WO2021023338A1

WO2021023338A1 - Compact transmission arrangement with a stepped planetary gear set and spur gear differential

Info

Publication number: WO2021023338A1
Application number: PCT/DE2020/100616
Authority: WO
Inventors: Florian Reinle; Jochen Loeffelmann; Bastian Rupp; Sebastian Langhans; Jörg BAUER
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2019-08-05
Filing date: 2020-07-15
Publication date: 2021-02-11
Also published as: CN114207321A; DE102019121079B3

Abstract

The invention relates to a transmission arrangement (1) for a motor vehicle, comprising a stepped planetary gear set (2) and a spur gear differential (3) connected via a common planetary gear carrier (4), which differential has a first and a second planetary gear set (6, 7), which mesh in pairs, wherein: each planetary gear set (6, 7) includes a sun gear (13, 14), which is rotationally fixed to an output shaft (15, 16) of the spur gear differential (3); torques introduced via an input shaft into the transmission arrangement (1) from the stepped planetary gear set (2) are transferred into the spur gear differential (3) and subsequently to the output shafts (15, 16), and then to driven wheels of the vehicle; wherein a meshing plane of the stepped planetary gear set (2) radially overlaps at least one sun gear (13, 14) of the spur gear differential (3); wherein differential pinion journals (10, 11) in the stepped planetary gear set (2) pass through a meshing plane of the spur gear differential (3) at a radial distance from the sun gears (13, 14) and radially and axially fix a differential cover (12) at the ends; and the planetary gear carrier (4) is mounted in the housing (4) via a floating bearing (34) created by the engagement of an input sun gear (39) and double planet gears in the form of spur gears (17) in the stepped planetary gear set (2), and on the opposite side by means of the differential cover (12) via a fixed bearing (36).

Description

Compact gear arrangement with stepped planetary set and spur gear differential

Transmission arrangement for a motor vehicle, comprising a stepped planetary set and a spur gear differential connected via a common planet carrier, according to the features of the preamble of claim 1.

DE 102015214031 A1 shows a transmission arrangement for a motor vehicle, which comprises a transmission input stage and a differential connected to it via a common planet carrier. The differential, constructed as a spur gear differential, has two planetary sets, the planetary gears of which are toothed with separate sun gears. Furthermore, the two planetary sets of the differential are toothed with each other in pairs. The transmission input stage has a drive sun that meshes with a first planetary gear set that is connected to the second planetary gear set in a rotationally fixed manner.

From EP 2 821 672 A1 a transmission arrangement assigned to an electric drive unit is known, comprising a rotor shaft as input shaft and a differential gear and a stepped planetary set designed as a planetary gear, also called gear input stage, whose sun gear is assigned to the input shaft. The differential gear, designed as a spur gear differential, includes planet gears as differential gears and sun gears as output gears, with an output shaft being assigned to each sun gear. A torque introduced via the input shaft is introduced into the spur gear differential via the stepped planetary set and from there it is transferred to the output shafts and then to the driven vehicle wheels. The input shaft forms a hollow shaft through which one of the output shafts is guided.

The invention is based on the object of creating a gear arrangement for a drive device which is compact at least in the axial direction and which can be easily installed and implemented at low cost. This object is achieved by a gear arrangement with the features of claim 1. Preferred and / or advantageous embodiments of the invention emerge from the subclaims, the following description and the accompanying figures.

According to the invention it is provided that planetary gear bolts of the stepped planetary set are arranged by a toothing plane of the spur gear at a radial distance from the sun gears and the pinion bolts continue to fix a differential cover radially and axially fi at the end facing away from the stepped planets. To support the planet carrier, it is provided that it is supported on the drive side of the gear arrangement via the running teeth of the large planet gears as a floating bearing and mutually by means of the differential cover via a fixed bearing in the housing of the gear arrangement.

Due to the inventive concept, which includes a radial expansion of the spur gear differential, an axially compact spur gear differential can advantageously be implemented, which at the same time has a positive effect on the space required for the entire transmission arrangement. Because of the spur gear differential that is expanded in the radial direction, a radial overlap occurs at least between the stepped planetary sets and a toothing plane of the spur gear differential. To implement this solution, the planetary gear bolt is axially extended from the stepped planetary set to such an extent that it enables the differential cover to be guided and fixed. The compact concept according to the invention advantageously leads to a desired smaller deformation of the planet carrier, which has a positive effect on the torsional rigidity of the gear arrangement.

