JPH0447250B2 - - Google Patents
Info
- Publication number
- JPH0447250B2 JPH0447250B2 JP57131019A JP13101982A JPH0447250B2 JP H0447250 B2 JPH0447250 B2 JP H0447250B2 JP 57131019 A JP57131019 A JP 57131019A JP 13101982 A JP13101982 A JP 13101982A JP H0447250 B2 JPH0447250 B2 JP H0447250B2
- Authority
- JP
- Japan
- Prior art keywords
- flow rate
- rate sensor
- sensor
- voltage
- flow
- 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
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
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Description
【発明の詳細な説明】
本発明は放熱型流量センサの駆動方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a heat radiation type flow sensor.
流体中におかれた金属抵抗体や感温半導体の抵
抗変化を検知することに基づき流体の流量を検出
するいわゆる放熱型流量センサは、厳密な流量測
定に適さないが、比較的構造が簡単で故障等が少
く使い易いという利点から、特に厳密な精度を要
求されない空調器等に広く用いられている。 So-called heat-dissipating flow rate sensors, which detect the flow rate of a fluid by detecting resistance changes in metal resistors or temperature-sensitive semiconductors placed in the fluid, are not suitable for exact flow measurement, but they have a relatively simple structure. It is widely used in air conditioners, etc., which do not require particularly strict accuracy, because it has the advantage of being easy to use and has few breakdowns.
しかしながら、従来の放熱型流量センサの駆動
方法では、温度によつて抵抗値変化の著しく異な
るサーミスタの如き流量センサを広い温度範囲
（流量範囲）にわたつて安全に駆動するのは困難
である。すなわち、従来の駆動方法は、例えば流
体中におかれたサーミスタに定電圧を印加して、
流量変化に基づくサーミスタの抵抗変化を検出し
て流量を算出するものであるから、流量が減少す
ることによりサーミスタの温度が上昇して、その
抵抗値が著しく低くなると、過大電流が流れてサ
ーミスタを焼損することがある。 However, with the conventional method of driving a heat dissipation type flow sensor, it is difficult to safely drive a flow sensor such as a thermistor whose resistance value changes significantly depending on temperature over a wide temperature range (flow rate range). In other words, the conventional driving method is to apply a constant voltage to a thermistor placed in a fluid, for example.
Since the flow rate is calculated by detecting the change in resistance of the thermistor based on the change in flow rate, if the temperature of the thermistor rises due to a decrease in flow rate and its resistance value drops significantly, an excessive current will flow and the thermistor will be damaged. It may burn out.
本発明は上記事情に鑑みてなされたもので、放
熱型流量センサを焼損させることなく安全に駆動
し得る放熱型流量センサの駆動方法を提供するこ
とを目的としている。 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for driving a heat radiation type flow rate sensor that can be safely driven without burning out the heat radiation type flow rate sensor.
そして、そのために本発明は流体中におかれた
流量センサの抵抗値が常に一定となるように流量
センサに電力を供給して駆動することを特徴とし
ている。 To this end, the present invention is characterized in that the flow rate sensor placed in the fluid is driven by supplying power so that the resistance value of the flow rate sensor is always constant.
以下、本発明に係る放熱型流量センサの駆動方
法の実施例について図面とともに説明する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a method for driving a heat-radiating flow rate sensor according to the present invention will be described with reference to the drawings.
第１図は本発明に係る方法の一実施例を説明す
るためのブロツク図、第２図は第１図に示した実
施例の各部の動作波形図である。図において１は
例えば、サーミスタ、白金測温抵抗体等よりなる
流量センサ、２は流量センサ１に直列接続される
抵抗、３は流量センサ１の端子間電圧と基準電圧
VSとの差を増幅して出力する差動アンプ、４は
比較器７の出力に応じて差動アンプ３の出力を通
過させるゲート回路、５はゲート回路４の出力を
与えられる積分器、６は計数回路１０の出力に同
期してのこぎり波を発生するのこぎり波発生回
路、７は積分器５の出力をのこぎり波発生回路６
の出力と比較する比較器、８は比較器７の出力に
応じて開閉されるスイツチング回路であり、この
スイツチング回路８は定電圧回路９の出力を断続
制御して抵抗２及び流量センサ１に与える。 FIG. 1 is a block diagram for explaining one embodiment of the method according to the present invention, and FIG. 2 is an operational waveform diagram of each part of the embodiment shown in FIG. In the figure, 1 is a flow sensor made of, for example, a thermistor or platinum resistance temperature sensor, 2 is a resistor connected in series with the flow sensor 1, and 3 is the voltage between the terminals of the flow sensor 1 and the reference voltage.
