Multi-speed electric axle and electric axle shifting strategy

1. A multi-speed electric axle comprising:

an electric motor rotationally coupled to an input shaft;

a planetary gearset rotationally coupled to an output shaft;

a gear reduction rotationally coupled to the input shaft and the output shaft;

a lower-speed clutch configured to selectively ground a ring gear of the planetary gearset to a housing; and

a higher-speed clutch configured to selectively connect the output shaft to a carrier of the planetary gearset;

wherein a sun gear of the planetary gearset is directly coupled to the output shaft;

wherein the carrier is rotationally coupled to a differential; and

wherein the higher-speed clutch is positioned axially between the differential and the ring gear.

2. The multi-speed electric axle of claim 1 , wherein the input gear reduction includes an idler gear on an idler shaft.

3. The multi-speed electric axle of claim 2 , wherein the electric motor is positioned on a side of the housing that circumferentially encloses the higher-speed clutch and the lower-speed clutch.

4. The multi-speed electric axle of claim 1 , wherein the higher-speed clutch is directly coupled to a case of a differential.

5. The multi-speed electric axle of claim 1 , wherein the lower-speed clutch and the higher-speed clutch are wet friction clutches.

6. The multi-speed electric axle of claim 1 , wherein the planetary gearset is a simple planetary gearset.

7. The multi-speed electric axle of claim 1 , wherein the sun gear is fixedly coupled to a shaft that is coaxial to an axle shaft.

8. The multi-speed electric axle of claim 7 , wherein the housing includes an interior section portion which radially extends inward along an axial side of the lower-speed clutch.

9. The multi-speed electric axle of claim 8 , further comprising a first bearing coupled to the shaft and an axially extending portion of the interior section of the housing.

10. The multi-speed electric axle of claim 9 , further comprising a second bearing coupled to the axially extending portion of the interior section of the housing and a set of plates of the lower-speed clutch.

11. A method for operation of a multi-speed electric axle, comprising:

powershifting between a higher gear and a lower gear via operation of a higher-speed clutch and a lower-speed clutch in the multi-speed electric axle;

wherein the multi-speed electric axle comprises:

an electric motor rotationally coupled to an input shaft;

a planetary gearset connected to the input shaft via an input gear reduction;

the lower-speed clutch configured to selectively ground a ring gear of the planetary gearset to a housing; and

the higher-speed clutch configured to selectively connect a sun gear to a carrier of the planetary gearset;

wherein the higher-speed clutch is positioned axially between the differential and the ring gear.

12. The method of claim 11 , wherein powershifting between the higher gear and the lower gear includes engaging the higher-speed clutch while disengaging the lower-speed clutch.

13. The method of claim 11 , wherein:

the planetary gearset, the higher-speed clutch, and the lower-speed clutch are enclosed within the housing; and

the housing is directly coupled to an axle shaft housing.

14. The method of claim 11 , wherein the higher-speed clutch and the lower-speed clutch are wet friction clutches that each includes a first set of plates and a second set of plates, respectively.

15. The method of claim 14 , wherein the second set of plates is coupled to an inner section of the housing.

16. A two-speed electric axle comprising:

an electric motor driving an input shaft;

a simple planetary gearset rotationally coupled to an output shaft which is rotationally coupled to the input shaft via an input gear reduction;

a higher-speed clutch that selectively grounds a ring gear of a planetary gearset to a housing; and

a lower-speed clutch that:

in an engaged configuration, connects a sun gear and a carrier of the simple planetary gearset; and

in a disengaged configuration, allows the sun gear and the carrier to independently rotate;

wherein the carrier is directly coupled to a case of a differential; and

wherein the higher-speed clutch is positioned axially between the differential and the ring gear.

17. The two-speed electric axle of claim 16 , wherein:

a set of plates of the higher-speed clutch is coupled to the case of the differential; and

a shaft to which the sun gear is fixedly coupled is directly coupled to the case.

18. The two-speed electric axle of claim 16 , wherein a shaft extends from the case to a bearing coupled to the housing.

19. The two-speed electric axle of claim 16 , wherein the higher-speed clutch and the lower-speed clutch are positioned on one axial side of the differential.

20. The two-speed electric axle of claim 16 , wherein the differential is a spider gear type differential.