JPS6159214A - Karman's vortex flowmeter - Google Patents

Karman's vortex flowmeter

Info

Publication number
JPS6159214A
JPS6159214A JP59182277A JP18227784A JPS6159214A JP S6159214 A JPS6159214 A JP S6159214A JP 59182277 A JP59182277 A JP 59182277A JP 18227784 A JP18227784 A JP 18227784A JP S6159214 A JPS6159214 A JP S6159214A
Authority
JP
Japan
Prior art keywords
vortex
karman
signal
fluid flow
signals
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.)
Pending
Application number
JP59182277A
Other languages
Japanese (ja)
Inventor
Yozo Mashima
要三 間嶋
Toru Mizuno
透 水野
Kazuma Matsui
松井　数馬
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.)
Denso Corp
Original Assignee
NipponDenso Co Ltd
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 NipponDenso Co Ltd filed Critical NipponDenso Co Ltd
Priority to JP59182277A priority Critical patent/JPS6159214A/en
Publication of JPS6159214A publication Critical patent/JPS6159214A/en
Pending legal-status Critical Current

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
    • G01F1/05—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 mechanical effects
    • G01F1/20—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 mechanical effects by detection of dynamic effects of the flow
    • G01F1/32—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 mechanical effects by detection of dynamic effects of the flow using swirl flowmeters
    • G01F1/325—Means for detecting quantities used as proxy variables for swirl
    • G01F1/3287—Means for detecting quantities used as proxy variables for swirl circuits therefor

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)

Abstract

PURPOSE:To enable accurate measurement of fluid flow rate, by dividing an electric signal issued from a Karman's vortex detector into 2 signals of different phases and obtaining a pulse signal synchronized to generation of the Karman's vortex by comparing these 2 signals. CONSTITUTION:A Karman's vortex flowmeter is constituted by vortex detector composed of a hot a hot wire 11 detecting the Karman's vortex formed corresponding to a fluid flow rate, circuit 30 amplifying an electric signal 20a issued from this, phase converting circuits 40, 50 issuing a signal 30a emitted from this circuit 30 as 2 signals 40a and 50a of different phases and comparing circuit 60, etc. issuing a pulse signal 60a synchronized to generation of the Karman's vortex 3 by comparing these signals 40a, 50a. Further, a phase difference of the output signals 40a, 50b of the phase converting circuits 40, 50 is generated in synchronization with generation of the Karman's vortex 3 and consequently, comparison of them enables stabilization of the pulse signal 60a issued even if the fluid flow rate is in an unstable condition. Thus, measurements of constant accuracy of fluid flow rate becomes available.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えば自動車用エンジンの吸入空気流量を測
定するカルマン渦流量計に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Karman vortex flowmeter for measuring the intake air flow rate of, for example, an automobile engine.

〔従来の技術〕[Conventional technology]

近年、自動車用エンジンにおいては吸入空気流量に対応
して燃料量を電磁式燃料噴射弁の開弁時間を制御し増減
する電子制御式のエンジンが採用されており、この場合
、吸入空気流量の正確な測定が求められ、種々の吸入空
気流量測定装置が開発されている。そして、その吸入空
気流量測定装置の一つとしてカルマン渦流量計がある。In recent years, automobile engines have adopted electronically controlled engines that increase or decrease the amount of fuel in response to the intake air flow rate by controlling the opening time of the electromagnetic fuel injection valve. Various types of intake air flow measuring devices have been developed to meet the demand for accurate measurement. A Karman vortex flow meter is one of the intake air flow rate measuring devices.

ここで従来のカルマン渦流量計について図面を用いて述
べる。Here, a conventional Karman vortex flowmeter will be described using drawings.

第２図はカルマン渦の発生状況を示す図であり、流体が
流通する流路管１の略中夫に流体流に対向して渦発生体
２が設けられており、この渦発生体２の下流側には流体
流量に比例した周波数のカルマン渦３が発生する。そし
て、このカルマン渦３の発生周波数を計測することによ
り、流体流量が測定される。FIG. 2 is a diagram showing the situation in which Karman vortices are generated. A vortex generator 2 is provided substantially in the middle of a flow path pipe 1 through which fluid flows, facing the fluid flow. A Karman vortex 3 with a frequency proportional to the fluid flow rate is generated on the downstream side. Then, by measuring the generation frequency of this Karman vortex 3, the fluid flow rate is measured.

