Thermal-type flow sensor
US5623097A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1994 |
| Grant date | Apr 22, 1997 |
| Priority date | — |
| Expiry date | Nov 25, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/692
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A heater-heat sensor type thermal flow sensor including a substrate installed in a fluid path, a channel formed on a part of the substrate; a bridge suspended over the channel; a heater constructed with an electric resistor formed on the bridge; a temperature sensor for measuring the temperature of the heater which is constructed with another electric resistor situated on the bridge and measuring the temperature of the heater; and a fluid temperature sensor constructed with still another electric resistor formed on a position of the substrate not thermally affected by the heater. There is a bridge circuit including the temperature sensor for measuring the temperature of the heater, the fluid temperature sensor, and first and second resistors both installed outside of the fluid path. A control circuit is provided to control the voltage applied to the heater in accordance with the output of the bridge circuit. The heater and the heat sensor are superposedly formed on the bridge through an interlayer insulating film in order to substantially eliminate the difference between the temperatures of the heater and heat sensor. A temperature compensating circuit is connected to the output st…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.