Patent Publication Number: US-6904639-B2

Title: Wiper blade for cleaning vehicle panes

Description:
BACKGROUND OF THE INVENTION 
   In known wiper blades, the purpose of the support element is to assure as uniform as possible a distribution of the wiper blade pressure against the window, which pressure is exerted by the wiper arm, over the entire wiping field wiped by the wiper blade. Through an appropriate curvature of the unloaded support element—i.e. when the wiper blade is not resting against the window—the ends of the wiper strip, which is placed completely against the window during operation of the wiper blade, are loaded toward the window by the support element, which is stretched in this state, even though the curvature radii of spherically curved vehicle windows change with each wiper blade position. The curvature of the wiper blade must therefore be somewhat sharper than the sharpest curvature measured within the wiping field on the window to be wiped. The support element consequently replaces the expensive support bracket structure with two spring strips disposed in the wiper strip, as is the practice in conventional wiper blades (DE-OS 15 05 357). 
   In a known wiper blade of the type known in the prior art (DE-OS 198 14 609). the support element ha two spring strips, which rest in receiving grooves disposed in the two longitudinal sides of a rubber-elastic wiper strip. This wiper strip has a top strip, which is essentially rectangular in cross section, with receiving grooves for the spring strips of the support element (FIG. 13), and has a strip-shaped wiper lip, which performs the wiping function on the window. The top strip and the wiper lip are of one piece and are connected to each other by means of an intermediary strip so that opposing walls of the top strip and the wiper lip are spaced apart from each other and constitute supports for the wiper lip, which is always disposed in a so-called drag position during the reciprocating wiper motion. In practice, it has turned out that under certain conditions, the flow conditions in front of the window reduce the pressure of the wiper blade against the window. A reduction of the wiper blade height in order to minimize this disadvantage can be achieved—as demonstrated by the known wiper blade shown in FIG. 12—by embodying the support element as a one-piece spring strip and attaching it, for example gluing it, to the top side of the top strip remote from the wiper lip. A glued connection of this kind can only adapt insufficiently to the harsh operating and environmental conditions—such as alternating stress, cold, heat, ozone influence, etc.,—for the wiper blade. 
   SUMMARY OF THE INVENTION 
   In the wiper blade according to the invention, the two spring strips are respectively disposed in one of the two existing groove-like constrictions of the wiper strip so that special receiving grooves are no longer required in the top strip of the wiper strip. This reduces the height of the wiper blade without requiring a problematic glued connection between the support element and the wiper strip. Because the width of the construction groove in a partial region is greater than the thickness of the spring strips, the wiper lip can always tilt into the required drag position during wiper operation. 
   In this connection, it is particularly advantageous if the lateral defining surfaces of the groove-like constrictions diverge from the intermediary strip to the longitudinal sides of the wiper strip. With a corresponding matching, the spring strips can thus guide the wiper strip on the intermediary strip and simultaneously allow the wiper lip to execute its required tilting motion into the drag position. 
   A modification of the invention provides that one of the lateral defining surfaces of the groove-like constriction has a spherical course, viewed in cross section. This permits a favorable and quiet rolling motion of this side wall against the band surface of the relevant spring strip oriented toward it. 
   This advantage can be further improved if both lateral defining surfaces of the groove-like constrictions have a spherical course, viewed in cross section. 
   According to one embodiment of the invention, the wiper lip has a completely enclosed longitudinal conduit in order to encourage an optimal contact of the wiper strip against the preferably spherically curved window to be wiped. 
   If in addition, an air gap remains between the opposing longitudinal edges of the spring strips and the longitudinal sides of the intermediary strip adjacent to them, this produces a tension-free guidance of the wiper strip and thereby a quiet, effective wiper operation. 
   So that it is no longer necessary to carry out particular steps to fasten a connecting device for a wiper arm that moves the wiper blade, each of the two spring strips, at least with a central edge strip, protrudes from its groove-like constriction so that the connecting device can be fastened to the free edge strips. 
   Embodying the two spring strips as separate components can result in manufacturing advantages. 
   The wiper blade can be assembled with the support element in a particularly simple manner if the two spring strips are connected by means of at least two crosspieces disposed at their end sections and each crosspiece has a middle section, which extends spaced apart from the upper band surface of the spring strips, producing bridge-like a crosspieces, where the distance between the two longitudinal spring strips is less than the bridge width. 
