KR100244902B1 - Air flow speed sensor element and its measurement circuit - Google Patents

Air flow speed sensor element and its measurement circuit Download PDF

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Publication number
KR100244902B1
KR100244902B1 KR1019970016906A KR19970016906A KR100244902B1 KR 100244902 B1 KR100244902 B1 KR 100244902B1 KR 1019970016906 A KR1019970016906 A KR 1019970016906A KR 19970016906 A KR19970016906 A KR 19970016906A KR 100244902 B1 KR100244902 B1 KR 100244902B1
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South Korea
Prior art keywords
thermistor
resistor
air flow
flow rate
resistance
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KR1019970016906A
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Korean (ko)
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KR970059740A (en
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은탁
김광진
박태원
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이종구
한국생산기술연구원
박태원
주식회사엔테크
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    • 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
    • G01P5/08—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect
    • G01P5/083—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect by using electronic circuits for measuring the dynamoelectric effect
    • 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
    • G01F1/6986—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters with pulsed heating, e.g. dynamic methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4073—Composition or fabrication of the solid electrolyte
    • G01N27/4074—Composition or fabrication of the solid electrolyte for detection of gases other than oxygen
    • 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
    • G01P5/14—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring differences of pressure in the fluid
    • G01P5/16—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring differences of pressure in the fluid using Pitot tubes, e.g. Machmeter
    • G01P5/165—Arrangements or constructions of Pitot tubes

Abstract

본 발명은 공조장치에 사용되어 덕트내를 흐르는 공기의 유속이나 유량을 검출하는 벌크형 공기유속 센서소자 및 그 측정회로에 관한 것으로써, 공기유속 센서소자의 한 구성요소인 발열부인 저항체(20)이 특정온도구간에서 매우 큰 정온도계수값을 갖는 써미스터(20')이다. 저항체(20)인 정온도계수 써미스터(20')와, 정전압을 인가하는 전원(60)과, 이 써미스터에 직렬로 연결되어 전류값을 감지하는 기준저항(70)과, 상기 기준저항의 양단에 연결되어 써미스터의 저항과 소모된 전기적 에너지의 크기를 계산하는 전류-유속계산기(80)으로 이루어진 측정회로이다.The present invention relates to a bulk type air flow sensor device for measuring the flow rate or flow rate of air flowing in a duct used in an air conditioner, and a measuring circuit thereof, wherein the resistor 20, which is a heat generating unit, is a component of the air flow sensor device. It is a thermistor 20 'having a very large positive temperature coefficient value in a specific temperature section. A constant temperature coefficient thermistor 20 ', which is a resistor 20, a power supply 60 for applying a constant voltage, a reference resistor 70 connected in series with the thermistor for sensing a current value, and both ends of the reference resistor. It is connected to the measurement circuit consisting of a current-flow calculator (80) for calculating the resistance of the thermistor and the amount of electrical energy consumed.

따라서, 본 발명에 의하면, 공기유속 센서소자의 저항체(발열부)로 이용되는 정온도계수 써미스터는 온도가 자기제한적이기 때문에 작은 유속에서도 열손상의 위험 없이 정전압 구동이 가능하므로 측정회로를 단순화시킬 수 있다. 또한, 작은 온도변화에도 큰 저항값의 변화가 생기므로 센서의 감도가 매우 커서 높은 측정 정밀도를 얻을 수 있다. 게다가 비저항이 크므로 큰 체적의 벌크형태로 제작이 가능하고, 내구성이 크고, 제작비용이 낮을 뿐만 아니라, 측정저항의 열용량이 커서 응답주파수가 낮은 대신 노이즈에 강해 공조장치등에 사용하기에 적합한 특성을 갖는다.Therefore, according to the present invention, since the constant temperature coefficient thermistor used as the resistor (heating unit) of the air flow sensor element is self-limiting, the constant voltage driving can be performed at a small flow rate without the risk of thermal damage, thereby simplifying the measurement circuit. have. In addition, since the change of the large resistance value occurs even at a small temperature change, the sensor's sensitivity is very large and high measurement accuracy can be obtained. In addition, due to the large specific resistance, it can be manufactured in bulk form of large volume, has high durability, low manufacturing cost, and large heat resistance of measuring resistance, so it is low in response frequency and is suitable for use in air conditioning equipment. Have

