JPH0663800B2 - Heater temperature control circuit - Google Patents
Heater temperature control circuitInfo
- Publication number
- JPH0663800B2 JPH0663800B2 JP63272934A JP27293488A JPH0663800B2 JP H0663800 B2 JPH0663800 B2 JP H0663800B2 JP 63272934 A JP63272934 A JP 63272934A JP 27293488 A JP27293488 A JP 27293488A JP H0663800 B2 JPH0663800 B2 JP H0663800B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- heater
- temperature sensor
- downstream
- upstream
- 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.)
- Expired - Lifetime
Links
Landscapes
- Measuring Volume Flow (AREA)
- Control Of Temperature (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は流速計に関し、特に、流速計に使用するヒータ
の温度を制御する回路に関するものである。The present invention relates to a current meter, and more particularly to a circuit for controlling the temperature of a heater used in the current meter.
流速センサとしてのマイクロブリッジにおいては、チッ
プ基板上に作られた橋の中央にヒータを配置し、そのヒ
ータの両脇に上流側温度センサと下流側温度センサを配
置している。また、チップ基板上には基準温度センサを
配置している。流速計においては、上流側温度センサと
下流側温度センサに対してヒータの与える温度が被測定
流体の流速により異なることを利用して流速を測定す
る。上流側温度センサは流速が増加するとその温度が減
少、したがってその抵抗値が増加し、下流側温度センサ
は逆に流速が増加するとその温度が増加、したがってそ
の抵抗値が減少する。In a microbridge as a flow velocity sensor, a heater is arranged at the center of a bridge formed on a chip substrate, and an upstream temperature sensor and a downstream temperature sensor are arranged on both sides of the heater. A reference temperature sensor is arranged on the chip substrate. The velocity meter measures the flow velocity by utilizing the fact that the temperature given by the heater to the upstream temperature sensor and the downstream temperature sensor varies depending on the flow velocity of the fluid to be measured. The upstream temperature sensor decreases its temperature when the flow velocity increases, and therefore its resistance value increases, and conversely, the downstream temperature sensor increases its temperature when the flow velocity increases and therefore its resistance value decreases.
従来のヒータ温度制御回路を第２図に示す。同図におい
て、R1およびR2は温度測定ブリッジを構成するブリッジ
抵抗、RHは抵抗値rHを有するヒータ、RRは基準温度セン
サとしての抵抗、Ｕは演算増幅器、Ｑはトランジスタ、
N1はブリッジ抵抗R1ヒータRHの接続点、N2はブリッジ抵
抗R2と基準温度センサRRの接続点である。第２図におい
ては、正電位Ｖ＋がトランジスタＱを介してブリッジ抵
抗R1とR2の接続点に供給され、負電位Ｖ−がヒータRHと
基準温度センサRRの接続点に供給されている。A conventional heater temperature control circuit is shown in FIG. In the figure, R1 and R2 are bridge resistors forming a temperature measurement bridge, R H is a heater having a resistance value r H , R R is a resistance as a reference temperature sensor, U is an operational amplifier, Q is a transistor,
N1 is a connection point of the bridge resistance R1 heater R H , and N2 is a connection point of the bridge resistance R2 and the reference temperature sensor R R. In FIG. 2, the positive potential V + is supplied to the connection point of the bridge resistors R1 and R2 via the transistor Q, and the negative potential V − is supplied to the connection point of the heater R H and the reference temperature sensor R R. .
次に動作について説明する。各抵抗R1,R2およびRRの抵
抗値は一定に保たれている。従って、ヒータRHの抵抗値
rHが一定に保たれている限り、接続点N1と接続点N2の電
位は一定に保たれ、トランジスタＱには一定の電位が供
給される。この場合、接点N1の電位は接点N2の電位より
わずかに高く、トランジスタＱは一定バイアスの下にオ
ンとなっている。ここで、ヒータRHの温度が何らかの原
因で上昇すると、ヒータRHの抵抗値rHは減少し、接続点
N1の電位が接続点N2の電位より低くなり、トランジスタ
Ｑはオン抵抗が高くなるようにそのバイアスを制御され
る。これにより、ヒータRHへの供給電流は減少し、その
温度は低くなり、その抵抗値rHは高くなり、接続点N1の
電位が上昇する。このようにしてヒータRHへの供給電流
はヒータRHの温度が一定になるように制御される。Next, the operation will be described. The resistance value of each resistor R1, R2 and R R is kept constant. Therefore, the resistance value of the heater R H
As long as r H is kept constant, the potentials at the connection points N1 and N2 are kept constant and the transistor Q is supplied with a constant potential. In this case, the potential of the contact N1 is slightly higher than the potential of the contact N2, and the transistor Q is on under a constant bias. Here, if the temperature of the heater R H rises for some reason, the resistance value r H of the heater R H decreases and the connection point
The potential of N1 becomes lower than the potential of the connection point N2, and the bias of the transistor Q is controlled so that the on-resistance becomes high. As a result, the current supplied to the heater R H decreases, its temperature decreases, its resistance value r H increases, and the potential at the connection point N1 increases. Current supplied to the heater R H in this manner is controlled so that the temperature of the heater R H is constant.
