Drive device for a vehicle axle of a two-track vehicle

Abstract

A drive device for a vehicle axle, especially a rear axle, of a two-track vehicle, wherein the vehicle axle includes an axle differential, which can be connected at the input end to a primary drive machine and can be connected at the output end across flange shafts arranged on either side to vehicle wheels of the vehicle axle, wherein the vehicle axle is associated with an additional drive machine and a shiftable superimposing gear, which can be shifted to a torque distribution gear in which a drive torque is generated by the additional drive machine.

Claims

1. A drive device for a vehicle axle of a two-track vehicle, wherein the vehicle axle comprises: an axle differential, which can be connected at the input end to a primary drive machine and can be connected at the output end across flange shafts arranged on either side to vehicle wheels of the vehicle axle, wherein the vehicle axle is associated with an additional drive machine and a shiftable superimposing gear, which can be shifted to a torque distribution mode in which a drive torque is generated by the additional drive machine, depending on the magnitude and direction of rotation of which a torque distribution on the two vehicle wheels can be changed, and shifted to at least one hybrid mode in which the drive torque generated by the additional drive machine can be coupled to both flange shafts of the vehicle wheels, evenly distributed across the axle differential, wherein the superimposing gear comprises exactly three planetary gearings coupled together: an input planetary gearing, an intermediate planetary gearing, and an output planetary gearing, wherein a load path is formed when a first hybrid mode is engaged in which a power branching occurs and all three of the three planetary gearings are incorporated, wherein, when a second hybrid mode is engaged and when the torque distribution mode is engaged, a load path is formed in the superimposing gear in which, of the three planetary gearings, only the input planetary gearing and the intermediate planetary gearing are incorporated.

2. The drive device according to claim 1, wherein the input planetary gearing is connected in driving manner to the additional drive machine, the output planetary gearing connected in driving manner to the axle differential, and the intermediate planetary gearing is connectively incorporated between the input planetary gearing and the output planetary gearing, wherein the three planetary gearings are arranged in succession coaxially to the flange shaft, and the input planetary gearing is rotationally fixed by its input element, a sun gear, to a gearing input shaft which is driven by the additional drive machine, and/or in that the output planetary gearing is rotationally fixed to a hybrid output flange by its output element, a planet carrier carrying planet gears, and is arranged on a gearing output shaft, which is connected in driving manner to the input end of the axle differential, and/or in that the output planetary gearing comprises a ring gear, meshing with the planet gears and fixed to the housing.

3. The drive device according to claim 2, wherein the sun gear of the input planetary gearing meshes with planet gears, which are rotatably mounted on a planet carrier and are in tooth engagement with a ring gear, and in that the ring gear of the input planetary gearing and a ring gear of the intermediate planetary gearing are rotationally fixed on a ring gear shaft, and in that the ring gear of the intermediate planetary gearing meshes with planet gears which are rotatably mounted on a planet carrier and which are in tooth engagement with a sun gear, fixed on the housing.

4. The drive device according to claim 3, wherein the planet carrier of the input planetary gearing can be locked by a hybrid shift element to the gearbox housing or be released from it, and in that a planet carrier of the intermediate planetary gearing is rotationally fixed on the planet carrier of the output planetary gearing or on the gearing output shaft, so that, in the second hybrid mode, the planet carrier of the input planetary gearing is connected by the hybrid shift element firmly to the housing, so that a load path is produced from the additional drive machine across the input planetary gearing to the intermediate planetary gearing and then across the gearing output shaft to the input end of the axle differential.

5. The drive device according to claim 4, wherein the planet carrier of the intermediate planetary gearing and the planet carrier of the output planetary gearing are connected in driving manner to each other by a connecting shaft.

6. The drive device according to claim 1, wherein the axle differential comprises: a Ravigneaux set, in which planet gears of a first planet gear set mesh with both a radially outer ring gear, forming the input end of the axle differential, with planet gears of a second planet gear set, respectively, and with a first, major sun gear, and in that the planet gears of the second planet gear set mesh with a second, minor sun gear, the two planet gear sets being rotatably mounted on a common planet carrier, and in that the first, major sun gear is rotationally fixed on the torque distribution output shaft, the second, minor sun gear is rotationally fixed on the one flange shaft and the common planet carrier is rotationally fixed on the other flange shaft.

7. The drive device according to claim 6, wherein the torque distribution shaft carries a rotationally fixed torque distribution output flange, by which a torque distribution shift element can be coupled in driving manner to the planet carrier of the input planetary gearing or be released from it.

