| 摘要 |
A hydraulic tensioner includes a relief valve mechanism assembled in a plunger and held in fluid communication with a high-pressure oil chamber defined between a housing and the plunger which is slidably inserted in a plunger accommodation bore in the housing with a tip portion projecting therefrom. The relief valve mechanism is composed of a cup-shaped orifice member having an orifice formed in an outer circumferential surface thereof, and a relief valve assembled in the cup-shaped orifice member. The relief valve includes a cup-shaped sleeve slidably received in the orifice member, a spring urging the sleeve toward the high-pressure chamber, and a discharge port normally closed by the sleeve and adapted to be opened when the sleeve is displaced against the force of the spring. The thus constructed relief valve mechanism is small in size and capable of achieving downsizing of the hydraulic tensioner.
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