ヒータRHの温度が何らかの原因で下がると、トランジス
タＱは上述した制御と逆の制御を受け、ヒータRHへの供
給電流は前よりも大きな或る値に制御され、その温度も
前よりも大きな或る値に制御され、ヒータ温度は一定に
保たれる。When the temperature of the heater R H is lowered for some reason, the transistor Q is subjected to the control reverse to the control described above, the supply current to the heater R H is controlled to a certain value larger than before, and the temperature thereof is also higher than before. It is controlled to a large value and the heater temperature is kept constant.
しかしながら、上述の従来回路においては、ヒータRHは
常に抵抗RRより高温になるため、抵抗値の経年変化がヒ
ータRHと抵抗RRとでは異なり、ヒータRHの方が早く劣化
が進む。第３図に示すヒータRHの温度特性グラフにおい
て初期特性を直線１、劣化の進んだ特性を直線２とする
と、第２図の回路では抵抗値が一定値になるよう制御さ
れるため、ヒータRHの温度は初期にTAであったものが、
経年変化によりTBになってしまう。温度センサ感度はヒ
ータRHの温度に比例しているため、ヒータRHの温度変化
は温度センサ感度の変化をもたらす。However, in the above-mentioned conventional circuit, since the heater R H is always higher in temperature than the resistance R R , the aging of the resistance value is different between the heater R H and the resistance R R, and the heater R H deteriorates faster. . In the temperature characteristic graph of the heater R H shown in FIG. 3, assuming that the initial characteristic is the straight line 1 and the deteriorated characteristic is the straight line 2, the resistance is controlled to be a constant value in the circuit of FIG. The temperature of R H was TA at the beginning,
It becomes TB due to aging. Since the temperature sensor sensitivity is proportional to the temperature of the heater R H, the temperature change of the heater R H results in a change in the temperature sensor sensitivity.
本発明はこのような点に鑑みてなされたものであり、そ
の目的とするところは、ヒータの温度制御においてヒー
タの特性変化の影響を受けない回路を得ることにある。The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a circuit that is not affected by changes in the characteristics of the heater in controlling the temperature of the heater.
このような課題を解決するために本発明は、流速計にお
けるヒータ温度制御回路において、上流側温度センサお
び下流側温度センサでヒータの温度を測定するための温
度測定ブリッジの一辺を構成し、上流側温度センサと下
流側温度センサの温度の平均値が一定になるようにヒー
タに供給する電力を制御する電力制御手段を設けるよう
にしたものである。In order to solve such a problem, the present invention configures one side of a temperature measurement bridge for measuring the temperature of a heater with an upstream temperature sensor and a downstream temperature sensor in a heater temperature control circuit in an anemometer, An electric power control means for controlling electric power supplied to the heater is provided so that the average value of the temperatures of the side temperature sensor and the downstream side temperature sensor becomes constant.
本発明によるヒータ温度制御回路においては、ヒータの
抵抗対温度の特性を使わないヒータ温度制御を行なう。In the heater temperature control circuit according to the present invention, heater temperature control is performed without using the resistance-temperature characteristic of the heater.
本発明は、上流側温度センサの抵抗値と下流側温度セン
サの抵抗値との和が流速にかかわらずヒータの温度によ
り定まることを利用したものである。これは、ヒータの
温度により上流側温度センサの温度と下流側温度センサ
の温度との和が定まることによる。流速の増加により上
流側温度センサの温度は低下し、下流側温度センサの温
度は上昇するが、その温度の和はほぼ一定に保たれる。
上述した温度の和は見方を変えれば温度の平均値とな
る。The present invention utilizes that the sum of the resistance value of the upstream temperature sensor and the resistance value of the downstream temperature sensor is determined by the temperature of the heater regardless of the flow velocity. This is because the temperature of the heater determines the sum of the temperature of the upstream temperature sensor and the temperature of the downstream temperature sensor. Although the temperature of the upstream temperature sensor decreases and the temperature of the downstream temperature sensor increases due to the increase of the flow velocity, the sum of the temperatures is kept substantially constant.
