Drive device for a vehicle axle

Abstract

The invention relates to a drive device for a vehicle axle of a two-track vehicle, the vehicle axle having an axle differential (9), the input side of which is drivingly connected to an electric machine (EM) and the output sides of which output to output shafts (27, 28) leading to the two vehicle wheels, the electric machine (EM) being installed in the vehicle axle in a transverse installation and being offset towards one side of the vehicle with respect to a vehicle central longitudinal axis such that the electric machine (EM) and the output shafts (27, 28) are arranged axially parallel to one another, and the vehicle axle being designed with a brake module (7, 8) on each output side of the axle differential (9). According to the invention, a brake module installation space (32) in which the two brake modules (7, 8) are located is spanned between the electric machine (EM), the output shaft (28) located on the side of the vehicle on which the electric machine is located, and the axle differential (9).

Description

[0001] Drive device for a vehicle axle

[0002] DESCRIPTION:

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

[0004] Such a vehicle axle has an axle differential, the input side of which is peacefully connected to an electric motor and the output sides of which drive on output shafts leading to the two vehicle wheels.

[0005] In a conventional vehicle axle, each wheel is equipped with a disc brake, consisting of a brake disc mounted on a vehicle output shaft and a cooperating brake caliper. The brake wear generated during braking is emitted into the environment. In contrast, in a generic vehicle axle, the disc brakes are replaced by multi-disk brakes, thus preventing brake wear from being emitted into the environment.

[0006] A differential assembly for a motor vehicle is known from DE 10 2008 029 282 A1. This assembly comprises a main differential, which distributes a drive torque introduced via a drive shaft to a first and a second output shaft, and a controllable auxiliary transmission coupled to the main differential, with which the distribution of the drive torque can be regulated. The auxiliary transmission comprises a first and a second planetary gear set, which are coupled to one another, each have a negative stationary gear ratio, and each have a brakeable transmission element. The auxiliary transmission comprises a third planetary gear set with a negative stationary gear ratio, which is coupled to the first and second planetary gear sets. A drive train for a motor vehicle is known from DE 10 2013 214 095 A1.This comprises a first electric machine with a rotor and a stator for driving a driven axle which passes coaxially through the rotor and has two steering knuckles, a gear stage coupled to the rotor and arranged coaxially to the first electric machine, a differential which is coupled at its input element to an output element of the gear stage, arranged coaxially to the gear stage and coupled at its output elements to the steering knuckles, and a torque application unit which is coupled to the differential via a reinforcement mechanism and arranged coaxially to the latter.

[0007] The object of the invention is to provide a drive device for a vehicle axle of a two-track vehicle which, compared to the prior art, can be implemented with reduced installation space requirements and is structurally simple.

[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 vehicle axle of a two-track vehicle, which has an axle differential. Its input side is drivingly connected to an electric motor, while its output sides drive output shafts leading to the two vehicle wheels. The electric motor is offset to one side of the vehicle with respect to a vehicle's central longitudinal axis and is installed transversely in the vehicle axle. Accordingly, the electric motor and the output shafts are arranged parallel to one another. The vehicle axle also has a brake module on each output side of the axle differential. The brake modules can be controlled by a control unit for uniform or uneven vehicle braking on both vehicle wheels.According to the characterizing part of claim 1, the installation space required can be reduced by the following design measure: A brake module installation space is created between the electric motor, the output shaft located on the electric motor side of the vehicle, and the axle differential. The two brake modules are arranged in the brake module installation space. This creates additional free space on the side of the vehicle opposite the brake module installation space in the transverse direction of the vehicle, in which a subframe or other components can be installed.

[0010] To further increase the brake module installation space, especially in the axial direction, the axle differential can be designed as a spur gear differential or a planetary gear differential, which are axially shorter than a conventional bevel gear differential. A key advantage of such a spur gear differential compared to a bevel gear differential is that, with simple design effort, the two brake modules positioned in the brake module installation space can act on the output sides of the spur gear differential.

[0011] The spur gear differential consists of a gear set arranged in a common gear plane, namely a radially outer ring gear, a radially inner sun gear, and a planet gear carrier. At least one radially outer planet gear and one radially inner planet gear are rotatably mounted on the planet gear carrier and mesh with each other. The radially outer planet gear meshes with an internal toothing of the ring gear, while the radially inner planet gear meshes with the sun gear.

