EP4042041A1

EP4042041A1 - Gearbox arrangement for wind turbine

Info

Publication number: EP4042041A1
Application number: EP20776066.1A
Authority: EP
Inventors: Martin KLÖNNE; Daniel Piel
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2019-10-11
Filing date: 2020-09-17
Publication date: 2022-08-17
Also published as: WO2021069038A1

Abstract

Aspects of the invention relate to a planetary gearbox arrangement (54) for a wind turbine (10). The planetary gearbox arrangement (54) comprises: a ring gear (40) and a housing (38) radially enclosing and coupled to the ring gear (40). At least one surface of the housing (38) defines a first meshing formation (70) that is formed to intermesh with a second meshing formation (76) defined in at least one surface of the ring gear (40) to couple the ring gear (40) and the housing (38).

Description

GEARBOX ARRANGEMENT FOR WIND TURBINE

TECHNICAL FIELD

The present disclosure relates to a gearbox arrangement for a wind turbine. Particularly, the present disclosure relates to a planetary gearbox arrangement including a ring gear and a housing, and to a wind turbine comprising the gearbox arrangement.

BACKGROUND

Wind turbines known in the art comprise a tower supporting a nacelle and a rotor with a number of rotor blades. The rotor drives a generator housed within the nacelle to output electrical power. A gearbox is positioned between the rotor and the generator. One type of wind turbine gearbox is known as an epicyclic or planetary gearbox, which are generally favoured for their compactness and high achievable gear ratios. As is known, planetary gear sets comprise a ring gear, a sun gear, and a planet carrier holding planet gears, all of which are contained within a housing. The housing functions as a structural element for transferring loads as well as for providing an enclosed and sealed volume for the gear sets and lubricants.

Load transfer between the ring gear and the housing is usually achieved using a combination of bolts and pins (‘pin-bolt interface’) extending between the housing and the ring gear. To meet existing standards, the connection between the housing and the ring gear is required to transmit maximum operating loads by friction. Moreover, to maintain performance over the design life of the turbine, an accurate tensioning of bolts and controlling of the friction at the interface is required for avoiding slip and consequential fretting. Currently, a high number of bolts and pins are required to meet these demands which restrict the extent to which the weight and size of the gearbox can be reduced. Furthermore, the pin-bolt interface of the ring gear to the housing represents a hard mount meaning that it provides virtually no vibration isolation.

Gear meshing within a gearbox generates vibrations, which are transferred to the gearbox housing and shafts. Such vibrations may either be radiated as airborne sound from the gearbox or be transmitted further out into the surrounding structural components of the wind turbine, where they may be radiated from blades, tower, or from the nacelle. Vibration caused by gear meshing can therefore contribute to the overall turbine noise output and/or cause tonalities in noise measurements. Wind turbine manufacturers are subject to increasingly strict limits for noise levels and tonal audibility and so gearbox design may compromise the ability of the wind turbine to confirm to these limits.

More recently, powertrain design has seen the development of integral gearboxes and generators, in which a generator is closely coupled to the gearbox. While this architecture leads to a compact powertrain, a major challenge is to insulate the gearbox from stray currents coming from the generator. In case of insufficient insulation, stray currents may travel into the gearbox and cause severe damage especially in Hertzian contact areas like gear meshes and roller bearings. As discussed above, the pin-bolt interface of the ring gear to the housing is a hard mount and provides little or no insulation.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a planetary gearbox arrangement for a wind turbine. The planetary gearbox arrangement comprises a ring gear. The planetary gearbox arrangement comprises a housing radially enclosing and coupled to the ring gear. At least one surface of the housing defines a first meshing formation that is formed to intermesh with a second meshing formation defined in at least one surface of the ring gear to couple the ring gear and the housing.

