Overload clutch

Abstract

The invention relates to an overload clutch (10) having a longitudinal axis AL, in particular in a drivetrain (76) of a wind turbine (100), comprising: a first clutch part (12) which forms a friction surface (14) oriented perpendicular to the longitudinal axis AL and a pressure plate (16); a second clutch part (20) having at least one fixedly connected hub lamella (22); and a plurality of friction lamellae (30) which are received in pairs between the friction surface (14) and the hub lamella (22) and between the hub lamella (22) and the pressure plate (16), wherein a friction disc (32) is arranged in a floatingly mounted manner between each pair of friction lamellae (30). Each friction lamellae (30) of the pair travels only half of the friction stroke over which frictional power is absorbed.

Description

[0001] Overload coupling

[0002] Description

[0003] The invention relates to an overload coupling with a longitudinal axis AL, in particular in a drive train of a wind turbine, with a first coupling part which forms a friction surface and pressure plate perpendicular to the longitudinal axis, a second coupling part with at least one fixedly connected hub plate and several friction plates which are received in pairs between the friction surface and the hub plate and between the hub plate and the pressure plate.

[0004] In wind turbines, high torques occur due to grid outages or rotor-side dynamics. These torque peaks are absorbed by slip clutches located in the drive train, for example, between the gearbox and the generator. This effectively limits the maximum torque. This is a proven principle used in many wind turbines. The state of the art is described in documents US 11,371,570 B2 and WO 2011 / 048186.

[0005] However, existing overload or slip clutches have limited energy absorption capacity. At larger slip angles, these clutches overheat and can consequently fail prematurely. This occurs particularly with higher-power wind turbines and in regions with unstable power grids where wind turbines are operated. There is a need to be able to absorb power across a wider slip angle.

[0006] The object of the invention is to demonstrate measures that make it possible to provide an overload clutch for power absorption over a larger slip angle.

[0007] The problem is solved by an overload coupling with 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.

[0008] One embodiment relates to an overload coupling with a longitudinal axis AL, in particular in a drive train of a wind turbine, with a first coupling part, which each forms a friction surface and pressure plate perpendicular to the longitudinal axis, a second coupling part with at least one fixedly connected hub lamella and several friction lamellae, which are received in pairs between the friction surface and the hub lamella and between the hub lamella and the pressure plate, wherein a friction disc is arranged floatingly between the friction lamellae arranged in pairs in order to distribute a slip path between the coupling parts to the friction discs in a power-split manner, preferably to distribute a slip path between the coupling parts to the friction discs equally.

[0009] The hub plate of the second coupling part is designed to project radially between the first and second pairs of friction plates. The hub plate is thus axially enclosed by the friction plate pairs. Each friction disc axially positioned between the friction plate pairs can, in principle, rotate relative to the friction plates after overcoming a prevailing frictional torque. Preferably, one friction plate of the paired friction plates is connected to the friction surface or the pressure plate, and the other friction plate is connected to the hub plate. Furthermore, it is preferred that the first coupling part substantially radially surrounds the second coupling part.

[0010] When the first clutch part rotates relative to the second clutch part, from the perspective of a friction plate pair, this means that its friction plates can rotate against each other, again after overcoming the prevailing frictional torque, by

[0011] either the friction plate of the hub plates rotates relative to the friction disc, or the friction plates of the friction surface or the pressure plate rotate relative to the friction disc, or

[0012] Respective relative rotations occur between the friction surface or the pressure plate and the friction disc on the one hand, and the hub lamella and the friction disc on the other.

[0013] The third of these distinct cases is the one considered and described below for the embodiment described here. If, for example, the first clutch part and the second clutch part complete a 360° rotation relative to each other, then, assuming the same friction ratio between all friction partners involved, this 360° rotation is divided equally into a 180° rotation between the friction surface or pressure plate and the friction disc, and another 180° rotation between the friction disc and the hub plate. These two partial rotations are serial to each other, so that they complement each other to form the full 360° rotation of the two clutch parts. Compared to conventional solutions, in which one or each friction plate must complete the full 360° rotation, in the present embodiment each of the two friction plates only completes half the friction path over which it absorbs frictional power.Due to the relationship frictional power = torque x frictional distance, this means that for a given torque, the absorbed frictional power as a result of the halved frictional distance for the considered friction plate is also only 50%.

[0014] Preferably, the friction discs are arranged to rotate circumferentially relative to the first and second clutch components. The friction disc thus performs a power-splitting function by distributing the total frictional power to be absorbed, relative to the required friction path, between the two friction plates arranged in pairs. For the 360° rotation considered here, which branches equally into 180° rotations, the friction plates arranged in pairs share the required friction path. The friction discs can be appropriately supported radially outwards for this purpose, so that they remain centered during their circumferential movement. In particular, the friction discs can be guided radially relative to at least the first clutch component by at least one sliding band.

