Abstract:
An assembly for use in a drive-train of a wind turbine having a transmission, a generator and a module. The module includes a shaft or hub, at least one bearing and a support structure. The shaft of the module or the hub is mounted by the bearing so as to rotate in the support structure. The shaft or the hub can be connected in a rotationally fixed manner to a shaft of the transmission. A rotor of the generator can be fixed to the shaft of the module or to the hub. The support structure can be fixed to a housing of the transmission or the generator. At least one assembly safety device is provided in order to be able to fix the rotor of the generator. When the rotor of the generator is fixed by way of the assembly safety device, the module can be fitted and removed.

Description:
[0001]    This application is a National Stage completion of PCT/EP2015/052820 filed Feb. 11, 2015, which claims priority from German patent application serial no. 10 2014 204 479.0 filed Mar. 11, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention concerns an assembly for use in the drive-train of a wind turbine. 
       BACKGROUND OF THE INVENTION 
       [0003]    During the operation of a wind turbine defects can occur. To keep maintenance costs as low as possible, it is important for defective components to be easily accessible and able to be replaced in a simple manner. In the wind turbines known from the prior art, the disassembly of the generator in particular is difficult. 
         [0004]    From the document EP 0811764 B1 a wind turbine is known, in which a machine support serves for the attachment of a transmission and a generator. In this case the transmission and the generator are on opposite sides of the machine support. In addition a housing of the generator with a stator is fixed onto the machine support. 
         [0005]    A sun gear shaft serves as the output shaft of the transmission. This passes through the machine support into the generator. A rotor of the generator is mounted on a tubular support structure fixed to the machine support. The support structure is so arranged that the sun gear shaft extends through the support structure. The spline teeth and a sun gear connected integrally to the sun gear shaft are on opposite sides of the support structure. 
         [0006]    Fixed on the support structure are the inner races of two bearings. Their outer races are fixed in a hollow shaft that surrounds the support structure. The hollow shaft is driven by the sun gear shaft by way of spline teeth. The hollow shaft serves as a pole wheel carrier. 
         [0007]    To disassemble the generator, first its housing together with all the generator components fixed in the housing have to be removed. The now exposed rotor must be removed in order to access its bearing. Although part of the sun gear shaft is now accessible, the sun gear shaft cannot be taken off. For that purpose the transmission would have to be removed. 
       SUMMARY OF THE INVENTION 
       [0008]    The purpose of the present invention is to design a drive-train of a wind turbine so as to avoid the disadvantages inherent in the prior art systems described at the start. In particular the accessibility of individual components of the drive-train, and hence the ease of maintaining it, should be improved. 
         [0009]    An assembly according to the invention for use in the drive-train of a wind turbine comprises a transmission, a generator and a module. The module has a shaft or a hub, at least one bearing and a support structure. The shaft of the module or the hub is mounted and able to rotate in the support structure by means of a bearing. 
         [0010]    For the arrangement of the shaft of the module or hub and the support structure relative to one another, two alternatives are conceivable. In a first version the shaft of the module is at least partially within the support structure, or it runs through the support structure. In this case the inner race of the bearing is fixed onto the shaft of the module. The outer race of the bearing is fixed in the support structure. In a second version the support structure is arranged at least partially within the hub. The inner race of the bearing is then fixed onto the support structure. Correspondingly, the outer race of the bearing is fixed in the hub. 
         [0011]    Preferably, the bearing allows just one rotary degree of freedom of the shaft of the module or the hub. Thus, the shaft or hub cannot tilt about an axis perpendicular to its rotational axis. The shaft of the module or hub is in this case mounted exclusively by means of the at least one bearing. Further bearings are not needed. Correspondingly, this means that the shaft or hub is mounted exclusively in the support structure. In particular therefore, every bearing by means of which the module shaft or hub is mounted, is fixed in the support structure. There are preferably two bearings. 
         [0012]    The shaft of the module or the hub and a shaft of the transmission can form a working surface pair, so that a rotationally fixed connection of the shaft of the module or the hub with the transmission shaft is formed. This enables the transmission of torque from the transmission shaft to the shaft of the module or the hub. 
         [0013]    The transmission shaft can in particular be an output shaft. An output shaft of a transmission is understood to be a shaft with meshing teeth, such that the shaft is acted upon by an output torque of the transmission by way of the teeth. 
         [0014]    In particular, the transmission shaft can be in the form of a sun gear shaft. 
