The number of advance chambers is larger than the number of retard chambers in an intake variable valve timing (VVT), whereas the number of retard chambers is larger than the number of advance chambers in an exhaust VVT. Accordingly, with limitation of an oil pressure that can be used by the VVTs, a pumping loss in a transition period in which a valve overlap amount is changed by advancing or retarding a valve timing can be reduced.

A valve timing adjustment device having a phase adjustment unit including an input rotator, a driving rotator that rotates in conjunction with a crankshaft, a driven rotator that rotates in conjunction with a camshaft that changes a relative rotation phase between the driving rotator and the driven rotator. A controller is configured to perform a startup phase control when operation of the internal combustion engine is started, the startup phase control including setting the relative rotation phase to a predetermined initial phase, and perform a startup preparation control during a period after the internal combustion engine is stopped and before the startup phase control is performed, the startup preparation control including changing the relative rotation phase.

A preparation control for suppressing fluctuation of an output torque of the engine at the time of executing switching operation from the whole cylinder operation to the partial cylinder operation is executed when having made a switching request from the whole cylinder operation to the partial cylinder operation. The target switching time executing the switching operation is calculated in accordance with the valve operation phase after the preparation time is completed. The cylinder deactivation mechanism is controlled such that the switching operation is executed at the target switching time. The target switching time is set in accordance with the valve operation phase at the timing in which the abnormal noises are not generated.

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 preparation control for suppressing fluctuation of an output torque of the engine at the time of executing switching operation from the whole cylinder operation to the partial cylinder operation is executed when having made a switching request from the whole cylinder operation to the partial cylinder operation, the valve operation phase is fixed to a predetermined phase before executing the switching operation, and the cylinder deactivation mechanism is controlled so as to execute the switching operation at a target switching time which is prefixed by corresponding to the predetermined phase. The target switching time is previously set to a timing at which abnormal noises are not generated, by corresponding to the valve operation phase fixed to the predetermined phase.

In a valve drive system, a rocker arm is swung by a cam. An exhaust valve abuts on a first end portion of the rocker arm. A second end portion of the rocker arm is supported by a lash adjuster. The lash adjuster includes a bottomed cylindrical body, a plunger that is contained in the body and that is biased in a direction in which the plunger abuts on the rocker arm, a pooling chamber that is formed in the plunger, a filling chamber that is formed by the plunger and a bottom surface of the body, and a valve body that blocks inflow of oil from the pooling chamber to the filling chamber when the plunger is put in the body. The oil supply to the pooling chamber is stopped when an exhaust throttle valve is closed for actuating an exhaust brake.

An engine includes a variable valve timing (VVT) mechanism that changes an opening timing or a closing timing of at least one of an intake valve or an exhaust valve in accordance with an operating region of the engine, and an oil jet that injects oil in a piston direction under a pressure of a first predetermined oil pressure or more. The control device of the engine controls supply of an oil pressure to the VVT mechanism in such a manner that an upper limit of an oil pressure used by the VVT mechanism is set to be lower than a first predetermined oil pressure and an operating speed of the VVT mechanism is high in a direction in which an overlap amount between open periods between an intake valve and an exhaust valve increases and is low in a direction in which the overlap amount decreases.

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.

A multifunctional engine brake, comprising an engine valve motion transformation mechanism, a slow seating mechanism (250), and a timing oil control mechanism. By axially moving a roller (235) on a roller shaft (231), the connections between the roller (235) and different cams (230, 2302) are switched, so as to implement the transformation between different engine valve motions. A roller axial driving mechanism (100) is disposed in the roller shaft (231), thereby achieving a simple and compact structure, a symmetrical and reliable force, and easy manufacturing and assembling. The timing oil control mechanism provides timing oil supply or discharge for the engine brake, thereby eliminating the randomness of the opening or closing of a conventional engine brake, avoiding slipping and impact of the roller during roller translation, and improving the reliability and durability of the brake and engine. The slow seating mechanism (250) effectively reduces and controls the seating speed of the valve, thereby eliminating the compact within the mechanism. The brake can be used for different types of variable valve motions, comprising valve motions generating 4-stroke braking, 2-stroke braking, or 1.5-stroke braking.

An oil supply control device for an engine includes: a hydraulic controller which outputs a control value to an adjusting device to cause a detected hydraulic pressure detected by a hydraulic pressure sensor to coincide with a predetermined hydraulic pressure value; a determination portion which compares an output control value output from the hydraulic controller to the adjusting device when the detected hydraulic pressure coincides with the predetermined hydraulic pressure value and a control value stored in a memory, to determine whether or not a difference between the output control value and the stored control value lies within a predetermined allowable range; and a device controller which allows activation of a hydraulic actuating device when an oil temperature is not lower than a first temperature in a case where the difference lies within the allowable range, inhibits activation of the hydraulic actuating device when the oil temperature is lower than a second temperature higher than the first temperature in a case where the difference does not lie within the allowable range, and allows activation of the hydraulic actuating device when the oil temperature is not lower than the second temperature in a case where the difference does not lie within the allowable range.