Abstract:
In a spindle drive and a production process for such a spindle drive, in particular for adjusting a moving part in a motor vehicle, having a drive assembly, which drives a drive wheel supported on a spindle, and the drive wheel is supported rotatably in a support tube which on one end of the support tube has a receptacle for a fastener for diverting crash forces, the spindle is capable of being installed in the identical support tube in either a first installation position or a second installation position rotated by 180°.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
       [0001]    The invention described and claimed hereinbelow is also described in German Patent Application DE 102006009576.6 filed on Feb. 28, 2006. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a spindle drive having a support tube, in particular for adjusting moving part in a motor vehicle. 
         [0003]    In European Patent Disclosure EP 0 759 374 A2, a device for adjusting a seat in a motor vehicle has been disclosed that is capable of absorbing considerably greater forces compared to normal operation. Such forces are caused by a traffic accident, for instance. It is important here that the vehicle seat remain solidly joined to the vehicle body, to assure the function of the intended provisions (safety belt, airbag) for protecting the vehicle occupants. 
         [0004]    In the above device, a threaded nut which receives a threaded spindle is solidly joined to the vehicle body. The threaded spindle is driven a worm gear by an electric motor that in turn is solidly joined to the seat. The gearbox of the worm gear is made from plastic and is joined to the drive motor via a further housing part. If the drive motor is actuated, the threaded spindle turns and displaces the gearbox, including the drive motor and the seat, relative to the threaded nut. In a rear-end collision, for instance, to prevent the gearbox from ripping loose from the threaded spindle, an additional U-shaped metal bracing part is provided, which connects the gearbox to the drive motor and thus to the seat via an articulated fastening bolt. 
         [0005]    The disadvantage of this embodiment is that the U-shaped bracing part requires a relatively large amount of installation space, so there is no flexibility in installing the spindle drive. 
       SUMMARY OF THE INVENTION 
       [0006]    Accordingly, it is an object of the present invention to provide a spindle drive, particularly for adjusting a moving part in a motor vehicle, which avoids the disadvantages of the prior art. 
         [0007]    In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a spindle drive, comprising a spindle; a drive wheel supported on said spindle; a drive assembly which drives said drive wheel supported on said spindle; a support tube rotatably supporting said drive wheel and having one end provided with a receptacle for a fastener for diverting crash forces, said spindle being installable in said support tube either in a first installation position or a second installation position rotated by 180°. 
         [0008]    The device and the method of the invention, having characteristics of the independent claims, have the advantage that because of the flexible support of the drive wheel inside the support tube, different installation positions for the spindle can be implemented. As a result, the receptacle for the fastener is located at various locations relative to the spindle, and as a result, without changing the individual components, the spindle drive can be adapted to different installation situations. For an identical position of the drive assembly with the support tube, the spindle can protrude from the support tube in the opposite direction—that is, rotated by 180°. 
         [0009]    Advantageously, both installation positions of the spindle can be implemented without structurally changing the individual components. The fastening means to the part to be adjusted or to the vehicle body are then easy to adapt to the location of the receptacle relative to the spindle drive. 
         [0010]    The cup-shaped bearing plate, remote from the receptacle, of the support tube can for instance be embodied integrally with the support tube or as a separate component that is inserted into the support tube or secured in the support tube. The radial inside face of the cup-shaped end serves the purpose of radially and axially supporting the drive wheel. If the cup-shaped bearing plate is embodied in one piece with the support tube, then this bearing plate can advantageously be embodied quite economically in a single work operation by means of deep drawing. 
         [0011]    It is especially advantageous if the gearbox is reliably secured to the support tube by means of a coupling device. To that end, the gearbox, which for instance has a base body and a cap, can be mounted radially in the manner of a cuff with a form lock around the support tube. 
         [0012]    This can be achieved for instance by providing that there are recesses in the support tube which in form-locking fashion engage the radial extensions of the gearbox. By the assembly of the gearbox, which for instance is in two parts, the support tube is simultaneously secured relative to the gearbox with the connection of the gearbox parts. The gearbox can be joined together for instance by means of screws, clips, welding, or pressing. 
         [0013]    If the bearing plates in the support tube are embodied symmetrically to the drive wheel located on the spindle, then the installation position of the spindle can be such that without structurally changing the individual components, the spindle protrudes in one or the other direction out of the gearbox. As a result, the spindle motor, constructed as a modular system, can be adapted to various installation spaces in the motor vehicle without additional effort or expense. 
