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[0001]    The present application claims the priority of German patent application no. 10 2007 016 953.3 “Guide Rail Assembly and Driving Element for Motor Vehicle Window Lifters and Method for the Production Thereof” filed on 5 Apr. 2007, the content of which is expressly included herewith by way of reference for the purposes of disclosure. 
       FIELD OF THE INVENTION  
       [0002]    The present invention relates in general to guide rail assemblies made of plastic material for motor vehicle window lifters and relates in particular to a guide rail assembly according to the preamble of claim  1 , a driving element (follower) for motor vehicle window lifters and a method for the production thereof. 
       BACKGROUND OF THE INVENTION 
       [0003]    From the prior art are known plastic carrier plates, also referred to as assembly carriers, which after being connected to a module carrier enable a moisture-proof separation of the wet space and the dry space, a pre-assembly of door module components and door module functions, for example of door operating elements, electric window lifters, side airbag module, speakers or similar, and allow for high mechanical strength requirements with easy installation. The advantage of using plastic as a material emerges particularly in that it is possible as a result to produce the carrier plate in a simple manner by means of injection moulding. 
         [0004]    Examples of such carrier plates are disclosed for example in DE 199 44 965 A1 by the applicant or DE 197 32 225 A1 (corresponding to U.S. Pat. No. 5,906,072), the content of which is expressly included in the present application by way of reference. 
         [0005]    DE 10 2005 033 115 A1 (corresponding to WO 2007/006296 A1) discloses a unit carrier made of plastic material for a motor vehicle door with a guide rail moulded integrally thereon in one piece. The guide rail should be characterised by high stability and rigidity in order to resist the considerable forces arising during operation of the guide rail. The guide rail comprises two guide webs spaced apart from each other formed on each of which are guide protrusions that protrude inwards away from the respective guide web. Additional stiffening beads and concavities are provided in the region of the guide rail to increase the rigidity. Thus the guide webs are not bendable in the sense of the present application. 
         [0006]      FIG. 7  of this application illustrates an injection moulding tool for the production of such a guide rail. The injection moulding tool comprises one central slider and two lateral sliders in the region of the guide rail, which have lateral protrusions to form the guide protrusions on the guide webs. Thus the total number of the injection moulding tool&#39;s sliders is comparatively high which increases the costs for the injection mould and also for the injection moulding process. As there are no recesses provided on the central slider for moulding of the guide protrusions, the principle of demoulding the guide rail assembly from (out of) the injection moulding tool also deviates distinctly from that according to the present invention. 
         [0007]    DE 10 2004 063 514 A1 (corresponding to WO 2006/069 559 A1) relates to a window pane made of synthetic material for motor vehicles. Disclosed is a carrier plate made from a plastic material on which a guide rail is formed integrally. To safeguard against transverse forces, the guide rail is stepped in design as illustrated in  FIGS. 2A to 2C . The guide rail does not have two guide webs spaced apart from each other with guide protrusions formed thereon protruding inwards or outwards. The principle of production, particularly demoulding from (out of) an injection moulding tool, also deviates distinctly from the procedure according to the present invention. 
         [0008]    DE 36 00 413 C2 (corresponding to U.S. Pat. No. 4,700,508) discloses a central guide rail, formed from a sheet metal profile and fixed to the motor vehicle bodywork, for a motor vehicle window lifter, wherein slide elements are disposed on the guide rail spaced apart from each other and are slidable on flanges of the guide rail which are orientated perpendicularly and parallel to the window pane. 
         [0009]    A cost benefit emerges particularly if the guide rail, which serves to guide a driving element serving to connect the window pane to the window lifter, is also made of plastic material, is in particular integrally with the carrier plate, namely by means of injection moulding of a plastic material. In order to guide the window pane and the driving element securely in a direction at right angles to the vehicle&#39;s longitudinal direction, the driving element must engage behind the guide rail&#39;s guiding profile. Only in this way does the driving element remain securely guided on the guide rail even at comparatively high accelerations in the motor vehicle&#39;s transverse direction such as occur particularly when the door is slammed shut. As explained previously particularly on the basis of DE 10 2005 033 115 A1, comparatively large sliders are necessary in the moulding tool in order to implement such a rear grip when injection moulding the carrier plate from a plastic material. This increases the cycle time when injection moulding the carrier plate and thus also the costs and risks. 
       SUMMARY OF THE INVENTION 
       [0010]    Thus it is an object of the present invention to provide a guide rail assembly made of a plastic material for motor vehicle window lifters, said assembly being inexpensive and easy to produce and install and which reliably guides a driving element. According to a further aspect of the present invention, there is also to be provides a driving element for a motor vehicle window lifter made of a plastic material, said driving element being inexpensive and easy to produce and install and being reliably guided on a guide rail, in particular on a guide rail which will be explained subsequently in greater detail. According to further aspects of the present invention, there is also to be provided a method for the production of a guide rail assembly and a driving element, as explained subsequently. 
