DE102011079975A1 - Drive device for a motor vehicle - Google Patents

Abstract

The invention relates to a drive device for a motor vehicle which, as such, comprises an axle differential gear and an epicyclic gearbox upstream of this axle differential. The planetary gear is designed as a planetary gear whose planetary gears are stepped and each form a first Planetenstirnradabschnitt and a coaxially and axially offset to this arranged second Planetenstirnradabschnitt. The first Planetenstirnradabschnitt stands with the sun gear and the second Planentenstirnradabschnitt is in engagement with the ring gear. The stepped planetary gears run together with the circulation housing around a transmission axis.

Description

Field of the invention

The invention relates to a drive device for a motor vehicle which, as such, comprises an axle differential gear and an epicyclic gearbox upstream of this axle differential. The planetary gear is designed so that this allows a central shaft passage, so that a to be connected to the axle differential drive shaft can be guided centrally through this epicyclic gear. In particular, the invention relates to an electromechanical drive device in which the branched over the axle differential on the Radantriebswellen drive power is generated by an electric motor which is coupled via the aforementioned epicyclic gear with the axle differential.

Background of the invention

Out DE 198 41 159 A1 is an electromechanical drive device for a motor vehicle of the aforementioned type known. The axle differential is designed there as a bevel gear differential. The introduction of the generated by an electric motor drive torque in this bevel gear differential via a planetary gear stage. The planetary gear stage comprises a planet carrier whose base body also forms part of the differential cage of the bevel gear differential. The electric motor itself is designed as an external rotor motor, the power take-off from the external rotor via a hollow shaft journal having a spur gear portion which dips into the planetary gear stage and thereby acts as a sun gear planetary gear stage.

Object of the invention

The invention has for its object to provide a drive device for a motor vehicle, which is characterized by a compact design, a low weight and an advantageous mechanical performance and is also inexpensive to produce.

Inventive solution

• – einem Differentialgetriebe, das als Stirnraddifferential ausgebildet ist und ein Umlaufgehäuse, ein darin aufgenommenes erstes Stirnrad und ein ebenfalls in dem Umlaufgehäuse aufgenommenes zweites Stirnrad aufweist, und
• – einer Planetengetriebestufe die mit dem Umlaufgehäuse kinematisch gekoppelt ist und ein Sonnenrad, Planetenräder und ein Hohlrad aufweist, wobei,
• – die Planetenräder der Planetengetriebestufe gestuft ausgebildet sind und jeweils einen ersten Planetenstirnradabschnitt und einen gleichachsig und axial zu diesem versetzt angeordneten zweiten Planetenstirnradabschnitt bilden,
• – der erste Planetenstirnradabschnitt mit dem Sonnenrad und der zweite Planentenstirnradabschnitt mit dem Hohlrad in Eingriff steht, und
• – die gestuft ausgebildeten Planetenräder gemeinsam mit dem Umlaufgehäuse umlaufen.

This object is achieved by a drive device for a motor vehicle, with:

• - A differential gear, which is designed as a spur gear and has a circulation housing, a first spur gear received therein and a second spur gear also received in the circulation housing, and
• A planetary gear stage kinematically coupled to the rotary housing and having a sun gear, planetary gears and a ring gear, wherein
• - The planetary gears of the planetary gear stage are formed stepped and each form a first Planetenstirnradabschnitt and a coaxially and axially offset to this arranged second Planetenstirnradabschnitt,
• - The first Planetenstirnradabschnitt with the sun gear and the second Planentenstirnradabschnitt is in engagement with the ring gear, and
• - Rotate the stepped planetary gears together with the circulation housing.

This makes it possible in an advantageous manner to provide a drive device for a motor vehicle in which compared to previous designs a significant reduction in complexity, weight and space requirements can be achieved.

According to a particularly preferred embodiment of the invention, the planetary gear stage and the spur gear differential are summarized such that the peripheral housing of the spur gear differential acts as a planet carrier of the planetary gear stage. In this construction, it is possible in particular, the orbit radii of the axes of the stepped planetary gears of the planetary gear and the orbit radii of the differential planet of Stirnraddifferentiales to be identical. In this design, the differential planets can be mounted on journals which form axially projecting over the circulation housing axial projections on which then the planet gears of the planetary gear stage are stored. These components can be arranged so that the operating forces and load deformations compensate structurally advantageous.

Preferably, the planetary gear stage is configured such that the first Planetenstirnradabschnitt, d. H. That Planetenradabschnitt which is in engagement with the sun gear is located in an intermediate region between the second Planetenstirnradabschnitt and the circulation housing of the spur gear differential. The first Planetenstirnradabschnitt is in this case according to the invention designed so that it has a larger diameter than the second Planetenradstirnradabschnitt. In this configuration, gear ratios in the range of 1/7 to 1/17, in particular of 1/9, can be advantageously realized via the planetary gear stage.

