DE102011102749A1 - Gear arrangement for a motor vehicle - Google Patents

Abstract

The invention comprises a transmission arrangement for a motor vehicle, comprising - a housing (4), - an electrical machine (12) with a stator (14) fixed to the housing and a rotor (16) rotatably mounted relative to the stator (14), and - a transmission device with a first spur-toothed planetary gear (18), which is connected by means of its input shaft (22) to the rotor (16) and by means of its output shaft (26) to a first flange shaft (30), and a second spur-toothed planetary gear (20), which by means of its input shaft (34; 38) is connected to a coupling shaft (28) of the first planetary gear (18) and by means of its output shaft (34; 38) to a second flange shaft (40), the first planetary gear (18) forming an input shaft, A first sun gear (22) arranged coaxially with the rotor (16) and connected to it, a ring gear (28) forming its coupling shaft and a first sun gear (28) forming its output shaft, coaxial with the rotor Rotor (16) and coaxially to the first flange shaft (30) and connected to this web (26), which carries a simple set of rotatably mounted first planetary gears (24), on the one hand with the first sun gear (22) and on the other hand with the first Ring gear (28) mesh, and wherein the second planetary gear (20) has a second sun gear (38) and a second web (37) fixed to the housing, which has a simple set of rotatably mounted second planetary gears (36; 36 '), which mesh with the second sun gear (38). The invention is characterized in that the second planetary gear (20) is designed as a simple minus planetary gear with a second ring gear (34), the second planet gears (36, 36 ') of which also mesh with the second ring gear (38).

Description

Field of the invention

• – ein Gehäuse,
• – eine elektrische Maschine mit einen gehäusefesten Statur und einem relativ zu dem Statur drehbar gelagerten Rotor sowie
• – eine Getriebeeinrichtung mit einem ersten stirnverzahnten Planetengetriebe, welches mittels seiner Eingangswelle mit dem Rotor und mittels seiner Ausgangswelle mit einer ersten Achsflanschwelle verbunden ist, und einem zweiten stirnverzahnten Planetengetriebe, welches mittels seiner Eingangswelle mit einer Koppelwelle des ersten Planetengetriebes und mittels seiner Ausgangswelle mit einer zweiten Achsflanschwelle verbunden ist,

wobei das erste Planetengetriebe ein seine Eingangswelle bildendes, koaxial zu dem Rotor angeordnetes und mit diesem verbundenes, erstes Sonnenrad, ein seine Koppelwelle bildendes Hohlrad und einen seine Ausgangswelle bildenden, koaxial zu dem Rotor sowie koaxial zu der ersten Achsflanschwelle angeordneten und mit dieser verbundenen Steg, welcher einen einfachen Satz drehbar gelagerter erster Planetenräder trägt, die einerseits mit dem ersten Sonnenrad und andererseits mit dem ersten Hohlrad kämmen, aufweist
und wobei das zweite Planetengetriebe ein zweites Sonnenrad und einen gehäusefesten, zweiten Steg, welcher einen einfachen Satz drehbar gelagerter zweiter Planetenräder trägt, die mit dem zweiten Sonnenrad kämmen, aufweist.The invention relates to a transmission arrangement for a motor vehicle, comprising

• A housing,
• - An electric machine with a fixed housing stature and a relative to the stature rotatably mounted rotor and
• - A transmission device with a first spur planetary gear, which is connected by means of its input shaft to the rotor and by means of its output shaft with a first Achsflanschwelle, and a second spur planetary gear, which by means of its input shaft with a coupling shaft of the first planetary gear and by means of its output shaft with a second Axle flange is connected,

wherein the first planetary gear forming an input shaft, coaxial with the rotor and connected thereto, the first sun gear, a coupling shaft forming ring gear and an output shaft forming coaxial with the rotor and coaxial with the first Achsflanschwelle arranged and connected to this web, which carries a simple set of rotatably mounted first planet gears, which mesh on the one hand with the first sun gear and on the other hand with the first ring gear has
and wherein the second planetary gear has a second sun gear and a housing-fixed second land which carries a simple set of rotatably mounted second planetary gears meshing with the second sun gear.