8. The drive device according to claim 7, wherein, when the torque distribution mode is engaged, the torque distribution shaft and the planet carrier of the input planetary gearing are joined together in driving manner by the torque distribution shift element, so that a load path is produced from the additional drive machine to the input planetary gearing, on the planet carrier of which a power distribution occurs, during which a first partial path goes across the ring gear of the input planetary gearing and across the ring gear shaft to the intermediate planetary gearing, and from here the first partial path continues across its planet carrier to the gearing output shaft, the output planetary gearing turning freely and not being incorporated in the load path, and a second partial path continues across the planet carrier of the input planetary gearing and the engaged torque distribution shift element to the torque distribution shaft.

9. The drive device according to claim 2, wherein the output planetary gearing further comprises a sun gear, which meshes with its planet gears and can be coupled by a hybrid shift element to the planet carrier of the input planetary gearing or be released from it, and in that, when the first hybrid mode is engaged, the planet carrier of the input planetary gearing is coupled in driving manner to a sun gear of the output planetary gearing by the hybrid shift element, so that a load path is formed from the additional drive machine to the input planetary gearing, on the planet carrier of which a power branching occurs, during which a first partial path continues across the planet gears and the ring gear of the input planetary gearing to the ring gear shaft; and then to the intermediate planetary gearing, from which the first partial path continues across the connecting shaft to the planet carrier of the output planetary gearing and to the gearing output shaft, and a second partial path continues from the planet carrier of the input planetary gearing across the engaged hybrid shift element to the sun gear of the output planetary gearing, and a power addition occurs on the planet carrier of the output planetary gearing, during which the first and second partial paths are combined.

10. The drive device according to claim 2, wherein the planet carrier of the input planetary gearing is connected to a shifting shaft, which bounds off a radially inward design space, in which the input and the intermediate planetary gearing are arranged, and in that, particularly at a shaft end of the shifting shaft situated axially away from the input planet carrier, the first hybrid shift element, the second hybrid shift element and the torque distribution shift element are positioned thereon.

11. The drive device according to claim 10, wherein a sun gear of the output planetary gearing is arranged on a sun gear shaft, and a shaft end of the sun gear shaft away from the sun gear can be coupled by the first hybrid shift element to the shifting shaft.

12. The drive device according to claim 1, wherein the output planetary gearing is situated vehicle-inward in the vehicle transverse direction and immediately next to the axle differential, and the intermediate planetary gearing is situated vehicle-outward, and in that the shift elements are positioned on the vehicle-outward side of the intermediate planetary gearing.

13. The drive device according to claim 2, wherein the axle differential comprises: a Ravigneaux set, in which planet gears of a first planet gear set mesh with both a radially outer ring gear, forming the input end of the axle differential, with planet gears of a second planet gear set, respectively, and with a first, major sun gear, and in that the planet gears of the second planet gear set mesh with a second, minor sun gear, the two planet gear sets being rotatably mounted on a common planet carrier, and in that the first, major sun gear is rotationally fixed on the torque distribution output shaft, the second, minor sun gear is rotationally fixed on the one flange shaft and the common planet carrier is rotationally fixed on the other flange shaft.

14. The drive device according to claim 3, wherein the axle differential comprises: a Ravigneaux set, in which planet gears of a first planet gear set mesh with both a radially outer ring gear, forming the input end of the axle differential, with planet gears of a second planet gear set, respectively, and with a first, major sun gear, and in that the planet gears of the second planet gear set mesh with a second, minor sun gear, the two planet gear sets being rotatably mounted on a common planet carrier, and in that the first, major sun gear is rotationally fixed on the torque distribution output shaft, the second, minor sun gear is rotationally fixed on the one flange shaft and the common planet carrier is rotationally fixed on the other flange shaft.

15. The drive device according to claim 4, wherein the axle differential comprises: a Ravigneaux set, in which planet gears of a first planet gear set mesh with both a radially outer ring gear, forming the input end of the axle differential, with planet gears of a second planet gear set, respectively, and with a first, major sun gear, and in that the planet gears of the second planet gear set mesh with a second, minor sun gear, the two planet gear sets being rotatably mounted on a common planet carrier, and in that the first, major sun gear is rotationally fixed on the torque distribution output shaft, the second, minor sun gear is rotationally fixed on the one flange shaft and the common planet carrier is rotationally fixed on the other flange shaft.

