Abstract:
The invention relates to a device for providing relative motion between two components of a cable window lifter which lie in the force transfer cord and are prestressed to one another, and functions as a dampener and for ensuring the provision of sensor signals for clamping protection, particularly if severe clamping leads to a sudden and complete standstill of the window pane. The device consists of a component on the casing side and a component positioned directly or indirectly thereto, on which the Bowden of a cable window lifter supports itself, whereby the two displaceable components that are connected to one another through friction locking components are pressed against reciprocally allocated stops by means of a prestressed spring. After completion of the assembly—the connection of the friction locking components is ensured against unintentional loosening through the prestressed spring or one of the components that can be displaced relative to another.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of German Application No. 198 52 977.5 filed Nov. 17, 1998, the disclosure of which is incorporated fully herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a device for providing relative motion between two components of a cable window lifter that lie in the force transfer cord and are positioned prestressed to one another. The device functions as a dampener and/or for ensuring the provision of sensor signals for clamping protection, in particular when severe clamping leads to a sudden and complete standstill of the window pane. 
     BACKGROUND OF THE INVENTION 
     DE 196 18 853 C1 disclosed a motor-driven window lifter with electronic clamping protection, whereby in the flux of force between the drive unit and the window pane there is a prestressed spring with a degressive course. When the prestress force is exceeded, this leads to relative motion of the components that are tensioned to one another, whereby the total stress of the spring is reduced and the clamping force is correspondingly reduced. It is provided that the spring is positioned within an essentially rigid case. The case, which for the purpose of supporting the great prestress force is formed in a comparatively stable way, has a high space requirement that is often not available. In addition, the assembly of the device described requires relatively high resources. The contents of DE 198 52 977.5 are incorporated fully herein by reference. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to develop a type of device that is characterised by a reduced space requirement, simple assembly, and a small number of components. In addition, with the use of as little material as possible, high stability and operating reliability should nonetheless be ensured. When clippable connecting components are provided for connecting the two tensioned and displaceable components a conflict is solved whereby on the one hand the clippable connecting components should be formed as flexibly as possible for a simple connection process and on the other hand, the clippable connecting components should be formed as rigidly as possible for ensuring high stability of the connection. 
     According to an embodiment of the present invention, after complete installation of the device, the connection between the friction locking components is ensured against unintended loosening. This occurs preferably through a functional component of this device, thus through one of the components that can be displaced relative to the other, or through the prestressed spring itself, which brings about the pressing apart of the friction locking components. 
     According to an embodiment of the present invention, after assembly of the device, the friction locking components are at least partly surrounded and supported by the spring in such a way as to prevent a bending open of an elastically deforming or radially displaceable friction locking component. The corresponding friction locking component must therefore simply take up the pulling forces arising through the prestress. Radially oriented forces, such as bending forces, are taken up by the spring. Ideally, the clippable friction locking components of the two axially displaceable components lie completely between the end-side supports of the spring in such a way that the spring encompasses the friction locking components completely. 
     In adapting to the construction and assembly concept of the window lifter, the device according to an embodiment of the present invention can be formed either as a pre-manufactured unit that can be assembled separately, or as an integral component of the drive unit. For a pre-manufactured unit it would be necessary to provide a bearing opening in a casing component of the drive unit, so that one of the displaceable components of the device can be inserted and supported against a stop. Alternatively, the friction locking components are a constituent part of a casing component and extend along the cable axis. 
     The friction locking components of the other component are preferably a constituent part of a generally used guiding shell, which through the interposition of a cable length compensation spring supports the end of a Bowden tube. They can, however, also be a constituent part of an adapter that is positioned between the other component carrying friction locking components and the guiding shell. This enables the device according to the invention to be easily inserted into series which are already running by merely shortening the length of a Bowden tube. All other components can be taken over without any changes. 
