CN115214354A

CN115214354A - Switching unit and drive unit for a drive train of a motor vehicle, and axle module

Info

Publication number: CN115214354A
Application number: CN202110960583.2A
Authority: CN
Inventors: 帕特里克·费舍尔
Original assignee: Hoerbiger Antriebstechnik Holding GmbH
Current assignee: Hoerbiger Antriebstechnik Holding GmbH
Priority date: 2021-04-16
Filing date: 2021-08-20
Publication date: 2022-10-21
Also published as: DE102021109712A1

Abstract

The invention relates to a switching unit (16) for an electrified drive train of a motor vehicle, comprising an input shaft (30), an output shaft (32) and a switching element (34) which is arranged at least partially in a housing (36). The shift element (34) couples the input shaft (30) to the output shaft (32) in a torque-transmitting manner in a first shift position. The switching element (34) rotationally couples the output shaft (32) with the housing (36) in a second switching position. Furthermore, a drive unit (12) for an electrified drive train of a motor vehicle is described, which drive unit comprises an electric drive machine (14) and such a switching unit (16). An axle module (10) for a motor vehicle is also presented, which is equipped with such a drive unit (12).

Description

Switching unit and drive unit for a drive train of a motor vehicle, and axle module

Technical Field

The invention relates to a switching unit for an electrified drive train of a motor vehicle, having an input shaft which can be coupled to an electric drive machine and an output shaft on which a drive torque can be provided and/or a regenerative torque can be received. Furthermore, a switching element is provided, which is at least partially arranged in the housing.

The invention also relates to a drive unit for an electrified drive train of a motor vehicle, having an electric drive machine and such a switching unit, wherein the electric drive machine is coupled to the input shaft in a torque-transmitting manner.

The invention further relates to an axle module for a motor vehicle, comprising such a drive unit. The output shaft of the switching unit forms a wheel output shaft or is coupled to at least one wheel output shaft in a torque-transmitting manner. In particular, the output shaft is coupled in a torque-transmitting manner with two wheel driven shafts arranged on opposite sides of the axle module.

Background

Such a switching unit and a drive unit and axle module equipped therewith are known from the prior art. The electric drive can generally be operated here not only as an engine but also as a generator.

In the sense of a simple explanation, the following is intended to be a standard case for a drive machine used as an engine. The components of the electrified powertrain system are therefore named at least partially for their function in standard situations, for example as input or output shafts. This does not however exclude: the electric drive machine may also be used as a generator for regeneration.

It is also known that: a transmission is provided in an electrified powertrain system of a motor vehicle. Such a transmission can have a switching unit in the form of a clutch or a brake. In particular in connection with automated or semi-automated switchable gear trains, a switching unit can also be provided in the drive train, which switching unit is designed as a parking lock.

Any type of switching unit should generally be simple and compact in construction. The same applies to drive units and axle modules equipped with switching units. In this way, an electrified drive train for a motor vehicle with an equally simple and compact structure is to be provided.

Disclosure of Invention

The invention aims to: the known switching unit is further improved. In particular, a switching unit of compact design should be realized.

The object is achieved by a switching unit of the type mentioned at the outset in which the switching element couples the input shaft to the output shaft in a torque-transmitting manner in a first switching position and rotationally couples the output shaft to the housing in a second switching position. It is clear here that: in the first switching position, neither the input shaft nor the output shaft is coupled with the housing. The first switching position is therefore used in particular to drive the output shaft by means of the input shaft. Correspondingly, in the second switching position, the input shaft is disconnected from the output shaft. Therefore, in the second switching position, the switching unit may function as a parking lock mechanism or a brake for the output shaft. The switching unit according to the invention fulfills both the function of a clutch and the function of a parking lock or brake. The switching unit according to the invention can thus replace the clutch and the parking lock mechanism compared to known electrified drive train systems and switching units thereof. The switching unit is of compact design, taking into account its functional range, in particular is more compact overall than the known clutch and the known parking lock. Due to the functional integration, the switching unit according to the invention also enables a simplified construction of the electrified drive train system. Furthermore, the switching unit according to the invention is cost-effective.

