Planetary gear with improved bearing flange

Abstract

The invention relates to a planetary gear comprising a ring gear, at least one gear stage and a bearing flange for mounting an output shaft. The problem addressed by the invention is that of providing a planetary gear which improves the gears known in the prior art and in particular provides a cost-effective and easy-to-produce solution for the installation of the output shaft of the gear. For this purpose, according to the invention, the bearing flange is provided in a multi-part design and has at least a first bearing flange part on the ring gear side and a second bearing flange part on the output side, the first bearing flange part being integrally formed with the ring gear and the second bearing flange part being designed as a separate component, and non-rotatably connected to the first bearing flange portion.

Description

Technical Field

[0001] The present patent application relates to a planetary gear comprising a ring gear, at least one gear stage and a bearing flange for supporting an output shaft.

[0002] The basic task of this planetary gear is to ensure safe load bearing of the output shaft of the gear. Specifically, radial forces acting on the output shaft must also be absorbed. Background Art

[0003] An electric motor with attached planetary gears is known from WO 2021 / 075217 A1. For this purpose, a motor holder is provided, which is screwed to the electric motor. The ring gear of the planetary gear is connected to the motor holder via a plug-in connection. On the side of the ring gear opposite the motor there is an integrally formed bearing holder, which holds the bearing for the output shaft of the planetary gear. The output shaft bearing is completely supported by the bearing holder. There is no contact between the bearing and the ring gear or the motor mount. The bearing holder is also connected to the planetary gearbox via a plug connection. In addition, the motor mount, the hollow gear wheel and the bearing holder are screwed together by means of several screws.

[0004] DE 10 2018 204 051 A1 also shows a geared motor with an electric motor and a planetary gear, which is attached to the electric motor by means of mounting screws. The ring gear of the planetary gear forms part of the gearbox housing. In addition, the planetary gear comprises a bearing plate, which is integral with the ring gear. The output shaft is supported by two sliding bearings, which are mounted in the bearing plate at a certain axial spacing from each other.

[0005] It is known from DE 10 2005 052 008 A1 that a planetary gear has an input shaft, one or two gear stages and a multi-part housing. The housing comprises a housing part for mounting an output shaft. The input shaft comprises a sun gear gear arrangement and is also referred to as a sun gear. The housing part for mounting the output shaft is designed with a first bearing seat for supporting a ring gear side bearing and a second bearing seat for supporting an output side bearing. Thus, the bearings of the two output shafts, i.e. the ring gear side bearing and the output side bearing, are accommodated in the housing part. The outer ring of the ring gear side bearing is arranged adjacent to the ring gear. The housing parts are connected to each other by screws. The screws extend in the gearbox housing between the outer side of the housing and the ring gear teeth. The ring gear teeth are designed as internal teeth on the gearbox housing and engage with the planetary gear.

[0006] US 5,240,462 A describes another planetary gear. The planetary gear comprises an input shaft on which a sun gear is arranged, a ring gear, a plurality of planetary gears meshing with the sun gear and the ring gear, and a housing. The planetary gears are rotatably mounted on the planet shaft. The planet shaft is connected to a carrier, which is integral with the output shaft. The output shaft is rotatably mounted in the housing by means of two bearings. The housing is formed of a plurality of parts and comprises a side plate, a center flange and a housing cylinder. One of the bearings of the output shaft is mounted in the center flange, and the other of the bearings of the output shaft is mounted in the side plate. The center flange is screwed to the housing cylinder by means of screws, and the ring gear is also located in the housing cylinder. The side plate is connected to the center flange by means of screws. The housing cylinder does not contact the two bearings for supporting the output shaft. Summary of the invention

[0007] The object of the present invention is to provide a planetary gear as described above which improves the gears known in the prior art and in particular provides a cost-effective and simple manufacturing solution for the output shaft load of the gear, regardless of the material used in the planetary gear.

