WO2012163438A1 - Transmission arrangement for a motor vehicle - Google Patents

Abstract

The invention relates to a transmission system for a motor vehicle, comprising a housing (4), an electric motor (12) having a stator (14) fixed to the housing and a rotor (16) mounted rotatably relative to the stator (14), and a transmission device having a first spur-cut planetary gear unit (18), which unit is connected to the rotor (16) by means of the input shaft (22) of the unit and to a first axial flanged shaft (30) by means of the output shaft (26) of the unit, and having a second spur-cut planetary gear unit (20), which is connected to a coupling shaft (28) of the first planetary gear unit (18) by means of the input shaft (34; 38) of the second unit and to a second axial flanged shaft (40) by means of the output shaft (34; 38) of the second unit. The first planetary gear unit (18) has a first sun gear (22) that forms the input shaft of the planetary gear unit, is arranged coaxially with respect to the rotor (16) and is connected thereto. Said first planetary gear unit also has a ring gear (28) that forms the coupling shaft thereof and a planet carrier (26) that forms the output shaft thereof, is arranged coaxially with respect to the rotor (16) and coaxially with respect to the first axial flanged shaft (30) and is connected thereto, said planet carrier supporting a single set of rotatably mounted first planet wheels (24) that mesh with both the first sun gear (22) and the first ring gear (28). The second planetary gear unit (20) has a second sun gear (38) and a second planet carrier (37) that is fixed to the housing and supports a single set of rotatably mounted second planet wheels (36; 36') that mesh with the second sun gear (38). The invention is characterized in that the second planetary gear unit (20) is formed as a simple minus planetary gear unit having a second ring gear (34), of which the second planet wheels (36, 36') additionally mesh with the second ring gear (38).

Description

 description

Gear arrangement for a motor vehicle

Field of the invention

The invention relates to a transmission arrangement for a motor vehicle, comprising

a housing,

 - An electric machine with a housing fixed stator and a rotatably mounted relative to the stator rotor and

 a transmission device having a first planetary gear, which is connected by means of its input shaft to the rotor and by means of its output shaft to a first axle flange,

 and a second spur planetary gear, which is connected 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 Achsflanschwelle,

wherein the first planetary gear forming a its input shaft, coaxial with the rotor and connected thereto, the first sun gear, a coupling shaft forming ring gear and its Ausgangsweile forming, arranged coaxially to the rotor and coaxial with the first Achsflanschwelle 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 an axle drive device is known from 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. His bridge, which carries a simple, not stepped planetary gear set, serves as an output shaft and is with the 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

Overlay gear with the second component of the transmission device, which will be hereinafter referred to as a 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 larger diameter axial portion of the step planets, serves as the input shaft of the precursor and is connected to the coupling shaft, i. 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 for the situation-specific distribution of the

Torque on the two axle flanges to stabilize the ride, 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 get the same sign: The precursor is in this switch position as a minus-Doppelplanetenradsatz with two suns, fixed landing stage and stepped planets:

 Due to the many tooth engagements, the efficiency of the preliminary stage in the drive switching position is not optimal. A transfer of this configuration to a pure one

Achsantriebsvorrichtung, ie without switching option for torque vectoring, 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 to take place in the superposition gear, uneven distribution of the torque of the electric machine to 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 continues to make possible, so that the latter not in space-saving, paraxial

Arrangement must be coupled via an efficiency-reducing, additional spur gear. For this purpose, the precursor is a simple planetary gear with sun,

planet-supporting web and ring gear and formed with negative stand translation. As a standard translation here, as is common practice, the ratio between the speeds of the central shafts, i. 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 invention

Transmission arrangement is assumed to be an electrical machine with an output torque of 100 Nm. The state translation of designed as a simple minus planetary gear superposition gearbox is assumed as ₂ = -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 is rectified to this. 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 precursor with a stand ratio of i _V s = -1, 25 should be interpreted. 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 implements the axle ratio required for coupling an electric motor which rotates quickly in comparison with the wheels of a motor vehicle, but without an additional spur gear stage.Of course, the invention is not based on the above

