CN111853098A

CN111853098A - Drive train for an electric or hybrid vehicle, drive train and method for operating a drive train

Info

Publication number: CN111853098A
Application number: CN202010226129.XA
Authority: CN
Inventors: F·P·布雷兹格尔
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2019-04-25
Filing date: 2020-03-26
Publication date: 2020-10-30
Also published as: DE102019003004A1

Abstract

The invention relates to a transmission (6) for a drive train (2) of an electric or hybrid vehicle, having a first shaft (8) which is connected in a rotationally driving manner to an electric machine (4) and a second shaft (10), wherein the transmission (6) can be switched from a first gear (14), in which the first shaft (8) is connected or connected in a rotationally driving manner to the second shaft (10) with a first transmission ratio, into a second gear (16), in which the first shaft (8) is connected or connected in a rotationally driving manner to the second shaft (10) with a second transmission ratio, which is smaller than the first transmission ratio. The first shaft (8) is connected or can be rotationally driven to the second shaft (10) in the first gear (14) via a freewheel clutch (30) and in the second gear (16) via a friction-locking clutch (32). The invention further relates to a drive train (2) having such a transmission (6) and to a method for operating such a drive train (2).

Description

Drive train for an electric or hybrid vehicle, drive train and method for operating a drive train

Technical Field

The invention relates to a transmission for a drive train of an electric or hybrid vehicle, having a first shaft which is connected in a rotationally driving manner to an electric machine, and having a second shaft, wherein the transmission can be switched from a first gear, in which the first shaft is connected in a rotationally driving manner or in a rotationally driving manner to the second shaft with a first transmission ratio, into a second gear, in which the first shaft is connected in a rotationally driving manner or in a rotationally driving manner to the second shaft with a second transmission ratio, which is smaller than the first transmission ratio. The invention also relates to a drive train for an electric or hybrid vehicle, having an electric machine and such a transmission. The invention also relates to a method for operating a drive train of an electric or hybrid vehicle.

Background

In practice, drive trains for electric or hybrid vehicles are known, which have an electric machine, wherein the electric machine can be operated as an engine or as a generator in the drive train, and can therefore also be referred to as an engine or a generator of the electric machine. In this case, the electric machine or its output shaft is usually connected, in particular when the electric machine is arranged in parallel, via a transmission to a further shaft, which can be arranged, for example, in the torque transmission path of the drive train and, in the case of a hybrid vehicle, can also be driven by the internal combustion engine. In this transmission, a first shaft is therefore provided which is connected in a rotationally driving manner to the electric machine, and a second shaft is provided which is connected in a rotationally driving manner to one another via a gear stage. In this case, a freewheel is known, for example, for shifting gears, which enables the second shaft to be driven by the first shaft via a freewheel clutch, wherein an electric machine, which is used here as a starter, can be overrun after an internal combustion engine in a hybrid vehicle has started. In this case, such freewheel clutches have a great utility, but do not meet the comfort requirements of modern drive trains. It is also known to connect the output side of the electric machine to the torque path via a friction-locking clutch, for example a wet-running diaphragm clutch, so that a particularly uniform shift can be achieved, which in addition meets high comfort requirements. However, the effectiveness of such shift elements is significantly reduced when the electric machine is connected in the drive train, for example due to drag torques in wet-running friction-locking clutches.

Disclosure of Invention

It is therefore an object of the present invention to provide a transmission for a drive train of an electric or hybrid vehicle, which ensures a small-sized electric machine, is particularly flexible to adapt to different driving situations, and is efficient and highly comfortable to drive. It is also an object of the invention to provide a drive train for an electric or hybrid vehicle with such an advantageous transmission. It is also an object of the invention to provide an advantageous method for operating such a drive train.

This object is achieved by the features given in claim 1, 8 or 9. Advantageous embodiments of the invention are the subject of the dependent claims.

