JPH05164585A - Air flowmeter - Google Patents
Air flowmeterInfo
- Publication number
- JPH05164585A JPH05164585A JP3336636A JP33663691A JPH05164585A JP H05164585 A JPH05164585 A JP H05164585A JP 3336636 A JP3336636 A JP 3336636A JP 33663691 A JP33663691 A JP 33663691A JP H05164585 A JPH05164585 A JP H05164585A
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- Prior art keywords
- air
- bypass passage
- passage
- path
- 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.)
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Links
Landscapes
- Measuring Volume Flow (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、主通路を迂回するバイ
パス通路を有する空気流量計に関し、特に内燃機関の吸
入空気量を検出するのに好適であり、また流量測定セン
サとして電気的発熱抵抗体を用いる熱式空気流量計に好
適なものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow meter having a bypass passage bypassing a main passage, and is particularly suitable for detecting an intake air amount of an internal combustion engine, and an electric heating resistor as a flow rate measuring sensor. It is suitable for a thermal air flow meter using a body.
【０００２】[0002]
【従来の技術】従来より、熱式空気流量計として、例え
ば特開昭５４−１３４２２３号公報に示されるように、
内燃機関の吸入空気量に応じて放熱量が変化する特性を
利用した流量計が知られている。このものは、吸入空気
を流す空気通路に発熱抵抗体を設け、空気流速と発熱体
の伝熱量の関係から決まる空気流速に応じた電気信号よ
り吸入空気量を検知する。2. Description of the Related Art Conventionally, as a thermal air flow meter, for example, as disclosed in Japanese Patent Laid-Open No. 54-134223,
2. Description of the Related Art A flow meter is known that uses a characteristic that the amount of heat radiation changes according to the amount of intake air of an internal combustion engine. In this device, a heating resistor is provided in an air passage through which intake air flows, and the intake air amount is detected from an electric signal corresponding to the air flow velocity determined by the relationship between the air flow velocity and the heat transfer amount of the heat generator.
【０００３】従来の他の内燃機関用空気流量計として
は、実開昭５４−１４３９０４号公報に示されるよう
に、内燃機関の吸気通路に設けられるバイパス通路に絞
り部を形成し、この絞り部に流量測定用の発熱抵抗体を
設けたものが開示されている。この絞り部がどのような
形状であるか、あるいはこの絞り部によってどのような
作用効果があるかについての詳細な記載はない。As another conventional air flow meter for an internal combustion engine, as shown in Japanese Utility Model Application Laid-Open No. 54-143904, a throttle portion is formed in a bypass passage provided in an intake passage of the internal combustion engine. There is disclosed a device provided with a heating resistor for flow rate measurement. There is no detailed description about what shape this throttle portion has, or what action and effect it has.
【０００４】[0004]
【発明が解決しようとする課題】しかし、このような従
来の熱式空気流量計によると、小型の発熱抵抗体の伝熱
量の変化により通路断面の一部の流速を測定して全体の
流量を測定するため、エアクリーナからの流れの影響を
受けやすいという問題がある。具体的には、エアクリー
ナのエレメントに汚れが付着し、空気流量計の上流の流
速分布が変化するようになると、空気流量計に測定誤差
が生じたり、エレメントの汚れにより通気抵抗増加量が
通路部位によって異なると、流速変動が増加して空気流
量計の出力変動が増加しやすい。However, according to such a conventional thermal type air flow meter, the flow rate of a part of the passage cross section is measured by the change of the heat transfer amount of the small heating resistor to determine the total flow rate. Since it is measured, there is a problem that it is easily affected by the flow from the air cleaner. Specifically, if dirt adheres to the element of the air cleaner and the flow velocity distribution upstream of the air flow meter changes, a measurement error may occur in the air flow meter, or the amount of ventilation resistance increase due to dirt on the element may increase the flow resistance. , The flow rate fluctuation increases and the output fluctuation of the air flow meter tends to increase.
