Planetary gear set with a ring gear and a bearing element connected to this ring gear; and gear system

Abstract

Planetary gear (1) for a motor vehicle, comprising a ring gear (2), at least one planet gear (4) meshing with the ring gear (2) and a sun gear (3), a housing (5) receiving the ring gear (2), and a bearing element (6) designed for the elastic mounting of the ring gear (2), wherein the bearing element (6) has a first support area (7) connected to the ring gear (2) and a second support area (8) received in the housing (5) and spaced apart from the first support area (7), wherein the bearing element (6) has a resiliently designed bridging area (9) that connects the first support area (7) to the second support area (8) which is rotationally fixed to the housing (5), characterized in that the bridging area (9) has at least one geometric weakening point (15) with a multilayered structure (17) forming at least section by section the bridging area (9), wherein the multilayered structure (17) is formed by - a first extension section (20) connected to the first support area (7) and - a second extension section (21) connected to the second support area (8) is trained wherein at least one spring element is used in the circumferential direction and / or in the axial direction between the two extension sections (20, 21).

Description

[0001] The invention relates to a planetary gear for a motor vehicle, preferably a drive train of a motor vehicle, such as a car, bus, truck or other commercial vehicle, with a ring gear, at least one planet gear meshing with the ring gear and a sun gear, a housing receiving the ring gear and a bearing element designed for elastic mounting of the ring gear, wherein the bearing element has a first support area connected to the ring gear and a second support area received in the housing and spaced apart from the first support area.

[0002] Adjacent prior art is known, for example, from DE 102 30 861 A1. This discloses a motor vehicle transmission, in particular an automatic transmission, in a planetary design with a ring gear as the output element. A device for damping structure-borne noise flowing from the ring gear to an output shaft is also provided. Thus, a rotatable bearing for ring gears to realize one degree of rotational freedom of the ring gear is already known from the prior art.

[0003] DE 10 2011 076 521 A1 describes a fastening arrangement for a ring gear which connects a bearing plate to a ring gear carrier via a connecting section.

[0004] DE 10 2010 003 431 A1 describes a starting device with a ring gear and intermediate bearing damping.

[0005] US Patent 4 096 769 A describes a planetary gear in which a weak point has a multi-layered structure.

[0006] One disadvantage of the current state of the art is its rather complex design, as the rotatable bearing of the ring gear must be ensured. The bearing element is designed as a rotating component and is therefore relatively expensive to manufacture, since tight tolerances must be maintained.

[0007] It is therefore the object of the present invention to provide a vibration-damped planetary gear unit that is easier to manufacture and assemble.

[0008] This is achieved according to the invention by the bearing element having a resiliently designed (i.e., acting as a spring / elastically deformable) bridging area, wherein the bridging area connects the first support area (directly / immediately) with the second support area, which is rotationally fixed / secured to the housing. The bearing element also functions as a damping component.

[0009] Thus, the bearing element is implemented as a spacer element that firmly supports / holds the ring gear at a specific distance relative to the housing, preventing direct contact between the ring gear and the housing, for example, at the ring gear's circumference. In other words, the ring gear is rotationally fixed to the housing by means of the bearing element. This provides particularly effective vibration isolation / shielding of the vibrations introduced at the ring gear from the housing. The bearing element serves to dampen vibrations in the axial, radial, and circumferential directions of the planetary gear set.

[0010] Further advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0011] The bearing element is preferably designed in a bowl-shaped / pot-shaped / plate-shaped form.

[0012] The rotationally fixed connection of the second support area in the housing is advantageously achieved by means of a force-fit connection, preferably a screw connection or a rivet connection, and more preferably an interference fit connection. In further preferred embodiments, this connection of the second support area in the housing is achieved alternatively (or more preferably additionally) to the force-fit connection by means of a positive-locking connection and / or a material-locking connection, preferably a welded connection.

[0013] If the bridging area exhibits higher elasticity (i.e., higher elastic deformability in the axial direction, in the radial direction and / or in the circumferential direction with respect to an axis of rotation of the planetary gear) and / or damping than the first support area and / or the second support area, the elastic compliance of the bearing element is specifically implemented mainly in the bridging area, so that only a relatively small deformation of the support areas takes place.

