Four-stroke internal combustion engine

A four-stroke engine fueled by a combustible mixture of fuel, oil and air, said engine comprising:

• a) an engine frame forming a crankcase chamber, a cylinder, and a valve enclosure;
• b) a piston mounted for reciprocation in said cylinder and forming with said frame a combustion chamber, and said crankcase chamber having a volume which alternately increases and decreases with reciprocation of said piston;
• c) said frame having inlet and outlet ports leading to and from said crankcase chamber, said inlet port being connectable to a source of said mixture;
• d) a valve mechanism mounted in said valve enclosure and comprising a fuel intake valve, an exhaust valve, and a valve actuating mechanism, said intake valve when open connecting said enclosure with said combustion chamber, and said exhaust valve when open connecting said combustion chamber with the ambient air;
• e) and duct means connecting said outlet port with said enclosure for conducting the mixture from said crankcase chamber to said valve enclosure;
• f) said crankcase chamber and said valve enclosure, during engine operation, flowing a sufficient quantity of said mixture around said valve actuating mechanism to lubricate the parts thereof.

A multiple cylinder four-stroke engine fueled by a combustible mixture of fuel, oil and air, said engine comprising:

• a) an engine frame forming a crankcase chamber and first and second cylinders;
• b) first and second pistons mounted for reciprocation in said first and second cylinders respectively and forming with said frame first and second combustion chambers, said first and second pistons moving simultaneously toward or away from said crankcase chamber whereby said crankcase chamber has a volume which alternately increases and decreases with said reciprocation of said pistons;
• c) said frame further forming first and second valve enclosures adjacent said first and second combustion chambers, and said engine further including first and second valve mechanisms mounted in said first and second valve enclosures, respectively;
• d) each of said valve mechanisms comprising a fuel intake valve and an exhaust valve;
• e) said frame further including at least one inlet port leading to said crankcase chamber and at least one outlet port leading out of said crankcase chamber, said at least one inlet port being connectable to receive said mixture;
• and
• f) duct means connecting said at least one outlet port with said first and second valve enclosures and with said fuel intake valves, said mixture flowing through said crankcase chamber and said valve enclosures and lubricating the parts therein during engine operation.

A four-stroke engine fueled by a combustible mixture of fuel, oil and air, said engine comprising:

• a) an engine frame forming a crankcase chamber, a cylinder, and a valve enclosure;
• b) a piston mounted for reciprocation in said cylinder and forming with said frame a combustion chamber, and said crankcase chamber having a volume which alternately increases and decreases with reciprocation of said piston;
• c) said frame having inlet and outlet ports leading to and from said crankcase chamber, said inlet port being connectable to a source of said mixture;
• d) a valve mechanism mounted in said valve enclosure and comprising a fuel intake valve and an exhaust valve, said intake valve when open connecting said enclosure with said combustion chamber, and said exhaust valve when open connecting said combustion chamber with the ambient air;
• e) duct means connecting said outlet port with said enclosure for conducting the mixture from said crankcase chamber to said enclosure;
• f) said crankcase chamber and said valve enclosure flowing, during engine operation, a sufficient quantity of said mixture to lubricate the parts therein;
• and
• g) said cylinder being formed by a cylinder wall, said inlet port being formed in said cylinder wall at a location where said inlet port is alternately opened and closed by said reciprocation of said piston.