【０００５】また一般に、エアクリーナの直下流に空気
流量計が取付けられる場合、空気流量計のすぐ上流で吸
気流の方向が曲げられることがあり、空気流の乱れある
いは偏りがあると、空気流量計の測定流量も誤差を生じ
る。さらには、内燃機関の運転状況例えば低負荷域から
高負荷域までの幅広い運転域全域において適正に空気流
量を計測するには、流速変動がどのような状況にあろう
と、その時の空気流量に正確に対応するセンサ出力信号
を発生する必要がある。Further, in general, when an air flow meter is installed immediately downstream of the air cleaner, the direction of the intake air flow may be bent immediately upstream of the air flow meter, and if the air flow is disturbed or biased, the air flow meter The measured flow rate of 1 also causes an error. Furthermore, in order to properly measure the air flow rate in a wide range of operating conditions of the internal combustion engine, for example, from the low load range to the high load range, the air flow rate at that time should be accurate regardless of the flow velocity fluctuations. It is necessary to generate a sensor output signal corresponding to
【０００６】本発明の目的は、内燃機関の吸入空気量の
変動が大きな場合にも正確な流量測定を行なえる空気流
量計を提供することにある。An object of the present invention is to provide an air flow meter which can accurately measure the flow rate even when the intake air amount of the internal combustion engine fluctuates greatly.
【０００７】[0007]
【課題を解決するための手段】前記目的を達成するため
の本発明による空気流量計は、空気が通過する主通路を
形成するハウジングと、前記主通路から空気を取り入れ
る入口部と連通し、軸方向に均等な通路径をもつ上流側
バイパス通路と、前記上流側バイパス通路の下流側に形
成され、前記上流側バイパス通路径よりも小径の通路径
をもち、前記主通路に空気を放出する出口部に連通する
下流側バイパス通路と、前記下流側バイパス通路に設け
られる流量測定センサとを備えることを特徴とする。SUMMARY OF THE INVENTION To achieve the above object, an air flow meter according to the present invention comprises a shaft for communicating with a housing forming a main passage through which air passes and an inlet portion for taking in air from the main passage. An upstream bypass passage having a uniform passage diameter in the direction, and an outlet formed on the downstream side of the upstream bypass passage, having a passage diameter smaller than the upstream bypass passage diameter, and discharging air to the main passage. It is characterized by comprising a downstream side bypass passage communicating with the section and a flow rate measuring sensor provided in the downstream side bypass passage.
【０００８】[0008]
【作用】本発明の空気流量計によると、主通路に流入し
た空気の一部は入口部から上流側バイパス通路に流入
し、さらに下流側バイパス通路を経て出口部から再び主
通路に戻される。そして、流量測定センサが下流側バイ
パス通路に設けられ、その流量を計測する。このとき、
本発明によると、上流側バイパス通路より、下流側バイ
パス通路の通路径が小径であるため、この下流側バイパ
ス通路内における流速変動が大幅に低減される。このた
め、この下流側バイパス通路内に設けられた流量測定セ
ンサにより、主通路の流速変動の影響を受けにくい正確
な流量測定が可能になる。According to the air flow meter of the present invention, part of the air that has flowed into the main passage flows into the upstream bypass passage from the inlet portion, and further returns to the main passage from the outlet portion via the downstream bypass passage. A flow rate measuring sensor is provided in the downstream bypass passage and measures the flow rate. At this time,
According to the present invention, since the diameter of the downstream bypass passage is smaller than that of the upstream bypass passage, the flow velocity fluctuation in the downstream bypass passage is significantly reduced. Therefore, the flow rate measuring sensor provided in the downstream bypass passage enables accurate flow rate measurement which is less likely to be affected by the flow velocity fluctuation in the main passage.
【０００９】[0009]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。図１は、内燃機関の吸入空気通路に設けられる熱
式流量計に本発明を適用した第１実施例を示す。図１に
示す矢印Ａの方向に空気が導入される。また熱式流量計
１００の下流側は図示しないスロットルバルブを介して
内燃機関の燃焼室に接続されている。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment in which the present invention is applied to a thermal type flow meter provided in an intake air passage of an internal combustion engine. Air is introduced in the direction of arrow A shown in FIG. The downstream side of the thermal type flow meter 100 is connected to the combustion chamber of the internal combustion engine via a throttle valve (not shown).