         [0015]    Preferably, the connection between the transmission shaft and the shaft of the module or hub can be released. Thus, in particular the transmission shaft and the shaft of the module or hub are not connected to one another integrally, but as two parts. Regarding this, particularly suitable is a spline teeth connection such that the shaft of the module or hub forms a first part of the spline connection and the transmission shaft forms a second part thereof. Thus, the module&#39;s shaft or hub and the transmission shaft can be plugged one into the other to produce the spline connection. 
         [0016]    A rotor of the generator can be fixed to the shaft of the module or the hub. 
         [0017]    A rotor is generally understood to be the non-stationary part of a rotary generator. 
         [0018]    Fixing a first component to a second component is generally understood to mean the forming of a connection between the first and second components, which opposes any relative movement between the first and second components. Such fixing may be indirect, i.e. involving a third component, or direct, i.e. without any third component. 
         [0019]    In the case of indirect fixing, the first component is fixed to the third component. The third component, in turn, is then fixed to the second component. In a direct connection of the first to the second component the two components may be joined by friction force, or with interlock, or by a material-merged method. This is expressed by the formulation “the first component is joined to the second component”. Thus, when the first component is joined to the second component, the first component is fixed directly onto the second component. In particular, there is then a frictional, interlocked or material-merged connection between the first and second components. 
         [0020]    Preferably, the rotor of the generator is fixed exclusively to the shaft of the module or the hub. Thus, besides the shaft of the module or the hub and a possible third component by way of which the rotor can be fixed indirectly to the module&#39;s shaft or the hub, there are no other components to which the rotor is fixed—whether directly or indirectly. 
         [0021]    Since the shaft of the module or the hub is mounted to rotate about just one rotational axis, by virtue of its attachment to the module&#39;s shaft or the hub the rotor can rotate about the same rotational axis. Thus, the shaft of the module or the hub restrict any translational degrees of freedom of the rotor of the generator and allow exactly two rotational degrees of freedom of the rotor of the generator. 
         [0022]    The transmission, the module and the generator are preferably arranged so that either the shaft of the module or the transmission shaft extends through the support structure and correspondingly through the bearing. In particular, the support structure and the bearing can extend coaxially with the shaft of the module and/or the shaft of the transmission, around the shaft of the module and/or the transmission shaft. 
         [0023]    Such an arrangement is produced when the generator and the transmission are located at least partially on two different sides of the support structure and the bearing. At least part of the transmission and at least part of the generator are therefore arranged on different sides of a plane extending through the support structure and/or through the hearing. A load path of a torque from one of the shafts of the transmission, via the shaft of the module, to the rotor of the generator, directed coaxially with the rotational axis of the bearing and the rotor of the generator, passes through the bearing. 
         [0024]    The support structure can be fixed on a housing of the transmission or of the generator. Preferably, the support structure and the housing can be bolted to one another. Furthermore, it is preferable if only the housing serves for the fixing of the support structure. Thus, the support structure is not fixed to any other components. In particular, it is preferable for the fixing of the support structure to the housing to be releasable. 
         [0025]    According to the invention, an assembly safety device is provided. This is a device, different from the module and from any part thereof, for fixing the rotor of the generator, preferably in a fixed position, so that all translational and rotational movements of the rotor of the generator are prevented. The assembly safety device is preferably designed such that it can be removed. 
         [0026]    Advantageously, there are in particular two versions of the assembly safety device. In a first version the rotor of the generator can be fixed to the housing of the transmission by means of the assembly safety device. Fixing of the transmission to the housing is preferred, since this enables the demounting of the housing of the generator and makes the assembly safety device simply accessible. 
         [0027]    In a second version of the assembly safety device, the rotor of the generator can be fixed to the housing of the generator by means of the assembly safety device. 
         [0028]    According to the invention, the module can be fitted and removed without having to dismantle components of the transmission, in particular its shafts, or components of the generator, in particular its rotor. 
         [0029]    The fixing of the support structure to the housing of the transmission or of the generator is preferably designed to be releasable. Moreover, it is preferable to connect the rotor of the generator releasably to the shaft or hub. Furthermore, the rotationally fixed connection of the shaft of the module or of the hub to the transmission shaft is also preferably releasable. 
         [0030]    In the operating condition, the shaft of the module or the hub serves to support the rotor of the generator. However, if the module and therefore its shaft or hub has been removed, that support is lacking. In order to fix the rotor of the generator in such a case, the assembly safety device is provided. 
