To provide a rigid and small-sized valve mechanism excellent in durability with simple constitution.
A piston 50 controlled to be advanced/retreated by oil pressure is incorporated into a first rocker arm (for low speed) 10 swingably supported by a rocker shaft 30, and driven by a first cam 41 to open an intake valve. An engaging projection 21 capable of engaging to the piston 50 is extendedly provided to a second rocker arm (for high speed) 20 provided adjacent to the first rocker arm 10 and driven by a cam 42 with lift amount larger than that of the first cam 41. An engaging part 51 selectively engaging to the engaging projection 21 is provided at a side portion of the piston 50. By incorporating the piston 50 into a boss part at an approximately central part of the first rocker arm 10, a direction of transfer of driving force is aligned in one direction.
SAITO SHINICHI
TOKIMATSU KAZUHISA
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