초록 ▼

A diesel engine adapted for operation under retarded fuel ignition timing relative to conventional fuel injection timing includes a piston shaped to increase the compression ratio of an engine cylinder, and specially designed combustion air intake and exhaust gas ports that increase scavenging flow

A diesel engine adapted for operation under retarded fuel ignition timing relative to conventional fuel injection timing includes a piston shaped to increase the compression ratio of an engine cylinder, and specially designed combustion air intake and exhaust gas ports that increase scavenging flow of exhaust gases and allow for manipulation of air intake and exhaust gas valves with a cam shaft. Thus, an engine may be operated under retarded fuel injection timing to decrease emissions of nitrogen oxides without sacrificing engine performance and efficiency.

대표청구항 ▼

[ What is claimed is:] [1.]1. A relatively large cylinder displacement volume, medium-speed compression ignition engine comprising:an engine block having at least one cylinder therein;a cylinder head covering the cylinder;a piston reciprocating in the cylinder between a top dead center position clos

[ What is claimed is:] [1.]1. A relatively large cylinder displacement volume, medium-speed compression ignition engine comprising:an engine block having at least one cylinder therein;a cylinder head covering the cylinder;a piston reciprocating in the cylinder between a top dead center position closely adjacent the cylinder head and a bottom dead center position spaced apart from the cylinder head;at least one combustion air intake port and at least one exhaust gas port extending through the cylinder head;the piston having a crown presenting a crown surface configured to reduce the clearance between the piston crown and the cylinder head when the piston is at its top dead center position for an increased compression ratio, the crown surface having a raised annular peripheral portion, a raised central portion and a recessed annular portion between the central and peripheral portions, with a generally smooth surface transition between the peripheral and recessed portions and between the recessed and central portions and a top of the raised central portion and a top of the raised peripheral portion being at generally the same level and the recessed portion presenting a generally shallow profile; andfuel injection for the injection of fuel at a timing relative to the position of the piston in the cylinder;with the engine having the midpoint of its fuel injection interval timed at a point after the top dead center position of the piston, which together with the increased compression ratio provides for reduced emissions of nitrogen oxides without loss of engine performance and efficiency.