Drive device for a motor vehicle

Abstract

A drive device includes a drive machine, such as an electric motor, gear reduction planetary gear sets, and a differential. One of the gear reduction planetary gear sets utilizes multi-step planetary gears. The differential is a spur gear differential. To reduce axial length, one of the gearwheels of each multi-step planetary gears axially overlaps with planetary gears of the spur gear differential.

Claims

1. A drive device for a motor vehicle, comprising a drive machine which is operatively connected via a drive shaft to a transmission device, the transmission device having a first planetary set with a plurality of planetary gears, a multi-step planetary set with a plurality of multi-step planetary gears, and a differential transmission with a second and third planetary set, each of the first, second, and third planetary sets having a plurality of planetary gears, the planetary gears of the first planetary set being arranged rotatably on a first planetary carrier and being in tooth engagement radially between a first sun and a first internal gear, each multi-step planetary gear having a first and a second gearwheel which are connected fixedly to one another so as to rotate together, the multi-step planetary gears being arranged rotatably on a second planetary carrier, the first gearwheel being in tooth engagement with a second sun, and the second gearwheel being in tooth engagement with a second internal gear, and the first planetary carrier being connected fixedly to the second sun so as to rotate with it, and the first internal gear being fixed on a housing in a stationary manner, the respective planetary gears of the second and third planetary set, furthermore, being mounted rotatably on the second planetary carrier, the planetary gears of the second planetary set being in tooth engagement with a third sun, and the planetary gears of the third planetary set being in tooth engagement with a fourth sun, and the planetary gears of the second planetary set being in tooth engagement in pairs with the planetary gears of the third planetary set.

2. The drive device of claim 1, wherein the drive machine is an electric machine with a stator and a rotor.

3. The drive device of claim 1, wherein the third sun is adapted for fixation to a first output shaft so as to rotate therewith, and the fourth sun is adapted for fixation to a second output shaft so as to rotate therewith.

4. The drive device of claim 3, wherein the drive shaft is arranged coaxially with respect to the first and second output shafts, the drive shaft being a hollow shaft, and the first output shaft being routed through the drive shaft.

5. The drive device of claim 1, wherein the second internal gear is fixed on the housing in a stationary manner.

6. The drive device of claim 1, wherein the planetary gears of the third planetary set extend at least partially in an axial installation space of the second gearwheel of the multi-step planetary gears.

7. The drive device of claim 1, wherein a static transmission ratio of the first planetary set is between 2.7 and 3.5.

8. The drive device of claim 1, wherein a static transmission ratio of the multi-step planetary set is between 4 and 7.5.

9. A drive device comprising: a first planetary gearset having a first sun gear fixed to a driveshaft, a first carrier, a first ring gear held against rotation, and a plurality of first planet gears supported for rotation with respect to the first carrier and meshing with the first sun gear and with the first ring gear; a second planetary gearset having a second sun gear fixed to the first carrier, a second carrier, a second ring gear held against rotation, and a plurality of multi-step planet gears, each multi-step planet gears having a first gearwheel fixed to a second gearwheel, each first gearwheel meshing with the second sun gear, each second gearwheel meshing with the second ring gear; and a differential.

10. The drive device of claim 9 further comprising an electric motor having a stator and a rotor fixed to the driveshaft.

11. The drive device of claim 9 wherein the differential comprises: a third sun gear fixed to a first output shaft; a fourth sun gear fixed to a second output shaft; a plurality of third planet gears supported for rotation with respect to the second carrier and meshing with the third sun gear; and a plurality of fourth planet gears supported for rotation with respect to the second carrier and meshing with the fourth sun gear, each fourth planet gear also meshing with one of the third planet gears.

12. The drive device of claim 11 wherein the driveshaft is hollow and the first output shaft extends through the driveshaft.

13. The drive device of claim 11 wherein the second gearwheels overlap axially with the third planet gears.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further measures will be shown in greater detail in the following text together with the description of one preferred exemplary embodiment on the basis of the two figures, in which:

(2) FIG. 1 shows a simplified diagrammatic illustration of a drive device having a transmission device, and

(3) FIG. 2 shows a diagrammatic exploded illustration of the partially shown transmission device according to FIG. 1.

