JPS58109816A - Air flow meter - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy during the pulsation, by opening the outlet of a by-pass line containing a hot wire in a slit form and rectangularly to an air flow path and linking the inlet and outlet of the by-pass line via a circular path. CONSTITUTION:The inlet of a by-pass line 4 containing a hot wire 5 for detection of air flow is opened in the direction same as the intake direction of a primary air flow path 2b. The outlet of the line 4 is opened in a slit form 7 and rectangularly to the intake direction. These inlet and outlet are linked to communicate with each other via a circular path 4b. As a result, the width is decreased for the opening 7 provided at the narrowest part of a Venturi part 3 having a low level of dynamic pressure, and at the same time the effect due to the intake pulsation is reduced. Therefore it is possible to detect the intake air flow rate with high accuracy even during the pulsation.

Description

【発明の詳細な説明】 本発明は内燃機関用の吸入空気流量検出装置に係り、特
に熱線を用いたエアフロメータに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air flow rate detection device for an internal combustion engine, and more particularly to an air flow meter using a hot wire.

バイパス通路に熱線を設けたエア７０メータにおいては
バイパス通路の出口で動圧を上、下で受けるので、エア
７０メータの出力は負の値とずれるような現象がある。An air 70 meter with a hot wire provided in the bypass passage receives dynamic pressure at the top and bottom at the outlet of the bypass passage, so there is a phenomenon in which the output of the air 70 meter deviates from a negative value.

本発明の目的は、特に脈動時の検出精度を向上させたエ
アフロメータを提供することにおる。An object of the present invention is to provide an air flow meter with improved detection accuracy, especially when pulsating.

第１．２図によって本発明の一実施例を説明する。エア
フロメータ１は、主空気通路２ｍ、２ｂとベンチエリ３
．バイパス通路４．縦通路４ｍ。An embodiment of the present invention will be explained with reference to FIG. 1.2. Air flow meter 1 has main air passages 2m and 2b and bench area 3.
．． Bypass passage 4. Vertical passage 4m.

横環状通路４ｂ、熱線エレメント５．熱線駆動回路６で
構成されている。バイパス通路４は、ベンチュリ３部に
開口分岐し、他端をベンチュリ３上流の主空気通路２ｂ
に開口している。熱線エレメント５はバイパス通路の縦
通路４ａに設けられ、熱線駆動回路６に接続されている
。Horizontal annular passage 4b, hot wire element 5. It is composed of a hot wire drive circuit 6. The bypass passage 4 opens and branches to the venturi 3, and the other end is connected to the main air passage 2b upstream of the venturi 3.
It is open to The hot wire element 5 is provided in the vertical passage 4a of the bypass passage, and is connected to the hot wire drive circuit 6.

計測される空気は、主空気通路２ｂ、ベンチュリ３．主
空気通路２ｍへと流れる。この時ベンチエリ部３は絞ら
れているため負の圧力が発生し、主空気通路部２ｂとの
圧力差によってバイパス通路４に空気流が生じる。この
空気流速を熱線エレメント５によって計測する。このこ
とはすでに周知の通シ、バイパス通路の流速を検出する
ことによって全体の空気流量が計量できる。The air to be measured is from the main air passage 2b, the venturi 3. Flows into the main air passage 2m. At this time, since the bench area 3 is constricted, negative pressure is generated, and an air flow is generated in the bypass passage 4 due to the pressure difference with the main air passage 2b. This air flow velocity is measured by the hot wire element 5. This is well known in the art, and by detecting the flow velocity in the bypass passage, the total air flow rate can be measured.

しかしながら、エンジン高負荷時には吸気脈動が生じる
。この際ベンチュリ最狭部に設けられたスリット状のバ
イパス出ロアにおいては動圧は小さくその影響を極力小
さくすることができる。However, when the engine is under high load, intake pulsation occurs. At this time, in the slit-shaped bypass output lower provided at the narrowest part of the venturi, the dynamic pressure is small and its influence can be minimized.

すなわち、スリット状のバイパス出ロアは主空気運路２
ｍ、２ｂを通過する空気流に対して直角に開口している
ので、出ロア０幅を小さくでき、脈動の影響を少なくす
ることが可能となるものである。In other words, the slit-shaped bypass output lower is connected to the main air passage 2.
Since the openings are perpendicular to the airflow passing through the openings m and 2b, the zero width of the lower exit can be made small, and the influence of pulsation can be reduced.

本発明によれば工／ジン、吸気脈動時に、ベンチュリ部
の脈動空気流れによって、バイパス通路への影響を極力
小さくでき、脈動時にも負の空気流量を検出できる効果
がある。According to the present invention, the effect on the bypass passage can be minimized by the pulsating air flow in the venturi section during intake pulsations, and a negative air flow rate can be detected even during pulsations.

【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になるエア７０メータの断面
図、第２図はＰ矢視図である。 １・・・エアフロメータ、２ａｓ２ｂ・・・主空気通路
、３・・・ベンチュリ、４・・・バイパス通路、４ｍ・
・・縦通路、４ｂ・・・横環状通路、５・・・熱線、７
・・・バイパス出口。 代理人　弁理士　高橋明夫FIG. 1 is a sectional view of a 70-meter air meter according to an embodiment of the present invention, and FIG. 2 is a view taken along arrow P. 1...Air flow meter, 2as2b...Main air passage, 3...Venturi, 4...Bypass passage, 4m
...Vertical passage, 4b...Horizontal annular passage, 5...Heating wire, 7
...Bypass exit. Agent Patent Attorney Akio Takahashi

Claims (1)

【特許請求の範囲】[Claims] １、バイパス通路にホットワイヤを設置したエア７０−
メータにおいて、バイパス通路の入口を主空気通路の吸
気方向と同一方向に開口し、出口を前記主空気通路の吸
気方向と直角にスリット形状で開口し、かつ前記入口と
前記出口を横環状通路で連通したエアフローメータ。1. Air 70- with a hot wire installed in the bypass passage
In the meter, the inlet of the bypass passage is opened in the same direction as the intake direction of the main air passage, the outlet is opened in the shape of a slit at right angles to the intake direction of the main air passage, and the inlet and the outlet are formed in a horizontal annular passage. Connected air flow meter.