JP2016050781A - Liquid level detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detection device that can detect a liquid level in a container without being affected by the density of the liquid used and can detect inclination, if any, of the container.SOLUTION: The liquid level detection device includes a first emission part 110 that emits a first wave motion at a prescribed angle θ1 to the bottom face portion 11 of a container 10 in a direction from a prescribed position O of the bottom face portion 11 toward the liquid level, a second emission part 120 that emits a second wave motion, in the direction reverse to the first wave motion, at the prescribed angle θ1 to the bottom face portion 11 from the prescribed position O to the liquid level, a detection part 130 that is arranged in the bottom face portion 11, detects the position of the first wave motion reflected by the liquid level and reaching the bottom face portion 11 and detects the position of the second wave motion reflected by the liquid level and reaching the bottom face portion 11, and a calculation part 140 that calculates the position of the liquid level and the inclination of the liquid level relative to the bottom face portion 11 on the basis of the prescribed angle θ1, the position of the first wave motion and the position of the second wave motion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid level detection device suitable for application to, for example, a fuel level detection device that detects the position of a fuel level in a fuel tank of an automobile.

  2. Description of the Related Art Conventionally, for example, a device described in Patent Document 1 is known as a liquid level detection device that detects a liquid level position of a liquid in a tank. In the liquid level detection device (ultrasonic liquid level meter) of Patent Document 1, a thin tubular transmission tube extending in the depth direction is provided in a tank, and an ultrasonic transducer is attached to a watertight case at the bottom of the transmission tube. ing.

  In Patent Document 1, when a pulsed ultrasonic wave is emitted from an ultrasonic transducer into a transmission tube, the ultrasonic pulse is reflected by the liquid surface, and the reflected ultrasonic pulse is transmitted through the transmission tube to generate ultrasonic vibrations. Detected by children. Then, the time required until the ultrasonic pulse is emitted and detected from the ultrasonic transducer is converted, and the liquid level position is grasped according to the required time.

Japanese Unexamined Patent Publication No. 6-249697

  However, in the above-mentioned Patent Document 1, since the ultrasonic pulse moves in the liquid, the time required for being detected after being emitted depends on the density of the liquid. Therefore, it is necessary to grasp the accurate characteristics of the liquid. There is. For example, it is necessary to accurately grasp the relationship of the liquid level position to the required time according to the liquid to be used.

  Also, when the tank is tilted, the ultrasonic pulse reflected on the liquid level returns to the ultrasonic transducer while being reflected on the inner wall of the transmission tube. Cannot be measured.

  In view of the above problems, the object of the present invention is not affected by the density of the liquid used in detecting the liquid surface position in the container, and can detect the inclination of the container when it is inclined. The object is to provide a liquid level detection device.

  In order to achieve the above object, the present invention employs the following technical means.

In the present invention, the liquid level detection device detects the position (H) of the liquid level of the liquid stored in the container (10),
A first launching unit that launches a first wave in a direction from the predetermined position (O) of the bottom surface part (11) toward the liquid surface at a predetermined angle (θ1) with the bottom surface part (11) of the container (10). 110)
A second launching unit that launches a second wave in a direction from the predetermined position (O) toward the liquid surface in a direction opposite to the first wave, at a predetermined angle (θ1) with the bottom surface part (11). 120),
A first wave position (C) that is disposed on the bottom surface part (11) and reflects on the liquid surface to reach the bottom surface part (11), and a second wave position that reflects on the liquid surface and reaches the bottom surface part (11). A detection unit (130) for detecting the position (F) of the wave;
Based on the predetermined angle (θ1), the position of the first wave (C), and the position of the second wave (F), the position of the liquid surface (H) and the liquid surface relative to the bottom surface (11) And a calculation unit (140) for calculating relative inclinations (θ2, θ3).

