WO2015067247A1

WO2015067247A1 - Planetary transmission with cohesively connected planet carrier

Info

Publication number: WO2015067247A1
Application number: PCT/DE2014/200103
Authority: WO
Inventors: Iñaki FERNANDEZ; Harald Martini; Thorsten Biermann
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2013-11-08
Filing date: 2014-03-03
Publication date: 2015-05-14
Also published as: DE102014203830A1

Abstract

The invention relates to a planetary transmission (1) for a motor vehicle, having a drive input gear (2) from which torque can be transmitted via a planet carrier (4) to a first planetary gear set (7) and/or to a second planetary gear set (8) and to a first and/or a second sun gear (9, 10), and having a bridging component (3) which is connectable to the drive input gear (2) and/or to the planet carrier (4). According to the invention, a cohesive connection (11, 12) is arranged between the bridging component (3) and the planet carrier (4) and is dimensioned such that 90% to 100% of the torque that is introduced into the drive input gear (2) is transmitted via the cohesive connection (11, 12).

Description

Description of the invention Planetary gear with cohesively connected planet carrier

description

Field of the invention

The invention relates to a planetary gear for a motor vehicle, with a drive wheel, from which via a planet carrier torque to a first planetary gear and / or a second planetary gear and then to a first and / or a second sun gear can be passed, and with a bridging component , which is connectable to the drive wheel and / or the planet carrier.

It is known that a planetary gear can be used for example as a differential or differential gear in a final drive of a motor vehicle can. Usually, such a planetary gear has a drive wheel, in which a torque of, for example, an output shaft of a vehicle transmission is introduced. The drive wheel is connected to a planetary carrier and transmits the introduced torque, less possibly occurring losses, such as friction losses, via a first and / or a second planetary gear set to a first and / or second sun gear. Reference is made to DE 10 2007 040 475 A1, whose functional and geometrical features are to be considered as integrated here.

It is also known that there is a general desire in vehicle development to keep the vehicle weight as low as possible in order to save energy in the form of fuel or electrical energy in this way. This desire also exists in the drive components of a vehicle, such as the final drive. Although the planetary gear described above meets the requirements of today's vehicle development in functional terms, it would be desirable to reduce the weight of such a planetary gear.

It is therefore an object of the present invention to provide a planetary gear for a motor vehicle available, in which with structurally simple means as possible, a weight reduction compared to a planetary gear from the prior art is achieved and eliminated or at least mitigated the disadvantages of the prior art are.

Disclosure of the invention In a generic planetary gear the above object is achieved in that between the bridging and the planet carrier a cohesive connection is arranged and dimensioned so that 90% to 100% of the torque introduced into the drive wheel via the cohesive connection be transmitted. In other words, the bridging component and the planetary carrier are connected to one another exclusively by means of a cohesive connection, that is to say without an additional positive or positive connection.

Under a cohesive connection in this context, in particular a welded joint, a solder joint or an adhesive bond to understand. In this case, different welding methods can be used for the realization of, for example, the welded connection. Laser welding, friction welding and (protective) gas welding have proved to be particularly suitable welding processes.

Ideally, the entire torque introduced into the drive wheel should be transmitted exclusively via the integral connection. The torque transmission in a planetary gear can in practice all- However, it may also be lossy, so that not the entire torque is transferable. The claimed value range of 90% to 100% should already take into account possible transmission losses, for example due to friction between the components. This means that in principle the entire torque introduced minus possible transmission losses is transferable. In other words, the introduced torque should at least partially, but then be transferable exclusively via the cohesive connection. The bridging component may, for example, be arranged radially on the outside of the planet carrier, so that the planet carrier is connected from the radially inner direction to the bridging component by means of the integral connection.

The inventive cohesive connection between the bridging member and the planet carrier a particularly easy-built planetary gear is realized because, for example, can be dispensed with a comparatively difficult to build screw and / or rivet connection between these components. This means that weight is saved simply by dispensing with the individual screws or rivets. In addition, can be dispensed with the components to be connected to flanges or webs for attaching the screws or rivets, so that the components to be connected can also be comparatively simple design, the waiver of these flanges or webs again causes additional weight savings. It is possible, for example, to use a rotationally symmetrical bridging component or drive wheel.

