Transmission for E-axle
An electric transmission ( 16 ) for a motor vehicle drive train ( 12 ) includes a transmission input shaft ( 24 ) for operatively connecting the electric transmission to an electric prime mover ( 14 ), a reduction gear ( 26 ) for reducing a rotational speed of the electric prime mover, a transmission ( 28 ) for establishing gear steps, including a first planetary gear set (RS 1 ) and a second planetary gear set (RS 2 ), a first output shaft ( 34 ) and a second output shaft ( 36 ) for transmitting drive power from the electric transmission, and a plurality of shift elements (B, C, D) for engaging the gear steps. A planet carrier of the first planetary gear set is drivingly connected to a planet carrier of the second planetary gear set, and a sun gear of the first planetary gear set is drivingly connected to a ring gear of the second planetary gear set.
1. An electric transmission ( 16 ) for a motor vehicle drive train ( 12 ) of a motor vehicle ( 10 ), comprising:
a transmission input shaft ( 24 ) configured for operatively connecting the electric transmission to an electric prime mover ( 14 ) of the motor vehicle;
a reduction gear ( 26 ) configured for reducing a rotational speed of the electric prime mover;
a transmission ( 28 ) configured for establishing gear steps, the transmission ( 28 ) comprising a first planetary gear set (RS 1 ) and a second planetary gear set (RS 2 );
a first output shaft ( 34 ) and a second output shaft ( 36 ) configured for transmitting drive power from the electric transmission; and
a plurality of shift elements (B, C, D) configured for engaging the gear steps,
wherein a planet carrier of the first planetary gear set is drivingly connected to a planet carrier of the second planetary gear set,
wherein a sun gear of the first planetary gear set is drivingly connected to a ring gear of the second planetary gear set, and
wherein:
the shift elements (B, C, D) comprise a first brake (C), a second brake (D), and a clutch (B), an uncoupled sun gear of the transmission ( 28 ) connectable to the input shaft by the clutch (B) and rotationally fixable by the first brake (C), an uncoupled ring gear of the transmission ( 28 ) rotationally fixable by the second brake (D); or
the shift elements (B, C, D) comprise a first clutch (C), a brake (D), and a second clutch (B), a free shaft ( 40 ) connectable to an uncoupled ring gear of the transmission ( 28 ) by the first clutch (C), the free shaft connectable to an uncoupled sun gear of the transmission ( 28 ) by the second clutch (B), the free shaft rotationally fixable by the brake (D); or
the shift elements (B, C, D) comprise a first brake and a second brake, an uncoupled ring gear rotationally fixable by the first brake, an uncoupled sun gear rotationally fixable by the second brake.
2. The electric transmission ( 16 ) of claim 1 , wherein two reduction gear steps and one direct gear step are establishable with the electric transmission.
3. The electric transmission ( 16 ) of claim 1 , wherein:
the first planetary gear set (RS 1 ) and the second planetary gear set (RS) are radially nested; and
a planet carrier of the first planetary gear set and a planet carrier of the second planetary gear set are formed as one piece.
4. The electric transmission ( 16 ) of claim 1 , wherein the shift elements (B, C, D) are constant-mesh shift elements.
5. The electric transmission ( 16 ) of claim 1 , wherein the shift elements (B, C, D) include exactly three shift elements (B, C, D).
6. The electric transmission ( 16 ) of claim 1 , further comprising:
a ball or spur gear differential ( 32 ) at an output end of the electric transmission ( 16 ); or
an axially parallel or coaxial reduction gear in the form of a 2 -carrier 5 -shaft transmission with an integrated differential ( 32 ).
7. The electric transmission ( 16 ) of claim 6 , further comprising a differential lock(S).
8. The electric transmission ( 16 ) of claim 1 , wherein the electric transmission has an overall gear ratio of greater than two.
9. The electric transmission ( 16 ) of claim 1 , wherein a ratio step between two adjacent gear steps is less than two.
10. A motor vehicle drive train ( 12 ) for a motor vehicle ( 10 ), comprising:
the electric transmission ( 16 ) of claim 1 ; and
the electric prime mover ( 14 ) drivingly connected to the transmission input shaft ( 24 ).
11. The motor vehicle drive train ( 12 ) of claim 10 , wherein the electric prime mover is actuatable as a synchronizer during a gear shift in the electric transmission.
12. The motor vehicle drive train ( 12 ) of claim 10 , wherein:
the electric transmission ( 16 ) is drivingly connectable to a first motor vehicle axle;
a second motor vehicle axle is connectable to a further hybrid drive ( 18 ); and
the electric prime mover ( 14 ) is one or both of
suppliable with power by the further hybrid drive operated as a generator in order to establish a serial driving mode, and
actuatable as a supporting force mechanism in order to maintain a supporting force during gear shifts in the further hybrid drive.
13. A method for operating the motor vehicle drive train ( 12 ) of claim 10 , the method comprising one or more of:
actuating the electric prime mover as a synchronizer during a gear shift in the electric transmission;
supplying the electric prime mover ( 14 ) with power by a further hybrid drive operated as a generator in order to establish a serial driving mode; and
actuating the electric prime mover ( 14 ) as a supporting force mechanism in order to maintain a supporting force during gear shifts in the further hybrid drive.
14. A motor vehicle, comprising:
the motor vehicle drive train ( 12 ) of claim 10 ; and
an energy accumulator ( 20 ) configured for storing energy for supplying the electric prime mover ( 14 ).
15. A motor vehicle drive train ( 12 ) for a motor vehicle ( 10 ), comprising:
an electric prime mover ( 14 );
an electric transmission ( 16 ), comprising:
a transmission input shaft ( 24 ) drivingly connected to the electric prime mover ( 14 ) for operatively connecting the electric transmission ( 16 ) to the electric prime mover ( 14 );
a reduction gear ( 26 ) configured for reducing a rotational speed of the electric prime mover;
a transmission ( 28 ) configured for establishing gear steps, the transmission ( 28 ) comprising a first planetary gear set (RS 1 ) and a second planetary gear set (RS 2 );
a first output shaft ( 34 ) and a second output shaft ( 36 ) configured for transmitting drive power from the electric transmission; and
a plurality of shift elements (B, C, D) configured for engaging the gear steps,
wherein a planet carrier of the first planetary gear set is drivingly connected to a planet carrier of the second planetary gear set, and
wherein a sun gear of the first planetary gear set is drivingly connected to a ring gear of the second planetary gear set;
a further hybrid drive ( 18 );
a first motor vehicle axle drivingly connectable to the electric transmission ( 16 ); and
a second motor vehicle axle connectable to the further hybrid drive ( 18 ),
wherein the electric prime mover ( 14 ) is one or both of:
suppliable with power by the further hybrid drive operated as a generator in order to establish a serial driving mode, and
actuatable as a supporting force mechanism in order to maintain a supporting force during gear shifts in the further hybrid drive.