カルマン渦３の発生周波数を計測する方式は種々あるが
、その一つとして渦発生体２の下流域に熱線１１を設け
る方式がある。これは、電流で定温度に加熱された熱線
１１が渦発生体２の下流側で発生するカルマン渦３によ
り冷却されて、その電流値がカルマン渦３の発生周波数
に同期して変化しており、この電流値変化の周波数を計
測することで、流体流量が測定できる。詳しくは、熱線
１１の電流値変化を電圧信号に変換し、この電圧信号を
比較回路にである比較電圧と比較することで、カルマン
渦３の発注に同期したパルス信号を得る。そしてこのパ
ルス信号の周波数を計数して、流体流量が測定される。There are various methods for measuring the generation frequency of the Karman vortex 3, and one of them is a method in which a hot wire 11 is provided in the downstream region of the vortex generator 2. This is because the hot wire 11 heated to a constant temperature by the current is cooled by the Karman vortex 3 generated downstream of the vortex generator 2, and the current value changes in synchronization with the generation frequency of the Karman vortex 3. By measuring the frequency of this current value change, the fluid flow rate can be measured. Specifically, by converting the change in the current value of the hot wire 11 into a voltage signal and comparing this voltage signal with a comparison voltage in a comparison circuit, a pulse signal synchronized with the ordering of the Karman vortex 3 is obtained. The fluid flow rate is then measured by counting the frequency of this pulse signal.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

上述した従来のカルマン渦流歪計のカルマン渦３の発生
周波数を計測する方式では、上記比較電圧として固定し
た比較電圧を用いており、計測する流体流が比較的安定
した状態にある時は、カルマン渦３も安定しており、熱
線１１から得られる電圧信号も安定しているが、流体流
が不安定な状態である時は、カルマン渦３の生成も不安
定となり、熱線１１から得られる電圧信号は第３図に示
すごとく低周波のゆらぎ成分を含んだ電圧信号Ａとなり
、このような電圧信号Ａを比較回路にて固定比較電圧Ｖ
Ｒと比較して出力されるパルス信号Ｂは、電圧ｆｇ号Ａ
に含まれたカルマン渦３の発生を示す信号成分の一部が
間引きされた信号となっ　−て示され、誤った流量信号
となるという問題点がある。In the method of measuring the generation frequency of the Karman vortex 3 in the conventional Karman eddy current strain meter described above, a fixed comparison voltage is used as the comparison voltage, and when the fluid flow to be measured is in a relatively stable state, the Karman vortex 3 The vortex 3 is also stable, and the voltage signal obtained from the hot wire 11 is also stable. However, when the fluid flow is unstable, the generation of the Karman vortex 3 becomes unstable, and the voltage signal obtained from the hot wire 11 becomes unstable. As shown in Fig. 3, the signal becomes a voltage signal A containing low frequency fluctuation components, and this voltage signal A is converted into a fixed comparison voltage V by a comparator circuit.
The pulse signal B output in comparison with R is the voltage fg A
There is a problem in that a part of the signal component indicating the occurrence of the Karman vortex 3 included in the flow rate is shown as a thinned out signal, resulting in an incorrect flow rate signal.

このような問題点に対して特開昭５５−１１３９１１号
公報に一解決手法が示されている。One solution to these problems is disclosed in Japanese Patent Laid-Open No. 113911/1983.

〔発明の目的〕[Purpose of the invention]

本発明の目的とするところは、測定する流体流が不安定
な状態であっても、カルマン渦の発生周波数に同期した
安定したパルス信号が得られ、正確な流量測定のできる
カルマン渦流量計を提供することにある。The object of the present invention is to provide a Karman vortex flowmeter that can obtain stable pulse signals synchronized with the frequency of Karman vortex generation and that can accurately measure flow rate even when the fluid flow to be measured is unstable. It is about providing.