16. The drive device according to claim 5, wherein the axle differential comprises: a Ravigneaux set, in which planet gears of a first planet gear set mesh with both a radially outer ring gear, forming the input end of the axle differential, with planet gears of a second planet gear set, respectively, and with a first, major sun gear, and in that the planet gears of the second planet gear set mesh with a second, minor sun gear, the two planet gear sets being rotatably mounted on a common planet carrier, and in that the first, major sun gear is rotationally fixed on the torque distribution output shaft, the second, minor sun gear is rotationally fixed on the one flange shaft and the common planet carrier is rotationally fixed on the other flange shaft.

17. The drive device according to claim 3, wherein the output planetary gearing further comprises a sun gear, which meshes with its planet gears and can be coupled by a hybrid shift element to the planet carrier of the input planetary gearing or be released from it, and in that, when the first hybrid mode is engaged, the planet carrier of the input planetary gearing is coupled in driving manner to a sun gear of the output planetary gearing by the hybrid shift element, so that a load path is formed from the additional drive machine to the input planetary gearing, on the planet carrier of which a power branching occurs, during which a first partial path continues across the planet gears and the ring gear of the input planetary gearing to the ring gear shaft; and then to the intermediate planetary gearing, from which the first partial path continues across the connecting shaft to the planet carrier of the output planetary gearing and to the gearing output shaft, and a second partial path continues from the planet carrier of the input planetary gearing across the engaged hybrid shift element to the sun gear of the output planetary gearing, and a power addition occurs on the planet carrier of the output planetary gearing, during which the first and second partial paths are combined.

18. The drive device according to claim 4, wherein the output planetary gearing further comprises a sun gear, which meshes with its planet gears and can be coupled by a hybrid shift element to the planet carrier of the input planetary gearing or be released from it, and in that, when the first hybrid mode is engaged, the planet carrier of the input planetary gearing is coupled in driving manner to a sun gear of the output planetary gearing by the hybrid shift element, so that a load path is formed from the additional drive machine to the input planetary gearing, on the planet carrier of which a power branching occurs, during which a first partial path continues across the planet gears and the ring gear of the input planetary gearing to the ring gear shaft; and then to the intermediate planetary gearing, from which the first partial path continues across the connecting shaft to the planet carrier of the output planetary gearing and to the gearing output shaft, and a second partial path continues from the planet carrier of the input planetary gearing across the engaged hybrid shift element to the sun gear of the output planetary gearing, and a power addition occurs on the planet carrier of the output planetary gearing, during which the first and second partial paths are combined.

19. The drive device according to claim 5, wherein the output planetary gearing further comprises a sun gear, which meshes with its planet gears and can be coupled by a hybrid shift element to the planet carrier of the input planetary gearing or be released from it, and in that, when the first hybrid mode is engaged, the planet carrier of the input planetary gearing is coupled in driving manner to a sun gear of the output planetary gearing by the hybrid shift element, so that a load path is formed from the additional drive machine to the input planetary gearing, on the planet carrier of which a power branching occurs, during which a first partial path continues across the planet gears and the ring gear of the input planetary gearing to the ring gear shaft; and then to the intermediate planetary gearing, from which the first partial path continues across the connecting shaft to the planet carrier of the output planetary gearing and to the gearing output shaft, and a second partial path continues from the planet carrier of the input planetary gearing across the engaged hybrid shift element to the sun gear of the output planetary gearing, and a power addition occurs on the planet carrier of the output planetary gearing, during which the first and second partial paths are combined.

20. The drive device according to claim 6, wherein the output planetary gearing further comprises a sun gear, which meshes with its planet gears and can be coupled by a hybrid shift element to the planet carrier of the input planetary gearing or be released from it, and in that, when the first hybrid mode is engaged, the planet carrier of the input planetary gearing is coupled in driving manner to a sun gear of the output planetary gearing by the hybrid shift element, so that a load path is formed from the additional drive machine to the input planetary gearing, on the planet carrier of which a power branching occurs, during which a first partial path continues across the planet gears and the ring gear of the input planetary gearing to the ring gear shaft; and then to the intermediate planetary gearing, from which the first partial path continues across the connecting shaft to the planet carrier of the output planetary gearing and to the gearing output shaft, and a second partial path continues from the planet carrier of the input planetary gearing across the engaged hybrid shift element to the sun gear of the output planetary gearing, and a power addition occurs on the planet carrier of the output planetary gearing, during which the first and second partial paths are combined.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) An exemplary embodiment of the invention is described below with the aid of the enclosed figures.

(2) There are shown:

(3) FIG. 1 in a schematic representation, a drive device for a vehicle rear axle of a two-track vehicle;

(4) FIG. 2 respective view corresponding to FIG. 1 with highlighted drive torque flow with the first hybrid gear engaged.

