JPH0617809B2 - Air flow meter - Google Patents
Air flow meterInfo
- Publication number
- JPH0617809B2 JPH0617809B2 JP63026327A JP2632788A JPH0617809B2 JP H0617809 B2 JPH0617809 B2 JP H0617809B2 JP 63026327 A JP63026327 A JP 63026327A JP 2632788 A JP2632788 A JP 2632788A JP H0617809 B2 JPH0617809 B2 JP H0617809B2
- Authority
- JP
- Japan
- Prior art keywords
- air flow
- heating resistor
- resistor
- bypass passage
- flow meter
- 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.)
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、空気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 an air flow meter.
従来より、例えば内燃機関等の分野においては、吸入空
気量を測定する手段として発熱抵抗体を用いた空気流量
計が使用されている。この種の空気流量計には、種々の
形式のものがある。この中で、例えば特開昭59−190624
号公報等に開示される如く吸気系の主通路の一部にバイ
パス通路を設け、このバイパス通路内に空気流量測定用
の発熱抵抗体（熱線）及び温度補償用の感温抵抗体を配
置した方式のものは、通路径の小さなバイパスに発熱抵
抗体を設けるので、吸気通路そのものには発熱抵抗を設
ける方式に較べて、抵抗体ひいては空気流計の小形化を
図り得る。また、バイパス通路構造に工夫を施すことで
抵抗体への塵埃付着防止を図り得る等の利点を有してい
る。2. Description of the Related Art Conventionally, in the field of, for example, an internal combustion engine, an air flow meter using a heating resistor has been used as a means for measuring the amount of intake air. There are various types of air flow meters of this type. Among these, for example, JP-A-59-190624
A bypass passage is provided in a part of the main passage of the intake system as disclosed in Japanese Patent Laid-Open Publication No. 2003-242242, and a heating resistor (heat wire) for measuring an air flow rate and a temperature sensing resistor for temperature compensation are arranged in the bypass passage. In the case of the system, the heating resistor is provided in the bypass having a small passage diameter, so that the resistor and thus the air flow meter can be made smaller than the system in which the heating resistor is provided in the intake passage itself. Further, by devising the bypass passage structure, there is an advantage that dust can be prevented from adhering to the resistor.
この種の空気流量計は、吸入空気流（バイパス空気量）
の変化により発熱抵抗体の空気流に対する熱伝達度合ひ
いては抵抗値が変化しても、発熱抵抗体に所定温度を保
つように出力電流を流し、この電流の出力状態に基づき
空気量を測定しようとするものである。そのため、空気
量の変化に対応する発熱抵抗体の出力応答性を早めるこ
とが、空気流量計の性能を決めることになり、特に自動
車エンジン制御等では、吸入空気量の変化に対応する応
答性の向上が強く要求されている。This kind of air flow meter, intake air flow (bypass air amount)
Even if the degree of heat transfer to the air flow of the heating resistor changes and the resistance value changes due to the change of the output current, an output current is applied to the heating resistor to maintain a predetermined temperature, and the amount of air is measured based on the output state of this current. To do. Therefore, accelerating the output responsiveness of the heating resistor that responds to changes in the air amount determines the performance of the air flow meter, and particularly in automobile engine control, etc., the responsiveness that responds to changes in the intake air amount There is a strong demand for improvement.
ところで、この種発熱抵抗体は次のような特性を有して
いる。これを、第５図及び第６図に基づき説明する。By the way, this kind of heating resistor has the following characteristics. This will be described with reference to FIGS. 5 and 6.
第５図は発熱抵抗体５（発熱抵抗体はアルミナ等の耐熱
絶縁筒に白金線等の熱線を巻装したり、或いは白金膜を
蒸着もの）の表面温度分布と空気流量（流速）との関係
を表わすものである。同図に示すように発熱抵抗体を通
過する空気流量が高流量になる程、発熱抵抗体の表面の
温度分布の変化が大きくなる。FIG. 5 shows the surface temperature distribution and the air flow rate (flow velocity) of the heating resistor 5 (the heating resistor is formed by winding a heating wire such as a platinum wire around a heat-resistant insulating cylinder such as alumina, or by depositing a platinum film). It represents a relationship. As shown in the figure, the higher the flow rate of air passing through the heating resistor, the greater the change in the temperature distribution on the surface of the heating resistor.