State of the art

Such a final drive device is known from the DE 10 2007 055 883 A1 ,

There, an electric axle drive is disclosed in which the electric machine is arranged coaxially with the driven axle. To distribute the torque to the wheels of the driven axle, a two-component transmission device is provided. A first, hereinafter referred to as superposition gear component is designed as a simple planetary gear in Stirnradbauweise. Its sun gear serves as an input shaft and is designed as a hollow shaft and connected to the rotor of the electric machine. Its bridge, which carries a simple, non-stepped planetary gear set, serves as an output shaft and is connected to the first Achsflanschwelle, which passes through the sun gear hollow shaft and the electric machine coaxially. Its ring gear serves as a coupling shaft for coupling the superimposed gear with the second component of the transmission device, which will be referred to hereinafter as the precursor.

The precursor is designed quite complex in the known embodiment and in particular comprises a switching device, with which depending on the switching position one of two ways can be selected, via which the voltage applied to the hollow shaft of the superposition gear torque can be passed to the second Achsflanschwelle. In one of these switch positions, the precursor takes the form of a positive planetary set with two suns, a housing-fixed bar and stepped planets. The first sun gear, which meshes with the axial portion of larger diameter of the stepped planetary, serves as the input shaft of the precursor and is connected to the coupling shaft, d. H. connected to the ring gear of the superposition gear. The second sun gear, which meshes with the axial portion of smaller diameter of the stepped planetary, serves as the output shaft of the precursor and is connected to the second Achsflanschwelle. In this switching position, the moment of the electric machine is distributed to equal amounts, but with different signs on the two axle flanges. In this switching position, the overall arrangement thus does not act as a drive; the drive of the motor vehicle must rather be achieved by other means, for example by means of an internal combustion engine, which attaches to a second driven shaft. Rather, the device is used to distribute the torque on the two axle flange thresholds in order to stabilize the driving situation, for example in curves, as well as to increase the driving dynamics. One speaks of so-called torque vectoring.

In a second switching position of the preliminary stage, in which the known device acts as a real drive, the precursor is extended by an additional planetary gear set, so that the moments distributed to the Achsflanschwellen receive the same sign. The precursor is formed in this switch position as a minus double planetary gear set with two suns, fixed housing and stepped planetary.

Due to the many dental interventions, the efficiency of the precursor in the drive switching position is not optimal. A transfer of this configuration to a pure final drive, i. H. without the possibility of switching to torque vectoring, it is out of the question for this reason and due to the large space requirement. A transmission of the torque vectoring switching position to a pure axle drive device is out of the question due to the different signs of the torques passed to the two axle flange thresholds.

task

It is the object of the present invention to develop a generic gear arrangement such that it represents an axle drive with improved efficiency and reduced space requirements.

Presentation of the invention

This object is achieved in conjunction with the features of the preamble of claim 1, characterized in that the second planetary gear is formed as a simple negative planetary gear with a second ring gear, the second planet gears additionally mesh with the second ring gear.

Preferred embodiments and further developments of the invention are subject matter of the dependent claims.

It is the basic idea of the present invention to radically detoxify and reduce to the functional minimum required in the prior art very complex precursor, which is required for the uneven distribution of the torque of the electric machine in the superposition gear on the first Achsflanschwelle and cancel the coupling shaft, while adjusting the direction of rotation and rotational speed and at the same time to realize an axle ratio, which makes the coaxial arrangement of the electric machine still possible, so that the latter does not have to be coupled in space-saving, axis-parallel arrangement via an efficiency-reducing, additional spur gear. For this purpose, the precursor is designed as a simple planetary gear with sun, planet-supporting web and ring gear and with negative state translation. As a standard translation is here, as is common practice, the ratio between the speeds of the central shaft, d. H. Sun gear and ring gear, understood in the planetary gear with stationary web. In the context of the invention, this state translation always corresponds to the actual translation due to the housing-fixed web. A negative sign of the state translation expresses reverse directions of rotation of the central waves.

As a design example to explain the function of the transmission arrangement according to the invention an electric machine with an output torque of 100 Nm is assumed. The state translation of the superposition gear designed as a simple minus planetary gear is assumed to be i ₁₂ = -4. It can be mathematically shown that this results in a torque at the web of the superposition gear, which corresponds to five times the torque of the electric machine and this opposite, whereas a torque at the ring gear of the superposition gear results, which corresponds to four times the torque of the electric machine and to this is rectified. In order to achieve the same torque distribution and the same directions of rotation required for a final drive for the overall transmission arrangement, the preliminary stage would have to be designed with a stand ratio of i _vs = -1.25. In this design, therefore, the E-machine torque would be transformed from 100 Nm to 500 Nm for each Achsflanschwelle, the speed of the electric machine would correspond to ten times the axle speed. The device thus acts as a "rolling differential", which realizes the necessary for coupling a compared to the wheels of a motor vehicle fast-rotating, but low-torque electric motor axle ratio without additional spur gear. Of course, the invention is not limited to the above design example. One skilled in the art can make designs tailored to the requirements of the particular case using the well-known equations for calculating gears.

