Abstract:
A connecting piece for connecting a wiper arm to a wiper blade is proposed, which includes yielding regions, so that wiper arms of the most various sizes can be received.

Description:
BACKGROUND OF THE INVENTION 
     The invention is based on a connecting piece for connecting a wiper blade and a wiper arm. 
     Connecting pieces for connecting the wiper arm to the wiper blade are already known, for instance from European Patent Disclosure EP 0 863 058 A2, but the connecting piece shown there is embodied in multiple parts, so that different adapter parts have to be used for each of the differently sized wiper arms. 
     SUMMARY OF THE INVENTION 
     The connecting piece of the invention has the advantage over the prior art that because it has elastic regions it has an auto-adaptive nature and thus is usable for many wiper arms of different sizes. It can moreover be produced in one piece, for instance by a injection molding process, which is a substantial advantage upon installation since there is not need first to determine which adapter piece fits the particular end of a wiper arm. This is of particular importance especially because as a rule the installation is done by the vehicle. driver himself, that is, by a layman rather than a professional. 
     It is especially advantageous if the elastic regions are formed in the form of resilient tabs, since then the connecting piece can be installed without being destroyed on the wiper arm end. Because the resilient tabs have a plurality of stop faces which correspond to differently sized wiper arm ends and which upon installation each automatically move into the correct position, the result is an auto-adaptive characteristic, which makes mistake-free installation substantially easier. 
     If one region is embodied as a yielding plateau, high torsional stability is obtained, combined with a high dimensional tolerance. 
     If the yielding nature of the plateau is due to ribs that have an angle of less than 90° from the wiper arm, then when the connecting piece is removed from the wiper arm a self-locking effect is brought about, which further enhances the strength of the connection between the wiper arm and the wiper blade. 
     If the connecting piece is provided with a resilient region for multiple positions that are associated with variously sized wiper arm ends, then it proves to be especially advantageous if in the resilient region, in each of these positions, a bracing action is exerted on the wiper arm by stabilizing elements. 
     Because for locking the connecting piece to the wiper blade the body or the means for receiving and bracing the wiper blade have elastic projections on which there are protuberances perpendicular to the direction of the wiper arm end, the force for attaching the connecting piece to the wiper arm and removing it from it can be adjusted easily and precisely by means of the size of the protuberances. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described below in terms of an exemplary embodiment in conjunction with the drawings. 
     Shown are: 
     FIG. 1, a connecting piece according to the invention in the installed position, in a schematic illustration; 
     FIG. 1 a , a detail of a wiper blade with a fastening element and a wiper arm end, in a perspective view; 
     FIGS. 2 and 3, a connecting piece of the invention in a perspective view; 
     FIG. 4, a side view of a connecting piece of the invention; 
     FIG. 5, a section through a connecting piece of the invention; 
     FIG. 6, a view from below of a connecting piece of the invention; 
     FIG. 7, a side view of a connecting piece of the invention, mounted on a narrow wiper arm end with a small bending radius; and 
     FIG. 8, a plan view on a connecting piece of the invention with a narrow wiper arm end. 
     FIG. 9, a section through a connecting piece of the invention with a narrow wiper arm end; 
     FIG. 10, a side view of a connecting piece of the invention, mounted on a wide wiper arm end with a small bending radius; 
     FIG. 11, a plan view on a connecting piece of the invention with a wide wiper arm end. 
     FIG. 12, a side view of a connecting piece of the invention on a wiper arm end with a large bending radius; 
     FIG. 13, a section through a connecting piece of the invention with a wide wiper arm end and a large bending radius; 
     FIG. 14, a section through part of a connecting piece of the invention, in a variant; and 
     FIG. 15 is a side view of the wiper blade with a limited angle of rotation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1, a connecting piece  10  with a wiper arm  11  and a wiper blade  11   a  can be seen. The wiper arm  11  has two ends; its lower end is connected to a wiper motor  12 , and its upper end is bent 180° in hooklike fashion. The wiper blade  11   a  is braced on a windshield lib. 
     In FIG. 1 a , the upper end of the wiper arm  11  and a detail of the wiper blade  11   a  are shown. The end of the wiper arm  11  having the thickness D and the width B has a hooklike 180° bend of radius R. The bent portion has the length L. The wiper blade  11   a  has a cylindrical shaft  60 , extending transversely to the longitudinal axis of the wiper blade, and with this cylindrical shaft, the wiper blade is supported rotatably on the wiper arm  11 . 
