Abstract:
The invention relates to a securing plate ( 10 ), a fixing device and to a method for fixing an electric machine ( 12 ), for example to a component ( 30 ) of a motor vehicle, comprising a central through-opening ( 14 ) for receiving a round bearing sleeve ( 16 ) of the electric machine ( 12 ), said through opening ( 14 ) having a polygonal shape ( 15 ), the lateral surfaces ( 18 ) resting on the bearing sleeve ( 16 ). The securing plate ( 10 ) has, in a radially outer region ( 20 ), securing holes ( 22 ) via which the electric machine ( 12 ) can be secured to the component ( 30 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a fastening plate, a fastening device, and also a method for fixing an electric machine to a component. 
         [0002]    DE 10 2005 030 218 A1 discloses a fastening device, wherein an adapter element is arranged about an output shaft of an electric motor in order to fasten said electric motor by way of example in an automobile bodywork. The adaptor element that is embodied in two pieces is joined in a radial manner to an axial extension of the electric motor. The axial extension is a component of a bearing shield and comprises in its radial outer periphery a form closure that prevents the adapter element from rotating with respect to the electric motor. In order to position the output shaft of the electric motor precisely with respect to the automobile bodywork, very high demands are placed on the production of the adapter element. However, it is not possible to guarantee that the precise positioning remains permanent particularly if the environmental temperatures change. 
       SUMMARY OF THE INVENTION 
       [0003]    The fastening plate in accordance with the invention and the fastening device and also the method for fastening an electric machine have in contrast thereto the advantage that by virtue of embodying a fastening plate with a central receiving opening for the axial extension of the bearing shield of the electric motor it is also possible to compensate effectively for bearing tolerances even over a large temperature range. For this purpose, the receiving opening is formed in the shape of a polygon that is pressed with its lateral surfaces in a radial manner against the axial extension of the electric machine. It is possible using the fastening orifices that are formed on the fastening plate to permanently fasten the electric machine in a highly space saving manner directly on a motor vehicle component. 
         [0004]    It is possible by virtue of the measures disclosed in the dependent claims to achieve advantageous further developments and improvements of the embodiments disclosed in the independent claims. It is particularly advantageous if the fastening plate is embodied as a metal plate that is to a great extent planar and in which the receiving open is punched out as a through-going orifice. This through-going orifice is advantageously not round but rather is embodied as a polygon, wherein in particular a triangular or rectangular or pentagon or hexagon shape is formed. As a consequence, the approximately circular axial extension of the electric motor does not lie over the entire periphery of the receiving opening. 
         [0005]    The cornered through-going orifice comprises in an expedient manner planar lateral surfaces that lie against the axial extension of the electric machine only in a contact region that is linear-shaped in the axial direction. The axial extension is preferably embodied as a bearing sleeve in which a bearing body—by way of example a roller bearing—of the output shaft is received. 
         [0006]    In a preferred embodiment, only precisely three lateral walls lie in a radial manner against the bearing sleeve since this avoids a mechanical over-dimensioning of the radial bearing arrangement. It is possible to arrange by way of example further lateral walls of the through-going orifice in a radial manner outwardly offset so that said lateral walls do not have any contact to the bearing sleeve. 
         [0007]    In order to compensate for manufacturing tolerances between the through-going orifice and the bearing sleeve, so-called deformation cut-outs are formed at least in the region of the bearing regions in a radial manner externally of the through-going orifice and said deformation cut-outs render it possible for the contact regions to move to a certain extent in a radial manner. The deformation cut-outs extend in the tangential direction along the lateral walls so that the peripheral wall of the through-going orifice comprises radially movable connecting pieces that can deform in an elastic or plastic manner. 
