Variable valve timing mechanism for internal combustion engine

摘要

A variable valve timing mechanism of an internal combustion engine varies the rotational phase of a driven shaft (15) with respect to a drive shaft (172) to vary the timing of the valve. The mechanism includes a first rotary member (11; 52, 53; 62; 82, 84) for a rotation in synchronism with the drive shaft (172) and a second rotary member (12, 14; 51; 63, 64; 83) for a rotation in synchronism with the driven shaft (15). The second rotary member (12, 14; 51; 63, 64; 83) has a vane. The movement of the vane rotates the second rotary member (12, 14; 51; 63, 64; 83) with respect to the first rotary member (11; 52, 53; 62; 82, 84) to change the rotational phase of the driven shaft (15) with respect to the drive shaft (172). Hydraulic pressure is supplied to one of the first hydraulic chamber (101) and the second hydraulic chamber (102) to move the vane. A lock member (20; 70; 75) locks the second rotary member (12, 14; 51; 63, 64; 83) to the first rotary member (11; 52, 53; 62; 82, 84) to fix the rotational phase of the driven shaft (15) with respect to the drive shaft (172). The lock member (20; 70; 75) is held in a locked position when the engine is not running. The lock member (20; 70; 75) is moved to an unlocked position by the hydraulic pressure when the engine reaches a predetermined running condition. The hydraulic pressure maintains the lock member (20; 70; 75) in the unlocked position.