In addition to the weight saving, a simplification or shortening of the manufacturing process is achieved by the planetary gear according to the invention, since a cohesive connection can be made comparatively easily. Furthermore, the cohesive connection also increases the mechanical rigidity of the planetary gear. Advantageous embodiments are also claimed in the subclaims and are explained in more detail below.

So it is for the mechanical rigidity of the planetary gear and also for the manufacturing process of the same advantageous if the cohesive connection is formed circumferentially between the bridging member and the planet carrier. Due to the radially encircling cohesive connection, a particularly high mechanical rigidity can be achieved. Alternatively, the cohesive connection can also be formed over the circumference of the planet carrier and / or the drive wheel selectively and / or in sections. This means that instead of a continuous, continuous cohesive connection, only individual connection points are created, which connect individual points and / or individual sections of the planar carrier and of the bridging component with one another.

An advantageous development of the invention provides that the cohesive connection has a plurality of connection points, which are offset from each other over the circumference of the planet carrier and / or the drive wheel to each other. Preferably, two, three, four, five, six, seven, eight, nine or more joints may be provided. Further preferably, the cohesive connection has three connection points, which are offset by 120 ° from each other over the circumference of the planetary carrier and / or the drive wheel.

It has proven to be advantageous if the planet carrier is designed in several parts and in particular has two planet carrier halves, which are each arranged in an axial end region of the drive wheel. The two planet carrier halves may be formed substantially disc-shaped.

In this context, it has been found to be particularly advantageous if at least one of the planetary carrier halves is pressed into the bridging component. Both halves of the planetary carrier can be integrated into the transmission be bridged component. By pressing a particularly small spatial distance between the components to be connected is achieved, so that provided for the connection of these components cohesive connection can be made very simple and accurate.

For the production of cohesive connection, it is advantageous if the planet carrier halves are produced without cutting and / or deep-drawn sheet metal parts. For example, these sheet metal parts can be made of a suitable steel by cold forming. In particular, when the cohesive connection is a welded joint, non-cutting produced, such as deep-drawn / cold-formed sheet metal parts are particularly suitable because of their good weldability.

It has been found that by the cohesive connection between see the planet carrier and the drive wheel or by dispensing with an additional positive or non-positive connection and a comparatively simple geometry of the planet carrier halves is made possible. Thus, it is possible to realize a largely planar geometry of the planet carrier halves, since no Anbindbarkeit the same must be considered on flanges or webs of the bridging member for a screw or rivet.

It is also expedient if the bridging component is integrally formed as a monolithic part with the drive wheel or, alternatively, rotatably connected to the material-separate, designed as a spur gear drive wheel. This means that the bridging component to be connected to the planetary carrier by means of the cohesive connection is formed either as an integral component by the drive wheel itself and accordingly has a spur wheel outer contour or an external toothing. In this case, the bridging member is then necessarily connected to the drive wheel because it is formed integrally therewith. Or, alternatively, the bridging member may also be a component materially formed separately to the drive wheel, which in turn by means of another, any connection with the trained as a spur gear drive wheel is connected. This connection between the Überrückungsbauteil and the drive wheel can be realized in particular by a material, positive or non-positive connection. For example, a weld, screw or rivet connection may be provided.

The bridging member may be formed, for example, as externally toothed ring gear or spur gear. For a particularly simple feasibility of the cohesive connection between the bridging member and the planet carrier, it is advantageous if the bridging member has a cylindrical inner recess. This means that the bridging component can be configured in the radial direction without flangeless, without projections, flat, smooth, continuous or the like. In this way, a particularly accurate cohesive connection, in particular during welding can be achieved.

It is advantageous if the first sun gear is connectably connected to the second sun gear via the first planetary gearset and the second planetary gearset.

