A cam follower assembly is provided including an improved lubricant flowpath. The assembly includes a generally cylindrical housing including an annular groove adapted to be in communication with a lubricant gallery in an engine block or cylinder head. An axial end of the housing includes skirt portions including openings, and one of the skirt portions includes a first recessed section indented from an outer lateral surface of the housing and extending axially between the annular groove and a respective one of the openings. A pin is mounted in the openings of the skirt portions and has a second recessed section indented from an outer lateral surface of the pin that extends to at least one of the ends of the pin. The second recessed section is in communication with the first recessed section, and a cam roller supported on the pin.

A four-stroke engine includes an oil tank, a crankshaft chamber, a distribution chamber, a rocker chamber, a combustion chamber, and a lubricating system. The oil tank is communicated with the crankshaft chamber through an oil supply channel. The four-stroke engine further comprises a cam and a transmission mechanism connected between the cam and a crankshaft of the crankshaft chamber in a matched manner. The cam is matched with a rocker of the rocker chamber and located above the combustion chamber.

A four-stroke engine includes an oil tank, a crankshaft chamber, a distribution chamber, a rocker chamber, a combustion chamber, and a lubricating system. The oil tank is communicated with the crankshaft chamber through an oil supply channel. The four-stroke engine further comprises a cam and a transmission mechanism connected between the cam and a crankshaft of the crankshaft chamber in a matched manner. The cam is matched with a rocker of the rocker chamber and located above the combustion chamber.

A camshaft is equipped with an inner shaft which is arranged rotatably inside a cylindrical outer shaft. Further, in the inner shaft, a plurality of pin holes extend along diametrical directions thereof, and are disposed at intervals along the axial direction of the inner shaft. The directions in which adjacent pin holes extend are arranged at angles obtained by dividing 360 degrees by the number of cylinders. The inner shaft and the inner cams are fixed in a state in which large diameter portions of pins, each of which is provided with a small diameter portion and a large diameter portion, are press-fitted through insertion holes of the inner cams and notches of the outer shaft, and are press-fitted into the pin holes.

Provided is a heat treatment method for a cam piece, and the cam piece has an insertion hole into which a cam shaft is inserted, a base portion configuring a base circle of a cam, and a nose portion configuring a cam ridge. The heat treatment method for the cam piece includes: a first step of using a jig formed into a shape having a cavity, the jig being inserted into the insertion hole such that the cavity is located between an inner circumferential surface of the nose portion of the cam piece and a central axis of the jig; and a second step of heating the cam piece from an outer circumferential surface side by high-frequency induction heating in a state in which the jig is inserted in the insertion hole of the cam piece.

In a valve drive train device for an internal combustion engine of motor vehicle, wherein at least one axially movably mounted cam element including at least one cam set with at least two cam parts and a shifting gate with at least two gate track for converting a rotary movement of the cam element into an axial shifting motion, at least one of the cam parts and the adjacent gate track are disposed in an at least partially axially overlapping relationship for reducing thereby the axial length and the mass of the cam element or permitting the use of a larger, highly durable, actuating mechanism.

A valve rocker arm assembly, a variable air distribution mechanism, and an engine are provided according to the present disclosure. The valve rocker arm assembly includes: an oil inlet hose; a rocker arm shaft, an oil drain channel, an oil return groove, and a first oil path being provided in the rocker arm shaft, the oil drain channel being communicated with the oil return groove by means of the first oil path; a first rocker arm and a second rocker arm rotatably connected onto the rocker arm shaft, a piston cavity, an oil inlet path, an oil drain path and a piston being provided on the second rocker arm; a one-way opening device provided in the oil inlet path and/or the oil inlet hose; and a control valve connected to the oil drain channel.

A valve rocker arm assembly, a variable air distribution mechanism, and an engine are provided according to the present disclosure. The valve rocker arm assembly includes: an oil inlet hose; a rocker arm shaft, an oil drain channel, an oil return groove, and a first oil path being provided in the rocker arm shaft, the oil drain channel being communicated with the oil return groove by means of the first oil path; a first rocker arm and a second rocker arm rotatably connected onto the rocker arm shaft, a piston cavity, an oil inlet path, an oil drain path and a piston being provided on the second rocker arm; a one-way opening device provided in the oil inlet path and/or the oil inlet hose; and a control valve connected to the oil drain channel.

A camshaft includes, as a cam that opens and closes an exhaust valve and an intake valve, a ball cam whose protrusion amount changes according to rotation of the camshaft, wherein the camshaft has a double structure consisting of an inner shaft and an outer shaft provided in a manner that the inner shaft is helically displaced with respect to the outer shaft around an axis of the camshaft according to a rotation speed of the camshaft, and the ball cam is accommodated movably in a guide groove provided in the inner shaft and protrudes from the outer shaft, and a protrusion amount of the ball cam from the outer shaft changes when the ball cam moves in the guide groove due to the helical displacement of the inner shaft with respect to the outer shaft.

A camshaft includes, as a cam that opens and closes an exhaust valve and an intake valve, a ball cam whose protrusion amount changes according to rotation of the camshaft, wherein the camshaft has a double structure consisting of an inner shaft and an outer shaft provided in a manner that the inner shaft is helically displaced with respect to the outer shaft around an axis of the camshaft according to a rotation speed of the camshaft, and the ball cam is accommodated movably in a guide groove provided in the inner shaft and protrudes from the outer shaft, and a protrusion amount of the ball cam from the outer shaft changes when the ball cam moves in the guide groove due to the helical displacement of the inner shaft with respect to the outer shaft.