Electric drive axle system with multi-speed gear train
Methods and systems for an electric drive axle of a vehicle are provided. An electric drive axle system includes, in one example, an electric motor-generator rotationally coupled to a gear train. The gear train includes an output shaft rotationally coupled to a gear assembly axially offset from an input shaft rotationally coupled to the electric motor-generator, where the gear assembly is rotationally coupled to a differential and the differential is rotationally coupled to an axle, a first clutch assembly is configured to rotationally couple and decouple a first gear set from the output shaft, and a second clutch assembly is configured to rotationally couple and decouple a second gear set from the output shaft, the second gear set having a different gear ratio than the first gear set.
1. An electric drive axle system, comprising:
an electric motor-generator rotationally coupled to a gear train, the gear train comprising:
an output shaft rotationally coupled to a gear assembly axially offset from an input shaft rotationally coupled to the electric motor-generator, the gear assembly rotationally coupled to a differential and the differential rotationally coupled to an axle;
a first clutch assembly configured to rotationally couple and decouple a first gear set from the output shaft; and
a second clutch assembly configured to rotationally couple and decouple a second gear set from the output shaft, the second gear set having a different gear ratio than the first gear set;
where the first clutch assembly includes a locking clutch and a one-way clutch.
2. The electric drive axle system of claim 1 , where the gear assembly is a planetary gear assembly.
3. The electric drive axle system of claim 2 , where the planetary gear assembly is positioned on a lateral side of a housing of the electric motor-generator.
4. The electric drive axle system of claim 2 , where the planetary gear assembly includes a single ring gear, carrier, and sun gear.
5. The electric drive axle system of claim 4 , where the ring gear is configured to remain stationary during operation of the electric drive axle system.
6. The electric drive axle system of claim 1 , where the axle is a beam axle.
7. The electric drive axle system of claim 1 , where the one-way clutch is a sprag clutch including a plurality of sprag mechanisms positioned between an extension of a gear in the first gear set and an outer surface of the output shaft.
8. The electric drive axle system of claim 1 , where the second clutch assembly includes a wet friction clutch.
9. The electric drive axle system of claim 1 , where the output shaft is co-axial with the axle.
10. The electric drive axle system of claim 1 , where the differential is an electronic locking differential or an electronic limited slip differential.
11. The electric drive axle system of claim 1 , where the electric drive axle system is included in an electric vehicle.
12. An electric drive axle system, comprising:
an electric motor-generator rotationally coupled to a gear train, the gear train comprising:
an output shaft rotationally coupled to a planetary gear assembly axially offset from an input shaft rotationally coupled to the electric motor-generator, the planetary gear assembly rotationally coupled to a differential and the differential rotationally coupled to an axle;
a first clutch assembly configured to rotationally couple and decouple a first gear set from the output shaft; and
a second clutch assembly configured to rotationally couple and decouple a second gear set from the output shaft, the second gear set having a different gear ratio than the first gear set;
where the axle is a beam axle extending between a first drive wheel and a second drive wheel and where the beam axle is positioned in an interior opening of the output shaft.
13. The electric drive axle system of claim 12 , where the planetary gear assembly includes a single ring gear, carrier, and sun gear, where the planetary gear assembly is positioned on a lateral side of the electric motor-generator, and where the output shaft is co-axial with the axle.
14. The electric drive axle system of claim 12 , where the first clutch assembly includes a locking clutch and a one-way clutch and where the second clutch assembly includes a wet friction clutch.
15. The electric drive axle system of claim 14 , where the one-way clutch is a sprag clutch including a plurality of sprag mechanisms positioned between an extension of a gear in the first gear set and an outer surface of the output shaft.
16. An electric drive axle system, comprising:
an electric motor-generator rotationally coupled to a gear train, the gear train comprising:
an output shaft rotationally coupled to a planetary gear assembly axially offset from an input shaft rotationally coupled to the electric motor-generator, the planetary gear assembly rotationally coupled to a differential and the differential rotationally coupled to a beam axle;
a first clutch assembly configured to rotationally couple and decouple a first gear set from the output shaft; and
a second clutch assembly configured to rotationally couple and decouple a second gear set from the output shaft, the second gear set having a different gear ratio than the first gear set;
where the first clutch assembly includes a sprag clutch including a plurality of sprag mechanisms positioned between an extension of a gear in the first gear set and an outer surface of the output shaft.
17. The electric drive axle system of claim 16 , where the planetary gear assembly is positioned on a lateral side of a housing of the electric motor-generator and includes a single ring gear, carrier, and sun gear and where the beam axle is positioned within an interior opening of the output shaft.