| 摘要 |
PURPOSE:To reduce the length required for arranging a plurality of cylinders, by shaping the cylinders to have a cross section in the form of an elongated circle and piston rings also in the form of an elongated circle, and providing an expansion ring along the straight portion of each piston ring. CONSTITUTION:Cylinders 2 having a cross section in the form of an elongated circle are formed in a cylinder block 1, and a piston 3 also having a cross section in the form of an elongated circle is fitted in each cylinder 2. Piston rings 4 shaped in the form of an elongated circle are fitted to each piston 3, and an expansion ring 5 consisting of a corrugated bimetal is inserted between the back surface of the piston ring 4 and a piston-ring groove 6 along the straight portion of the piston ring 4 so as to impart tension to the straight portion of the piston ring 4 where the tension is otherwise low. With such an arrangement, it is enabled to improve the sealing performance of the piston rings 4. |
