SHAFT-HUB CONNECTION FOR A GEARBOX

Description

[0001] The invention relates to a shaft-hub connection for a planetary gear unit, comprising an inner hub element, an outer hub element connected to the inner hub element via a splined connection about a main rotational axis AR, and an outer hub element circumferentially surrounding the inner hub element, wherein the inner hub element and the outer hub element bear against each other via a pairing of axial contact surfaces. The invention further relates to a gear unit with a shaft-hub connection.

[0002] Wind turbine gearboxes typically contain planetary gear sets, which can be configured with one or more planetary stages. The gear teeth of the planetary gear sets are generally helical. The helical gearing results in axial forces within a planetary stage, which must be supported in the subsequent stage in the power flow. There are various configurations for the planetary gear sets and their stages. In one configuration, for example, the output of a planetary stage may be provided via the sun gear or a corresponding sun shaft, which is radially supported by a running gear against the planet gears and by a splined connection against a subsequent component, such as a hollow hub element of a spur gear stage. Structurally, the sun shaft is the inner hub element, while the hollow hub element is an outer one and may be designed as a hollow shaft.It is also possible to have a configuration in which the outer hub element directly drives a downstream generator, without an intermediate spur gear stage. In another configuration of the planetary stages, the arrangement of the inner and outer hub elements is such that the sun gear shaft of a planetary stage is designed as the outer hub element, and the inner hub element is designed as a hollow shaft for driving the downstream planetary stage. The inner hub element can, for example, be directly or indirectly connected to the planet carrier of the downstream stage.

[0003] The axial support of one hub element for the axial forces introduced in a principal force direction is typically achieved via a contact shoulder of this hub element, which bears against a corresponding contact shoulder of the other hub element. The corresponding contact shoulders are connected via a pair of axial contact surfaces. A contact shoulder can also be referred to as a shaft collar or shaft shoulder. Depending on the magnitude of the axial forces and any displacements of the components involved, wear can occur on the axial contact surfaces. This wear can generally be counteracted by lubricating the axial contact surfaces during operation. One possibility is to guide the oil axially through the splined connection between the two hub elements and supply it to the axial contact surfaces.This involves a passive oil supply, which reaches its limits particularly under high-speed operating conditions. Since the direct oil supply point to the axial contact surfaces is inherently located radially outside these surfaces, the prevailing centrifugal force drives the oil outwards, preventing sufficient oil from reaching the axial contact surfaces radially inwards. Another possibility is described in DE 10 2013 217 950 A1, which overcomes the described shortcomings of passive oil supply through pressure lubrication. This system actively delivers lubricating oil to the axial contact surfaces via oil channels. Such pressure lubrication can be considered disadvantageous in terms of effort and cost. There is a constant need to simplify and improve the lubrication of axial contact surfaces. Furthermore, EP 3 954 925 A1 and CN 102 312 928 A should be mentioned as prior art.

[0004] The purpose of the invention is to demonstrate measures that enable simplified and improved lubrication.

[0005] The problem is solved by a shaft-hub connection for 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.

[0006] One embodiment relates to a shaft-hub connection for a planetary gear, comprising an inner hub element, an outer hub element connected to the inner hub element via a splined connection about a main rotation axis AR and surrounding the inner hub element on the outside, wherein the inner hub element and the outer hub element bear against each other via a pairing of axial contact surfaces, wherein the inner hub element forms at least one oil channel in the region of the axial position of the axial contact surfaces, opening radially within the axial contact surfaces via an outlet opening, for lubricating the axial contact surfaces.

[0007] The main axis of rotation AR defines the axial direction, from which the respective radial directions result. The respective axial positions of the axial contact surfaces and the at least one radially extending oil channel of the inner hub element thus largely coincide. A strict geometric agreement between the axial positions of the axial contact surfaces and the oil channel(s) is not absolutely necessary.

[0008] Depending on the underlying configuration, the outer hub element can be designed as a hollow shaft or as a sun shaft / sun gear. The splined connection, which positively engages the inner and outer hub elements to transmit torque, can be referred to as short splines. The splines can be helical. The hub elements can be supported by bearing arrangements, for example, relative to a gearbox housing structure, with one of the bearings designed to absorb or support axial forces.

[0009] The oil channel is a through-bore extending from an inner circumferential surface of the inner hub element to an outer circumferential surface. The oil channel does not necessarily have to have a round cross-section; it can also be oval, rectangular, or slotted. The number of oil channels can vary depending on the application. It is advantageous if the oil channels are evenly spaced around the circumference of the inner hub element.

[0010] The inner hub element, preferably hollow, can centrally accommodate a pitch tube through which electrical conductors are routed. A circumferential volume is provided between the pitch tube and an inner circumference of the hub element, in which oil is held or into which oil can flow during operation, so that this oil is driven through the oil channel(s) by the centrifugal forces acting during operation.

[0011] In the described design of the shaft-hub connection, the lubricating oil does not have to work against centrifugal force to reach the axial contact surfaces, as is the case with conventional solutions for lubricating these surfaces. Instead, the centrifugal force assists the oil in reaching the axial contact surfaces. The service life of the axial contact surfaces can be extended by the more targeted and improved radial application of the lubricant within these surfaces.

[0012] In a further development that particularly promotes oil intake through the oil channels, the oil channels open into a geometry that runs circumferentially on the inner circumferential surface of the inner hub element. This geometry can be designed as a groove, a keyway, a shoulder, or a recess of some other shape opposite the inner circumferential surface. The inner circumference of the hub element has a larger diameter at one base of this geometry than in adjacent areas. Due to the centrifugal force present during operation, the oil collects particularly well in or around this geometry and can be retained there before flowing radially outwards through the oil channels extending from the geometry to reach the axial contact surfaces, thus lubricating and lubricating them. This circumferential geometry does not structurally weaken the hollow shaft, as the torque flow is already transmitted to the hub element via the splined connection during operation.The geometry is not within the area of ​​torque flow.

[0013] Since, in a specific embodiment, the axial contact surface of the inner hub element is formed on a radial shoulder of this hub element, an advantageous embodiment may provide that the oil channels open in the region of the radial shoulder. For example, a foot area can be provided as the opening region. This makes it easy for the oil to be flung radially outwards by the centrifugal force prevailing during operation, or to be driven outwards at the radial shoulder, directly onto the axial contact surface or between the pairing of axial contact surfaces of the inner and outer hub elements.

[0014] In a further preferred embodiment, a seal is provided between the inner and outer hub elements, with an axial offset relative to the oil channels. In particular, the seal is positioned such that the oil channels are located between the axial contact surfaces on the one hand and the seal on the other, so that the lubricating oil, after exiting the oil bores, must necessarily drain via the axial contact surfaces. The seal can be achieved, for example, by means of an O-ring or a plastic bushing inserted between the inner and outer hub elements.

[0015] In an advantageous embodiment of the axial contact surfaces, at least one of these surfaces is profiled. This ensures that a certain amount of lubricating oil can be retained in the oil grooves as a reserve, which continues to provide lubrication in operating situations where the supply of lubricating oil via the oil channels is reduced. The surface profiling can be designed such that at least one of the axial contact surfaces has a central convexity. Alternatively, the axial contact surfaces can also be conical or tapered relative to each other.

[0016] In a first possible embodiment, the radial shoulder or contact shoulder is integrally formed by the inner hub element, such that the hub element is machined at its end, for example by turning, and the radial shoulder extends between the turned diameter and the subsequent diameter. This embodiment is particularly advantageous when the main force direction, determined by the axial force, is directed towards the turned shaft end.

[0017] In another possible embodiment, the radial shoulder is formed by a bearing ring attached coaxially to the end of the inner hub element. The radial shoulder extends between the diameter of the shaft end and a correspondingly larger diameter of the bearing ring. This embodiment is particularly advantageous when the main force direction, determined by the axial force, is directed along the shaft from the shaft end carrying the bearing ring. For manufacturing purposes, the bearing ring can be held to the end of the hub element by a screw connection. This multi-part construction allows for the advantageous formation of oil channels by radially extending grooves on an end face of the hub element and / or an end face of the bearing ring.Furthermore, it can be provided that the oil channels and the groove circumferential on an inner circumferential surface of the hub element are arranged in a separating plane between the hub element and the mounting ring, resulting in a further simplification of the manufacturing process.

[0018] The problem is also solved by a gearbox for a wind turbine, consisting of at least one planetary stage and an outer hub element connected to the at least one planetary stage for drive, wherein at least one drive connection between several planetary stages and / or between the at least one planetary stage and the outer hub element is a shaft-hub connection as described above. In particular, it can be provided that the subsequent planetary stage rotates faster than the preceding planetary stage.

[0019] The problem can also be solved by a drive train for a wind turbine, comprising a rotor shaft connected to a gearbox for torque transmission and a generator connected to the gearbox for torque transmission, the gearbox being designed as described above. Furthermore, the planetary gearbox and the generator can also be integrated into one another, i.e., designed as a generator gearbox.

[0020] Similarly, the underlying problem is solved by a wind turbine comprising a nacelle on which a multi-blade rotor is rotatably arranged and which is connected to a drive train in a torque-transmitting manner, the drive train being designed as described above.

[0021] The underlying problem is solved by data agglomeration using data packages either combined in a single file or distributed across multiple files. These packages represent the three-dimensional shape and / or the interactions of all components in a shaft-hub connection as described above. The data packages are designed to enable the additive manufacturing of the shaft-hub connection components, particularly through 3D printing using a 3D printer, and / or the simulation of the shaft-hub connection's functionality. This allows for the cost-effective production of prototypes and / or computer-based simulations to study the shaft-hub connection's functionality, identify problems in specific applications, and find improvements.Similarly, the data model can be suitable for simulating the fluid dynamic behavior of an operating fluid, such as a lubricant.

[0022] 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: Fig. 1 : a first variant of a structural design of a shaft-hub connection; Fig. 2 : a detailed description of the shaft-hub connection according to Fig. 1 ; Fig. 3 : an alternative design of a shaft-hub connection; Fig. 4 : a second variant of a structural design of a shaft-hub connection; Fig. 5 : an alternative version to the variant according to Figure 4 ; Fig. 6 : a planetary gearbox in a drive train for a wind turbine and Fig. 7 : a perspective view of a wind turbine.

[0023] In the Figure 1Figure 1 shows a structural diagram of a possible configuration of a shaft-hub connection 10, the details of which are described in more detail below with reference to the following figures. The shaft-hub connection 10 is designed as a drive connection between a planetary gear stage 6 and a spur gear stage 8. Only a planet carrier PT and the meshing of planet gears PR with an inner hub element 12 are shown for the planetary gear stage 6, the inner hub element 12 being designed as a sun shaft. Only an outer hub element 14, designed as a hollow shaft, and a gear ZR non-rotatably connected to it are shown for the spur gear stage 8. If no spur gear stage 8 is provided, the outer hub element 14 can be driven, at least indirectly, by a generator (not shown). The outer hub element 14 is supported by a bearing arrangement L1 relative to a gearbox housing GG.Axial forces introduced into the outer hub element 14 can be supported via the bearing arrangement L1. The inner hub element 12 is supported, firstly, by a splined connection 16, through which the inner hub element 12 is drive-connected to the outer hub element 14 arranged around its circumference. Secondly, the inner hub element 12 is supported indirectly via a bearing arrangement L2 of the planet carrier PT in the gearbox housing GG. Both hub elements 12 and 14 can rotate about a main axis of rotation AR. The inner hub element 12, or sun shaft, is designed as a hollow shaft. This allows, for example, a non-rotating pitch tube to run inside the sun shaft 12 in an application where the shaft-hub connection 10 is used in a planetary gearbox for a wind turbine. The outer hub element 14 is also designed as a hollow shaft.

[0024] The Figure 2 Figure 1 shows a detailed view of the shaft-hub connection 10, in particular the area where an axial force acting on the inner hub element 12 is supported on the outer hub element 14. For clarity, arrow F indicates one of the principal directions of the axial force. The axial force arises during operation due to the helical gearing of the planetary stages. In this case, the angle of the helical gearing is designed such that the principal direction F of the axial force is shown in the diagram. Figure 2The diagram shows the inner hub element 12 and the outer hub element 14, which are connected via a pair of axial contact surfaces 20 and 22. The axial force introduced into the inner hub element 12 during operation is supported by these axial contact surfaces 20 and 22. Despite the positive-locking connection between the two hub elements 12 and 14 via the splined connection 16, relative movement occurs between the axial contact surface 20 of the inner hub element 12 and the axial contact surface 22 of the outer hub element 14. To counteract the resulting wear or at least to minimize it, the axial contact surfaces 20 and 22 are lubricated.

[0025] The inner hub element 12 forms a radial shoulder 24 on which the axial contact surface 20 is located. The outer hub element 14 forms a corresponding radial shoulder 36 on which the axial contact surface 22 is located. The two axial contact surfaces 20, 22 are advantageously oriented radially with respect to the main axis of rotation AR. The position of the two radial shoulders 24, 36 results in a mounting direction of the inner hub element 12 into the outer hub element 14 that is aligned with the main force direction F. To axially support an axial force acting opposite to the main force direction F during reversing operation of the planetary stage, a retaining ring 38 is held on the inner hub element 12. The retaining ring 38 supports the hub element 12 against a flank of the radial shoulder 36 that is rearward of the axial contact surface 22.

[0026] The inner hub element 12 forms several circumferentially distributed and radially directed oil channels 30 in the region of the axial position, with respect to the main axis of rotation AR, of the axial contact surfaces 20, 22 of the two radial shoulders 24, 36 for lubricating the axial contact surfaces 20, 22. The oil channels 30 can be designed as oil bores, for example, with a round cross-section. It can be seen that the oil channels 30 open radially outwards directly or at least approximately in a foot region 26 of the radial shoulder 24 via an outlet opening 50. Radially inwards, the oil channels 30 open onto an inner circumferential surface 34 of the hollow shaft 12, wherein it is specifically provided that an inner circumferential surface 34 of the hollow shaft 12 has a circumferential groove 32 and the oil channels 30 open into this groove 32.The indentation 30 ensures to a greater extent that, during operation and due to the prevailing centrifugal force, lubricating oil collects and is driven outwards via the oil channels 30. Upon exiting the oil channels 30, the oil then reaches and lubricates the axial contact surfaces 20 and 22. To ensure that the lubricating oil is delivered as completely as possible to the axial contact surfaces 20 and 22 after exiting the oil channels 30, a seal 28 is advantageously provided, which is arranged between an inner circumferential surface of the radial shoulder 36 and the inner hub element 12.

[0027] The Figure 3 Figure 1 shows an alternative embodiment of the shaft-hub connection 10, which can be used particularly when the main force direction F is in the opposite direction. This occurs when the angle of the helical gearing is opposite to the main axis of rotation AR. Essentially, the outer hub element 14 is identical to that shown in Figure 1. Figure 2In the variant shown, the axial contact surface 22 is arranged on the opposite axial flank. Correspondingly, the radial shoulder 24 is formed by a bearing ring 40 attached to the end of the inner hub element 12, with the bearing ring 40 and hub element 12 being coaxial to each other. The axial contact surface 22 of the hub element 12 is located on the end face 44 of the bearing ring 40 facing the radial shoulder 24. The bearing ring 40 is screwed to the shaft end of the hub element 12 by means of a screw connection 42, which is only indicated. It can be seen that the oil channels 30 are formed by radial grooves 46 that run on the end face 44 of the bearing ring 40. Alternatively or additionally, the grooves 46 can also run on an end face 18 of the hub element 12, which is not shown here.The oil channels 30 are extended radially outwards to such an extent that they cover the axial contact surface 22 in a radial direction.

[0028] In the Figure 4 A structural design of a further configuration of a shaft-hub connection 10 is shown. The shaft-hub connection 10 is intended here as a drive connection between a first planetary stage 4 and a second planetary stage 6, which are symbolized here by the two arrows and the reference symbols 4 and 6. Only a solar shaft SW of the planetary stage 4 is shown, with the solar shaft being designed as the outer hub element 14 of the shaft-hub connection 10. Only a planet carrier PLT of the subsequent planetary stage 6 is shown schematically, with the planet carrier PLT being designed as the inner hub element 12 of the shaft-hub connection 10. As for the Figure 2As described, a retaining ring 38 is provided, which supports the hub element 12 against a rear flank of the radial shoulder 36, relative to the axial contact surface 22. For further details regarding the structural design of the shaft-hub connection 10 and the configuration of the pairing of the axial contact surfaces 20, 22 and the radially internal lubrication, please refer to the description in the Figures 1 to 3 referred.

[0029] The Figure 5 shows an alternative structural design of the shaft-hub connection 10 of the Figure 4 Here, the axial contact surface 20, 22 of the inner hub element 12 is formed on a second retaining ring 48 that completely surrounds the inner hub element 12. Furthermore, reference is made here to the description of the Figures 1 to 4 referred.

[0030] The Figure 6Figure 2 shows, purely as an example, a planetary gear set 2, for instance, for a wind turbine. A first and second rotating planetary stages 4 and 6, and a spur gear stage 8 are arranged one after the other in a gear housing 3. A shaft-hub connection 10 is provided between the second planetary stage 6 and the spur gear stage 8 as a drive connection. It is possible that the second planetary stage 6 is designed to rotate at a higher speed than the first planetary stage 4.

[0031] In the Figure 7Figure 1 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 belonging to a drive train 76. The drive train 76 further comprises a planetary gear 2, which is connected to the main shaft 74 for torque transmission. The planetary gear 2 has at least one planetary stage 6 and one spur gear stage 8 and is coupled to a generator 80. In this embodiment, a shaft-hub connection 10 is provided between the planetary stage 6 and the spur gear stage 8 as a drive connection, the shaft-hub connection 10 being designed as described above. Reference symbol list

[0032] 2 Planetary gear 3 Gearbox housing 4 Planetary stage 6 Planetary stage 8 Spur gear stage 10 Shaft-hub connection 12 Hollow shaft 14 Hub element 16 Splined connection 18 End face 20 Axial contact surface 22 Axial contact surface 24 Radial shoulder 26 Foot area 28 Seal 30 Oil channel 32 Groove 34 Inner circumferential surface 36 Radial shoulder 38 Retaining ring 40 Mounting ring 42 Screw connection 44 End face 46 Groove 48 Retaining ring 50 Outlet 70 Wind turbine 71 Nacelle 72 Multi-blade rotor 74 Main shaft 76 Drive train 80 Generator

Claims

1. Shaft-hub connection (10) for a planetary transmission (2), comprising an inner hub element (12), an outer hub element (14) which is connected in terms of drive to the inner hub element (12) about a main axis of rotation AR via a spline toothing (16) and surrounds the inner hub element (12) at the outer circumference, wherein the inner hub element (12) and the outer hub element (14) bear against one another via a pairing of axial contact surfaces (20, 22), characterized in that the inner hub element (12) forms in the region of the axial position of the axial contact surfaces (20, 22) at least one oil channel (30) for oiling of the axial contact surfaces (20, 22), said at least one oil channel opening out radially within the axial contact surfaces (20, 22) via an outlet mouth (50).

2. Shaft-hub connection (10) according to Claim 1, characterized in that the at least one oil channel (30) opens out in a geometry which extends circumferentially on an inner circumferential surface (34) of the inner hub element (12).

3. Shaft-hub connection (10) according to Claim 1 or 2, characterized in that provision is made of multiple oil channels (30) which are distributed in a circumferential manner.

4. Shaft-hub connection (10) according to one of Claims 1 to 3, characterized in that, in the inner hub element (12), the at least one oil channel (30) has a radial profile or a profile which is inclined axially with respect to a radial direction.

5. Shaft-hub connection (10) according to one of Claims 1 to 4, characterized in that the axial contact surface (20, 22) of the inner hub element (12) is formed on a radial shoulder (24) of the inner hub element (12), and the at least one oil channel (30) opens out into regions (26) of the radial shoulder (24).

6. Shaft-hub connection (10) according to Claim 5, characterized in that the radial shoulder (24) is formed by an abutment ring (40) which is attached coaxially to the inner hub element (12) at one end.

7. Shaft-hub connection (10) according to Claim 6, characterized in that the abutment ring (40) is held on the inner hub element (12) at one end via a screw connection (42).

8. Shaft-hub connection (10) according to Claim 6 or 7, characterized in that the at least one oil channel (30) is formed by a geometry (46) which extends radially on an end face (18) of the inner hub element (12) and / or on an end side (44) of the abutment ring (40).

9. Shaft-hub connection (10) according to Claims 2 and 5, 6 or 7, characterized in that the at least one oil channel (30) and the encircling geometry are arranged in a separation plane between the inner hub element (12) and the abutment ring (40).

10. Shaft-hub connection (10) according to one of Claims 1 to 4, characterized in that the axial contact surface (20, 22) of the inner hub element (12) is formed on a securing ring (38) which engages circumferentially around the inner hub element (12).

11. Shaft-hub connection (10) according to one of Claims 1 to 10, characterized in that provision is made of a seal (28) between the inner hub element (12) and the outer hub element (14) with an axial offset from the at least one oil channel (30).

12. Shaft-hub connection (10) according to one of Claims 1 to 11, characterized in that a surface profiling is applied at least to one of the axial contact surfaces (20, 22).

13. Transmission (2) for a wind turbine, consisting of at least one planetary stage (4) and of an outer hub element (14) which is connected in terms of drive to the at least one planetary stage (4), wherein at least one drive connection between multiple planetary stages and / or between the at least one planetary stage (4) and the outer hub element (14) is configured as a shaft-hub connection (10) according to one of Claims 1 to 12.

14. Drive train (76) for a wind turbine (70), comprising a rotor shaft (74), which is connected in a torque-transmitting manner to a transmission (2), and a generator (80), which is connected in a torque-transmitting manner to the transmission (2), characterized in that the transmission (2) is designed according to Claim 12 or 13.

15. Wind turbine (70), comprising a nacelle (71) on which a multi-blade rotor (72) is arranged in a rotatable manner, said multi-blade rotor being connected in a torque-transmitting manner to a drive train (76), characterized in that the drive train (76) is designed according to Claim 14.