The above-described coupling between the input shaft, the output shaft and/or the housing can take place directly, i.e. without intermediate pieces, or indirectly, i.e. via intermediate elements, such as additional shafts and/or gear stages (Zahnradstufen). The switching unit can thus be variably adapted to the predetermined application.

The shift element can couple the input shaft to the output shaft in the first shift position by means of a form fit and/or by means of a friction fit. A reliable coupling of the input shaft to the output shaft is thus always obtained.

Likewise, the shift element can rotationally couple the output shaft to the housing in the second shift position via a form-fit and/or via a friction-fit. The output shaft is thus coupled in rotation with the housing in a reliable manner.

For example, the switching elements comprise dog clutches, cone clutches and/or synchronizing units. It is also possible that: the shift element is designed as a shiftable one-way clutch. Such switching elements are known per se and will therefore not be described further. Since the electric drive can be used to compensate for a possible rotational speed difference between the input shaft and the output shaft when shifting into the first shift position, i.e. to synchronize the input shaft and the output shaft, the use of form-locking shift elements such as dog clutches or dog clutches is entirely possible in the shift unit according to the invention. For this purpose, the electric drive is actuated, for example, by means of pulse width modulation. This simplifies the engagement of the form-locking shift element.

According to one embodiment, the switching element disconnects the input shaft from the output shaft and disconnects the output shaft from the housing in the third switching position. Therefore, such a switching position may also be referred to as a neutral position. Since the output shaft can rotate independently of the input shaft in this case, the third shift position is particularly suitable for achieving what is known as coasting of the electric drive train. In this operating state, the wheels of the motor vehicle are neither actively driven nor provide regenerative torque. There is also a lower drag torque loss due to the possibility of non-rotation of the electric drive coupled with the input shaft in the third switching position. This is particularly advantageous when the input shaft is coupled to a permanently excited synchronous machine.

In one variant, the switching element is biased into one of the switching positions, in particular by means of a spring. Depending on the actuation scheme of the switching element, a switching position can be determined which, without external influences, should always be reliably assumed. The switching unit can thus be operated safely. In particular, the switching element is pretensioned into the second switching position. In the absence of external influences, in particular in the absence of actuation, the output shaft is always coupled in rotation with the housing, so that the associated drive train is braked or blocked.

In the case of a switching unit serving as a parking lock and a switching element designed as a dog clutch, good release behavior can also be ensured in the following manner: dog clutches are designed with either a downwardly pointing side (abweissenden Flanken) or a side with a small side reentrant angle (hindregungswinkel). In this way, the level of force required for releasing can be kept low even when the switching unit is used in a vehicle standing on a slope, in which vehicle a large force acts on the switching element due to the slope.

The spring may be a bistable spring. In this configuration, the switching element can be switched back and forth between the two switching positions with a small force.

The switching unit may also comprise a variable transmission mechanism which is located in the power flow between the input shaft and the output shaft. A variable speed transmission is to be understood here as any transmission providing variable speed. The size of the associated transmission ratio is not critical here, so that a variable-speed transmission is also understood as a transmission that provides a reduction. Preferably, the speed change transmission is a gear transmission. However, it is of course also possible: the variable speed drive is a belt drive. In particular, a variable speed drive is used to convert rotational speed and torque. The switching unit can be adapted to different applications by means of a gear change transmission.

In this case, the shift element can couple the input shaft in a torque-transmitting manner with the output shaft via at least one intermediate gear shaft in the first shift position. The shift element can be located in the power flow between the input shaft and the transmission countershaft or between the transmission countershaft and the output shaft. It is also possible that: at least two transmission countershafts are provided, and the shift element is located in the power flow between the two transmission countershafts. The shift unit can also be configured for different applications via the countershaft of the gear mechanism.

In addition, the shift element can rotationally couple the output shaft with the housing via at least one transmission intermediate shaft in the second shift position. In this case, the shift element can also be arranged between the output shaft and the transmission countershaft or between the housing and the transmission countershaft. In the case of two or more transmission countershafts, the rotary coupling can also be realized via a shift element arranged between the two transmission countershafts. As already explained, the switching unit can thus be adapted to different application scenarios.