また、第６図は空気流量（流速）変化時の空気流量系
（発熱抵抗体５）の出力特性を示すものであり、実線は
空気流量の変化状態、点線は空気流量計の出力信号を示
すものである。しかして、空気流量によって発熱抵抗体
５の表面温度分布が変化すると、空気流量変化時の空気
流量計出力信号（以下、Ｈ／Ｗ信号とする）の応答は、
第６図の点線に示すように遅れが生じる。Ｈ／Ｗ信号の
遅れのうちＡ部は、発熱抵抗体の熱容量と回路定数によ
つて決まり、Ｂ部の遅れは、第５図の実線から破線への
温度分布の移動に要する時間である。従つて、Ｂ部の遅
れは、第５図の温度分布の変化が小さければ、その遅れ
も小さくなる。こゝで、温度分布の変化は、第５図の勾
配温度領域ｌｃで表わされる。ｌｃは、計算によれば
(1) 式となる。Further, FIG. 6 shows the output characteristics of the air flow rate system (heating resistor 5) when the air flow rate (flow velocity) changes. The solid line shows the change state of the air flow rate, and the dotted line shows the output signal of the air flow meter. It is a thing. When the surface temperature distribution of the heating resistor 5 changes depending on the air flow rate, the response of the air flow meter output signal (hereinafter referred to as H / W signal) when the air flow rate changes is
A delay occurs as shown by the dotted line in FIG. Of the delay of the H / W signal, the A part is determined by the heat capacity and the circuit constant of the heating resistor, and the B part delay is the time required to move the temperature distribution from the solid line to the broken line in FIG. Therefore, if the change in the temperature distribution shown in FIG. 5 is small, the delay in the B section also becomes small. Here, the change in the temperature distribution is represented by the gradient temperature region lc in FIG. lc is calculated
It becomes formula (1).
こゝで、ｄは発熱抵抗体プローブ（Ｈ／Ｗプローブ）の
直径、λはＨ／Ｗプローブの熱伝導率、ｈはＨ／Ｗプロ
ーブと空気流の熱伝達関数である。 Here, d is the diameter of the heating resistor probe (H / W probe), λ is the thermal conductivity of the H / W probe, and h is the heat transfer function of the H / W probe and the air flow.
また、Ｈ／Ｗプローブの長さｌに比較して上述のｌｃが
小さければ、温度分布の変化は小さく、第５図の遅れは
小となる。If the above-mentioned lc is smaller than the length l of the H / W probe, the change in temperature distribution is small and the delay in FIG. 5 is small.
従つて、これを式で表わせば、 となる。Therefore, if this is expressed by the formula, Becomes
以上からすれば、空気流量計の出力応答性を高めるため
には、発熱抵抗体の長さｌをできるだけ長くすることが
望ましいが、従来のバイパス型の空気流量計は、発熱抵
抗体がバイパス通路の空気流に対して直角に配置される
ため、その長さがバイパス通路径，支持ピンの位置等に
よつて制約を受けていた。From the above, in order to improve the output responsiveness of the air flow meter, it is desirable to make the length 1 of the heating resistor as long as possible. However, in the conventional bypass type air flow meter, the heating resistor has a bypass passage. Since it is arranged at a right angle to the air flow, the length was restricted by the bypass passage diameter, the position of the support pin, and the like.
本発明は以上の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、バイパス通路を大きくすることなく
発熱抵抗体の全長を増加させ、ひいては出力応答性，性
能の向上化を図り得る空気流量計を提供することにあ
る。The present invention has been made in view of the above points, and an object thereof is to increase the total length of a heating resistor without enlarging a bypass passage, which in turn can improve output responsiveness and performance. To provide an air flow meter.
上記目的は、この種のバイパス通路形の空気流量計にお
いて、バイパス通路の内部に配置される空気流量測定用
の発熱抵抗体を前記バイパス通路の空気流に対して斜め
配置に設定することで達成される。The above object is achieved in this type of bypass passage type air flow meter by setting a heating resistor for air flow rate measurement arranged inside the bypass passage in an oblique arrangement with respect to the air flow in the bypass passage. To be done.
以上のように、発熱抵抗体を空気流に対し従来の直角配
置から斜め配置に変更することにより、バイパス通路径
を変えなくとも発熱抵抗体の長さを増長させることがで
きる。そして、既述した(2) 式で示したように、発熱抵
抗体の長さｌを長くすることによつて、空気流量に対す
る温度分布の変化を小さくでき、ひいては温度分布変化
に起因する発熱抵抗体の出力応答性の遅れを小とし、そ
の結果、空気流量計の出力応答性を高めることができ
る。As described above, the length of the heating resistor can be increased without changing the bypass passage diameter by changing the conventional arrangement of the heating resistor from the conventional right angle arrangement to the air flow. Then, as shown in the equation (2), by increasing the length l of the heating resistor, it is possible to reduce the change in the temperature distribution with respect to the air flow rate, and in turn, the heating resistance caused by the change in the temperature distribution. The delay in the output response of the body can be reduced, and as a result, the output response of the air flow meter can be improved.