         [0011]    These and further objects are achieved according to the present invention by means of a guide rail assembly having the features according to claim  1 , by a driving element or follower according to claim  20  and by a method for the production or assembly thereof according to claims  17 ,  27  and  28 , respectively. Further advantageous embodiments are the subject-matter of the related dependent claims. 
         [0012]    Thus the present invention proceeds according to a first aspect from a guide rail assembly for motor vehicle window lifters, which is formed from a plastic material and comprises a flat carrier and at least one guide rail for guiding a window lifter driving element, wherein the guide rail has two guide webs spaced apart from each other, which protrude from the carrier, and wherein guide protrusions are formed on the guide webs, each of which extends over the entire guidance length of the guide webs, and which protrude by a predetermined distance inwards or outwards from the respective guide web such that the driving element cooperating therewith is securely guided against detachment perpendicular to the carrier. 
         [0013]    According to the invention, the guide webs are designed such that in the region of the guide protrusions they are each elastically bendable inwards or outwards by at least the predetermined distance. Thus according to the invention, the guide rail may be demoulded from an injection moulding tool by means of elastic deformation of its guide webs. Consequently, according to the invention, it is possible to reduce the number of sliders necessary for the moulding tool. In particular, no cross sliders or transversal sliders are necessary for forming the guide webs as all the moulding tool parts can be withdrawn in the same direction in order to demould the guide rail from (out of) the moulding tool. 
         [0014]    In this case the guide protrusions protrude preferably perpendicularly or, according to further embodiments, virtually perpendicularly away from the carrier and are formed integrally therewith. The carrier may, according to a further embodiment, be extended into a carrier plate basically known from the prior art, also referred to as a door module carrier, which can also carry at least one further guide rail. At the same time, the guide rail is formed according to the invention from two guide webs spaced apart from each other, which together form a guide rail having a substantially U-shaped cross-section, wherein a guide protrusion protrudes inwards and/or outwards from the inside or outside of the guide webs, said guide protrusion cooperating positively with correspondingly formed sections of the driving element in order to guide it securely in the guide rail&#39;s longitudinal direction and to safeguard against detachment of the driving element perpendicular to the longitudinal direction, i.e. in the intended transverse direction of the vehicle. For this purpose the driving element preferably engages behind one or a plurality of the guide rail&#39;s guiding protrusions as explained below. 
         [0015]    To implement such a rear grip, the protrusions each have, according to a further embodiment, a guide surface facing towards the carrier, which preferably represents a plane, wherein the notional extension of the guide surface includes a first acute angle with a line perpendicular to the carrier. The protrusion of the inclined guide surface onto the plane defined by the carrier in the region of the guide rail thereby defines the predetermined distance referred to previously by which the guide webs are bent elastically inwards or outwards on demoulding from the moulding tool. Sections of a moulding tool also engage, in a similar manner to the driving element, behind the guide protrusions after injection moulding of the guide rail assembly. According to the invention, demoulding of the guide rail assembly from the moulding tool is made easier in that the guide surface previously mentioned extends at an angle and not in parallel with the carrier. According to a further embodiment, however, such a rear grip can also be still be implemented in principle if the guide surface previously mentioned extends in parallel with or substantially in parallel with the carrier. 
         [0016]    According to a further embodiment, the protrusions each also have a bevel facing away from the carrier, the notional extension o which includes a second acute angle with a line perpendicular to the carrier. In this case the first acute angle is smaller than the second acute angle. The bevel facing away from the carrier is thus formed preferably steeply in the installation (assembly) direction to enable effortless clipping or pushing of the driving element onto the guide rail. As a result, it is possible to advantageously reduce installation forces in particular. On the other hand, the guide surface facing the carrier is formed flatter in this case to enable high detachment forces of the driving element perpendicular to the carrier and thus to ensure a high holding force of the driving element on the guide webs. However, the angle must be chosen such that demoulding of the guide rail assembly from the injection mould or from the tool can be carried out without problems, particularly without damage to the guiding regions of the guide rail assembly. 
         [0017]    The angles of inclination of the guide surface or bevel referred to previously are appropriately chosen in this case such that the limits of elastic deformability of the material regions concerned are taken into account when designing the tool and when specifying the dimensions of the portions of the guide rail. The demoulding forces arising in this case are not essential for the invention. 
         [0018]    According to a further embodiment, the guide protrusions each have a spherical, i.e. essentially ball-shaped or outwardly convex guide surface on the side facing towards the carrier, which merges into the associated guide web at an obtuse angle. It is also possible to implement forcible demoulding of the guide rail assembly from the moulding tool with elastic deformation of the guide webs due to a spherical guide surface. 
