Patent ID: 7469583

Claim:
A flow sensor including: a flow channel having a pair of parallel portions; and a plurality of temperature sensing resistors for heating a fluid flowing through the flow channel to a preset temperature, the temperature sensing resistors being disposed on parts of the parallel portions of the flow channel to detect a fluid flow rate based on a change in temperature distribution of the flow channel due to a change in flow rate of the fluid flowing through the flow channel, wherein the plurality of temperature sensing resistors includes: a first upstream temperature sensing resistor and a first downstream temperature sensing resistor that are disposed in a line on one of the parallel portions; and a second upstream temperature sensing resistor and a second downstream temperature sensing resistor that are disposed in a line on the other parallel portion, and wherein the first upstream temperature sensing resistor is upstream of the first downstream temperature sensing resistor in a direction of flow of the fluid in the flow channel, the first downstream temperature sensing resistor is upstream of the second upstream temperature sensing resistor in the direction of flow of the fluid in the flow channel, and the second upstream temperature sensing resistor is upstream of the second downstream temperature sensing resistor in the direction of flow of the fluid in the flow channel wherein the first upstream temperature sensing resistor and the second upstream temperature sensing resistor are electrically connected as a combined upstream temperature sensing resistor, and the first downstream temperature sensing resistor and the second downstream temperature sensing resistor are electrically connected as a combined downstream temperature sensing resistor.