〔問題点を解決するための手段〕[Means for solving problems]

上記の問題点を解決するために、本発明においては、流
体流路中に流体流に対向して設けられる渦発生体の近傍
に流体流量に応じて発生するカルマン渦を検出して電気
信号を出力する渦検出器と、この渦検出器より出力され
る電気信号を位相の異なる２個の信号とする位相変換回
路と、この位相変換回路より出力される２個の信号を入
力し、この２個の信号を比較してカルマン渦発生に同期
したパルス信号を出力する比較回路とを備えたカル　。In order to solve the above problems, the present invention detects a Karman vortex generated in accordance with the fluid flow rate near a vortex generator provided in a fluid flow path facing the fluid flow, and generates an electric signal. An output vortex detector, a phase conversion circuit that converts the electrical signal output from this vortex detector into two signals with different phases, and two signals output from this phase conversion circuit are input, and these two signals are input. and a comparison circuit that compares the signals and outputs a pulse signal synchronized with the generation of the Karman vortex.

マン渦流量計としている。It is a Mann vortex flowmeter.

〔実施例〕〔Example〕

以下、本発明の一実施例を図面を用いて説明する。 An embodiment of the present invention will be described below with reference to the drawings.

第２図に示すごとく、流路管１中には渦発生体２が流路
管１の略中央に図中矢印で示す流体流に対向して設けら
れており、この渦発生体２の下流側には流体流量に比例
した周波数でカルマン渦３が規則的に発生する。また渦
発生体２の下流側にはカルマン渦３の発生を検出する渦
検出器をなす白金等の径が５〜３０μｍ程度の細線の熱
線１１が設けられており、カルマン渦３による流速の変
化が熱線１１を冷却し熱線１１の電流値を増す。As shown in FIG. 2, a vortex generator 2 is provided in the flow pipe 1 at approximately the center of the flow pipe 1, facing the fluid flow indicated by the arrow in the figure, and downstream of the vortex generator 2. On the side, Karman vortices 3 are regularly generated at a frequency proportional to the fluid flow rate. Further, on the downstream side of the vortex generator 2, a thin hot wire 11 made of platinum or the like and having a diameter of about 5 to 30 μm is provided, which serves as a vortex detector for detecting the generation of the Karman vortex 3. cools the hot wire 11 and increases the current value of the hot wire 11.

この熱線１１は第１図図示の信号処理回路中のプリフジ
回路１０を他の固定抵抗とともに構成し、制御回路２０
の差動増幅！５２１に熱線１１の電流値変化によるブリ
ッジ回路１０の不平衡電圧が人力される。また差動増幅
器２１の出力信号はトランジスタ２２に入力されて、ト
ランジスタ２２は熱線１１の温度を一定温になるよう電
流供給を行う。そしてこのトランジスタ２２より出力さ
れる信号は熱線１１の冷熱に応じたものであり、カルマ
ン渦３の発生周波数と同期した渦信号２０ａである。This hot wire 11 constitutes the pre-fuji circuit 10 in the signal processing circuit shown in FIG.
Differential amplification! The unbalanced voltage of the bridge circuit 10 due to the change in the current value of the hot wire 11 is manually applied to 521 . Further, the output signal of the differential amplifier 21 is input to the transistor 22, and the transistor 22 supplies current to keep the temperature of the hot wire 11 constant. The signal outputted from the transistor 22 is a vortex signal 20a that corresponds to the cold heat of the hot wire 11 and is synchronized with the frequency at which the Karman vortex 3 occurs.

この制御回路２０の渦信号２０ａは増幅回路３０の交流
増幅器３１に入力されており、交流増幅器３１は所定の
振幅を有する信号３０ａを出力する。この信号３０ａは
位相変換回路４０及び５０に入力されて互いに異なる位
相を有する信号４０ａ及び５０ａとし゛て出力される。The vortex signal 20a of the control circuit 20 is input to the AC amplifier 31 of the amplifier circuit 30, and the AC amplifier 31 outputs a signal 30a having a predetermined amplitude. This signal 30a is input to phase conversion circuits 40 and 50 and output as signals 40a and 50a having mutually different phases.

