Abstract:
A locking arrangement includes at least a rotatable part, a stationary part with respect to the first part, and a locking member having locking protrusions. At least one working plane passing through the locking protrusions is defined in a locking position where compression forces are concentrated which are reaction forces to external forces tending to rotate the parts relative to each other. The parts have locking protrusions defining gaps for receiving the locking protrusions in the locking position for preventing the parts from being rotated to each other.

Description:
This application claims the benefit of European Patent Application EP 12382236.3 filed Jun. 11, 2012 and U.S. Provisional Patent Application Ser. No. 61/682,610 filed Aug. 13, 2012, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     A locking arrangement for preventing at least one part to be rotated relative to at least another part around an axis of rotation in wind turbine applications. 
     A wind turbine provided with such a locking arrangement. 
     BACKGROUND 
     Within the field of wind turbine applications, temporary locking of movable parts is very important, particularly temporary locking of parts such as the rotor with respect to the stator, the blades with respect to the nacelle, etc., in a wind turbine. 
     Positive locking systems in wind turbine rotor braking devices should be provided according to current guidelines for certification of wind energy plants. This means that a mechanical interlocking should be provided to lock rotating parts in wind turbines for repair and/or maintenance operations and in general for purposes where such parts must be locked against rotation. In this respect, for example frictional brakes and the like are not allowed according to these guidelines. 
     The use of locking arrangements for locking rotatable parts against rotation in wind turbines, such as the rotor, is known in the art. Such locking arrangements include one or more locking pins that are fixedly arranged, for example, to the stator of the wind turbine generator. When service activities are required in the wind turbine, a brake assembly is actuated to stop the wind turbine in operation. Once the wind turbine generator is stopped, the locking arrangement can be then activated to lock the rotor against rotation. The activation of the locking arrangement is carried out by driving a locking member or locking pin into a corresponding locking gap that is usually formed in the rotor. Driving of the locking pin can be carried out manually or hydraulically along the axis of the locking pin. The axis of the locking pin is substantially parallel to the rotor axis. Once the locking pin is inserted into a target locking hole, the rotor is prevented from being rotated relative to the stator and service activities can take place safely. 
     The main problem of the above method is the large tolerances existing in the relative position of the locking pins and the locking holes when in the locking position. This further results in alignment problems of the locking pins and the corresponding locking holes. 
     Another problem with known locking arrangements is that wind turbines are currently becoming bigger in order to produce more energy. This involves increased dimensions of the generator such that the locking pins are also bigger. Since the locking pins must be manufactured to withstand the requirements of operating within harsh working conditions of the wind turbine, costs become undesirably high. This also applies to the actuating mechanisms for driving the locking pins into and out of the locking position which need to be dimensioned in order to withstand high loads. 
     In addition, the increased dimensions of the wind turbines and parts thereof have led to increased loads on the locking arrangement. Consequently, concentration of shear forces has become an important issue. Alternative materials for the locking arrangements or the increase in their size are solutions that are not useful for withstanding the extremely high loads involved in current wind turbines. Attempts have been made to provide several locking pins. However, costs and misaligning problems still remain. 
     EP1291521 discloses a locking arrangement for a wind turbine rotor. The locking arrangement in this case comprises an axially movable locking pin that is arranged on the nacelle structure and corresponding locking gaps formed in the wind turbine rotor. The locking pin has a tapered end for compensating for misalignments and plays into the holes. Due to the location and the small dimensions of the working plane of the locking pin where shear forces are concentrated, extremely high stresses are present resulting in a highly potential risk of failure of the locking pin when the locking arrangement is in a locking position. 
     Document WO2008059088 discloses an adjustable, self-aligning rotor locking device for preventing the hub from being rotated relative to the wind turbine nacelle. The rotor locking device includes locking pins fixed to the nacelle and actuation means for driving the locking pin axially in relation to at least one corresponding hole formed in the hub. In this case, the location and the small dimensions of the working plane of the locking pin where shear forces are concentrated is the same as the above document such that extremely high stresses are present with a resulting potential risk of failure of the locking pin. 