The invention can be implemented in principle by a variety of different constructions. In a particularly preferred design it is provided that the second ring gear forms the input shaft of the second planetary gear and the second sun gear forms the output shaft of the second planetary gear. In other words, in this embodiment, the (single) sun gear of the precursor is connected to the second axle flange and the ring gear of the precursor is connected to the ring gear of the superposition gear. The latter, that is, the first and the second ring gear can be formed in a preferred development as a common component, preferably with the same number of teeth for each functional ring gear. This embodiment optimizes the axial space of the overall device.

In order to realize the required translation of the precursor while optimizing the radial installation space, it is provided in a development of the above-described design that the second planetary gears, that is, the planetary gears of the precursor, as stepped planets with a first axial portion of larger circumference and with a second axial portion smaller circumference are formed. In particular, it can be provided that the second planet gears mesh with the second ring gear via their first axial sections and with the second sun gear via their second axial sections. This means that the planet gears mesh with their axial portion of larger circumference with the ring gear and with its axial portion of smaller circumference with the sun gear of the precursor. It is particularly preferred that the number of teeth of the first Planet gears coincides with the number of teeth of the first axial sections of the second planetary gears.

In an alternative, likewise preferred design variant, it is provided that the second sun gear forms the input shaft of the second planetary gear and the second ring gear forms the output shaft of the second planetary gear. This means that the sun gear of the precursor is connected to the coupling shaft, that is, the ring gear of the superposition gear and that the ring gear of the precursor is connected to the second Achsflanschwelle. The basic structure of the precursor thus corresponds to the basic structure of the superposition gearing. In a preferred development of this design is therefore provided that the first and the second planetary gear, ie the superposition gear and the precursor are of identical construction. This has manufacturing advantages, since the number of usable common parts in both planetary gears is maximized. In an identical embodiment of both planetary gear can only a single axle ratio, namely realize about i = 5.24. This can be achieved by, as preferred provided, the state ratios of the first and the second planetary gear i ₁₂ = i _vs = 1.62 ± 0.02, the tolerance is given to compensate for losses occurring in practice. It can be seen that in comparison to the above-described design example, in the case of the design described here, a significant low axle ratio is realized. The design described here is therefore particularly suitable for cases in which the electric machine can deliver its maximum power at comparatively low speeds.

With regard to the axial space, the invention can be optimized in that the first and the second planetary gear in the axial neighborhood together in the interior of the rotor of the preferably designed as an internal rotor electrical machine are arranged.

Further features and advantages of the invention will become apparent from the following, specific description and the drawings.

Brief description of the drawings

Show it:

1 : a schematic representation of a first design of the gear arrangement according to the invention,

2 a partially cut, perspective view of the design of 1 .

3 : a schematic representation of a second design of the gear arrangement according to the invention,

4 a partially cut, perspective view of the design of 3 ,

Detailed description of preferred embodiments

Like reference numerals in the drawings indicate like or analogous elements.

The 1 and 2 show, in each case in a different representation, a first preferred embodiment of the transmission arrangement according to the invention 10 , The gear arrangement 10 shows a (in 2 not shown) electrical machine 12 with a stator 14 and a rotor 16 , In the illustrated embodiment, the electric machine 12 designed in a conventional manner as an internal rotor machine. Next includes the gear assembly 10 a first planetary gear 18 and a second planetary gear 20 , The first planetary gear 18 is also referred to as a superposition gearbox here. The second planetary gear 20 is also referred to here as a precursor. The rotor 16 the electric machine 12 is with the sun wheel 22 of the superposition gearbox 18 connected. The sun wheel 22 meshes with a set of planet gears 24 rotatable on a bridge 26 are stored. In addition, the planetary gears mesh 24 with a ring gear 28 , The jetty 26 is with a first, in the illustrated embodiment right Achsflanschwelle 30 connected, which is the right wheel in the representation 32 the driven axle of the motor vehicle not shown carries. It can be seen that the right axle flange threshold 30 the sun gear formed as a hollow shaft 22 as well as the electric machine 12 coaxially interspersed.