         [0019]    According to a further embodiment, the guide webs in the region of the guide protrusions are each bendable elastically inwards or outwards by the predetermined distance on operation of a minimum force, whereby the minimum force corresponds to a force required for demoulding of the guide rail or guide rail assembly made of plastic from the moulding tool. Expediently, the required minimum force is greater in this case than a maximum force which corresponds to a maximum holding force of the driving element on the guide rail during intended use. Such a maximum holding force may be specified here, for example, by the driving element&#39;s mass multiplied by a maximum intended transverse acceleration, i.e. acceleration in the vehicle&#39;s transverse direction. Consequently, sufficient resistance to detachment of the driving element on the guide rail is implemented even without additional securing elements which secure the driving element on the guide rail. 
         [0020]    According to a further embodiment, the guide rail assembly referred to above comprises a window lifter driving element having contact sections, which are formed in correspondence with the guide protrusions of the guide webs and cooperate therewith in order to guide the driving element securely perpendicular to the carrier to prevent detachment. Preferably, the window lifter driving element is guided in the process substantially without play in the vehicle&#39;s longitudinal direction and secured against tilting about the guide rail&#39;s longitudinal axis. 
         [0021]    According to a further embodiment, formed in each case on the driving element are securing means which counteract or prevent or inhibit bending of the guide webs. Here the securing means may be permanently in contact on the inner or outer sides of the guide webs or may only come into contact with them when the guide webs are bent inwards or outwards and namely by a distance that is smaller than the predetermined distance previously referred to which would lead to cancellation of the positive fit previously referred to between the driving element and the guide protrusions. At the same time the securing means have sufficient rigidity, particularly in the vehicle&#39;s longitudinal direction, to suppress or inhibit bending or further bending of the guide webs. 
         [0022]    Expediently, the driving element has a central protrusion which protrudes into an inner side of the essentially U-shaped guiding profile of the guide rail. 
         [0023]    The central protrusion may at the same time be thickened in a mushroom-shape in order to implement the rear grip referred to previously, in particular in order to implement a positive fit between the mushroom-shaped thickened section of the driving element and the guide protrusions of the guide webs protruding into the inner volume of the guide rails. In such an embodiment, the securing means are disposed on an outer side of the guide webs, i.e. on a side of the guide webs opposing the guide protrusions. 
         [0024]    According to a further embodiment, the securing means are designed as resilient webs, which are bent up at an acute angle and, directed towards a base of the driving element, are inclined towards the outsides of the guide webs. In this way it is possible to implement an advantageously high intrinsic stiffness of the securing webs against outward bending of the guide rail&#39;s guide webs. Preferably, in this case the mushroom-shaped thickening on the driving element&#39;s central section protrudes further into the inside of the guide rail than the elastic securing webs stand out from the driving element&#39;s base. In this way it is possible to virtually exclude detachment of the driving element from the guide rail in the vehicle&#39;s transverse direction. 
         [0025]    According to a further embodiment, the guide protrusions are provided on the outside of the guide web, whereby resilient securing webs protrude in the manner of wings from the outer sides of the driving element, the front free ends of said securing webs being designed to correspond with the guide protrusions and being in contact therewith. At the same time the driving element is disposed practically jammed against the guide webs of the guide rail which reliably prevents detachment of the driving element from the guide rail in the vehicle&#39;s transverse direction. Expediently, the contact surfaces are formed as concave dished webs. 
         [0026]    For reliable introduction of the driving element into the guide rail profile referred to previously, introductory bevels are provided at the same time on the sides of the guide protrusions facing away from the carrier, said bevels coming into contact with a central protrusion of the driving element and/or with the securing means on introduction of the driving element into the guide rail and so bringing about elastic bending of the guide webs of the guide rail or of the securing means on introduction of the driving element into the guide rail profile. 
         [0027]    According to a further aspect of the present invention, a method is provided for the production of a guide rail assembly, as described previously, by means of injection moulding from a plastic material. To form the guide rail, the moulding tool in this case comprises three movable moulding tool parts, which together form cavities for forming the flat carrier and for forming the guide webs with the guide protrusions formed integrally therewith. According to the invention, in the process the part of the moulding tool defining the guide rail&#39;s interior is designed in a wedge shape, thus its marginal surfaces run towards or away from each other at an acute angle. In this case, for forming the guide rail profile, the wedge-shaped moulding tool part is disposed between two adjacent moulding tool parts, which are expediently formed in one piece. According to the invention, these three movable moulding tool parts are withdrawn in the same direction when demoulding the guide rail assembly from the moulding tool. The moulding tool according to the invention thus manages without a cross slider (transverse slider) which conventionally leads to an increased cycle time and thus to higher costs and risks. When the wedge-shaped part of the moulding tool is withdrawn, there is elastic bending of the guide webs forming the guide rail at the same time, as described previously. 
