Turner gear assembly for a wind turbine and method of using same

Abstract

A turner gear assembly (36) for turning a rotor (16) of a wind turbine (10) includes a turner gear (40) and a valve housing (62) or space configured to be in fluid communication with a hydraulic system. The turner gear (40) includes a motor (42), a torque converter (44), and a torque coupling element (46). The turner gear (40) further includes a brake system (60) connected to the motor (42) and having a no-slip brake mechanism (98) that prohibits the motor (42) from rotating when acted on by a torque less than a predetermined torque threshold. The brake mechanism (98) provides a consistent braking force over extended periods of time that is immune to leaks in fluid-based actuators. A turner drive system (34), which includes the turner gear assembly (36), a rotor lock (38), and a controller (80), is also disclosed for avoiding stuck rotor lock conditions. Additionally, a method of installing wind turbine blades (24) on a wind turbine (10) using the turner drive system (34) is disclosed.

Description

[0001] TURNER GEAR ASSEMBLY FOR A WIND TURBINE AND METHOD OF USING SAME

[0002] Technical Field

[0003] The invention relates generally to wind turbines, and more particularly to a turner gear assembly and a turner drive system and to a method of using the turner drive system during assembly, disassembly, and maintenance procedures.

[0004] Background

[0005] Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A horizontal-axis wind turbine includes a tower and an energy generating unit positioned atop of the tower. The energy generating unit typically includes a nacelle to house mechanical and electrical components, such as a generator, and a rotor operatively coupled to the components in the nacelle through a main shaft extending from the nacelle. The rotor, in turn, includes a central hub and a plurality of blades extending radially therefrom and configured to interact with the wind to cause rotation of the rotor. The rotor is supported on the main shaft, which is either directly or indirectly operatively coupled with the generator which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator.

[0006] During the assembly and disassembly of the wind turbine at the wind turbine site, the individual blades are typically attached or detached one at a time to blade bearings circumferentially spaced about the central hub on the energy generating unit. For example, to attach a first blade, the central hub is rotated so that a first blade bearing on the central hub is rotated to generally the nine o’clock position (or alternatively the six o’clock position or three o’clock position). In this orientation, a generally horizontally oriented blade is lifted via a lifting device, such as a crane, and then attached to the first blade bearing. After the first blade is attached to the central hub, the central hub and the first blade are rotated until a second blade bearing is generally in the nine o’clock position and the second blade is lifted and attached to the second blade bearing. Again, the central hub and the first and second blades are rotated until a third blade bearing is generally in the nine o’clock position and the third blade is lifted up and attached to the third blade bearing. These steps may generally be performed backwards to remove blades from the central hub during disassembly of the wind turbine.

[0007] Moreover, during maintenance on the wind turbine it may be necessary to detach one or more of the blades from the central hub, repair the blade on the ground or deck of a ship, depending on the location of the wind turbine, and reattach the repaired blade to the central hub. Alternatively, if damage to the wind turbine blade is too severe, it may be necessary to replace the damaged blade with a new or refurbished blade that is brought to the wind turbine site.

[0008] To facilitate rotating the rotor and thus the central hub during such operations as described above, a turner gear is often used. The turner gear may be part of the drivetrain of the wind turbine to assist with rotating the central hub while the wind turbine is not being used to generate power, such as to install or remove blades. After the blades are installed to or removed from the central hub, the turner gear may be removed from the wind turbine. The turner gear is typically coupled to a hydraulic pump of a hydraulic system of the wind turbine and further coupled, directly or indirectly, to the main shaft to which the central hub is connected. During the blade mounting or removal process, an operator operates the turner gear to turn the main shaft either clockwise or counterclockwise so as to position a particular blade bearing where needed to attach or remove a blade.

[0009] During the installation or removal of wind turbine blades, especially when the central hub is stopped at each rotational position to attach or detach a blade, it may be necessary to maintain the wind turbine rotor in a fixed position. This prevents the central hub from inadvertently rotating. Any inadvertent or unexpected movement of the central hub during such operations can result in serious harm to personnel and equipment. However, when only some of the blades are attached to the central hub, the rotor is highly unbalanced. Consequently, a high torque may be applied to the central hub during blade attachment and removal processes.

[0010] There are two systems typically used to maintain the position of the wind turbine rotor in a fixed position. The first is a brake system associated with the turner gear or alternatively the wind turbine. Many of the current brake systems include a brake mechanism (e.g., brake calipers) having fluid-based actuators for applying a brake torque on the main shaft to prevent its rotation. By way of example, the brake mechanism may include hydraulic or pneumatic actuators for applying the brake torque to the main shaft of the wind turbine. Such actuators work by providing pressurized fluid on one side of a piston to generate a pressure imbalance across the piston thereby producing the braking torque. To maintain the pressure in the actuator, the piston chamber is sealed to prevent the pressurized fluid from leaking, thereby decreasing the braking torque on the main shaft and possibly allowing the rotor to turn.

[0011] The second system typically used to maintain the position of the wind turbine rotor in a fixed position is a rotor lock. The rotor lock generally provides one or more positive stops between the rotating parts of the rotor and the non-rotating parts of the wind turbine. For example, in many cases, the non-rotating portions in the nacelle will include one or more lock pins that are activated to engage with corresponding holes or bores in the main shaft, central hub, or other portion of the rotor. Unlike many of the fluid-based brake mechanisms, rotor locks are configured such that once the lock pins are in position, maintaining pressure or force on the lock pins may be unnecessary to maintain the engaged position of the lock pins.

[0012] As one can appreciate, the attachment and removal of wind turbine blades from the central hub can take some time. This invention seeks to improve systems and methods for using the turner drive system during assembly, disassembly, and maintenance procedures.

[0013] Summary

[0014] To this end, maintaining a fluid-tight seal in a pressurized chamber can be difficult to maintain over extended periods of time. Thus, it is fairly common that hydraulic actuators and pneumatic actuators, for example, leak causing a depressurization on the one side of the piston chamber and causing the braking force and resulting braking torque to decrease over time. Depending on the aerodynamic forces on the rotor during attachment or detachment of a wind turbine blade, such as from turbulence, wind gusts, storms, etc., when the braking force drops below a threshold level, the brake system may slip thereby allowing small rotations of the central hub and rotor. Because of the rotor lock, however, these rotations due to brake slippage cannot progress to any substantial amount of rotation of the central hub and safety is maintained.

[0015] Brake slippage, however, introduces other problems during assembly, disassembly, and maintenance procedures. In this regard, the pins of the rotor lock may become stuck, preventing the rotor lock from releasing to allow the central hub to be rotated by the turner gear to a different rotational position (e.g., for attachment or removal of another blade). In a stuck rotor lock condition, an operator must determine which direction torque is being applied to the rotor lock components and operate the turner gear to rotate the central hub in the opposite direction (or the same direction) so that the rotor lock may be released. However, this process is subject to human error, and in some cases, the turner gear is operated to apply too much rotational force in the direction of the torque force, resulting in the destruction of at least the rotor lock components. Similarly, operating the turner gear to apply too much rotational force in the opposite direction of the torque force can also damage the rotor lock among other components. Either case can lead to harm to personnel working on the wind turbine. Consequently, the process to resolve a stuck rotor lock without damage can take several hours (e.g., four or five hours or more), which is costly and stacks up when attaching or detaching multiple wind turbine blades.

