Patent Description:
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.

Wind turbines are typically assembled on the site where the wind turbine will operate. For example, at the site the tower is erected and an energy generating unit is place at the top of the tower. Then, the individual blades may be attached one at a time to blade bearings circumferentially spaced about the central hub on the energy generating unit. In one specific method to attach the first blade, the central hub is rotated so that a first blade bearing on the central hub is rotated to generally the three o'clock position, for example, (or alternatively the six 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 three 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 three o'clock position and the third blade is lifted up and attached to the third blade bearing. To facilitate rotating the central hub to orient the blade bearings on the central hub, a turner gear is typically used. The turner gear is configured to drive the rotor mainshaft in rotation, especially when the wind turbine is decommissioned or prior to its commissioning. The turner gear is not normally an integral part of the drivetrain of a wind turbine but may be installed and operated solely to assist with rotating a hub or rotor, for example during installation of blades to the rotor hub. Thus, after the blades are installed on the hub, the turner gear may be removed from the wind turbine. The turner gear may be powered by electric power or sometimes by hydraulic power. In the case of a hydraulically powered turner gear, hydraulic drive elements of the turner gear are typically coupled to a hydraulic pump. Such a pump may be portable along with the turner gear, and may therefore be installed to or removed from the wind turbine respectively before or after use. Typically, the turner gear may be coupled, directly or indirectly, to the main shaft to which the rotor hub is connected. During the blade mounting process, an operator may command the turner gear to turn the main shaft e.g. clockwise or counterclockwise so as to orient the hub for attachment of successive blades.

When the hub has only one or two blades attached, the rotor is considered to be in an unbalanced condition. The torque needed to turn the rotor, when it is unbalanced is higher than when the rotor is in a balanced condition, i.e., when all its blades are installed. Furthermore, a rotor comprising larger, heavier blades will require higher turning torques than with smaller, lighter blades. Also, if the wind turbine site experiences high winds during installation, this may increase the torque needed to rotate the unbalanced rotor. Thus, a turner gear must be capable of generating enough torque to rotate the rotor in an unbalanced condition. An unbalanced rotor may typically comprise a hub with only a single attached blade, or with only two attached blades.

A turner gear may comprise one or more torque motors. As mentioned, these may be electrically or hydraulically driven. Torque motors may be attached to drive, directly or indirectly, the main shaft of the wind turbine. In some cases, torque motors of a turner gear may be installed at or near a gearbox of a drivetrain, thereby to drive a gearbox shaft in rotation, which may thereby turn the rotor hub to the desired position for blade attachment. In general, when a gearbox is present in a wind turbine powertrain, the rotor is coupled to the low speed shaft of the gearbox, sometimes known as an input shaft. A turner gear may be installed to drive a high speed shaft of a gearbox, to thereby use the gearbox to increase the applied torque. A high speed gearbox shaft may also be known as an output shaft thereof.

When one or more hydraulic motors are used in a turner gear, then these are driven using a hydraulic fluid pump. By way of example, a plurality of hydraulic motors may be connected in parallel to a hydraulic pump such that each motor receives the same fluid flow and pressure, which is delivered by the hydraulic pump. The hydraulic motors are thereby run in parallel so that if one of the hydraulic motors fails, the others will remain operational to at least put the hub in a safe condition until the failed hydraulic motor is fixed. Operating the hydraulic motors in parallel allows the hydraulic motors to generate maximum torque but may limit how fast they can each turn when driven by a hydraulic pump with a fixed fluid flow rate.

A wind turbine manufacturer may connect a turner gear to a pre-installed hydraulic pump in the wind turbine, e.g. in the nacelle. A pre-installed hydraulic pump may for example be used to power other systems in the wind turbine, such as e.g. blade pitch drive elements. Alternatively, a turner gear may be associated with or may comprise one or more dedicated hydraulic pump, which may be temporarily installed in the nacelle for the sole purpose of operating the turner gear. That installed hydraulic pump may be sized to provide a fixed fluid flow rate based on the needs of a particular wind turbine. For example, a wind turbine with large, heavy wind turbine blades will require a hydraulic pump sized to generate a greater fluid flow rate compared to a wind turbine with smaller, lighter blades, which will require a smaller hydraulic pump which generates a lower fluid flow rate.

The speed at which the turner gear can turn the hub or rotor is directly related to the fluid flow rate generated by the hydraulic pump. Thus, a turner gear coupled to a hydraulic pump with one fluid flow rate may rotate the rotor <NUM> degrees in <NUM> minutes, whereas the same turner gear may take <NUM> minutes to turn a rotor <NUM> degrees when coupled to a hydraulic pump generating half the fluid flow rate. This reduced rotational rate can impact the time it takes to install all of the blades. This situation may occur if the same turner gear is utilized in association with both large or small rotors. For example, a turner gear may be used with a large wind turbine where the "installed" hydraulic pump can generate a large fluid flow rate such that the turner gear may generate a large amount of torque at a given rotation speed. That same turner gear may then be removed and thereafter used during the assembly of a rotor at a smaller wind turbine whose installed hydraulic pump may generate a fluid flow rate that is appreciably less than that of the installed hydraulic pump on the larger wind turbine. As such, that same turner gear may turn at a correspondingly lower rotational speed, even while it is otherwise capable of generating more torque than required to rotate the smaller rotor on the smaller wind turbine. Consequently, that blade assembly process may take appreciably longer, even while the turner gear is capable of generating a higher torque than is needed for turning the smaller rotor. This means that more time is taken for turning a rotor than is strictly necessary when considering the power envelope of the turner gear.

An insight underlying the present disclosure resides in the recognition that there may be needed a turner gear that can generate sufficient torque and rotational speed in one wind turbine and then be reconfigured to generate a different torque and rotational speed in a different wind turbine. In this way, a wind turbine requiring less torque may use the same turner gear at lower torque output but rotate at an increased speed, thereby saving time during installation.

