| 摘要 |
PURPOSE:To aim at the promotion of lightweightness and improvements in a sliding characteristic and abrasion resistance, by forming a shaft part and an eccentric rotor part both with aluminum or its alloy, while forming an anodic oxide film, made up of anodic treatment, on the rotor eccentric part surface. CONSTITUTION:Oxide film layers A of a film made up of anodic treatment, a film made up of taprum process, etc., are formed on the surface of an eccentric rotor part 5. It is a matter of course that the oxided film layers A may be formed on not only the eccentric rotor part but also on a shaft part 4a. With this constitution, a sliding characteristic and abrasion resistance with a piston is well improvable. In addition, since the shaft part 4a and the eccentric rotor part 5 use aluminum or its alloy as material, both parts 4a and 5 are made to be lightweight, whereby high speed output is securable and, what is more, vibro- absorbability and sound absorbability as a property inherent in aluminum are securable so that vibration and noise both are reducible. |