A particularly compact and structurally advantageous embodiment of the invention is given by the fact that the differential gear in particular a spur gear received therein forms a hub portion in which a Wheel drive shaft, for example via a toothing rotatably inserted.

According to a particular aspect of the present invention, the drive device is constructed such that it comprises an electric motor, wherein this electric motor is arranged coaxially to the axis of rotation of the planetary gear stage. The electric motor can in this case be constructed such that its rotor is seated on a hollow shaft, wherein the above-mentioned wheel drive shaft in the manner of a plug shaft in this hollow shaft inserted axially and in the corresponding inserted state of the toothed section thereof with the hub of Stirnraddifferentiales engages.

According to another aspect of the present invention, it is possible to insert a precursor into the drive train between the electric motor and the planetary gear stage connected to the spur gear differential. This pre-stage may include a switching device by which the precursor can be selectively activated or bypassed. This switching device may comprise an electromechanical actuator, a positioning cylinder, a cable or lever mechanism, or other adjusting mechanisms. The switching device preferably comprises a friction and a claw clutch. About the dog clutch then the planet carrier of the precursor can be positively coupled to the sun gear of the seated on Stirnraddifferential planetary gear stage. The dog clutch thus transmits high torques. When releasing the dog clutch, the input shaft of the precursor can directly, d. H. not translated with the sun gear of the planetary gear stage are frictionally coupled. This frictional coupling state can be brought about without any special need for synchronization. However, the drive device preferably comprises sensor devices that provide information about the instantaneous rotational states, wherein this information can be taken into account when changing a switching state. Thus, it is possible in particular when engaging the dog clutch to tune the power supply of the electric motor so that here sufficient synchronization of the sections of the temporarily separated drive train is brought about and thus the clutch can be engaged quietly.

As an alternative to the preferred embodiment of the electric motor as an electric motor with an internally rotating rotor, the electric motor can also be designed as an external rotor motor. In the previously described variant with a precursor, the power input into the precursor via the ring gear can take place here, which in this variant then circulates with the external rotor rotor. The sun gear would then be stationary.

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:

1 a schematic representation of a first embodiment of the drive device according to the invention with a spur gear, whose circulation housing acts as a planet carrier for stepped planetary gears;

2 a schematic representation of a second embodiment of the drive device according to the invention also with a spur gear, whose circulation housing acts as a planet carrier for stepped planetary gears, with a switchable activatable precursor.

Detailed description of the figures

In 1 a drive device according to the invention for a motor vehicle is shown. This drive device comprises a differential gear which is designed as a spur gear differential and a circulation housing 2 , and a first spur gear received therein 3 and a second spur gear received therein 4 having. Furthermore, the drive device comprises a planetary gear stage 5 the with the circulation housing 2 kinematically coupled and a sun gear 6 , Planetary gears 7 and a ring gear 8th having. The planet wheels 7 the planetary gear stage 5 are stepped and each form a first Planetenstirnradabschnitt 7a and a coaxially and axially offset to this arranged second Planetenstirnradabschnitt 7b , The first planetary spur gear section 7a stands with the sun wheel 6 and the second planetary gear section 7b stands with the ring gear 8th engaged. The planet wheels 7 are on a journal 9 which is mounted on the circulation housing 2 is anchored. The planet wheels 7 rotate together with the circulation housing 2 around the transmission main axis X.

The spur gear differential 1 and the differential gear 5 are arranged coaxially to the transmission main axis. The power tap from the spur gear differential 1 takes place via its inner spur gears 3 . 4 , These spur gears 3 . 4 form here not detail constructively illustrated hub sections to which a left edge drive shaft 10 and a right wheel drive shaft 11 are coupled.

In the embodiment shown here, the circulation housing acts 2 of the spur gear differential 1 as already mentioned as planet carrier of the planetary gear stage 5 , The spur gear differential 5 has differential planets 2a . 2 B on top of that axle journal 9 in the circulation housing 2 are stored. These journals 9 are like that designed that these axial projections have on which the planetary gears 7 the planetary gear stage 5 are stored.

The first planetary spur gear section 7a , which with the sun wheel 6 is in an intermediate region between the second Planetenstirnradabschnitt 7b and the circulation housing 2 , This first planetary spur gear section 7a has a larger diameter than the second Planetenradstirnradabschnitt 7b ,

In the embodiment shown here forms the differential gear 5 a shaft passage through which the wheel drive shaft 10 passed through here with the spur gear 3 of the spur gear differential 1 is coupled. This shaft passage is here by an axial bore 12 formed coaxially with the transmission axis X in a rotor shaft 13 extends. This rotor shaft forms part of an electric motor 14 in the same way as the spur gear differential 1 and the inventively designed planetary gear stage 5 to the transmission axis X is arranged coaxially.

