JP2017021001A - Liquid level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize downsizing of an electrode unit disposed in a container in a liquid level detector while enhancing the detection accuracy regarding the level of liquid stored within the container.SOLUTION: A liquid level detector 20 has an electrode unit 21 disposed within an oil pan. The electrode unit 21 has an electrode cluster 31 in which multiple electrodes are assembled, and a common electrode 32 that generates electrostatic capacitance between itself and the electrode cluster 31. The electrode cluster 31 has multiple detection electrodes 34a and 34b and an electrode support 35 supporting these detection electrodes 34a and 34b. The front side detection electrode 34a is disposed on the front face of the electrode support 35 and the rear side detection electrode 34b is disposed on the rear face of the electrode support 35. In the electrode cluster 31, multiple detection electrode groups 39 each having paired the detection electrodes 34a and 34b are arrayed in a vertical direction, and a control unit 26 calculates a liquid level L by detecting the electrostatic capacitance of each detection electrode group 39.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid level detection device that detects a liquid level position of a liquid stored in a container.

  2. Description of the Related Art Conventionally, a liquid level detection device that detects a liquid level position of a liquid stored in a container is known. For example, the liquid level detection device described in Patent Document 1 includes a plurality of sensor electrodes arranged in the height direction of the container, and a first ground electrode extending along the vertical direction. In this liquid level detection device, both the sensor electrode and the first ground electrode are provided on the surface of the substrate portion, and the liquid level is determined based on the capacitance between the sensor electrode and the first ground electrode. Is to be detected. Further, the liquid level detection device has a second ground electrode extending in the vertical direction like the first ground electrode, and the second ground electrode is provided on the back surface of the substrate portion. A wiring connected to the sensor electrode is provided inside the board part, and this wiring is shielded by each ground electrode, preventing changes in wiring capacity due to changes in the liquid level position. It has come to be.

JP 2013-190379 A

  However, in the configuration in which the sensor electrode and the first ground electrode are provided on the surface of the substrate portion and the second ground electrode is provided on the back surface of the substrate portion, although the wiring inside the substrate portion can be shielded by the two ground electrodes, The installation space for the sensor electrode is limited. In this case, since the facing area between the sensor electrode and the first ground electrode is limited, there is room for improvement with respect to improving the detection accuracy of the liquid level.

  The present invention has been made in view of the above problems, and an object thereof is to provide a liquid level position of a liquid stored in the container while increasing the detection accuracy by the liquid level detection device. The purpose is to reduce the size of the electrode unit.

  The technical means of the invention for achieving the object will be described below. The reference numerals in parentheses described in the scope of claims and this column disclosing technical means of the invention indicate the correspondence with the specific means described in the embodiment described in detail later. It is not intended to limit the technical scope of the invention.

The invention disclosed in order to solve the above problems
An electrode unit (21) provided inside the container (12, 13);
A liquid level detection unit (22, 23, 26) for detecting the liquid level position (L) of the liquid stored in the container by detecting capacitance from the electrode unit;
With
The electrode unit
A plurality of detection electrodes (34a, 34b) arranged in the height direction of the container;
A storage electrode (32) facing each of the plurality of detection electrodes in a state of storing the plurality of detection electrodes;
An electrode support (35) supporting a plurality of detection electrodes in the internal space (32a) of the storage electrode;
Have
In the plurality of detection electrodes, a plurality of detection electrode groups (39) having at least two detection electrodes facing each other across the electrode support portion are arranged in the height direction of the container,
The liquid level detector
The liquid level position is detected based on the capacitance between the plurality of detection electrodes and the storage electrode.

  According to the present invention, since a plurality of detection electrode groups are arranged inside the storage electrode, even if bubbles or liquid level fluctuations occur in the container, these bubble or liquid level fluctuations are detected. It is difficult to reach the electrode group. For this reason, it can suppress that the detection precision of a liquid level position falls by bubble and the fluctuation | variation of a liquid level. That is, the detection accuracy by the liquid level detection device can be increased.

  In addition, in the detection electrode group, since at least two detection electrodes are arranged side by side, it is not necessary to arrange all the detection electrodes vertically. For this reason, the height dimension of the space for installing a set of detection electrodes can be reduced. Also, for example, unlike the configuration in which the detection electrodes of the detection electrode group are arranged side by side on one side of the electrode support portion, the size and shape of each detection electrode are limited by the interference of a pair of detection electrodes. You can avoid that. Accordingly, it is possible to reduce the size of the electrode unit while maintaining the facing area between each detection electrode and the storage electrode of the detection electrode group so that the capacitance can be appropriately secured.

1 is a cross-sectional view of an engine for illustrating an overall configuration of a liquid level detection device according to a first embodiment. The exploded perspective view of an electrode unit. FIG. 3 is a transverse sectional view of the electrode unit, taken along the line III-III in FIG. 1. The longitudinal cross-sectional view of an electrode unit and the figure which shows the electrical structure of a liquid level detection apparatus. The figure which shows the 1st state of a unit switching part. The figure which shows the 2nd state of a unit switching part. The figure which shows the Nth state of a unit switching part. The figure which shows the equivalent circuit of an electrode unit. The flowchart which shows the procedure of a liquid level detection process. The figure for demonstrating the manufacturing procedure of an electrode assembly. The perspective view of the front side of the electrode assembly in 2nd embodiment, and the perspective view of a back side. The front view of the surface and back surface of the electrode assembly in 3rd embodiment. The front view of the surface of a front side insulation part, and a back surface. The figure for demonstrating the manufacturing procedure of an electrode assembly. The front view of the electrode unit in 4th embodiment. FIG. 16 is a transverse sectional view of the electrode unit, taken along line XVI-XVI in FIG. 15. It is a longitudinal cross-sectional view of an electrode unit, Comprising: The XVII-XVII sectional view taken on the line of FIG. The perspective view of the electrode unit in 5th embodiment. The cross-sectional view of an electrode unit. The disassembled perspective part of the electrode unit containing the fragmentary broken view of a common electrode. The perspective view of the electrode unit in 6th embodiment. The cross-sectional view of the intermediate part of an electrode assembly and a common electrode. The figure which looked at the electrode assembly and the common electrode from the bottom. The exploded perspective view of an electrode unit and the figure which shows the electrical structure of a liquid level detection apparatus. The longitudinal cross-sectional view of the electrode unit in 7th embodiment. The exploded longitudinal cross-sectional view of the electrode unit containing the partial broken view of a common electrode. The cross-sectional view of the electrode unit in the eighth embodiment. The exploded perspective view of an electrode unit and the figure which shows the electrical structure of a liquid level detection apparatus. The front view of the electrode assembly in 10th embodiment. The figure which shows the electrical structure of an electrode assembly and a unit switching part. The figure which shows the electrical structure of the electrode assembly and unit electrode part in 11th embodiment. The flowchart which shows the procedure of a liquid level detection process. The figure which shows the surface of the another electrode assembly, a back surface, and a side surface. The longitudinal cross-sectional view of another electrode unit. The longitudinal cross-sectional view of another common electrode. The front view of another common electrode. The longitudinal cross-sectional view of another electrode unit.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. In addition, not only combinations of configurations explicitly described in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if they are not explicitly specified unless there is a problem with the combination. .

(First embodiment)
As shown in FIG. 1, an engine 10 mounted on a vehicle has a cylinder head 11, a crankcase 12, and an oil pan 13, and is an internal combustion engine that serves as a driving power source for the vehicle. The cylinder head 11 has a cylinder 11a as its internal space, and the piston 14 slides in the vertical direction in the cylinder 11a. The piston 14 is connected to the crankshaft 16 via a connecting rod 15.

  The cylinder head 11, the crankcase 12 and the oil pan 13 form a main body of the engine 10, and oil 18 such as engine oil is stored in the oil pan 13. The oil 18 is a lubricating oil that lubricates the sliding portion of the piston 14, the connecting rod 15 and the bearing portion of the crankshaft 16, and corresponds to the liquid stored in the oil pan 13 as a container. In the engine 10, it is also assumed that the liquid level L, which is the liquid level position of the oil 18, rises to a position higher than the upper end of the oil pan 13. In this case, a container is constituted by the crankcase 12 in addition to the oil pan 13. The liquid level L can also be referred to as a liquid level or a liquid level.

  The engine 10 is provided with a liquid level detection device 20 that detects the liquid level h of the oil 18 based on the capacitance. The liquid level detection device 20 includes an electrode unit 21 provided in the oil pan 13, a unit switching unit 22 that switches the electrical state of the electrode unit 21, and a static for detecting the capacitance of the electrode unit 21. It has a capacitance detection unit 23, an arithmetic processing unit 24 that calculates the liquid level L based on the detection result of the capacitance detection unit 23, and a switching processing unit 25 that controls the operation of the unit switching unit 22. Yes.

  The electrical configuration of the liquid level detection device 20 will be briefly described. In the liquid level detection device 20, as a circuit configuration, a capacitance detection unit 23 is connected to the electrode unit 21 via a unit switching unit 22. The arithmetic processing unit 24 is connected to the capacitance detection unit 23, and a detection signal from the capacitance detection unit 23 is input to the arithmetic processing unit 24. The switching processing unit 25 is connected to the unit switching unit 22, and a command signal is input from the switching processing unit 25 to the unit switching unit 22. The liquid level detection device 20 includes a control device 26 configured to include a control unit such as a microcomputer, and the arithmetic processing unit 24 and the switching processing unit 25 are included in the control device 26. The unit switching unit 22, the capacitance detecting unit 23, and the control device 26 constitute a liquid level detecting unit that detects the liquid level L.

  The electrode unit 21 has a vertically long shape as a whole, and extends in the height direction of the oil pan 13, that is, in the vertical direction. For this reason, when the storage amount of the oil 18 increases or decreases, the liquid level L of the oil 18 is displaced in the longitudinal direction of the electrode unit 21. The electrode unit 21 is fixed to the crankcase 12 and the oil pan 13 via a bracket.

