| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic auto tensioner easily compressible at a normal temperature. SOLUTION: The upper opening of an oil chamber 13 formed in a cylinder 11 is sealed by an oil seal 14. An outwardly projecting property is imparted to a rod 16 allowing the oil seal 14 to slidably pass therethrough by a return spring 19. A plunger 24 slidable along the inner diameter surface of the oil chamber 13 is installed at the end part positioned inside the oil chamber 13 of the rod 16. A passage 28 allowing a pressure chamber 26 to communicate with a reservoir chamber 27 is formed in the plunger 24. The passage 28 is closed by a valve plate 29 when the pressure in the pressure chamber 26 rises. A gap adjusting layer 30 with a high coefficient of linear expansion is formed on the outer diameter surface of the plunger 24. The amount of a leak gap formed between the oil chamber 13 and the plunger 24 is adjusted by the gap adjusting layer 30 according to a variation in temperatures. A variation in a hydraulic damper force due to a variation in oil viscosity is suppressed to facilitate the compressing operation of the auto tensioner at normal temperatures. Consequently, a belt can be easily replaced. COPYRIGHT: (C)2008,JPO&INPIT
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