Fluid flow rate measuring device and water meter

摘要

There is offered a water meter that requires no coil so that its cost is reduced. The water meter is formed to include an impeller, a rotation reduction unit, a first circular plate, a second circular plate, a rotation detection unit and an arithmetic unit. The rotation detection unit forms first, second and third combination capacitors with a switching circuit. The rotation detection unit detects changes in capacitances of the first, second and third combination capacitors associated with a rotation of the first circular plate. The arithmetic unit is configured so as to electrically detect the rotation angle θ of the first circular plate based on the changes in the capacitances.

主权项

1. A fluid flow rate measuring device comprising:
a first circular plate comprising a fan-shaped common capacitor electrode disposed on a principal of the first circular plate surface and an insulator portion disposed on the rest of the principal surface; a rotation device rotating the first circular plate at a rotation speed proportional to a flow rate of a fluid; a second circular plate superposed above the principal surface of the first circular plate with a certain space therebetween and comprising a first, a second and a third fan-shaped capacitor electrodes disposed on a principal surface of the second circular plate point-symmetrically with respect to a center of its principal surface; and a rotation detection unit detecting a capacitance of each of first, second and third capacitors each formed between the common capacitor electrode and each of the first, second and third capacitor electrodes, respectively.