[0008] This problem is solved by the features of independent claim 1. Therefore, in a planetary gear comprising a ring gear, at least one gear stage and a bearing flange for mounting an output shaft, a solution to the problem according to the invention is provided if the bearing flange is designed in multiple parts and comprises at least a first ring gear side bearing flange part and a second output side bearing flange part, wherein the first ring gear side bearing flange part is formed integrally with the ring gear, while the second output side bearing flange part is formed as a separate component and is connected to the first ring gear side bearing flange part in a rotationally fixed manner.

[0009] The bearing flange is arranged around the bearing for supporting the output shaft from the outside in the radial direction, or supporting the bearing from the inside. The bearing flange of the present invention is designed in multiple parts. Preferably, each bearing flange part is arranged around the bearing for at least partially mounting the output shaft from the outside in the radial direction, or at least partially supporting the bearing from the inside. The first ring gear side bearing flange part can be designed as an annular disk. The annular disk is adjacent to the ring gear, for example, adjacent to the cylindrical part of the ring gear. The second output side bearing flange part can include the same outer contour as the first ring gear side bearing flange part, and can also be designed as a cylinder. The two-part design of the bearing flange ensures that the two bearings provided for the output shaft bearing can be arranged at a certain axial spacing from each other. This makes it possible to absorb larger radial forces on the output shaft. Due to the two-part or multi-part design of the bearing flange, different materials can be used for the two bearing flange parts. This allows various material combinations for the two bearing flange parts. This makes it particularly cost-saving, wherein the two bearing flanges can be designed more simply according to their different loads and the forces that the two components need to absorb.

[0010] Advantageous embodiments of the invention are subject matter of the dependent claims.

[0011] In a preferred embodiment of the invention, a sintered ring gear can be provided. Due to the fact that the ring gear is made of sintered material, low-cost production can be achieved while maintaining a high level of precision. In order to achieve the required precision, the sintered part can be pressed into a mold under high pressure. This is only possible when the component reaches a certain length, which is why the sintered metal component can only include a limited maximum length. Due to the two-part design of the bearing flange, the ring gear formed integrally with the first ring gear side bearing flange part can be designed to be longer, so that several planetary gears for higher reduction ratios or wider planetary gears for transmitting greater torques can be arranged in the ring gear. The arrangement of the bearings in the two-part bearing flange enables the output shaft to be supported by means of two bearings arranged at a certain or predetermined axial spacing from each other, even in the case where the ring gear is made of sintered material.

[0012] Advantageously, it can also be provided that the first gear ring-side bearing flange part and the second output-side bearing flange part are connected to each other in a rotationally fixed manner by means of a screw connection. The screw connection can be made with almost all materials. In particular, with sintered components, alternative connection methods such as welding, gluing or pressing are disadvantageous and complicated to implement. In addition, the screw connection can be separated and reassembled without leaving any residues.

[0013] In order to prevent the screw connection of the two bearing flange parts from loosening from the outside, at least one through hole can be formed in the first ring gear side bearing flange part, and at least one blind hole can be formed in the second output side bearing flange part, the blind hole cooperating with the through hole to accommodate the screw. In an alternative design, the hole in the second output side bearing flange part can also be designed as a through hole. Therefore, the screw connection will not be guided along the ring gear in the gearbox housing, but will be arranged at the end of the ring gear in the first ring gear side flange part. For the screw connection, the screw is inserted through the through hole in the ring gear side bearing flange part and screwed into the blind hole in the second output side bearing flange part. Therefore, one or more screws are oriented from the inside to the outside, from the ring gear side toward the output side. When assembling the planetary gear, the connection between the two bearing flange parts cannot be loosened from the outside. Nevertheless, optionally, the gearbox can be disassembled and the screw connection can be loosened in a non-destructive manner from the inside of the ring gear. In a simple design of the screw connection, preferably, a blind hole including a thread can also be provided. Alternatively, the blind hole can also be designed to have no thread. In this case, the screws are self-tapping.