<CIT> relates to a method for assembling a wind power generator, including coupling a counterweight to a first flange of a rotor hub, coupling a first wind turbine blade to a second flange of the rotor hub, and then positioning a third flange of the rotor hub in a desired position. After the step of rotating the rotor hub so as to adjust the center of gravity position of the counterweight in the circumferential direction of the rotor hub, and the step of adjusting the center of gravity position of the counterweight, the second wind turbine blade is coupled to the third flange. During the rotation, the center of gravity of the counterweight and the center of gravity of the first wind turbine blade are adjusted to be substantially symmetrical to each other with respect to the rotation axis of the rotor hub. The center of gravity of the counterweight is such that the center of gravity of the counterweight, the center of gravity of the first wind turbine blade, and the center of gravity of the second wind turbine blade are approximately the same distance from the rotation axis of the rotor hub, and they are adjusted so that they are located at approximately the same angular spacing around the circumference.

To these and other ends, a turner gear assembly for turning an unbalanced rotor of a wind turbine having a drivetrain is disclosed. The turner gear assembly includes a turner gear configured to couple to the drivetrain and having at least two motors, and a valve block operatively connectable to the turner gear and including a first flow control valve configured to be in fluid communication with a pump and with the at least two motors of the turner gear. The first flow control valve is selectively moveable between a first fluid control position and a second fluid control position. When the first flow control valve is in the first fluid control position, the at least two motors are configured to operate in parallel. When the first flow control valve is in the second fluid control position, the at least two motors are configured to operate in series. The ability to configure the valve block to operate the at least two motors in parallel, in series, or not at all (e.g., in the case of three of more motors) allows the turner gear assembly to be configured to the specific torque and rotational speed needs across a wide range of wind turbine sizes. The at least two motors may include two or more motors. Where more than two motors are provided, there may preferably be a first, and a second flow control valve. Where more than three motors are provided, there may be a first, and a second and a third flow control valve or more.

In one embodiment, the turner gear may have first, second, and third turner gear motors. In this arrangement, the first flow control valve may be configured to be in fluid communication with a pump and with first and second turner gear motors and the valve block may further include a second flow control valve configured to be in fluid communication with the pump and with the second and third turner gear motors. The second flow control valve may be selectively moveable between a first fluid control position and a second fluid control position. The first and second fluid control positions of the respective first flow control valve and the second flow control valve may be selectively configured such that the first, second, and third motors operate in parallel, operate in series, or operate in a combination of parallel and series. In one exemplary arrangement, when the first flow control valve is in its first fluid control position and the second flow control valve is in its first fluid control position, the first, second and third motors may operate in parallel. In another exemplary arrangement, when the first flow control valve is in its second fluid control position and the second flow control valve is in its second fluid control position, the first, second, and third motors may operate in series. In yet another arrangement, when the first flow control valve is in its second fluid control position and the second flow control valve is in its first fluid control position, the first and second motors may operate in series and the third motor may operate in parallel to the combination of the first and second motors. The turner gear assembly may include a control unit configured to selectively move the first flow control valve between its first and second positions, and when the turner gear assembly includes a second flow control valve, the control unit may be configured to selectively move both the first and second flow control valves between their respective first and second positions.

In another embodiment, the turner gear may have first, second, third, and fourth turner gear motors. In this arrangement, the first flow control valve is configured to be in fluid communication with the first and second motors, and the valve block includes a second flow control valve configured to be in fluid communication with the pump and with the second and third motors. The second flow control valve may be selectively moveable between a first fluid control position and a second fluid control position. The valve block may additionally include a third flow control valve configured to be in fluid communication with the pump and with the third and fourth motors. The third flow control valve may be selectively moveable between a first fluid control position and a second fluid control position. In this embodiment, the first and second fluid control positions of the respective first, second, and third flow control valves may be selectively configured such that the first, second, third, and fourth motors operate in parallel, operate in series, or operate in a combination of parallel and series. In one exemplary arrangement, when the first flow control valve is in its second fluid control position, the second flow control valve is in its first fluid control position, and the third flow control valve is in its second fluid control position, the first and second motors operate in series with each other and the third and fourth motors operate in series with each other. Still further, the turner gear may have more than four turner gear motors. In such arrangements, and in any case, it is preferred for the turner gear motors to be connected to pressurised hydraulic fluid supply via an array of flow control valves in said valve block in such a way that the turner gear motors can be driven in either a series or parallel fluid flow connection relative to other motors, preferably also in a mixed configuration of series and parallel operating turner gear motors.

The valve block may include a flow direction valve operatively connected to the pump The flow direction valve may be selectively movable between first and second positions, where the first position is configured to allow the fluid flowing from the pump to move in a first fluid flow direction through the turner gear motors, and the second position configured to allow the fluid from the pump to move in a second fluid flow direction through the turner gear motors. Accordingly, the turner gear motors are preferably configured to be bi-directional motors.

A drivetrain of a wind turbine may comprise elements including a rotor mainshaft, a mainshaft housing and a gearbox, the gearbox being drivingly coupled to the rotor mainshaft. The gearbox may comprise a low speed input shaft and a high speed output shaft. The input shaft may be operatively coupled to the rotor mainshaft. A generator may be coupled to the gearbox high speed shaft. In particular a generator may comprise a stator and a generator rotor, rotatable in relation to the stator on a generator rotor shaft. The generator rotor shaft may be coupled to the gearbox output shaft, i.e. the gearbox output shaft and the generator rotor shaft may be regarded as a high speed shaft of the drivetrain. The turner gear may be coupled to a drivetrain element of the wind turbine. In embodiments, the turner gear may be drivingly connected to a high speed shaft of the drivetrain. More particularly, the turner gear may be drivingly connected to a rotor shaft of the generator. Alternatively, the turner gear may be drivingly connected to a gearbox shaft which may preferably be a gearbox output shaft. Alternatively, in embodiments, the turner gear may be drivingly coupled to a low speed, input shaft of the gearbox, or to the blade rotor mainshaft.

