Abstract:
A wiper blade for a wiper system for wiping motor vehicle windows includes a wiper blade rubber squeegee, which has a wiping lip that faces the window, a rear part that faces away from the window, and a tilting connecting element that joins the wiping lip to the rear part. The wiper blade also includes a strip-like elastic supporting element, or at least one spring rail, which stabilizes the wiper blade rubber squeegee. The supporting element can be joined to a wiper arm which can be transversally driven with regard to the longitudinal extension of the wiper blade and which can be tensioned against the window. The wiper blade is additionally provided with a casing or covering which surrounds, at least in sections, the rear part and the supporting element or the at least one spring rail. The casing is provided with a streamlined form, surrounds the rear part, and when viewed in a direction parallel to the window and of the longitudinal extension of the wiper blade, covers the tilting connecting element. Alternately, the covering is held on the at least one spring rail.

Description:
BACKGROUND 
   The invention relates to wiper blades. 
   Wiper blades are known from DE 299 03 123 U1 which have a resilient insert with a tube-like elastomer sheath, into which a wiper rubber is inserted. With wiper blades of this type the supporting element is supposed to ensure the most even distribution possible of the contact pressure on the windshield emanating from the wiper arm over the entire area swept by the wiper blade. The supporting element is advantageously pre-curved in a suitable way to achieve the necessary even contact pressure of the wiper blade against the windshield. A supporting element of this type replaces the costly bow design with two splines located in the wiper body, such as is the practice with traditional wiper blades and is known, for example, from DE 15 053 97 A1. 
   The generic, known wiper blades do, however, have the disadvantage that their construction is costly. In addition to the supporting element, a wiper blade of this type furnishes transverse bars disposed perpendicularly to the supporting element, recesses located in the supporting element and locating grooves in the wiper rubber to receive the casing which surrounds the supporting element at least in sections. Such a construction results in an overall height which cannot be ignored and is accompanied by great disadvantages during operation. For example, the side of the wiper blade facing the air stream offers a fairly large target for the air stream striking the wiper blade. Furthermore, a substantial vacuum builds up on the back side of the wiper blade facing away from the air stream. It is true that the wiper blade constantly changes its position with respect to the oncoming air stream, generally carrying out a oscillating motion during operation, but even then one longitudinal side of the wiper blade is always facing the air stream more or less directly. Because of the air stream affecting the wiper blade, the wiper blade&#39;s contact pressure is reduced to such an extent that the wiper blade tends to lift off and flutter, rendering proper wiper performance impossible. Increasing the wiper blade&#39;s contact pressure against the glass can mitigate this problem at high speeds, but at low speeds, when the attempt of the wiper blade to lift is reduced, friction between the wiper blade and the glass is increased, resulting in undesirable noise and unacceptably high loading of the drive components and of the wiper rubber. 
   Wiper blades are known from DE 197 36 368 A1 of a type which essentially consist of a wiper body and at least one spline connected to this wiper body. These wiper blades, often described as “flat wiper blades”, have the disadvantage that the protruding splines generate extremely irritating noises, caused particularly by the air stream, and also represent a hazardous source of injuries. 
   SUMMARY 
   The invention is to demonstrate a wiper blade which, while retaining the basic advantages of a known wiper blade, has improved properties. 
   This object is achieved under the invention in the case of a wiper blade by giving an aerodynamic shape to the casing which completely surrounds the supporting element and the back part in the longitudinal extension of the wiper blade and covers the hinge when viewed parallel to the glass along the longitudinal extension of the wiper blade. 
   A wiper blade of this type has the specific advantage that it can be designed to be extremely shallow and creates only a very small target for the air stream. Since the supporting element, the back part and, in particular, the hinge are covered by the casing, a very small target is offered to the oncoming flow of air impinging on the wiper blade approximately parallel to the glass. 
   A further advantage of the invention is that because of the simple construction of the wiper blade under the invention, the wiper blade has a very low overall weight and is easily to assemble. 
   In one advantageous aspect of the invention the casing also covers the part of the wiper lip facing away from the glass. The wiper blade can thereby be made even shallower and even more favorable wiper blade air flow characteristics can be achieved. 
   In one aspect of the invention, advantageous provision can be made for the casing to have a largely elliptical cross section. Just such an elliptic cross section demonstrates relatively low aerodynamic drag. Additionally, the wiper body under the invention can be designed to be very shallow by means of an elliptical cross section. 
