Abstract:
The invention relates to a wiper blade ( 10 ) and to a method for producing a wiper blade ( 10 ) for wiping panes, in particular motor vehicle panes, comprising a support element ( 12 ) for receiving a wiper strip ( 14 ), to which a connecting device ( 20 ) is attached, which has a wiper blade-side part ( 15 ) having claw-like receptacles ( 34, 36 ) surrounding the support element ( 12 ) at least in some regions. According to the invention, the connecting device comprises passages and/or openings which allow a weld connection or can receive melt flow.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    In wiper blades for wiping panes, comprising a support element for receiving a wiper strip, to which a connecting device is fastened, said connecting device having a part on a wiper blade side with claw-like receivers, which at least partially encompass the support element, the support element is intended to ensure a distribution which is as uniform as possible of the contact pressure of the wiper blade on the pane, originating from the wiper arm, over the entire wiping area covered by the wiper blade. By means of an appropriate curvature of the unloaded support element—i.e. when the wiper blade does not bear against the pane—the ends of the wiper strip, which is applied fully against the pane during operation of the wiper blade, are urged toward the pane by the support element which is then tensioned, even if the radii of curvature of spherically curved vehicle windshields change in every wiper blade position. The curvature of the wiper blade thus has to be somewhat greater than the greatest curvature measured in the wiping area on the pane to be wiped. A connecting device is fastened to the support element via which the connection to the wiper arm is produced. 
         [0002]    It has been disclosed in EP 0914269 B1 to fasten the connecting device to the support element by means of a weld connection. To this end, the connecting element on the wiper blade side, which consists either of metal or a plastics material, is applied or pushed onto the support element and connected by a material connection to the support element, by means of resistance welding in the case of a metal connecting element or by means of ultrasonic welding in the case of a plastics connecting element. This weld connection is subjected to extreme conditions in everyday use and has to withstand high torques and vibrations, additionally in variable weather conditions. In particular, in wiper blades produced in large quantities, the weld connection sets high requirements in terms of the quality of the process management. 
       SUMMARY OF THE INVENTION 
       [0003]    A wiper blade according to the invention has the advantage that the welding may be carried out at defined points in predefined conditions. 
         [0004]    By means of the through-passages and/or recesses, it is possible to introduce the energy in a targeted manner and to control the melt flow. As a result, it is possible to increase or even to limit the welding zone to predetermined regions so that the strength and resilience between the connecting device and the support element are able to have predetermined values. 
         [0005]    In order to control the melt flow further, it is expedient to arrange the through-passages and/or recesses opposite an upper convex face of the support element or opposite a lower concave face of the support element. It may also be expedient if the corresponding through-passages have a different size on the side opposite the through-passages on the other side and/or are arranged offset relative to one another. 
         [0006]    The invention also relates to a method for producing a wiper blade in which the energy is introduced via the through-passages according to the invention provided in the connecting device and the connecting device is connected in this manner to the support element. By means of the through-passages and/or recesses it is possible to introduce the energy in a targeted manner and to control the melt flow. As a result, it is possible to increase or even to limit the welding zone to predetermined regions so that the strength and resilience between the connecting device and the support element are able to have predetermined values. 
         [0007]    The energy may be introduced in a particularly simple manner by means of ultrasonic sonotrodes. 
         [0008]    The introduction of energy may take place in a particularly controlled manner if a plurality of sonotrodes are used, said sonotrodes introducing energy via through-passages of both the upper face and the lower face. The sonotrodes may advantageously be of variable diameter, for example the sonotrodes which protrude through the upper through-passages may be of greater diameter than those which protrude through the lower through-passages. In this manner, both the introduction of energy and the pressure to be applied by the sonotrodes onto the connecting device and/or the support element may be individually optimized. 
         [0009]    For further optimization of the melt flow, the sonotrodes are preferably placed on opposing sides on the connecting device and/or on the support element, wherein opposing sonotrodes are arranged offset relative to one another. The melt flows are thus produced at different points from one another and preferably move toward one another in each case on the side thereof facing the support element. As a result, it is possible to control the melt flow so that it does not flow excessively over the edges of the support element and/or the connecting device. 