The transmission according to the invention is designed for a drive train of an electric or hybrid vehicle and has a first shaft and a second shaft. The first shaft is connected or connected in a rotationally driving manner to the electric motor. In principle, the first shaft of the transmission can also be formed by the output shaft of the electric machine. The transmission is designed as a two-speed transmission, wherein preferably the transmission has only two gears. The transmission can thus be shifted from a first gear, in which the first shaft is connected or connected in a rotationally driving manner to the second shaft with a first transmission ratio, into a second gear, in which the first shaft is connected or connected in a rotationally driving manner to the second shaft with a second transmission ratio, which is smaller than the first transmission ratio. In the case of the gear ratios described here and below, the first shaft is the drive shaft and the second shaft is the driven shaft. In other words, the engine is operated with a given transmission ratio based on the electric machine mentioned here and below, although the electric machine can also be operated as a generator when the secondary shaft is the drive shaft. In the first gear, the first shaft is connected or can be connected in a rotationally driving manner to the second shaft via a freewheel clutch, and in the second gear, the first shaft is connected or can be connected in a rotationally driving manner to the second shaft via a friction-locking clutch, for example a disk clutch. The freewheel clutch can be, for example, a roller freewheel or a sprag freewheel or a pawl freewheel, wherein a so-called overrunning clutch can also be referred to in the freewheel clutch.

The transmission according to the invention for a drive train of an electric or hybrid vehicle has the advantage that, on the basis of the shiftable transmission, firstly an electric machine of as small a construction as possible can be used. In addition, flexible adaptation to extreme driving situations, such as, for example, starting on a gravel, acceleration, etc., can be achieved by appropriate shifting of the transmission. In particular, the first gear, in which the driving rotary connection is effected via the freewheel clutch, can thereby be used for starting, in particular starting on a rock and for maximum acceleration, wherein a particularly high efficiency of the transmission is achieved in this case. The second gear can be used for the majority of the travel time, wherein the friction-locking clutch, in particular the wet-running diaphragm clutch, meets the high comfort requirements imposed on the drive train of the motor vehicle.

In a preferred embodiment of the transmission according to the invention, the freewheel clutch has a plurality of movable first clamping elements which are arranged between a first running ring (on the one hand) connected in a rotationally fixed manner to the first shaft and a second running ring (on the other hand) connected in a rotationally fixed manner to the second shaft. As mentioned above, the freewheel clutch can be, for example, a roller freewheel, a sprag freewheel or a pawl freewheel. The first running ring need not necessarily be connected in a rotationally fixed manner to the first shaft, but the second running ring likewise need not be connected in a rotationally fixed manner to the second shaft, as will be described below.

In a further preferred embodiment of the transmission according to the invention, the first clamping element of the freewheel clutch is movable from an open position, in which the first running ring is rotatable relative to the second running ring in a first relative rotational direction and in a second relative rotational direction opposite to the first relative rotational direction, into a closed position, in which the first running ring is coupled in a rotationally driving manner in the first relative rotational direction to the second running ring via the first clamping element and is rotatable relative to the second running ring in the second relative rotational direction.

In a further preferred embodiment of the transmission according to the invention, the first clamping element is movable or displaceable into the open position by the first operating ring being rotated in the second relative direction of rotation relative to the second operating direction, so that it does not necessarily have to be moved directly into the open position, but rather must be moved or displaced into the open position when the first operating ring is rotated in the second relative direction of rotation relative to the second operating ring.

As can be seen from the foregoing description, the aforementioned first clamping element in its closed position causes only a rotationally driving coupling between the first operating ring and the second operating ring in the first relative rotational direction. In order to provide a transmission which can be used in a particularly flexible manner and which meets different driving situations of the vehicle, however, in a particularly preferred embodiment of the transmission according to the invention the freewheel clutch further has a plurality of movable second clamping elements which are arranged between the first running ring (on the one hand) and the second running ring (on the other hand), wherein the second clamping elements are movable from an open position, in which the first running ring is rotatable relative to the second running ring in a first relative rotational direction and in a second relative rotational direction, into a closed position, in which the first running ring is rotatable relative to the second running ring in the first relative rotational direction and is coupled in a rotationally driving manner in the second relative rotational direction via the second clamping elements. Thus, by combining the first and second clamping elements, not only can a driving rotational coupling of the running ring in opposite relative rotational directions be achieved, but also a simultaneous coupling or locking of the two opposite relative rotational directions is possible, as a result of which a recovery or setting of the braking torque can be achieved, in particular by the electric machine in the first gear. This also has the advantage that a torque-free reversal from the first gear into the second gear is likewise achieved, as a result of which the comfort and functional range of a drive train having such a transmission is significantly increased.

