JPH04344424A - Hot wire type air flow meter - Google Patents

Abstract

PURPOSE:To reduce stains for improving durability while providing a high accuracy output property by providing flow arranging gratings such as honeycomb, fin, etc., in a bypass path section in a flow mesuring section provided to cross a main air path. CONSTITUTION:Air sucked in a body 1 is diversed into a main air path 5 and bypass path inlet 6. Air entering the inlet 6 passes through a bypass path 6a disposed parallel to the main air path 5, passes through a bypass path 6b in a flow mesasuring section 7 provided to cross the main air path 5 and joins in the main air path 5 from a bypass path outlet 10. The bypass path 6b in the flow measuring section 7 is provided with a flow arranging grating 11 such as honeycomb, fin, etc. Thus, since air entering an inlet 6 flows through the bypass path 6b in the flow measuring section 7 without causing air turbulence, an exothermic resistor 3 can detect air flow under the best condition without receiving any air turbulence.

Description

【発明の詳細な説明】[Detailed description of the invention]

【０００１】0001

【産業上の利用分野】本発明は内燃機関に供給される空
気流量を検出する熱線式空気流量計の構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a hot wire air flowmeter for detecting the flow rate of air supplied to an internal combustion engine.

【０００２】0002

【従来の技術】従来の軸流型バイパス通路を有する装置
は、実願平１−３０８４６号に記載の様に、主空気通路
内にバイパス通路入口を設け、主空気通路を横切る様に
設けた流量測定部内に、バイパス通路下流側を通路カバ
ーで覆う構造となっているものはある。[Prior Art] A conventional device having an axial flow type bypass passage has a bypass passage inlet provided within the main air passage, as described in Utility Model Application No. 1-30846, which is provided so as to cross the main air passage. Some flow measurement units have a structure in which the downstream side of the bypass passage is covered with a passage cover.

【０００３】0003

【発明が解決しようとする課題】上記従来技術は、流れ
の剥離の大きい流量測定部内のバイパス通路部にノイズ
低減等の工夫がされておらず、バイパス通路部に空気の
乱れが発生し、ノイズが大きく、出力特性がばらつく問
題がある。さらにエンジからの吹き返し流に対する対策
もされておらずエンジンからの吹き返し流に含まれるカ
ーボン，オイルが発熱抵抗体に付着し、汚損する問題も
ある。[Problems to be Solved by the Invention] In the above-mentioned prior art, no measures such as noise reduction have been made in the bypass passage section in the flow measurement section where the flow separation is large, and air turbulence occurs in the bypass passage section, causing noise. There is a problem that the output characteristics vary. Furthermore, no measures have been taken to prevent blowback from the engine, and there is also the problem that carbon and oil contained in the blowback from the engine adhere to the heating resistor and cause it to become dirty.

【０００４】本発明は、バイパス通路部の空気の乱れを
小さくすることにより高精度な出力特性を得ることとも
に、エンジンからの吹き返し流に含まれるカーボン，オ
イルによる発熱抵抗体の汚損低減を図り耐久性を得るこ
とにある。The present invention achieves highly accurate output characteristics by reducing air turbulence in the bypass passage, and also reduces contamination of the heating resistor by carbon and oil contained in the blowback flow from the engine, thereby increasing durability. It's about gaining sex.

【０００５】[0005]

【課題を解決するための手段】上記目的は、主空気通路
内を横切る様に設けた流量測定部内のバイパス通路部に
、ハニカム又は、フィン等の整流格子を設けることによ
り達成される。[Means for Solving the Problems] The above object is achieved by providing a rectifying grid such as a honeycomb or fins in the bypass passage section of the flow rate measuring section provided so as to traverse the interior of the main air passage.

