Internal combustion engine with vented piston clearance spaces and method

Claim 3

The method of claim 1 wherein said step of venting to the crankcase is performed continuously during engine operation.

Claim 4

The method of claim 2 wherein said venting of each said clearance space occurs through passage means provided in the wall of each piston at its second piston ring land.

Claim 5

In combination with a four stroke non-rotary spark ignition internal combustion engine having a crankcase, a plurality of cylinders having one of their ends open to the crankcase and closed at their other ends, pistons in the cylinders defining combustion chambers at the closed ends thereof and separating the combustion chambers from the crankcase and means permitting the cyclic admission of air and fuel to the combustion chambers and the discharge of exhaust gases therefrom said pistons each carrying first and second axially spaced gas sealing piston rings engaging said cylinder and defining a clearance space between said rings and between said piston and cylinder, each said first piston ring being disposed between a clearance space and a combustion chamber and having an end gas permitting limited passage of gas therethrough between each said combustion chamber and its respective clearance space and vent means through a wall of said piston and directly communicating said clearance space with the engine crankcase at least during the latter parts of the high pressure portions of the combustion chamber working cycle without increasing the gas leakage path past said first piston ring to said clearance space, said vent means being capable of expelling to said crankcase a sufficient portion of the gas entering said clearance space to prevent retention therein during the expansion and exhaust strokes of gas pressure significantly higher than in the adjacent combustion chamber.

Claim 6

In combination with a four stroke non-rotary spark ignition internal combustion engine having a crankcase, a plurality of cylinders having one of their ends open to the crankcase and closed at their other ends, pistons in the cylinders defining combustion chambers at the closed ends thereof and separating the combustion chambers from the crankcase and means permitting the cyclic admission of air and fuel to the combustion chambers and the discharge of exhaust gases therefrom said pistons each carrying first and second axially spaced gas sealing piston rings engaging said cylinder and defining a clearance space between said rings and between said piston and cylinder, each said first piston ring being disposed between a clearance space and a combustion chamber and having an end gas permitting limited passage of gas therethrough between each said combustion chamber and its respective clearance space and vent means through a wall of said piston and directly communicating said clearance space with the engine crankcase at least during the latter parts of the high pressure portions of the combustion chamber working cycle without increasing the gas leakage path past said first piston ring to said clearance space, said vent means being capable of expelling to said crankcase a sufficient portion of the gas entering said clearance space to prevent retention therein during the expansion and exhaust strokes of gas pressure significantly higher than in the adjacent combustion chamber.

Claim 7

The combination of claim 4 wherein said vent means comprise passage means extending radially through the piston wall between said first and second piston rings.

Claim 8

The combination of claim 5 wherein said vent means further comprise two of said passage means disposed on opposite sides of the piston.