| 摘要 |
<P>PROBLEM TO BE SOLVED: To increase a rate of balls which are detained in ball detention positions and reduce aggravation of unbalance caused by balls which are not detained in the ball detention positions. <P>SOLUTION: A bottom wall inner surface (103) is inclined upward from an inner peripheral wall (11) toward an outer peripheral wall (12). A plurality of ball detention portions (105) are formed on the outer peripheral edge portion of the bottom wall inner surface (103) so as to be arranged at predetermined intervals in the circumferential direction of a race member (10). When the rotation speed of a rotator is lower than a first rotation speed causing primary resonance of a rotary system, each ball detention portion (105) allows a ball (BB) to be detained in the ball detention portion (105) by gravity or centrifugal force acting on the ball (BB). When the rotation speed of the rotator is higher than the first rotation speed, the ball detention portion (105) allows the ball (BB) to be separated from the ball detention portion (105) by centrifugal force acting on the ball (BB). An outer peripheral wall inner surface (102) is inclined upward from the lower end of the outer peripheral wall inner surface (102) toward the upper end thereof more steeply than the bottom wall inner surface (103). <P>COPYRIGHT: (C)2013,JPO&INPIT |