In an advantageous embodiment of the transmission according to the invention, the at least one first clamping element and the at least one second clamping element can be moved into the respective closed position in a first relative rotational direction and in a second relative rotational direction while achieving a driving rotational coupling between the first shift ring and the second shift ring.

In a particularly advantageous embodiment of the transmission according to the invention, the freewheel clutch is designed as a switchable freewheel clutch. In this embodiment, therefore, corresponding actuating devices are preferably provided for the targeted switching of the freewheel clutch into the different operating modes, without the freewheel clutch reacting only to the rotational speed difference between its operating rings.

In a further advantageous embodiment of the transmission according to the invention, the first clamping element or/and the second clamping element can be locked in the open position or in the closed position, wherein, in addition, in this embodiment, it is preferred that the first clamping element or/and the second clamping element is/are pretensioned into the respectively different position.

In accordance with a further preferred embodiment of the transmission according to the invention, the transmission is configured as a spur gear transmission, so that a particularly safe and reliable transmission of torque is ensured. The first and second shafts are preferably arranged offset parallel to one another.

In accordance with a further preferred embodiment of the transmission according to the invention, a friction-locking clutch is arranged between the spur gear of the transmission and the first shaft or the second shaft. In this embodiment, it is preferred that the spur gear is also mounted rotatably on the first shaft or the second shaft, wherein this can be done, for example, via a rolling bearing.

The two embodiments described above have the advantage that the transmission is particularly compact. In this case, it is preferred that the friction-locking clutch and the freewheel clutch are arranged between their shafts and the respective spur gear, wherein their shafts are preferably formed by a first shaft, which is connected in a rotationally driving manner to the electric machine, even forming its output shaft.

In order to achieve the aforementioned requirements for comfort and utility to a particularly high degree, in a further preferred embodiment of the transmission according to the invention the first transmission ratio is at least 1, wherein the first transmission ratio is preferably greater than 1.3, particularly preferably greater than 1.4, and the second transmission ratio is less than 1, preferably less than 0.9, particularly preferably less than 0.8.

In a further advantageous embodiment of the transmission according to the invention, the friction-locking clutch is a diaphragm clutch, preferably a wet-running diaphragm clutch. In wet-running diaphragm clutches, although the drag torque may occur, the effectiveness may be lower than in friction-locking clutches, such as freewheel clutches, which ensure a high level of driving comfort.

In a further preferred embodiment of the transmission according to the invention, the friction-locking clutch is designed as a normally closed clutch.

The drive train according to the invention for an electric or hybrid vehicle has an electric machine and a transmission of the type described above according to the invention, wherein a first shaft of the transmission is connected in a rotationally driving manner to the electric machine. As mentioned before, the first shaft may equally be the output shaft of the motor. With regard to the advantages of the drive train according to the invention, reference is made to the advantages of the transmission described above, which apply accordingly to the drive train.

In a preferred embodiment of the drive train according to the invention, the drive train further has an internal combustion engine by means of which the second shaft of the transmission can be selectively driven. Thus providing a drive train for a hybrid vehicle.