  According to the present invention, the wave has a straight traveling property, and reaches the bottom surface portion (11) in a state where the incident angle and the reflection angle when hitting the liquid surface are equal. Therefore, the calculation unit (140) geometrically calculates the liquid level based on the predetermined angle (θ1), the first wave position (C), and the second wave position (F). In addition to the position (H), the relative inclination (θ2, θ3) of the liquid surface with respect to the bottom surface portion (11) can be calculated (details will be described later). By calculating the relative inclination (θ2, θ3) of the liquid level, it can be determined whether the change in the position (H) of the liquid level is due to the change in the original liquid amount or the inclination of the container (10). It becomes possible to specify. And in the said calculation, since it is not influenced by the density of the liquid to be used, it is not necessary to grasp | ascertain the exact characteristic of the liquid beforehand.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

It is a front view which shows the liquid level detection apparatus in 1st Embodiment. It is explanatory drawing which shows the state which projected the locus | trajectory of the emitted laser beam, a liquid level position, and inclination (theta) 2 on xy plane. It is explanatory drawing (III direction arrow line view of FIG. 2) which shows the state which projected the locus | trajectory of the emitted laser beam, and inclination (theta) 3 on zy plane. It is an arrow line view which shows the locus | trajectory of the emitted laser beam in xyz coordinate. It is a front view which shows the liquid level detection apparatus in 2nd Embodiment.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly indicate that the combination is possible in each embodiment, but also a combination of the embodiments even if they are not clearly specified unless there is a problem with the combination. It is also possible.

(First embodiment)
The liquid level detection apparatus 100 of 1st Embodiment is demonstrated using FIGS. 1-4. The liquid level detection device 100 is, for example, a device that detects (calculates) the position of the liquid level of fuel (for example, gasoline) stored in the vehicle fuel tank 10. The fuel tank 10 corresponds to the container of the present invention, and the fuel corresponds to the liquid of the present invention.

  As shown in FIG. 1, the fuel tank 10 has a rectangular parallelepiped shape, for example, and the bottom surface portion 11 is formed in a flat shape. Here, in order to facilitate understanding of the following description, xyz coordinates are defined in the fuel tank 10. The x-axis is an axis indicating one direction (the left-right direction in FIG. 1) along the surface of the bottom surface portion 11, the y-axis is an axis indicating a direction orthogonal to the bottom surface portion 11, and the z-axis is the axis of the bottom surface portion 11. It is an axis | shaft which shows the direction (front-back direction in FIG. 1) orthogonal to the x-axis along a surface. The origin O in the xyz coordinates is defined as a reference position (a predetermined position in the present invention).

  The liquid level detection apparatus 100 includes a first light emitting element 110, a second light emitting element 120, a support part 125, a light receiving part 130, a calculating part 140, and the like.

  The first light emitting element 110 is a first emitting unit that emits a first wave. Waves are light here. As the first light emitting element 110, for example, a laser pointer that emits laser light is used. The first light emitting element 110 is, for example, a case where the amount of fuel in the fuel tank 10 has become a minimum amount (Empty) at a position separated from the bottom surface portion 11 by a predetermined distance to the liquid surface side by the rod-shaped support portion 125. Also, it is fixed so as to be in a position to be immersed in the fuel. For example, the first light emitting element 110 is disposed so as to be included in the xy plane.

  The first light emitting element 110 emits a first laser beam toward the liquid level of the fuel. The direction in which the laser beam is emitted is the first direction from the reference position (origin O) in the bottom surface portion 11 to the liquid surface at an angle θ1 with the bottom surface portion 11 included in the xy plane, for example. The angle θ1 corresponds to the predetermined angle of the present invention.

  The second light emitting element 120 is a second emitting unit that emits a second wave, and has the same structure as the first light emitting element 110 described above. In other words, the wave here uses light. The second light emitting element 120 uses a laser pointer that emits laser light. The second light emitting element 120 is used as a fuel even when the fuel in the fuel tank 10 becomes a minimum amount (Empty) at a position separated from the bottom surface portion 11 by a predetermined distance to the liquid surface side by the support portion 125. It is fixed so that it is in the position of immersion. For example, the second light emitting element 120 is disposed so as to be included in the xy plane, and is disposed with a certain distance in the x-axis direction with respect to the first light emitting element 110. Therefore, both the first light emitting element 110 and the second light emitting element 120 are arranged so as to be included in the xy plane.

