流量センサ

Japanese Patent JP3718198

B2

The invention relates to a flow rate sensor for detecting, with higher accuracy, the flow rate in a pulsating condition including a large amount of the reverse flow (21). Upstream temperature sensors (6, 7) and downstream temperature sensors (8, 9) are formed in both sides of a heater (4), parallel resistors (10, 11) are formed in the external side of a thin film portion (cavity) (26), and the downstream temperature sensors (8, 9) are connected at the contacts. The upstream and downstream temperature sensors (6, 7, 8, 9) are respectively allocated to the four sides of the bridge circuit in the manner that the sensors of the same type are never provided side by side and the electrodes are balanced when the flow rate is zero. The upstream temperature sensor (6, 7) is cooled during the forward flow (20), while the downstream temperature sensor (8, 9) is influenced by the heater (4) but virtual change is rather small and potential difference between the electrodes becomes larger. During the reverse flow (21), the downstream temperature sensor (8, 9) is cooled but virtual change is rather small. The upstream temperature sensor (6, 7) is influenced by the heater (4) and heated up to higher temperature. As a result, reverse flow (21) can be detected within a narrower voltage range than that of the prior art because the flow rate characteristics of reverse flow (21) are compressed against those of forward flow (20).

Keiichi Nakata
Junichi Horie
Izumi Watanabe

JP2003049181A

November 16, 2005

February 26, 2003

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株式会社日立製作所
株式会社日立カーエンジニアリング

G01F1/684; G01F1/692; G01F1/68; G01F1/698; G01F1/699; G01F1/72; G01F5/00; F02D41/18; (IPC1-7): G01F1/692; G01F1/68; G01F1/698

JP9318412A
JP5164584A
JP5157758A
JP11051954A
JP10019626A

Katsuo Ogawa
Kyosuke Tanaka

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