Abstract:
An outer joint part of a constant velocity universal joint comprises an externally cylindrical casing part. An inside is provided with tracks to allow the engagement of torque transmitting elements, and which further comprises a substantially annular flange part which is provided with a central inner recess and which is slid on to the casing part and connected thereto, as well as circumferentially distributed fixing holes for threading on a counter flange. The flange part comprises circumferentially distributed, individual, separate fixing portions which receive the fixing holes, and connecting portions which connect the fixing portions and have a greater flexibility than said fixing portions.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an outer joint part of a constant velocity universal joint which comprises an externally cylindrical casing part whose inside is provided with tracks to allow the engagement of torque transmitting elements, and which further comprises a substantially annular flange part which is provided with a central inner recess and which is slid on to the casing part and connected thereto, as well as provided with circumferentially distributed fixing holes for threading on a counter flange. 
     An outer joint part of this type is known from DE 43 14 503 C1. Between fixing portions having circular-arc-shaped outer edges, there are provided concave connecting portions and which have a smaller radial dimension than the fixing portions. The casing part and flange part are joined by a continuous weld. 
     In the attempt to save weight, outer joint parts of the above-mentioned type become more and more thin-walled. In some cases, outer joint parts which used to be exclusively forgings or hot-formed parts are now produced from plate metal by cold forming processes. 
     Even if a suitable material is selected, such thin-walled outer joint parts are easily deformable. One of the main objectives of modern forming processes consists in finish-producing the guiding tracks of the outer joint parts in the course of the forming operation which, at most, are followed by surface treatment processes. 
     This method is risky in that during subsequent assembly of the flange parts, the casing part of the outer joint part may be subject to deformation resulting in inaccuracies in the previously accurately produced guiding tracks. The measures of providing increased accuracy in producing the flange parts or of machining the seat faces for the flange parts at the casing part, which would prevent this deformation, are undesirable because of the additional costs. 
     It is therefore the object of the present invention to provide an outer joint part of the initially mentioned type which makes use of the advantages of a cost-effective production process without allowing any defects in the dimensional accuracy of the guiding tracks during the assembly of the casing part and flange part. 
     SUMMARY OF THE INVENTION 
     The solutions proposed to achieve the above objective are all characterized in that the flange part comprises circumferentially distributed, individual, separate fixing portions which receive the fixing holes, and connecting portions which connect the fixing portions and have a greater flexibility than the fixing portions. Furthermore, according to a first embodiment, it is only in the region of the fixing portions where the flange part is welded to the casing part. According to a second embodiment, the connecting portions are provided with apertures or slots. According to a third embodiment, the connecting portions comprise parts whose wall thickness is reduced as compared to that of the fixing portions. According to a fourth embodiment, the connecting portions comprise folds which project from the plane of the fixing portions. In the case of the second and further embodiment, the flange part can be continuously welded to the casing part. 
     These methods make it possible to fully utilize the scope available for the lightweight construction of the casing part in respect of the strength values required in operation, and at the same time to ease the requirements in respect of production accuracy, shape of the flange part and production of the respective seat face at the casing part. Even if the conditions of fit are inaccurate, assembly is possible without any distortion occurring in the casing part. The inaccuracies are compensated for by deformations in the regions of the connecting portions. Even with relatively large production tolerances, classification of the casing parts and flange parts is not required. By connecting the casing part and flange part, the casing part acquires the stiffness needed in operation. After the flange part has been slid on to the casing part, the connecting portions, in the case of press fits, are able to reduce forces as a result of their flexibility and, in particular, to bias non-uniform forces by means of deformation. 
     The dimensions of the connecting portions can be reduced in such a way that they can be regarded entirely as means for connecting the individual fixing regions to one another, in order to facilitate assembly. The individual fixing regions are stiffened relative to one another by being welded to the casing part and by being fixed to a sufficiently stable counter-flange. 
     To reduce the forces during press-fit assembly, knobs are preferably provided in the inner recess of the flange part, which knobs project inwardly beyond a continuous contour, or to provide knobs at the casing part in the region of the seat face for the flange part, which knobs project beyond a continuous outer contour. Such knobs are more easily deformable than the connecting portions, so that part of the forces or peak forces occurring during assembly are reduced immediately. The gap existing between the contact points in the regions of the knobs is preferably closed by a weld. The knob height is preferably small enough to allow the gap to be closed by laser welding. 