[0014] The bearing element is preferably designed separately from the ring gear or as a single piece of material / as a single piece with the ring gear.

[0015] The difference in elasticity between the support areas and the bridging area is easily achieved if the first support area and / or the second support area are reinforced relative to the bridging area. Such reinforcement preferably refers to material thickening, and more preferably to increased strength, for example, by means of additional reinforcing elements (e.g., fasteners) or treatment steps (e.g., hardening). Conversely, this weakens the bridging area relative to the support areas, creating a (first) weakening point.

[0016] If the first support area is attached to a radial outer side of the ring gear, a particularly strong connection between the bearing element and the ring gear is achieved.

[0017] In this respect, it is particularly advantageous if the first support area forms or has an axially extending sleeve section, which sleeve section is pushed / placed onto the ring gear in a radial direction from the outside / on a radial outer side of the ring gear. The connection between the first support area and the ring gear is preferably achieved via a friction-fit connection, such as an interference fit, a screw connection and / or a rivet connection, or more preferably via a positive-locking connection, such as a toothed connection, or a material-locking connection, such as a weld connection.

[0018] Alternatively or additionally to attaching the first support area to the radial outer side, it is also advantageous, according to further explanations, if the first support area is attached to an (axial) end face of the ring gear. This either further reinforces the connection of the bearing element to the ring gear or makes it particularly compact.

[0019] If the first support area is attached to the end face of the ring gear, it is further advantageous if the first support area is designed as a disc section / flange section or has such a disc section / flange section, and this disc section is attached to the end face of the ring gear. With this attachment, it is particularly advantageous if the first support area is attached to the ring gear by means of a friction-fit connection. A bolted or riveted connection is a preferred friction-fit connection. More preferably, the first support area is positively connected to the ring gear, or, even more preferably, materially connected, for example, by welding.

[0020] To adjust the elasticity of the bridging area to a desired level, it is further advantageous if at least one geometric and / or material weakening point is deliberately introduced into the bridging area.

[0021] In this context, it is advantageous if a (second) weakening point has an opening / window, preferably a through-hole, introduced into the bridging area. This makes the weakening point easy to create.

[0022] If several circumferentially distributed openings are provided to create the second weakening point, a spring effect that is as uniform as possible along the entire circumference is achieved. The openings are preferably shaped and arranged relative to each other such that a rib / spoke / rod is formed between each pair of adjacent openings in the circumferential direction.

[0023] A third weakening point advantageously features a wave structure that forms at least a portion of the bridging area. The wave structure is preferably formed by means of one or more beads. This creates a bellows-like structure that allows for relatively high compliance in the smallest possible installation space.

[0024] A fourth weakening point according to the invention has a multi-layered (preferably two-layered) structure / sandwich structure that forms the bridging area at least partially. This also makes it easy to adjust the elasticity to the desired level.

[0025] With regard to this multi-layered structure in the form of the fourth weakening point, according to the invention a first extension section (preferably integral with the material) is connected / formed with the first support area and a second extension section is connected / formed with the second support area (preferably integral with the material). It is advantageous if these are flexibly / relatively displaceably connected.

[0026] The connection between the two extension sections is advantageously designed such that the extension sections can be displaced relative to each other in the circumferential and / or radial and / or axial direction. The extension sections preferably rest against each other by frictional engagement.

[0027] The connection of the two extension sections to each other is preferably achieved via a force-fit connection, such as riveting and / or screwing, or more preferably alternatively (or additionally) to the force-fit connection via a form-fit connection and / or via a material-fit connection, such as bonding.

[0028] According to the invention, at least one spring element is inserted between the two extension sections in the circumferential and / or axial direction, connecting the extension sections in the circumferential and / or axial direction. Preferably, a spring element acting at least in the axial direction is implemented as an elastic plastic layer, for example, a rubber layer.

[0029] If the two support areas are kept spaced apart from each other in a radial direction and / or an axial direction of the ring gear by the bridging area, a particularly stable support of the ring gear relative to the housing is achieved.

