US-12618456-B2 - Roller-mounted motor vehicle drive unit

US12618456B2US 12618456 B2US12618456 B2US 12618456B2US-12618456-B2

Abstract

A motor vehicle drive system has a traction transmission device. A traction transmission drive shaft is rotatably mounted in a transmission device housing. A traction transmission intermediate shaft is rotatably mounted in the transmission housing. A traction transmission output shaft is rotatably mounted in the transmission housing device, and is arranged axially parallel to and radially spaced apart from the two other traction transmission shafts. The motor vehicle drive system is characterized in that three traction transmission shafts are each mounted in the traction transmission housing device with a fixed/floating bearing, these bearings each having a fixed bearing for absorbing axial forces and at least one floating bearing designed exclusively to absorb radial forces. The three fixed bearings are mounted in the traction transmission cover, and at least three of the floating bearings are mounted in the traction transmission housing.

Inventors

Richard Baeumler
Tobias Riesch
Michael Staake

Assignees

BAYERISCHE MOTOREN WERKE AKTIENGESELLSCHAFT

Dates

Publication Date: 20260505
Application Date: 20230718
Priority Date: 20220817

Claims (5)

1 . A motor vehicle drive system, comprising: an electromechanical energy converter as an electric drive machine; and a traction transmission apparatus for transmitting drive power to a motor vehicle axle drive, wherein the traction transmission apparatus comprises: a traction transmission housing device, wherein a traction transmission drive shaft is rotatably mounted in the traction transmission housing device and is connected for conjoint rotation, or is selectively connectable for conjoint rotation, to the electric drive machine, a traction transmission intermediate shaft, which is rotatably mounted in the traction transmission housing device and which is arranged axially parallel to and at a radial spacing from the traction transmission drive shaft, and a traction transmission output shaft, which is rotatably mounted in the traction transmission housing device and which is arranged axially parallel to and at a radial spacing from the two other traction transmission shafts, a traction transmission drive gearwheel is arranged on the traction transmission drive shaft and meshes with a first traction transmission intermediate gearwheel arranged on the traction transmission intermediate shaft, and a second traction transmission intermediate gearwheel is arranged on the traction transmission intermediate shaft and meshes with a traction transmission output gearwheel arranged on the traction transmission output shaft, and wherein the traction transmission housing device has a traction transmission housing and a traction transmission cover, wherein the three traction transmission shafts are each mounted in the traction transmission housing device via a fixed/floating bearing arrangement, and said bearing arrangements comprise in each case a fixed bearing for accommodating axial forces and in each case at least one floating bearing configured exclusively for accommodating radial forces, wherein said three fixed bearings are arranged in the traction transmission cover, and wherein at least three of said floating bearings are arranged in the traction transmission housing.
2 . The motor vehicle drive system according to claim 1 , wherein at least one of, or all of, the floating bearings of the traction transmission intermediate shaft, the traction transmission output shaft and the traction transmission drive shaft are formed as a cylindrical roller bearing.
3 . The motor vehicle drive system according to claim 1 , wherein in the bearing arrangement of the traction transmission drive shaft, both the fixed bearing and the floating bearing of said bearing arrangement are formed as deep groove ball bearings.
4 . The motor vehicle drive system according to claim 1 , wherein in the bearing arrangement of the traction transmission intermediate shaft, both the fixed bearing and the floating bearing of said bearing arrangement are formed as deep groove ball bearings.
5 . The motor vehicle drive system according to claim 1 , wherein the bearing arrangement of the traction transmission output shaft has a first and a second cylindrical roller bearing, wherein said cylindrical roller bearings are arranged in an axial direction of the traction transmission output shaft on different sides of the traction transmission output gearwheel, and the fixed bearing of said bearing arrangement is formed as a deep groove ball bearing or as a four-point bearing.

Description

BACKGROUND AND SUMMARY The invention relates to a roller-bearing-mounted motor vehicle drive system for overcoming motor vehicle driving resistances such as roller resistance, air resistance and the like, and to a motor vehicle having such a drive system. DE 10 2019 127 242 A1 discloses an electric drive apparatus for a motor vehicle. A general requirement for the drive of a motor vehicle is that the drive has a long service life and high efficiency. These two properties, or the achievement thereof, can have a negative influence on one another. The invention is discussed below on the basis of a motor vehicle drive system having a gearwheel transmission, the gearwheels of this transmission having what is known as an involute toothing. Although such a toothing has low sensitivity to a deviation from the planned axis spacing (known as axis spacing error), a rigid (low load-dependent displacement) and efficient bearing arrangement is also advantageous here. Particularly rigid supporting of transmission shafts is achievable with what is known as an adjusted bearing arrangement; however, such a bearing arrangement does not have a low degree of loss, in particular compared to a non-adjusted bearing arrangement. The invention proposes a roller-bearing-mounted motor vehicle drive system which equally permits a transmission of drive power with high efficiency and low displacement of transmission shafts. This object is achieved by a subject according to the independent claim(s), the dependent patent claims providing preferred developments of the invention. In the invention, it is in particular proposed to take the supporting of the transmission shafts as a whole into account, in order thus to be able to realize an in particular low-displacement and efficient motor vehicle drive system. In the context of the invention, a motor vehicle drive system should be understood to mean a system for driving a motor vehicle, preferably a passenger car, the drive power for overcoming driving resistances such as the frictional resistance, the roller resistance, the air resistance and what is known as the acceleration resistance being provided by means of an electromechanical energy converter. In the context of the invention, such an electromechanical energy converter should thus be understood to mean an electric drive machine, in particular an electric motor/generator, such an electric drive machine being known in different constructions. Furthermore, the motor vehicle drive system has a traction transmission apparatus, this transmission apparatus being configured to transmit and adapt drive power to a load requirement of the motor vehicle, which results in particular from the driving resistances. The traction transmission apparatus is thus configured to transmit drive power in the form of rotation speed and torque to a motor vehicle axle drive. Here, this motor vehicle axle drive should be understood in particular to mean a motor vehicle drive axle, in particular a front or rear axle. The traction transmission apparatus has a traction transmission housing device, in particular the traction transmission housing device consists of multiple components and is preferably also configured to receive the electric drive machine. A traction transmission drive shaft is rotatably mounted in this traction transmission housing, this traction transmission drive shaft being able to be interpreted, in relation to a transmission of power from the electric drive machine to the motor vehicle axle drive, what is known as the motor drive direction, as a first transmission shaft or as an input shaft into the traction transmission apparatus. In a first embodiment of the invention, the traction transmission drive shaft is connected for conjoint rotation to the electric drive machine, is preferably oriented coaxially with respect thereto and is further preferably coupled for conjoint rotation directly thereto. In a further embodiment, the traction transmission drive shaft is selectively connectable for conjoint rotation to the electric drive machine, preferably by means of a clutch device. In particular, a permanently rotationally conjoint connection of the electric drive machine to the traction transmission drive shaft makes it possible to save on a bearing point, and a selectively couplable electric drive machine can reduce drag losses. In addition to the traction transmission drive shaft, the traction transmission apparatus also has a traction transmission intermediate shaft, which, in relation to the motor drive direction, is arranged downstream of the traction transmission drive shaft, preferably this is arranged directly downstream thereof. The traction transmission intermediate shaft is rotatably mounted in the traction transmission housing device and is arranged axially parallel to and at a radial spacing from the traction transmission drive shaft. Furthermore, the traction transmission apparatus also has a traction transmission output shaft, which,