     Special embodiments of the connecting portions are described in the sub-claims to whose contents reference is made hereby. In particular, reference is made to the special description of the drawing. The fixing portions may preferably comprise one or two fixing holes each. In a preferred embodiment, there should be provided three or more fixing portions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the flange of an inventive outer joint part in the form of a detail, 
       a ) in a plan view 
       b ) in a longitudinal section according to sectional line  1   b—   1   b  of of FIG. 1 a.    
     FIG. 2 shows a tripode joint with an inventive outer joint part in a first embodiment 
       a ) in a longitudinal section according to sectional line  2 A— 2 A of FIG. 2 b    
       b ) in a cross-section according to sectional line  2 B— 2 B of FIG. 2 a    
       c ) in a view “X” according to FIG. 2 a.    
     FIG. 3 shows an inventive outer part of a tripode joint in a second embodiment, 
       a ) in a longitudinal section according to sectional line  3 A— 3 A of FIG. 3 b    
       b ) in a view “Y” according to FIG. 3 a.    
     FIG. 4 shows an inventive outer joint part in half a section, 
       a ) with a flange in a third embodiment in a quarter view, 
       b ) with a flange in a fourth embodiment in a quarter view. 
     FIG. 5 shows an inventive outer joint part in half a section 
       a ) with a flange in a fifth embodiment in a quarter view, 
       b ) with a flange in a sixth embodiment in a quarter view. 
     FIG. 6 shows an inventive outer joint part in half a section, 
       a ) with a flange in a seventh embodiment in a quarter view, 
       b ) with a flange according to FIG. 1 in quarter view. 
     FIG. 7 shows an inventive outer joint part in half a section, 
       a ) combined with a flange pre-mounted so as to define a gap, with knobs provided at the flange, 
       b ) combined with a flange pre-mounted so as to define a gap, with knobs provided at the joint part. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 a  and  1   b  show a substantially annular flange part  11  which, substantially, is cut out of a planar piece of plate metal with a constant thickness. The flange part  11  comprises a substantially round inner recess  12  into which it is possible to insert a casing part of an inventive outer joint part. It can be seen that the flange part is provided with three circumferentially distributed fixing portions  13  of greater strength which extend radially by approximately the same amount, and with three connecting portions  14  whose strength is considerably reduced due to their web-like shape. The fixing portions are provided with two fixing holes  15 ,  16  each. Between the two holes they comprise an outer indentation  17  which, however, does not greatly reduce the strength of the fixing portions  13  between the fixing holes  15 ,  16 . On their insides, the fixing portions are provided with a circular-arc-shaped fixing edge  18 . The connecting portions  14 , on their radial outsides, adjoin the neighboring fixing portions  13  by means of tabs  19 ,  20  and, while retaining their width, form an inwardly opening U-shaped web  21 . In accordance with the invention, the connecting portions  14 , on their insides, are contact-free relative to a casing part inserted into the inner recess  12  and are not permanently connected to same, whereas the fixing portions  13  are welded along the circular fixing edges  18  to the inserted casing part. As a result of the increase in flexibility, any fit inaccuracies occurring when sliding the flange part on to the casing part can be compensated for within the connecting portions  14  without adversely affecting the casing part. The flange part  11  shown here is provided for an externally circular-cylindrical casing part, such as they are particularly common in constant velocity ball joints. However, said flange part  11  can also be used for casing parts which, on their outsides, only comprise a circular-cylindrical turned recess, at least in the region of their bases, especially casing parts for tripode joints. 
     FIGS. 2 a ,  2   b ,  2   c  and  2   d  show a complete tripode joint whose outer part consists of a casing part  42  and a flange part  31 , with the latter corresponding to the flange part  11  according to FIGS  1   a  and  1   b . The casing part  42  comprises a cylindrical portion  43  and, at one end, is provided with an aperture  44  whereas at the other end it is closed by a base  45 . While having an approximately constant wall thickness, the cylindrical portion comprises a clover-leaf-like circumferential line for the purpose of forming three guiding tracks  46 . The inner joint part consists of a tripode  47  with three tripode arms  48  and roller assemblies  49  held thereon. A plug-in shaft  50  is inserted into the tripode  47  and axially secured thereto. The aperture  44  of the casing part  42  is sealed towards the outside by a convoluted boot  51 , and on to the casing part  42  there is placed a compensating element  52  which, on its inside, adapts itself to the contour of the cylindrical portion  43  and, on its outside, has a circular cross-section for the purpose of securing the convoluted boot. The flange part  31  is similar in design to that shown in FIGS. 1 a  and  1   b  and comprises three fixing portions  33  each having two fixing holes  35 ,  36 , as well as three connecting portions  34  with connecting tabs  39 ,  40  and a U-shaped web  41 . The inner fixing edges  38  which embrace the cylindrical portion  43  in portions, are arranged on an outer recess  53  in the base  45 , which recess has a circular cross-section in the seat region. The U-shaped webs  41  are arranged at a radial distance from the portions of the casing part  42  positioned between the guiding grooves  46 . 