         [0008]    In order to embody the lateral walls in such a manner that they move radially, the connecting pieces comprise a radial width of 0.5 mm to 3.0 mm, wherein a width of approx. 1.0 mm has proven itself to be particularly favorable. The axial thickness of the fastening plate in the region of the connecting pieces is ideally likewise 0.5 to 3.0 mm, preferably approx. 1.0 mm. It is possible by virtue of the radially flexibly lateral walls of the receiving opening to achieve a press-fit with the bearing sleeve without having to influence the bearing body inside the bearing sleeve with external press-down forces. The radial movability of the connecting pieces can be achieved in particular in a simple manner by means of elongated slots in the fastening plate, the extension of said slots in the tangential direction being greater than their radial dimension, and said slots being aligned approximately along the straight lateral surfaces. 
         [0009]    In order to fasten the electric machine in a simple manner, the fastening plate comprises on the outer periphery fastening orifices that preferably lie radially outside the dimensions of the electric machine, in particular radially outside its pole housing. As a consequence, connecting means, such as screws, rivets or bent brackets, can be mounted without said connecting means conflicting with the installation space of the electric machine. 
         [0010]    In addition to the through-going orifice and the deformation cut-outs, further through-going passages are embodied in the fastening plate and by way of example the electrical supply lines of the electric machine are routed through said through-going passages. Said electrical supply lines are located preferably radially outside the deformation cut-outs and are pushed onto the bearing sleeve by way of the cable feeds during the axial assemble of the fastening plate. In order to precisely fasten the rotational position of the fastening plate with respect to the housing of the electric machine, the fastening plate comprises an anti-rotation feature that is embodied as a radial and/or axial extension and engages in a corresponding mating receiving device in the housing of the electric machine. Consequently, by way of example, the fastening orifices and the through-going passages for the electrical contacts are positioned in their rotational position precisely with respect to the housing of the electric machine. 
         [0011]    The fastening plate is part of a fastening device wherein the fastening plate is fastened in a non-rotatable manner to the bearing sleeve of the electric machine. The bearing sleeve is embodied in one piece with a bearing lid that closes a cylindrical pole housing of the electric machine. The bearing sleeve receives inside a bearing body in which the output shaft of the electric machine is mounted, said output shaft being in particular identical to the rotor shaft of the electric machine. In the case of this fastening device, a roller bearing—by way of example a ball bearing—can be received inside the bearing sleeve in such a manner that the outer bearing ring of the roller bearing is not adversely affected as the fastening plate is pressed onto the bearing sleeve. 
         [0012]    Manufacturing tolerances and also thermal expansions during operation are effectively compensated for by virtue of the fastening method in accordance with the invention by means of the peripheral wall of the through-going orifice deforming in the radial direction. As a result of the symmetrical arrangement of the orifice regions of the lateral walls, the output pinion always remains precisely centered with respect to the fastening orifices. This ensures that the electric machine is positioned in a simple and precise manner during all operating states of the electric machine in the motor vehicle. 
         [0013]    It is possible using this fastening device to fasten by way of example an electric machine that is embodied as a geared drive unit for an adjusting device to the motor vehicle in a reliable manner. By way of example, it is possible using the fastening plate to fasten a seat-adjusting drive, a window-operating drive, a windscreen washer drive or a throttle flap adjuster in the engine compartment to the bodywork in a reliable manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Exemplary embodiments of the fastening plate, the fastening device and the fastening method in accordance with the invention are illustrated in the drawings and further explained in the description hereinunder. 