Coupling the ring gear and housing using intermeshing surfaces permits a high load transfer from the ring gear to the housing. Intermeshing surfaces may permit a higher load or torque transfer than is possible with conventional bolts. Accordingly, gearbox size can be reduced because the same torque transfer may be achieved for a smaller size of ring gear. The intermeshing surfaces define a load transfer path from the ring gear to the housing so that loading, particularly tangential, axial and radial loading, on the ring gear is transferred to the housing via the meshing surfaces. The intermeshing surfaces reduce the likelihood that the ring gear will experience, at its outer and side faces, slipping or fretting, or even failure of one or more bolts. In addition, the intermeshing surfaces hold the ring gear in place, and aid with assembly of the ring gear. Further advantages are seen in that the ring gear intermeshes with the housing rather than relying on other components, and so is better able to adjust to and deform under loads. The deformation under loads may be further controlled by the introduction of an intermediary layer between the housing and the ring gear. The stiffness of this intermediary layer affects the deformation. The deformation may also be influenced by adjusting the fit or clearance between the intermeshing surfaces.

The ring gear may be described as an annular gear. The ring gear may comprise one or more side surfaces connecting a radially inner surface and a radially outer surface.

The intermeshing surfaces of the ring gear may be described as ‘form fit’ surfaces. The intermeshing surfaces are formed to fit with one another. By intermeshing, it is meant that the relevant surfaces of ring gear and the housing are adapted to complement one another, and to lock one element in place relative to the other. The intermeshing surfaces also provide a torque transfer path through them.

The intermeshing surfaces may be formed with a rectangular, tapered, polygonal, involute or any other profile suitable to transmit the loads. The intermeshing surfaces may be straight or skewed providing a helix angle for supporting axial loads.

The housing radially encloses the ring gear, such that the ring gear is surrounded or enclosed by the housing. Particularly, the housing covers or extends across the ring gear at its radially outer surface. The housing may cover one or more of the side surfaces of the ring gear. The housing can therefore be considered to be radially external to the ring gear, with the ring gear disposed radially internal to the housing. The housing may also partially cover some of a radially inner surface of the ring gear, but it will be appreciated that the ring gear is not entirely enveloped by the housing, and that some of the ring gear will be left exposed to perform its function.

The ring gear may define a radially inner surface and a radially outer surface. The at least one surface of the ring gear that defines the second meshing formation may comprise the radially inner surface. The at least one surface of the ring gear that defines the second meshing formation may comprise the radially outer surface. Meshing of involute gear teeth introduces a tangential as well as radial force, which are transferred by meshing formations on the radially outer or inner surfaces of the ring gear.

The planetary gearbox arrangement may comprise an elastic and/or damping arrangement between the first and second meshing formations. The damping arrangement may comprise a damping layer formed to complement the first and second meshing formation.

The damping arrangement may comprise a hydraulic damping arrangement. The hydraulic damping arrangement may be provided in each of a plurality of chambers defined between the first and second meshing formations. The hydraulic damping arrangement may be controlled by a hydraulic actuator.

The provision of intermeshing surfaces permits the inclusion of elastic elements therebetween, which may be useful in reducing the transfer of vibrations caused by the gear meshing in the planetary gear.

The elastic elements may as well be useful for allowing the ring gear to deform and/or align under loads. This may lead to an improved load sharing between the planet gears and a better load distribution in the gear contacts.

The provision of intermeshing surfaces permits the inclusion of damping therebetween, which is useful in dissipating or damping vibrations caused by the gear meshing in the planetary gear. Damping or dissipating vibrations reduces noise radiated from the gearbox housing or other components within the wind turbine.

The damping arrangement may provide electrical insulation. Alternatively, the planetary gearbox arrangement may comprise an electrical insulation arrangement between the first and second meshing formations. The electrical insulation may be disposed between the ring gear and the housing.

Providing electrical insulation protects the gearbox, particularly running gear teeth and roller bearings from stray currents. This is important in general, but the present invention is particularly important in compact powertrain architectures where the generator is directly attached to the gearbox because in compact powertrain architectures the interface area providing potential spots for undesired electrical connections between generator and gearbox is much higher. Hence the risk of stray currents may be increased.

The first and second meshing formations may each comprise a plurality of protrusions. The plurality of protrusions may be evenly spaced around their respective surfaces.

The radially inner surface of the ring gear may comprise a plurality of gear teeth for meshing with one or more planet gears of the planetary gear set.

The housing may comprise at least two housing elements joined to one another. The first meshing formation may be defined at least in part by each of the housing elements. The ring gear may comprise at least two ring gear elements joined to one another. The second meshing formation may be defined at least in part by each of the ring gear elements.