     Many other locking arrangements have been provided having in common the location and the small dimensions of the working plane of the locking pin where shear forces are concentrated. For example, documents WO2010102967, WO2005090780 and WO2008155053 all describe locking arrangements for wind turbine applications where a locking pin is movable in a direction towards a locking gap for locking the parts against rotation. 
     Due to the fact that the locking pin is subjected to high loads when in the locking position and that said loads are concentrated on a small working plane of the locking pin, loads concentrated therein result in that the locking pin may be likely to deform, crack or break when in the locking position. In addition, it also remains difficult to compensate for radial misalignments in prior art locking arrangements. 
     SUMMARY 
     The above disadvantages have been overcome by the present locking arrangement of the present disclosure as well as by a wind turbine having such locking arrangement. Advantageous embodiments are defined in the dependent claims. 
     A locking arrangement is provided for preventing at least a first part to be rotated relative to at least a second part around an axis of rotation in a wind turbine when in a locking position in which one part is prevented from being rotated relative to the other part. The first and second parts may be, for example, the stator or the rotor in a wind turbine. Other rotatable and/or stationary parts in wind turbine applications are not ruled out for the present locking arrangement. 
     Specifically, the present locking arrangement includes a locking member in which at least one working plane is defined. In such working plane, compression forces are concentrated when in the locking position. Compression forces in the working plane are reaction forces generated in response to external forces tending to rotate said first and second parts relative to each other when they are in the locking position. 
     The provision of a locking member having defined at least one working plane where compression forces are concentrated when in the locking position allows an important improvement on the strength behaviour to be achieved. A multiplicity of mutually parallel working planes can be defined within the locking member when in the locking position. 
     In some embodiments, the locking member is an element having at least one locking protrusion. This locking protrusion includes the working plane when in the locking position. In other words, although the working plane may pass through other elements of the locking arrangement such as the protrusion of the second part, the working plane mainly passes through the locking member. 
     The locking protrusion is configured, e.g. in size and shape, to be suitably received into a corresponding gap defined between said first and second parts of the wind turbine. The locking protrusion may be fully received into the gap defined between the first and second parts or it may be partly received therein. In any case, the insertion depth of the locking protrusion into the gap defined between the first and second parts is sufficient for suitably locking the first and/or second parts against rotation with respect to one another and in a way that at least one working plane is defined where compression forces are concentrated. 
     It is preferred that the locking member includes a parallelepiped elongated element. However, different geometries are not ruled out as long as said working plane where compression forces are concentrated is defined in said locking position. 
     The first part of the locking arrangement may be provided with at least two locking protrusions and the second part may be provided with at least one corresponding locking protrusion. The locking protrusion of the second part may be such that it projects between the locking protrusions of the first part. Gaps are thus defined between said locking protrusions of the parts. The first and second parts are prevented from being rotated relative to each other when the locking protrusions of the locking member are inserted into the gaps. In such position, the working plane is defined where compression forces are concentrated. 
     In a preferred embodiment of the present locking arrangement, the working plane is at least substantially parallel to the major dimensions of at least one of the locking protrusions of the locking member, or at least substantially parallel to the major dimensions of at least one of the locking protrusions of the first part or at least substantially parallel to the major dimensions of the locking protrusion of the second part. In addition, the working plane may be at least substantially parallel to the major dimensions of several of the above locking protrusions. 
     The major dimension of a locking protrusion refers to the larger surface thereof. For example, in the case of locking members having an elongated parallelepiped geometry, the major dimension is any of the larger faces thereof so the working plane in this case is any of the geometric planes arranged parallel to said larger surfaces. The working plane may also include any of the larger faces of the locking protrusion. 
