阅读说明：本技术 用于风力涡轮机的偏航系统的支承单元 (Support unit for a yaw system of a wind turbine ) 是由 F·克里斯滕森 D·奥斯特伯格 于 2019-09-02 设计创作，主要内容包括：本发明涉及一种用于风力涡轮机(10)的偏航系统(27)的支承组件(23)的支承单元(5)。风力涡轮机(10)包括通过偏航系统(27)连接的塔架(12)和机舱(14)。偏航系统(27)包括齿圈(24),齿圈(24)包括齿形构件(33),齿形构件(33)被构造成与电动机的齿轮相互作用以允许机舱(14)相对于塔架(12)定向。该支承单元(5)包括：调整器元件(11),其被布置成可移动地固定到该支承组件(23)；主体元件(8),其相对于该调整器元件(11)可平移；支承元件(7),其与该主体元件(8)相接触,该支承元件(8)包括用于在使用期间与该齿圈(24)的表面(26,28)相接触的支承表面(71)；以及偏置装置(9),其被定位在该主体元件(8)与该调整器元件(11)之间以用于向该支承单元(5)施加张力以便在使用期间将该支承元件(8)偏置成与该齿圈(24)的表面(26,28)相接触。该调整器元件(11)被构造成通过控制该主体元件(8)的平移来调整施加到该支承单元(5)上的张力,并且该支承单元(5)被构造成使得该调整器元件(11)和该主体元件8的对应表面(25,21)在使用期间是可见的。(The invention relates to a support unit (5) for a support assembly (23) of a yaw system (27) of a wind turbine (10). The wind turbine (10) includes a tower (12) and a nacelle (14) connected by a yaw system (27). The yaw system (27) includes a ring gear (24), the ring gear (24) including a toothed member (33), the toothed member (33) being configured to interact with a gear of the motor to allow orientation of the nacelle (14) relative to the tower (12). The support unit (5) comprises: an adjuster element (11) arranged to be movably fixed to the support assembly (23); a body element (8) translatable relative to the adjuster element (11); a bearing element (7) in contact with the body element (8), the bearing element (8) comprising a bearing surface (71) for contact with a surface (26, 28) of the ring gear (24) during use; and biasing means (9) positioned between the body element (8) and the adjuster element (11) for applying tension to the support unit (5) to bias the support element (8) into contact with the surfaces (26, 28) of the ring gear (24) during use. The adjuster element (11) is configured to adjust the tension applied to the support unit (5) by controlling the translation of the body element (8), and the support unit (5) is configured such that the adjuster element (11) and corresponding surfaces (25, 21) of the body element (8) are visible during use.)

1. A support unit (5) for a support assembly (23) of a yaw system (27) of a wind turbine (10), the wind turbine (10) comprising a tower (12) and a nacelle (14) connected by the yaw system (27), wherein the yaw system (27) comprises a gear ring (24), the gear ring (24) comprising a toothed member (33), the toothed member (33) being configured to interact with a gear of an electric motor to allow orientation of the nacelle (14) with respect to the tower (12), the support unit (5) comprising:

an adjuster element (11) arranged to be movably secured to the support assembly (23);

a body element (8) which is translatable with respect to the adjuster element (11);

a bearing element (7) in contact with the body element (8), the bearing element (8) comprising a bearing surface (71) for contacting a surface (26, 28) of the ring gear (24) during use; and the number of the first and second groups,

a biasing means (9) positioned between the body element (8) and the adjuster element (11) for applying tension to the support unit (5) so as to bias the support element (8) into contact with a surface (26, 28) of the ring gear (24) during use, wherein the adjuster element (11) is configured to adjust the tension applied to the support unit (5) by controlling translation of the body element (8),

the support unit (5) is configured such that corresponding surfaces (25, 21) of the adjuster element (11) and the body element (8) are visible during use.

2. The support unit (5) according to claim 1, wherein the biasing means (9) is configured to apply a predetermined tension to the support unit (5) when the support unit (5) is mounted in the support assembly (23) prior to use, and wherein the support unit (5) is configured such that the corresponding surfaces (25, 21) of the adjuster element (11) and the body element (8) are coplanar when the predetermined tension is applied.

