Mack Trucks, Inc.

Charlie C Kim

Jeffrey S Zsoldos

William A Meacock

Robert Gorman

A system for accomplishing engine exhaust braking and exhaust gas recirculation for an engine having an exhaust manifold and a plurality of exhaust valves per cylinder during a four stroke engine cycle is provided. The system includes an actuation device operable to provide valve actuation of a single exhaust valve for an exhaust braking event and an exhaust gas recirculation event. The exhaust valve is not completely closed during the exhaust braking event and the exhaust gas recirculation event. The exhaust braking event includes actuating a single exhaust valve beginning during a second half of a compression stroke and a first half of an expansion stroke, and closing the exhaust valve beginning during a second half of an exhaust stroke. The exhaust gas recirculation event includes reactuating the exhaust valve beginning during a first half of an intake stroke, and closings the exhaust valve beginning during a second half of the intake stroke. Since a single exhaust valve is actuated during the exhaust braking and exhaust gas recirculation events, the overall performance of the vehicle is increased.

Method and apparatus for combining exhaust gas recirculation and engine exhaust braking using single valve actuation

A turbocharged internal combustion engine assembly with exhaust gas recirculation (EGR) includes an air compressor driven by an exhaust turbine, an EGR line that diverts exhaust gases from an exhaust line leading from the engine to an air intake line leading to the engine from the compressor, and a combustion bypass line that conveys compressed air from the compressor to the exhaust turbine without combustion. A pressure adjusting feature disposed along at least one of the air intake line and the exhaust line maintains the pressure at the turbine inlet below the pressure at the compressor outlet and above the pressure at the air inlet of the engine. Examples of suitable pressure adjusting features include a venturi placed in the air intake line at the second point, a power turbine located along the exhaust line downstream of the exhaust turbine, a split exhaust manifold feeding unequal turbine inlets, and an orifice located along the exhaust line between the EGR line and the bypass line.

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Martinsburg, WV, United States of America

Charlie C Kim