Patent Description:
In wind turbine design, it is necessary to size the connecting structure of the main drive shaft appropriately to the connecting structure of the rotor hub. For example, a relatively small diameter main drive shaft may be appropriately sized relative to a particular rotor hub. If it is desired to attach a different sized main drive shaft to the same rotor hub, an adapter might be used between the main shaft and the rotor hub. This adapter increases complexity and costs and, therefore, is undesirable.

It is also sometimes necessary to lock the rotor of a wind turbine against rotation when the wind turbine is not in use, such as during maintenance or at other downtimes. For this purpose, wind turbines have included rotor braking and locking systems. The braking system is designed to stop the rotor after the rotor has been slowed almost to a stop by the pitch of the blades. The locking system then locks the rotor against any rotation. Locking systems typically utilize locking members, such as pins, that move between locking and unlocking positions in either an axial or a radial direction relative to the direction of rotation of the rotor. The axial direction is parallel to the lengthwise axis of the wind turbine main shaft, while the radial direction is perpendicular to the lengthwise axis of the main shaft. The pin is moved into and out of engagement with a rotatable ring-like structure that is fixed for rotation with both the main shaft and the rotor hub. The present invention relates to those systems using one or more pins moving axially or parallel to the main shaft and the axis of rotation of the rotor rather than moving radially or perpendicular to the main shaft and axis of rotation. The components of the rotor lock systems are usually large cast parts formed in one large piece. The main component is often a cast locking ring having a plurality of closed perimeter recesses that selectively receive rotor locking pins. The recesses may be blind bores or through bores. The locking ring is fixed generally at a location between the main shaft and the rotor hub and rotates with the rotor hub and main shaft when the wind turbine is in operation. When it is desired to lock the rotor hub against rotation, one or more pins are moved into one or more of the respective recesses in the locking ring. The extended pin or pins prevent the locking ring, and therefore both the rotor hub and the main shaft, from rotating. In addition to the rotor locking elements, the locking ring also typically includes fastener holes used to receive bolts for connecting the main shaft to the rotor hub. Design challenges are presented by the inclusion of both rotor locking elements and fastener holes on rotor locking rings. <CIT>, <CIT> and <CIT> disclose rotor locking rings known from the prior art.

It would be desirable to provide apparatus and methods for rotor lock systems and for main shaft/rotor hub connections that address the various drawbacks and challenges associated with current technology. Specifically, it would be desirable to provide manners in which the connections made between a main drive shaft and a rotor hub are more modular thereby saving costs in various manners. In addition, it would be desirable to increase efficiency in the use of space on a locking ring for configuring rotor locking elements and fastener holes.

The present invention generally provides a wind turbine according to claim <NUM>. The wind turbine comprising a main shaft, a rotor hub, a plurality of blades coupled to the rotor hub and a rotor locking disc. The main shaft includes a front end, and the front end includes a first connecting structure. The rotor hub includes a second connecting structure. The first connecting structure of the main shaft is fixed to the second connecting structure of the rotor hub. The rotor locking disc is carried on the main shaft and includes a peripheral region and a plurality of rotor locking elements in the peripheral region for receiving one or more rotor locking pins that are configured to move in an axial direction relative to the lengthwise axis of the main shaft. The first connecting structure further comprises at least first and second sets of fastener holes in the peripheral region of the rotor locking disc. The first set of fastener holes is located at a position radially inward of the rotor locking elements and the second set of fastener holes is located between adjacent rotor locking elements. The first and/or second set of fastener holes are used to receive fasteners to secure the main shaft to the rotor hub. In this embodiment, the first and second sets of fastener holes, as well as the corresponding sets of fasteners, may be of the same diameter or of different diameter. In addition, the rotor locking elements may be of any desired configuration or design, such as recesses of any suitable shape.

The invention may alternatively or additionally include further features and/or components. For example, a third set of fastener holes may be located in the peripheral region of the rotor locking disc radially outwards of the second set of fastener holes. In this embodiment, both the second and third sets of fastener holes are located between adjacent rotor locking elements. At least one set of the two or three sets of fastener holes may be of different diameter than another set of the fastener holes. The set or sets of fastener holes located between the rotor locking elements may be of a smaller diameter than the first set of fastener holes located at a radially inward position relative to the rotor locking elements. The rotor locking elements may further comprise open perimeter recesses in which the perimeters of the recesses open to an outer circumference of the rotor locking disc. Alternatively, these rotor locking elements may be comprised of complete or continuous closed perimeter throughholes as in conventional technology. The rotor locking disc may be integrated with the main shaft, or may be comprised of at least one component separate from the main shaft proximate or near the front end of the main shaft and affixed to the main shaft with a plurality of fasteners. Each of the plurality of recesses may be generally U-shaped.