The abovementioned, advantageous embodiments of the planetary gear according to the invention can be used particularly well if the planetary gear is designed as Leichtbasustirnradgetriebe or is used as such. Such Leichtbaustirnradgetriebe is then characterized due to the inventive design by a comparatively low weight, high mechanical rigidity and ease of manufacture. Further aspects of the invention provide that the planetary gear can have at least two toothing planes, that is to say an asymmetrical toothing. It is also possible that the toothed contact between the planet gears or differential gears is located in an axially disposed plane above the smaller sun.

Furthermore, a substantially annular tool in the form of a fixing ring, which holds a planet carrier half in an aligned welding position on the bridging component or the drive wheel, can also be used for the production or production of the integral connection. For this purpose, the tool may have, arranged over its circumference, extending in the axial direction of the planetary gear pin. The pins may be adapted to engage in appropriately configured fixing holes of the respective planet half.

Furthermore, the invention also relates to a method for producing and / or mounting a planetary gear. The manufacturing process may include the following steps:

Providing a drive wheel which is preferably designed as an externally toothed spur gear and with which also preferably a bridging component is either integrally formed or connected,

Providing a one-part or multi-part planetary carrier, which is preferably formed by two planetary carrier halves, which may be produced without cutting,

Providing at least one planetary gear set and at least one sun gear,

- Arranging or introducing the at least one planetary gear and the at least one sun gear within the drive wheel - Pressing the planet carrier, preferably the planetary carrier halves, in the drive wheel, wherein the pressing in axial end regions of the drive wheel can take place, and - cohesive connection, preferably by welding, the planet carrier with the drive wheel.

In other words, the invention particularly relates to a planetary gear with at least one planet carrier, which is optionally pressed into a drive wheel of a planetary gear and additionally secured by means of a welded connection between the drive wheel and planet carrier. With the planetary gear according to the invention u.a. achieved that the drive wheel can be designed rotationally symmetric and easier to build. Furthermore, in the planetary gear an asymmetrical toothing, that is, two toothing planes in a differential toothing, be provided. In addition, a toothed contact between the differential gears can be located in an axially arranged above or next to a smaller sun. The invention will be explained in more detail below with the aid of a drawing, in which different embodiments are shown. Show it:

Fig. 1 shows an inventive planetary gear with a cohesive

Connection between a bridging component and a planetary carrier in a longitudinal section,

2 shows an enlarged detail of the integral connection shown in FIG. 1 between the bridging component and the planetary carrier in a longitudinal section,

Fig. 3a shows an inventive planetary gear with a cohesive

Connection between the bridging component and the planet carrier of a first exemplary embodiment in a side view, 3b shows the planetary gear according to the invention from Figure 3a with a material connection between the bridging member and the planet carrier in a longitudinal section,

Fig. 3c shows an enlarged detail of the material connection shown in Figure 3b between the bridging member and the planet carrier in a longitudinal section, Fig. 4a shows an inventive planetary gear with a cohesive

Connection between the bridging component and the planet carrier of a second exemplary embodiment in a side view,

4b shows the planetary gear according to the invention from FIG. 4a with a coherent connection between the bridging component and the planet carrier in a longitudinal section,

4c shows an enlarged detail of the cohesive connection between the bridging component and the planet carrier shown in FIG. 3b in a longitudinal section, and a schematic illustration of an alternative, materially separate embodiment of the drive wheel and the bridging component.

The figures are merely schematic in nature and are only for the understanding of the invention. The same elements are provided with the same reference numerals.

In Fig. 1 the basic structure of a Planetengetrie- bes invention 1 is shown in a longitudinal section. In this embodiment, the planetary gear 1 is designed as Leichtbaustradradifferential, as used for example as an aggregate in a (not shown) final drive of a (also not shown) motor vehicle. The planetary gear 1 has a drive wheel 2 designed as an external and helical spur gear, which merges in a radially inwardly directed direction into an annular bridging component 3, which in this embodiment is connected in one piece to the drive wheel 2 as a monolith component. That is, the lock-up member 3 is arranged in the radial direction of the planetary gear 1 within the drive wheel 2. In addition, the planetary gear 1 has a two-part in this embodiment designed planet carrier 4, which has a first planet carrier half 5 and a second planet carrier half 6. In the case of the two planetary carrier halves 5 and 6, these are non-cutting, deep-drawn steel sheets, with the selected steel being distinguished by good weldability. The planetary carrier halves 5 and 6 of the planet carrier 4 are each arranged in an axial end region of the drive wheel 2, so that they are in the installed state opposite and form a housing of the planetary gear 1.