[0016] In view of the above, wind turbine manufacturers need a turner gear system that includes a no-slip brake mechanism that maintains the rotor in a fixed position and avoids a stuck rotor lock scenario, and a method of using a turner gear system during an assembly, disassembly, or maintenance procedure so as to avoid the rotor lock from becoming stuck.

[0017] To these and other ends, in one aspect of the invention, a turner gear assembly for turning a rotor of a wind turbine having a drivetrain is provided. The turner gear assembly includes a turner gear operably connectable to the drivetrain for turning the rotor. The turner gear includes at least one motor having an output shaft, a torque converter having an input shaft and output shaft, wherein the output shaft from the at least one motor is connected to the input shaft of the torque converter, and a torque coupling element operably connectable to the drivetrain and connected to the output shaft of the torque converter. The turner gear assembly further includes a valve housing configured to be in fluid communication with a hydraulic system and operatively connectable to the at least one motor of the turner gear, and a brake system operatively connected to the output shaft of the at least one motor. The brake system includes at least one brake mechanism having an opened position and a closed position. In the opened position, the brake mechanism is disengaged from the output shaft of the at least one motor, and in the closed position the brake mechanism is engaged with the output shaft of the at least one motor such that the output shaft of the at least one motor is prohibited from rotating when acted on by a torque less than a predetermined torque threshold.

[0018] In one embodiment, the at least one brake mechanism of the brake system may be mechanically biased toward the closed position. In other words, the brake mechanism may be a mechanical-type brake having a mechanical element for applying a braking force. For example, the brake mechanism may include one or more springs that bias the brake mechanism toward the closed position. In one embodiment, the brake system may further include a hydraulic valve configured to be in fluid communication with the hydraulic system and having a first position and a second position. When the hydraulic valve is in the first position, the brake mechanism is in fluid communication with the hydraulic system for supplying pressurized fluid to the brake mechanism, and when the hydraulic valve is in the second position, the brake mechanism is isolated from the hydraulic system and in fluid communication with a drain line for draining pressurized fluid from the brake mechanism. In one embodiment, the brake mechanism is binary in operation and switches between the opened position and the closed position at a predetermined threshold pressure in the hydraulic system. In one embodiment, the predetermined torque threshold may be greater than the torque output of the at least one motor, preferably at least two times greater than the torque output of the at least one motor, and even more preferably at least three times greater than the torque output of the at least one motor. This ensures to a high degree of confidence that the rotor will not rotate during an assembly, disassembly, or maintenance procedure. In one embodiment, the brake system may further include a hydraulic orifice disposed between the hydraulic valve and the brake mechanism to restrict the flow rate to and from the brake mechanism and thereby control the reactiveness of the brake mechanism. In one embodiment, the turner gear assembly may further include a clutch joint connecting the output shaft of the at least one motor and the input shaft of the torque converter. The clutch joint may include a connected state where the output shaft of the at least one motor and the input shaft of the torque converter are rotationally disconnected, and a disconnected state where the output shaft of the at least one motor and the input shaft of the torque converter are rotationally disjoined and may rotate independently of each other. In one embodiment, the clutch joint may include a plurality of bolts for mechanically connecting the output shaft of the at least one motor and the input shaft of the torque converter. For example, the number of bolts in the mechanical connection may be no more than five bolts and preferably no more than three bolts, thereby allowing a technician to quickly move between the connected state and the disconnected state.

[0019] In one embodiment, the turner gear assembly may include at least three motors and the brake system may include at least three brake mechanisms. In this embodiment, each of the at least three motors may be associated with a corresponding one of the at least three brake mechanisms. In one embodiment, the at least one motor and the at least one brake mechanism may share a common hydraulic system.

[0020] In another aspect of the invention, a turner drive system of a wind turbine is disclosed. The turner drive system includes a rotor lock for the wind turbine having a locked position and an unlocked position, and the turner gear assembly according to the first aspect described above connected to the drivetrain of the wind turbine. The turner drive system further includes a controller operatively coupled to the rotor lock and the turner gear assembly and configured to operate the turner drive system by rotating the rotor of the wind turbine to a first predetermined position using the turner gear assembly, moving the brake mechanism from the opened position to the closed position, and moving the rotor lock from the unlocked position to the locked position. In one embodiment, the controller may be further configured to operate the turner drive system by moving the brake mechanism from the closed position to the opened position and moving the rotor lock from the locked position to the unlocked position.

[0021] In one embodiment, the controller may be further configured to operate the turner drive system by rotating the rotor of the wind turbine to a second predetermined position using the turner gear assembly and repeating the above steps at the second predetermined position.

[0022] In one embodiment, the rotor lock, the at least one motor, and the brake system may share a common hydraulic system. In one embodiment, the turner gear assembly may be connected to a generator of the drivetrain, a gearbox output shaft of the drivetrain, or to the gearbox input shaft of the drivetrain.

[0023] In yet another aspect of the present invention, a method of installing wind turbine blades on a wind turbine is disclosed. The method includes providing a wind turbine having a rotor hub with a plurality of blade sites, the wind turbine also having a drivetrain operatively coupled to the rotor hub; providing the turner gear assembly according to the first aspect described above; connecting the turner gear assembly to the drivetrain of the wind turbine; rotating the rotor hub of the wind turbine using the turner gear assembly to position one of the plurality of blade sites in a blade handling position; moving the brake mechanism from the opened position to the closed position; attaching a wind turbine blade to the one of the plurality of blade sites in the blade handling position; and moving the brake mechanism from the closed position to the opened position.

[0024] In one embodiment, the method may further include rotating the rotor hub of the wind turbine using the turner gear assembly to position another one of the plurality of blade sites in the blade handling position and repeating steps described above.

[0025] In one embodiment, the wind turbine may include a rotor lock having a locked position and an unlocked position, and the method may further include moving the rotor lock from the unlocked position to the locked position after using the turner gear assembly to position one of the plurality of blade sites in the blade handling position, and moving the rotor lock from the locked position to the unlocked position after attaching the wind turbine blade to the one of the plurality of blade sites in the blade handling position.

[0026] In one embodiment, the method may further include moving the clutch joint from a connected state to a disconnected state during periods when it is desired to place the rotor in a freewheeling mode, such as during inclement weather.

[0027] Brief Description of the Drawings

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

[0029] Fig. 1 is a perspective view of a wind turbine having a tower and an energy generating unit.

[0030] Fig. 2 is an enlarged partial perspective view of the wind turbine of Fig. 1 , illustrating wind turbine components in the nacelle.

[0031] Fig. 3 is a partial schematic side view of the wind turbine of Figs. 1 and 2, illustrating a rotor lock system in a disengaged position to allow the central hub to be rotated.

[0032] Fig. 4 is a view similar to Fig. 3, illustrating the rotor lock system in an engaged position to prevent rotation of the central hub.

[0033] Fig. 5 is a schematic representation of a hydraulic circuit of a turner drive system having a turner gear assembly incorporating a no-slip brake system.

[0034] Fig. 6 is a partial schematic representation of the turner gear assembly illustrated in Fig. 5.

[0035] Fig. 7 is a schematic flowchart illustrating a method of installing wind turbine blades on a wind turbine using the turner drive system.

