Abstract:
A follower for holding a window pane is adjustable by a motor vehicle window lifter. The follower is connectable to the window lifter and has at least one retaining arm which can be brought into engagement with the window pane and thereby extends at least in part along a window pane surface. The follower is designed so that in the event of the window pane being loaded with force (F) in the lifting direction (H) a torque is exerted on the retaining arm of the follower. The torque is exerted in the direction of the window pane surface to press the retaining arm toward the window pane and prevent the window pane from becoming disengaged and sliding out from the follower.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of International application number PCT/DE99/02555, filed Aug. 13, 1999, which in turn claims priority to German patent application number 19840682.7, filed Aug. 26, 1998. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a follower for holding a window pane which can be adjusted by means of a vehicle window lifter. 
     BACKGROUND OF THE INVENTION 
     A follower of this kind is known from DE 4434589 A1. The known follower comprises a pair of elastically expanding jaws, which are connected to the base body of the follower. In order to insert a window pane into the follower the jaws are spread apart. After inserting the window pane the jaws move back to adjoin same; they thereby come into keyed engagement with a hole in the window pane or a positive locking element fixed on the window pane. 
     The drawback with the known follower is that if larger forces occur in the lifting direction of the window, for example in the event of a crash, the jaws of the follower are inclined to spread open. There is then the risk of the window pane coming out of the follower. 
     From EP 0 643 188 A1, a follower is known for a motor vehicle window lifter having a fixed part and a movable part fixed thereon. The movable part is fitted on the fixed part by swivelling the movable part about a swivel point of the fixed part and then sliding the movable part along the fixed part. This produces a positive and force-locking connection between the fixed and movable parts of the follower. The movable part has a retaining arm which adjoins a surface of the window pane which is to be taken up by the follower and engages with a projection through an opening in this window pane. In its functioning position (i.e. after fitting the movable part on the fixed part), this retaining arm is mounted so that when a removal force acts on the window pane having a tendency to loosen the window pane from the follower the retaining arm is swivelled in a direction away from the associated surface of the window pane. 
     From EP 0 694 669 A1 a device is known for connecting a window pane to a window lifter (follower) where a pair of clamping jaws are pressed in the region of a window pane edge through a tensioning force onto each one side of the window pane. The formation of this follower is such that the clamping jaws are inclined to spread out when a removal force acts on the window pane. 
     SUMMARY OF THE INVENTION 
     The object of the invention is therefore to provide a follower of the kind mentioned at the beginning which can also hold the window pane secure even when large forces arise in the lifting direction of same. 
     According to this, it is proposed to design the follower so that if the window pane is loaded with a removal force that has the tendency to loosen the window pane in the lifting direction out from the follower, a torque acts on the follower to press the at least one retaining arm of the follower, which is located in engagement with the window pane, in the direction of the window pane surface. This is possible in particular through a suitable design and binding of the retaining arm on the base body of the follower. 
     The invention is based on the surprising knowledge that securing the window pane from sliding out of the follower can be undertaken without any expensive additional structural elements by using the force which acts on the window pane and which threatens to loosen the pane, to strengthen the connection between the window pane and follower. This is based on the same underlying principle as in the case of scissors, where the cutters are closed when they hang down vertically by their handles. 
     The solution according to the invention has the advantage that as a result of the stressed design of the follower, the force by which the pane is held in the follower becomes greater the greater the force which acts on the window pane in the lifting direction. For it is the latter force which produces the torque through which the follower is pressed towards the surface of the window pane in order to strengthen the connection. 
     The window pane is therefore held securely in the follower up to very high removal forces. The limit lies only at those forces which would lead to a destruction of the follower. 
     In a preferred embodiment of the invention, the holding arm of the follower is able to swivel substantially across the plane of the window pane and can thereby be brought into positive locking engagement with the window pane. 