         [0010]    If recesses are provided in the connecting device on the sides opposing the sonotrodes, here the activation of the melt flow is delayed. If the recesses are offset relative to the sonotrodes, the melt flow is still produced but limited in the direction of the recesses. 
         [0011]    The welding process may be controlled if an auxiliary body is introduced between the upper face of the support element and the connecting device. Said auxiliary body is removed again after the welding has taken place. Said auxiliary body may consist of different metals, plastics material or ceramics, depending on the extent to which the welding process is intended to be controlled. 
         [0012]    If the auxiliary body is configured as a heat sink which is thus able to absorb heat from the support element, in particular, the melt flow is restricted as a result. 
         [0013]    By introducing an auxiliary body which preferably acts on the support element, the support element may be loaded such that it is forced from its curved position in the unloaded state into an entirely or partially extended position. The support element is thus moved into an extended position as predetermined during normal operation on the vehicle windshield by the loading of the wiper arm. The weld connection is thus carried out so that in the operating position it remains more or less without tension. 
         [0014]    The invention also relates to a method for producing a wiper blade, in which the support element with an auxiliary body below the connecting device or bearing against the connecting device is preferably moved into a substantially extended position and energy is introduced to connect the connecting device to the support element, said energy connecting the connecting device to the support element by a positive and/or material connection. In this manner, only the support element is loaded whilst the connecting device is able to be accurately positioned. The auxiliary body is introduced immediately before introducing the energy and removed again after the connection is complete. During the connection process, the auxiliary body is able to absorb excess energy and thus control the connecting sequence. 
         [0015]    If the support element has a slot, the auxiliary body may be simply pushed along the support element from the outside and after the connection process pulled out again. 
         [0016]    The auxiliary body may be advantageously configured in a T-shape, wherein the width of the T-bar is slightly narrower than the width of the slot in the support element, so that the T-bar is inserted from below into the slot and is then able to be twisted until it overlaps the support element. The support element is then moved into an approximately extended position and energy introduced for fastening the connecting device. Subsequently, the support element is unloaded again and the auxiliary body twisted back and removed. 
         [0017]    If the T-limb of the auxiliary body is not round and configured so that when twisted it moves the slot to a predetermined distance and/or holds the slot at a predetermined distance, a dimensional stability may be ensured in a simple manner. It is also possible, however, to introduce a support element, which consists of two longitudinal rails, in a defined manner into receiving regions of the connecting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    In the drawings: 
           [0019]      FIG. 1  shows a wiper blade according to the invention in a perspective view with the wiper arm indicated in dashed-dotted lines and the surface of a windshield indicated in dashed-dotted lines, 
           [0020]      FIG. 2  shows a view along II-II in  FIG. 1 , 
           [0021]      FIG. 3  shows a schematic view of the view according to  FIG. 2  with only one spring rail, 
           [0022]      FIG. 4  shows a schematic view in the viewing direction IV in  FIG. 1  with only one end cap, 
           [0023]      FIG. 5  shows a sectional view of a connecting device with the sonotrodes introduced, 
           [0024]      FIG. 6  shows a sectional view of a connecting device with the sonotrodes introduced and an auxiliary body, 
           [0025]      FIGS. 7 to 11  show schematic views of the connecting device similar to  FIG. 5  with variable arrangements of sonotrodes, recesses and auxiliary bodies and  FIGS. 12 and 13  show variable auxiliary bodies. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    A wiper blade  10  shown in  FIG. 1  has a strip-like, elongated, rubber-elastic support element  12  ( FIGS. 1 and 2 ), on the lower strip side  13  thereof facing the pane, an elongated rubber-elastic wiper strip  14  being fastened parallel to the longitudinal axis. The part  15  of a connecting device on the wiper blade side is arranged on the upper strip side  11  of the support element  12 , also to be denoted as a spring rail, remote from the pane, in the central portion thereof, by means of which the wiper blade  10  is able to be releasably connected in an articulated manner to a wiper arm  16  indicated in dashed-dotted lines in  FIG. 1 . The wiper arm  16 , driven in an oscillating manner in the direction of a double arrow  18  in  FIG. 1 , is loaded in the direction of an arrow  24  relative to the pane to be wiped, for example relative to the windshield of a motor vehicle—the surface thereof in  FIG. 1  being indicated by a dashed-dotted line  22 . As the line  22  is intended to represent the greatest curvature of the pane surface, it is clearly visible that the curvature of the wiper blade which bears against the pane with both ends thereof, and is still unloaded, is greater than the maximum pane curvature ( FIG. 1 ). Under the contact pressure (arrow  24 ) the wiper blade  10  bears with its wiper lip  26  over its entire length against the pane surface  22 . In this case, in the spring-elastic support element  12  produced from metal, a tension is created which ensures correct bearing of the wiper strip  14  and/or the wiper lip  26  over the entire length thereof against the pane surface  22  and also for the uniform distribution of the contact pressure (arrow  24 ). 
