| 摘要 |
PROBLEM TO BE SOLVED: To satisfy both of ensuring a sufficient sealing performance of a sealing portion of a ball bearing for supporting a throttle shaft in freely rotatable manner and of reducing a full frictional force (rotary resistance) acting on the sealing portion at the time of running. SOLUTION: Among an external diameter surface of an end of an inner race 10b for making up the ball bearing, a portion for sliding a point edge of a seal lip 17a that makes up a seal ring 12a is formed into a taper surface 21. Then, an angleθof inclination of the taper surface 21 is made as moderate as 2 to 10 degrees. Thereby, the problem is solved by preventing abutting pressure of the seal lip 17a against the taper surface 21 from becoming excessively large or excessively small even when the inner race 10b is displaced in an axial direction together with the throttle shaft or positive pressure or negative pressure is applied from the outside to the seal ring 12a at the time of running. COPYRIGHT: (C)2005,JPO&NCIPI
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