   In an especially preferred aspect of the invention, the casing has a surface texture at least in sections to reduce aerodynamic drag. This too helps to achieve even better wiping characteristics for the wiper blade under the invention. 
   It is specifically conceivable that the surface texturing has spherical segment-shaped dimples. Such dimples result in a favorable turbulent boundary layer on the surface of the casing based on the golf ball effect and additionally reduce the drag of the wiper blade against which the air stream is flowing. Furthermore, positive visual effects can be achieved with a surface textured in this way, appealing particularly to the person viewing the wiper blade. 
   In another aspect of the invention, the casing has a turbulence generator on the windward side. Such a turbulence generator is furnished to create a turbulent boundary layer which has positive effects on the wiping characteristics of the wiper blade from the invention. 
   In a further aspect of the invention, the wiper body with the hinge is flexibly disposed in a direction running orthogonally to the glass. As a result of such an arrangement, the wiper blade&#39;s contact pressure is distributed evenly over the wiper blade and the wiping characteristics of the wiper blade are improved. 
   In another further aspect of the invention, the back part for the flexible arrangement of the wiper lip has a membrane area. A membrane area positioned in this way suggests itself because the back part is positioned immediately above the wiper lip and the hinge. 
   What can additionally be achieved by the presence of the membrane area in the area between the hinge and the side of the back part facing away from the hinge is that the flexible motion of the wiper lip introduced via the hinge can be positively influenced. 
   In a related further aspect of the invention, it is envisioned that the membrane area is formed by cavities present in the back part. Such cavities can be realized in a simple and inexpensive way in the back part of the wiper body. 
   Advantageous provision can be made in a further aspect of the invention for the wall thickness between the cavity and the side of the back part facing the wiper strip to be roughly equal to the wall thickness of the hinge. A particularly favorable springily flexible rocking motion of the rubber lip can thereby be achieved. 
   In a particularly preferred aspect of the invention, the casing possesses intrinsic stability which stabilizes the wiper blade in its entirety and counteracts plastic deformation of the supporting element. The casing thereby assumes the retaining function for the wiper blade, together with the supporting element. Designing the intrinsic stability of the casing accordingly can specifically have a positive influence on the overall spring characteristic curve of the wiper blade. 
   In a further inventive aspect of the invention, the casing also encloses the free ends of the supporting element and of the back part. This can additionally increase the intrinsic stability of the casing, whereby the wiping characteristics of the wiper body can likewise be improved. 
   As part of the invention is it also conceivable that the casing has end caps at its free ends. Such caps, which are specifically designed to be detachable, have the advantage that the wiper rubber can be removed if necessary, or replaced. 
   One variant of the invention provides for bonding the side of the supporting element facing the back part to the side of the back part facing the supporting element. Improved torsional stiffness of the wiper blade can be achieved through such bonding. 
   In another aspect of the invention, the supporting element is a metallic spring element and the casing is a plastic element. The use of such materials has proven to be particularly advantageous. 
   Under the invention, provision can also be made for the supporting element to be coated, specifically plastic coated. The supporting element is protected particularly from environmental factors, e.g., rain water, through such a coating. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention as well as further advantageous aspects and details are described and explained in greater detail in what follows in conjunction with the embodiments shown in the drawings. 
       FIG. 1  shows a cross section through a first embodiment of a wiper blade under the invention; 
       FIG. 2  shows a perspective view of a section of the wiper blade from  FIG. 1 ; 
       FIGS. 3-6  show various possible aspects of the wiper blade in accordance with the invention, in each case simplified and in section; and 
       FIG. 7  shows a simplified top view of a spline for use in one of the wiper blades from  FIGS. 3-6 . 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a wiper blade  101  under the invention for a wiping device for wiping vehicle windows having a wiper rubber  102  which possesses a wiper lip  103  facing the glass, a back part  104  facing away from the glass and a hinge  105  which connects the wiper lip  103  to the back part  104 . In the cross section shown in  FIG. 1 , a stabilizing, strip-like, elastically flexible support element  107  is shown in addition, which is preferably bonded to the side of the back part  104  facing the supporting element  107 . The supporting element  107  and the back part  104  of the wiper rubber  102  is completely enclosed by a casing  108 . The casing  108  is aerodynamically shaped and possesses a largely elliptical form. In a view parallel to the glass directed along the longitudinal extension of the wiper blade  101 , which corresponds to a view matching arrow  109 , the hinge  105  and a part  112  of the wiper lip  103  facing away from the glass are covered by the casing  108 . 