     In some specific cases, the locking protrusion or protrusions of at least one of the locking member, the first part and the second part could have at least one inclined surface. 
     The present locking arrangement may be further provided with an actuator. The actuator is intended for driving the locking member into and out of the locking position. Such actuator may be mechanical, electric, hydraulic or any other suitable type. 
     In preferred embodiments, the locking member is movable in a direction perpendicular to the axis of rotation of said first and second rotatable parts of the wind turbine. 
     A wind turbine is herein provided including a rotor having a rotor portion and a stator having a stator portion. The rotor and stator portions are complimentarily shaped such that both define a locking gap for receiving at least one portion of a locking member according to the above locking arrangement. In this case, the locking member may be mounted radially or axially into rotor and stator flange portions. In any case, the locking member may be mounted close to the rotor and/or the stator flange portions. 
     Additional objects, advantages and features of embodiments of the present locking arrangement will become apparent to those skilled in the art upon examination of the description, or may be learned by practice of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Particular embodiments of the present locking arrangement will be described in the following by way of non-limiting examples, with reference to the appended drawings, in which: 
         FIG. 1  is a perspective view of a first embodiment of the present locking arrangement showing the first part of the locking arrangement, the second part of the locking arrangement and the locking member of the locking arrangement in a locking position in which the first and second parts are prevented from being rotated relative to each other; 
         FIG. 2  is an enlarged detail view of the locking arrangement in  FIG. 1 ; 
         FIG. 3  is a front elevational view of the locking arrangement in  FIG. 1 ; 
         FIG. 4  is an enlarged sectional view of the locking arrangement in  FIG. 1 ; 
         FIG. 5  is a perspective view of the embodiment of the present locking arrangement with the locking member in an unlocking position in which the first and second parts are allowed to be rotated relative to each other; 
         FIG. 6  is an enlarged perspective view of the locking arrangement in  FIG. 5 ; 
         FIG. 7  is a perspective view of a second embodiment of the present locking arrangement with the locking member in an unlocking position in which the first and second parts are allowed to be rotated relative to each other; 
         FIG. 8  is a front elevational view of the locking arrangement in  FIG. 7  with the locking member in a locking position in which the first and second parts are prevented from being rotated relative to each other; 
         FIG. 9  is a perspective view of the second embodiment of the present locking arrangement with the locking member in the locking position in which the first and second parts are prevented from being rotated relative to each other; 
         FIG. 10  is an enlarged detail view of the locking arrangement in  FIGS. 8 and 9 ; and 
         FIG. 11  is an enlarged front elevational detail view of the locking arrangement in  FIGS. 8 and 9 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Two embodiments of the present locking arrangement are disclosed herein with reference to the above figures. Both embodiments of the present locking arrangement are described and depicted in a locking position and in an unlocking position. 
     Like reference numerals refer to like parts throughout the description of several views of the drawings. 
     According to the figures, the locking arrangement is indicated as a whole at  100 . In said two embodiments, the locking arrangement  100  is provided for preventing a first part such as a wind turbine rotor  110  to be rotated relative to a second part such as a wind turbine stator  120 . In operation, and in the unlocking position as shown in  FIGS. 5-7 , the wind turbine rotor  110  can be rotated relative to the wind turbine stator  120  around an axis of rotation A when in the unlocking position. 
     The embodiments of the locking arrangement  100  include the above parts  110 ,  120  and a locking member  130 . One specific but non limiting example of the locking member  130  is shown in  FIGS. 2, 6 and 10, 11 . 
     Referring now to  FIGS. 4 and 6  of the drawings, the locking member  130  includes a locking element  135  that is defined by a substantially curved elongated parallelepiped geometry. The locking element  135  has two downwardly extending locking protrusions  135   a ,  135   b  and a corresponding central recess  135   c.    
     The wind turbine rotor  110  includes a rotor flange portion having two locking protrusions  110   a ,  110   b.    
