Method for assembling a drive unit

Abstract

Drive units for a vehicle having an electric machine and a transmission device are disclosed, as well as methods for assembling the drive units. The method may include mounting the transmission device in a transmission housing; passing an assembly mandrel axially through an aperture in the transmission housing and through a pinion shaft, which is designed as a hollow shaft and is rotatably mounted in the transmission housing; and centering a rotor shaft, which is designed at least partially as a hollow shaft, on the assembly mandrel. A rotor of the electric machine may be pushed axially onto the rotor shaft; the rotor shaft may be inserted axially into the pinion shaft, wherein a set of splines on the rotor shaft engages in a set of splines on the pinion shaft; a stator of the electric machine may be pushed axially onto the rotor of the electric machine and fixing the stator on the transmission housing; and the assembly mandrel may be removed and the aperture in the transmission housing may be closed with a closure cover.

Claims

1. A method for assembling a drive unit for a vehicle, wherein the drive unit has an electric machine and a transmission device, the method comprising: mounting the transmission device in a transmission housing; passing an assembly mandrel axially through an aperture in the transmission housing and through a pinion shaft, which is designed as a hollow shaft and is rotatably mounted in the transmission housing; centering a rotor shaft, which is designed at least partially as a hollow shaft, on the assembly mandrel; pushing a rotor of the electric machine axially onto the rotor shaft; inserting the rotor shaft axially into the pinion shaft, wherein a set of splines on the rotor shaft engages in a set of splines on the pinion shaft; pushing a stator of the electric machine axially onto the rotor of the electric machine and fixing the stator on the transmission housing; and removing the assembly mandrel and closing the aperture in the transmission housing with a closure cover.

2. A drive unit for a vehicle comprising: an electric machine having a stator and a rotor as well as a transmission device arranged in a transmission housing, wherein a transmission input shaft for torque transmission is arranged between the electric machine and the transmission device, wherein the rotor is arranged radially on a first end of the transmission input shaft and a pinion shaft is arranged radially on a second end of the transmission input shaft, wherein a respective set of splines for connecting the transmission input shaft to the pinion shaft for conjoint rotation is formed radially between the transmission input shaft and the pinion shaft, wherein the second end of the transmission input shaft is hollow, and wherein the transmission housing has an aperture adjacent to the second end of the transmission shaft and a closure cover for closing the aperture is arranged in the aperture.

3. The drive unit as claimed in claim 2, wherein the stator is accommodated in a housing flange and the housing flange has a bearing location, which is provided for the purpose of accommodating a bearing element for supporting the first end of the transmission input shaft.

4. The drive unit as claimed in claim 2, wherein the pinion shaft is rotatably mounted in the transmission housing by at least one first and second bearing element, wherein the first bearing element is designed as a fixed bearing and wherein the second bearing element is designed as a floating bearing.

5. The drive unit as claimed in claim 4, wherein a spring element for producing an elastic preload is arranged axially between the transmission housing and an outer race of a bearing element.

6. The drive unit as claimed in claim 4, wherein the respective bearing element is designed as an angular ball bearing.

7. The drive unit as claimed in claim 2, wherein the pinion shaft has a first and a second raceway on an outer circumferential surface and the respective raceway is provided for the purpose of accepting a respective rolling element row of a respective bearing element.

8. The drive unit as claimed in claim 2, wherein the transmission device has a first and a second output shaft and each output shaft is provided for connection to a wheel of a vehicle axle.

9. The drive unit as claimed in claim 2, wherein the aperture is formed coaxially with the pinion shaft.

10. A drive unit for a vehicle, the drive unit assembled by: mounting a transmission device in a transmission housing; passing an assembly mandrel axially through an aperture in the transmission housing and through a pinion shaft, which is designed as a hollow shaft and is rotatably mounted in the transmission housing; centering a rotor shaft, which is designed at least partially as a hollow shaft, on the assembly mandrel; pushing a rotor of an electric machine axially onto the rotor shaft while the assembly mandrel is extended through the aperture and pinion shaft; inserting the rotor shaft axially into the pinion shaft, wherein a set of splines on the rotor shaft engages in a set of splines on the pinion shaft; pushing a stator of the electric machine axially onto the rotor of the electric machine and fixing the stator on the transmission housing; and removing the assembly mandrel after inserting the rotor shaft into the pinion shaft and closing the aperture in the transmission housing with a closure cover; wherein the drive unit comprises the stator, the rotor, the transmission device, and the transmission housing, wherein a transmission input shaft arranged between the electric machine and the transmission device comprises the rotor shaft and the pinion shaft, wherein the splines for connecting the rotor shaft and the pinion shaft are formed radially between the rotor shaft and the pinion shaft.

