Abstract:
A suspension strut support bearing with a spring retainer on a housing part made from plastic and a cup-shaped retainer for a limit bumper is provided. The cup-shaped retainer fits at least partially into the housing part in the axial direction and is held on the housing part guided in the radial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of German Patent Application No. DE 10 2010 011 423.5, filed Mar. 15, 2010, which is incorporated herein by reference as if fully set forth. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a suspension strut support bearing with a spring retainer on a housing part made from plastic and to a cup-shaped retainer for a limit bumper, wherein the cup-shaped retainer fits at least partially into the housing in the axial direction and is held on the housing guided in the radial direction. 
       BACKGROUND 
       [0003]    From DE 103 59 638 B3, such a suspension strut support bearing is known that is formed from an upper housing part, a lower housing part, and a rolling bearing encapsulated by the lower and the upper housing parts. The upper housing part is arranged on the side of the car body and the lower housing part is arranged on the side of the road surface. The coil spring of the suspension strut is supported on the lower housing part accordingly. 
         [0004]    Suspension strut support bearings are axial supports, because the primary loading directions of the vehicle-side loads against the spring forces are predominantly axial directions that are thus oriented in the same direction as the pivot axis of the suspension strut support bearing. Independent of this situation, however, suspension strut support bearings are often also loaded by radial force components in the radial direction, that is, perpendicular to the pivot axis of the suspension strut support bearing. These radial force components are generated, for example, when the center axis of the coil spring and the pivot axis of the suspension strut support bearing are not aligned. In addition, the force transfer of the spring forces on the spring retainer into the lower housing part is not uniform, which could be dependent, for example, on the position of the end of the coil spring and its torsion characteristics when it is deflected. For hard impacts on the road surface, the coil spring could deflect so much that the limit bumper begins to carry a load. This limit bumper also held on the lower housing of the suspension strut support bearing in the retainer is an arbitrarily shaped rubber pad that is also designated as a bump stop. The impacts absorbed by the bump stop with peak forces definitely up to 60 kN are transferred, in the extreme case, at least partially also into the lower housing of the suspension strut support bearing. 
         [0005]    The previously mentioned influences lead to the result that the loads are not transferred uniformly on the periphery of the suspension strut support bearing. Thus there are zones that are highly loaded and less highly loaded in the suspension strut support bearing, wherein the positions of these zones are known to design engineers as a function of the vehicle type. In the past, those skilled in the art have increasingly moved, as described in DE 103 59 638 B3, towards replacing spring retainers made from metal with lower housing parts made from plastics for reasons of costs. The spring retainer and a holder/retainer for the bump stop are integrated in the housing parts. The higher elasticity modulus of the housing parts made from plastic could have the result that such non-uniform loading has a much greater effect than before on non-uniform distributions of the loads in the suspension strut support bearing. 
         [0006]    The high loads therefore often resulted in someone skilled in the art reverting to suitable measures like the use of reinforcement made from sheet metal on the lower housing part, in order to avoid impermissible deformation. Such measures lead to increased production costs and thus at least partially cancel out the cost advantages that could be achieved by the use of plastic. In addition, the seats of the retainers for the bump stop made from metal could become loose due to the loads and the different coefficients of thermal expansion in the housing parts made from plastic. 
         [0007]    The non-uniform loads prompt someone skilled in the art to shape the more highly loaded zones of the lower housing part differently than the other zones in part through suitable structural measures. Due to these partially non-obvious measures, the suspension strut support bearings must be installed oriented with respect to direction or position. In addition, a position-oriented assembly or positioning could also be required due to other conditions of the arrangement, such as, for example, due to the position of the end of the last winding of the coil spring. Furthermore, a position-oriented direction for automated assembly could be required. 
       SUMMARY 
       [0008]    The objective of the invention is therefore to create a suspension strut support bearing of the class-forming type that can be produced simply and economically. In addition, the position of the individual components, especially the retainer of the limit bumper in the suspension strut support bearing, should be guaranteed in an operationally reliable way over the entire service life of the vehicle. Furthermore, a position-oriented alignment of the suspension strut support bearing should be ensured during assembly. 
         [0009]    This objective is met according to the invention. 
         [0010]    The suspension strut support bearing has a spring retainer on a housing part of the suspension strut support bearing. The spring retainer is provided for holding the last winding of the coil spring of a suspension strut. The housing part is made from plastic. 