On the rotor shaft designed as a hollow shaft 13 is a rotor 15 fixed. This rotor 15 gets over yours through a stator 16 generated rotating field driven. The stator 16 carries several windings which can be acted upon by power electronics with voltage to drive the rotor 15 generate required spin field. The electric motor 14 is constructed and electrically connected such that it is temporarily operable as a generator in a recuperation mode. Due to the structure of the drive device according to the invention is achieved that the rotor 15 due to the large through the special planetary gear stage 5 achievable transmission ratio rotated with correspondingly high speeds and thus offers a high electrical efficiency.

For the in 2 illustrated embodiment, the comments apply to 1 analogous. Deviating from the variant 1 is in the variant after 2 in the drive train between the electric motor 14 and the connected to the Stirnraddifferential planetary gear stage 5 a preliminary stage 16 intended. This precursor 16 is with a switching device 17 coupled a selective activation of the precursor 16 allows.

In the embodiment shown here, the precursor comprises 16 a sun wheel 18 that on the rotor shaft 13 sitting. This sun wheel stands with planet wheels 19 engaged. These planet wheels 19 are on a planet carrier 20 which is mounted coaxially to the transmission axis X, in particular on the rotor shaft 13 is stored. The planet wheels 19 continue to stand with a ring gear 21 engaged. this ring gear 21 is with the stator of the electric motor 14 rigidly coupled. The precursor is preferably designed so that this between sun gear 18 and the planet carrier 20 a translation in the range of 1: 3 to 1: 7 realized.

switching device 17 includes a dog clutch K1 and friction clutch K2. The switching device 17 is constructed such that via the clutches K1, K2 selectively the planet carrier 20 or the rotor shaft 13 with the sun wheel 6 the planetary gear stage 5 can be coupled. The actuation of the clutches K1, K2 takes place in the variant shown here via an adjusting mechanism 22 , This adjusting mechanism 22 here includes an electromechanical actuator 23 through which a shift claw 24 is relocatable. The shift claw 24 accesses a release bearing 15 on a peripheral structure of the switching device 17 at.

The dog clutch K1 comprises a clutch claw 26 in a counterstructure of the planet carrier 20 is engageable. When engaged, the planet carrier is then 20 with the sun wheel 6 the planetary gear stage 5 coupled. Between the circulation housing 2 of the spur gear differential 1 and the rotor 15 of the electric motor 14 then there is the pre-stage 16 and the planetary gear stage 5 Generated maximum gear ratio. By disengaging the dog clutch K1 this coupling state is canceled. By correspondingly further displacement of the shift claw 24 (Right here), the second clutch device K2 is activated. This coupling device is designed as a friction clutch. The clutch torque generated by this friction clutch is proportional to the clutch engagement force. About this friction clutch, the rotor shaft 13 directly with the sun wheel 6 be coupled. In this coupling condition exists between the spur gear differential 1 and the rotor 15 of the electric motor 14 that through the special planetary gear stage 5 caused gear ratio.

The inventive concept results in comparison to previous designs a significant reduction in complexity, the weight and space requirements.

The drive device according to the invention can be used as a so-called. Electric axis in coaxial design in corresponding vehicles. The drive device according to the invention provides a relatively high gear ratio which makes it possible to carry out the electric motor as a relatively compact, space-saving engine. According to the invention for the planetary gear stage 5 a planetary set with stepped double planets used. The planetary gear set has two rotatably connected planets 7a . 7b on the same bolt 9 on, with the one larger planet 7a with the sun 6 , the other small planetary gear 7b with the ring gear 8th the planetary stage 5 combs. The larger of the two planet gears can be right next to the differential 1 (as shown in the picture). Alternatively, the position of the two planets can also be used 7a . 7b be reversed, ie the smaller planet 7b is next to the differential 1 , The first variant shown here, however, is more favorable with regard to the overall system deformations. The from the position of the two planets 7a . 7b resulting tilting moments between the ring gear 8th and the sun 6 counteract the deformations of the differential cage 2 , This results in a lower tendency for misalignment of the planet pins 9 ,

Both in the variant 1 , as well as the variant 2 are the bolts 9 of the planetary gear set 7a . 7b identical to the bolts of the differential 1 (same pitch circle, same position in the circumferential direction).

After a 2-speed transmission 2 There is a wide range of realizable gear ratios. By the use of the invention graduated double planet 7a . 7b in the second gear stage 5 It is possible to set the number of teeth of the gears in a wide range and thus to realize desired translations in the first and second gear with at least largely the same basic design.