   Advantages in the manufacture of the wiper blade are achieved if the crosspieces are embodied as separate components and are connected to the spring strips. 
   For the connection between the spring strips and the crosspieces, it is suitable if the crosspieces are fastened to the upper band surfaces of the two spring strips. 
   So that the wiper blade and/or its wiper strip can easily adapt to the respective window curvature during wiper operation, it has turned out to be advantageous if the length of the spring strips is greater than the length of the wiper strip, because then, through appropriate embodiments, a certain, advantageous longitudinal mobility of the wiper strip in relation to the support element can be assured. 
   A stable, low-torsion support element is produced if at least one crosspiece is disposed at each end section of the two associated spring strips. Depending on the length of the wiper blade, however, it is also quite conceivable to connect the two spring strips to each other by means of additional bridge-like crosspieces. In short wiper blades, it has turn out that placing a single crosspiece at each end section of the support element is sufficient to achieve a stable, torsion-free wiper blade. 
   An additional stabilization of the support element is achieved if a crosspiece disposed in the central region of the two associated spring strips is embodied as part of a connecting device for connecting the wiper blade to the wiper arm. 
   In a modification of the invention, at least one of the two crosspieces, which is respectively disposed at one of the end sections of the spring strips, has a stop, which is connected to its middle section and partially covers the end of the wiper strip adjacent to it. This prevents the wiper strip from creeping out of the support element in the longitudinal direction of the wiper blade. When a crosspiece, which is provided with a stop, is respectively disposed at each of the two ends of the support element, the distance between the two stops is greater than the length of the wiper strip in order to assure a favorable adaptation of the wiper strip to the respective window curvature. 
   In order to reduce the danger of injury when manipulating the wiper, each crosspiece disposed at the end sections of the two spring strips is provided with a covering cap that is preferably made of plastic. 
   Other advantages during the wiping operation of the wiper according to the invention ensue from the fact that the thickness of a wall or intermediary strip between the two longitudinal grooves in the wiper strip is less than the distance between the adjacent longitudinal edges of the two associated spring strips. The longitudinal play of the wiper strip in the support element consequently produces a “free-floating”, tension-free wiper strip, which can continuously adapt to the window profile during wiper operation without being impaired by a clamped connection. 
   Other advantageous improvements and updates of the invention are disclosed in the following description of exemplary embodiments shown in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a wiper blade according to the invention, 
       FIG. 2  is a prolate depiction of the wiper blade from  FIG. 1 , in a perspective representation not drawn to scale, 
       FIG. 3  shows a foreshortened support element associated with the wiper blade according to the invention, in an enlarged, prolate, perspective depiction, 
       FIG. 4  shows an enlargement of the sectional plane of a section along the line IV—IV in  FIG. 2 , 
       FIG. 5  shows an enlargement of a detail labeled V in  FIG. 2 , 
       FIG. 6  shows the sectional plane of a section according to FIG.  4  through another embodiment of the wiper blade according to the invention, 
       FIG. 7  shows the wiper blade from  FIG. 6  in a detail that corresponds to  FIG. 5 , 
       FIG. 8  shows the sectional plane of a section according to  FIGS. 4 and 6  through another embodiment of the wiper blade according to the invention, 
       FIG. 9  is a schematic representation of the sectional plane of a section along the line IX—IX in  FIG. 2 through a  wiper blade according to the invention, in an enlarged depiction, in which the wiper blade is placed against the window surface to be wiped, 
       FIG. 10  shows the wiper blade from  FIG. 9  during wiper operation in one wiping direction, and 
       FIG. 11  shows the wiper blade from  FIG. 9  during wiper operation in the other wiping direction. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A wiper blade  10  indicated in  FIGS. 1 and 2  has a band-like, elongated, spring-elastic support element  12 , against whose underside  13  an elongated, rubber-elastic wiper strip  14  is disposed in a longitudinally parallel fashion. On the top side  11  of the support element  14 , which is also referred to as a spring bar, the center section of this part is provided with the wiper blade part  16  of a connecting device, with the aid of which the wiper blade  10  can be detachably connected in an articulating fashion to a driven wiper arm  18  indicated with a dot-and-dash line in FIG.  1 . To that end, the free end of the wiper arm  18  is provided with the wiper arm part of the connecting device. The wiper arm  18  is loaded in the direction of the arrow  20  toward the window to be wiped, for example the windshield of a motor vehicle, whose surface to be wiped is indicated with a dot-and-dash line  22  in FIG.  1 . Since the line  22  is intended to represent the sharpest curvature of the window surface, it is clear that the curvature of the wiper blade  10 , which is resting with both of its as yet un-stressed ends against the window, is sharper than the maximal window curvature (FIG.  1 ). Due to the pressure (arrow  20 ), the wiper blade  10  places its wiper lip  24  over its entire length against the window surface  22 . This causes a stress to be built up in the spring-elastic support element  12 , which is made of metal for example, which stress produces a uniform contact of the wiper strip  14  and the wiper lip  24  over its entire length against the window and produces a uniform distribution of the pressure. 
