Planetary transmission with planetary gears axially mounted on sliding bearings

Abstract

The invention relates to a planetary transmission (10) for a wind turbine (70) driven by a rotor (72), comprising at least one planetary stage (14) rotating about an axis of rotation (AD), wherein the planetary stage (14) has a sun gear (22), a planet carrier (16) and a ring gear (20) and the planet carrier (16) receives a plurality of planet gears (18) which rotate between side pieces (24, 26) of the planet carrier (16), are radially mounted on sliding bearings and are alternately in toothed engagement with the ring gear (20) and the sun gear (22), and wherein at least one axial sliding element (30) is inserted into each side piece (24, 26) and a collar portion (32) of each axial sliding element (30) projects in the axial direction beyond the side piece (24, 26) and on the end face carries a sliding surface (34) for axially supporting the planet gear (18). The collar portion (32) bears directly against the respective side piece (24, 26) at the rear.

Description

[0001] FLENDER GMBH Düsseldorf, September 5, 2025

[0002] Our reference number: FD 45689 - 2024P04723WO

[0003] Flender GmbH

[0004] Alfred-Flender-Str. 77, 46395 Bocholt, Germany

[0005] Planetary gear with axially sliding bearing planetary gears

[0006] Description

[0007] The invention relates to a planetary gear for a wind turbine driven by a rotor, with a planetary stage rotating about an axis of rotation AD, wherein the at least one planetary stage has a sun gear, a planet carrier and a ring gear and the planet carrier accommodates several planet gears rotating between side plates of the planet carrier and radially sliding mounted and alternatingly in tooth engagement with the ring gear and the sun gear and wherein at least one axial sliding element is inserted into each side plate and a collar section of each axial sliding element projects axially beyond the side plate and carries a sliding surface on the voice side for the axial mounting of the planet gear.

[0008] Gearboxes, particularly planetary gearboxes, for wind turbines can be designed with plain bearings. In planetary gearboxes, this typically refers to the radial mounting of the planet gears on the corresponding planet carrier. Both during assembly and operation of the planetary gearbox, axial forces occur, and the planet gears can shift axially to a certain extent. Since such a plain bearing of the planet gears cannot absorb axial forces, axial support of the planet gears relative to the side plates of the planet carrier, between which the planet gears are mounted, is always necessary. The axial guidance or support of the planet gears relative to the side plates is usually achieved via thrust washers, which are typically made of bronze.The side plates are provided with a sliding surface by these thrust washers, on which the corresponding mating surface of the planet gear can slide and over which the resulting axial forces can be supported. Although the thrust washers are loosely inserted into the planet carrier, they must nevertheless be secured against rotation relative to the planet carrier, for example by a circumferential wrench flat. Such an axial bearing arrangement for the planet gears is described in EP 2 383 480 Al and DE 10 2016 219 008 Al. Another possibility is shown in EP 3 612 743 Bl, in which tilting elements are provided that are inserted into the side plates from the inside and supported against the side plates by spring elements. EP 4 328 440 Al should also be mentioned.

[0009] A disadvantage of this solution, equipping the planetary carrier's side plates with anti-rotation thrust washers, is the high manufacturing complexity, resulting in high machining costs for the planetary carrier. The tilting elements integrated into the side plates also appear disadvantageous from an assembly perspective. There is a constant need to find a simpler design and manufacturing solution that can absorb the axial forces that occur.

[0010] The object of the invention is to demonstrate measures that enable the absorption of the occurring axial forces through a structurally and technically simpler solution.