【０００６】[0006]

【作用】主空気通路内を横切る様に設けた流量測定部内
のバイパス通路部に、ハニカム又は、フィン等の整流格
子を設けることにより主空気通路内にあるバイパス通路
入口から入った空気が、流量測定部内のバイパス通路部
を空気の乱れを起こさずに流れるため、バイパス通路入
口部下流側にある発熱抵抗体が空気の乱れを受けず、最
良の状態で空気流量を検出することができる。[Function] By providing a rectifying grid such as a honeycomb or fins in the bypass passage in the flow rate measurement section installed across the main air passage, the air entering from the bypass passage entrance in the main air passage can be adjusted to the flow rate. Since the air flows through the bypass passage in the measuring section without causing any turbulence, the heating resistor located downstream of the bypass passage inlet is not affected by air turbulence, and the air flow rate can be detected in the best condition.

【０００７】さらに上記ハニカム又は、フィンによりエ
ンジンからの吹き返し流に含まれるカーボン，オイルが
ハニカム又は、フィンの壁面に付着し、発熱抵抗体の汚
損低減を図り耐久性が良くなる。Furthermore, the honeycomb or fins cause carbon and oil contained in the flow blown back from the engine to adhere to the walls of the honeycomb or fins, thereby reducing staining of the heating resistor and improving durability.

【０００８】[0008]

【実施例】以下、本発明の一実施例を図１〜図６で説明
する。[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

【０００９】本実施例のバイパス通路を採用した熱線式
空気流量計の構造は図１で示す様にボディ１と、モジュ
ール２から構成される。ボディ１に吸入された空気は主
空気通路５と主空気通路５内に設けたバイパス通路入口
６に分流して流れる。バイパス通路入口６から入った空
気は、主空気通路５と平行に配置したバイパス通路６ａ
を通り主空気通路５を横切る様に設けた流量測定部７内
のバイパス通路６ｂを通過しバイパス通路出口１０より
主空気通路５に合流する。流量測定部７に設けたバイパ
ス通路６ｂは下流側を別部材の通路カバー８によって覆
い取りつけネジ９によりボディ１に組み込んで構成して
いる。一方主空気通路５と平行に配置したバイパス通路
６ａには発熱抵抗体３及び感温抵抗体４が配置されバイ
パス通路６ａを流れる空気流量から全空気量を想定し測
定する方式を取っている。The structure of the hot-wire air flow meter employing the bypass passage of this embodiment is composed of a body 1 and a module 2, as shown in FIG. Air taken into the body 1 is divided into a main air passage 5 and a bypass passage inlet 6 provided in the main air passage 5. Air entering from the bypass passage inlet 6 flows through the bypass passage 6a arranged parallel to the main air passage 5.
The air passes through the bypass passage 6b in the flow rate measuring section 7 provided to cross the main air passage 5, and joins the main air passage 5 through the bypass passage outlet 10. The bypass passage 6b provided in the flow rate measuring section 7 is constructed by covering the downstream side with a passage cover 8, which is a separate member, and incorporating it into the body 1 with mounting screws 9. On the other hand, a heating resistor 3 and a temperature-sensitive resistor 4 are arranged in a bypass passage 6a arranged parallel to the main air passage 5, and a system is adopted in which the total amount of air is assumed and measured from the air flow rate flowing through the bypass passage 6a.

【００１０】本発明では、バイパス通路６ａを通った空
気が流量測定部７に設けたバイパス通路６ｂとの交点で
起こる剥離現象をバイパス通路６ｂに設けた整流格子１
１により抑える構造とし、バイパス通路６ａ内に配置し
た発熱抵抗体３が下流側の空気の乱れを受けず、最良の
状態で空気流量を検出することができる。In the present invention, the separation phenomenon that occurs at the intersection of the air passing through the bypass passage 6a with the bypass passage 6b provided in the flow rate measuring section 7 can be avoided by using the rectifying grid 1 provided in the bypass passage 6b.
1, the heating resistor 3 disposed in the bypass passage 6a is not affected by air disturbance on the downstream side, and the air flow rate can be detected in the best condition.