この位相変換回路４０及び５０は各々抵抗Ｒ４、コンデ
ンサＣ４及び抵抗Ｒ５、コンデンサＣ５により構成され
る積分回路を用いており、その位相特性は第４図のＣ及
びＤに示される特性を有している。なお両値相変換回路
４０．５０の位相差θは５°〜ｌＯ。The phase conversion circuits 40 and 50 each use an integrating circuit composed of a resistor R4, a capacitor C4, a resistor R5, and a capacitor C5, and their phase characteristics have the characteristics shown in C and D in FIG. There is. Note that the phase difference θ of the two-value phase conversion circuit 40.50 is 5° to lO.

にすることが望ましい。It is desirable to

位相変換回路４０及び５０にて出力された信号４０ａ及
び５０ａは比較回路６０のコンパレータ６１に入力され
両信号を比較し、パルス信号６０ａに変換し出力する。The signals 40a and 50a output from the phase conversion circuits 40 and 50 are input to a comparator 61 of a comparison circuit 60, which compares both signals, converts them into a pulse signal 60a, and outputs the pulse signal 60a.

上記の構成において、流路管１中の流体流の状態が不安
定なものであると、前述したようにカルマン渦３のでき
方も不安定で、カルマン渦３の発生に伴なう流体の変位
も不規則となって、熱線１１にて検出され、制御回路２
０の渦信号２０ａは低周波のゆらぎ成分を含んだ信号と
なって、増幅回路３０の交流増幅器３１からの出力信号
３０ａは第５図のＡに示すような波形となる。In the above configuration, if the state of the fluid flow in the flow path pipe 1 is unstable, the formation of the Karman vortex 3 will also be unstable as described above, and the fluid flow accompanying the generation of the Karman vortex 3 will be unstable. The displacement also becomes irregular and is detected by the hot wire 11, and the control circuit 2
The zero vortex signal 20a becomes a signal containing low frequency fluctuation components, and the output signal 30a from the AC amplifier 31 of the amplifier circuit 30 has a waveform as shown in A in FIG.

第５図のＡに示される信号３０ａが位相変換回路４０及
び５０に入力され信号４０ａ及び５０ａとなり、信号４
０ａと信号５０ａとの間には所定の位相差θが与えられ
ており、第５図に示すごとく、同一の波形が位相差θ分
だけずれている。そしてこの信号４０ａ及び５０ａが比
較回路６０のコンパレータ６１に入力されると、第５図
に示されるように、信号５（ｌａが信号４０ａを上回っ
ている時を矩形波に変換しパルス信号６０ａを出力する
。The signal 30a shown in A in FIG. 5 is input to the phase conversion circuits 40 and 50 and becomes signals 40a and 50a,
A predetermined phase difference θ is given between signal 0a and signal 50a, and as shown in FIG. 5, the same waveform is shifted by the phase difference θ. When the signals 40a and 50a are input to the comparator 61 of the comparison circuit 60, as shown in FIG. Output.

従って、この場合信号４０ａが信号５０ａに対する比較
電圧の働きをしていることになり、信号５０ａと信号５
０ａの比較電圧の働きをする信号４０ａとがともに信号
３０ａ、つまりカルマン渦３の発生周波数に応じた信号
から作られているので、信号４０ａは信号５０ａを必ず
追従し、流体流の不安定状態による渦信号２０ａの低周
波のゆらぎ成分が無視できるようになり、カルマン渦３
の発生周波数に対応したパルス信号６０ａが出力される
ようになる。Therefore, in this case, the signal 40a acts as a comparison voltage for the signal 50a, and the signal 50a and the signal 5
Since the signal 40a, which acts as a comparison voltage of 0a, is created from the signal 30a, that is, a signal corresponding to the frequency of occurrence of the Karman vortex 3, the signal 40a always follows the signal 50a, and the fluid flow is in an unstable state. The low-frequency fluctuation component of the vortex signal 20a due to this can be ignored, and the Karman vortex 3
A pulse signal 60a corresponding to the generation frequency of is outputted.

なお、上述の実施例においては渦検出器として熱線１１
を用いていたが、カルマン渦３の発生を電気信号に変換
する検出器、例えば渦発生体２の下流側の圧力変動を電
気信号に変換する検出器等を用いてもかまわない。In addition, in the above-mentioned embodiment, the hot wire 11 is used as the vortex detector.
However, a detector that converts the generation of the Karman vortex 3 into an electrical signal, such as a detector that converts pressure fluctuations on the downstream side of the vortex generator 2 into an electrical signal, may also be used.

