| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable valve gear capable of improving control accuracy by inhibiting strike noise and sudden load change during axial movement of a ball nut while securing failsafe of a drive mechanism. SOLUTION: This variable valve gear variably controls valve lift of an intake valve by rotating a ball screw shaft 45 by an electric motor 36 and controlling rotation of a control shaft 32 by linearly moving a ball nut 46 in an axial direction. The ball nut is maintained in a middle movement position in the axial direction between the maximum lift movement position and the minimum lift movement position regulated by stopper mechanism by energizing force of a first coil spring 61 and resistance force of a second coil spring 64 during stop of the electric motor and the ball nut is always energized from the axial direction by spring force of each coil spring. COPYRIGHT: (C)2008,JPO&INPIT
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