In all embodiments in which the shift unit comprises a change speed transmission, it is to be noted that the position of the shift element within or relative to the change speed transmission may have a large influence on its design and operation. The shift element arranged at the output side of the manual transmission can in this case be designed to be relatively robust in order to be able to receive the forces and torques present there. Correspondingly, a large force is required to switch the switching element. This is particularly true when the switching unit is used as a parking lock mechanism and the vehicle mounted with the parking lock mechanism is stopped on a slope. In contrast, the shift element arranged on the drive side on the transmission can be designed more compactly and can thus also be shifted with less force.

In particular, when the switching unit can be used as a parking lock mechanism, it is advantageous that: the switching element is arranged on the drive side on the gear mechanism. This results in the following: only a small torque needs to be supported. This is particularly true in comparison to the arrangement on the driven side or on the axle drive. This can improve the engagement and disengagement properties, since a reduced force level is also required for this purpose. Since shorter shafts are usually used in transmissions for electrically driven vehicles, these shafts are also twisted only slightly. Furthermore, in such applications, there are typically fewer gear stages engaged, and thus less torsion between the drive and driven ends of the variable speed drive as a whole. For these reasons, the lock safety can be ensured at a known high level by the switching unit serving as the parking lock mechanism, the switching element of which is provided on the transmission on the drive side.

Furthermore, it can be provided that: the shift element couples the input shaft in a torque-transmitting manner with the output shaft via a first power path of the transmission in the first shift position. In short, the first power path is the first gear of the variable transmission. The shift element is therefore used to engage such a gear.

Alternatively or additionally it is possible: the shift element couples the input shaft in a torque-transmitting manner with the output shaft via the second power path of the transmission in the fourth shift position. The second power path is at least partially separated from the first power path. The designation of the switching position as "fourth" is for simplicity of explanation only. The number of switching positions is not implied thereby. In particular, the switching unit can be designed in such a case that there is no third switching position. The second power path can be used to provide a different transmission ratio than the first power path, in that the second power path is at least partially separated from the first power path. In short, the second power path is a second "gear" of the variable speed transmission, and the shift element is used to selectively engage that gear.

In a further variant, the switching unit comprises a locking mechanism which is configured to prevent a switching movement of the switching element. In particular, the locking mechanism operates according to the operating parameters of the switching unit. For example, the operating parameter is the rotational speed of the output shaft or the rotational speed of the input shaft. In an exemplary embodiment, the second shift position can be assumed here only when the output shaft has a rotational speed which is below a predetermined limit rotational speed. This prevents: the parking lock mechanism or brake is engaged when the rotational speed of the output shaft is too high. In summary, it can thus be ensured by means of the locking mechanism that a switching movement of the switching element is only carried out if this switching movement is also desired and/or meaningful in view of the operating parameters of the switching unit. This achieves a high functional safety and favorable wear behavior of the switching unit.

A synchronization unit for reducing the difference in rotational speed between the components to be coupled by means of the shift element may also be provided. The components to be coupled here relate in particular to the input shaft, the output shaft, the transmission intermediate shaft which may be present, and the housing. In this case, the synchronizing unit comprises a friction system which is comparable to the friction system of the synchronizing unit for synchronously switching the gear. In particular, the rotational speeds of the input shaft and the output shaft can thus be matched before the first switching position is occupied. In the same way, the rotational speed of the output shaft can be braked to zero before the second switching position is occupied and the output shaft is rotationally coupled with the housing. In the case of the presence of an intermediate shaft of the gear mechanism, the rotational speed of the intermediate shaft can be adapted in a corresponding manner to the rotational speed of the input shaft or the output shaft. Such a switching unit works reliably and firmly. In particular, the switching unit can also be operated reliably when there is a difference in rotational speed.

The object of the invention is furthermore achieved by a drive unit of the initially mentioned type, which comprises a switching unit according to the invention. In view of the predetermined functional range, such a drive unit is constructed compactly. As already explained, the switching unit according to the invention can be substituted for a plurality of known switching units. The associated drive unit is thus also of simple and cost-effective design.

