| 摘要 |
PROBLEM TO BE SOLVED: To improve following performance during high-frequency oscillation or high amplitude of a belt in a hydraulic automatic tensioner in which a sleeve is fitted into a cylinder. SOLUTION: A steel valve sleeve 14 is fitted into an aluminum alloy cylinder 11. A plunger 16 at the lower end part of a rod 15 is incorporated into the valve sleeve 14. Thus, the inside of the valve sleeve 14 is partitioned into a pressure chamber 26 and a reservoir chamber 27. A return spring 22 for elongating the cylinder 11 and the rod 15 is provided to the outside of the cylinder 11. A passage 33 for making the pressure chamber 26 and the reservoir chamber 27 communicate with each other is provided between the fitting faces of the cylinder 11 and the valve sleeve 14. A check valve 28 for opening/closing the passage 33 is provided to the lower part of the valve sleeve 14. A sub-reservoir chamber 34 is provided below the check valve 28. An operating fluid is made to flow into the pressure chamber 26 from both of the reservoir chamber 27 and the sub-reservoir chamber 34 when the volume inside the pressure chamber 26 is steeply increased. Consequently, the cylinder 11 and the rod 15 can be smoothly expanded or contracted even when the high-frequency oscillation or the large amplitude of the belt occurs. COPYRIGHT: (C)2007,JPO&INPIT
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