【００１０】熱式流量計１００は、主通路２を形成する
円筒形状をなすハウジング１と、このハウジング１の主
通路２の中央に配置される中央部材４とから構成されて
いる。ハウジング１は、例えば樹脂材料にて射出成形等
により形成されるもので、その入口部３に上流側絞り部
Ｂが形成される。主通路２の下流側は通路径が拡大する
よう形成されている。中央部材４は、例えば樹脂材料に
て射出成形等によって形成されるもので、リブ１８によ
ってハウジング１の中央位置にて保持される。The thermal type flow meter 100 is composed of a cylindrical housing 1 forming a main passage 2 and a central member 4 arranged at the center of the main passage 2 of the housing 1. The housing 1 is formed of, for example, a resin material by injection molding or the like, and an upstream throttle portion B is formed in the inlet portion 3 thereof. The downstream side of the main passage 2 is formed so that the passage diameter increases. The central member 4 is formed of, for example, a resin material by injection molding or the like, and is held by the rib 18 at the central position of the housing 1.
【００１１】中央部材４の上流側の部位５は、その内部
６が中空状に形成されるとともに、内周面によって主通
路２をバイパスする円筒状のバイパス通路７を有する。
このバイパス通路７は、上流側バイパス通路７ａと下流
側バイパス通路７ｂとからなり、これらの上流側バイパ
ス通路７ａと下流側バイパス通路７ｂは、軸方向に通路
径がほぼ均等に形成される。上流側バイパス通路径ｄ1
は、下流側バイパス通路径ｄ2 よりも大径に形成され
る。従って、上流側バイパス通路７ａと下流側バイパス
通路７ｂの間に形成される段差部１９の下流側のバイパ
ス通路面積は、段差部１９の上流側のバイパス通路面積
より小となっている。そして、ハウジング１の主通路２
と中央部材４の上流側の部位５の後端部９とのなす通路
は下流側流路絞り部Ｃを形成している。下流側流路絞り
部Ｃの流路面積は上流側流路絞り部Ｂの流路面積より大
きい。The upstream portion 5 of the central member 4 has a hollow interior 6 and a cylindrical bypass passage 7 that bypasses the main passage 2 by its inner peripheral surface.
The bypass passage 7 is composed of an upstream bypass passage 7a and a downstream bypass passage 7b, and the upstream bypass passage 7a and the downstream bypass passage 7b are formed so that the passage diameters are substantially equal in the axial direction. Upstream bypass diameter d 1
Is formed to have a diameter larger than the diameter d 2 of the downstream bypass passage. Therefore, the bypass passage area on the downstream side of the step portion 19 formed between the upstream bypass passage 7 a and the downstream bypass passage 7 b is smaller than the bypass passage area on the upstream side of the step portion 19. And the main passage 2 of the housing 1
The passage formed by the rear end portion 9 of the upstream side portion 5 of the central member 4 forms a downstream side flow passage narrowing portion C. The flow passage area of the downstream flow passage throttle portion C is larger than the flow passage area of the upstream flow passage throttle portion B.
【００１２】中央部材４の下流側の部位１０は、上流側
の部位５と同様にその内部１１が中空に形成されるとと
もに、外周径が下流側に次第に小さくなるよう形成され
ている。この下流側の部位１０は、下流側バイパス通路
７ｂ中に配置される流速測定用抵抗体１２と、温度補償
抵抗体１３とを保持するとともに、この抵抗体１２、１
３を電気的に制御する制御回路１４と接続されている。
流速測定用抵抗体１２は、制御回路１４によって吸気温
度に対して一定温度差に加熱され、下流側バイパス通路
７ｂ内を流れる空気流量を検出する。Like the upstream portion 5, the downstream portion 10 of the central member 4 is formed so that its inside 11 is hollow and the outer diameter gradually decreases toward the downstream side. The downstream portion 10 holds a flow velocity measuring resistor 12 and a temperature compensating resistor 13 arranged in the downstream bypass passage 7b, and the resistors 12, 1
3 is electrically connected to a control circuit 14 for electrically controlling.
The flow velocity measuring resistor 12 is heated by the control circuit 14 to a constant temperature difference with respect to the intake air temperature, and detects the flow rate of air flowing in the downstream side bypass passage 7b.