In addition, this compact design according to the invention enables alternative, cost-effective manufacturing methods such as cold-forming processes, for example deep drawing, stamping or extrusion, for individual components of the gear arrangement, which ensure overall improved rigidity even with reduced wall thicknesses. The bearing of the planet carrier constructed according to the invention comprises a floating bearing on the drive side which results from the meshing engagement of the large double planets with the input sun. On the output side, the differential cover, which is non-rotatably connected to the planet carrier, is preferably mounted in the gear housing of the gear arrangement via a fixed bearing designed as a deep groove ball bearing.

According to an advantageous embodiment, which underlines the axially compact design of the Ge gear arrangement, according to the invention, a sun gear of the spur gear differential is placed close to the planet carrier. In order to achieve the smallest possible axial distance, a recess is made locally in the guide support structure of the planet carrier near the pinion pin, which allows unhindered rotation of the sun gear.

A preferred structural design of the spur gear differential provides for the outer enveloping circle of the spur gear differential to be designed to be smaller than the tip circle of an internal toothing of the associated ring gear. This measure results in a simplified assembly sequence, since there is no need to join the ring gear before assembling the spur gear differential over the planet gears.

According to the invention, the pinion pin of the spur gear in the installation was positively fixed on the component geometries of the differential cover and the plane carrier axially. Preferably, the differential gear bolt is inserted with one end side into a blind hole of the planet carrier and with the other end side fitted into a hole in the differential cover and supported on a radially inwardly directed rim of the differential cover. A complementary form-fitting and / or material-locking anti-rotation device can be dispensed with for reasons of cost.

The planet gear bolts of the stepped planetary sets are permanently secured in position by means of caulking at both soft ends of the planet gear bolts. The caulking of the planetary gear pin creates backlash-free attachment to the differential cover and the planetary carrier, which does not require any additional interference fit of the pin in the planetary carrier. The caulking results in a permanent connection that can withstand high mechanical requirements, such as vibrations that occur when the gear assembly is in operation.

A caulking tool with a special contour is preferably used for caulking the planetary gear pin, which initially has an acute angle which is then increasingly flatter, so that the deformation increases as the axial caulking path increases. With this measure, the resilience of the caulking can be increased while the caulking force remains the same. The caulking of the planetary gear pin, also known as caulking marks, also leads to improved torsional rigidity of the planetary carrier, which for example has a positive effect on the bearing of the planetary gears, reduces the toothing forces of the gears and consequently optimizes the service life of the entire transmission arrangement.

The stepped planetary sets are free-flying, with the planetary gears also called spur gears being mounted on roller bearings designed as a needle roller ring. All of the planet gears are centered on the planet gear pin and the needle roller and cage assembly. The release of the planetary gear sets necessary for load balancing takes place via the associated ring gear. An axial distance of at least 6 mm is provided for the spur gears of the stepped planetary set, which are also referred to as transmission gears, which are assigned to a planetary gear pin in each case.

The gear arrangement includes a lubrication device, with the associated pinion pin or a blind hole or a longitudinal hole closed on one side due to installation for specific lubrication of the rotatably mounted differential gears or spur gears of the spur gear differential and the stepped planetary set. Preferably, egg ne oil pan is used in the differential pin of the spur gear end. Oil or oil mist is absorbed within the gear arrangement due to centrifugal forces in the operating state via the oil pan, which can also be referred to as a baffle and which preferably connects all the planetary gear bolts around the circumference. then passed into the longitudinal bore and fed from there through radial bores of the plane pin of the bearing.

The planetary gear bolt assigned to the stepped planetary set preferably forms a partition wall in the middle of the longitudinal bore to form a blind bore so that lubricating oil can then flow into the axially offset bearings of the spur gears via radial bores.

Skiving is preferably suitable for producing the toothing of the stepped planetary set and / or of the spur gear differential. Skiving is a continuous cutting process for the production of gears. This production process combines hobbing and shaping through continuous rolling with axial feed and enables the production of internal and external gears. The envisaged power skiving enables a higher cross-axis angle with a larger distance, which can reduce tool wear and thus costs. To achieve an overall cost-effective production, the toothings of the stepped planetary set are preferably arranged axially at a distance of at least 6 mm from one another.

The compactly constructed according to the invention, a spur gear differential and a stepped planetary gear assembly including is preferably suitable for the drive train of an electric drive unit of a motor vehicle. For example, it is advisable to couple the gear arrangement with an electric motor to form a so-called E-axis. The e-axle is a solution for the electric drive of purely electric vehicles or for hybrid applications. In the case of the e-axle, components such as the motor, axle and gearbox, which are used separately in a conventional design, are combined into one structural unit.

