WO2018188692A1

WO2018188692A1 - Planetary transmission

Info

Publication number: WO2018188692A1
Application number: PCT/DE2018/100314
Authority: WO
Inventors: Hans-Walter Wodtke
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2017-04-12
Filing date: 2018-04-09
Publication date: 2018-10-18
Also published as: DE102017107929B4; DE102017107929A1

Abstract

The invention relates to a planetary transmission (1) having a sun gear (2), at least one planetary gear (3) and a ring gear (4), wherein: the ring gear (4) is arranged in a rotatably fixed manner in a housing (5); there is a recess (6 and 7) on the ring gear (4) and/or on the housing (5); and at least one decoupling element (8 and 9) is arranged between the ring gear (4) and the housing (5), which is interlockingly received in the recess (6 and 7).

Description

planetary gear

The invention relates to a planetary gear with a ring gear, which is mounted in a housing of the planetary gear.

Planetary gear are used in motor vehicles, for example, in automatic transmissions or axle differentials. In hybrid vehicles, planetary gears are used as a summing gear to couple the electric motor and the internal combustion engine to a common output.

A planetary gear usually consists of a centrally mounted sun gear, a ring gear and a plurality of planet wheels that roll between the sun gear and ring gear. From this structure explains the term planetary gear, because the planetary gears orbiting the sun so astronomical sense, the planet a sun. The advantage of the planetary gear results from the load distribution on several planetary gears. This makes it possible to transmit high torques in a compact design and to realize correspondingly large transmission ratios. Planetary gear also have a high mechanical efficiency. In this case, planetary gears often have a high operating noise, which arises primarily by the rolling of the gears of the planetary gear and the engagement of the corresponding tooth flanks. While the airborne sound produced within the transmission does not penetrate to any appreciable extent, the vibrations of the gears and carriers are transmitted via the ring gear and a housing connected to the ring gear, which also makes the vibrations audible outside the planetary gear.

From CH 424 410 A a planetary gear with a ring gear, a sun gear and a plurality of planetary gears is known, wherein the ring gear is rotatably mounted on vibration damping elements in the housing of the planet gear. From DE 10 2012 105 549 A1 a planetary gear with a sun gear, a plurality of planet gears and a ring gear is known, wherein the ring gear is rotatably mounted in a housing and wherein damping elements are provided to prevent striking of the ring gear on the housing of the planetary gear.

DE 1 204 076 discloses a planetary gear with two ring gears, two sun gears and a plurality of planet gears, wherein the sun gears and the ring gears are connected to each other via axial bolts to allow the most elastic connection of the gears to a drive train and compensate for misalignments and shocks.

From DE 102 30 861 A1 a motor vehicle transmission in planetary construction is known, in which a damping device is provided to reduce the vibrations between the ring gear and the output shaft in order to reduce the transmitted from the ring gear to the output shaft structure-borne noise and thus the sound emitted to the outside minimize the planetary gear. A disadvantage of such a solution, however, is that only insufficient axial forces can be transmitted by the solution proposed in DE 102 30 861 A1, this solution has an increased space requirement in the radial direction and requires a complex assembly of the planetary gear. In addition, the solution of DE 102 30 861 A1 can not be transferred without significant modifications to a ring gear connected to the housing, since in this case the vibrations are transmitted to the housing and thus the transmission noises are carried to the outside.

The object of the invention is to improve the noise and the vibration behavior in a planetary gear with rotatably mounted ring gear and in particular to reduce the structure-borne sound transmission to the housing. According to the invention the object is achieved by a planetary gear with a sun gear, at least one planetary gear and a ring gear, wherein the ring gear rotatably disposed in a housing, wherein on the ring gear and / or on the housing at least one recess is provided, and wherein between the ring gear and the housing at least one decoupling element is arranged, which is received positively in the at least one recess. The planetary gear according to the invention, it is possible to significantly improve the vibration behavior and noise of the planetary gear and in particular to greatly reduce a transmission of structure-borne noise to the housing of the planetary gear. In this case, the vibration behavior can be tuned by the replacement of the decoupling elements and adapted to the respective intended use. At the same time, the ring gear is centered by the decoupling elements. In this case, the axial forces arising due to helical gears can be supported on the ring gear, so that this solution can be used both for straight-toothed ring gears and for helical gears. The elastic compliance of the bearing can be adjusted via the cross-sectional shape, hardness and profile design of the decoupling elements. It is further provided that, instead of a single decoupling element, a packet of a plurality of layered decoupling elements is arranged between the ring gear and the housing. In this context, a decoupling element is to be understood as meaning an element which, in addition to the energy dissipation, makes it possible to decouple the ring gear from the housing.