  As shown in FIGS. 2 and 3, the electrode unit 21 includes an electrode assembly 31 in which a plurality of electrodes are aggregated, and a common electrode 32 that generates a capacitance between the electrode assembly 31. . The electrode assembly 31 has a vertically long shape as a whole, and the common electrode 32 has a vertically long rectangular tube shape. The common electrode 32 is formed of a metal material such as stainless steel having oil resistance, and has a flat shape in which the width dimension is larger than the depth dimension. The electrode assembly 31 is accommodated in the internal space 32 a of the common electrode 32 with the width direction thereof coinciding with the width direction of the common electrode 32. The length dimension of the common electrode 32 is larger than the length dimension of the electrode assembly 31, and the electrode assembly 31 does not protrude upward or downward from the common electrode 32.

  The electrode assembly 31 includes a plurality of detection electrodes 34a and 34b arranged along the longitudinal direction of the common electrode 32, and an electrode support 35 that supports the detection electrodes 34a and 34b. The electrode support 35 is in the form of a vertically long rectangular plate as a whole, and in this embodiment, the surface of the electrode support 35 on which the front-side detection electrode 34a is provided among the detection electrodes 34a and 34b is the surface. The plate surface on which the back side detection electrode 34b is provided is referred to as a back surface. Like the common electrode 32, the detection electrodes 34a and 34b are made of a metal material such as stainless steel having oil resistance, and have a horizontally long rectangular plate shape. The detection electrodes 34a and 34b are arranged at equal intervals and extend in parallel to each other.

  The width dimensions of the detection electrodes 34 a and 34 b are smaller than the width dimension of the electrode support 35, and the detection electrodes 34 a and 34 b are arranged at the center position in the width direction of the electrode support 35. In this case, the electrode support 35 protrudes laterally from the detection electrodes 34a and 34b in the width direction.

  The electrode support 35 includes a pair of insulating portions 36a and 36b facing each other, and an intermediate electrode 37 provided between the insulating portions 36a and 36b. The insulating portions 36a and 36b are formed in a rectangular plate shape by an insulating material such as a resin having oil resistance. Similar to the common electrode 32 and the detection electrodes 34a and 34b, the intermediate electrode 37 is formed of a metal material such as stainless steel having oil resistance, and has the same size and shape as the insulating portions 36a and 36b. . The insulating portions 36a and 36b and the intermediate electrode 37 are overlapped with each other on the plate surfaces, and the outer plate surfaces of the insulating portions 36a and 36b serve as attachment surfaces for the detection electrodes 34a and 34b. The intermediate electrode 37 faces the detection electrodes 34a and 34b with the insulating portions 36a and 36b interposed therebetween.

  The common electrode 32 has a pair of width plate portions 32b and 32c extending in the width direction and a pair of depth plate portions 32d extending in the depth direction. Of the pair of width plate portions 32b and 32c, the front side width plate portion 32b provided on the front side faces the front side detection electrode 34a, and the back side width plate portion 32c provided on the back side faces the back side detection electrode 34b. ing.

  In the electrode unit 21, the width plate portions 32b and 32c, the detection electrodes 34a and 34b, and the intermediate electrode 37 extend in parallel with each other. The front-side detection electrode 34a is disposed between the front-side width plate portion 32b and the intermediate electrode 37, and capacitance is generated between the front-side detection electrode 34a, the front-side width plate portion 32b, and the intermediate electrode 37, respectively. It has become easier. Further, the back side detection electrode 34 b is disposed between the back side width plate portion 32 c and the intermediate electrode 37, and a capacitance is provided between the back side detection electrode 34 b, the back side width plate portion 32 c and the intermediate electrode 37. Is prone to occur.

  The electrode assembly 31 is disposed at the center position in both the thickness direction and the width direction of the common electrode 32. The separation distance D1 between the front side detection electrode 34a and the front side width plate portion 32b is the same as the separation distance D2 between the back side detection electrode 34b and the back side width plate portion 32c. The separation distances D1 and D2 are substantially the same as the separation distance D3 between the depth plate portion 32d and the detection electrodes 34a and 34b. In this case, since the separation distance between the electrode assembly 31 and the width plate portions 32b and 32c is appropriately ensured, the electrode assembly 31 and the width plate portion 32b, It is difficult for the capillary phenomenon of the oil 18 to occur between 32c. For this reason, generation | occurrence | production of the liquid level separation that the liquid level L differs by the inner side and the outer side of the common electrode 32 is suppressed. The separation distances D1 to D3 can also be referred to as gaps.

  Incidentally, the separation distances D1 and D2 may be larger than the separation distance D3. In this case, the effect of suppressing capillary action can be enhanced.

  As shown in FIG. 4, in the electrode unit 21, a detection electrode group 39 is configured by a pair of detection electrodes 34 a and 34 b that are opposed to each other with the electrode support 35 sandwiched among the plurality of detection electrodes 34 a and 34 b. N detection electrode groups 39 are arranged along the longitudinal direction of the electrode support 35, and the center lines O of the detection electrode groups 39 are arranged at equal intervals. In one detection electrode group 39, the front-side detection electrode 34a and the back-side detection electrode 34b are arranged at the same height position, and the center line O passes through the center portions of the detection electrodes 34a and 34b. The pair of detection electrodes 34 a and 34 b is electrically connected to each detection electrode group 39 by an electric path.

  When the longitudinal direction of the electrode unit 21 is the vertical direction, in the detection electrode group 39 adjacent to the upper and lower sides, the detection electrodes 34a and 34b of the upper detection electrode group 39 are connected to the detection electrodes 34a and 34a of the lower detection electrode group 39, respectively. It is in a position higher than 34b. In this case, a gap region SP in which none of the detection electrodes 34a and 34b exists is provided between the detection electrode groups 39 adjacent in the vertical direction. This gap region SP has a front side gap between the front side detection electrodes 34a adjacent to each other in the vertical direction and a back side gap between the back side detection electrodes 34b adjacent to each other in the vertical direction. It arrange | positions in the position which overlapped on both sides of the support body 35. FIG.

  The electrical path connecting the detection electrodes 34a and 34b includes electrode lines 41a and 41b as electrical wiring. The electrode line 41a is a front side electrode line 41a connected to the front side detection electrode 34a, and the electrode line 41b is a back side electrode line 41b connected to the back side detection electrode 34b.

  The common electrode 32 corresponds to a storage electrode that stores a plurality of detection electrodes 34a and 34b, the internal space 32a of the common electrode 32 corresponds to a storage space, the electrode support 35 corresponds to an electrode support portion, and the detection electrode. Reference numerals 34a and 34b correspond to detection electrodes opposed to the storage electrodes. In the electrode support 35, the intermediate electrode 37 corresponds to a support electrode, and the insulating portions 36a and 36b correspond to a support insulating portion.

  As shown in FIGS. 2 and 3, connection holes 42a and 42b for connecting the electrode wires 41a and 41b are formed in the detection electrodes 34a and 34b, and the electrode wires 41a are formed in the connection holes 42a and 42b. , 41b, a connector member 43 is inserted. Similarly to the detection electrodes 34a and 34b, the connector member 43 is made of a metal material such as stainless steel having oil resistance, and electrically connects the detection electrodes 34a and 34b and the electrode wires 41a and 41b.

  The connection hole 42a is a front side connection hole 42a arranged in the front side detection electrode 34a, and the connection hole 42b is a back side connection hole 42b arranged in the back side detection electrode 34b. One connection hole 42a, 42b is formed in each of the plurality of detection electrodes 34a, 34b, and these connection holes 42a, 42b overlap each other in the vertical direction by being shifted in the width direction of the electrode support 35. It is arranged at a position where it is not possible.

  For example, the front side detection electrode 34a will be described. In the lowermost front detection electrode 34a, a front connection hole 42a is arranged at a position near one end, and in the uppermost front detection electrode 34a, at a position near the end on the opposite side to the lowermost front detection electrode 34a. The front side connection hole 42a is arranged. In each front side detection electrode 34a at the intermediate position, the front side connection hole 42a is located closer to the end opposite to the lowermost front side detection electrode 34a as the front side detection electrode 34a is closer to the uppermost front side detection electrode 34a. Has been placed.

  The front side electrode wire 41a is disposed inside the front side insulating portion 36a, and the back side electrode wire 41b is disposed inside the back side insulating portion 36b. In this case, the electrode wires 41a and 41b are electrically insulated from the detection electrodes 34a and 34b and the intermediate electrode 37 by the insulating portions 36a and 36b, respectively. The connector member 43 is connected to the electrode wires 41a and 41b in a state where the connector member 43 enters the insulating portions 36a and 36b from the connection holes 42a and 42b of the detection electrodes 34a and 34b.

  The electrode lines 41a and 41b are disposed between the detection electrodes 34a and 34b and the intermediate electrode 37. In this case, the shielding effect by the detection electrodes 34a and 34b and the intermediate electrode 37 is imparted to the electrode lines 41a and 41b, thereby suppressing the occurrence of noise in the voltage applied to the electrode lines 41a and 41b. .

  Next, the electrical configuration of the liquid level detection device 20 will be described with reference to FIG.

  In the liquid level detection device 20, it is possible to individually detect the capacitance for each of the plurality of detection electrode groups 39. The capacitance detection unit 23 includes a DC power supply unit 23a that applies a DC voltage between the detection electrode group 39 and the common electrode 32, a resistor 23b connected in series to the DC power supply unit 23a, and these DC power supply units. And a voltage measuring unit 23c connected to the resistor 23b.

  The unit switching part 22 has a negative connection part 22a in which the common electrode 32 is connected to the negative electrode side of the DC power supply part 23a, and a switch part 22b for switching the connection state of the DC power supply part 23a to the detection electrode group 39. The negative connection part 22a is an electrical path, and holds the common electrode 32 and the DC power supply part 23a in a conductive state. The switch unit 22b can shift between a positive state in which the detection electrode group 39 is connected to the positive electrode side of the DC power supply unit 23a and a negative state in which the detection electrode group 39 is connected to the negative electrode side, and is provided for each detection electrode group 39. In this case, the same number N of switch parts 22b as the detection electrode group 39 are provided, and a pair of detection electrodes 34a and 34b are connected to one switch part 22b. The positive state corresponds to the power supply side state, and the negative state corresponds to the storage side state.