         [0011]    The two axial directions set opposite each other are directions in the same direction as the pivot axis of the suspension strut support bearing. Radial directions are directions projecting at a right angle arbitrarily from the pivot axis. 
         [0012]    The housing part is the lower housing part of the suspension strut support bearing, with an upper housing part being allocated to this lower housing part. Between the housing parts, selectively a rolling bearing or a slide bearing is arranged in the axial direction, so that these form a common housing and thus encapsulate the roller or slide bearing. It is also conceivable that, in addition to the axial support, a radial bearing component in the form of a slide bearing or a rolling bearing is arranged in the housing. 
         [0013]    The suspension strut support bearing is predominantly designed as an axial support and is a pivot support through which forced movements (torsion) on the support of the car body between this car body and the suspension strut due to pivoting of the two housing parts are as friction free as possible. 
         [0014]    A cup-shaped retainer for a limit bumper sits in the housing. The cup-shaped retainer has a base that is perforated and extends essentially in the radial direction and a side wall that projects from the base, predominantly in an axial direction. The base advantageously has an annular disk-shaped construction. Alternatively, the base could also be curved or shaped with beads or shaped differently in some other way. The retainer is advantageously a cold-formed component made from sheet metal, in particular, sheet steel. The side wall advantageously has a hollow cylindrical construction, but could also have cross sections shaped differently in some other way and could be provided with beads or other shaped elements. At the opening of the cup-shaped retainer, at least one edge projects from the side wall, wherein, with this edge, the retainer can be supported, for example, toward the car body on the lower housing part. 
         [0015]    The lower housing part has, on the side of the road surface, an opening that is directed in the axial direction, with the retainer with the base being inserted into this opening. The retainer is inserted at least so far into the lower housing that a part of its side wall around the pivot axis is surrounded at least partially by the material of the lower housing part. 
         [0016]    So that the seat of the retainer cannot become loose in the lower housing part despite high loads and different thermal expansion of the components, individual holding elements are constructed on the housing part according to the invention. The holding elements are arranged around the retainer. The holding elements engage behind the retainer with a positive fit in at least one axial direction and thus secure the retainer in the lower housing part. The holding elements hold the retainer either in interaction with one edge in the passage opening or secure the retainer in both axial directions on the housing. So that the retainer can be inserted easily and with low resistance into the lower housing part, several individual holding elements are arranged with spacing relative to each other around the pivot axis. 
         [0017]    One construction of the invention provides that the retainer has windows formed in the side wall of the retainer around the pivot axis with spacing relative to each other. The windows are passage holes of arbitrary cross section directed in the radial direction. In each of the windows, at least one of the holding elements engages with a positive fit in the radial direction and thus the side wall engages behind at least one edge of the window in at least one direction. Through such an arrangement of the positive-fit connection, a secure solution that saves space especially in the axial directions is created. 
         [0018]    The invention further distinguishes itself in that the housing part has at least a first type of holding elements that are flexible in the radial direction and a second type of holding elements that are rigid in the radial direction. Both types of holding elements on the lower housing part extend in the radial direction in the form of radial projections into the opening of the lower housing part and thus are initially in the way of the retainer for insertion into the opening. 
         [0019]    Flexible in the radial direction means that, when the retainer is inserted into the lower housing part, the holding elements of the first type deflect elastically in the radial direction so far that these can be pushed between the holding elements of the first type and the second type until the holding elements of both types meet the windows predetermined for them and lock in these windows. 
         [0020]    Holding elements of the rigid type are holding elements that are not at all or only barely noticeably flexible in the radial direction compared with the holding elements of the type that are flexible in the radial direction and therefore, these rigid type holding elements could shear off when the retainer is inserted into the opening or must be designed with slight radial extent of offset relative to the retainer. For use of just holding elements of the second type, too little extent of offset could have the result that the seat becomes loose in the case of different thermal expansion of the components. The invention provides, however, a combination of first types and second types of holding elements that are distributed around the pivot axis so that, for assembly of the retainer, the holding elements of the first type yield to a sufficient enough degree in the radial direction, in order to also compensate for the radial overlap of the rigid holding elements. 
