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WO2003093838A1 - Capteur de vitesse d'ecoulement - Google Patents

Capteur de vitesse d'ecoulement Download PDF

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Publication number
WO2003093838A1
WO2003093838A1 PCT/JP2003/005473 JP0305473W WO03093838A1 WO 2003093838 A1 WO2003093838 A1 WO 2003093838A1 JP 0305473 W JP0305473 W JP 0305473W WO 03093838 A1 WO03093838 A1 WO 03093838A1
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WO
WIPO (PCT)
Prior art keywords
temperature
resistance
elements
flow velocity
resistor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2003/005473
Other languages
English (en)
Japanese (ja)
Inventor
Tarou Nakata
Shoji Kamiunten
Seishi Nakano
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Azbil Corp
Original Assignee
Azbil Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Azbil Corp filed Critical Azbil Corp
Publication of WO2003093838A1 publication Critical patent/WO2003093838A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G01F1/692—Thin-film arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G01F1/698—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters
    • G01F1/699—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters by control of a separate heating or cooling element
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/10—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables
    • G01P5/12—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables using variation of resistance of a heated conductor

Definitions

  • the present invention relates to a flow rate sensor used for measuring a flow rate of a fluid such as a gas or a liquid.
  • the applicant has proposed in Japanese Patent Application Laid-Open No. 2-2595277 a flow rate sensor having a semiconductor fine processing configuration realizing high accuracy and high speed response.
  • the configuration of the flow velocity sensor disclosed in Japanese Patent Application Laid-Open No. 2255952/27 will be described with reference to FIGS. 6A and 6B.
  • the flow velocity sensor is formed on a base 1 made of single-crystal silicon or the like, and a void 2 is formed in the center of the base 1.
  • a thin film layer 3 is formed which is spatially isolated from the base 1 by the gap 2.
  • the thin film layer 3 is provided with a pair of slits 4 a and 4 b communicating with each other through the gap 2 at a predetermined interval. Further, between these slits 4a and 4b, there is provided a slit 5 extending in a direction orthogonal to a straight line connecting the slits 4a and 4b.
  • Two arrangement parts 6a and 6b are formed between b.
  • the disposition parts 6 a and 6 b are thermally insulated from each other by the slit 5.
  • a temperature measuring resistance element A 1 functioning as a heating element and a temperature sensor is formed in the disposing portion 6 a, and a temperature measuring resistance element B functioning as a heating element and a temperature sensor is similarly formed in the disposing portion 6 b. 1 is formed. Further, in the portion where the thin film layer 3 and the base 1 are in thermal contact with each other, that is, in the portion where the void portion 2 is not provided, an ambient temperature measuring resistance element C 1 whose resistance value changes with the ambient temperature is formed. Is done.
  • FIG. 7 is an electric circuit diagram of the flow velocity sensor proposed in Japanese Patent Application Laid-Open No. 2-259595.
  • the electric circuit of the flow velocity sensor is for measuring the flow velocity of the gas moving on the base 1, and includes a temperature difference detection circuit 100, a constant current circuit 200, and a switching circuit 300. Be composed.
  • the temperature difference detection circuit 100 is composed of a temperature measuring resistor element A1, B1 and a resistor R101, R102 having a larger resistance value. Circuit, an amplifier A101, A102 for amplifying the output voltage of the bridge circuit, a differential amplifier A103 for outputting a difference value between the output voltages of the amplifiers A101, A102, and resistors R103 to R109. Be composed.
  • the bridge circuit is supplied with a constant current from a constant current circuit 200 composed of an ambient temperature resistance element C1, transistors TR201 and TR202, and a resistor R201, and is composed of a transistor T301 and a resistor R301. It is intermittently driven by the switching circuit 300 that is operated.
  • the ambient temperature measuring resistance element C1 is provided to compensate for a change in the ambient temperature.
  • the resistance temperature elements Al and B 1 generate heat by the constant current supplied from the constant current circuit 200.
  • the resistances R101 and R102 have considerably larger resistance values than the resistance temperature measurement elements A1 and B1, it is assumed that the resistance temperature elements Al and B1 are driven by a constant current. Can be considered.