  Here, the common electrode 32 and the intermediate electrode 37 are grounded by being connected to the ground GND. For this reason, the negative electrode side of the DC power supply unit 23a is grounded through the negative connection unit 22a. The detection electrode group 39 is grounded when the corresponding switch portion 22b is in a negative state.

  The switching processing unit 25 can individually operate each switch unit 22b of the unit switching unit 22 by outputting a command signal. For example, when a voltage is applied from the DC power supply unit 23a to only the kth detection electrode group 39 from the bottom among the plurality of detection electrode groups 39, the switch unit 22b corresponding to the kth detection electrode group 39 is provided. Are shifted to the positive state, while N−1 switch units 22b corresponding to the other N−1 detection electrode groups 39 are shifted to the negative state. 4 to 7, the arrangement order from the left of the plurality of switch portions 22 b is illustrated in correspondence with the arrangement order from the bottom of the detection electrode group 39.

  As shown in FIG. 5, when a voltage is applied only to the lowest-order detection electrode group 39, which is the first stage, only the leftmost switch unit 22b is shifted to the positive state, so that the unit switching unit 22 Transition to one state. As shown in FIG. 6, when a voltage is applied only to the detection electrode group 39 in the second stage, only the second switch unit 22b from the left is shifted to the positive state, so that the unit switching unit 22 is in the second state. Migrate to As shown in FIG. 7, when a voltage is applied only to the uppermost detection electrode group 39 that is the Nth stage, only the rightmost switch unit 22b that is Nth from the left is shifted to the positive state. The unit switching unit 22 shifts to the Nth state.

  In FIG. 8, the unit switching unit 22 is in the kth state. In this case, a voltage is applied only to the detection electrode group 39 at the k-th stage, and a capacitance is generated between the detection electrode group 39 and the common electrode 32 and the intermediate electrode 37. In the equivalent circuit in this case, virtual capacitors C1 and C2 exist between the k-th detection electrode group 39, the common electrode 32, and the intermediate electrode 37. Further, as described above, since the common electrode 32 and the intermediate electrode 37 are grounded to the ground GND, the voltages of the common electrode 32 and the intermediate electrode 37 are stabilized at the zero level, and the measurement value of the voltage measurement unit 23c is not affected by noise. Is less likely to occur.

  In this case, as described above, the detection electrode groups 39 at stages other than the k-th stage are also grounded to the ground GND, and between the detection electrode group 39 at the k-th stage and the detection electrode group 39 at the other stage. Virtual capacitors C3 and C4 are present. The k-th detection electrode group 39 is further apart from the fact that a virtual capacitor C3 exists between the detection electrode groups 39 of the (k + 1) -th stage and the (k-1) -th stage adjacent to each other in the upper and lower sides. A virtual capacitor C4 also exists between the detection electrode group 39 such as the (k-2) th stage.

  The voltage measuring unit 23c measures the charging voltage of the virtual capacitors C1 to C4 as the measured value V, and the relationship between the measured value V, the combined capacitance C of the virtual capacitors C1 to C4, and the charge Q is as follows. V = Q / C. Here, when the virtual capacitors C1 to C4 are connected in parallel to the DC power supply unit 23a and the virtual capacitor C1 of the common electrode 32 is sufficiently larger than the other virtual capacitors C2 to C4, the combined electrostatic capacitance The capacitance C is smaller than the virtual capacitor C1. In this case, by connecting the detection electrode group 39 and the intermediate electrode 37 at stages other than the k-th stage to the common electrode 32, the measurement value V of the voltage measurement unit 23c is amplified, and as a result, synthesized based on the measurement value V. The calculation accuracy when calculating the capacitance C is improved.

  The control device 26 executes a liquid level detection process for detecting the liquid level L of the oil 18. In the liquid level detection process, the capacitance is individually detected for each of the detection electrode groups 39, and the liquid level L is obtained by comparing these capacitances. The control device 26 repeatedly executes the liquid level detection process at predetermined intervals.

  In FIG. 9, in step S <b> 101, the number k of stages indicating which of the plurality of detection electrode groups 39 is to be detected for capacitance is set to zero. In step S102, the value of the stage number k is incremented.

  In step S103, a voltage application process is performed on the detection electrode group 39 in the k-th stage. In this process, by outputting a command signal from the switching processing unit 25, the switch unit 22b corresponding to the k-th detection electrode group 39 is shifted to the positive state. The kth detection electrode group 39 corresponds to the first electrode group.

  In step S104, the grounding process is performed on all the detection electrode groups 39 in stages other than the k-th stage. In this processing, by outputting a command signal from the switching processing unit 25, all the switch units 22b are shifted to the negative state corresponding to the detection electrode groups 39 in the stages other than the k-th stage. Note that the detection electrode group 39 at a stage other than the k-th stage corresponds to the second electrode group.

  The control device 26 has a function of executing steps S103 and S104, and this function corresponds to a transition unit. In particular, the function of executing step S103 corresponds to the first transition unit, and the function of executing step S104 corresponds to the second transition unit.

  In step S105, the arithmetic processing unit 24 calculates the combined capacitance as the capacitance Ck for the k-th detection electrode group 39 as a target. Here, the capacitance generated between the detection electrode group 39 at the k-th stage and the detection electrode group 39 at the other stage, the common electrode 32, and the intermediate electrode 37 based on the measurement result of the voltage measurement unit 23c. calculate.

  In step S106, the arithmetic processing unit 24 determines whether or not the capacitance Ck is equal to or greater than a predetermined threshold Th. As the threshold Th, a calculated value calculated from the dielectric constant ε of the oil 18 or an estimated value estimated based on a database is used. If the capacitance Ck is equal to or greater than the threshold value Th, the process proceeds to step S107, and the processing unit 24 performs in-liquid processing to indicate that the k-th detection electrode group 39 is in the liquid. To remember. As the case where the k-th detection electrode group 39 is in the liquid, the entire detection electrode group 39 is immersed in the oil 18, or at least the lower end portion of the detection electrode group 39 is immersed in the oil 18. Can be mentioned.

  When the electrostatic capacitance Ck is not equal to or greater than the threshold Th, the process proceeds to step S108, and the arithmetic processing unit 24 performs air processing to store in the storage unit that the k-th detection electrode group 39 is in air. The case where the k-th detection electrode group 39 is in the air includes a case where the detection electrode group 39 is not immersed in the oil 18.

  After the state of the k-th detection electrode group 39 is stored in steps S107 and S108, the process proceeds to step S109, where it is determined whether or not the number k of stages is smaller than the number N of detection electrode groups 39. When the number of stages k is smaller than the number N, it is determined that the state determination for all the detection electrode groups 39 has not ended, and the process returns to step S102. As described above, in step S102, the number of stages k is incremented, so that the state determination is performed by the processing of steps S103 to S108 for the detection electrode group 39 that is one higher than the previous time.

  If it is determined in step S109 that the number of stages k is equal to or greater than the number N, it is determined that the state determination has been completed for all the detection electrode groups 39, and the process proceeds to step S110. In step S110, the arithmetic processing unit 24 calculates the height position of the liquid level L. Here, the number of stages of the uppermost detection electrode group 39 among the detection electrode groups 39 in the liquid is determined based on the stored data in the storage unit.

  Next, the manufacturing procedure of the electrode assembly 31 will be described.

  First, for the purpose of collectively creating the detection electrodes 34a and 34b of the plurality of electrode assemblies 31, as shown in FIG. 10, a plurality of insulating plate members 45 used as the insulating portions 36a and 36b are respectively connected to the upper ends and Align the bottom edge and place it in parallel on the workbench. A plurality of small holes 46 used as connection holes 42a and 42b are formed in the insulating plate material 45 in advance. Then, a plurality of stainless steel metal foil tapes 47 used as the detection electrodes 34 a and 34 b are attached to one side of these insulating plate members 45 so as to extend over the plurality of insulating plate members 45. Thereafter, the metal foil tape 47 is cut or cut at the boundary portion between adjacent insulating plate members 45, thereby forming the detection electrodes 34 a and 34 b with the metal foil tape 47. In this case, the insulating plate material 45 is used as the insulating portions 36a and 36b.

  In the insulating portions 36a and 36b, electrode lines 41a and 41b are formed on the surface opposite to the detection electrodes 34a and 34b by etching. Thereafter, by inserting the connector member 43 into the small hole 46, the detection electrodes 34a, 34b and the electrode wires 41a, 41b are electrically connected. In this case, the small holes 46 are used as the connection holes 42a and 42b.

  Note that FIG. 10 is merely an example of the manufacturing process of the electrode assembly 31, and therefore the number and shape of the detection electrodes 34a and 34b are different from those in FIG.

  Then, the electrode assembly 31 is manufactured by attaching the insulating portions 36 a and 36 b to the front side and the back side of the intermediate electrode 37. In the electrode assembly 31, insulating portions 36a and 36b and detection electrodes 34a and 34b are formed by the insulating plate material 45 and the tape piece. In this case, since the detection electrodes 34a and 34b are formed of the metal foil tape 47, the usage fee of the etching solution can be reduced as compared with the case where the detection electrodes 34a and 34b are formed by etching, for example. For this reason, the burden to the environment at the time of manufacturing the electrode assembly 31 can be reduced. Further, the thickness dimension of the detection electrodes 34a and 34b can be increased as compared with the etching process, and the strong detection electrodes 34a and 34b can be manufactured. Furthermore, since the upper end surface and the lower end surface of the detection electrodes 34a and 34b are formed as cutting surfaces by the side end surfaces of the metal foil tape 47, it is not necessary to perform etching to form the cutting surfaces.

  In place of the metal foil tape 47, a plurality of rows of stainless steel metal plates may be attached to these insulating plate members 45 so as to pass over the plurality of insulating plate members 45. Even in this case, the detection electrodes 34a and 34b can be formed by cutting each metal plate.

