System and method for preventing piston-valve collision on a non-freewheeling internal combustion engine

A valve actuation method for use in an internal combustion engine comprising at least one combustion cylinder having a piston and an engine valve, said engine comprising an electro-hydraulic valve actuation system for opening and dosing said engine valve, said valve actuation system comprising a hydraulic pump including a plunger mechanically coupled with a cam, said cam moving said plunger to create hydraulic pressure and being mechanically coupled to an engine crankshaft, said electro-hydraulic valve actuation system also including a second plunger fluidly connected with said hydraulic pump and mechanically connected with said engine valve for opening and closing said engine valve, said method comprising steps of:

• determining a piston-valve clearance profile of said piston and said engine valve for said, at least one combustion cylinder;
• and
• selecting a shape of said cain of said hydraulic pump based on said piston-valve clearance profile, such that said plunger moves toward said cam when valve-piston clearance of said piston and said engine valve approaches zero;
• wherein said valve actuation system further comprises a control chamber coupled with a high-pressure reservoir via a control valve, said method further comprising a step of:
• coupling an accumulator with said high-pressure reservoir;
• and
• providing a feedback loop from said control chamber to said high-pressure reservoir via a check valve, such that when the pressure in said control chamber exceeds the pressure in said high-pressure reservoir, hydraulic fluid flows to said high-pressure reservoir from said control chamber to prevent piston-valve collision.

An electro-hydraulic valve actuation system for use in an internal combustion engine comprising at least one combustion cylinder having an engine piston and an engine valve, said valve actuation system comprising:

• a hydraulic pump means for producing a hydraulic output of hydraulic fluid based on a valve-piston clearance profile of at least one cylinder of said combustion engine;
• a valve actuation means for actuating at least one engine valve of said combustion engine according to an output of hydraulic fluid of said pump means;
• a high pressure-reservoir means coupled with said hydraulic pump;
• a control chamber means coupled with said high-pressure reservoir;
• feedback means for redirecting hydraulic fluid from said valve actuation means when the engine piston moves close to the engine valve;
• and
• a check valve means disposed in said feedback means, for allowing hydraulic fluid flow from said control chamber to said high-pressure reservoir when pressure in said control chamber exceeds pressure in said high-pressure reservoir.