Patent ID: 12253145

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

FIG.1shows a vehicle1with two axles11a,11b, a power train2according to example aspects of the invention being drivingly arranged at the first axle11a. The vehicle1is an electric vehicle in this case, the vehicle1being driven purely electrically. The first axle11acan be either a front axle or a rear axle of the vehicle1and forms a driven axle of the vehicle1. The power train2includes a drive unit22, which is in the form of an electric machine, and a transmission3operatively connected thereto. The design and the arrangement of the transmission3are explained in greater detail in the following figures. The design of the drive unit22is not shown here. The drive unit22or the electric machine also has an accumulator, which supplies the drive unit22with electrical energy, and a power electronics system for the open-loop control and closed-loop control of the drive unit22. A rotor (not shown here), which is arranged so as to be rotatable with respect to the stator and is connected, as a drive shaft, to an input shaft4(shown inFIG.2) in the transmission3for conjoint rotation, is set into a rotational movement in relation to the stator by energizing a stator (not shown here). The drive power of the drive unit22is directed via the input shaft4into the transmission3and there is converted by an integral differential7and at least indirectly divided onto a first output shaft5and a second output shaft6. The drive unit22is coaxial to the integral differential7.

A wheel18is at least indirectly connected at each of the ends of the output shafts5,6, which are coaxial to each other in the present case, in order to drive the vehicle1. Joints and wheel hubs can be arranged between the respective wheel18and the output shafts5,6in order to compensate for possible inclinations of the output shafts5,6. These are not shown or described in greater detail here.

The transmission3shown in greater detail inFIG.2is a differential gear. The output shafts5,6are coaxial to each other and extend in opposite directions to the wheels18inFIG.1, wherein the first output shaft5extends axially through the transmission3, in particular through the integral differential7, and through the drive unit22.

The integral differential7has a first planetary gear set8, which includes multiple gear set elements, and a second planetary gear set9, which also includes multiple gear set elements and which is operatively connected to the first planetary gear set8. A first output torque is transmittable onto the first output shaft5by the first planetary gear set8. A support torque of the first planetary gear set8is convertible in the second planetary gear set9such that a second output torque, which corresponds to the first output torque, is transmittable onto the second output shaft6.

In the present case, a first sun gear25aas the first gear set element, a first planet carrier26aas the second gear set element, and a first ring gear27aas the third gear set element are arranged at the first planetary gear set8, wherein multiple first planet gears28a, which are meshed with the first sun gear25aand the first ring gear27a, are rotatably arranged on the first planet carrier26a. The first output shaft5extends axially through the first sun gear25ain the first planetary gear set8. Therefore, the first sun gear25ais formed as a ring gear and the input shaft4connected thereto is formed as a hollow shaft. The first sun gear25ais fixedly seated on the input shaft4or is connected thereto for conjoint rotation. The first sun gear25aand the input shaft4are connected to each other as one piece in this case.

Furthermore, a second sun gear25bas the first gear set element, a second planet carrier26bas the second gear set element, and a second ring gear27bas the third gear set element are arranged at the second planetary gear set9, wherein multiple second planet gears28b, which are meshed with the second sun gear25band the second ring gear27b, are rotatably arranged on the second planet carrier26b.

The first planetary gear set8and the second planetary gear set9are each in the form of a negative planetary gear set and are radially nested and, therefore, arranged in a common plane, which extends perpendicularly to the axle11a. Axial installation space is reduced as a result. The first planetary gear set8is arranged radially inside the second planetary gear set9in the present case.

The first planet carrier26ain the first planetary gear set8is connected to the first output shaft5for conjoint rotation via a driving tooth system29. The first ring gear27ain the first planetary gear set8is connected via a coupling shaft14to the second sun gear25bin the second planetary gear set9for conjoint rotation. The second planet carrier26bin the second planetary gear set9is supported in a housing-fixed manner against the stationary component13which is the transmission housing in the present case. In addition, the second ring gear27bin the second planetary gear set9is connected to the second output shaft6for conjoint rotation via a coupling element10, which is formed as a ring gear carrier in this case.