  The operational effects of the first embodiment described so far will be described below.

  According to the first embodiment, since the electrode assembly 31 is accommodated in the internal space 32a of the common electrode 32, even if bubbles are generated in the oil 18, the bubbles contact the detection electrodes 34a and 34b. It has become difficult. Further, even if the liquid level of the oil 18 is undulating, the wave is less likely to contact the detection electrodes 34a and 34b. Therefore, the common electrode 32 can prevent the detection accuracy of the liquid level L from being lowered due to bubbles or waves. In addition, since the electrode support 35 is disposed between the front side detection electrode 34a and the back side detection electrode 34b, the detection electrodes 34a and 34b interfere with each other without arranging the detection electrodes 34a and 34b vertically. Can be avoided. In this case, it is possible to reduce the size of the electrode unit 21 while increasing the degree of freedom regarding the size and shape of the detection electrodes 34a and 34b.

  According to the first embodiment, since the common electrode 32 and the intermediate electrode 37 are arranged with respect to the detection electrodes 34a and 34b, for example, the measurement by the voltage measuring unit 23c is compared with a configuration in which the intermediate electrode 37 is not arranged. The value is amplified. For this reason, the detection accuracy at the time of detecting an electrostatic capacitance and the liquid level L using a measured value can be improved. In addition, since the intermediate electrode 37 is included in the electrode support 35, the support strength of the detection electrodes 34a and 34b by the electrode support 35 can be increased. Therefore, it is possible to suppress the detection accuracy of the liquid level L from being lowered due to the electrode support 35 being bent and the separation distances D1 to D3 between the common electrode 32 and the detection electrodes 34a and 34b unintentionally changing.

  According to the first embodiment, the electrode wires 41 a and 41 b are arranged inside the insulating portions 36 a and 36 b in the electrode support 35. In this case, it is not necessary to separately arrange a dedicated member for insulating the detection electrodes 34a and 34b and the intermediate electrode 37 and a dedicated member for insulating the electrode wires 41a and 41b, so the electrode support 35 is manufactured. It is possible to reduce the material cost.

  According to the first embodiment, since the switching processing unit 25 can individually switch the states of the plurality of switch units 22b, the voltage of the DC power supply unit 23a is individually applied to each of the detection electrodes 34a and 34b. be able to. For this reason, it becomes easy to detect a capacitance for each of the detection electrodes 34a and 34b.

  According to the first embodiment, when the unit switching unit 22 is in the k-th state, the detection electrode groups 39 other than the k-th stage are electrically connected to the common electrode 32. The measurement value of the voltage measurement unit 23c is amplified. For this reason, the detection accuracy at the time of detecting an electrostatic capacitance and the liquid level L using a measured value can be improved.

  According to the first embodiment, since the common electrode 32 is grounded to the ground GND, the voltage of the common electrode 32 is easily stabilized at the zero level. In this case, the detection accuracy can be increased when the capacitance is detected using the measurement value of the voltage measurement unit 23c. Further, since the detection electrode group 39 other than the intermediate electrode 37 and the k-th stage is also grounded to the ground GND, the measurement value of the voltage measuring unit 23c is unstable due to noise or the like by the intermediate electrode 37 or the detection electrode group 39. Can be suppressed.

  According to the first embodiment, in the adjacent detection electrode groups 39, since the detection electrodes 34a and 34b are separated from each other in the vertical direction, the liquid level L straddles two or more detection electrode groups 39. Is less likely to occur. For this reason, the detection accuracy of the liquid level L can be increased by detecting the capacitance for each detection electrode group 39.

  According to the first embodiment, since the electrode assembly 31 is separated from the common electrode 32 toward the inner peripheral side, the liquid level L is suppressed from becoming nonuniform around the electrode assembly 31. Further, even if bubbles are present in the internal space 32 a of the common electrode 32, it is possible to suppress the presence of the bubbles from becoming uneven around the electrode assembly 31. By these things, the detection accuracy of the liquid level L can be improved using the electrode unit 21.

(Second embodiment)
In the first embodiment, the gap region SP is provided between the detection electrode groups 39 that are vertically adjacent to each other. However, in the second embodiment, the gap region SP is not provided. In the present embodiment, description will be made focusing on differences from the first embodiment.

  As shown in FIG. 11, in the electrode assembly 31, the center lines Oa and Ob of the detection electrodes 34a and 34b are arranged at equal intervals, and the distance between the center lines Ob of the front detection electrode 34a and the back detection electrode 34b. The interval between the center lines Ob is the same. On the other hand, these center lines Oa and Ob are arranged at different height positions. Specifically, the center line Oa on the front side is at the center position of the center line Ob on the back side adjacent to each other in the vertical direction. In this case, the front-side center line Oa is at a height position between the upper and lower adjacent back-side detection electrodes 34b, and the back-side center line Ob is at a height position between the upper-and-lower adjacent front-side detection electrodes 34a. . The distance between the center line Oa and the center line Ob adjacent to each other in the vertical direction is 2 / p, where the distance between the center lines Oa and the distance between the center lines Ob are defined as a pitch p.

  In the detection electrode group 39, the center line Oa of the front side detection electrode 34a is arranged at a position higher than the center line Ob of the back side detection electrode 34b, the front side detection electrode 34a corresponds to the upper side detection electrode, and the back side detection electrode 34b. Corresponds to the lower detection electrode. The front side detection electrode 34a extends upward from the back side detection electrode 34b, and the back side detection electrode 34b extends downward from the front side detection electrode 34a. In this case, the upper part of the front detection electrode 34a of the k-th detection electrode group 39 is opposed to the lower part of the rear detection electrode 34b of the (k + 1) th detection electrode group 39 with the electrode support 35 interposed therebetween. Similarly, the lower part of the back-side detection electrode 34b of the k-th detection electrode group 39 is opposed to the upper part of the front-side detection electrode 34a of the k-1th detection electrode group 39 with the electrode support 35 interposed therebetween. Therefore, the water immersion state with respect to the liquid level L is different between the front side detection electrode 34a and the back side detection electrode 34b. In FIG. 11, the combination of the detection electrodes 34a and 34b is illustrated using hatching.

  The electrode support 35 is provided with electrode terminals 48 that are electrically connected to the detection electrodes 34a and 34b. The electrode terminal 48 is disposed above the electrode support 35 on each of the front and back surfaces of the electrode support 35, and is connected to the detection electrodes 34a and 34b via the electrode wires 41a and 41b. Among the plurality of electrode terminals 48, the electrode terminal 48 connected to the front side detection electrode 34 a is disposed on the surface of the electrode support 35, and the electrode terminal 48 connected to the back side detection electrode 34 b is the back surface of the electrode support 35. Is arranged.

  In the present embodiment, unlike the first embodiment, the pair of detection electrodes 34a and 34b are connected to separate switch portions 22b, respectively. Therefore, the control device 26 can individually detect the flooded state of the pair of detection electrodes 34 a and 34 b for the detection electrode group 39. In addition, eight detection electrodes 34a and 34b are arranged one above the other, and the height positions of the plurality of front side center lines Oa are referred to as heights L1 to L8 in order from the bottom, and the heights of the plurality of back side center lines Ob. The positions are referred to as heights L0.5 to L7.5 in order from the bottom.

  For example, when the liquid level L is between the heights L3.5 and L4, there is a high possibility that the detection electrodes 34a and 34b of the detection electrode groups 39 in the fourth and lower stages are all immersed in the oil 18. Here, when the liquid level L is lower than the height L3.5, the back side detection electrode 34b of the fourth detection electrode group 39 is immersed in the oil 18, while the front side detection electrode 34a is oil. There is a high possibility that it is not immersed in 18. Further, when the liquid level L is higher than the height L4, the detection electrodes 34a and 34b of the detection electrode group 39 in the fourth stage are both likely to be immersed in the oil 18, and in addition, 5 There is a high possibility that the back side detection electrode 34 b of the detection electrode group 39 at the stage is also immersed in the oil 18. From the above, the control device 26 calculates that the liquid level L is between the heights L3.5 and L4.

  In the configuration in which each of the eight front-side detection electrodes 34a and the back-side detection electrodes 34b are at different height positions by 2 / p as in this embodiment, for example, the detection electrodes 34a and 34b are arranged at the same height position. Compared to the above configuration, the resolution of the liquid level L is set to 16, which is twice. For the detection electrodes 34a and 34b, the ratio of the height dimension to the width dimension is set to approximately 1: 2. In contrast, for example, in a configuration in which the back side detection electrode 34b is not provided, in order to set the resolution to 16 without increasing the size of the electrode support 35, it is necessary to arrange the 16 front side detection electrodes 34a vertically. is there. In this case, it is necessary to set the ratio of the height dimension to the width dimension to a value close to 1: 4 for the front side detection electrode 34a, and the liquid level L is detected by the smaller height dimension of the front side detection electrode 34a. Accuracy will be reduced. Further, the capacitance of the front electrode line 41a is likely to be included as an error in the detection result of the liquid level L.

  The electrode wires 41a and 41b are arranged not on the positions overlapping the detection electrodes 34a and 34b in the thickness direction of the electrode assembly 31 but on the side positions of the detection electrodes 34a and 34b in the width direction of the electrode assembly 31. In this case, the connection holes 42a and 42b are arranged at positions near either one of the both side ends of the detection electrodes 34a and 34b.

  According to the second embodiment, since the front side detection electrode 34a and the back side detection electrode 34b are not connected by an electric path, the liquid level L is detected based on the electrostatic capacitance of each of the detection electrodes 34a and 34b. can do. Moreover, since the height positions of the front side detection electrode 34a and the back side detection electrode 34b are different, the capacitance of one detection electrode group 39 can be used to detect the liquid level L in three stages. Thereby, the decomposition degree at the time of detecting the liquid level L can be raised.

