Drive mechanism and power shifting method of electric vehicles

Abstract

This invention relates to a drive mechanism and power shifting method for an electric vehicle. The drive mechanism comprises: a first drive wheel and a second drive wheel (R1, R2) having wheel axles (a1, a2); a first electric motor (EM1) and a second electric motor (EM2) having a common axis of rotation (m); a shift transmission (G3) having a transmission input shaft (EW) and a transmission output shaft (AW); and an axle differential (DI) having a differential input end (DIK) and two differential output shafts (3a, 3b), wherein the first electric motor (EM1) is connected to the transmission input shaft (EW), and the transmission output shaft (AW) is connected to the differential input end (DIK), and wherein the second electric motor (EM2) can be engaged as an additional drive as needed.

Description

Technical Field

[0001] This invention relates to a drive mechanism for an electric vehicle, comprising: a first drive wheel and a second drive wheel having wheel axles; a first electric motor and a second electric motor having a common axis of rotation; a shift transmission having a transmission input shaft and a transmission output shaft; and an axle differential. The invention also relates to a method for performing gear shifting under power (power shifting method) by means of a shifting device and a coupling device of the shift transmission. Background Technology

[0002] An earlier application, file number 10 2019 202 994.9, discloses a drive unit for an electric vehicle, comprising an electric motor and a three-speed or two-speed transmission, wherein a shifting device is provided having three or two shift elements for switching between three or two gears. By omitting the shift elements, the three-speed transmission can be used as a two-speed transmission. The transmission includes two interconnected planetary sets, wherein the first planetary set is driven by the electric motor via its sun shaft (transmission input shaft), and the ring gear shaft of the first planetary set is fixed. The first planetary set is connected to the ring gear shaft of the second planetary set via its planet carrier shaft. The planet carrier shaft of the second planetary set forms the transmission output shaft. The three or two shift elements are integrated into a sliding sleeve that is axially displaceable on the sun shaft of the second planetary set, resulting in a total of five positions for the three-speed transmission: three shift positions and two neutral positions. An earlier application also disclosed a drive axle with drive wheels, wherein a drive unit acts as a driver and drives an axle differential arranged between the drive wheels. Therefore, the transmission output shaft of the drive unit is connected to the differential input end (differential housing). Power shifting is not possible with this drive axle, which has only one electric drive unit, one shift transmission, and one axle differential. Shifting is performed when traction is interrupted, based on shifting elements designed as pawls. The aforementioned earlier application is fully incorporated into the disclosure of this application and is hereinafter referred to as the earlier application. Summary of the Invention

[0003] Starting from earlier applications, this invention aims to fully utilize additional potential.

[0004] According to the present invention, in the drive mechanism of an electric vehicle having two electric motors, a shift transmission, and an axle differential, a first electric motor is wedged into the axle differential via the shift transmission, and a second electric motor can be engaged as needed. Advantageously, the second electric motor can be considered, on the one hand, to enhance drive power (i.e., to assist the first electric motor) and / or on the other hand, to provide traction support during gear shifting. Since the shift element is designed as a pawl, traction interruption may occur without the second electric motor. When the second electric motor is engaged, power flows from the second electric motor into the shift transmission during gear shifting, thus preventing traction interruption and enabling power shifting. Furthermore, it is advantageous that although the drive axle has two electric motors, only one shift transmission is required.

[0005] According to an advantageous design, the gearbox is designed as a three-speed gearbox, which has three shift elements and two interconnected planetary gear sets forming gear sets. The gear sets include a first planetary gear set and a second planetary gear set, each having three shafts, wherein two shafts (i.e., the first planet carrier shaft and the second sun shaft) are fixedly and permanently connected to each other and form a coupling shaft. The second ring gear shaft is fixed; the first sun shaft is driven by a first electric motor.