According to another aspect of the invention, there is provided a wind turbine comprising a planetary gearbox arrangement as described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic diagram of a wind turbine and its power generation system architecture according to an embodiment of the invention;

Figure 2 shows a schematic cross-section of a planetary gearbox according to an embodiment of the invention;

Figure 3 shows an exploded perspective view of a ring gear and a ring gear housing of a planetary gearbox arrangement according to an embodiment of the invention;

Figure 4 shows a front view of the ring gear and part of the ring gear housing of Figure

3;

Figure 5 shows a perspective sectional view of the assembled ring gear housing and the ring gear of the planetary gearbox arrangement of Figure 3;

Figure 6 shows a damping layer for use in a planetary gearbox arrangement;

Figure 7 shows perspective view of part of a planetary gearbox arrangement including the damping layer of Figure 6 according to an embodiment of the invention;

Figure 8 shows a perspective sectional view of a planetary gearbox arrangement including the part shown in Figure 7 according to an embodiment of the invention;

Figure 9 shows a schematic cross section of a planetary gearbox arrangement according to an embodiment of the invention;

Figure 10 shows a sectional view of the assembled ring gear housing and a ring gear assembly comprising two separate ring gears; and

Figure 11 shows a cross-section of assembled ring gear housing and the ring gear including a schematic of an active hydraulic actuation system.

DETAILED DESCRIPTION Figure 1 illustrates an example wind turbine 10 and a schematic overview of the power generation system architecture 12 of the wind turbine 10. In Figure 1, a rotor 14, comprising blades 16 and a hub 18, drives a transmission in the form of a gearbox 20 by way of an input drive shaft 22. The gearbox 20 has an output shaft 24 which drives an electrical generator 26 for generating three-phase electrical power. The generator 26 is connected to a generator-side power conversion system 28, typically comprising an AC-DC power converter. The gearbox 22, generator 26, and the generator-side power conversion system 28 are housed within a nacelle 30 of the wind turbine. The generator-side power conversion system 28 connects to a line-side power conversion system 32, typically including a DC-AC converter and a step-up transformer. The line- side power conversion system 32 connects the wind turbine 10 to a power network 34 for transmission of power across long distances to where it is required. Other arrangements and architectures of a wind turbine are well known in the art.

Figure 2 shows a schematic view of an exemplary gearbox 22 in cross section. The gearbox 22 is a planetary gearbox, and comprises a planetary or epicyclic gear set 36 and a ring gear housing 38. The ring gear housing 38 forms part of a gearbox housing, which is represented schematically in Figure 2 and referred to generally with the reference numeral 39. The planetary gear set 36 includes a ring gear 40, three planet gears 42 connected by a planet carrier 44, and a sun gear 46. In other arrangements, the planetary gear set may include more than three planet gears. Torque is transferred from the rotor 14 through the gearbox 20 to the generator 26 via the planetary gear set 36. One of the planet carrier 44 and sun gear 46 is directly or indirectly connected to the input drive shaft 22, and the other is directly or indirectly connected to the output shaft 24. The planet carrier 44 and sun gear 46 may be indirectly connected to its respective one of the input shaft 22 or the output shaft 24 by further gear sets or torque converters. Typically, a gearbox comprises two or three gear stages. The operation of a planetary gear set is well known in the art and will not be discussed further here.

The ring gear 40 defines a radially inner surface 48 and a radially outer surface 50. At the radially inner surface 48 of the ring gear 40, a plurality of gear teeth (not shown in the Figures) are defined for meshing with gear teeth (not shown in the Figures) of the planet gears 42. As the ring gear 40 is substantially annular, two side surfaces 52, only one of which is shown in Figure 2, are provided between the radially inner and outer surfaces 48, 50.

The ring gear housing 38 of the gearbox 22 encloses the planetary gear set 36. As shown in Figure 2, the ring gear housing 38 surrounds the ring gear 40 around its radially outer surface 50. In some wind turbine gearboxes, the ring gear housing and the ring gear may be made of one integral part. In the embodiments shown, the ring gear housing 38 is part of a wider gearbox housing 39, as mentioned above. The gearbox housing is represented schematically in Figure 2 and, for clarity, is not specifically shown in the later figures.