     Through the securing of the engaging friction locking components of the components that can be displaced relative to one another and are tensioned with one another, the conditions are created whereby clippable connections can be used as friction locking components. This is a basis for solving the conflict that arises because in order to produce a simple connection between two components, elastically deforming friction locking components should be sought, but the tensioning of these components through a comparatively high spring force requires a solid formation of the connection points. According to the invention, the conflicting demands are met because, at least one component of the device that functions to ensure relative motion after assembly additionally assumes a securing function for the permanent engaging of the friction locking components. 
     The invention can be brought into effect in embodiments which vary greatly in their construction. Depending upon these different embodiments, for example, either one or both of the clippable areas participating in the connection of the displaceable components should be elastically formed. When both of the clippable areas are elastically formed, the relative degree of deformation of the clippable areas can be kept comparatively lower. In certain circumstances, however, securing measures for both clippable areas are necessary, which guarantee permanent friction locking. The clippable area that springs inwards can be secured via an axial channel, into which the securing component is inserted, e.g. in the form of a guiding shell supporting the Bowden. When only one clippable area is elastically formed, the clippable area of one component is formed essentially rigidly, whereas the other clippable area must have the entire flexibility necessary for the production of friction locking. 
     The invention is also intended to include a device with a separate securing component, that can be used in association with the generally used guiding shells for cable length compensation of a Bowden tube window lifter. Special stops formed contrary to the assembly direction are intended to guarantee security against the loss of the separate securing component during transport of the device up until its assembly. 
     According to an additional embodiment of the invention, shell-like components or other components that can be placed radially are used, whereby these components form one of the two displaceable components and support the prestressed spring on one side. The securing of the functional position of these components takes place through friction locking with the end of the spring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described below by reference to embodiments of the invention and the figures illustrated, wherein: 
     FIG. 1 a  is a side view of a device with outer clippable areas and a prestressed spring as the securing component. 
     FIG. 1 b  is a transverse section of FIG. 1 a.    
     FIG. 1 c  is a perspective diagram of FIG. 1 a.    
     FIG. 1 d  is the same as FIG. 1 c,  but without springs. 
     FIG. 1 e  is a perspective diagram of the relatively displaceable component on the casing side. 
     FIG. 2 is a transverse section of a device with a securing component completely encompassing the elastic clippable area. 
     FIG. 3 is a transverse section of a device with guiding channels in both displaceable components. 
     FIG. 4 a  is a side view of a device with outer and inner clippable fields as well as outer and inner securing components. 
     FIG. 4 b  is a transverse section of FIG. 4 a.    
     FIG. 4 c  is a perspective diagram of FIG. 4 a.    
     FIG. 4 d  is the same as FIG. 4 c,  but without a spring. 
     FIG. 5 a  is a side view of a device with relatively displaceable components which are not tensioned. 
     FIG. 5 b  is a transverse section of FIG. 5 a,  rotated by 90°. 
     FIG. 5 c  is a transverse section of FIG. 5 a  (Section B—B). 
     FIG. 5 d  is a perspective diagram of FIG. 5 a.    
     FIG. 5 e  is a perspective “exploded” diagram of the two displaceable components. 
     FIG. 5 f  is a cross-section through the device of FIG. 5 a  (Section C—C). 
     FIG. 5 g  is a plan view of the device. 
     FIG. 5 h  is a perspective “exploded” diagram of the device of FIG. 5 a.    
     FIG. 6 a  is a partially sectional side view of a device with a flexible, clippable area that is in pipe form. 
     FIG. 6 b  is a transverse section of FIG. 6 a.    
     FIG. 6 c  is a transverse section of FIG. 6 a,  rotated by 90° with the spring removed. 
     FIG. 6 d  is a perspective diagram of FIG. 6 a.    
     FIG. 6 e  is a perspective exploded diagram of the relatively displaceable components. 
     FIG. 7 a  is a side view of a device wherein one of the two relatively displaceable components is radially positionable. 
     FIG. 7 b  is a transverse section of FIG. 7 a,  rotated by 90°. 