     In FIGS. 2 and 3, an exemplary embodiment of the connecting piece  10  of the invention is shown in more detail. It substantially comprises a hollow body with two side walls  13 , which laterally define three transverse walls, that is, an upper, a middle and a lower face  14   a ,  14   b ,  14   c . At the top and bottom, the walls  13  protrude past the three transverse walls or faces  14   a ,  14   b  and  14   c , and the wiper blade  11   a  in the installed position is braced on the outer faces of the walls  13  (FIGS.  7  and  9 ). 
     In the installed position on the wiper arm  11 , the connecting piece  10  has a front end  16 , remote from the wiper motor  12 , in the direction of which the walls  13  taper. The connecting piece  10  also has a rear end  18 , toward the wiper motor  12 , and an underside  20  toward the windshield  11   b  and a top side  22  remote from the windshield  11   b.    
     On its underside  20 , the connecting piece  10  has a continuous transverse groove  28 , which extends over the width of the connecting piece. The transverse groove  28  forms keyhole-shaped recesses  28  in the walls  13 , and each of these recesses merges with a respective circular recess  20 . The transverse groove  28  extends as far as the uppermost transverse wall that has the upper face  14   a . The groove bottom of the transverse groove  28  is formed by a partial hollow cylinder for fitting over the shaft  60 . 
     On each of the outer sides of the walls  13  is a respective raised, annular stop face  31 , which is concentric with the center of the circular recesses  30 . 
     Between the walls  13  and parallel to them, the transverse walls of the upper face  14   a  and the middle face  14   b  are joined at the rear end  18  by a support wall  32 , along which the uppermost face  14   a  has an elongated recess  34 . As a result, the transverse walls of the faces  14   a, b , the support wall  32  and the left-hand wall  13  form a hollow profile of rectangular cross section. 
     In the right-hand wall  13 , in the region of the elongated recess  34 , there is a wedge-shaped recess  36  opening toward the rear end  18 . It extends from the rear end  18  to near the circular recess  30  (FIG.  4 ). 
     At the end of the wedge-shaped recess  36 , the right-hand wall  18  has a wedge-shaped notch  37 . The notch is open toward the top and begins at the point of contact of the wall  13  with the uppermost face  14   a.    
     As viewed from the rear end  18 , this creates an inverted L-shaped, first yielding region in the form of a resilient tab  38 . On the side of the wall  13  toward the elongated recess  34  is a wedge-shaped first extension  40 , located on this resilient tab  38  and forming a first lateral stop face  40   a.    
     As shown in FIG. 4, two pegs  56  are located on one of the walls  13 , perpendicular to the wall  13 , near the circular recess  30 . 
     As FIG. 5 shows, the uppermost face  14   a  is joined to the middle face  14   b  in the region of the front end  16  along a radius  23 . Inward-oriented protuberances  24  are located, opposite the walls  13 , on the front end  16  of the connecting piece  10 . 
     At the radius  23  of the connecting piece  10 , as shown in FIGS. 3,  4  and  6 , there is a second yielding region  41 . The wall  13  at this point is recessed, as FIG. 4 shows, in such a way that a portion  44  of the radius  23  together with a projection  46  of the wall  13  can be bent elastically upward. The middle face  14   b  has a recess  42  of inverted L-shape, as viewed from the underside  20 , in the region of the radius  23 . Also located at the projection  46  of the wall  13  is a further lateral extension  48 , which forms a second stop face  48   a.    
     The transverse wall of the lowermost face  14   c , which extends from the rear end  18  to the transverse groove  28 , is also yielding, as can be seen in FIGS. 2 and 4, and forms a third elastic region  49 . To that end, the two walls  13  have oblique slots  50 , in such a way that the wall portions  51  that have the lowermost face  14 c are joined to the walls  13  only by thin, leaf-springlike oblique ribs  52 . Thus the lowermost face  14   c , as a yielding plateau  53 , can be displaced parallel in the direction of the middle face  14   b.    
     In the paragraphs that follow, the function of the connecting piece  10  will be explained. 
     As shown in FIG. 1 a , the wiper arm  11 , on its end remote from the wiper motor  12 , has a portion that is typically bent 180°. Depending on how the wiper arm  11  is embodied, the bend can have various radii R and a varying length L. The thickness D of the wiper arm  11  is equally variable. 
