| 摘要 |
PURPOSE:To prevent a mechanism unnecessary upon rest of one of two valves from being an engine load by providing a stopping mechanism for releasing one of two camshafts from a rotary drive system and interrupting the motion thereof in an engine fitted with two or more intake and exhaust valves per cylinder. CONSTITUTION:Two intake ports 4a and 4b are formed from the left side of the center line P of cylinder arrangement toward the inside of a cylinder 3, and ports 5a and 5b at the side of the cylinder 3 are positioned symmetrically right and left about the center line P. Also, the first intake port 4a is made a swirl port and the second intake port 4b straight port. Furthermore, for each cylinder 3, two exhaust ports 6a and 6b are formed in inverse relation to the intake ports 4a and 4b, and intake valves 8a and 8b for opening and closing the right and left intake (exhaust) ports 4a and 4b are opened and closed with the left camshafts 10a and 10b. One of the camshafts 10b is made releasable from a rotational drive system via a stop mechanism fitted to the end thereof, when an engine is operating under a low load.
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