In a non-claimed aspect, it is further foreseen a wind turbine comprising a main shaft, a rotor hub, and a plurality of blades coupled to the rotor hub. The main shaft includes a front end and the front end has a first connecting structure. The rotor hub includes a second connecting structure. The first connecting structure of the main shaft is fixed to the second connecting structure of the rotor hub to allow these two components to rotate together. The first connecting structure comprises at least first and second sets of fastener holes. The first set of fastener holes comprises holes of a larger diameter than the fastener holes of the second set.

Additional aspects may include a third set of fastener holes radially outwards of the second set of fastener holes, wherein both the second and third sets of fastener holes are comprised of holes having smaller diameters than the fastener holes of the first set. The first and second sets of fastener holes may be located on a flange integrated onto the front end of the main shaft. A rotor locking disc may be carried on the main shaft, wherein the first and second sets of fastener holes are located on the rotor locking disc. The rotor locking disc may be either integrated onto the main shaft or affixed as a separate component on the main shaft.

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.

Referring first to <FIG>, a wind turbine <NUM> is shown and is constructed with a tower <NUM>, a nacelle <NUM>, and a rotor <NUM> coupled for rotation relative to the nacelle <NUM>. The rotor <NUM> generally comprises a rotor hub <NUM> and three turbine blades <NUM> fixed for rotation with the rotor hub <NUM>. As shown, the tower <NUM> includes a base <NUM> fixed to a support surface <NUM> which may, for example, be a foundation in the ground or any other suitable support surface including a platform at sea.

Referring now to <FIG>, a first illustrative embodiment is shown. At times the rotor <NUM> must be fixed against any rotation. For example, these time periods may include maintenance periods or other times during which the wind turbine <NUM> is not in use. For this purpose, the wind turbine <NUM> includes a braking system and control (not shown) which will be used to slow and then stop the rotor <NUM> from rotating. The control will be used to activate a rotor lock system that comprises a plurality of rotor locking pins <NUM> engageable and disengageable with a rotor locking disc <NUM> as further described below. The wind turbine <NUM> generally includes a main shaft <NUM> which is coupled to a generator directly or through other drive components (not shown). The main shaft <NUM> further includes a front end 34a. The front end 34a includes a first connecting structure <NUM>. The rotor hub <NUM> includes a second connecting structure <NUM> configured to mate with the first connecting structure <NUM> on the front end 34a of the main shaft <NUM>. These connecting structures <NUM>, <NUM> are fixed rigidly together using one or more sets of threaded bolts 39a, 39b, 39c extending through respective holes 38a, 38b, 38c of the flange <NUM> and into large holes <NUM> and/or smaller holes (not shown) provided in the rotor hub <NUM> as will be described further below. As shown, the rotor locking disc <NUM> is carried on the main shaft <NUM> proximate the front end 34a. This may be accomplished in several different manners. For example, the disc <NUM> may be comprised of one or more separate components sandwiched or located between or adjacent the flange <NUM> and the connecting structure <NUM> of the rotor hub <NUM> and thereby rigidly affixed between these two components using the same bolts 39a, 39b, 39c as used to connect the flange <NUM> to the rotor hub <NUM>. Alternatively, the rotor locking disc <NUM> may be integrated onto an area proximate the front end 34a of the main shaft <NUM>, such as by casting or otherwise forming the rotor locking disc <NUM> with the main shaft <NUM>. One advantage of having the rotor locking disc <NUM> comprised of at least one separate component is that if the rotor locking system somehow damages the disc <NUM>, the disc may be replaced and/or repaired without having to remove and replace the entire main shaft <NUM>.

As further shown in <FIG>, the rotor locking disc <NUM> has an outer generally circular circumference 32a and a plurality of rotor locking elements in the form of recesses <NUM> having openings 50a on their perimeters that communicate with the outer circumference 32a. In other embodiments, the rotor locking elements <NUM> may comprise any other configurations, such as conventional circular or other continuous or closed perimeter recesses. The recesses may be complete through bores or blind bores. At least one rotor locking pin <NUM> is movable in an axial direction parallel to the lengthwise axis of the main shaft <NUM>. The pin <NUM> moves between a disengaged position relative to at least one of the recesses <NUM> and an engaged position at least partially located in one of the recesses <NUM> for locking the rotor hub <NUM> against rotation. The recesses <NUM> are shown as partially circular in shape and the pins <NUM> have a complementary cylindrical shape for closely extending at least partially into an aligned recess <NUM>. Other shapes may be used instead. Two rotor locking pins <NUM>, for example, may be located at the three o'clock and nine o'clock positions relative to the disc <NUM> and may be driven along their respective axes by suitable drive components (not shown) between extended and retracted positions. In the extended position, the pins <NUM> will have their ends at least partially received in a respective aligned recess <NUM> thereby locking the rotor hub <NUM> and main shaft <NUM> against any rotation. For achieving this purpose, it will be appreciated that the pins <NUM> are part of a rotor locking system in the nacelle <NUM> (<FIG>) that is rigidly secured and fixed in place with components that are not shown for the sake of conciseness. However, these components of the rotor locking system are well known to those of skill in the art. In the retracted or disengaged position, the pins <NUM> will move along the same axial path as the engagement movement previously described but in the opposite direction. This disengagement will unlock disengage the recesses <NUM> and allow rotation of the rotor hub <NUM> and main shaft <NUM>.