The above-mentioned temperature sum is an average value of the temperatures if the viewpoint is changed.
第１図は、本発明によるヒータ温度制御回路の一実施例
を示す回路図である。同図にいて、Ruは上流側温度セン
サとしての抵抗、RDは下流側温度センサとしての抵抗、
N3は抵抗R1と抵抗Ruとの接続点、U1は演算増幅器、C1は
コンデンサ、R3は抵抗、Q1はトランジスタであり、抵抗
R1、抵抗R2、基準温度センサRRおよび温度センサRuとRD
は温度測定ブリッジの各辺を構成する。また、演算増幅
器U1とトランジスタQ1は電力制御手段を構成する。な
お、第１図において第２図と同一部分又は相当部分には
同一符号が付してある。FIG. 1 is a circuit diagram showing an embodiment of a heater temperature control circuit according to the present invention. In the figure, Ru is a resistance as an upstream temperature sensor, R D is a resistance as a downstream temperature sensor,
N3 is a connection point between resistors R1 and Ru, U1 is an operational amplifier, C1 is a capacitor, R3 is a resistor, and Q1 is a transistor.
R1, resistor R2, reference temperature sensor R R and temperature sensors Ru and R D
Constitutes each side of the temperature measuring bridge. Further, the operational amplifier U1 and the transistor Q1 constitute power control means. In FIG. 1, the same or corresponding parts as those in FIG. 2 are designated by the same reference numerals.
本実施例においては、上流側温度センサRuと下流側温度
センサRDとを直列に接続してその両端の電圧をとること
により、温度センサRuとRDの抵抗値ruとrDの和を演算増
幅器U1の一方の入力とする。また、基準温度センサRRの
電圧をとることにより、基準温度センサRRの抵抗値rHを
演算増幅器U1の他方の入力とする。すなわち、演算増幅
器U1は抵抗値ruおよびrDの和と抵抗値rRとを比較し、そ
の値の差に応じた信号を出力する。In the present embodiment, the upstream side temperature sensor Ru and the downstream side temperature sensor R D are connected in series and the voltage across both ends thereof is taken to obtain the sum of the resistance values ru and r D of the temperature sensors Ru and R D. Use as one input of operational amplifier U1. Further, by taking a voltage reference temperature sensor R R, the resistance value r H of the reference temperature sensor R R and the other input of the operational amplifier U1. That is, the operational amplifier U1 compares the sum of the resistance values ru and r D with the resistance value r R, and outputs a signal according to the difference between the values.
演算増幅器U1の出力信号はトランジスタQ1で増幅され、
ヒータRHを駆動する。これによりヒータRHの熱は温度セ
ンサRuとRDに伝わり、ヒータRHの電流を制御することに
より、温度センサRuとRDの温度の加算値、換言すれば温
度の平均値を一定に保つ。ヒータRHからの熱が温度セン
サRu,RDに伝わるまでの無駄時間によりフィードバック
回路が不安定になることを防ぐため、位相補償用コンデ
ンサC1を演算増幅器U1の出力点と反転入力端子との間に
入れる。抵抗R3は電流制限用である。The output signal of the operational amplifier U1 is amplified by the transistor Q1,
Drives heater R H. Thus the heat of the heater R H is transmitted to the temperature sensor Ru and R D, by controlling the current of the heater R H, the sum of the temperature of the temperature sensor Ru and R D, the average value of the temperature in other words certain keep. In order to prevent the feedback circuit from becoming unstable due to the dead time until the heat from the heater R H is transmitted to the temperature sensors Ru and R D , connect the phase compensation capacitor C1 between the output point of the operational amplifier U1 and the inverting input terminal. Put in between. Resistor R3 is for current limiting.
第１図の回路で、センサ出力信号（流量信号）ａは温度
センサRu,RDの接続点から取り出す。周囲温度は基準温
度センサRRによって検出されるので、周囲温度が変わっ
ても、温度センサRu,RDの周囲温度からの温度上昇は常
に一定に保たれる。In the circuit of FIG. 1, the sensor output signal (flow rate signal) a is taken out from the connection point of the temperature sensors Ru and RD . Since the ambient temperature is detected by the reference temperature sensor R R , even if the ambient temperature changes, the temperature increase of the temperature sensors Ru and R D from the ambient temperature is always kept constant.