[0012] In such a spur gear differential design, the planetary gear carrier can be connected to one of the two output shafts via a drive flange. Furthermore, the ring gear can form an input element of the axle differential, which is in driving connection with the electric motor. The sun gear, on the other hand, can be connected to the other output shaft, in particular to the electric motor-side output shaft.

[0013] A brake flange, which is a component of one of the brake modules, can also be formed on the electric motor-side output shaft. Furthermore, the planetary gear carrier can be axially extended with an intermediate hollow shaft on the side axially opposite its input flange. The electric motor-side output shaft extends coaxially through the intermediate hollow shaft. A further brake flange, which is a component of the other brake module, can be formed on the intermediate hollow shaft.

[0014] In a technical implementation, each of the brake modules can be a wet-running multi-disk brake. This consists of an inner disc carrier, an outer disc carrier, and an intermediate disc pack. The outer disc carrier can be permanently attached to a transmission housing, while the inner disc carrier is attached to the brake flange. The multi-disk brake can be hydraulically controlled. For this purpose, a hydraulic cylinder is assigned to the multi-disk brake, which is connected to the control unit via a hydraulic control line. The hydraulic cylinder, with an annular piston in between, applies contact pressure to the disc pack of the multi-disk brake to engage the multi-disk brake.

[0015] In a specific embodiment, the rotor shaft of the electric motor can be connected to an intermediate shaft via a countershaft stage, in particular a countershaft spur gear stage. The intermediate shaft can be aligned axially parallel to the rotor shaft. With regard to an axially short transmission housing, the intermediate shaft can extend on one side from the countershaft stage in the opposite direction to the rotor shaft back toward the front end of the electric motor. The intermediate shaft can carry a fixed gear that meshes with an axle differential input gear. In the case of a spur gear differential, the intermediate shaft fixed gear can mesh with an external toothing of the spur gear differential gear.

[0016] In a further development, the axle differential can have a differential lock, by means of which the axle differential can be locked. The differential lock can be constructed from a clutch. For example, a locking flange formed on the intermediate hollow shaft can be connected to the ring gear of the spur gear differential in a force-transmitting manner by means of the differential lock clutch. Alternatively, the differential lock clutch can be connected between the brake flange of the planetary gear carrier and the electric motor-side output shaft. In a further design variant, the differential lock clutch can be connected between the drive flange of the planetary gear carrier and the electric motor-side output shaft.

[0017] Embodiments of the invention are described below with reference to the attached figures.

[0018] They show:

[0019] Figures 1 to 4 show different representations of a vehicle axle with integrated multi-disk brakes.

[0020] Figure 1 shows an electrified vehicle axle with an electric motor EM and a transmission. The electric motor EM is connected to a high-voltage battery (not shown). Conventional vehicle wheel disc brakes are omitted from the vehicle axle. Instead, the vehicle axle has brake modules 7, 8, which in the present embodiment are implemented as wet-running multi-disk brakes, by means of which vehicle braking can be carried out. Each of the multi-disk brakes consists of an inner disc carrier, an outer disc carrier, and an intermediate disc pack. The outer disc carrier is fixedly connected to a transmission housing 55, while the inner disc carrier is connected to the brake flange 34, 37.

[0021] The electric motor EM is connected via its rotor shaft 5, with a transmission stage 6 interposed, to the input side of an axle differential 9. Its output sides are connected to the vehicle wheels via output shafts 27, 28. Furthermore, the electric motor EM is offset toward the right-hand vehicle axle with respect to a vehicle centerline. In the present exemplary embodiment, the axle differential 9 is, for example, a spur gear differential. The axle differential 9 can be designed as an open differential or as a limited-slip differential, for example, as a torque-sensing differential with a passive differential lock.

[0022] In Figure 1, the EM electric motor is installed transversely in the vehicle axle. Accordingly, the rotor shaft 5 and the output shafts 27, 28 are arranged axially parallel to each other. Likewise, the multi-disk brakes 7, 8 installed in the vehicle axle are aligned axially parallel to each other.