As well as enclosing the ring gear 40, the ring gear housing 38 is also coupled to the ring gear 40 to permit transfer of torque and non-torque loads from the planetary gear set 36 and to keep the ring gear 40 stationary. The relationship between the ring gear 40 and the ring gear housing 38 will now be discussed with reference to Figures 3 to 5, which illustrate an exemplary planetary gearbox arrangement 54. Each of Figures 3 to 5 shows the ring gear housing 38 and the ring gear 40.

The ring gear 40 and ring gear housing 38 are coupled to improve static load transfer between these stationary components against the rotational, radial, and axial forces applied to the ring gear 40 by virtue of the planet gears 42. The coupling is achieved by a surface of the ring gear housing 38 and a surface of the ring gear 40 being shaped to complement one another so that they fit together to form a torque/ load coupling. The surfaces are therefore formed to intermesh with one another. The use of intermeshing surfaces permits a higher load transfer from the ring gear 40 to the housing 38. Additionally, the ring gear 40 and ring gear housing 38 are effectively locked together so that rotational movement of the ring gear 40, which may be detrimental to the operation of the gearbox 22, is prevented. Unwanted noise and vibration within the wind turbine 10 is also avoided by virtue of the improved coupling.

Although only the ring gear housing 38 is shown in these Figures, in practice the gearbox 22 may comprise one or more additional planetary gear sets arranged on one or both axial sides of the ring gear 40 and the ring gear housing 38, and additional housing parts that together with the ring gear housing 38 form the housing 39. In Figures 3 to 5, two housing components 56 are shown, which form the ring gear housing 38. For simplicity, the housing components 56 are depicted as identical halves, although it will be appreciated that each component 56 may be different. Each housing component 56 comprises an annular portion 58 and a flange portion 60 extending radially outwardly from one end of the annular portion 58. A plurality of holes 62 extend through the flange portion 60 around its circumference from its upper surface 64 to its lower surface 66. In other embodiments, the housing component may have a non-annular, casted shape such as including torque arms for supporting the gearbox against a bed frame.

As can be seen in Figure 5, the two housing components 56 are brought together to form the ring gear housing 38 so that the lower surfaces 66 of the flange portion 58 are in contact. When the lower surfaces 66 of the flange portion 58 are in contact, the plurality of holes 62 of one flange portion 58 can align with the plurality of holes 62 of the other flange portion 58. Pairs of aligned holes can receive connecting means (not shown) such as a pin or bolt to fix the two housing components 56 together.

A meshing formation is provided on the ring gear housing 38 to couple the ring gear housing 38 to the ring gear 40. Specifically, on a radially inner surface 68 of each housing component 56, a first meshing formation 70 is provided. The meshing formation 70 is formed in, i.e. integrally with, the ring gear housing 38, and, by extension, the gearbox housing 39, and is provided in the form of a plurality of grooves 72. The grooves 72 extend axially from an edge 74 of the radially inner surface 68 that is configured to be in contact with the other housing component of the ring gear housing 38 when the housing components 56 are connected. The grooves 72 are stopped grooves or blind grooves and so they extend only a part of the way along the surface 68. The grooves 72 are equally spaced around the circumference of the surface 68. When the housing components 56 are joined together by receiving a bolt or pin through aligned holes 62 in the flange portions 60, the grooves 72 also align.

By virtue of the first meshing formation 70, the ring gear housing 38 intermeshes with the ring gear 40. The first meshing formation 70 formed in the internal surface of the ring gear housing 38, i.e. the grooves 72 on the inner surface 68 of the annular portion 58, intermeshes with a corresponding meshing formation formed in the ring gear 40. Particularly, the meshing formation formed in the ring gear 40 is a second meshing formation 76. The second meshing formation 76 is formed in, i.e. integrally with, the radially outer surface 50 of the ring gear 40. The second meshing formation 76 comprises a plurality of protrusions 78, which may also be referred to as teeth or steps. It will be appreciated that the protrusions 78 of the second meshing formation 76 are shaped differently to the gear teeth on the radially inner surface 48. The protrusions 78 are formed to complement the grooves 72 of the housing components 56 and to fit into them, and so are evenly spaced around the circumference of the ring gear 40 at the same spacing as the spacing of the grooves 72 of the ring gear housing 38. It will be appreciated that in some embodiments the grooves 72 and protrusions 78 are not evenly spaced. The dimensions of the protrusions 76 and grooves 72 are substantially similar, although the dimensions differ such that a predetermined clearance is incorporated between the ring gear 40 and the ring gear housing 38. For example, see Figure 4, in which a clearance 80 is provided between each protrusion 76 and the corresponding groove 72.