[0014] In order to be able to fix the installation of the output shaft in the bearing flange, it can also be arranged that the bearing flange includes a first ring gear side bearing seat and a second output side bearing seat, wherein the first ring gear side bearing seat and the second output side bearing seat are arranged at a certain distance from each other in the axial direction of the output shaft. Due to the spacing of the bearings arranged in the two bearing seats, according to the lever principle, a large radial force can be absorbed by the output shaft.

[0015] In this case, preferably, the first ring gear side bearing seat is formed in both the first ring gear side bearing flange part and the second output side bearing flange part. Preferably, the second output side bearing flange part forms a stop for the bearing arranged in the first bearing seat. This makes it easy to compensate for the manufacturing tolerances of the two bearing flange parts. The bearing can also be pressed into the bearing seat, so that the bearing tolerance can be compensated by pressing into a suitable size. The bearing seat on the bearing of the second output side bearing flange part can have a clearance fit. Therefore, the first ring gear side bearing flange part and the second output side bearing flange part are centered relative to each other, which simplifies the assembly of the two parts when they are combined together. In addition, the processing of the bearing seat can also be facilitated. The existing bearing seat manufacturing tolerances in the first ring gear side bearing flange part and / or on the second output side bearing flange part can be reduced by post-processing such as turning, drilling, milling or grinding.

[0016] Preferably, the second output side bearing seat can be formed in the second output side bearing flange portion. Because the two bearing seats are formed on two different components, namely the two bearing flange portions, the two bearing seats can be well processed.

[0017] In a further advantageous embodiment, a first ring gear side bearing for the output shaft is arranged on a first ring gear side bearing seat and a second output side bearing for the output shaft is arranged on a second output side bearing seat. Preferably, the first bearing and the second bearing are designed to absorb radial forces, in particular via the second output side bearing. This allows the first ring gear side bearing to be smaller than the second output side bearing. This enables the screw connection between the two bearing flange parts to be arranged radially between the first ring gear side bearing and the ring gear diameter. In this way, despite the need for a bearing on the output side and the stronger output shaft due to the torque, the necessary installation space can be found even in small gearboxes with a diameter of less than 100 mm to provide an additional screw connection.

[0018] Preferably, the second output side bearing seat is arranged on the axial end as much as possible, opposite to the first ring gear side bearing flange portion, so as to achieve the farthest possible distance between the first ring gear side bearing seat and the second output side bearing seat, and thus achieve the farthest possible distance between the first ring gear side bearing and the second output side bearing.

[0019] A further advantageous embodiment provides that the first ring gear side bearing comprises a diameter which is smaller than the diameter of the second output side bearing. Thus, the screw connection can be arranged inside the ring gear, so that the installation space in the outer periphery of the hollow space can be reduced, which in turn allows the use of larger ring gears with larger reduction ratios.

[0020] In another embodiment, the planetary gear can be designed as a multi-stage gear, wherein the ring gear covers at least the first two output-side gear stages. A higher reduction ratio can be achieved by means of a multi-stage gear.

[0021] In order to achieve a particularly compact design of the planetary gear, the ring gear can be designed to form part of the transmission housing.

[0022] Preferably, the wall thickness of the gear ring of the gearbox housing is less than 20%, preferably less than 15%, and particularly preferably less than 10% of the outer radius of the gearbox housing. Due to the small wall thickness, the gearing diameter of the gear ring can be as large as possible, which enables a larger gear reduction ratio. A larger gear reduction ratio can also be achieved with additional stages, but this increases the overall length of the gearbox and reduces efficiency.

[0023] Advantageously, at least one through hole in the first gear ring-side bearing flange part is provided with a step or chamfer, wherein the through hole comprises a larger diameter on the gear ring side. This allows the screw head of the screw to be received axially in the through hole in the first gear ring-side bearing flange part and to be approximately flush with the gear ring-side end face of the bearing flange. This avoids the need for additional installation space for the screw head.