【００１１】図２は図１のＡ−Ａ断面である。図３及び
図５は、図１の応用例であり、図１Ｐ方向からカバーを
透して見た図である。図４は図３のＢ−Ｂ断面であり、
図６は図５のＣ−Ｃ断面である。FIG. 2 is a cross section taken along line AA in FIG. 3 and 5 are applied examples of FIG. 1, and are views seen through the cover from the direction of FIG. 1P. FIG. 4 is a cross section taken along line B-B in FIG.
FIG. 6 is a cross section taken along line CC in FIG.

【００１２】図２は図１のＡ−Ａ断面で、整流格子とし
てハニカムを採用した一実施例を示すものである。FIG. 2 is a cross section taken along the line AA in FIG. 1, and shows an embodiment in which a honeycomb is used as the rectifying grid.

【００１３】図３及び図４は、流量測定部７に設けたバ
イパス通路内６ｂにフィン１１を設けた一実施例である
。バイパス通路の屈曲部下流は、ボディ１に成形された
バイパス通路部６ｂを上記通路カバー８にて覆い完成す
る。このとき、通路カバー８にはフィン１１が一体成形
されておりボディ１へ固定されることによってバイパス
通路内６ｂにフィン１１を設けることができる。FIGS. 3 and 4 show an embodiment in which a fin 11 is provided in the bypass passage 6b provided in the flow rate measuring section 7. FIG. The downstream side of the bending part of the bypass passage is completed by covering the bypass passage part 6b formed in the body 1 with the passage cover 8. At this time, fins 11 are integrally molded on the passage cover 8 and fixed to the body 1, so that the fins 11 can be provided in the bypass passage 6b.

【００１４】図５及び図６は、流量測定部７に設けたバ
イパス通路内６ｂにフィン１１を設けた他の実施例であ
る。本実施例では、フィン１１は流れ方向に間隔のせば
まる形状，配置としている。又フィン１１は、図５に示
す様に曲面を有するものも形成できる。本実施例では、
他の実施例でもあるバイパス通路内の流れの乱れを低減
し、流量計の出力ノイズを低減する効果と、エンジンか
らの吹き返し流に含まれるカーボン，オイル等の発熱抵
抗体への付着も低減し流量計の耐久劣化を低減する効果
に加えて、正流に対する逆流のバイパス通路通過率を低
減して流量計の高精度化が図れる。FIGS. 5 and 6 show another embodiment in which a fin 11 is provided in the bypass passage 6b provided in the flow rate measuring section 7. FIG. In this embodiment, the fins 11 are shaped and arranged so that the intervals are narrow in the flow direction. Further, the fin 11 can also be formed with a curved surface as shown in FIG. In this example,
Another example is the effect of reducing flow turbulence in the bypass passage, reducing the output noise of the flow meter, and reducing the adhesion of carbon, oil, etc. contained in the blowback flow from the engine to the heating resistor. In addition to the effect of reducing durability deterioration of the flowmeter, it is possible to improve the accuracy of the flowmeter by reducing the passage rate of reverse flow through the bypass passage with respect to forward flow.

【００１５】[0015]

【発明の効果】本発明によれば、流量測定部内のバイパ
ス通路部の空気の乱れを低減する効果が有り、さらにエ
ンジンからの吹き返し流に含まれるカーボン，オイルが
流量測定部内のバイパス通路部内に設けた、ハニカム又
は、フィンの壁面に付着し、バイパス通路入口部下流側
にある発熱抵抗体の汚損低減効果もある。[Effects of the Invention] According to the present invention, there is an effect of reducing air turbulence in the bypass passage section in the flow rate measurement section, and furthermore, carbon and oil contained in the blowback flow from the engine are absorbed into the bypass passage section in the flow rate measurement section. It also has the effect of reducing contamination of the heating resistor attached to the wall surface of the honeycomb or fin provided and located downstream of the bypass passage entrance.