また、本実施例では積分回路を位相変換回路４９ａ、５
０ａに採用していたが微分回路を採用してもかまわない
、また積分・微分回路一段の位相変化９０°に対し周波
数の変化はほぼ１００倍であるから、広い範囲の周波数
域をカバーするためには必要に応じて回路を複数個設け
ればよい。Further, in this embodiment, the integrating circuit is replaced with phase converting circuits 49a and 5.
0a, but it is okay to use a differentiating circuit, and since the frequency change is almost 100 times compared to the 90° phase change of one stage of the integrating/differential circuit, in order to cover a wide frequency range. A plurality of circuits may be provided as necessary.

また、本実施例では熱線１１の配置する位置を渦発生体
２の下流側としていたが、カルマン渦３の発生状態が検
出される位置ならばどこであってもかまわない。Further, in this embodiment, the hot wire 11 is placed downstream of the vortex generator 2, but it may be placed anywhere as long as the state of generation of the Karman vortex 3 is detected.

〔発明の効果〕〔Effect of the invention〕

以上述べてきたように本発明においては、流体流路中に
流体流に対向して設けられる渦発生体の近傍に流体流量
に応じて発生ずるカルマン渦を検出して電気信号を出力
する渦検出器と、この渦検出器より出力される電気信号
を位相の異なる２個の信号とする位相変換回路と、この
位相変換回路より出力される２個の信号を入力し、この
２個の信号を比較してカルマン渦発生に同期したパルス
信号を出力する比較回路とを備えたカルマン渦流量計と
したことから、渦検出器からの電気信号が位相変換回路
に入力されると、位相変換回路にて出力される２個の信
号の間の位相差によるずれがカルマン渦発生に同期して
生じるので、このずれを比較回路が検出してカルマン渦
発生に応じたパルス信号を確実に出力するようになり、
また渦検出器より出力される電気信号に乱れがあっても
、位相変換回路より出力される２個の信号の位相差によ
るずれを比較回路にて検出するので、渦検出器より出力
される電気信号の乱れは無視され、従って流体流が不安
定な状態であっても比較回路からはカルマン渦発生に同
期した安定したパルス信号が得られるようになることよ
り、正確な流体流量測定が確実に得られるようになると
いう優れた効果がある。As described above, in the present invention, the vortex detection detects the Karman vortex generated in accordance with the fluid flow rate near the vortex generator provided in the fluid flow path facing the fluid flow, and outputs an electric signal. A phase conversion circuit converts the electric signal output from the vortex detector into two signals with different phases, and the two signals output from this phase conversion circuit are inputted, and these two signals are converted into two signals. Since the Karman vortex flowmeter is equipped with a comparison circuit that compares and outputs a pulse signal synchronized with the generation of Karman vortices, when the electrical signal from the vortex detector is input to the phase conversion circuit, the phase conversion circuit Since a shift due to the phase difference between the two signals output by the two signals occurs in synchronization with the generation of the Karman vortex, the comparator circuit detects this shift and reliably outputs a pulse signal in accordance with the generation of the Karman vortex. Become,
In addition, even if there is a disturbance in the electrical signal output from the vortex detector, the comparator circuit detects the shift due to the phase difference between the two signals output from the phase conversion circuit. Signal disturbances are ignored, so even if the fluid flow is unstable, the comparator circuit can provide a stable pulse signal synchronized with Karman vortex generation, ensuring accurate fluid flow measurement. It has the excellent effect of making it possible to obtain

