Patent ID: 8001941

Claim:
A lash adjuster which is provided in a valve gear, comprising: a cylindrical bottomed body; a cylindrical bottomed plunger which is provided in the body so as to be movable upward and downward and has an underside, the plunger including a high-pressure chamber which is defined between the underside thereof and a bottom wall of the body to reserve an operating oil; a leak path defined by an inner circumferential surface of the body and an outer circumferential surface of the plunger so that the operating oil reserved in the high-pressure chamber leaks therethrough with downward movement of the plunger; and a ring-shaped member provided between the inner circumferential surface of the body and the outer circumferential surface of the plunger, the ring-shaped member projecting into the leak path during a normal operation of the valve gear and being elastically deformed radially inward with increase in pressure of the operating oil at the high-pressure chamber side so as to be retreated from the leak path when an abnormal movement occurs in the valve gear such that the pressure of the operating oil in the high-pressure chamber exceeds a normal range thereof, thereby reducing flow resistance of the operating oil in the leak path, the ring-shaped member having a pressure-receiving surface which receives pressure of the operating oil in the high-pressure chamber thereby to elastically deform the ring-shaped member radially inward, the pressure-receiving surface being inclined relative to the radial direction.