According to the invention it is provided that the decoupling element is designed as a corrugated spring. By a corrugated spring, a vibration decoupling between the ring gear and the housing of the planetary gear can be realized in a simple and cost-effective manner. Thus, the corrugated springs can positively transmit torque and thus the ring gear is centered clearly in the housing, recesses are provided both on the ring gear and on the housing, which surround the crests of the corrugated springs partially. The elastic resilience of the storage can preferably via the free Sections of the wave spring and the Wellfederquerschnitt be adjusted. Compliance and damping can also be influenced by shaping the corrugations of the corrugated springs and the recesses in the housing. Furthermore, the spring stiffness can be advantageously influenced by a layering of a plurality of corrugated springs to form a corrugated spring package.

According to the invention, it is provided that the decoupling element is arranged on an axial end face of the ring gear. In order to allow the simplest possible storage of the ring gear in the housing, the decoupling elements are arranged on the axial end faces of the ring gear. As a result, in the axial direction of a power transmission to the housing possible, wherein the running noise occurring due to the rolling of the planetary gears in the ring gear can be effectively damped and thus a decoupling of the vibrations is possible.

Due to the features specified in the dependent claims further improvements and developments of the planetary gear described in the independent claim are possible.

According to an advantageous embodiment of the invention it is provided that the decoupling element is biased in the axial direction. By a corresponding bias of the decoupling elements, it is possible to store the ring gear in the housing. This can prevent the decoupling elements from sliding out of the recesses of the ring gear and / or the housing and shifting undesirably. In addition, the floating bearing of the ring gear leads to an elastic centering and thus to a better load distribution on the planetary gears, since the ring gear receives a limited displaceability, and thus load peaks can be intercepted. This increases the durability of the planetary gear. In a further preferred embodiment of the planetary gear is provided that on the ring gear, a groove or a shoulder is provided, which reduces the width of the ring gear. By a shoulder or a corresponding groove in an axial end face of the ring gear, it is possible to reduce the width of the ring gear in this area, so that additional space for the decoupling elements can be created. Thus, an inventive planetary gear does not require more axial space than a planetary gear in which the ring gear is rigidly fixed in the housing of the planetary gear. Under certain circumstances, however, the space requirement in the radial direction may increase slightly, because the ring gear must be made with a greater material thickness and thus thicker to absorb the forces and moments.

It is particularly preferred if on both sides of a respective groove or a shoulder are provided on the ring gear, which reduces the width of the ring gear. By two paragraphs or two grooves can be saved on both sides according to space to create the space required for the decoupling between the ring gear and the housing. As a result, forces and moments can be absorbed elastically in both axial directions, without the ring gear striking the housing and thus the risk of damage or increased wear occurring.

In a further preferred embodiment of the planetary gear is provided that the decoupling element is substantially incompressible. The decoupling element is preferably made of a metallic material and does not allow any further compression except for an elastic deformation according to the E-modulus of the material. The decoupling element preferably contains no gas spring, no elastomer or other components, which already at low forces have a significant change in volume in order to avoid striking the ring gear on the housing. Elastomers are less suitable because they deform non-linearly under load, have a settling behavior and are subject to noticeable aging. A gas spring is not very suitable because there is a risk of leakage over the long service life of a planetary gear and they no Shear stresses can transmit, making it unsuitable to support the occurring at planetary gears high torques. The aim of the decoupling elements is primarily a vibration isolation of the ring gear and not a damping in the sense of energy dissipation. However, energy dissipation, particularly by stratification of corrugated springs, can positively assist the desired effect of vibration isolation.