DETAILED DESCRIPTION

(4) According to FIG. 1, a drive device for a motor vehicle (not shown here) has a drive machine 1 and a transmission device 3. The drive machine 1 is configured as an electric machine and has a stator 13 which is fixed on the housing and a rotor 14 which is arranged movably therein. In the present case, the transmission device 3 is flange-connected to the drive machine 1. Drive power of the drive machine 1 is introduced into the transmission device 3 via a drive shaft 2 which is arranged between the drive machine 1 and the transmission device 3. The transmission device 3 comprises a first planetary set 4a with a plurality of planetary gears 5a, a multi-step planetary set 9 with a plurality of multi-step planetary gears 10, and a differential transmission 16 with a second and third planetary set 4b, 4c which in each case have a plurality of planetary gears 5b, 5c. On account of the sectional illustration, only one planetary gear 5a of the first planetary set 4a, one multi-step planetary gear 10 of the multi-step planetary set 9, and in each case one planetary gear 5b, 5c of the second and third planetary set 4b, 4c are shown. The planetary gears 5a of the first planetary set 4a are arranged rotatably on a first planetary carrier 6a, and are in tooth engagement radially between a first sun 7a and a first internal gear 8a. The first internal gear 8a is fixed on a housing 12 of the transmission device 3 in a stationary manner. Each multi-step planetary gear 10 has a first and a second gearwheel 11a, 11b which are connected fixedly to one another so as to rotate together, the multi-step planetary gears 10 being arranged rotatably on a second planetary carrier 6b. The first gearwheel 11a is in tooth engagement with a second sun 7b, and the second gearwheel 11b is in tooth engagement with a second internal gear 8b. The first gearwheel 11a has a greater diameter than the second gearwheel 11b. The first planetary carrier 6a is connected fixedly to the second sun 7b so as to rotate with it.

(5) The respective planetary gears 5b, 5c of the second and third planetary set 4b, 4c are mounted rotatably on the second planetary carrier 6b. The planetary gears 5b of the second planetary set 4b are in tooth engagement with a third sun 7c, and the planetary gears 5c of the third planetary set 4c are in tooth engagement with a fourth sun 7d. Furthermore, the planetary gears 5b of the second planetary set 4b are in tooth engagement in pairs with the planetary gears 5c of the third planetary set 4c. The third sun 7c is connected fixedly to a first output shaft 15a so as to rotate with it, and the fourth sun 7d is connected fixedly to a second output shaft 15b so as to rotate with it. The differential transmission 16 is configured as a spur gear differential. The drive shaft 2 is arranged coaxially with respect to the two output shafts 15a, 15b, the drive shaft 2 being configured as a hollow shaft, and the first output shaft 15a being routed through the drive shaft 2. The two output shafts 15a, 15b belong to a drive axle of the motor vehicle. As a consequence, the drive device is provided as an electric drive axle of the motor vehicle. The static transmission ratio at the first planetary set 4a is advantageously between 2.7 and 3.5, the static transmission ratio at the multi-step planetary set 9 advantageously being between 4 and 7.5. As a consequence, the illustrated construction of the transmission device 3 realizes a relatively high transmission ratio and power density.

(6) According to FIG. 2, the transmission device 3 from FIG. 1 is shown partially. It is noted that the first planetary set 4a and the first sun 7a and the first internal gear 8a are not shown. The second sun 7b is in tooth engagement with the first gearwheel 11a of the multi-step planetary gear 10 which is received on the second planetary carrier 6b. The second gearwheel 11b of the multi-step planetary gear 10 is in tooth engagement with the second internal gear 8b which is fixed on the housing. The way is particularly clearly apparent from FIG. 2, in which the respective multi-step planetary gears 10 of the multi-step planetary set 9 and the respective planetary gears 5b, 5c of the second and third planetary set 4b, 4c are mounted rotatably on the second planetary carrier 6b. At this point, in order to explain this arrangement, reference is made, in particular, to the description of the figures in paragraphs [0019] to [0024] and to FIGS. 1 to 4 of document DE 10 2015 214 031 A1 in respect of the prior art which was cited at the outset. The transmission arrangement from DE 10 2015 214 031 A1 is identical and is therefore structurally identical to the multi-step planetary set 9 which is shown in FIG. 2 with the differential transmission 16 which is connected to it. It is noted, in particular, that the planetary gears 5c of the third planetary set 4c extend at least partially in an axial installation space of the second gearwheel 11b of the multi-step planetary gears 10. Together with the differential transmission 16, the multi-step planetary set 9 forms a particularly compact unit.

LIST OF DESIGNATIONS

(7) 1 Drive machine 2 Drive shaft 3 Transmission device 4a, 4b, 4c Planetary set 5a, 5b, 5c Planetary gear 6a, 6b Planetary carrier 7a, 7b, 7c, 7d Sun 8a, 8b Internal gear 9 Multi-step planetary set 10 Multi-step planetary gear 11a, 11b Gearwheel 12 Housing 13 Stator 14 Rotor 15a, 15b Output shaft 16 Differential transmission