The ring gear 40 fits into each housing component 56, as can be seen in Figure 4, by the complementary formation and intermeshing of the radially outer surface 50 of the ring gear 40 and the inner surface 68 of the ring gear housing 38. When the housing components 56 are connected, as shown in Figure 5, the ring gear 40 is clamped in place by the housing components 56 by virtue of the stopped ends of the grooves 72. Therefore, both axial and rotational/radial movement of the ring gear 40 relative to the ring gear housing 38 is prevented, and the ring gear housing 38 and ring gear 40 are coupled together to create a torque transfer path for transmitting torque and loads from the ring gear 40 to the ring gear housing 38 for dissipation to the gearbox housing 39 in general and to the mounting structures to which the gearbox is mounted within the wind turbine.

In the embodiment of Figures 3 to 5, the first meshing formation 70 is distributed across more than one part of the ring gear housing 38. By distributing the first meshing formation 70 across two housing components 56, torque transferred from the ring gear 40 to the housing 38 via the intermeshing first and second meshing formations 70, 76 is distributed between the components 56 and each housing component 56 receives a reduced load. In other embodiments, the first meshing formation may be distributed across more than two housing components that are part of the ring gear housing, or may be entirely provided in one housing component of the ring gear housing, as will be discussed later in relation to Figure 8.

The distribution of the first meshing formation 70 is determined according to how the loads are to be distributed or dispersed. For example, having identical halves as housing components 56 is likely to result in a 50% split of torque across the components 56. The first meshing formation 70 may be distributed in a different ratio between housing components, and the torque transfer will be shared according to the distribution. It is the relative overlap between the ring gear housing and the ring gear that influence the torque transferred to each component.

Similarly, in the embodiment of Figures 3 to 5, the ring gear 40 is a single structure and so the second meshing formation 76 entirely on the single structure of the ring gear 40. In other embodiments, such as the embodiment of Figure 10, the ring gear 40 may comprise two or more ring gear elements connected by pins, bolts, or other joining elements. In the embodiment of Figure 10, the ring gear 40 comprises two ring gear elements 106 having the same width joined by pins 108. Despite not being explicitly depicted in Figure 10, the second meshing formation may be distributed between the two or more of the ring gear elements 106 in order to dictate how loads are transferred or dissipated to the housing 38. In the embodiment of Figure 10, the housing 38 comprises two housing components 56, as in the embodiment shown in Figures 3 to 5. The split 110 between the housing components 56 and the split 112 between the ring gear elements 106 are aligned in this embodiment, although the splits may not be aligned in other embodiments to further dictate how loads are transferred.

Another exemplary embodiment of a gearbox arrangement 90 is provided in Figures 6 to 8, where the gearbox arrangement 90 is provided with a damping layer 92 between a housing 94 and the ring gear 40.

The gearbox arrangement 90 of Figures 6 to 8 differs from the gearbox arrangement 54 of Figures 3 to 5 by virtue of the provision of a damping layer 92 and a differently arranged ring gear housing 94, having different housing components 96, 98. The ring gear 40 is the same in each of the two embodiments, and so has been given the same reference numeral.

In this gearbox arrangement 90, the ring gear housing 94 comprises first and second housing components 96, 98. The first housing component 96 is similar to the housing components 56 in the embodiment of Figures 3 to 5. The first housing component 96 has an annular portion 58 and a flange portion 60 arranged as in the housing components 56 of the previous illustrated embodiment. Once again, it will be appreciated that the housing component 96 may have a non-annular shape in other embodiments. The flange portion 60 similarly has a plurality of holes 62. The holes 62 of the flange portion 60 are configured to align with corresponding holes (not shown) of the second housing component 98 to fix the first and second housing components 96, 98 together using the appropriate fasteners, such as bolts or pins (not shown).