     FIG. 7 c  is a perspective diagram of FIG. 7 a.    
     FIG. 7 d  is the same as FIG. 7 c,  but without a spring. 
     FIG. 8 a  is a side view of a device one of the two relatively displaceable components is double-shell-formed and radially erectable. 
     FIG. 8 b  is a transverse section of FIG. 8 a,  rotated by 90°. 
     FIG. 8 c  is a perspective diagram of FIG. 8 a.    
     FIG. 8 d  is the same as FIG. 8 c,  but without a spring. 
     FIG. 9 is a dual cable Bowden tube window lifter with an electric drive and a device according to an embodiment of the present invention which is inserted into a cable exit of the drive case. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 a  to  1   e  show a device according to an embodiment of the present invention from different perspectives, whereby rigid inner friction locking components of one component  2   a  in the form of a ring-form projection  24   a  engage with flexible, clippable friction locking components  11   a  of the other component  1   a.  The hook-like friction locking components  11   a  of the component  1   a  form the free end of the area  10   a,  which is divided into elastic segments through axially running slits  100   a  (only shown in FIG. 1 e ). At the other end, the component  1   a  merges into a pipe-formed guiding area  14   a  with a reduced diameter, whereby on the inner side this guiding area  14   a  takes up the guiding tube  25   a  of the component  2   a,  and whereby on the outside it carries a spring  4  supported on the casing side to compensate for the cable length. 
     The upper end of the component  2   a  is formed as a supporting area  20   a  for a Bowden tube which is inserted into a tube-like opening  22   a  and supports itself with its end on the stop  23   a.  For the purpose of supporting the spring  3 , the outer contour of the supporting area  20   a  is formed as a ring-form projection  21   a.  The other side of the spring  3  is supported on the ring-form projection  12   a  of the component  1   a,  whereby the spring  3  overlaps the area of the friction locking components  11   a,    24   a,  and thus ensures a secure positioning of the elastic fields  10   a,  even when there is very great axial tension. The prestress force of the spring  3  is generally selected to correspond at least to the sum of the mass force of the window pane and all the forces that are effective up to the device. Therefore, via the lift of the window pane until arrival at the sealing area on the end position side, there is no compressing of the spring  3 . 
     As soon as the supporting force exerted by the Bowden tube on the component  2   a  exceeds the prestress force of the spring  3 , the latter is compressed and the component  2   a  is displaced in the component  1   a.  This displacement is limited by a stop  13   a,  which forms the passage between the areas  10   a  and  14   a.  In any case, however, the possible relative motion between the components  1   a  and  2   a  is dimensioned to be sufficiently large to ensure that, in the event of a blocking of the displacement movement of the window pane, the drive can still generate the signals necessary for the recognition of the blocking. In the case of a severe, i.e. sudden, blocking, an additional sensor signal must as a rule be fed to the evaluation electronics. The conditions are fulfilled when the relative motion between the two components  1   a,    2   a  is sufficient for the generation of a signal period. It is thereby ensured that after the beginning of the clamping at least one further signal is generated. 
     In comparison with the above-described embodiment, the device according to an alternative embodiment shown in FIG. 2 differs essentially through an axially displaced positioning of the rigid friction locking component  24   b  of the component  2   b  and of the ring-form projection  12   b  of the component  1   b.  Through the positioning of the ring-form projection  12   b  in the area of the stop  13   b,  the spring  3  overlaps the entire elastically deforming area  10   b  and thus ensures friction locking between the friction locking components  11   b  and  24   b.  Note that in FIG.  2  and all other figures, items denoted by a number immediately followed by a subscript letter correspond generally to similarly numbered items with different subscript letters that are appearing in separately numbered figures showing alternate embodiments of the invention. 
     FIG. 3 shows an additional embodiment that is very similar to the device shown in FIG.  1 . The device shown in FIG. 3 differs in that the guiding tube  25   c  which is connected to the Bowden supporting area  20   c  does not extend through the component  1   c,  but instead ends in the guiding area  14   c.  Instead, a further guiding tube  15   c  connects to the guiding area  14   c,  so that the cable is fed through two separate channels that are positioned axially behind one another. 