A differential amplifier that amplifies and outputs the difference from V S , a gate circuit 4 that passes the output of the differential amplifier 3 according to the output of the comparator 7, an integrator 5 that is given the output of the gate circuit 4; 6 is a sawtooth wave generation circuit that generates a sawtooth wave in synchronization with the output of the counting circuit 10; 7 is a sawtooth wave generation circuit 6 that generates a sawtooth wave in synchronization with the output of the integrator 5;
8 is a switching circuit that is opened and closed according to the output of the comparator 7, and this switching circuit 8 controls the output of the constant voltage circuit 9 intermittently and supplies it to the resistor 2 and the flow rate sensor 1. .
一方、１０は例えば、入力する所定周波数のク
ロツクパルス（C.P）を計数する16ビツトの計数
回路であり、この計数回路１０はカウント出力を
ラツチ回路１１に与えるとともに、計数の繰り返
し毎にリセツト信号をのこぎり波発生回路６に与
える。ラツチ回路１１は比較器７の出力が立下つ
たときの計数回路１０のカウント出力をラツチ
し、比較器７の出力の次の立下りまでの間前記カ
ウント出力である16ビツトのパラレルデータを出
力する。 On the other hand, 10 is, for example, a 16-bit counting circuit that counts input clock pulses (CP) of a predetermined frequency.This counting circuit 10 provides a count output to a latch circuit 11, and also sends out a reset signal every time counting is repeated. It is applied to the wave generation circuit 6. The latch circuit 11 latches the count output of the counting circuit 10 when the output of the comparator 7 falls, and outputs 16-bit parallel data as the count output until the next fall of the output of the comparator 7. do.
次に、上述した如き構成を有する本発明の実施
例の動作について説明する。 Next, the operation of the embodiment of the present invention having the above-described configuration will be explained.
いま、定電圧回路９の出力がスイツチング回路
８によつて断続制御されて例えば、第２図イに示
したようなデユーテイ比がＴ／T0で電圧ESなる
パルス出力でもつて流量センサ１が駆動されてい
るとする。このとき流量センサ１には同図ロに示
したように前記パルス出力と同じデユーテイ比で
電圧Vtの端子間電圧が表われる。そして、この
端子間電圧は差動アンプ３の一方入力として与え
られ、他方入力として予め与えられている基準電
圧VSとの間の誤差電圧が検出される。第２図ハ
は差動アンプ３から出力された誤差電圧を示す。
このときゲート回路４は、前記スイツチング回路
８に与えられている同図ニに示したデユーテイ比
Ｔ／T0のパルス信号を入力しているから、結局、
積分器５を介して比較器７に与えられる誤差電圧
は、流量センサ１の端子間電圧でVTを示す区間
についてのものになる。 Now, the output of the constant voltage circuit 9 is controlled intermittently by the switching circuit 8, so that, for example, the flow rate sensor 1 is controlled by the pulse output with the duty ratio T/T 0 and the voltage E S as shown in FIG. 2A. Suppose it is being driven. At this time, an inter-terminal voltage of voltage V t appears on the flow rate sensor 1 at the same duty ratio as the pulse output, as shown in FIG. This inter-terminal voltage is given as one input of the differential amplifier 3, and an error voltage between it and a reference voltage V S given in advance as the other input is detected. FIG. 2C shows the error voltage output from the differential amplifier 3.
At this time, the gate circuit 4 is inputting the pulse signal with the duty ratio T/T 0 shown in FIG.
The error voltage given to the comparator 7 via the integrator 5 is for the section in which the terminal-to-terminal voltage of the flow rate sensor 1 indicates VT .