         [0028]    According to a further aspect of the present invention, which may also in principle be claimed separately by means of an independent claim, but which is particularly designed or suitable for a guide rail assembly, as described previously, according to the invention a driving element for motor vehicle window lifters is further provided, which has at least one U-shaped longitudinal recess and is comprised of a first material, expediently of plastic and produced in a plastic injection moulding process. According to the invention, the driving element has at least one sliding insert, which is formed from a second material that is different from the first material and which is held securely in the relevant longitudinal recess of the body. At the same time the sliding insert has a guide groove, which is formed to correspond at least in sections to a guide web of the associated guide rail such that the driving element (follower) is movably guided in the guide web&#39;s longitudinal direction by positive-fit engagement of the guide web in the guide groove and is secured against detachment perpendicular to the longitudinal direction. 
         [0029]    The sliding insert is thus formed as a separate component from a different material such that, according to the invention, it is possible to provide a particularly appropriate tribological pairing for the counterpart, i.e. for the associated guide web. 
         [0030]    According to a further preferred embodiment, according to the invention, a guide rail assembly is provided, which comprises a driving element (follower), wherein a longitudinal recess is formed in the driving element, which extends parallel to the carrier&#39;s guide webs, and whereby a locking web furthermore protrudes from the carrier, said locking web engaging in the longitudinal recess so as to counteract bending of the web&#39;s surfaces forming the longitudinal recess and/or to prevent the at least one sliding insert from popping out of the associated U-shaped longitudinal recess on detachment of the driving element perpendicular to a plane defined by the carrier. In this manner the locking web locks each sliding insert inserted into the driving element. 
         [0031]    At the same time, according to the invention, it is possible to simplify the assembly of a guide rail assembly which comprises a guide rail and a driving element engaging therein. The driving elements are conventionally threaded (inserted) into the guide rail profile at the top and bottom end of the guide rail and then slid into a position determining the window lifter&#39;s assembly position. As also with the previously mentioned first aspect of the present invention, relating to the guide rail assembly in which the driving element may be pressed onto or clipped into the guide rail under elastic deformation of the guide webs in the vehicle&#39;s transverse direction, the driving element may also, according to the second aspect of the present invention, be assembled by pressing on or clipping in under the application of force in the vehicle&#39;s transverse direction. In this case, first of all the appropriate sliding insert is placed onto or slid onto the associated guide web, if necessary under elastic deformation of side walls of the U-shaped sliding insert. The driving element is subsequently pushed onto the sliding insert or sliding inserts such that each sliding insert is accommodated in the driving element&#39;s associated longitudinal recess and thus a driving element is formed which is securely guided on the guide web in its longitudinal direction but is secured on the guide web against detachment perpendicular to the longitudinal direction, i.e. in the vehicle&#39;s transverse direction. 
         [0032]    According to a preferred alternative embodiment, the sliding inserts are, however, first inserted in the driving element, in particular clipped in, in order to thus form a pre-assembled driving element unit. This is then placed on the associated guide webs in such a manner that the driving element is movably guided on each guide web in the longitudinal direction thereof and is secured in a direction perpendicular thereto. Subsequently, the driving element is pushed into a region in which the carrier&#39;s locking webs engage in the driving element&#39;s longitudinal recess in such a manner that bending of the driving element&#39;s surfaces forming the longitudinal recess and/or popping of the at least one sliding insert out of the associated U-shaped longitudinal recess on detachment of the driving element perpendicular to a plane defined by the carrier is counteracted such that the sliding inserts are locked or secured in the driving element. 
         [0033]    At the same time, the driving element may comprise securing means in order to hold the sliding insert securely in each longitudinal recess. Basically, such securing means may be implemented by means of a friction fit, force fit or positive fit. Especially preferred, the securing means according to the invention are implemented by means of a positive fit. This may be implemented by the engagement of securing protrusions and securing recesses formed on the driving element and the sliding insert respectively into securing recesses and securing protrusions corresponding to the sliding insert or the driving element. 
         [0034]    According to a preferred embodiment, the securing means in this case are implemented as protruding longitudinal edges of the driving element&#39;s relevant longitudinal recess. Thus the sliding insert may be introduced therein by clipping on of the driving element. 
         [0035]    In a further embodiment, having two sliding inserts spaced apart from each other, a central web may be formed between the sliding inserts, said web having a central longitudinal recess, which enables elastic bending of the side walls limiting the driving element&#39;s longitudinal recesses when the sliding inserts are clipped in. At the same time, securing hooks, which hold the sliding inserts securely in the longitudinal recess by means of positive fit, may be formed on the central web. 