   On the side facing away from the wiper lip  103 , the casing  108  has surface texturing, namely, spherical segment-shaped dimples  113 , which are furnished to reduce the aerodynamic drag of the wiper blade based on the so-called golf ball effect. The spherical segment-shaped dimples can be seen particularly clearly in  FIG. 2 . 
   In the inventive wiper blade  101  shown in  FIG. 1  and  FIG. 2 , the wiper lip  103  with the hinge  105  is supported flexibly in an orthogonal direction to the glass, indicated by arrow  114 . The back part  104  has a membrane area for this flexible seating, namely, a cavity  117  in the back part extending in the longitudinal direction of the wiper blade  103 . For optimal flexibility as well as to improve the pivoting characteristics of the wiper lip, provision is made for the wall thickness  118  between the cavity  117  and the side of the back part  104  facing the wiper lip  101  to be roughly the same as the wall thickness of the hinge  105 . 
   In the case of the wiper blade  101  shown in  FIGS. 1 and 2 , the supporting element  107  is advantageously a metallic spring element. The use of such a supporting element  107  has the advantage that increased torsional stiffness of the wiper blade can be achieved. 
   As can be seen particularly clearly from  FIG. 2 , the casing  108  extends over the entire length of the wiper blade  101 . Because of the wall thickness of the casing  108 , which is clearly seen in  FIG. 1 , the casing possesses good intrinsic stability, which stabilizes the wiper blade  101  in its entirety and specifically counteracts any possible plastic deformation of the supporting element  107  caused by external influences. 
   The wiper blade  101  shown in  FIGS. 1 and 2  is configured/designed extremely shallow and demonstrates very low aerodynamic drag, particularly as a result of the elliptical cross section of the wiper lip  103 , which is largely covered by the casing  108  in the direction of flow  109  of the air stream, and of the spherical segment-shaped dimples  113  on the surface of the casing  108 . Consequently, lower air flow forces are operating on the inventive wiper blade  101 , particularly at higher speeds. Lifting of the wiper blade  101  from the vehicle windshield is largely eliminated. 
   The wiper blade shown in  FIG. 3  identified generally with reference numeral  1  consists in a manner known of a wiper strip  2 , which is manufactured from a flexible rubber material, specifically for example by injection molding, pressing or extrusion, and of two flat strip-like splines  3  and  4 , each of which is made from a springy flat-strip material, for example from spring steel or spring strip steel and which like the wiper strip  2  extend over the entire length of the wiper blade  1 . 
   The cross-sectional profile of the wiper strip  2  is comprised of an upper profiled section or wiper strip body  5  and of wiper lip  7  projecting beyond the underside  6  of this wiper strip body, said lip being produced in one piece with the wiper strip body  5  via a hinge  8 , and when the wiper blade  1  is in operation presses against the vehicle glass to be cleaned. 
   M identifies a center plane in  FIG. 3 , which includes the longitudinal axis of the wiper strip  2  and lies perpendicular to the plane of the drawing in  FIG. 3 . The wiper strip  2 , its body  5 , the wiper lip  7  and the hinge  8  are configured symmetrically to this center plane M. 
   The wiper strip  2  is configured on each longitudinal side with two grooves  9  and  10  open to the longitudinal side and to the ends of the wiper strip  2 , of which groove  9  is at a greater distance from the underside  6  and groove  10  is at a lesser distance. A spline  3  or  4  is partially seated in each groove  9 , specifically along an inner longitudinal edge  3 ′ or  4 ′ of the particular spline  3  or  4 . The greater part of the width of each spline  3  or  4  projects laterally out of the particular groove  9 . In each instance the splines  3  and  4  lie with their surface sides, i.e. with their top and bottom sides, in a common plane running perpendicular to the center plane M. In the embodiment shown about two-thirds of the width of each spline  3  and  4  projects from the particular groove  9 . At least at both ends of the wiper blade  1  the splines  3  and  4  are connected to each other in a known way, for example by a connecting element, and thereby also retained to the wiper strip  2 . 