The pump may in particular be a hydraulic pump or a group of hydraulic pumps. In embodiments the pump may be a part of the wind turbine. For example, the pump may be part of a blade pitch control system of the wind turbine. Alternatively, a turner gear assembly may include a pump, in particular a pump which may be temporarily installed and removed along with the turner gear, successively at one or more wind turbines.

In yet another embodiment, there is disclosed a method of operating the turner gear assembly as described above for turning an unbalanced rotor of a wind turbine. The method includes installing a turner gear at a wind turbine drivetrain by coupling the turner gear to a relevant drivetrain element, and thereafter selecting between the first fluid control position and the second fluid control position of the first flow control valve, such that when the first fluid control position is selected, the at least two motors run in parallel, and when the second fluid control position is selected, the at least two motors run in series, and operating the turner gear assembly with the first fluid control valve in the selected fluid control position.

For example, in one embodiment of the method, the turner gear may have first, second, and third motors and the first flow control valve in fluid communication with the first and second motors. A valve block of the turner gear assembly may further include a second flow control valve in fluid communication with the pump and with the second and third motors, the second flow control valve being selectively moveable between a first fluid control position and a second fluid control position. The method may further include selecting between the first fluid control position and the second fluid control position of the second flow control valve, such that the first, second, and third motors operate in parallel, operate in series, or operate in a combination of parallel and series.

In an example, a method of turning an unbalanced rotor of a wind turbine using a turner gear assembly is disclosed. The method includes providing a first wind turbine having a central hub with a plurality of blade attachment sites, the first wind turbine further having a drivetrain operatively coupled to the central hub; providing a turner gear assembly as described above; attaching the turner gear to the drivetrain of the first wind turbine and operatively connecting the valve block to the turner gear; configuring the valve block to operate the at least two turner gear motors in a first operational mode; operating a pump of the turner gear assembly to actuate the at least two motors and turn the central hub until one of the plurality of blade sites is in a blade handling position; attaching/removing a wind turbine blade to/from the blade site at the blade handling position; and repeating the operating and attaching steps until the first wind turbine has all of its wind turbine blades attached/removed to/from a respective one of the plurality of blade sites.

The method according to the example may further include removing the turner gear assembly from the first wind turbine; providing the turner gear assembly to a second wind turbine having a central hub with a plurality of blade sites; attaching the turner gear to a drivetrain of the second wind turbine and operatively connecting the valve block to the turner gear; configuring the valve block to operate in a second operational mode different from the first operational mode; operating a pump of the turner gear assembly to actuate the at least two motors and turn the central hub until one of the plurality of blade sites is in a blade handling position; attaching/removing a wind turbine blade to/from the blade site at the blade handling position; and repeating the operating and attaching steps until the second wind turbine has all of its wind turbine blades attached/removed to/from a respective one of the plurality of blade sites.

In one example, operating the pump further comprises coupling the turner gear to a hydraulic system of the wind turbine having a pump and operating the pump of the wind turbine hydraulic system to drive the turner gear motors. The hydraulic system may be the pitch control system of the wind turbine.

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.

With reference to <FIG> and <FIG>, a wind turbine <NUM> includes a tower <NUM>, a nacelle <NUM> disposed at the apex of the tower <NUM>, and a rotor <NUM> operatively coupled to a generator <NUM> via a gearbox <NUM> housed inside the nacelle <NUM>. In addition to the generator <NUM> and gearbox <NUM>, the nacelle <NUM> may house various components needed to convert wind energy into electrical energy and to operate and optimize the performance of the wind turbine <NUM>. The tower <NUM> supports the load presented by the nacelle <NUM>, rotor <NUM>, and other wind turbine components housed inside the nacelle <NUM> and operates to elevate the nacelle <NUM> and rotor <NUM> 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.

The rotor <NUM>, also known as a blade rotor <NUM>, may include a central hub <NUM>, otherwise known or referred to herein as a rotor hub <NUM> or hub <NUM>. The blade rotor <NUM> may include a plurality of blades <NUM> attached to the central hub <NUM> at locations distributed about the circumference of the central hub <NUM>. In the representative embodiment, the rotor <NUM> includes three blades <NUM>, however the number may vary. The blades <NUM>, which project radially outward from the central hub <NUM>, are configured to interact with passing air currents to produce rotational forces that cause the rotor <NUM>, including its hub <NUM>, to spin about its rotational axis. The rotational axis of the hub <NUM> and rotor <NUM> may in particular correspond to the longitudinal axis of the rotor mainshaft <NUM>. The design, construction, and operation of the blades <NUM> 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 <NUM> 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 if wind velocity exceeds design limitations.

The rotor <NUM> may be coupled to the gearbox <NUM> directly or, as shown, indirectly via a mainshaft <NUM> extending between the hub <NUM> and the gearbox <NUM>. The main shaft <NUM> rotates with the rotor <NUM> and is supported within the nacelle <NUM> by a main bearing support <NUM>, or mainshaft housing <NUM>, which supports the weight of the rotor <NUM> and transfers the rotor <NUM> loads on to the tower <NUM>, possibly via a nacelle bedframe. A gearbox <NUM> transfers the rotation of the rotor <NUM> to a generator <NUM>. This transfer of rotational motion between a gearbox <NUM> and a generator <NUM> may take place via a coupling between a gearbox output shaft and a generator rotor shaft of the generator <NUM>. Wind exceeding a minimum level may activate the rotor <NUM>, causing the rotor <NUM> to rotate in a direction substantially perpendicular to the wind, applying torque to the rotor mainshaft <NUM> and thereby also to the input shaft of the gearbox <NUM>, which in turn applies a torque to the generator rotor shaft of the generator <NUM>. The electrical power produced by the generator <NUM> 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 <NUM> for power generation.

