Diesel engine with blowby scavenging

Claim 2

In a diesel engine of the type having a cylinder with closed and open ends, a piston reciprocable in the cylinder and defining therewith a variable volume combustion chamber at the cylinder closed end, means at the cylinder closed end for admitting charging fluids to and exhausting residual products from the combustion chamber, a lubricant chamber at the open end of the cylinder, the piston having a skirt bearing on the cylinder under side thrust loading, and at least two spaced sealing rings on the piston and engaging the cylinder to limit the passage of combustion blowby products and lubricant from their respective chambers to the other, at least the top one of said sealing rings being located between the skirt and the combustion chamber end of the piston, and the improvement comprising an annular recess around the piston between the skirt and said top sealing ring, said recess comprising a blowby storage space of volume sufficient to collect a substantial amount of the blowby gases which escape from the combustion chamber past the top one of said sealing rings during each cycle of piston reciprocating motion, and blowby scavening means intermittently communicating with said recess to carry away blowby gases collected therein and thereby reduce contamination of the lubricant with particulates from the combustion products, said blowby scavenging means including an air supply passage in the cylinder and positined to communicate with the piston recess near the bottom position of piston motion and to be closed by the pistion skirt during other portions of the piston motion.

Claim 3

In a diesel engine of the type having acylinder with closed and open ends, a piston reciprocable in the cylinder and defining therewith a variable volume combustion chamber at the cylinder closed end, means at the cylinder closed end for admitting charging fluids to and exhausting residual products from the combustion chamber, a lubricant chamber at the open end of the cylinder, the piston having a skirt bearing on the cylinder under side thrust loading, and at least two spaced sealing rings on the piston and engaging the cylinder to limit the passage of combustion blowby products and lubricant from their respective chambers to the other, at least the top one of said sealing rings being located between the skirt and the combustion chamber end of the piston, and the improvement comprising an annular recess around the piston between the skirt and said top sealing ring, said recess comprising a blowby storage space of volume sufficient to collect a substantial amount of the blowby gases which escape from the combustion chamber past the top one of said sealing rings during each cycle of piston reciprocating motion, and blowby scavenging means intermittently communicating with said recess to carry away blowby gases collected therein and thereby reduce contamination of the lubricant with particulates from the combustion products, said blowby scavenging means including an air supply passage in the cylinder and positioned to communicate with the piston recess near the bottom position of piston motion and to be closed by the piston skirt during other portions of the piston motion, at least the bottom one of said sealing rings being an oil control ring located on the piston skirt below the position of said air supply passage at the top position motion to avoid passing scavenging air through the oil ring groove and any resultant oil carryover.

Claim 4

In a diesel engine of the type having acylinder with closed and open ends, a piston reciprocable in the cylinder and defining therewith a variable volume combustion chamber at the cylinder closed end, means at the cylinder closed end for admitting charging fluids to and exhausting residual products from the combustion chamber, a lubricant chamber at the open end of the cylinder, the piston having a skirt bearing on the cylinder under side thrust loading, and at least two spaced sealing rings on the piston and engaging the cylinder to limit the passage of combustion blowby products and lubricant from their respective chambers to the other, at least the top one of said sealing rings being located between the skirt and the combustion chamber end of the piston, and the improvement comprising an annular recess around the piston between the skirt and said top sealing ring, said recess comprising a blowby storage space of volume sufficient to collect a substantial amount of the blowby gases which escape from the combustion chamber past the top one of said sealing rings during each cycle of piston reciprocating motion, and blowby scavenging means intermittently communicating with said recess to carry away blowby gases collected therein and thereby reduce contamination of the lubricant with particulates from the combustion products, said blowby scavenging means including an air supply passage in the cylinder and positioned to communicate with the piston recess near the bottom position of piston motion and to be closed by the piston skirt during other portions of the piston motion, at least the bottom one of said sealing rings being an oil control ring located on the piston skirt below the position of said air supply passage at the top position motion to avoid passing scavenging air through the oil ring groove and any resultant oil carryover.

Claim 5

The combination of claim 1 or 2 wherein the blowby scavenging means further includes a gas discharge passage opening through the cylinder opposite the air supply passage and communicating with the engine induction system to recirculate to the engine intake blowby gases received from the blowby storage space between the seal rings near the bottom position of piston motion, said discharge passage also being closed by the piston skirt during other portions of the piston motion.

Claim 6

The combination of claim 1 or 2 wherein the blowby scavenging means further includes a gas discharge passage in the cylinder wall and communicating the blowby storage space with the adjacent combustion chamber near the bottom of piston motion to recirculate blowby gases directly to the respective combustion chamber, said discharge passage means also being closed by the piston skirt during other positions of piston motion.

Claim 7

The combination of claim 4 wherein said discharge passage is a groove in the cylinder wall that bypasses the seal ring between the combustion chamber and blowby storage space when the piston is at the bottom position of its motion.