WO2017092740A1

WO2017092740A1 - Epicyclic gearing for a motor vehicle drive unit

Info

Publication number: WO2017092740A1
Application number: PCT/DE2016/200499
Authority: WO
Inventors: Franz Kurth
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2015-12-01
Filing date: 2016-11-07
Publication date: 2017-06-08
Also published as: DE102015223914A1; DE102015223914B4

Abstract

The invention relates to epicyclic gearing for a motor vehicle drive unit, comprising a first sun gear, a second sun gear, an epicyclic gear housing operating as the planet carrier, a planet arrangement received in the planet carrier, comprising first and second planet gears engaged with the two sun gears in such a way that the two sun gears are coupled such that they can rotate in opposite directions, a stepped planet gear which comprises a first toothed section and a second toothed section and is mounted on the planet carrier, a ring gear which surrounds the planet carrier concentrically in relation to the rotational shaft thereof and is engaged with the first toothed section of the stepped planet gear, and a third sun gear which is engaged with the second toothed section of the stepped planet gear and is arranged coaxially with the rotational shaft of the planet carrier, the first toothed section of the stepped planet gear extending along the axial level of the first and second sun gears and being mounted on the planet carrier, on a first and a second bearing point, and the second toothed section being mounted on the planet carrier in a floating manner and extending on an outer side of the planet carrier, which faces away from the first toothed section.

Description

title

Planetary gear for a motor vehicle drive unit

The invention relates to a planetary gear for a motor vehicle drive unit with a first sun gear, a second sun gear, acting as a planet carrier circulation housing, and a planetary gear with a planetary axis rotating planetary arrangement, wherein the power tap is accomplished from the planetary gear via its sun gears.

From DE 10 2012 213 392 A1 a planetary gear transmission of the aforementioned type is known, which is designed as a spur gear and has a circulation housing with a planetary assembly received therein, wherein the planets of this planetary order with sun gear in engagement are also included in the interior of the circulating housing are. The circulation housing comprises a first housing side part and a second housing side part, wherein these two housing side parts are laterally connected to opposite end faces of an externally toothed toothed ring. Due to the axial extent of this toothed ring results between the two side panels required for receiving the sun gears and the planetary assembly space. The planetary arrangement itself is engaged with the sun gears so that the sun gears are rotatably coupled to each other in opposite directions. The coupling of the drive power in the spur gear is via an external spur gear, which is in engagement with the external toothing of the said toothed ring. Object of the invention

The invention has for its object to provide a planetary gear for a motor vehicle drive unit, which is characterized by a robust and compact design and advantageous manufacturing under production aspects.

Inventive solution

The above object is achieved by a planetary gear for a motor vehicle drive unit, with: a first sun wheel,

a second sun wheel,

a circulation housing that acts as a planet carrier,

a planetary assembly received in the planetary carrier having first and second planets in mesh with the two sun gears such that the two sun gears are rotatably coupled to each other in opposite directions;

a stepped planetary gear that has a first gear section and a second gear section and is mounted on the planet carrier,

a ring gear which surrounds the planetary carrier concentrically with its revolution axis and engages with the first gear portion of the stepped planet, and a third sun gear which engages with the second gear portion of the stepped planet and is coaxially disposed with the planet carrier rotational axis;

wherein the first gear portion of the stepped planet extends on the axial level of the first and the second sun gear and is mounted on a first and a second bearing point on the planet carrier, and

the second gear section is cantilevered on the planet carrier and extends on an outer side of the planet carrier facing away from the first gear section.

This makes it possible in an advantageous manner to provide an epicyclic gear in which provided for the realization of the differential gear function planet carrier also acts as a planet carrier for a stepped planet, wherein the coupled via the stepped planet in the planet carrier circumferential forces in those Stufenplan- th supporting force levels also in the bearings of the planetary arrangement are derived. This results in a structurally advantageous load on the planet carrier and also the possibility of using a space between the planet relevant for the differential function planet in the planetary space remaining space for, or the stepped planets. In addition, a primarily caused by circumferential forces under extensive internal compensation of the radial forces structure of the drive torque results in the planet carrier, so that it can be stored on cost-effective bearings on the power tap provided for wave systems.

The second toothed section of the stepped planet preferably projects axially beyond an end face of a side part of the planet carrier and is preferably formed by two, the first toothed portion between flying bearings on the planet carrier stored flying.

