| 摘要 |
PURPOSE:To prevent combustion from becoming unstable because of spitting of exhaust by aligning in the direction of a cam shaft intake ducts through which intake air is delivered to intake valves, and disposing control valves in those intake ducts each of which includes the center of their overall width in the direction of the cam shaft, the control valves being closed at least during operation at low speeds. CONSTITUTION:Three intake valves 20a-20c are disposed on one side of a center face betacontaining a cylinder center line alpha and parallel to a plurality of cam shafts 22, 24 and two exhaust valves 18 are disposed on the other side in such a way that both the intake and exhaust valves surround a spark plug 34 which faces near the center of a combustion chamber. Of the intake valves 20a-20c, those 20a, 20c located on both sides are brought closer to the center face beta than the center one 20b is. In this case, a plurality of intake ducts 40a-40c through which intake air is delivered to the intake valves 20a-20c are aligned in the direction of each cam shaft 22, 24. Control valves 44a, 44b which are closed at least during operation at low speeds are disposed in those respective intake ducts 40b, 40c each of which includes the center of their overall width in the direction of the cam shafts 22, 24. Combustion is therefore prevented from becoming unstable because of spitting of exhaust. |
