Systems and methods for intermittent supply of lubricating oil to a tip of a rocker arm assembly. In one embodiment, a lubricating oil may be selectively to a tip of a rocker arm via oil channels aligned only during opening of a valve coupled to the tip.

An engine oil passage structure for an engine contributing to downsizing the engine and achieving protection of an oil passage against external forces is provided. Provided is an oil passage structure for an engine installed in a small vehicle, the engine including an engine body formed of a crankcase and a cylinder block and a cylinder head stacked inclined vehicle frontward on the crankcase, the crankcase, the cylinder block, and the cylinder head being integrally fastened. The oil passage structure includes, near a bent part formed by a case front wall of the crankcase and a cylinder front wall of the cylinder block forming a valley part by an obtuse angle, a right-left direction oil passage extending in a right-left direction along the valley part.

An oil supply path passes through members separate from a cylinder head (4) to supply a lubricant to bearings (73, 74) of camshaft journals. The oil supply path includes an oil supply passage (66) for the camshaft above the camshaft (19, 20), a connection passage (64) for the camshaft between the oil supply passage for the camshaft and an internal passage (61, 62) in the cylinder head (4), and branch oil passages (68) for the camshaft journals. Each branch oil passage branches off from the oil supply passage for the camshaft, and is connected to one of the bearings (73, 74) from above. Each of the branch passages includes a throttle (168) with a smaller cross-sectional flow area than the oil supply passage for the camshaft.

A gearbox comprising an input shaft fixed with a first gear, an output shaft fixed with a second gear, and a rim gear without a web or hub rotatably mounted on a shaft having a hollow space. A lubrication line extends from within the shaft to a lubrication space disposed between an inner surface of the rim gear and an outer surface of the shaft. The rim gear is held in place on the shaft by a first interior surface of a first chamber member and a second interior surface of a second chamber member.

A switchable valve train assembly including a carrier housing defining a hydraulic circuit, a supply assembly, a plurality of rocker shafts, a plurality of separators, and a plurality of rocker arm assemblies is provided. Each one of the plurality of separators divides the rocker shafts into (1) a first chamber extending between a first chamber axial end and the separator, and (2) a second chamber extending between a second chamber axial end and the separator. The plurality of separators each include an orifice defined between the first chamber and the second chamber that provides fluid connection between the first chamber and the second chamber. Locking assemblies of the rocker arm assemblies are selectively actuated based on the supply assembly. The separators ensure that hydraulic fluid within the hydraulic fluid is de-aerated and that the second chambers remain primed with hydraulic fluid for faster actuation of the locking assemblies.

Systems and methods for operating an engine with deactivating valves are presented. In one example, a groove in a camshaft controls oil flow to a valve operator that selectively activates and deactivates a poppet valve of a cylinder. The groove moves with the camshaft so that oil delivery to the valve operator is timed properly to deactivate and reactivate the cylinder.

In a valve train of an internal combustion engine, an input sprocket mounting portion is provided on one end of an exhaust camshaft, and a valve operating cam portion is formed on the other end of the camshaft. A decompression shaft of a decompression device is inserted in a decompression shaft hole, which is formed from the input sprocket mounting portion toward the valve operating cam portion. The decompression shaft hole is formed at a position offset from an axis of the camshaft. A camshaft inner oil passage is formed in the camshaft to extend from one end toward the other end of the camshaft in parallel arrangement to the decompression shaft hole to supply lubricant from the bearing journal portion to the bearing journal portion. The above arrangement makes it possible to supply a sufficient amount of lubricant oil to slide portions of the valve train of a saddle riding vehicle.

An oil supply path passes through members separate from a cylinder head (4) to supply a lubricant to bearings (73, 74) of camshaft journals. The oil supply path includes an oil supply passage (66) for the camshaft above the camshaft (19, 20), a connection passage (64) for the camshaft between the oil supply passage for the camshaft and an internal passage (61, 62) in the cylinder head (4), and branch oil passages (68) for the camshaft journals. Each branch oil passage branches off from the oil supply passage for the camshaft, and is connected to one of the bearings (73, 74) from above. Each of the branch passages includes a throttle (168) with a smaller cross-sectional flow area than the oil supply passage for the camshaft.

A continuous variable valve duration apparatus may include: a camshaft; first and second cam portions on which a cam is formed respectively; first and second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively; a slider housing in which the first and the second inner brackets are rotatably inserted; first and second guiding portions formed on the slider housing; a control shaft parallel to the camshaft; a control rod eccentrically formed on the control shaft; a positioning protrusion connected to the control shaft; a guide head on which a head guiding portion and a head hole are formed; a cam cap supporting rotations of the first and the second cam portions and guiding movement of the slider housing, a control portion selectively rotating the control shaft; and a stopper unit limiting movement of the positioning protrusion.

A continuous variable valve duration apparatus may include: a camshaft; first and second cam portions on which a cam is formed respectively; first and second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively; a slider housing in which the first and the second inner brackets are rotatably inserted; first and second guiding portions formed on the slider housing; a cam cap on which a cam cap guide contacting the second guiding portion is formed; a control shaft parallel to the camshaft; a control rod eccentrically formed on the control shaft; a guide head on which a head guiding portion and a head hole are formed; a control portion selectively rotating the control shaft; and a stopper limiting movement of the guide head. The head guiding portion is connected to the first guiding portion, and the control rod is inserted into the head hole.