According to a particularly preferred embodiment of the invention, the Umlaufrä- dergetriebe is designed such that the two sun gears, the planetary arrangement and the planet carrier form a spur gear, for symmetrical branching of the guided over the planet carrier drive power to the two sun gears. The two sun gears can be arranged side by side in close proximity by special tip circle dimensioning and supplementary design and mounting of the planetary arrangement, so that the axial length of the first toothed portion of the stepped planetary planet corresponds to the sum of the width dimensions of the toothed rings of the two inner sun gears.

The planet carrier is preferably made as a sheet metal forming part and consists of a first side part and a second side part, wherein the two inner sun gears are located axially between these two side parts. The stepped planet may then be integrated into the transmission system in such a way that it radially distances the first side part to the axis of rotation and passes through it axially parallel, so that then the second gear section of the stepped planet on a side of the first side part facing away from the first gear section outside of the first side part Planet carrier extends. For this second toothed section, there is then a so-called flying bearing, wherein this flying bearing has a high rigidity due to the two-sided support of the first toothed section in the planet carrier. The stepped planet is preferably configured such that the first toothed portion extending on the axial level of the inner sun gears has a pitch circle diameter smaller than the pitch diameter of the second toothed portion. This makes it possible to dimension the diameter of the third toothed wheel engaged with and driving the second toothed portion relatively small and via the engagement of the third sun gear in the second toothed portion of the stepped planet, as well as the tooth engagement of the first toothed portion of the stepped planet in the internal toothing of the ring gear to realize a high overall gear ratio. In a particularly advantageous manner, the concept according to the invention also results in a reduction of the relative movements of the components, since numerous adjacent components which position one another via bearing points or movement surfaces have the same directions of rotation. So this has to drove the stepped planet provided third sun gear in the same direction of rotation as the driven via the first inner sun gear output shaft. The planet carrier and the two inner sun gears also have the same directions of rotation, so that only relative to the compensatory action of the differential gear system relative movements occur at low relative angular velocities.

In the transmission system according to the invention, it is possible in an advantageous manner, the third sun gear and coupled to the first sun gear first output shaft via a sun gear bearing rotatably supported against each other. This support can be accomplished in particular by a needle bearing, or cylindrical roller bearing, wherein the running surfaces of the rolling elements can advantageously be provided directly by corresponding peripheral surfaces of that third sun gear (cylindrical inner surface) and the first output shaft (cylindrical outer surface). The bearing of the planet carrier can be accomplished in an advantageous manner by the first side part of the planet carrier and coupled to the first sun gear output shaft via a first planet carrier bearing point are rotatably supported against each other. This bearing point can be realized in an advantageous manner as a sliding bearing point, since in this bearing only the relative movements occurring in the context of the compensating effect of Differentialgetrie- must be permitted. In the same way, then the second side part of the planet carrier and coupled to the second sun gear second output shaft via a second planet carrier bearing point can be rotatably supported against each other, whereby this bearing in turn is preferably realized as a sliding bearing. The main bearing of the circulating system can then be accomplished by supporting the output shafts so that they support the planet carrier radially.

The stepped planet preferably forms part of a stepped planetary group, the stepped planets of that stepped planetary group preferably having the same construction and being connected to the planetary carrier in the same circumferential division. This stepped planetary group then preferably comprises at least two, in particular three or even four stepped planets arranged at equal pitch on the planetary carrier. The stepped planets can be designed as helical stepped planets. In this case, the tooth angles can again be selected such that an at least substantial compensation of the axial force components of the reaction forces acting on the stepped planet results. The fixed storage of the stepped planet is preferably carried out via the second storage unit. le of the stepped planet accomplished via which this is rotatably supported on the side facing away from the second toothed portion side in the second side part of the planet carrier. The Stufenplanet can be made in an advantageous manner as a built structure, so that in particular the first toothed portion forms part of a pin which is inserted via a toothing in a second toothed portion forming spur gear. The above-mentioned, the stepped planet in the second, ie the "rear" planet carrier side member overlapping bearing assembly may be designed so that this allows a push-through of the first toothed portion through the corresponding hole in the second planet carrier side part. For this purpose, the tip circle of the first gear portion is then dimensioned smaller than the inner bore of a rolling bearing receiving bearing seat in the second planet carrier side part. However, it is also possible in particular to design the stepped planet so that a driver profile, in particular a spline, is formed in the inner region of the first spline section, into which a complementary shaped journal can be inserted. The drive of the third sun gear is preferably effected by an electromechanical drive unit. This may comprise a hollow shaft rotor through which an output shaft of the drive assembly extends axially therethrough. The electromechanical drive unit then comprises a coaxially arranged to that output shaft motor. The third sun gear can then be produced directly as a pinion seated on a hollow rotor shaft. However, it is also possible to drive the third sun gear by otherwise connecting a drive unit. Thus, the drive of the third sun gear via a spur gear, a traction drive or an angular gear can be done. As an alternative to a purely electric drive of the third sun gear, it is also possible to drive it by another drive system, for example an internal combustion engine, an oil engine or a hybrid drive system.

