| 摘要 |
PURPOSE:To improve the combustion efficiency in a main combustion chamber by forming the skewish area of a cylinder wider on the non-opposed side than on the bank opposed side. CONSTITUTION:A combustion chamber 21 is formed by forming a recessed part at the position eccentric from the center of a cylinder bore, on the top surface of a piston 5, and a skewish area 22 on the opposed side to a bank is formed relatively narrow and a skewish area 23 on the not-opposed side to the bank is formed relatively wide. When the piston 5 rises closely to a top dead center, the skewish flow which is directed towards the main combustion chamber 21 from the skewish areas 22 and 23 is larger on the skewish area 23 side. Therefore, fuel is efficiently sent to the vicinity of a spark plug 11, and the stratification around the spark plug 11 is performed effectively, and the combustibility in the main combustion chamber 21 is improved. Further, since the main combustion chamber 21 is set eccentric to an intake port 7 side, an exhaust valve 10 is prevented from forming a heating point, and knocking can be effectively suppressed.
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