[0030] The ring gear is advantageously made of an iron alloy, such as steel, and the housing is made / molded from an aluminum alloy.

[0031] In other words, according to the invention, a ring gear cup (bearing element / damping component) is implemented in a planetary gear unit. To prevent vibrations on the one hand, and loosening of a seat on the other, possibly due to differences in the coefficients of thermal expansion of the materials used (e.g., steel for the ring gear and aluminum alloy for the housing), the bearing element (damping component) is, according to the invention, inserted between the ring gear and the housing. The ring gear is thus connected to the housing by means of an elastic cup. The connection to the housing is radially directed towards the transmission shaft. The elastic cup is spoke-shaped or of another form.

[0032] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are also shown.

[0033] They show: Fig. 1 a longitudinal sectional view of a planetary gear according to a first embodiment according to the invention, wherein the basic structure of the planetary gear and the connection of a ring gear to a housing by means of a bearing element are particularly clearly visible, Fig. 2 a simplified longitudinal section view of a planetary gear according to a second embodiment according to the invention, wherein an opening provided in a bridging area of ​​the bearing element can be seen, Fig. 3 a simplified longitudinal section view of a planetary gear according to a third embodiment according to the invention, wherein the bridging area has a wave structure, Fig. 4 a simplified longitudinal section view of a planetary gear according to the invention in a fourth embodiment in which the bridging area has a multi-layered structure. Fig. 5 a perspective view of the planetary gear according to Fig. 2 without housing, with the bearing element shown in section, Fig. 6 a perspective view of the planetary gear according to the Fig. 2 and Fig. 5 inserted longitudinally cut bearing elements, Fig. 7 a perspective view of the planetary gear according to Fig. 3 inserted longitudinally cut bearing elements, and Fig. 8 a perspective view of the planetary gear according to Fig. 4 inserted longitudinally cut bearing elements.

[0034] The figures are purely schematic and serve solely to illustrate the invention. The same elements are identified by the same reference numerals. Furthermore, the different features of the various embodiments can be freely combined.

[0035] The planetary gear 1 according to the invention is, in its basic design, in the embodiment of the Fig. 1. The planetary gear 1 is, in operation, part of a motor vehicle's drivetrain (not shown in detail here for clarity) and thus serves to convert torque to be transmitted in the drivetrain. Preferably, the planetary gear 1 is used in an electric axle drive (not shown in detail here for clarity).

[0036] The planetary gear 1 shows after Fig. 1 a central (i.e., rotatable about a central axis of rotation 24) sun gear 3. The sun gear 3 meshes with several planet gears 4 arranged circumferentially. The planet gears 4 of the planetary gear 1 are in turn rotatably mounted / supported on a planet carrier 25 of the planetary gear 1. One of the planet gears 4 is in Fig. Figure 1 shows a longitudinal section, revealing its mounting on the planet carrier 25 by means of rolling bearings 26. The planet carrier 25 has a drive gear 27, which is arranged offset from the planet gears 4 in an axial direction of the planetary gear set 1 (i.e., along the axis of rotation 24). The planet gears 4 are also in mesh with a ring gear 2 that surrounds them radially from the outside. The meshing teeth of the ring gear 2 and the planet gears 4 are each designed as helical teeth.

[0037] To dampen the vibrations introduced / present by the ring gear 2 during operation, particularly in the form of acoustic vibrations, a bearing element 6 is attached to the ring gear 2 according to the invention. This bearing element 6 serves as a vibration-isolating coupling between the ring gear 2 and the housing 5. The bearing element 6 connects the ring gear 2 to the housing 5 in a rotationally fixed manner.

[0038] The bearing element 6 has two support areas 7, 8, which are spaced apart from each other both axially and radially in the direction of the planetary gear 1. A first support area 7 is fixed to the ring gear 2 in a rotationally fixed and axially fixed manner. A second support area 8 is fixed to the housing 5 in a rotationally fixed and axially fixed manner. The two support areas 7, 8 are connected to each other by means of a bridging section 9, which is designed to be resilient. The bearing element 6 is formed from sheet metal. The bearing element 6 is essentially dished.

