Yamatake-Honeywell Co., Ltd.

Shigeru Aoshima

Shoji Kamiunten

Shosaku Maeda

Tetsuo Hisanaga

Takashi Tsumura

Takashi Inaba

Kouichi Ochiai

Koichi Ochiai

A flow meter is provided which employs a thermal flow sensor and a correcting flow meter, for example, a Karman vortex flow meter such that the output from the thermal flow sensor is corrected by the Karman vortex flow meter, thereby making it possible to accurately and stably measure the flow rate of fluids in a wide range even if the composition of fluids changes.

Flow meter and measuring method therefor

A respiratory air flowmeter includes a flow path forming member, a restricting portion, rectifying lattices, and a sensor. The flow path forming member forms a flow path in which respiratory air flows. The restricting portion and the rectifying lattices are arranged in the flow path in order to stabilize a respiratory air flow. The sensor is mounted in a sensor mounting portion of the flow path forming member, and detects a flow rate of respiratory air flowing in the flow path.

Respiratory air flowmeter

A zero point compensating circuit for a microbridge flow meter including an upstream thermal sensor means, a downstream thermal sensor means and a heater means located between said upstream and downstream thermal sensor is provided which comprises a first switch coupled to said heater for turning on and off the same and a current supply circuit coupled to said upstream and downstream thermal sensors for selectively supplying the same with a first current when said first switch is closed and a second current larger than said first current when said first switch is opened such that said upstream and downstream thermal sensors reach a temperature to which they are heated when said heater is on in no flow condition. Thus, an offset caused by discrepancy in the resistance value and thermal coefficients of resistance (TCR) of the upstream and downstream temperature sensors can be removed by the above circuit, thereby making it possible to achieve a precise measurement of small flow rates of a fluid of interest.

Zero point compensating circuit

A flow sensor comprising a flow passage, a rectifying element such as a plurality of screens or a honeycomb structure or both, arranged in the flow passage, a flow passage reducer for reducing the flow passage behind the rectifying element, and a thermal flow sensor, such as for example a micro bridge sensor, mounted at a location immediately behind the reducer. The above structure can largely reduce disturbance in flow to thereby enable highly accurate measurements of a wide range of flow without a low pass filter.

Flow meter

A fluid flow speed measuring apparatus comprising a first pipe having an opening exposed into a fluid to be measured, a direction of the opening having an angle larger than a critical negative pressure angle, a second pipe having an opening exposed into the fluid to be measured, a direction of the opening of the second pipe having an angle larger than the critical negative pressure angle and at least one of conditions such as a diameter, a direction, and the number of the openings for determining a magnitude of the negative pressure being different from that of the opening of the first pipe, negative pressure difference detector for detecting a difference between negative pressures acting on the openings of the first and second pipes, and device for calculating a flow speed of the fluid to be measured on the basis of an output from the negative pressure difference detector.

Growing community of inventors

Chigasaki, Japan

Shigeru Aoshima