[0015] In a preferred embodiment, the pressure plate is held against a housing of the first coupling part by a screw connection. This screw connection can be implemented, in particular, by several stretch bolts arranged circumferentially. Stretch bolts advantageously ensure a constant preload even with progressive wear of the friction plates.

[0016] In a further preferred embodiment, at least one sliding band is arranged between the first and the second coupling part for radial guidance of both coupling parts relative to each other.

[0017] The problem is further solved by a drive train for a wind turbine for the torque-transmitting connection of a rotor to a generator, comprising a main bearing unit and a main shaft, and a gearbox driven via the main shaft, wherein the gearbox and the generator are connected to each other via an overload coupling as previously described. Furthermore, the problem is solved by a wind turbine comprising a rotor flange with a rotor and a generator, wherein a drive train is provided that is held on a machine frame and connects the rotor flange to the generator, and wherein the drive train is designed as described.

[0018] 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:

[0019] Fig. 1: a schematic representation of a wind turbine,

[0020] Fig. 2: a possible design of an overload coupling for a wind turbine and Fig. 3: a schematic representation of the operating principle of the overload coupling for torque limitation.

[0021] Figure 1 shows a schematic representation, not to scale, of a possible configuration of a wind turbine 100. The essential element of the wind turbine 100 is a drive train 102, which in this case structurally comprises a rotor flange 104 with a rotor 106, a main bearing unit 108, a gearbox 110, and a generator 112. The main bearing unit 108, the gearbox 110, and the generator 112 are supported against the ground (not shown) via a machine support 114 and a tower 116.

[0022] The main bearing unit 108 comprises a main shaft 118, which is rotatably mounted about an axis of rotation D relative to a bearing housing 120 of the main bearing unit 108. The rotor flange 104 is held at one end of the main shaft 118, and the rotor 106 is mounted on the flange. The other end of the main shaft 118 is driven by the gearbox 110 to transmit a drive torque applied by the rotor 106 to the gearbox 110. The gearbox 110 is connected to the machine carrier 114 via a torque arm 128 and can be designed as a planetary gearbox with one or more planetary stages. The gearbox 110 is driven by the generator 112 via a generator shaft 124. Reference numeral 10 denotes an overload clutch that can absorb any torque spikes that occur.

[0023] Figure 2 shows a possible embodiment of an overload coupling 10. Structurally, the overload coupling 10 consists of a first coupling part 12 and a second coupling part 20. Both coupling parts 12 and 20 are arranged concentrically around a longitudinal axis AL. The first coupling part 12 surrounds the second coupling part 20 essentially radially. The second coupling part 20 forms a radially projecting hub lamella 22, which projects into the first coupling part 12 and is axially encompassed by it. The hub lamella 22 is either rigidly connected to the second coupling element 20 or integrally formed with it.

[0024] The first coupling part 12 is composed of a housing 24 and a pressure plate 16 in the axial direction. The pressure plate 16 is held relative to the housing 24 of the first coupling part 12 by a screw connection 26, the screw connection 26 preferably being designed with several expansion bolts 28 arranged circumferentially.

[0025] The hub plate 22 of the second coupling part 20 projects radially into the first coupling part 12 between the housing 24 and the pressure plate 16. The housing 24 forms a friction surface 14 on the side facing the pressure plate 16. Between the friction surface 14 and the pressure plate 16, in addition to the hub plate 22, four friction plates 301 to 3Ü4 and two friction discs 32i, 322 are arranged. This arrangement is such that one friction plate 30i is located on the friction surface 14, one friction plate 3Ü4 is located on the pressure plate 16, and one friction plate 3Ü2 and one friction plate 30s are located on the axial surfaces of the friction plate 30. The friction plates 30i, 3Ü2 are thus arranged in pairs between the friction surface 14 and the hub plate 30 on the one hand, and the friction plate 30s, 3Ü4 is arranged in pairs between the hub plate 30 and the pressure plate 16 on the other. A friction disc 32i, 322 is floatingly mounted between each of these paired friction plates 30i, 3Ü2 and 3Ü3, 3Ü4.The friction discs 32i, 322 are arranged to be rotatable around their circumference relative to the first and second clutch parts 12, 20, and in this case are guided radially relative to at least the first clutch part 12 by a sliding band 18. A further sliding band 34 is arranged between the first and the second clutch parts 12, 20 for the radial guidance of both clutch parts 12, 20 relative to each other.

[0026] The operating principle of the overload clutch 10 for absorbing torque peaks is explained with reference to Figure 3. The following discussion focuses on the first clutch part 12 with the friction plate 301, the friction disc 321, and the hub plate 22 with the friction plate 3Ü2 of the second clutch part 20. A 360° rotation between the first and second clutch parts 12 and 20 is assumed, with the first clutch part 12 considered stationary and the 360° rotation being completed by a rotation of the second clutch part 20. It is further assumed that ideal and identical friction conditions prevail between the friction partners. This means that a torque applied to the second clutch part 20 simultaneously overcomes the existing static friction between the friction partners, and the respective friction partners begin a relative rotation with respect to each other. Consequently, the same slip occurs between all friction partners during the rotation.Figure 3 is divided into an upper half 36 and a lower half 38, which is symbolized by the arrows with the corresponding reference symbols.