     The embodiment shown in FIGS. 4 a  to  4   d  has displaceable components  1   d,    2   d,  whereby there are friction locking components  11   d,    23   d  which are worked onto the spring elastic fields  10   d,    22   d.  To prevent the friction locking components  11   d  of the component  1   d  on the casing side from moving away inwards, a guiding shell  55   d  is inserted into a corresponding central channel. The guiding shell is also shown with a bottom  53   d  and a ledge  54   d  between the supporting area and the channel. The position of the friction locking component  23   d  of the component  2   d  on the Bowden side is, as in all the previously described examples, ensured by the encompassing of the spring  3 . In order to ensure cable length compensation, a spring  4  is provided, that supports itself on the one hand on the ring-form projection  51   d  of the supporting area  50   d  and on the other hand on an inwardly oriented projection  20   d  of the component  2   d,  which also serves as a stop for limiting the relative motion between the components  1   d,    2   d.  An advantage of this embodiment is the possibility of further use of guiding shells  5   d  commonly in use and the simple rearrangement of devices that are already positioned in series without a tensioned spring  3 . 
     FIGS. 5 a  to  5   h  show a device whereby the prestressed spring  3  supports itself between a ring-form projection  12   e  and a hook-like friction locking component  11   e  of the component  1   e  on the casing side that is positioned on the free end of the elastic area  10   e.  The Bowden side component  2   e  can be inserted between the spring sides (areas  10   e ) and into the axial channel  16   e  attached thereto, whereby this Bowden side component  2   e  works against an inward evasion of the friction locking components  11   e.  The spring side  10   e  has in the vicinity of the friction locking component  11   e  a ledge forming a stop  15   e,  which—in association with the ledge of the inserted component  2   e  forming a stop  25   e —forms security against loss. 
     The component  2   e  also has an axial channel  27   e,  in which the guiding tube  55   e  of the guiding shell  5   e  is fed. The supporting field  50   e,  which takes the Bowden tube end, has on its outer contour a spring  4  for cable length compensation, whereby this spring  4  supports itself on the one hand on the ring-form projection  51   e  and on the other hand on the axial stop  24   e  of the upper end of the displaceable component  2   e.  In the event of cable lengthening, the spring  4  would push the guiding shell  5   e  out of the channel  27   e  of the component  2  by the corresponding length. 
     As can be clearly seen from the FIGS. 5 b  and  5   c  as well as the FIGS. 5 e  and  5   h,  the displaceable components  1   e  and  2   e  are not formed rotation-symmetrically. Instead they have opposite-lying, differing sectors with differing functions. Thus, the sector  20   e  of the component  2   e  is not only equipped with a stop  24   e  for the cable length compensating spring  4 , but is also equipped with a projection  21   e,  which transfers the supporting force of the Bowden tube on to the allocated end of the prestressed spring  3 , and upon the prestress force being exceeded compresses the spring  3 , whereby this goes hand in hand with relative motion between the two components  1   e,    2   e  and a lifting of this spring end from the stops  11   e.  The component  1   e  also has a base  10 ′ e.  On the other side of the projection  21   e  the sector  20   e  has a continuation, which functions in a stop  23   e  in association with the stop  13   e  of the component  1   e  for the purpose of limiting the relative motion. The stopper  22   e  attaching thereto serves for the guiding of the component  2   e  in the channel  16   e  of the component  1   e.  The area  26 ′ e  extending over the stopper  22   e  into the vicinity of the projection  21   e  serves for guiding the spring sides  10   e  and continues via a ledge  25   e  in the surface  26   e.  As already mentioned, the combination of the ledges  25   e  with the ledges  15   e  on the inner sides of the spring sides  10   e  gives rise to a security against loss, whereby this is intended to prevent the Bowden side component  2   e  slipping unintentionally out of the component  1   e  on the casing side. 