【００１３】また、上流側の部位５と下流側の部位１０
との対向する間には、バイパス通路７と垂直な関係をな
す径方向通路１５が全周方向にわたって形成されてい
る。さらに、上流側の部位５の後端部９の内周面と下流
側の部位１０の外周面との間には、径方向通路１５と垂
直な関係をなす円環状の出口通路１６が形成されてい
る。この出口通路１６の出口部１７は、主通路２に対し
て平行となるようにスリット状にリブ１８の部分を除い
てほぼ全周にわたって開口している。Further, the upstream side portion 5 and the downstream side portion 10
A radial passage 15 that is in a vertical relationship with the bypass passage 7 is formed over the entire circumferential direction while facing each other. Further, between the inner peripheral surface of the rear end portion 9 of the upstream side portion 5 and the outer peripheral surface of the downstream side portion 10, an annular outlet passage 16 having a vertical relationship with the radial passage 15 is formed. ing. The outlet portion 17 of the outlet passage 16 is opened in a slit shape so as to be parallel to the main passage 2 over substantially the entire circumference except for the rib 18.
【００１４】次に、前記実施例の作用について説明す
る。図１において、大気から導入された空気は、図示し
ないエアクリーナを通して矢印Ａで示すように熱式流量
計１００内の主通路２に導入される。この際、下流側流
路絞り部Ｃによって流路面積が絞られているので、この
部位の主通路２を流れる空気の流速が増加し、これによ
って出口部１７に負圧が発生する。したがって、バイパ
ス通路７の入口部８と出口部１７との差圧によって、バ
イパス通路７内に空気の流れが発生する。Next, the operation of the above embodiment will be described. In FIG. 1, air introduced from the atmosphere is introduced into the main passage 2 in the thermal type flow meter 100 through an air cleaner (not shown) as shown by an arrow A. At this time, since the flow passage area is narrowed down by the downstream flow passage narrowing portion C, the flow velocity of the air flowing through the main passage 2 at this portion is increased, and thereby a negative pressure is generated at the outlet portion 17. Therefore, an air flow is generated in the bypass passage 7 due to the pressure difference between the inlet portion 8 and the outlet portion 17 of the bypass passage 7.
【００１５】熱式流量計１００の上流側の空気の流速変
動（乱れ）が発生する場合、この乱れが入口部８へ導入
されると、この乱れた空気の流れの一部は上流側バイパ
ス通路７ａにて整流される。さらに、段差部１９にて縮
流により空気の流速変動（乱れ）が低減される。したが
って、熱式流量計１００の上流からの空気流の乱れある
いは偏りがあっても、これらの影響を受けることのない
精確な流量測定を行なえる。吸入空気量の変動が大きな
場合にも、吸入空気量に対応した正確な電気出力信号を
発生する構成であるから、その電気信号を補正するなど
の後処理が不要となるという利点がある。When the flow velocity fluctuation (turbulence) of the air on the upstream side of the thermal type flow meter 100 occurs, when this turbulence is introduced into the inlet section 8, a part of this turbulent air flow is caused by the upstream bypass passage. It is rectified by 7a. Further, the flow velocity fluctuation (turbulence) of the air is reduced by the contraction in the step portion 19. Therefore, even if the air flow from the upstream of the thermal type flow meter 100 is disturbed or biased, accurate flow rate measurement can be performed without being affected by these. Even if the intake air amount fluctuates significantly, the configuration is such that an accurate electric output signal corresponding to the intake air amount is generated, so there is an advantage that post-processing such as correction of the electric signal is unnecessary.
【００１６】次に、熱式流量計１００のバイパス通路７
を流れる空気の流速変動が各部位でどのようになるかに
ついて比較例と対比した実験結果を図２に示す。ここに
比較例の熱式流量計は、図７に示すように、バイパス通
路３７の始端３７ａから終端３７ｂまで真直ぐに均等な
通路径ｄ3 を有し、前記実施例に示す段差部１９をもた
ないものである。実験において、空気の流速変動（乱
れ）は、高応答熱線流速計によりバイパス通路７内の空
気の流速変動（乱れ）の低減度を測定したものである。Next, the bypass passage 7 of the thermal type flow meter 100
FIG. 2 shows an experimental result in which the flow velocity fluctuation of the air flowing through the chamber is compared with that of the comparative example. As shown in FIG. 7, the thermal type flow meter of the comparative example has a straight passage diameter d 3 straight from the starting end 37a to the terminating end 37b of the bypass passage 37, and also includes the step portion 19 shown in the embodiment. It is something that can not be done. In the experiment, the flow velocity fluctuation (turbulence) of the air is obtained by measuring the degree of reduction of the flow velocity fluctuation (turbulence) of the air in the bypass passage 7 by the high response hot wire anemometer.