[0036] Fig. 8 is a perspective view of a clutch joint for the turner gear assembly according to an embodiment of the invention. Detailed Description

[0037] With reference to Figs. 1 and 2, a wind turbine 10 includes a tower 12, a nacelle 14 disposed at the apex of the tower 12, and a rotor 16 operatively coupled to a generator 18 via a gearbox 20 housed inside the nacelle 14. In addition to the generator 18 and gearbox 20, the nacelle 14 may house various components needed to convert wind energy into electrical energy and to operate and optimize the performance of the wind turbine 10. The tower 12 supports the load presented by the nacelle 14, rotor 16, and other wind turbine components housed inside the nacelle 14 and operates to elevate the nacelle 14 and rotor 16 to a height above ground level or sea level, as may be the case, at which air currents having lower turbulence and higher velocity are typically found.

[0038] The rotor 16 may include a central hub 22 and a plurality of blades 24 attached to the central hub 22 at locations distributed about the circumference of the central hub 22. In the representative embodiment, the rotor 16 includes three blades 24, however the number may vary. The blades 24, which project radially outward from the central hub 22, are configured to interact with passing air currents to produce rotational forces that cause the central hub 22 to spin about its longitudinal axis A1. The design, construction, and operation of the blades 24 are familiar to a person having ordinary skill in the art of wind turbine design and may include additional functional aspects to optimize performance. For example, pitch angle control of the blades 24 may be implemented by a pitch control mechanism (not shown) responsive to wind velocity to optimize power production in low wind conditions, and to feather the blades 24 if wind velocity exceeds design limitations.

[0039] The rotor 16 may be coupled to the gearbox 20 directly or as shown in Fig. 2, indirectly via a main shaft 26 extending between the hub 22 and the gearbox 20. The main shaft 26 rotates with the rotor 16 and is supported within the nacelle 14 by a main bearing support 28 which supports the weight of the rotor 16 and transfers the loads on the rotor 16 to the tower 12. The gearbox 20 transfers the rotation of the rotor 16 through a coupling to the generator 18. Wind exceeding a minimum level may activate the rotor 16, causing the rotor 16 to rotate in a direction substantially perpendicular to the wind, applying torque to the input shaft of the generator 18. The electrical power produced by the generator 18 may be supplied to a power grid (not shown) or an energy storage system (not shown) for later release to the grid as understood by a person having ordinary skill in the art. In this way, the kinetic energy of the wind may be harnessed by the wind turbine 10 for power generation.

[0040] During the assembly, disassembly, and maintenance procedures on the wind turbine 10, blades 24 may need to be removed from or attached to the central hub 22. In this context, a lifting device, such as a crane, may be used to lift and lower each blade 24 to or from the central hub 22. For such blade handling operations, the central hub 22 is selectively rotated to position a desired blade pitch bearing 30 (and blade 24 if already attached to the central hub 22) generally horizontally, typically at the nine o’clock position (or alternatively, the three o’clock position). This rotational position of a pitch bearing 30 and the central hub 22 is considered a blade handling position, where the blade 24 can be either attached to or removed from the desired pitch bearing 30 of the central hub 22. With the blade pitch bearing 30 in the desired blade handling position, the lifting device may lift or lower the blade 24, in a generally horizontal orientation, to facilitate attaching it to or removing it from the blade pitch bearing 30. The six o’clock position may be considered another blade handling position where the blade 24 may be either be attached to or removed from a respective blade pitch bearing 30 while in a generally vertical orientation.

[0041] While the wind turbine 10 is shown with three blades 24, other wind turbines 10 may have more or less than three blades 24. As used herein, the term “drivetrain,” schematically illustrated at 32 in Fig. 2, may include one or more of a rotor main shaft, a gearbox, and a generator. The rotor main shaft 26 is considered a “low-speed shaft” that turns an input shaft of the gearbox 20. The gearbox 20 has an output shaft, considered a “high-speed shaft”, that drives the generator 18. As such, the turner gear of the turner gear assembly may be coupled to the rotor main shaft 26, the high-speed shaft of the generator 18, or the rotor of the generator 18, which may be considered a continuation of the high-speed shaft of the generator 18. In this regard, the drawings are not intended to be limiting.

[0042] Rotating the central hub 22 to a blade handling position while the wind turbine 10 is not being used to generate power may be carried out using a turner drive system 34, illustrated schematically in Fig. 5. In accordance with embodiments of the present invention, the turner drive system 34 includes at least a turner gear assembly 36 and a rotor lock 38 of the wind turbine 10. In that regard, the central hub 22 is rotated using the turner gear assembly 36, which operates to rotate the main shaft 26 of the wind turbine 10, and ultimately the central hub 22. The wind turbine rotor 16 is then locked in the desired blade handling position using the rotor lock 38. The rotor lock 38 prevents inadvertent rotational movement of the central hub 22, particularly during blade handling operations. As will be described in further detail below, the turner gear assembly 36 and the rotor lock 38 of the turner drive system 34 may be connected to the same hydraulic system and thus share a common hydraulic pressure source. Alternatively, the turner gear assembly 36 and the rotor lock 38 of the turner drive system 34 may receive fluid from separate hydraulic systems (not shown).

[0043] An exemplary turner gear assembly 36 is illustrated in Fig. 2 and schematically illustrated in Figs. 5 and 6. The turner gear assembly 36 is configured to be coupled to the rotor 16 of the wind turbine 10 to apply a torque to the rotor 16 via the driveshaft 26, and / or gearbox 20, and / or generator 18 in order to rotate the rotor 16, and thus the central hub 22, to a desired blade handling position. The turner gear assembly 36 may be permanently installed within the nacelle 14 or it may be temporarily installed during periods of assembly, disassembly, and / or maintenance of the wind turbine 10, for example. In the illustrated embodiment, the turner gear assembly 36 mounts to the generator 18, as shown, and engages components of the generator 18, ultimately resulting in rotation of the central hub 22. In one embodiment, and as best illustrated in Fig. 6, the turner gear assembly 36 includes a turner gear 40 having one or more torque motors 42, such as hydraulically driven motors, with corresponding pinion gears (not shown), a torque converter 44 operatively connected to the one or more torque motors 42, and a torque coupling element 46 operatively connected to the torque converter 44 and operatively connected to the driveshaft 26, and / or gearbox 20, and / or generator 18 of the wind turbine 10.

[0044] In one embodiment, the turner gear 40 may include three torque motors 42, but the number may be more or less than this in alternative embodiments. Each of the torque motors 42 includes an output shaft 48 that is operatively connected to the torque converter 44. Torque motors are well known in the wind turbine industry and a further description of such motors will not be provided herein. The torque converter 44 generally includes an input shaft 50, a gear arrangement 52, and an output shaft 54. The input shaft 50 of the torque converter 44 is operatively connected to the output shaft 48 of the torque motors 42 and operatively connected to the gear arrangement 52. In one embodiment, the gear arrangement 52 may include a planetary gear design so as to adjust the torque provided by the motors 42 to a design value suitable for connection to different input / output shafts in the drivetrain 32, e.g., the high-speed shaft or the low-speed shaft. The torque from the gear arrangement 52 is transmitted to the output shaft 54 of the torque converter 44. Torque converters, such as planetary torque converters, are well known in the wind turbine industry and a further description will not be provided herein. The torque coupling element 46 operatively connects the torque of the output shaft 54 of the torque converter 44 to the drivetrain 32 of the wind turbine 10, such as via the high-speed shaft or the low-speed shaft. Similar to the above, such torque coupling elements 46 are well known in the wind turbine industry and a further description will not be provided herein. Additional details of a turner gear are described in EP Application No. 4127462, owned by the Assignee of the present disclosure, the contents of which are herein incorporated in their entirety.