3. The support unit (5) of claim 1 or 2, wherein, when the support unit (5) is mounted in the support assembly (23), the surface (21) of the body element (8) is configured to move up or down relative to the surface (25) of the adjuster element (11) to indicate that the tension applied to the support unit (5) has decreased.

4. Support unit (5) according to any one of the preceding claims, wherein said corresponding surfaces (25, 21) comprise end faces of said regulator element (11) and said body element (8).

5. Support unit (5) according to any one of the preceding claims, wherein the body element (8) comprises a rod (83) and the adjuster element (11) comprises an aperture (15) through which the rod (83) is slidably received.

6. Support unit (5) according to claim 5, wherein said rod (83) comprises retaining means (19) arranged to limit the translation of said body element (8) away from said adjuster element (11).

7. Support unit (5) according to any one of the preceding claims, wherein the adjuster element (11) comprises an inner surface (94) for limiting the translation of the body element (8) towards the adjuster element (11).

8. The support unit (5) according to any one of the preceding claims, wherein the support surface (71) is arranged to contact a lower surface (28) or an upper surface (26) of the ring gear (24) during use.

9. A support assembly (23) for a yaw system (27) of a wind turbine (10), the support assembly (23) comprising a support unit (5) according to any of the preceding claims.

10. A yawing system (27) for a wind turbine (10), the yawing system (27) comprising a support assembly (23) according to claim 9.

11. A yawing system (27) according to claim 10, the yawing system (27) further comprising a control unit configured to:

-determining a translation of the body element (8) with respect to the adjuster element (11); and the number of the first and second groups,

upon determining that the body element (8) has translated, issuing a maintenance control signal.

12. A yawing system (27) according to claim 11, wherein the maintenance control signal is configured to indicate a deterioration of the support element (7) if it is determined that the body element (8) has moved away from the regulator element (11), and to indicate that the biasing device (9) needs to be replaced if it is determined that the body element (8) has moved towards the regulator element (11).

13. A wind turbine (10), the wind turbine (10) comprising a yaw system (27) according to any of claims 10-12.

Technical Field

The present invention generally relates to the field of support units for wind turbines. In particular, the invention relates to a support unit for a yaw system of a wind turbine.

Background

Wind turbines known in the art include a yaw system that includes a ring gear supported by a plurality of bearing units held in a series of bearing assemblies. The bearing unit is designed to contact the gear ring to stabilize the motion of the yaw system and is tensioned at installation to maintain the necessary contact during use. These support units are regularly checked to verify that they are correctly tensioned and/or need to be replaced or repaired if necessary. In order to access the support unit during inspection, at least a portion of the support assembly needs to be disassembled. This can be cumbersome, time consuming and labor intensive.

Against this background, the present invention has been devised.

Disclosure of Invention

According to a first aspect of the present invention, there is provided a support unit for a support assembly of a yawing system for a wind turbine, the wind turbine comprising a tower and a nacelle connected by the yawing system, wherein the yawing system comprises a ring gear including a toothed member configured to interact with a gear of an electric motor to allow orientation of the nacelle relative to the tower, the support unit comprising: an adjuster element arranged to be movably secured to the support assembly; a body element translatable relative to the adjuster element; a bearing element in contact with the body element, the bearing element including a bearing surface for contacting a surface of the ring gear during use; and biasing means positioned between the body element and the adjuster element for applying tension to the support unit to bias the support element into contact with a surface of the ring gear during use, wherein the adjuster element is configured to adjust the tension applied to the support unit by controlling translation of the body element, the support unit being configured such that the adjuster element and corresponding surface of the body element are visible during use.

Preferably, the biasing means is configured to apply a predetermined tension to the support unit when the support unit is mounted in the support assembly prior to use, and wherein the support unit is configured such that the corresponding surfaces of the adjuster element and the body element are coplanar when the predetermined tension is applied.

Preferably, when the support unit is mounted in the support assembly, the surface of the body element is configured to move upwardly or downwardly relative to the surface of the adjuster element to indicate that the tension applied to the support unit has been reduced.

Preferably, the corresponding surfaces comprise end faces of the adjuster element and the body element.

Preferably, the body element comprises a rod and the adjuster element comprises an open aperture through which the rod is slidably received.

Preferably, the linkage comprises a retaining means arranged to limit translation of the body element away from the adjuster element.

