| 摘要 |
To limit the maximum speed of the fan blade of an automotive-type alternator, the fan blade (21) is secured to the outer race (23) of a ball bearing (22) having a two-part inner race (24, 25), one of the parts being an axially slidable sleeve (25) which is spring-pressed by a cup spring (26) in engagement with a drive pulley (18) against the first race (24). Until a certain limiting reactive pneumatic force or frictional force is reached, the cup spring (26) will clamp the balls (22) between the inner and outer races, so that the fan blade (21) will rotate with the pulley; when the reactive force and speed are exceeded, however, the fan blade can rotate about the balls (22), and hence slip with respect to the rotation of the pulley (18). |
