Patent ID: 6772719
Filing Date: 2004-08-10
Classification: F01L

Abstract:
An operating system for a hydraulic valve clearance control element (4) of an internal combustion engine having a hydraulic fluid with a pressure that depends on the engine operating state, said hydraulic valve clearance control element (4) comprising a cylinder part (101) and a piston part (102) defining a pressure chamber (120) having a hydraulic fluid supply opening and a hydraulic fluid drain, said piston part (102) being movable relative to said cylinder part (101) with changing volume of said pressure chamber (120) between opposite end positions, said pressure chamber (120) being in communication with a pressurized hydraulic fluid source (5) by way of said hydraulic fluid supply opening, a one way valve (104) disposed in said hydraulic fluid supply opening which is closed when the hydraulic fluid pressure of said hydraulic fluid source is below the hydraulic pressure in said pressure chamber (120), a blocking valve (105) arranged upstream of said one way valve (104) said blocking valve (105) being open only when the pressure of the fluid supply for said valve clearance control element is above a predetermined value, a hydraulic fluid drain including a passage (121) for returning leakage fluid from said pressure chamber to said fluid supply when said blocking valve (105) is open, and an electromagentically operated pressure release valve (8) arranged in the communication line (6) between said hydraulic fluid source (5) and said blocking valve (105) for releasing hydraulic fluid from said communication line (6) so as to reduce its pressure to a value at which said blocking valve (105) is closed immediately upon shut-down of the engine.