The outer diameter of the rotor locking disc <NUM> is smaller than the outer diameter of a conventional rotor locking ring having closed perimeter recesses near the periphery for receiving rotor locking pins. However, embodiments having closed perimeter recesses also have advantages and will be described further below in connection with <FIG>. The reduction in diameter allowed by the use of open perimeter recesses <NUM> further increases accessibility to the rotor hub <NUM> and reduces weight of the rotor locking disc <NUM> while enabling optimization of strength and stress characteristics, as well as allowing more design freedom for the shape and configuration of the disc <NUM>.

Referring further to <FIG>, the connection between the main drive shaft <NUM> and the rotor hub <NUM> is shown. As illustrated best in <FIG>, the main shaft <NUM> includes a front end 34a including a flange <NUM> having a first connecting structure <NUM>. The rotor hub <NUM> includes a second connecting structure <NUM>. The first connecting structure <NUM> of the main shaft <NUM> is fixed to the second connecting structure <NUM> of the rotor hub <NUM>. More specifically, the first connecting structure <NUM> comprises at least first and second sets of fastener holes 38a, 38b in the peripheral region of the rotor locking disc <NUM>. The rotor locking disc <NUM>, in this embodiment, comprises an integral flange <NUM>. However, it will be appreciated that the rotor locking disc <NUM> may instead be a separate component affixed to the main shaft <NUM>. The rotor locking disc <NUM> is carried proximate the front end 34a of the main shaft <NUM>. In this embodiment, the rotor locking elements are respective recesses <NUM>, as mentioned above, but these may be formed in any other configurations such as when combined with the sets of different sized fastener holes 38a, 38b and/or 38c. The first set of fastener holes 38a is located at a position radially inward of the rotor locking elements <NUM> and the second set of fastener holes 38b is located between adjacent rotor locking elements <NUM>.

As indicated by a comparison of <FIG>, the first and/or second sets of fastener holes 38a, 38b are used to receive fasteners 39a and/or 39b to secure the main shaft <NUM> to the rotor hub <NUM>. A third set of fastener holes 38c are located in the peripheral region of the rotor locking disc <NUM> in this embodiment as well. Both the second and third sets of fastener holes 38b, 38c are located between adjacent rotor locking elements <NUM>. When making certain connections between a main shaft <NUM> and a rotor hub <NUM>, it may be desirable to use all three sets of fastener holes 38a, 38b, 38c and corresponding bolts 39a, 39b, 39c for securing the main shaft <NUM> to the rotor hub <NUM>. In other situations, it may be necessary to only use the first set of fastener holes 38a and corresponding large bolts 39a for securing the main shaft <NUM> to the rotor hub <NUM>. In this embodiment, the first set of fastener holes 38a comprise holes of larger diameter than the second and third sets of fastener holes 38b, 38c. For example, the first set of fastener holes 38a are relatively larger sized to receive M48 bolts, while the second and third sets of fastener holes 38b, 38c are relatively smaller sized to receive M36 bolts. Using a main shaft <NUM> configured with these three sets of circularly arranged holes 38a, 38b, 38c, the same main shaft may be affixed to a first hub <NUM> using only the larger holes 38a and larger bolts 39a, or to another hub <NUM> having a different size and/or design configuration using all three sets of holes 38a, 38b, 38c and both large bolts 39a and smaller bolts 39b, 39c. Further, as the third set of fastener holes 38c are positioned radially outwards of the second set of fastener holes 38b, further combinations of the use of holes are possible dependent on which configuration is desired. Examples of possible combinations are <NUM>) only holes 38a as mentioned above, <NUM>) holes 38a and 38b for slightly larger hubs, <NUM>) holes 38b and 38c for even larger hubs, and <NUM>) all holes 38a, 38b and 38c for heavy hubs. As further described in the embodiment illustrated in <FIG>, below, in various aspects the invention may include multiple sets of holes in which all holes have the same diameter.

