Patent Publication Number: US-2019195197-A1

Title: Rotor arresting device for a wind turbine and method

Description:
BACKGROUND 
     Technical Field 
     The invention relates to a rotor arresting device for a wind turbine, to a wind turbine and to methods for arresting and for moving a rotor of a wind turbine. 
     Description of the Related Art 
     A wind turbine converts the energy of the wind into electrical energy. The dominant design form of wind turbines is the three-bladed horizontal-axis wind turbine in which, during operation, the rotor is situated on the windward side and its machine housing is arranged on a tower and actively tracks the wind direction. 
     The rotor blades of a wind turbine are generally fastened to a common hub. This hub is preferably connected to a rotation assembly in a rotationally rigid manner. In the case of wind turbines with a direct drive, that is to say without a gearbox for transmission, the rotor generally drives a generator rotor. In the case of wind turbines with gearbox, the rotation assembly generally comprises a rotor shaft which connects the rotor and a gearbox to one another and thus converts the rotational movement of the rotor into a gearbox output movement and then transmits this gearbox output movement in turn to a generator. 
     What is to be understood by a rotor in the context of this application is the aerodynamic rotor of a wind turbine having, typically, three rotor blades. What is to be understood by a generator rotor in the context of this application is an electrodynamic rotor of a generator. A generator in the context of this application comprises both inner-rotor generators, in which a generator rotor rotates radially within a stator, and outer-rotor generators, in which a generator rotor rotates radially outside around a stator. 
     It is desirable in various situations for the rotor of a wind turbine to be arrested. For example, it is frequently required for the rotor to be arrested in order to carry out repair and/or maintenance work, for example in the interior of the nacelle or in the region of the hub. Furthermore, it is required, for example, for the rotor to be arrested when the wind turbine is mounted and/or demounted. For example, high arresting forces and/or arresting torques occur in order to hold a rotor in a defined position if not all of the intended rotor blades are arranged and the rotor is situated in an unstable position. As a result, the rotor blades, which are not uniformly arranged about a point of rotation, produce a high torque with respect to this point of rotation. Furthermore, it is frequently required for the rotor to be arrested in a desired position with a high degree of accuracy such that position-dependent repairs and/or maintenance work and/or assembly work can be carried out. 
     Current rotor arresting devices primarily have the aim of providing secure arresting. This is explained in particular by the fact that corresponding safety measures must be put in place for persons working on the wind turbine. Therefore, there is primarily provision in known rotor arresting devices for combinations of bolts and preferably a plurality of openings. Openings are preferably arranged on a generator rotor of a generator, in particular on a rotor support, the passage direction of which openings is preferably arranged substantially parallel to an axis of rotation of the generator. Bolts which correspond to the openings and which can be arranged in the openings are preferably arranged on the generator stator, in particular on a stator support. The arrangement of the bolts within the openings means that the generator rotor, and hence also the aerodynamic rotor, can be arrested. 
     Although such a rotor arresting device can, on the one hand, provide secure arresting of the rotor, positioning of the rotor is possible only at the positions at which openings are provided on the rotation assembly. Furthermore, it is required, for example for mounting rotor blades, to release the arresting action after mounting a first rotor blade in order to rotate the rotor into the position for mounting the second rotor blade and to arrest it again in said position. This results in high costs and a large degree of effort in a wide variety of application regions. Although the existing systems and methods for arresting wind turbine rotors offer various advantages, further improvements are desirable. 
     The German Patent and Trademark Office has searched the following prior art in the priority application pertaining to the present application: DE 10 2010 020 355 A1 and GB 2 535 331 A. 
     BRIEF SUMMARY 
     According to a first aspect of the present invention, provided is a rotor arresting device for a wind turbine having a rotor and a rotation assembly which is connected to the rotor in a rotationally rigid manner, comprising at least one coupling device which can be arranged on a static assembly, which is positionally fixed relative to the rotation assembly, of the wind turbine, having a first actuator, a second actuator, a coupling element which is connected to the first and the second actuator, and a counterpart coupling element which can be arranged on the rotation assembly, wherein the coupling element and the counterpart coupling element are releasably connected, preferably in a form-fitting manner, in an arresting position of the coupling device, and wherein the coupling device can be brought from a release position into the arresting position by means of a first coupling movement of the first actuator and/or by means of a second coupling movement of the second actuator, and wherein the first coupling movement has a first setting direction component and the second coupling movement has a second setting direction component, wherein the first setting direction component and the second setting direction component are directed in opposite directions. 
     The rotation assembly is connected to the rotor in a rotationally rigid manner. If not explicitly otherwise described, a rotor is to be understood as meaning the assembly comprising at least one rotor blade and a hub on which the at least one rotor blade is arranged. The rotor often also has a spinner. The rotation assembly can comprise, for example, a rotor support and/or a rotor shaft which are or is arranged on the rotor hub in a rotationally rigid manner. The rotation assembly can preferably also comprise a generator rotor. Furthermore, the rotation assembly preferably comprises any component which, by means of a rotation of the rotor, is likewise set into a rotational movement. 
     In addition to the rotation assembly, a wind turbine generally comprises a static assembly which is positionally fixed in relation to the rotation assembly. The static assembly particularly comprises such elements which are arranged within the nacelle and which perform no rotational movement about an axis of rotation of the rotor. The static assembly is thus positionally fixed in relation to the rotation assembly. However, the static assembly, together with the nacelle, can as a rule be rotated about a substantially vertical axis with respect to the tower and/or the foundation of the wind turbine, since wind turbines generally have a wind direction tracking system, with the result that the nacelle can rotate about an axis parallel to the longitudinal axis of the tower. Consequently, the static assembly, which is arranged within the nacelle, also rotates with respect to a point outside of the nacelle, in particular with respect to the ground on which the wind turbine is erected. In the context of this application, the term “positionally fixed” is therefore to be understood in relation to the rotating rotation assembly. The static assembly comprises, for example, a generator stator, a journal, a machine support, a generator housing, or a gearbox housing. Furthermore, the static assembly preferably comprises an element on which the coupling device can be arranged. 