(Third embodiment)
In the second embodiment, one detection electrode group 39 has one front side detection electrode 34a and one back side detection electrode 34b. However, in the third embodiment, one detection electrode group 39 has one front side detection electrode 34a. And a plurality of back side detection electrodes 34b. In the present embodiment, description will be made focusing on differences from the second embodiment.

  As shown in FIG. 12, two front side detection electrodes 34a and two back side detection electrodes 34b are arranged side by side. One of the two front side detection electrodes 34a is arranged at a position higher than the other, and one of the two back side detection electrodes 34b is arranged at a position higher than the other. In this case, even the lower detection electrode 34a at the lower position is higher than the rear detection electrode 34b at the higher position. In this case, the capacitance of one detection electrode group 39 can be used for the detection of the liquid level L in seven stages based on the same principle as described in the second embodiment. Thereby, the decomposition degree at the time of detecting the liquid level L can further be raised.

  Similarly to the first embodiment, connection holes 42a and 42b are formed in the detection electrodes 34a and 34b, and electrode wires 41a and 41b are connected to the connection holes 42a and 42b. As shown in FIG. 13, in the front side insulating portion 36a, the front side connection holes 42a of the plurality of front side detection electrodes 34a arranged in a line in the vertical direction are arranged at positions that do not overlap with each other. In this case, the front electrode wires 41a are arranged side by side on the back surface side of the front insulating portion 36a.

  Next, the manufacturing procedure of the electrode assembly 31 of this embodiment will be described. As shown in FIG. 14, a plurality of insulating plate members 45 are arranged in parallel as in the first embodiment. Then, a stainless steel metal plate 49 used as the detection electrodes 34 a and 34 b is attached to these insulating plate members 45 in a state of straddling a pair of adjacent insulating plate members 45. Thereafter, the detection electrodes 34 a and 34 b are formed of the metal plate material 49 by cutting the metal plate material 49 at the boundary portion between the adjacent insulating plate materials 45. In this case, the insulating plate material 45 is used as the insulating portions 36a and 36b.

  Here, before attaching the metal plate member 49, the pair of insulating plate members 45 are arranged so that the positions of the upper end and the lower end of the pair are not aligned. Thereby, when one of the pair of insulating plate members 45 is used as the front side insulating portion 36a and the other is used as the back side insulating portion 36b, the height positions of the front side detecting electrode 34a and the back side detecting electrode 34b can be shifted. It becomes possible. When a plurality of insulating plate members 45 are arranged, a plurality of boundary portions between the insulating plate members 45 are arranged side by side, and a plurality of metal plate members 49 straddling each boundary portion are also arranged side by side. In this case, it is possible to shift the height positions of the two front-side detection electrodes 34a in, for example, one front-side insulating portion 36a by shifting the height positions of the side-by-side and adjacent metal plate members 49. This means that every other two types of electrode rows are arranged and manufactured simultaneously, and the arrangement work of arranging a plurality of metal plate members 49 can be facilitated.

  In the insulating plate material 45, small holes 46 are arranged in the detection electrodes 34a and 34b so as to be symmetric with respect to a center line extending in the longitudinal direction. In this case, the machining pattern when forming the small hole 46 using a tool such as a drill is simplified, and the amount of movement of the tool can be reduced.

(Fourth embodiment)
In the fourth embodiment, as shown in FIGS. 15 to 17, a plurality of slits 52 are provided in the common electrode 32. In the present embodiment, description will be made focusing on differences from the first embodiment.

  The slits 52 are horizontally long through holes penetrating the width plate portions 32b and 32c of the common electrode 32, and a plurality of slits 52 are arranged at predetermined intervals along the vertical direction in each of the width plate portions 32b and 32c. In the slit 52, the ceiling surface 52 a and the bottom surface 52 b extend parallel to each other in both the width direction and the depth direction of the common electrode 32. Each slit 52 of the front side width plate portion 32b and each slit 52 of the back side width plate portion 32c face each other with the internal space 32a and the electrode assembly 31 interposed therebetween. The slit 52 is disposed at the center position in the width direction of the common electrode 32.

  The width dimension of the slit 52 is larger than the width dimension of the detection electrodes 34 a and 34 b, while being smaller than the width dimension of the electrode support 35. In the present embodiment, the electrode support 35 is formed of one insulating plate material, and the front side detection electrode 34a is attached to the surface of the insulating plate material, and the back side detection electrode 34b is attached to the back surface.

  The slit 52 is disposed at a position that does not face the detection electrodes 34 a and 34 b in the depth direction of the common electrode 32. Specifically, the slit 52 is disposed at a height position between the detection electrodes 34a and 34b adjacent in the vertical direction. In this case, the slit 52 is disposed at a position lower than the lower ends of the upper detection electrodes 34a and 34b, and is disposed at a position higher than the upper ends of the lower detection electrodes 34a and 34b.

  In the electrode unit 21, unlike the first embodiment, the distances D1 and D2 between the detection electrodes 34a and 34b and the width plates 32b and 32c are the distance between the detection electrodes 34a and 34b and the depth plate 32d. It is smaller than D3. In this case, the separation distances D1 and D2 of the present embodiment are smaller than the separation distances D1 and D2 of the first embodiment. That is, the separation distance between the electrode assembly 31 and the width plate portions 32b and 32c is smaller in the present embodiment than in the first embodiment. The common electrode 32 has a bottom 32e. For this reason, the internal space 32a is not opened downward but opened upward.

  According to the fourth embodiment, since the slit 52 is provided in the common electrode 32, for example, the capillary phenomenon of the oil 18 is less likely to occur between the width plate portions 32b and 32c and the electrode assembly 31. In addition, since the common electrode 32 is disposed at a height position between the slits 52 adjacent to each other in the vertical direction, even if a capillary phenomenon occurs between the slits 52 adjacent to each other in the vertical direction, the generation range of the common electrode 32 is reduced to one common range. It can be limited between the upper end and the lower end of the electrode 32. In this way, in the internal space 32a of the common electrode 32, the liquid level L is prevented from moving up and down between the plurality of detection electrodes 34a and 34b due to capillary action. Can be increased.

  Furthermore, since the capillary phenomenon is less likely to occur in the internal space 32a of the common electrode 32, the distance between the electrode assembly 31 and the width plate portions 32b and 32c can be minimized. For this reason, further miniaturization of the electrode unit 21 is realizable.

(Fifth embodiment)
In the fifth embodiment, as shown in FIGS. 18 to 20, separators 53 a and 53 b for holding the position of the electrode assembly 31 are provided in the internal space 32 a of the common electrode 32. The electrode unit 21 according to the present embodiment is obtained by applying the electrode assembly 31 according to the second embodiment to the electrode unit 21 according to the first embodiment. Description will be made centering on differences from the second embodiment.

  The separators 53a and 53b are made of an insulating material such as a resin having oil resistance, and are paired with the electrode assembly 31 in the width direction of the electrode unit 21. The pair of separators 53a and 53b are separated from each other and extend in the vertical direction.

  Separator 53a, 53b has the fitting recessed part 54 with which the side edge part of the electrode support body 35 was fitted. The fitting recess 54 is a groove extending in the vertical direction, and almost the entire side end portion of the electrode support 35 is in the fitting recess 54. The separators 53a and 53b have their outer peripheral surfaces overlapped with the inner peripheral surface of the common electrode 32, so that the relative movement with respect to the common electrode 32 is restricted. In this case, the electrode assembly 31 is fixed to the common electrode 32 via the separators 53a and 53b. The separators 53a and 53b can also be referred to as a position holding unit that holds the position of the electrode support 35 with respect to the common electrode 32.

  According to the fifth embodiment, the relative movement of the electrode support 35 with respect to the common electrode 32 is restricted by the separators 53a and 53b. In this case, the fact that the separation distance between the electrode assembly 31 and the common electrode 32 changes due to the shaking of the electrode unit 21 or the bending of the electrode support 35 is suppressed for the entire electrode assembly 31 in the vertical direction. Therefore, the detection accuracy of the liquid level L can be increased.

(Sixth embodiment)
In the sixth embodiment, as shown in FIGS. 21 and 24, in the fifth embodiment, the electrode unit 21 has a lid portion 61 provided at a position above the common electrode 32. In the present embodiment, description will be made centering on differences from the fifth embodiment.

  The lid part 61 is formed in a short cylindrical shape as a whole, and is in a state of closing the internal space 32a of the common electrode 32 from above. The upper end of the electrode support 35 is fixed to the lid 61, and the electrode support 35 extends downward from the lid 61. A lid groove portion 62 extending along the upper end portion of the common electrode 32 is provided on the lower surface of the lid portion 61, and the common electrode 32 is fixed to the lid portion 61 while entering the lid groove portion 62 from below. Has been. In this case, the lid portion 61 holds the position of the upper end portion of the electrode assembly 31 with respect to the upper end portion of the common electrode 32 and can be referred to as an upper holding portion.

  The common electrode 32 has a lower end holding portion 63 that holds the lower end portion of the electrode support 35. As shown in FIGS. 22 and 23, at the lower end portion of the common electrode 32, the distance between the pair of depth plate portions 32d is smaller than the width dimension of the electrode support 35, and the lower end holding portion 63 is a pair of depths. It is provided in each of the plate portions 32d. The lower end holding portion 63 has a fitting recess in which the side end portion of the electrode support 35 is fitted, and this fitting recess extends in a groove shape upward from the lower end portion of the depth plate portion 32d. Yes. The electrode support 35 is held in position by the lower end holding part 63 because at least the lower end of the side end part is in the fitting recess of the lower end holding part 63.

  As shown in FIG. 21, the common electrode 32 has a cylindrical shape opened upward and downward, and the internal space 32a is opened downward by providing the lid portion 61 above. ing. Further, the width plate portions 32b and 32c of the common electrode 32 are provided with cutout portions 64 extending downward from the respective upper end portions. In this case, in the common electrode 32, an oil drain hole through which the oil 18 enters and exits is formed by the lower end opening part and the notch part 64.

