JPS6484053A - Valve gear - Google Patents

Abstract

PURPOSE: To improve a durability of a valve disc by providing a valve port at a head wall of a cylinder, supporting the disc for opening or closing the port to a valve operating member via an elastic element, and providing a vent hole for ventilating a space substantially sealed via slidable contact of the member with an inner surface of the cylinder and a space in the cylinder. CONSTITUTION: A sealing surface of a valve disc (sealing pad) 28 is brought into contact or separated from a head wall 2 merely in an axial direction, i.e., moved in a direction non-sliding to an inner surface of a cylinder 1 or the wall 2 to open or close a valve port (exhaust port) 21. Accordingly, no wear occurs on the sealing surface of the disc 28. And, a pressure contact force of the disc 28 is given by an elastic element 29 provided between the disc 28 and a valve operating member 22. A reaction force of the contact force is operated at the member 22 in a direction for separating the member 22 from the wall 2. When a piston 14 starts to move in a direction for separating from the wall 2, the member 22 is moved to a position where the reaction is balanced with a sliding resistance of the member 22, and then stopped. In this case, the contact force of the member 22 to the inner surface of the cylinder 1 is not changed due to a vent hole 45.