| 摘要 |
<p>A tensioner in which sticking between a rotation member and a drive member when the tensioner is in a fully retracted state is prevented by using a simple mechanism, thereby ensuring reduced man-hour for control in assembling the tensioner and enabling the tensioner to function when it is abnormally operated. A pair of shaft members (3, 4) is threaded to each other by thread sections (8, 9), and one (3) of the shaft members (3, 4) is rotatingly urged by a spring (5) and driven by rotational force transmitted from the one shaft member (3) with the other shaft member (4) restrained from rotating. A contact section (20) is formed at that portion of the shaft members (3,4) which is other than that of the thread sections (8, 9), and the contact section (20) come into contact with the other shaft member (4) when it is moved in the direction opposite the drive direction. The contact section (20) is set to satisfy the expression of R1/R2 < -tan(µ2 - a)/µ1, where R1 is a contact radius caused by contact, R2 the effective diameter of the thread sections (8, 9), µ1 the coefficient of friction of the contact section (20), µ2 the coefficient of friction of the thread sections (8, 9), and a the lead angle of the thread faces of the thread sections (8,9).</p> |