         [0031]    Particularly for maintenance purposes the ability to fit and take off the module is advantageous. In the event of damage this reduces the time required for repairing or replacing one of the components of the module. It is not necessary—as it is with the systems known from the prior art—to dismantle the generator component by component in order to access the damaged component. Instead a module can be prepared, for example in a workshop, and exchanged with the module containing the damaged components. 
         [0032]    Furthermore, the weight of the components that have to be lifted by a crane for fitting and dismantling operations is reduced. Whereas previously an external crane was usually needed in order to separate the generator from the transmission, the module can be fitted and removed using a crane integrated in the engine gondola of the wind turbine. This saves time and eliminates the costs incurred for the provision of the external crane. 
         [0033]    It is also advantageous that the rotor of the generator can remain in its place, since the rotor of the generator as a rule comprises strong permanent magnets. If the rotor of the generator has to be removed, there is a risk that ferromagnetic components inside the engine gondola might be attracted. This could cause injury to assembly workers working in the engine gondola. There is also some risk of damaging the rotor. 
         [0034]    A transport safety device can be provided in order to be able to transport the generator without the module. By means of such a transport safety device the rotor of the generator can be fixed to the housing of the generator. This is particularly important when the module is manufactured by the maker of the transmission and the generator (without the module) is supplied by a generator manufacturer. Depending on the design of the assembly, the assembly safety device can also be used as the transport safety device. 
         [0035]    In a particularly preferred further development of the invention, the module itself fulfills the function of a transport safety device. For that purpose at least a first part of the generator housing can be fixed at least to the support structure. The housing of the transmission is in that case designed such that the support structure can be fixed to the transmission housing. 
         [0036]    The fixing of the first part of the generator housing to the support structure makes it possible to fit and remove the module and the generator as a unit. The module can thus be fitted and removed while at least the first part of the generator housing is fixed to the support structure. 
         [0037]    Such a further development puts a manufacturer of the generator in a position to use the module for testing the generator. The generator is then delivered with the module to a manufacturer of the transmission, and during this the module can serve as a transport safety device. 
         [0038]    Besides the rotor of the generator, in another preferred further development of the invention the stator of the generator also remains in place when the module is fitted and removed. According to this further development the module can be fitted and removed while at least a first part of the generator housing is fixed to the housing of the transmission. In this case the generator housing is preferably designed to carry the stator of the generator. 
         [0039]    In general terms a stator is that part of a generator which is static and does not move. 
         [0040]    The support structure and thus also the bearing are preferably positioned outside the housing of the transmission. In particular therefore, the support structure and the bearing are outside the transmission housing before they are fitted and after they have been fitted, i.e. after the support structure has been fixed to the transmission housing or the generator housing. 
         [0041]    Also preferred is to arrange the support structure and thus also the bearing inside the generator housing in the assembled condition. When the support structure has been fixed to the housing of the transmission or the generator, it is accordingly inside the generator housing. 
         [0042]    To be able to maintain the module, the housing of the generator is preferably designed in such manner that after the fixing of the support structure to the housing of the transmission or the generator has been released, and after fixing of the rotor of the generator to the shaft or hub has also been released and the rotor of the generator has been secured by means of the assembly safety device, the module can be taken out of the housing of the generator. For this, the module must in particular be accessible from outside through the generator housing. Thus, the module can be fitted and removed while at least a first part of the generator housing is fixed to the transmission housing. 
         [0043]    The first part of the generator housing preferably has an opening through which the module is accessible for purposes of fitting and removal. In particular, for fitting and removal, the module can be inserted into the generator housing and removed therefrom through the opening. 
         [0044]    Preferably, the generator housing is made in at least two parts. In this case a cover forms a second part of the generator housing. The cover can be fitted onto the first part of the generator housing so as to close off the opening. For the fitting and removal of the module, the cover can be taken off so that the opening is unobstructed. 
         [0045]    With a two-part housing having the above-described cover as its second part, the assembly can be designed such that the rotor can be fixed to the first part of the generator housing by means of the assembly safety device. 
         [0046]    At least one fixing element can be provided for fixing the support structure to the housing of the transmission or the generator. At least one further fixing element can be provided for fixing at least the first part of the generator housing to the support structure. In particular, releasable fixings of the support structure to the housing of the transmission or the generator and of the first part of the generator housing to the support structure can be made by means of such a fixing element. 