The method according to the invention for operating a drive train of the type according to the invention has the method steps described in detail below. First, the first shaft is driven by the electric machine during engine operation, wherein the second shaft is driven by the first shaft via the freewheel clutch in the first gear of the transmission. In this case, the drive is therefore preferably effected via the clamping element of the freewheel clutch in its closed position. During the driving of the first shaft and the second shaft in the first gear, the friction clutch is first disengaged. If a certain type of situation is implemented, for example, a start or a sudden acceleration on a broken rock, the clutch is switched into the second gear by closing the friction clutch while the freewheel clutch is overrun, so that the torque is transmitted in the second gear by the second slip ring of the freewheel clutch over the first slip ring via the friction clutch. The transition from the switched freewheel clutch and thus from the first gear into the higher second gear is thus gradual. The aforementioned overrunning of the freewheel clutch is preferably performed here in the movement or displacement of the first clamping element into the open position, as described above with reference to the transmission. In addition, in this embodiment it is preferred that the first clamping element is locked in the open position after its movement or displacement into the open position, so that an unwanted movement of the first clamping element is suppressed in the second gear during driving.

In a preferred embodiment of the method according to the invention, after shifting into the second gear, the first gear is shifted back into the first gear by opening the friction clutch and the first clamping element is moved from the open position into the closed position. The first clamping element is preferably moved from the open position into the closed position by releasing the aforementioned locking of the first clamping element in its open position.

In a further preferred embodiment of the method according to the invention, the friction-locking clutch is disengaged by driving the electric machine via the first shaft in generator mode and by driving the first shaft in the first gear of the transmission via the freewheel clutch via the second shaft. In this case, in a first gear of the transmission, the first shaft is driven by the second shaft in its closed position via a freewheel clutch, preferably via a second clamping element of the freewheel clutch. In a further method step, the second shaft is braked, preferably by means of an existing motor vehicle brake in the motor vehicle. The shift into the second gear is then carried out, wherein this is done by releasing the freewheel clutch, preferably by moving the second clamping element into its open position, wherein the friction-locking clutch is then closed, so that the shifting process into the second gear is ended.

In a further advantageous embodiment of the method according to the invention, the second shaft is switched back into the first gear by braking, preferably with a motor vehicle brake, the freewheel clutch is closed, preferably the second clamping element is moved into its closed position, and the friction clutch is then disengaged.

Drawings

The invention is explained below with reference to the figures according to exemplary embodiments.

FIG. 1 shows a schematic diagram and a schematic representation of an embodiment of a drive train for an electric or hybrid vehicle

Fig. 1 to 5 show partial schematic views of the switchable freewheel clutch from fig. 1 in different positions or switching states.

Detailed Description

Fig. 1 shows a schematic representation of a drive train 2 for an electric or hybrid vehicle. The drive train 2 has an electric machine 4 which can be operated as a drive or as an engine in engine operation and as a generator in generator operation. Following the electric motor 4 is a transmission 6, which is designed as a spur gear transmission.

The transmission 6 has a first shaft 8 and a second shaft 10 arranged parallel to the first shaft 8, but non-coaxially therewith. Within the drive train for a hybrid vehicle, the second shaft 10 can be connected in a rotationally driving manner, for example, to an internal combustion engine, not shown in detail. A first shaft 8 of the transmission 6 is connected in a driving train 2 in a rotationally driving manner to the electric machine 4. In particular, the first shaft 8 is connected in a rotationally driving manner to an output or input side 12 of the electric machine 4, wherein the first shaft 8 can likewise be formed by the output or input side 12 of the electric machine 4.

The transmission can be shifted from the first gear 14 to the second gear 16 and vice versa, wherein, for operation in the first gear 14, a first gear stage consisting of two

gearwheels

18, 20 engaging one another is provided and, for operation in the second gear 16, a second gear stage with

gearwheels

22, 24 engaging one another is provided. In the case of the transmission 6 shown here in the form of a spur gear transmission, the gears 18 to 24 can accordingly also be referred to as spur gears. The two

toothed wheels

20, 24 are fixed in a rotationally fixed manner and are supported on the second shaft 10, and the two

toothed wheels

18, 22 are each mounted rotatably on the first shaft 8, wherein this can take place, for example, via schematically illustrated rolling

bearings

26, 28.