[0006] According to another preferred embodiment, the first ring gear shaft is connected to the housing to switch to a first gear. The first ring gear shaft is connected to the second planetary carrier shaft to switch to a second gear. The planetary carrier shaft and the ring gear shaft of the first planetary set are interconnected (i.e., the first planetary set is interlocked) to switch to a third gear, wherein two other interlocking variations can also be implemented: the planetary carrier shaft is connected to the sun shaft and the sun shaft is connected to the ring gear shaft. Switching is achieved by a first shifting element (first gear), a second shifting element (second gear), and a third shifting element (third gear) forming the shifting device, respectively.

[0007] According to another preferred embodiment, the shift transmission is designed as a two-speed shift transmission, wherein the first gear is switched via a second shift element, and the second gear is switched via a third shift element. That is, compared to a three-speed shift transmission, the two-speed shift transmission omits only the first shift element. In other cases, the two-speed shift transmission has the same gear set as the three-speed shift transmission.

[0008] According to another preferred embodiment, the shifting element is designed with asynchronous pawls, wherein the shifting element is a robust and cost-effective shifting element.

[0009] According to another preferred embodiment, the first electric motor can be disconnected, for which the shifting device has at least one neutral position. By disconnecting the motor, the electric vehicle can travel freely without the resistance of a synchronously rotating electric motor.

[0010] According to another preferred embodiment, the three shifting elements are integrated into a sliding sleeve, which is arranged to be displaceable on a shaft (i.e., the gear ring shaft of the first planetary set). Thus, all shift positions and neutral positions (five positions) can be selected via the sliding sleeve and operated by a single actuator.

[0011] According to another preferred embodiment, the second electric motor is equipped with a coupling device having two engagement positions and one neutral position. Therefore, it is possible to deliver the power of the second electric motor to the shift transmission via two different paths as needed.

[0012] According to another preferred embodiment, the second electric motor is directly connected to the transmission input shaft at the first connection position. Therefore, the power or torque of the two electric motors is summed. Because the two machines rotate at the same speed in this connection, twice the drive power and twice the torque are obtained at the differential input when the electric motors are identical.

[0013] According to another preferred embodiment, the second electric motor is connected to the ring gear shaft of the first planetary gear set at a second engagement position. Therefore, the power of the second electric motor flows into the shift transmission via a second path, where a superposition operation occurs: the torques of the first and second electric motors are combined via the ring gear shaft and sun shaft in the first planetary gear set and summed in the planet carrier shaft. At this engagement position, traction support can be achieved in the shift transmission during shifting. If traction is interrupted during shifting through neutral, the second electric motor provides support via the first ring gear shaft, preventing traction interruption at the transmission output shaft. Therefore, power shifting can be achieved.

[0014] According to another preferred embodiment, the coupling device has a neutral position in which the second electric motor can be disconnected (i.e., not engaged). This avoids traction loss.

[0015] According to another preferred embodiment, the common axis of rotation of the electric motors is arranged perpendicular to the wheel axle (i.e., along the longitudinal direction of the electric vehicle), wherein the axle differential is driven by the transmission output shaft via a bevel gear assembly. This drive mechanism is referred to as the central drive, wherein the electric motors and the shift transmission are located outside the axle, which comprises only the axle differential and the drive wheels. The two electric motors can be designed to be the same or different in terms of type, power, speed, torque, and / or efficiency range.

[0016] According to another aspect of the invention, in a method for performing gear shifting under power (the so-called power shifting method), a first electric motor operates as the main drive machine and a second electric motor can be considered for providing traction support during the gear shifting process. Therefore, the advantage of power shifting, i.e., shifting without interruption of traction, is achieved.

[0017] According to a preferred variation of the method, the first gear shaft is coupled to a second electric motor to prepare for shifting in the shift transmission. As a result, additional power flows into the shift transmission, and the second electric motor provides support during the shifting process, particularly when passing through neutral. Therefore, no interruption of traction occurs.

[0018] According to another preferred variation of the method, the shifting elements are synchronized by a second electric motor during the shifting process. Therefore, smooth, material-protective shifting can be performed, i.e., the shifting elements are closed while the speeds are synchronized.