[0045] As briefly described above, once the central hub 22 is rotated to the desired blade handling position (or another desired rotational position) using the turner gear assembly 36, the wind turbine rotor 16 may be locked in place using the rotor lock 38 to thereby prevent inadvertent or undesired rotational movement of the central hub 22. With reference to Figs. 3 and 4, the rotor lock 38 includes one or more engagement elements 56 that are movable between a disengaged or unlocked position (Fig. 3) and an engaged or locked position (Fig. 4). When the rotor lock 38 is in the unlocked position, as illustrated schematically in Fig. 3, the engagement elements 56 are withdrawn from the central hub 22 or otherwise disengaged from the rotor 16. This allows the main shaft 26 to be rotated by the turner gear assembly 36, for example, to rotate the central hub 22 about its longitudinal axis A1 . Fig. 4 schematically illustrates the rotor lock 38, and in particular the engagement elements 56 moved into the locked position to prevent rotation of the central hub 22 about its longitudinal axis A1. The engagement elements 56 may be in the form of pins, bolts, gears, or similar mechanisms capable of physically restraining rotational movement of the central hub When only some of the wind turbine blades 24 are attached to the central hub 22, as shown in Fig. 2, the central hub 22 is considered to be “unbalanced” relative to the rotation of the central hub 22. Additionally, or alternatively, uneven wind loads on the blades 24, independent of the number of blades 24 attached to the wind turbine 10, may also create an unbalanced state of the central hub 22. In either case, if the rotor 16 is locked in position with the rotor lock 38, the unbalanced state may cause the rotor 16 to move slightly, resulting in the engagement elements 56 of the rotor lock 38 becoming frictionally engaged with components of the rotor 16. In certain cases, this engagement prevents actuators intended to unlock the rotor lock 38 (i.e., actuators configured to withdraw the engagement elements 56 from engagement with the rotor 16) from moving the engagement elements 56 to the unlocked position. This is referred to as a stuck rotor lock condition. Conventionally, to free the engagement elements 56 so that they may be moved to the unlocked position, an operator would manually operate the turner gear assembly 36 to rotate the rotor 16 to free the engagement elements 56. However, as discussed above, there is a risk that the operator may inadvertently apply torque in the wrong direction and / or too much torque, increasing the binding force on the engagement elements 56 of the rotor lock 38 instead of decreasing it, for example. This can lead to damage to parts of the wind turbine 10, such as cracking of the bearings, especially considering the forces involved, particularly during an unbalanced condition of the wind turbine 10.

[0046] Considering the issues described above, the present invention provides the turner drive system 34 and a method of operating the same that ensure that the central hub 22 of the wind turbine rotor 16 does not turn during engagement of the rotor lock 38, thereby preventing the engagement elements 56 from becoming stuck in the locked position. In accordance with an aspect of the present invention, this is achieved by incorporating a no-slip brake system, generally illustrate at 60, into the turner gear assembly 36 which is configured to maintain the wind turbine rotor 16, including the central hub 22, in a fixed position over extended periods of time without a decay in braking force and without small, unintentional rotations (e.g., slip rotations) of the wind turbine rotor 16. Aspects of the brake system 60 are described in detail below.

[0047] Fig. 5 schematically illustrates an exemplary embodiment of the turner drive system 34 for carrying out methods of using the wind turbine 10 in accordance with one or more embodiments of the present invention. As shown, the turner drive system 34 includes the turner gear assembly 36, the rotor lock 38, and a valve housing 62. In particular, the turner gear assembly 36 and the rotor lock 38 are each operatively connected to a common pressure source, such as a hydraulic pump 64 and a tank 66 of a hydraulic system in the nacelle 14. In another embodiment, the turner gear assembly 36 and the rotor lock 38 may receive fluid from separate hydraulic sources. For example, the hydraulic source for the turner gear assembly 36 may be portable and brought to the wind turbine 10 to operate the turner gear assembly 36. In the embodiment shown, the pump 64 and tank 66 are installed in the nacelle 14 and may power other hydraulic systems driving components of the wind turbine 10, such as the blade pitch control system, for example. In another embodiment, a hydraulic pump may be temporarily installed in the nacelle 14 to power the torque motors 42 and the brake system 60. In the embodiment shown, the three torque motors 42 of the turner gear assembly 36 are operatively connected to the valve housing 62 which is in turn operatively connected to the hydraulic pump 64 and the tank 66. Additionally, the brake system 60 may be separately operatively connected to the hydraulic pump 64 and the tank 66. In an alternative embodiment (not shown), the brake system 60 may be operatively connected to the hydraulic pump 64 and the tank 66 through the valve housing 62.

[0048] An electric motor 68 provides power to the hydraulic pump 64 so that the hydraulic pump 64 may send hydraulic fluid (not shown) from the tank 66 to the torque motors 42 and the brake system 60 of the turner gear assembly 36 and to the rotor lock 38. In one embodiment, the hydraulic pump 64 may run at a constant speed to generate a predetermined, fixed fluid flow rate, i.e., gallons per minute (gpm) or litres per minute (Ipm) to each connected consumer. In other words, the hydraulic pump 64 will deliver a fixed fluid flow rate to at least the turner gear assembly 36 (including the brake system 60) and the rotor lock 38 when the hydraulic pump 64 runs under normal conditions.

[0049] With respect to the rotor lock 38, when the hydraulic pump 64 is running, hydraulic fluid exits the pump 64 and flows to the rotor lock 38, as indicated by directional arrows 70, to drive movement of the engagement elements 56 via hydraulically powered actuators (or motors) 72, for example. Fluid then exits the rotor lock 38 and returns to the tank 66. The flow of fluid to the rotor lock 38 may not flow through the valve housing 62, as shown, or it may be supplied to the rotor lock 38 from the valve housing 62 in an alternative embodiment (not shown). In either case, when the hydraulic pump 64 is running, fluid is pumped to both the rotor lock 38 and the turner gear assembly 36. The fluid pumped to both the rotor lock 38 and the turner gear assembly 36 may be supplied at different working pressures and flows.

[0050] With respect to the turner gear assembly 36, when the hydraulic pump 64 is running, hydraulic fluid exits the hydraulic pump 64, enters into the valve housing 62, and may pass to a three-position flow direction valve 74. The three-position flow direction valve 74 is actuatable so that the fluid may exit the valve housing 62 and circulate to the torque motors 42. After passing through the torque motors 42, the fluid flows back into the valve housing 62 and through the three-position flow direction valve 74, exits the valve housing 62, and returns to the tank 66. The three-position flow direction valve 74 may have three operational positions. The three-position flow direction valve 74 may be a type of servo-valve relying on feedback control to regulate the flow of fluid. Further, the turner gear assembly 36 may include more than one three-position flow direction valve 74, if required.

