Patent ID: 7213553

Claim:
For use in a four-stroke, internal combustion, compression-ignition engine having at least one engine cylinder, at least one combustion chamber and a crankshaft, an internal exhaust gas recirculation (EGR) system for reducing oxides of nitrogen (NOx), for each combustion chamber the system comprising: at least one intake valve disposed to admit air into the combustion chamber; and at least one exhaust gas intake valve; a rocker arm shaft fixedly supported by the engine; an intake rocker arm assembly having a driven end portion and a driving end portion and being pivotally supported at a generally central location between the two end portions by the rocker arm shaft, the at least one intake valve being opened in response to an intake-valve-actuating force that emanates from the driving end portion when the intake rocker arm assembly is pivoted in a first angular direction, the at least one exhaust gas intake valve being opened in response to an exhaust-gas-intake-valve-actuating force that emanates from a point between the driven end portion and the rocker arm shaft when the intake rocker arm assembly is pivoted in the first angular direction; a force transfer assembly fixedly disposed relative to the engine for communicating the exhaust-gas-intake-valve-actuating force from the intake rocker arm assembly to the at least one exhaust gas intake valve; and a cam mounted on and rotatable with a camshaft to pivot the intake rocker arm assembly in the first angular direction, the configurations and relative orientations of the intake rocker arm assembly and the force transfer assembly being such that the exhaust gas intake valve is opened during at least a portion of an engine intake stroke when the intake valve is open and the pressure of exhaust gas is greater than the pressure of gas in the combustion chamber, thus allowing exhaust gas to flow into the combustion chamber to establish internal exhaust gas recirculation.