With reference to <FIG>, the wind turbine <NUM> is shown with two blades <NUM> attached to the hub <NUM>. A lifting device <NUM>, such as a crane, is shown lifting the third blade <NUM> so a root end <NUM> of the blade <NUM> may be attached to a blade site <NUM>, such as a blade pitch-bearing on the central hub <NUM>. As shown in <FIG>, the central hub <NUM> has been rotated after the second blade <NUM> was attached so that the blade pitch-bearing <NUM> is generally at the nine o'clock position (as viewed facing the central hub <NUM>). The blade pitch-bearing <NUM> at the nine o'clock position (or alternatively in the <NUM> o'clock position) may be considered a blade handling position where the blade <NUM> may be either attached to or removed from the central hub <NUM>. With the blade pitch-bearing <NUM> in that position, the lift device <NUM> may lift the blade <NUM> in a generally horizontal orientation to facilitate attaching it to the blade pitch-bearing <NUM>. Alternatively, the central hub <NUM> may be rotated so that the blade pitch-bearing <NUM> is generally at the six o'clock position. The six o'clock position may also be considered another blade handling position where the blade <NUM> may be either attached to or removed from the central hub <NUM>. In that orientation, the lifting device <NUM> may lift the blade <NUM> in a generally vertical orientation.

While <FIG> illustrates the third blade <NUM> arranged to be attached to the blade pitch-bearing <NUM>, the first and second blades <NUM> may be attached in a similar fashion. To attach the first blade <NUM>, for example, a turner gear <NUM> (<FIG>), which may be coupled to a drivetrain, is operated to rotate the main shaft <NUM> and thereby also the central hub <NUM>. The turner gear <NUM> rotates the rotor hub <NUM> until the blade pitch-bearing <NUM> is in the desired position (three, six, or nine o'clock position) depending the orientation of the blade <NUM> when lifted. After the first blade <NUM> is attached, the turner gear <NUM> is operated to turn the rotor hub <NUM> until the next blade pitch-bearing <NUM> is in the desired position. This process is repeated until all the blades <NUM> are attached to the central hub <NUM>, making up a blade rotor <NUM>. While the wind turbine <NUM> in <FIG> is shown with three blades <NUM>, other wind turbines <NUM> may have more or less than three blades <NUM>. As used herein, the term "drivetrain," schematically illustrated at <NUM> in <FIG>, may include one or more of a rotor main shaft, a gearbox, and a generator. A drivetrain may also comprise a rotor mainshaft bearing and a rotor mainshaft housing <NUM>. A drivetrain which comprises a generator may sometimes be referred to as a powertrain. In this specification, the term "drivetrain" is used to denote a drivetrain with or without a generator, although a drivetrain <NUM> shown in the drawings includes a generator <NUM>, which may be preferred in the present context. The rotor mainshaft is considered a "low-speed shaft" that turns an input shaft of the gearbox. The gearbox has an output shaft, considered a "high-speed shaft", that drives the generator. As such, the turner gear <NUM> may be coupled on the one hand to the rotor mainshaft or the low-speed, input shaft of the gearbox, or on the other hand, the turner gear <NUM> may be coupled to the high-speed, output shaft of the gearbox, or to the rotor shaft of the generator, which may be considered a continuation of the high-speed shaft of the gearbox.

When one blade <NUM> is attached to a central hub <NUM>, the rotor <NUM> is considered to be "unbalanced", in particular when considered relative to the rotation axis of the central hub <NUM>. In that unbalanced condition, the turner gear <NUM> must generate more torque to turn the central hub <NUM> compared to when all the blades <NUM> are attached to the central hub <NUM>, which is considered a "balanced" condition of the blade rotor <NUM>.

An exemplary turner gear <NUM> is illustrated in <FIG>, <FIG> and <FIG>. The turner gear <NUM> has turner gear motors <NUM> in the form of torque motors, provided for rotationally driving a nacelle drivetrain. In the illustrated embodiment, the turner gear has three torque motors <NUM> (see numerals 58a, 58b, 58c), such as hydraulically driven motors, and each with a corresponding pinion gear <NUM> (see numerals 60a, 60b, 60c). The torque motors <NUM> may be attached to a motor frame <NUM>, which may hold the motors <NUM> in spaced, fixed relation to each other. A motor frame <NUM> may simplify the task of attaching a batch or cluster of torque motors <NUM> to a drivetrain element. A motor frame <NUM> may preferably include torque supports <NUM> that are used to secure the turner gear <NUM> to the drivetrain <NUM> using appropriate fasteners (not shown). The motor frame <NUM> may be attached to a main frame <NUM> of the turner gear <NUM> by appropriate fasteners (not shown). The illustrated main frame <NUM> is shown including a ring gear <NUM> which is a primary component of an output drive of the turner gear <NUM>. The ring gear <NUM> is driven by the torque motor pinions <NUM>. One or more spacing blocks <NUM> may help to accurately position the turner gear <NUM> at a drivetrain <NUM>. Preferably spacer blocks <NUM> may locate the motor frame <NUM> at a desired distance from a drivetrain element, to ensure engagement between the turner gear output drive and the drivetrain element to which the turner gear <NUM> is drivingly coupled. The pinion gears 60a, 60b, 60c rotatingly engage the ring gear <NUM> such that when the motors 58a, 58b, 58c operate they rotate the pinion gears 60a, 60b, 60c which rotates the ring gear <NUM>. A ring flange <NUM> may be mounted to the ring gear <NUM>. The ring flange <NUM> may also form a part of the turner gear output drive. The ring flange <NUM> may have a first and a second side. A first side thereof may be mounted to the ring gear <NUM>. A second side of the ring flange <NUM> may be drivingly connectable to an element of the drivetrain <NUM>. As illustrated in the example, the ring flange <NUM> may comprise one or more torque pins <NUM>. The torque pins may engage with an element of the drivetrain <NUM> to transmit torque from the turner gear <NUM> to the drivetrain <NUM>. In the illustrated example, the second side of the flange <NUM> may mount to the generator <NUM> such that when ring gear <NUM> rotates, the generator rotor rotates, which in turn causes the gearbox output shaft, the gearbox input shaft and the mainshaft <NUM> to rotate, thereby also rotating the rotor hub <NUM>.

