| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a such configuration as engagement rate of gears in a gear transmission does not degrade even under prying of a wheel hub which accompanies occurrence of the lateral force of a tire. <P>SOLUTION: The rotation of a rotor (7) of an electric motor 4 is transmitted to a sun gear 11 of a gear set 5 by way of an input shaft 8, and a stepped planetary pinion 13 is caused to roll along the inner periphery of a ring gear 12 and the outer periphery of the sun gear 11. The rolling is propagated to a wheel hub 9 through carriers 14a and 14b and a hollow drive shaft 21 in this order. A planetary gear structure consisting of the carriers 14a and 14b and the stepped planetary pinion 13 is rotatably supported on the input shaft 8 using bearings 19 and 20. An end part of the input shaft 8 on a wheel side is rotatably supported on the wheel hub 9 using a bearing 18, and the opposite end is rotatably supported on a rear cover 2 of a housing 3 using a bearing 17. Consequently, the planetary gear structure is displaced in radial direction together with the input shaft 8 in integral manner even under prying (A) of the wheel hub 9 that accompanies occurrence of the lateral force of a tire, causing no degradation in engagement rate of the gears in the gear transmission. <P>COPYRIGHT: (C)2012,JPO&INPIT |