(5) FIG. 3 respective view corresponding to FIG. 1 with highlighted drive torque flow with the second hybrid gear engaged.

(6) FIG. 4 respective views corresponding to FIG. 1 with highlighted drive torque flow with the torque distribution gear engaged.

DETAILED DESCRIPTION

(7) FIG. 1 shows, roughly schematically, a gearing structure of a drive device for a vehicle rear axle HA of a two-track vehicle. The drive device shown in FIG. 1 may be part of an all-wheel drive, in which a front-end internal combustion engine (not shown) as the primary drive machine drives the front wheels of the vehicle across a transmission as well as a central differential and a front axle differential. The central differential can be connected in driving manner across a Cardan shaft and across a bevel gear 4 to the input end 13 of a rear axle differential 3. Between the bevel gear 4 and the input end 13 of the rear axle differential 3 there is connected a clutch K, by which the rear axle HA can be decoupled from the drive of the Cardan shaft.

(8) The rear axle differential 3 is coupled at its output, in driving manner, to the rear wheels 9 of the vehicle's rear axle HA across flange shafts 5, 7 arranged on both sides. In FIG. 1, the rear axle differential 3 is a planetary differential with a Ravigneaux gear set, in which planet gears 11 of a first planet gear set mesh with both a radially outer ring gear 13, forming the input end of the axle differential 3, and also with planet gears 15 of a second planet gear set. Furthermore, the planet gears 11 of the first planet gear set are in toothed engagement with a first, major sun gear 17. The planet gears 15 of the second planet gear set, on the other hand, are in toothed engagement with a second, minor sun gear 19. Both planet gear sets are rotatably mounted on a common planet carrier 21, which is rotationally fixed on a flange shaft away from the gearing. On the other hand, the second, minor sun gear 19 is rotationally fixed on the flange shaft 7 at the gearing side, while the first, major sun gear is rotationally fixed on a torque distribution output shaft 23, leading to the superimposing gear 25.

(9) The rear axle HA comprises an already mentioned superimposing gear 25 as well as an electric machine 26. The superimposing gear 25 can be operated in a hybrid mode or in a torque distribution mode (that is, electronic torque vectoring or cross lock function), as will be described later on. In the hybrid mode, a drive torque generated by the electric machine 26 is coupled, evenly distributed across the superimposing gear 25 and the rear axle differential 3, to both flange shafts 5, 7. The hybrid mode can be implemented as a pure electric motor or in combination of the electric machine 26 with the internal combustion engine (for example for a boost function).

(10) In the torque distribution mode, the drive torque generated by the electric machine 26 is taken not only to the input end (ring gear 13) of the axle differential 3, but also across the superimposing gear 25 to the first, major sun gear 17 of the axle differential 3, in order to change a torque distribution on the two rear wheels 9. The channeling to the first, major sun gear 17 occurs across a torque distribution flange 24 of the superimposing gear 25, mounted on the torque distribution output shaft 23. The torque distribution between the vehicle wheels 9 will occur according to the magnitude and the rotary direction of the drive torque generated by the electric machine 26.

(11) In the following, the gearing structure of the superimposing gear 25 will be explained with the aid of FIG. 1: accordingly, the superimposing gear 25 comprises an input planetary gearing PG1 coupled in driving manner to the electric machine 26, an output planetary gearing PG3 connected in driving manner to the axle differential 3, and an intermediate planetary gearing PG2 connected between them. The three planetary gearings PG1, PG2, PG3 are arranged in succession, coaxially to the flange shaft 7. The output planetary gearing PG3 is positioned vehicle-inward in the vehicle transverse direction y and immediately next to the axle differential 3, while the intermediate planetary gearing PG2 is situated vehicle-outward. The shift elements SH1, SH2, STV to be described later on are positioned on the vehicle-outward side of the intermediate planetary gearing PG2 and assembled to form a shifting group.

(12) The input planetary gearing PG1 has as its input element a sun gear 31, which is rotationally fixed to a gearing input shaft 33 driven by the electric machine 26.

(13) In regard to a torque transformation, the electric machine 26 in FIG. 1 is coupled by a reduction stage 35 (that is, a spur gear stage) to the gearing input shaft 33. The electric machine 26 is thus situated axially parallel to the flange shaft 7 in regard to a package optimization.