Reference will now be made to exemplary embodiments shown in <FIG>. Multiple torque motors <NUM> of the turner gear <NUM> are connectable via hydraulic fluid lines to a pressurised hydraulic fluid source including a pump <NUM>. The illustrated torque motors 58a-d are hydraulic motors. In a most basic mode, hydraulic fluid flows from the pump <NUM>, via a valve block <NUM> to and from the hydraulic motors <NUM> and then back to the pump <NUM>. Hydraulic fluid flow between the pump <NUM> and the motors <NUM> may be adjusted by means of flow control valves <NUM>, <NUM>, <NUM> in the valve block <NUM>. The valve block <NUM> may comprise pump interface ports channelling hydraulic fluid between the pump <NUM> and the bock <NUM>. The valve block <NUM> may comprise torque motor interface ports 94a-d, 104a-d, channelling hydraulic fluid between the block <NUM> and each of the motors 58a-d. The pump interface ports and the motor interface ports <NUM>, <NUM> are connected by a network of hydraulic fluid lines within the valve block <NUM>. Flow control valves <NUM>, <NUM>, <NUM> in the hydraulic fluid line network in the valve block <NUM> adjust the fluid flow path through the valve block <NUM> between the pump interface ports and the motor interface ports <NUM>, <NUM>. Thereby, the flow control valves <NUM>, <NUM>, <NUM> in the hydraulic fluid line network in the valve block <NUM> adjust the fluid flow path between the pump <NUM> and the respective motors 58a-d. Each flow control valve <NUM>, <NUM>, <NUM> may be linked with hydraulic fluid lines to and from pump <NUM> interface ports in the valve block <NUM>. In addition, each fluid control valve <NUM>, <NUM>, <NUM> may be linked with motor interface ports <NUM>, <NUM> to and from more than one motor <NUM>. Each flow control valve <NUM>, <NUM>, <NUM> can be selectively adjusted between two fluid control positions, a first, parallel flow position (106b, 108b, 110b) or a second, series flow position (106a, 108a, 110a). As such a flow control valve <NUM>, <NUM>, <NUM> can be controlled to selectively place associated hydraulic motors <NUM> in a series flow connection or in a parallel flow connection.

The hydraulic pump <NUM> may be configured to run at a constant speed to generate a predetermined, fixed fluid flow rate, i.e. measurable in e.g. gallons per minute (gpm) or litres per minute (lpm). In other words, after the hydraulic pump <NUM> is installed and adjusted, the hydraulic pump <NUM> may preferably deliver a fixed fluid flow rate at a fixed pressure level when it runs under normal conditions. If the pump <NUM> were connected exclusively with a single motor <NUM>, then the motor <NUM> would exhibit a speed and a level of torque corresponding to respectively to the pump's full fluid flow output flow rate and to the pumped fluid pressure. Consequently, the effect of placing e.g. two similar motors <NUM> in a parallel fluid flow connection, would be to apply half the fluid flowing from the pump <NUM> to each motor <NUM>, at essentially the full pumped fluid pressure (ignoring minor losses e.g. due to fluid friction in the flow lines). This would generate a level of torque at each driven motor <NUM> corresponding to a full pressure amount of the fluid passing through it from the pump <NUM>. The halved fluid flow rate due to the reduced, i.e. halved, fluid flow through each motor <NUM> reduces the motor speed by half, when compared to the speed at which a single motor <NUM> would run, if all the pumped fluid were carried to and from the one motor <NUM>. Conversely, the effect of placing e.g. two similar motors <NUM> in a series fluid flow connection, would be to apply the full fluid flow rate from the pump <NUM> to each motor <NUM>, at essentially half the pumped fluid pressure. This would result in a level of torque at each driven motor <NUM> corresponding to half the full pressure amount of the fluid passing through it from the pump <NUM>. The full fluid flow rate through each motor <NUM> would maintain the motor speed at the speed at which a single motor <NUM> would run, if it were connected exclusively to the pump <NUM>. Similarly, with three motors 58a-c, as illustrated in <FIG> and <FIG>, the flow control valves <NUM>, <NUM>, <NUM> can be set such that there are either in parallel (see flow positions 106b, 108b, 110b shown in <FIG>) or in series (see flow positions 106a, 108a, 110a shown in <FIG>). Hence analogously, with three motors 58a-c placed in parallel fluid flow connection with a pump <NUM> as per the example of <FIG>, and with the pump <NUM> operating at a constant rate, each motor 58a,b,c may run at the same, full torque level as a single connected motor <NUM> would, even while only at one third of the speed. And with three motors 58a-c placed in series fluid flow connection with a pump <NUM> as per the example of <FIG>, and with the pump <NUM> operating at a constant rate, each motor 58a,b,c may run at the same, full speed as a single connected motor <NUM> would, even while only delivering one third of the torque. An alternative arrangement, not shown, might see any two motors e.g. 58a, 58b placed in parallel, and a remaining motor 58c placed in series with the two which are in parallel. This would deliver a level of speed lower than the full speed of a single motor <NUM> and higher than the one-third speed level of three motors <NUM> placed in parallel. In other words, it would deliver an intermediate level of performance in respect of both speed and torque, between a complete parallel arrangement and a complete series arrangement of the motors <NUM>.

