| 摘要 |
PURPOSE:To obtain a small-sized, inexpensive and highly accurate flowmeter with durability by burying a piezoelectric element of a thickness slide mode in an inwall of a fluid channel and combining a resistance piece as a flow resistor with the piezoelectric element. CONSTITUTION:When the fluid flow in the arrow direction in figure is generated in the channel 10 of the flowmeter 1 via a hose 12, the resistance piece 6a projecting in the channel 10 receives the pressure by the flow and the inner surface of the piezoelectric element 5 receives a vibration generating in the flowing direction by a vortex generating at the downstream side of the resistance piece 6a. In accordance with this, the piezoelectric element 5 of the thickness shear mode converts the vibrational force into an electrical signal. Here, since the flow velocity is proportional to the flow rate and the flow velocity has the proportional relation with the size and velocity of the vortex generating at the downstream side of the resistance piece 6a, the flow velocity and flow rate can be known by electrical output generating on the piezoelectric element 5. Then, the processing of the electrical output generating on the piezoelectric element 5 is made to detect an effective value of the voltage or the quantity of electric charge and displayed on a charge amplifier 13.
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