US-12620860-B2 - Drive unit for a vehicle

US12620860B2US 12620860 B2US12620860 B2US 12620860B2US-12620860-B2

Abstract

A drive unit ( 10 ) for a vehicle including an electric machine ( 12 ) having a rotor shaft ( 14 ) and a transmission ( 16 ) with a transmission shaft ( 18 ). The transmission shaft ( 18 ) is rotatably mounted in a first housing section ( 22 ) with a first rolling bearing ( 20 ) and the rotor shaft ( 14 ) is rotatably mounted in a second housing section ( 26 ) with a rolling second bearing ( 24 ). The transmission shaft ( 18 ) and the rotor shaft ( 14 ) are coupled to one another in a rotationally fixed manner. A third rolling bearing ( 28 ), which has an inner bearing ring ( 30 ), is arranged at the transition between the transmission shaft ( 18 ) and the rotor shaft ( 14 ), The inner bearing ring ( 30 ) is in contact with the rotor shaft ( 14 ) and the transmission shaft ( 18 ) with its inner surface ( 32 ).

Inventors

Johannes Daniel Kocherscheidt
Timo Kiekbusch
Philipp Jung

Assignees

ROBERT BOSCH GMBH

Dates

Publication Date: 20260505
Application Date: 20210726

Claims (8)

1 . A drive unit ( 10 ) for a vehicle comprising: an electric machine ( 12 ) having a rotor shaft ( 14 ) and a transmission ( 16 ) having a transmission shaft ( 18 ), wherein the transmission shaft ( 18 ) is rotatably mounted in a first housing section ( 22 ) by a first rolling bearing ( 20 ) and the rotor shaft ( 14 ) is rotatably mounted in a second housing section ( 26 ) by a second rolling bearing ( 24 ), wherein the transmission shaft ( 18 ) and the rotor shaft ( 14 ) are coupled to one another in a rotationally fixed manner, wherein a third rolling bearing ( 28 ) which comprises an inner bearing ring ( 30 ) is disposed at a transition between the transmission shaft ( 18 ) and the rotor shaft ( 14 ), wherein an inner surface ( 32 ) of the inner bearing ring ( 30 ) abuts the rotor shaft ( 14 ) and the transmission shaft ( 18 ), wherein the third rolling bearing ( 28 ) is seated on the transmission shaft ( 18 ), wherein the inner bearing ring ( 30 ) abuts a radial projection ( 38 ) on a side facing away from the rotor shaft ( 14 ), and wherein the radial projection ( 38 ) is formed by a radially projecting shaft shoulder of the transmission shaft ( 18 ).
2 . The drive unit ( 10 ) according to claim 1 , wherein the rotor shaft ( 14 ) abuts the inner surface ( 32 ) of the inner bearing ring ( 30 ) of the third rolling bearing ( 28 ) with an outer peripheral surface ( 41 ), wherein the rotor shaft ( 14 ) is supported axially on the inner bearing ring ( 30 ) of the third rolling bearing ( 28 ) or on the transmission shaft ( 18 ) with a radial shoulder ( 44 ).
3 . The drive unit ( 10 ) according to claim 1 , wherein the third rolling bearing ( 28 ) comprises an axially extended inner bearing ring ( 30 ) which projects axially from the third rolling bearing ( 28 ).
4 . The drive unit ( 10 ) according to claim 3 , wherein the third rolling bearing ( 28 ) comprises a shoulder ( 60 ) having an enlarged inner diameter on the inner bearing ring ( 30 ), wherein the rotor shaft ( 14 ) abuts the inner bearing ring ( 30 ) with an outer peripheral surface ( 41 ) in this shoulder ( 60 ).
5 . The drive unit ( 10 ) according to claim 1 , wherein the rotor shaft ( 14 ) comprises a step ( 42 ) having a reduced outer diameter, wherein the inner surface ( 32 ) of the inner bearing ring ( 30 ) of the third rolling bearing ( 28 ) abuts the rotor shaft ( 14 ) at this step ( 42 ).
6 . The drive unit ( 10 ) according to claim 1 , wherein the transmission shaft ( 18 ) is configured axially in sections or entirely as a hollow shaft.
7 . The drive unit ( 10 ) according to claim 1 , wherein the rotor shaft ( 14 ) and the transmission shaft ( 18 ) are connected to one another in a material-locking, form-locking and/or force-locking manner.
8 . A drive unit ( 10 ) for a vehicle comprising: an electric machine ( 12 ) having a rotor shaft ( 14 ) and a transmission ( 16 ) having a transmission shaft ( 18 ), wherein the transmission shaft ( 18 ) is rotatably mounted in a first housing section ( 22 ) by a first rolling bearing ( 20 ) and the rotor shaft ( 14 ) is rotatably mounted in a second housing section ( 26 ) by a second rolling bearing ( 24 ), wherein the transmission shaft ( 18 ) and the rotor shaft ( 14 ) are coupled to one another in a rotationally fixed manner, wherein a third rolling bearing ( 28 ) which comprises an inner bearing ring ( 30 ) is disposed at a transition between the transmission shaft ( 18 ) and the rotor shaft ( 14 ), wherein an inner surface ( 32 ) of the inner bearing ring ( 30 ) abuts the rotor shaft ( 14 ) and the transmission shaft ( 18 ), wherein the third rolling bearing ( 28 ) comprises an axially extended inner bearing ring ( 30 ) which projects axially from the third rolling bearing ( 28 ), wherein the third rolling bearing ( 28 ) comprises a shoulder ( 60 ) having an enlarged inner diameter on the inner bearing ring ( 30 ), and wherein the rotor shaft ( 14 ) abuts the inner bearing ring ( 30 ) with an outer peripheral surface ( 41 ) in this shoulder ( 60 ).