【００１７】前記本発明の実施例によると、図２に実線
で示すように、段差部１９の下流側において流速変動が
大幅に低下することが解る。これに対し、比較例による
と、図２に点線で示すように、流速変動の大幅な低減効
果はない。次に、前記実施例における段差部１９の上流
側バイパス通路径ｄ1 と下流側バイパス通路径ｄ2 との
比ｄ1 ／ｄ2 をパラメータとし、この熱式流量計をエア
クリーナの下流部に装着した場合のセンサ出力変動を測
定した実験結果を図３に示す。According to the above-described embodiment of the present invention, as shown by the solid line in FIG. 2, it is understood that the flow velocity fluctuation is significantly reduced on the downstream side of the step portion 19. On the other hand, according to the comparative example, as shown by the dotted line in FIG. 2, there is no significant reduction effect of the flow velocity fluctuation. Next, using the ratio d 1 / d 2 of the upstream side bypass passage diameter d 1 and the downstream side bypass passage diameter d 2 of the step portion 19 in the above embodiment as a parameter, this thermal type flow meter is attached to the downstream portion of the air cleaner. FIG. 3 shows the experimental result of measuring the sensor output fluctuation in the case of doing so.
【００１８】図３に示すように、上流側バイパス通路径
ｄ1 と下流側バイパス通路径ｄ2 との比ｄ1 ／ｄ2 の値
が１．２を超えるとセンサ出力変動が大幅に低減される
ことが判明した。またこの比ｄ1 ／ｄ2 を十分に大きく
してもさほどセンサ出力変動は低減されるものでないこ
とも判明した。さらに、熱式流量計１００内を流れる吸
入空気の流速が変動する場合にセンサ出力変動がどのよ
うに変化するかについて実験した結果を図４に示す。As shown in FIG. 3, when the ratio d 1 / d 2 of the upstream side bypass passage diameter d 1 to the downstream side bypass passage diameter d 2 exceeds 1.2, the sensor output fluctuation is greatly reduced. It turned out that It was also found that even if the ratio d 1 / d 2 is made sufficiently large, the sensor output fluctuation is not so much reduced. Further, FIG. 4 shows a result of an experiment on how the sensor output fluctuation changes when the flow velocity of the intake air flowing in the thermal type flow meter 100 changes.
【００１９】本発明の実施例においては流量が低流量の
場合にもセンサ出力変動が十分に低減されることが理解
される。これにより前記実施例によると低流量域から高
流量域の全域においてセンサ出力変動が相対的に小さく
なるため、空気流量測定を精度よく行えるという効果が
あることが判明した。これに対し、比較例では、流量が
相対的に低流量である場合にセンサ出力変動が比較的大
きいことが理解される。特に、自動車に搭載される内燃
機関のように運転状況が著しく変動する状況において
も、空気流速が低速から高速までの広い流速範囲におい
て精度のよい空気流量測定が行えるという効果がある。It is understood that in the embodiment of the present invention, the sensor output fluctuation is sufficiently reduced even when the flow rate is low. As a result, according to the above-described embodiment, the sensor output fluctuation is relatively small in the entire range from the low flow rate region to the high flow rate region, and therefore, it has been found that there is an effect that the air flow rate measurement can be performed accurately. On the other hand, in the comparative example, it is understood that the sensor output fluctuation is relatively large when the flow rate is relatively low. In particular, even in a situation where the operating condition changes remarkably like an internal combustion engine mounted on an automobile, there is an effect that the air flow rate can be accurately measured in a wide flow velocity range from low speed to high speed.
