Abstract:
The invention concerns a gearing for an adjustment device, especially an automotive adjustment device. Included is a threaded spindle as well as a spindle nut sitting on the threaded spindle, while inside a housing of the gearing. On either side of the spindle nut, there is provided a bearing bush to mount the spindle nut inside the gearing housing, while at least one of the bearing bushes consists of flexible material and is clamped under prestressing between the gearing housing and the spindle nut.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to DE 10 2007 023 329.0 filed May 16, 2007, the entire contents of which are herein incorporated fully by reference. 
       FIGURE SELECTED FOR PUBLICATION 
       [0002]    
       FIG. 1 
     
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to gearing for an adjustment device. More specifically, the present invention relates to an automotive adjustment device with compensation for play. 
         [0005]    2. Description of the Related Art 
         [0006]    The related art involves an automotive adjustment device known, for example, from DE 10 2004059538 B3. The gearing has a threaded spindle as well as a spindle nut sitting on the threaded spindle. Inside the gearing housing, on either side of the spindle nut, is provided a bearing bush to hold the spindle nut inside the gearing housing. 
         [0007]    As a detriment to this design, in order to achieve a mounting of the spindle nut in the housing free of play, a specially configured bearing bush is provided. The bearing bush lies with its bearing shoulder against the end face of the spindle nut. By its tubular bearing segment, each bearing bush protrudes through a continuous opening of the housing, in which the spindle nut is accommodated. 
         [0008]    The tubular segment of the bearing bush projects from the continuous opening of the gearing housing and thrusts against a further support, which is configured, e.g., as a U-clamp, while an elastic element is interposed between the additional support and the end of the tubular bearing segment. In this way, the spindle nut is elastically stressed. The bearing bush can move axially. As a further detriment, this solution requires a specially configured bearing bush, which projects through the wall of the gearing housing. Furthermore, an additional elastic component is needed to provide for an elastic prestressing. 
         [0009]    Another gearing for an automotive seat adjustment device is known from DE 10 2005 001 333 A1. Here, again, a spindle nut sitting on a spindle is arranged between two bearing bushes inside a gearing housing. For noise reduction, these bearing bushes have a guide segment for guiding the spindle nut and a guide segment for guiding the threaded spindle. For this, the cylindrical bearing segment of the bearing bush is outfitted with a varying internal diameter, for example. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0010]    An object of the invention is to indicate a very simple gearing for an adjustment device wherein a possibility for providing a no-play or largely no-play mounting of a spindle nut inside the gearing housing exists, without having to use extra structural elements that sit outside of the gearing housing and thus increase the footprint needed for such a gearing. 
         [0011]    The present invention relates to a gearing for an adjustment device, especially an automotive adjustment device. Included is a threaded spindle as well as a spindle nut sitting on the threaded spindle, while inside a housing of the gearing. On either side of the spindle nut, there is provided a bearing bush to mount the spindle nut inside the gearing housing, while at least one of the bearing bushes consists of flexible material and is clamped under prestressing between the gearing housing and the spindle nut. 
         [0012]    The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conduction with the accompanying drawings, in which like reference numerals designate the same elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    The invention shall be discussed more closely hereafter in connection with 13 Figures. These show: 
           [0014]      FIG. 1 , an exploded perspective view of a sample embodiment of the gearing of the invention. 
           [0015]      FIG. 2 , a piece of the housing of the gearing of  FIG. 1  in perspective view, looking at the inside of the housing piece. 
           [0016]      FIG. 3 , a perspective view of the housing piece of  FIG. 2 , looking at the outside of the housing piece. 
           [0017]      FIG. 4 , a top view of the housing piece shown in  FIG. 2  and  FIG. 3 , looking at the inside of the housing piece. 
           [0018]      FIG. 5 , a cross section along section line A-A of the housing piece of  FIG. 4 . 
           [0019]      FIG. 6 , a perspective view of the bearing bush used in the gearing of  FIG. 1  for mounting the spindle nut in the gearing housing, in perspective representation, 
           [0020]      FIG. 7 , a side view of the bearing bush of  FIG. 6 . 
           [0021]      FIG. 8 , a side view of the assembled gearing of  FIG. 1 . 
           [0022]      FIG. 9 , a perspective representation of the assembled gearing of  FIG. 8 . 
           [0023]      FIG. 10 , a detail view of the assembled gearing of  FIGS. 8 and 9  in the region of the elastically deformed bearing bush in a side view, for better visibility without detailed representation of the spindle nut. 
           [0024]      FIG. 11 , a detail view of the gearing of  FIG. 10  in side view with spindle nut not yet installed and thus the bearing bush is not deformed. 
           [0025]      FIG. 12 , a longitudinal section through a second embodiment of the gearing of the invention. 