一方、計数回路１０は計数の繰り返し周期Ｔご
とに第２図ホに示す如きリセツト信号をのこぎり
波発生回路６に与えているので、のこぎり波発生
回路６は同図ヘに示すような信号を比較器７に与
える。その結果、比較器７は、同図ヘに鎖線で示
した誤差電圧の直流成分Vt′と前記信号とを比較
して、同図トに示した如きデユーテイ比T′／T0
なるパルスを出力する。例えば、流量センサ１が
サーミスタ（負特性）の場合、流量センサ１の端
子間電圧Vtが基準電圧VSよりも高いとき、パル
ス幅T′は広くなる。従つて、前記デユーテイ比
のパルスによつてスイツチング回路８が駆動され
る結果、前述した誤差電圧は零になる方向に制御
される。 On the other hand, the counting circuit 10 gives a reset signal as shown in FIG. Give to container 7. As a result, the comparator 7 compares the DC component V t ' of the error voltage shown by the chain line in FIG .
Outputs a pulse of For example, when the flow rate sensor 1 is a thermistor (negative characteristic), the pulse width T' becomes wider when the voltage Vt between the terminals of the flow rate sensor 1 is higher than the reference voltage Vs. Therefore, as a result of the switching circuit 8 being driven by the pulse of the duty ratio, the error voltage mentioned above is controlled in the direction of becoming zero.
それ故、流量センサ１の抵抗値をRTとすると、
RT＝2RB・Vt／（ES−VT）
＝2RB・VS／（ES−VS）
と表わされるから、流量センサ１の抵抗値RTは
基準電圧VSに応じて一定値になる。また、抵抗
値RTを一定にすることは、流量センサ１の温度
を一定にすることに等しいから、流量を測定すべ
き流体の温度が一定のとき、流体と流量センサ１
との間の温度差が一定にすることができる。その
結果、流量センサ１の放熱量は、その流量センサ
１によつて消費される電力に比例することになる
から、流体の温度とともに流量センサ１の消費電
力を検知することに基づき流量センサ１の放熱量
に関連する流体流量を算出することができる。 Therefore, if the resistance value of the flow rate sensor 1 is R T , it can be expressed as R T = 2R B・V t / (E S − V T ) = 2R B・V S / (E S − V S ), The resistance value RT of the flow rate sensor 1 becomes a constant value according to the reference voltage V S. Furthermore, since keeping the resistance value R T constant is equivalent to keeping the temperature of the flow rate sensor 1 constant, when the temperature of the fluid whose flow rate is to be measured is constant, the fluid and the flow rate sensor 1
The temperature difference between can be kept constant. As a result, the amount of heat dissipated by the flow rate sensor 1 is proportional to the power consumed by the flow rate sensor 1. Therefore, the amount of heat released by the flow rate sensor 1 is proportional to the power consumed by the flow rate sensor 1. A fluid flow rate related to heat dissipation can be calculated.
ここで、流量センサ１の消費電力Ｐは、
Ｐ＝（Ｔ／T0）・（VT 2／RT）＝（Ｔ／T0）
・VS（ES−VS）／2RB
で表わされるから、デユーテイ比Ｔ／T0を検知
することにより算出できる。 Here, the power consumption P of the flow rate sensor 1 is P=(T/T 0 )・(V T 2 /R T )=(T/T 0 )・V S (E S −V S )/2R B Therefore, it can be calculated by detecting the duty ratio T/T 0 .
それ故、上述の実施例において、16ビツトの計
数回路１０のカウント出力を与えられるラツチ回
路１１は、第２図ニ及びトに示したように比較器
７の出力の立下つたときに計数回路１０のカンウ
ト出力をラツチする。従つて、ラツチ回路１１か
ら与えられる16ビツトのパラレルデータは前述し
たデユーテイ比Ｔ／T0に対応するものであるか
ら、ラツチ回路１１の出力データと流体温度とに
基づき、流体の流量を容易に算出することができ
る。 Therefore, in the above-described embodiment, the latch circuit 11 to which the count output of the 16-bit counting circuit 10 is applied is activated when the output of the comparator 7 falls, as shown in FIG. Latch count output of 10. Therefore, since the 16-bit parallel data given from the latch circuit 11 corresponds to the duty ratio T/T 0 described above, the fluid flow rate can be easily adjusted based on the output data of the latch circuit 11 and the fluid temperature. It can be calculated.