Preferably, the adjuster element includes an inner surface for limiting translation of the body element towards the adjuster element.

Preferably, the bearing surface is arranged to contact a lower or upper surface of the ring gear during use.

According to a second aspect of the invention, a support assembly for a yaw system of a wind turbine is provided, the support assembly comprising a support unit according to the first aspect of the invention. Preferably, the bearing assembly is a sliding bearing assembly, a ball bearing assembly or a roller bearing assembly.

According to a third aspect of the invention, there is provided a yawing system for a wind turbine, the yawing system comprising a support assembly according to the second aspect of the invention.

Preferably, the yawing system comprises: a control unit configured to determine a translation of the body element relative to the adjuster element; and issuing a maintenance control signal upon determining that the body element has been switched.

Preferably, the maintenance control signal is configured to indicate degradation of the support element if it is determined that the body element has moved away from the adjuster element, and to indicate that the biasing device needs to be replaced if it is determined that the body element has moved towards the adjuster element.

According to a fourth aspect of the invention, a wind turbine is provided comprising a yawing system according to the third aspect of the invention.

Drawings

The above and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a wind turbine for use with the present invention;

FIG. 2 illustrates an exploded view of a yaw system of the wind turbine shown in FIG. 1;

FIG. 3 is a cross-sectional assembly view of the yawing system shown in FIG. 2;

FIG. 4 is a cross-sectional view of a support unit for the yawing system shown in FIG. 2, according to an embodiment of the invention;

FIG. 5a is a cross-sectional view of the support unit of FIG. 4 installed in the yawing system of FIG. 2 and correctly tensioned;

FIG. 5b is a cross-sectional view of the support unit of FIG. 4 installed in the yawing system of FIG. 2, after degradation of the support surface;

FIG. 5c is a cross-sectional view of the support unit of FIG. 4 installed in the yawing system of FIG. 2, after failure of the belleville springs; and the number of the first and second groups,

FIG. 6 is a cross-sectional view of the support unit of FIG. 4 installed in an alternative yawing system.

In the drawings, like features are denoted by like reference numerals.

Detailed Description

The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural and logical changes may be made without departing from the scope of the present invention as defined by the following claims. Furthermore, references to "upper," "lower," and any other terms having an implied orientation in the following description are not intended to be limiting and refer only to the orientation of the feature as shown in the figures.

To provide a background for the present invention, FIG. 1 illustrates a wind turbine, generally designated 10, that includes a tower 12. The tower 12 supports a nacelle 14, and a rotor 16 is mounted to the nacelle 14. The rotor 16 is operatively coupled to a generator housed within the nacelle 14. In addition to the generator, the nacelle 14 houses various other components required for converting wind energy into electrical energy, as well as various other components required for operating, controlling, and optimizing the performance of the wind turbine 10. Rotor 16 includes a plurality of rotor blades 18 extending radially from a central hub 20. In this example, the rotor 16 includes three rotor blades 18, but it will be apparent to those skilled in the art that other configurations are possible. Wind turbine 10 also includes a yaw system (not shown) that is positioned between tower 12 and nacelle 14. The yaw system is used to rotate the nacelle 14 in a yaw motion relative to the tower 12 to orient the rotor 16 according to the wind direction.

FIG. 2 is an exploded view of an embodiment of a yaw system, generally indicated at 27. The yaw system 27 includes the main machine 22, and all mechanical and electrical components of the nacelle 14 are assembled on the main machine 22. At least one motor (not shown) is mounted on the main machine 22 and configured to drive yaw movement of the nacelle 14. This embodiment of the yaw system 27 comprises two holes 4 arranged to receive respective motors.

Yaw system 27 also includes a ring gear, generally indicated at 24, that is configured to be fixedly secured to the top of tower 12. The outer radial surface of ring gear 24 defines a toothed member 33 for interacting with gears fixed to at least one motor to enable yaw motion of host 22 relative to ring gear 24. The ring gear 24 also includes an upper circumferential bearing surface 26 (hereinafter "upper surface 26"), a lower circumferential bearing surface 28 (hereinafter "lower surface 28"), and an inner radial bearing surface 31 (hereinafter "inner surface 31"), wherein the main machine 22 rests and slides on the upper surface when undergoing yaw motion, and wherein the inner surface extends vertically between the upper surface 26 and the lower surface 28.