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、本発明の一実施例の要部を示す回路図、第２
図は、流体流路内のカルマン渦発生状況を示す図、第３
図は、従来の検出方式を示す説明図、第４図は、第１図
中の位相変換回路の位相特性を示す特性図、第５図は、
第１図番部の出力波形を示す波形図である。 ｌ・・・流路管、２・・・渦発生体、３・・・カルマン
渦、１１・・・熱線、２０ａ・・・渦信号、４０．５０
・・・位相変換回路、４０ａ、５０ａ・・・位相変換さ
れた信号、６０・・・比較回路、６０ａ・・・パルス信
号。FIG. 1 is a circuit diagram showing the main parts of an embodiment of the present invention, and FIG.
Figure 3 shows the state of Karman vortex generation in the fluid flow path.
The figure is an explanatory diagram showing a conventional detection method, FIG. 4 is a characteristic diagram showing the phase characteristics of the phase conversion circuit in FIG. 1, and FIG.
FIG. 2 is a waveform diagram showing the output waveform of the numbered part in FIG. 1; l... Channel pipe, 2... Vortex generator, 3... Karman vortex, 11... Heat wire, 20a... Vortex signal, 40.50
... Phase conversion circuit, 40a, 50a... Phase-converted signal, 60... Comparison circuit, 60a... Pulse signal.

Claims (1)

【特許請求の範囲】 　流体流路中に流体流に対向して設けられる渦発生体の
近傍に流体流量に応じて発生するカルマン渦を検出して
電気信号を出力する渦検出器と、前記渦検出器より出力
される電気信号を位相の異なる２個の信号とする位相変
換回路と、 前記位相変換回路より出力される２個の信号を入力し、
この２個の信号を比較してカルマン渦発生に同期したパ
ルス信号を出力する比較回路とを具備したことを特徴と
するカルマン渦流量計。[Scope of Claims] A vortex detector that detects a Karman vortex generated in response to a fluid flow rate near a vortex generator provided in a fluid flow path facing the fluid flow and outputs an electric signal; a phase conversion circuit that converts the electrical signal output from the detector into two signals with different phases; and inputs the two signals output from the phase conversion circuit;
A Karman vortex flowmeter characterized by comprising a comparison circuit that compares these two signals and outputs a pulse signal synchronized with the generation of Karman vortex.
JP59182277A 1984-08-30 1984-08-30 Karman's vortex flowmeter Pending JPS6159214A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59182277A JPS6159214A (en) 1984-08-30 1984-08-30 Karman's vortex flowmeter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59182277A JPS6159214A (en) 1984-08-30 1984-08-30 Karman's vortex flowmeter

Publications (1)

Publication Number Publication Date
JPS6159214A true JPS6159214A (en) 1986-03-26

Family

ID=16115451

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59182277A Pending JPS6159214A (en) 1984-08-30 1984-08-30 Karman's vortex flowmeter

Country Status (1)

Country Link
JP (1) JPS6159214A (en)

Similar Documents

Publication Publication Date Title
Smits et al. Constant temperature hot-wire anemometer practice in supersonic flows: Part l: The normal wire
US4320650A (en) Flow rate measuring apparatus having vortex-generating element and hot wire element
US4463601A (en) Method and apparatus for measuring mass airflow
US4118780A (en) Technique for monitoring flow rate differences in water cooling conduit
JPS5858417A (en) Method and device for measuring quantity of fluid medium, which flow through fluid section and change in pulsatile form
US4386520A (en) Flow rate measuring apparatus
US4459847A (en) Vortex shedding device
US4285246A (en) Intake air flow rate detector
US6058785A (en) Noise reduction in a mass flow measuring system
KR900005880B1 (en) Thermo-water meter
US4026150A (en) Mass flow meter
US3894430A (en) Electromagnetic flowmeter
US3433066A (en) Magnetic flowmeter apparatus
JPS6159214A (en) Karman's vortex flowmeter
US4633717A (en) Thermocouple vacuum gauge
JP2656669B2 (en) Thermal air flow meter that also functions as a temperature measurement meter
EP0072033A2 (en) Air flow rate measuring device and an internal combustion engine using the same
Morrison Effects of fluid property variations on the response of hot-wire anemometers
JPS5826346Y2 (en) Karman vortex flow meter or current meter
EP0088827B1 (en) Flow velocity measuring apparatus
JPH0334652Y2 (en)
SU817592A1 (en) Thermoanemometric device for measuring gas flow rate
US3420109A (en) Readout for a vortex rate-of-turn sensor
JPS63206616A (en) Measurement of fluid temperature by thermal flowmeter
JPS6162819A (en) Karman vortex flowmeter