     The at least one coupling device has at least two actuators, namely the first actuator and the second actuator, wherein an actuator is preferably to be understood as meaning an element which can move itself and/or a further element into a defined position. In particular, the first actuator and the second actuator are arranged and designed in such a way that they can move the coupling element, to which the actuators are connected, into different positions. 
     Furthermore, the rotor arresting device comprises the counterpart coupling element, which, in the installed state and/or in the operating state, is arranged on the rotation assembly of the wind turbine. The counterpart coupling element and the coupling element are arranged and designed in such a way that they can form a releasable, in particular form-fitting, connection. This form-fitting connection preferably results in the rotation assembly being prevented from rotating about an axis of rotation. This releasable connection of the coupling element and of the counterpart coupling element is formed as soon as the coupling element is situated in an arresting position. 
     As already stated in the foregoing, the connection between the coupling element and the counterpart coupling element is configured to be releasable. The coupling element can also be brought into a position in which the connection is released, that is to say no connection between coupling element and counterpart coupling element is present. In this position, the coupling element and the counterpart coupling element are not connected to one another, this position being referred to as release position. In the release position, the rotation assembly can rotate about its axis of rotation without it being prevented from rotating about this axis of rotation by the coupling element or the coupling device. For a coupling element there preferably result one, two or more release positions in which it is thus not connected to the counterpart coupling element. Moreover, one, two or more arresting positions can also result for a coupling element. This can be achieved, for example, by the arrangement of more than one counterpart coupling element, wherein the one coupling element is then designed and arranged to reach more than one counterpart coupling element. 
     From this release position, the coupling element can be moved into the arresting position by the first actuator and/or by the second actuator by means of a first coupling movement of the first actuator and/or by means of a second coupling movement of the second actuator. The first coupling movement and the second coupling movement have a direction component which is directed in opposite directions. This so-called setting direction component is preferably oriented substantially tangentially to the rotation assembly. The first coupling movement comprises the first setting direction component, which is preferably oriented in a first tangential direction of the rotation assembly. The second coupling movement comprises the second setting direction component, which is preferably oriented in a second tangential direction of the rotation assembly, wherein the first tangential direction and the second tangential direction are opposite to one another. 
     In a preferred embodiment variant of the rotor arresting device, there is provision that it comprises two or more coupling devices and/or two or more first actuators and/or two or more second actuators and/or two or more coupling elements. The two or more coupling devices are preferably designed according to the above description of the coupling device. It is furthermore preferable for the two or more coupling devices to be arranged equidistantly on a circumference of the rotation assembly. On account of the generally high forces and/or torques which occur during the arresting of a rotor of a wind turbine, it is preferable for two or more coupling devices to be arranged. Six or more coupling devices are preferably arranged. In particular, it is preferable for two or more coupling devices to be arranged if one, two or more coupling devices or their coupling elements are temporarily not situated in the arresting position, for example in order to form a connection with a counterpart coupling element which is spaced apart from a current arresting position in the tangential direction. In order that the movement of one, two or more coupling elements toward a counterpart coupling element spaced apart in the tangential direction can occur while ensuring rotor arresting, a sufficient number of coupling elements should still be situated in an arresting position during this movement. The sufficient number of coupling elements in preferably one, two or more. A cyclical activation of the coupling devices can thus also occur. 
     Moreover, it can be advantageous that the coupling device comprises two or more first actuators and/or two or more second actuators. The arrangement of two more first and/or second actuators can ensure an improved movement of the coupling element. Moreover, in certain embodiment variants, a plurality of actuators can also be used in a space-saving manner, for example if a large actuator is replaced by a plurality of small ones. Moreover, it can be advantageous that two or more coupling elements are used per coupling device, with the result that, for example, better force distribution can be achieved. 
     According to a further preferred embodiment variant of the rotor arresting device, there is provision that the first coupling movement has a first coupling direction component and the second coupling movement has a second coupling direction component, wherein the first coupling direction component and the second coupling direction component are directed in the same direction, wherein furthermore the first coupling direction component and the second coupling direction component is preferably directed from the coupling element toward the counterpart coupling element. A coupling movement preferably comprises in particular a coupling direction component and a setting direction component. In this embodiment variant, there is preferably provision that the first coupling movement and the second coupling movement each have a movement component which is directed in the same direction, that is to say the coupling direction component, and a movement component which is directed in the opposite direction, that is to say the setting direction component. The coupling direction component of the coupling movement is primarily provided to move the coupling element from a release position into an arresting position. By contrast, the setting direction component of the coupling movements is oriented at least in part orthogonally to the coupling direction component and thus is preferably primarily provided to move the coupling element in a tangential direction of the rotation assembly. As a result of the first and second coupling direction component and the first and second setting direction component of the first and second coupling movement, the first actuator and the second actuator are preferably arranged in a V-shaped arrangement. Furthermore, as a result of a tangential force on the coupling element, there preferably result no exclusive transverse forces on the actuators or the coupling element, and therefore the risk of jamming is reduced. 
     A further preferred development of the rotor arresting device is distinguished by the fact that the first coupling direction component and/or the second coupling direction component are or is oriented parallel to an axis of rotation of the rotation assembly of the wind turbine. In this embodiment variant, the counterpart coupling element is preferably arranged at a location of the rotation assembly which is accessible for example on the end side for the coupling element, with the result that the coupling element can be fed to the counterpart coupling element with an axial movement. The counterpart coupling element is preferably arranged on an end side of one or more elements of the rotation assembly. Furthermore preferably, the counterpart coupling element is arranged on a radial circumferential surface of one or more elements of the rotation assembly, but accessible by a coupling element moved in the axial direction. 
     Furthermore, there is preferably provision that the first coupling direction component and/or the second coupling direction component are or is oriented orthogonally and/or radially to the axis of rotation of the rotation assembly of the wind turbine. In this embodiment variant, the counterpart coupling element is preferably arranged on a radial circumferential surface of the rotation assembly or on an element of the rotation assembly, with the result that the coupling element can be brought into connection with the counterpart coupling element in that the coupling element performs a radial and/or orthogonal movement to the axis of rotation of the rotation assembly. Furthermore preferably, the counterpart coupling element is arranged on an end face of the rotation assembly or on one or more elements of the rotation assembly, wherein the counterpart coupling element arranged in such a way can be brought into connection with a coupling element moved orthogonally and/or radially to the axis of rotation. 
