Variable valve system

#The present invention relates to a variable valve system for an internal combustion engine.

#More specifically, the present invention relates to a variable valve system which is provided with a plurality of variable gears for controlling valve lift characteristic and the like of an engine valve such as an intake valve and an exhaust valve.

#U.S. Pat. No. 6,123,053 (equivalent of Japanese Patent Unexamined Publication No. 2000-38910 which is applied by the applicant of the present invention) discloses a variable valve system (referred to as “VARIABLE VALVE ACTUATION APPARATUS”). The variable valve system according to the above related art is applied to a movable valve gear which is provided with two intake valves for one cylinder. The variable valve system has a first variable gear and a second variable gear, each for variably controlling a valve lift characteristic of one of the respective two intake valves, namely, a first intake valve and a second intake valve, in such a manner that a lift of the first intake valve becomes different from a lift of the second intake valve, to thereby achieve engine performance in accordance with engine operating condition.

#FIG. 1 is an essential side view of a variable valve system, according to a first preferred embodiment of the present invention;

#FIG. 2 shows an operation of a first variable gear 1, according to the first preferred embodiment, in which,

#FIG. 2A is a cross section II—II in FIG. 1 showing a closed valve operation when the first variable gear 1 is controlled at a maximum lift, and

#As is seen in FIG. 1, there is provided a variable valve system, according to a first preferred embodiment of the present invention.

#In FIG. 1, the variable valve system is applied to a movable valve gear which is provided with two intake valves for one cylinder, namely, a first intake valve 12A and a second intake valve 12B. The first intake valve 12A and the second intake valve 12B are slidably mounted, by way of a valve guide (not shown), to a cylinder head 11. The variable valve system is provided with a first variable gear 1 and a second variable gear 2. In accordance with engine operating condition, the first variable gear 1 variably controls lift of the first intake valve 12A continuously, while the second variable gear 2 variably controls lift of the second intake valve 12B stepwise. The first variable gear 1 and the second variable gear 2 are allowed to operate independently of each other.

#Hereinafter, there is described a constitution of the first variable gear 1.