  As shown in FIG. 24, the capacitance detection unit 23 of the present embodiment is connected in series with an AC power supply unit 23d that passes an AC current between the detection electrode group 39 and the common electrode 32, and the AC power supply unit 23d. Current measurement unit 23e. The current measurement unit 23e is an impedance analysis unit and is used to calculate impedance and capacitance based on the measured current value.

  The unit switching unit 22 has one power supply side terminal 65 connected to the AC power supply unit 23d and a plurality of electrode side terminals 66 connected to the detection electrodes 34a and 34b. A switch unit is configured. In the unit switching unit 22, the power supply side terminal 65 can be electrically connected to one electrode side terminal 66, and the conduction target of the power supply side terminal 65 is switched to any one of the plurality of electrode side terminals 66. For this reason, unlike the first embodiment, when an alternating current is supplied to the k-th detection electrode group 39, the detection electrode groups 39 other than the k-th detection electrode group 39 are not grounded. . The common electrode 32 is also connected to the negative side of the AC power supply unit 23d, but is not grounded to the ground GND.

  According to the sixth embodiment, the relative movement of the electrode support 35 with respect to the common electrode 32 is restricted by the lid portion 61 and the lower end holding portion 63. In this case, since the electrode assembly 31 is less likely to be inclined with respect to the common electrode 32, it is possible to suppress an unintentional change in the separation distance between the common electrode 32 and the detection electrodes 34a and 34b. Thereby, the detection accuracy of the liquid level L can be increased.

  According to the sixth embodiment, the electrode support 35 can be prevented from being buckled and deformed by supporting the upper end and the lower end of the electrode support 35 by the lid portion 61 and the lower end holding portion 63. Here, the oil 18 stored in the crankcase 12 and the oil pan 13 is less likely to increase or decrease compared to the fuel stored in the fuel tank, for example. In this case, even if the electrode unit 21 has the lid portion 61 and the lower end holding portion 63, the liquid level L is less likely to overlap the height positions of the lid portion 61 and the lower end holding portion 63. For this reason, it is difficult for the detection accuracy of the liquid level L to decrease due to the presence of the lid portion 61 and the lower end holding portion 63.

(Seventh embodiment)
In the seventh embodiment, as shown in FIGS. 25 and 26, in the sixth embodiment, the common electrode 32 includes an intermediate holding portion 68 that holds an intermediate portion of the electrode support 35. In the present embodiment, description will be made focusing on differences from the sixth embodiment.

  The intermediate holding portion 68 is provided in each of the pair of depth plate portions 32d at a central position between the lid portion 61 and the lower end holding portion 63. Similar to the lower end holding portion 63, the intermediate holding portion 68 has a fitting recess in which the side end portion of the electrode support 35 is fitted, and the fitting recess extends in a groove shape in the vertical direction. . The electrode support 35 has a side protrusion 69 protruding sideways in the width direction. A pair of the side convex portions 69 are arranged with the detection electrodes 34 a and 34 b interposed therebetween, and the side convex portions 69 are fitted in the fitting concave portions of the intermediate holding portion 68, respectively. The electrode support 35 is held in position by the intermediate holding part 68 because the side convex part 69 is in a state where it enters the fitting concave part of the intermediate holding part 68.

  In this embodiment, the length dimension of the electrode unit 21 is larger than the length dimension of the electrode unit 21 of the sixth embodiment. In this case, the detection electrodes 34a and 34b of the electrode assembly 31 are arranged in the vertical direction by 16 pieces, which is twice the number of the detection electrodes 34a and 34b of the sixth embodiment.

  The electrode unit 21 is not installed in the crankcase 12 and the oil pan 13 as in the sixth embodiment, but is installed in the fuel tank. The liquid level detection device 20 is a fuel as a liquid. The liquid level can be detected. When detecting the liquid level in the fuel tank using the electrode unit 21, the length dimension of the electrode support 35 is set to a large value in accordance with the size and shape of the fuel tank. In this case, for example, it is considered that the electrode support 35 is easy to bend as compared with the electrode unit 21 of the sixth embodiment, but the occurrence of this buckling is caused by the fitting between the intermediate holding portion 68 and the side convex portion 69. It can be suppressed.

  Here, the amount of fuel stored in the fuel tank is larger than the amount of oil 18 stored in the oil pan 13 or the like. On the other hand, by sufficiently increasing the length of the electrode assembly 31 and the common electrode 32, the lid portion 61 is disposed at a position higher than the upper limit value of the liquid level in the fuel tank, and is lower than the lower limit value. It is possible to arrange the lower end holding part 63 at a lower position. In this configuration, unintentional changes in the relative positions of the electrode assembly 31 and the common electrode 32 are restricted for both the upper limit position and the lower limit position. For this reason, it can suppress that detection accuracy falls about the liquid level when the fuel is replenished, and the liquid level when the remaining fuel is low.

(Eighth embodiment)
In the eighth embodiment, as shown in FIGS. 27 and 28, the common electrode 32 is formed in a U-shaped cross section instead of a cylindrical cross section. The liquid level detection device 20 according to the present embodiment is obtained by applying the electrode unit 21 according to the fifth embodiment to the liquid level detection device 20 according to the sixth embodiment. Description will be made centering on differences between the embodiment and the sixth embodiment.

  The common electrode 32 has a side opening portion 71 that opens the internal space 32a toward the side. The side opening portion 71 is in a state of being stretched between the upper end portion and the lower end portion of the common electrode 32, and the common electrode 32 has a pair of depth plate portions 32d as in the fifth embodiment. Instead, only one depth plate 32d is provided.

  In the present embodiment, of the pair of separators 53a and 53b, the first separator 53a is housed in the internal space 32a of the common electrode 32, while the second separator 53b blocks the side opening 71 from the side. It is in a state. In this case, the second separator 53 b enters the internal space 32 a through the side opening portion 71 and protrudes laterally from the common electrode 32. The second separator 53b is fitted in the side opening 71, and in this state, the electrode support 35 fitted in the fitting recess 54 of the second separator 53b is held in position.

  A plating layer 72 made of a metal material such as copper is overlaid on the inner peripheral surface of the common electrode 32. The plated layer 72 is provided on the entire inner peripheral surface of the common electrode 32.

(Ninth embodiment)
In the first embodiment, the detection electrodes 34a and 34b are formed of a metal material such as stainless steel. However, in the ninth embodiment, the detection electrodes 34a and 34b are formed of a carbon material such as carbon fiber as a carbon fiber. ing. In the present embodiment, description will be made focusing on differences from the first embodiment.

  The detection electrodes 34a and 34b have an electrode main body formed of a carbon material and a thin film covering the electrode main body. The thin film is formed by oxidizing the surface of the electrode body with fluorine having the strongest oxidizing power among all elements, and is a thin film of an organic fluorine compound having a C—F bond. The thin film of this embodiment is formed of graphite fluoride shown in the following generation reaction formula (1). Fluorine has the highest electronegativity due to being the smallest atom in the halogen group, and has the highest oxidizing power among all elements including oxygen.

nC + (n / 2) F2 → (CF) n (1)
The organic fluorine compound part is an electrical insulator and acts as an insulating coating on the detection electrodes 34a and 34b. For this reason, even if metal scraps adhere to the detection electrodes 34a and 34b, for example, an electrical short circuit is suppressed. In addition, the organic fluorine compound is chemically stable and has a property of repelling moisture and oil due to the contact angle being 120 degrees or more. For this reason, in the detection electrodes 34a and 34b, the rise in the liquid level L due to the surface tension of the oil 18 is suppressed. Further, in this case, since sludge is difficult to adhere to the thin film in the oil 18, the sludge is fixed so as to straddle the plurality of detection electrodes 34a and 34b, and it becomes difficult to measure the liquid level by the detection electrodes 34a and 34b. Is deterred.

  The organic fluorine compound is the same organic compound as the oil 18. Here, while the dielectric constant of the organic fluorine compound is 2.0, the dielectric constant of the oil 18 is assumed to be 2.0 to 2.5. In this case, in the detection electrodes 34a and 34b, the thin film which is an organic fluorine compound is measured as if it is equivalent to the oil 18, so that it is difficult for the thin film to interfere with the detection of the liquid level L. And the precision about the thickness dimension of a thin film can be improved compared with the structure by which the thin film was formed by application | coating of the electrical insulator with respect to an electrode main body.

  In addition, when forming a thin film with an organic fluorine compound, it is assumed that the oxidation reaction of an organic fluorine compound becomes intense. On the other hand, for example, it is preferable to suppress the reaction rate of the organic fluorine compound by exposing the electrode body in an atmosphere of sufficiently reduced pressure or an atmosphere of fluorine gas diluted with an inert gas.

  According to the ninth embodiment, since the electrode main bodies of the detection electrodes 34a and 34b are formed of a carbon material, even if the oil 18 is in an acidic state with an organic acid or the like, the electrode main body is caused by corrosion or the like. It can suppress melting. Moreover, it can suppress that the physical property change of an electrode main body arises by the high temperature in the oil pan 13. FIG.

  When the electrode body is made of a carbon material, the electrode body is oxidized by oxygen of high-temperature steam in the exhaust gas leaking from the piston 14, and the surface of the electrode body is consumed by changing the physical properties to carbon monoxide or carbon dioxide. There is concern. On the other hand, according to the ninth embodiment, since the electrode body is covered with the thin film formed of the organic fluorine compound, corrosion of the electrode body surface can be suppressed. Moreover, since the oxidizing power of fluorine is strong, the state in which the electrode body is covered with the thin film can be chemically stabilized.

(Tenth embodiment)
In the tenth embodiment, in the electrode assembly 31, the detection electrode group 39 has a plurality of front side detection electrodes 34a and a plurality of back side detection electrodes 34b. In the present embodiment, description will be made focusing on differences from the first embodiment.

