Compact electric drive unit for automobile

摘要

The arrangement includes a stator and a rotor, with a reduction gearing and differential gearing closely coupled to the hollow rotor shaft housing the road wheel drive shaft. The wound (8) stator (7) is mounted within one portion (146) of a casing, finned to enhance cooling (111) and bolted to a complementary portion (148) housing the reduction and differential gears. The unit's axis (4) is approximately aligned with the driven road wheel axles. The rotor (9), carrying permanent magnets (13) and fitting closely inside the stator, is keyed (136) to a hollow shaft (119) running in bearings (50,152) at each end. One end (128) extends radially to carry the reduction gear planet wheels (127), which engage with a fixed sun wheel (125) and with a hollow toothed wheel (131) fixed on the rotating differential cage (135). The reduction ratio is 4:1. One of the differential driven shafts (43) extends through the casing (148) to drive one road wheel. The other (45) returns via the hollow rotor shaft (119) to drive the other road wheel. In an alternative configuration, the stator, mounted within the rotor's cylindrical shell, incorporates channels for liquid coolant and has a central end recess accommodating the gears, so minimizing the overall axial dimension. The driven shafts emerge from the unit at opposite ends.