     The positive locking engagement can be produced in particular if the retaining arm has a stop which is supported on a counter surface of the window pane so that the window pane is prevented from sliding out from the follower in the lifting direction. 
     With this embodiment of the invention, the follower is designed so that the swivel movement of the retaining arm corresponds substantially to a movement about an imaginary swivel area which, as seen from the section of the retaining arm running along the window pane, is arranged behind a plane which runs through a force engagement point of the stop at the counter surface and parallel to the displacement plane of the window pane. 
     The swivel area can thereby be formed both by a conventional swivel axis and by a section of the follower with reduced material thickness. 
     It can thereby be proposed that the retaining arm has a connecting section which, as seen from the section of the retaining arm running along the window pane, is connected to the base body of the follower behind the aforementioned plane. 
     If the follower is provided in the conventional way for holding the window pane in the area of the lower pane edge then the connecting section of the retaining arm underneath the lower edge of the pane can be supported on the base body of the follower. 
     The retaining arm underneath the lower edge of the pane can thereby be supported on a counter member of the follower so that it can swivel about this counter member. Furthermore the retaining arm is preferably hung from the counter member of the follower secured against loss. 
     The stop at the upper end of the retaining arm of the follower is preferably formed as a hooked element which projects into an opening of the window pane associated with same or is supported on a counter face protruding from the window pane. This counter face can be formed on one side by a structural element which is pushed into an opening of the window pane or by a structural element which is stuck onto the window pane. 
     The follower can have on the side opposite the retaining arm a rigid follower section which adjoins the window pane. As an alternative, the follower can have two retaining arms which can be brought into engagement with opposing side faces of the window pane, wherein each retaining arm is formed so that when the window pane is loaded with a force in the lifting direction a torque is exerted on the retaining arm which presses it towards the surface of the pane. 
     In a preferred embodiment of the invention the two retaining arms of the follower criss-cross one another and thereby form a U-shaped socket for the lower edge of the pane. 
     The retaining arm itself is preferably made of an elastically deformable material and is connected for swivel or bending movement to the base body of the follower. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages of the invention will be apparent from the following description of examples as shown in the drawings in which: 
     FIG. 1 a  is a side view showing a first embodiment of the follower according to the invention with two swivel retaining arms; 
     FIG. 1 b  is a view showing a retaining arm of the first embodiment shown on FIG. 1 a;    
     FIG. 2 a  is a side view showing a second embodiment of the follower according to the invention with two swivel retaining arms; 
     FIG. 2 b  is a side view showing the retaining arm of the second embodiment shown on FIG. 2 a;    
     FIG. 3 shows a third embodiment of the follower according to the invention with two swivel retaining arms; 
     FIG. 4 shows an embodiment of the follower according to the invention with only one swivel retaining arm; 
     FIG. 5 shows an embodiment of the follower according to the invention wherein the stops extend into an opening of the window pane. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 a  shows a side view of a follower  1  in which a window pane  20  is inserted. 
     The follower  1  comprises two retaining arms  11 ,  12  which are each connected to the base body  2  of the follower through a connecting section  31 ,  32 . In addition, the retaining arm  11  is thereby shown separately in FIG. 1 b.    
     The two retaining arms  11 ,  12  each have in their upper section  13  a hooked stop  14  which is supported on a counter face  26  of the window pane  20  running across the lifting direction H. The lifting face  26  is thereby formed by a bolt  25  which is inserted in an opening  24  of the window pane  20 . 
     The two connecting areas  31 ,  32  through which the retaining arms  11 ,  12  are connected to the base member  2  of the follower  1  are characterised by a comparatively thin material thickness. The two connecting sections  31 ,  32  of the follower  1 , which is preferably made of plastic, are therefore sufficiently elastic in order to form swivel areas A 1  about which the retaining arms  11 ,  12  can be swivelled. Expressed in other terms, the retaining arms  11 ,  12  can be swivelled away from the associated window pane surface  21 ,  22  by elastically deforming the connecting sections  31 ,  32 . This is necessary, for example, if the window pane  20  is inserted in the follower  1  against the lifting direction H. 
