Increased compression ratio diesel engine assembly for retarded fuel injection timing

A relatively large cylinder displacement volume, medium-speed compression ignition engine comprising:

• an engine block having at least one cylinder therein;
• a cylinder head presenting a generally planar surface covering the cylinder;
• a piston reciprocating in the cylinder between a top dead center position closely adjacent the cylinder head for providing an increased compression ratio, and a bottom dead center position spaced apart from the cylinder head;
• at least one combustion air intake port extending up from an air intake valve seat and at least one exhaust gas port extending through the cylinder head;
• at least one combustion air intake valve projecting down through the intake port and movable between a lowered position for opening the port for delivery of combustion air into the cylinder and a raised position in engagement with the air intake valve seat in the cylinder head for closing the port and defining in part the enclosed space of the cylinder;
• at least one exhaust gas valve projecting down through the exhaust gas port and movable between a lowered position for discharge of exhaust gas from the cylinder and a raised position in engagement with the exhaust gas valve seat in the cylinder head for closing the port and defining in part the enclosed space of the cylinder with the distance of downward movement of the air intake valve and the exhaust gas valve into the cylinder being limited so as to avoid contact with the piston crown when the piston is adjacent top dead center;
• and
• with the surfaces of the valve ports extending up from their respective valve seats presenting generally smooth transitions to enhance the flow of intake air and exhaust gases into and out of the cylinder through the limited distance provided by the limited downward movement of the valves when the piston is adjacent top dead center.

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 for providing an increased compression ratio, 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;
• a first valve cam operating through a cycle for moving a combustion air intake valve projecting down through the intake port between a lowered position for opening the port for delivery of combustion air to the cylinder and a raised portion in engagement with the cylinder head for closing the port and defining in part the enclosed space of the cylinder;
• a second valve cam operating through a cycle for moving an exhaust gas valve projecting down through the exhaust gas port between a lowered position for opening the port for discharge of exhaust gas from the cylinder and a raised position for closing the port and defining in part the enclosed space of the cylinders;
• the portion of the valve cycles during which the ports are open overlapping while the piston moves toward and away from top dead center;
• with the valve cam moving the valves downward a limited distance toward the piston crown for partial opening of the respective ports during the valve overlap period to avoid contact of the valves and the piston crown when the piston is adjacent top dead center;
• and
• fuel 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.

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;
• and
• fuel 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.