     In a further preferred embodiment variant of the rotor arresting device, there is provision that the coupling device can be brought from the arresting position into the release position by means of a first decoupling movement of the first actuator and/or by means of a second decoupling movement of the second actuator, and/or wherein the first decoupling movement has a first release direction component and the second decoupling movement has a second release direction component, wherein the first release direction component and the second release direction component are directed in opposite directions, and/or wherein the first decoupling movement has a first decoupling direction component and the second decoupling movement has a second decoupling direction component, wherein the first decoupling direction component and the second decoupling direction component are directed in the same direction. 
     The first decoupling movement is preferably parallel to the first coupling direction component, wherein the latter is furthermore preferably directed in an opposite direction. Furthermore preferably, the second decoupling direction component is parallel to the second coupling direction component, wherein the second coupling direction component is directed in an opposite direction to the second decoupling direction component. Moreover, the first release direction component can be oriented parallel to the first setting direction component, wherein they are preferably directed in opposite directions. Furthermore, the second release direction component can be oriented parallel to the second setting direction component, wherein these are preferably directed in opposite directions. The first decoupling movement and/or the second decoupling movement are particularly designed to move the coupling element away from the counterpart coupling element. In particular, the first decoupling movement and/or the second decoupling movement are or is designed to release the releasable connection between the coupling element and the counterpart coupling element. 
     According to a further particularly preferred embodiment variant of the rotor arresting device, there is provision that the first actuator and the second actuator are each designed to be activatable independently of one another. Consequently, the first actuator can preferably carry out the first coupling movement and/or the first decoupling movement independently of the second coupling movement and/or of the second decoupling movement of the second actuator. However, since the first actuator and the second actuator are each connected to the coupling element and to the static assembly, the movement components of the first actuator and/or of the second actuator are as a rule independent of one another. Moreover, there is the possibility that the first actuator or the second actuator is switched to a force-free state, with the result that the actuator which is respectively not switched to a force-free state codetermines the movement of the actuator which is respectively switched to a force-free state. This preferably also applies if the forces of the one actuator exceed the oppositely acting forces of the other actuator. 
     It is furthermore preferred that the first actuator and/or the second actuator comprise or comprises an extendable cylinder. In this embodiment variant, the first actuator and/or the second actuator preferably carry or carries out the above-described movements by means of the extendable cylinder. This cylinder is preferably guided by a further element. The cylinder is preferably situated within a sleeve, wherein the sleeve furthermore preferably guides a radial circumferential surface of the cylinder. Moreover, the sleeve can be rotatably arranged on the static assembly. 
     A further particularly preferred embodiment variant of the rotor arresting device provides that the first actuator and/or the second actuator comprise or comprises a hydraulic cylinder or are or is designed as a hydraulic cylinder, wherein the hydraulic fluid is preferably water. Hydraulic cylinders are preferably distinguished by the fact that they can exert a large force in at least one linear force direction. Furthermore, hydraulic cylinders are distinguished by the fact that they can also hold large forces stationary. A hydraulic cylinder is generally a working cylinder operated by means of fluid. Hydraulic cylinders are also referred to as a hydraulic linear motor. The first and/or second actuator, in particular the first and/or second hydraulic cylinder, are or is preferably designed and arranged to be able to apply a torque of 100 to 1,000 kNm to the rotation assembly. The (external) torque originating from the rotation assembly, in particular the rotor, and to be taken up by the static assembly, in particular the stator, can lie in an order of magnitude of up to or even above 10,000 kNm. Since preferably a plurality of first and/or second actuators are provided, the torques to be applied by the actuators can be considerably lower. 
     In a hydraulic cylinder, the energy from the hydraulic fluid, which is preferably provided from a hydraulic pressure source, is converted into a simply controllable, preferably rectilinearly acting, force. Hydraulic cylinders preferably comprise as main constituent parts a tubular element with a cavity which has a cross section orthogonal to the longitudinal axis of the cavity, and a cylinder which is arranged within said cavity. In the present application case, the hydraulic fluid provided is preferably water since the otherwise also customary hydraulic fluid oil can lead to disadvantages during a malfunction of the hydraulic system. Particularly problematic here is the leaking-out of oil onto other components and/or onto the coupling elements or counterpart coupling elements, since the arresting functionality could be reduced as a result. However, under certain circumstances, oil can also be used as the hydraulic fluid. 
     Furthermore preferably, the first actuator and/or the second actuator have or has a nonreturn valve. In particular, nonreturn valves designed as load-holding valves prevent a situation in which loads on cylinders and/or actuators can be reduced in an uncontrolled manner. Such a holding mechanism is of great advantage particularly in the present application field of rotor arresting for wind turbines. In particular, the provision of a nonreturn valve can avoid or reduce the risk of unwanted release of the connection between coupling element and counterpart coupling element. 
     A further preferred development of the rotor arresting device is distinguished by the fact that the first actuator and/or the second actuator can be rotatably arranged on the static assembly and/or wherein the first actuator and/or the second actuator are or is rotatably connected to the coupling element. The first actuator and/or the second actuator are or is preferably rotatable about an axis, wherein this axis is arranged on the static assembly or in a region adjoining the static assembly. Further preferably, the first actuator and/or the second actuator are or is rotatable about an axis, wherein this axis is arranged on the coupling element or in a region adjoining the coupling element. 
     Furthermore, there is preferably provision that the first actuator and/or the second actuator are or is rotatably connected to the static assembly in such a way that the first actuator and/or the second actuator are or is rotatable about an axis which is oriented parallel to the axis of rotation of the rotation assembly of the wind turbine. In this embodiment variant, the first actuator and/or the second actuator are or is rotatable in a plane which is oriented orthogonally to the axis of rotation of the rotation assembly. This plane is preferably substantially surface-parallel to the plane of rotation of the rotor. 