         [0047]    To be able to fit and remove the module, however, the fixing elements must be accessible. Accordingly, in another preferred further development the rotor of the generator has a first intermediate component or the hub has at least a first cut-out, through which at least one of the fixing elements can be inserted and/or removed. 
         [0048]    The first intermediate component is a component that can be provided as a connection between the rotor of the generator and the shaft of the module or the hub. Thus, the rotor of the generator can be joined to the first intermediate component. Correspondingly, the intermediate component can be joined to the shaft of the module or to the hub. 
         [0049]    Usually, the module is arranged offset relative to the rotor of the generator on the transmission side, i.e. in the direction toward the transmission. Correspondingly, the rotor of the generator is arranged offset relative to the module on the generator side, i.e. in the direction toward the generator. However, to be able to fit and remove the module while the rotor of the generator is fixed by means of the assembly safety device, in a preferred further development the rotor of the generator has a second cut-out through which the module can be at least partially inserted. This cut-out is preferably located centrally, i.e. the rotational axis of the rotor of the generator extends through the second cut-out. 
         [0050]    Depending on the design of the module in each case, various intermediate components may be needed for connection to the rotor of the generator or to the shaft of the transmission. The above-mentioned first intermediate component is preferably used, if the module is designed with a shaft, in order to connect the rotor of the generator to the shaft. The shaft can be arranged so that it projects into the housing of the transmission. Inside the housing of the transmission there is then an element, preferably a toothed spline, for connecting the transmission shaft to the shaft of the module in a rotationally fixed manner. 
         [0051]    In the case when the module is designed with a hub, the hub can be joined directly to the rotor of the generator. However, it is then preferred to use a second intermediate component to connect the hub rotationally fixed to the transmission shaft. In that case the hub is joined to the second intermediate component. Particularly preferably, the hub and the second intermediate component are connected releasably so that for the fitting and removal of the module the second intermediate component can be removes from the hub. Furthermore the second intermediate component is designed to form a rotationally fixed connection with the transmission shaft. Preferably, the second intermediate component is connected to the transmission shaft by spline teeth. 
         [0052]    To enable the fitting and removal of the module, in another preferred further development the first intermediate component and/or the second intermediate component can be removed. In particular it is preferable for the first and/or the second intermediate component to be removable when the rotor of the generator is fixed by means of the assembly safety device while at least the first part of the generator housing is fixed to the transmission housing, and while the module is fitted, i.e. the support structure is fixed to the housing of the transmission or of the generator. 
         [0053]    That the first intermediate component can be removed as described above is particularly preferable if the first intermediate component has no cut-out. In that case it may be necessary to remove the first intermediate component in order to make accessible the fixing element serving to fix the support structure onto the housing of the transmission or of the generator. 
         [0054]    Stray currents produced by the generator can lead to sparking between the rolling elements and the rolling surfaces of a bearing. This results in damage to the bearing. In a preferred embodiment, therefore, the rotor of the generator is electrically insulated relative to the other components of the assembly by means of one or more insulators. For this, the hub or the first intermediate component consist of a first part and a second part, such that the rotor can be joined to the first part. The insulators serve to insulate the first part electrically relative to the second part. This prevents electric currents from flowing between the first and second parts. 
         [0055]    Furthermore, the insulators must ensure that the first part is fixed to the second part. Accordingly, a first insulator can be designed to support the first part in at least one radial direction and preferably in every radial direction relative to the second part. This can be done for example by arranging the first insulator radially between the first and second parts, so that a load path running radially is formed between the first and second parts by the first insulator. 
         [0056]    Particularly preferred is an embodiment having a second and a third insulator. These insulators are each clamped between the first part and the second part. The second part grips the first part and presses the second and third insulators against the first part. Thus, the second part clamps the first part between the second and third insulators. In that way, forces in opposite directions act upon the two insulators. 
         [0057]    By virtue of the described arrangement of the second and third insulators, the function of a slipping clutch can be realized. If torque from the second part transmitted by way of the second and third insulators remains below a certain threshold value, the second part is frictionally connected to the first part via the second and third insulators. The first and second parts then rotate at the same speed. 
         [0058]    In contrast, if the torque transmitted exceeds the threshold value, then slipping takes place between the first and the second insulator and the first and/or second part. This protects the transmission against torque peaks that can occur, possibly due to short-circuits in the generator or in the electricity supply. 