Although the

gear wheels

18, 22 of the first and second gear stages are rotatably mounted on the first shaft, a torque transmission between the first shaft 8 and the second shaft 10 can be achieved via these gear stages, i.e. the first shaft 8 is connected or can be connected in a rotationally driving manner to the second shaft 10 in the first gear via a freewheel clutch 30 and in the second gear 16 via a friction-locking clutch 32. In particular, a switchable friction clutch 32 is arranged between the gear wheel 22 of the transmission 6 and the first shaft 8, while a freewheel clutch 30, which is likewise designed to be switchable, is arranged between the gear wheel 18 of the transmission 6 and the first shaft 8.

If gear 18 is the drive gear, gear 18 and gear 20 form a first gear ratio. Further, if gear 22 is a drive gear, gear 22 and gear 24 form a second gear ratio, wherein the second gear ratio is less than the first gear ratio. The transmission 6 can thus be shifted from the first gear 14, in which the first shaft 8 is connected or connected in a rotationally driving manner with a first transmission ratio via the

gears

18, 20 to the second shaft, into the second gear 16, in which the first shaft 8 is connected or connected in a rotationally driving manner with a second transmission ratio via the

gears

22, 24 to the second shaft. It has been found to be advantageous here if the first transmission ratio is at least 1, wherein the first transmission ratio is preferably greater than 1.3, particularly preferably greater than 1.4, so that a slow transmission is achieved. And the second transmission ratio is advantageously less than 1, so that the second gear 16 is a fast transmission. In this case, the second transmission ratio is preferably less than 0.9, particularly preferably less than 0.8.

The friction clutch 32 mentioned above is designed as a wet-running diaphragm clutch. The wet-running diaphragm clutch 32 thus has a first side 34 connected in a rotationally driving manner to the first shaft 8 and a second side 36 connected in a rotationally driving manner to the gearwheel 22, which first and second sides can be coupled in a rotationally driving manner via a pressed-together lining set 38, wherein for the sake of clarity corresponding actuating devices for the lining set 38 are not shown. In addition, the friction clutch 32 is designed as a normally closed clutch, so that the disk set 38 is pressed together in the illustrated embodiment with the two

sides

34, 36 coupled, in which case the friction clutch 32 is not specifically actuated and disengaged. The pretensioning into the closed state can be achieved, for example, by a spring device, which is not shown in detail.

The freewheel clutch shown in detail and partially in fig. 2 to 5 has a first running ring 40 and a second running ring 42, which extend in the

circumferential direction

44, 46, wherein the first running ring 40 is connected in a rotationally fixed manner to the first shaft 8, and the second running ring 42 is connected in a rotationally fixed manner to the gearwheel 18 and thus via the

gearwheels

18 and 20 to the second shaft 10. Between the two running

rings

40, 42, in mutually opposite

radial directions

48, 50, a receptacle is formed, in which a plurality of movable first clamping elements 52 and a plurality of movable second clamping elements 54 are arranged. In this case, the clamping

elements

52, 54 of the freewheel clutch 30 are alternately connected to one another in the

circumferential direction

44, 46.

The first clamping element can be moved or pivoted from an open position, illustrated in fig. 4, in which the first running ring 40 can be rotated relative to the second running ring 42 in a first relative rotational direction 56 and in a second relative rotational direction 58 opposite the first relative rotational direction 56, into a closed position, illustrated in fig. 2, 3 and 5, in which the first running ring 40 is coupled in a rotationally driving manner in the first relative rotational direction 56 to the second running ring 42 via the first clamping element 52 and can be rotated relative to the second running ring 42 in the second relative rotational direction 58. In this case, the first clamping element 52 is preferably moved or displaced by rotating the first operating ring 40 relative to the second operating ring 42 in the second relative direction of rotation 58, in this case being pivoted into the open position. The second clamping element 54 is movable from an open position, which is illustrated in fig. 2 and 3 and in which the first running ring 40 is rotatable relative to the second running ring 42 in a first relative direction of rotation 56 and a second relative direction of rotation 58, into a closed position, which is illustrated in fig. 4 and 5 and in which the first running ring 40 is rotatable relative to the second running ring 42 in the first relative direction of rotation 56 and is coupled in a rotationally driving manner in the second relative direction of rotation 58 with the second running ring 42 via the second clamping element 54.