     It is further preferable that the first actuator and/or the second actuator are or is rotatably connected to the static assembly in such a way that the first actuator and/or the second actuator are or is rotatable about an axis which is oriented orthogonally and/or radially to the axis of rotation of the rotation assembly of the wind turbine. According to a further preferred embodiment variant of the rotor arresting device, there is provision that the first actuator and/or the second actuator are or is rotatably connected to the coupling element in such a way that the first actuator and/or the second actuator are or is rotatable about an axis which is oriented parallel to the axis of rotation of the rotation assembly of the wind turbine. 
     A further particularly preferred embodiment variant of the rotor arresting device provides that the first actuator and/or the second actuator are or is rotatably connected to the coupling element in such a way that the first actuator and/or the second actuator are or is rotatable about an axis which is oriented orthogonally and/or radially to the axis of rotation of the rotation assembly of the wind turbine. In a particularly preferred embodiment variant of the rotor arresting device, there is provision that the actuators are rotatably connected to the static assembly and to the coupling element. It is thus possible to achieve a maximum flexibility of the movement direction of the first actuator and/or of the second actuator in combination with the coupling element. In particular, particularly many degrees of freedom are thus provided for the kinematics of the coupling device. 
     According to a further particularly preferred embodiment variant of the rotor arresting device, there is provision that the counterpart coupling element is arranged on a counterpart coupling device which is preferably ring-shaped, and wherein the counterpart coupling device can be arranged on the rotation assembly and/or wherein the counterpart coupling element is designed as a toothing recess. The ring-shaped counterpart coupling device preferably has a plurality of counterpart coupling elements which are furthermore preferably arranged equidistantly on the circumference of the counterpart coupling device. 
     The counterpart coupling device can preferably be designed as a constituent part of an existing element of the rotation assembly or be arranged on one element or two or more elements of the rotation assembly. The counterpart coupling device can preferably be an internally toothed circumference of the generator rotor, in particular of a rotor support. Furthermore preferably, the counterpart coupling device can be an externally toothed circumference of the generator rotor, in particular of a rotor support. Furthermore preferably, the counterpart coupling device can be a toothed end side of the generator rotor, in particular of a rotor support. The counterpart coupling device can alternatively preferably also be a separate element, for example a disk which is arranged on the rotation assembly in a rotationally rigid manner. Furthermore preferably, the counterpart coupling device can also be arranged on the input and/or output side of a gearbox of the wind turbine. With particular preference, the counterpart coupling element takes the form of a toothing recess. Two adjacent toothing recesses preferably form between them a tooth. The arrangement of a plurality of toothing recesses is particularly preferred. 
     A preferred development of the rotor arresting device is distinguished by the fact that the counterpart coupling device comprises a plurality of segment plates or consists of a plurality of segment plates. Furthermore, it is preferable that a device of the stator assembly comprises a plurality of segment plates or consists of a plurality of segment plates. Such segment plates preferably have at least one radial portion which forms a segment of a supporting structure of a counterpart coupling device and/or of a device of the stator assembly and has, for example, a plurality of reinforcing struts, the reinforcing struts being designed to take up compressive, tensile and shear forces. A plurality of segment plates are preferably arranged on one another in a plane such that they together form a plate ring, and a plurality of segment plates are stacked in the plate rings formed in such a way that they together form a plate bundle. In particular, the radial portion is preferably designed to form, in conjunction with the radial portions of further segment plates, a supporting structure of a counterpart coupling device and/or of a device of the stator assembly. 
     This configuration has the advantage, inter alia, that a counterpart coupling device and/or a device of the stator assembly can be produced and/or transported in a time and/or cost-effective manner. 
     Furthermore preferably, a plurality of through-openings which are adapted to guide through corresponding bracing elements are formed in the radial portion. The through-openings are preferably arranged along two or more spaced-apart circular arc lines, wherein the circular arc lines are preferably formed concentrically. With particular preference, in one embodiment with a first circular arc line and a second circular arc line, the through-openings on a first circular arc line are arranged offset in the circumferential direction to the through-openings on a second circular arc line. Furthermore preferably, the through-openings are arranged equidistantly to one another on their respective circular arc lines. This arrangement has the following advantage: the segment plates can be stacked on top of one another in an overlapping manner, with the result that the “seams” between the segment plates which adjoin one another in a ring plane are offset with respect to one another. At the same time, the equidistant, in particular two or more-rowed, arrangement of the through-openings allows an axial bracing of the overlapping segment plates. The thus produced static friction between the plates significantly increases the load-bearing capacity of the plate bundles and can contribute to a better damping behavior of acoustic vibrations which are emitted during the operation of the wind turbine. 
     The bracing elements are preferably designed to fixedly interconnect segment plates which are stacked on top of one another. The bracing elements preferably take the form of threaded rods, screws, bracing cables or the like. For the bracing, pressure distribution elements are preferably arranged at the ends of the bracing elements and are designed to distribute the bracing forces to as large a surface area as possible of the segment plates. The pressure distribution elements are designed, for example, as disks, rings, ring segments, sleeves or the like. 
     Furthermore preferably, a plurality of material weakenings or cutouts are arranged between the reinforcing struts in the radial portion. The material weakenings or cutouts preferably have the effect of weight reduction. The structure of the reinforcing struts is preferably obtained by means of laser cutting, water jet cutting, stamping or—particularly preferably—punching. 
     With particular preference, the through-openings and/or the reinforcing struts are in each case formed in the third radial portion by means of punching a base plate, wherein preferably, in the case of the reinforcing struts, material regions are punched out or stamped adjacent to the struts to be formed. 
     In a preferred embodiment variant of the rotor arresting device, there is provision that the counterpart coupling element designed as a toothing recess substantially has a semicircular geometry and/or the coupling element has a cylindrical geometry. In the embodiment variant with a toothing recess with a semicircular geometry and a coupling element with a cylindrical geometry, wherein this cylindrical geometry can preferably be arranged in the semicircular geometry of the toothing recess, a particularly good releasable connection between coupling element and counterpart coupling element that can be produced quickly can be achieved. In particular, jamming of the coupling element in the toothing recess can be avoided. Furthermore, in the case of the coupling element being positioned between two toothing recesses, a quick connection between coupling element and counterpart coupling element can nevertheless be achieved in that a tangential movement of the coupling element and/or of the counterpart coupling element is carried out, with the result that the coupling element can be positioned in the toothing recess. 