         [0059]    A method according to the invention for removing the module described from the assembly, comprises the following steps:
       if necessary, opening the generator or removing the cover of the generator housing;   fixing the rotor of the generator by means of the assembly safety device;   releasing the fixing of the generator rotor to the shaft or hub;   if necessary, removing the first intermediate component and/or the second intermediate component;   releasing the fixing of the support structure to the housing of the transmission or the generator, if necessary by removing the fixing element;   removing the module.       
 
         [0066]    These process steps are preferably carried out in the sequence indicated. The sequence given, however, is not conclusive. Thus, alternative embodiments of the method according to the invention with a different sequence of the process steps indicated are possible. 
         [0067]    By carrying out the converse process steps in the reverse sequence, the module can be fitted into the assembly. Such a process comprises the following steps:
       insertion of the module;   fixing the support structure onto the housing of the transmission or the generator;   if necessary, joining the rotor of the generator to the first intermediate component and joining the first intermediate component to the shaft of the module or to the hub, and/or forming a rotationally fixed connection between the second intermediate component and the transmission shaft and joining the second intermediate component to the hub;   fixing the rotor of the generator to the shaft of the module or to the hub;   removing the assembly safety device;   closing the housing of the generator.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0074]    Below, example embodiments of the invention are described, these being illustrated in the figures, in which the same indexes denote the same or functionally equivalent features. In detail, the figures show: 
           [0075]      FIG. 1 : A module for coupling a transmission to a generator, having an internal shaft; 
           [0076]      FIG. 2 : A first possibility for fitting and removing such a module; 
           [0077]      FIG. 3 : A second possibility for fitting and removing such a module; 
           [0078]      FIG. 4 : A module for coupling a transmission to a generator with an external hub; 
           [0079]      FIG. 5 : A possibility for fitting and removing such a module; 
           [0080]      FIG. 6 : An assembly safety device; 
           [0081]      FIG. 7 : A device for holding a transmission output shaft; 
           [0082]      FIG. 8 : A module with a transmission housing fixed on it; 
           [0083]      FIG. 9 : The fitting of such a module; and 
           [0084]      FIG. 10 : A module with a structure corresponding to the structure of the module according to  FIG. 8  and having a slipping clutch. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0085]    A first shaft  102  according to  FIG. 1  is inside a transmission housing  104 . By means of spline teeth  106  the first shaft  102  is connected in a rotationally fixed manner to a second shaft  108 . Like the first shaft  102 , the spline teeth  106  are inside the transmission housing  104 . In contrast, the second shaft  108  is only partly within the transmission housing  104 . Another part of the second shaft  108  projects out of the transmission housing  104 . 
         [0086]    The second shaft  108  is mounted to rotate in a support structure  112  by means of two bearings  110 . The inner races of the bearings  110  are fixed on the second shaft  108 . The outer races of the bearings  110  are fixed in the support structure  112 . The latter is joined to the transmission housing  104  by means of screw-bolts  114 . 
         [0087]    A first intermediate component  116  serves to connect the second shaft  108  to a rotor  118 . The rotor is connected to the first intermediate component  116  by screw-bolts  120 . Furthermore, the first intermediate component  116  is connected by screw-bolts  122  to a flange of the second shaft  108 . 
         [0088]    A generator housing  124  encapsulates the rotor  118 , the first intermediate component  116 , the support structure  112 , the bearings  110  and part of the second shaft  108 . The transmission housing  104  and the generator housing  124  are bolted to one another. 
         [0089]    To make the inside of the generator housing  124  accessible for maintenance work, the generator housing  124  has a removable cover  126 . The cover is bolted to another part of the generator housing  124 . 
         [0090]    The second shaft  108 , the bearings  110  and the support structure  116  constitute a module  128  that can be removed. This is made clear by  FIG. 2 . 
         [0091]    To remove the module  128 , first the inside of the generator housing  124  is made accessible by removing the cover  126 . Now, the rotor  108  can be fixed to the transmission housing  104  by means of assembly safety devices  202 , in order to remove the module  128 . For this it is necessary to make the screw-bolts  114  accessible. According to the procedure illustrated in  FIG. 2 , this happens when, after unscrewing the bolts  120  and  122 , the first intermediate component  116  is removed. During this the rotor  108  is held in position by the assembly safety devices  202 . 
