An engine camshaft has a lubricating oil passage formed along the longitudinal axis of the same, a cam communicating oil hole is radially formed from the lubricating oil passage to an outer peripheral surface of the camshaft at the same axial position as an engine valve. Cam lubrication holes are radially formed from the inside to cam surfaces of cam lobes formed around a cam carrier fitted around the camshaft. One of the cam lubrication holes of the cam lobes shifted to a position for operating the valve communicates with the cam communicating oil hole of the camshaft to supply lubricant oil.

A lubricating oil supply structure includes: a shaft; a bearing supporting the shaft and having an oil supply port, through which lubricating oil is supplied to between the shaft and the bearing, and an oil introduction port, through which the lubricating oil is introduced; a first oil passage, connected to the oil supply port, distributing the lubricating oil from an oil pump toward the oil supply port; a second oil passage, connected to the oil introduction port, supplying the lubricating oil introduced through the oil introduction port to a supply destination; a connection oil passage, formed by a gap between the bearing and the shaft, connecting between the first oil passage and the second oil passage, and a throttle portion, formed on a part of the connection oil passage, suppressing a flow of the lubricating oil from the oil supply port toward the oil introduction port.

An object of the present invention is to simplify portions of an oil supply passage which portions are formed at a cylinder block. An oil supply device according to the present invention includes a cylinder block, an oil pan, an oil pump, and an oil filter. Wall portions of the oil pan are coupled to wall portions of the cylinder block. An oil filter is attached to the oil pan. An upstream oil supply passage through which the oil filtrated by the oil filter flows is formed at the oil pan. A downstream oil supply passage including a main gallery extending in a cylinder column direction is formed at the cylinder block. A first communication passage through which the main gallery and the upstream oil supply passage communicate with each other is formed at the wall portion of the cylinder block and the wall portion of the oil pan.

A valve drive for a cylinder head of an internal combustion engine has a camshaft which is rotatably mounted in a first and a second camshaft bearing and which includes at least one cam with a first cam curve and a second cam curve that differs from the first cam curve. A gas exchange valve can be actuated by the first or the second cam curve via a cam follower. A camshaft section is provided, by which the cam can be moved by an actuator such that the gas exchange valve can be actuated either via the first or the second cam curve via the cam follower. The camshaft and the cam have a fixed position relative to each other. The camshaft can be axially moved in the first and the second camshaft bearing. The camshaft bearings consist of a camshaft bearing block and a common bearing frame. A lubricant supply bore is provided which opens into a fourth lubricant groove in the bearing frame in order to supply the bearing points with lubricant. A first lubricant groove is provided in the first camshaft bearing block, and a second lubricant groove is provided in the second camshaft bearing block. These lubricant grooves correspond to the fourth lubricant groove and are open in the direction of the cam follower.

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.

A cam chain tensioner device of an internal combustion engine includes a cam chain tensioner, and a tensioner lifter pressing the cam chain tensioner to a cam chain. The tensioner lifter is mounted on an inclined upper surface of the cylinder head. The cylinder head has therein a valve train oil supply passage supplying oil from an oil pump to the valve train camshafts, and a tensioner lifter oil supply passage supplying oil to the tensioner lifter. The valve gear oil supply passage has a branching portion where the tensioner lifter oil supply passage branches. The branching portion is at a position higher than the tensioner lifter, and communicates with the tensioner lifter disposed at a position lower than the branching portion. It is thus possible to prevent fluttering of the cam chain and to reduce noise generated by the cam chain at the time of restart of the engine after it is stopped.

A valve timing adjustment device includes: a driving rotating body that rotates with a crankshaft; a driven rotating body that rotates with a camshaft; a reduction mechanism configured to change a relative rotation phase of the driving rotating body and the driven rotating body by a driving force of an actuator; and a filter unit capable of capturing a foreign matter contained in lubricating fluid supplied into the reduction mechanism. The reduction mechanism includes: an internal gear portion having internal teeth formed inward in a radial direction, and an external gear portion having external teeth formed outward in the radial direction to mesh with the internal teeth. The driven rotating body has a supply hole penetrating in an axial direction. The filter unit has holes penetrating in the axial direction, and the holes are arranged in a flow path of the lubricating fluid connected to the supply hole.

The oil filter device is disposed on a side portion of one side of a cylinder body in a width direction in a cylinder head side with respect to an engine case in a space between center lines of main lubricating oil passages and a cylinder axis line of the cylinder body, and includes an oil pump disposed on the engine case and further lubricating oil passages that connect to the main lubricating oil passage.

An engine case includes bearings, an oil pump, lubricating oil passages, and a relief device. The bearings rotatably support a crankshaft and a camshaft. The oil pump and the lubricating oil passages are configured to pressure-feed lubricating oil to the bearings. The relief device is configured to adjust a pressure of the lubricating oil. The lubricating oil passages include main lubricating oil passages. The main lubricating oil passages include communication portions linearly formed with extending portions. The communication portions communicate between the respective bearings of the crankshaft and the camshaft from outside the engine case. The extending portions extend from outside the engine case to the bearing of the camshaft. The relief device is disposed having a relief valve and a relief hole at the extending portions.

An engine camshaft has a lubricating oil passage formed along the longitudinal axis of the same, a cam communicating oil hole is radially formed from the lubricating oil passage to an outer peripheral surface of the camshaft at the same axial position as an engine valve. Cam lubrication holes are radially formed from the inside to cam surfaces of cam lobes formed around a cam carrier fitted around the camshaft. One of the cam lubrication holes of the cam lobes shifted to a position for operating the valve communicates with the cam communicating oil hole of the camshaft to supply lubricant oil.