A plurality of skids, generally indicated at 29, are located in a radial arrangement between the main machine 22 and the ring gear 24. The skid plate 29 is fixed relative to the main machine 22 and provides a smooth, near frictionless surface that enables the main machine 22 to slide on the upper surface 26 during yaw motion. These slides 29 each comprise a horizontal slide 30 and a radial slide 32. A horizontal slide 30 to which an axial force is applied during yaw movement of the main machine 22 is positioned between the main machine 22 and the upper surface 26 of the ring gear 24. However, the radial slides 32 (on which radial forces are exerted during yaw movement of the main machine 22) are positioned between the respective bearing assemblies 23 and the inner surface 31 of the ring gear 24, wherein the bearing assemblies 23 are arranged to be fixed to the main machine 22 in a radial arrangement. In the embodiment shown in fig. 2, eight bearing assemblies 23 are arranged radially around the ring gear 24. In a preferred embodiment, the material intended for the slide out plates 30, 32 is a polymer, such as PET or PA.

FIG. 3 is a cross-sectional view of yaw system 27 when assembled. In this figure, only two bearing assemblies 23 are visible in cross-section and are shown on opposite sides of the ring gear 24. Likewise, only two horizontal slides 30 positioned between the main frame 22 and the upper surface 26 of the ring gear 24 and only vertical slides 32 positioned between the respective support assemblies 23 and the inner surface 31 of the ring gear 24 are visible and are also shown at opposite sides of the ring gear 24. Each support assembly 23 has a generally vertical first portion 1 and a horizontal second portion 2, the horizontal second portion 2 being secured to the first portion 1 and extending radially outwardly from the first portion 1. When the yaw system 27 is assembled, the first part 1 is fixed to the main machine 22 by screws 35 and is located around the inner surface 31 of the ring gear 24, adjacent the radial slide 32. The second portion 2 extends below the ring gear 24, substantially parallel to the lower surface 28 of the ring gear 24. Each second part 2 is arranged to carry a plurality of support units 5, said support units 5 serving to exert a force on the lower surface 28 of the ring gear 24 to stabilize the yaw motion of the main machine 22. Preferably, the second portion 2 of each support assembly 23 is held between four support units and six support units 5.

Fig. 4 is a cross-sectional view of an embodiment of the support unit 5 according to the invention before being mounted in the support assembly 23. The bearing unit 5 is generally cylindrical and comprises a plurality of concentrically arranged assemblies comprising a bearing element 7 in the form of a cylindrical block comprising a bearing surface 71 for contacting the lower surface 28 of the ring gear 24 during use. The support unit 5 further comprises a generally cylindrical body element 8. Depending on the orientation of the support unit 5 as shown in fig. 4, the support element 7 contacts the upper surface 87 of the body element 8 such that the support surface 71 and the upper surface 87 are in parallel alignment. The body element 8 is centrally located within the support unit 5 and comprises an upper portion 81, which defines an upper surface 87 of the body element 8, a central portion 82 and a lower stem 83. The upper portion 81 is connected in a concentric arrangement to a central portion 82 which in turn is connected to a rod 83. The central portion 82 has a diameter smaller than the diameter of the upper portion 81 so as to define a first annular surface 92 in the lower surface of the upper portion 81. Similarly, the rod 83 has a diameter smaller than that of the central portion 82 so as to define an annular contact surface 93 in the lower surface of the central portion 82.

The support unit 5 further comprises a ring adjuster element 11 at the opposite end of the support element 7. The adjuster element 11 comprises an external thread 13 on its outer radial surface for fastening the support unit 5 in the support assembly 23 together with a centrally located aperture 15 configured to slidably receive the rod 83. The adjuster element 11 further comprises an end face 25 comprising at least two tool receptacles 17 for receiving adjustment tools (not shown in the figures) and an inner surface 94 comprising a second annular surface 91.

The support unit 5 further comprises biasing means positioned between the adjuster element 11 and the upper portion 81 of the body element 8. In this embodiment of the support unit 5, the biasing means comprises a stack of annular disc springs 9 (hereinafter referred to as "spring pack 9") positioned around a central portion 82 of the body element 8 between the adjuster element 11 and an upper portion 81 thereof. In the orientation of the support unit as shown in fig. 4, the upper and lower ends of the spring pack 9 abut against the first and second annular surfaces 91, 92 to apply tension to the support unit 5, respectively, thereby urging the body element 8 and thus the support element 7 to move in translation away from the adjuster element 11.