Design example limited. 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

Combining planetary gears via their first axial sections with the second ring gear and their second axial sections with the second sun gear. This means that the planet gears with their axial portion of larger circumference with the ring gear and with their Axiaiabschnitt smaller circumference mesh with the sun gear of the precursor. It is particularly preferred that the number of teeth of the first planetary gears coincide with the number of teeth of the first axial sections of the second Pianetenräder. 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 preliminary stage 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 preliminary stage thus corresponds to the basic structure of the

Superposition gear. 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 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

Figure 1: a schematic representation of a first design of the invention

 Transmission assembly

FIG. 2: a partially sectioned perspective view of the design of FIG. 1

Figure 3: a schematic representation of a second design of the invention

Transmission assembly Figure 4 is a partially sectioned perspective view of the construction of Figure 3. Detailed Description of Preferred Embodiments

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

Figures 1 and 2 show, each in a different representation, a first preferred embodiment of the transmission assembly 10 of the invention. The gear assembly 10 shows a (not shown in Figure 2) electric machine 12 having a stator 14 and a rotor 16. In the illustrated embodiment the electric machine 12 in

conventionally designed as an internal rotor machine. Next includes the

Gear arrangement 10, a first planetary gear 18 and a second planetary gear 20. The first planetary gear 18 is also referred to as a superposition gear. The second planetary gear 20 is also referred to as a precursor. The rotor 16 of the

Electric machine 12 is connected to the sun gear 22 of the superposition gear 18. The sun gear 22 meshes with a set of planet gears 24 which are rotatably mounted on a web 26. In addition, the planet gears 24 mesh with a ring gear 28. The web 26 is provided with a first, in the illustrated embodiment right Achsflanschwelle 30th

connected, which carries the right wheel 32 in the illustration of the driven axle of the motor vehicle, not shown. It can be seen that the right Achsflanschwelle 30 designed as a hollow shaft sun gear 22 and the electric machine 12 passes coaxially.

The pre-stage 20 comprises a ring gear 34 which is connected to the ring gear 28 of the

Overlay gear 18 formed as a common component and with the same

Number of teeth is equipped. With this ring gear 34 meshes a first axial portion 36 a larger diameter of a set of stepped planetary 36 having axially adjacent to the first axial portion 36 a second axial portion 36 b, which has a smaller

Diameter has. The mesh with this axial portion 36b of smaller diameter

Stepped planetary 36 with a sun gear 38, which is connected to a second, in the figure left Achsflanschwelle 40, the second wheel 42 of the driven shaft of

Car carries. In Figure 2, the transmission housing 44 is not shown in detail in Figure 1 can be seen on the right in Figure 2 flange shown the electric machine can be flanged.

The superposition gear 18 is designed as a negative gear, i. at a stationary web 26, the directions of rotation of sun 22 and ring gear 28 are opposite to each other. The

Ring gear 28 of the superposition gear 18 drives the stepped planetary gear 36 of the precursor 20 at. The pre-stage 20 can be executed with three evenly distributed over the circumference step planets 36, wherein the web 37 of the precursor 20 is fixed to the housing. About the sun gear 38 of the precursor 20, the Achsflanschwelle 40 and thus the left wheel 42 is driven.

The entire transmission assembly 10 has only one circumferential ridge 26. The shaft with the highest torque in each sub-transmission, i. the web 26 in the superposition gear 18 and the sun gear 38 in the precursor 20 are each connected to the associated Achsflanschwelle 30 and 40 respectively. This means that it is in the whole

Gear assembly 10 is no wave that would have to perform a torque above the wheel torque. In addition, the two partial transmissions 18, 20 are each loaded with only half the axial moment applied by the electric machine. Accordingly, less robust, the individual elements must be designed, resulting in a clear

Weight saving contributes.

The illustrated in Figure 2, 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, which serves both as a ring gear 28 of the superposition gear 18 and as a ring gear 34 of the precursor 20, 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 planet 24 run in the superposition gear 18 without axial force. The helix angles of the teeth of the stepped planets 36 of the precursor 20 can be selected so that there also no axial force must be supported.

