An internal combustion engine includes at least one cylinder crankcase, at least one cylinder head (1), at least one overhead camshaft (2), at least two rocker arms (3) which are driven by the camshaft (2) and actuate the combustion valves, the camshaft(s) (2) being mounted in the cylinder head housing, and an oil supply line (9) which is situated in particular in the area of the top face of the cylinder head (1) for lubricating camshaft bearing brackets (10) and the rocker arm brackets (11).

The present utility model discloses a portable four-stroke engine, comprising: an engine body, a flywheel and an oil storage tank, wherein an air valve distribution chamber and a crank shaft chamber are arranged in the engine; a crank shaft is arranged in the crank shaft chamber, and is connected to the flywheel; the oil storage tank is arranged on the engine body, located above the flywheel, and configured to store lubricating oil; a cam and a rocker arm mechanism are arranged in the air valve distribution chamber; and the cam is configured to drive the rocker arm mechanism. The portable four-stroke engine provided by the present utility model has a small volume and therefore has better operation performance.

An internal combustion engine with a reduced size while securing a sufficient amount of lubricating oil for rocker shafts in the internal combustion engine. A cam holder formed in a cylinder head extends from a rear wall portion of the cylinder head toward the attachment hole, and an intake-side downstream rocker shaft oil supply passage formed in a cross shape by causing two linear portions to intersect each other is formed inside the cam holder. In the intake-side downstream rocker shaft oil supply passage, one of the linear portions communicates with a left intake-side support hole located on a left side and configured to support a left intake-side rocker shaft, while the other one of the linear portions communicates with a right intake-side support hole located on a right side and configured to support a right intake-side rocker shaft.

An internal combustion engine with a reduced size while securing a sufficient amount of lubricating oil for rocker shafts in the internal combustion engine. A cam holder formed in a cylinder head extends from a rear wall portion of the cylinder head toward the attachment hole, and an intake-side downstream rocker shaft oil supply passage formed in a cross shape by causing two linear portions to intersect each other is formed inside the cam holder. In the intake-side downstream rocker shaft oil supply passage, one of the linear portions communicates with a left intake-side support hole located on a left side and configured to support a left intake-side rocker shaft, while the other one of the linear portions communicates with a right intake-side support hole located on a right side and configured to support a right intake-side rocker shaft.

A rocker shaft assembly configured to support a rocker arm and deliver oil to the rocker arm and related method of making is provided. The rocker shaft assembly includes a core shaft and a sleeve. The core shaft has a core body including a main oil supply channel formed thereon. The sleeve has passages formed thereon. The sleeve is disposed around the core shaft. The main oil supply channel aligns with at least one of the passages on the sleeve. The main oil supply is milled into the core shaft.

A rocker arm assembly for translating force between an intermediate member in communication with a camshaft of an internal combustion engine and a valve supported in a cylinder head of the engine. The rocker arm assembly includes a tube member and an arm. The tube member has first and second ends, a substantially cylindrical inner surface, and a tapered outer surface. The arm has a body extending between a pad for engaging the valve of the engine, and a socket for engaging the intermediate member of the engine. The body also has a tapered bore disposed between the pad and the socket. The tapered bore of the body of the arm cooperates with the tapered outer surface of the tube member so as to define a lock for constraining the arm to the tube member at a predetermined position between the first end and the second end.

A valvetrain for translating force and oil between a valve and intermediate member of an engine, including a rocker, a shaft, and a recess. The rocker has an inner surface, a pad for engaging the valve, a socket for engaging the intermediate member, a socket port defined in the surface, and a socket channel extending from the socket port to the socket. The shaft has a bearing surface for supporting the rocker, a channel spaced from the bearing surface, a feed port in the bearing surface, and a feed channel extending from the feed port to the channel. The rocker rotates between: closed, with the socket port and feed port aligned; and open, with the socket port spaced from the feed port. A recess is disposed in the bearing surface adjacent to the feed port and extends to a base aligned with the socket port when the rocker is open.

A rocker shaft assembly configured to support a rocker arm and deliver oil to the rocker arm and related method of making is provided. The rocker shaft assembly includes a core shaft and a sleeve. The core shaft has a core body including a main oil supply channel formed thereon. The sleeve has passages formed thereon. The sleeve is disposed around the core shaft. The main oil supply channel aligns with at least one of the passages on the sleeve. The main oil supply is milled into the core shaft.

A variable valve device includes a pair of cam housings separated from each other in a predetermined direction, a pair of rocker shafts supported by the pair of cam housings, a plurality of rocker arms supported by the pair of rocker shafts in a swingable manner, a switching mechanism that couples and separates intake arms, and an upper housing on the pair of cam housings. The upper housing is formed with a first injection hole for supplying lubrication oil to the switching mechanism and a second injection hole for supplying lubrication oil to the rocker arms. A passage length from a lubrication groove around a camshaft to the second injection hole is larger than a passage length from the lubrication groove to the first injection hole.

A variable valve device includes a pair of cam housings separated from each other in a predetermined direction, a pair of rocker shafts supported by the pair of cam housings, a plurality of rocker arms supported by the pair of rocker shafts in a swingable manner, a switching mechanism that couples and separates intake arms, and an upper housing on the pair of cam housings. The upper housing is formed with a first injection hole for supplying lubrication oil to the switching mechanism and a second injection hole for supplying lubrication oil to the rocker arms. A passage length from a lubrication groove around a camshaft to the second injection hole is larger than a passage length from the lubrication groove to the first injection hole.