本発明の一実施例を第１図及び第２図に基づき説明す
る。An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
第１図は本発明の一実施例を示す縦断面図、第２図は第
１図のＡ方向からみたバイパス通路の部分断面図であ
る。FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the bypass passage as viewed from the direction A in FIG.
第１図において、１は内燃機関の吸気系の一部を構成す
るボデイで、ボデイ１の内部には、主吸気通路２とバイ
パス通路３が形成されている。In FIG. 1, reference numeral 1 denotes a body which constitutes a part of an intake system of an internal combustion engine. Inside the body 1, a main intake passage 2 and a bypass passage 3 are formed.
４は発熱抵抗体５及び温度補償用の感温抵抗体６を支持
するための支持体で、支持体４には、抵抗体支持用のピ
ン７ａ，７ｂ及び８ａ，８ｂが取付けられている。本実
施例における支持体４は真空の筒形を呈し、バイパス通
路３のある位置のボデイ１の壁部に嵌装される。また、
第２図に示すようにピン７ａ，７ｂで対をなし、ピン８
ａ，８ｂで対でなすものである。各対のピンのうち７
ａ，７ｂ及び８ａ，８ｂの夫々は、高さ位置をずらした
配置構造でバイパス通路３内に面し、ピン７ａ，７ｂを
介して発熱抵抗体５が空気流に対し斜め配置に支持さ
れ、また、ピン８ａ，８ｂを介して温度補償用抵抗体６
も空気流に対し斜め配置により支持される。Reference numeral 4 is a support for supporting the heating resistor 5 and the temperature-sensitive temperature-sensitive resistor 6 for temperature compensation. The support 4 is provided with resistors-supporting pins 7a, 7b and 8a, 8b. The support 4 in this embodiment has a vacuum cylindrical shape and is fitted to the wall portion of the body 1 at the position where the bypass passage 3 is located. Also,
As shown in FIG. 2, the pins 7a and 7b form a pair, and the pin 8
It is a pair of a and 8b. 7 out of each pair of pins
Each of a, 7b and 8a, 8b faces the inside of the bypass passage 3 with a dislocated height structure, and the heating resistor 5 is supported in an oblique arrangement with respect to the air flow via the pins 7a, 7b. Further, the temperature compensating resistor 6 is connected via the pins 8a and 8b.
Is also supported at an angle to the air flow.
発熱抵抗体５は、例えば、アルミナよりなる耐熱性絶縁
筒に白金線を巻装したり、白金膜を蒸着したものが使用
される。この発熱抵抗体５は、温度補償用抵抗体６及び
その他の抵抗要素と組んでブリツジを構成し、且つ駆動
回路９と接続される。駆動回路９は、発熱抵抗体６が所
定の発熱温度を保つような電流を流すもので、吸入空気
流量が変動すると、それに対応して熱伝達量ひいては抵
抗値，出力電流値が変化するため、この出力電流の変化
を信号（出力電圧）としてとり出すことにより、吸入空
気流量の測定が可能となる。温度補償用の抵抗体６は、
吸入空気温度を検出して、その空気温度の変化による吸
入空気流量の質量誤差分を補償する。As the heating resistor 5, for example, a heat-resistant insulating cylinder made of alumina in which a platinum wire is wound or a platinum film is vapor-deposited is used. The heating resistor 5 is combined with the temperature compensating resistor 6 and other resistance elements to form a bridge, and is connected to the drive circuit 9. The drive circuit 9 supplies a current such that the heat generating resistor 6 maintains a predetermined heat generation temperature, and when the intake air flow rate changes, the heat transfer amount and thus the resistance value and the output current value change correspondingly. By taking out the change of the output current as a signal (output voltage), the intake air flow rate can be measured. The resistor 6 for temperature compensation is
The intake air temperature is detected and the mass error of the intake air flow rate due to the change of the air temperature is compensated.