[0019] According to another preferred variation of the method, if this power is no longer needed, the second electric machine can be disconnected after the shifting process is completed (i.e., after the gear is engaged). Attached Figure Description

[0020] Embodiments of the invention are illustrated in the accompanying drawings, which will be described in more detail below, wherein other features and / or advantages may be obtained from the specification and / or drawings. In the drawings:

[0021] Figure 1 The diagram illustrates a first drive mechanism of an electric vehicle, serving as the central drive unit. This first drive mechanism comprises two electric motors and a three-speed transmission.

[0022] Figure 2 The second drive mechanism, which serves as the central drive, is shown and has a two-speed shift gearbox. Detailed Implementation

[0023] Figure 1A first drive mechanism 1 for an electrically driven vehicle (hereinafter referred to as an electric vehicle) is shown as a first embodiment of the present invention. This first drive mechanism is designed as a so-called central drive. The drive mechanism 1 includes a drive unit 1a, which consists of a first electric motor EM1 having a first rotor RO1, a second electric motor EM2 having a second rotor RO2, and a three-speed transmission G3 having a shifting device SE3 and a connecting device KE. The electric motors EM1 and EM2 have a common axis of rotation m, which extends along the longitudinal direction of the electric vehicle. The axis of rotation m is also the axis of symmetry of the transmission G3, and only the upper half of the transmission is shown. The drive mechanism 1 also includes a conventional axle 1b having a first drive wheel R1 and a second drive wheel R2 with corresponding wheel axles a1 and a2, an axle differential DI, and two differential output shafts 3a and 3b that drive the drive wheels R1 and R2. The wheel axles a1 and a2 are arranged transversely to the axis of rotation m. The axle differential DI has a differential input or differential housing DIK, which is driven by a bevel gear assembly KT (which consists of a bevel pinion KT1 and a crown gear KT2).

[0024] The shifting device SE3 can be operated by the first actuator AK1, and the connecting device KE can be operated by the second actuator AK2. The shifting device SE3 has three shifting elements for switching three gears: a first shifting element A, a second shifting element B, and a third shifting element C. All three gears can be shifted using a sliding sleeve SM. The connecting device KE has two connecting elements for connecting the second electric machine EM2: a first connecting element D and a second connecting element E.

[0025] The three-speed shift transmission G3 (hereinafter referred to as shift transmission G3) includes two interconnected planetary sets: a first planetary set PS1 having a first sun shaft SO1, a first planetary carrier shaft ST1, and a first ring gear shaft HR1; and a second planetary set PS2 having a second planetary carrier shaft ST2, a second ring gear shaft HR2 fixed to the housing, and a second sun shaft SO2. The second sun shaft is fixedly and permanently connected to the first planetary carrier shaft ST1, forming the connecting shaft between the two planetary sets PS1 and PS2. The first sun shaft SO1 is fixedly connected to the first rotor RO1, thus forming the transmission input shaft EW of shift transmission G3. The second planetary carrier shaft ST2 forms the transmission output shaft AW, which drives the axle differential DI via a bevel gear assembly KT. The two planetary sets PS1 and PS2 form a gear set, which can also be used in a two-speed shift transmission G2 (…). Figure 2 ).

[0026] The shifting device SE3 allows switching between three gears: To engage the first gear, the first gear ring shaft HR1 is connected and fixed to the housing (shown by shaded lines) by closing the first shifting element A. Therefore, the two planetary sets PS1 and PS2 operate at fixed gear ratios, which are multiplied together to obtain the gear ratio for the first gear.

[0027] By closing the second shifting element B, the second gear is engaged, connecting the first ring gear shaft HR1 to the second planetary carrier shaft ST2. Therefore, a double connection exists between the first planetary set PS1 and the second planetary set PS2, resulting in a superimposed operation.

[0028] By closing the third shift element C, the third gear is switched, and the first planetary gear set PS1 is interlocked, which in principle allows two of the three shafts SO1, HR1, and ST1 to be interconnected. In the illustrated embodiment, the first planetary carrier shaft ST1 is connected to the first ring gear shaft HR1. Through interlocking, the first planetary gear set PS1 operates as a whole, i.e., at a 1:1 gear ratio, so that the gear ratio of the third gear is derived from the fixed gear ratio of the second planetary gear set PS2.