[0039] In the first embodiment, the first support area 7 is designed as a sleeve section 18. The first support area 7 thus forms an axially extending region. The first support area 7 is attached to / mounted on the ring gear 2 on a radial outer surface 10. In this embodiment, a positive-locking connection serves to prevent rotation between the ring gear 2 and the bearing element 6. This positive-locking connection is realized by means of a toothed connection, namely a splined connection 29. The axial securing of the first support area 7 relative to the ring gear 2 is achieved here by a retaining ring 30, which fixes the bearing element 6 axially relative to the ring gear 2. The first support area 7 is therefore arranged radially outside the planet gears 4.

[0040] Radially within the first support area 7, the second support area 8 is arranged. The second support area 8 is specifically located at a radial height of the planet gears 4, i.e., within a region of the radial extent of the planet gears 4. The second support area 8 is essentially annular in shape. In this embodiment, the second support area 8 is rotationally fixed and axially fixed to the housing 5 by means of a screw connection. Radially, the second support area 8 is also supported / centered by a cup-shaped area 34 of the housing 5. For this purpose, screws 31 are provided at several circumferentially distributed areas, which fasten the second support area 8 to the housing 5. The second support area 8 has several circumferentially distributed internal thread areas 32.The respective screw 31 is firmly anchored to the housing 5 on one side and screwed into an associated internal thread area 32 on the other.

[0041] The bearing element 6 is thus attached in a rotationally fixed / rotationally secured manner to both the ring gear 2 and the housing 5. Therefore, the bearing element 6 serves to attach the ring gear 2 to the housing 5 in a rotationally fixed / rotationally secure manner.

[0042] Regarding the attachment of the second support area 8 to the housing 5, it should be noted that in further embodiments it is also attached to the housing 5 in a different manner. According to further preferred embodiments, the second support area 8 is attached to the housing 5 by a different friction-fit connection, namely a rivet or an interference fit. A material-fit connection in the form of a weld is also implemented in a further preferred embodiment. A positive-fit connection is also implemented according to a further preferred embodiment.

[0043] Furthermore, it should be noted that even if the bearing element 6 is formed separately from the ring gear 2 in this embodiment, in another embodiment it is also formed integrally with the ring gear 2. In this context, the first support area 7 is integrated into the ring gear 2 / integrally connected to it, and the bridging area 9 extends from an internal toothing 33 formed on a radial inner surface 36 of the ring gear 2 both axially and radially (towards the second support area 8).

[0044] According to the invention, the bridging area 9 has a deliberately higher elasticity (i.e., a greater elasticity in shape / flexural elasticity) than the two support areas 7 and 8. In the first embodiment, the bridging area 9 is therefore deliberately weakened compared to the support areas 7 and 8. Conversely, the first support area 7 and the second support area 8 are reinforced relative to the bridging area 9. This reinforcement is achieved in particular by thickening the material (increased sheet thickness). The second support area 8 has a greater material thickness / sheet thickness than the bridging area 9. The first support area 7 also has a greater material thickness / sheet thickness than a section of the bridging area 9 facing the first support area 7. In addition, the first support area 7 is hardened in the area of ​​its splined connection 29, which provides further reinforcement.By selectively weakening the bridging area 9 geometrically and materially, a (first) weakening point 12 is introduced into the bridging area 9, increasing the elasticity of the bridging area 9 compared to the support areas 7 and 8.

[0045] Furthermore, it should be noted that the first support area 7 can be connected to the ring gear 2 in ways other than a positive-locking connection. In other embodiments, a force-fit connection is achieved via a press fit, a bolted connection, and / or riveting. In other embodiments, a material-bonded connection in the form of a weld is achieved between the first support area 7 and the ring gear 2.

[0046] In connection with the Fig. Figures 2 to 8 illustrate further preferred embodiments in a simplified representation, each of which is constructed and functions according to the first embodiment, therefore for the sake of brevity only the differences between these embodiments are described below.

