Patent ID: 6889544
Filing Date: 2005-05-10
Classification: G01F

Abstract:
1. A thermal type flow rate detector, comprising: a bridge circuit comprising first and second temperature detecting elements for detecting a temperature of fluid flowing from the upstream side to the downstream side, and first and second fixed resistors; and a temperature difference controlling circuit for continuously supplying an electric power to first and second heat generating elements so that a temperature difference between the first and second temperature detecting elements becomes a predetermined value, the temperature difference controlling circuit comprising: a differential amplifier connected to the bridge circuit; a first constant voltage power supply; a second constant voltage power supply having a lower constant voltage than that of the first constant voltage power supply; and the first and second heat generating elements, wherein the first heat generating element is connected between an output side of the differential amplifier and the second constant voltage power supply, and the second heat generating element is connected between the output side of the differential amplifier and the first constant voltage power supply.