Patent ID: 7404382

Claim:
A variable engine valve control system with pressure difference comprising a hydraulic supply equipment, a hydraulic actuator apparatus, a valve and a spring for controlling piston balance; said hydraulic actuator includes a hydraulic cylinder, a piston and a piston rod; said piston rod is coupled and moved with said valve; wherein said piston divides said hydraulic cylinder into a upper chamber and a lower chamber; said hydraulic supply equipment is connected with said upper chamber of said hydraulic cylinder through a general fluid inlet pipe, and said lower chamber of the said hydraulic cylinder is connected with said hydraulic supply equipment through a pressure difference proportional relief valve; a hydraulically-controlled check valve connected with said pressure difference proportional relief valve in parallel is situated between the upper chamber of said hydraulic cylinder and the lower chamber of said hydraulic cylinder, thereby hydraulic fluid can enter into the lower chamber of said hydraulic cylinder from the upper chamber of said hydraulic-cylinder directly.