The preliminary stage 20 includes a ring gear 34 , which with the ring gear 28 of the superposition gearbox 18 designed as a common component and equipped with the same number of teeth. With this ring gear 34 meshes a first axial section 36a larger diameter of a set of stepped planets 36 axially adjacent to the first axial section 36a a second axial section 36b have, which has a smaller diameter. With this axial section 36b smaller diameter comb the stepped planet 36 with a sun wheel 38 , which with a second, in the figure left Achsflanschwelle 40 connected to the second wheel 42 the driven shaft of the motor vehicle carries. In 2 is that in 1 not shown in detail gear housing 44 recognizable, in whose in 2 Flange shown on the right can be flanged electrical machine.

The superposition gearbox 18 is designed as a negative gear, ie with stationary web 26 are the directions of the sun 22 and ring gear 28 opposing each other. The ring gear 28 of the superposition gearbox 18 drives the stepped planet 36 the preliminary stage 20 at.

The preliminary stage 20 can with three evenly distributed over the circumference step planets 36 be executed, the web 37 the preliminary stage 20 is fixed to the housing. About the sun wheel 38 the preliminary stage 20 becomes the axle flange threshold 40 and thus the left wheel 42 driven.

The entire gear arrangement 10 has only a circumferential bridge 26 , The shaft with the highest torque in each partial transmission, ie the bridge 26 in the superposition gearbox 18 and the sun wheel 38 in the preliminary stage 20 , are each driveable with the associated axle flange 30 respectively. 40 connected. This means that it is in the whole gear arrangement 10 There is no shaft that would have to carry a torque above the wheel torque. In addition, the two partial transmissions 18 . 20 each loaded only with the half applied by the electric machine axle torque. Correspondingly less robust, the individual elements must be designed, which contributes to a significant weight saving.

In the 2 illustrated, special construction is a very compact design, because in total only three tooth engagement planes are realized in the axial direction. The summary of the functional ring gears 28 and 34 to a common component, both as a ring gear 28 of the superposition gearbox 18 as well as a ring gear 34 the preliminary stage 20 serves, represents a further advance in terms of an axially compact design. The leadership of the ring gear 28 / 34 can be done via the teeth, so no own ring gear storage is required.

In the illustrated embodiment, the planets are running 24 in the superposition gearbox 18 axial forces. The helix angles of the gears of the stepped planets 36 the preliminary stage 20 can be chosen so that there also no axial force must be supported.

The 3 and 4 show, in each case in a different representation, a second design of the transmission arrangement according to the invention 10 , The transmission components of the arrangement 10 are in this design in the interior of the rotor 16 the electric machine 12 arranged. The stator 14 the electric machine 12 , which is formed in an inner rotor shape, is fixed to the housing 44 connected. Also in the 3 and 4 shown design has a superposition gear 18 and a preliminary stage 20 on. The superposition gearbox 18 is constructed according to the same principle as the superposition gearbox 18 of the 1 and 2 , For explanation, reference should therefore be made to the above.

The design of the 3 and 4 However, it differs from the design of the 1 and 2 in the design of the preliminary stage 20 as well as in the coupling of the preliminary stage 20 with the superposition gearbox 18 , In the design of the 3 and 4 is the ring gear 28 of the superposition gearbox 18 with the sun wheel 38 the preliminary stage 20 connected. The planets 36 the preliminary stage 20 standing on the bridge 37 are stored, are designed as simple, non-stepped planets. They mesh with both the sun wheel 38 as well as with the ring gear 34 , in this design as a separate and from the ring gear 28 the superposition gear various ring gear is formed. The ring gear 34 is with the left axle flange threshold 40 connected to the left wheel 42 wearing.

In the in the 3 and 4 Embodiments shown are the individual partial transmission, that is, the superposition gear 18 and the precursor 20 identical in construction. Thus, two identical transmission parts are installed, whereby significant cost advantages can be achieved via the scaling effects. From the structure of the gear assembly 10 from two identical partial transmissions 18 . 20 shows that only an axle ratio of about 5.2 is possible, which can be achieved with partial transmissions of a stand ratio of about 1.6. As with the design of the 1 and 2 runs throughout the gear assembly 10 only a single jetty 26 around.

Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. In the light of the disclosure herein, those skilled in the art will be offered a wide range of possible variations. In particular, statements such as "right" and "left" each refer only to the discussed figures and represent no limitation of the invention.

LIST OF REFERENCE NUMBERS

10

transmission assembly

12

electric machine

14

Stature of 12

16

Rotor of 12

18

first planetary gearbox / superposition gearbox

20

second planetary gear / precursor

22

Sun gear / input shaft of 18

24

Planet wheel of 18

26

Bridge / output shaft of 18

28

Ring gear / coupling shaft of 18

30

first (right) axle flange threshold

32

first (right) drive wheel

34

Ring gear of 20

36

Planet of 20 / Step planet

36a

first axial section of 36

36b

second axial section of 36

36 '

Planet of 20 / ungestufter planet

37

Footbridge of 20

38

Sun wheel of 20

40

second (left) axle flange threshold

42

second (left) drive wheel

44

casing

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 102007055883 A1 [0002]

Claims (10)

Transmission arrangement for a motor vehicle, comprising - a housing ( 4 ), - an electric machine ( 12 ) with a housing-fixed stator ( 14 ) and one relative to the stator ( 14 ) rotatably mounted rotor ( 16 ) and - a transmission device with a first spur planetary gear ( 18 ), which by means of its input shaft ( 22 ) with the rotor ( 16 ) and by means of its output shaft ( 26 ) with a first axle flange threshold ( 30 ), and a second spur planetary gear ( 20 ), which by means of its input shaft ( 34 ; 38 ) with a coupling shaft ( 28 ) of the first planetary gear ( 18 ) and by means of its output shaft ( 34 ; 38 ) with a second axle flange threshold ( 40 ), wherein the first planetary gear ( 18 ) forming its input shaft, coaxial with the rotor ( 16 ) and connected thereto, the first sun gear ( 22 ), a coupling shaft forming its ring gear ( 28 ) and its output shaft forming, coaxial with the rotor ( 16 ) and coaxial with the first axle flange ( 30 ) and connected to this web ( 26 ), which is a simple set of rotatably mounted first planet gears ( 24 ), on the one hand with the first sun ( 22 ) and on the other hand with the first ring gear ( 28 ), and wherein the second planetary gear ( 20 ) a second sun gear (38) and a housing-fixed, second web ( 37 ), which is a simple set of rotatably mounted second planet gears ( 36 ; 36 ' ), with the second sun gear ( 38 ), characterized in that the second planetary gear ( 20 ) as a simple minus planetary gear with a second ring gear ( 34 ) is formed, the second planetary gears ( 36 . 36 ' ) additionally with the second ring gear ( 38 ) comb. Gear arrangement according to claim 1, characterized in that the second ring gear ( 34 ) the input shaft of the second planetary gear ( 20 ) and the second sun gear ( 38 ) the output shaft of the second planetary gear ( 20 ). Gear arrangement according to claim 2, characterized in that the first and the second ring gear ( 28 . 34 ) are formed as a common component. Gear arrangement according to one of claims 2 to 3, characterized in that the second planet gears ( 36 ) as stepped planets with a first axial section ( 36a ) and a second axial section ( 36b ) are formed smaller scale. Gear arrangement according to claim 4, characterized in that the second planet gears ( 36 ) over their first axial sections ( 36a ) with the second ring gear ( 34 ) and via their second axial sections ( 36b ) with the second sun gear ( 38 ) comb. Gear arrangement according to one of claims 4 to 5, characterized in that the number of teeth of the first planetary gears ( 24 ) with the number of teeth of the first axial sections ( 36a ) of the second planetary gears ( 36 ) matches. Gear arrangement according to claim 1, characterized in that the second sun gear ( 38 ) the input shaft of the second planetary gear ( 20 ) forms and the second ring gear ( 34 ) the output shaft of the second planetary gear ( 20 ). Gear arrangement according to claim 7, characterized in that the first and the second planetary gear ( 18 . 20 ) are constructed identical. Gear arrangement according to claim 7, characterized in that the state ratios of the first and the second planetary gear ( 18 . 20 ) Be 1.62 ± 0.02. Gear arrangement according to one of the preceding claims, characterized in that the first and the second planetary gear ( 18 . 20 ) in axial proximity to each other together in the interior of the rotor ( 16 ) of the electric machine ( 12 ) are arranged.

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