Patent attributes
A pressure adjustment unit includes a valve body including a base end portion, a shaft portion protruding in a first-direction from the base end portion, and an elastic member, and a casing that has a partition wall formed with a through hole into which the shaft portion is inserted, and a first-wall protruding in a second-direction opposite to the first-direction to define the first-chamber. On a first-chamber side of the partition wall, a valve seat, which is annular, is provided around the through hole to block a flow path by contacting with the elastic member, an outer periphery of the base end portion has a positioning region, and a distance between a first-direction-side end portion of the positioning region and a first-direction-side distal end of the shaft portion is shorter than a distance between the valve seat and a second-direction-side end portion of the first-wall.
