| 摘要 |
PROBLEM TO BE SOLVED: To obtain sufficient cooling efficiency by jetting a cooling air within a specified angle range toward a specified portion or a plurality of specified portions of a gap communicating a plurality of ball bearings with each other between an outside fixing body and an inside rotating body. SOLUTION: A rotating face of an inside rotating body 1 is determined for a reference and a cooling air is jetted to one portion or a plurality of portions of a gap 3 located between an outside fixing body 2 and an inside rotating body 1 at an angle of -45 deg. to +45 deg. in a rotating direction of the inside rotating body 1. As a result, in both cases of a case where cooling air collides against an outside surface of the inside rotating body 1 or a case where cooling air collides against an inside surface of the outside fixing body 2, components of cooling air moving in the direction opposite to the rotating direction of the inside rotating body 1 becomes a remarkably little amount and relatively large amount of cooling air moves in the same direction together with a rotating ball 41 along the rotating direction of the inside rotating body 1. Therefore, cooling air circulates in the gap 3 for a long time without decreasing wind speed, thus a cooling effect can be improved. |