However, due to the combination of the first clamping element 52 and the second clamping element 54 shown here, not only can two shift states of the freewheel clutch 30 be realized. Instead, the at least one first and the at least one second clamping element can be moved into the respective closed position in a first and a second relative direction of

rotation

56, 58, while the driving rotational coupling between the first and the

second operating ring

40, 42 is achieved, as is shown in fig. 5.

As already indicated, the freewheel clutch 30 is designed as a switchable freewheel clutch 30, wherein the corresponding actuating device for actuating the clamping

element

52 or 54 is not shown for the sake of clarity. It is also preferred that the first clamping element 52 or/and the second clamping element 54 can be locked in the open position or in the closed position, preferably in the open position, so that the movability or the pendability of the clamping

elements

52 or 54 can be limited or suppressed by the locking. It is also preferred that the clamping elements 52 and/or 54 are pretensioned into another position, wherein this can be achieved, for example, by means of spring elements. In this case, it is also preferred that the first clamping element 52 and/or the second clamping element 54 are prestressed into the closed position.

Further features of the drive train 2 or the transmission 6 are explained below with reference to fig. 1 to 5, depending on the method for operating the drive train 2.

In a first method step, the electric machine 4 is operated as a motor, so that it drives the first shaft 8 via the input side or output side 12. The friction clutch 32 is disengaged, while the second shaft 10 is driven by the first shaft 8 in the first gear 14 via the freewheel clutch 30 or its first clamping element in the closed position and the

gears

18 and 20 are driven. This switching state of the transmission 6 is suitable, for example, for the case of a motor vehicle start on a gravel load, an emergency acceleration, etc. Fig. 2 shows the respective switching states of the clamping

elements

52, 54. Thus, the first clamping member 52 is in the closed position, while the second clamping member 54 is in the open position.

When driving is continued, the gear is then shifted into the second gear 16, this being done by closing the friction clutch 32. The second shaft 10 is thereby driven via the first shaft 8, the friction-locking clutch 32, the gear 22 and the gear 24, so that the freewheel clutch is thereby overrun. Specifically, the second operating ring 42 is driven by the second shaft 10 via the

gears

20 and 18 in such a way that the second operating ring 42 passes beyond the first operating ring 40 in a first relative rotational direction 56, wherein the first clamping element 52 is thereby moved or displaced into the open position by means of the corresponding contour of the first operating ring 40 shown in the figures, as shown in fig. 3. As previously described, the first clamping element 52 can then be locked in its open position.

Since the second shaft 10 is now driven via the friction clutch 32, the transmission meets higher comfort requirements, even if the efficiency is reduced, for example, due to the drag torque occurring in the friction clutch 32. The transition from the first gear 14 to the second gear 16 by the aforementioned overrun of the freewheel clutch 30 takes place very gently and smoothly. Overall, a transmission 6 is thus provided which can be used in a particularly flexible manner in various driving situations and which, on the basis of the switchability, allows a small-sized electric machine.

Furthermore, it is also possible to switch back from the second gear into the first gear, wherein this can be done by simply opening the friction clutch 32 and moving the first clamping element 52 from the open position into the closed position according to fig. 2. If the clamping elements 52 are locked in the open position and pretensioned into the closed position, they can be returned into the closed position simply by releasing the locking of the first clamping element 52.