[0027] In the upper and lower halves of the image 36, 38, the hub plate 22 (outer) and the friction surface 14 of the first clutch part 12 (inner) are shown. Only in the upper half of the image 36 is the end face of the friction disc 321 facing the hub plate 22 shown. Only in the lower half of the image 38 is the end face of the friction disc 32i facing the friction surface 14 shown. Arrows symbolizing rotations are drawn for the hub plate 22 and the friction disc 32i, respectively. The friction surface 14 of the first clutch part 12 does not rotate; therefore, no arrow is assigned to it. If the hub plate 22 now performs an angular rotation relative to a stationary friction surface 14, the friction disc 32i always experiences exactly half the angular rotation.The angular rotation of the hub plate 22 – with the friction plate 3Ü2 – is thus divided equally between the friction pair consisting of hub plate 22 and friction disc 321 on the one hand, and friction disc 32i and friction surface 14 – with the friction plate 301 – on the other. These friction pairs therefore experience only half the relative rotation, or only travel half the friction path, during a 360° rotation of the hub plate 22 or the second clutch part 20 relative to the friction surface 14 or the first clutch part 12. The friction path or slip path of the friction plates 30, via which the frictional power is absorbed, is consequently halved. Reference numeral list.

[0028] 10 Overload coupling 12 Coupling part 14 Friction surface

[0029] 16 printing plate

[0030] 18 sliding belt

[0031] 20 Clutch part 22 Hub plate 24 Housing

[0032] 26 Screw connection 28 Expansion screw 30 Friction plates

[0033] 32 friction disc

[0034] 34 Sliding band

[0035] 36 half of the image

[0036] 38 half of the image

[0037] 100 Wind turbine 102 Drive train 104 Rotor flange 106 Multi-blade rotor 108 Main bearing unit 110 Gearbox

[0038] 112 Generator

[0039] 114 Machine carrier 116 Tower

[0040] 118 Main shaft

[0041] 120 Bearing housing coupling generator shaft flange

[0042] Torque support

Claims

Patent claims 1. Overload coupling (10) with a longitudinal axis (AL), in particular in a drive train (76) of a wind turbine (100), comprising a first coupling part (12) which forms a friction surface (14) and pressure plate (16) perpendicular to the longitudinal axis (AL), a second coupling part (20) with at least one permanently connected hub plate (22) and several friction plates (30) which are mounted in pairs between the friction surface (14) and the hub plate (22) and between the hub plate (22) and the pressure plate (16), wherein a friction disc (32) is arranged floatingly between the paired friction plates (30) in order to distribute a slip path between the clutch parts (12, 20) to the friction discs (32) in a power-split manner.

2. Overload coupling (10) according to claim 1, characterized in that the friction discs (32) are arranged to be rotatable circumferentially relative to the first and second coupling part (12, 20).

3. Overload coupling (10) according to claim 1 or 2, characterized in that the friction discs (32) are guided radially at least relative to the first coupling part (12) via at least one sliding band (18).

4. Overload coupling (10) according to one of claims 1 to 3, characterized in that one friction plate (30i, 3 O4) of the paired friction plates (30) is connected to the friction surface (14) or the pressure plate (16) and the other friction plate (3Ü3, 3O4) is connected to the hub plate (22).

5. Overload coupling (10) according to one of claims 1 to 4, characterized in that the pressure plate (16) is held relative to a housing (24) of the first coupling part (12) by means of a screw connection (26).

6. Overload coupling (10) according to claim 5, characterized in that the screw connection (26) is designed via several expansion screws (28) arranged circumferentially distributed.

7. Overload coupling (10) according to one of claims 1 to 6, characterized in that the first coupling part (12) substantially radially surrounds the second coupling part (20).

8. Overload coupling (10) according to one of claims 1 to 7, characterized in that at least one sliding band (34) is arranged between the first and the second coupling part (12, 20) for radial guidance of both coupling parts (12, 20) to each other.

9. Drive train (102) for a wind turbine (100) for torque-transmitting connection of a rotor (106) with a generator (112), comprising a main bearing unit (108) and a main shaft (118) and a gearbox (110) driven via the main shaft (118), characterized in that the gearbox (110) and the generator (112) are connected to each other via an overload coupling (10) designed according to the preceding claims.

10. Wind turbine (100) comprising a rotor flange (104) with a rotor (106) and a generator (112), wherein a drive train (102) held on a machine carrier (114) and connecting the rotor flange (104) to the generator (112) is provided, characterized in that the drive train (102) is designed according to claim 9.

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