[0047] In Fig. 2 is the first support area 7 attached to the outside 10. A perspective view of the planetary gear 1 according to Fig. 2 is in Fig. Figure 5 illustrates the basic structure of the planetary gear 1 without housing 5 and with a partially cut bearing element 6. The second support area 8 is connected to the housing 5 by means of a material-bonded connection in the form of a weld. The bridging area 9 runs as already shown in Fig. 1, essentially funnel-shaped and has a reduced material thickness compared to the first support area 7 and the second support area 8.

[0048] Additionally, the bridging area 9 has a (second) weakening point 13. For this purpose, several openings 28 in the form of through holes, penetrating axially through the bridging area 9, are provided. This is also evident from the illustration of the bearing element 6 alone. Fig. 6 is clearly visible. The respective opening 28 is specifically designed to increase the elasticity of the bridging area 9 relative to the support areas 7, 8. Several (here seven) openings 28 are arranged circumferentially in this embodiment. A spoke 35 is formed between each pair of adjacent openings 28. The spoke 35 extends radially outwards and thus serves as a connecting element between the two support areas 7 and 8. The spokes 35 preferably do not extend exclusively in the radial direction, i.e., straight in the radial direction, but obliquely in the radial direction, i.e., both radially and circumferentially. As an alternative to the openings 28, other recesses, such as depressions, bulges, or notches, are also implemented in further embodiments.

[0049] In Fig. Figure 3 illustrates a third embodiment of a planetary gear 1 according to the invention. In contrast to the first embodiment, the first support area 7 is no longer attached to the radial outer surface 10, but to an (axial) end face 11 of the ring gear 2. The first support area 7 is implemented as a disc section 19, which extends substantially in the radial direction. Viewed axially, the disc section 19 lies flat against the end face 11. The attachment of the first support area 7 to the end face 11 is achieved by means of a material-bonded connection, namely a weld. Alternatively or additionally, in further embodiments, a friction-fit connection, preferably by screws and / or rivets, is implemented.

[0050] The planetary gear 1 according to Fig. The bearing element 6 used in 3 is also in its shape in Fig. Figure 7 illustrates this. The bridging area 9 additionally features a (third) weakening point 14, which is implemented in the form of a wave structure 16. The bridging area 9 is thus designed with a wave-like structure. The wave structure 16, as implemented here by means of several radially offset and circumferentially extending beads 37, forms a structure that can be compressed / springed in both the radial and axial directions. The second weakening point 13 can also be used as an alternative or in addition to the first and third weakening points 12, 14.

[0051] As already in the second embodiment according to Fig. 2 implemented, also takes place in Fig. 3 the material thickness of the bridging area 9 increases continuously along its extension in the radial and axial direction from the first support area 7 to the second support area 8.

[0052] In Fig. Figure 4 illustrates a fourth embodiment of the planetary gear 1 according to the invention. In this embodiment, a further (fourth) weakening point 15 is realized by a multi-layered structure 17. The multi-layered structure 17 is formed by two overlapping extension sections 20 and 21 (each extension section 20 and 21 representing a layer). This design of the bearing element 6 is also used in conjunction with Fig. 8 clearly. A first extension section 20 is connected to the first support area 7, namely, it is formed as a single piece with the first support area 7. A second extension section 21, which rests flat on the first extension section 20 and is thus essentially parallel to the first extension section 20, is connected to the second support area 8, namely, it is formed as a single piece with the second support area 8.

[0053] The two extension sections 20 and 21 are connected to each other by means of fasteners 22. The two extension sections 20 and 21 are pressed together over their surfaces by the fasteners 22 and are thus connected by frictional force. The fasteners 22 are designed as rivets and positioned at a fastening point 23. In a further preferred embodiment, a rubber layer between the opposing contact surfaces of the extension sections 20 and 21 is also conceivable.

[0054] In this context, it should also be noted that the two extension sections 20 and 21 for the formation of the fourth weakening point 15 can be combined in any other way. It is also in Fig.4. Furthermore, the second weakening point 13 is preferably implemented. Then, viewed circumferentially, the several openings 28 are again provided, and the extension sections 20 and 21 each have a spoke-like appearance.