The drive train 2 or the transmission also has the aforementioned advantages when the drive train 2 with the electric machine 4 as a generator is operated. The electric machine 4 can thus be driven via the first shaft 8 in generator mode, while the first shaft 8 is driven via the second shaft 10 in the first gear 14 of the transmission via the freewheel clutch 30. In this case, the second clamping element 54 is pivoted into its closed position, while the first clamping element 52 can be set and locked in the open position, as shown in fig. 4. And the friction-locking clutch 32 is disengaged. In order to be able to shift into the second gear position 16, the second shaft 10 is first braked, which can be done, for example, by means of a motor vehicle brake, so that the second clamping element 54, which is subjected to force loading by the first operating ring 40 and the second operating ring 42, is released from the clamping state in the closed position, and then the freewheel clutch 14 is opened by moving the second clamping element 54 back into its open position, wherein the friction-locking clutch 32 is then closed, so that the shifting operation is locked in the second gear position.

In generator mode of the electric machine 4, the transmission 6 can again be switched from the second gear back into the first gear, preferably first of all by means of the motor vehicle brake by braking the second shaft, so that when the second clamping element is pivoted into the closed position, the operating

ring

40 or 42 is prevented from excessively striking the second clamping element 54. The pivoting of the first clamping element 52 into its closed position helps to synchronize the rotational speeds of the first and second running rings 40, 42, as shown in fig. 5. If the second shaft 10 is braked in the manner described above, the freewheel clutch 30 is closed by the second clamping element 54 moving into the closed position according to fig. 4 and then the friction clutch 32 is opened.

The shift state of the freewheel clutch 30 shown in fig. 5, in which the first and

second clamping elements

52, 54 are arranged in their closed position, completely locks the two shift rings 40, 42 against one another in opposite relative

rotational directions

56, 58.

List of reference numerals

2 drive train

4 electric machine

6 speed variator

8 first shaft

10 second axis

12 output/input side

14 first gear

16 second gear

18 gears

20 gears

22 gear

24 gear

26 rolling bearing

28 rolling bearing

30 freewheel clutch

32 friction lock clutch

34 first side

36 second side

38 facing set

40 first run ring

42 second operating ring

44 circumferential direction

46 circumferential direction

48 radial direction

50 radial direction

52 first clamping element

54 second clamping element

56 first relative rotational direction

58 second relative direction of rotation

Claims

1. A transmission (6) for a drive train (2) of an electric or hybrid vehicle, having a first shaft (8) which is connected in a rotationally driving manner to an electric machine (4) and a second shaft (10), wherein the transmission (6) can be switched from a first gear (14), in which the first shaft (8) is connected in a rotationally driving manner or in a rotationally driving manner to the second shaft (10) with a first transmission ratio, into a second gear (16), in which the first shaft (8) is connected in a rotationally driving manner or in a rotationally driving manner to the second shaft (10) with a second transmission ratio which is smaller than the first transmission ratio, characterized in that the first shaft (8) is connected in the first gear (14) to the second shaft (10) via a freewheel clutch (30) and in the second gear (16) via a friction-locking clutch (32) Is connected or can be connected in a driving and rotating manner.

2. Transmission (6) according to claim 1, characterized in that the freewheel clutch (30) has a plurality of movable first clamping elements (52) which are arranged between a first running ring (40) connected in a rotationally fixed manner to the first shaft (8) and a second running ring (42) connected in a rotationally fixed manner to the second shaft (10), wherein preferably the first clamping elements (52) are movable from an open position, in which the first running ring (40) is rotatable relative to the second running ring (42) in a first relative rotational direction (56) and a second relative rotational direction (58) opposite to the first relative rotational direction (56), into a closed position, in which the first running ring (40) is coupled in a rotationally fixed manner in the first relative rotational direction (56) with the second running ring (42) via the first clamping elements (52) and the second running ring (42), and a closed position And can be rotated in the second relative direction of rotation (58) relative to the second running ring (42), wherein the first clamping element (52) is particularly preferably movable or displaceable into the open position by the first running ring (40) being rotated in the second relative direction of rotation (58) relative to the second running ring (42).