   A first embodiment of the wiper blade will be explained in detail below in conjunction with  FIGS. 3  to  5 .  FIG. 4  shows that the support element  12  of the wiper blade  10  is spaced a distance  26  apart from the window  22  to be wiped. Its position is designed so that its band surfaces  11  and  13  are disposed in a plane extending essentially parallel to the window surface  22  to be wiped. The particularly advantageous design of the support element  12  is shown particularly in  FIGS. 3 and 4 . It has two band-like spring strips  28  and  30  disposed in a common plane, which are aligned parallel to each other. The inner longitudinal edges  32  are spaced a distance  34  apart from each other. The spring strips  28 ,  30  are connected to each other at each of the two ends by means of a bridge-like crosspiece  36  and  38 , for example by means of welds. In this instance, each bridge-like crosspiece rests with its end sections  40  against the top side  11  of the support element  12  or its spring strips  28 ,  30 . Each of the two lateral strips  36  and  28  has a middle section  42  which is spaced a distance  44  apart from the upper band surface  11  of the spring strips, thereby forming the basis of its bridge-like design. Since the longitudinal span  46  of the middle sections  42  is greater than the distance  34  between the opposing inner longitudinal edges  32 , the two spring strips  28  and  30  extend with inner edge strips  48  into the region of the middle sections  42 , where the edge strips  48  are disposed a distance  44  underneath the middle sections  42 . In addition to the above-mentioned purposes of the support element  12  with regard to pressure distribution, it should also assure a regulation-compliant, tension-free guidance of the wiper strip  14  during wiper operation. This also assures a quite wiper operation. 
   The wiper strip  14  of this first embodiment has a cross section, which will be clarified in conjunction with FIG.  4 . It has a top strip  50  that is connected to the wiper lip  24 , which performs the actual wiping function, by means of a narrow intermediary strip  52 . The disposition of the intermediary strip  52  permits the wiper lip  24  to tilt into a drag position that encourages the wiping function, which will be explained later. On its opposing longitudinal sides, the top strip  50  is provided with longitudinal grooves  54  and  56  that are open at the edges oriented toward these longitudinal sides. The longitudinal grooves  54  and  56  serve to contain the inner edge strips  48  of the spring strips  28  and  30 . The depth of the longitudinal grooves  54  and  56  is selected so that a wall  58  remains between the two longitudinal grooves. The top strip  50  consequently has a main strip  60  and a covering strip  62 , which are connected to each other by means of the wall  58 . The thickness  64  of the wall  58  is less than the distance  34  between the inner longitudinal edges  32  of the spring strips  28 ,  30 , i.e. less than the distance between their inner edge strips  48 . The width of the two longitudinal grooves  54  and  56  in the top strip  50  is matched to the thickness of the spring strips  28 ,  30  and/or their inner edge strips  48  so that a tension-free securing of the wiper strip to the support element  12  is assured when the wiper strip according to  FIG. 4  is put together with the support element  12  according to FIG.  3 . Since the width  66  of the covering strip  62  is somewhat less than the longitudinal span  46  of the middle section  42 , also referred to as the bridge width, and its thickness  67  is less than the distance  44  between the middle section  42  and the top sides  11  of the spring strips  28 ,  30 , wiper strip  14 , which has a uniform cross section over its entire longitudinal span, can easily be inserted longitudinally into the support element  12  and thus connected to it. 