[0024] Preferably, the seal is arranged between the first gear ring side bearing flange part and the second output side bearing flange part. Preferably, the seal is designed as an O-ring. The seal tightly seals the first gear ring side bearing flange part and the second output side bearing flange part, which particularly prevents liquid or gas from penetrating between the two parts.

[0025] In a further advantageous embodiment, it can be provided that the second output-side bearing flange portion is made of aluminum. This makes the planetary gear advantageous in terms of cost and weight.

[0026] In order to achieve a fixed connection between the two bearing flange parts, it can be provided that the first gear-ring-side bearing flange part and the second output-side bearing flange part are screwed together by means of at least four screws, preferably by means of eight screws.

[0027] Hereinafter, embodiments of the present invention are described in more detail with reference to the accompanying drawings.

[0028] Figure 11 shows a cross-sectional view of a planetary gear 1 according to the invention. The planetary gear 1 comprises an input shaft 2 and a ring gear 3, in which a first gear stage 4 and a second gear stage 5 are arranged. Both gear stages 4, 5 comprise a central sun gear 6, which engages with at least one planet gear 7. Each planet gear 7 is provided with external teeth, which engage with the internal teeth of the ring gear 3. Furthermore, the planetary gear 1 comprises an output shaft 8. From Figure 1 It can be clearly seen in FIG. 2 that the ring gear 3 forms part of the transmission housing 24 .

[0029] Figure 1 A two-stage planetary gear 1 is shown in FIG. The planetary gear can also be designed as a multi-stage planetary gear. In planetary gears with more than two stages, the ring gear covers at least the first two output-side gear stages. Multi-stage gears can achieve higher gear reduction ratios, although the efficiency of the planetary gear decreases per stage.

[0030] The output shaft 8 is mounted by means of a first ring gear side bearing 9 and a second output side bearing 10. The two bearings 9, 10 are held in a bearing flange 11. The bearing flange 11 is designed in multiple parts, in the illustrated embodiment in two parts, and comprises a first ring gear side bearing flange part 12 and a second output side bearing flange part 13. The first ring gear side bearing flange part 12 is designed as one piece with the ring gear. Therefore, the ring gear 3 and the first bearing flange part 12 are designed as a single-piece component. Figure 1 As shown, the first bearing flange portion 12 extends from the outer peripheral surface of the ring gear 3 in the direction of the center axis M of the planetary gear 1. The bearing flange portion 12 includes a central recess for receiving the output shaft 8 and the first bearing 9. The second bearing flange portion 13 is designed as a separate component. The second output side bearing flange portion 13 is preferably made of aluminum.

[0031] Two bearing seats 14, 15 are formed in the bearing flange 11, namely a first ring gear side bearing seat 14 and a second output side bearing seat 15. The first ring gear side bearing seat 14 is formed by a first bearing flange part 12 and a second bearing flange part 13, which are integral with the ring gear 3. In this case, a first shoulder 16 is formed in the second output side bearing flange part 13, which forms an axial stop for the outer ring of the first ring gear side bearing 9. The second output side bearing seat 15 is formed in the second output side bearing flange part 13. A second shoulder 17 is formed in the second output side bearing flange part 13, which forms an axial stop for the outer ring of the second output side bearing 10. The two bearings 9, 10 are arranged at a certain axial distance from each other. This makes it possible to absorb greater radial forces on the output shaft 8.

[0032] Preferably, the gear ring 3 and the first bearing flange part 12 which is integral therewith are made of a sintered material. Therefore, the gear ring 3 and the first bearing flange part 12 are sintered, i.e. produced in a sintering process. The sintered metal part can only include a limited maximum length. Since the bearing flange 11 is designed as a plurality of parts, in the illustrated embodiment as two parts, i.e. the first gear ring side bearing flange part 12 and the second output side bearing flange part 13, the first gear ring side bearing flange part 12 is designed integrally with the gear ring 3, and the second output side bearing flange part 13 is designed as a separate part, a sintered gear ring can be used and still ensure that the axial spacing between the two bearing seats 14, 15 formed in the bearing flange 11 meets the requirements.

