| 摘要 |
PROBLEM TO BE SOLVED: To provide an auto tensioner which retains a screw rod while being screwed into a nut member and which does not give an excessive tension to a chain when vibration of the chain becomes large transitionally. SOLUTION: An auto tensioner 1 includes: a nut member 10 having an internal thread 17 on its inside circumference; a screw rod 11 having an external thread 18, which is in threaded engagement with the internal thread 17, on its outside circumference; and a return spring 12, which biases the screw rod 11. The external screw 18 and the internal screw 17 are formed into a saw tooth shape such that a flank angleθ1 of the pressure flank 20 is larger than a flank angleθ2 of a clearance flank 21. In this auto tensioner, the size of a lead angleαof the external thread 18 and the internal thread 17 is set satisfy tanα<μ×secθ2 to static friction coefficientμbetween the clearance flanks 21, 21 and the flank angleθ2 of the clearance flank 21. COPYRIGHT: (C)2011,JPO&INPIT
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