Description

공기유속 센서소자 및 그 측정회로Air velocity sensor element and its measuring circuit

본 발명은 공조장치의 덕트에 설치하여 대류에 의해 빼앗기는 열량과 인가된 전기적에너지의 평형관계에 의해 유량 또는 유속을 측정하는 벌크형 공기유속 센서소자 및 그 측정회로에 관한 것으로, 더욱 상세하게는 정온도계수를 가지며 발열온도가 자기제한적인 저항체 써미스터를 이용한 센서소자를 제조하여 작은 공기 유속에서도 열손상의 위험 없이 정전압 구동이 가능하므로 측정회로를 단순화시킬 수 있는 것이다.The present invention relates to a bulk air flow sensor device and a measuring circuit for measuring a flow rate or a flow rate by equilibrium relationship between the amount of heat deprived by convection and applied electrical energy installed in a duct of an air conditioning apparatus, and more specifically, a thermostat By manufacturing a sensor element using a resistor thermistor which has a number and a self-limiting heating temperature, it is possible to simplify the measurement circuit because the constant voltage can be driven without the risk of thermal damage even at a small air flow rate.

종래의 공조장치에 사용되는 공기유속 센서소자로서, 주로 피토튜브식, 핫와이어 또는 핫필름식을 사용하고 있다.As an air velocity sensor element used in a conventional air conditioner, a pitot tube type, hot wire or hot film type is mainly used.

상대적으로 저렴해서 많이 사용되고 있는 피토튜브식 공기유속 센서소자의 경우는, 측정방식상 별도의 공기배관과 함께 차압센서가 필요하여 측정장치가 복잡하고 부피가 클 뿐만 아니라, 유속이 차압의 제곱근에 비례하는 특성이 있어 유속의 측정정밀도가 사용된 차압센서의 정밀도 보다 낮아지는 문제점이 있다.In the case of the pitot tube type air flow sensor element, which is relatively inexpensive and widely used, a differential pressure sensor is required along with a separate air pipe in terms of the measurement method, so that the measuring device is complicated and bulky, and the flow rate is proportional to the square root of the differential pressure. There is a problem that the measurement accuracy of the flow rate is lower than the accuracy of the differential pressure sensor used.

핫와이어식 또는 핫필름식 공기유속 센서소자의 경우는, 측정정밀도는 상대적으로 우수하나, 사용되는 측정소자가 외경 10㎛내외의 선재이거나, 두께 수㎛의 박막으로, 선재의 경우는 내구성이 매우 취약하고, 필름의 경우는 제조비용이 높아지는 문제점이 있다.In the case of hot-wire type or hot film type air velocity sensor elements, the measurement accuracy is relatively high, but the measuring element used is a wire rod with an outer diameter of 10 μm or a thin film having a thickness of several μm. In the case of the film, there is a problem that the manufacturing cost increases.

또한, 사용된 재질이 백금이나 니켈등으로 작은 정온도계수를 갖고 있어 센서의 감도가 낮을 뿐만 아니라, 발열에 의한 소손을 막기 위해 도 1과 같은 정온도방식의 측정회로가 필수적이다. 이러한 정온도방식의 측정회로에서, 부호 100은 R1, R2, R3, Rx으로 구성하여, R1R2 = R3Rx의 조건이 성립할 때 전류계A의 전류가 0으로 되는 것을 이용하여 저항값을 측정하는 휘트스톤 브리지이다. 이 휘트스톤 브리지(100)의 한 구성요소로써, 저항체인 써미스터(Rx)가 사용되며, 이때 브리지(100)의 출력전압을 증폭기(200)으로 적분한 크기의 전압이 브리지(100)의 입력단에 인가되어 유속이 커짐에 따라 써미스터(Rx)의 온도가 내려가는 경우, 브리지(100)의 저항균형이 깨져 기준저항(300)의 양단에 출력전압이 발생하게 되고, 이 기준저항(300)의 전류값과 전압값으로부터 써미스터(Rx)에서 소모된 전기적 에너지의 크기를 전류-유속계산기(400)으로 계산하여 불평형일 때 브리지(100)에의 인가전압을 높여 상기 브리지(100)를 다시 평형상태로 만든다. 즉 써미스터(Rx)의 온도가 항상 일정하도록 제어되는 것으로, 이 회로는 제조비용이 높아지는 문제점이 있다.In addition, since the material used has a small constant temperature coefficient such as platinum or nickel, the sensitivity of the sensor is low, and the constant temperature measuring circuit as shown in FIG. 1 is essential to prevent burnout by heat generation. In this constant temperature measurement circuit, reference numeral 100 is composed of R1, R2, R3, and Rx, and the Wheatstone for measuring the resistance value by using the current of the ammeter A becomes zero when the condition of R1R2 = R3Rx is satisfied. It is a bridge. As a component of the Wheatstone bridge 100, a thermistor (Rx), which is a resistor, is used, and at this time, a voltage having the magnitude integrated by the output voltage of the bridge 100 to the amplifier 200 is applied to the input terminal of the bridge 100. When the temperature of the thermistor Rx decreases as the flow rate increases, the resistance balance of the bridge 100 is broken, and output voltages are generated at both ends of the reference resistor 300, and the current value of the reference resistor 300 is reduced. The amount of electrical energy consumed in the thermistor Rx is calculated from the overvoltage value by the current-flow calculator 400 to increase the applied voltage to the bridge 100 when it is unbalanced to bring the bridge 100 back into equilibrium. In other words, the temperature of the thermistor (Rx) is controlled to be constant at all times, this circuit has a problem that the manufacturing cost increases.

