FLOW RATE SENSOR HAVING FLOWING WATER SWITCHING AND FLUID TEMPERATURE DETECTING FUNCTIONS

摘要

PROBLEM TO BE SOLVED: To provide a flow rate sensor which is not affected by foreign matters existing in a fluid, does not cause pressure loss in the flow of the fluid, has a highly reliable flowing water switching function and/or fluid temperature measuring function, and can be attached to a object as a single attaching unit. SOLUTION: A flow rate sensor is provided with a temperature measuring resistor 19 for comparison which is composed of a resistor, having a resistance-temperature characteristic such that it changes according to the temperature of a fluid to be measured and outputs a divided voltage as a comparative output as the flow rate detecting output of the sensor, a comparator circuit 25 which compares the flow rate detecting output with the comparative output and outputs an 'on' or 'off' signal as a flowing water switching output in accordance with the compared results, a bridge circuit 41 composed of a temperature-measuring resistor 18 for detecting exothermic resistor and a temperature-measuring resistor 19 for comparison, and a means 42 which corrects the nonconformities between the thermistor constants of the resistors 18 and 19 for making the differential voltage of the bridge circuit 41 a flow rate detecting output such that does not substantially depend upon the temperature of the fluid, but only corresponds to the flow rate of the fluid.