3. Transmission (6) according to claim 2, characterized in that the freewheel clutch (30) has a plurality of movable second clamping elements (54) which are arranged between the first running ring (40) and the second running ring (42), wherein the second clamping elements (54) are movable from an open position, in which the first running ring (40) is rotatable relative to the second running ring (42) in a first relative rotational direction (56) and in a second relative rotational direction (58), into a closed position, in which the first running ring (40) is rotatable relative to the second running ring (42) in the first relative rotational direction (56) and is coupled in a rotationally driving manner in the second relative rotational direction (54) with the second running ring (42) via the second clamping elements (54), wherein at least one first clamping element (52) and at least one second clamping element (54) can be moved into a respective closed position in the first relative direction of rotation (56) and in the second relative direction of rotation (58) while a rotationally driving coupling between the first running ring (40) and the second running ring (42) is achieved.

4. Transmission (6) according to one of the preceding claims, characterized in that the freewheel clutch (30) is configured as a switchable freewheel clutch (30), wherein the first clamping element (52) or/and the second clamping element (54) can preferably be locked in the open or closed position, particularly preferably pretensioned into different positions.

5. Transmission (6) according to one of the preceding claims, characterized in that the transmission (6) is configured as a spur gear transmission, wherein preferably a friction-locking clutch (32) is arranged between a spur gear of the transmission (6) and the first shaft (8) or the second shaft (10), particularly preferably the spur gear (22) is rotatably supported on the first shaft or the second shaft, if necessary via a rolling bearing (28), or/and the freewheel clutch (30) is preferably arranged between a spur gear (18) of the transmission (6) and the first shaft (8) or the second shaft (10), particularly preferably the spur gear (18) is rotatably supported on the first shaft or the second shaft, if necessary via a rolling bearing (26).

6. Transmission (6) according to any of the preceding claims, characterized in that the first transmission ratio is at least 1, preferably greater than 1.3, particularly preferably greater than 1.4, and the second transmission ratio is less than 1, preferably less than 0.9, particularly preferably less than 0.8.

7. Transmission (6) according to one of the preceding claims, characterized in that the friction-locking clutch (32) is a diaphragm clutch, preferably a wet-running diaphragm clutch, or/and a normally closed clutch.

8. Drive train (2) for an electric or hybrid vehicle, having an electric machine (4) and a transmission (6) according to one of the preceding claims, the first shaft of which is connected in a rotationally driving manner to the electric machine (4), wherein an internal combustion engine is preferably also provided, by means of which the second shaft (10) can be optionally driven.

9. Method for operating a drive train (2) according to claim 8, having the following method steps:

in engine operation, the first shaft (8) is driven by the electric machine (4), and in a first gear (14) of the transmission (6), the second shaft (10) is driven by the first shaft (8) in the closed position via the freewheel clutch (30), preferably via the first clamping element (52), the friction-locking clutch (32) is disengaged, and

the friction clutch (32) is switched into the second gear (16) by closing the friction clutch while the freewheel clutch (30) is being overrun, preferably while the first clamping element (52) is moved or displaced into the open position, particularly preferably while the first clamping element (52) is locked in the open position, and

In particular, the friction clutch (32) is preferably switched back into the first gear (14) by opening and the first clamping element (52) is moved from the open position into the closed position, preferably by releasing the locking of the first clamping element (52) in its open position.

10. Method for operating a drive train (2) according to claim 8, having the following method steps:

in generator operation, the electric machine (4) is driven via the first shaft (8) and in a first gear (14) of the transmission, the first shaft (8) is driven in the closed position by the second shaft (10) via the freewheel clutch (30), preferably via the second clamping element (54), the friction-locking clutch (32) is disengaged,

preferably braking the second shaft (10) by means of a motor vehicle brake,

switching into the second gear (16) by releasing the freewheel clutch (30), preferably by moving the second clamping element (54) into its open position, and then closing the friction-locking clutch (32),

particularly preferably, the second shaft (10) is switched back into the first gear (14) by braking, preferably with a motor vehicle brake, the freewheel clutch (30) is closed, preferably the second clamping element (54) is moved into its closed position, and the friction-locking clutch (32) is then opened.