  The second light emitting element 120 emits a second laser beam toward the fuel surface. The direction in which the laser light is emitted is included in, for example, the xy plane from the reference position (origin O) in the bottom surface portion 11, and is the direction opposite to the first direction in the first light emitting element 110, and the bottom surface portion. 11 and an angle θ1 in the second direction reaching the liquid surface.

  The light receiving unit 130 is a detection unit disposed on the bottom surface part 11, and is emitted from the first light emitting element 110 and the second light emitting element 120, reflected on the liquid surface, and further reaches the bottom surface part 11. The second laser beam is detected.

  The light receiving unit 130 is formed, for example, on a circular plate member centered on a reference position (origin O), in which a plurality of photosensitive elements 131 are arranged in a mesh pattern at predetermined intervals. The light receiving unit 130 determines the position of the photosensitive element 131 having the highest intensity of received light among the plurality of photosensitive elements 131 as the position of the first laser beam (C in FIG. 2, G in FIG. 3), and The position is detected as the position of the second laser beam (F in FIG. 2).

  Among the plurality of photosensitive elements 131, the photosensitive element 131 having the highest received light intensity outputs a detection signal indicating that the first laser beam and the second laser beam have been detected to the calculation unit 140 described later. It is like that. When there are a plurality of photosensitive elements 131 having the strongest received light intensity, the calculation unit 140 grasps, for example, an average position of the photosensitive elements 131 with respect to the reference position as a detection position. It has become.

  The calculation unit 140 calculates the fuel based on the known angle θ1 when the first and second laser beams are emitted, the position C of the first laser beam obtained from the light receiving unit 130, and the position F of the second laser beam. The liquid surface position (H in FIG. 2) and the relative inclination of the liquid surface with respect to the bottom surface portion 11 (θ2 in FIG. 2, θ3 in FIG. 3) are calculated. The calculation unit 140 preliminarily includes calculation formulas for calculating the position H of the fuel liquid level (distance L from the bottom surface part 11 to the liquid level) and the relative inclinations θ2 and θ3 of the liquid surface with respect to the bottom surface part 11. Held (stored) (details will be described later).

  Further, the calculation unit 140 has a volume calculation formula for calculating the volume of fuel in the fuel tank 10. The volume calculation formula is a formula calculated based on the position of the liquid level (distance L to the liquid level), the relative inclinations θ2 and θ3 of the liquid level, and the shape characteristics related to the fuel tank 10 that have been grasped in advance. . The shape characteristic of the fuel tank 10 in the volume calculation formula represents, for example, how the area of the bottom surface portion 11 changes in the y-axis direction depending on the distance L to the liquid surface and the inclinations θ2 and θ3. can do. Therefore, the volume of the fuel can be calculated by integrating such shape characteristics (area change of the bottom surface portion 11) in the y-axis direction.

  Next, the operation of the liquid level detection apparatus configured as described above (the calculation procedure in the calculation unit 140) will be described with reference to FIGS. 2 and 3 show a state in which the fuel tank 10 is tilted. Here, for convenience, the liquid level is displayed as being tilted relative to the bottom surface portion 11. 2 indicates the inclination with respect to the x-axis on the xy plane, and the inclination θ3 in FIG. 3 indicates the inclination with respect to the z-axis on the zy plane.

  In the case where the relative inclination of the liquid surface has only θ2, as shown in FIG. 2, the first and second laser beams move on the xy plane according to the inclination θ2. Further, when the inclination θ3 is added to the inclination θ2, the first and second laser beams are on the liquid surface (point A, point E) according to the inclination θ3, as shown in FIGS. When reflected, it shifts in the z-axis direction and reaches the bottom surface portion 11. Therefore, FIG. 2 shows the first and second laser beams when projected from the z-axis direction, and FIG. 3 shows the first (second) when projected from the x-axis direction. Laser light is shown.