         [0092]    Once the first intermediate component  110  has been removed, the screw-bolts  114  and the module  128  are accessible. When the screw-bolts  114  have been removed, the module  128  can be extracted. During this the first shaft  102  remains in place. 
         [0093]      FIG. 3  shows a modified procedure. In this case the first intermediate component  116  has cut-outs  302 . For each of the screw-bolts  114  there is a cut-out  302 . The cut-outs  302  are arranged so that the screw-bolts  114  are accessible through the cut-outs  302 . Thus, to remove the screw-bolts  114  the connection between the first intermediate component  116  and the flange of the second shaft  108  does not have to be released. Instead, the first intermediate component  110  remains on the flange of the second shaft  108 . 
         [0094]    The module  128  shown in  FIG. 4  has a hub  402  instead of the second shaft  108 . The support structure  112  is arranged so that it is partially within the hub  402 . By means of the bearings  110  the hub  402  is mounted and able to rotate in the support structure  112 . The inner races of the bearings  110  are fixed on the support structure  112 . The hub  402  is fixed to the outer races of the bearings  110 . 
         [0095]    The first shaft  102  projects out of the transmission housing  104  and extends through the support structure  112 . On the side of the support structure  112  opposite the transmission housing  104  are the spline teeth  106  by means of which the first shaft  102  is connected rotationally fixed to a second intermediate component  404 . 
         [0096]    The screw-bolts  122  serve to join the second intermediate component  404  to the hub  402 . In this way a rotationally fixed connection is formed between the first shaft  102  and the hub  402 . 
         [0097]    The screw-bolts  120  serve to connect the rotor  118  to the hub  402 . 
         [0098]    In the example embodiment shown in  FIG. 4 , the hub  402  covers the screw-bolts  114  by which the support structure  112  is fixed to the transmission housing  104 . In order to remove the module  128  as shown in  FIG. 5 , the hub is therefore provided with cut-outs  502 . The cut-outs  502  are arranged so that the screw-bolts  114  are accessible through the cut-outs  502  and can be inserted and removed through the cut-outs  502 . 
         [0099]    To remove the module  128 , first the cover  126  is taken off. When the rotor  118  has been secured by means of the assembly safety devices  202 , the module  128  can be taken out. After undoing the screw-bolts  120  and  122 , the second intermediate component  404  is first removed. Through the cut-outs  502  the screw-bolts  114  can now be removed. This releases the connection of the support structure  112  to the transmission housing  104 , so that the module  128  can be removed. During this the first shaft  102  remains in place. 
         [0100]      FIG. 6  shows as an example a design of the assembly safety device  202 . The assembly safety device  202  consists of an outer shell  602 , an inner shell  604  and a screw-bolt  606 . The outer shell  602  is set into a cut-out of the rotor  118 . Since the outer shell  602  is not accessible through the opening in the generator housing  124  left free by the cover  126 , the outer shell  602  is preassembled. 
         [0101]    To fix the rotor, the inner shell  604  is inserted into the outer shell  602  and screwed into it. For this, the outer shell  602  and the inner shell  604  form a matching thread pair  608 . When the inner shell  604  is screwed into the outer shell  602 , it comes in contact with the transmission housing  104 . An abutment  610  prevents the outer shell  602  from being pushed out of the rotor  118  during this. 
         [0102]    The screw-bolt  606  is inserted into the inner shell  604  screwed into the outer shell  602 . The transmission housing  104  has a thread  612  into which the screw-bolt  606  can then be screwed. The rotor  118  is then fixed to the transmission housing  104  thereby, so that the module  128  can be removed. 
         [0103]    When the module  128  is removed, there is a risk that the first shaft  102  may tilt in the radial direction and/or be displaced in the axial direction. A device whose purpose is to prevent that is shown in  FIG. 7 . The first shaft  102  has a groove  702  running concentrically to the first shaft  102 . In this groove  702  there engages a disk  704 . The disk  704  is fixed to a transmission component  706  which cannot move in the axial and radial directions. The component  706  can for example be a planetary carrier. Example embodiments are also conceivable, in which the transmission housing  104  itself is the component  706 . 
         [0104]    During normal operation there is an air gap between the disk  704  and the groove  702 . Under these circumstances the disk  704  and the groove  702  have no function. In particular, the rotation of the first shaft  102  is not impeded by the disk  704 . In contrast, when the module  128  is removed the disk  704  running in the groove  702  restricts the first shaft  102  and prevents it from tilting in the radial direction or moving in the axial direction. 