[0029] Shift elements A, B, and C are preferably designed as asynchronous pawls. In principle, friction-fitting shift elements and synchronous shift elements can also be used for the shifting function. The shift transmission G3 has two neutral positions between these three shift positions. In each of the three shift positions, either the first shift element A, the second shift element B, or the third shift element C is closed. In these two neutral positions, the first electric motor EM1 is disengaged from the shift transmission G3. This enables so-called coasting operation (Segelbetrieb), where the electric vehicle moves freely without the loss of the synchronously rotating first electric motor EM1.

[0030] As described above, the first ring gear shaft HR1 of the first planetary gear set PS1 participates in all three shift positions—thus, all shift elements (i.e., the first shift element, the second shift element, and the third shift elements A, B, and C) can be integrated into a single sliding sleeve SM, which is anti-rotatably connected to the first ring gear shaft HR1 in all shift positions. The sliding sleeve SM is operated by a single actuator AK1. Because first to third gear can be shifted sequentially through neutral each time by moving the sliding sleeve SM in one direction, it is possible to synchronize the shift elements.

[0031] The second electric motor EM2 can be connected or disconnected via the connecting device KE. The connecting device KE has a first connecting element D and a second connecting element E. The second connecting element E connects the second electric motor EM2, or its rotor RO2, to the transmission input shaft EW of the shift transmission G3. Through this connection of the two rotors RO1 and RO2, the two electric motors EM1 and EM2 operate at the same speed. This increases the drive power of the second electric motor EM2, which can potentially double (assuming the electric motors EM1 and EM2 are identical).

[0032] The second electric motor EM2 is connected to the first gear ring shaft HR1 via the first connecting element D. Therefore, the power of the second electric motor EM2 flows into the shift transmission G3 via the second path; the power flows of the two electric motors EM1 and EM2 are superimposed in the first planetary gear set PS1 and are delivered to the second planetary gear set PS2 via the connecting shaft ST1 / SO2.

[0033] According to the present invention, traction support is achieved during gear shifting via the first engagement position D of the coupling device KE, thereby enabling power shifting via the shift transmission G3. If, for example, the power flow of the first electric machine EM1 is interrupted during gear shifting (i.e., engaging a new gear), a torque fed by the second electric machine EM2 is applied to the ring gear shaft HR1 of the first planetary set PS1, which maintains traction in the driven shaft AW or the second planetary carrier shaft ST2. Gear shifting without interruption of traction is also referred to as a power shifting method, which is described in more detail below.

[0034] According to the power shifting method of the present invention, the first electric motor EM1 functions as the main drive machine because it is fixedly connected to the shift transmission G3 via the transmission input shaft EW. To support shifting, the second electric motor EM2 is ready to be connected to the first gear ring shaft HR1.

[0035] The shifting process from first gear to second gear will be described below, wherein the first shifting element A of the shifting device SE3 is first disengaged and then the second shifting element B is subsequently closed. Starting from the condition that the second electric motor EM2 is already connected to the transmission input shaft EW (i.e., both electric motors EM1 and EM2 are driven together), the power at the second electric motor EM2 is first eliminated. Then, the second connecting element E of the connecting device KE is disengaged, and the first connecting element D is synchronized with the second electric motor EM2, i.e., braked to zero speed. Then, the first connecting element D is closed, and the second electric motor EM2 is connected to the first gear ring shaft HR1. Next, torque is generated by the second electric motor EM2, thereby reducing the load on the first shifting element A, which acts as a brake. If the second electric motor EM2 cannot apply sufficient torque, then the torque of the first electric motor EM1 is correspondingly reduced. Then, the first shifting element A is disengaged. Therefore, the torques of the first electric motor and the second electric motors EM1 and EM2 are controlled or adjusted to increase the speed of the second electric motor EM2 and decrease the speed of the first electric motor EM1. Therefore, if feasible, it is preferable, for example, to increase the torque of the second electric motor EM2 while slightly decreasing the torque of the first electric motor EM1. The target speed of the first ring gear shaft HR1 (which corresponds to the rotational speed of the second electric motor EM2) is the rotational speed of the second planetary carrier shaft ST2, thereby synchronizing the second shift element B. Once the second shift element B is synchronized, it can be closed. The torques of the first electric motor and the second electric motors EM1 and EM2 can now be arbitrarily divided because a fixed gear, namely the second gear, is engaged. When needed, the second electric motor EM2 can be disconnected from the first ring gear shaft HR1. If full drive power is desired, the second electric motor EM2 can also be connected to the transmission input shaft EW or the first sun shaft SO1.