         [0014]    In the method according to the invention for producing the spindle drive, the support tube with the built-in spindle and the drive wheel is a prefabricated module, onto which the gearbox can then be mounted. In the preassembly, depending on the application, the spindle can be located in the first or the second installation position in the support tube, without thereby affecting the further mounting of the drive assembly on the support tube. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a first exemplary embodiment of a spindle drive in a first installation position of the spindle in section in accordance with the present invention; and 
           [0016]      FIG. 2  shows a further exemplary embodiment in a second installation position of the spindle, in a section taken along the line II-II in accordance with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    The spindle drive  10  shown in  FIG. 1  comprises a first component unit  12 , in which a spindle  16  with a drive wheel  18  located on it is supported in a support tube  14 . The support tube  14 , on a first end region  20 , has a first cup-shaped bearing receptacle  22  for the drive wheel  18 . With a first end  25 , remote from the drive wheel  18 , the spindle  16  protrudes through an opening  24  in the first cup-shaped bearing receptacle  22  and out of the support tube  14 . The other, second spindle end  26  with the drive wheel  18  is located inside the support tube  14  and is supported axially and radially by means of the first bearing plate  22  and a second bearing plate  28  that contacts the end  26  of the spindle  16 . 
         [0018]    In  FIG. 1 , both bearing plates  22  and  28  are embodied as separate components and are secured inside the support tube  14 , for instance being placed in it or screwed into it. The spindle end  26  has a spherical stop face  30 , which axially contacts the bearing plate  28 . Optionally, a stop disk  32  of increased strength can be located in the bearing plate  28 . In the exemplary embodiment the drive wheel  18  is embodied as a worm wheel  19 , which for radial support has axial extensions  34 . The drive wheel  18  is injected from plastic directly onto the spindle  16  or is mounted in a manner fixed against relative rotation and has a set of teeth  36  that meshes with a driven element  40  of a drive assembly  42 . 
         [0019]    The drive assembly  42  is embodied as an electric motor  43 , which has a gearbox  46  that is joined to the first component unit  12  by means of a coupling device  44 . An inner contour  49  of the gearbox  46  surrounds an outer contour  15  of the component unit  12 . On the inner contour  15 , there is at least one radial extension  90 , which engages at least one corresponding radial recess  92  in the support tube  14 . The radial extensions  90 , together with the recesses  92 , form fastening means  89  of the coupling device  44  for the component unit  12 . In further variant embodiments, the fastening means  89  may also be formed by different form locks. 
         [0020]    The gearbox  46  has a base body  47  and a cap  48 , which are mounted radially around the support tube  14  and joined together. Upon the connection of the two gearbox parts  47  and  48 , the support tube  14  is simultaneously secured to the gearbox  46  via the fastening means  89 . For transmitting the driving moment from the drive assembly  42  to the separate component unit  12 , the support tube  14  has a radial recess  50 , which is engaged by the driven element  40 . The driven element  40  is embodied for instance as a worm  39 , which is located on an armature shaft  41  of the electric motor  43 . 
         [0021]    The support tube  14 , as practically a standard component, forms a housing for the separate component unit  12 , on which housing a receptacle  52  for a fastener  54  is located on the end region  21  diametrically opposite the end  20 . As the fastener  54 , a link pin  55  can be inserted centrally to the support tube  14  into the receptacle  52 , which is embodied as a continuous bore  56 . Via this fastener  54 , the support tube  14  is connected, for instance pivotably with a part  58  to be adjusted in the motor vehicle, such as a seat or seat part, not further shown, that is adjusted relative to another seat part. 
         [0022]    In  FIG. 1 , the spindle  16  is shown in a first installation position  60 , in which the end  25  of the spindle  16  remote from the drive wheel  18  protrudes from the end  20  of the support tube  14  diametrically opposite the receptacle  52 . In this first installation position  60 , the end  21  toward the receptacle of the support tube  14  protrudes axially past the gearbox  46 , so that the receptacle  52  is located axially adjacent to the spindle  16 . In this arrangement, a continuous bolt  55  can be inserted as a fastener  54  into the continuous bore  56 , resulting in a very stable fastening to the adjusting member  58 . 