以上説明したように本発明は、上流側温度センサおよび
下流側温度センサでヒータの温度を測定するための温度
測定ブリッジの一辺を構成し、上流側温度センサと下流
側温度センサの温度の平均値が一定になるようにヒータ
に供給する電力を制御するようにしたことにより、従来
のようにヒータの抵抗対温度特性を使用する必要がなく
なったので、ヒータの特性変化の影響を受けないヒータ
温度制御ができる効果がある。As described above, the present invention constitutes one side of the temperature measurement bridge for measuring the temperature of the heater with the upstream temperature sensor and the downstream temperature sensor, and the average value of the temperatures of the upstream temperature sensor and the downstream temperature sensor. By controlling the electric power supplied to the heater so that the temperature becomes constant, it is no longer necessary to use the resistance-temperature characteristic of the heater as in the past, so the heater temperature that is not affected by the heater characteristic changes There is an effect that can be controlled.
また、上流側温度センサと下流側温度センサの温度の平
均値が一定に保たれることにより、ゴミの付着等により
ヒータの放熱状態が変わっても、流量に対する感度特性
の変動を防止できる効果がある。Further, since the average value of the temperatures of the upstream temperature sensor and the downstream temperature sensor is kept constant, even if the heat radiation state of the heater changes due to the adhesion of dust or the like, it is possible to prevent the fluctuation of the sensitivity characteristic with respect to the flow rate. is there.
第１図は本発明によるヒータ温度制御回路の一実施例を
示す回路図、第２図は従来のヒータ温度制御回路を示す
回路図、第３図は従来の回路における不具合を説明する
ためのグラフである。 R1,R2……ブリッジ抵抗、Ru……上流側温度センサ、RD
……下流側温度センサ、RR……基準温度センサ、N2,N3
……接続点、U1……演算増幅器、C1……コンデンサ、R3
……抵抗、Q1……トランジスタ、RH……ヒータ。FIG. 1 is a circuit diagram showing an embodiment of a heater temperature control circuit according to the present invention, FIG. 2 is a circuit diagram showing a conventional heater temperature control circuit, and FIG. 3 is a graph for explaining defects in the conventional circuit. Is. R1, R2 …… Bridge resistance, Ru …… Upstream temperature sensor, R D
...... Downstream temperature sensor, R R …… Reference temperature sensor, N2, N3
...... Connection point, U1 …… Operational amplifier, C1 …… Capacitor, R3
...... Resistance, Q1 ...... Transistor, RH ...... Heater.
Claims (1)
間にヒータを配置し、前記上流側温度センサと下流側温
度センサの前記ヒータによる温度が被測定流体の流速に
より異なることを利用して流速を測定する流速計におけ
る前記ヒータの温度を制御する回路において、前記上流
側温度センサおよび下流側温度センサは前記ヒータの温
度を測定するための温度測定ブリッジの一辺を構成し、
前記上流側温度センサと下流側温度センサの温度の平均
値が一定になるように前記ヒータに供給する電力を制御
する電力制御手段を備えたヒータ温度制御回路。1. A heater is arranged between an upstream temperature sensor and a downstream temperature sensor, and the temperature of the heater of the upstream temperature sensor and the temperature of the downstream temperature sensor varies depending on the flow velocity of a fluid to be measured. In the circuit for controlling the temperature of the heater in the anemometer for measuring the flow velocity, the upstream temperature sensor and the downstream temperature sensor constitute one side of a temperature measurement bridge for measuring the temperature of the heater,
A heater temperature control circuit including power control means for controlling power supplied to the heater so that an average value of temperatures of the upstream temperature sensor and the downstream temperature sensor becomes constant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63272934A JPH0663800B2 (en) | 1988-10-31 | 1988-10-31 | Heater temperature control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63272934A JPH0663800B2 (en) | 1988-10-31 | 1988-10-31 | Heater temperature control circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02120620A JPH02120620A (en) | 1990-05-08 |
| JPH0663800B2 true JPH0663800B2 (en) | 1994-08-22 |
Family
ID=17520802
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63272934A Expired - Lifetime JPH0663800B2 (en) | 1988-10-31 | 1988-10-31 | Heater temperature control circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0663800B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3955747B2 (en) * | 2001-08-22 | 2007-08-08 | 三菱電機株式会社 | Flow measuring device |
| JP5153996B2 (en) * | 2005-01-26 | 2013-02-27 | 日立オートモティブシステムズ株式会社 | Thermal flow meter |
| JP4836864B2 (en) | 2007-05-16 | 2011-12-14 | 日立オートモティブシステムズ株式会社 | Thermal flow meter |
| JP2019207111A (en) * | 2018-05-28 | 2019-12-05 | 株式会社Ｓｏｋｅｎ | Anemoscope |
-
1988
- 1988-10-31 JP JP63272934A patent/JPH0663800B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02120620A (en) | 1990-05-08 |
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