The object of the invention is also achieved by an axle module of the type mentioned at the outset having a drive unit according to the invention. The axle module is also of simple and compact design due to the simple, compact and cost-effective design of the drive unit. Furthermore, such an axle module can be produced cost-effectively.

Furthermore, the effects and advantages described with reference to the switching unit according to the invention also apply to the drive unit according to the invention and to the axle module according to the invention or vice versa.

Drawings

The invention is explained below with the aid of different embodiments shown in the drawings. In the drawings:

fig. 1 shows an axle module according to the invention with a drive unit according to the invention comprising a switching unit according to a first embodiment of the invention, wherein the switching element of the switching unit is located in a first switching position;

fig. 2 shows the axle module of fig. 1, with the switching elements of the switching unit in a second switching position;

fig. 3 shows the axle module of fig. 1 and 2, wherein the switching elements of the switching unit are in a third switching position;

fig. 4 shows an axle module according to the invention with a drive unit according to the invention comprising a switching unit according to a second embodiment of the invention;

fig. 5 shows an axle module according to the invention with a drive unit according to the invention comprising a switching unit according to a third embodiment of the invention, wherein the switching element of the switching unit is in a first switching position;

fig. 6 shows the axle module of fig. 5 with the switching elements of the switching unit in a second switching position;

fig. 7 shows the axle module of fig. 5 and 6, with the switching elements of the switching unit in a third switching position;

fig. 8 shows the axle module of fig. 5 to 7, with the switching element of the switching unit in a fourth switching position.

Detailed Description

Fig. 1 shows an axle module 10 for a motor vehicle.

The axle module 10 has a drive unit 12, which is formed primarily from an electric drive machine 14 and a switching unit 16.

The drive unit 12 acts on a first wheel output shaft 22 and a second wheel output shaft 24 via the transmission 18 and the differential 20.

Here, the wheel driven

shafts

22, 24 are arranged on opposite sides of the axle module 10.

In addition, a first wheel 26 is mounted on the first wheel driven axle 22, and a second wheel 28 is mounted on the second wheel driven axle 24.

Specifically, the electric drive machine 14 is coupled in torque transmitting fashion with an input shaft 30 of the switching unit 16.

The output shaft 32 of the switching unit 16 simultaneously forms the input shaft of the change gear mechanism 18. The output shaft 32 is thus coupled in a torque-transmitting manner to the two driven

wheel shafts

22, 24 and the

wheels

26, 28 as a whole.

In this case, the electric drive machine 14 may function as an engine or a generator.

The output shaft 32 can be supplied with a drive torque generated by the electric drive machine 14 or can receive a regenerative torque, which is generated by the rotational movement of the

wheels

26, 28.

Furthermore, the switching unit 16 comprises a switching element 34, which is shown in the illustration according to fig. 1 in a first switching position.

The switching element 34 comprises a bearing part 34a, which can also be referred to as a hub part and is connected to the output shaft 32 in a rotationally fixed manner.

Furthermore, a sliding part 34b is provided, which is designed, for example, as a sliding sleeve.

The slide member 34b is supported on the support member 34a so as to be relatively non-rotatable but axially movable.

The switching element 34 further includes a first clutch device 34c and a second clutch device 34d, which are respectively provided on axially opposite sides of the sliding member 34 b.

The shift element 34 couples the input shaft to the output shaft in a torque-transmitting manner in the first shift position.

For this purpose, the sliding member 34b is moved relative to the support member 34a as follows: so that the first clutch element 34c is rotationally coupled with the clutch element 30a of the input shaft 30.

Said movement takes place against the force of a spring 35 which pretensions the sliding part 34b into a position corresponding to the second switching position, which will be explained below.

Actuators for moving such sliding members 34b are well known and are therefore not shown for better clarity.

When the electric drive machine is used as an engine, the

wheels

26, 28 can be driven in this switching position by means of the electric drive machine 14.

On the other hand, the electric drive machine may receive regenerative torque generated by the rotational motion of the

wheels

26, 28.

The switching element 34 can also assume a second switching position, which is shown in fig. 2.