The drive unit according to the invention can be used advantageously for the realization of a rear axle system, which is compatible for example to the connection points of a conventional rear axle, so that the drive unit according to the invention can be integrated into vehicles whose bottom plate is designed primarily for other types of drives. Brief description of the figures

Further details and features of the invention will become apparent from the following description taken in conjunction with the drawings. It shows:

Figure 1 is a schematic representation to illustrate the structure of a planetary gear according to the invention which can be used in particular for the realization of electromechanical Hinterachsantriebs application;

Figure 2 is a simplified axial sectional view for explaining further details of the stepped planet and this bearing on the planet carrier storage system.

Detailed description of the figures

The illustration of Figure 1 shows an inventive epicyclic gearbox for a motor vehicle drive system, with a first sun gear S1, a second sun gear S2, a circulation housing G acting as a planet carrier C, a planetary arrangement P with first and second planet P1, P2 with each other and the two sun gears S1, S2 are engaged in such a way that the two sun gears S1, S2 are rotatably coupled in opposite directions via the planets P1, P2.

The epicyclic gearbox further comprises a stepped planetary P3 having a first gear portion P3Z1 and a second gear portion P3Z2, and a ring gear H engaged with the first gear portion P3Z1 of the stepped planet P3. The drive of the stepped planet P3 is accomplished via a third sun gear S3, which engages with the second toothed section P3Z2 of the stepped planet P3 and is arranged coaxially to a revolving axis X of the circulating housing G. The first gear portion P3Z1 of the stepped planet P3 extends at the axial level of the first and second sun gear S1, S2 and is mounted in the rotary housing G via first and second bearing points L1, L2.

The two sun gears S1, S2, the planetary arrangement P and the circulation housing G form a spur gear differential for the symmetrical branching of the drive power guided via the planet carrier C to the two sun gears S1, S2. The planet carrier C is composed of a first side part C1 and a second side part C2 and the two sun gears S1, S2 are arranged axially between these two side parts C1, C2.

The stepped planet P3 passes axially through the first side part C1 and the second toothed section P3Z2 of the stepped planet P3 extends on a side of the first side part C1 facing away from the first toothed section P3Z1. In this case, the first toothed section P3Z1 has a pitch circle diameter which is smaller than the pitch circle diameter of the second toothed section P3Z2. The second gear portion P3Z2 is cantilevered on the planet carrier C, i. its end region facing away from the planet carrier C is not supported by any further bearing device.

The power tap of the two inner sun gears S1, S2 is accomplished via a first and a second output shaft WS1, WS2. The third sun gear S3 provided for driving the second toothed section P3Z2 of the stepped planetary gear is rotatably mounted on the first output shaft WS1 coupled to the first sun gear S1 via a sun gear bearing point L3. Both components rotate within the scope of operation in the same directions of rotation, so that there is a reduction of the relative movements.

The first side part C1 of the planetary carrier C and the output shaft WS1 coupled to the first sun gear S1 are rotatably supported against each other via a first planetary carrier bearing point L4. The second side part C2 of the planetary carrier C and the output shaft WS2 coupled to the second sun gear S2 are rotatably supported against each other via a second planet carrier bearing point L5.

The first toothed section P3Z1 of the stepped planet P3 engages radially from the inside into the ring gear H. The ring gear H is stationary anchored in the gear housing HO. As can be seen from the integrated sketch Vi, the stepped planet P3 forms part of a step planetary group, the step planets P3 of that step planetary group being of identical design and connected to the planetary carrier C in the same circumferential division. The stepped planetary P3 is made as a built structure, ie it is composed of several components. As will be explained in more detail below in connection with FIG. 2, the stepped planetary P3 can in particular be designed in such a way that the first toothing portion P3Z1 part of a pin P3S forms, which is inserted via a toothing in a second toothing portion forming spur gear P3S1.