11. The drive unit as claimed in claim 10, wherein the stator is accommodated in a housing flange and the housing flange has a bearing location, which is provided for the purpose of accommodating a bearing element for supporting the rotor shaft.

12. The drive unit as claimed in claim 10, wherein the pinion shaft is rotatably mounted in the transmission housing by at least one first and second bearing element, wherein the first bearing element is designed as a fixed bearing and wherein the second bearing element is designed as a floating bearing.

13. The drive unit as claimed in claim 12, wherein a spring element for producing an elastic preload is arranged axially between the transmission housing and an outer race of a bearing element.

14. The drive unit as claimed in claim 12, wherein the respective bearing element is designed as an angular ball bearing.

15. The drive unit as claimed in claim 10, wherein the pinion shaft has a first and a second raceway on an outer circumferential surface and the respective raceway is provided for the purpose of accepting a respective rolling element row of a respective bearing element.

16. The drive unit as claimed in claim 10, wherein the transmission device has a first and a second output shaft and each output shaft is provided for connection to a wheel of a vehicle axle.

17. The drive unit as claimed in claim 10, wherein the aperture is formed coaxially with the pinion shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further measures that improve the disclosure are explained in greater detail below together with the description of two example embodiments of the disclosure with reference to the three figures, in which identical or similar elements are provided with the same reference signs. Here:

(2) FIG. 1 shows a highly simplified schematic sectional view intended to illustrate the construction of a drive unit according to the disclosure,

(3) FIG. 2 shows a schematic sectioned detail view intended to illustrate the construction of and support for the transmission input shaft in accordance with a first illustrative embodiment, and

(4) FIG. 3 shows a schematic sectioned detail view intended to illustrate the construction of and support for the transmission input shaft in accordance with a second illustrative embodiment.

DETAILED DESCRIPTION

(5) According to FIG. 1, a drive unit according to the disclosure for a motor vehicle—not shown here—has an electric machine 1 with a stator 9 and a rotor 7 as well as a transmission device 2. The transmission device 2 is arranged in a transmission housing 3. The electric machine 1 is furthermore also arranged in a section of the transmission housing 3 provided for this purpose, wherein the rotor 7 and the stator 9 are illustrated in an exploded view. In particular, the stator 9 is furthermore accommodated in a housing flange 12, wherein the housing flange 12 has a bearing location, which is provided for the purpose of accommodating a third bearing element 13 for supporting a rotor shaft 6. The rotor 7 is arranged for conjoint rotation on an outer circumferential surface of the rotor shaft 6 and is provided for the purpose of producing, together with the stator 9, a driving output, which is fed into the transmission device 2 via the rotor shaft 6 for distribution between two output shafts 17a, 17b of the transmission device 2. The two output shafts 17a, 17b are formed parallel to the rotor shaft 6. The respective output shaft 17a, 17b is furthermore connected to a respective wheel—not shown here—on a vehicle axle. Thus, the drive unit according to the disclosure is provided for an electric axle drive of the motor vehicle.

(6) A pinion shaft 5 designed as a hollow shaft is furthermore rotatably mounted in the transmission housing 3. Together with the pinion shaft 5 arranged radially thereon, the rotor shaft 6 forms a transmission input shaft 11. The transmission input shaft 11 is provided for torque transmission between the electric machine 1 and the transmission device 2 and thus serves as an interface between the electric machine 1 and the transmission device 2.