しかして本実施例では、発熱抵抗体５をバイパス通路３
の空気流に対し斜め配置となるよう設定しているので、
発熱抵抗体５の長さをバイパス通路の径を変更せずして
従来の発熱抵抗体の長さに較べて長くすることができ
る。具体的には、支持体４を真円形状にして、この支持
体面上に発熱抵抗体５及び温度補償用抵抗体６を上下に
平行配置する場合、ピンの取付位置等の制約を受けつつ
も、抵抗体５，６を空気流に対して４５゜の斜め配置と
する場合が抵抗体の長さを最も長くすることができる。
この４５゜斜め配置の場合には、第７図に示すような従
来の抵抗体配置方式（第７図はバイパス通路３に発熱抵
抗体５及び温度補償用抵抗体６を空気流に対し直角に配
置したもので、これらの抵抗体５，６を支持体４面上に
ピン７ａ，７ｂ，８ａ，８ｂを介して上下に平行配置し
た状態を表わしている）に較べて、抵抗体５，６の長さ
をバイパス径を変更することなく約１．４倍増加させる
ことができる。In the present embodiment, however, the heating resistor 5 is connected to the bypass passage 3
Since it is set to be diagonally arranged with respect to the air flow of
The length of the heating resistor 5 can be made longer than that of the conventional heating resistor without changing the diameter of the bypass passage. Specifically, when the support 4 is formed into a perfect circle and the heating resistor 5 and the temperature compensating resistor 6 are arranged in parallel vertically on the support surface, there are restrictions such as the mounting position of the pin. When the resistors 5 and 6 are arranged at an angle of 45 ° with respect to the air flow, the length of the resistors can be maximized.
In the case of this 45 ° oblique arrangement, the conventional resistor arrangement method as shown in FIG. 7 (in FIG. 7, the heat generating resistor 5 and the temperature compensating resistor 6 are arranged in the bypass passage 3 at right angles to the air flow). The resistors 5 and 6 are arranged in parallel in the vertical direction on the surface of the support 4 through the pins 7a, 7b, 8a and 8b). Can be increased about 1.4 times without changing the bypass diameter.
従つて、本実施例によれば、発熱抵抗体の長さｌを長く
することによつて、発明の「作用」の項でも既述したよ
うに、空気流量に対する発熱抵抗体の温度分布の変化を
小さくでき、ひいては温度分布変化に起因する発熱抵抗
体５の出力応答特性を遅れを小とし、その結果、空気流
量計の出力応答性を高めることができる。Therefore, according to the present embodiment, by increasing the length l of the heating resistor, the change in the temperature distribution of the heating resistor with respect to the air flow rate, as already described in the "Operation" section of the invention. It is possible to reduce the output response characteristic of the heating resistor 5 due to the change in the temperature distribution, and to delay the output response characteristic of the air flow meter.
第４図の点線は、本実施例の発熱抵抗体５を空気流に対
して配置角度θを変え、且つその時にとり得る発熱抵抗
体５の長さを変えて空気流量計の出力応答性を調べたも
ので、実線はその時の発熱抵抗体の感度特性を表わした
ものであり、第７図の従来例（現状）を１００％とし
て、これを基準の特性値を表わしている。しかして、第
４図の特性図に示すように、出力応答性は、発熱抵抗体
５の長さが比例し、その特性値も、抵抗体の長さが最大
長となり得る角度θ（約４５度）で出力応答性がピーク
値に至る。そして、第４図の斜線の領域に示すように角
度θが４５゜直前からほゞ45゜の範囲では、発熱抵抗体
の出力応答性を顕著に高め、しかも、抵抗体と感度特性
も支障のない範囲にとどめることができるので、この斜
線領域に抵抗体配置角度を設定することが最も好まし
い。The dotted line in FIG. 4 examines the output response of the air flow meter by changing the arrangement angle θ of the heating resistor 5 of this embodiment with respect to the air flow and changing the length of the heating resistor 5 that can be taken at that time. The solid line represents the sensitivity characteristic of the heating resistor at that time, and the characteristic value with this as a reference is represented by setting the conventional example (current state) in FIG. 7 to 100%. As shown in the characteristic diagram of FIG. 4, the output responsiveness is proportional to the length of the heating resistor 5, and the characteristic value also has an angle θ (about 45) at which the length of the resistor can be the maximum length. The output response reaches a peak value. As shown by the hatched area in FIG. 4, when the angle θ is in the range from just before 45 ° to approximately 45 °, the output response of the heating resistor is remarkably improved, and the resistor and sensitivity characteristics are also hindered. It is most preferable to set the resistor arrangement angle in this shaded area because it can be kept within a non-existing range.
更に、本実施例によればバイパス通路３の径を拡大させ
ることなく抵抗体の長さを増長できるので、装置全体を
大形化することなく空気流量計の性能を向上することが
できる。Further, according to this embodiment, the length of the resistor can be increased without increasing the diameter of the bypass passage 3, so that the performance of the air flow meter can be improved without increasing the size of the entire device.
