Drive device for a two-track vehicle

Abstract

The invention relates to a drive device for a two-track vehicle with a vehicle axle which has an axle differential (3) that can be connected on the input side to a primary drive machine and can be connected on the output side to vehicle wheels (9) via output shafts (5, 7) arranged on both sides, wherein the vehicle axle has an electric torque vectoring module with a superimposing transmission (25) and with an electric machine (26) which acts as a torque vectoring actuator, activation of which electric machine enables electric torque vectoring, that is to say superimposition of a differential torque between the vehicle wheels (9), to be carried out. According to the invention, the vehicle axle has at least one multi-disc brake (55), in particular a central multi-disk brake, in particular a wet-running multi-disc brake, which acts on the vehicle axle such that vehicle braking can be carried out, in particular in combination with the electric torque vectoring module.

Description

[0001] Drive device for a two-track vehicle

[0002] DESCRIPTION:

[0003] The invention relates to a drive device for a two-track vehicle according to the preamble of claim 1.

[0004] A typical drive system for a two-track vehicle, for example, has an electric motor on its rear axle as the primary drive unit. The drive system is also designed with an electrically driven torque vectoring module, which consists of a superposition gear and an electric motor acting as a torque vectoring actuator. When the torque vectoring actuator is activated, electric torque vectoring is performed, i.e., a differential torque is created between the vehicle wheels on the rear axle. In addition to conventional wheel-side brakes, such a system offers the possibility of selectively transferring torque from one wheel to the other, thus intervening in the vehicle's lateral dynamics to stabilize or enhance agility.

[0005] On a conventional vehicle rear axle, each wheel is equipped with a disc brake, consisting of a brake disc positioned on a vehicle output shaft and a cooperating brake caliper. The brake wear generated during braking is emitted into the environment. Furthermore, conventional disc brakes are maintenance-intensive and, due to their less frequent use on the rear axle of electrically powered vehicles, are often subject to severe wear and tear due to corrosion. DE 10 2017 102 880 A1 discloses a torque vectoring device that is operatively connected to the wheels of a vehicle axle. The torque vectoring device has an electric actuator and is designed in combination with a wet brake device, dispensing with conventional wheel brakes.

[0006] DE 10 2014 117 227 A1 discloses an electric axle drive for a vehicle, which has a torque vectoring unit and a wet brake. This serves to provide two selectable gears of the drive. DE 10 2022 103 839 B3 discloses a drive device for a vehicle axle. This drive device has a multi-disk brake combined with the drive device as the vehicle wheel brake. Mechanical torque vectoring can be implemented in the drive device, which is actuated via clutches.

[0007] The object of the invention is to provide a drive device with an integrated braking function for a two-track vehicle, which, compared to the prior art, can be implemented with reduced installation space, is structurally simple, requires little maintenance and is emission-free.

[0008] The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.

[0009] The invention relates to a drive device for a two-track vehicle with a vehicle axle having an axle differential. The axle differential is connected on the input side to a primary drive motor and on the output side to vehicle wheels via output shafts arranged on both sides. The vehicle axle has an electric torque vectoring module, which is designed with a superposition gear and an electric motor. The electric motor acts as a torque vectoring actuator. When activated, electric torque vectoring is performed, i.e., a differential torque is established between the vehicle wheels. According to the characterizing part of claim 1, the vehicle axle has at least one, in particular central, wet-running multi-disk brake acting on the vehicle axle. With the aid of the multi-disk brake, the drive device in question enables the implementation of a braking function for the vehicle.

[0010] The multi-disk brake serves as a replacement for conventional vehicle wheel brakes, i.e., disc or drum brakes. This eliminates brake dust emissions into the environment. Furthermore, the unsprung mass on the vehicle wheel is reduced compared to a conventional vehicle axle. Furthermore, the wet multi-disk brake is low-maintenance and, unlike conventional wheel brakes, corrosion-free. The wet multi-disk brake is switchable in an oil / cooling circuit of the electric motor acting as the primary drive unit or of the transmission. Furthermore, the multi-disk brake can be lubricated and cooled as needed, but only during braking. If no braking is required, any drag torque generated in the multi-disk brake can be reduced by evacuating the wet brake.

[0011] In one technical implementation, the multi-disk brake can be constructed from an inner disc carrier, an outer disc carrier, and an intermediate disc pack. The input side of the axle differential can be designed as an input gear that is rigidly connected to a differential housing of the axle differential. Furthermore, the multi-disk brake can act directly on the differential housing of the axle differential, thus saving space. With regard to package optimization, it is preferred if the inner disc carrier is rigidly connected to the differential housing, while the outer disc carrier is rigidly connected to a transmission housing wall.