  As shown in FIG. 2, the first laser light emitted from the first light emitting element 110 proceeds to the liquid surface as if emitted from the reference position (origin O) at an angle θ1, and is reflected at the point A. Thus, the position reaches the position C of the first laser beam on the bottom surface 11. Similarly, the second laser light emitted from the second light emitting element 120 has an angle θ1 as if it was emitted from the reference position (origin O), and the liquid level is opposite to the first laser light. Then, the light is reflected at the point E and reaches the position F of the second laser beam on the bottom surface 11.

  Further, as shown in FIG. 3, the first laser light emitted from the first light emitting element 110 proceeds to the liquid surface as if it was emitted from the reference position (origin O), and reflected at the point A, The position reaches the position G of the first laser beam on the bottom surface 11 according to the inclination θ3. The same applies to the second laser light emitted from the second light emitting element 120.

  Hereinafter, calculation formulas for calculating the position H (the distance L from the bottom surface portion 11 to the liquid surface) of the fuel liquid level and the relative inclinations θ2 and θ3 of the liquid surface with respect to the bottom surface portion 11 will be described. Here, in order to obtain the calculation formula, OC, OF, OC / OF in FIG. 2 and the length (distance) of OG in FIG. 3 are derived as mathematical formulas including distance L, slope θ2, and slope θ3. Yes.

  First, in FIG. 2, a straight line AB is a perpendicular drawn from the point A to the x-axis (bottom surface portion 11). The straight line AD is a straight line that reaches the x-axis (bottom surface portion 11) perpendicular to the liquid surface at point A. The distance from the bottom surface 11 to the liquid surface position H on the y-axis is L, and the distance from the liquid surface position H to the position corresponding to the point A along the y-axis is M. In FIG. 3, a straight line AG is a straight line that reaches the z-axis (bottom surface portion 11) perpendicular to the liquid surface at point A.

The angle of each part is as follows. That is,
∠OAB = π / 2−θ1,
∠BAD = θ2,
From the relationship of incident angle = reflection angle,
∠OAD = ∠DAC = (π / 2−θ1) + θ2 = π / 2−θ1 + θ2,
∠ BAC = θ2 + (π / 2−θ1 + θ2) = π / 2−θ1 + 2 · θ2.

In AB and OB,
(Equation 1)
tan θ1 = AB / OB

From Equation 1,
OB = AB / tan θ1 = (L + M) / tan θ1

Therefore,
(Equation 2)
OB = (L + M) / tan θ1.

Also, tan θ2 = M / OB,
(Equation 3)
M = OB · tan θ2.

Substituting equation 3 into equation 2,
OB = (L + M) / tan θ1 = (L + OB · tan θ2) / tan θ1
OB · tan θ1 = L + OB · tan θ2
OB (tan θ1−tan θ2) = L

Therefore (Equation 4)
OB = L / (tan θ1-tan θ2)

Also, from Equation 1, AB = tan θ1 · OB, and when Equation 4 is substituted into this,
AB = tan θ1 · OB = tan θ1 · L / (tan θ1−tan θ2)

Therefore,
(Equation 5)
AB = tan θ1 · L / (tan θ1−tan θ2)

Also,
(Equation 6)
tan (∠BAC) = tan (π / 2−θ1 + 2 · θ2) = BC / AB

From Equation 5 and Equation 6,
BC = AB · tan (π / 2−θ1 + 2 · θ2)
= {Tan θ1 · L / (tan θ1−tan θ2)} · tan (π / 2−θ1 + 2 · θ2)

Therefore,
(Equation 7)
BC = {tan θ1 · L / (tan θ1−tan θ2)} · tan (π / 2−θ1 + 2 · θ2)

From Equation 4 and Equation 7,
OC = OB + BC
= L / (tan θ1−tan θ2) + {tan θ1 · L / (tan θ1−tan θ2)} · tan (π / 2−θ1 + 2 · θ2)
= {L + L · tan θ1 · tan (π / 2−θ1 + 2 · θ2)} / (tan θ1−tan θ2)

Therefore,
(Equation 8)
OC = {L + L · tan θ1 · tan (π / 2−θ1 + 2 · θ2)} / (tan θ1−tan θ2)

  Next, the OF can be obtained by setting θ2 to −θ2 in the OC of Expression 8 above.

