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US 2004/0163464 A1Published application
Flow rate sensor
AssigneesHitachi, Ltd., Hitachi Car Engineering Co., Ltd.
InventorsKeiichi Nakada, Junichi Horie, Izumi Watanabe
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AssigneesHitachi, Ltd., Hitachi Car Engineering Co., Ltd.
InventorsKeiichi Nakada, Junichi Horie, Izumi Watanabe
Estimating the term…
A flow rate sensor for detecting, with higher accuracy, the flow rate in a pulsating condition including a large amount of the reverse flow. Upstream temperature sensors and downstream temperature sensors are formed in both sides of a heater, parallel resistors are formed in the external side of a thin film portion (cavity), and the downstream temperature sensors are connected at the contacts. The upstream and downstream temperature sensors 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 is cooled during the forward flow, while the downstream temperature sensor is influenced by the heater but virtual change is rather small and potential difference between the electrodes becomes larger. During the reverse flow, the downstream temperature sensor is cooled but virtual change is rather small. The upstream temperature sensor is influenced by the heater and heated up to higher temperature. As a result, reverse flow can be detected within a narrower voltage range than that of the prior art because the flow rate characteristics of reverse flow are compressed against those of forward flow.
A flow rate sensor comprising a heater, an upstream temperature sensor allocated in a forward flow side of said heater, and a downstream temperature sensor allocated in a reverse flow side of said heater, wherein a voltage is applied to said upstream temperature sensor and said downstream temperature sensor in order to detect a flow rate using a potential difference generated between said upstream temperature sensor and said downstream temperature sensor,
A flow rate sensor comprising a heater, an upstream temperature sensor allocated in a forward flow side of said heater, and a downstream temperature sensor allocated in a reverse flow side of said heater, wherein a voltage is applied to said upstream temperature sensor and said downstream temperature sensor in order to detect flow rate using a potential difference generated between said upstream temperature sensor and said downstream temperature sensor,
A flow rate sensor comprising a thin film portion comprising a heater, an upstream temperature sensor allocated in a forward flow side of said heater and a downstream temperature sensor allocated in a reverse flow side of said heater, wherein a voltage is applied to said upstream temperature sensor and said downstream temperature sensor in order to detect flow rate using a potential difference generated between said upstream temperature sensor and said downstream temperature sensor,
A flow rate sensor comprising, in the thin film portion, a heater, an upstream temperature sensor allocated in the forward flow side of said heater, and a downstream temperature sensor allocated in the reverse flow side of said heater in order to detect flow rate using potential difference generated between said upstream temperature sensor and said downstream temperature sensor by applying voltages to said upstream temperature sensor and said downstream temperature sensor,
A flow rate sensor comprising a thin film portion comprising a heater, an upstream temperature sensor allocated in a forward flow side of said heater and a downstream temperature sensor allocated in a reverse flow side of said heater, wherein a voltage is applied to said upstream temperature sensor and said downstream temperature sensor in order to detect flow rate using a potential difference generated between said upstream temperature sensor and said downstream temperature sensor,
A flow rate sensor comprising a thin film portion comprising a heater, an upstream temperature sensor allocated in a forward flow side of said heater and a downstream temperature sensor allocated in a reverse flow side of said heater, wherein a voltage is applied to said upstream temperature sensor and said downstream temperature sensor in order to detect flow rate using a potential difference generated between said upstream temperature sensor and said downstream temperature sensor, wherein a resistive element connected in parallel to said downstream temperature sensor and the connecting point thereof are allocated in the external side of said thin film portion.
Dependencies are inferred from the claim text.