     FIGS. 3 a  and  3   b  show an inventive outer joint part consisting of a casing part  72  and a flange part  61 . The casing part  72  comprises a cylindrical portion  73  with an aperture  74  and is closed by the base part  75  which, while having a reduced wall thickness, is spherical in shape in its center. In this embodiment, the flange part  61  comprises a total of six fixing portions  63 ,  65  and six connecting portions  64  connecting the fixing portions. The fixing portions  63 ,  65  each comprise only one centrally arranged fixing hole  66 ,  67 . The fixing portions  63 ,  65  differ from one another in respect of the shape of their fixing edges  68 ,  70  which are in contact with differently formed parts of the clover-leaf-shaped cylindrical portion  73 , so that the flange part  61  is secured against rotation on the casing part  72 . The connecting portions  64  are provided in the form of simple circumferential webs of a small radial thickness and arranged at a distance from the casing part  72 . 
     In FIGS. 4 a  and  4   b , a fourth flange part  81  and a fifth flange part  101  are each shown in a quarter view and arranged on a casing part  122 . 
     The flange part  81  in FIG. 4 a  is shown to be provided with two fixing portions  83 ,  85  which each comprise a centrally arranged fixing hole  86 ,  87 . The connecting portion  84  connecting the two fixing portions is provided in the form of a circumferentially extending narrow web which is arranged at a radial distance from the cylindrical portion  123  of the casing part  122  whose flexibility, furthermore, is reduced by a circumferential slot  89  which projects into the fixing portions  83 ,  85  and extends on a circular arc relative to the flange center. The shape of the connecting portion  84  is determined by the outer indentation  97  and an inner recess  98 . The shape of the fixing edges  88 ,  90  is adapted to the outer contour of the cylindrical portion  123 , so that the flange part  81 , in the direction of rotation, is form-fittingly secured on the casing part  122 . 
     The flange part  101  in FIG. 4 b  is shown to comprise two fixing portions  103 ,  105  which each comprise a centrally arranged fixing hole  106 ,  107 . The shape of the connecting portion  104  connecting the two fixing portions is defined by an outer circular edge  117  and inner adapting means  118  relative to the cylindrical portion  123  of the casing part  122 , with the flexibility of the connecting portion  104  being reduced only by three radial slots  109  which are located between the fixing portions  103 ,  105  and are aligned radially relative to the flange center. The shape of the fixing edges  108 ,  110  is adapted to the outer contour of the cylindrical portion  123 , so that, in the direction of rotation, the flange part is form-fittingly secured on the casing part  122 . 
     FIGS. 5 a  and  5   b  shows a quarter illustration of the sixth flange part  141  and of the seventh flange part  161 , both arranged on a casing part  182 . The flange part  161  corresponds to the flange part  61  according to FIG. 3 b.    
     The flange part  141  in FIG. 5 a  is shown to comprise two fixing portions  143 ,  145  which each comprise a centrally arranged fixing hole  146 ,  147 . The shape of the connecting portion  144  connecting the two fixing portions is defined by an outer indentation  157  and inner adapting means relative to the cylindrical portion  183  of the casing part  182 , with the flexibility of the connecting portion  144  being reduced only by radial grooves  149  which are located between the fixing portions  143 ,  145  and are aligned radially relative to the flange center. The shape of the fixing edges  148 ,  150  is adapted to the outer contour of the cylindrical portion  183 , so that, in the direction of rotation, the flange part is form-fittingly secured to the casing part  182 . In a sectional view, the radial grooves are shown in two embodiments. According to the first detail a, the radial groove is achieved by a stamped protrusion on one side and according to the second detail b, by stamped impressions on both sides. 