The rod 83 of the body element 8 comprises retaining means arranged to limit the upward translation of the body element 8 with respect to the adjuster element 11. I.e. the holding means limits the translation of the body element 8 away from the adjuster element 11. In a preferred embodiment, the retaining means is a circlip 19 which is positioned around the outer radial surface of the stem 83 of the body element 8 and is configured to abut the end face 25 of the adjuster element 11 to limit the extent to which the body element 8 can be translated away from the adjuster element 11. Instead, the annular contact surface 93 is configured to abut the inner surface 94 of the adjuster element 11 so as to limit the extent to which the body element 8 can translate downwardly relative to the adjuster element 11. That is, the annular contact surface 93 of the body element 8 and the inner surface 94 of the adjuster element 11 serve to limit translation of the body element 8 towards the adjuster element 11.

Fig. 5a is an enlarged view of detail "a" shown in fig. 3 and shows the support unit 5 mounted within the support assembly 23. The second portion 2 of each bearing assembly 23 comprises a plurality of cylindrical holes 84 for receiving respective bearing units 5. Each bore 84 includes internal threads (not shown) that form an adjustable threaded connection with the external threads 13 of the support unit 5 to retain the support unit 5 within the support assembly 23.

The adjustable threaded connection allows the adjuster element 11 to be moved relative to the body element 8 within the bore 84 by rotating the adjuster element 11 about the longitudinal axis of the support unit 5. To adjust the force exerted by the bearing surface 71 on the lower surface 28 of the ring gear 24, the adjuster member 11 may be rotated clockwise or counterclockwise within the bore 84. Rotating the adjuster member 11 clockwise causes it to move upwardly relative to the body member 8 because the upward movement of the body member 8 is prevented by the contact of the bearing surface 71 with the lower surface 28. This has the effect of compressing the spring pack 9, which causes the spring pack 9 to exert a greater tension on the support unit 5, thereby increasing the force exerted by the support surface 71 on the lower surface 28 of the ring gear 24. However, rotating the adjuster element 11 counter-clockwise has the opposite effect. I.e. the adjuster element 11 is moved downwards relative to the body element 8, thereby decompressing the spring pack 9. This reduces the tension applied to the support unit 5 and thus the force exerted by the support surface 71 on the lower surface 28.

To ensure that the bearing surface 71 exerts the necessary stabilizing force on the lower surface 28 of the ring gear 24, the tension of the support unit 5 must be properly adjusted when installed in the support assembly 23 prior to use.

In the known support unit, the biasing means is configured to provide a correct or predetermined tension when the adjuster element is rotated back a predetermined amount from its uppermost position. That is, the adjuster element is rotated clockwise to its uppermost position, over-compressing the biasing means and then rotated counterclockwise away from the uppermost position by a predetermined amount, which may be, for example, a half turn. At this position, the known support unit is adjusted to the correct tension. However, the known support unit is completely accommodated within its support assembly, which means that the adjuster element can only be accessed by removing a part of the support assembly. This makes the process of accessing and adjusting the regulator elements cumbersome and time consuming.

The support unit 5 of the present invention is configured such that the adjuster element 11 and the rod 83 are visible and accessible from below the support assembly 23 when the support unit 5 is mounted in the support assembly 23. This arrangement allows for a direct adjustment of the adjuster element 11, unlike known support units.

The spring pack 9 is configured to apply a correct or predetermined tension to the support unit 5 when the adjuster element 11 is rotated until its end face 25 is substantially coplanar with the end face 21 of the rod 83, as shown in fig. 5 a. That is, the alignment of the end surfaces 21, 25 provides a visual indication that the support unit 5 is correctly tensioned to provide the necessary stabilizing force on the lower surface 28 of the ring gear 24 prior to use.

The support unit 5 may not be able to provide the necessary stabilizing force during its working life. This may be because the support element 7 has deteriorated and/or the spring pack 9 has been damaged. As a result, each support unit 5 must be monitored to determine whether the adjuster element 11 needs to be adjusted to account for degradation of the support surface 71, or whether the spring pack 9 needs to be replaced. In both cases, by checking the position of the end faces 21, 25 with respect to each other, it is possible to diagnose the type of fault without removing the support unit 5 from the support assembly 23.

