| 摘要 |
PROBLEM TO BE SOLVED: To provide a flow rate sensor having a simple circuit, and capable of detecting, with high accuracy, a detection signal corresponding to a fluid flow direction.SOLUTION: The average temperatures of an upstream-side heat-generation element 12a and a downstream-side heat-generation element 12b are maintained by an average temperature control part 1a at a temperature always higher by a prescribed temperature than the temperature of a fluid detected by a fluid temperature detection part 2. Heating currents flowing in the upstream-side heat-generation element 12a and the downstream-side heat-generation element 12b are controlled by a voltage ratio control part 8a so that a temperature difference or a ratio of applied voltages between the upstream-side heat-generation element 12a and the downstream-side heat-generation element 12b becomes equal to a prescribed value, and a detection signal corresponding to a fluid flow direction is obtained from the above control state, whereby determination is made as to whether the fluid flow direction is a forward flow or a reverse flow. |