A control unit <NUM> associated with the valve block <NUM> may allow automated control of the flow control valves <NUM>, <NUM>, <NUM> in the valve block <NUM>. For example, a user interface associated with the control unit <NUM> may be operable by an operator to select the settings of the flow control valves <NUM>, <NUM>, <NUM>. Alternatively, the control unit may be associated with a computer or wireless network allowing software interaction with the flow control valves <NUM>, <NUM>, <NUM> and thereby of the motor output characteristics of the turner gear assembly <NUM>.

In embodiments, a flow control body <NUM> (see numerals 76a, 76b, 76c) may optionally be coupled, respectively, to each motor 58a-c. A flow control body <NUM>, described further below, allows hydraulic fluid lines to be connected to a motor <NUM> to supply pressurized hydraulic fluid thereto. A flow control body <NUM> may further include fluid flow management elements described further below, for managing hydraulic fluid to and away from a motor <NUM>. A flow control body <NUM> may in particular comprise a hydraulic fluid inflow and outflow connection for allowing hydraulic fluid flow connection to and from a hydraulic fluid pumping arrangement. When installing a turner gear assembly <NUM> at a drivetrain of a nacelle, it may be preferred to first operatively connect the turner gear <NUM> to a drivetrain element, as mentioned above, and subsequently to connect a hydraulic fluid pumping arrangement of the turner gear assembly <NUM> to the turner gear <NUM>, e.g. via pipes or hoses, as described below.

<FIG> schematically illustrate exemplary embodiments of a turner gear assembly <NUM> which collectively includes the turner gear <NUM> and a hydraulic fluid pumping arrangement in the form of a valve block or housing <NUM>, associated with a pump <NUM> and a control unit <NUM>. The turner gear <NUM> comprises motors <NUM> (see numerals 58a,b,c,d), each of which may be associated with an optional flow control body <NUM>. The turner gear <NUM> is operatively connectable to a hydraulic fluid pumping arrangement including a valve block <NUM>, which is in turn operatively connected to a hydraulic pump <NUM> associated with a hydraulic fluid tank <NUM>. A pump motor <NUM> drives the hydraulic pump <NUM> so the hydraulic pump <NUM> may send hydraulic fluid (not shown) from the tank <NUM>, through the valve block <NUM>, and to the turner gear <NUM> and back again in a fluid flow circuit. The term "pump" may be used herein to refer collectively to a pump and a pump motor. Each turner gear motor <NUM> may be connectable to a valve block <NUM> via motor interface ports <NUM>, <NUM>. Optionally, each turner gear motor <NUM> may be associated with a respective flow control body <NUM> (see numerals 76a-d) which in turn is connectable in hydraulic fluid flow connection with the valve block <NUM> which controls hydraulic fluid flow to the motors <NUM> (see numerals 58a-d). The hydraulic fluid flow connection between a motor 58a-d and a said valve block <NUM> may comprise an inflow and an outflow port <NUM>, <NUM>. Inflow and outflow may be interchangeable in the context of reversing fluid flow direction <NUM>, <NUM> and thereby reversing the drive direction of the turner gear motors <NUM>. For example, a flow control body 76a-d associated with a respective motor 58a-d may be removably connectable to a valve block <NUM> associated with a pump <NUM> via inflow and outflow motor interface ports <NUM>, <NUM>. In particular, a respective motor 58a-d may be removably connectable to a valve block <NUM> via one or more quick-disconnect couplings <NUM>, <NUM> on fluid lines in communication with said motor interface ports <NUM>, <NUM>. There may be provided a pair of quick-disconnect couplings 102a, 96a; 102b, 96b; 102c, 96c; 102d, 96d for respective pairs of motor interface ports <NUM>, <NUM> (see numerals 94a-d, 104a-d) to and from a motor <NUM>. For ease of connection and disconnection between a valve block <NUM> and a motor <NUM>, fluid inflow and outflow lines to and from the motor interface ports <NUM>, <NUM> at the valve block <NUM> may include lengths of flexible hose. An inflow and outflow line in the form of a flexible hose combined with a quick disconnect coupling <NUM>, <NUM> may facilitate or speed up the temporary installation or removal of a turner gear assembly <NUM> at a nacelle drivetrain.

The valve block <NUM> preferably includes one or more fluid flow control valves <NUM>, <NUM>, <NUM> for selectably controlling fluid flow between the pump <NUM> and the motors <NUM>. In particular, each, any or all of fluid flow control valves 106a-d, 108a-d, 110a-d in the valve block <NUM> associated with a pump <NUM> may be switched to selectably place associated turner gear motors 58a-d in parallel or in series fluid-flow relation relative to the pump <NUM>. Optionally, all the motors 58a-d may thereby be placed in parallel connection such as in <FIG> or <FIG>, or all the motors 58a-d may be placed in series connection such as in <FIG>, or some of the motors <NUM> may be placed in series connection even while others are placed in parallel connection. Additionally, the valve block <NUM> may comprise a flow-direction valve <NUM> interposed between pump ports at the valve block <NUM> and the flow control valves <NUM>, <NUM>, <NUM>. Optionally, a fluid filter <NUM> may be provided on the fluid line between the pump <NUM> and the valve block <NUM>, preferably along a portion of said line which is a fluid outflow line in relation to the pump <NUM>. The flow direction valve <NUM> may be actuated so the fluid exits the valve block <NUM> and circulates to the motors <NUM> in an outbound first fluid flow direction, as represented by arrow <NUM>. After passing through the motors <NUM>, the fluid flow returns into the valve block <NUM> and through the flow direction valve <NUM> as in a return fluid flow direction, represented by arrow <NUM>. Thereafter, it exits the valve block <NUM>, and returns to the tank <NUM>. The flow direction valve <NUM> may have two operational positions, 88a, 88c, each of which corresponds to a respective forward or reverse direction of the turner gear motors 58a-d. The flow-direction valve <NUM> may be a three-position flow-direction valve <NUM>, as illustrated. Accordingly, the flow-direction valve may optionally also include a third position 88b, described below. In <FIG>, the fluid is shown flowing through a first direction fluid flow position 88c of the flow-direction valve <NUM>. The fluid flow <NUM> then flows towards the motors 58a-d as represented by arrows 90a, 90b, 90c, 90d. The fluid to and from the motors <NUM> may flow through fluid connection lines <NUM>, <NUM> (see numerals 94a, 94b, 94c, 94d), which may be a flexible hose, to a respective fluid control body 76a-d of a respective motor 58a-d.