본 발명은 상기한 제반 문제점을 감안하여 이루어진 것으로, 기존의 공기유속 측정소자의 저항체로 사용되는 백금이나 니켈 대신에 대단히 큰 정온도계수를 가지며 발열온도가 자기제한적인 저항체인 써미스터를 이용함으로써 매우 간단한 공기유속/유량 측정회로를 제공하는데 있다.The present invention has been made in view of the above-described problems, and is very simple by using a thermistor which has a very large positive temperature coefficient and a heat generating temperature is a self-limiting resistor instead of platinum or nickel used as a resistor of the conventional air flow measurement device. To provide an air flow rate / flow rate measurement circuit.

제1도는 종래의 공기유속 센서소자의 측정회로도.1 is a measurement circuit diagram of a conventional air flow sensor device.

제2도는 본 고안의 공기유속 센서소자의 개략적인 사시도.Figure 2 is a schematic perspective view of the air flow sensor device of the present invention.

제3도는 본 고안의 공기유속 센서소자의 측정회로도.3 is a measurement circuit diagram of the air flow sensor device of the present invention.

제4도는 본 고안의 공기유속 센서소자에 사용되는 정온도계수 저항체 써미스터의 특성도.4 is a characteristic diagram of a constant temperature coefficient resistor thermistor used in the air flow sensor device of the present invention.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

10 : 센서소자 20 : 저항체10: sensor element 20: resistor

20': 써미스터 30 : 절연체20 ': Thermistor 30: Insulator

40 : 세라믹스부 50 : 전극40: ceramics 50: electrode

60 : 전원 70 : 기준저항60: power supply 70: reference resistance

80 : 전류유속계산기80: current flux calculator

상기한 과제를 달성하기 위한 본 발명의 구성 및 작용을 첨부도면에 의하여 상세히 설명하면 다음과 같다.When described in detail by the accompanying drawings the configuration and operation of the present invention for achieving the above object is as follows.

제2도는 본 고안의 공기유속 센서소자의 개략적인 사시도이고, 제3도는 본 고안의 공기유속 센서소자의 측정회로도이고, 제4도는 본 고안의 공기유속 센서소자에 사용되는 정온도계수 저항체 써미스터의 특성도이다.2 is a schematic perspective view of the air flow sensor device of the present invention, and FIG. 3 is a measurement circuit diagram of the air flow sensor device of the present invention, and FIG. 4 is a diagram of a constant temperature coefficient resistor thermistor used in the air flow sensor device of the present invention. It is a characteristic diagram.

제2도를 참조하여, 본 발명의 벌크형 공기유속센서(10)은, 특정온도 구간에서 대단히 큰 정온도계수(제4도 참조)값을 갖는 써미스터(20')인 저항체(20)과, 지지대인 절연체(30)을 동시에 성형 소결하여 접합시킨 일체형 세라믹스부(40)의 상하면에 전극(50)을 형성하고 있다.Referring to FIG. 2, the bulk type airflow sensor 10 of the present invention includes a resistor 20 and a support, which are thermistors 20 'having a very large positive temperature coefficient (see FIG. 4) in a specific temperature section. Electrodes 50 are formed on the upper and lower surfaces of the integral ceramic portion 40 in which the phosphorous insulator 30 is molded and sintered at the same time.