In the switching position, the switching element 34 rotationally couples the output shaft 32 with the housing 36, in which the switching element 34 is at least partially disposed.

In the illustrated embodiment, the housing 36 is fixed in space, and thus the output shaft 32 is fixed to the housing 36 and does not rotate.

For this purpose, the sliding member 34b is moved relative to the support member 34a in such a way that the second clutch element 34d is rotatably coupled to the clutch element 36a of the housing 36.

The wheel driven

axles

22, 24 and the

wheels

26, 28 are correspondingly prevented from rotating.

In other words, in the second switching position, the

wheels

26, 28 are braked or jammed. The switching unit 16 thus functions as a parking lock mechanism.

The first clutch element 34c is disconnected from the clutch element 30a of the input shaft 30.

Due to the pretensioning of the sliding part 34b by means of the spring 35, no actuator is required for moving into the second switching position.

The switching element 34 can also assume a third switching position, which is shown in fig. 3.

In this switching position, not only the input shaft 30 is disconnected from the output shaft 32, but also the output shaft 32 is disconnected from the housing 36.

Thus, the output shaft 32 can rotate without the input shaft 30 rotating therein.

The third switching position may therefore be referred to as neutral position and is particularly suitable for so-called coasting, i.e. the

wheels

26, 28 may turn with less resistance if they are not supplied with driving torque or if they do not provide regenerative torque.

In the embodiment shown in fig. 1 to 3, the shift element 34 is designed as a double-acting dog clutch element.

The

clutch elements

30a, 34c, 34d and 36a thus each comprise a claw, wherein the claw of the clutch element 34c can selectively interact with the claw of the clutch element 30a, and the claw of the clutch element 34d selectively interacts with the claw of the clutch element 36a.

In order to make the engagement of the clutch element 34c in the clutch element 30a easier, the drive machine 14 can be actuated in such a way that the

clutch elements

34c, 30a engage one another appropriately substantially without a rotational speed difference and/or with a rotational angle.

Alternatively, it is of course also possible: the switching element 34 is designed as a two-sided synchronization unit.

The

clutch elements

34c and 34d then each comprise a friction unit, which is equipped with at least one friction ring, and a form-locking element.

Furthermore, each of the

clutches

34c, 34d is provided with a locking mechanism which comprises in particular a locking ring and is designed such that the coupling via the form-locking element can only be achieved if the difference in rotational speed between the output shaft 32 and the input shaft 30 or between the output shaft 32 and the housing 36 is below a predetermined limit value.

In this case, the clutch element 30a comprises at least one friction engagement surface, which can be brought into frictional contact with the friction ring, and a form-locking engagement element.

Clutch 36a also has a friction engagement surface configured to interact with the friction ring. The clutch element 36a likewise comprises a form-fitting element.

When the shift element 34 is to be transferred from the third shift position (see fig. 3) into the first shift position, a rotational speed difference that may exist between the output shaft 32 and the input shaft 30 is first reduced or eliminated by means of the friction unit of the clutch element 34 c. To this end, the friction ring of clutch element 34c is in contact with the friction engagement surface of clutch element 30 a. In other words, the output shaft 32 and the input shaft 30 are first coupled via a friction lock.

When the rotational speed difference is below the predetermined limit value, the form-fitting element of the clutch means 34c engages in the form-fitting element of the clutch means 30 a. The output shaft 32 is then coupled with the input shaft 30 via a form-fit.

The friction unit of the clutch element 34c may also be referred to as a first synchronization unit.

The switching element 34 can alternatively be transferred from the third switching position shown in fig. 3 into the second switching position.

Then, the difference in rotational speed that may exist between the output shaft 32 and the housing 36 is first reduced or eliminated by means of the friction unit of the clutch device 34 d. To this end, the friction ring of the clutch element 34d is in contact with the friction-fitting surface of the housing 36. In other words, the output shaft 32 is first coupled with the housing via a friction lock.

When the rotational speed difference is below a predetermined limit value, the form-locking element of the clutch element 34d engages in the form-locking counter element of the housing 36. The output shaft 32 is then coupled with the housing 36 via a form-fit.