Furthermore, it is advantageously provided that a gap is formed between a radial circumferential surface of the ring gear and the housing. By a gap in the radial direction between a radial circumferential surface of the ring gear and the housing, a vibration transmission is prevented via this radial surface area. All transmitted from the ring gear on the housing forces and moments are thus passed through the decoupling elements, resulting in the need for high strength of these decoupling elements. The decoupling elements do not engage around the ring gear and are not substantially cylindrical, but preferably ring, plate or plate-shaped.

In an alternative embodiment of the invention it is provided that the decoupling element between a radial outer surface of the ring gear and the housing is arranged. As an alternative to decoupling elements, which are arranged on the axial end faces of the ring gear, it is conceivable, in particular for small loads and small forces and moments to be transmitted between the ring gear and the housing, that the ring gear has a corresponding decoupling element on its radial lateral surface. In this case, the ring gear is preferably decoupled in the axial direction by corresponding column of the housing, so that all forces and moments are passed through the decoupling element. Due to the axial forces and shear moments occurring, however, such a solution is generally less favorable than a damping over the axial end faces. However, it is particularly suitable when in the axial direction no space is available and / or mobility of the ring gear is to be made possible in particular in the radial direction. In this case, a plurality of uniformly distributed over the circumference of the ring gear decoupling elements are preferably provided which a Allow radial bias of the decoupling between the housing and the radial end face of the ring gear.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

Figure 1 shows a detail of a planetary gear according to the invention, in which a vibration-damping decoupling element is arranged between the ring gear and the housing.

Fig. 2 is an enlarged detail of the radial end portion of the

Ring gear of a planetary gear according to the invention;

Fig. 3 shows a detail of an alternative embodiment of a planetary gear according to the invention.

1 shows a section through an inventive planetary gear. 1 The planetary gear 1 has a housing 5, in which a ring gear 4 is rotatably mounted. The ring gear 4 has at a radially outer end portion on a web 25, which reduces the width B of the ring gear 4 respectively. Thus, in this radially outer end portion of the ring gear 4 each one shown in Fig. 2 paragraph 14 is formed. At the axial end faces 10, 1 1 of the ring gear 4 are on both sides decoupling elements 8, 9 arranged in the region of the web 25, with which the ring gear 4 is held in the housing 5. For this purpose, the decoupling elements 8, 9 are biased by a clamping element 17 in the axial direction. The bias of Decoupling elements 8, 9 can be adjusted via an interference fit of the decoupling elements 8, 9. Alternatively, the bias voltage can be adjusted via a screw 18. In the radial direction, a gap 16 results between a radial circumferential surface 15 of the ring gear 4 and the housing 5, so that no vibrations are transmitted from the ring gear 4 to the housing 5 in this area. The ring gear 4 is connected to a toothing 24 shown in FIG. 2 in engagement with at least one planetary gear 3, which is supported by a planet carrier 19. On the housing 5, a first housing opening 21 is provided to connect the planet carrier 19 with a drive or output shaft. The planetary gear 3 is engaged with a sun gear 2 which is connected to a drive or output shaft 20. The drive or output shaft 20 penetrates the housing 5 through a second housing opening 22, which is opposite to the first housing opening 21. The ring gear 4, the sun gear 2 and the planet carrier 19 are arranged concentrically to a central axis 23 of the planetary gear 1. Alternatively, the housing 5 may also be closed on the second end face and the drive shaft 20 on the same side of the housing as a hollow shaft connected to the planet carrier 19 exit from the housing 5.