     A further preferred development of the rotor arresting device is distinguished by the fact that the rotor arresting device comprises a plurality of counterpart coupling elements which are preferably designed as semicircular toothing recesses and furthermore are spaced apart from one another by preferably less than 45 degrees, and/or less than 30 degrees, and/or less than 25 degrees, and/or less than 20 degrees, and/or less than 15 degrees, and/or less than 10 degrees, and/or less than 7.5 degrees, and/or less than 5 degrees, and/or less than 2 degrees, and/or less than 1 degree. 
     Furthermore, there is preferably provision that the rotor arresting device comprises an emergency power supply which is preferably designed as one, two or more power accumulators, wherein the power accumulators are or comprise batteries in particular. Such an emergency power supply can ensure a secure supply of the components of the rotor arresting device, with the result that rotor arresting can be ensured even during a power failure. 
     According to a further particularly preferred embodiment variant of the rotor arresting device, the latter comprises a control device which is arranged and designed to move the coupling element by means of the first actuator and/or by means of the second actuator from a release position into an arresting position, wherein the coupling element is releasably connected, preferably in a form-fitting manner, to the counterpart coupling element in the arresting position. In a further preferred embodiment variant of the rotor arresting device, the latter comprises a control device which is arranged and designed to move the coupling element in a first tangential direction of the rotation assembly by means of the first actuator and/or by means of the second actuator, wherein one of the actuators is preferably switched to a force-free state. The movement in the tangential direction is preferably provided by the first setting direction component or the second setting direction component of the coupling movement. 
     It is furthermore preferable that the rotor arresting device comprises a control device which is arranged and designed to move the first coupling element by means of the first actuator and/or by means of the second actuator of a first coupling device and/or the second coupling element by means of the first actuator and/or by means of the second actuator of a second coupling device from a release position into an arresting position, wherein the first coupling element and/or the second coupling element are or is releasably connected, preferably in a form-fitting manner, to one, two or more counterpart coupling elements. 
     A further particularly preferred embodiment variant of the rotor arresting device provides that the latter comprises a control device which is arranged and designed to move the first coupling element in a first tangential direction of the rotation assembly by means of the first actuator and/or by means of the second actuator, wherein one of the actuators is preferably switched to a force-free state, and/or to move the second coupling element in the first tangential direction of the rotation assembly by means of the first actuator and/or by means of the second actuator of the second coupling device, wherein one of the actuators is preferably switched to a force-free state. Since the setting direction components of the first and second coupling movement are directed in opposite directions, preferably only one actuator is actively involved, and the other actuator is switched to a force-free state, when carrying out such a movement in the tangential direction. It can thus be ensured that the movement of an actuator occurs only in the pressure direction or main force direction. Furthermore preferably, one of the actuators is not switched to a force-free state, but is loaded with a force which is less than the force of the other actuator, with the result that the stability of the coupling device can be improved. 
     Moreover, it is preferable that the rotor arresting device comprises a control device which is arranged and designed to move the first coupling element into an arresting position, then to move the second coupling element into a release position and in a second tangential direction and then to move the first coupling element in the first tangential direction, to move the second coupling element into an arresting position, then to move the first coupling element into a release position and in a second tangential direction and then to move the second coupling element in the first tangential direction. A rotor arresting device controlled in such a way means that the counterpart coupling element can be successively moved in the first tangential direction. Thus, the rotation assembly of the wind turbine can be moved with many small steps in the first tangential direction. It goes without saying that this movement direction can also occur counter to the above-described direction of rotation, for example that the rotation assembly or the counterpart coupling element is moved in the second tangential direction and the movement of the coupling element in the release position in turn occurs in the first tangential direction. 
     In a particularly advantageous embodiment variant of the rotor arresting device, the latter comprises a control device which is arranged and designed to move the first coupling element into an arresting position, then to move the second coupling element into a release position and in a second tangential direction and then to move the second coupling element into an arresting position. A control device arranged and designed in such a way can ensure that a movement in the tangential direction occurs only if both coupling elements of the two coupling devices present are situated in an arresting position. In a further preferred embodiment variant of the rotor arresting device, the latter comprises a control device which is arranged and designed to move the counterpart coupling element in the first tangential direction by multiple movement of the coupling elements according to at least one of the above-described movement sequences. An advantageous design of a control device results if the latter has two or more of the above-described designs of the control device. 
     According to a further aspect of the present invention, provided is a wind turbine having a rotor, a rotation assembly connected to the rotor in a rotationally rigid manner, and a static assembly which is positionally fixed relative to the rotation assembly, comprising a rotor arresting device according to at least one of the above-described embodiment variants. 
     According to a further aspect of the present invention, provided is a method for arresting a rotor of a wind turbine, in particular of a wind turbine according to the previous aspect, comprising providing a rotor arresting device according to at least one of the above-described embodiment variants, moving the coupling element by means of the first actuator and/or by means of the second actuator from a release position into an arresting position, wherein the first coupling element is releasably connected, preferably in a form-fitting manner, to the counterpart coupling element in the arresting position. 
     This method allows a rotor which is braked to substantially zero to be arrested. A rotor which is braked to substantially zero is distinguished in particular by the fact that it has a speed of rotation of substantially zero. The rotor braked to substantially zero also has, at its rotation assembly, a rate or speed of rotation of substantially zero, with the result that the at least one coupling element can be guided by the first actuator and/or the second actuator by means of a coupling movement toward the counterpart coupling element on the rotation assembly, and a releasable, preferably form-fitting, connection is produced by correspondingly bringing up or connecting the coupling element to the counterpart coupling element. 
     In particular, it is preferable that the method comprises braking and/or positioning the aerodynamic rotor before it is arrested. 