The friction unit of the clutch element 34d may be referred to as a second synchronizing unit.

An axle module 10 according to a second embodiment is shown in fig. 4.

Only the differences with respect to the first embodiment will be discussed here. The same or mutually corresponding components are provided with the same reference numerals.

The switching unit 16 is now arranged on the output side relative to the transmission 18 and the differential 20.

In contrast to the first embodiment, the ring gear 20a of the differential 20 is designed as a movable gear. The ring gear 20a can thus rotate relative to the basket 20b of the differential 20.

The input shaft 30 of the switching unit 16 is now formed by the ring wheel 20 a.

The output shaft 32 is constituted by the basket 20 b.

The switching element 34 can occupy the switching position already described in connection with the first embodiment.

The shift element 34 couples the input shaft 30, i.e., the ring gear 20a, to the output shaft 32, i.e., the basket 20b, in a torque-transmitting manner in the first shift position.

In this switching position, the

wheels

26, 28 can be driven by the electric drive machine 14.

The electric drive machine 14 can also be operated as a generator in the first switching position and regenerate the power applied to the

wheels

26, 28.

In the second switching position, the output shaft 32, i.e., the basket 20b, is rotationally coupled with the housing 36. In this switching position, the

wheels

26, 28 are braked or blocked as previously described.

In a third switching position, which corresponds to the switching position shown in fig. 4, the input shaft 30, i.e. the ring gear 20a, is decoupled from the output shaft 32, i.e. the basket 20b, and the output shaft 32 is likewise decoupled from the housing 36.

The

wheels

26, 28 are thus free to rotate.

Fig. 5 to 8 show a third embodiment of the axle module 10. Only differences from the embodiments already described are discussed again. The same or mutually corresponding components are once again provided with the same reference numerals.

The gear change transmission 18 is now designed as an integral part of the switching unit 16.

The output shaft 32 is constituted by an output shaft of the speed change transmission mechanism 18.

As in the first embodiment, the input shaft 30 of the switching unit 16 coincides with the output shaft of the electric drive machine 14.

The speed change transmission 18 is thus positioned in the power flow between the input shaft 30 and the output shaft 32.

The switching element again comprises a bearing part 34a, which is, however, now connected in a rotationally fixed manner to the input shaft 30, which is hollow in this case.

The sliding part 34b is again mounted in a rotationally fixed but axially displaceable manner on the bearing part 34a, but now, in addition to the previously described embodiment, also comprises a third clutch element 34e.

Furthermore, the first clutch element 34c and the second clutch element 34d are now arranged on the same axial side of the sliding part 34 b.

The switching element 34 can again assume a first switching position, which is shown in fig. 5.

In this switching position, the input shaft 30 and the output shaft 32 are connected in a torque-transmitting manner.

The first clutch element 34c is now connected to the clutch element 40a of the gear 40, which is rotatably mounted on the transmission countershaft 38, which is coaxial with the input shaft 30 and extends parallel to the output shaft 32.

The gear 40 meshes with a gear 42 which is mounted in a rotationally fixed manner on the output shaft 32.

Here, the path from the input shaft 30 to the output shaft 32 via the

gears

40, 42 is the first power path a of the change speed transmission mechanism 18.

The shift element 34 can also assume a second shift position, in which the output shaft 32 is coupled to the housing 36 again. This is shown in fig. 6.

The second clutch element 34d is connected to the clutch element 36a of the housing 36.

Furthermore, the first clutch element 34c is also connected to the clutch element 40a of the gear 40.

The output shaft 32 is thus rotationally coupled with the housing 36 via the

gears

40, 42.

In contrast to the previous exemplary embodiment, the input shaft 30 is now also coupled in rotation to the housing 36 via the sliding part 34b in the second switching position.

Furthermore, the shift element 34 can assume a third shift position, in which the input shaft 30 and the output shaft 32 are likewise decoupled from one another, as are the output shaft 32 and the housing 36 (see fig. 7).

In this case, all the

clutch elements

34c, 34d, and 34e are disengaged.