[0036] The power shifting method, when shifting from the second gear to the third gear (whereby the second shift element B is disengaged and the third shift element C is engaged), is similar to the shifting process from the first gear to the second gear, and is described in detail below:

[0037] Starting from the condition that the second electric motor EM2 is already connected to the transmission input shaft EW (i.e., both electric motors EM1 and EM2 are driven together), the power at the second electric motor EM2 is first eliminated. Then, the second connecting element E of the connecting device KE is disconnected, and the first connecting element D is synchronized with the second electric motor EM2. Then, the first connecting element D is closed, and the second electric motor EM2 is connected to the first gear shaft HR1. Next, torque is generated by the second electric motor EM2, thereby reducing the load on the second shift element B. If the second electric motor EM2 cannot apply sufficient torque, then the torque of the first electric motor EM1 is correspondingly reduced. Then, the second shift element B is disconnected. Therefore, the torques of the first electric motor and the second electric motors EM1 and EM2 are controlled or adjusted to increase the speed of the second electric motor EM2 and decrease the speed of the first electric motor EM1. For this purpose, if feasible, it is preferable, for example, to increase the torque of the second electric motor EM2 while slightly reducing the torque of the first electric motor EM1. The target speed of the first ring gear shaft HR1 (which corresponds to the speed of the second electric machine EM2) is the speed of the first planetary carrier shaft ST1 or the second sun shaft SO2, thereby synchronizing the third shift element C. Once the third shift element C is synchronized, it can be closed. The torque of the first electric machine and the second electric machines EM1 and EM2 can now be arbitrarily divided because a fixed gear, the third gear, is engaged. When needed, the second electric machine EM2 can be disconnected from the first ring gear shaft HR1. If full drive power is desired, the second electric machine EM2 can also be kept connected to the ring gear shaft HR1. Because the first planetary set PS1 operates as a whole in the third gear, it is not necessary to reconnect the second electric machine EM2 from the first ring gear shaft HR1 to the transmission input shaft EW, as all three shafts have the same speed during overall operation.

[0038] Downshifting is done in a similar manner, except that it is done in the opposite direction of the rotational speeds of the first and second electric motors EM1 and EM2.

[0039] Over-range shifting is performed similarly, except that it is performed with opposite torques from the first electric motor and the second electric motor EM1, EM2.

[0040] Figure 2 The drive mechanism 2, which serves as a central drive and includes a drive unit 2a and an axle 2b, is shown as another embodiment of the invention. The same components are used with... Figure 1 Same reference numerals as in the accompanying drawings. (According to...) Figure 1The difference between the drive mechanism 1 and the transmission 2 is that the shift transmission is implemented here as a two-speed shift transmission G2 and has a shifting device SE2 with only two shifting elements (i.e., the second shifting element B and the third shifting element C). Therefore, compared with the transmission 2 according to the drive mechanism 1, the shift transmission is implemented here as a two-speed shift transmission G2 and has a shifting device SE2 with only two shifting elements (i.e., the second shifting element B and the third shifting element C). Figure 1 Compared to the three-speed shift transmission G3, the first shift element A is omitted in the two-speed shift transmission G2. The first and second gears are switched using two shift elements B and C. With the second shift element B closed, the first ring gear shaft HR1 is connected to the second planetary carrier shaft ST2; the first and second planetary sets PS1 and PS2 are then doubly interconnected, resulting in a superimposed operation with a running gear ratio. The second gear is formed by closing the third shift element C, thereby interlocking the first planetary set PS1. In the illustrated embodiment, the first ring gear shaft HR1 and the first planetary carrier shaft ST1 are interconnected. During overall operation, all three shafts rotate at the same speed. Two other interlocking variations for the first planetary set PS1 can be implemented: the ring gear shaft is connected to the sun shaft, or the planetary carrier shaft is connected to the sun shaft, where the latter case may require an additional sliding sleeve.