The fluid exits motors <NUM> and returns to the valve block <NUM> via a fluid connection line and an interface port <NUM>, <NUM>, depending on the momentary fluid flow direction i.e. depending on which direction the motors <NUM> are turning in. In <FIG>, fluid returns in a direction <NUM> from a motor <NUM> to a valve block <NUM> via fluid connection line <NUM> and quick disconnect coupling <NUM>. Additional optional elements in a turner gear assembly may include a hose rupture valve 100a, 100b, 100c, (inside a flow control body <NUM>). This feature, along with associated check valves 98a-c,<NUM>00a-c may automatically disable a fluid connection to the motor interface ports <NUM>, <NUM> at a valve block <NUM>, in case fluid flow lines between the motor <NUM> and the valve block are breached, e.g. in case a hydraulic fluid connection hose or quick-disconnector <NUM>, <NUM> between the valve block <NUM> and a motor <NUM> is or becomes unseated or is breached in some way. The fluid from motors 58a-d may pass through flow control valves <NUM>, <NUM>, <NUM> having positions 106a, 106b, 108a, 108b, or 110a, 110b respectively. As illustrated in <FIG>, the flow control valves <NUM>, <NUM> aretwo-position flow control valves and are in positions 106b, 108b, respectively. The fluid from motor 58c flows directly back to flow direction valve <NUM>.

The quick disconnect couplings 96a-d and quick disconnect couplings 102a-d permit the valve block <NUM> to be readily connected to and disconnected from the motors <NUM>, and thus the turner gear <NUM>. It will be appreciated that the valve block <NUM> may also be readily connected to and disconnected from the pump <NUM> and tank <NUM>. As such, both the turner gear <NUM> and the valve block <NUM> may be temporarily installed in one wind turbine during the blade installation process and then removed and temporarily installed in a different wind turbine for another blade installation process.

With the flow control valves <NUM>, <NUM> set in parallel connection positions 106b, 108b as illustrated in <FIG>, the three motors 58ac are considered to be operating in parallel. When all motors 58a-d operate in parallel that may be called a "straight" mode of operation. Another "straight" mode of operation is when all three motors 58a-d operate in series, which will be discussed in more detail below. When some (but not all) of the motors <NUM> operate in parallel or series, then that may be called a "mixed" mode of operation. For example, looking at the arrangement of <FIG>, in the straight parallel configuration, each motor 58a-c receives one-third of the fluid flow rate generated by the pump <NUM> so that each motor 58a-c generates approximately the same amount of output torque which may be used to turn the central hub <NUM>. Should one of the motors 58a-c fail or if a corresponding hose fails and cannot deliver fluid to one of the motors 58a-c, then the other two unaffected motors <NUM> may continue to function or at least put the central hub <NUM> in a safe position. The fluid Ifow rate to each motor 58a will be one third the fluid flow rate from the pump <NUM> and thereby the motor speed will correspond to one third the maximum speed of the motors <NUM> were placed in series.

<FIG> illustrates the fluid flow circulating in a first fluid flow direction as illustrated by the direction of arrows <NUM>, <NUM>. To change (reverse) the fluid flow to a second fluid flow direction, the flow direction valve <NUM> may be moved to second fluid flow direction position 88a. With the flow direction valve <NUM> in its second position 88a, the outbound fluid flow travels to the opposite side of the motors 58a-c so that they turn in the opposite direction. Alternatively, and still as illustrated, if the flow direction valve <NUM> has an optional third position 88b, called an open center, then with the flow direction valve in its third position, the fluid from the pump <NUM> returns to the tank <NUM> and does not flow to the motors <NUM>, so they do not turn. Third position 88b thereby allows the pump <NUM> to remain operational, but without sending fluid to any of the motors <NUM>.

Control unit <NUM> may be operatively coupled to the various components illustrated in <FIG>, such as pump <NUM>, flow direction valve <NUM>, and flow control valves <NUM>, <NUM>, <NUM> so that an operator may change their respective operations or positions as necessitated by the blade assembly process. A pressure gauge <NUM> and a temperature gauge <NUM> may be used to monitor the pressure and temperature of the hydraulic fluid exiting the pump <NUM>. A pressure release valve <NUM> may be utilized to allow the fluid exiting the pump <NUM> to return to the tank <NUM> should the fluid experience downstream pressure over a predetermined high pressure threshold. A filter <NUM> may be positioned on a hydraulic fluid line in the valve block <NUM>, in particular between a pump interface port and a flow direction valve <NUM>. An additional fluid filter <NUM> with a bypass check valve <NUM> may be used to filter the fluid returning to the tank <NUM>. A check valve maybe positioned just prior to the tank <NUM> to prevent fluid in the various lines from draining back into the tank <NUM> when the pump <NUM> is shut off.