It is explicitly pointed out that the assignment of the gear set elements to the elements in the particular planetary gear set8,9can be arbitrarily interchanged. The particular connection of the sun gear, the planet carrier and the ring gear, as the gear set elements, is implemented including the sign as required for the ratios. Instead of a negative planetary gear set, the particular planetary gear set8,9can also always be in the form of a positive planetary gear set by interchanging the connection of the planet carrier and the ring gear and increasing the absolute value of the stationary gear ratio by one (1). Correspondingly, the other way around is also possible.

It is also conceivable to arrange an additional transmission gearing (not shown here), which is in the form, for example, of a spur gear stage or a planetary transmission having one or multiple planetary gear set(s), between the drive unit22and the transmission3in order to increase an overall gear ratio of the drive and/or to implement an axial offset of the output shafts5,6, for example, when it is not possible to axially extend one of the output shafts5,6through the drive unit22.

According toFIG.2, the input shaft4is mounted for rotation with respect to the stationary component13by a first bearing L1, which is a fixed bearing. In addition, the second output shaft6is mounted for rotation with respect to a stationary component13, which is the transmission housing in this case, by a second bearing L2, which is a fixed bearing. Furthermore, the first output shaft5is mounted for rotation with respect to the stationary component13by a third bearing L5, which is a fixed bearing. It is pointed out that the drive unit22is arranged between the first bearing L1and the third bearing L5and is operatively connected to the input shaft4. The first, the second, and the third bearings L1, L2, L5are each grooved ball bearings in the present case, which transmit axial forces as well as radial forces. The first planet carrier26ain the first planetary gear set8is mounted for rotation with respect to the second output shaft6, the coupling element10and the second ring gear28bin the second planetary gear set27bvia a radial bearing L3, which is a needle bearing. The radial bearing L3can also be a plain bearing for reasons of installation space and costs. The coupling element10is also rotatably mounted on the stationary component13together with the second output shaft6and the second ring gear28bvia a floating bearing L4. The floating bearing L4can be a plain bearing or an anti-friction bearing.

FIG.3ashows a cutout portion of the integral differential7according toFIG.2in detail, wherein the first planet carrier26ain the first planetary gear set8is axially fixed on the first output shaft5and, in fact, by a snap ring31, which is arranged radially between an axial section21of the first planet carrier26ain the first planetary gear set8and the first output shaft5. The snap ring31is arranged in the area of the driving tooth system29and axially fixes the first planet carrier26aon the first output shaft5. As a result, an undesired axial displacement of the first planet carrier26ain relation to the other gear set elements in the differential7due, for example, to meshing forces, is prevented. In this example, the provision of axial bearings for axially mounting the first planet carrier26acan be dispensed with entirely.

FIG.3bthroughFIG.3gshow further example design options for the axial fixation of the first planet carrier26ain the first planetary gear set8with respect to the first output shaft5, wherein the design options can be reasonably arbitrarily combined with one another. The advantage of all example embodiments for the axial fixation of the first planet carrier26aof the first planetary gear set8in relation to the first output shaft5is that at least a portion of the axial bearings, preferably all axial bearings, for mounting the first planet carrier26aof the first planetary gear set8can be dispensed with.

According toFIG.3bthroughFIG.3eandFIG.3g, it is provided that the first planet carrier26ain the first planetary gear set8is axially fixed on the first output shaft5by at least one retaining ring32,33.

According toFIG.3b, a first retaining ring32is accommodated to the left of the driving tooth system29in a first groove34formed on the first output shaft5. As a result, the first planet carrier26ain the first planetary gear set8can come to rest, toward the left, axially against the axially fixed, first retaining ring32and be supported against the first retaining ring32. In the opposite axial direction, i.e., toward the right in this case, the first planet carrier26ain the first planetary gear set8is mounted with respect to the stationary component13via only one single axial bearing A1. Further axial bearings can be dispensed with.

