Hydraulic valve control

摘要

An i. c. engine poppet valve 7 biased closed by a spring 14 is opened by control of the hydraulic pressure acting in a chamber 11 on a piston 8. A valve 27 connects the chamber 11 to a reservoir 38 in place of a connection to a pump via a line 45. The pump pressure in a chamber 18 at the end of the valve stem 2 or a spring acting on the stem causes valve opening when the pressure in the chamber 11 is relieved by connection to the reservoir 38. The pressure or force acting on the valve stem end is variable during valve operation. Chambers 28 and 29 at opposite ends of the piston 8 which are vented to the reservoir 38 in the end positions provide for a net valve closing force on the piston when the valve 7 is closed and a net valve opening force when the valve is fully open (Fig. 3). The chambers 18, 28 and 29 are connected to the reservoir 38 by valving between the stem 2 and its bore.