The partial circle P3C3 of the second toothed section P3Z2 shown in the sketch V1 has a larger diameter than the partial circle P3C1 of the first toothed section P3Z1. The first gear section P3Z1 extends within the planet carrier C between the side parts C1, C2 thereof.

In the illustrated embodiment, the planetary arrangement P is designed in such a way that the first and second planets P1, P2 engage with each other at the axial level of the second ("smaller") sun gear S2. The first planet P1 is designed as a "long" planet extends over the entire length of the outer toothing of the first sun gear S1 and the outer toothing of the second sun gear S2. The second planet P2 is designed as a "short" planet and only extends beyond the outer toothing of the second sun gear S2 and engages it so that the first planet P1 does not engage in the second sun gear S2, the sun gears S1, S2 With this measure, it becomes possible to arrange the first planets P1 of the planetary arrangement P on a pitch circle whose diameter is larger than the pitch circle which the second planetary P2 of the planetary arrangement P are arranged and the first planet P1 thus come out of the external toothing of the second sun gear S2 free.

In the embodiment shown here, three identical stage planets P3 are mounted on the planet carrier C. The planetary arrangement P provided for realizing the differential gear function is in each case located in an intermediate region of successive stepped planets P3. When three stepped planets P3 are used, therefore, three planetary arrangements P are also provided which each have a first and a second coupling planet P1, P2. Due to the close proximity of the stepped planetary planets P3 and the coupling planets P1, P2 of the planetary arrangement P results in a favorable power transmission within the side parts C1, C2 of the planet carrier C and the realization of the translation effect and the differential function in the smallest space.

The representation of Figure 2 illustrates in the form of a simplified Axialteilschnitts the structure of a stepped planet P3 and the storage thereof in the side parts C1, C2 of the planet carrier C. The stepped planet P3 comprises a core pin P3S on the one hand the first toothing portion P3Z1 forms and on the other hand has a plug-in portion P3Z3, which in a complementary internally toothed bore P3Z4 of the spur gear P3S1 rotatably inserted, in particular einpressbar. The spur gear P3S1 forms on its outer peripheral region the second toothed section P3Z2 of the stepped planet P3.

The storage of the stepped planet P3 in the planet carrier C is accomplished as shown by a first rolling bearing L1 in the first side part C1 and by a second rolling bearing L2 in the second side part. The first rolling bearing L1 is located axially between the first and the second toothing section P3Z1, P3Z2 of the stepped planet. This first rolling bearing L1 is designed as a floating bearing and also designed as a cylindrical roller bearing. The rolling elements L1W of this first bearing L1 of the stepped planet run directly on a cylindrical outer peripheral surface of the core pin P3S. The first bearing L1 further comprises a bearing outer ring L1 Ra which is pressed into a corresponding receiving bore C1 B1. The rolling elements L1W are guided in a cage L1 K. The bearing outer ring L1 R1 is axially secured in the receiving bore C1 B1 by a securing device (not shown here, for example, by roll-up flanging). The side part C1 of the planetary carrier C is formed thickened in the area surrounding the receiving bore C1 B1. The corresponding bead is produced by plastic deformation of the starting material used to form the side part C1. The material accumulation is brought about by radial displacement of the material initially located in the area of the receiving bore C1 B1 to the outside.

On the side of the core pin P3S facing away from the second toothed section P3Z2, the core pin P3S is mounted in the second side part C2 of the planet carrier C via the second bearing L2. This second bearing L2 forms the fixed bearing and determines the axial position of the core pin P3S in the planet carrier C. This bearing L2 is designed here as a deep groove ball bearing. It comprises a bearing inner ring L2i and a bearing outer ring L2a, and designed as balls rolling elements L2W which are guided in a cage L2C. The bearing inner ring L2i is secured via a locking ring L2R on the core pin P3S. The bearing outer ring L2a of the second bearing L2, similar to the bearing outer ring L1 Ra of the first bearing L1, is press-fitted into a bore C1 B2 formed in a bead-surrounded region of the second side part C2. The axial securing of this bearing outer ring L2a can in turn be accomplished by plastic deformation of the bearing outer ring in the region of its end faces skirting material of the second side part C2. In the illustrated embodiment, the first bearing L1 is designed such that the inner diameter of the first bearing outer ring L1 Ra is greater than the head circle through knife of the first gear section. This makes it possible to first fix the first bearing outer ring L1 Ra in the first side part and then pass the core pin P3S through the first bearing outer ring L1 Ra. The second bearing L2 can also be fixed first in the second side part C2 before inserting the core pin P3S, and then after inserting the corresponding end portion of the core pin P3S this is axially fixed by inserting the retaining ring L2R in the second bearing.