[0033] In the example shown, the two bearings 9, 10 are designed such that radial forces are absorbed in particular by the second output-side bearing 10. This means that the first gear-side bearing 9 can be made smaller and comprise a smaller outer diameter than the second output-side bearing 10.

[0034] The second output side bearing flange part 13 is connected to the first ring gear side bearing flange part 12 in a rotatably fixed manner. In the example shown, this connection in a rotatably fixed connection is achieved by means of a screw connection. For this purpose, the first ring gear side bearing flange part 12 includes at least one through hole 18. At least one blind hole 19 is formed in the second output side bearing flange part 13, which cooperates with the through hole 18 in the first bearing flange part 12 to receive a screw 20. The advantage of the screw connection is that the screw connection can be separated and reassembled without leaving any residue. In addition, almost all materials can be connected with screws. Alternative connection methods such as welding, gluing or pressing are disadvantageous and costly, especially with sintered parts.

[0035] Preferably, the screw connection is formed by means of at least four and preferably eight screws. Therefore, the first bearing flange part 12 comprises at least four, preferably eight through holes, and the second bearing flange part 12 comprises at least four, preferably eight blind holes, each of which interacts with one of the through holes in the first bearing flange part 12 to receive a screw. Therefore, the screw 20 is oriented from the inside to the outside, i.e. from the ring gear side towards the output side. Therefore, the screw connection is not visible or accessible from the outside. This means that when assembling the planetary gear 1, the screw connection cannot be loosened from the outside. However, optionally, the planetary gear 1 can be disassembled and the screw connection loosened non-destructively from the inside of the ring gear.

[0036] As mentioned above, the first ring gear side bearing 9 comprises a smaller diameter than the second output side bearing 10 on the output side. This allows the screw connection to be arranged radially between the first bearing 9 and the ring gear diameter. This eliminates the need for screw connections on the outside of the ring gear 3 and screws extending axially in the gearbox housing 24. As a result, the installation space required for the outer periphery of the ring gear 3 is reduced, which can allow the installation of larger ring gears with larger gear reduction ratios. Figure 1 In the embodiment shown, the wall thickness of the gearbox housing 24 is less than 15%. The wall thickness depends mainly on the size of the gearbox housing, the torque to be transmitted and the material used for the housing.

[0037] In the example shown, the through hole 18 in the first gear ring-side bearing flange part 12 is designed with an enlarged diameter. On the output side, the through hole has a smaller diameter. This forms a shoulder in the through hole 18. This allows the screw head 21 to be accommodated axially in the through hole 18. The screw head 21 of the screw 20 is thus approximately flush with the gear ring-side end face 22 of the bearing flange 11 and rests against the shoulder in the through hole 18. This avoids the need for additional installation space for the screw head 21.

[0038] Preferably, at least one blind hole 19 or each blind hole 19 has a thread. Alternatively, (one or more) blind holes 19 can also be designed without a thread. In this case, (one or more) screws 20 are self-tapping.

[0039] Preferably, a seal 23 is arranged in the interface of the two-part bearing flange 11, namely between the first bearing flange part 12 and the second bearing flange part 13. In the embodiment shown, the seal 23 is designed as an O-ring.