           [0015]    In the drawings: 
           [0016]      FIG. 1  illustrates a plan view of a fastening plate, 
           [0017]      FIG. 2  illustrates a fastening plate that is mounted on an electric machine, and 
           [0018]      FIG. 3  illustrates a sectional view through the fastening device in accordance with  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  illustrates a fastening plate  10  that is suitable for fastening an electric machine  12  to a component  30 , by way of example to a motor vehicle bodywork. The fastening plate  10  comprises centrally a through-going orifice  14  into which it is possible to insert an axial extension of the electric machine  12 . The through-going orifice  14  comprises planar lateral surfaces  18  that lie against the axial extension in a radial manner after assembly, said extension being embodied by way of example as a bearing sleeve  16 . The individual lateral surfaces  18  are mutually connected by way of more or less emphasized corners  21 . Consequently, the through-going orifice  14  is embodied approximately as a polygon or polygonal traverse that comprise by way of example rounded corners  21 . In  FIG. 1 , the polygon is embodied by way of example as a hexagon with six planar surfaces  19 . However, alternatively, the through-going orifice  14  can also be embodied as a triangle, rectangle, or pentagon. Deformation cut-outs  24  are embodied in a radial manner outside the lateral surfaces  18  and allow the lateral surfaces  18  to deform in a radial manner in order to compensate for tolerances when receiving the bearing sleeve  16 . The deformation cut-outs  24  are longer in the tangential direction  52  than in the radial direction  54  so that the lateral surfaces  18  are embodied as radially deformable connecting pieces  26 . The deformation cut-outs  24  that are embodied in this case as slots extend approximately parallel to the lateral surfaces  18 . However, said deformation slots can also have a rounded or oval shape as illustrated by way of example in a variation in  FIG. 2 . The connecting pieces  26  preferably comprise a radial width  28  that is approximately equal to the axial thickness  32  of the fastening plate  10  in the region of the connecting pieces  26 . In order to render the connecting pieces  26  radially deformable, the width  28  and the thickness  32  are approx. 1 mm; however, the width and thickness can also be in the range between 0.5 and 3.0 mm depending upon the requirement. 
         [0020]    In the exemplary embodiment in  FIG. 1 , the through-going orifice  14  comprises approximately a regular hexagonal shape. However, it is possible in one variation to offset each second lateral surface  18  in a radially outwards manner so that only the three radially further inwards lying lateral surfaces  18  of the hexagon through-going orifice  14  lie against the bearing sleeve  16 . It is possible by virtue of the round bearing sleeve  16  bearing in this manner against only three planar surfaces  19  to avoid a mechanical over-dimensioning of the bearing arrangement. A through-going orifice  14  of this type that is embodied as an irregular hexagon having lateral surfaces  18  that are of different lengths in the tangential direction  52  require by way of example less surface area than a corresponding triangular through-going orifice for a bearing sleeve  16  having the same diameter. 
         [0021]    Furthermore, through-going passages  34  for connection elements are embodied in the fastening plate  10  and corresponding connections of the electric machine  12  are guided through said through-going passages in the assembled state.  FIG. 2  illustrates by way of example electrical contacts  35  that can be embodied as punched-out parts or also as a cable. The electrical contacts  35  are by way of example embodied as supply lines or as electrical signal lines of the electric machine  12 . Fastening orifices  22  for connection means to the component  30  are embodied in the radially outer region  20 . The fastening orifices  22  are punched out in the exemplary embodiment as eyelets  23  directly from the fastening plate  10 . The fastening orifices  22  lie radially outside the housing of the electric machine  12  in the assembled state so that it is possible to insert without any problem screws or rivets as connection means into the fastening orifices  22 . Alternatively, the fastening orifices  22  can also be embodied as punched-out brackets that can be connected to the component  30  by means of material plastic deformation. In order to fix the fastening plate  10  precisely to the electric machine  12  with regard to the tangential direction  52 , the fastening plate  10  comprises an anti-rotation device  36  that cooperates with a mating receiving device  37  of the electric machine  12 . The anti-rotation device  36  is embodied as an axially bent bracket that engages into a corresponding receiving device in the housing of the electric machine  12 . The anti-rotation device  36  can thus form a form closure with the housing of the electric machine  12  in the radial direction  54  or axial direction  50 . In the exemplary embodiment, precisely two fastening orifices  22  are embodied on the axially outer periphery of the fastening plate  10 . However, it is also possible in one variant to provide three or four fastening orifices  22 . The fastening plate  10  is embodied as a metal sheet and the respective cut-outs are punched out from the metal sheet. All the cut-outs can be punched out advantageously in one working step and where applicable particular regions—such as by way of example the anti-rotation device  36  or the fastening orifices  22 —can also be formed as one by means of a bending procedure. The through-going orifice  14  is embodied in the approximately circular fastening plate  10  in a radially central manner, radially offset thereto are the deformation cut-outs  24 , radially offset thereto are the through-going passages  34  for the electrical contacts  35  and radially offset thereto are the fastening orifices  22 . 