[0012] The electric torque vectoring module can operate as follows in a torque distribution mode, i.e., when the torque vectoring actuator is activated: A drive torque generated by the torque vectoring actuator is coupled into one of the drive shafts via a first load path in order to apply a differential torque to the two vehicle wheels. With regard to a drive device that is short in the vehicle's longitudinal direction, it is preferred if the electric motor is installed transversely in the vehicle axle. The electric motor and the superposition gear can be arranged on the same side of the vehicle with respect to the axle differential. In this case, a multi-disk brake installation space can be spanned between the electric motor and the input gear of the axle differential, in which the multi-disk brake is arranged in a space-efficient manner.The multi-disk brake can be encapsulated together with the electric motor, the transmission stage and the axle differential as well as the torque vectoring module in a transmission housing from which the output shafts are led out on both sides in the transverse direction of the vehicle.

[0013] In a package-optimized implementation, the superposition gearing can comprise a first planetary gear consisting of a sun gear, a radially outer ring gear, and intermeshing planetary gears that are rotatably mounted on a planetary carrier. The elements of the first planetary gearing can be interconnected in the superposition gearing as follows: An input element, in particular a sun gear, can be connected to a transmission input shaft driven by the additional drive motor and, via its output element, in particular the planetary carrier, can be connected to a transmission output shaft that is seamlessly connected to the input side of the axle differential.

[0014] With a view to further package optimization, it is preferred if the transmission input shaft, the transmission output shaft, and the transmission-side output shaft are arranged coaxially and interleaved with one another. In this case, with a view to simple interconnection, it is preferred if the transmission input shaft is implemented as an external hollow shaft, within which the transmission output shaft is arranged as an intermediate hollow shaft. The transmission-side output shaft can preferably extend through this intermediate hollow shaft.

[0015] Depending on the available installation space, it may be preferable for the planetary gear set to be arranged coaxially with the transmission-side output shaft, while the space-intensive torque vectoring actuator (i.e., the electric motor) is not positioned coaxially with it, but rather axially parallel to the transmission-side output shaft. In this case, the torque vectoring actuator can be connected to the transmission input shaft via a countershaft stage. The countershaft stage can be a double spur gear stage for space-saving purposes. Alternatively, the countershaft stage can be of any other design, for example, a single spur gear stage.

[0016] In the above transmission design, both the sun gear of the first planetary gear and an output-side gear of the countershaft stage can be positioned in a rotationally fixed manner on the transmission input shaft in order to save space.

[0017] The superposition gearing can also comprise a second planetary gearing, which is preferably constructed identically to the first planetary gearing. Accordingly, the second planetary gearing can be connected to the ring gear of the first planetary gearing via its input element, in particular a ring gear, and can be connected in a rotationally fixed manner to the transmission-side output shaft via its output element (in particular a planet carrier). Its reaction element, in particular a sun gear, can be fixedly connected to the transmission housing.

[0018] With regard to a drive device that is short in the longitudinal direction of the vehicle, it is preferred if the first planetary gear is positioned coaxially with the second planetary gear. Furthermore, the installation space and component requirements can be reduced if both gears have only one common ring gear.

[0019] An embodiment of the invention is shown below with reference to the attached figure.

[0020] The figure shows a rough schematic of a transmission structure of a drive device for a vehicle axle of a two-track vehicle. The drive device indicated in the figure can have an electric motor as the primary drive machine (not shown). The axle differential 3 is drivingly coupled to the vehicle wheels 9 of the vehicle axle on the output side by means of output shafts 5, 7 arranged on both sides. In the figure, the axle differential 3 is a bevel gear differential with a differential housing 11 on which two or four differential bevel gears 13 (of which only one differential bevel gear 13 is shown in the figure) are rotatably mounted, as well as first and second axle shaft bevel gears 15, 17 which are arranged at right angles to the differential bevel gears 13 and coaxially spaced from one another and are each in tooth engagement with the two or four differential bevel gears 13.The first output bevel gear 15 is non-rotatably mounted on the left output shaft 5 in the figure, while the second output bevel gear 17 is non-rotatably mounted on the right output shaft 7 in the figure. The primary drive motor (not shown) is drivingly connected to an input gear 4 fixedly mounted on the differential housing 11.

[0021] As further shown in the figure, the vehicle axle has a torque vectoring module with a superposition gear 25 and an electric motor 26 that acts as a torque vectoring actuator. The superposition gear 25 is operable in a torque distribution mode (i.e., electric torque vectoring), as described later.

