Multi-speed electric axle and electric axle shifting strategy
Systems and methods for a multi-speed electric axle. The multi-speed electric axle includes an electric motor that is rotationally coupled to an input shaft. The multi-speed electric axle also includes a planetary gearset connected to the input shaft via an input gear reduction, a lower-speed clutch that selectively grounds a ring gear in the planetary gearset to a housing, and a higher-speed clutch that selectively connects a sun gear to a carrier.
1. A multi-speed electric axle comprising:
an electric motor rotationally coupled to an input shaft;
a planetary gearset connected to the input shaft via an input gear reduction;
a lower-speed clutch configured to selectively ground a gear in the planetary gearset;
a higher-speed clutch configured to selectively connect a sun gear to a case of a differential;
a housing enclosing the planetary gearset, the higher-speed clutch, and the lower-speed clutch; and
a first actuation assembly configured to actuate the higher-speed clutch and positioned axially between a carrier in the planetary gearset and a first plate carrier that is included in the higher-speed clutch;
wherein the first plate carrier is coupled directly to the case.
2. The multi-speed electric axle of claim 1 , wherein the first plate carrier is an outer plate carrier.
3. The multi-speed electric axle of claim 1 , wherein the gear is a ring gear.
4. The multi-speed electric axle of claim 3 , wherein the higher-speed clutch is positioned axially between the case and the ring gear.
5. The multi-speed electric axle of claim 4 , wherein the lower-speed clutch, when engaged, grounds the ring gear to the housing.
6. The multi-speed electric axle of claim 1 , further comprising:
a second actuation assembly configured to actuate the lower-speed clutch and positioned axially between two portions of the housing that radially extend inward along opposing axial sides of the lower-speed clutch.
7. The multi-speed electric axle of claim 1 , wherein the multi-speed electric axle is a beam axle.
8. The multi-speed electric axle of claim 1 , wherein the higher-speed clutch and the lower-speed clutch are wet friction clutches.
9. The multi-speed electric axle of claim 1 , wherein the differential is a spider gear differential.
10. The multi-speed electric axle of claim 1 , wherein the higher-speed clutch includes a second plate carrier coupled to the sun gear.
11. The multi-speed electric axle of claim 1 , wherein the planetary gearset is a simple planetary gearset.
12. The multi-speed electric axle of claim 1 , wherein the first actuation assembly is a hydraulic piston.
13. 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 in the planetary gearset;
the higher-speed clutch configured to selectively connect a sun gear to a case of a differential;
a housing enclosing the planetary gearset, the higher-speed clutch, and the lower-speed clutch; and
a first actuation assembly configured to actuate the higher-speed clutch and positioned axially between a carrier in the planetary gearset and a first plate carrier that is included in the higher-speed clutch;
wherein the higher-speed clutch includes a plate carrier directly coupled to the case.
14. The method of claim 13 , wherein the plate carrier is an outer plate carrier.
15. The method of claim 13 , wherein powershifting between the higher gear and the lower gear includes engaging the lower-speed clutch and grounding the ring gear to the housing.
16. A multi-speed electric axle comprising:
an electric motor rotationally coupled to an input shaft;
a planetary gearset connected to the input shaft via an input gear reduction;
a lower-speed friction clutch configured to selectively ground a gear in the planetary gearset to a housing;
a higher-speed friction clutch configured to selectively connect a sun gear to a case of a differential;
the housing which encloses the planetary gearset, the higher-speed friction clutch, and the lower-speed friction clutch; and
a first actuation assembly configured to actuate the higher-speed friction clutch and positioned axially between a carrier in the planetary gearset and a first plate carrier that is included in the higher-speed friction clutch;
wherein the higher-speed friction clutch includes:
an outer plate carrier coupled directly to the case; and
an inner plate carrier directly coupled to the sun gear.
17. The multi-speed electric axle of claim 16 , wherein the planetary gearset is a simple planetary gearset.
18. The multi-speed electric axle of claim 16 , wherein the higher-speed friction clutch is positioned axially between the case and the lower-speed friction clutch.
19. The multi-speed electric axle of claim 16 , wherein the electric motor is an alternating current (AC) motor.
20. The multi-speed electric axle of claim 16 , wherein the differential is a spider gear differential or a planetary differential.