[0041] The output shaft AW (second planetary carrier shaft ST2) of the two-speed transmission G2 is connected to the axle differential DI via a bevel gear assembly KT. The axle differential drives the drive wheels R1 and R2 via its output shafts 3a and 3b. Therefore, the drive unit 2a is connected to the axle 2b via the transmission output shaft AW and can thus be arranged at any distance from the axle 2b, for example, in the "central" position of an electric vehicle.

[0042] List of reference numerals

[0043] 1. Drive mechanism

[0044] 1a Drive Unit

[0045] 1b Axle

[0046] 2. Drive mechanism

[0047] 2a Drive Unit

[0048] 2b axle

[0049] 3a Differential output shaft

[0050] 3b Differential output shaft

[0051] A First shifting element

[0052] AK1 actuator

[0053] AK2 actuator

[0054] AW transmission output shaft

[0055] a1 Wheel axle (R1)

[0056] a2 Wheel axle (R2)

[0057] B Second shift element

[0058] C Third shift element

[0059] D First connecting element

[0060] DI axle differential

[0061] DIK differential housing / differential input

[0062] E Second connecting element

[0063] EM1 First Electric Machine

[0064] EM2 Second Electric Machine

[0065] EW transmission input shaft

[0066] G2 two-speed shift gearbox

[0067] G3 three-speed shift transmission

[0068] HR1 First Gear Shaft (PS1)

[0069] HR2 Second Gear Shaft (PS2)

[0070] KE Connection Device

[0071] KT bevel gear device

[0072] KT1 pinion

[0073] KT2 Crown Gear

[0074] m Rotation axis (EM1, EM2)

[0075] PS1 First Planet Group

[0076] PS2 Second Planet Group

[0077] R1 drive wheel

[0078] R2 drive wheel

[0079] RO1 rotor (EM1)

[0080] RO2 rotor (EM2)

[0081] SE2 shift mechanism (G2)

[0082] SE3 shift mechanism (G3)

[0083] SM sliding sleeve

[0084] SO1 First Sun Axis (PS1)

[0085] SO2 Second Sun Axis (PS2)

[0086] ST1 First Planetary Carrier (PS1)

[0087] ST2 Second Planetary Carrier (PS2)

Claims

1. A drive mechanism for an electric vehicle, the drive mechanism comprising: - A first drive wheel (R1) and a second drive wheel (R2) having wheel axles (a1, a2). - A first electric machine (EM1) and a second electric machine (EM2) sharing a common axis of rotation (m). - Shift transmissions with input shaft (EW) and output shaft (AW) (G3, G2), and - An axle differential (DI) with a differential input (DIK) and two differential output shafts (3a, 3b). - wherein the first electric motor (EM1) is connected to the transmission input shaft (EW), and the transmission output shaft (AW) is connected to the differential input (DIK), and -The second electric motor (EM2) can be switched on as an additional driver as needed. in, The shift transmission has two interconnected planetary sets (PS1, PS2), wherein the first planetary set (PS1) has a first sun shaft (SO1), a first ring gear shaft (HR1), and a first planet carrier shaft (ST1), and the second planetary set (PS2) has a second sun shaft (SO2), a second ring gear shaft (HR2), and a second planet carrier shaft (ST2), wherein the first planet carrier shaft (ST1) is fixedly connected to the second sun shaft (SO2), wherein the first sun shaft (SO1) forms the transmission input shaft (EW), wherein the second ring gear shaft (HR2) is fixed, and wherein the second planet carrier shaft (ST2) forms the transmission output shaft (AW). The first gear ring shaft (HR1) can be connected to the second planetary carrier shaft (ST2). The second electric motor (EM2) is connected to the first gear ring shaft (HR1) via a connecting element. The gearbox includes a third shift element (C). The first planetary gear set (PS1) is interlocked via the third shifting element (C).