According toFIG.3c, a second retaining ring33is accommodated to the right of the driving tooth system29in a second groove35formed on the axial section21of the first planet carrier26ain the first planetary gear set8. As a result, the first planet carrier26ain the first planetary gear set8comes to rest via an end face against the first output shaft5and can be supported against the first output shaft5. In the opposite axial direction, i.e., toward the right in this case, the first planet carrier26ain the first planetary gear set8is mounted with respect to the stationary component13via only one single axial bearing A1. Further axial bearings can be dispensed with.

The axial fixation of the first planet carrier26ain the first planetary gear set8according toFIG.3dis based, in the first axial direction, on the embodiment according toFIG.3b, and so reference is made to the comments presented with respect toFIG.3b. In this example, a third groove30, in which a second retaining ring33is accommodated, is also formed to the right of the driving tooth system29. In other words, the driving tooth system29and the axial section21of the first planet carrier26ain the first planetary gear set8are arranged axially between two grooves34,30, wherein the first planet carrier26ain the first planetary gear set8is held in its axial position in relation to the first output shaft5by the retaining ring33. In this case, axial bearings for mounting the first planet carrier26acan be dispensed with.

FIG.3eshows a single retaining ring32to the right of the driving tooth system29. The retaining ring32is accommodated in a first groove34formed on the first output shaft5. As a result, the first planet carrier26ain the first planetary gear set8can come to rest, toward the right, axially against the axially fixed, first retaining ring32and be supported against the first retaining ring32. To the left of the driving tooth system29, the first output shaft5has a circumferential first shoulder19, against which the first planet carrier26ain the first planetary gear set8is axially supported toward the left. The first output shaft5therefore has at least two sections with different outer diameters. The axial section21of the first planet carrier26ain the first planetary gear set8is arranged axially between the first shoulder19and the first retaining ring32. In this case, axial bearings for mounting the first planet carrier26acan be dispensed with.

According toFIG.3f, an axial fixation of the first planet carrier26ain the first planetary gear set8is implemented by a second shoulder20, which can be generated via plastic shaping. The second shoulder20is a local taper of an inner diameter of the first planet carrier26aon the axial section21. Via the second shoulder20, the first planet carrier26ain the first planetary gear set8comes to rest via an end face against the first output shaft5. The second shoulder20forms an axial stop. In the opposite axial direction, i.e., toward the right in this case, the first planet carrier26ain the first planetary gear set8is mounted with respect to the second output shaft6via only one single axial bearing A1. Further axial bearings can be dispensed with.

The axial fixation of the first planet carrier26ain the first planetary gear set8according toFIG.3gis based, in the first axial direction, on the embodiment according toFIG.3c, and so reference is made to the comments presented with respect toFIG.3c. In this example, a circumferential third shoulder23is also formed on the first planet carrier26ain the first planetary gear set8. The third shoulder23comes to rest via an end face against the second output shaft6. The third shoulder23is an axial stop, which simultaneously acts as a plain bearing, such that the first planet carrier26acan turn in relation to the second output shaft6, or vice versa. In this case, axial bearings for mounting the first planet carrier26acan be dispensed with.

Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

1vehicle2power train3transmission4input shaft5first output shaft6second output shaft7differential8first planetary gear set9second planetary gear set10coupling element11afirst axle11bsecond axle12epicyclic gear train13stationary component14coupling shaft18wheel19first shoulder20second shoulder21axial section of the first planet carrier in the first planetary gear set22drive unit23third shoulder25afirst sun gear in the first planetary gear set25bsecond sun gear in the second planetary gear set26afirst planet carrier in the first planetary gear set26bsecond planet carrier in the second planetary gear set27afirst ring gear in the first planetary gear set27bsecond ring gear in the second planetary gear set28afirst planet gear in the first planetary gear set28bsecond planet gear in the second planetary gear set29driving tooth system30third groove31snap ring32first retaining ring33second retaining ring34first groove35second grooveA1axial bearingL1first bearingL2second bearingL3radial bearingL4floating bearingL5third bearing