     
    
     
       OVERVIEW OF FIGURES  
         [0036]    The invention will be described in the following in an exemplary manner and with reference to the associated drawings, from which will ensue further features, advantages and objects to be achieved. The figures show: 
           [0037]      FIG. 1  in a schematic cross-sectional view the engagement of a driving element in a guide rail according to a first embodiment of the present invention; 
           [0038]      FIG. 2  in a schematic sectional view three moulding tool parts for injection moulding of the guide rail assembly according to  FIG. 1 ; 
           [0039]      FIG. 3  the guide rail assembly according to  FIG. 1  in a first phase of demoulding from the moulding tool according to  FIG. 2 ; 
           [0040]      FIG. 4  the guide rail assembly according to  FIG. 1  in a second phase of demoulding from the moulding tool according to  FIG. 2 ; 
           [0041]      FIG. 5  in a schematic cross-sectional view the engagement of a driving element in a guide rail of a guide rail assembly according to a second embodiment of the present invention; 
           [0042]      FIG. 6  in a schematic sectional view the production of a guide rail according to a third embodiment of the present invention in a moulding tool with three movable moulding tool parts; 
           [0043]      FIG. 7  the cooperation of a driving element with the guide rail according to  FIG. 6  according to a third embodiment of the present invention; 
           [0044]      FIG. 8  a driving element with two sliding inserts of a different material according to a further embodiment of the present invention; 
           [0045]      FIG. 9   a  a driving element according to a further embodiment of a guide rail assembly of the present invention, which is held securely on the carrier against detachment perpendicular to the carrier using a locking web provided on the carrier; 
           [0046]      FIG. 9   b  in a schematic partial view from above the guide web of the guide rail assembly according to  FIG. 9   a;    
           [0047]      FIG. 10   a  in a partial section and in a view from above the cooperation of the driving element and the locking web of the guide rail assembly according to  FIG. 9   a  on attaching the driving element to the guide webs close to their end region; and 
           [0048]      FIG. 10   b  in a partial section and in a view from above the cooperation of the driving element and the locking web of the guide rail assembly according to  FIG. 9   a  in a defined working range of the driving element. 
       
    
    
       [0049]    Identical reference numerals in the Figures indicate identical elements or element groups or those with substantially the same effect. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0050]    According to  FIG. 1 , two guide webs  4 , which together form a substantially U-shaped rail profile, protrude essentially perpendicularly from carrier plate  1  on which the guide rail is formed, said carrier plate being substantially flat and only a protruding section of which is illustrated for reasons of simplification. According to  FIG. 1 , protruding into inner space  3  of the rail profile from the insides of guide webs  4  are triangular guide protrusions  5 . Guide protrusions  5  each have a bevel  7  facing towards base  2  of the rail profile and an introductory bevel  6  facing away from base  2 . Engaging in the rail profile thus formed is a central thickened section  11  of driving element  10 . More precisely, the acute angle at which a notional extension line of bevel  7  intersects the plane defined by carrier plate  1  in the region of the guide rail corresponds to the angle at which rear bevels  15  intersect side walls  12  of central section  11 . According to  FIG. 1 , the front ends of guide webs  4  are in contact with the base of driving element  10  in such a manner that driving element  10 , due to the positive fit, is guided movably overall on the guide rail thus formed in its longitudinal direction and is secured against detachment from the rail profile in a direction perpendicular thereto, i.e. in the vehicle&#39;s transverse direction y. 
         [0051]    As will be described subsequently with reference to  FIGS. 2-4 , guide webs  4  may be bent elastically outwards, namely in the region of guide protrusions  5 , by at least a distance which corresponds to the distance by which guide protrusions  5  protrude from the inside of guide webs  4 , i.e. substantially by at least the height of the point of triangle-shaped guide protrusion  5  relative to the inside of guide web  4 . Consequently, driving element  10  may be pressed into or clipped onto the rail profile formed by guide webs  4 . For this purpose, formed on the upper front face of central thickened section  11  are two bevels  14 , which on being pressed onto driving element  10  ultimately come into contact with introductory bevels  6  and subsequently, on further pressing of driving element  10  onto the rail profile, bring about an expansion of guide webs  4  until finally central thickened section  11  slides at its widest point past pointed, triangle-shaped guide protrusions  5  and slides into inner space  3  of the rail profile. On further pushing on of driving element  10 , guide webs  4  ultimately return to the initial position shown in  FIG. 1  in which they are pre-tensioned. 