         [0027]    Further details of the specific embodiment of the wiper blade according to the invention are to be provided below. 
         [0028]    In  FIG. 2  it may be seen that the support element  12  is made up of two spring strips  28  and  30  separated from one another, which are spaced apart from one another and form a gap  32 . The connecting device  15  has in a lower region two U-shaped receivers  34  and  36 , in which the spring strips  28  and  30  are received. The receivers  34  and  36  encompass the spring strips  28  and  30  in each case over a greater part of their cross section, wherein the part of the connecting device  15  corresponding to the wiper arm  16  is arranged on the convex face  29  of the support element  12 , whilst the concave face  31  opposes said convex face. 
         [0029]    In  FIG. 3 , the connecting device  15  is shown schematically, wherein the corresponding spring strip  28  is illustrated in the receiver  34  whilst the spring strip  30  is not located in the corresponding receiver  36 . It may be seen that the receivers  34  and  36  encompass the spring strips  28  and  30  with a snug fit. In the region above the spring strips  28  and  30 , and above the gap  32 , the connecting device  15  has a recess  40  into which a top part of a wiper strip comes to rest when the wiper blade  10  is assembled. 
         [0030]    The wiper blade  10  which is shown in  FIG. 4  from below and which is illustrated without the wiper strip  14  and/or the wiper lip  26 , reveals the spring strips  28  and  30 , the gap  32  as well as the receivers  34  and  36  of the connecting device  15 . In this embodiment of the wiper blade  10 , it may be seen that the spring strips  28  and  30  are entirely separate from one another and merely held together by the connecting device  15  and/or via end caps  38 , only one thereof being shown at one end in  FIG. 4 . 
         [0031]    The wiper blade  10  according to the invention is characterized in that the connecting device comprises through-passages and/or recesses which allow a weld connection or are also able to receive melt flow. In  FIG. 3 , various through-passages and recesses for introducing energy are shown, wherein it is clear that the person skilled in the art will accordingly select the respective embodiment to optimize the connection thereof and the process reliability. In the region  42 , a simple through-hole  44  is shown, through which a sonotrode is directly placed onto the spring strip and heating, originating from the support element, is able to take place. In the region  46 , a blind hole  48  is shown in which the sonotrode initially melts and penetrates a part of the material of the connecting device  15  before contact is made with the spring strip  28 . In the region  50 , a two-step through-hole is shown with a first larger blind hole  52  and a smaller through-hole  54  adjacent thereto. In the region  56 , a two-step blind hole is shown with a larger first blind hole  58  and a second smaller blind hole  60  adjacent thereto. It may be observed that the opposing through-passages and/or recesses do not have to be of the same size or of the same shape, but naturally they can be. Moreover, the through-passages and/or recesses may directly oppose one another or may be more or less offset relative to one another. Such an offset may be provided both in the transverse direction and in the longitudinal direction of an individual spring rail  28  or  30 . 
         [0032]    In  FIG. 4 , through-holes  44  which are incorporated in the receiver  36  may be seen from below. A single through-hole  62 , similar to the through-hole shown in the region  50 , is incorporated in the receiver  34 . 