[0051] As shown in Fig. 5, the valve housing 62 may include one or more flow control valves 76, 78. The two-position flow control valves 76, 78 provide the turner gear assembly 36 with additional control over the speed at which the turner gear assembly 36 rotates the rotor 16 as well as the torque applied by the turner gear assembly 36 to rotate the rotor 16. In that regard, the two-position flow control valves 76, 78 may be set in a parallel, series, or a combination operating configuration to vary the speed at which the turner gear assembly 36 rotates the rotor 16 as well as vary the torque level applied by the turner gear assembly 36 to rotate the rotor 16.

[0052] A control unit 80 may be operatively coupled to the various components of the turner drive system 34, such as the pump 64, components of the valve housing 62 such as the three-position flow direction valve 74 and the two-position control valves 76, 78, and the rotor lock 38 to control operation of the turner drive system 34. In that regard, the turner drive system 34 may include certain sensors to facilitate control of the turner drive system 34, such as a pressure gauge 82 and a temperature gauge 84 used to monitor the pressure and temperature of the hydraulic fluid exiting the pump 64, each of which is operatively connected to the control unit 80. The turner drive system 34 may also include a torque sensor 86 and a speed sensor 88 used to monitor the torque output and speed output of the turner gear assembly 36 on the rotor 16, each of which is operatively connected to the control unit 80.

[0053] The turner drive system 34, and in particular the valve housing 62 further includes a pressure release valve 90 operatively connected to the control unit 80. The pressure release valve 90 may be utilized to allow the fluid exiting the pump 64 to return to the tank 66 should the fluid experience downstream pressure over a predetermined high- pressure threshold. In the embodiment shown, the pressure release valve 90 is in the form of an auto-compensated valve or servo valve configured to adjust its positioning to maintain a constant pressure drop across the valve to thereby ensure that a consistent, steady fluid pressure downstream of the valve to the torque motors 42. In response to pressure measurements by the pressure sensor 88, for example, the pressure release valve 90 may open more or less (i.e. , throttle) to regulate the flow of fluid, thereby controlling the pressure of the fluid being delivered to the torque motors 42. In the embodiment shown, the pressure release valve 90 regulates the pressure and flow of fluid to the turner gear assembly 36. Thus, an additional advantage of the pressure release valve 90 is that it enables steady and precise control of the torque output from the turner gear assembly 36.

[0054] When the two-position flow control valves 76, 78 are operated to place the turner gear assembly 36 in a parallel operating configuration, each torque motor 42 receives one- third of the fluid flow rate that is directed to the turner gear assembly 36 by the pump 64. This distribution ensures that each torque motor 42 generates approximately the same amount of output torque to turn the central hub 22. Since each torque motor 42 only receives one-third of the fluid flow in the parallel configuration, the torque motors 42 rotate the rotor 16 and the central hub 22 at a slower rate or speed compared to if they were receiving the full flow rate of fluid available from the pump 64. In this way, torque may be controlled to a lower level. For example, in the parallel mode configuration, the torque motors 42 may rotate the rotor 16 at only 50% of the turner gear assembly’s 36 maximum rotational speed capability. However, there is no pressure loss of the fluid supplied to each torque motor 42 in the parallel mode configuration, allowing for 100% of the maximum torque capability of the turner gear assembly 36 to be available. Finally, should one of the torque motors 42 fail or otherwise become inoperable, the other two unaffected motors may continue to function to at least place the central hub 22 in a safe position.

[0055] The pressure relief valve 90 allows for the throttling of the fluid pressure supplied to each torque motor 42 in the parallel mode configuration. This provides for a full range of torque capabilities from 0% to 100% of the maximum torque of the turner gear assembly 36 to be available. The active feedback from the auto-compensated pressure relief valve 90 allows for precise control of the fluid pressure supplied to each torque motor 42, and thus precise control of the torque applied by the turner gear assembly 36 to the rotor 16. Consequently, the torque applied by the turner gear assembly 36 to the rotor 16 may be precisely controlled.

[0056] When the two-position flow control valves 76, 78 are operated to place the turner gear assembly 36 in the series operating configuration, each torque motor 42 experiences the same fluid flow rate from the pump 64 but at a lower pressure. In particular, each torque motor 42 receives the full flow rate of fluid available from the pump 64. As a result, each torque motor 42 may rotate the rotor at 100% of the turner gear assembly’s 36 maximum rotational speed capability when in the series configuration. However, the lower pressure of the fluid delivered to each torque motor 42 in the series configuration only allows for 50% of the maximum torque capability of the turner gear assembly 36 to be available, for example. Like the parallel configuration described above, the pressure relief valve 90 may be operated to throttle the fluid pressure supplied to each torque motor 42 providing for a range of torque capabilities from 0% to 50% of the maximum torque of the turner gear assembly 36 to be available in the series configuration.

[0057] Again, with respect to the turner gear assembly 36, and more particularly to the brake system 60, the brake system 60 includes a two-position flow control valve 94, a flow orifice 96, and at least one no-slip brake mechanism 98. The two-position flow control valve 94 includes a first position that places the brake mechanism 98 in communication with a hydraulic pressure source, such as the hydraulic pump 64 in the nacelle 14, and a second position that places the brake mechanism 98 in communication with a drain line, such as a drain line to a fluid reservoir. For example, this may take the form of a drain line to the tank 66 in the nacelle 14. The control unit 80 may be operatively connected to the two-position flow control valve 94 to control the movement of the valve 94 between its first and second positions in dependence on the desired state of the brake mechanism 98, as explained in more detail below.

[0058] The at least one brake mechanism 98 is operatively connected to the output shaft 48 of the one or more torque motors 42 of the turner gear 40 for applying a braking force Fb on the output shaft 48 that restricts the rotation of the output shaft 48. In one embodiment, there may be a brake mechanism 98 for each of the torque motors 42 of the turner gear 40. Thus, in the embodiment shown, the brake system 60 may include three brake mechanisms 98 associated with respective output shafts 48 of each of the torque motors 42. Each of the brake mechanisms 98 is in fluid communication with the two-position flow control valve 94 and is capable of moving between an opened position and a closed position. In the opened position of the brake mechanism 98, the brake mechanism 98 is disengaged from the output shaft 48 of the torque motor 42, thereby allowing the output shaft 48 to rotate freely without the braking force Fb being applied thereto. In the closed position of the brake mechanism 98, the brake mechanism 98 is engaged with the output shaft 48 of the torque motor 42, thereby applying the braking force Fb thereto to restrict or prohibit the output shaft 48 from rotating. In one embodiment, for example, the brake mechanism 98 may be configured as a caliper-type brake having pads that engage the output shaft 48 in the closed position and disengage the output shaft 48 in the opened position. It should be recognized, however, that the brake mechanism 98 may have other configurations and remain within the scope of the present invention.

