Patent Publication Number: US-2006010662-A1

Title: Clamping piece for holding a window pane in a window lifter

Description:
BACKGROUND OF THE INVENTION  
      The application claims priority to DE 10 2004 033 984.8 which was filed on Jul. 14, 2004.  
      The invention relates to a clamping piece for holding a window pane in a window lifter. The clamping piece cooperates with a counter piece in order to clamp therebetween a movable window pane of a motor vehicle. The window pane can be moved by the window lifter between an open and a closed position. To this end, the clamping piece and the counter piece are fastened to a carriage, for instance, which can be moved by a mechanism of the window lifter, e.g. in a guide rail. The movement of the carriage, for instance in vertical direction, is transferred to the window pane via the clamping piece and the counter piece.  
      A bolt is commonly used to fasten the clamping piece to the counter piece. The bolt is screwed into a thread on the clamping piece. Traditionally, this thread is provided on a nut configured as a separate component, and which is fastened to the clamping piece. This will be explained briefly in the following with respect to FIGS.  1  to  3 .  
       FIG. 1  shows a clamping piece  5  mounted to a counter piece  7 . A window pane is inserted between the clamping piece  5  and the counter piece  7 , which is indicated here by lower edge R. A clamping rubber piece  9  is arranged between the window pane and clamping piece  5  and between the window pane and counter piece  7 . The clamping rubber piece  9  enhances friction and protects the window pane. The counter piece  7  is connected with a carriage  10 , which is connected with a mechanism of a window lifter (not illustrated).  
      The clamping piece  5  is pulled towards the counter piece  7  by a bolt  11 , which is screwed into a nut  13  shown more clearly in  FIGS. 2-3 . The nut  13  is a separate component that is inserted in an appropriate opening of the clamping piece  5  and is fixed at this place by pressing or caulking.  
      This construction is disadvantageous, because it entails a relatively high expenditure in manufacturing. The nut  13  has to produced as a separate component and then has to be mounted to the clamping piece  5 . Moreover, a special expenditure is required to fasten the nut  13  to the clamping piece  5  in such a reliable manner that the nut  13  will not come loose when the bolt  11  is repeatedly tightened and untightened.  
      It is the object of the invention to provide a clamping piece that can be produced under low expenditure and in which the nut can be repeatedly tightened and untightened.  
     SUMMARY OF THE INVENTION  
      To accomplish this objective, the subject invention provides a clamping piece comprising an annular lug that is configured in one piece with the clamping piece, and in which a thread-forming bolt can be screwed. The bolt pulls the clamping piece towards a counter piece in order to clamp a window pane between the clamping piece and the counter piece. The invention is based on the idea of eliminating the nut. In order to ensure that the bolt still has a reliable grip and the clamping piece can be pulled towards the counter piece, a lug is provided that is made in one piece with the clamping piece, and in which several turns can be formed. In this way a required tensile force is reliably provided. Further, the thread in the lug can be loaded to such an extent that the bolt can be tightened and untightened several times, for instance with maintenance or service activities in which the window pane has to be dismounted from the window lifter.  
      A low expenditure is involved to produce the lug on the clamping piece by deep-drawing or pressing, as the clamping piece usually is made of metal. The lug preferably has a wall thickness that is larger than a remaining wall thickness of the clamping piece. This can be ensured by suitable parameters during drawing of the lug. If necessary, the lug may subsequently be upset and/or calibrated in order to obtain the desired wall thickness. Upsetting is a processing step in which the lug is compressed and plastically deformed. Calibration is a processing step in which an opening in the lug is precisely defined by using a die, punch, or by machining for example.  
      These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a perspective view of a clamping piece together with a counter piece according to the prior art.  
       FIG. 2  shows an enlarged view of the clamping piece of  FIG. 1 .  
       FIG. 3  shows a further enlarged view of a detail from  FIG. 2 .  
       FIG. 4  shows an assembly unit consisting of a counter piece, a bolt and a clamping piece according to the invention.  
       FIG. 5  shows an enlarged view of the clamping piece of  FIG. 4 .  
       FIG. 6  shows a further enlarged view of a detail from  FIG. 5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 4  shows a clamping piece  5  mounted to a counter piece  7 . There is further provided a bolt  11 , the head (not visible) of which rests against the counter piece  7 , and a threaded shaft of which engages in the clamping piece  5 . The clamping piece  5  includes a lug  15  (see also  FIG. 4 ) that is made in one piece with the clamping piece  5 . The lug  15  is of annular shape and protrudes from the clamping piece  5  at a side facing away from the counter piece  7 . The lug  15  has a cylindrical inner surface  17  with an inner diameter that is adapted to the bolt  11  such that a female thread will be formed in the cylindrical inner surface  17  of lug  15  when the bolt  11  is screwed in. The bolt  11  may be designed such that the bolt  11  forms the female thread in the lug  15  by rolling, or by cutting in case the bolt  11  is configured as a self-tapping bolt.  
      The annular lug  15  is configured such that its wall thickness provides a desired strength of the thread formed therein. If the wall thickness of the clamping piece  5  is already comparably large, for instance 3 mm, the wall thickness of the lug  15  may be equal to the wall thickness of the remaining body of the clamping piece  5 . If the clamping piece  5  is configured to have a comparably small wall thickness, however, the lug  15  may be made such that its wall thickness is larger than the remaining wall thickness of the clamping piece  5 . This provides a high strength of the thread formed in the lug  15  and, hence, a high clamping torque for the bolt  11 .  
      Also, the wall thickness of the lug  15  could be larger in a transition region to a body of the clamping piece  5  than on an end face of the lug  15 . Such a parameter is another way to influence the strength of the formed thread.  
      The clamping piece  5  is made of metal and produced by punching, stamping, pressing or deep-drawing. The cylindrical lug  15  is pressed or deep-drawn, too. This results in a very low expenditure in manufacturing. As the entire clamping piece  5  is made from one single piece, there will be no expenditure for mounting additional components. Further, there is no risk of an incorrect mounting of additional components.  
      Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.