2. The driving mechanism according to claim 1, characterized in that, The gearbox is designed as a three-speed gearbox (G3) having a first shift element (A), a second shift element (B), a third shift element (C) and two interconnected planetary gear sets (PS1, PS2), wherein the first shift element (A) can be operated to shift to a first gear, the second shift element (B) can be operated to shift to a second gear, and the third shift element (C) can be operated to shift to a third gear.

3. The driving mechanism according to claim 2, characterized in that, The first gear ring shaft (HR1) can be connected to the housing via the first shifting element (A).

4. The driving mechanism according to claim 1, characterized in that, The gearbox is designed as a two-speed gearbox (G2) having a second shift element (B), a third shift element (C), and two interconnected planetary gear sets (PS1, PS2), wherein the second shift element (B) can be operated to switch to a first gear, and the third shift element (C) can be operated to switch to a second gear.

5. The driving mechanism according to any one of claims 1 to 4, characterized in that, The shifting elements (A, B, C) are designed as asynchronous chucks.

6. The driving mechanism according to any one of claims 1 to 4, characterized in that, The shift transmission (G3, G2) has a neutral position in which the first electric motor (EM1) can be disconnected.

7. The driving mechanism according to any one of claims 1 to 4, characterized in that, The first shift element (A), the second shift element (B) and / or the third shift element (C) are integrated into a sliding sleeve (SM), and the sliding sleeve (SM) is arranged to be displaceable on the first gear shaft (HR1).

8. The driving mechanism according to claim 7, characterized in that, The sliding sleeve (SM) can be manipulated by an actuator (Ak1).

9. The driving mechanism according to any one of claims 1 to 4, characterized in that, The second electric machine (EM2) can be switched on by means of a coupling device (KE) having two connection positions.

10. The driving mechanism according to claim 9, characterized in that, In the first connection position, the second electric motor (EM2) can be connected to the transmission input shaft (EW) or the first sun shaft (SO1).

11. The driving mechanism according to claim 9, characterized in that, In the second connection position, the second electric motor (EM2) can be connected to the first gear shaft (HR1).

12. The driving mechanism according to claim 9, characterized in that, The connecting device (KE) has a neutral position in which the second electric motor (EM2) can be disconnected.

13. The drive mechanism according to any one of claims 1 to 4, characterized in that, The wheel axles (a1, a2) and the differential output shafts (3a, 3b) are arranged perpendicular to the rotation axis (m) of the electric motors (EM1, EM2), and the differential (DI) can be driven by the transmission output shaft (AW) via a bevel gear assembly (KT).

14. The driving mechanism according to claim 1, characterized in that, The first gear shaft (HR1) can be connected to the first planetary carrier shaft (ST1) or the second sun shaft (SO2).

15. A power shifting method, the method being used to perform power shifting by means of shifting elements (A, B, C) and coupling elements of the shift transmission (G3, G2) and a first electric motor (EM1) and a second electric motor (EM2) according to any one of the preceding claims, characterized in that, - The first electric motor (EM1) operates as the main drive machine, and - The second electric motor (EM2) is used to provide traction support during the gear shifting process. The second electric motor (EM2) is connected to the first gear ring shaft (HR1) of the shift transmission via the connecting element.

16. The power shifting method according to claim 15, characterized in that, Connect the first gear shaft (HR1) to the second electric motor (EM2) in preparation for switching from the first gear to the second gear or from the second gear to the third gear.

17. The power shifting method according to claim 15 or 16, characterized in that, Synchronization is achieved during the gear shifting process via the second electric motor (EM2).

18. The power shifting method according to claim 15 or 16, characterized in that, The second electric motor (EM2) can be disconnected after the shifting process is completed.

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