<FIG> shows the same schematic layout shown in <FIG>, but the flow control valves <NUM>, <NUM> are placed in series connection positions 106a, 108a, respectively. In this configuration, the motors 58a, 58b, 58c are considered to be operating in series. As such, each motor 58a, 58b, 58c experiences the same fluid flow rate from the pump <NUM> but at a lower pressure. Compared to the configuration in <FIG>, the motors 58a, 58b, 58c will rotate three times faster, but their torque output will be decreased to one-third each. With the two-position flow control valves <NUM>, <NUM> in positions 106a, 108a, the fluid leaving motor 58a is redirected by two-position flow control valve <NUM> so that it flows next to motor 58b as represented by arrow <NUM>. Similarly, the fluid leaving motor 58b is redirected by two-position valve <NUM> so that it flows next to motor 58c as represented by arrow <NUM>. Thus, a single stream of fluid flows through the three motors 58a, 58b, 58c before that fluid returns to the tank <NUM> as represented by arrow <NUM>. Similar to the above, the direction of the fluid flow may be changed (reversed) by moving the three-position flow direction valve <NUM> from position 88c to position 88a.

If the blade assembly process requires additional torque beyond what the configuration in <FIG> can generate, two-position valve <NUM> may for example be switched to parallel position 108b so that only motors 58a, 58b operate in series. In this configuration the fluid flow generated by the pump <NUM> is divided equally between motors 58a, 58b and motor 58c such that motors 58a, 58b generate less torque than motor 58c, but they each operate at the same speed. In this configuration, the overall torque output is greater than the configuration in <FIG> (all motors in series), but the rotational speed is less. In yet another configuration, motor 58c could be disconnected altogether, such as by disconnecting the quick disconnect 96c so that no fluid flows to motor 58c and only motors 58a, 58b operate in series. Thus, an operator may configure the different two-way flow control valves <NUM>, <NUM> and/or disconnect a particular motor 58a-58c to achieve a required output torque or a desired rotational speed, depending of the requirements of the particular blade assembly. Alternatively, one or more shutoff valves (not shown) may be used to specifically control the fluid flow to the individual motors 58a, 58b, 58c so that each motor 58a, 58b, 58c may be selectively shutoff (or turned on) to meet the torque requirements during the blade installation process.

<FIG> schematically illustrates a similar layout shown in <FIG>, but with an additional motor 58d with corresponding components of flow control body 76d, quick disconnect couplings 96d, 102d, check valves 98d, 112d, hose rupture valve 100d, 114d. The motor 58d is connected to motor interface ports 94d, 104d at the valve block <NUM>. To accommodate operatively connecting the motor 58d to the pump <NUM>, the valve block <NUM> may include an additional flow control valve <NUM> which may be a two-position valve with a respective positions 110a for a series connection and a position 110b for a parallel connection. By manipulating the flow control valve <NUM>, the motors 58c, 58d may thereby be run in parallel or series as dictated by the blade assembly process. It will be appreciated that additional motors may be added to the turner gear <NUM> to increase the torque output of the turner gear as torque requirements increase. Similarly, a corresponding flow control valve may be added to the valve block <NUM> for each additional motor so that each additional motor may be run in parallel or in series with the other motors in the turner gear <NUM>. In <FIG>, the flow control valves <NUM>, <NUM>, <NUM> may be switched between series connection and parallel connection positions 106a, 106b, 108a, 108b, 110a, 110b to put some or all of the motors 58a-58d in series so that varying amounts of output torque may be produced by the turner gear <NUM>. Again, just like in the three-motor configuration of <FIG> and <FIG>, an operator may configure the different flow control valves <NUM>, <NUM>, <NUM> via controller <NUM> and/or disconnect a particular motor 58a-58d to achieve a required output torque or a desired rotational speed, depending of the torque requirements of the particular blade assembly.

In one advantageous aspect of the invention, a "standardized" turner gear assembly may be used on different wind turbines having different sizes and different torque requirements. By design, the standardized turner gear may be used during the blade installation process on respective large, medium, and small wind turbines, despite the possibility that the torque requirements may vary widely for each installation. In addition, by using a standardized turner gear assembly, the installer does not have to be concerned with using a turner gear that is not compatible with either the structure (e.g., the gearbox or generator) or the torque requirements of the wind turbine. By manipulating the various valves in the valve block, the installer may configure the turner gear <NUM> to achieve a sufficient amount of torque without sacrificing rotational speed.

The flexibility of the turner gear assembly as disclosed herein also allows the installer to configure the turner gear to compensate for wind conditions at the work site. In this regard, wind conditions during the wind blade installation process may increase the torque requirements placed upon the turner gear e.g. by adding increased wind resistance against a turning motion of a blade rotor. To address the wind loading, the turner gear may be designed to produce not only the torque required to turn the unbalanced rotor, but also the torque required to overcome wind loading at the work site. Thus, where low wind conditions are present during the blade installation process, the turner gear assembly may be configured to generate a lower amount of torque, which may allow the turner gear to turn faster. In contrast, if moderate to high wind conditions are present at the work site, the turner gear assembly may be configured to produce additional torque, but at a slower rotational speed. Thus, a single turner gear assembly may be adapted for use on a wide range of wind turbines during a wide range of wind conditions. By adjusting the settings of the turner gear assembly for the specific wind turbine and installation (and conditions), a balance between torque requirements and rotational speed of the central hub may be achieved. A valve block at a turner gear assembly may be integral with the turner gear motors or separably connectable thereto.

Claim 1:
A turner gear assembly (<NUM>) for turning an unbalanced rotor of a wind turbine having a drivetrain, comprising:
a turner gear (<NUM>) configured to couple to a said drivetrain and having at least two motors (58a, 58b); and
a valve block (<NUM>) operatively connectable to the turner gear (<NUM>) and including a first flow control valve (<NUM>) configured to be in fluid communication with a pump (<NUM>) and with the at least two motors (58a, 58b) of the turner gear (<NUM>), characterized in that the first flow control valve (<NUM>) is selectively moveable between a first fluid control position (106b) and a second fluid control position (106a), and
when the first flow control valve (<NUM>) is in the first fluid control position (106b), the at least two motors (58a, 58b) operate in parallel, and when the first flow control valve (<NUM>) is in the second fluid control position (106a), the at least two motors (58a, 58b) operate in series.