           [0026]      FIG. 13 , a longitudinal section through a third sample embodiment of the gearing of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    Reference will now be made in detail to several embodiments of the invention that are illustrated in the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. 
         [0028]      FIG. 1  shows a perspective view of a sample embodiment of the gearing of the invention in exploded view. On a threaded spindle  10  is arranged a spindle nut  20 , which can be placed in rotation by a drive worm  60 , which can be driven by an electric motor. Thanks to a rotation of the spindle nut  20 , it can move in the axial direction on the threaded spindle  10 . The spindle nut  20  and the drive worm  60  are mounted, able to rotate, in a housing assembled from two housing pieces  30 ,  32 . 
         [0029]    The mounting of the spindle nut  20  occurs via bearing bushes  40  (or alternatively called bush bearing), which are suitably arranged in the housing. Likewise, the mounting of the drive worm  60  occurs via suitably arranged bearing bushes  62 .  FIG. 1  furthermore shows an elastic shell  80 , which encloses the assembled housing from the top. 
         [0030]      FIG. 2  shows a housing piece  30  of the housing of the gearing of  FIG. 1  in perspective representation, looking at the inside of the housing piece  30 . The housing pieces  30 ,  32  are molded as so-called identical parts, which means that two identical housing parts  30 ,  32  are used to assemble one housing. As is shown in  FIG. 2 , one housing piece  30  has an essentially rectangularly shaped cross section, on which pins  33  are arranged at two diagonally opposite corners. At the two remaining corners of the housing piece  30 , again being diagonally opposite, there are arranged openings  34  with which the pins  33  engage when assembling two housing pieces  30 ,  32 , and which line up and join together the housing pieces  30 ,  32 . In the lower part of the housing piece  30  there is a recess  37  to receive the spindle nut  20  in the axial direction. 
         [0031]    The recess  37  is bounded by contact surfaces  38  front and rear in the axial direction. The contact surfaces  38  have a semicircular opening  35  in the axial direction, by which the threaded spindle  10  is guided in the assembled condition. Furthermore, the contact surfaces  38  have two roughly triangular thickenings  39 , which are placed on the contact surfaces  38  at the height of the upper and lower limit of the recess  37  and outside of a diameter of the spindle nut  20 . In the upper region, the housing piece  30  has another opening  36  transversely to the axial direction of the spindle nut, being suitably configured to receive a bearing bush  62  to mount the drive worm  60 . 
         [0032]      FIG. 3  shows a perspective representation of the housing piece  30  from  FIG. 2 , looking at the outside of the housing piece  30 . In this view, the pins  33  and openings  34  described in  FIG. 2  for assembling the two housing pieces  30 ,  32  can again be seen. Through the recess  37  to accommodate the spindle nut  20 , one can also see one of the contact surfaces  38  with the thickenings  39  arranged on the contact surface  38 . In the upper part of the housing piece  30 , in the middle, is arranged the opening  36  described in  FIG. 2  to mount the drive worm  60 . 
         [0033]      FIG. 4  shows a side view of the housing piece  30  from  FIGS. 2 ,  3 , looking at the inside of the housing piece  30 . In the view shown in  FIG. 4 , the rectangular recess  37  to accommodate the spindle nut  20  is especially well seen, being bounded front and rear by the contact surfaces  38  in the axial direction. In particular, the thickenings  39  placed on the contact surfaces  38  are especially evident in this view, standing out as projections. 
         [0034]      FIG. 5  shows a cross section along line A-A of the housing piece  30  of  FIG. 4 . In this representation of the housing piece  30 , the contact surface  38  with the semicircular opening  35  is especially well seen. Likewise well seen are the thickenings  39 , approximately triangular in plan view, which are arranged on the outer margin of the contact surface, at the upper and lower end, respectively, of the recess  37 . The thickenings  39  are each provided with a bevel toward the inside of the housing  30 , so that a platelike bearing shoulder  41  of the bearing bush  40  can be shoved across the bevel when putting the gearing together. 
         [0035]      FIG. 6  shows a perspective view of the bearing bush  40  used in the gearing of  FIG. 1  to mount the spindle nut  20  in the gearing housing. The bearing bush  40  consists of a platelike bearing shoulder  41  and a tubular bearing segment  42  arranged on the platelike bearing shoulder  41 . The platelike bearing shoulder  41  is fashioned approximately as a circle and has approximately triangular projecting regions  45  arranged on the bearing shoulder  41  on the outer side, which extend in particular beyond the diameter of the spindle nut  20 . 
         [0036]    The bearing shoulder  41 , furthermore, has a circular opening in the region of the tubular bearing segment  42 , formed as a single piece with it, so that the bearing shoulder  41  is arranged essentially as an annular region  44  at one end of the tubular bearing segment  42 . The bearing bush  40  is dimensioned so that the platelike bearing shoulder  41  in the mounted condition of the gearing coincides with the contact surfaces  38  and the projecting regions  45  are arranged in the region of the thickenings  39 . The annular region  44  of the bearing shoulder  41  is dimensioned so that it has an outer diameter corresponding to the outer diameter of the spindle nut. 