     This is only an imaginary swivel area A 1  since there is no actual swivel movement of the retaining arms  11 ,  12  about an axis. Rather the elastic design of the retaining arms  11 ,  12  in their lower sections  31 ,  32  enables the retaining arms  11 ,  12  to bend corresponding substantially to a swivel movement of the retaining arms  11 ,  12  about the swivel area A 1 . 
     The particular feature in the design of the follower  1  is now that the swivel areas A 1  are arranged so that a torque is exerted on the retaining arms  11 , 12  which presses them against the associated surface of the pane  21 ,  22  when a force F is exerted on the window pane  20  in the lifting direction H. 
     This is due to the fact that the connecting section  31 , associated with the retaining arm  11 , and the connecting section  32 , associated with the retaining arm  12 , each run—seen from the retaining arm  11  or  12 —on the opposite side of the plane E 1  or E 2 . The planes E 1  and E 2  respectively are defined in that they each run parallel to a surface  21  or  22  of the window pane through a force engagement point  15  in the vicinity of which the hooked stop  14  of the relevant follower  11  or  12  engages on the counter face  26  of the bolt  25  associated with same. 
     Expressed in other terms, the section of each retaining arm  11 ,  12  running from the stop  14  to the swivel area A 1  extends at first substantially along the surface  21 ,  22  of the pane towards the lower edge  28  of the pane and then runs underneath the lower edge  28  of the pane across the window surface  21 ,  22  towards the associated swivel area A 1  which is mounted on the side E 1   i , E 2   i  of the corresponding plane E 1 , E 2 . The swivel area A 1  is thus located not as is normal in the prior art, on the side E 1   a , E 1   b  of the plane E 1 , E 2  respectively, remote from the window pane  20 . 
     The two retaining arms  11 ,  12  criss-cross underneath the lower edge  28  of the pane and thereby form above the intersection point a U-shaped section for the window pane  20  and underneath the intersection point swivel areas A 1 . 
     If a force F acts in the lifting direction H on the window pane  20  then this force is transferred in the region of the force engagement points  15  to the retaining arms  11  and  12  of the follower  1 . As a result of the design of the follower described above, this results in a torque acting on the retaining arms  11  and  12  through which the retaining arms  11 ,  12  are moved towards each other substantially transversely to the window pane so that each retaining arm  11 ,  12  is pressed against the surface  21 ,  22  of the pane associated with same. This is based on the same principle that also causes scissors to fold up closed when hanging vertically down by their handles. 
     Thus the stronger the force F which acts on the window pane  20  in the lifting direction H then the greater is also the torque through which the retaining arms  11 ,  12  are pressed against the surfaces  21 ,  22  of the window pane. This has the result that the positive locking connection between the follower  1  and window pane  20  is strengthened through the retaining arms  11 ,  12  and the bolt  25 . 
     It thus produces a ‘self-tensioning’ follower which uses the forces which could cause the window pane to become loose from the follower to strengthen the connection between the follower and window pane. 
     The window pane  20  can thereby also be held secured by the follower  1  even in the event of very strong loads in the lifting direction H (e.g. in the event of a crash). 
     Further embodiments of the invention that are based on the principle described above are illustrated in FIGS. 2 to  4 . 
     With the description of these figures, only those features are dealt with in detail where the relevant embodiment differs from the example explained with reference to FIG.  1 . 
     In FIG. 2 a  a follower  1  is shown in side view whose base body has a lower section  2  and an upper section  2 ′. The lower section  2  of the base body thereby serves to connect the follower to a window lifter whilst the upper section  2 ′ of the base body surrounds the window pane  20  in the region of its lower edge  28 . 