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

However, the design of Figures 3 and 4 differs from the design of Figures 1 and 2 in the design of the precursor 20 and in the coupling of the precursor 20 with the

Superposition gear 18. In the design of Figures 3 and 4, the ring gear 28 of the Superposition gear 18 connected to the sun gear 38 of the precursor 20. The planets 36 of the precursor 20, which are mounted on the housing-fixed web 37, are formed as simple, non-stepped planets. They mesh with both the sun gear 38 and the ring gear 34, which in this design as a separate and from the ring gear 28 of the

Superposition gear different ring gear is formed. The ring gear 34 is connected to the left axle flange 40 which carries the left wheel 42.

In the embodiments shown in Figures 3 and 4, the individual partial transmission, that is, the superposition gear 18 and the precursor 20 are 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 of two identical partial transmissions 18, 20 results in 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 Figures 1 and 2 runs in the entire gear assembly 10 only a single web 26 to.

Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. Those skilled in the art will be aware of a broad spectrum in light of the disclosure herein

Variations are given to the hand. 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

transmission assembly

 electric machine

 Stator of 12

 Rotor of 12

 first planetary gearbox / superposition gearbox second planetary gearbox / precursor

 Sun gear / input shaft of 18

 Planet wheel of 18

 Bridge / output shaft of 18

 Ring gear / coupling shaft of 18

 first (right) axle flange threshold

 first (right) drive wheel

 Ring gear of 20

 Planet of 20 / Stufenplanet

a first axial section of 36

b second axial section of 36

1 planet of 20 / ungestufter planet

 Footbridge of 20

 Sun wheel of 20

 second (left) axle flange threshold

 second (left) drive wheel

 casing

Claims

claims Gear arrangement for a motor vehicle, comprising  a housing (4),  - An electric machine (12) with a housing fixed stator (14) and a relative to the stator (14) rotatably mounted rotor (16) and  - A transmission device with a first spur planetary gear (18) which is connected by means of its input shaft (22) with the rotor (16) and mittete its output shaft (26) with a first Achsflanschwelle (30)  and a second spur planetary gear (20) which is connected by means of its input shaft (34; 38) to a coupling shaft (28) of the first planetary gear (18) and by means of its output shaft (34; 38) to a second axle flange (40), wherein the first planetary gear (18) has a first sun gear (22) arranged coaxially with the rotor (16) forming its input shaft, a ring gear (28) forming its coupling shaft and an output shaft forming it, coaxial with the rotor ( 16) and coaxial with the first Achsflanschwelle (30) arranged 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) comb and wherein said second planetary gear (20) carries a second sun gear (38) and a housing-fixed second land (37) which carries a simple set of rotatably mounted second planetary gears (36; 36 ') meshing with said second sun gear (38). having, characterized, 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 ') in addition with the second ring gear (38) mesh. Gear arrangement according to claim 1, characterized, in that the second ring gear (34) forms the input shaft of the second planetary gear (20) and the second sun gear (38) forms the output shaft of the second planetary gear (20). 3. Gear arrangement according to claim 2,  characterized,  the first and the second ring gear (28, 34) are formed as a common component. 4. Gear arrangement according to one of claims 2 to 3,  characterized,  in that the second planetary gears (36) are designed as stepped planets with a larger circumference of the first axial section (36a) and of a smaller circumference of the second axial section (36b). 5. gear arrangement according to claim 4,  characterized,  in that the second planet wheels (36) mesh with the second ring gear (34) via their first axial sections (36a) and with the second sun gear (38) via their second axial sections (36b). 6. Gear arrangement according to one of claims 4 to 5,  characterized,  that the number of teeth of the first planet gears (24) with the number of teeth of the first  Axial sections (36a) of the second planet gears (36) coincides. 7. Gear arrangement according to claim 1,  characterized,  in that the second sun gear (38) forms the input shaft of the second planetary gear (20) and the second ring gear (34) forms the output shaft of the second planetary gear (20). 8. gear arrangement according to claim 7,  characterized,  that the first and the second planetary gear (18, 20) are of identical construction. 9. gear arrangement according to claim 7,  characterized, the level ratios of the first and second planetary gears (18, 20) are 1.62 ± 0.02. 10. Transmission arrangement according to one of the preceding claims,  characterized,  the first and the second planetary gear (18, 20) are arranged in axial proximity to one another in common in the interior of the rotor (16) of the electric machine (12).