         [0105]    As shown in  FIG. 8 , further screw-bolts  802  can be provided for fixing the generator housing  124  to the support structure  112 . For this the generator housing  124  is designed so that it can be bolted to the transmission housing  104  and the support structure  112 . Besides the cut-outs  302 , through which the screw-bolts  114  for fixing the support structure  112  to the transmission housing  104  are accessible, the first intermediate component  116  has further cut-outs  804 . These cut-outs  804  serve to make accessible the screw-bolts  802  by which the generator housing  124  can be fixed to the support structure  112 . 
         [0106]    To remove the module  128  the screw-bolts  114  and the screw-bolts  802  are undone. During this the generator housing  124  remains bolted to the transmission housing  104 . 
         [0107]      FIG. 9  shows the assembly of the module  128  together with the rotor  118  and the generator housing  124 . The support structure  112  is fixed to the generator housing  124  by means of the screw-bolts  802 . By way of the first intermediate component  116  the rotor  118  is fitted onto the second shaft  108 . Thus, the rotor  108  is held in position by the second shaft  108  of the module  128 . 
         [0108]    The transmission housing  124 , the rotor  118  and the module  128  can be fitted as a unit onto the transmission housing  104 . For this the module  128  and the generator housing  124  are bolted to the transmission housing  104 . In addition, the spline teeth  106  are pushed together so that a rotationally fixed connection is formed between the first shaft  102  and the second shaft  108 . 
         [0109]      FIG. 10  shows a module  128  whose basic structure corresponds to that of the example embodiment shown in  FIG. 8 . However, in this case the first intermediate component  116  is designed as a slipping clutch. 
         [0110]    The first intermediate component  116  has a first part  1002  and a second part  1004 . By means of the bolt  120  the rotor  118  is joined to the first part  102 . 
         [0111]    A first insulator  1006  is positioned in the radial direction between the first part  1002  and the second part  1004 . Together with the first part  1002  and the second part  1004  the first insulator  1006  extends concentrically around the rotational axis of the rotor  118 , in such manner that a rotation of the first part  1002  about the rotational axis of the rotor  118  relative to the second part  1004  is possible. 
         [0112]    The second part  1004  comprises a clamping device  1008 . This applies a force which clamps the first part  1002  between a second insulator  1010  and a third insulator  1012 . The clamping device  1008  has a baseplate  1014  and a plate  1016  that can be moved relative to the baseplate  1014  in the axial direction. 
         [0113]    By means of bolts  1018  the movable plate  1016  can be tightened down toward the baseplate  1014 . The baseplate  1014  is fixed on the second part  1004  by means of bolts  1019 . Consequently a force acts upon the second insulator  1012 , which force is transmitted via the first part  1002  to the first insulator  1010  and from there in turn to the second part  1004 . A bolt  1020 , preferably in the form of a cylindrical pin, is provided in order to prevent the movable plate  1016  from twisting relative to the baseplate  1014 . 
         [0114]    Alternatively to the intermediate component  116 , the hub  402  shown in  FIG. 4  can also be made as a slipping clutch in accordance with the system illustrated in  FIG. 10 , by virtue of the first part  1002 , the second part  1004 , the first insulator  1006 , the second insulator  1010 , the third insulator  1012  and the clamping device  1008 . 
       Indexes 
       [0000]    
       
           102  First shaft 
           104  Transmission housing 
           106  Spline teeth 
           108  Second shaft 
           110  Bearings 
           112  Support structure 
           114  Screw-bolts 
           116  First intermediate component 
           118  Rotor 
           120  Screw-bolt 
           122  Screw-bolt 
           124  Generator housing 
           126  Cover 
           128  Module 
           202  Assembly safety device 
           302  Cut-out 
           402  Hub 
           404  Second intermediate component 
           502  Cut-out 
           602  Outer shell 
           604  Inner shell 
           606  Screw-bolt 
           608  Matching threads 
           610  Abutment 
           612  Thread 
           702  Groove 
           704  Disk 
           706  Transmission component 
           802  Screw-bolt 
           804  Cut-out 
           1002  First part 
           1004  Second part 
           1006  First insulator 
           1008  Clamping device 
           1010  Second insulator 
           1012  Third insulator 
           1014  Baseplate 
           1016  Movable plate 
           1018  Screw-bolt 
           1019  Screw-bolt 
           1020  Bolt