Patent ID: 8069828
Filing Date: 2011-12-06
Classification: F01L

Abstract:
1. An internal combustion engine comprising: an intake system through which air enters at least one engine cylinder within which the air supports combustion of fuel to operate the engine; an exhaust system through which products of in-cylinder combustion are exhausted; cylinder valves for controlling communication of the respective systems with the at least one cylinder, one of which valves is biased closed by a valve spring to seat on a valve seat but is increasingly opened by a rocker of a valve opening mechanism pivoting about a relocatable pivot axis and increasingly compressing the valve spring; a hydraulic actuator for hydraulically locking the relocatable pivot axis against relocation as the one valve is being increasingly opened by the rocker, and with the one valve open, unlocking the relocatable pivot axis to allow the valve spring to increasingly expand and simultaneously force the one valve toward the valve seat and the relocatable pivot axis to relocate; a hydraulic fluid pressure source for delivering hydraulic fluid through a first check valve to a variable volume chamber of a hydraulic snubber that is disposed to snub motion of the one valve toward the valve seat, through a second check valve to a variable volume chamber of the hydraulic actuator, and to a hydraulic accumulator that is in fluid communication with the variable volume chamber of the hydraulic snubber and a first port of a control valve that has a second port in fluid communication with the variable volume chamber of the hydraulic actuator; the variable volume chamber of the hydraulic snubber being cooperatively defined by a snubbing element and by a snubber body with respect to which the snubbing element is extendable and retractable; the snubbing element and the snubber body collectively comprising a variable restriction through which the variable volume chamber of the hydraulic snubber is in fluid communication with the hydraulic accumulator, the hydraulic fluid pressure source, and the first port of the control valve, and which decreases and increases respectively as the snubbing element extends and retracts respectively relative to the snubber body; the hydraulic fluid source and accumulator collectively being effective, as the valve opening mechanism is increasingly opening the one valve, to force hydraulic fluid into the variable volume chamber of the hydraulic snubber and thereby extend the snubbing element relative to the snubber body; during increasing opening of the one valve by the valve opening mechanism, the control valve closing the first port to the second port to hydraulically lock the hydraulic actuator by preventing hydraulic fluid that had been forced into the variable volume chamber of the hydraulic actuator before the one valve was unseated from the valve seat from escaping from the variable volume chamber of the hydraulic actuator; and with the one valve open, the control valve opening the first port to the second port to unlock the hydraulic actuator by communicating the variable volume chamber of the hydraulic actuator to the accumulator and consequently allow the valve spring to force hydraulic fluid out of the variable volume chamber of the hydraulic actuator into the accumulator as the one valve is being forced toward the seat by the valve spring and snubbed by interaction with the hydraulic snubber that forces the snubbing element to retract and force fluid out of the variable volume chamber of the hydraulic snubber into the accumulator with increasing restriction as the one valve moves toward the seat.