[0055] In other words, according to the invention, an adaptably elastic spring element (bearing element 6) is provided between the ring gear 2 and the housing 5. This bearing element simultaneously centers the ring gear 2 and supports the torque as well as any axial forces arising from helical gearing. According to the invention, the ring gear 2 is held in the housing 5 by an elastic, essentially dish-shaped ring gear carrier (bearing element 6), which is supported at a certain distance, but certainly not directly on the circumference of the ring gear 2, within the housing 5. The ring gear carrier 6 transmits the torque and axial forces and pre-centers the ring gear 2 relative to the rest of the planetary gear set 1. It is designed to be as elastic as possible so that, on the one hand, the transmission of high-frequency force and torque fluctuations to the housing 5 is reduced, and on the other hand, the centering is essentially "floating," i.e., determined by the planet gears 4.The elasticity of the ring gear carrier 6 is achieved primarily by the shape of the bearing element 6. This element can be thin-walled, may contain cutouts (openings 28) and grooves 37 (wave structure 16), and may be multi-layered (multi-layered structure 17). The ring gear carrier 6 can be connected to the ring gear 2 or to the gearbox housing 5 using any method known in the art (positive locking axially or radially with a retaining ring 30, screws, rivets, welding). The planetary gear 1 is preferably used in electric axle drives. Reference symbol list 1 planetary gear 2. Ring gear 3 Sun wheel 4 planetary gear 5 cases 6 Bearing element / damping component 7 first support area 8 second support area 9 Bridging area 10 Outside 11 Front 12 first weak point 13 second weak point 14 third weak point 15 fourth weak point 16 wave structure 17 multi-layered structure 18 Sleeve section 19 disc section 20 first extension section 21 second extension section 22 Fasteners 23 Mounting point 24 Rotary axis 25 planetary carriers 26 rolling bearings 27 drive wheel 28 Opening 29 Splined connection 30 retaining ring 31 screw 32 Internal thread area 33 Internal teeth 34 bowl area 35 spokes 36 Inside 37 groove

Claims

[1] Planetary gear (1) for a motor vehicle, comprising a ring gear (2), at least one planet gear (4) meshing with the ring gear (2) and a sun gear (3), a housing (5) receiving the ring gear (2) and a bearing element (6) designed for elastic mounting of the ring gear (2), wherein the bearing element (6) has a first support area (7) connected to the ring gear (2) and a second support area (8) received in the housing (5) and spaced apart from the first support area (7), wherein the bearing element (6) has a resiliently designed bridging area (9) connecting the first support area (7) to the second support area (8) which is rotationally fixed to the housing (5), characterized by , that the bridging area (9) has at least one geometric weakening point (15) with a multilayered structure (17) forming at least section by section the bridging area (9), wherein the multilayered structure (17) is formed by - a first extension section (20) connected to the first support area (7) and - a second extension section (21) connected to the second support area (8) is trained wherein at least one spring element is used in the circumferential direction and / or in the axial direction between the two extension sections (20, 21). [2] Planetary gear (1) according to claim 1, characterized by that the bridging area (9) has a higher elasticity and / or damping than the first support area (7) and / or the second support area (8). [3] Planetary gear (1) according to claim 1 or 2, characterized by , that the bearing element (6) is formed separately from the ring gear (2) or as a single piece with the ring gear. [4] Planetary gear (1) according to any one of claims 1 to 3, characterized bythat the first support area (7) and / or the second support area (8) are reinforced relative to the bridging area (9). [5] Planetary gear (1) according to any one of claims 1 to 4, characterized by , that the first support area (7) is attached to a radial outer side (10) of the ring gear (2) and / or to an end face (11) of the ring gear (2). [6] Planetary gear (1) according to any one of claims 1 to 5, characterized by , that at least one material weakening point (12, 13, 14, 15) is introduced into the bridging area (9). [7] Planetary gear (1) according to claim 6, characterized by , that a weakening point (13) has an opening (28) introduced into the bridging area (9). [8] Planetary gear (1) according to claim 6 or 7, characterized by , that a weakening point (14) has a wave structure (16) that forms at least section by section the bridging area (9). [9] Planetary gear (1) according to any one of claims 1 to 8, characterized by , that the two support areas (7, 8) are held apart from each other in a radial direction and / or an axial direction of the ring gear (2) by the bridging area (9).

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