| 摘要 |
PURPOSE:To improve safety and a sealing property by forming a base bottom portion, an outer periphery crest portion, and an inner periphery crest portion, etc. on a spacer expander and supporting the bottom face and inner peripheral face of a side rail by means of the outer periphery crest portion and inner periphery crest portion respectively. CONSTITUTION:A spacer expander 10 is formed by integrally linking a central base bottom portion 11, an outer periphery crest portion 12, and an inner periphery crest portion 13 together. An outside slope 14 is formed on the inner periphery crest portion 13 while a barrel shaped outer peripheral face is formed on the outer periphery crest portion 12. Further, a number of slits 15 which extend in the radial direction alternately from inner and outer peripheries are formed while forming grooves 16 in the radial direction for allowing oil to escape in the spacer expander 10. The spacer expander 10 thus formed is installed in the ring groove 31 of a piston 30 after placing a side rail 20 on the top thereof. The inner peripheral edge and bottom face of the side rail 20 are placed on the outer slopes 14 of the inner peripheral crest portions 13 and the top of the outer peripheral crest portions 12 respectively. |