[0022] In torque distribution mode, the drive torque generated by the electric motor 26 is not only routed to the input side of the axle differential 3 via a drive flange 38 described later, but is also coupled directly to the transmission-side output shaft 7 via a torque distribution flange 40 in order to apply a differential torque to the two vehicle wheels 9. The magnitude and direction of rotation of the drive torque generated by the electric motor 26 are determined depending on current driving parameters.

[0023] The gear structure of the superposition gear 25 is explained below using the figure: Accordingly, the superposition gear 25 comprises a first planetary gear PG1 and a second planetary gear PG2. The two gears PG1, PG2 are arranged directly adjacent to one another in the vehicle's transverse direction y, are coaxially aligned, and are drivingly coupled to one another via a common ring gear 37. A sun gear 27 of the first planetary gear PG1 is rotatably mounted on a transmission input shaft 29, which is drivingly connected to the electric motor 26 via a countershaft 31. The sun gear 27 is in tooth engagement with the planet gears 33, which are rotatably mounted on a planet carrier 35, and the planet gears 33 are in tooth engagement with the radially outer ring gear 37. The planet carrier 35 is connected via the drive flange 38 to a transmission output shaft 41, which is fixedly connected to the drive-side differential housing 11.

[0024] In the figure, the transmission input shaft 29, the transmission output shaft 41, and the transmission-side output shaft 7 are arranged coaxially and nested within each other. The transmission input shaft 29 is implemented as an external hollow shaft, within which the transmission output shaft 41 is arranged as an intermediate hollow shaft, through which the transmission-side output shaft 7 extends.

[0025] The second planetary gear PG2 has a sun gear 47 acting as a reaction element, which is non-rotatably mounted on a hollow shaft through which the transmission-side output shaft 7 is guided. The hollow shaft is fixedly connected to the transmission housing 43. As can be seen from the figure, the sun gear 47 meshes with the planet gears 49, which are rotatably mounted on a planet carrier 51, and the planet gears 49 mesh with the common ring gear 37. The planet carrier 51 (acting as the output element) is non-rotatably coupled to the transmission-side output shaft 7 via the torque distribution flange 40.

[0026] In the figure, the reduction gear 31 is constructed as a two-stage spur gear stage, the output-side gear 53 of which sits as a fixed gear on the transmission input shaft 29.

[0027] In a torque distribution mode, the electric motor 26 is activated during cruising operation (e.g., when cornering) depending on the current driving parameters. This results in a first load path between the electric motor 26 and the transmission-side output shaft 7, in which a drive torque generated by the electric motor 26 can be coupled via the transmission input shaft 29, the common ring gear 37, as well as the planet gears 49 and the planet carrier 51 of the second planetary gear PG2 via the torque distribution flange 40 into the transmission-side output shaft 7. At the same time, a second load path results in which the drive torque generated by the electric motor 26 can be coupled via the transmission input shaft 29, the planet gears 33, the planet carrier 35, and the central drive flange 38 into the transmission output shaft 41, which is connected to the differential housing 11.

[0028] A core of the invention is that the vehicle axle has a central wet-running multi-disk brake 55 instead of conventional vehicle wheel brakes (i.e., disc or drum brakes), so that vehicle braking is possible. In the figure, the central multi-disk brake 55, together with the electric motor 26, the countershaft stage 31, the axle differential 3, and the torque vectoring module, is encapsulated in the transmission housing 43, from which the output shafts 5, 7 lead to the vehicle wheels 9 on both sides in the vehicle transverse direction y. The multi-disk brake 55 is arranged in a brake installation space 57 between the electric motor 26 and the input gear of the axle differential 3 with a view to package optimization.

[0029] An inner disc carrier 59 of the multi-disk brake 55 is fixedly connected to the differential housing 11, while an outer disc carrier 60 of the multi-disk brake 55 is fixedly connected to the transmission housing 53. The multi-disk brake 55 is actuated by an actuator 63. This can be controlled electrically or hydraulically by means of a control unit (not shown).

