| abstract |
A diesel engine and method for operating a diesel engine with exhaust after-treatment device regeneration capability are disclosed. The diesel engine may employ an exhaust after-treatment device such as a diesel particular filter to remove soot from the combustion gases exhausted by the engine. In order to regenerate the exhaust after-treatment device, the temperature of the exhaust gases is raised sufficiently to do so. The temperature of the exhaust gases is raised to such a level by employing multiple compression and expansion strokes of the piston in certain engine cycles, with a combustion event associated with each pair of compression and expansion strokes. The engine may operate in a four stroke, one combustion cycle during conventional power operation, and switch to an enhanced combustion cycle during regeneration. The enhanced combustion cycle may include eight strokes such as one intake stroke, three compression strokes, three expansion strokes, and one exhaust stroke, with three combustion events. The engine may switch between cycles by using a cam follower with lost motion device capability, an electrical actuator, or any other selectively actuable valve actuator to prevent opening of the intake and exhaust valves during regeneration. |