A method of joining a functional module comprises the steps of providing a frame structure that defines a bearing channel with at least one circumferentially closed bearing seat; providing at least two attachment parts; providing a hollow shaft that comprises at least one support section for the at least two attachment parts, wherein the attachment parts comprise a mounting seat that is adapted to a support section; feeding the attachment parts in the bearing channel in a first feeding direction; feeding the hollow shaft in the bearing channel in a second feeding direction, wherein the hollow shaft is inserted into the respective mounting seat of the at least two attachment parts; and, subsequent to the feeding of the attachment parts and the hollow shaft in the bearing channel, at least sectionally widening the hollow shaft for a torsionally rigid fixation of the at least two attachment parts with their mounting seats at the respective support section of the hollow shaft.

A valve timing adjusting device adjusts an opening/closing timing of a first valve driven by a rotation of a first camshaft and an opening/closing timing of a second valve driven by a rotation of a second camshaft. The valve timing adjusting device includes a first driving circuit controlling a first motor configured to generate a torque to shift a rotation phase of the first camshaft and a second driving circuit controlling a second motor configured to generate a torque to shift a rotation phase of the second camshaft. A first switching element of the first driving circuit operates at a switching frequency that is different from that of a second switching element of the second driving circuit.

Methods and systems are provided for a cam drive system of an engine. In one example, a front end of an engine includes an idler gear assembly including an idler gear and idler pulley, the idler gear in meshing engagement with a first end of a crankshaft and the idler pulley coupled to and sharing a rotational axis with the idler gear. The front end of the engine may further include first and second camshaft pulleys positioned vertically above the idler gear assembly and a cam drive belt contacting each of the first and second camshaft pulleys and the idler pulley.

In a lean-burn engine equipped with a turbocharger, a responsiveness of a super-charging pressure in a lean region is enhanced by control of a valve timing of an exhaust valve while a combustion state is restrained from varying. A variable valve mechanism that can change an opening timing of the exhaust valve while keeping a closing timing of the exhaust valve constant, is included in the lean-burn engine. When a target operation point is located in the lean region, and when an actual supercharging pressure is lower than a target supercharging pressure, supercharging pressure increasing control that advances the opening timing while keeping the closing timing constant is executed by operating the variable valve mechanism.

An exhaust valve includes a stem extending to a valve end. The valve end includes a pressure relief apparatus. An engine assembly includes a casing defining a cylinder bore, a combustion chamber and an exhaust passage. The combustion chamber is disposed between the exhaust passage and the cylinder bore. The engine assembly also includes a piston movable in the cylinder bore. The engine assembly further includes an exhaust valve movable between a first position blocking fluid communication through the exhaust passage and a second position allowing fluid communication through the exhaust passage. The exhaust valve includes a pressure relief apparatus configured to allow fluid communication through the exhaust valve from the cylinder bore to the exhaust passage when the exhaust valve is in the first position and a predetermined pressure threshold occurs in the cylinder bore between the exhaust valve and the piston.

A valve gear for an engine includes a camshaft including a cam, a rocker shaft, and a first rocker arm which swings when pressed by the cam. The valve gear includes a spring, which biases the first rocker arm and a second rocker arm which presses an intake valve or an exhaust valve, in a return direction. The valve gear includes a first pin hole of the first rocker arm, a second pin hole and a third pin hole of the second rocker arm, a first switch pin, a second switch pin, a third switch pin, and a switch which switches between a connected state and a non-connected state of the switch pins. The second rocker arm includes a stopper against which the first rocker arm abuts. When the first rocker arm abuts against the stopper, all of the pin holes are located on the same axis.

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.

A helical torsion valve spring assembly includes one or more helical torsion springs mounted within a frame and are held in a statically loaded state so that installation of a valve spring retainer can be easily performed. The entire helical torsion valve spring assembly is installed as a single part onto a cylinder head of an engine valvetrain. The helical torsion springs are mounted around a shaft to accurately locate the helical torsion springs so that the forces acting on the retainer and valve are precisely controlled. The assembly minimizes the size of the retainer, and applies only one bending mode to the helical torsion springs, which provides maximum utilization of the spring material and minimizes coil vibration. The assembly allows spring coils to be strategically packaged in the engine valvetrain to create space in critical areas.

An engine includes a cylinder head including a first oil path and a second oil path. The cylinder head includes a valve gear including a first support and a second support that support a rocker shaft. The first support includes, on its outer surface, a first constriction located at an inlet of a connection-switching third oil path and connected to the first oil path, and a second constriction connected to the second oil path. The second support includes, on its outer surface, a third constriction connected to the first oil path, and a fourth constriction located at an inlet of a lubrication fourth oil path and connected to the second oil path.

A continuously variable valve duration apparatus may include a camshaft, a plurality of first cams and second cams of which a cam key is formed respectively thereto, and of which relative phase angles with respect to the camshaft are variable, a plurality of rotation rings mounted to the camshaft and of which a ring key is formed thereto respectively, a plurality of inner brackets transmitting rotation of the camshaft to the cam keys of the first cams and the seconds respectively, a plurality of slider housings of which each inner bracket is rotatable inserted therein and of which a control slot is formed thereto respectively, an eccentric control shaft inserted into the control slots and a control portion selectively rotating the eccentric control shaft to move positions of the slider housing and change positions of the inner brackets.