         [0022]    In the fastening device  60  shown in  FIG. 2 , a fastening plate  10  in accordance with  FIG. 1  is pressed onto the electric machine  12 . The planar surfaces  19  of its through-going orifice  14  lie with contact regions  44  in a radial manner against the rounded bearing sleeve  16 . The contact regions  44  are embodied in the axial direction  50  in an approximately linear manner so that in the plan view in accordance with  FIG. 1  the planar surfaces  19  are only pressed at various spots in a radial manner against the rounded bearing sleeve  16 . As the fastening plate  10  is pressed on, the deformable connecting pieces  26  are bent radially outwards until the fastening plate  10  lies against the electric machine  12  in an axial manner during the pressing-on procedure. A press-fit is formed between the through-going opening  14  and the bearing sleeve  16  and said press-fit fixes the fastening plate  10  in a reliable manner to the electric machine  12 . The width  28  and the tangential length of the connecting pieces  26  are dimensioned in such a manner that the radial pressing-on forces do not deform the bearing sleeve  16 . As a consequence, the function of the bearing body  40  that is mounted in the bearing sleeve  16  is not impaired. The rotor shaft  38  of the electric machine  12  is mounted in the bearing body  40  and an output element  42  that is embodied by way of example as a pinion is mounted on said rotor shaft. This output element  42  drives as a part that is to be adjusted by way of example a throttle flap or a seat component or a window lever or a windscreen wiper. A drive unit  70  of this type is connected to a component  30  of the motor vehicle by means of connection elements, not illustrated, that are arranged in the fastening orifices  22 . By way of example, the drive unit  70  is reliably positioned in the engine compartment or on the frame of the motor vehicle by means of the fastening device  60  in accordance with the invention. 
         [0023]      FIG. 3  illustrates a sectional view of the drive device  70 , wherein it is evident that the output element  42  is pushed onto the end of the output shaft  38 . The bearing sleeve  16  is embodied as one piece with the bearing lid  17  that is preferably produced as a punched-out bent part. The bearing lid  17  is fastened by way of example on the outer periphery of a pole housing  46  of the electric machine  12 . The bearing body  40  is arranged within the axial extension of the bearing sleeve  16  and said bearing body receives the output shaft  38  that is identical in this case to the rotor shaft of the electric machine  12 . The bearing body  40  is embodied by way of example as a roller bearing, preferably as a ball bearing  41 . The outer ring of the ball bearing  41  is subsequently pressed inside the axial extension that is embodied as the bearing sleeve  16 , wherein the bearing inner ring is fastened to the output shaft  38 . By way of example, the bearing body  40  is fixed in an axial manner in the bearing sleeve  16  by means of material plastic deformation of the bearing lid  17 . The specific arrangement and design of the fastening orifices  22  on the fastening plate  10  can be modified in a simple manner depending upon the application without having to change the design of the through-going orifice  14  on the fastening plate  10 . A precise coaxial positioning of the fastening plate  10  with respect to the output element  42  is always ensured by virtue of providing at least three contact regions  44  that are arranged uniformly distributed over the periphery. The electric machine  12  is embodied by way of example as an electric motor, wherein permanent magnets are arranged in the pole housing  46  that drive the rotor that is mounted on the output shaft  38 . 
         [0024]    It is to be noted that with respect to the exemplary embodiments illustrated in the figures and the description numerous possible combinations of the individual features are possible. Thus, by way of example specific shapes of the through-going orifice  14  and of the deformation cut-out  24 , the through-going guide  34  and the fastening orifice  22  can be adapted to suit the respective application. In particular, the width  28  and the thickness  32  of the connecting pieces  26  are adapted to suit the required, or rather admissible, radial pressing-on forces with respect to the bearing sleeve  16 . In the case of the embodiment of the through-going orifice  14 , it is not the corners  21  that are decisive but rather the design of the planar lateral surfaces  19  between the corners  21  of a polygonal traverse.