【００２０】図５は、本発明の第２実施例による熱式流
量計を示す。この第２実施例は、前記第１実施例による
段差部１９に代えて、上流側バイパス通路７ａと下流側
バイパス通路７ｂとの間に円錐斜面状の傾斜面２０を形
成した例である。この例は、バイパス通路径が均等な図
７に示す比較例に比べて、傾斜面２０の下流側の下流側
バイパス通路７ｂでの空気の流速変動を大幅に低減する
ものである。したがって、下流側バイパス通路７ｂに設
けられる流速測定用抵抗体１２と温度補償抵抗体１３と
によって吸入空気の温度変化あるいは流速変動があって
も主通路２を通過する空気流の測定が精度よく電気信号
に置き換えられるという効果がある。FIG. 5 shows a thermal type flow meter according to a second embodiment of the present invention. The second embodiment is an example in which a conical inclined surface 20 is formed between the upstream side bypass passage 7a and the downstream side bypass passage 7b instead of the step portion 19 according to the first embodiment. In this example, the flow velocity fluctuation of the air in the downstream bypass passage 7b on the downstream side of the inclined surface 20 is significantly reduced as compared with the comparative example shown in FIG. Therefore, the flow rate measuring resistor 12 and the temperature compensating resistor 13 provided in the downstream bypass passage 7b can accurately measure the air flow passing through the main passage 2 even if the temperature of the intake air changes or the flow velocity changes. It has the effect of being replaced by a signal.
【００２１】図６は、本発明の第３実施例による熱式流
量計を示す。この第３実施例は、前記第１実施例による
段差部１９に代えて、上流側バイパス通路７ａと下流側
バイパス通路７ｂとの間になだらかなベルマウス状の曲
面３０を形成した例である。この例は、バイパス通路径
が均等な図７に示す比較例に比べて、曲面３０の下流側
の下流側バイパス通路での空気の流速変動を大幅に低減
する。したがって、下流側バイパス通路７ｂに設けられ
る流速測定用抵抗体１２と温度補償抵抗体１３とによっ
て吸入空気の温度変化あるいは流速変動があっても主通
路２を通過する空気流の測定が精度よく電気信号に置き
換えることができる。FIG. 6 shows a thermal type flow meter according to a third embodiment of the present invention. The third embodiment is an example in which, in place of the step portion 19 according to the first embodiment, a gentle bellmouth-shaped curved surface 30 is formed between the upstream bypass passage 7a and the downstream bypass passage 7b. In this example, compared with the comparative example shown in FIG. 7 in which the bypass passage diameter is uniform, the flow velocity fluctuation of the air in the downstream bypass passage on the downstream side of the curved surface 30 is significantly reduced. Therefore, the flow rate measuring resistor 12 and the temperature compensating resistor 13 provided in the downstream bypass passage 7b can accurately measure the air flow passing through the main passage 2 even if the temperature of the intake air changes or the flow velocity changes. Can be replaced with a signal.
【００２２】[0022]
【発明の効果】以上説明したように、本発明の空気流量
計によれば、主通路を迂回するバイパス通路に設ける流
量測定センサにより上流側で空気の流速変動があっても
精度よい空気流量測定を行える効果がある。As described above, according to the air flow meter of the present invention, the flow rate measurement sensor provided in the bypass passage bypassing the main passage accurately measures the air flow rate even if the flow velocity of the air fluctuates on the upstream side. There is an effect that can be.
【図面の簡単な説明】[Brief description of drawings]
【図１】本発明の第１実施例を示す断面図である。FIG. 1 is a sectional view showing a first embodiment of the present invention.
【図２】本発明の第１実施例によるバイパス通路の各部
位における流速変動を示す特性図である。FIG. 2 is a characteristic diagram showing a flow velocity fluctuation in each part of the bypass passage according to the first embodiment of the present invention.
【図３】本発明の第１実施例において段差部の上流側バ
イパス通路径と下流側バイパス通路径とを変化させた場
合のセンサ出力変動を示す特性図である。FIG. 3 is a characteristic diagram showing sensor output fluctuations when the upstream bypass passage diameter and the downstream bypass passage diameter of the step portion are changed in the first embodiment of the present invention.
【図４】本発明の第１実施例と従来の比較例とについて
空気流量とセンサ出力変動との関係を示す特性図であ
る。FIG. 4 is a characteristic diagram showing the relationship between air flow rate and sensor output fluctuation for the first embodiment of the present invention and a conventional comparative example.
【図５】本発明の第２実施例を示す断面図である。FIG. 5 is a sectional view showing a second embodiment of the present invention.