[0040] Reference numerals list

[0041] 1Planetary gear

[0042] 2 Input shaft

[0043] 3 gear ring

[0044] 4First gear stage

[0045] 5 Second gear stage

[0046] 6 Sun gear

[0047] 7Planetary gear

[0048] 8 Output shaft

[0049] 9First gear ring side bearing

[0050] 10 Second output side bearing

[0051] 11 Bearing flange

[0052] 12First gear ring side bearing flange

[0053] 13 Second output side bearing flange portion

[0054] 14 First gear ring side bearing seat

[0055] 15 Second output side bearing seat

[0056] 16 First Shoulder

[0057] 17 Second Shoulder

[0058] 18 through holes

[0059] 19 blind holes

[0060] 20 screws

[0061] 21 Screw head

[0062] 22 End face of gear ring of bearing flange

[0063] 23 Seals

[0064] 24 gearbox housing

[0065] M Center axis of planetary gear

Claims

1. A planetary gear (1), comprising a ring gear (3), at least one gear stage (4, 5) and a bearing flange (11) for mounting an output shaft (8), characterized in that: The bearing flange (11) is designed as a plurality of parts and includes at least a first ring gear side bearing flange part (12) and a second output side bearing flange part (13), wherein the first ring gear side bearing flange part (12) is formed integrally with the ring gear (3), and the second output side bearing flange part (13) is formed as a separate component and is connected to the first ring gear side bearing flange part (12) in a rotatably fixed manner.

2. The planetary gear according to claim 1, characterized in that: The gear ring (3) is sintered.

3. The planetary gear (1) according to claim 1 or 2, characterized in that: The first ring gear side bearing flange portion (12) and the second output side bearing flange portion (13) are connected to each other in a rotationally fixed manner by means of a screw connection.

4. Planetary gear (1) according to at least one of the preceding claims, characterized in that At least one through hole (18) is formed in the first gear ring side bearing flange portion (12), and at least one blind hole (19) is formed in the second output side bearing flange portion (13), the at least one blind hole (19) cooperating with the through hole (18) to receive a screw (20).

5. Planetary gear (1) according to at least one of the preceding claims, characterized in that The bearing flange (11) has a first ring gear side bearing seat (14) and a second output side bearing seat (15), wherein the first ring gear side bearing seat (14) and the second output side bearing seat (15) are arranged at a certain distance from each other along the axial direction of the output shaft (8).

6. The planetary gear (1) according to claim 5, characterized in that The first ring gear side bearing seat (14) is formed in the first ring gear side bearing flange portion (12) and in the second output side bearing flange portion (13).

7. Planetary gear (1) according to one of claims 5 or 6, characterized in that The second output side bearing seat (15) is formed in the second output side bearing flange portion (13).

8. Planetary gear (1) according to one of claims 5 to 7, characterized in that A first ring gear side bearing (9) for the output shaft (8) is arranged on the first ring gear side bearing seat (14), and a second output side bearing (10) for the output shaft (8) is arranged on the second output side bearing seat (15).

9. The planetary gear (1) according to claim 8, characterized in that The first ring gear side bearing (9) has a diameter that is smaller than the diameter of the second output side bearing (10).

10. Planetary gear (1) according to at least one of the preceding claims, characterized in that The planetary gear (1) is designed to have multiple stages, and the ring gear (3) covers at least the first two output-side gear stages (4, 5).

11. Planetary gear (1) according to at least one of the preceding claims, characterized in that The ring gear (3) forms part of a gearbox housing (24).

12. Planetary gear (1) according to at least one of the preceding claims, characterized in that The wall thickness of the gear ring (3) is less than 20%, preferably less than 15%, and particularly preferably less than 10% of the outer radius of the transmission housing (24).

13. Planetary gear (1) according to one of claims 4 to 12, characterized in that At least one through hole (18) in the first gear ring side bearing flange portion (12) is provided with a step or a chamfer, wherein the through hole (18) has a larger diameter on the gear ring side.

14. Planetary gear (1) according to at least one of the preceding claims, characterized in that A seal (23) is arranged between the first ring gear side bearing flange portion (12) and the second output side bearing flange portion (13).

15. Planetary gear (1) according to at least one of the preceding claims, characterized in that The second output side bearing flange portion (13) is made of aluminum.

16. Planetary gear (1) according to at least one of the preceding claims, characterized in that The first gear ring side bearing flange part (12) and the second output side bearing flange part (13) are screwed together by means of at least four screws (20), preferably by means of eight screws (20).

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