| 摘要 |
<p>A contact angle of a ball (15) to a first guide groove (21) of an inner joint member (12) is gradually decreased from an opening side toward a bottom side, and a curvature radius of the first guide groove (21) is gradually increased from the opening side toward the bottom side. When the contact angle alone is gradually decreased from the opening side to the bottom side, the contact angle is too small and unsmooth rotation is produced. When the curvature radius alone is gradually increased from the opening side to the bottom side, a contact ellipse (M2) formed by the ball (15) and the first guide groove (21) is too small and a concave is formed in the surface of the first guide groove (21) by the ball (15). However, the problem above can be eliminated when the contact angle is gradually decreased from the opening side to the bottom side and, at the same time, the curvature radius is gradually increased.</p> |