[0059] Unlike conventional brake systems, the brake mechanism 98 is configured such that the braking force Fb, and the resulting braking torque Tb, applied by the brake mechanism 98 is relatively constant and does not decrease or decay over an extended time period suitable for an assembly, disassembly, or maintenance procedure (e.g., on the order of hours or days, not months or years). This is achieved, for example, by using a mechanical means or element to generate the braking force Fb that is applied to the output shaft 48 of the torque motor 42. For example, the mechanical element of the braking system 98 for generating the braking force Fb on the output shaft 48 of the torque motor 42 may be one or more springs. In this embodiment, for example, the one or more springs may urge one or more brake pads into contact with the output shaft 48 of the torque motor 42. The one or more springs of the brake mechanism 98 do not depend on a sealed and pressurized fluid chamber to maintain the brake force Fb on the output shaft 48 of the torque motor 42. Thus, leaks from a hydraulic or pneumatic actuator, for example, do not vary the braking force Fb and the resulting braking torque Tb being applied by the brake mechanism 98.

[0060] In an exemplary embodiment, the brake mechanism 98 may be configured to be a normally closed system. This means that the brake mechanism 98 is normally in its closed position, i.e. , the brake mechanism 98 is engaged with the output shaft 48 of the torque motor 42 thereby applying the braking force Fb to restrict or prohibit the output shaft 48 from rotating. Thus, another force or action must be taken in order to move the brake mechanism 98 to its opened position, where the output shaft 48 of the torque motor 42 is free from the braking force Fb of the brake mechanism 98. In the embodiment shown, the hydraulic pressure source associated with the two-position flow control valve 94 may be used to move the brake mechanism 98 from its closed position to its opened position. In this regard, when the two-position flow control valve 94 is in the first position, the hydraulic pump 64 is in communication with the brake mechanism 98 and causes hydraulic fluid to flow from the pump 64, through the two- position flow control valve 94, and to a chamber of the brake mechanism 98. This causes the pressure within the chamber to increase. With continued fluid flow to the brake mechanism 98, the pressure within the chamber will reach a threshold pressure Pt at which point the brake mechanism will move from the closed position to the opened position. In this position, the brake mechanism 98 is disengaged from the output shaft 48 of the torque motor 42 and the output shaft 48 may rotate. In this regard, the brake mechanism 98 is configured as a binary system, i.e., either the full braking force Fb is being applied to the output shaft 48 of the torque motor 42 or none of the braking force Fb is being applied to the output shaft 48 of the torque motor 42 (e.g., like a step function). In other words, should the chamber in the brake mechanism 98 start to lose pressure, the braking force Fb will remain either at its full value or zero.

[0061] When it is desired to apply the brake mechanism 98 to prevent the rotor 16 from rotating, such as during an assembly, disassembly, or maintenance procedure, the two-position flow control valve 94 may be moved to the second position, where the two-way flow control valve 94 is open to the tank 66 of the hydraulic system, causing the chamber in the brake mechanism 98 to depressurize. With the loss of hydraulic pressure below the threshold pressure, the brake mechanism 98 moves to its closed position. In this position, the brake mechanism 98 is engaged with the output shaft 48 of the torque motor 42 and the output shaft 48 is prevented from rotating.

[0062] To prevent the rotor 16 from slipping during the application of the brake mechanism 98, the braking force Fb (and the resulting braking torque Tb) must be relatively large. During an assembly, disassembly, or maintenance procedure, the rotor 16 is subjected to unbalanced forces from the addition or the removal of one or more blades, aerodynamic forces from the wind including wind gusts, etc. These forces on the rotor 16 cause a back torque on the drivetrain components, including the brake mechanism 98 of the turner gear assembly 36 that is resisting the rotation of the rotor 16. If the back torque on the brake mechanism 98 from the rotor 16 exceeds the braking torque Tb provided by the braking force Fb, the brake mechanism 98 may slip and allow the rotor 16 to slightly turn. To prevent this from happening, the braking torque Tb resulting from the braking force Fb must be greater than any back torque caused by forces on the rotor 16. Depending on the type of wind turbine (e.g., number, size, and weight of blades) and wind conditions at the wind turbine site (e.g., wind speeds, wind gusts, turbulence, etc.), a predetermined torque threshold Tt may be established which the brake mechanism 98 must meet when in the closed position. In one embodiment, the torque threshold Tt may be provided in terms of the torque output on the one or more torque motors 42 provided by the turner gear assembly 36. For example, in one embodiment, the torque threshold Tt may be greater than the torque output of the at least one torque motor 42, more preferably the torque threshold Tt may be greater than about two times the torque output of the at least one torque motor 42, and even more preferably the torque threshold Tt may be greater than about three times the torque output of the at least one torque motor 42. In essence, the brake mechanism 98 is configured to tightly grip the output shaft 48 of the torque motor 42 to prevent the rotor 16 from turning in the presence of back torque. In one embodiment, for example, the brake mechanism 98 may have a torque threshold Tt between about 1 ,000 Nm and about 1 ,500 Nm (e.g., per brake). Other torque threshold values greater or less than that provided above may also be possible. In this way, during the time that the brake mechanism 98 is in its closed position, the braking torque Tb is sufficient to prevent the rotor 16 from slipping. Moreover, because the brake mechanism 98 employs a mechanical brake element, the braking torque Tb does not decay or decrease over the time which the brake mechanism 98 is expected to be engaged (i.e., in the closed position). Instead, the brake mechanism 98 is configured to provide a consistent and constant braking torque Tb during the period that the brake mechanism 98 is expected to be engaged. This will, in turn, prevent the rotor lock 38 from becoming stuck.

[0063] As noted above, the brake system 60 includes an orifice 96 disposed between the two- position flow control valve 94 and the brake mechanism 98. The orifice 96 is configured to slow the reactiveness of the brake mechanism 98 down by limiting the hydraulic flow to and from the brake mechanism 98. In other words, the orifice 96 determines the maximum hydraulic flow rate to and from the brake mechanism 98, thereby controlling the reactiveness of the brake mechanism 98.

[0064] With reference to Fig. 7, an exemplary method 100 of installing wind turbine blades 24 on the wind turbine 10 will now be described. The method 100 may be used, for example, during the initial assembly of the wind turbine 10 or during a maintenance process where one or more of the wind turbine blades 24 are being replaced. The described process will start with the turner gear assembly 36 operatively connected to the drivetrain 32 of the wind turbine 10, such as at a rear of the generator 18 in the nacelle 14 of the wind turbine 10.

[0065] In a first step 102, the turner gear assembly 36 may be activated to turn the central hub 22 of the rotor 16 such that one of the plurality of blade sites 30 is in the blade handling position, which may be, for example, the nine o’clock position, the six o’clock position, or the three o’clock position. When the selected blade site 30 is in the blade handling position, and in the next step 104 of the method 100, the brake mechanism 98 may be activated to engage with the output shafts 48 of the torque motors 42 and thereby prevent the central hub 22 of the rotor 16 from rotating. In this regard, the control unit 80 may be operatively connected to the two-way flow control valve 94 of the brake system 60 to control the movement of the valve 94 from the first position to the second position. As explained above, when the brake mechanism 98 is in the second position, the mechanical element of the brake mechanism 98, such as the spring, biases the brake mechanism 98 toward the closed position and into engagement with the output shafts 48 of the torque motors 42. The brake mechanism 98 is designed to be normally closed and therefore does not rely on hydraulic pressure (or other force that decays over time) to arrest the movement of the output shaft 48 of the torque motor 42. Therefore, the brake mechanism 98 applies a constant and consistent braking torque Tb that resists rotation of the central hub 22 of the rotor 16.

