| 摘要 |
A self-ventilated bi-directional traction drive unit (10) comprises a bi-directional motor (12), an asymmetric fan (14) for ventilating the motor (12), and a mechanical transmission (14) between a motor shaft (24) of the motor (12) and an asymmetric fan rotor (38) of the fan (14). The mechanical transmission (14) is operative to drive the fan rotor (38) in a preferred fan direction (102) with a first constant gear ratio Ri when the motor shaft (24) rotates in a first traction direction and to drive the fan rotor (38) in the preferred fan direction with a second constant gear ratio R2 when the motor shaft (24) rotates in a second traction direction opposite to the first traction direction. The mechanical transmission (14) includes a planetary gear train (28) comprising a sun gear (30), a sun gear (32) and a set of one or more planet gears (34) supported on at least one planet carrier (36) and further includes free wheels (40, 42, 44, 46, 48, 50, 52), A first (46) of the free wheels operates between the planet carrier (36) and the fan rotor (38) to block the rotation of the fan rotor (38) with respect to the planet carrier (36) in a direction opposite to the preferred fan direction and a second (50) of the free wheels operates between the ring gear (32) and the fan rotor (38) to block the rotation of the fan rotor (38) with respect to the ring gear (32) in the preferred fan direction and in that the mechanical transmission (14) is such that (I). |
