Four-cycle engine

Claim 2

A four-cycle engine characterized in that a gear on a crankshaft is made to engage with an internal gear having twice the number of teeth of the former gear, cams are formed on the exterior surface of the internal gear, the cams are connected with valve actuating mechanisms for actuating an exhaust valve and an intake valve to open or close, the crankshaft is supported by a crankcase cover of the engine via a first bearing and by a crankcase of the engine via a second bearing, the internal gear is sealed within and directly supported by the crankcase cover and the crankcase, and the first bearing and second bearing are positioned to directly face opposite sides of the gear such that the first bearing and second bearing support the gear and maintain a desired engagement condition between the gear and the internal gear.

Claim 3

The four-cycle engine of claim 1 wherein the space between said gear and said internal gear is hermetically sealed, a member for bisecting the space is provided, a suction port for lubricating oil is provided in one of the bisected spaces, a discharge port is provided in the other bisected space, at least one lubricating oil route is connected to the suction port, and at least one lubricating oil route is connected to the discharge port.

Claim 4

A four-cycle engine comprising: a crankshaft positioned within a crankcase and a crankcase cover of the engine, said crankshaft including a crankshaft gear with teeth; a first bearing positioned between said crankshaft and the crankcase cover such that the crankcase cover supports said crankshaft via said first bearing; a second bearing positioned between said crankshaft and the crankcase such that the crankcase supports said crankshaft via said second bearing; an internal gear mechanically coupled to said crankshaft gear, said internal gear including twice the number of teeth of said crankshaft gear, said internal gear including cams on an external surface thereof, said cams being mechanically coupled to a valve actuating mechanism of the engine, said internal gear being sealed within and rotatably supported by the crankcase forming an oil pump constructed from the crankshaft gear and said internal gear; said first bearing and said second bearing being positioned to directly face opposing sides of said crankshaft gear such that said first and second bearings support said crankshaft gear and maintain a desired engagement condition between said crankshaft gear and said internal gear; a first oil route from the oil pump directing oil to the cams; and a second oil route from the oil pump directing oil to said first bearing.

Claim 5

A four-cycle engine comprising: a crankshaft positioned within a crankcase and a crankcase cover of the engine, said crankshaft including a crankshaft gear with teeth; a first bearing positioned between said crankshaft and the crankcase cover such that the crankcase cover supports said crankshaft via said first bearing; a second bearing positioned between said crankshaft and the crankcase such that the crankcase supports said crankshaft via said second bearing; an internal gear mechanically coupled to said crankshaft gear, said internal gear including twice the number of teeth of said crankshaft gear, said internal gear including cams on an external surface thereof, said cams being mechanically coupled to a valve actuating mechanism of the engine, said internal gear being sealed within and rotatably supported by the crankcase forming an oil pump constructed from the crankshaft gear and said internal gear; said first bearing and said second bearing being positioned to directly face opposing sides of said crankshaft gear such that said first and second bearings support said crankshaft gear and maintain a desired engagement condition between said crankshaft gear and said internal gear; a first oil route from the oil pump directing oil to the cams; and a second oil route from the oil pump directing oil to said first bearing.

Claim 6

The four-cycle engine of claim 3 wherein said crankshaft gear and said internal gear define a sealed chamber therebetween, the engine further comprising: a spacer mechanism positioned in said sealed chamber between said crankshaft gear and said internal gear, said spacer mechanism partitioning said sealed chamber defining a suction port and a discharge port for a lubricating oil.

Claim 7

The four-cycle engine of claim 3 wherein said first bearing comprises a bush-type bearing.

Claim 8

The four-cycle engine of claim 3 wherein said second bearing comprises a bush-type bearing.

Claim 9

The four-cycle engine of claim 3 wherein said second bearing comprises a rolling bearing.

Claim 10

A four-cycle engine comprising: a crankshaft including a crankshaft gear with teeth; an internal gearing mechanically coupled to said crankshaft gear, said internal gear including cams on an external surface thereof, the cams being mechanically coupled to a valve actuating mechanism of the engine; a crankcase; a crankcase cover; said crankcase rotatably forming a concavity accommodating and rotatably supporting said internal gearing, the concavity being sealed to provide an oil pump constructed from said internal gearing, the crankshaft gear, and a spacer accommodated within the concavity; a first bearing positioned between said crankshaft and said crankcase cover such that said crankcase cover supports said crankshaft via said first bearing; a second bearing positioned between said crankshaft and said crankcase such that said crankcase supports said crankshaft via said second bearing; said first and second bearings being positioned on opposing sides of the crankshaft gear; a first oil route from the oil pump directing oil to the cams; a second oil route from the oil pump directing oil to said first bearing; and a third oil route from the oil pump directing oil to said second bearing.

Claim 11

A four-cycle engine comprising: a crankshaft including a crankshaft gear with teeth; an internal gearing mechanically coupled to said crankshaft gear, said internal gear including cams on an external surface thereof, the cams being mechanically coupled to a valve actuating mechanism of the engine; a crankcase; a crankcase cover; said crankcase rotatably forming a concavity accommodating and rotatably supporting said internal gearing, the concavity being sealed to provide an oil pump constructed from said internal gearing, the crankshaft gear, and a spacer accommodated within the concavity; a first bearing positioned between said crankshaft and said crankcase cover such that said crankcase cover supports said crankshaft via said first bearing; a second bearing positioned between said crankshaft and said crankcase such that said crankcase supports said crankshaft via said second bearing; said first and second bearings being positioned on opposing sides of the crankshaft gear; a first oil route from the oil pump directing oil to the cams; a second oil route from the oil pump directing oil to said first bearing; and a third oil route from the oil pump directing oil to said second bearing.