[0023] In the transmission structure of the vehicle axle shown in Figure 1, the countershaft stage 6 consists of two spur gear stages 19, 20. The rotor shaft 5 of the electric machine EM is connected to an intermediate shaft 13 via a first spur gear stage 19. The first spur gear stage 19 is constructed from a fixed gear 15 arranged on the rotor shaft 5 and a fixed gear 17 meshing therewith and arranged on the intermediate shaft 13. The intermediate shaft 13 is connected to the input side of the spur gear differential 9 via a second spur gear stage 20. The second spur gear stage 20 is constructed from a fixed gear 21 arranged on the intermediate shaft 13 and an input-side spur gear differential gear 23. In view of an axially short transmission housing, the intermediate shaft 13 extends on one side from the countershaft stage 19 in the opposite direction to the rotor shaft 5 back towards the electric machine end face 51.

[0024] In Figure 1, the spur gear differential gear 23 is part of a radially outer ring gear 25 with internal teeth. The radially outer ring gear 25, together with an inner sun gear 22 and a planet gear carrier 24, forms a planetary gear set. In Figure 1, the planet gear carrier 24 carries a radially outer planet gear 28 and a radially inner planet gear 26. The radially outer planet gear 28 meshes with an internal toothing of the ring gear 25, while the radially inner planet gear 26 meshes with the sun gear 22. Furthermore, the two planet gears 26, 28 mesh with each other. The planet gear carrier 24 is connected to the left output shaft 27 via a drive flange 30. In contrast, the sun gear 22 of the spur gear differential 9 is connected to the right output shaft 28 (hereinafter referred to as the electric machine-side output shaft).

[0025] A core of the invention is that between the electric machine EM, the output shaft 28 arranged on the electric machine side of the vehicle and the spur gear differential 9, a brake module installation space 32 is spanned, in which the two multi-disk brakes 7, 8 are arranged in a space-efficient manner.

[0026] The two multi-disk brakes 7, 8 are connected to the two output sides of the spur gear differential 9 as follows: The electric machine-side output shaft 28 has a brake flange 34. This protrudes into the brake module installation space 32 and is a component of one of the multi-disk brakes 8. In contrast, the planetary gear carrier 24 is axially extended on the side axially opposite its input flange 30 by an intermediate hollow shaft 35. The electric machine-side output shaft 28 extends through the intermediate hollow shaft 35. A further brake flange 37 is formed on the intermediate hollow shaft 35. This also protrudes—axially adjacent to the brake flange 34—into the brake module installation space 32 and is a component of the other brake module 7.

[0027] Figure 2 shows a vehicle axle according to a second exemplary embodiment. Its transmission structure is essentially similar to the transmission structure of the first exemplary embodiment. In contrast to the first exemplary embodiment, the transmission structure according to Figure 2 additionally has an active differential lock 41, by means of which the spur gear differential 9 can be locked. The differential lock 41 can be implemented as a clutch, by means of which, in Figure 2, a locking flange 43 formed on the intermediate hollow shaft 35 can be connected to the ring gear 25 of the spur gear differential 9 in a force-transmitting manner. Alternatively, a further exemplary embodiment is indicated in Figure 3. In contrast to Figure 2, in Figure 3 the differential lock 41 is connected between the brake flange 37 of the planetary gear carrier 24 and the electric machine-side output shaft 28.Alternatively, in Figure 4, the transverse lock 41 is connected between the drive flange 30 of the planetary gear carrier 24 and the electric machine-side output shaft 28.

[0028] LIST OF REFERENCE SYMBOLS:

[0029] 5 Rotor shaft

[0030] 6 countershaft stage

[0031] 7, 8 brake modules

[0032] 9 axle differential

[0033] 13 Intermediate shaft

[0034] 15, 17 fixed gears

[0035] 19, 20 spur gear stages

[0036] 21 Fixed gear

[0037] 23 Input gear of the axle differential

[0038] 25 ring gear

[0039] 27, 28 Output shafts

[0040] 22 Sun gear

[0041] 24 planetary gear carriers

[0042] 26 radial inner planetary gear

[0043] 28 radial outer planetary gear

[0044] 30 drive flange

[0045] 32 brake module installation space

[0046] 34 Brake flange

[0047] 35 Intermediate hollow shaft

[0048] 37 Brake flange

[0049] 41 Transverse lock

[0050] 43 Locking flange

[0051] 51 Electrical machine front side

[0052] 55 Gearbox housing

[0053] EM electric machine

Claims

PATENT CLAIMS:

1. Drive device for a vehicle axle of a two-track vehicle, which has an axle differential (9), the input side of which is drivingly connected to an electric machine (EM) and the output sides of which drive on output shafts (27, 28) leading to the two vehicle wheels, wherein the electric machine (EM) is installed transversely in the vehicle axle, is offset towards one side of the vehicle with respect to a vehicle central longitudinal axis, and the electric machine (EM) and the output shafts (27, 28) are arranged axially parallel to one another, and wherein the vehicle axle is formed on each output side of the axle differential (9) with a brake module (7, 8), which can be controlled in particular by a control unit for uniform or uneven vehicle braking on both vehicle wheels, characterized in that between the electric machine (EM),a brake module installation space (32) is spanned between the output shaft (28) arranged on the electric machine side of the vehicle and the axle differential (9), in which the two brake modules (7, 8) are arranged.

2. Drive device according to claim 1, characterized in that in order to increase the brake module installation space (7, 8) in the axial direction, the axle differential (9) is designed as an axially short spur gear differential or planetary gear differential, and / or that the axle differential (9) can be designed as an open differential or as a self-locking differential, for example a torque-sensing differential with a passive transverse lock.

3. Drive device according to claim 2, characterized in that the spur gear differential (9) comprises a gear set arranged in a common gear plane comprising a radially outer ring gear (25), a radially inner sun gear (22) and a planet gear carrier (24), and that the planet gear carrier (24) has at least one radially outer planet gear (28) and one radially inner planet gear (26), which mesh both with an internal toothing of the ring gear (25) and with the sun gear (22) and also mesh with each other.

4. Drive device according to claim 3, characterized in that the planet gear carrier (24) is connected to one of the two output shafts (27) via a drive flange (30), and / or that the ring gear (25) forms an input element of the axle differential (9) which is in driving connection with the electric machine (EM), and / or that the sun gear (22) is connected to the other output shaft (28), in particular to the electric machine-side output shaft (28).

5. Drive device according to claim 4, characterized in that a brake flange (34) is formed on the electric machine-side output shaft (28), which is a component of the one brake module (8).

6. Drive device according to claim 4 or 5, characterized in that the planet gear carrier (24) is axially extended on the side axially opposite its drive flange (30) by an intermediate hollow shaft (35) through which the electric machine-side output shaft (28) extends, and in that in particular a brake flange (37) is formed on the intermediate hollow shaft (35), which is a component of the other brake module (7).

7. Drive device according to one of the preceding claims, characterized in that each of the brake modules (7, 8) is a multi-disk brake which is constructed from an inner disk carrier, an outer disk carrier and an intermediate disk pack, and in particular that the The outer disk carrier is fixed to a gearbox housing (55), while the inner disk carrier is connected to the brake flange (34, 37).

8. Drive device according to one of the preceding claims, characterized in that the axle differential (9) has a transverse lock (41) by means of which the axle differential (9) can be locked, and in particular by means of the transverse lock (41) the planet gear carrier (24) can be locked to the ring gear (25), and in particular that the transverse lock (41) is connected between a locking flange (43) formed on the intermediate hollow shaft (35) of the planet gear carrier (24) and the ring gear (25).

9. Drive device according to claim 8, characterized in that the planet gear carrier (24) can be locked to the sun gear (25) by means of the transverse lock (41), and in particular that the transverse lock (41) is connected between the brake flange (37) of the intermediate hollow shaft (35) of the electric machine-side output shaft (28), or that the transverse lock (41) is connected between the drive flange (30) of the planet gear carrier (24) and the electric machine-side output shaft (28).

10. Drive device according to one of the preceding claims, characterized in that the rotor shaft (5) of the electric machine (EM) is connected to an intermediate shaft (13) via a countershaft stage (7), in particular a countershaft spur gear stage, that the intermediate shaft (13) is arranged axially parallel to the rotor shaft (5), that the intermediate shaft (13) extends in the opposite direction to the rotor shaft (5) in the direction of the electric machine end face (51), and that in particular the intermediate shaft (13) carries a fixed gear (21) which meshes with an axle differential input gear (23).

Images