Abstract:
The invention is based on a link joint with a first lever ( 10 ) which is constructed as a bent sheet metal part and which has, at one end, a trough ( 24 ) for receiving a bearing pin ( 14 ) and with a second lever ( 12 ) having a bearing eye ( 15 ) which encloses the bearing pin ( 14 ) and which has a bearing part ( 16 ) that is held between two stop surfaces ( 18, 20 ) arranged at its front sides. It is proposed that the bearing pin ( 14 ) has a hollow space ( 22 ) which is open at least toward a front side.

Description:
BACKGROUND OF THE INVENTION 
     The invention is based on an articulation connection or link joint. 
     Link joints are frequently used in lever linkages, including wiper drives, especially in so-called four-bar linkage wiper drive installations. In this respect, a first lever, e.g., a fastening part, is usually constructed as a bent sheet metal part having, at the end on the joint side, a trough whose edge is bent outward at the free sides in the direction of the bottom of the trough in the shape of an apron or skirt and projects over the base of the trough. A bearing pin is riveted in the center of the trough accompanied by an outer washer, wherein a rivet part is formed integral with the bearing pin and the rivet head is covered by a protective cap which is fastened to the washer. The bearing pin is enclosed by a bearing eye of a second lever, e.g., a coupling lever, in which a bearing part of plastic is injected. The second lever is held axially between a bearing disk in the trough of the first lever and a collar of the bearing journal. The bearing between the bearing pin and the bearing part is sealed outwardly. The second lever carries an outer covering in the area of the bearing eye. 
     The wiper drives which are arranged in the area between a vehicle windshield and a part of the body, particularly an engine hood, substantially determine with their link joints the distance between the body part and the windshield, wherein this distance should be kept as short as possible for visual and acoustic reasons as well as for reasons of flow. 
     SUMMARY OF THE INVENTION 
     According to the invention, the bearing pin has a hollow space which is open at least toward one front side. This saves on material and weight on the one hand and, on the other hand, numerous possibilities are opened for constructing the link joint in a simpler and especially in a flatter manner in that the hollow space is utilized for the connection between the bearing pin and the first lever. 
     According to a construction of the invention, the trough has, in the center, a deep-drawn or cupped hollow body which projects into the hollow space of the bearing pin and is riveted at its front side with the bearing pin. The hollow body which is formed integral with the first lever can serve to fasten the bearing journal in the manner of a hollow rivet, but can also form the bearing journal by itself. In both cases, with the length of the bearing surface remaining the same, the link joint is flatter because, in the first case, the connection point between the first lever and the bearing pin lies within the joint and therefore does not take up any axial construction space and, in the second case, a connection point is omitted. An outer washer and protective cap can be dispensed with. This facilitates manufacture and assembly and reduces weight and use of material. Further, the connection point is located in an area with low mechanical loading with respect to bending moments. 
     Since the bottom of the trough forms the lower limit of the first lever, the skirt-shaped part of the trough edge which previously concealed the washer and protective cap can also be dispensed with. The trough edge advisably runs in a quarter circle transverse to a swivel axis and terminates radially with a joint cover at the second lever. The diameter of the bearing eye with its covering accordingly determines the greatest width of the lever which is reduced compared with conventional link joints. 
     The hollow body can be open or closed. When closed, it is no longer necessary to seal relative to the joint space. The hollow body can only project slightly into the hollow space of the bearing pin and can rest against a corresponding narrowed portion of the hollow space by its riveted head. In another construction, the hollow body is guided through the hollow space and is riveted at its free end with a collarless bearing journal via a bearing disk. In this case, the bearing journal is formed of a cylindrical spacer sleeve which is held between the two bearing disks. The hollow body is connected with the outer bearing disk in that its outer edge is beaded and the bearing disk presses against the end face of the spacer sleeve or its base is connected with the bearing disk by a separate rivet. According to another construction of the invention, the hollow body forms a collar at the front side for contact by the bearing disk, wherein the bearing disk is riveted against this collar with the outer part of the hollow body. 
     The height of the link joint can be further reduced through the use of a high-quality bearing bush, e.g., formed of plastic-coated steel, which is connected with the bearing pin or the bearing part. The length of the bearing surface and friction are reduced by the increased loading capacity and wear behavior is also improved. 
     When the hollow body itself serves as a bearing journal, a bearing material is preferably sprayed or injection-molded onto its outer circumference. The layer of bearing material extends up to the trough base. In this construction, the hollow body carries the second bearing disk at a collar, against which it is riveted with the edge of the hollow body. 
     The link joint can be constructed in a more economical manner even when the second lever is formed by a bent sheet metal part which has a substantially U-shaped cross section and has everted portions facing inward in the area of the link joint, wherein the bearing part is injection-molded on the everted portions on both sides. Owing to the injection on both sides, the everted portions do not deform during the injection process and the bearing surfaces can be produced within the desired tolerances. In order to promote the injection process, it is further advisable to more or less fill up the intermediate space between the everted portion and the U-shaped profile. 
     The U-shaped profile is lined with a plastic covering. When the covering closes the open side of the U-shaped profile, a lever is formed which is closed on all sides. The advantages of the second lever as a bent sheet metal part are so great that it appears worthwhile to utilize it not only in combination with a link joint according to the invention, but also with a link joint according to the preamble of claim 1. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages are indicated in the following description of the drawings. The drawings show embodiment examples of the invention. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will also advisably consider the features individually and combine them to form other useful combinations. 