【図６】本発明の第３実施例を示す断面図である。FIG. 6 is a sectional view showing a third embodiment of the present invention.
【図７】比較例を示す断面図である。FIG. 7 is a cross-sectional view showing a comparative example.
１ ハウジング ２ 主通路 ７ａ 上流側バイパス通路 ７ｂ 下流側バイパス通路 ８ 入口部 １２ 流速測定用抵抗体（流量測定センサ） １３ 温度補償抵抗体（流量測定センサ） １７ 出口部 １９ 段差部 １００ 熱式流量計（空気流量計） DESCRIPTION OF SYMBOLS 1 Housing 2 Main passage 7a Upstream bypass passage 7b Downstream bypass passage 8 Inlet portion 12 Flow velocity measuring resistor (flow rate measuring sensor) 13 Temperature compensation resistor (flow rate measuring sensor) 17 Outlet portion 19 Step portion 100 Thermal flow meter (Air flow meter)
───────────────────────────────────────────────────── フロントページの続き (72)発明者 北原 昇 愛知県刈谷市昭和町１丁目１番地 日本電 装株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Kitahara 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihondenso Co., Ltd.
Claims (3)
ングと、 前記主通路から空気を取り入れる入口部と連通し、軸方
向に均等な通路径をもつ上流側バイパス通路と、 前記上流側バイパス通路の下流側に形成され、前記上流
側バイパス通路径よりも小径の通路径をもち、前記主通
路に空気を放出する出口部に連通する下流側バイパス通
路と、 前記下流側バイパス通路に設けられる流量測定センサと
を備えることを特徴とする空気流量計。1. A housing forming a main passage through which air passes, an upstream bypass passage communicating with an inlet portion for taking in air from the main passage, and having an axially uniform passage diameter, and the upstream bypass passage. A downstream bypass passage that is formed on the downstream side of the upstream bypass passage, has a passage diameter smaller than that of the upstream bypass passage, and that communicates with an outlet portion that discharges air to the main passage, and a flow rate provided in the downstream bypass passage. An air flow meter, comprising: a measurement sensor.
イパス通路との間に段差部が形成されることを特徴とす
る請求項１記載の空気流量計。2. The air flow meter according to claim 1, wherein a step portion is formed between the upstream side bypass passage and the downstream side bypass passage.
ス通路径ｄ1 と前記下流側バイパス通路の下流側バイパ
ス通路径ｄ2 との比ｄ1 ／ｄ2 が１．２以上であること
を特徴とする請求項１記載の空気流量計。3. The ratio d 1 / d 2 of the upstream bypass passage diameter d 1 of the upstream bypass passage and the downstream bypass passage diameter d 2 of the downstream bypass passage is 1.2 or more. The air flow meter according to claim 1.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3336636A JP3053483B2 (en) | 1991-12-19 | 1991-12-19 | Air flow meter |
| EP92121479A EP0547595B1 (en) | 1991-12-19 | 1992-12-17 | Flow meter |
| DE69231960T DE69231960T2 (en) | 1991-12-19 | 1992-12-17 | Flow meter |
| US08/319,030 US5581026A (en) | 1991-12-19 | 1994-10-06 | Flow meter |
| US08/429,471 US5571964A (en) | 1991-12-19 | 1995-04-27 | Flow meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3336636A JP3053483B2 (en) | 1991-12-19 | 1991-12-19 | Air flow meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05164585A true JPH05164585A (en) | 1993-06-29 |
| JP3053483B2 JP3053483B2 (en) | 2000-06-19 |
Family
ID=18301215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3336636A Expired - Lifetime JP3053483B2 (en) | 1991-12-19 | 1991-12-19 | Air flow meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3053483B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5672822A (en) * | 1994-06-23 | 1997-09-30 | Nippondenso Co., Ltd. | Thermal flow meter with less turbulence in fluid flow |
-
1991
- 1991-12-19 JP JP3336636A patent/JP3053483B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5672822A (en) * | 1994-06-23 | 1997-09-30 | Nippondenso Co., Ltd. | Thermal flow meter with less turbulence in fluid flow |
| US5894088A (en) * | 1994-06-23 | 1999-04-13 | Nippondenso Co., Ltd. | Thermal flow meter with less turbulence in fluid flow |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3053483B2 (en) | 2000-06-19 |
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