  As shown in FIGS. 29 and 30, the electrode assembly 31 includes detection electrode groups 39a to 39g. Each of these detection electrode groups 39a to 39g has two front side detection electrodes 34a and two back side detection electrodes 34b. Regarding the plurality of detection electrodes 34a and 34b, detection electrodes adjacent in the vertical direction are included in different detection electrode groups. For example, as shown in FIG. 29, one front side detection electrode 34a included in each of the detection electrode groups 39a and 39c is disposed between two front side detection electrodes 34a included in the detection electrode group 39b. Similarly, as shown in FIG. 30, between the two back side detection electrodes 34b of the detection electrode group 39b, the back side detection electrodes 34b of the detection electrode groups 39a and 39c are arranged one by one.

  In each of the detection electrode groups 39a to 39g, the front-side detection electrode 34a and the back-side detection electrode 34b are opposed to each other while being vertically displaced. For example, in the detection electrode group 39b, the lower front detection electrode 34a is disposed at a height position between the two back detection electrodes 34b, and the upper back detection electrode 34b includes the two front detection electrodes 34a. It is arranged at the height position between. In this case, in the detection electrode group 39b, the upper front detection electrode 34a and the upper back detection electrode 34b are paired, and the lower front detection electrode 34a and the lower back detection electrode 34b are paired. Yes. For this reason, the detection electrode group 39b has a plurality of sets of detection electrodes 34a and 34b facing each other with the electrode support 35 interposed therebetween.

  As the configuration in which the front side detection electrode 34a and the back side detection electrode 34b are opposed to each other, a configuration in which at least a part of the detection electrodes 34a and 34b overlaps in the thickness direction of the electrode support 35, the detection electrodes 34a, The structure which does not overlap in the thickness direction of the electrode support body 35 because 34b has shifted | deviated up and down or right and left is mentioned.

  As in the first embodiment, the plurality of detection electrodes 34 a and 34 b are individually connected to the switch unit 22 b of the unit switching unit 22 for each detection electrode group 39. For example, for the detection electrode group 39b, the front electrode lines 41a extending from the two front detection electrodes 34a and the back electrode lines 41b extending from the two back detection electrodes 34b are connected to each other. In the state, it is connected to the switch part 22b.

  Also in the present embodiment, the liquid level detection process is performed by the control device 26, whereby the height position of the liquid level L is calculated as in the first embodiment. In the present embodiment, since the detection electrode group 39 includes four detection electrodes having different height positions, the capacitance Ck varies depending on the height of the liquid level L. For example, as shown in FIG. 30, when comparing the case where the liquid level L is at the height positions Ha and Hb, the detection electrode group 39c is more oily when the liquid level L is at the height position Hb. The capacitance Ck increases due to the large number of detection electrodes immersed in 18.

  According to the present embodiment, since the detection electrode group 39 includes a plurality of sets of detection electrodes 34a and 34b that are opposed to each other with the electrode support 35 interposed therebetween, the liquid level is detected at a plurality of height positions by one detection electrode group 39. The position L can be detected. Further, in the detection electrode group 39, since the detection electrodes 34a and 34b of the other detection electrode group 39 are arranged at a height position between the plurality of detection electrodes 34a and 34b arranged in the vertical direction, a plurality of detection electrodes are provided. Based on the capacitance Ck of each electrode group 39, the position of the liquid level L can be calculated with high accuracy.

  According to the present embodiment, the detection electrodes 34a and 34b of the other detection electrode group 39 are arranged between the two detection electrodes 34a and 34b in one detection electrode group 39, so that a plurality of detection electrode groups is provided. 39 are not arranged in order up and down. For this reason, the material cost of the detection electrodes 34a and 34b is reduced to 1/3 while maintaining the resolution when the liquid level L is detected as compared with the configuration in which the plurality of detection electrode groups 39 are arranged in the vertical direction. It becomes possible to reduce. In other words, even if the detection electrodes 34a and 34b are downsized, it is possible to avoid the liquid level detection device 20 from becoming insufficiently sensitive. In this case, even if the change rate of the liquid level with respect to the change in the liquid level L is increased by downsizing the engine 10 or the oil pan 13, the resolution for the detection of the liquid level L is enhanced, so that the liquid amount can be reduced. Detection accuracy can be increased.

  In the present embodiment, one detection electrode group 39 may include three or more detection electrodes 34a and 34b. Further, the number included in one detection electrode group 39 may be different between the front side detection electrode 34a and the back side detection electrode 34b.

(Eleventh embodiment)
In the eleventh embodiment, the combinations included in one detection electrode group 39 are switched by the unit switching unit 22 for the plurality of detection electrodes 34 a and 34 b. In the present embodiment, description will be made focusing on differences from the tenth embodiment.

  In the present embodiment, as shown in FIG. 31, in the electrode assembly 31, each of the plurality of detection electrodes 34a, 34b is individually connected to the unit switching unit 22 via the electrode wires 41a, 41b. The unit switching unit 22 has a circuit capable of switching the combination of the detection electrodes 34a and 34b to which a voltage is applied during the liquid level detection among the plurality of detection electrodes 34a and 34b.

  For example, when the detection electrodes 34 a and 34 b in the first, third, and fifth stages are to be applied with voltage, these six detection electrodes 34 a and 34 b are included in one detection electrode group 39. become. In addition, the detection electrodes 34 a and 34 b in the second stage and the fourth stage may be included in one detection electrode group 39 by switching the voltage application target by the unit switching unit 22. In the electrode assembly 31, N detection electrodes 34a and 34b are arranged.

  The control device 26 performs a liquid level detection process as in the first embodiment. Here, the liquid level detection process will be described with reference to FIG. In this liquid level detection process, six detection electrodes 34 a and 34 b are selected as one detection electrode group 39 for three stages among the plurality of detection electrodes 34 a and 34 b. For the three stages, the lower stage ka, the middle stage kb, and the upper stage kc are selected.

  In FIG. 32, in step S201, the steps ka, kb, kc indicating the detection electrodes 34a, 34b to be detected for capacitance are set to predetermined values, respectively. For example, k = 0, k = 2, and k = 4 are set. In step S202, the lower ka is incremented, in step S203, the middle kb is incremented, and in step S204, the upper kc is incremented. Thereafter, in steps S205 to S210, the same processing as steps S103 to S108 of the first embodiment is performed.

  However, in step S207, the total capacitance of the six detection electrodes 34a and 34b in the stages ka, kb, and kc is calculated as the capacitance Cka. In the first processing, the lower stage ka = 1, the middle stage kb = 3, and the upper stage kc = 5. The detection electrodes 34a of the first stage, the third stage, and the fifth stage shown by hatching in FIG. The capacitance Cka is calculated with 34b as one detection electrode group 39.

  In step S208, the threshold Th used for determination of the capacitance Cka is set to a value when one of the six detection electrodes 34a and 34b is in the liquid. For this reason, in step S208, when at least one detection electrode is present in the liquid for one detection electrode group 39, a YES determination is made. In the submerged processing in step S209, processing for specifying the number of detection electrodes in the liquid is performed for one detection electrode group 39. Here, threshold values in the case where the number of detection electrodes in the liquid is 2 to 6 are stored in the storage unit, and each of these threshold values is in the liquid by comparing the capacitance Cka. The number of detection electrodes is calculated.

  In step S211, a value obtained by subtracting the difference between the upper stage kc and the lower stage ka from the number N of each of the detection electrodes 34a and 34b is calculated as a repetition number, and it is determined whether or not the lower stage ka is smaller than the repetition number. Here, each process of steps S202 to S210 is repeated until the lower stage ka reaches the number of repetitions. When the lower stage ka reaches the number of repetitions, the process proceeds to step S212, and the height position of the liquid level L is calculated.

  According to the present embodiment, since the combination included in one detection electrode group 39 is changed for the plurality of detection electrodes 34a and 34b, one detection electrode 34a and 34b has a plurality of detection electrodes in the liquid level detection process. It is included in the detection electrode group 39. For this reason, about the detection of the liquid level L, resolution | decomposability more than the number of detection electrodes 34a and 34b is realizable. In this case, as in the tenth embodiment, even if the detection electrodes 34a and 34b are downsized, the liquid level detection device 20 can be prevented from becoming insufficiently sensitive.

  In the present embodiment, the number of detection electrodes 34a and 34b set as one detection electrode group 39 may be two, or may be four or more. Further, the number set as one detection electrode group 39 may be different between the front side detection electrode 34a and the back side detection electrode 34b.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and various embodiments and combinations can be made without departing from the scope of the present invention. Can be applied.

  In Modification 1, as shown in FIG. 33, in the first embodiment, the height position of the front side detection electrode 34a may be different from the height position of the back side detection electrode 34b. This configuration is a configuration in which the electrode unit 21 of the first embodiment is applied to the second embodiment without changing the number of detection electrodes 34a and 34b.

  In Modification 2, as shown in FIG. 34, in the fourth embodiment, the slit 52 may be disposed at a height position facing the detection electrodes 34a and 34b. In this case, the height dimension of the slit 52 is larger than the height dimension of the detection electrodes 34 a and 34 b, and the detection electrodes 34 a and 34 b are more than the slit 52 in the slit 52 and the detection electrodes 34 a and 34 b facing each other. Are not projected upward and downward.

  In the third modification, the ceiling surface 52a and the bottom surface 52b of the slit 52 do not have to extend in parallel in the fourth embodiment. For example, as shown in FIG. 35, the bottom surface 52b is inclined with respect to the ceiling surface 52a in the depth direction of the common electrode 32. The bottom surface 52 b of this configuration is a tapered surface extending obliquely downward toward the outer peripheral side of the common electrode 32. According to this configuration, the change in the liquid level L due to the surface tension of the oil 18 is suppressed by the inclination of the bottom surface 52 b, and the liquid level in the internal space 32 a with respect to the displacement of the liquid level L outside the common electrode 32. The followability of L can be made favorable.

  In the outer peripheral portion of the common electrode 32, an acute angle portion is formed by the bottom surface 52 b of the upper slit 52 and the ceiling surface 52 a of the lower slit 52 among the slits 52 adjacent to each other in the vertical direction. Thereby, the followability of the liquid level L in the internal space 32a is easily improved. In FIG. 35, the electrode assembly 31 is not shown.