Fig. 5b is a cross-sectional view of the support unit 5, wherein the support element 7 has deteriorated. As mentioned above, the spring pack 9 serves to urge the bearing surface 71 into contact with the lower surface 28 of the ring gear 24. When the support element 7 deteriorates, the spring pack 9 causes the support element 7 and the body element 8 to translate upwards with respect to the adjuster element 11. This translation due to the deterioration of the support element 7 is indicated by the end face 21 of the rod 83 which has been moved from its initial position (aligned in a coplanar arrangement with the end face 25 of the adjuster element 11) into a plane above the end face 25 of the adjuster element 11. Typically, when the wind turbine 10 is operating under normal operating conditions, the support elements 7 deteriorate at a rate of about 0.1mm per year. However, due to testing during commissioning of the wind turbine 10 and the stabilization of the individual components of the yaw system 27, the initial rate of deterioration of the support element 7 may be greater than 0.1mm per year. The translation of the body member 8 away from the adjuster member 11 has the effect of expanding the spring pack 9, which in turn reduces the tension applied to the support unit 5 together with the stabilising force on the lower surface 28 of the ring gear 24. To re-establish the correct tension on the support unit 5, the adjuster element 11 is rotated clockwise so that it moves upwardly in the bore 84 until its end face 25 is again aligned with the end face 21 of the rod 83. The distance over which the regulator element 11 moves upwards in the bore 84 to compensate for the deterioration of the support element 7 may be up to 3mm over the working life of the support unit 5.

Fig. 5c is a sectional view of the support unit 5, wherein the spring pack 9 fails, typically due to breakage of one or more annular disc springs. In the event of such a malfunction, the spring pack 9 is no longer able to provide the required tension to the support unit 5. Thus, the bearing surface 71 moves away from the lower surface 28 of the ring gear 24, and these bearing element 7 and body element 8 translate downwards relative to the adjuster element 11, as indicated by the end surface 21 of the rod 83, which has moved from its original position into a plane below the end surface 25 of the adjuster element 11.

In both cases shown in fig. 5b and 5c, the relative movement of the corresponding surfaces of the adjuster element 11 and the body element 8 provides the following visual indication: the tension applied by the support unit 5 has decreased and requires corrective action.

As mentioned above, the known support unit is completely accommodated in the support assembly. Therefore, at least a portion of the support assembly must be disassembled in order to inspect the support unit to determine whether the tension applied to the support unit has been reduced. This is labor intensive, especially when multiple support units must be inspected.

The benefit of the support unit 5 of the present invention is that the known support unit design is further improved by providing means for determining whether the tension applied to the support unit 5 is correct and, if not, what corrective action is required in situ (i.e. when it is installed in the support assembly 23). In this way, a service person can easily determine whether the support unit 5 needs to be adjusted or whether components within the support unit 5 have failed without having to disassemble any aspect of the yaw system 27.

As indicated above, the relative position of the end faces 25, 21 of the adjuster element 11 and the rod 83 provides a visual indication that the tension applied by the support unit 5 has been reduced. The relative position of the end faces 25, 21 can be assessed by eye or more accurately determined using specialized measurement tools (not shown in the figures). The measuring tool comprises a surveying instrument using, for example, a laser distance measuring instrument for measuring the offset between the end faces 25, 21. In an exemplary embodiment, the measuring tool may form part of the adjustment tool.

