| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems of increasing electric power consumption of an electric motor in a small operation angle control state, and deteriorating operational responsiveness of a variable mechanism in small to large operation angle control since the speed reduction ratio is constant in a conventional variable valve system. SOLUTION: This variable valve system has the variable mechanism for controlling so as to increase or decrease an operation angle of an intake valve by rotating a control shaft 32 according to an engine operation state and a driving mechanism 6 for controlling rotation of the control shaft. A screw transmitting means 37 is a speed reduction means of the driving mechanism, and is composed of a screw shaft 45 rotating by an electric motor 36 and having a male screw part 49 on an outer peripheral surface, a screw nut 46 for moving in the shaft direction of an output shaft according to rotation of the screw shaft by threadedly engaging with the male screw part, a link member 48 and a connecting arm 47 for connecting the screw nut and the control shaft. The speed reduction ratio of the screw transmitting means is set so as to become larger in the small operation angle control state than a large operation angle control state of the intake valve. COPYRIGHT: (C)2004,JPO |
