| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic automatic tensioner capable of allowing a non-return valve to be easily opened by suppressing suction of a check ball to a ball seat. SOLUTION: The hydraulic automatic tensioner 9 comprises a low pressure oil chamber and a high pressure oil chamber, a communication hole 51 for allowing oil to flow from the low pressure oil chamber to the high pressure oil chamber, and a non-return valve 61 for preventing the oil from flowing from the high pressure oil chamber to the low pressure oil chamber through the communication hole 51. The non-return valve 61 includes a ball seat 62 provided on an edge of an opening part of the communication hole 51 on the high pressure oil chamber side, and a check ball 63 which is abutted on the ball seat 62 when the valve is closed to close the opening part. The ball seat 62 is formed oval in sectional view at the opening part, and the check ball 63 is formed in a truly spherical shape, and formed in a truly spherical shape in sectional view at the opening part when the valve is closed. A plurality of very small gaps G of the gap width w=1-5μm are intermittently formed long in the circumferential direction of the opening part between the seat and the ball when the valve is closed. COPYRIGHT: (C)2009,JPO&INPIT
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