         [0037]    As can be seen from  FIG. 6 , the projecting regions  45  are situated at the annular region  44  of the bearing shoulder  42  so that two outer edges  41  a are produced, being arranged parallel to each other and tangential to the annular region  44 . The bearing bush  40  is fabricated as a single plastic piece, for example. 
         [0038]      FIG. 7  shows a side view of the bearing bush  40  from  FIG. 6 . Especially well seen in this view is the platelike bearing shoulder  41  and the tubular bearing segment  42  arranged on this bearing shoulder. 
         [0039]      FIG. 8  shows a side view of the assembled gearing from  FIG. 1 . The spindle nut  20  is mounted in the housing  30 ,  32  by means of the bearing bushes  40 . The tubular bearing segments  42  will come to lie in a circular opening of the housing  30 ,  32 , formed from the semicircular openings  35 , as can be seen in  FIG. 9 . The threaded spindle  10  is led through the bearing bush  40  and the spindle nut  20 . It is especially well seen in the view from  FIG. 8  that the projecting regions  45  in the assembled condition of the gearing are arranged so that they sit in the recess  37  on the thickenings  39  in the axial direction. As is especially well seen in  FIG. 9 , the outer edges  41  a of the bearing shoulder  41  are flush with the housing pieces  30 ,  32  on the outer side. 
         [0040]      FIG. 10  shows a representation of the assembled gearing from  FIGS. 8 and 9  in the region of the elastically deformed bearing bush  40  in a side view. hi this side view of the assembled gearing, it is especially well seen that the platelike bearing shoulder  41  is under a prestressing in the finally assembled gearing and runs along a line of flexure B, as shown. The prestressing of the bearing shoulder  41  is achieved in that the contact surfaces  38  are arranged at a distance from each other, corresponding to the sum of the length of the spindle nut  20  and twice the thickness of the platelike bearing shoulder  41 . Because the projecting regions  45  come to lie against the thickenings  39 , a prestressing of the platelike bearing shoulder  41  is produced, which prevents any play in the mounting of the spindle nut  20 . 
         [0041]    In  FIG. 11 , the gearing from  FIG. 10  is represented with the spindle nut  20  not yet installed. If the bearing bush  40  is inserted into the gearing housing  30 ,  32  in its relaxed state, the bearing shoulder  41  will come to lie against the thickenings  39  with its projecting regions  45 . There will remain a gap between the annular region  44  of the bearing shoulder  41  and the contact surface  38  at the height of the thickenings  39 , which defines the possible spring travel X of the bearing bush  40 . By installing the spindle nut  20 , the bearing shoulder  41  will be forced against the contact surface  38  between the thickenings  39 , becoming thus prestressed along the aforementioned line of flexure B. It should be noted here that the invention is not limited to the thickenings  39  being arranged on the housing. For example, it is also possible to provide the thickenings  39  directly on the projecting regions  45  of the bearing shoulder  41 . 
         [0042]      FIG. 12  shows a longitudinal section of another sample embodiment of the gearing of the invention. In this embodiment, a prestressing of the bearing bush  40  is achieved not by thickenings  39 , but instead by a tension ring  70 , which is arranged between the bearing bush  40  and the contact surface  38 . By a beveling of the contact surfaces  38 , one ensures that the tension ring  70  comes to lie in optimal position relative to the bearing bush  40 , and a force is produced in both the axial and the radial direction of the bearing bush  40 . The rest of the construction of the gearing corresponds to that of the above described sample embodiment and therefore will not be set forth further. 
         [0043]      FIG. 13  shows the gearing from  FIG. 12 , with a tension ring  70  provided on the bearing bushes  40  at either side of the spindle nut  20 . 
       LIST OF REFERENCE NUMBERS  
       [0044]      10  threaded spindle 
         [0045]      20  spindle nut 
         [0046]      30  housing piece 
         [0047]      32  housing piece 
         [0048]      33  pin 
         [0049]      34  opening 
         [0050]      35  opening 
         [0051]      36  opening 
         [0052]      37  recess 
         [0053]      38  contact surface 
         [0054]      39  thickening 
         [0055]      40  bearing bush 
         [0056]      41  platelike bearing shoulder 
         [0057]      41   a  outer edge 
         [0058]      42  tubular bearing segment 
         [0059]      44  annular region 
         [0060]      45  projecting region 
         [0061]      60  drive worm 
         [0062]      62  bearing bush 
         [0063]      70  tension ring 
         [0064]      80  elastic shell 
         [0065]    B line of flexure 
         [0066]    X spring travel 
         [0067]    Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes, modifications, and adaptations maybe effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.