  • the resistance temperature element A1 located on the upstream side is cooled more strongly than the resistance element B1 located on the downstream side.
  • a temperature difference appears between the two resistance temperature measurement elements Al and B1
  • this temperature difference becomes a resistance change
  • the bridge circuit loses its balance, and the difference amplifier A 103 responds to the temperature difference. Output voltage.
  • the flow velocity sensor proposed in Japanese Patent Application Laid-Open No. 2-259527 is capable of detecting the flow velocity of a fluid with high accuracy because the resistance X-elements Al and B 1 are formed on the thermally insulated thin film layer 3. Has features. However, in this flow velocity sensor, when the flow velocity increases, the amount of heat energy taken from the downstream resistance temperature measuring element B 1 increases and the temperature decreases, and the upstream and downstream resistance temperature elements A 1, B 1 The difference in resistance value of 1 decreases. For this reason, in the flow velocity sensor proposed in Japanese Patent Application Laid-Open No. 2-259527, there is a problem that, when the flow velocity is increased, the sensitivity is reduced and measurement at a high flow velocity becomes difficult.
  • the temperature measurement resistance elements Al and B 1 are driven by a constant current, so that the average temperature of the temperature measurement resistance elements Al and B 1 and the thin film layer 3 in the vicinity thereof changes depending on the flow velocity. . That is, the series resistance of the resistance temperature elements A 1 and B 1 changes.
  • the series resistance of the resistance temperature elements A 1 and B 1 changes.
  • the resistance of the resistance temperature elements A 1 and B 1 and the thin Along with the thermal delay due to the heat capacity of the membrane layer 3, the temperature change due to the change in the calorific value of the resistance temperature measuring elements A 1 and B 1 interferes with this, resulting in a delay in the response speed. There was a problem.
  • the present invention has been made to solve the above problems, and has as its object to provide a high-speed response flow rate sensor capable of measuring a wide range of flow rates.
  • a flow rate sensor includes a base having an air gap, a thin film layer formed on a surface of the base on which the air gap is formed, and a serial connection formed on the thin film layer.
  • a flow rate calculating means for determining a flow velocity of the fluid based on a temperature difference between the first and second resistance temperature resistance elements obtained, and the first and second resistance temperature resistance elements;
  • Control means for controlling the average temperature of the second resistance temperature element to be always higher than the ambient temperature by a constant temperature.
  • the first and second temperature measuring resistance elements have functions as a heating element and a temperature sensor
  • the control means includes first and second temperature measuring resistance elements. This is to control the current flowing through the device.
  • one configuration example of the flow rate sensor according to the present invention further includes a heating unit disposed near the first and second resistance temperature elements having a function as a temperature sensor, and the control unit supplies the heating unit with the heating unit. The current is controlled.
  • one configuration example of the flow velocity sensor of the present invention further includes an ambient temperature sensor for measuring an ambient temperature unaffected by the flow of the fluid, and the first and second resistance temperature measuring elements and the ambient temperature sensor are each provided with a bridge circuit.
  • the control means controls the current flowing through the first and second resistance temperature measuring elements so as to keep the voltage difference between the respective middle points of the bridge circuit constant. It is.
  • the apparatus further includes an ambient temperature sensor that measures an ambient temperature unaffected by the flow of the fluid.
  • the first and second resistance temperature measuring elements and the ambient temperature sensor each constitute one side of a bridge circuit. The current flowing to the heating means may be controlled so that the voltage difference between the respective midpoints of the circuit is constant.
  • the apparatus further comprises at least one voltage follower circuit connected to both ends of the first and second resistance temperature elements, and the flow rate calculating means includes a first and a second resistance temperature element connected in series. The flow rate may be determined by comparing the divided voltage of the voltage between both ends and the voltage at the connection point of the first and second resistance temperature measuring elements.
  • the first and second temperature measuring resistance elements are arranged side by side at a predetermined interval in a flowing direction of the fluid in the thin film layer, and generate heat by flowing current. It was made.
  • one configuration example of the flow rate sensor of the present invention further includes a slit formed on the thin film layer between the first and second resistance temperature elements, and thermally insulating the first and second resistance temperature elements from each other. It is a thing.
