The present disclosure provides a valve timing adjustment apparatus for an internal combustion engine. The apparatus includes an anti-rotation mechanism for inhibiting a position change between a rotor and a housing by inhibiting or preventing relative rotation of the rotor to the housing. The anti-rotation mechanism includes: a plurality of locking grooves formed on the ratchet plate with different depths and connected to each other; and a locking pin member having an outer pin elastically disposed in a fitting hole formed in one of the vanes, and an inner pin elastically disposed inside the outer pin. In particular, the inner pin locks the rotor to the housing when the outer pin and the inner pin are sequentially fitted in the locking grooves by torque from the camshaft.

A driving rotor is configured to rotate about a rotational shaft center in conjunction with a crankshaft. A driven rotor is configured to rotate about the rotational shaft center in conjunction with the camshaft. A deceleration mechanism is configured to change a relative rotational phase between the driving rotor and the driven rotor by using a driving force of an electric motor. The deceleration mechanism includes an internal gear portion, which includes an internal tooth extending radially inward, and an external gear portion, which includes an external tooth extending radially outward and engaging with the internal tooth. A linear expansion coefficient of the external gear portion is greater than a linear expansion coefficient of the internal gear portion.

A depressurization device is mounted on a camshaft that includes an exhaust cam operable to push an exhaust rocker arm. The depressurization device includes a base disc mounted on the camshaft and adjacent to the exhaust cam, a counterweight swing arm coupled to the base disc, an elastic element arranged between the base disc and the counterweight swing arm, a depressurization cam element coupled to the exhaust cam and drivable by the counterweight swing arm, and an axle bar extending through the base disc and the counterweight swing arm. The depressurization cam element includes a driving section, a depressurization cam section, and a rotary shaft section. The depressurization cam element is drivable by the counterweight swing arm to rotate by an angle. The depressurization cam section includes an arc portion and first and second cut-off portions arranged at a side opposite to the arc portion.

A flange portion in an annular shape extending toward the axis is formed at an end portion of a reinforcement ring on the cam side, and the flange portion is positioned between a seal lip and a back pressure lip of an elastic body part in the axis direction. An interval in the axis direction between an inner-periphery end portion of the flange portion and a root portion of the back pressure lip in the elastic body part is larger than an interval in the axis direction between the root portion of the back pressure lip and a tip end portion of the back pressure lip, and the outline of a cylinder-side corner portion of the inner-periphery end portion of the flange portion on the cylinder side is a curved line in a cross section.

A variable valve actuation mechanism is provided for an internal combustion engine including at least one valve for control of gas admission to a cylinder of the engine and/or gas exhaust from the cylinder. The mechanism includes two concentrically arranged camshafts, a cam set comprising two cams, each fixed to a respective of the camshafts, whereby the camshafts are arranged to be turned in relation to each other, so as to change the combined profile of the cams, and a cam follower adapted to follow the combined profile of the cams and to actuate at least one of the at least one valve in dependence on the combined profile of the cams, wherein the cam follower includes two rollers, each roller being adapted to follow a respective one of the cams.

A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

A variable drive for an internal combustion engine with a first gas exchange valve, in particular outlet valve, and a second gas exchange valve, in particular outlet valve. The variable valve drive has a sliding cam system. The sliding cam system has an axially displaceable cam carrier which, for the first gas exchange valve, has only two cams, namely a first cam and a second cam offset axially with respect thereto, and, for the second gas exchange valve, has only two cams, namely a third cam and a fourth cam offset axially with respect thereto. The first cam, the second cam, the third cam and the fourth cam differ from a zero lift cam. The first cam and the third cam are identical in design. The second cam and the fourth cam differ in design.

A method of operating a cam shaft phaser including a stator including a radially inwardly extending protrusion, a rotor including a radially outwardly extending protrusion and a slot in the radially outwardly extending protrusion, a cover non-rotatably connected to the stator, a chamber circumferentially bounded by the radially inwardly extending protrusion and the radially outwardly extending protrusion, a pin disposed in the slot, and a first channel connecting the chamber with the slot. The method comprises: blocking, with the locking pin, rotation of the rotor with respect to the stator; applying pulse width modulation voltage to a control valve as a non-rectangular wave form; flowing fluid from the control valve to the chamber; flowing the fluid through the first channel to the slot; axially displacing the locking pin with the fluid; disengaging the locking pin from the cover; and rotating the rotor with respect to the stator.

A method for predicting a future camshaft position includes approximating a regulating circuit or a part of a regulating circuit that includes at least an adjusting device by a transfer function, and ascertaining a future camshaft position on the basis of the transfer function. An engine control unit is also provided.

A driving rotor is rotational about a rotational shaft center in conjunction with a crankshaft. A driven rotor is rotational about the rotational shaft center in conjunction with the camshaft. A deceleration mechanism is configured to change a relative rotational phase between the driving rotor and the driven rotor by using a driving force of an electric motor. The deceleration mechanism includes an internal gear portion, which includes an internal tooth formed inward in a radial direction, and an external gear portion, which includes an external tooth formed outward in a radial direction and engages with the internal tooth. A linear expansion coefficient of the external gear portion is larger than a linear expansion coefficient of the internal gear portion.