(7) FIG. 2 shows a detail from FIG. 1. According to FIG. 2, a respective set of splines 8a, 8b for connecting the rotor shaft 6 and the pinion shaft 5 for conjoint rotation is formed radially between the rotor shaft 6 and the pinion shaft 5. The pinion shaft 5 is rotatably mounted in the transmission housing 3 by a first and second bearing element 13a, 13b, wherein the first bearing element 13a is designed as a fixed bearing and wherein the second bearing element 13b is designed as a floating bearing. The first and second bearing elements 13a, 13b each comprise an outer race 15a, 15b, which is arranged non-rotatably in the transmission housing 3, an inner race 18a, 18b, which is arranged for conjoint rotation on the pinion shaft 5, and a respective rolling element row 19a, 19b, which is arranged radially between the respective outer race 15a, 15b and the respective inner race 18a, 18b and is guided by a respective cage 20a, 20b. In particular, the respective bearing element 13a, 13b may be designed as an angular ball bearing. A spring element 16 for producing an elastic pre-load is arranged axially between the transmission housing 3 and an outer race 15b of bearing element 13b. In particular, the spring element 16 may be designed as a diaphragm spring.

(8) FIG. 3 shows a second embodiment of the drive unit according to the disclosure. This differs from the embodiment shown in FIG. 2 in that the pinion shaft 5 has a first and a second raceway 14a, 14b on an outer circumferential surface, wherein the respective raceway 14a, 14b is provided for the purpose of accepting a respective rolling element row 19a′, 19b′ of a respective bearing element 13a′, 13b′. Consequently, according to the embodiment in FIG. 3, the respective inner race 18a, 18b, which is illustrated in FIG. 2, is eliminated. Thus, the respective rolling element row 19a′, 19b′ is arranged radially between the pinion shaft 5 and a respective outer race 15a′, 15b′. The respective bearing element 13a′, 13b′ is designed as an angular ball bearing. A spring element 16 for producing an elastic preload is arranged axially between the transmission housing 3 and the outer race 15b′ of the bearing element 13b′.

(9) According to both FIGS. 2 and 3, the transmission housing 3 has an aperture 4, wherein a closure cover 10 for closing the aperture 4 is arranged in the aperture 4. The aperture 4 is formed coaxially with the pinion shaft 5 and is used for assembling the drive unit.

(10) The method for assembling the drive unit may generally include seven assembly steps. In a first assembly step, the transmission device 2 is mounted in the transmission housing 3. This gives rise, in particular, to the advantage that the transmission device 2 can be tested before the installation of the electric machine 1. After this, an assembly mandrel 21 is passed through the aperture 4 in the transmission housing 3 and through the pinion shaft 5, which is designed as a hollow shaft. In a third assembly step, the rotor shaft 6, which is designed at least partially as a hollow shaft, is centered on the cylindrical assembly mandrel. During this process, the assembly mandrel 21 penetrates at least partially into the rotor shaft 6. In a fourth step, the rotor 7 is pushed axially onto the rotor shaft 6. As an alternative, the rotor 7 can already be arranged on the rotor shaft 6, with the result that pushing the rotor 7 axially onto the rotor shaft 6 during assembly may be eliminated. After this, the rotor shaft 6 is inserted axially into the pinion shaft 5, wherein the set of splines 8a on the rotor shaft 6 engages in the set of splines 8b on the pinion shaft 5. In a sixth assembly step, the stator 9 of the electric machine 1 is pushed axially onto the rotor 7 of the electric machine 1. The stator 9 is fixed on the transmission housing 3, wherein, in particular, the housing flange 12 in which the stator 9 is accommodated is screwed to the transmission housing 2. Finally, the assembly mandrel 21 is removed and the aperture 4 in the transmission housing 3 is closed by the closure cover 10.

LIST OF REFERENCE SIGNS

(11) 1 electric machine

(12) 2 transmission device

(13) 3 transmission housing

(14) 4 aperture

(15) 5 pinion shaft

(16) 6 rotor shaft

(17) 7 rotor

(18) 8a, 8b set of splines

(19) 9 stator

(20) 10 closure cover

(21) 11 transmission input shaft

(22) 12 housing flange

(23) 13a-13c bearing element

(24) 13a′, 13b′ bearing element

(25) 14a, 14b raceway

(26) 15a, 15b outer race

(27) 15a′, 15b′ outer race

(28) 16 spring element

(29) 17a, 17b output shaft

(30) 18a, 18b inner race

(31) 19a, 19b rolling element row

(32) 19a′, 19b′ rolling element row

(33) 20a, 20b cage

(34) 21 assembly mandrel