     FIGS. 6 a  to  6   e  show an additional embodiment of the invention. This embodiment uses a component  1   f  on the casing side, which on the one hand can be connected via the coupling area  14   f  to a case (not illustrated), and which on the other hand has an elastically deforming area  10   f  with an essentially cylinder-casing-like contour. The area  10   f  is provided with recesses  11 ′ f  which are limited by the projection  12   f  provided for supporting the spring  3  and by a closed ring  11   f,  whereby the inner surface of the ring  11   f  limiting the recess  11 ′ f  functions as a friction locking component for engaging the friction locking component  23   f  of the component  2   f  on the Bowden side. The friction locking component  23   f  is formed as a hook-like projection on the stopper  22   f.    
     Before the connection of the two components  1   f  and  2   f,  the spring  3  must be pushed away from the areas of the friction locking components  11   f,    23   f,  in order to allow the elastic deformations necessary for the connection. Upon insertion of the component  2   f  into the component  1   f,  first the ring  11   f  is elastically deformed through the friction locking components  23   f  until the friction locking components  23   f  engage in the recess. The spring  3  can subsequently be released, whereby the spring  3  now supports itself between the projections  12   f  and  21   f  and encloses the area of the friction locking components  11   f  and  23   f  in such a narrow way that the degree of deformation of the friction locking components  11   f,    23   f  necessary for the uncoupling is excluded through the spring  3 . A limitation of the spring excursion between the components  1   f  and  2   f  is given by the axial length of the recess  11 ′ f  in that the edge of the recess  11 ′ f  serves as a stop for the friction locking component  23   f.    
     All of the above-described devices have displaceable components  1 ,  2  that are positioned to one another through an axial assembly movement. This does not apply to the embodiments of the invention of FIGS. 7 and 8, which are explained below. In the embodiments shown in FIGS. 7 and 8, the assembly movement of the component  1   g,    1   h  on the casing side takes place radially to the longitudinal axis of the component  2   g,    2   h  on the Bowden side. 
     FIGS. 7 a  to  7   d  show a component  1   g  on the casing side with a cut-away portion  18   g,  which is intended to facilitate a radial positioning on the other component  2   g.  The component  1   g  has a radially inward area, whereby this area, upon completion of the assembly, engages a cut-away portion  28   g  of the component  2   g  and can engage with a projection of the component  2   g  functioning as a stop  24   g.  Between the projections  12   g  and  21   g,  the prestressed spring is supported. A permanent and secure positioning of the two components  1   g  and  2   g  in relation to one another can be ensured by an axially directed arching  11   g  over the projection  12   g  on the side lying opposite the cut-away portion, and by an expansion of the supporting area  20   g  of the component  2   g  corresponding approximately to the inner diameter of the spring  3 . 
     If the prestress force of the spring  3  is exceeded by the supporting force of the Bowden tube inserted into the opening  22   g,  the component  2   g  is depressed, whereby the stop  11   g  displaces itself within the cut-away portion  28   g.  The maximum possible relative motion is again determined through the internal width of the cut-away portion after the assembly of the component  1   g.    
     The embodiment shown in FIG. 8 corresponds essentially to that of FIG. 1, but with the difference that the component  1   h  consists of two half shells divided by slits  16   h,  whereby these half shells are connected to each other by means of a film joint  15   h.    
     FIG. 9 shows a dual cable Bowden tube window lifter with two guiding passages  8   a,    8   b  on which grippers  9   a,    9   b  are positioned in a sliding way for the purpose of connection of the window pane. The driving force is transferred from a drive unit  7  consisting of a motor  71  and drive  70  via the cable loop to the grippers  9   a,    9   b.  The cable is thereby guided trough Bowden tubes  6  and over upper and lower cable deflections  80 ,  81 . A device according to the embodiment shown in FIG. 5 is connected to one of the cable exits of the drive  70 .