   A casing or cover  11  is disposed on the upper side of the arrangement formed by wiper strip  2  and the splines  3  and  4  facing away from the wiper lip  7 . The cross section of the cover  11  is formed by a strip-like section or body  12  which is curved convexly on its upper side facing away from wiper lip  7 , essentially symmetrical to the center plane M, around axes of curvature parallel to the longitudinal extension of wiper blade  1 . On the underside facing the wiper strip  2 , the body  12  is furnished with a concavity  13  which in the embodiment shown is configured essentially symmetrical to the center plane M and in which the two splines  3  and  4  are seated with their areas projecting from the grooves  9  together with at least an upper section  5 ′ of the wiper strip body  5 . To receive the section  5 ′, the concavity  13  has a depression  13 ′ in the center extending over the entire length of the concavity  13 , the cross section of said depression  13 ′ being matched to the trapezoidal cross section of section  5 ′ forming the upper side of the wiper strip  2 . The outwardly lying longitudinal edges  3 ″ or  4 ″ of splines  3  and  4  both engage grooves  14  or  15  which are formed on the longitudinal sides of the concavity  13  so that the cover  11  is retained via the splines  3  to the wiper blade  1 . The two splines  3  and  3  are in turn located only with one part of their width by grooves  3 ″ and  4 ″ so that one part of their width in each case extends freely between grooves  8  and  14  or  15 , respectively. 
   On the one side extending in the longitudinal direction of wiper blade  1 , the body  12  transitions into a strip-like section  16  projecting beyond the underside of the cover  11  and extending over the entire length of the cover  11 , which section, with the cover  11  installed, lies with its lower open edge  17  on a common level  18  with the upper area of the wiper lip  7  facing the hinge relative to a plane perpendicular to the center plane M. During operation, wiper blade  1  is mounted on the particular vehicle such that the longitudinal side of wiper blade  1  furnished with section  16  forms the leading longitudinal side of the wiper blade in the direction of travel. Section  16  forms a forward-mounted spoiler, specifically with an outwardly located spoiler surface  16 ′ facing away from the wiper strip  2 , which surface seen as a whole with one plane perpendicular to the center plane M includes an angle of less than 90° which opens toward wiper strip  2  and which is convexly curved around axes parallel to the longitudinal axis of the wiper blade. 
   On the other longitudinal side, i.e. in the area of the groove  15 , the cover  11  forms a bulbous edge  19 . 
   Cover  11  is manufactured from a suitable elastic material, for example, from elastomeric plastic, also for example, by extruding a suitable profile. The possibility also exists in principle of then producing cover  11  in an injection molding process or by pressing, when it is then possible to shape concavity  13  in such a way that it is also closed laterally at the two ends of cover  11 , for example, with an edge corresponding to edge  19 , so that wiper strip  2  and splines  3  and  4 , or the means connecting these splines at the wiper blade ends respectively, are also covered on their end faces by cover  11 . Naturally it is understood that the length of the cover  11  is in any case selected such that it covers the wiper blade  2  and the splines  3  and  4  over the entire length, as well as the connecting elements furnished at the ends of the wiper blade for the splines  3  and  4 . 
   The advantages of the cover  11  include the following:
         risk of injury from the splines protruding laterally beyond the wiper strip  2  is prevented;   an aerodynamically optimal outer contour is achieved for the wiper blade by the cover  11 , so that annoying noise generated by the air stream at high speeds is prevented, while retaining good wiping quality;   it is furthermore possible by using the cover  11  to configure the splines  3  and  4  to have great width in comparison to wiper strip  2 , or conversely the keep the wiper strip  2  narrow and compact, where the cross section of splines  3  and  4  can be selected in each instance such that an optimal contact of wiper blade  1  against the vehicle window and thus optimal wiping quality is achieved.       

   A further advantage of wiper blade  1  lies in the fact that, through the form of the cover  11 , specifically through the forward-mounted spoiler formed by section  16 , especially low drag is achieved and air is prevented from passing under the wiper blade, with the associated deterioration in wiping quality. 
     FIG. 4  shows a wiper blade  1   a  as a further possible aspect which consists of wiper strip  2   a  corresponding to wiper strip  2  having the wiper strip body  5   a  and the wiping lip  7  formed on via the hinge  8 , and of the two splines  3  and  4  and of the cover  11   a.  Wiper blade  1   a  differs initially from wiper blade  1  in that the wiper strip body  5   a  has only a groove  9  on each long side, and the grooves  9 , as well as the grooves  14  and  15  on the sides of concavity  13   a  corresponding to concavity  13 , are selected in their depth so that the splines  3  and  4  are each accommodated over their entire width by a groove  9  and the adjacent groove  14  or  15 , respectively. Furthermore, the concavity  13   a  is adapted to the cross section of the wiper strip body  5   a  such that the later completely fills the concavity  13   a,  or is essentially accommodated completely by the concavity  13   a.    