  • the thin film layer is further provided with slits formed at predetermined intervals from each other.
  • the base includes a diaphragm, and the first and second temperature measurement resistance elements are formed on a surface of the diaphragm opposite to the flow path side, and
  • the calculating means measures the flow velocity of the gas moving on the side of the diaphragm opposite to the side on which the first and second temperature measuring resistance elements are formed.
  • a flow path forming member having a through hole for forming a flow path together with the base is further provided.
  • the flow velocity calculating means includes a bridge circuit, a differential amplifier circuit, and an output circuit, and the bridge circuit includes a resistor, a first resistance temperature element, and a second resistance element connected in series.
  • the differential amplifier circuit includes a first series circuit, and a second series circuit in which a resistor, a resistor, and an ambient temperature sensor are connected in series. And an operational amplifier connected to the non-inverting input terminal at the connection point between the resistor and the resistor, and the output terminal connected to the connection point between the resistor and the resistor.
  • An operational amplifier connected to the connection point of the first resistance temperature element and having an inverting input terminal and an output terminal connected thereto, one end connected to the output terminal of the operational amplifier, and one end connected to the other end of the resistance And the other end is grounded,
  • a non-inverting input terminal is connected to a connection point between the first resistance temperature element and the second resistance temperature element, and an inverting input terminal is provided with an operational amplifier connected to a connection point between the resistors.
  • a flow rate sensor includes a base having an air gap, a thin film layer formed on a surface of the base on which the air gap is formed, and a serial connection formed on the thin film layer.
  • the flow rate of the fluid is determined based on the temperature difference between the first and second resistance temperature elements and the first and second resistance temperature elements, which function as a heating element and a temperature sensor. And a current flowing through the first and second resistance temperature measuring elements so that the average temperature of the first and second resistance temperature elements is always higher than the ambient temperature by a constant temperature. And control means for performing such operations.
  • a base having a gap, a thin film layer formed on the surface of the base on which the gap is formed, and a temperature sensor formed on the thin film layer and connected in series
  • a first resistance temperature element and a second resistance temperature element having a function a heating means disposed in the vicinity of the first and second resistance temperature elements;
  • Flow velocity calculating means for calculating the flow velocity of the fluid based on the temperature difference, and controlling the current supplied to the heating means so that the average temperature of the first and second temperature measuring resistance elements is always higher than the ambient temperature by a constant temperature. It is provided with control means for controlling.
  • 1A and 1B are a plan view and a sectional view of a flow rate sensor according to a first embodiment of the present invention.
  • FIG. 2 is an electric circuit diagram of the flow velocity sensor of FIG.
  • FIG. 3 is a plan view of a flow velocity sensor according to a second embodiment of the present invention.
  • FIG. 4 is an electric circuit diagram of the flow velocity sensor of FIG.
  • FIG. 5 is a sectional view of a flow velocity sensor according to a third embodiment of the present invention.
  • 6A and 6B are a plan view and a cross-sectional view of a conventional flow velocity sensor.
  • FIG. 7 is an electric circuit diagram of a conventional flow velocity sensor.
  • FIG. 1A is a plan view of a flow velocity sensor according to a first embodiment of the present invention
  • FIG. 1B is a cross-sectional view taken along the line I-I of FIG. 1A
  • FIG. It is a circuit diagram.
  • the flow rate sensor of the present embodiment is formed on a base 101 made of single-crystal silicon or the like, and a void 102 is formed in the center of the base 101 by, for example, anisotropic etching. Further, on the base 101, a thin film layer (diaphragm member) 103 which is spatially isolated from the base 101 by the gap 102 is formed. Fluid such as gas passes over the thin film layer 103.
  • the thin film layer 103 is provided with a pair of slits 104 a and 104 b communicating with each other through the gap 102 at a predetermined interval. Further, between these slits 104a and 104b, there is provided a slit 105 extending in a direction perpendicular to a straight line connecting the slits 104a and 104b. Two arranging portions 106a and 106b are formed between the slits 104a and 104b along the flowing direction. The arrangement portions 106a and 106b are thermally insulated from each other by the slit 105.
  • a temperature measuring resistance element A functioning as a heating element and a temperature sensor is formed in the disposing portion 106a by a thin film forming technique.