That is,
(Equation 9)
OF = {L + L · tan θ1 · tan (π / 2−θ1-2 · θ2)} / (tan θ1 + tan θ2)

From Equation 8 and Equation 9,
OC / OF = {L + L · tan θ1 · tan (π / 2−θ1 + 2 · θ2)}
/ (Tan θ1-tan θ2)
/ [{L + L · tan θ1 · tan (π / 2−θ1-2 · θ2)}
/ (Tan θ1 + tan θ2)]
= [(Tan θ1 + tan θ2) / (tan θ1−tan θ2)]
・ [(1 + tan θ1 · tan (π / 2−θ1 + 2 · θ2)
/ (1 + tan θ1 · tan (π / 2−θ1-2 · θ2)].

Therefore,
(Equation 10)
OC / OF = [(tan θ1 + tan θ2) / (tan θ1-tan θ2)]
・ [(1 + tan θ1 · tan (π / 2−θ1 + 2 · θ2) /
(1 + tan θ1 · tan (π / 2−θ1-2 · θ2)]

On the other hand, as shown in FIG.
(Equation 11)
tan θ3 = OG / OA.

AO = AB, and from Equations 11 and 5,
OG = OA · tan θ3
= AB ・ tanθ3
= {Tan θ1 · L / (tan θ1−tan θ2)} · tan θ3.

Therefore,
(Equation 12)
OG = {tan θ1 · L / (tan θ1−tan θ2)} · tan θ3.

  The calculation unit 140 holds (stores) Formulas 10, 8, 9, and 12 based on the above description as calculation formulas in advance. Then, the calculation unit 140 grasps the position C (G) of the first laser light and the position F of the second laser light on the bottom surface part 11 from the detection signal obtained from the light receiving unit 130, and the distance OC on the xy plane. , OF, and OG are calculated.

  Then, the calculation unit 140 calculates the inclination θ2 by substituting OC, OF, and the angle θ1 into Equation 10. Next, the OC, the angle θ1, and the inclination θ2 are substituted into Formula 8, and the distance L to the liquid surface (that is, the position H of the liquid surface) is calculated. Alternatively, OF, angle θ1, and inclination θ2 are substituted into Formula 9, and the distance L to the liquid level (that is, the position H of the liquid level) is calculated. Further, the inclination θ3 is calculated by substituting OG, the angle θ1, and the inclination θ2 into Expression 12.

  Furthermore, the calculation unit 140 calculates the volume of the fuel using the volume calculation formula based on the distance L to the liquid level, the inclinations θ2 and θ3, and the shape characteristics related to the fuel tank 10 obtained above.

  The calculation unit 140 calculates the inclinations θ2 and θ3, the position H of the liquid level, and the volume of fuel in the fuel tank 10 at predetermined time intervals.

  As described above, according to the present embodiment, the first and second laser beams (waves) have a straight traveling property, and the incident angle and the reflection angle when hitting the liquid surface are equal. The bottom part 11 is reached. Therefore, the calculation unit 140 geometrically (formulas 10, 8, 9, and 10) based on the predetermined angle θ1, the position C (G) of the first laser light, and the position F of the second laser light. 12), the relative inclinations θ2 and θ3 of the liquid surface with respect to the bottom surface portion 11 can be calculated in addition to the position H of the liquid surface. By calculating the relative inclinations θ2 and θ3 of the liquid level, it is possible to specify whether the change in the position H of the liquid level is due to the change in the original liquid amount or the inclination of the fuel tank 10. It becomes. And in the said calculation, since it is not influenced by the density of the liquid to be used, it is not necessary to grasp | ascertain the exact characteristic of the liquid beforehand.