     The wind turbine stator  120  includes a stator hub  125  having a locking protrusion  125   c . In operation, that is when in the unlocking position, the rotor  130  can be rotated relative to the stator hub  125  such that the locking protrusions  110   a ,  110   b  of the wind turbine rotor  110  rotate above the locking protrusion  125   c  of the stator hub  125 . 
     Between the locking protrusions  110   a ,  110   b  of the wind turbine rotor  110  and the locking protrusion  125   c  of the stator hub  125  corresponding gaps  140   a ,  140   b  are defined as shown in  FIG. 6 . The gaps  140   a ,  140   b  are suitable for receiving the locking protrusions  135   a ,  135   b  of the locking member  130 . 
     In the locking position of the locking member  130 , shown in  FIGS. 1-4 , the locking protrusions  135   a ,  135   b  of the locking member  130  are inserted into the gaps  140   a ,  140   b.    
     In such locking position, the wind turbine rotor  110  is prevented from being rotated relative to the wind turbine stator  120 . In this condition, that is, when the wind turbine rotor  110  is locked against rotation, a working plane P is defined in the locking member  130  as shown in  FIG. 4 . A working plane P or a multiplicity of mutually parallel working planes P are defined passing within the locking protrusions  135   a ,  135   b  of the locking member  130  when in said locking position. The working plane P contains compression forces F-F′ as shown in  FIG. 4 , generated when in the locking position. Compression forces F-F′ in the working plane P are reaction forces to external forces tending to rotate the wind turbine rotor and stator  110 ,  120  relative to each other when the wind turbine rotor  110  is locked against rotation. Said compression forces F-F′ are concentrated between the protrusions  110   a ,  110   b  of the wind turbine rotor  110  and the locking protrusion  125   c  of the wind turbine stator  120 . 
     The working plane P is defined in the locking member  130  when in the locking position. As shown in  FIG. 4 , the working plane P is parallel to the major surfaces of the locking protrusions  110   a ,  110  of the locking member and the major surfaces of the locking protrusion  125   c  of the wind turbine stator  120  and also the major surfaces of the locking protrusions  135   a ,  135   b  of the locking member  130 . 
     It is foreseen that the locking member  130  may be fitted radially or axially relative to the wind turbine rotor or stator  110 ,  120 . 
     A second embodiment is provided according to  FIGS. 7-11 . In this embodiment, the locking member  130  includes a locking element  135  defined by a substantially curved elongated parallelepiped geometry and provided with a single downwardly extending locking protrusion  135   a.    
     Between the protrusions formed in the wind turbine rotor  110  and the protrusion  125   c  of the stator hub  125  a gap  140   a  is defined as shown in  FIG. 7 . The gap  140   a  is suitable for receiving the locking protrusion  135   a  of the locking member  130 . 
     In the locking position of the locking member  130 , shown in  FIGS. 8-11 , the locking protrusion  135   a  of the locking member  130  is inserted into the gap  140   a . In this locking position, the wind turbine rotor  110  is prevented from being rotated relative to the wind turbine stator  120  in one direction such that a working plane P or a multiplicity of mutually parallel working planes P are defined passing within the locking protrusion  135   a  of the locking member  130  when in said locking position. 
     In all the embodiments disclosed herein, the wind turbine rotor  110  and the wind turbine stator  120  may be near a flange provided in a bearing joining them. This flange is a good region to place the locking arrangement since it is already reinforced as it is a stress concentration region. Additional reinforcements are thus not necessary. 
     Although only a number of particular embodiments and examples of the present locking arrangement have been disclosed herein, it will be understood by those skilled in the art that other alternative embodiments and/or uses and obvious modifications and equivalents thereof are possible. All possible combinations of the particular embodiments described herein are covered. 
     Reference signs related to drawings and placed in parentheses in a claim, are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim. Thus, the scope of the present disclosure should not be limited by particular embodiments, but should be determined only by a fair reading of the claims that follow.