[0011] The problem is solved by a planetary gear unit having the features of claim 1. Preferred embodiments are specified in the dependent claims and the following description, each of which, individually or in combination, can represent an aspect of the invention. When a feature is presented in combination with another feature, this serves only to simplify the presentation of the invention and is in no way intended to imply that this feature cannot also be a further development of the invention without the other feature.One embodiment relates to a planetary gear for a wind turbine driven by a rotor, with at least one planetary stage rotating about an axis of rotation AD, wherein the planetary stage comprises a sun gear, a planet carrier, and a ring gear, and wherein the planet carrier accommodates several planet gears rotating between side plates of the planet carrier and radially sliding-mounted, and alternatingly meshing with the ring gear and the sun gear, and wherein at least one axial sliding element is inserted into each side plate, and a collar section of each axial sliding element projects axially beyond the side plate and carries a sliding surface on its end face for the axial support of the planet gear. The collar section rests against the respective side plate on its rear side for direct axial support of the axial sliding element against the planet carrier.The collar section therefore rests directly against an inner surface of the side panel with its rear contact surface. A supporting force thus acts directly between the contact surface of the collar section and the inner surface of the side panel. No other elements or components are positioned between the collar section and the side panel in this area that would indirectly establish contact or force transmission.

[0012] The planetary gear set can comprise one or more planetary stages. The last planetary stage can drive a generator directly or indirectly. In the case of an indirect drive, an intermediate spur gear stage may be provided. The planet carrier can be of a cage-like design, rotatably mounted about the axis of rotation AD relative to a housing or housing component via suitable bearings. A rolling bearing arrangement may be provided for this mounting. In this case, the axis of rotation AD defines the axial direction, so that the respective radial directions result from this axial direction.

[0013] The planet gears are held to the planet carrier by planet shafts. The planet shafts run parallel to and offset from the axis of rotation AD. The planet gears are enclosed on both axial sides by a side plate of the planet carrier. The planet gears are free from the planet carrier and the side plates in a radial direction inwards and in a radial direction outwards, and are in meshing with a ring gear and a sun gear or sun gear shaft, respectively.

[0014] Structurally, the sliding surfaces are associated with the side walls. The side walls have an inner surface from which the sliding surfaces project axially, i.e., towards the respective planet gear. The inner surface of each side wall is advantageously aligned with an axial plane. The sliding surfaces are axially raised above the inner surface of the side walls, ensuring that during operation the planet gears contact the sliding surfaces and not the inner surfaces. The sliding surfaces are designed to be detachable from the side walls in a suitable manner.

[0015] The conventionally used thrust washers are replaced by at least one axial sliding element per side plate. This eliminates both the cost of the thrust washers and the associated costs for machining the inner surfaces of the side plates. The need for complex mirror surfaces, anti-rotation devices for the thrust washers, and their positioning is also eliminated. The material requirement of expensive bronze is reduced. By using a uniform design, the axial sliding elements can be used for different planetary stages, ideally for all gearboxes, resulting in further cost savings.

[0016] In a preferred embodiment of the planetary gear set, each side plate has at least one through-hole, and the axial sliding elements are inserted into the respective through-hole. The through-holes are particularly advantageous for a method of mounting planet gears in a planet carrier equipped with axial sliding elements. A holding element can be inserted from the outside through the through-holes as a tool, which holds the respective axial sliding element in a fixed position relative to the side plate. This allows the planet carrier to be moved during the assembly process, if necessary, without the axial sliding element dislodging from its mounting position if the planet gear is not yet installed. Advantageously, the axial sliding element has a threaded bore in its end face axially opposite the sliding surface to allow the holding element to be detachably received via this threaded bore.

[0017] In a preferred embodiment of the axial sliding element, it comprises a shaft section in addition to the collar section, wherein the shaft section of the axial sliding element has a diameter corresponding to the diameter of the through-hole. Specifically, it can be provided that the collar section has a second, larger diameter than the shaft section.

[0018] In a preferred embodiment of the axial sliding element, at least the sliding surface is formed from a bronze material or a polymer composite. A suitable support material is provided onto which the sliding surface is applied. In a further embodiment, however, it is also possible for the axial sliding element to be formed largely or even entirely from a bronze material or a polymer composite.

[0019] In a preferred embodiment of the planetary gear, it can be provided that each side plate has a number of axial sliding elements corresponding to the number of planet gears received by the planet carrier.

[0020] The problem is also solved by a drive train for a wind turbine for the torque-transmitting connection of a rotor with a generator, comprising a main bearing unit and a main shaft and a gearbox driven via the main shaft, wherein the gearbox is designed as a planetary gearbox as described.

[0021] The problem is further solved by a wind turbine with a rotor flange with a rotor and a generator, wherein a drive train held on a machine carrier and connecting the rotor flange to the generator is provided, wherein the drive train is designed as described.The problem is further solved by a method for mounting planetary gears in a planet carrier, in which, after providing a vertically positioned planet carrier, at least one axial sliding element is inserted into each through-bore passing through each side wall of the planet carrier, a retaining element is inserted into the through-bore of the vertically upper side wall and connected to the axial sliding element to hold the axial sliding element in the through-bore, and at least one planet gear is inserted between the axial sliding elements in the side walls, and a planetary axle is inserted into the side walls and the planet gear, and the retaining element is removed from the axial sliding element and from the through-bore.

[0022] In a preferred embodiment of the method, the retaining element is designed as a threaded pin and screwed to the axial sliding element in order to hold the axial sliding element in the through-hole.

[0023] In a preferred embodiment of the method, the axial sliding element is inserted into the vertically upper side wall from the bottom and the holding element from the top.

[0024] The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show:

[0025] Fig. 1: a schematic and partial representation of a gearbox,

[0026] Fig. 2: a detailed view of the gearbox according to Figure 1 in the area of ​​the planet carrier,

[0027] Fig. 3: an axial sliding element as a detail in a sectional view,

[0028] Figs. 4a) to 4d): a process flow for the assembly of planetary gears in a planet carrier and

[0029] Fig. 5: A perspective view of a wind turbine. Figure 1 shows a schematic, partial view of a gearbox 10. The gearbox 10 is designed as a planetary gearbox, of which only a first planetary stage 14 is shown. Several planetary stages 14 can be provided. The gearbox 10 can be part of a wind turbine, which will be described later, and connect a rotor to a generator to transmit drive torque.

[0030] The gearbox 10 comprises a gearbox housing 12, which may be multi-part, and in which a planet carrier 16 of the planetary stage 14 rotates about an axis of rotation AD. The planet carrier 16 holds several planet gears 18 rotatably mounted about their respective planet axes 44, the planet gears 18 meshing alternately with a ring gear 20 and a sun gear 22, both rotatably mounted in the gearbox housing 12. The planet gears 18 are mounted relative to the planet axis 28 via plain bearings 46. It may be provided that a rotor 72 of a wind turbine 70 drives the planet carrier 16 at least indirectly; see Figure 6. A further description of the structural design of the gearbox 10 is not necessary here.

[0031] Figure 2 shows a detailed view of the transmission 10 in the area of ​​the planet carrier 16 and a planet gear 18 rotatably mounted on a planet axis 44, and the ring gear 20 meshing radially with it. The planet carrier 16 forms two radially extending side plates 24, 26, spaced axially apart from each other, of which only one side plate 24 is shown in Figure 2. A gap 48 is located axially between the two side plates 24, 26, in which the planet gears 18 are accommodated. The planet gears 18, of which only one is shown as an example in Figure 2, are thus located axially between the side plates 24, 26. Due to axial forces acting on the planet gears 18, they tend to rotate towards one of the side plates 24, 26, depending on the direction of rotation.To hold the planet gears 18 in their axially intended position, at least one axial sliding element 30 is integrated into each side flange 24, 26. The axial sliding element 30 forms a collar section 32 that projects axially beyond the side flange 24, 26 and extends into the space 48, thus ensuring that the side flanks of the planet gear 18 are free from the respective side flange 24, 26 in both assembly and operating situations. The collar section 32 of the axial sliding element 30 has a sliding surface 34 on its end face for the axial support of the planet gear 18. The collar section 32 rests against the respective side flange 24, 26 on its rear side for direct axial support of the axial sliding element 30 against the planet carrier 16.

[0032] At least one of the side walls 24, 26 has a through-hole 36 into which an axial sliding element 30 is inserted. In addition to the collar section 32, the axial sliding elements 30 have a shaft section 38. The axial sliding element 30 sits in the through-hole 36 via the shaft section 38 and is thus positioned relative to the respective side wall 24, 26. The diameter of the shaft section 38 is approximately the same as the diameter of the through-hole 36, so that the shaft section 38, for example, fits into the through-hole 36 with a clearance fit. The collar section 32 has a second, larger diameter than the shaft section 38.

[0033] At least the sliding surface 34 is made of a bronze material or a polymer composite material. Alternatively, it can also be provided that the axial sliding element 30 is made of a bronze material or a polymer composite material.

[0034] Figure 3 shows a section view of an axial sliding element 30. The figure shows a variant in which a base body 50 of the axial sliding element 30 is made of a carrier material, and the sliding surface 34, for example made of a bronze material or a polymer composite, is applied to the base body 50. Furthermore, the axial sliding element 30 has, for example, a threaded bore 42 in the end face 40 axially opposite the sliding surface 34. A retaining element can then be detachably fastened in the threaded bore 42 for mounting purposes of the planet carrier 16, as will be described below.

[0035] Figures 4a) to 4d) show a process for mounting planetary gears 18 in a planet carrier 16, with the additional positioning of axial sliding elements 30 in the side walls 24, 26 of the planet carrier 16. In a first process step, schematically depicted in Figure 4a), a planet carrier 16 is provided and positioned vertically with respect to the axis of rotation AD. This results in one of the side walls 24, 26 being vertically at the top and the other side wall 24, 26 being vertically at the bottom. The space 48 is thus accessible from one side. Figure 4b) shows a process step in which an axial sliding element 30 is inserted into the through-bore 36 in each of the side walls 24, 26. The axial sliding elements 30 are inserted into the side walls 24, 26 from the inside through the space 48. A retaining element 52 is inserted into the vertical upper through-hole 36 of the vertical upper side wall 24.The retaining element 52 can be detachably screwed into the threaded bore 42 of the axial sliding element 30 to hold the vertically upper axial sliding element 30 in its position. Alternatively, the retaining element can have a magnet by which the axial sliding element 30 can be held in the through-bore 36. Figure 4c) shows the process step in which a planet gear 18 is inserted between the axial sliding elements 30 seated in the side walls 24, 26. Figure 4d) shows the process step in which a planetary shaft 28 is inserted into the side walls 24, 26 and the planet gear 18. The retaining element 52 is removed from the axial sliding element 30 and from the through-bore 36.

[0036] Figure 5 shows an embodiment of a wind turbine 70. The wind turbine 70 comprises a nacelle 71 to which a multi-blade rotor 72 is rotatably attached. The multi-blade rotor 72 is connected to a main shaft 74 for torque transmission, the main shaft 74 being part of a drive train 76. The drive train 76 further comprises a gearbox 78, which is connected to the main shaft 74 for torque transmission. The gearbox 78 has at least one planetary stage 14 and is in turn coupled to a generator 84 via a main bearing unit 82. A main shaft 74 is provided in the main bearing unit 82.

[0037] Reference symbol list

[0038] 10 planetary gears

[0039] 12 Gearbox housings

[0040] 14th planetary stage

[0041] 16 planetary carriers

[0042] 18 planetary gears

[0043] 20 Ring gear

[0044] 22 sun wheel

[0045] 24 side cheeks

[0046] 26 Side cheek

[0047] 28 Planetary axis

[0048] 30 Axial gl eitel em ent

[0049] 32 Collar section

[0050] 34 Sliding surface

[0051] 36 Through hole

[0052] 38 shaft section

[0053] 40 Front surface

[0054] 42 threaded holes

[0055] 44 planetary axes

[0056] 46 plain bearings

[0057] 48 space

[0058] 50 basic shapes

[0059] 52 retaining element

[0060] 70 wind turbines

[0061] 71 gondola

[0062] 72 Rotor

[0063] 74 Main shaft

[0064] 76 Drive train Rotor flange Machine carrier Main bearing unit Generator

Claims

1. P a t e n t a n s p r ü c h e 1. Planetary gear (10) for a wind turbine (70) driven by a rotor (72), with at least one planetary stage (14) rotating about an axis of rotation AD, wherein the planetary stage (14) has a sun gear (22), a planet carrier (16) and a ring gear (20), and the planet carrier (16) accommodates several planet gears (18) rotating between side plates (24, 26) of the planet carrier (16) and radially sliding-bearing mounted and alternatingly meshing with the ring gear (20) and the sun gear (22), and wherein at least one axial sliding element (30) is inserted into each side plate (24, 26), and a collar section (32) of each axial sliding element (30) projects axially beyond the side plate (24, 26) and carries a sliding surface (34) on its end face for axially supporting the planet gear (18), characterized in that the collar section (32) on the back of the respective side cheek (24,26) for the direct axial support of the axial sliding element (30) against the planet carrier (16).

2. Planetary gear (10) according to claim 1, characterized in that each side wall (24, 26) has at least one bore (36) and the axial sliding elements (30) are inserted into the respective bore (36).

3. Planetary gear (10) according to claim 2, characterized in that a shaft section (38) of the axial sliding element (30) has a diameter corresponding to a diameter of the bore (36).

4. Planetary gear (10) according to claim 3, characterized in that the collar section (32) has a second, larger diameter than the shaft section (38).

5. Planetary gear (10) according to one of claims 2 to 4, characterized in that the bore (36) is designed as a through bore through the respective side wall (24, 26).

6. Planetary gear (10) according to one of claims 1 to 5, characterized in that the sliding surface (34) is made of a bronze material or a polymer composite material.

7. Planetary gear (10) according to one of claims 1 to 6, characterized in that the axial sliding element (30) is made of a bronze material or a polymer composite material.

8. Planetary gear (10) according to one of claims 1 to 7, characterized in that the axial sliding element (30) forms a threaded bore (42) in the end face (40) axially opposite to the sliding surface (34).

9. Planetary gear (10) according to one of claims 1 to 8, characterized in that each side wall (24, 26) is provided with a number of axial sliding elements (30) corresponding to the number of planet gears (18) received by the planet carrier (16).

10. Drive train (76) for a wind turbine (70) for torque-transmitting connection of a rotor (72) with a generator (84), comprising a main bearing unit (82) and a main shaft (74) and a gearbox (10) driven via the main shaft (74), characterized in that the transmission (10) is designed as a planetary transmission according to one of the preceding claims.

11. Wind turbine (70) comprising a rotor flange (78) with a rotor (72) and a generator (84), wherein a drive train (76) is provided which is held on a machine carrier (80) and connects the rotor flange (78) to the generator (84), characterized in that the drive train (76) is designed according to claim 10.

12. Method for mounting planetary gears (18) in a planet carrier (16), in which, after providing a vertically positioned planet carrier (16), at least one axial sliding element (30) is inserted into each of the side walls (24, 26) of the planet carrier (16), a retaining element (52) is inserted into the through-hole (36) of the vertically upper side wall (24, 26) and connected to the axial sliding element (30) in order to hold the axial sliding element (30) in the through-hole (36), and at least one planet gear (18) is inserted between the axial sliding elements (30) in the side walls (24, 26), and a planetary shaft (28) is inserted into the side walls (24, 26) and the planet gear (18), and the retaining element (52) is removed from the axial sliding element (30). g eitel em ent (30) and is removed from the through-bore (36).

13. Method according to claim 12, characterized in that the retaining element is designed as a threaded pin (52) and is screwed to the axial guide element (30) in order to hold the axial guide element (30) in the through bore (36).

14. Method according to claim 12 or 13, characterized in that the axial sliding element (30) is inserted into the vertically upper side wall (24, 26) from vertically below and the retaining element (52) is inserted from vertically above.

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