  • a temperature measuring element functioning as a heating element and a temperature sensor is formed in the disposing portion 106b.
  • Resistive element B is formed by a thin film forming technique.
  • the resistance value changes depending on the ambient temperature (temperature of the fluid).
  • Ambient temperature sensor) C is formed by thin film formation technology.
  • 107 and 108 are pads for connecting both ends of the resistance temperature element A to an external electric circuit.
  • Reference numerals 109 and 110 are pads for connecting both ends of the resistance temperature element B to the electric circuit 20.
  • Reference numerals 111 and 112 denote pads for connecting both ends of the ambient temperature resistance measuring element C to the electric circuit 20.
  • the electric circuit 20 of the flow rate sensor according to the present embodiment measures the flow rate of the fluid moving on the base 101. And a bridge circuit 21, a differential amplifier circuit (control circuit) 22, and an output circuit 23.
  • the bridge circuit 21 includes a first series circuit in which a resistor R1, a resistance temperature element A and a resistance element B are connected in series, a resistance R2, a resistance R3, and an ambient temperature resistance element C. And a second series circuit connected in series, and is configured by connecting the first series circuit and the second series circuit in parallel.
  • the inverting input terminal is connected to the connection point of the resistor R1 and the resistance thermometer element A
  • the non-inverting input terminal is connected to the connection point of the resistor R2 and the resistor R3
  • the output terminal is It consists of an operational amplifier A1 connected to the connection point of the resistor R1 and the resistor R2.
  • the differential amplifier circuit 22 calculates the difference value between the potential V 1 at the connection point between the resistors R 2 and R 3 and the potential V 2 at the connection point between the resistance R 1 and the resistance element A.
  • the amplified output voltage Vo is applied to the connection point between the resistors R1 and R2 of the bridge circuit 21.
  • the output circuit 23 has an operational amplifier A 2 having a non-inverting input terminal connected to the connection point of the resistor R 1 and the resistance temperature measuring element A, and an inverting input terminal and an output terminal connected thereto, and one end having an operational amplifier A 2.
  • the resistor R5 connected to the output terminal of the resistor R5, one end is connected to the other end of the resistor R5, and the other end is grounded.
  • the operational amplifier A3 is connected to the connection point of the element B, and has an inverting input terminal connected to the connection point of the resistor R5 and the resistor R6.
  • the balance condition of the bridge circuit 21 is
  • Resistance value of resistance R 1 Z resistance value of resistance R 2 / (resistance value of resistance R 3 + resistance element of ambient temperature resistance C) Resistance value)
  • the resistance value of the resistor R2 the resistance value of the resistor R3 + the resistance value of the ambient temperature measuring resistance element C, and
  • Resistance value of resistance R 1 (resistance value of resistance element A + resistance value of resistance element B) at the set temperature
  • Resistance R 3 is the average temperature of resistance temperature elements A and B This is an adjustment resistor to maintain the temperature difference between the temperature and the temperature measurement resistance element C.
  • the temperature difference may not be kept constant, but may be changed, for example, such that this difference increases as the ambient temperature increases.
  • the bridge circuit 21 loses its balance and the potential V 1 at the connection point between the resistor R 2 and the resistor R 3 is reduced.
  • the differential amplifier circuit 22 raises the applied voltage Vo to the bridge circuit 21 in order to rebalance the bridge circuit 21.
  • the current supplied to the resistance thermometer elements A and B increases, so that the calorific value of the resistance thermometer elements A and B increases, and the resistance values of the resistance thermometer elements A and B increase. Balance occurs where the equilibrium condition is satisfied.
  • the resistance elements A and B are cooled, the resistance values of the resistance elements A and B decrease, and the potential V 2 at the connection point between the resistance R1 and the resistance element A is obtained.
  • the differential amplifier circuit 22 increases the voltage Vo applied to the bridge circuit 21. As a result, the calorific values of the resistance temperature elements A and B increase, the resistance values of the resistance temperature elements A and B increase, and the balance is established when the above-mentioned equilibrium condition is satisfied.
  • the differential amplifier circuit 22 detects the temperature detected by the temperature measuring resistance elements A and B (the average value of the temperatures detected by the elements A and B) by the ambient temperature temperature measuring resistance element C.