Description

BACKGROUND The invention relates to a drive unit for a vehicle. A drive unit for a vehicle is known from DE 10 2016 206 479 A1. This drive unit comprises an electric machine having a rotor shaft and a transmission device having a transmission input shaft which is double mounted and comprises an integral pinion, wherein the rotor shaft and the transmission input shaft are inserted into one another. For assembly, in which an assembly mandrel is used and the transmission device is mounted in the transmission housing first, a precise assembly sequence has to be observed. SUMMARY According to the invention, a drive unit for a vehicle is proposed, which comprises an electric machine having a rotor shaft and a transmission having a transmission shaft (separate from the rotor shaft). The transmission shaft is rotatably mounted in a first housing section by means of a first rolling bearing and the rotor shaft is rotatably mounted in a second housing section by means of a second rolling bearing. The transmission shaft and the rotor shaft are coupled to one another in a rotationally fixed manner, wherein a third rolling bearing which comprises an inner bearing ring is disposed at the (axial) transition between the transmission shaft and the rotor shaft, wherein the inner bearing ring abuts the rotor shaft and the transmission shaft with its inner surface. The transmission shaft and the rotor shaft are thus accommodated (axially in sections) in the inner ring of the third bearing, and the inner ring of the third rolling bearing supports the transmission shaft and the rotor shaft in radial direction. The two shafts can thus be centered directly in the third rolling bearing on the inner surface of the inner bearing ring. The electric machine and the transmission can consequently be assembled separately. This allows greater flexibility in the assembly sequence of the drive unit, since the electric machine can be built followed by the assembly of the transmission or the transmission can be built followed by the assembly of the electric machine. By centering the transmission shaft and the rotor shaft in the inner bearing ring, there is no need for additional centering elements (e.g., centering surface) to guide the two shafts toward one another. Guiding the shafts through the third rolling bearing moreover makes it possible to achieve higher running accuracy (lower coaxial tolerance) than when guiding the rotor shaft by means of the transmission shaft. The inner surface of the inner bearing ring can be an inner surface having an (axially) uniform inner diameter throughout or a stepped inner surface having different inner diameters. The first housing section can be a housing of the transmission (transmission housing). The second housing section can be a housing of the electric machine (motor housing). As already indicated, the rotor shaft and the transmission shaft are disposed coaxially with one another. The transmission shaft can be an input shaft of the transmission. The rotor shaft and the transmission shaft are configured separately from one another and are coupled to one another in a rotationally fixed manner during assembly of the drive unit. The separate configuration of the transmission shaft and the rotor shaft makes a fit-for-purpose selection of the materials of the shafts possible. The shafts can furthermore be machined separately and, if necessary, heat treated separately (lower masses of the shafts than in the case of a one-piece configuration). Greater flexibility can also be achieved in the configuration of the running gear diameter, the seal diameter, the bearing diameter or a parking lock connection. The first rolling bearing can be disposed on the end of the transmission shaft facing away from the rotor shaft. The second rolling bearing can be disposed on the end of the rotor shaft facing away from the transmission shaft. The third rolling bearing can be disposed axially between the first and second rolling bearing. The transmission shaft can be toothed for torque transmission, for example to a further transmission shaft, for example by a gear mounted on the transmission shaft or a toothing configured or, for example cut, in the transmission shaft. The drive unit can comprise other components. Thus, the electric machine can comprise a rotor that is coupled to the rotor shaft in a rotationally fixed manner. The electric machine can also comprise a stator that interacts electromagnetically with the rotor. The transmission can be a single-stage or multi-stage transmission, for example a spur gear transmission. The drive unit can form an electrical axle for a vehicle. According to a further development, the third rolling bearing can be seated on the transmission shaft, in particular for the axially predominant part, wherein the inner bearing ring abuts a radial projection on the side facing away from the rotor shaft. Radial and axial forces acting on the transmission shaft, which emanate from a toothing or a