以上の実施例の説明より明らかなように、本発
明に係る放熱型流量センサの駆動方法は、流体中
におかれた流量センサの抵抗値が常に一定になる
ように流量センサを駆動しているので、流体の流
量が変化しても流量センサに流れる電流値は変わ
らない。それ故、本発明は、温度によつて抵抗値
変化の著しく異なる流量センサであつても焼損さ
せることなく安全に駆動することができる。 As is clear from the description of the embodiments above, the method for driving a heat-dissipating flow rate sensor according to the present invention drives the flow rate sensor so that the resistance value of the flow rate sensor placed in the fluid is always constant. Therefore, even if the fluid flow rate changes, the value of the current flowing through the flow rate sensor does not change. Therefore, according to the present invention, even a flow sensor whose resistance value changes significantly depending on temperature can be safely driven without burning out.
第１図は本発明に係る方法の一実施例を説明す
るためのブロツク図、第２図は第１図に示した実
施例の各部の動作波形図である。
１……流量センサ、２……抵抗、３……差動ア
ンプ、４……ゲート回路、５……積分器、６……
のこぎり波発生回路、７……比較器、８……スイ
ツチング回路、９……定電圧回路、１０……計数
回路、１１……ラツチ回路、VS……基準電圧、
CP……クロツクパルス。
FIG. 1 is a block diagram for explaining one embodiment of the method according to the present invention, and FIG. 2 is an operational waveform diagram of each part of the embodiment shown in FIG. 1...Flow rate sensor, 2...Resistor, 3...Differential amplifier, 4...Gate circuit, 5...Integrator, 6...
Sawtooth wave generation circuit, 7... Comparator, 8... Switching circuit, 9... Constant voltage circuit, 10... Counting circuit, 11... Latch circuit, V S ... Reference voltage,
CP...Clock pulse.
Claims (1)
その変化値に応じて流量センサに与える電力を制
御することにより、流体中におかれた流量センサ
の抵抗値を常に一定になるように流量センサを駆
動する方法であつて、前記流量センサに与える電
力の制御を、流量センサの端子間電圧と基準電圧
との誤差を検知し、その誤差電圧をこれに対応し
たデユーテイ比を有するパルスに変換して、この
パルスに従つてスイツチングを行うことによつて
断続的に行わせることを特徴とする放熱型流量セ
ンサの駆動方法。1 Detect minute changes in the resistance value of the flow sensor,
A method of driving a flow rate sensor such that the resistance value of the flow rate sensor placed in a fluid is always constant by controlling the electric power applied to the flow rate sensor according to the change value, the electric power applied to the flow rate sensor Power is controlled by detecting the error between the terminal voltage of the flow sensor and the reference voltage, converting the error voltage into a pulse with a corresponding duty ratio, and performing switching according to this pulse. A method of driving a heat dissipation type flow sensor, characterized in that the heat dissipation type flow sensor is driven intermittently.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57131019A JPS5919815A (en) | 1982-07-26 | 1982-07-26 | Driving method of radiation type flow rate sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57131019A JPS5919815A (en) | 1982-07-26 | 1982-07-26 | Driving method of radiation type flow rate sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5919815A JPS5919815A (en) | 1984-02-01 |
| JPH0447250B2 true JPH0447250B2 (en) | 1992-08-03 |
Family
ID=15048091
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57131019A Granted JPS5919815A (en) | 1982-07-26 | 1982-07-26 | Driving method of radiation type flow rate sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5919815A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04129914U (en) * | 1991-05-22 | 1992-11-30 | 丸喜金属株式会社 | Locking device for fasteners |
| CN114440998B (en) * | 2021-12-20 | 2024-07-23 | 重庆川仪自动化股份有限公司 | Fluid mass flow measuring circuit and fluid mass flow meter |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5543447A (en) * | 1978-09-22 | 1980-03-27 | Hitachi Ltd | Hot-wire type flow rate measuring device |
-
1982
- 1982-07-26 JP JP57131019A patent/JPS5919815A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5919815A (en) | 1984-02-01 |
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