   In the case of wiper blade  1   a,  the cover  11   a  is configured flat on its upper side and slightly rounded to the adjacent long sides, where the cover  11   a  on the forward long side of the wiper blade  1   a  facing the direction of travel when in operation in turn forms the strip-like projection  16  with the open edge  17  projecting beyond the underside of the cover. 
     FIG. 5  shows as a further aspect a wiper blade  1   b  which is very similar to wiper blade  1   a  and consists of the wiper strip  2   b  and the wiper lip  7  formed on via the hinge, of the two splines  3  and  4  and the cover  11   b.  In the case of this aspect, the wiper strip body  5   b,  which is rectangular in cross section, is completely accommodated in the concavity  13   b  of the cover  11   b,  said concavity being adapted to this cross section. The cover  11   b,  or its body  12   b,  respectively, have a tear drop-shaped cross-sectional profile, i.e., a cross-sectional profile which is similar to the cross section of half a water drop. The outer surface or outer contour of the cover  11   b  is configured asymmetrically to the center plane M, in particular around axes of curvature running parallel to the longitudinal extension of wiper blade  1   b,  such that the radius of the curvature is small at the left edge in  FIG. 5  and starting from this left edge increases to the right long side. The design is furthermore carried out such that the height-to-width ratio is in the range between 1:8 and 1:4, where B is the maximum width of the cover  11   b  in the axial direction perpendicular to the center plane M, and II is the maximum height, or the maximum distance respectively between the plane of the undersides of the splines  3  and  4  and the upper side of the cover  11   b.  The splines  3  and  4  in turn lie with their surface sides in common planes perpendicular to center plane M. 
   As  FIG. 5  also shows, the cover  11   b  terminates flush with the underside of the wiper strip  2   b  in the area of the right long side in this figure, i.e. in the area of spline  4 , while on the opposite long side, i.e. in the area of spline  3 , the cover  11   b  forms a section  16   b  projecting beyond the underside  6   b  and extending over the entire length of cover  11   b.  This section turn in turn lies with its lower open edge—with reference to a plane perpendicular to the center plane M—on the same level as the upper area of the wiper lip  7  and augments the tear-drop shape of the cover  11   b  on this long side. In operation, section  16   b  is at the forward long side of the wiper blade facing the direction of travel. 
   Wiper blade  1   b  has the advantage of especially low drag resulting from the described shape of the cover  1   b,  where wind noise is also greatly reduced. To further reduce wind noise, the surface around which air flows can also be furnished with small additional elevations, for example on the magnitude of 0.1-2 mm. 
     FIG. 6  shows as a further possible aspect a wiper blade  1   c  which differs essentially from wiper blade  1   b  only in that in place of the cover  11   b  with the tear-drop contour a cover  11   c  is provided whose body  12   c  is configured as a spoiler having a spoiler surface  20 . As is shown in  FIG. 6  by broken lines, the possibility exists of furnishing the cover  11   c  with the downwardly protruding section  16  on the long side where the spoiler surface  20  has the least distance from the vehicle window to be cleaned and forms the forward long side of the wiper blade with reference to the direction of travel. 
   Through the spoiler-like configuration of cover  11   c  the drag of wiper blade  1   c  is somewhat increased, but this shape for cover  11   c  has the advantage that the high-speed characteristics of wiper strip  1   c  are substantially improved. 
     FIG. 7  shows in simplified form and in plan view a spline  21  which is formed from a length of a springy flat material, namely for example of spring strip steel, and is furnished in a suitable way, for example by stamping, with a slot  22  which is closed at both ends of the spline  21 . At one end of the spline the slot  22  is enlarged to form an insertion opening  23 . 
   The width of the slot  22  (outside of the insertion opening) corresponds to the distance between the inside long edges  3 ′ and  4 ′ of splines  3  and  4  in  FIGS. 3-6 . In the area of the insertion opening  23 , in a direction perpendicular to its longitudinal extension, slot  22  has a width which is roughly equal to the width of the particular wiper strip  2 - 2   c,  so that the particular wiper strip can be attached to the spline  21  by being threaded through the opening  23  in such a way that the sections  21 ′ of the spline  21  provided on both sides of the slot can engage grooves  9  and  14 , as described in what preceded for splines  3  and  4 , respectively. 
   The spline  21  can be used for wiper blades  1 - 1   c  in place of individual splines  3  and  4 . In principle, spline  21  can also be used with other wiper blades which consist of a wiper strip and two splines engaging in lateral grooves of the wiper strip. 
   All the features presented in the description, the subsequent claims and the drawing can be fundamental to the invention both individually as well as in any given combination with each other.