| 摘要 |
PURPOSE:To make unnecessary the supply of a constant current and thereby to make an apparatus small in size and light in weight by a construction where in a swirling movement is given to an inflow gas by guide vanes provided at an inlet portion of a venturi tube, and a pulsating current of the gas is detected by a piezoelectric element. CONSTITUTION:A swirling movement is given to an inflow gas by guide vanes 3 provided at an inlet part of a venturi tube 1, and a pulsating current caused by the vortex flow of the gas is detected by a sensor 6 fitted in projection into the gas flow. In the sensor, which is constructed of a piezoelectric element, a bending displacement is caused under a periodical pressure given by the pulsating current. Accordingly, the supply of a constant electric current is made unnecessary, and the apparatus can be made small in size and light in weight. |