         [0033]    The connection between the connecting elements  15  and the spring strips  28  and  30  of the support element  12  takes place by the addition of energy, in which generally the material of the connecting device  15  is melted and connected by a positive and/or by a material connection to the material of the support element  12 . To this end, the connecting device  15  consists at least partially of plastics material whilst the spring rails  28  and  30  of the support element  12  generally consist of spring steel encased in plastics material. It is, however, also conceivable to use spring rails  28  and  30  consisting only of metal or only of plastics material. The energy is supplied, as shown in  FIG. 5 , by means of upper sonotrodes  64  and lower sonotrodes  66 . In  FIG. 6  it is shown that the sonotrodes are also able to act merely from one side. 
         [0034]    In  FIGS. 7 to 10 , it is shown thematically that the upper sonotrodes  64  are of the same size as the lower sonotrodes  66  and oppose said sonotrodes. In  FIG. 8 , the sonotrodes  64  are larger in diameter than the sonotrodes  66 . On the left-hand side, the sonotrodes are located directly opposite one another whilst on the right-hand side the upper sonotrode  64  and the lower sonotrode  66  are arranged offset relative to one another. In  FIG. 10 , in each case only one upper and/or one lower sonotrode  64  and/or  66  is shown, wherein a recess  68  directly opposes the upper sonotrode  64 , whilst a recess  70  opposes the lower sonotrode  66  in an offset manner. Also in this case, said arrangement is only shown by way of example and it is clear to the person skilled in the art that is it possible to arrange the recesses  68  and/or  70  at the top or bottom and/or directly opposing or offset therefrom, depending on the other process parameters in order to optimize the process thereby. 
         [0035]    In the method according to the invention for producing a wiper blade  10  comprising a support element  12  for receiving a wiper strip  14 , to which a connecting device  15  is fastened, said connecting device having claw-like receivers  34 ,  36 , which at least partially encompass the support element  12 , the energy is introduced via the through-passages  44 ,  54 ,  62  or recesses such as the blind hole  48 ,  52 ,  58  or  60  and the connecting device  15  is connected to the support element  12 . 
         [0036]    The energy is preferably introduced as ultrasonic energy by means of ultrasonic sonotrodes  64 ,  68 . 
         [0037]    Preferably a plurality of sonotrodes  64 ,  68  are used. Said sonotrodes are used at the same time or staggered chronologically. Moreover, said sonotrodes are able to introduce the energy from the upper and/or the lower face. Preferably, the sonotrodes  64  of the upper face are configured to be larger than the sonotrodes  66  of the lower face. 
         [0038]    According to a further embodiment of the method according to the invention, as shown in  FIG. 11 , initially the energy is introduced by a smaller upper sonotrode  64  (left-hand side) and then the connection is completed by a larger sonotrode  64  (right-hand side). This method is naturally also implemented from the lower face. By melting the additional material, hollow spaces which are provided for tolerance reasons, for example, may be filled up. 
         [0039]    In a further embodiment of the method according to the invention, the sonotrodes on opposing sides are placed on the connecting device  15  and/or on the support element  12 , wherein the opposing sonotrodes  64 ,  66  are offset relative to one another. As visible in  FIG. 10 , recesses  68  and/or  70  are arranged in the regions opposite the sonotrodes  64  and/or  66 . The recess  68  opposes the sonotrode  64  directly so that the energy introduced by the sonotrode  64  is not able to melt the material of the receiver  36  on the directly opposing side. Instead a melt flow is produced which moves toward the recess  68 . On the right-hand side of  FIG. 10  it is shown that the recess  70  may be arranged offset to the opposing sonotrode  66 . The energy introduced by the sonotrode  66  is able to melt the material of the connecting device  15  in the opposing region, so that a melt flow is produced away from this point in the direction of the recess  70  and/or the recess  40 . 
         [0040]    As shown in  FIG. 9 , the spring strips  28  and  30  are spaced apart by an auxiliary body  72 . The auxiliary body  72  is of T-shaped configuration, wherein the T-limb  74  has a width which corresponds to the width of the gap  32  and the T-bar  76  partially overlaps the spring strips  28  and  30 . To this end, the T-bar  76  is located within the recess  40 . 