[0030] 3 axle differential

[0031] 4 input gear

[0032] 5, 7 output shafts

[0033] 9 Vehicle wheel

[0034] 11 Differential housing

[0035] 13 differential bevel gear

[0036] 15, 17 Output bevel gears

[0037] 25 superposition gears

[0038] 26 Electric machine or torque vectoring actuator

[0039] 27 Sun gear

[0040] 29 Gearbox input shaft

[0041] 31 Countershaft stage

[0042] 33 Planetary gear

[0043] 35 planet carrier

[0044] 37 common ring gear

[0045] 38 Drive flange

[0046] 40 moment distribution flange

[0047] 41 Gearbox output shaft

[0048] 43 Gearbox housing

[0049] 47 Sun gear

[0050] 49 Planetary gear

[0051] 51 planet carrier

[0052] 53 output-side gear

[0053] 55 multi-disk brake

[0054] 57 installation space

[0055] 59 inner disc carrier

[0056] 61 outer disc carrier

[0057] 63 Actuator

[0058] PG1 , PG2 planetary gear

Claims

PATENT CLAIMS:

1. Drive device for a two-track vehicle with a vehicle axle having an axle differential (3) which can be connected on the input side to a primary drive machine and on the output side to vehicle wheels (9) via output shafts (5, 7) arranged on both sides, wherein the vehicle axle has an electric torque vectoring module with a superposition gear (25) and an electric machine (26) acting as a torque vectoring actuator, the activation of which enables electric torque vectoring, i.e., the introduction of a differential torque between the vehicle wheels (9), characterized in that the vehicle axle has at least one, in particular central, in particular wet-running multi-disk brake (55) acting on the vehicle axle, so that vehicle braking can be carried out, in particular in combination with the electric torque vectoring module.

2. Drive device according to claim 1, characterized in that the multi-disk brake (55) is constructed from an inner disk carrier (59), an outer disk carrier (61) and an intermediate disk pack.

3. Drive device according to claim 1 or 2, characterized in that the input side of the axle differential (3) is an input gear (4) which is fixedly connected to a differential housing (11) of the axle differential (3), and / or that in particular the multi-disk brake (55) acts directly on the differential housing (11) of the axle differential (3).

4. Drive device according to claim 3, characterized in that the inner disk carrier (59) is fixed to the differential housing (11), while the outer disk carrier (61) is fixed to the gearbox housing (43).

5. Drive device according to one of the preceding claims, characterized in that the electric machine (26) is installed transversely in the vehicle axle, and / or that the electric machine (26) and the superposition gear (25) are arranged on the same side of the vehicle with respect to the axle differential (3), and that between the electric machine (26) and the input gear (4) of the axle differential (3), a brake installation space (57) is spanned, in which the multi-disk brake (55) is arranged, and / or that in particular the multi-disk brake (55) together with the electric machine (26), the torque vectoring module and the axle differential (3) are encapsulated in a transmission housing (43) from which the output shafts (5, 7) are led out on both sides in the vehicle transverse direction (y).

6. Drive device according to one of the preceding claims, characterized in that in a torque distribution mode, that is to say when the electric machine (26) is activated, a drive torque generated by the electric machine (26) can be coupled into one of the drive shafts (5, 7) via a first load path, and in particular the drive torque generated by the electric machine (26) can be coupled into the input side of the axle differential (3) via a second load path in order to set a differential torque and thus change the torque distribution to the two vehicle wheels (9) and / or in particular the superposition gear (25) has a first planetary gear (PG1) which, via its input element, in particular a sun gear (27), is connected to a transmission input shaft (29) driven by the electric machine (26) and via its output element, in particular a planet carrier (35) carrying planetary gears (33), with a transmission output shaft (41) leading to the axle differential (3).

7. Drive device according to claim 6, characterized in that the transmission input shaft (29), the transmission output shaft (41) and the transmission-side output shaft (7) are arranged coaxially and interleaved with one another, and in that the transmission input shaft (29) is realized as an external hollow shaft in which the transmission output shaft (41) is arranged as an intermediate hollow shaft through which the transmission-side output shaft (7) extends, and / or in particular that the first planetary gear (PG1) is arranged coaxially to the transmission-side output shaft (7), and / or in that the electric machine (26) is arranged axially parallel to the transmission-side output shaft (7) and is connected to the transmission input shaft (29) via a countershaft stage (31), in particular a double spur gear stage (31),and that in particular on the transmission input shaft (29) the sun gear (27) of the first planetary gear (PG1) as well as an output-side gear (53) of the countershaft stage (31) are arranged in a rotationally fixed manner.

8. Drive device according to one of the preceding claims, characterized in that the superposition gear (25) has a second planetary gear (PG2), and that the second planetary gear (PG2) can be connected to the ring gear of the first planetary gear (PG1) via its input element, in particular a ring gear (37), and is connected in a rotationally fixed manner to the transmission-side output shaft (7) via its output element, in particular a planet carrier (51) carrying planet gears (49), the reaction element of which, in particular a sun gear (47), is connected to the transmission housing (43) in a housing-fixed manner.

9. Drive device according to claim 8, characterized in that the second planetary gear (PG2) is arranged coaxially to the first planetary gear (PG1), and / or that the two planetary gears (PG1, PG2) have a common ring gear (37).

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