[0066] In a next step 106, the rotor lock 38 of the turner drive system 34 may be actuated so as to engage the engaging elements 56 of the rotor lock 38 with the, for example, central hub 22 of the rotor 16, thereby providing a positive lock of the rotor 16. The rotor lock 38 is operatively connected to the control unit 80 for controlling the movement of the engaging elements 56 between their locked and unlocked positions. With the rotor lock 38 engaged, in a next step 108, a wind turbine rotor blade 24 may be connected to the blade site 30 of the central hub 22 that is in the blade handling position. This typically involves the use of a crane and is well known in the wind turbine industry. Thus, a further description of this step will not be described herein.

[0067] Once the wind turbine blade 24 is connected, in a further step 110, the rotor lock 38 may be disengaged by moving the engaging pins 56 from the locked position to the unlocked position. Again, this may be controlled by the control unit 80. One benefit of the present invention is apparent at this step of the method 100. During the installation process, the wind turbine 10, and especially the wind turbine blade(s) 24 that are attached to the wind turbine are subjected to the wind and other forces that urge the rotor 16 to rotate. This causes a back torque in the drivetrain 32 of the wind turbine 10. That back torque is first resisted by the braking torque Tb of the brake mechanisms 98 of the turner gear assembly 36. Should that back torque exceed the braking torque Tb of the brake mechanisms 98, then the brake mechanism will slip and allow a “slip” rotation of the central hub 22 of the rotor 16. Should these slip rotations be significant, then the resistance to the back torque will be assisted by the positive stops provided by the rotor lock 38. As discussed above, however, reliance on the rotor lock 38 to resist the back torque on the rotor 16 during an installation procedure may cause the rotor lock 38 to become stuck, which introduces its own issues and delays. To avoid scenarios where the rotor lock 38 becomes stuck, the braking torque Tb provided by the brake mechanisms 98 is designed to be greater than and preferably significantly greater than the back torque that is to be expected during the installation procedure. The output torque of the torque motors 42 may be indicative of the expected back torque experienced by the rotor 16 during an installation procedure. Thus, for example, the braking torque Tb from the brake mechanism 98 may be designed to be greater than twice or three times the torque output of the torque motor 42. This ensures to a very high confidence level that the back torque on the rotor 16 will not exceed the braking torque Tb provided by the brake mechanisms 98 and the rotor 16 will not slip. By preventing or minimizing the slip of the rotor 16, the engagement pins 56 of the rotor lock 38 will not be impinged and a stuck rotor lock condition may be avoided. Thus, the movement of the rotor lock 38 from its locked position to its unlocked position is straightforward and takes little time.

[0068] After the rotor lock 38 is disengaged, and in a next step 112 of the method 100, the brake mechanism 98 of the turner gear assembly 36 may be disengaged from the output shafts 48 of the torque motors 42. In this regard, the two-way flow control valve 94 may be moved from its second position to its first position, such as under the control of the control unit 80. This exposes the brake mechanisms 98 to hydraulic pressure from the pump 64 of the hydraulic system. The hydraulic pressure overcomes the braking force Fb from the mechanical elements (e.g., one or more springs) and causes the brake mechanisms 98 to move to the opened position and release the output shafts 48 for rotations free from the brakes.

[0069] During installation, the process described above may have to be repeated for the attachment of multiple wind turbine blades 24. Thus, in accordance with the method 100, a decision block 114 is presented. If there are more wind turbine blades 24 to attach to the central hub 22 of the rotor 16, the method 100 may return to step 102 and repeat steps 102-112 until all of the wind turbine blades 24 (e.g., three blades 24) have been attached to the central hub 22 of the rotor 16. Moreover, while the above method 100 described an assembly procedure for a wind turbine 10, aspects of the method may be used in other procedures for wind turbines 10. In this regard, during the lifetime of the wind turbine 10, it may be necessary to replace one or more of the wind turbine blades 24. Aspects of the method 100 may be used during maintenance procedures to replace one or more of the wind turbine blades 24. Furthermore, at the end of the lifetime of the wind turbine 10, the wind turbine 10 may be disassembled. To this end, the method 100 described above may be reversed and used during the disassembly of the wind turbine 10. Thus, aspects of the invention should not be limited in use to the assembly of the wind turbine 10.

[0070] In a further feature of the present invention, assembly, disassembly, and maintenance procedures may occur over several days. During this time period, the wind turbine 10 may be subjected to severe weather and wind conditions that may cause large back torques in the drivetrain 32 of the wind turbine 10. While the turner gear assembly 36 may be capable of withstanding these back torques in the drivetrain 32, in some instances it may be better to release the brake mechanisms 98 (and rotor lock 38) and allow the rotor 16 to be in a “freewheeling” mode. For example, during the nighttime hours there typically are no technicians in or around the wind turbine 10. As safety to personnel during this time is not implicated, should a nighttime storm be forecasted or arise, it may be desirable to release the brake mechanisms 98 and place the rotor 16 in its freewheeling mode. In conventional systems, however, this could only be achieved by disconnecting the entire turner gear assembly from the drivetrain of the wind turbine, which was labour intensive and time consuming.

[0071] To overcome this deficiency, the turner gear assembly 36 according to the present invention includes a quick connect / disconnect arrangement that allows the brake mechanisms 98 to be in engagement with / disengagement from the drivetrain 32 of the wind turbine 10. Because the brake mechanisms 98 do not allow for slippage, the hold that the brake mechanisms 98 have on the drivetrain 32 must be broken at a different location. That location is referred to herein as a clutch joint 120. Fig. 8 illustrates an exemplary embodiment of the clutch joint 120. In one embodiment, the clutch joint 120 may be disposed between the brake mechanism 98 and the torque converter 44 in the turner gear assembly 36. Other locations of the clutch joint 120, however, may also be possible. In one embodiment, the clutch joint 120 may be a mechanical joint, such as a joint between the output shaft 48 of the torque motors 42 and the input shaft 50 of the torque converter 44. In one embodiment, this mechanical joint may include a bolted connection between the output shaft 48 of the torque motors and the input shaft 50 of the torque converter 44. Other mechanical connectors may also be possible and remain within the slope of the present invention.

[0072] In the normal course, a plurality of bolts 122 connect the two shafts 48, 50 such that the output torque from the torque motor 42 is transmitted to the torque converter 44. This is referred to as a connected state of the clutch joint 120. When it is desired to place the wind turbine 10 in a freewheeling mode, the brake mechanisms 98 are disconnected from the drivetrain 32. This is achieved by removing the bolts 122 at the clutch joint 120, thereby creating a “break” between the brake mechanisms 98 and the torque converter 44. This is referred to as a disconnected state of the clutch joint 120. The clutch joint 120 is designed to be easy and relatively quick to move between the connected and disconnected states. For example, the clutch joint 120 may be configured to have the fewest possible bolts 122. In this regard, the clutch joint 120 may include no more than five bolts 122 per torque motor 42, and preferably no more than three bolts 122 per torque motor 42. Thus, for a turner gear assembly 36 with three torque motors 42, the rotor 16 may be placed in the freewheeling mode by removing nine bolts for three bolts per torque motor (or fifteen bolts for five bolts per torque motor), which should take a technician just minutes to complete. In a similar manner, when it is desired to take the rotor 16 out of its freewheeling mode, such as in the morning when severe weather has passed, the bolts 122 may be replaced and the drivetrain 32 reengaged by the brake mechanism 98.