The second gear section P3Z2 of the stepped planet P3 forming spur gear P3S1 sitting on the side facing away from the second side part C2 of the planet carrier C side of the Plane- tenträgers C and is cantilevered over the two camps L1, L2. The second toothed section P3Z2 is thus located outside of the planet carrier C and is seated on a pin P3S of the stepped planet P3 which is cantilevered as a result.

Claims

claims

Epicyclic gearbox for a motor vehicle drive system, comprising:

a first sun gear (S1),

a second sun gear (S2),

a planet carrier (C),

a planetary assembly (P) having first and second planets (P1, P2) engaged with the two sun gears (S1, S2) such that the two sun gears (S1, S2) are rotatably coupled to each other in opposite directions;

a stepped planetary (P3) having a first gear section (P3Z1) and a second gear section (P3Z2),

a ring gear (H) engaged with the first gear portion (P3Z1) of the stepped planet (P3),

a third sun gear (S3) engaged with the second gear portion (P3Z2) of the stepped planet (P3) and arranged coaxially with a revolving axis (X) of the planetary carrier (C),

wherein the first gear portion (P3Z1) of the stepped planet (P3) extends at the axial level of the teeth of the first and second sun gears (S1, S2) and supported in the planet carrier (C) via first and second bearings (L1, L2) is and

the second toothed portion (P3Z2) is cantilevered on the planetary carrier (C) and extends on an outer side of the planet carrier facing away from the first toothed portion (P3Z1).

2. epicyclic gearbox according to claim 1, characterized in that the two sun gears (S1, S2), the planetary arrangement (P) and the planet carrier (C) form a spur gear, the symmetrical branching of the planet carrier (C) guided drive power to the two Sun wheels (S1, S2).

3. planetary gear according to claim 1 or 2, characterized in that the planet carrier (P) of a first side part (C1) and a second side part (C2) composed and the two sun gears (S1, S2) axially between these two side parts (C1 , C2) are arranged.

4. planetary gear according to at least one of claims 1 to 3, characterized in that the stepped planet (P3) has a portion which the first side part (C1) passes through axially and that the second toothed section (P3Z2) of the stepped planet (P3) is located on a side of the first side part (C1) facing away from the first toothed section (P3Z1).

5. planetary gear according to at least one of claims 1 to 4, characterized in that the first toothed portion (P3Z1) aufsteist a pitch circle diameter which is smaller than the pitch circle diameter of the second toothing portion (P3Z2).

6. planetary gear according to at least one of claims 1 to 5, characterized in that the third sun gear (S3) and one with the first sun gear (S1) coupled first output shaft (WS1) via a sun gear bearing (L3) are rotatably supported against each other.

7. planetary gear according to at least one of claims 1 to 6, characterized in that the first side part (C1) of the planet carrier (C) and one with the first sun gear (S1) coupled output shaft (WS1) via a first planet carrier bearing point (L4) rotatably to each other are supported.

8. planetary gear according to at least one of claims 1 to 7, characterized in that the second side part (C1) of the planet carrier (C) and one with the second sun gear (S2) coupled second output shaft (WS2) via a second planet carrier bearing (L5) rotatable supported on each other.

9. epicyclic gear according to at least one of claims 1 to 8, characterized in that the Stufenplanet (P3) forms part of a Stufenplanetengruppe, wherein the stepped planets (P3) of that stepped planetary are identical and are used in the same circumferential division in the planet carrier (C).

10. epicyclic gear according to at least one of claims 1 to 9, characterized in that the Stufenplanet (P3) is made as a built structure, and that the first toothed portion (P3Z1) part of a pin P3S) which forms a toothing (P3Z3) in a spur gear (P3S1) forming the second gear portion (P3Z2) is inserted.