         [0052]    According to  FIG. 1 , driving element  10  also has two wing-like marginal webs  16 ,  17 , which in cross-section almost form a closed equilateral triangle with the base of driving element  10 , wherein front free ends  17  are inclined at an acute angle to the base of driving element  10  and are disposed a short distance from the outside of guide webs  4  or, according to a further embodiment (not illustrated) are permanently in contact on the outside of guide webs  4 . Webs  16 ,  17  serve as securing elements in order to additionally secure the driving element against detachment from the guide rail in the vehicle&#39;s transverse direction y. According to  FIG. 1 , inclined marginal web  17  is spaced further from base  2  of the guide rail than the widest part of central thickened section  11 . On detaching driving element  10  from the guide rail, guide webs  4  are pressed outwards due to the cooperation of rear bevels  15  with bevels  7 . This evasive movement of guide webs  4  is, however, at least obstructed or even prevented by securing webs  16 ,  17  which depends on the elastic properties of securing webs  16 ,  17  and their geometric design. It should be emphasized that additional securing webs  16 ,  17  are not absolutely necessary. 
         [0053]    In the embodiment according to  FIG. 1 , rear bevels  15  of driving element  10  engage behind guide protrusions  5  of guide webs  4 . In the embodiment illustrated, the angle at which bevels  7  are inclined towards base  2  is approximately 45 degrees. This acute angle may be varied within broad limits and may even be relatively small but should not be negligibly small so as to enable demoulding of the rail profile from the moulding tool. 
         [0054]    A method for injection moulding of the carrier plate with the guide rail according to  FIG. 1  is described below with reference to  FIGS. 2 to 4 .  FIG. 2  illustrates three adjacent moulding tool parts  30 - 32 , which together define the carrier plate in the region of the guide rail. In this case moulding tool part  32  is wedge-shaped, i.e. the marginal areas of moulding tool part  32  taper towards one another at a comparatively small acute angle. According to  FIG. 2 , formed in the marginal areas of wedge-shaped moulding tool part  32  are recesses  34 ,  35 , which define the guide protrusions and guide webs of the subsequent rail profile. Together moulding tool parts  30 - 32  form a central cavity  33 , which is limited by a male mould not illustrated, in order to thus define the shape of the carrier plate. Moulding tool parts  30 - 32  are slidable in the direction of the arrow for demoulding of the work piece, whereby regions  30 ,  31  are expediently integrally formed such that sliders  32  forms the second tool part. The third tool part is formed at the same time by the male mould not illustrated, which together with the other tool parts forms the cavity to be filled. 
         [0055]    The following procedure is followed to produce the carrier plate with the guide rail: first of all the moulding tool is formed according to  FIG. 2  and the male mould not illustrated is inserted. Injection moulding of the carrier plate with the guide rail formed integrally therein is carried out subsequently. Then both lateral moulding tool parts  30  and  31  are first withdrawn in the direction of the arrow for demoulding. This procedure is illustrated schematically in  FIG. 3 , which is a hugely inflated representation from a perspective point of view. In this state, wedge-shaped moulding tool part  32  continues to be engaged with the guide rail. 
         [0056]    In a subsequent step, as shown in  FIG. 4 , wedge-shaped moulding tool part  32  is then also lifted off in the same direction. In  FIG. 4  one can identify triangle-shaped notches  38  formed in marginal areas  37 , said notches defining guide protrusions  5  on the insides of guide webs  4 . On withdrawal of wedge-shaped moulding tool part  32 , guide webs  4  are bent elastically outwards such that the tips of guide protrusions  5  slide on marginal areas  37  until guide webs  4  finally return into the initial position illustrated in  FIG. 4  due to their elastic properties. 
         [0057]      FIG. 5  shows a second embodiment in which driving element  10  can no longer be detached from the guide rail without destroying it. To this end, driving element  10  is formed substantially in a C-shape having two marginal webs  19 , which extend perpendicularly to the base of driving element  10 . According to  FIG. 5 , protruding from the insides of marginal webs  19  are two protrusions acting as securing elements, which may be permanently in contact on the outsides of guide webs  4  but which may also be disposed at a short distance from them, said distance being smaller than the predefined distance referred to previously. According to  FIG. 5 , guide protrusions  5  have on their inside a bevel  7 , which cooperates with centrally thickened section  11  of driving element  10 . According to  FIG. 5 , securing protrusions  20  and the widest sections of centrally thickened section  11  are disposed at the same distance from base  2  of the rail profile. In order to detach driving element  10  from the rail profile in the vehicle&#39;s transverse direction y, it is necessary not only to bend guide webs  4  outwards but also marginal webs  19  at the same time. Thus it is possible to achieve a high resistance to detachment of driving element  10 . Expediently, such a driving element is assembled by threading onto one of the ends of a guide rail. 
         [0058]    As can be seen from  FIG. 5 , rear sides  18  of centrally thickened section  11  extend at a right angle to lateral surfaces  12 . Basically, however, an inclined surface may also be provided at this point as in the embodiment according to  FIG. 1 . 