     Between the lower section  2  and the upper section  2 ′ of the base body there is a recess into which a counter member  5  of the follower  1  projects. The counter member  5  has an undercut section and the two retaining arms  11 ,  12  of the follower  1  underneath the lower edge of the pane  28  are hung from this counter member  5 . 
     The retaining arm  11  is for clarity shown also separately in FIG. 2 b.    
     The two retaining arms  11 ,  12  which criss cross underneath the lower edge  28  of the pane and the counter member  5  are formed spring-elastic in their lower sections  33  and are inserted under pretension into the recess between the upper section  2 ′ and the lower section  2  of the base body of the follower  1 . 
     The two retaining arms  11 ,  12  are therefore able to swivel about a swivel area A 2  which is formed underneath the lower edge  28  of the pane in the vicinity of the counter member  5 . 
     This is thereby a constructional swivel region wherein there is no actual swivel movement of the retaining arms  11 ,  12  about an ideal axis. Rather the elastic design of the retaining arms  11 ,  12  in their lower sections  33  enables bending of the retaining arms  11 ,  12  which corresponds substantially to a swivel movement of the retaining arms  11 ,  12  about the swivel area A 2 . 
     Even with this embodiment of the invention, the swivel area A 2  is, seen from each retaining arm  11 ,  12 , mounted behind the planes E 1  and E 2  respectively so that it produces a “self-tensioning follower” of the kind described in FIG.  1 . 
     Also, with the embodiment of the invention illustrated in FIG. 3, the base body of the follower has a lower section  2  and an upper section  2 ′ which are separated from each other through a recess. 
     In this recess there is a bearing point underneath the lower edge  28  of the pane to form a swivel axis A 3  for the retaining arm  11 ,  12  of the follower  1 . 
     With this embodiment of the invention, the design of the retaining arms  11 ,  12  comes closest to scissors insofar as these are able to swivel about an actual axis A 3  to which they are attached by their lower sections  35 . 
     Also with this embodiment of a follower  1  according to the invention, a force F acts in the lifting direction H of the window pane which engages through the force engagement points  15  on the retaining arms  11 ,  12  of the follower  1  so that the two retaining arms  11 ,  21  move towards each other. The positive locking engagement between the follower  1  and the window pane  20  is thereby strengthened through the retaining arms  11 ,  12  and the bolt  25 . 
     The follower  1  illustrated in FIG. 4 differs from the embodiments of the invention described up until now in that it only has one swivel retaining arm  11 . 
     The upper section  13  of the retaining arm  11  has a hooked stop  14  which is supported on a counter face  26  of the window pane  20  which is formed by a bolt  25 . 
     The retaining arm  11  is connected underneath the lower edge  28  of the pane through a connecting section  34  of thinner material thickness to the base body  2  of the follower  1 . This connecting section  34  forms a swivel area A 4  which is mounted on the opposite side of the window pane  20  seen from the retaining arm  11 . Thus the retaining arm  11  of the present embodiment has the same structure as the retaining arm  11  illustrated in FIG.  1 . 
     Moreover in the embodiment according to FIG. 4 the retaining arm  11  is not associated with any second retaining arm on the opposite side of the window pane  20 . Rather a rigid follower section  9  extends there where it adjoins the side  22  of the window pane remote from the retaining arm  11 . 
     With the present embodiment, only one retaining arm  11  is provided which, when the window pane  20  is loaded with a force F in the lifting direction H, is moved towards the pane surface  21  associated therewith and ensures a secure positive locking engagement between the follower  1  and the window pane  20  through the hooked stop  14  and the bolt  25 . The rigid follower section  9  thereby only serves as an abutment. FIG. 5 illustrates another exemplary embodiment in which stops  14  extend into opening  24  of the window pane  20 . 
     In short all the embodiments of the invention described above are characterised in that when the window pane is loaded with a force F in the lifting direction H, a torque acts on at least one retaining arm of the follower which counteracts the window pane slipping out from the follower.