2, a radial portion of the ring gear 4 is shown. The ring gear 4 has in the region of the web 25 two opposite recesses 6, in which the decoupling elements 8, 9, which are preferably designed as corrugated springs 12, are positively received. In this case, a further recess 7 is in each case formed on the housing 5 shown in FIG. 1 and on the clamping element 17 in order to receive the respective decoupling element 8, 9 in a form-fitting manner. As a result, a transmission of peripheral forces from the ring gear 4 to the housing 5 without the risk of displacement of the respective decoupling element 8, 9 possible. The decoupling elements 8, 9 are preferably not in the radial direction. The centering of the ring gear 4 is preferably carried out exclusively by tangential positive locking. The ring gear 4 has on its side facing away from the web 25 a toothing 24, in which the planet gears 3 of the planetary gear 1 can engage and on which these planet gears 3 roll. FIG. 3 shows an alternative embodiment of a planetary gear 1 according to the invention. In substantially the same construction as shown in FIG. 1, the ring gear 4 in this embodiment, no web 25 and two paragraphs 14, but at the two axial end faces 10, 1 1 each have a groove 13 in which the respective decoupling element 8, 9 is recorded. In this case, the groove 13 is only so deep that the decoupling element 8, 9 projects beyond the respective axial end face 10, 1 1 of the ring gear 4 even at maximum deformation. At the groove bottom of the grooves 13 additional recesses 6 are formed to receive the decoupling elements 8, 9 positively. Recesses 7 are also provided on the housing 5 and on the tensioning element 17 in order to receive the decoupling element 8, 9 in a form-fitting manner and thus to enable transmission of tangential forces.

During operation of the planetary gear 1 caused by the rolling of the gears 2, 3, 4, in particular by the rolling of the planetary gears 3 on the ring gear 4 oscillations, which lead to a noise of the planetary gear 1. In order to reduce a transmission of the vibrations to the housing 5 and thus to reduce the outwardly urgent noise of the planetary gear 1, these vibrations can be reduced by an elastic deformation of the decoupling elements 8, 9. In this case, the ring gear 4 in the axial direction (and limited in the radial direction) move, which can be compensated by component tolerances and mounting tolerances concentricity errors and concentricity errors, whereby the mechanical component load of the ring gear 4 and the planet gears 3 can also be reduced. LIST OF REFERENCE NUMBERS

1 planetary gear

2 sun wheel

3 planetary gear

4 ring gear

5 housing

6 recess

7 recess

8 first decoupling element

9 second decoupling element

10 first axial end face

1 1 second axial end face

12 wave spring

13 groove

14 paragraph

15 radial lateral surface

16 gap

17 clamping element

18 screw

19 planet carrier

20 output shaft

21 first housing opening

22 second housing opening

23 central axis

24 toothing

25 footbridge

B width of the ring gear

Claims

claims

1 . Planetary gear (1) with a sun gear (2), at least one planetary gear (3) and a ring gear (4), wherein the ring gear (4) rotatably in a housing (5) is arranged, wherein on the ring gear (4) and / or at least one recess (6, 7) is provided on the housing (5), wherein at least one decoupling element (8, 9) is arranged between the ring gear (4) and the housing (5), which in the at least one recess (6 , 7), characterized in that the

Decoupling element (8) is designed as a corrugated spring (12) and on an axial end face (10, 1 1) of the ring gear (4) is arranged.

2. planetary gear (1) according to claim 1, characterized in that the

Decoupling element (8, 9) is biased in the axial and / or radial direction.

3. planetary gear (1) according to claim 1 or 2, characterized in that in each case a decoupling element (8) on both axial end faces (10, 1 1) of the ring gear (4) is arranged, and the ring gear (4) between the two decoupling elements (8) is elastically mounted.

4. planetary gear (1) according to one of claims 1 to 3, characterized

in that a groove (13) or a shoulder (14) which reduces the width (B) of the ring gear (4) is provided on the ring gear (4).

5. planetary gear (1) according to claim 4, characterized in that on the ring gear (4) on both sides in each case a groove (13) or a shoulder (14) is provided, which reduces the width of the ring gear (4).

6. Planetengetnebe (1) according to one of claims 1 to 5, characterized in that the decoupling element (8, 9) is substantially incompressible.

7. planetary gear (1) according to one of claims 1 to 6, characterized

in that a gap (16) is formed in the radial direction between a radial jacket surface (15) of the ring gear (4) and the housing (5).

8. planetary gear (1) according to claim 1, characterized in that the decoupling element (8, 9) between a radial end face (15) of the ring gear (4) and the housing (5) is arranged.