         [0059]    A third embodiment is described below with reference to  FIGS. 6 and 7 . According to  FIG. 7 , triangle-shaped guide protrusions  5  protrude from the outsides of guide webs  4 . Three moulding tool parts  30 - 32 , as illustrated by way of example in  FIG. 6 , are used to produce such a rail profile. According to  FIG. 6 , the spaces, which are defined by guide webs  4  and guide protrusions  5 , are formed in the marginal areas of moulding tool part  30 ,  31 . Central moulding tool part  32  is wedge-shaped, i.e. its lateral surfaces taper towards each other at a relatively small acute angle, as described previously on the basis of  FIG. 2 . 
         [0060]    The following procedure is followed to demould such a guide rail: first of all wedge-shaped moulding tool part  32  is withdrawn in the wedge direction illustrated such that the insides of guide webs  4  are exposed. Subsequently, adjacent moulding tool parts  30 ,  31  are withdrawn in the same direction as indicated by the arrows. In the process, introductory bevels  7  of guide protrusions  5  slide off on the narrowed sections of moulding tool parts  30 ,  31  which leads to elastic bending of guide webs  4  in the inward direction. Finally, guide webs  4  return to their unstressed initial position  4  according to  FIG. 7 . 
         [0061]    To further secure driving element  10  on the rail profile, provided laterally on driving element  10  are marginal webs  19 ,  17 , whereby lateral webs  19  extend substantially perpendicular to the base of driving element  10  and securing webs  17  face towards guide protrusions  5  at an acute angle. According to  FIG. 7 , centrally thickened section  11  slides directly on the insides of guide webs  4 . To secure driving element  10  on the rail profile, a securing section  21  formed on each of the front free ends of securing webs  17  is in direct contact on the opposing surface of guide protrusion  5  facing towards base  2  of the rail profile. The surfaces may be bevelled as described previously on the basis of  FIG. 1 . In the embodiment according to  FIG. 7 , these lateral surfaces  9  are convex in shape and securing sections  21  formed correspondingly to them are concave in shape. According to  FIG. 7 , convex securing section  9  merges into the outer surface of securing web  4  at an obtuse angle, i.e. an angle greater than 90 degrees. Overall, driving element  10  is secured against detachment in the vehicle&#39;s transverse direction y by clamping on the rail profile. 
         [0062]      FIG. 8  shows a driving element for motor vehicle window lifters according to a further aspect of the following invention, which is suitable for a guide rail assembly, as described previously, but which is also basically suitable for any other rail profiles, also for those that are not made of a plastic material. The guide rail has, in the embodiment according to  FIG. 8 , two guide webs  4  spaced apart from each other, which are formed according to the first embodiment of  FIG. 1 . Basically, however, a single guide web  4 , from which, for example, two guide protrusions  5  protrude in opposing directions, is also sufficient to guide the driving element. According to  FIG. 8 , driving element  10  is comprised of two different materials, namely a body  10 , which is preferably formed out of a plastic material, particularly is injection moulded out of plastic, in which U-shaped longitudinal recesses are formed, in which U-shaped slider inserts  27  are securely accommodated, said slider inserts being comprised of a different material. This other material is particularly suitable for a particularly appropriate tribological pairing with the material of guide webs  4 , may in particular be a metal or a metal insert, also in the form of a sintered body, but may also in principle be comprised of another plastic material. According to  FIG. 8 , slider inserts  27  engage with a positive fit in the U-shaped longitudinal recesses of driving element  10 . Edges  24 ,  25  on the inside of driving element  10  engage behind edges on the top end of slider inserts  27  to secure slider inserts  27  in the longitudinal recesses. 
         [0063]    The following procedure is followed for assembly of such a guide rail assembly: first of all a guide rail is provided, for example with two guide webs  4  spaced apart from one another, as illustrated in  FIG. 8 . Then slider inserts  27  are pushed onto the front free ends of guide webs  4 . At the same time the lateral webs of U-shaped slider inserts  27  must be elastically expanded, which is possible due to the design of the inner sides of the lateral flanks and of guide protrusion  5 . Subsequently, driving element  10  in  FIG. 8  is pushed onto the guide rail from above with slider inserts  27  attached to it until the bottom ends of slider inserts  27  are in contact on edges  24 ,  25  or on the introductory bevels formed on these edges, which leads to an elastic expanding of the webs of driving element  10  which form the longitudinal recess. According to  FIG. 8 , the central section of driving element  10  has a U-shaped longitudinal cut-recess  26 , such that the inner side walls of driving element  10  can be bent elastically inwards. On further pushing on of driving element  10 , slider inserts  27  finally slide completely into the longitudinal recess of the driving element until then edges  24 ,  25  finally snap back and engage behind the front ends of slider inserts  27  in order to thus secure driving element  10  against detachment in the vehicle&#39;s transverse direction, i.e. in the vertical direction in  FIG. 8 . 