     In a particularly preferred embodiment variant of the method, the latter comprises moving the coupling element in a first tangential direction of the rotation assembly by means of the first actuator and/or by means of the second actuator, wherein one of the actuators is preferably switched to a force-free state. This method step affords the possibility that the rotor is arrested at a specific position. This occurs in particular by virtue of the fact that the rotation assembly, and hence also the rotor, is rotated by means of one of the actuators. This rotation occurs in particular by virtue of the fact that the first actuator and/or the second actuator move or moves the counterpart coupling element in a tangential direction of the rotation assembly, wherein the coupling element is situated in an arresting position in the meantime. Since the setting direction components of the coupling movement of the first actuator and of the second actuator are in opposite directions, it is particularly preferable that one of the actuators is switched to a force-free state during this movement, with the result that the force of the one actuator is not in opposition to the force of the other actuator. 
     According to a further aspect of the present invention, provided is a method for arresting a rotor of a wind turbine, in particular of a wind turbine according to an above-described embodiment variant, comprising providing a first rotor arresting device having a first coupling element, a first actuator and a second actuator according to at least one of the above-described embodiment variants, and providing a second rotor arresting device having a second coupling element, a third actuator and a fourth actuator according to at least one of the above-described embodiment variants, moving the first coupling element by means of the first actuator and/or by means of the second actuator and/or moving the second coupling element by means of the third actuator and/or by means of the fourth actuator from a release position into an arresting position, wherein the first coupling element and/or the second coupling element are or is releasably connected, preferably in a form-fitting manner, to the counterpart coupling element in the arresting position. 
     The second rotor arresting device comprises a third actuator and a fourth actuator, wherein the third actuator and the fourth actuator can be designed in a substantially identical or similar manner to the first actuator and/or the second actuator of the first rotor arresting device. Furthermore, the second rotor arresting device likewise comprises, in principle, a total of two actuators, namely the third actuator and the fourth actuator. This method allows the rotor or the rotation assembly having a counterpart coupling element to be arrested by two coupling elements. 
     In particular, it is preferable that the method comprises braking and/or positioning of the aerodynamic rotor before it is arrested. 
     According to a preferred embodiment variant of the method, the latter comprises moving the first coupling element in a first tangential direction of the rotation assembly by means of the first actuator and/or by means of the second actuator, wherein one of the actuators is preferably switched to a force-free state, and/or moving the second coupling element in the first tangential direction of the rotation assembly by means of the third actuator and/or by means of the fourth actuator, wherein one of the actuators is preferably switched to a force-free state. 
     A further preferred development of the method is distinguished by the method step of moving the first coupling element into an arresting position, then moving the second coupling element into a release position and in a second tangential direction and then moving the first coupling element in the first tangential direction, moving the second coupling element into an arresting position, then moving the first coupling element into a release position and in a second tangential direction and then moving the second coupling element in the first tangential direction. 
     Furthermore, the method preferably comprises the step of moving the first coupling element into an arresting position, then moving the second coupling element into a release position and in a second tangential direction and then moving the second coupling element into an arresting position. According to a further preferred embodiment variant of the method, the latter comprises the step of moving the counterpart coupling element in a first tangential direction by repeating at least one of the steps of the above-described embodiment variants. 
     The methods according to the invention and possible developments thereof have features or method steps which make them particularly suitable to be used for a rotor arresting device according to the invention and developments thereof. For further advantages, embodiment variants and embodiment details of these further aspects and possible developments thereof, reference is also made to the above description of the corresponding features and developments of the rotor arresting device. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Preferred embodiments of the invention will be explained by way of example with reference to the appended figures, in which: 
         FIG. 1  shows a schematic view of an exemplary embodiment of a wind turbine; 
         FIG. 2  shows a schematic side view of an exemplary embodiment of a generator of a wind turbine according to  FIG. 1 ; 
         FIG. 3  shows a schematic three-dimensional view of an exemplary embodiment of a rotor arresting device; 
         FIG. 4  shows a three dimensional view of a detail of an exemplary embodiment of a rotor arresting device. 
     
    
    
     In the figures, identical or substantially functionally identical or similar elements are designated with the same reference signs. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a schematic view of an exemplary embodiment of a wind turbine.  FIG. 1  shows, in particular, a wind turbine  100  having a tower  102  and a nacelle  104 . An aerodynamic rotor  106  having three rotor blades  108  and a spinner  110  is arranged on the nacelle  104 . In the installed state and/or in the operating state, the aerodynamic rotor  106  is set into a rotational movement by the wind and thus drives a generator in the nacelle  104 . The aerodynamic rotor  106  thus also drives an electrodynamic rotor of a generator which is directly or indirectly coupled to the aerodynamic rotor  106 . The electric generator is arranged in the nacelle  104  and generates electrical energy. The pitch angles of the rotor blades  108  can be varied by means of pitch motors on the rotor blade roots of the respective rotor blades  108 . 
       FIG. 2  schematically shows an inner-rotor generator  130  of the wind turbine  100  in a side view. It has a stator  132  and an electrodynamic rotor  134  mounted rotatably with respect thereto and is fastened by its stator  132  to a machine support  138  via a journal  136 . The stator  132  has a stator support  140  and stator plate bundles  142  which form stator poles of the generator  130  and are fastened to the stator support  140  via a stator ring  144 . The electrodynamic rotor  134  has rotor pole shoes  146  which form the rotor poles and are mounted so as to be rotatable about the axis of rotation  152  via a rotor support  148  and bearings  150  on the journal  136 . The stator plate bundles  142  and rotor pole shoes  146  are separated by only a narrow air gap  154  which is a few millimeters thick, in particular less than 6 mm, but has a diameter of several meters, in particular more than 4 m. The stator plate bundles  142  and the rotor pole shoes  146  each form a ring and are together also ring-shaped, with the result that the generator  130  is a ring generator. As intended, the electrodynamic rotor  134  of the generator  130  rotates together with the rotor hub  156  of the aerodynamic rotor, of which starts of rotor blades  158  are indicated. 