따라서, 본 발명의 구성에 의하면, 정온도계수 저항체(20)인 써미스터(20')를 이용한 공기유속 센서소자(10)은 일정온도 이상의 온도에서는 일종의 절연체와 같아서 더 이상의 전류가 흐르지 않아 이미 가열되었던 센서소자(10)이 냉각되고, 센서소자(10)의 온도가 일정온도 이하로 떨어지면 저항도 낮아져서 다시 센서소자에 전류가 흘러 온도가 올라가는 것으로써 써미스터의 특성에 의해 센서소자 스스로 온도를 자동제어하는 특유의 정온발열 조절기능을 갖고 있다Therefore, according to the configuration of the present invention, the air flow rate sensor element 10 using the thermistor 20 ', which is the constant temperature coefficient resistor 20, is a kind of insulator at a temperature above a certain temperature, and no more current flows, so that it is already heated. When the sensor element 10 is cooled and the temperature of the sensor element 10 falls below a predetermined temperature, the resistance is also lowered, so that the current flows to the sensor element and the temperature rises, thereby automatically controlling the temperature of the sensor element by the characteristics of the thermistor. It has a unique constant temperature heat regulation function

제3도는 정온도계수 저항체 써미스터를 이용한 공기유속 센서소자의 측정회로로서, 저항체(20)인 정온도계수 써미스터(20')와, 정전압을 인가하는 전원(60)과,이 써미스터에 직렬로 연결되어 전류값을 감지하는 기준저항(70)과, 상기 기준저항의 양단에 연결되어 써미스터의 저항과 소모된 전기적 에너지의 크기를 계산하는 전류-유속계산기(80)으로 이루어져 있다.3 is a measurement circuit of an airflow sensor element using a constant temperature coefficient resistor thermistor, which is connected to the thermistor in series with a constant temperature coefficient thermistor 20 'which is a resistor 20, a power supply 60 for applying a constant voltage, and the like. And a reference resistor 70 for sensing a current value, and a current-flow calculator 80 connected to both ends of the reference resistor to calculate the resistance of the thermistor and the amount of consumed electrical energy.

이 측정회로에 전전압을 인가하여 정온도계수 저항체인 써미스터(20')에 직렬로 연결된 기준저항(70)에 흐르는 전류값을 감지하고, 상기 기준저항(70) 양단의 전압을 측정하여 상기 정온도계수 저항체인 써미스터(20')에 인가된 전류값과 순전압을 얻고, 그것으로 부터 써미스터의 저항과 정온도계수 저항체인 써미스터(20')에서 소모된 전기적 에너기의 크기를 전류-유속계산기(80)으로 계산한다. 이때 소모된 전기적에너지와 대류에 의해 빼앗긴 열량간의 평형방정식은 다음식과 같다.Applying full voltage to the measuring circuit detects the current value flowing through the reference resistor 70 connected in series to the thermistor 20 ', which is a constant temperature coefficient resistor, and measures the voltage across the reference resistor 70. The current value and the forward voltage applied to the thermistor 20 ', which is a temperature coefficient resistor, are obtained, and the magnitude of the electrical energy consumed by the thermistor 20', which is the resistance of the thermistor and constant temperature coefficient resistor, is obtained from the current-flow calculator. Calculate as 80. The equilibrium equation between the electrical energy consumed and the heat lost by convection is given by

[식][expression]

전기적에너지 = 대류열량Electrical energy = convective heat

전기적에너지 = (써미스터에 인가된 순전압)·(써미스터를 통과한 전류)Electrical energy = (forward voltage applied to thermistor) · (current through thermistor)

대류열량 = (유효대류단면적)·(대류상수)·{(써미스터의 온도) - (공기의 온도)}Convection heat = (effective convection cross section), (convection constant), {(temperature of thermistor)-(temperature of air)}

대류상수 = (실험상수1) + (실험상수2)

Figure kpo00002
·√(공기의 속도) --- King's lawConvective Constant = (Experimental Constant 1) + (Experimental Constant 2)
Figure kpo00002
√ (speed of air) --- King's law

상기의 식에서 정온도계수 저항체인 써미스터(20')의 온도는 써미스터의 저항값으로부터 추정할 수 있으며, 두 개의 실험상수는 미리 실험적으로 구해질 수 있다. 그러므로 공기의 온도만 추가로 측정되면 공기의 속도를 알 수 있다.In the above equation, the temperature of the thermistor 20 ', which is a positive temperature coefficient resistor, can be estimated from the resistance value of the thermistor, and two experimental constants can be obtained experimentally in advance. Therefore, if only the temperature of the air is further measured, the speed of the air can be known.

