| 摘要 |
PROBLEM TO BE SOLVED: To provide an oil seal having a bidirectional screw specification constituted of a combination of a normal direction screw and a reverse direction screw and having a ship's bottom-shaped screw, in which a sealing performance with the screw can be improved.SOLUTION: A normal direction screw and a reverse direction screw realizing a pumping action against sealed fluid are arranged side-by-side on a circumference at a side surface of a seal lip sliding part facing atmospheric atmosphere. Each of the normal direction screw and the reverse direction screw is constituted in such a way that a parallel thread starting from a lip extremity end and a ship's bottom-shaped screw continuous to the parallel thread are made to be continuous as one thread. The ship's bottom-shaped screw at the normal direction screw is made in such a way that an inclination angle of a slant surface at a rear side in a normal rotating direction of its axis is formed to be larger than an inclination angle of a slant surface at a front side in the normal rotating direction of its axis. The ship's bottom-shaped screw at the reverse direction screw is made in such a way that an inclination angle of a slant surface at a front side in a normal rotating direction of its axis is formed to be larger than an inclination angle of a slant surface at a rear side in the normal rotating direction of its axis. |
