| 摘要 |
PURPOSE:To enable the area of a surface to which heat of a piston is transmitted to be ensured by forming a recess in one of contact surfaces of a piston ring and a crank chamber side wall of a piston ring groove and a wedge type of the groove sides having an opening diverging toward the crank chamber. CONSTITUTION:At least one of contact surfaces of a piston ring 21 and a crank chamber side wall 22a of a piston ring groove 22 is formed with a recess 29. And the sides of the piston ring groove 22 formed like a wedge having an opening diverging toward the crank chamber side. Thus, the area of piston ring surface contacting the side walls of the groove is ensured so that heat flow bundle flowing from a piston 8 to a cylinder through the piston ring 21 is sufficiently ensured to cool sufficiently the piston while the function of interrupting combustion gas can be improved. |