A second illustrative embodiment of the invention is shown in <FIG>. This embodiment may be formed as described generally above in connection with the first embodiment, but may further include differences as shown and/or described with respect to <FIG>. In this figure, the same reference numerals are used to describe common features or components with respect to the first embodiment and need no further detailed discussion. Features or components that are slightly different from analogous features or components of the first embodiment are denoted with the same reference numerals but also include prime (`) marks. More specifically, the first connecting structure <NUM>' comprises at least first and second sets of fastener holes 38a', 38b' in the peripheral region of the rotor locking disc <NUM>. The rotor locking disc <NUM>, in this second embodiment, comprises an integral flange <NUM>. However, it will be appreciated that the rotor locking disc <NUM> may instead be a separate component affixed to the main shaft <NUM>. The rotor locking disc <NUM> is carried proximate the front end 34a of the main shaft <NUM>. In this embodiment, the rotor locking elements are illustrated as respective closed perimeter recesses <NUM>, but these may be formed in any other configuration(s) as described herein or otherwise. The first set of fastener holes 38a is located at a position radially inward of the rotor locking elements <NUM> and the second and third sets of fastener holes 38b', 38c' are located in the spaces of the locking disc <NUM> between adjacent rotor locking elements <NUM>. As with the first embodiment, there may be only holes 38b' or 38c' located between adjacent rotor locking elements <NUM>, or both sets may be located between adjacent rotor locking elements <NUM>. In addition, there may be additional holes (not shown) located radially outward of the rotor locking elements <NUM>. Notably, in this embodiment, fastener holes 38a, 38b', and 38c' each have the same diameter. The diameters may be of any desired or necessary size for the application. While there are advantages of using sets of fastener holes having different diameters as previously described herein, there are independent advantages of locating fastener holes between adjacent rotor locking elements <NUM>. In this regard, the space between adjacent rotor locking elements <NUM> is efficiently used for connection purposes by placement of one or more fastener holes in these spaces, regardless of the size of the fastener holes and regardless of the particular design or configuration of the rotor locking elements.

As in the first embodiment, the first and/or second sets of fastener holes 38a, 38b' are used to receive suitable fasteners such as bolts to secure the main shaft <NUM> to the rotor hub <NUM>. A third set of fastener holes 38c' are located in the peripheral region of the rotor locking disc <NUM> in this embodiment as well. Both the second and third sets of fastener holes 38b', 38c' are located in the material of the disc <NUM> between adjacent rotor locking elements <NUM>. When making certain connections between a main shaft <NUM> and a rotor hub <NUM>, it may be desirable to use all three sets of fastener holes 38a, 38b', 38c'. As one of many examples, bolts 39a as described in the first embodiment may be used for securing the main shaft <NUM> to the rotor hub <NUM>. In other situations, it may be necessary to use only the first set of fastener holes 38a and corresponding bolts 39a for securing the main shaft <NUM> to the rotor hub <NUM>. If all holes 38a, 38b', 38c' have the same corresponding diameter, then bolts 39a may be used as necessary in each of the holes 38a, 38b', 38c'.

Claim 1:
A wind turbine (<NUM>), comprising:
a main shaft (<NUM>) including a front end (34a), the front end (34a) including a first connecting structure (<NUM>, <NUM>');
a rotor hub (<NUM>) including a second connecting structure (<NUM>), wherein the first connecting structure (<NUM>, <NUM>') of the main shaft (<NUM>) is fixed to the second connecting structure (<NUM>) of the rotor hub (<NUM>);
a plurality of blades (<NUM>) coupled to the rotor hub (<NUM>);
a rotor locking disc (<NUM>, <NUM>') carried on the main shaft (<NUM>), the rotor locking disc (<NUM>, <NUM>') having a peripheral region and a plurality of rotor locking elements (<NUM>) in the peripheral region for receiving one or more rotor locking pins (<NUM>) that are configured to move in an axial direction relative to the lengthwise axis of the main shaft (<NUM>); and
at least first and second sets of fastener holes (38a, 38b, 38b', 38c, 38c') in the peripheral region of the rotor locking disc (<NUM>, <NUM>'), the first set of fastener holes (38a) located at a position radially inward of the rotor locking elements (<NUM>) and the second set of fastener holes (38b, 38b') located between adjacent rotor locking elements (<NUM>), wherein the first and/or second set of fastener holes (38a, 38b, 38b') are used to receive fasteners (39a, 39b) to secure the main shaft (<NUM>) to the rotor hub (<NUM>), characterized in that the rotor locking disc (<NUM>, <NUM>') is integrated with the main shaft (<NUM>).