     The inner-rotor generator  130  and the further shown elements of the wind turbine  100  comprise a static assembly  13  and a rotation assembly  14 , wherein the static assembly  13  is enclosed by a dashed line for illustration. The static assembly  13  of this exemplary wind turbine comprises, for example, the machine support  138 , the stator  132  with stator support  140 , stator ring  144  and stator plate bundles  142 , and the journal  136 . The rotation assembly  14  of the partially shown wind turbine from  FIG. 2  comprises, inter alia, the electrodynamic rotor  134  with the rotor support  148 . These elements are connected to the aerodynamic rotor in a rotationally rigid manner and preferably have a common axis of rotation  152 . The elements of the static assembly are arranged in a positionally fixed manner in relation to these elements of the rotation assembly. The static assembly comprises, for example, the machine support  138 , the stator  132  with stator support  140 , stator ring  144  and stator plate bundles  142 , and the journal  136 . As will be described below, rotor arresting devices according to the invention can be used to arrest the aerodynamic rotor  106 . 
       FIG. 3  shows a schematic three-dimensional view of an exemplary embodiment of a rotor arresting device.  FIG. 3  shows, in particular, a rotor arresting device  1  having a first coupling device  210 , a second coupling device  220 , a third coupling device  230 , a fourth coupling device  240 , a fifth coupling device  250  and a sixth coupling device  260 , each of which devices being arranged on a static assembly  200  which is positionally fixed relative to a rotation assembly. Moreover, the rotor arresting device  1  has a counterpart coupling device  120 . The static assembly  200  has a ring-shaped geometry which has a center axis. The static assembly  200  also has a total of six projections, for example projection  202  or  204 , which are arranged equidistantly on the outer radial circumferential surface of the static assembly. The counterpart coupling device  120 , likewise ring-shaped, is arranged coaxially to the static assembly  200  and is preferably arranged on a rotation assembly (not shown) in a rotationally rigid manner. 
     The counterpart coupling device  120  has, moreover, a plurality of counterpart coupling elements which are designed here in the present case as toothing recesses. By way of example, the toothing recesses  124  and  126  are provided here with a reference sign, these two adjacent toothing recesses  124 ,  126  forming a tooth  122 . The toothing recesses are arranged equidistantly on the inner circumferential surface of the counterpart coupling device  120 . The toothing recesses are interrupted in certain regions in the axial direction. The interrupted part has a radius with respect to the center axis of the counterpart coupling device  120  which is greater than or equal to the radius from a low point of one of the toothing recesses to the center axis. It is thus possible for a cylindrical coupling element to be arranged in the toothing recesses and not to be influenced by the interrupted part. 
     All the toothing recesses on the counterpart coupling device  120  are designed in such a way that coupling elements  212 ,  222 ,  232 ,  242 ,  252 ,  262  can be arranged in these toothing recesses. The coupling elements  212  to  262  have a cylindrical geometry, the cylinder axis being oriented substantially parallel to the center axis of the static assembly  200  and of the counterpart coupling device  120 . It is thus possible for the coupling elements  212  to  262  to have a part of their radial circumferential surface arranged within the toothing recesses, which are here in the present case semicircular. As a representative of all the coupling devices  210 ,  220 ,  230 ,  240 ,  250 ,  260  the detailed design of the coupling devices will be explained below on the basis of the first coupling device  210 . 
     The coupling device  210  has a first actuator  213  and a second actuator  216 . The first actuator  213  comprises a hydraulic cylinder  214  with an extendable cylinder element  215 . Analogously to the first actuator  213 , the second actuator  216  likewise has a hydraulic cylinder  217  with an extendable cylinder element  218 . The first actuator  213  extends from a first end to a second end. The first actuator  213  is arranged by the first end on a first projection  202  of the static assembly  200  so as to be rotatable about an axis parallel to the center axis of the static assembly  200 . The first coupling element  212  is arranged on the second end of the actuator  213 , in particular on the end of the cylinder element  215  that faces away from the hydraulic cylinder  214 . The second actuator  216  likewise extends from a first end to a second end. The second actuator  216  is likewise arranged by the first end on the static assembly  200 . In particular, the second actuator  216  is arranged by its first end on a second projection  204 , wherein the second projection  204  is arranged adjacent to the first projection  202 . On the second end of the second actuator  216 , in particular on the end of the cylinder element  218  that faces away from the hydraulic cylinder  217 , the second actuator  216  is likewise rotatably connected to the first coupling element  212 . 
     In the completely retracted state, that is to say that the cylinder elements  215 ,  218  are arranged as far as possible within the hydraulic cylinders  214 ,  217 , the first actuator  213  and the second actuator  216  are oriented substantially tangentially to the static assembly  200 . The coupling element is then situated in a release position and is in particular not releasably connected to one of the counterpart coupling elements, for example  124 ,  126 . If the cylinder elements  215 ,  218  are now extended from the hydraulic cylinders  214 ,  217 , the coupling element  212  moves with a coupling direction component in the direction of the counterpart coupling element  120 . With sufficient extension of the cylinder elements  215 ,  218 , the coupling element  212  is situated, with corresponding tangential positioning, in one of the toothing recesses of the counterpart coupling element  120 . 
     The counterpart coupling device  120  can be securely arrested relative to the static assembly  200  through the arrangement of the coupling element  212  in one of the recesses of the counterpart coupling element. This is achieved in particular in that tangential forces of the counterpart coupling device are channeled via the coupling element into the actuators and from there are channeled to the static assembly  200 . 
     Moreover, the counterpart coupling device  120  can also be rotated by the provided coupling devices  210  to  260  relative to the static assembly  200  in the tangential direction T. This preferably occurs by the first actuators extending their cylinder elements and the second actuators of the coupling device being switched to a force-free state. The rotation occurs in particular by virtue of the fact that the second coupling devices exert a smaller tangential force on the counterpart coupling device than is caused by the cylinder elements of the first actuators. After the first actuators have completely extended the cylinder elements, there can at first not take place any further rotation of the counterpart coupling device in relation to the static assembly  200 . A coupling element of a coupling device is then preferably successively set back again into an arresting position counter to the direction of rotation, with the result that the coupling element is again arranged within a toothing recess and the coupling elements can carry out a repeated movement in the tangential direction of the desired direction of rotation. 