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

【図１】本発明による熱線式空気流量計の一実施例を示
す横断面図である。FIG. 1 is a cross-sectional view showing an embodiment of a hot wire air flow meter according to the present invention.

【図２】図１のＡ−Ａ断面図である。FIG. 2 is a sectional view taken along line AA in FIG. 1;

【図３】図１の応用例であり、図１Ｐ方向から通路カバ
ーを透して見た外観図である。FIG. 3 is an application example of FIG. 1, and is an external view seen through the passage cover from the direction of FIG. 1P.

【図４】図３のＢ−Ｂ断面図である。FIG. 4 is a sectional view taken along line BB in FIG. 3;

【図５】図１の応用例であり、図１Ｐ方向から通路カバ
ーを透して見た外観図である。FIG. 5 is an application example of FIG. 1, and is an external view seen through the passage cover from the direction of FIG. 1P.

【図６】図５のＣ−Ｃ断面図である。FIG. 6 is a sectional view taken along line CC in FIG. 5;

【符号の説明】[Explanation of symbols]

１…ボディ、２…モジュール、３…発熱抵抗体、４…感
温抵抗体、５…主空気通路、６…バイパス通路入口、６
ａ…主空気通路と平行なバイパス通路、６ｂ…流量測定
部内バイパス通路、７…流量測定部、８…通路カバー、
９…取りつけネジ、１０…バイパス通路出口、１１…整
流格子。DESCRIPTION OF SYMBOLS 1...Body, 2...Module, 3...Heating resistor, 4...Temperature-sensitive resistor, 5...Main air passage, 6...Bypass passage entrance, 6
a... Bypass passage parallel to the main air passage, 6b... Bypass passage in the flow rate measurement section, 7... Flow rate measurement section, 8... Passage cover,
9... Mounting screw, 10... Bypass passage outlet, 11... Rectifier grid.

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】流量検出部をバイパス通路内に有し、バイ
パス通路が流量検出部の下流で屈曲部を有する熱線式空
気流量計において、その屈曲部からバイパス通路出口部
の間に整流格子を設けたことを特徴とする熱線式空気流
量計。1. A hot-wire air flowmeter having a flow rate detection section in a bypass passage, and the bypass passage having a bent part downstream of the flow rate detection part, wherein a rectifying grid is provided between the bent part and the outlet of the bypass passage. A hot wire air flow meter characterized by the following: 【請求項２】流量検出部をバイパス通路内に有し、バイ
パス通路が流量検出部の下流で屈曲部を有する熱線式空
気流量計において、その屈曲部からバイパス通路出口部
の間に少なくとも１つ以上のフィンを設けたことを特徴
とする熱線式空気流量計。2. A hot-wire air flowmeter having a flow rate detection section in a bypass passage, the bypass passage having a bend downstream of the flow rate detection section, wherein at least one air flow meter is provided between the bend and the outlet of the bypass passage. A hot wire air flowmeter characterized by having the above fins. 【請求項３】請求項２において、フィンは流れ方向に間
隔のせばまる形状，配置としたことを特徴とする熱線式
空気流量計。3. The hot wire air flowmeter according to claim 2, wherein the fins are shaped and arranged so that the spacing becomes narrower in the flow direction. 【請求項４】請求項１〜３において、上記バイパス通路
はボディと一体に成形された溝部をボディと別部材で覆
うことにより完成され、整流格子及びフィンは上記別部
材と一体成形されていることを特徴とする熱線式空気流
量計。4. In any one of claims 1 to 3, the bypass passage is completed by covering a groove formed integrally with the body with a member separate from the body, and the rectifying grid and the fins are integrally formed with the separate member. A hot wire air flow meter characterized by: 【請求項５】請求項４において、上記別部材はプラスチ
ックで成形されていることを特徴とする熱線式空気流量
計。5. A hot wire air flowmeter according to claim 4, wherein said separate member is molded from plastic.