Within the planet carrier halves 5, 6 functioning as a housing, the planetary gear 1 also has a first planetary gearset 7 and a second planetary gearset 8 and a first sun gear 9 and a second sun gear 10. With this arrangement or with this structural design of the planetary gear 1 is it is possible to pass on a torque introduced into the drive wheel 2, for example, from a transmission output shaft (not shown) via the bridging component 3 to the planet carrier 4, the first planetary gearset 7 or a second planetary gearset 8 and to the first sun gear 9 and the second sun gear 10, respectively.

Furthermore, it can be seen in FIG. 1 that, for a non-rotatable and thus torque-transmitting connection between the annular bridging component 3 formed integrally with the drive wheel 2 in this exemplary embodiment and the two planetary carrier halves 5, 6 of the planet carrier 4, a cohesive one in each case Compound 1 1 and 12 between the bridging part 3 and the respective planet carrier half 5, 6 is formed is. In this embodiment, the cohesive connections 1 1, 12 are each a welded connection, which can be produced for example by laser welding. The cohesive connections 1 1, 12 are dimensioned and / or arranged such that the torque introduced into the drive wheel 2 is at least partially or better transmitted completely to the planet carrier 4.

Due to the cohesive connection for the compounds 1 1, 12, the drive wheel 2 and the bridging member 3 can be structurally simple compared to the prior art. In this embodiment, the bridging member 3 formed integrally with the drive wheel 2 has an annular shape without ridges or flanges. In particular, the bridging component 3 has a stepless, cylindrical, flangeless, featureless, smooth or continuous inner recess 13. Thus, the drive wheel 2 and the bridging member 3 are rotationally symmetrical and are characterized by a comparatively simple manufacturability and a low weight. Accordingly, but also accounts for the planet carrier halves 5, 6 corresponding webs or flanges, so that the planet carrier halves 5, 6 are comparatively easy to produce. Overall, the planetary gear 1 is characterized by a comparatively low overall weight.

In Figure 2, which shows an enlarged partial section of the planetary gear 1 according to Figure 1, it can be seen that the cohesive connection 1 1 or 12 is formed between the bridging part 3 and the respective planet carrier half 5 and 6 respectively.

Furthermore, in FIG. 3a, which shows the planetary gear 1 with the integral connection 12 between the bridging component 3 and the planet carrier half 6 of a first exemplary embodiment in a side view, it can be seen that the material-locking connection formed as a welded connection is designed to be circumferential. As shown in FIGS. 3 b and 3 c, which show a longitudinal section through the planetary gear 3 according to FIG. know that the rest, the basic structure of the planetary gear 3 is unchanged from the above description.

According to FIG. 4 a, which shows the planetary gear 1 with the integral connection 12 between the bridging component 3 and the planetary carrier half 6 in a side view of a second exemplary embodiment, the cohesive connection 12 can also be embodied selectively or in sections instead of circulating. In this exemplary embodiment, the integral connection 12 embodied as a welded connection has three welds 14, 15 and 16, which are each arranged at a spacing of approximately 120 ° over the circumference of the components to be connected. Compared to the first embodiment, this embodiment is characterized by a relatively short production time. The decision as to whether the cohesive connections 1 1, 12 are executed circumferentially or selectively or in sections can be made, for example, as a function of a respective customer request and / or the magnitude of the torque to be transmitted.