         [0041]    The auxiliary body  72  firstly acts in a stabilizing manner, by pressing the spring strips  28  and  30  into the receivers  34  and  36  and is fixed there until the welding process is complete and the plastics material has cured again. Secondly, the auxiliary body  72  acts to equalize the temperature as, acting as a heat sink, it is able to absorb excess energy which would have the effect of increasing the temperature in the spring strips  28  and  30  in the direction of the gap  32 . As a result, a potential melt flow in the direction of the gap  32 , originating from the sonotrodes  64  and  66  and the energy introduced there, is reduced and/or stopped. 
         [0042]    The method according to the invention for producing a wiper blade  10  comprising a support element  12  for receiving a wiper strip  14 , to which a connecting device  20  is fastened, said connecting device having a part  15  on the wiper blade side with claw-like receivers  34  and  36 , which at least partially encompass the support element  12 , is also characterized in that by means of the auxiliary body  72  below the connecting device  20  or adjacent to the connecting device  20 , the support element  12  is moved into a substantially extended position and energy is introduced for connecting the connecting device  20  to the support element  12 , said energy connecting the connecting device  20  to the support element  12  by a positive and/or material connection. 
         [0043]    To this end, the support element  12  has a gap  32  in which the auxiliary body  72  is pushed from outside along the support element  12  and, after the connection is made, is pulled out again. The auxiliary body  72  may naturally also be introduced into the gap  32  by the wiper blade  10  and/or the support element  12 , with the connecting device  20  already pushed on, being moved relative to the auxiliary body  72  whilst the auxiliary body  72  remains stationary. If the auxiliary body  72  is in position, together with the receivers  34  and  36  it fixes the spring strips  28  and  30  in position so that the welding process is able to take place securely. 
         [0044]    The auxiliary body  72 , as  FIG. 12  shows, may be of cuboidal shape, with a first cuboid as the T-limb  74  and a second cuboid as the T-bar  76 . The fastening in a machine is therefore carried out via the lower region of the T-limb  74 , which is either simply clamped or to this end may also comprise corresponding receivers, not shown. 
         [0045]    It is, however, also possible to create an auxiliary body  78  from oval-shaped portions, with an elliptical T-limb  80  and a similarly elliptical T-bar  82 . The width  84  of the T-bar  82  is slightly less than the width of the gap  32 , so that the auxiliary body  78  is able to be introduced from below into the gap  32 . The auxiliary body  78  is then twisted by ca. 90°, so that the T-bar  82  overlaps the spring strips  28  and  30 . The support element  12  is thus able to be pulled into an extended position. After connecting the connecting device  20  to the support element  12 , the support element  12  is unloaded again, the auxiliary body is rotated by ca. 90° and removed from the gap  32 . 
         [0046]    The T-limb  80  is also elliptical, wherein the large main axis of the ellipse has a length  86  which corresponds to the size of the gap  32 . As a result, when the auxiliary body  78  is twisted, the spring strips  28  and  30  are pressed into the receivers  34  and  36  and held until the connecting device  20  and the support element  12  are connected together. If the auxiliary body  78  is then rotated back, the spring strips  28  and  30  remain in the preset position. 
         [0047]    As visible in  FIG. 6 , the auxiliary body  78  may also be introduced from the top through the part  15  of the connecting device  20  on the wiper blade side, provided the required through-passage is present. 
         [0048]    It is clear to the person skilled in the art that the embodiments of the auxiliary bodies  72  and/or  78  may be combined with the different embodiments of the corresponding through-passages and/or recesses. In cooperation with the recesses  68  and  70  shown in the example in  FIG. 10 , by the specific removal of the heat via the auxiliary body, the melt flow may be influenced in flow velocity, flow direction and flow duration. Naturally, it is also possible to introduce heat via the auxiliary body  72  and/or  78  into the connecting zones. The correct choice of size and arrangement of the through-passages and recesses and the auxiliary body is highly dependent on the materials of the connecting device and the spring strips used. The person skilled in the art may select these by a series of tests so that the process is optimized and the quality improved thereby.