| 摘要 |
A sensor device for a mass flow controller suitable for stably sensing gas flowrate of the mass flow controller regardless of variation of peripheral temperature. This sensor device comprises a case being covered with a thermal insulation plate, a sensor tube being arranged in the in-suit case to pass therethrough, an up-stream coil and a down-stream coil coiling around the sensor tube and being adapted for sensing heat of a gas passing through the sensor tube, respectively, a thermoelectric converter for converting a heat difference of the gas in the sensor tube into a voltage, an amplifier for amplifying the voltage output from the thermoelectric converter, a linearizer for linearizing the amplified voltage of the amplifier, a refrigeratory plate being arranged in the case for maintaining the inside temperature of the sensor device at a predetermined temperature, a pair of Peltier thermoelectric wires comprising an antimon wire and a bismuth wire being connected to a drive power supply terminal and a ground terminal of an electric power connector, respectively, and a thermostat for selectively cutting off power supply to the refrigeratory plate when the inside temperature of the sensor device is lower or higher than a predetermined critical temperature.
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