     FIG. 1 shows a section through a link joint according to the prior art; 
     FIG. 2 shows a section through a link joint according to the invention; 
     FIG. 3 shows a variant of FIG. 2 with a bearing bush; 
     FIG. 4 shows a perspective view of a first lever according to a link joint according to the invention; 
     FIG. 5 shows a perspective view of a second lever as a bent sheet metal part; 
     FIGS. 6 to  9  show variants of FIG. 2; 
     FIG. 10 shows a section through a link joint according to FIG. 1 with a second lever as bent sheet metal part; and 
     FIG. 11 shows a section through a link joint according to FIG. 2 with a second lever as bent sheet metal part. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Conventional link joints have a first lever  10  which is constructed as a bent sheet metal part, wherein a trough  24  is formed integral therewith at one end on the joint side. A bearing pin  14  is arranged in the center of the trough  24 , wherein the bearing pin  14  is inserted through a bearing disk  80 , the base of the trough  24  and a washer  72  and riveted with a rivet part  76 . A protective cap  74  which is fastened to the washer  72  covers the rivet head  78 . The edge of the trough  24  is bent outward and extends over the region of the protective cap  74  in a skirt-shaped manner. 
     A second lever  12  comprises the bearing pin  14  with a bearing eye  15  in which a bearing part  16  conventionally made from plastic is injection molded. As a rule, it is produced as a die-cast part. The bearing part  16  runs on the bearing pin  14  and is supported axially at the bearing disk  80  and at a collar  82  of the bearing pin  14 . The bearing formed in this way is protected by a sealing cap  48  on the one hand and, on the other hand, by an axial seal in the form of a lip seal  40  or profile ring  42 ,  44  between the bearing disk  80 ,  36  and the bearing part  16 . A joint cover  34  fastened to the second lever  12  lines the joint area. 
     In the constructions according to the invention according to FIGS. 2 and 3,  6  to  9 , and  11 , the bearing pin  14  has a hollow space  22 , so that the connection between the first lever  10  and the bearing pin  14  can be situated in the bearing area and therefore does not take up any axial construction space. For this purpose, the hollow space  22  according to the construction shown in FIG. 2 forms a narrowed area toward the trough, so that the upset end of the hollow body  26  contacts a contact face  30  in the area of its front side  28 . The deep-drawn hollow body  26  is closed at its front side  28  and tightly closes the bearing at the connection point. Accordingly, the protective cap  74  and the washer  72  can be dispensed with so as to save on structural component parts and reduce the axial structural length. Further, a sealing cap  48  and a profile ring  42  in the form of a round rubber ring are provided which seal the bearing region at the front sides of the bearing part  16 . 
     Since the trough  24  is closed at the bottom and the base of the trough  24  forms the lower boundary of the first lever  10 , its apron-shaped edge can be omitted and the edge  32  can terminate in a quarter circle and close radially at the joint cover  34 . This results in a narrow first lever  10  whose width is substantially determined by the bearing eye  15  and the joint cover  34 . Due to these steps, the link joint is flatter and narrower given the same bearing surface. 
     In the constructions according to FIGS. 3,  6  and  7 , a bearing bush  46  formed of high-quality bearing material is provided, e.g., a so-called DU bush or plastic bush, which is fastened in the bearing part  16 . However, it can also be pressed on the bearing pin  26  (FIG.  7 ). Because of the greater loading capacity of the bearing bush  46 , the bearing surface can be reduced, especially its length, resulting in a flatter link joint construction. The seal between the bearing part  16  and the bearing disk  36  is formed, according to FIG. 3, by a profile ring  44  with a substantially square cross section and, according to FIG. 5, by a lip seal. 
     In the constructions according to FIGS. 6 to  9 , the stop face or terminating surface  18  is formed by another bearing disk  50 . This is held between a spacer sleeve  52  and an outer rivet edge of the hollow body  26  (FIG. 3) or is connected by a separate rivet  60  with the base of the hollow body  26 , wherein the hollow body  26  serves as a spacer piece between the bearing disks  36  and  50  (FIG.  6 ). The spacer sleeve  52  can accordingly be dispensed with. Finally, the bearing disk  50  can contact a collar  56  of the hollow body  26  and can be held by its rivet edge (FIGS.  8  and  9 ). In the constructions according to FIGS. 7 to  9 , the spacer sleeve  52  and bearing bush  46  can be omitted in that a bearing material  54  is applied directly to the hollow body  26 , in particular by injection. The bearing material  54  advisably extends into the area of the trough  24 , so that the bearing disk  36  can be omitted. 
     As was already mentioned, the inner front side of the hollow body  26  is advisably closed. However, it can also be constructed so as to be open (FIGS. 6 and 8) when a hat-shaped part  58  of the sealing cap  48  seals the opening. 
     The constructions according to FIGS. 10 and 11 have a second lever  62  in the form of a bent sheet metal part which has a U-shaped cross section and whose bearing eyes are formed by everted portions  64 . The latter are injection-molded on both sides with bearing material  70 . This ensures that the bearing areas retain their shape within permissible tolerances and do not deform during the injection process. For technical process-related reasons, the intermediate space  68  between the everted portion  64  and the U-shaped profile is filled to a greater or lesser extent with bearing material  70 . 
     The second lever  62  is lined on the outside with a plastic covering  66 . When the open side of the U-shaped profile faces toward the plastic covering  66 , this results in a closed lever  62  which is protected on all sides. The second lever  62  can take the place of the second lever  12  unconditionally, so that one or more advantages can be realized, as desired.