To provide a simple-structured chain guide assembly frame capable of reliably maintaining a correct positional relationship between a driven sprocket and a sprocket holding portion without the possibility of driven sprocket detachment. The chain guide assembly frame includes a main body having a fixed-guide-side sprocket holding portion and a pivoting-guide-side sprocket holding portion. The fixed-guide-side sprocket holding portion includes a first fixed-guide-side support portion that supports a driven sprocket at a first contact point, and a second fixed-guide-side support portion that supports the driven sprocket at a second contact point located more outside than the first contact point. When the driven sprocket is in an erected state in which the driven sprocket is supported at the first contact point and second contact point, the vector of gravity acting on the gravity center of the driven sprocket points between the first contact point and second contact point.

Provided is a timing chain cover that allows suppressing vibration transmission. A timing chain cover of the present disclosure houses a timing chain transmitting a rotative force of a crankshaft to a camshaft in one end side of an internal combustion engine. The timing chain cover includes a chain cover main body and a damping resin layer formed on an abutment surface of the chain cover main body. The abutment surface abuts on an internal combustion engine main body. The damping resin layer contains a heat resistant resin and a damping filler. The damping filler converts a vibration energy into a heat energy.

An endless band drive system having a variable center distance between the drive pulley and the driven pulley also has a rotatable control shaft and an endless band guide, where the guide is positioned by the rotatable control shaft for maintaining a slackless endless band with change of pulley center distance. Rotation of the control shaft pivots the endless band guide thereby maintaining a slackless endless band with change of the pulley center distance. Preferably, the rotatable control shaft also provides means for adjusting the center distance between the drive pulley and the driven pulley. The present invention provides a slackless endless band system for a variable compression ratio engine having a variable center distance between the drive pulley mounted on the crankshaft and the driven pulley mounted on the camshaft. The system provides slackless operation of the endless band at two or more compression ratio values.

A product for applying tension is disclosed. The product may include a block with a first bore opening into to the block. A body may be provided having a second bore substantially larger in diameter than the first bore. The body may be positioned against the block so that the first bore is open to the second bore. The body may have a passage for providing fluid to a pressure chamber from the second bore. The passage may be arranged to open to the second bore and form a tangent to the second bore. Fluid may flow from the first bore to the pressure chamber through the second bore and the passage substantially unimpeded. Fluid flow is impeded from the passage to the first bore as a result of the configuration of the first bore, second bore and passage.

A case that houses a chain includes a first cover member fixed to a cylinder block and a cylinder head, and a second cover member arranged on the opposite side of the cylinder block and the cylinder head from the first cover member. In an intermediate part, which is a part of a confronting wall of the first cover member between the first flange and the second flange, a cover-side rib is provided, having a height so that a distal end of the cover-side rib is not in contact with the cylinder block.

There is provided a lubricating structure for a power transmission mechanism in which a crankshaft is coupled to a piston disposed in a cylinder bore and in which power is transmitted from the crankshaft to a camshaft. The lubricating structure includes: an idler gear that is configured to transmit power from the crankshaft to the camshaft; and an idler gear shaft that supports the idler gear via a bearing. One end portion of the idler gear shaft protrudes into the cylinder bore, and an oil passage configured to guide oil from the cylinder bore to the bearing is formed in the idler gear shaft.

An internal combustion engine is provided with a DOHC-type valve train in a cylinder head. The valve train includes an intake side camshaft with an intake side driven gear, and an exhaust side camshaft with an exhaust side driven gear. The cylinder head supports therein a spindle with an idle gear with an idle chain sprocket fixed thereto. The idle gear is in meshing engagement with both the intake and exhaust side driven gears. Rotary power of a crankshaft is transmitted via a cam chain to the idle gear to rotate both the intake and exhaust side camshafts. These camshafts are supported by bearings of a bearing wall and a camshaft holder. These bearings and camshaft holder are located, for compact arrangement, at a position axially coinciding or overlapping with the idle chain sprocket.

An engine variable valve train includes a cam changeover mechanism for axially shifting a cylindrical cam carrier fitted on and around a camshaft for changing over cam lobes on the cam carrier to cause one of the cam lobes to selectively act on an engine valve for engine operation. The cam changeover mechanism includes changeover pins adapted to be advanced and retracted for engagement with or disengagement from a lead groove formed around the cam carrier, and with a changeover driving shaft constituting a linear motion cam mechanism for causing the changeover pins to selectively advance to engage with the lead groove. The cam carrier, while rotating with the cam shaft, is axially shifted by the action of the lead groove having the changeover pins selectively engaged therewith, so that the cam lobes are changed over and one of the cam lobe is made to act on the engine valve.

A chain cover is configured to cover a timing chain that transmits rotation of a crankshaft of an internal combustion engine to a camshaft. The chain cover includes a crankshaft-side opening forming portion that defines a crankshaft-side opening into which the crankshaft is inserted, and a general portion that is a section different from the crankshaft-side opening forming portion. The crankshaft-side opening forming portion is made of a first material. The general portion is made of a second material. The first material and the second material are different from each other.

An engine including a motorized throttle valve that can implement mutually neighboring disposition of a throttle body and a cylinder head and can implement a good opening and closing responsibility thereof. A swelling portion is formed on a side wall of a valve chamber in such a manner so as to bite between those of throttle bodies which neighbor with each other in order to accept a protrusion of part of a valve system in a radial direction of first and second camshafts. An electric motor is disposed at one side of the group of the throttle bodies. A speed reduction mechanism, for transmitting output power of the electric motor to a valve shaft, is disposed between those throttle bodies, which neighbor with each other at a different location in the group of the throttle bodies, in a neighboring relationship with the valve chamber.