     The flange part  161  in FIG. 5 b  is shown to comprise two fixing portions  163 ,  165  which each comprise a centrally arranged fixing hole  166 , 157 . The connecting portion  164  connecting the two fixing portions is provided in the form of a circumferentially extending narrow web arranged at a radial distance from the cylindrical portion  183  of the casing part  182 , with the flexibility of the connecting portion  164  being reduced exclusively by its shape. The shape of the connecting portion is determined by an outer indentation  177  and an inner recess  178 . The shape of the fixing edges  168 ,  170  is adapted to the outer contour of the cylindrical portion  183 , so that, in the direction of rotation, the flange part  161  is form-fittingly secured to the casing part  182 . 
     FIGS. 6 a  and  6   b  show a quarter illustration of an eighth flange part  201  and of a ninth flange part  211 , both arranged on a casing part  242 . The flange part  221  corresponds to the flange parts  11 ,  31  according to FIGS. 1 a  and  1   b  and  2   a  and  2   b.    
     The flange part  201  in FIG. 6 a  is shown to comprise two fixing portions  203 ,  205  which are each provided with a central fixing hole  206 ,  207 . The connecting portion  204  connecting the two fixing portions is provided in the form of a web whose width is reduced and which is provided with an outer indentation  217  and inner adapting means  218  relative to the cylindrical portion  243  of the casing part  242 , with the flexibility of the connecting portion  204  being reduced by the expansion fold  209  which is located between the fixing portions and which is aligned relative to the flange center. The shape of the fixing edges  208 ,  210  is adapted to the outer contour of the cylindrical portion  243 , so that, in the direction of rotation, the flange part  201  is form-fittingly secured to the casing part  242 . The sectional view, in the form of a detail, shows an embodiment of the expansion fold  209  in an enlarged scale. 
     The flange part  221  according to FIG. 6 b  is provided with two fixing portions  223  of an increased strength and with one connecting portion  224  whose strength is reduced considerably due to being provided in the form of a web. The fixing portions  223  are each provided with two fixing holes  225 ,  226  one of which is shown in each case. They each comprise an outer indentation  227  which, however, does not greatly reduce the strength of the fixing portions  223  between the fixing holes  225 ,  226 . On their insides, the fixing portions are provided with a fixing edge  228  which is adapted to the casing part  243 . On its radial outside, the connecting portion  224 , by means of tabs  229 ,  230 , adjoins the neighboring fixing portions  223  and, while retaining a constant width, forms an outwardly opening U-shaped web  231 . 
     FIGS. 7 a  and  7   b  show a quarter illustration of a tenth flange part  261  and an eleventh flange part  281  which substantially correspond to the flange parts  141  and  201  in FIGS. 5 a  and  6   a  and are slid on to associated casing part portions  302 ,  322 . 
     The flange part  261  in FIG. 7 a  is shown to comprise two fixing portions  263 ,  265  which are each provided with a central fixing hole  266 ,  267 . The shape of the connecting portion  264  connecting the two fixing portions is defined by an outer indentation  277  and inner adapting means  278  relative to the cylindrical portion  303  of the casing part  302 , with the flexibility of the connecting portion  264  being reduced by a radial weak zone  269  which is not illustrated in greater detail and which is located between the fixing portions  263 ,  265  and is aligned radially relative to the flange center. The shape of the fixing edges  268 ,  270  is adapted to the outer contour of the cylindrical portion  303 , so that, in the direction of rotation, the flange part is form-fittingly secured to the casing part  302 . At the fixing portions, there are arranged knobs  271 ,  272  in pairs which form a radial gap  273  relative to the cylindrical portion  303  during assembly, with a weld being produced in said radial gap. 
     The flange part  281  in FIG. 7 a  is shown to comprise two fixing portions  283 ,  285  which are each provided with a central fixing hole  286 ,  287 . The shape of the connecting portion  284  connecting the two fixing portions is defined by an outer indentation  297  and inner adapting means  298  relative to the cylindrical portion  323  of the casing part  322 , with the flexibility of the connecting portion  284  being reduced only by a weak zone  289  which is not described in greater detail, which is located between the fixing portions  283 ,  285  and which is aligned radially relative to the flange center. The shape of the fixing edges  288 ,  290  is adapted to the outer contour of the cylindrical portion  323 , so that, in the direction of rotation, the flange part is form-fittingly secured to the casing part  322 . The outer contour of the cylindrical portion  323  is provided with knobs arranged in pairs which form a radial gap relative to the flange part  281  during assembly, with a weld being produced in said radial gap. 
     Preferred embodiments have been disclosed. However, the claims should be studied to determine the true coverage of these inventions.