(14) The sun gear 31 of the input planetary gearing PG1 meshes with planet gears 37, which are rotatably mounted on a planet carrier 39. Moreover, the and planet gears are in tooth engagement with a ring gear 41. The ring gear 41 together with a ring gear 43 of the intermediate planetary gearing PG2 is rotationally fixed on a ring gear shaft 45. The ring gear 43 of the intermediate planetary gearing PG2 meshes with planet gears 47 which are rotatably mounted on a planet carrier 49 and which are in tooth engagement with a sun gear 51, fixed on the housing.

(15) The planet carrier 39 of the input planetary gearing PG1 is connected to a radially outward shifting shaft 53, which bounds off a radially inward design space, in which both the input and the intermediate planetary gearing PG1, PG2 are arranged. At a shaft end of the shifting shaft 53 situated axially away from the input planet carrier there are positioned a first hybrid shift element SH1, a second hybrid shift element SH2 and a torque distribution shift element STV.

(16) The output-end planetary gearing PG3 has as its output element a planet carrier 57, carrying planet gears 55, which is rotationally fixed by a hybrid output flange 59 to a gearing output shaft 61. This is connected in driving manner to the input end 13 of the axle differential 3. The output planetary gearing PG3 furthermore has a sun gear 65, meshing with its planet gears 55, being rotationally fixed to a sun gear shaft 67. Its shaft end away from the sun gear 65 can be coupled by the first hybrid shift element SH1 to the shifting shaft 53. The output planetary gearing PG3 furthermore has a ring gear 73, meshing with the planet gears 55 and fixed to the housing.

(17) Furthermore, the planet carrier 49 of the intermediate planetary gearing PG2 is rotationally fixed across a connecting shaft 69 to the planet carrier 57 of the output planetary gearing PG3. The planet carrier 57 of the output planetary gearing PG3 furthermore has a hybrid output flange 61, which is rotationally fixed to the gearing output shaft 63.

(18) In order to explain the functioning of the drive device, a driving situation will be described with the aid of FIG. 2, in which the first hybrid gear H1 is engaged. In this case, the first hybrid gear H1 is designed, for example, as a starting gear, which can be engaged at low driving speeds. When the first hybrid gear H1 is engaged, the planet carrier 39 des input planetary gearing PG1 is coupled in driving manner across the first hybrid shift element SH1 to the sun gear 65 of the output planetary gearing PG3. This forms a load path from the electric machine 26 to the input planetary gearing PG1, on whose planet carrier 39 a power branching occurs into a first partial path and a second partial path. The first partial path goes across the planet gears 37 and the ring gear 41 of the input planetary gearing PG1 to the ring gear shaft 45 and then to the intermediate planetary gearing PG2. From here, the first partial path goes across the connecting shaft 69 to the planet carrier 57 of the output planetary gearing PG3 and to the gearing output shaft 63. The second partial path goes from the planet carrier 39 of the input planetary gearing PG1 across the engaged hybrid shift element SH1 to the sun gear 65 of the output planetary gearing PG3. A power addition occurs on the planet carrier 57 of the output planetary gearing PG3, during which the first and second partial paths are combined.

(19) FIG. 3 shows another driving situation, in which the superimposing gear 25 is operated with engaged second hybrid-Gear H2, by contrast with FIG. 2. In this case, the planet carrier 39 of the input planetary gearing PG1 is connected by means of the second hybrid shift element SH2 firmly to the housing. In this way, a load path is formed from the electric machine 26 across the input planetary gearing PG1 to the intermediate planetary gearing PG2 and then across the gearing output shaft 63 to the input end 13 of the axle differential 3.

(20) In FIG. 4, the superimposing gear 25 is operated not in a hybrid mode, but instead in a torque distribution mode. This mode is activated, for example, when negotiating a curve, in order to accomplish a torque difference between the flange shafts 5, 7. In the torque distribution mode, the torque distribution gear TV is engaged, so that the torque distribution shaft 23 is connected in driving manner by means of the torque distribution shift element STV to the planet carrier 39 of the input planetary gearing PG1. In this way, a load path is produced from the electric machine 26 to the input planetary gearing PG1, on whose planet carrier 39 a power distribution occurs into a first partial path and a second partial path. The first partial path goes across the ring gear 41 of the input planetary gearing PG1 and across the ring gear shaft 45 to the intermediate planetary gearing PG2. From here, the first partial path proceeds across the planet carrier 49 of the intermediate planetary gearing PG2 to the gearing output shaft 63. In this case, both the input and intermediate planetary gearing PG1, PG2 are incorporated in the load path, while the output planetary gearing PG3 turns freely and is not incorporated in the load path. The second partial path goes across the planet carrier 39 of the input planetary gearing PG1 and across the engaged torque distribution shift element STV to the torque distribution shaft 23.