     The wiper blade  11   a , at the point intended for connection to the wiper arm  11 , has a fastening element  60 , serving as a shaft, which is often a rivet or a roller rivet. The connecting piece  10  is slipped onto this fastening element  60  by its transverse groove  28 , so that the fastening element  60  snaps into the circular recesses  30 . 
     If the wiper arm  11  has a width B that to the spacing between the wall  13 , which is remote from the tab  38 , and the first stop face  40   a  of the tab  38 , then the wiper arm  11 , after the insertion of the connecting piece  10 , is retained both between the first stop face  40 a and the opposed wall  13  on the top side and by the second extension  48 , which is located on the same side as the first extension  40 , and the opposed wall. Depending on the radius R of the bend of the wiper arm  11 , the bent piece L of the wiper arm  11  can either come between the middle face  14   b  and the lower face  14   c  or can come into contact under the lowermost face  14   c  of the connecting piece  10 . This is shown in FIGS.  7  and  8 . 
     The gripper locking of the connecting piece  10  to the wiper arm  11  is brought about by the protuberances  24 , which as part of resilient tongues press the connecting piece  10  against the radius  23 . Because of the triangular shape of the protuberance  24 , the most various wiper arm thicknesses D can be can be tightened by nonpositive engagement, in gripper fashion. This is shown in FIG.  9 . 
     If the width B of the wiper arm  11  is greater than the inside spacing between the stop face  40   a  and the opposed wall  13 , then when the connecting piece  10  is pulled onto the wiper arm  11 , the resilient tab  38  is automatically pressed downward by the wedge-shaped extension  40  and retained directly by the piece of the wall  13  that protrudes past the sloping plane of the extension  40 . The second yielding region  41  is also bent away by the second extension  48  (FIGS.  3  and  4 ), so that in addition to the locking between the radius  23  and the protuberance  24  of the connecting piece, a clamping tension is created between the second yielding region  41  and the uppermost face  14   a . However, if the radius R of the wiper arm  11  is so large that the bent end is not inserted between the middle face  14   b  and the lowermost face  14   c  but instead slips underneath the lowermost face  14   c , then the second yielding region  41  is not bent. In that case, an additional clamping tension can be brought about by the third yielding region  49 , by embodying the lowermost face  14   c  as a yielding plateau  53 . This is shown in FIGS. 10-13. 
     The direction of the slots  50  and thus of the ribs  52  is expediently selected such that to remove the connecting piece  10  from the wiper arm  11 , first a resistance must be overcome, because the friction of the wiper arm  11  at the lowermost face  14   c  causes an increase in the contact pressure of the lower face  14   c  against the wiper arm  11 . This is achieved because when the connecting piece  10  is pulled out of the wiper arm  11 , the lowermost face  14   c  adheres slightly to the wiper arm  11 , so that an erecting moment is exerted on the ribs  52 . The ribs  52  become more steeply erect relative to the wiper arm  11 , and as a result the spacing between the upper face  14   a  and the lower face  14   c  becomes greater, which increases the contact pressure. 
     The yielding regions  38 ,  41  and  49 , to limit the yielding, have stabilizing elements  58 , which are shown in FIG.  12 . Thus the recess  36  is formed such that precisely whenever the sloping plane of the extension  40  is in the same plane as the upper face  14 , or in other words the tab  38  is folded away toward the underside  20 , the stabilizing element  58  at one point strikes the wall  13  or a face  14 . In the face of the third elastic region  49 , analogously, the wall portions  51  are formed such that a maximum adjustment path can be specified. In this way, the ribs  52  are protected against excessive stress and thus against breaking. 
     The protuberances  24  on the resilient tongues of the walls  13  need not extend over the entire height of the connecting piece. For instance, as seen in FIG. 14, the protuberance  24  can extend over only part of the wall  13 , so that the force required for installation can be adjusted. 
     To limit the possible angle of rotation of the wiper blade  11   a  relative to the wiper arm  11 , two peglike elements  56  extending perpendicular from the wall  13  are disposed in the region of the circular recesses  30  where the wiper blade  11   a  rotates as shown in FIG.  15 . As shown in FIG. 1 a , the arrangement is made such that when the maximum desired angle of rotation is reached, a rim of the box region  62  of the wiper blade  11   a , in which the connecting piece  10  rotates, strikes one of the elements  56 . For installing the wiper blade  11   a , the connecting piece  10  does not have to be rotated out of the box region  62  of the middle bracket  61  of the wiper blade  11   a.