Compression release mechanism for an internal combustion engine

摘要

A compression release mechanism for a combustion chamber in an internal combustion engine comprises a pressure relief valve assembly and a control member. The valve assembly includes a valve body and a plunger cooperating with a vent passageway through the valve body to selectively allow pressure relief through the vent passageway. The control member cooperates with the plunger and is movable between an engaged position in which the control member urges the plunger toward the open position, and a disengaged position in which the plunger is held in the closed position. When the control member is engaged, the plunger oscillates between the open and closed positions in response to combustion chamber pressures during a combustion cycle which facilitates engine start-up while the compression release mechanism is engaged.