     FIG. 5  shows another exceptional feature of the wiper blade according to the invention. This figure shows that on its side oriented toward the wiper blade end, in its middle section, the crosspiece  70  disposed at one end of the support element is provided with a stop  74 , which is connected to it and which at least partially covers the end face  72  adjacent to it. The stop  74  is constituted by a tab-like projection from the middle section  42 , which projection is bent at right angles. If each of the two wiper blade ends or each of the two support element ends is provided with a crosspiece  70  according to  FIG. 5 , care must be taken that the distance between the opposing inner wills  75  of the stop tabs  74  is slightly greater than the length  76  of the wiper strip  14  (FIG.  2 ). This can also be achieved, for example, by the length  78  of the support element  12  being slightly greater than the length  76  of the wiper strip  14 . The placement of the stops  74  at both ends thus constitutes an effective securing means for preventing the wiper strip  14  from creeping in the longitudinal direction out of its support element  12  during wiper operation. Naturally, in such a case, at least one of the two stop tabs  74  is bent at right angles is executed only after the wiper strip  14  is inserted into the support element  12 . 
   The wiper arm part  16  of the connecting device disposed in the middle section of the wiper blade  10  engages around the outer edge strips  80  of the spring strips  28 ,  30  or the support element  12  protruding from the longitudinal grooves  54  and  56 . The connection between the part  16  and the support element  12  can be produced by means of positive or frictional engagement. With a corresponding length of the wiper blade, it can also be useful to provide additional corresponding crosspieces between the two crosspieces  36  and  38  disposed at the ends. In order to prevent injury when the wiper blade is being manipulated, particularly by the end user, a covering cap  82  that is preferably made of plastic is disposed on the two spring strips  28 ,  30  or the crosspieces  36 ,  38  at the end, preferably connected to them in detent fashion (FIGS.  1  and  2 ). 
     FIGS. 6  to  8  show additional embodiments of the wiper blade according to the invention. 
   The support elements of these embodiments fully correspond to the support elements  12  from  FIGS. 3  to  5  explained above so that the reference numerals used for them in these figures can be adopted directly. The embodiment of the wiper strip  100  in this embodiment, though, differs fundamentally from the design of the wiper strip  14  in the embodiment described above. As  FIG. 6  in particular shows, the wiper strip  100  has only one wiper lip  101 , which is of one piece with a covering strip  104  and is connected to it by means of an intermediary strip  102 . The main strip  60  in the exemplary embodiment described above in conjunction with  FIGS. 4 and 5  is consequently eliminated. The inner edge strips  48  of the spring strips  28  and  30  rest in groove-like constrictions  106  of the wiper strip  100 , which are required to produce the narrow intermediary strip  102 . Consequently, the lateral defining surface  108  of the constriction  106  embodied on the covering strip  104  is oriented toward the upper band surface  11  of the support element  12 . The other lateral defining surface  110  of the groove-like constriction  106  is consequently disposed directly opposite from the lower band surface  13  of the support element  12 . It is consequently clear that each of the two inner longitudinal edges  32  of the two spring strips  28 ,  30  or of the support element  12  is disposed in one of the two groove-like constrictions  106  of the wiper strip  100 . In addition,  FIG. 6  particularly shows that the two lateral defining surfaces  110  of the constrictions  106  are embodied spherically and are disposed so that the width dimension of the groove-like constrictions  106  is wider than the thickness of the spring strips  28 ,  30 , at least over an outer partial region. It is therefore possible for the wiper lip  101  to tilt over into the desired, advantageous drag position during wiper operation. In this embodiment of the wiper blade according to the invention as well, the width  112  of the intermediary strip  102  is matched to the distance  34  between the opposing inner longitudinal edges  32  of the spring strips  28 ,  30  in such a way that an air gap remains between the intermediary strip and the spring strips. Here, too, the thickness  114  of the covering strip  104  is also slightly less than the distance  44  between the middle section  42  of the crosspiece  36  and the inner edge strip  48 . Also, the width  116  of the covering strip  104  is slightly less than the longitudinal span  46  of the middle section  42  of the bridge-like crosspieces  36 . As a result, it is possible to insert the wiper strip  100 , which has a uniform cross section over its entire length, without trouble into the support element  12  over its longitudinal span so that the installation position shown in  FIG. 6  is achieved. 
   In this embodiment as well, the plane in which the support element  12  extends is spaced the distance  26  apart from the surface  22  of the window  22  to be wiped. 