なお、上記実施例では、発熱抵抗体５及び温度補償用抵
抗体６を平行な斜め配置状態とするが、第３図に示すよ
うに抵抗体５及び６を支持体４面上でクロスさせて斜め
配置状態としても、上記実施例同様の効果を奏し得る。
また、支持体４は真円とするが、これに代えて楕円形そ
の他種々の形状としてもよい。In the above embodiment, the heating resistor 5 and the temperature compensating resistor 6 are arranged in parallel and obliquely. However, as shown in FIG. 3, the resistors 5 and 6 are crossed on the support 4 surface. Even in the obliquely arranged state, the same effect as the above embodiment can be obtained.
Although the support 4 is a perfect circle, it may be an ellipse or other various shapes instead.
以上のように本発明によれば、バイパス通路を大きくす
ることなく発熱抵抗体の全長を増加させ、ひいては空気
流量計の出力応答性，性能の向上化を図ることができ
る。As described above, according to the present invention, it is possible to increase the overall length of the heating resistor without increasing the size of the bypass passage, and to improve the output response and performance of the air flow meter.
第１図は本発明の第１実施例を示す縦断面図、第２図は
第１図をＡ方向からみた部分断面図、第３図は本発明の
第２実施例を示す部分断面図、第４図は上記第１実施例
における発熱抵抗体の配置角度及び長さに対する出力応
答性，感度特性を表わす線図、第５図は発熱抵抗体の表
面温度分布特性図、第６図は発熱抵抗体の出力応答特性
図、第７図は熱線式空気流量計の従来例を示す部分断面
図である。 １……ボデイ、２……吸気系主通路、３……バイパス通
路、５……発熱抵抗体、６……温度補償用抵抗体。1 is a longitudinal sectional view showing a first embodiment of the present invention, FIG. 2 is a partial sectional view of FIG. 1 seen from the direction A, and FIG. 3 is a partial sectional view showing a second embodiment of the present invention. FIG. 4 is a diagram showing the output response and sensitivity characteristics with respect to the arrangement angle and length of the heating resistor in the first embodiment, FIG. 5 is a surface temperature distribution characteristic diagram of the heating resistor, and FIG. 6 is heat generation. FIG. 7 is an output response characteristic diagram of a resistor, and FIG. 7 is a partial cross-sectional view showing a conventional example of a hot wire air flow meter. 1 ... Body, 2 ... Intake system main passage, 3 ... Bypass passage, 5 ... Heating resistor, 6 ... Temperature compensation resistor.
Claims (2)
け、このバイパス通路の内部に空気流量測定用の発熱抵
抗体及び温度補償用の感温抵抗体とを配置してなる空気
流量計において、前記発熱抵抗体を前記バイパス通路の
空気流に対して斜め配置に設定してなることを特徴とす
る空気流量計。1. An air flow rate in which a bypass passage is provided in a part of a main passage of an intake system, and a heat generating resistor for measuring an air flow rate and a temperature sensitive resistor for temperature compensation are arranged inside the bypass passage. An air flowmeter, wherein the heating resistor is set obliquely to the air flow in the bypass passage.
体は、前記バイパス通路の空気流に対して略４５度の斜
め配置に設定してなる空気流量計。2. The air flow meter according to claim 1, wherein the heat generating resistor is set in an oblique arrangement at an angle of about 45 degrees with respect to the air flow in the bypass passage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63026327A JPH0617809B2 (en) | 1988-02-06 | 1988-02-06 | Air flow meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63026327A JPH0617809B2 (en) | 1988-02-06 | 1988-02-06 | Air flow meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01201117A JPH01201117A (en) | 1989-08-14 |
| JPH0617809B2 true JPH0617809B2 (en) | 1994-03-09 |
Family
ID=12190321
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63026327A Expired - Lifetime JPH0617809B2 (en) | 1988-02-06 | 1988-02-06 | Air flow meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0617809B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4909561B2 (en) * | 2005-10-19 | 2012-04-04 | 日立オートモティブシステムズ株式会社 | Heating resistor type air flow measuring device |
| JP4404104B2 (en) * | 2007-03-29 | 2010-01-27 | 株式会社デンソー | Air flow measurement device |
| JP5223708B2 (en) * | 2009-02-09 | 2013-06-26 | 株式会社デンソー | Air flow measurement device |
-
1988
- 1988-02-06 JP JP63026327A patent/JPH0617809B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01201117A (en) | 1989-08-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |