Shaft-hub connection with wear-optimized layer

Abstract

A shaft-hub connection (10) for a planetary transmission (2), with an inner hub element (12), an outer hub element (14) which is drive-connected to the inner hub element (12) about a main rotational axis AR via a spline system (16) and surrounds the inner hub element (12) on the outer circumference, wherein a housing element (3) is provided which is stationary with regard to the main rotational axis AR, and the inner and the outer hub element (12), (14) are mounted in the housing element (3) so as to circulate jointly about the main rotational axis AR, and the inner and outer hub element (12), (14) bear against one another via a pair of axial contact surfaces (20), (22). At least one of the axial contact surfaces (20), (22) is formed from a wear-optimized layer (28). The wear-optimized layer (10) provides an increased durability of the material pairing.

Description

[0001] Shaft-hub connection with wear-optimized layer

[0002] Description

[0003] The invention relates to a shaft-hub connection for a planetary gear, with an inner hub element, an outer hub element which is drivingly connected to the inner hub element via a spline around a main rotational axis AR and which surrounds the inner hub element on the outside, wherein a housing element which is fixed with respect to the main rotational axis AR is provided and in the housing element the inner and outer hub elements are mounted together so as to rotate around the main rotational axis AR and the inner and outer hub elements abut one another via a pair of axial contact surfaces.

[0004] Wind turbine gearboxes typically contain planetary gears, which can be designed with one or more planetary stages. The gearing of the planetary gears is usually helical. The helical gearing leads to axial forces within a planetary stage, which must be supported in the adjacent stage in the power flow. There are different configurations for planetary gearboxes and stages. In one configuration, for example, the output in a planetary stage can be via the sun gear or via a corresponding sun shaft, which is radially mounted in running gearing relative to the planet gears and in spline gearing relative to a downstream component, for example 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 can be designed as a hollow shaft.There may also be a structure in which the outer hub element directly drives a subsequently arranged generator, in particular the rotor of the generator, i.e. without the interposition of a spur gear stage.

[0005] The state of the art includes DE 10 2013 217950 Al, CN 102 312 928 A, D3, EP 3 954 925 Al and the brochure “Higher Performance capacity through the use of Coatings” from Schaeffler Technologie, the latter describing pairs of components rotating relative to one another, e.g. plain and rolling bearings.

[0006] The axial support of the axial forces introduced in a main force direction is usually provided by a contact shoulder on this hub element, which rests against a corresponding contact shoulder on the other hub element. The corresponding contact shoulders contact each other 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 operational displacements of the components involved relative to one another, movement and thus microwear can occur on the axial contact surfaces. One possible approach to reducing microwear is to maximize the contact surfaces within the available installation space. The disadvantage is that the contact surfaces then become dimensionally dependent on the component and further restrict the design options within the limited installation space.In addition, or in combination with these methods, the contact surfaces can be strengthened using conventional hardening processes. This can lead to additional and costly hard machining of components. There is a need to increase the load-bearing capacity of the contact surfaces through measures other than appropriate dimensioning.

[0007] The object of the invention is to demonstrate measures that enable an increase in the load-bearing capacity of the contact surfaces. This object is achieved by a shaft-hub connection with the features of claim 1. Preferred embodiments are specified in the subclaims and the following description, each of which, individually or in combination, can represent an aspect of the invention. If a feature is presented in combination with another feature, this merely serves 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.

[0008] One embodiment relates to a shaft-hub connection for a planetary gear, comprising an inner hub element, an outer hub element that is drivingly connected to the inner hub element via a spline around a main axis of rotation AR and that surrounds the inner hub element on the outside, wherein a housing element that is fixed with respect to the main axis of rotation AR is provided and in the housing element the inner and outer hub elements are jointly mounted so as to rotate around the main axis of rotation AR and the inner and outer hub elements abut one another via a pair of axial contact surfaces, wherein at least one of the axial contact surfaces is formed from a wear-optimized layer. From a structural perspective, the hub elements can also be shaft elements, flange elements or other components that are connected to one another in a rotationally fixed manner, which can transmit torque and support one another in the axial direction.

[0009] In this case, the main axis of rotation AR defines the axial direction, so that the respective radial directions arise from this axial direction. Depending on the underlying configuration, the outer hub element can be designed as a hollow shaft. The spline, which positively connects the inner and outer hub elements to transmit torque, can be referred to as short gearing. The hub elements can be mounted via bearing arrangements, for example relative to a gearbox housing structure that encompasses the housing element, wherein one of the bearings is designed to absorb or support axial forces. The inner hub element, preferably hollow, can centrally accommodate a pitch tube through which electrical lines are routed. A circumferential volume, in which oil can be held, is provided between the pitch tube and an inner circumference of the hub element.

[0010] The housing element can be a cover for a gearbox housing. The cover can be attached to the gearbox housing and screwed in place.

[0011] The wear-optimized layer can be designed with either a hard or a soft texture. If the wear-optimized layer has a hard texture, then the increased load-bearing capacity of the material pairing due to the layer eliminates the need to enlarge the contact surfaces. This leads to advantages in the utilization of limited installation space. Furthermore, the present invention report contributes significantly to an increase in reliability at the described contact point. If the wear-optimized layer has a soft texture, then the wear-optimized layer possesses a certain emergency running property due to its inherent lubricating properties, which can be created, for example, by adding bronze or graphite.

[0012] The wear-optimized coating provides increased resilience of the material pairing, eliminating the need to enlarge the contact area. This leads to advantages in utilizing limited installation space. Furthermore, the wear-optimized coating contributes significantly to increased reliability at the contact point described. In addition to the wear reduction achieved by the wear-optimized coating, another advantage is the increased insulation against current passage.

[0013] In a preferred embodiment, the at least one wear-optimized layer comprises a hot-work steel from group H, in particular H13, applied by an additive manufacturing process, or an applied plain bearing material. In particular, the wear-optimized layer can be applied by laser deposition welding. For laser deposition welding, this process can preferably be powder-based or wire-based. The wear-optimized layer can comprise a bronze alloy.

[0014] In a further preferred embodiment, it is provided that the axial contact surface of the inner and outer hub elements is formed on a respective, complementary radial shoulder of the hub elements. In one possible embodiment, it can be provided that at least one oil channel runs in the inner and / or outer hub element, opening in the region of the axial contact surfaces, for lubrication of at least the axial contact surfaces. The oil channel can be guided through one or both of the radial shoulders.

[0015] The object is also achieved by a gearbox for a wind turbine, comprising at least one planetary stage and an outer hub element drive-connected to the at least one planetary stage, wherein the connection between the at least one planetary stage and the outer hub element is designed as a shaft-hub connection as described.

[0016] The object is also achieved by a drive train for a wind turbine for the torque-transmitting connection of a rotor to a generator, comprising a main bearing unit, a main shaft accommodated in the main bearing unit, a gearbox driven via the main shaft and a generator drive-connected to the gearbox, wherein the gearbox is designed as previously described.

[0017] Finally, the object is achieved by a wind turbine comprising a rotor flange with a rotor and a generator, wherein a drive train is provided which is held on a machine support and connects the rotor flange to the generator, wherein the drive train is designed as described. The invention is explained below by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below can represent an aspect of the invention both individually and in combination. They show:

[0018] Fig. la): a non-scale representation of a wind turbine with one embodiment of the drive train;

[0019] Fig. 1b): a non-scale representation of a wind turbine with an alternative design of the drive train;

[0020] Fig. 2: a structural design of a possible configuration of a shaft-hub connection;

[0021] Fig. 3: a detail of the shaft-hub connection according to Figure 2.

[0022] Figure 1a) shows a schematic and not to scale representation of a wind turbine 100 with a drive train 102 in a so-called exploded arrangement. The drive train 102 structurally comprises a rotor flange 104 with a rotor 106, a main bearing unit 108, a gearbox 10, and a generator 112. At least the main bearing unit 108 and the generator 112 are supported by a machine support 114 via a tower 116 relative to a ground (not shown). The main bearing unit 108 comprises a main shaft 118, which is mounted rotatably about an axis of rotation AD relative to a bearing housing 120 of the main bearing unit 108 via an adjusted tapered roller bearing. The rotor flange 104 and the rotor 106 are held at one end of the main shaft 118. The other end of the main shaft 118 is in this case rigidly connected to the transmission 10 in order to introduce a drive torque applied by the rotor 106 into the transmission 10.The gearbox 10 is designed as a planetary gearbox with one or more planetary stages. The gearbox 10 is drivingly connected to the generator 112 via a generator shaft 124. The bearing housing 120 is connected to the gearbox 10 via a flange 126. A reaction torque of the gearbox 10 is supported against the machine frame 114 via the flange 126.

[0023] Figure 1b) shows a schematic and not-to-scale representation of a wind turbine 100 with a drive train 102 in a so-called integrated arrangement. In contrast to the split arrangement, the drive train is designed such that the gearbox 10 and the generator 112 form a structural unit, which is indirectly supported relative to the machine frame 114 via the main bearing unit 108.

[0024] Figure 2 shows the structural design of a possible configuration of a shaft-hub connection 10, the details of which will be described below with reference to the subsequent figures. The shaft-hub connection 10 is provided here as a drive connection between a planetary stage 6 and a spur gear stage 8. A generator (not shown) can be driven via the spur gear stage 8. Of the planetary stage 6, only a planet carrier PT and the toothed engagement of planet gears PR with an inner hub element 12 are shown, wherein the inner hub element 12 is designed here as a sun shaft. Alternatively, the inner hub element 20 can be connected to a planet carrier PT of the planetary gear 2, although this is not shown here. Of the spur gear stage 8, only an outer hub element 14, which is designed as a hollow shaft, and a gear ZR connected to it in a rotationally fixed manner are shown.If no spur gear stage 8 is provided, the outer hub element 14 can be drive-connected at least indirectly to a generator (not shown), in particular to the rotor of the generator. The outer hub element 14 is mounted via a bearing arrangement LI relative to a gearbox housing GG. Axial forces introduced into the outer hub element 14 can be supported via the bearing arrangement LI. The inner hub element 12 is mounted, on the one hand, via a spline 16, via which the inner hub element 12 is drive-connected to the outer hub element 14 arranged on the outside circumference. On the other hand, the inner hub element 12 is mounted indirectly via a bearing arrangement L2 of the planet gear carrier PT in the gearbox housing GG. The two hub elements 12, 14 can rotate about a main rotation axis AR. The inner hub element 12 or the sun shaft is designed as a hollow shaft.In an application where the shaft-hub connection 10 is used, for example, in a planetary gear for a wind turbine, this offers the possibility of having a non-rotating pitch tube running within the sun shaft 12. The outer hub element 14 is also designed as a hollow shaft in this case.

[0025] Figure 3 shows a detailed view of the shaft-hub connection 10, in particular of the area in which an axial force acting on the inner hub element 12 is supported on the outer hub element 14. For clarity, the arrow F indicates the main direction of the axial force. During normal operation, in contrast to reversing operation, the axial force is generated by the helical planetary gears. In this case, the angle of the helical gearing is designed such that the main direction F of the axial force points from left to right in the illustration in Figure 2. The inner hub element 12 and the outer hub element 14 contact one another via a pair of axial contact surfaces 20, 22. The axial force introduced into the inner hub element 12 during operation is supported via the axial contact surfaces 20, 22 and is introduced into the outer hub element 12.Despite the positive connection between the two hub elements 12, 14 via the spline 16, relative movements occur between the axial contact surface 20 of the inner hub element 12, on the one hand, and the axial contact surface 22 of the outer hub element 14, on the other. To counteract the resulting wear, the axial contact surfaces 20, 22 are formed from a wear-optimized layer 28. The axial contact surface 20, 22, and thus the respective wear-optimized layer 28, of the inner and outer hub elements 12, 14 are formed on a respective, complementary radial shoulder 24, 26 of the two hub elements 12. The radial shoulders 24, 26 and the respective wear-optimized layer 28 are not shown to scale. List of reference symbols.

[0026] 2 planetary gears

[0027] 3 Gearbox housing

[0028] 4 planetary stage

[0029] 6 planetary stage

[0030] 8 spur gear stage

[0031] 10 Shaft-hub connection

[0032] 12 Hub element

[0033] 14 Hub element

[0034] 16 spline

[0035] 18 Frontal surface

[0036] 20 axial contact surface

[0037] 22 Axial contact surface

[0038] 24 Radial shoulder

[0039] 26 Radi al Shoulder

[0040] 28 wear-optimized layer

[0041] 100 wind turbines

[0042] 102 drive train

[0043] 104 Rotor flange

[0044] 106 multi-blade rotor

[0045] 108 Main bearing unit

[0046] 112 Generator

[0047] 114 machine carriers

[0048] 116 Tower

[0049] 118 Main shaft

[0050] 120 bearing housings

[0051] 124 Generator shaft

[0052] 126 flange

Claims

Patent claims 1. Shaft-hub connection (10) for a planetary gear (2), comprising an inner hub element (12), an outer hub element (14) which is drivingly connected to the inner hub element (12) via a spline (16) about a main axis of rotation (AR) and which surrounds the inner hub element (12) on the outside, wherein a housing element (3) which is fixed with respect to the main axis of rotation AR is provided and in the housing element (3) the inner and outer hub elements (12, 14) are mounted together so as to rotate about the main axis of rotation AR and the inner and outer hub elements (12, 14) abut one another via a pair of axial contact surfaces (20, 22), characterized in that at least one of the axial contact surfaces (20, 22) is formed from a wear-optimized layer (28).

2. Shaft-hub connection (10) according to claim 1, characterized in that the at least one wear-optimized layer (28) comprises a hot-work steel from group H or an applied plain bearing material, in particular applied by an additive manufacturing process.

3. Shaft-hub connection (10) according to claim 1 or 2, characterized in that the wear-optimized layer comprises a bronze alloy.

4. Shaft-hub connection (10) according to one of claims 1 to 3, characterized in that the at least one wear-optimized layer (28) is applied by laser deposition welding.

5. Shaft-hub connection (10) according to one of claims 1 to 4, characterized in that the laser deposition welding process is powder-based or wire-based.

6. Shaft-hub connection (10) according to one of claims 1 to 5, characterized in that the wear-optimized layer (28) is formed by an applied anti-friction coating.

7. Shaft-hub connection (10) according to one of claims 1 to 6, characterized in that the axial contact surface (20, 22) of the inner and outer hub elements (12) are formed on a respective radial shoulder (24, 26) of the hub elements (12) which is formed complementary to one another.

8. Shaft-hub connection (10) according to one of claims 1 to 7, characterized in that the inner and outer hub elements (20, 22) are designed as hollow shaft elements, wherein the inner hub element (20) is designed as a hollow sun shaft for the planetary gear (2).

9. Shaft-hub connection (10) according to one of claims 1 to 7, characterized in that the inner and outer hub elements (20, 22) are designed as hollow shaft elements, wherein the inner hub element (20) is connectable to a planet carrier (PT) of the planetary gear (2).

10. Shaft-hub connection (10) according to one of claims 1 to 9, characterized in that in the inner and / or the outer hub element (20, 22) there runs at least one oil channel opening in the region of the axial contact surfaces (20, 22) for oiling at least the axial contact surfaces (20, 22).

11. Gearbox (2) for a wind turbine, comprising at least one planetary stage (4) and an outer hub element (14) drivingly connected to the at least one planetary stage (4), wherein the connection between the at least one planetary stage (4) and the outer hub element (14) is designed as a shaft-hub connection (10) according to one of claims 1 to 10.

12. Drive train (102) for a wind turbine (100) for the torque-transmitting connection of a rotor (106) to a generator (112), comprising a main bearing unit (108), a main shaft (118) received in the main bearing unit (108), a gearbox (10) driven via the main shaft (118), and a generator (112) drive-connected to the gearbox (2), characterized in that the gearbox (2) is designed according to claim 11.

13. Drive train according to claim 12, characterized in that a machine carrier (114) is provided on which the transmission (10) and the generator (112) are held.

14. Drive train according to claim 13, characterized in that the generator (112) is held indirectly via the transmission (10) on the machine carrier (114).

15. Wind turbine (100), comprising a rotor flange (104) with a rotor (106) and a generator (112), wherein a drive train (102) is provided which is held on a machine carrier (114) and connects the rotor flange (104) to the generator (112), characterized in that the drive train (102) is designed according to one of claims 12 to 14.

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