  • the resistance elements A and B generate heat so that the temperature is always higher than the ambient temperature.
  • the operational amplifier A2 forms a port follower.
  • the series circuit composed of the resistors R 5 and R 6 is connected to the series circuit composed of the resistance temperature elements A and B via the voltage follower A 2.
  • the voltage follower By using the voltage follower, the current flowing in the bridge circuit 21 is prevented from flowing out to the resistors R5 and R6.
  • the output voltage of the operational amplifier A3 becomes zero.
  • the output voltage when the flow velocity is 0 may be calibrated as the output voltage at the flow velocity 0, or an offset may be set so that the output voltage becomes an arbitrary voltage value when the flow velocity is 0. Good.
  • the resistance temperature elements A and B are cooled.
  • the resistance element A located upstream is cooled more strongly than the resistance element B located downstream, so that the resistance value of the resistance element A is the resistance of the resistance element B. Value.
  • the potential V 3 at the connection point between the resistance element A and the resistance element B rises, so that a difference occurs between the potential V 3 and the potential V 4 at the connection point between the resistors R 5 and R 6.
  • the operational amplifier A 3 outputs an output voltage corresponding to the flow velocity, that is, a voltage proportional to (V 3 ⁇ V 4).
  • the resistance temperature measuring element G regardless of the ambient temperature and the flow velocity, the resistance temperature measuring element G.
  • the resistance elements A and B generate heat so that the average value of the temperatures detected at points A and B is always higher than the ambient temperature by a certain amount.
  • the resistance of the resistance elements A and B increases. The difference in resistance value does not decrease and the sensitivity does not decrease.
  • a series circuit composed of the resistance temperature elements A and B and a series circuit composed of the resistances R5 and R6 are connected in parallel.
  • the terminal voltage of the resistor R5 (the output voltage of the port-follower A2) is correspondingly changed. ) Also changes to the same value as the voltage V2, so the reference potential (potential V4) of the RTD elements A and B is always adjusted to the value obtained by multiplying the voltage V2 by the predetermined ratio R6Z (R5 + R6). .
  • the potential difference V3-V4 is a value that reflects only the flow velocity, and a characteristic that increases almost linearly as the flow velocity increases is obtained.
  • FIG. 3 is a plan view of a flow rate sensor according to a second embodiment of the present invention
  • FIG. 4 is an electric circuit diagram of the flow rate sensor of FIG. 3.
  • a temperature-measuring resistance element A ′ functioning as a temperature sensor and a heating resistance element D functioning as a heating element are formed in the disposing portion 106a by a thin-film forming technique.
  • a temperature measuring resistance element B 'functioning as a temperature sensor and a heating resistance element E functioning as a heating element are formed in the disposition portion 106b by a thin film forming technique.
  • 107 and 108 are pads for connecting both ends of the resistance temperature measuring element A 'to the electric circuit 20a.
  • Reference numerals 109 and 110 denote pads for connecting both ends of the resistance temperature measuring element B 'to the electric circuit 20a.
  • 113 and 114 are pads for connecting both ends of the heating resistance element D to an external electric circuit 20a.
  • 115 and 116 are pads for connecting both ends of the heating resistor element E to the electric circuit 20a.
  • the bridge circuit 21a of this embodiment uses temperature-measuring resistance elements A 'and B' functioning as temperature sensors instead of the temperature-measuring resistance elements A and B functioning as a heating element and a temperature sensor.
  • a constant voltage Vs is applied to the connection point between the resistors R1 and R2 of the bridge circuit 21a, and the non-inverting input terminal is connected to the resistor R2 and the resistor R2.
  • the operational amplifier A4 is connected to the connection point of R3 and the inverting input terminal is connected to the connection point of the resistor R1 and the resistance temperature measuring element A '.
  • a heating resistor element D and a heating resistor element E are connected in series to the output terminal of the operational amplifier A4.
  • the operational amplifier A4, the heating resistor element D, and the heating resistor element E form a control circuit 22a.