  In the fourth modification, as shown in FIG. 36, the slit 52 may be inclined with respect to the width direction W of the common electrode 32 in the fourth embodiment. For example, the ceiling surface 52 a and the bottom surface 52 b of the slit 52 are configured to be inclined with respect to the width direction W by an angle θ. In this configuration, the ceiling surface 52 a and the bottom surface 52 b are also inclined by the angle θ with respect to the upper end surface and the lower end surface of the common electrode 32. On the other hand, the side end portion of the slit 52 extends parallel to the side end surface of the common electrode 32. In FIG. 36, the electrode assembly 31 is not shown.

  In Modification 5, as shown in FIG. 37, in the fourth embodiment, instead of the slit 52, an inner concave portion 75 formed by denting the inner peripheral surface of the common electrode 32 toward the outer peripheral side is provided. It may be. The inner recess 75 has a horizontally long shape extending in the width direction of the common electrode 32, and is disposed at a height position between the detection electrodes 34a and 34b adjacent in the vertical direction. The recess size of the inner recess 75 is approximately ½ of the thickness of the outer peripheral portion of the common electrode 32. According to this configuration, since the separation distance between the electrode assembly 31 and the common electrode 32 is large in the arrangement portion of the inner concave portion 75, occurrence of liquid level separation due to capillary action in the internal space 32a can be suppressed.

  In Modification 6, the pair of detection electrodes 34a and 34b is not electrically connected through an electrical path as in the above embodiments, but the detection electrode group 39 is connected to the pair of detection electrodes 34a and 34b. You may have an electrode. For example, the connection electrode extends over the pair of detection electrodes 34 a and 34 b, and the connection electrode is configured to face the depth plate portion 32 d of the common electrode 32. In this configuration, a pair of detection electrodes 34a and 34b and a connection electrode are formed by folding a single metal plate, and an electrostatic capacity is also generated between the connection electrode and the depth plate portion 32d. Become.

In the modified example 7, unlike the above-described embodiments, the detection electrodes 34a and 34b and the common electrode 32 may not face each other on the plate surfaces. For example, the common electrode 32 may be formed in a cylindrical shape, and the detection electrodes 34 a and 34 b may have curved surfaces that protrude toward the common electrode 32. Even in these cases, it is possible to detect the liquid level L based on the capacitance between the detection electrodes 34a and 34b and the common electrode 32.

  In the modified example 8, in the detection electrode group 39, the pair of detection electrodes 34a and 34b may not extend in parallel to each other. For example, in a configuration in which the electrode support 35 is formed in a columnar shape or a cylindrical shape, a pair of detection electrodes 34a and 34b are arranged with the electrode support 35 sandwiched between them in a state where the distance between them is non-uniform. To do.

  In the modified example 9, in the first embodiment, the four sides of the intermediate electrode 37 may be surrounded by supporting insulating portions such as the insulating portions 36a and 36b. For example, the support insulating part is formed in a cylindrical shape, and the intermediate electrode 37 is arranged in the internal space of the support insulating part. Even in this case, it is possible to realize a configuration in which the intermediate electrode 37 and the detection electrodes 34a and 34b are electrically insulated by the support insulating portion.

  In Modification 10, in the first embodiment, only one switch unit 22b may shift to the positive state, and a plurality of switch units 22b may shift to the positive state. In this case, the capacitance is detected for a plurality of detection electrode groups 39. Even in this configuration, it is possible to calculate the liquid level L based on the detected capacitance by changing the combination of the plurality of detection electrode groups 39 that are capacitance detection targets.

  In Modification 11, in each of the above embodiments, the capacitance detection unit 23 and the arithmetic processing unit 24 may be provided individually for each detection electrode group 39. In this case, the arithmetic processing unit 24 can detect the liquid level L by comparing the detection results of the respective capacitance detection units 23. In this configuration, it is not necessary to provide the unit switching unit 22 and the switching processing unit 25.

  In Modification 12, in the first embodiment, when the capacitance of the detection electrode group 39 at the k-th stage is detected, the detection electrode group 39 connected to the common electrode 32 or the ground GND is other than the k-th stage. Not all of this. For example, when a voltage is applied to the detection electrode group 39 at the k-th stage, only the detection electrode groups 39 at the (k + 1) -th stage and the (k-1) -th stage are grounded to the ground GND. In addition, when the k-th stage is not the lowermost stage or the uppermost stage, only the lowermost detection electrode group 39 or the uppermost detection electrode group 39 is connected to the common electrode 32 or the ground GND. In any configuration, in addition to the positive state and the negative state, the switch portion 22b can shift to a neutral state in which the detection electrode group 39 is not connected to either the positive electrode side or the negative electrode side of the DC power supply unit 23a. . In this case, the switch unit 22b that does not shift to either the positive state or the negative state is shifted to the neutral state.

  In the modified example 13, the common electrode 32 and the intermediate electrode 37 may not be grounded to the ground GND, and the switch unit 22b may ground the detection electrode group 39 to the ground GND by shifting to a negative state.

  In the modified example 14, in the first embodiment, if the gap region SP is formed between the upper and lower adjacent detection electrode groups 39, the pair of detection electrodes 34a and 34b are shifted from each other in the vertical direction. It may be arranged. For example, the upper and lower ends of the front side detection electrode 34a are arranged at positions higher than the upper and lower ends of the back side detection electrode 34b.

  In the modified example 15, in the second embodiment, if the center line Ob of the back side detection electrode 34b is disposed between the center lines Oa of the front side detection electrodes 34a adjacent to each other in the vertical direction, the center line Ob on the back side is arranged. May not be arranged at the center of the center line Oa on the front side that is adjacent vertically.

  In the modification 16, in each said embodiment, the magnitude | size and shape may differ between the front side detection electrode 34a and the back side detection electrode 34b.

  DESCRIPTION OF SYMBOLS 12 ... Crankcase, 13 ... Oil pan, 20 ... Liquid level detection apparatus, 21 ... Electrode unit, 22 ... Unit switching part, 22b ... Switch part, 23 ... Electrostatic capacity detection part, 23a ... DC power supply part, 23d ... AC Power supply unit 26 ... Control device 32 ... Common electrode 32a ... Internal space 34a ... Front side detection electrode 34b ... Back side detection electrode 35 ... Electrode support 36a ... Front side insulation part 36b ... Back side insulation part 37 ... Intermediate electrode 39 ... detection electrode group, 41a ... front side electrode line, 41b ... back side electrode line, 52 ... slit, 65 ... power source side terminal, 66 ... electrode side terminal, SP ... gap region.

Claims (10)

An electrode unit (21) provided inside the container (12, 13);
A liquid level detector (22, 23, 26) for detecting a liquid level position (L) of the liquid stored in the container by detecting a capacitance from the electrode unit;
With
The electrode unit is
A plurality of detection electrodes (34a, 34b) arranged in the height direction of the container;
A storage electrode (32) facing each of the plurality of detection electrodes in a state of storing the plurality of detection electrodes;
An electrode support (35) supporting the plurality of detection electrodes in the internal space (32a) of the storage electrode;
Have
In the plurality of detection electrodes, a plurality of detection electrode groups (39) having at least two detection electrodes facing each other across the electrode support portion are arranged in the height direction of the container,
The liquid level detector
The liquid level detection device (20), wherein the liquid level position is detected based on capacitance between the plurality of detection electrodes and the storage electrode. The electrode support is
A support electrode (37) provided in a state extending along the height direction of the container and electrically connected to the storage electrode;
By being provided between the support electrode and the detection electrode, a support insulating part (36a, 36b) that electrically insulates the support electrode and the detection electrode;
The liquid level detection device according to claim 1, comprising:   An electrical wiring that is electrically insulated from both the detection electrode and the support electrode by being provided inside the support insulation portion, and is connected to the detection electrode and extends along the height direction of the container (41a, 41b) The liquid level detection device according to claim 2, wherein the liquid level detection device is provided. A power supply state in which each detection electrode of the detection electrode group is electrically connected to a power supply unit (23a, 23d) to apply a voltage to each detection electrode of the detection electrode group, and the voltage is applied to each detection electrode of the detection electrode group. It is possible to shift to a storage side state in which each detection electrode of the detection electrode group is electrically connected to the storage electrode so as not to be applied, and switch portions (22b, 65, 66)
A transition unit (S103, S104) for individually transitioning the state of the switch unit for each of the plurality of detection electrode groups;
The liquid level detection device according to claim 1, wherein the liquid level detection device is provided. The transition unit is
A first transition unit (S103) that causes any one of the plurality of detection electrode groups to be a first electrode group that is a capacitance detection target and shifts the switch unit corresponding to the first electrode group to the power supply side state. When,
A second transition unit (S104) that shifts the switch unit corresponding to the second electrode group to the storage-side state, with the second electrode group being different from the first electrode group among the plurality of detection electrode groups. When,
The liquid level detection device according to claim 4, comprising:   The liquid level detection device according to claim 1, wherein the storage electrode is grounded.   The gap region (SP) in which none of the detection electrodes of these detection electrode groups is installed is provided between the detection electrode groups adjacent to each other in the height direction of the container. The liquid level detection apparatus as described in any one of 1-6. In the detection electrode group, one detection electrode is an upper detection electrode (34a) extending above the other detection electrode with respect to the pair of detection electrodes facing each other across the electrode support portion, The detection electrode is a lower detection electrode (34b) extending below one detection electrode,
In the detection electrode group adjacent in the height direction of the container, at least a part of the lower detection electrode of the upper detection electrode group has the electrode support portion on the upper detection electrode of the lower detection electrode group. The liquid level detection device according to any one of claims 1 to 6, wherein the liquid level detection device faces each other.   The liquid level detection device according to any one of claims 1 to 8, wherein the detection electrode group includes a plurality of sets of two detection electrodes opposed to each other with the electrode support portion interposed therebetween.   The said storage electrode is provided with multiple through-holes (52) which penetrate the outer peripheral part of the said storage electrode along the height direction of the said container, The any one of Claims 1-9 characterized by the above-mentioned. The liquid level detection apparatus described in 1.

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