In one aspect of the invention, the yaw system 27 includes a control unit (not shown in the figures) operable to monitor the relative positions of the end faces 25, 21 and issue a maintenance control signal in the event that the end faces 25, 21 become misaligned as they move from their coplanar arrangement. To this end, the control unit is operatively coupled to one or more sensors configured to determine the relative position of the end faces 25, 21. The sensor may be a mechanical or electromagnetic contact or proximity sensor, or may form part of an optical or laser measurement system. When it is determined that the end faces 25, 21 are aligned, the control unit is operable to issue a signal confirming that the support unit 5 is correctly pre-tensioned. Alternatively or in addition, the adjustment means may also be operable to provide an indication that the bearing unit 5 is correctly pre-tensioned. When it is determined that the end faces 25, 21 are misaligned, the control unit issues a maintenance control signal relating to information about the position and maintenance status of the support unit 5 within the support assembly 23. For this purpose, the maintenance control signal contains information about whether the support unit 5 needs to be adjusted or whether the spring package 9 has failed and needs to be replaced. If the control unit determines that the body element 8 has moved upwards relative to the adjuster element 11, the maintenance control signal is configured to indicate a deterioration of the bearing surface 71. However, if it is determined that the body element 8 has moved downwards relative to the adjuster element 11, the maintenance control signal is configured to indicate that the spring pack 9 needs to be replaced. The control unit includes a transmitter configured to transmit the maintenance control signal to a remote server wirelessly or through a wired connection. Alternatively, the maintenance control signal is sent directly to an off-board device (e.g., a smart phone, a personal computer, etc.) belonging to the service person.

The benefit of this aspect of the invention is that the control unit automatically determines the tension and maintenance conditions of each support unit 5 in situ. In this way, the maintenance control signal is only sent to the service personnel when the carrier unit 5 needs to be replaced or adjusted. This reduces the need for maintenance personnel to periodically field inspect the yaw system 27, which can be time consuming, expensive, and labor intensive. Furthermore, if the service person is made aware of the maintenance condition of the support unit 5 in advance, it is effective to ensure maintenance access by the service person since the service person already knows the location and type of repair and/or adjustment required.

As described above, the support surface 71 of the support unit 5 is arranged to contact the lower surface 28 of the ring gear 24. However, in another embodiment, a plurality of support units 5 are arranged to contact the upper surface 26 of the ring gear 24, replacing the horizontal sliding plate 30. Fig. 6 shows a single bearing unit 5 as part of a ball bearing assembly 95 comprising an outer bearing ring 96 and a toothed inner bearing ring 24 to perform the function of the ring gear 24 from the previous example. The balls 97 of the ball bearing assembly 95 are labeled. Similar to the horizontal sliding plate 30, the bearing surface 71 of the bearing unit 5 is in contact with the upper surface 26 of the ring gear 24. Although this example application of the bearing unit 5 is shown with respect to the ball bearing assembly 95, it should be appreciated that the bearing unit 5 may also replace the horizontal slide plate 30 of the slide bearing assembly 23 previously described. The support unit 5 is secured within the bore 84 of the main machine 22, provides a connection between the main machine 22 and the ring gear 24, and functions in the same manner as the support unit 5 contacts the lower surface 28 of the ring gear 24. That is, when the support assembly 5 is fastened to the main machine 22, the end surfaces 21, 25 of the rod 83 and the adjuster element 11 are visible to indicate when the support unit 5 is correctly tensioned and whether the tension applied to the support unit 5 has been reduced.

It will be appreciated by persons skilled in the art that the present invention has been described by way of example only, and that various alternatives may be employed without departing from the scope of the invention as defined by the appended claims. For example, it has been described that the spring pack 9 is configured to apply a predetermined tension to the support unit 5 prior to use, and that the corresponding surfaces of the adjuster element 11 and the body element 8 are coplanar when the predetermined tension is applied and misaligned when the tension is reduced. In the embodiments of the invention described above, the corresponding surfaces of the adjuster element 11 and the body element 8 comprise the end faces 25, 21 of the adjuster element 11 and the body element 8. However, it will be apparent to those skilled in the art that the corresponding surfaces of the adjuster element 11 and the body element 8 may include surfaces in place of the end surfaces 25, 21, provided that these alternative surfaces are visible during use and are capable of indicating translation of the body element 8 relative to the adjuster element 11.

It will be apparent to those skilled in the art that the support unit 5 described herein is applicable to different embodiments of the yaw system 27, such as embodiments in which the gear ring 24 is rotatably connected to the nacelle 14, either directly or indirectly, as opposed to being fixedly secured to the top of the tower 12, and the motors configured to drive yaw movement of the nacelle 14 remain stationary relative to the tower 12.

Furthermore, it will be understood by a person skilled in the art that the bearing unit 5 as defined in the appended claims is not limited to use in the bearing assembly 23, 95 described herein, and that it may also be used in other types of bearing assemblies used in yawing systems, such as for example roller bearing assemblies.