       FIG. 4  shows a three-dimensional view of a detail of an exemplary embodiment of a rotor arresting device. The rotor arresting device  1 ′ comprises a coupling device  301  having a first actuator  310  and a second actuator  350 , wherein the two actuators  310 ,  350  extend from a first end to a second end in an analogous manner to the previous description, wherein the first ends of the actuators  310 ,  350  are arranged on the static assembly on two adjacent projections  302 ,  303 , and the second ends are each arranged on an individual coupling element  305 . The coupling element  305  is situated in an arresting position in which the coupling element  305  is releasably connected to a counterpart coupling element of a counterpart coupling device  120 ′. In the present case, this connection is produced in a form-fitting manner in that the cylindrical coupling element  305  is arranged in a semicircular toothing recess. 
     Particularly evident in the present case is the rotatable arrangement of the actuators  310 ,  350  on the static assembly  300  and on the coupling element  305 . The actuators  310 ,  350  are each fastened at their first end to the static assembly by a bolt receiving element  313 ,  353  and a bolt  314 ,  354 . In the present case, the axis of rotation is again oriented parallel to the center axis of the static assembly  300 . 
     The actuators  310 ,  350  each have, in particular in a region adjoining the first end, a preferably circular first opening, and are arranged with this region between openings of the bolt receiving elements  313 ,  353 , with the result that a bolt can be arranged in the openings of the bolt receiving element, and is thus also arranged in the first openings of the first ends of the first actuator  310  and second actuator  350 , and therefore nonrotational movements of the first ends of the actuators  310 ,  350  relative to the static assembly  300  are substantially prevented. It is thus possible to realize a rotatable arrangement of the actuators  310 ,  350  on the static assembly  300 . The coupling element  305  is designed in the present case as a cylindrical element and can be used in the present case, also acting as a bolt, to connect the first actuator  310  and the second actuator  350  to one another. In an analogous manner to the counterpart coupling device  120 , the counterpart coupling device  120 ′ has a plurality of counterpart coupling elements which are designed as semicircular toothing recesses. 
     The counterpart coupling device  120 ′ can be rotated relative to the static assembly  300  through this arrangement. This occurs in particular by virtue of the fact that a tangential force of the one actuator is greater than the oppositely directed tangential force of the respective other actuator. The actuator which is not used for the rotation of the counterpart coupling device  120 ′ is preferably switched to a force-free state. It is thus possible to achieve a preferably successive rotation of the counterpart coupling device  120 ′ in relation to the static assembly  300 . 
     Rotor arresting devices  1 ,  1 ′ as shown in  FIG. 3  and in  FIG. 4  can also be used for arresting the aerodynamic rotor  106  as shown in  FIG. 1  in that a counterpart coupling element  124 ,  126  is arranged in a rotationally rigid manner the rotation assembly and at least one coupling device  210 ,  220 ,  230 ,  240 ,  250 ,  260 ,  301  is arranged on the static assembly. For example, the counterpart coupling element  124 ,  126  can be arranged in a rotationally fixed manner on the end side of the rotor support  148  that faces the machine support  138 . The at least one coupling device  210 ,  220 ,  230 ,  240 ,  250 ,  260 ,  301  is then preferably arranged on the end side of the stator support  140  that faces away from the machine support, with the result that the at least one coupling element  212 ,  222 ,  232 ,  242 ,  252 ,  262 ,  305  of the at least one coupling device  210 ,  220 ,  230 ,  240 ,  250 ,  260 ,  301  can be releasably connected to a counterpart coupling element  124 ,  126  of the counterpart coupling device  120 ,  120 ′. 
     The rotor arresting devices  1 ,  1 ′ shown in  FIGS. 3 and 4  can be arranged, to arrest an aerodynamic rotor  106 , on stator supports  140  and rotor supports  148  of inner-rotor generators and also of outer-rotor generators. 
     Particularly by virtue of the fact that the actuators, which are preferably designed as hydraulic elements, are arranged on the static assembly, the supply lines and control devices for them can be arranged without great difficulties. Moreover, many elements are situated on a rotation assembly of a wind turbine, on which elements a counterpart coupling device  120 ,  120 ′ can be arranged. Thus, a secure rotation of a rotor of a wind turbine can be achieved, with it being possible for the proposed rotor arresting device to be designed in a cost-effective manner. Moreover, given the large number of coupling devices to be arranged, said device offers a high safety factor which simplifies mounting and demounting, maintenance and repair work and other work in the region of the rotor and/or of the nacelle and reduces the effort for ensuring a controlled operation. 
     REFERENCE SIGNS 
     
         
         
           
               1 ,  1 ′ Rotor arresting device 
               13  Static assembly 
               14  Rotation assembly 
               100  Wind turbine 
               102  Tower 
               104  Nacelle 
               106  Rotor 
               108  Rotor blade 
               110  Spinner 
               120 ,  120 ′ Counterpart coupling device 
               122  Tooth 
               124  First toothing recess 
               126  Second toothing recess 
               130  Inner-rotor generator 
               132  Stator 
               134  Electrodynamic rotor 
               136  Journal 
               138  Machine support 
               140  Stator support 
               142  Stator plate bundles 
               144  Stator ring 
               146  Rotor pole shoes 
               148  Rotor support 
               150  Bearings 
               152  Axis of rotation 
               154  Air gap 
               156  Rotor hub 
               158  Rotor blade 
               200 ,  300  Static assembly 
               202  First projection 
               204  Second projection 
               210  First coupling device 
               212  First coupling element 
               213  First actuator 
               214  Hydraulic cylinder 
               215  Cylinder element 
               216  Second actuator 
               217  Hydraulic cylinder 
               218  Cylinder element 
               220  Second coupling device 
               222  Second coupling element 
               230  Third coupling device 
               232  Third coupling element 
               240  Fourth coupling device 
               242  Fourth coupling element 
               250  Fifth coupling device 
               252  Fifth coupling element 
               260  Sixth coupling device 
               262  Sixth coupling element 
               301  Coupling device 
               302 ,  303  Projections 
               305  Coupling element 
               310  First actuator 
               312  Hydraulic cylinder 
               313  Bolt receiving element 
               314  Bolt 
               315  Cylinder element 
               316  Arrangement element 
               350  Second actuator 
               352  Hydraulic cylinder 
               353  Bolt receiving element 
               354  Bolt 
               355  Cylinder element 
               356  Arrangement element 
             T Tangential direction