  • Resistance value of resistance R1 / resistance value of resistance R2 / (resistance value of resistance R3 + resistance value of ambient temperature resistance element Mentor C resistance)
  • the operational amplifier A4 When a voltage Vs is applied to the bridge circuit 21a, the operational amplifier A4 generates a potential VI at a connection point between the resistor R2 and the resistor R3 and a potential V at a connection point between the resistor R1 and the resistance temperature measuring element A '. Amplify and output the difference voltage V 1 -V2 from 2.
  • the operational amplifier A4 outputs the output voltage To rise.
  • the current supplied to the heating resistor elements D and E increases, so that the amount of heat generated by the heating resistor elements D and E increases, and the resistance values of the temperature measuring resistor elements A ′ and B ′ increase. Balance when the equilibrium condition is satisfied.
  • the resistance values of the resistance elements A 'and B' decrease, and the potential V2 at the connection point between the resistance R1 and the resistance element A 'decreases.
  • the operational amplifier A4 increases the output voltage. As a result, the amount of heat generated by the heat generating resistance elements D and E increases, and the resistance values of the temperature measuring resistance elements A ′ and B ′ increase.
  • the resistance R3 is deleted and the resistance R2 is directly connected to the ambient temperature resistance element C.
  • the resistance elements A and B (A ', B By adding a resistor in parallel with the series circuit consisting of '), adjustment may be made to maintain the temperature difference between the RTD elements A' and B 'and the ambient temperature RTD element C.
  • the base 1 made of single-crystal silicon is used.
  • a base made of stainless steel, ceramic, sapphire, or the like may be used.
  • the average temperature of the two resistance temperature elements connected in series using the bridge circuit and the differential amplifier circuit is calculated from the ambient temperature measured by the ambient temperature resistance element.
  • the current is controlled using a microcomputer or the like so that the average temperature of the two temperature measuring resistance elements connected in series is higher than the ambient temperature by a certain temperature.
  • the voltage may be controlled.
  • the series resistance at the average temperature which is the setting target of the two temperature measuring resistance elements connected in series, is obtained from the relational expression between temperature and resistance, and the current or voltage applied to achieve the resistance is controlled. May be.
  • a general external temperature sensor may be used for measuring the ambient temperature.
  • the slit 105 may be omitted, and the wiring may be taken out from the middle point of one RTD, so that it may be used as substantially two RTDs. .
  • FIG. 5 is a sectional view of a flow rate sensor according to a third embodiment of the present invention, and the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals.
  • the elements A, B, and C are provided in the flow of the fluid.
  • the thin portion (diaphragm portion) 13 3 Elements A, B, and C are provided on the opposite side of the flow path side and not directly in contact with the fluid to be measured.
  • 13 1 is a flow path forming member made of stainless steel
  • 13 2 is a stainless steel base installed on the flow path forming member 13 1
  • 13 3 is a base 13 2
  • the thin part (diaphragm part) 134 formed on the base 132 is an electrical insulating film such as silicon oxide, silicon nitride, alumina or polyimide.
  • the flow path forming member 13 1 has two through holes 13 7 and 13 8 which form a flow path 13 6 of the fluid.
  • An oval concave portion 135 is formed in the center of the lower surface of the base 132, so that the surface side where the concave portion 135 is formed forms a thin portion (diaphragm portion) 133.
  • the concave portion 135 communicates with the through holes 133 and 138 at both ends.
  • the recesses 135 are preferably oval in order to smoothly flow the fluid, but are not limited to this, and may be rectangular or circular.
  • an electric insulating film 1 34 is formed over the entire surface, and the surface of the electric insulating film 1 34 has temperature-measuring resistance elements A and B and an ambient temperature temperature-measuring resistance element ( :
  • the pads 107 to 112 are formed in the same manner as in the first embodiment.
  • the electric circuit is as shown in Fig. 2.
  • the recesses 135 are formed.
  • An electric insulating film is formed on the entire bottom surface, and the temperature measuring resistance elements A and B and the pad are formed in the same manner on the surface of the electric insulating film. It may be formed in the same manner together with the pad via the electric insulating film in the portion, and the fluid may flow on the opposite surface.
  • the temperature-measuring resistance elements A and B instead of the temperature-measuring resistance elements A and B, the temperature-measuring resistance element C and the pads 107 to 112 of the first embodiment, the temperature-measuring resistance elements A ′ and A ′ of the second embodiment are used.
