Abstract: A control device has two modes as control modes of an electric power supply to an electromagnetic solenoid, which are used when a first determining unit determines that a difference between a sensed value of a phase and a target value of the phase exceeds a permissible range. One of the modes is a special mode that is used when a second determining unit determines that the sensed value of the phase reaches a threshold value. Another one of the modes is a normal mode that is used when the second determining unit determines that the sensed value of the phase does not reach the threshold value. In the special mode, the control device controls supply of the electric power to the electromagnetic solenoid in such a manner that an opening degree of an advancing port is larger than the opening degree of the advancing port in the normal mode.

Abstract: In a variable valve actuation apparatus for an internal combustion engine, a rotor of a variable valve timing mechanism is fixed to one end of a camshaft by a plurality of bolts. An oil control valve configured to control hydraulic pressure that acts on the rotor is fixed to the rotor by one or some of the plurality of bolts. For this reason, by releasing fastening of the bolt that fixes the oil control valve to the rotor among the plurality of bolts that fix the rotor to the one end of the camshaft, the oil control valve is allowed to be removed from the rotor while the rotor is fixed to the camshaft. Therefore, it is not required to perform positioning for fixing the rotor to the camshaft at the time of replacement of the oil control valve.

Abstract: A control device has two modes as control modes of an electric power supply to an electromagnetic solenoid, which are used when a first determining unit determines that a difference between a sensed value of a phase and a target value of the phase exceeds a permissible range. One of the modes is a special mode that is used when a second determining unit determines that the sensed value of the phase reaches a threshold value. Another one of the modes is a normal mode that is used when the second determining unit determines that the sensed value of the phase does not reach the threshold value. In the special mode, the control device controls supply of the electric power to the electromagnetic solenoid in such a manner that an opening degree of an advancing port is larger than the opening degree of the advancing port in the normal mode.

Abstract: In a variable valve actuation apparatus for an internal combustion engine, a rotor of a variable valve timing mechanism is fixed to one end of a camshaft by a plurality of bolts. An oil control valve configured to control hydraulic pressure that acts on the rotor is fixed to the rotor by one or some of the plurality of bolts. For this reason, by releasing fastening of the bolt that fixes the oil control valve to the rotor among the plurality of bolts that fix the rotor to the one end of the camshaft, the oil control valve is allowed to be removed from the rotor while the rotor is fixed to the camshaft. Therefore, it is not required to perform positioning for fixing the rotor to the camshaft at the time of replacement of the oil control valve.

Abstract: A variable valve timing device that allows a valve timing of an engine valve to be varied by relatively rotating a vane rotor and a housing. The variable valve timing includes a lock mechanism that releases the locking in accordance with the application of a lock releasing oil pressure. A crank angle CCA at which the application of the lock releasing oil pressure is instructed can be varied in accordance with an engine speed NE so that the lock releasing oil pressure rises at a crank angle in which cam torque is suitable for lock releasing.

Abstract: In a variable valve timing device, which varies the rotational phase of a camshaft through the relative rotation of a vane rotor and a housing and is provided with a lock mechanism that releases the lock thereof in response to the application of lock-release hydraulic pressure, the crank angle CCA at which the application of lock-release hydraulic pressure is commanded is set variably in accordance with the pressure of the oil supplied for the application so that the lock-release hydraulic pressure rises at a crank angle at which the state of the cam torque becomes suitable for lock-release without relying on changes of time needed for the lock-release hydraulic pressure to raise resulting from oil temperature.

Abstract: A variable valve timing apparatus includes: a variable valve timing mechanism that changes a valve timing and locks the valve timing at a most retarded timing; an oil control valve that controls a mode in which hydraulic fluid is supplied to the variable valve timing mechanism; and a controller that varies a duty ratio of the oil control valve within a set range that includes an advance active band, a retard active band, a holding range, an advance release range and a retard release range. In the advance release range, a varying speed of the valve timing is higher than the holding range and a housing rotor is disengaged from a vane rotor. When an engine operating state is a release request state, the controller sets the duty ratio of the oil control valve within the advance release range.

Abstract: In a hydraulic variable valve timing mechanism including a lock pin that locks a vane rotor and a housing against relative rotation in the most retarding phase, a specified angle ? is set so that release of the lock pin is started at a time when positive cam torque acts on the vane rotor. When the crank angle reaches the specified angle ?, supply of hydraulic pressure to the advancing oil chamber is started to release the lock pin from the engagement with the lock hole, thereby enabling a reliable release of the lock pin prior to start of change of valve timing.

Abstract: In a variable valve timing device, which varies the rotational phase of a camshaft through the relative rotation of a vane rotor and a housing and is provided with a lock mechanism that releases the lock thereof in response to the application of lock-release hydraulic pressure, the crank angle CCA at which the application of lock-release hydraulic pressure is commanded is set variably in accordance with the pressure of the oil supplied for the application so that the lock-release hydraulic pressure rises at a crank angle at which the state of the cam torque becomes suitable for lock-release without relying on changes of time needed for the lock-release hydraulic pressure to raise resulting from oil temperature.

Abstract: A variable valve timing device that allows a valve timing of an engine valve to be varied by relatively rotating a vane rotor and a housing. The variable valve timing includes a lock mechanism that releases the locking in accordance with the application of a lock releasing oil pressure. A crank angle CCA at which the application of the lock releasing oil pressure is instructed can be varied in accordance with an engine speed NE so that the lock releasing oil pressure rises at a crank angle in which cam torque is suitable for lock releasing.

Abstract: In a hydraulic variable valve timing mechanism including a lock pin that locks a vane rotor and a housing against relative rotation in the most retarding phase, a specified angle ? is set so that release of the lock pin is started at a time when positive cam torque acts on the vane rotor. When the crank angle reaches the specified angle ?, supply of hydraulic pressure to the advancing oil chamber is started to release the lock pin from the engagement with the lock hole, thereby enabling a reliable release of the lock pin prior to start of change of valve timing.

Abstract: A variable valve timing mechanism changes a relative rotation phase of a camshaft to a target phase based on hydraulic pressure supplied to an advance and a retard sides pressure chambers. A lock mechanism is placed in a locked state in which the relative rotation phase is locked at a maximum retard phase when the hydraulic pressure in the advance and the retard side pressure chambers is low, and that is placed in an unlocked state in which the locked state is released when the hydraulic pressure becomes high. Hydraulic pressure regulations in a first mode that changes the relative rotation phase to a side toward the maximum retard phase and in a second mode that changes the relative rotation phase to a side away from the maximum retard phase are executed in combination during a period from when an operating switch is turned off until a crankshaft stops rotating.

Abstract: A variable valve timing apparatus includes: a variable valve timing mechanism that changes a valve timing and locks the valve timing at a most retarded timing; an oil control valve that controls a mode in which hydraulic fluid is supplied to the variable valve timing mechanism; and a controller that varies a duty ratio of the oil control valve within a set range that includes an advance active band, a retard active band, a holding range, an advance release range and a retard release range. In the advance release range, a varying speed of the valve timing is higher than the holding range and a housing rotor is disengaged from a vane rotor. When an engine operating state is a release request state, the controller sets the duty ratio of the oil control valve within the advance release range.