Furthermore, the switching element 34 can assume a fourth switching position, which is shown in fig. 8.

In this fourth switching position, the input shaft 30 is again coupled with the output shaft 32 in a torque-transmitting manner.

In this case, the third clutch element 34e is now connected to the clutch element 44a of the gear wheel 44, which is rotatably mounted on the input shaft 30.

The gear 44 meshes with a gear 46 which is mounted non-rotatably on the output shaft 32.

Thus, the path from the input shaft 30 to the output shaft 32 via the

gears

44, 46 is the second power path B of the variator 18.

The second power path B is at least partially separate from the first power path a.

In other words, two gears of the variable speed transmission 18 can be shifted by means of the shift element 34, wherein the first gear uses the first power path a and the second gear uses the second power path B.

Claims

1. Switching unit (16) for an electrified drive train of a motor vehicle, comprising:

an input shaft (30) that is couplable to the electric drive machine (14),

an output shaft (32) on which a drive torque can be provided and/or a regenerative torque can be received, and

a switching element (34) at least partially disposed in the housing (36),

it is characterized in that the preparation method is characterized in that,

the shift element (34) couples the input shaft (30) to the output shaft (32) in a torque-transmitting manner in a first shift position, and

the switching element (34) rotationally couples the output shaft (32) with the housing (36) in a second switching position.

2. The shift unit (16) according to claim 1, characterized in that the shift element (34) couples the input shaft (30) with the output shaft (32) in the first shift position via a form-fit and/or via a friction-fit.

3. The shift unit (16) according to claim 1 or 2, characterized in that the shift element (34) rotationally couples the output shaft (32) with the housing (36) in the second shift position via a form-fit and/or via a friction-fit.

4. The switching unit (16) according to any one of the preceding claims, characterized in that the switching element (34) disconnects the input shaft (30) from the output shaft (32) and disconnects the output shaft (32) from the housing (36) in a third switching position.

5. The switching unit (16) according to any one of the preceding claims, wherein the switching element (34) is pretensioned into one of the switching positions, in particular by means of a spring (35).

6. The switching unit (16) of any of the preceding claims characterized by a variable speed transmission (18) located in the power flow between the input shaft (30) and the output shaft (32).

7. The shift unit (16) according to claim 6, characterized in that the shift element (34) couples the input shaft (30) in torque-transmitting manner with the output shaft (32) via at least one gear mechanism intermediate shaft (38) in the first shift position.

8. The shift unit (16) according to claim 6 or 7, characterized in that the shift element (34) rotationally couples the output shaft (32) with the housing (36) via at least one gear intermediate shaft (38) in the second shift position.

9. The switching unit (16) according to any one of claims 6 to 8, wherein the switching element (34) couples the input shaft (30) in a torque-transmitting manner with the output shaft (32) via a first power path (A) of the change gear (18) in the first switching position.

10. The shift unit (16) according to claim 9, characterized in that the shift element (34) couples the input shaft (30) in a torque-transmitting manner with the output shaft (32) via a second power path (B) of the change gear (18) in a fourth shift position, wherein the second power path (B) is at least partially separated from the first power path (a).

11. The switching unit (16) according to any one of the preceding claims, characterized by a locking mechanism configured to prevent a switching movement of the switching element (34), in particular depending on an operating parameter of the switching unit (16).

12. The switching unit (16) according to any one of the preceding claims, characterised by a synchronization unit for reducing a difference in rotational speed between components to be coupled by means of the switching element (34).

13. Drive unit (12) for an electrified drive train of a motor vehicle, having an electric drive machine (14) and a switching unit (16) according to one of the preceding claims, wherein the electric drive machine (14) is coupled with the input shaft (30) in a torque-transmitting manner.

14. Axle module (10) for a motor vehicle, having a drive unit (12) according to claim 13, wherein the output shaft (32) of the switching unit (16) forms a wheel output shaft (22, 24) or is coupled in a torque-transmitting manner to at least one wheel output shaft (22, 24), in particular the output shaft (32) is coupled in a torque-transmitting manner to two wheel output shafts (22, 24) arranged on opposite sides of the axle module (10).