The invention is described in more detail below with the aid of an exemplary embodiment shown in three figures. However, the invention is not limited to the exemplary embodiment shown. It shows: Fig. 1: In a longitudinal section, a constructed according to the invention, a spur gear differential and a stepped planetary including gear arrangement;

FIG. 2: in a three-dimensional view, a section of a spur gear differential and a stepped planetary set of the gear arrangement according to FIG. 1;

3: In a front view, the planetary sets of the spur gear differential and the gear wheels of the stepped planetary set;

4: a detail section through the spur gear differential of the gear arrangement.

The following description of the figures of an exemplary embodiment is intended to provide a better understanding of the invention. The same components are provided with the same reference numerals.

1 shows a transmission arrangement 1 according to the invention according to a preferred exemplary embodiment with regard to its structure and the arrangement of individual components, not all components of the transmission arrangement 1 being shown in FIG. 1. The gear arrangement 1 assigned to a drive train (not shown) from an electrical drive of a motor vehicle, for example, is divided into a stepped planetary set 2 and a spur gear 3. In the stepped planetary set 2, which is also known as a gear ratio section or reduction step, for example, an electric motor (not shown) introduced drive torque translated or reduced from a high input speed to a low output speed. The converted output torque is then distributed via the spur gear differential 3 to its output shafts connected to the drive wheels of the motor vehicle. For the stepped planetary set 2 and the spur gear 3, a planet carrier 4 is vorgese hen, which is inserted in a housing 5 of the transmission arrangement 1.

The planetary carrier 4 is on the drive side via the toothing engagement between the input sun 39, which is the output shaft, for example as a floating bearing 34 15 encloses, and the large planet gears 17 rotatably mounted. The output-side bearing of the planetary carrier 4 is via a fixed bearing 36. For this purpose, a Rillenkugella ger is provided, which is inserted between a receptacle 37 of the gear housing 5 of the Ge transmission arrangement 1 and a cylindrical, axially protruding projection 38 of the Differen tialdeckels 12, which is torsionally rigid with the Planet carrier 4 is connected.

The spur gear differential 3 comprises, as shown in Fig. 2, two planetary sets 6, 7 with differently dimensioned differential gears, a wide differential gear 8 and a narrow differential gear 9, which are each rotatably mounted on an associated balance wheel bolts 10, 11, which rotatably in associated bores of the planetary gear carrier 4 and a differential cover 12 are used. On the radially inner side, the differential gears 8, 9 are each toothed with a sun gear 13, 14, each sun gear 13, 14 being connected to an output shaft 15, 16 in a rotationally fixed manner.

The stepped planetary set 2 includes transmission gears, with two axially offset, helical and interconnected, also planet gears called spur gears 17, 18 via roller bearings 19, 20 rotatably mounted on a planet gear pin 21, which are in engagement with other gears (not shown) . Needle roller and cage assemblies (KZK) are preferably suitable as roller bearings 19, 20. To achieve a cost-effective production, the two mutually offset, differently dimensioned spur gears 17, 18 are arranged at an axial distance of> 6 mm. Furthermore, the stepped planetary set 2 or its planetary gear pin 21 overlaps the sun gears 13, 14 when installed and consequently a toothing plane of the spur gear 3. The axially compact design of the transmission arrangement 1 is emphasized by the toothing plane of the sun gear 13 of the spur gear 3 axially close to the planet carrier 4 placed. In order to achieve the smallest possible axial distance, a recess 33 for the sun gear 13 is made locally in the guide support structure of the planetary carrier 4.

The planetary gear bolts 21 of the stepped planetary set 2 are permanently secured in position by means of caulking 22, 23 at both soft ends of the planetary gearbol 21. The caulking 22, 23 over the circumference of the planetary gear is advantageous. Bolt 21 arranged distributed, whereby the planet gear pin 21 is non-positively and / or positively connected to the differential cover 12 or the planet carrier 4 and secured in a rotationally and positionally fixed manner. To lubricate the roller bearings 19, 20 of the spur gears 17, 18 of the stepped planetary set 2, a blind hole 24 is made in the planet gear bolt 21, into which in operating state 1 lubricating oil flows in from the side facing the output shaft 16 and into one via radial bores 25 of the planet gear bolt 21 Annular space 26 bounded axially by the roller bearings 19, 20 occurs.

Fig. 2 and Fig. 3 illustrate in different views the arrangement or installation positions of the planetary sets 6, 7 of the spur gear differential 3 and the transmission gears forming, also called double planetary spur gears 17, 18 of the stepped planetary set 2, to create a compact in the axial direction Ge gear arrangement 1. In Fig. 2 is a through the toothing plane of the spur gear differential 3 guided planetary gear pin 21 from the stepped planetary set 2, which runs at a radial distance from the sun gears 13, 14 of the spur gear 3.