The manufacture or assembly of the planetary gear 1 can proceed as described below:

Providing the drive wheel 2, which is designed here as an externally toothed spur gear and is formed in one piece with the bridging component 3,

Providing the planet carrier 4, which is formed here by two planet carrier halves 5, 6 which are produced without cutting,

Providing the planetary gear sets 7, 8 and the sun gears 9, 10,

Arranging or introducing the planetary gear sets 7, 8 and the sun gears 9, 10 within the drive wheel 2, - Pressing the planet carrier 4 and the planet carrier halves 5, 6 in the drive wheel 2, wherein the pressing can be done in axial end portions of the drive wheel, - cohesive bonding (preferably from two sides), here by welding, the planet carrier 4 with the drive wheel. 2 or the bridging component 3.

Optionally, for fixing and holding the planetary carrier 4 in a welding position, a substantially annular tool (not shown) may also be used, which has pins extending in the axial direction of the planetary gear 1. The pins may be distributed over the circumference of the tool and cooperate with fixing holes, which may be provided in the planet carrier halves 5, 6 respectively.

Starting from the illustrated embodiments, the invention can be modified in many ways.

For example, as indicated in FIG. 5, it is conceivable that the bridging component 3 is not formed in one piece as a monolithic part with the drive wheel 2, but instead is formed materially separately and connected to the drive wheel 2 by means of a suitable connection type. In other words, the bridging member 3 and the drive wheel 2 may initially be formed as material-separate components, which are then joined together. For example, it is conceivable that the bridging member 3 and the drive wheel 2 are connected to each other by means of a cohesive connection and previous press-fitting. Alternatively, however, it is also conceivable for the bridging component 3 and the drive wheel 2 to be screwed, riveted or connected to one another in a suitable manner. LIST OF REFERENCE NUMBERS

1 planetary gear

2 drive wheel

3 bridging component

4 planet carrier

5 planet carrier half

6 Planet carrier half

7 first planetary gear set

8 second planetary gear set

9 first sun wheel

10 second sun wheel

1 1 cohesive connection

12 cohesive connection

13 inner recess

14 weld

15 weld

16 weld

Claims

claims

Planetary gear (1) for a motor vehicle, with a drive wheel (2) from which via a planet carrier (4) torque to a first planetary gear set (7) and / or a second planetary gear set (8) and to a first and / or a second sun gear (9, 10) is weitergebbar, and with a bridging member (3) which is connectable to the drive wheel (2) and / or the planet carrier (4), characterized in that a cohesive connection (1 1, 12) between the bridging member (3) and the planet carrier (4) is arranged and dimensioned so that 90% to 100% of the drive wheel (2) introduced torque via the cohesive connection (1 1, 12) are transmitted.

Planetary gear (1) according to claim 1, characterized in that the cohesive connection (1 1, 12) circumferentially between the bridging member (3) and the planet carrier (4) is formed.

Planetary gear (1) according to claim 1, characterized in that the cohesive connection (1 1, 12) over the circumference of the planet carrier (4) and / or the drive wheel (2) is formed punctiform and / or in sections.

Planetary gear (1) according to claim 3, characterized in that the cohesive connection (1 1, 12) connecting points (14, 15, 16) which are offset from each other over the circumference of the planet carrier and / or the drive wheel (2).

Planetary gear (1) according to one of claims 1 to 4, characterized in that the planet carrier (4) has two planetary carrier halves (5, 6) which are each arranged in an axial end region of the drive wheel (2). Planetary gear (1) according to claim 5, characterized in that the planetary carrier halves (5, 6) are pressed into the bridging member (3).

Planetary gear (1) according to any one of claims 4 or 5, characterized in that the planetary carrier halves (5, 6) are produced without cutting and / or deep-drawn sheet metal parts.

Planetary gear (1) according to one of claims 1 to 7, characterized in that the bridging member (3) integrally formed as a monolithic part with the drive wheel (2) or non-rotatably connected to the material-separate, designed as a spur gear drive wheel (2).

Planetary gear (1) according to one of claims 1 to 8, characterized in that the bridging member (3) has a cylindrical inner recess (13).

Planetary gear (1) according to one of claims 1 to 9, characterized in that the first sun gear (9) via the first planetary gear set (7) and the second planetary gear set (8) is coupled to the second sun gear (10).