         [0023]    To achieve a shorter spindle drive  10  or a mirror-symmetrical arrangement of the spindle  16 , the spindle  16  can be installed, with the drive wheel  18  and the bearing plates  22  and  28 , rotated by 180° into the identically located support tube  14 , with the flanged-on drive assembly  42 . The bearing plate  28  is then located with the central stop face  30  of the spindle  16  in  FIG. 1  on the left-hand side on the end  20 , and the end  25  of the spindle  16  protrudes toward the right, through the opening  24  in the bearing plate  22  located toward the receptacle  52 , out of the end  21  of the support tube  14 . In this second installation position  62 , shown in terms of a variant in  FIG. 2 , a continuous bolt  55  cannot be inserted because of the axial overlap of the receptacle  52  with the spindle  16 . 
         [0024]      FIG. 2  shows a further variant embodiment of a spindle drive  10  in a section taken along the line II-II in  FIG. 1 , in which the first bearing plate  22  on the end  20  of the support tube  14  is embodied integrally with the support tube, for instance being produced by deep drawing. The bearing plate  22  embodied in one piece with the support tube  14  has the central opening  24 , through which the end  25  of the spindle  16  protrudes in the first installation position  60 , not shown. 
         [0025]    In  FIG. 2 , the second installation position  62  is shown, in which the end  25  of the spindle  16  protrudes to the right out of the end  21 , toward the receptacle, of the support tube  14 . The bearing plate  28 , toward the receptacle  52 , likewise has a central opening  24 , through which the end  25  of the spindle  16  protrudes to the outside in the second installation position  62 , shown. Since here the receptacle  52  is located axially in the region of the spindle  16 , fastening pins  57  are each inserted laterally through the respective bores  56  in the support tube wall  13 , and with them the support tube  14  is connected for instance pivotably to the part  58  to be adjusted. A threaded nut  76 , which is joined to the vehicle body  84 , for instance, is located on the spindle  16 . 
         [0026]    To attain the first installation position  60 , the spindle  16  in  FIG. 2  need merely be rotated 180°. The bearing plate  22  together with the support tube  14  remains in the same position, and the bearing plate  28 , after the insertion of the spindle  16 , is introduced into the support tube  14  again with the end  25 , through the opening  24  in the bearing plate  22 , and secured. Since in this embodiment both bearing plates  22  and  28  have central openings  24 , the spindle  16  is supported axially in both directions on an annular collar  23  of each of the two bearing plates  22 ,  28 . In this second installation position  62 , the support tube  14 , with its end  20  remote from the receptacle  52 , ends approximately flush with the gearbox  46 , so that the required installation space on the spindle end  26  is reduced compared to the first installation position  60 . 
         [0027]    It should be noted that with regard to the exemplary embodiments shown in the drawings and to the description, manifold possible combinations of the individual characteristics with one another can be made. For instance, the support tube  14  can be produced by different methods and can have different concrete shapes. Instead of an integrally formed cup-shaped bearing receptacle  22 , the support tube  14  may also be embodied as a smooth cylindrical tube, in which two separate bearing plates  22  and  28  are located for supported the spindle  16 . 
         [0028]    The spindle  16  is preferably supported via the drive wheel  18  supported thereon, but in a variation can also be supported by means of bearing plates which are integrally formed directly onto the spindle  16 . The torque transmission from the drive assembly  42  is not limited to a worm gear  19 ,  39 ; it can also be done for instance by means of a spur-gear unit. The cross section of the support tube  14  is not limited to a circle and may for instance be embodied rectangularly or elliptically instead. 
         [0029]    Instead of a rotary spindle, a plunging spindle may be located in the support tube  14 , which protrudes in both directions from the support tube  14  and past the gearbox  46 . The driven wheel  18  is rotatably supported on the spindle  16 , and during the adjustment mode the spindle  16  does not rotate but instead is displaced only linearly by the driven wheel  18 . The advantage of this version is that with an identical location of the drive assembly  42  and the gearbox  46 , in the 180°-rotated installation of the driven wheel  18  with the spindle  16 , the receptacle  52  for the fastener  54  extends on the one hand to the left and on the other to the right with regard to the driven wheel  18 . This increases the flexibility in installing this kind of plunging spindle drive. 
         [0030]    It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above. 
         [0031]    While the invention has been illustrated and described as embodied in a spindle drive, particularly for adjusting a moving part in a motor vehicle, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
         [0032]    Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.