         [0064]      FIG. 9   a  shows a variation of the guide rail assembly according to  FIG. 8 . Unlike  FIG. 8 , standing up from base  2  of the module carrier is a locking web  260 , which in the working range of the driving element engages in the U-shaped longitudinal recess or cut-out  26  of driving element  10 . Sliding inserts  27  are at the same time clipped into driving element  10 , with elastic deformation or bending of securing hooks  25  limiting longitudinal recess  26 . In the working range of the driving element, locking web  260  engages in longitudinal recess  26  in such a manner that bending of securing hooks  25  towards one another on detaching driving element  10  perpendicularly from base  2  of the module carrier is prevented. This effectively prevents sliding inserts  27  from popping out of the longitudinal recesses of driving element  10  and secures driving element  10  on guide webs  4 . 
         [0065]    To be able to assemble the driving element illustrated on guide webs  4  of a carrier  1  provided with locking web  260 , said locking web  260  according to  FIG. 9   b  has a narrowed section or cut-out  261  on at least one end region. To assemble the driving element, the positive fit between driving element  10  and protrusions  5  of guide webs  4  may be created first of all by simply clipping on driving element  10  with slider inserts  27  inserted therein in the region of narrowed section  261 . On moving driving element  10  within its working range, locking web  260  then engages in recess  26  of the driving element, as described previously, such that large detachment forces acting perpendicular to the module carrier can be transferred. In addition, the width of locking web  260  corresponds in the working range or adjustment range of driving element  10  substantially to the width of longitudinal recess  26  of driving element  10 . 
         [0066]    It is possible to dispense with the narrowed section or cut-out  261  previously referred to if the geometry of the module carrier allows the driving element to be pushed on in the adjustment direction of driving element  10 . The advantage of locking web  260  is therefore, that unintentional bending upwards of securing hooks  25  and thus unbuttoning of protrusions  5  from slider insert  27  can be securely prevented. Of course, for this it is necessary for the outer regions of the driving element or the body of the driving element as such to be designed with sufficient rigidity. 
         [0067]    As will clearly be self-explanatory to the person skilled in the art on studying the preceding description, the features of the embodiments described previously may also be combined with each other in any other way than previously described. 
       LIST OF REFERENCE NUMBERS  
       [0068]      1  Carrier plate 
         [0069]      2  Base of guide rail 
         [0070]      3  Inside of guide rail 
         [0071]      4  Guide web 
         [0072]      5  Guide protrusion 
         [0073]      6  Introductory bevel 
         [0074]      7  Bevel 
         [0075]      8  Front face of guide web  4   
         [0076]      9  Rounded contact section/guiding section 
         [0077]      10  Driving element 
         [0078]      11  Central thickened section 
         [0079]      12  Narrowing 
         [0080]      13  Front face of the central thickened section  11   
         [0081]      14  Front bevel 
         [0082]      15  Rear bevel 
         [0083]      16  Inclined marginal web 
         [0084]      17  Securing web 
         [0085]      18  Edge 
         [0086]      19  Marginal web 
         [0087]      20  Securing element 
         [0088]      21  Rounded securing section 
         [0089]      22  Stiffening rib 
         [0090]      23  Bevel 
         [0091]      24  Front end 
         [0092]      25  Securing hook 
         [0093]      26  Recess 
         [0094]      260  Locking web 
         [0095]      261  Cut-out/narrowed end of locking web  260   
         [0096]      27  Sliding insert 
         [0097]      28  Inner leg 
         [0098]      29  Outer leg 
         [0099]      30  First half of moulding tool 
         [0100]      31  Second half of moulding tool 
         [0101]      32  Wedge insert of moulding tool 
         [0102]      33  Central cavity 
         [0103]      34  Cavity 
         [0104]      35  Narrowing 
         [0105]      36  Lateral surface of first half of moulding tool 
         [0106]      37  Lateral surface of wedge insert  32   
         [0107]      38  Notch

Summary:
A guide rail assembly for motor vehicle window lifters and a method for the production thereof. Two guide webs having protrusions formed thereon form a guide rail on a carrier plate made from a plastic material. The guide webs may be bent elastically inwards or outwards, enabling the driving element to be clipped on by pushing it on in the vehicle&#39;s transverse direction y and considerably simplifies production in an injection moulding process because the guide rail may be removed by elastically bending the guide rails such that a smaller number of sliders is required in the moulding tool. In one embodiment, there is also provided a driving element comprising a body of a first material and, securely held therein, sliding inserts comprised of a second material which material ensures a particularly good tribological pairing with the material of the associated guide web.