The drive device according to the invention can also be constructed so that its center of gravity substantially centrally between the Radantriebswellenflanschen 31 . 32 is because the system weight and the axial space requirement of the spur gear differential 1 and the planetary gear stage 5 in about the system weight and the space requirement of the electric motor 14 correspond. The preliminary stage 16 is located in the vicinity of the center of gravity and contributes only slightly to the position of the center of gravity in the direction of the system axis X.

The spur gear differential 1 , the special planetary gear stage 5 and - if provided - the preliminary stage 16 can be accommodated in a housing which also stores a lubricant sump in which these system components can dive sufficiently. This housing can be made as a pot structure to a corresponding flange portion of the electric motor 14 can be recognized. The location of the Radantriebswellenflansche 31 . 32 is preferably adjusted so that when integrated into a corresponding vehicle for the left and the right Radantriebsgelenkwelle same dimensions result, so that these components can be made identical.

The drive device according to the invention is suitable both for steered front drive axles, as well as for non-steered rear drive axles. The drive device according to the invention can be designed so that it also forms connection points for components of the suspension.

In the variant after 2 it is possible to make the coupling devices K1 and K2 so that they can be engaged simultaneously when the vehicle is stationary. This makes it possible to pre-stages 16 to block in itself. This will in turn make it possible through the preliminary stage 16 and their clutches K1, K2 to realize a parking lock function.

The according to the variant 2 between the electric motor 14 and the differential gear 5 arranged precursor can also on a the differential gear 5 opposite end face of the electric motor 14 be arranged. In this variant, the switching device 17 be split such that the coupling device K1 on the side of the precursor 16 sits and the coupling device K2, ie that coupling device which a direct coupling of the rotor 15 to the sun wheel 6 continues to effect between the electric motor 14 and the planetary gear stage 5 located.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19841159 A1 [0002]

Claims (10)

Drive device for a motor vehicle, comprising: - a differential gear ( 1 ), which is designed as a spur gear differential and a circulation housing ( 2 ), and a first spur gear received therein ( 3 ) and a second spur gear received therein ( 4 ), and - a planetary gear stage ( 5 ) with the circulation housing ( 2 ) is kinematically coupled and a sun gear ( 6 ), Planet gears ( 7 ) and a ring gear ( 8th ), wherein - the planet gears ( 7 ) of the planetary gear stage are formed stepped and in each case a first Planetenstirnradabschnitt ( 7a ) and a coaxially and axially offset to this arranged second Planetenstirnradabschnitt ( 7b ), - the first Planetenstirnradabschnitt ( 7a ) with the sun wheel ( 6 ) and the second planetary gear section ( 7b ) with the ring gear ( 8th ), and - the planet wheels ( 7 ) together with the circulation housing ( 2 ). Drive device according to claim 1, characterized in that the circulation housing ( 2 ) of the spur gear differential ( 1 ) as planet carrier of the planetary gear stage ( 5 ) acts. Drive device according to claim 2, characterized in that the spur gear ( 1 ) Differential planets ( 2a . 2 B ) has the over journals ( 9 ) in the circulation housing ( 2 ) and that these journals ( 9 ) Have axial projections on which the planet gears ( 7 ) of the planetary gear stage ( 5 ) are stored. Drive device according to claim 3, characterized in that the first Planetenstirnradabschnitt ( 7a ) which with the sun gear ( 6 ) engages in an intermediate region between the second Planetenstirnradabschnitt ( 7b ) and the circulation housing ( 2 ) is located. Drive device according to at least one of claims 1 to 4, characterized in that the first Planetenstirnradabschnitt ( 7a ) has a larger diameter than the second Planetenstirnradabschnitt ( 7b ). Drive device according to at least one of claims 1 to 5, characterized in that the differential gear ( 5 ) forms a shaft passage through which a wheel drive shaft ( 10 ) is guided, which with one of the spur gears ( 3 ) of the spur gear differential ( 5 ) is coupled. Drive device according to at least one of claims 1 to 6, characterized in that the drive device is an electric motor ( 14 ), and that this electric motor ( 14 ) to the axis (X) of the planetary gear stage ( 5 ) is arranged coaxially. Drive device according to claim 7, characterized in that the electric motor ( 14 ) a hollow shaft ( 13 ), and that the wheel drive shaft ( 10 ) through this hollow shaft ( 13 ) is passed axially. Drive device according to at least one of claims 1 to 8, characterized in that between the electric motor ( 14 ) and to the spur gear differential ( 1 ) connected planetary gear stage ( 5 ) a preliminary stage is provided, and that a switching device ( 17 ) is provided for selectively incorporating or bridging the precursor. Drive device according to claim 9, characterized in that the switching device comprises a friction clutch (K2) and that by this friction clutch (K2) of the electric motor ( 14 ) selectively directly with the sun gear ( 6 ) of the planetary gear stage 5 can be coupled.

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