   As described above in conjunction with  FIG. 5 , in this embodiment of the wiper blade according to the invention as well, each of the two bridge-like crosspieces  70 , at their outer ends in the longitudinal span of the wiper blade, can be provided with a stop  74 , which is bent at right angles so that after the wiper strip  14  is inserted into the support element  12  and the stop tabs  74  are bent at right angles, the wiper strip  100  is assured of being longitudinally secured in the support element  12 . It is clear that in this embodiment as well, the distance between the opposing inner walls  75  of the stop tabs  74  must be slightly greater than the length  76  of the wiper strip. 
   Another embodiment of the wiper blade according to the invention will be explained in conjunction with FIG.  8 . The embodiment according to  FIG. 8  corresponds in its basic design to the design of the embodiment described in conjunction with FIG.  6 . In contrast to the embodiment according to  FIG. 6 , though, in this embodiment, not only the lateral defining surfaces  110  of the groove-like constrictions  106 , but also the other lateral defining surfaces  108  embodied on the covering strip  104  are embodied spherically. The embodiment according to  FIG. 8  also differs from the embodiment according to  FIG. 6  by means of a continuous, completely closed longitudinal conduit  118  disposed in the wiper lip  101 . The disposition of the longitudinal conduit  118  in the wiper lip can be used by itself or in connection with additional longitudinal grooves, for a smooth, quiet tilting behavior of the wiper lip during wiper operation. In addition, its disposition is not absolutely required in connection with the spherical embodiment of the defining surfaces  108 ,  110 . 
   As is clear from  FIGS. 2 and 3 , the width of the support element  12  is the same over its entire longitudinal span. However, it is also conceivable for the support element to taper toward the end sections of the wiper blade. In order for the part  16  to be fastened to the wiper blade, it is sufficient if each spring strip  28 ,  30 , at least with a central, outer edge strip  80 , protrudes from its groove-like constriction so that the part  16  of the connecting device can be fastened to this edge strip  80 . Instead of a support element  12  according to  FIG. 3 , it is also conceivable for the two spring strips to be embodied as separate components and to be disposed in the groove-like constrictions of the wiper strip. The securing, in particular of the distance  34 , can then be performed by other components that are not shown in detail. 
     FIGS. 9  to  11  show schematic sectional depictions of the wiper blade according to  FIGS. 6 and 7 , cut along the line IX—IX in  FIG. 2 ; in  FIG. 9 , the wiper blade  10  is merely placed with its wiper lip  101  against the window surface  22  to be wiped. The wiper strip  100  is secured with play between the inner longitudinal edges  32  of the two spring strips  28 ,  30  (also see FIGS.  3  and  4 ). Since the length  76  of the wiper strip  100  is also slightly less than the length  78  of the support element  12  or is slightly less than the distance between the opposing inner walls  75  of the stops  7  at the two ends of the support element  12 , this produces a so-called “free-floating”, tension-free, but operationally reliable securing of the wiper strip  100  in the support element  12 . 
   If during wiper operation, the wiper blade  10 , loaded by the pressure (arrow  20  in FIG.  1 ), is then moved across the window  22  in the direction of the arrow  122  in  FIG. 10 , then the wiper lip  101  tilts in the vicinity of the intermediary strip  102  into an advantageous drag position in which the support element  12  comes slightly closer to the window (arrow  123 ). The tilting motion is limited by the fact that a lateral defining surface  110  of the one groove-like constriction  106  is supported against the underside  13  of the one spring strip  30 . When the wiper blade  10  has reached its reversal position and is moved by the wiper arm  18  in the opposite direction (arrow  124  in FIG.  11 ), the wiper lip  101  tilts through an intermediary position shown in  FIG. 9 , into its other drag position (FIG.  11 ), in which the wiper lip  101  is supported with the lateral defining surface  110  of the other groove-like constriction  106  against the underside  13  of the other spring strip  28 . 
   When the drag positions of the wiper lip  101 , close to their reversal positions—due to the usually spherical curvature of the windshield  22 —approaches the window, the spherically embodied defining surfaces  110  roll silently against the undersides  13  of the spring strips  28 ,  30 . Correspondingly, the other spherical defining surfaces  108  of the groove-like constrictions  106  can, if necessary, also roll against the top sides  11  of the spring strips  28  and  30 .