  • B ′ the ambient temperature resistance element C, the heating resistance elements D and E, and the pads 107 to 116 may be formed.
  • the electric circuit in this case is as shown in FIG.
  • the elements A, B, C, ⁇ ,., ⁇ ′, D, ⁇ ⁇ ⁇ ⁇ in the first to third embodiments of the present invention are all preferably formed of a platinum thin film or the like. It is not limited to this.
  • the average temperature of the first resistance temperature element and the second temperature resistance element (the average value of the temperatures detected by the first and second resistance temperature elements) is Since the voltage applied to the first resistance temperature element and the second resistance temperature element is controlled such that the temperature is always higher than the ambient temperature by a certain amount, the decrease in sensitivity is reduced even if the flow velocity increases. As a result, a wide range of flow velocities from low to high can be measured. Further, according to the present invention, since the temperatures of the first and second resistance temperature measuring elements can be kept constant, the response speed can be made faster than before. Further, by forming the output circuit from the third series circuit and the differential amplifier, it is possible to extract a value corresponding to the flow velocity of the fluid.
  • the flow sensor according to the present invention is suitable for measuring a wide range of flow velocities, particularly high flow velocities.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Measuring Volume Flow (AREA)

Abstract

L'invention concerne un capteur de vitesse d'écoulement comprenant un support de base doté d'un évidement, une couche à film mince formée sur la surface du support de base où l'évidement est formé, un premier élément de résistance mesurant la température et un second élément de résistance mesurant la température, formé sur la couche à film mince, reliés en série l'un avec l'autre, des moyens de calcul de la vitesse d'écoulement permettant de calculer la vitesse d'écoulement d'un fluide, en fonction d'une différence de température entre les premier et second éléments de résistance de mesure de la température, ainsi que des moyens de commande permettant de commander les premier et second éléments de résistance de mesure de la température, de manière que la température moyenne des premier et second éléments de résistance de mesure de la température soit toujours supérieure d'une quantité spécifiée par rapport à la température ambiante.
PCT/JP2003/005473 2002-05-02 2003-04-28 Capteur de vitesse d'ecoulement Ceased WO2003093838A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2002-130507 2002-05-02
JP2002130507A JP3802443B2 (ja) 2002-05-02 2002-05-02 流速センサ

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WO2017122090A1 (fr) * 2016-01-13 2017-07-20 Analog Devices Global Capteur d'écoulement d'air pour systèmes refroidis par ventilateur
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JP6322052B2 (ja) * 2013-10-28 2018-05-09 日本電産サンキョー株式会社 センサ装置
KR101581134B1 (ko) * 2013-10-28 2015-12-29 니혼 덴산 산쿄 가부시키가이샤 센서 장치
CN107228692A (zh) * 2017-06-30 2017-10-03 深圳龙电电气股份有限公司 一种水流流量的计量方法及其装置
CN107345826B (zh) * 2017-07-06 2020-12-18 中国科学院上海微系统与信息技术研究所 一种热式气体流量传感器及其制备方法
CN107328449B (zh) * 2017-07-06 2019-08-30 中国科学院上海微系统与信息技术研究所 一种热电堆式气体流量传感器及其制备方法
JP6867909B2 (ja) * 2017-08-02 2021-05-12 アズビル株式会社 熱式流量計
WO2019031329A1 (fr) * 2017-08-05 2019-02-14 株式会社村田製作所 Dispositif de mesure de la vitesse du vent et dispositif de mesure d'écoulement d'air
JP6940441B2 (ja) * 2018-03-27 2021-09-29 アズビル株式会社 熱式フローセンサ装置および流量補正方法
CN109211342B (zh) * 2018-09-05 2020-03-20 四方光电股份有限公司 一种气流流量计、mems硅基温敏芯片及其制备方法
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WO2017122090A1 (fr) * 2016-01-13 2017-07-20 Analog Devices Global Capteur d'écoulement d'air pour systèmes refroidis par ventilateur
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CN100405066C (zh) 2008-07-23
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CN1650175A (zh) 2005-08-03

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