The first housing component 96 defines the first meshing formation 70. The second housing component 98 comprises an annular ring and acts to clamp the ring gear 40 within the ring gear housing 94. Therefore, in this embodiment, both meshing formations 70, 76 are provided on a single element of the housing and ring gear 40 respectively.

As with the previous embodiment, it will be appreciated that the ring gear housing 94 forms only a part of a complete gearbox housing, and is provided to illustrate the arrangement shown only.

With specific reference to Figure 6, the damping layer 92 is configured to damp vibrations caused by meshing of the planet and ring gears and/or to provide vibration isolation so as to isolate the ring gear housing 94 from the ring gear 40, and is provided between the ring gear housing 94 and the ring gear 40, in this embodiment between the first housing component 96 and the ring gear 40. To allow the damping layer 92 to be positioned between the first housing component 96 and the ring gear 40, the layer is shaped to conform to the first and/or second meshing formation 70, 74, and so comprises, in this embodiment, a plurality of grooves and protrusions as can be seen in Figure 6. The damping layer may be formed of a rubber material or a plastic material or another material having good damping or vibration isolation properties. The material may also be electrically insulating. Although depicted here in relation to the embodiment of Figures 6 to 8, the damping layer may also be provided in the arrangement of Figures 3 to 5 or any other ring gear and housing formation according to the present invention.

In other embodiments, a damping layer may cover the outer and side surfaces of the ring gear 40 entirely. In other embodiments, an alternative damping arrangement may be provided to damp vibrations caused by the meshing of the planet and ring gears instead of or in addition to the damping layer. For example, although the damping layer 92 is a single structure, the damping layer may be provided as multiple elements arranged between the ring gear and ring gear housing. In other embodiments, the damping arrangement may be a hydraulic damping arrangement. An embodiment showing an arrangement with a hydraulic damping arrangement is shown in Figure 11. The ring gear and housing shown in Figure 11 are substantially identical to the arrangement of Figure 4 so share the same reference numerals. The arrangement of Figure 11 differs in that a plurality of chambers 114 are defined in the clearances 80 between the meshing formations. The chambers may be sealed, for example with static sealing elements (not shown) and filled with a hydraulic fluid so that hydraulic damping is achieved between the ring gear and the ring gear housing, further improving the damping capabilities of the arrangement. The hydraulic damping system 116 comprises a hydraulic actuator, here depicted as a two-way variable displacement pump 118 connected between adjacent chambers 114. Additionally, or alternatively, the hydraulic damping arrangement may be controlled by a passive or other active hydraulic actuator configured to control the damping action of the fluid within the chambers.

Electrical insulation may also be provided between the ring gear and the ring gear housing. An electrical insulation arrangement, in the form of a layer of electrically insulating material may be provided between contacting surfaces of the ring gear and ring gear housing to prevent stray electrical currents passing from the ring gear to the housing or from the housing to the ring gear. The electrical insulation arrangement and damping arrangement may be integrally formed. For example, the damping arrangement may be chosen based on its electrically insulating and damping properties, so that the damping arrangement provides both damping and electrical insulation in a combination that is useful for the gearbox. The damping arrangement and electrical insulation arrangement may be generally referred to as a functional layers or arrangements. One or more functional layers may be provided between the ring gear and ring gear housing to perform particular functions.

In embodiments where the housing and ring gear contact directly, i.e. without an intermediate layer, the fit between these components may be relatively tight, so that movement and vibration between them is minimised. In embodiments without an intermediate layer, where deformation and/or a displacement of the ring gear under load shall be realized, the fit between the housing and the ring gear may be relatively loose in order to achieve load compensation. In embodiments including an intermediate layer or arrangement, such as the damping arrangement or electrical insulation arrangement, a suitable spacing or clearance is provided between the housing and ring gear to accommodate the additional arrangement.