이상과 같이, 본 발명의 측정센서 소자는 종래의 핫와이어 또는 핫필름와 비교하여 가장 큰 차이점은, 첫째로, 제4도와 같은 온도-저항특성을 갖는 정온도계수 저항체 써미스터을 이용한 공기유량/유속 측정센서 소자는 온도가 자기제한적이기 때문에 작은 유속에서도 오염에 의한 소손의 위험 없이 정전압 구동이 가능하므로 측정회로가 간단하다. 둘째로, 정온도계수 저항체 써미스터는 작은 온도변화에도 큰 저항값의 변화가 생기므로 센서의 감도가 매우 커서 높은 측정 정밀도를 얻을 수 있다. 셋째로, 정온도계수 저항체 써미스터는 비저항이 크므로 큰 체적의 벌크형태로 제작이 가능하고 내구성이 크며 제조비용이 낮다. 게다가 측정저항의 열용량이 커서 응답주파수가 낮은 대신 노이즈에 강해 공조장치등에 사용하기에 적절한 특성을 갖는 이점이 있는 것이다.As described above, the measurement sensor element of the present invention is the biggest difference compared to the conventional hot wire or hot film, first, air flow rate / flow rate sensor using a constant temperature coefficient resistor thermistor having a temperature-resistance characteristic as shown in FIG. Because the device is self-limiting in temperature, the measurement circuit is simple because the constant voltage can be driven even at a small flow rate without the risk of burnout. Secondly, since the constant temperature coefficient resistor thermistor has a large resistance value change even with a small temperature change, the sensor's sensitivity is very large and high measurement accuracy can be obtained. Thirdly, the constant temperature coefficient resistor thermistor has a large specific resistance, so that it can be manufactured in a bulk form of large volume, and it has high durability and low manufacturing cost. In addition, the heat capacity of the measuring resistor is large, and the response frequency is low, but it has the advantage of being suitable for use in an air conditioner because it is resistant to noise.

Claims (2)

발열부인 저항체(20)과, 지지대인 절연체(30)과, 전극(50)으로 구성된 공기유속 측정센서(10)에 있어서, 상기 저항체(20)이, 특정온도 구간에서 큰 정온도계수값을 갖는 써미스터(20')인 것을 특징으로 하는 공기유속 측정센서 소자.In the air flow rate measuring sensor 10 including the resistor 20 that is a heating unit, the insulator 30 that is a support, and the electrode 50, the resistor 20 has a thermistor having a large positive temperature coefficient value in a specific temperature section. And an air velocity measuring sensor element, characterized in that (20 '). 공기유속 측정센서 소자의 측정회로에 있어서, 저항체(20)인 정온도계수 써미스터(20')와, 정전압을 인가하는 전원(60)과, 이 써미스터에 직렬로 연결되어 전류값을 감지하는 기준저항(70)과, 상기 기준저항의 양단에 연결되어 써미스터의 저항과 소모된 전기적에너지의 크기를 계산하는 전류-유속계산기(80)으로 구성하여 유량 또는 유속을 측정하는 것을 특징으로 공기유속 측정센서 소자의 측정회로.In the measurement circuit of an air flow measurement sensor element, a constant temperature coefficient thermistor 20 ', which is a resistor 20, a power supply 60 for applying a constant voltage, and a reference resistor connected in series with the thermistor for sensing a current value And a current-flow calculator 80 connected to both ends of the reference resistor to calculate the magnitude of the thermistor's resistance and consumed electrical energy to measure the flow rate or flow rate. Measuring circuit.
KR1019970016906A 1997-05-01 1997-05-01 Air flow speed sensor element and its measurement circuit KR100244902B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20030018345A (en) * 2001-08-28 2003-03-06 한국생산기술연구원 Mass flow sensor and measuring apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20030018345A (en) * 2001-08-28 2003-03-06 한국생산기술연구원 Mass flow sensor and measuring apparatus

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