Valve device and system in which the valve device is mounted

Abstract

A valve device that includes a valve body; a valve shaft configured to rotate the valve body; a coil spring being electrically conductive and configured to be twisted with rotation of the valve body and the valve shaft; a first conductive member being electrically conductive and facing an inner circumferential surface or an outer circumferential surface of the coil spring in a radial direction of the coil spring; and a first detector configured to detect at least one of a rotation angle of the valve body or a rotation angle of the valve shaft based on an electrostatic capacitance between the coil spring and the first conductive member, the electrostatic capacitance changing according to a state of the coil spring that changes with the rotation of the valve body and the valve shaft.

Dependencies are inferred from the claim text.