Although the first and second meshing formations 70, 74 above comprise corresponding protrusions and grooves, the first and second meshing formations may comprise any complementary shapes that permit intermeshing of the ring gear and housing. For example, a plurality of splines may be provided on the ring gear that correspond to grooves provided in the housing. Alternatively, a plurality of apertures or blind bores may be provided in one of the housing or ring gear that mate with and intermesh with a plurality of dowels or pins formed in the other of the housing or ring gear. Such an inverted form fit may be particularly beneficial for ease of manufacturing.

In some embodiments, the radially inner surface of the ring gear may define the second meshing formation. Figure 9 is provided as an example of the radially inner surface defining the second meshing formation. Figure 9 shows a cross-sectional view of the ring gear housing 100 and ring gear 40. Here, the housing 100 comprises a re entrant portion 102 that wraps around the ring gear 40 from the radially outer surface 50 to the side 52 and to the radially inner surface 48 of the ring gear 40. The first meshing formation is formed on the re-entrant portion 102 and is configured to intermesh with the second meshing formation formed on the radially inner surface 48 of the ring gear 40. Although the outer surface of the housing obscures the meshing formations in Figure 9, the dotted lines 105 indicate the relative positions of the protrusions and grooves of the first and second meshing formations. In Figure 9, the gear teeth 41 of the ring gear 40, which are configured to mesh with gear teeth of the planet gears in use, are represented by horizontal lines on the radially inner surface 48 of the ring gear 40. In other embodiments of an arrangement where the radially inner surface of the ring gear defines the second meshing formation, the gear teeth 41 of the ring gear 40 form the second meshing formation and the re-entrant portion 102 is provided with protrusions that are configured to intermesh with the gear teeth 41 to lock the ring gear and housing together. In effect, therefore, the protrusions will form a negative shape of the gear teeth to provide intermeshing.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A planetary gearbox arrangement (54) for a wind turbine (10), comprising: a ring gear (40); and a housing (38) radially enclosing and coupled to the ring gear (40), wherein: at least one surface of the housing (38) defines a first meshing formation (70) that is formed to intermesh with a second meshing formation (76) defined in at least one surface of the ring gear (40) to couple the ring gear (40) and the housing (38).

2. The planetary gearbox arrangement (54) of claim 1, wherein the ring gear (40) defines a radially inner surface (48) and a radially outer surface (50) and wherein the at least one surface of the ring gear (40) that defines the second meshing formation (76) comprises the radially inner surface (48) or the radially outer surface (50).

3. The planetary gearbox arrangement (54) of claim 1 or claim 2, comprising a damping arrangement between the first and second meshing formations (70, 76).

4. The planetary gearbox arrangement (54) of claim 3, wherein the damping arrangement comprises a damping layer (92) formed to complement the first and second meshing formation (70, 76).

5. The planetary gearbox arrangement (54) of claim 3, wherein the damping arrangement comprises a hydraulic damping arrangement.

6. The planetary gearbox arrangement (54) of claim 5, wherein the hydraulic damping arrangement is provided in each of a plurality of chambers defined between the first and second meshing formations (70, 76).

7. The planetary gearbox arrangement (54) of claim 5 or claim 6, wherein the hydraulic damping arrangement is controlled by a hydraulic actuator.

8. The planetary gearbox arrangement (54) of any of claims 3 to 7, wherein the damping arrangement provides electrical insulation.

9. The planetary gearbox arrangement (54) of any of claims 1 to 7, comprising an electrical insulation arrangement between the first and second meshing formations (70, 76).

10. The planetary gearbox arrangement (54) of any of claims 1 to 9, wherein the first and second meshing formations (70, 76) each comprise a plurality of protrusions (78).

11. The planetary gearbox arrangement (54) of claim 10, wherein the plurality of protrusions (78) are evenly spaced around their respective surfaces.

12. The planetary gearbox arrangement (54) of any of claims 1 to 11, wherein the housing (38) comprises at least two housing elements (56) joined to one another and wherein the first meshing formation (70) is defined at least in part by each of the housing elements (56).

13. The planetary gearbox arrangement (54) of any of claims 1 to 12, wherein the ring gear (40) comprises at least two ring gear elements joined to one another and wherein the second meshing formation (76) is defined at least in part by each of the ring gear elements.

14. A wind turbine (10) comprising the planetary gearbox arrangement (54) of any preceding claim.