In the detailed section of the transmission arrangement 1 according to FIG. 4, in particular the installation position of the differential gear pin 10 and the lubrication of the differential gears 8, 9 of the spur gear 3 are shown. In the installed state, the differential gear bolt 10 is fitted into a blind hole 27 in the planetary gear carrier 4 and mutually axially fixed on a radially inwardly directed rim 28 of the differential cover 12. For the targeted application of lubricating oil to the bearing 29 of the compensating wheel 8, which is designed as a slide bearing, an oil pan 31 is inserted at the end in the longitudinal bore 30 of the compensating wheel bolt 10. Lubricating oil taken up by the oil collecting tray 31 is directed into the longitudinal bore 30, which is then fed to the bearing 29 via radial bores 32 of the planetary gear pin 10. List of reference symbols

1 gear arrangement

2 stepped planetary set 3 spur gear differential

4 planet carriers

5 housing

6 planetary gear set

7 Planetary set 8 Balance gear (wide)

9 balance wheel (narrow)

10 differential pin

11 differential pin

12 differential cover 13 sun gear

14 sun gear

15 output shaft

16 output shaft

17 spur gear 18 spur gear

19 rolling bearings

20 rolling bearings

21 planet gear bolts

22 caulking 23 caulking

24 blind hole 25 radial bore

26 annulus

27 blind hole

28 Board 29 Storage

30 longitudinal bore

31 Oil pan

32 radial bore

33 recess 34 floating bearing

35 running gears

36 fixed bearings

37 Recording

38 Extension 39 input sun gear s Distance between the spur gears

Claims

1 . Gear arrangement for a motor vehicle, comprising a stepped planetary set (2) and a spur gear differential (3) connected via a common planetary carrier (4), which has a first and a second planetary set (6, 7) which are geared to one another in pairs, each planetary set (6, 7) each includes a sun gear (13, 14) which rotates fixedly with an output shaft (15,

16) of the spur gear differential (3) is connected, torques introduced via an input shaft into the gear assembly (1) integrated in a housing (5) are transferred from the stepped planetary set (2) to the spur gear differential (3) and then to the output shafts (15 , 16) and thus transferred to driven vehicle wheels, with a toothing plane of the stepped planetary set (2) radially overlaps at least one sun gear (13, 14) of the spur gear differential (3), characterized in that the differential pin (10, 11) of the stepped planetary set (2 ) are guided through a toothing plane of the spur gear differential (3) with a radial distance from the sun gears (13, 14) and at the end a differential cover (12) fix radially and axially and the planet carrier (4) via a floating bearing (34), which is made up of tooth engagement of an input sun (39) and spur gears (17) of the stepped planetary set (2) which form double planets and mutually by means of the differential cover Is (12) is mounted in the housing (4) via a fixed bearing (36).

2. Gear arrangement according to one of the preceding claims, characterized in that a sun gear (13) of the spur gear differential (3) in the installation was placed at a small axial distance from the planet carrier (4), which is too local in the area of the differential gear pin (10 , 11) each has a recess (33).

3. Gear arrangement according to one of the preceding claims, characterized in that an outer enveloping circle of the spur gear differential (3) is designed to be smaller than an inner diameter of an associated ring gear.

4. Gear arrangement according to one of the preceding claims, characterized in that the differential gear bolts (10, 11) of the spur gear differential (3) in the installed state are positively fixed via the component geometries of the differential cover (12) and the planetary carrier (4) at least axially.

5. Gear arrangement according to one of the preceding claims, characterized in that the planetary gear bolts (21) of the stepped planetary sets (2) are fixed in position at both ends by means of caulking (22, 23) with the planet carrier (4) and the differential cover (12).

6. Gear arrangement according to one of the preceding claims, characterized in that the spur gears (17, 18) of the stepped planetary sets (2) via roller bearings (19, 20) are rotatably mounted on the planetary gear pin (21).

7. Gear arrangement according to one of the preceding claims, characterized in that for the lubrication of a bearing (29) of the differential gears (8,

9) of the spur gear differential (3) at the end in a longitudinal bore (30) of the equal gear bolts (10, 11) an oil pan (31) is inserted.

8. Gear arrangement according to one of the preceding claims, characterized in that for the lubrication of the roller bearings (19, 20) of the spur gears (17, 18) of the stepped planetary sets (2) the planetary gear bolts (21) have a blind hole (24) and radial bores (25) exhibit.

9. Gear arrangement according to one of the preceding claims, characterized in that a skiving is provided for producing the teeth of the differential gears (8, 9) of the spur gear differential (3) and / or the spur gears (17, 18) of the stepped planetary set (2) .

10. Gear arrangement according to one of the preceding claims, characterized in that the gear arrangement (1) is used in a drive train of an E-axle.