  In the present embodiment, as described above, the position H of the liquid level and the relative inclinations θ2 and θ3 of the liquid level are set to the predetermined angle θ1, the position C (G) of the first laser beam, and the second laser. Calculation is based on the position F of light. Therefore, even when the relative inclinations θ2 and θ3 of the liquid surface with respect to the bottom surface portion 11 are generated, the transmission pipe as described in Patent Document 1 is not required, and a simple configuration can be achieved.

  In this embodiment, by using light (laser light) as the wave, suitable straightness and reflection characteristics can be obtained, and a result that matches the theory can be calculated.

  In addition, since the volume of the fuel can be calculated by the volume calculation formula, it is possible to prepare for future measures such as fuel supply.

(Second Embodiment)
A liquid level detection apparatus 100A of the second embodiment is shown in FIG. In the second embodiment, a warning unit 150 is added to the liquid level detection device 100 in the first embodiment.

  The warning unit 150 is a warning unit that warns the driver (user) of the vehicle that the volume of fuel in the fuel tank 10 has decreased. The warning for the driver is, for example, alerting by a buzzer, chime, voice, or the like.

  As described in the first embodiment, when the calculation unit 140 determines that the volume of the fuel in the fuel tank 10 is less than a predetermined volume, the calculation unit 140 operates the warning unit 150. As a result, the driver can quickly take measures such as refueling.

(Other embodiments)
In the first and second embodiments, the waves emitted from the first and second emitting units using the first and second light emitting elements 110 and 120 are light (laser light), and the emitted light is emitted. The light receiving unit 130 (photosensitive element 131) is used as a detection unit for detecting the light. However, the present invention is not limited to this, and a sound (for example, an ultrasonic wave) may be used as the wave. In this case, it is possible to cope with the problem by using a sound wave vibrator as the first and second emitting units and the detecting unit.

  Moreover, in the said 1st Embodiment, when calculating the volume of the fuel tank 10, it is good also as what grasps | ascertains the magnitude of the volume of a fuel by the magnitude of the position H of a liquid level as what was abbreviate | omitted.

10 Fuel tank (container)
DESCRIPTION OF SYMBOLS 11 Bottom part 100, 100A Liquid level detection apparatus 110 1st light emitting element (1st emission part)
120 2nd light emitting element (2nd emission part)
130 Light receiver (detector)
140 Calculation unit 150 Warning unit

Claims (4)

A liquid level detection device for detecting a position (H) of a liquid level of a liquid stored in a container (10),
A first launch that launches a first wave in a direction from the predetermined position (O) of the bottom surface portion (11) toward the liquid surface at a predetermined angle (θ1) with the bottom surface portion (11) of the container (10). Part (110),
A second wave is emitted in a direction opposite to the first wave, in a direction from the predetermined position (O) toward the liquid surface at a predetermined angle (θ1) with the bottom surface portion (11). Two launchers (120),
The first wave position (C) that is disposed on the bottom surface portion (11), reflects on the liquid surface and reaches the bottom surface portion (11), and reflects on the liquid surface and transmits the bottom surface portion (11). ) To detect the position (F) of the second wave leading to
Based on the predetermined angle (θ1), the position (C) of the first wave, and the position (F) of the second wave, the position (H) of the liquid level and the bottom surface part (11) And a calculation unit (140) for calculating a relative inclination (θ2, θ3) of the liquid level with respect to the liquid level.   The liquid level detection device according to claim 1, wherein the first wave and the second wave are light.   The calculation unit (140) is based on the position characteristics (H) of the liquid level, the relative inclinations (θ2, θ3) of the liquid level, and the shape characteristics related to the container (10) that are grasped in advance. The liquid level detection device according to claim 1, wherein the volume of the liquid is calculated.   The liquid level detection according to claim 3, wherein the calculation unit (140) activates a warning unit (150) that warns a user when the volume of the liquid falls below a predetermined volume. apparatus.

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