[0073] While the invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the Applicant’s general inventive concept.

Claims

CLAIMS1 . A turner gear assembly (36) for turning a rotor (16) of a wind turbine (10) having a drivetrain (32), comprising: a turner gear operably connectable to the drivetrain (32), the turner gear (40) comprising: at least one motor (42) having an output shaft (48); a torque converter (44) having an input shaft and output shaft, wherein the output shaft (48) from the at least one motor (42) is connected to the input shaft of the torque converter (44); a torque coupling element (46) operably connectable to the drivetrain (32) and connected to the output shaft of the torque converter (44), a valve housing (62) configured to be in fluid communication with a hydraulic system and operatively connectable to the at least one motor (42) of the turner gear (40); and a brake system (60) operatively connected to the output shaft (48) of the at least one motor (42), the brake system (60) comprising: at least one brake mechanism (98) having an opened position and a closed position, wherein in the opened position the brake mechanism (98) is disengaged from the output shaft (48) of the at least one motor (42), and wherein in the closed position the brake mechanism (98) is engaged with the output shaft (48) of the at least one motor (42) such that the output shaft (48) of the at least one motor (42) is prohibited from rotating when acted on by a torque less than a predetermined torque threshold (Tt).

2. The turner gear assembly (36) of claim 1 , wherein the at least one brake mechanism (98) of the brake system (60) is mechanically biased toward the closed position.

3. The turner gear assembly (36) of claim 1 or 2, wherein the brake system (60) further comprises: a hydraulic valve (94) configured to be in fluid communication with a hydraulic system and having a first position and a second position, wherein when the hydraulic valve (94) is in the first position, the brakemechanism (98) is in fluid communication with hydraulic system for supplying pressurized fluid to the brake mechanism (98), and wherein when the hydraulic valve (94) is in the second position, the brake mechanism (98) is isolated from the hydraulic system and in fluid communication with a drain line for draining pressurized fluid from the brake mechanism (98).

4. The turner gear assembly (36) of claim 3, wherein the brake mechanism (98) is binary in operation and switches between the opened position and the closed position at a predetermined threshold pressure (Pt).

5. The turner gear assembly (36) of claim 3 or 4, wherein the brake system (60) further comprises a hydraulic orifice (96) disposed between the hydraulic valve (94) and the brake mechanism (98).

6. The turner gear assembly (36) of any of the preceding claims, wherein the predetermined torque threshold (Tt) is greater than the torque output of the at least one motor (42), preferably at least two times greater than the torque output of the at least one motor (42), and even more preferably at least three times greater than the torque output of the at least one motor (42).

7. The turner gear assembly (36) of any of the preceding claims, wherein the turner gear (40) further comprises a clutch joint (120) connecting the output shaft (48) of the at least one motor (42) and the input shaft of the torque converter (44), the clutch joint (120) having: a connected state where the output shaft (48) of the at least one motor (42) and the input shaft of the torque converter (44) are rotationally joined; and a disconnected state where the output shaft (48) of the at least one motor (42) and the input shaft of the torque converter (44) are rotationally disjoined and may rotate independently of each other.

8. The turner gear assembly (36) of claim 7, wherein the clutch joint (120) comprises: a plurality of bolts (122) for mechanically connecting the output shaft (48) of the at least one motor (42) and the input shaft of the torque converter (44), wherein the number of bolts (122) in the mechanical connection is no more than five bolts (122) and preferably no more than three bolts (122).

9. The turner gear assembly (36) of any of the preceding claims, wherein the turner gear (40) includes at least three motors (42), wherein the brake system (60) includes at least three brake mechanisms (98), and wherein each of the at least three motors (42) is associated with a corresponding one of the at least three brake mechanisms (98).

10. The turner gear assembly (36) of any of the preceding claims, wherein the at least one motor (42) and the at least one brake mechanism (98) share a common hydraulic system.

11. A turner drive system (34) of a wind turbine (10), comprising: a rotor lock (38) for the wind turbine (10) having a locked position and an unlocked position; the turner gear assembly (36) according to any of claims 1 -10 connected to the drivetrain (32) of the wind turbine (10); and a controller (80) operatively coupled to the rotor lock (38) and the turner gear assembly (36) and configured to operate the turner drive system (34) as follows: a. rotating the rotor (16) of the wind turbine (10) to a first predetermined position using the turner gear assembly (36); b. moving the brake mechanism (98) from opened position to the closed position; and c. moving the rotor lock (38) from the unlocked position to the locked position.

12. The turner drive system (34) of claim 11 , wherein the controller (80) is further configured to operate the turner drive system (34) as follows: d. moving the brake mechanism (98) from the closed position to the opened position; and e. moving the rotor lock (38) from the locked position to the unlocked position.

13. The turner drive system (34) of claim 12, wherein the controller (80) is further configured to operate the turner drive system (34) as follows: rotating a rotor (16) of the wind turbine (10) to a second predetermined position using the turner gear assembly (36); and repeating steps b.-e. at the second predetermined position.

14. The turner drive system (34) of any of claims 11 -13, wherein the rotor lock (38), the at least one motor (42), and the brake system (60) share a common hydraulic system.

15. The turner drive system (34) of any of claims 11 -14, wherein the turner gear assembly (36) is coupled to a generator of the drivetrain (32), or wherein the turner gear assembly (36) is coupled to a gearbox output shaft of the drivetrain (32), or wherein the turner gear assembly (36) is coupled to the gearbox input shaft of the drivetrain (32).

16. A method of installing wind turbine blades (24) on a wind turbine (10), comprising: a. providing a wind turbine (10) having a rotor hub (22) with a plurality of blade sites (30), the wind turbine (10) also having a drivetrain (32) operatively coupled to the rotor hub (22), b. providing the turner gear assembly (36) of any of claims 1 -10; c. connecting the turner gear assembly (36) to the drivetrain (32) of the wind turbine (10); d. rotating the rotor hub (22) of the wind turbine (10) using the turner gear assembly (36) to position one of the plurality of blade sites (30) in a blade handling position; e. moving the brake mechanism (98) from the opened position to the closedposition; f. attaching a wind turbine blade (24) to the one of the plurality of blade sites (30) in the blade handling position; and g. moving the brake mechanism (98) from the closed position to the opened position.

17. The method of claim 16, further comprising: h. rotating the rotor hub (22) of the wind turbine (10) using the turner gear assembly (36) to position another one of the plurality of blade sites (30) in the blade handling position; and i. repeating steps e.-g.

18. The method of claim 16 or 17, wherein the wind turbine (10) includes a rotor lock (38) having a locked position and an unlocked position, and wherein the method further comprises: moving the rotor lock (38) from the unlocked position to the locked position after using the turner gear assembly (36) to position one of the plurality of blade sites (30) in the blade handling position; and moving the rotor lock (38) from the locked position to the unlocked position after attaching the wind turbine blade (24) to the one of the plurality of blade sites (30) in the blade handling position.

19. The method of any of claims 16-18, further comprising: moving the clutch joint (120) from a connected state to a disconnected state to place the rotor (16) of the wind turbine (10) in a freewheeling mode.

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