         [0021]    With one construction of the invention it is provided that the holding elements of the first type are each formed by at least one snap tab that is constructed in most cases on the end on an elastically flexible lever. Each snap tab is connected in an elastically flexible way to the housing part by the lever fixed on one side on the housing. Levers and snap tabs are advantageously made from the same material as the lower housing part and constructed integrally with this part. So that the lever and thus the associated snap tab can deflect freely and elastically in radial directions by the necessary path, this is released relative to the other material of the housing in the direction about the pivot axis and in the radial direction between the lever and housing as well as between the snap tab and housing. 
         [0022]    “Released” means that an air gap is formed in the mentioned directions between the lever or the snap tab and the material of the housing. In the radial direction, the air gap must be at least so large that, at least under consideration of all of the tolerances, the associated snap tab can deflect according to its function. Alternatively, the snap tab is completely free from the housing in the radial direction. The air gap directed in the directions about the pivot axis can have an arbitrarily narrow or wide design, because this should ensure only the radial movement of the associated lever with the snap tab. 
         [0023]    The advantage of the invention lies in that, in the seat of the retainer in the housing part, sufficient radial extent of offset for secure holding can be guaranteed even for high loads and large play by means of the positive-fit connection between holding elements and the retainer and thus between the lower housing part and the retainer. 
         [0024]    As already described in the “Background” section, suspension strut support bearings are not loaded uniformly in any case. There are zones of higher loading and lower loading distributed around the periphery. The advantage of a combination of holding elements of a flexible, elastic type and a rigid type lies in that the holding elements of the second type are constructed in the zones of the housing part that are exposed to high loads. Because these extend merely as radial projections from the material of the housing part, the solid structure of the lower housing part is not weakened. 
         [0025]    The elastically flexible construction of the holding elements of the first type necessarily leads to the result that the lower housing part is weakened in these regions. The holding elements of the first type are therefore arranged in zones of the lower housing part that are less affected by high loads. 
         [0026]    One construction of the invention provides that the retainer has at least one position orientation element for the oriented installation of the retainer in the housing part. This can then be especially useful when the holding means or the lower housing part do not have symmetric constructions and an oriented assembly is required. In this respect it is further provided that the position orientation element are oriented to one type of the holding elements. This is especially advantageous when the retainer must already have, for various reasons, a position orientation element for the directed assembly of the suspension strut in a suspension strut arrangement. For example, such a position-oriented assembly can ensure that the suspension strut support bearing is directed with the holding elements of the second type in the zones with the higher loads and with the holding elements of the first type in the zones with lower loading. 
         [0027]    The position orientation elements are selectively hidden (for example, magnetic) or visible and advantageously formed by at least one flattened section running perpendicular to the axial direction on the cup-shaped retainer. Thus, two of the flattened sections could lie opposite and parallel to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will be explained in detail below with reference to an embodiment. In the drawings: 
           [0029]      FIG. 1  is a perspective overall view of a suspension strut support bearing, 
           [0030]      FIG. 2  is a longitudinal section through the suspension strut support bearing according to  FIG. 1  along the pivot axis of the suspension strut support bearing, 
           [0031]      FIG. 3  is a view X on the suspension strut support bearing according to  FIG. 1 , 
           [0032]      FIG. 4  is a perspective overall view of the lower housing part of the suspension strut support bearing according to  FIG. 1 , 
           [0033]      FIG. 5  is the view Y on the lower housing part according to  FIG. 4 , 
           [0034]      FIG. 6  is a longitudinal section along the line VI-VI from  FIG. 5  of the lower housing part, 
           [0035]      FIG. 7  is a perspective overall view of the retainer of the suspension strut support bearing according to  FIG. 1 , and 
           [0036]      FIG. 8  is a section diagram of the retainer according to  FIG. 7  in a plane cut perpendicular to the pivot axis. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]      FIG. 1  shows a perspective overall view of a suspension strut support bearing  1  that is illustrated in  FIG. 2  in a longitudinal section along the pivot axis  2  of the suspension strut support bearing  1 . An upper housing part  4  is snapped together with a lower housing part  3 . Between the housing parts  3  and  4  there is a rolling bearing  5  that is arranged in the axial direction and is sealed in the radial direction towards the outside by a seal  6  and in the radial direction towards the inside by a seal  7 . The suspension strut support bearing  1  has a spring retainer  8  on the lower housing part  3  for support of a last winding  8   a  of a coil spring of a not-shown suspension strut, wherein this last winding is shown only in outline. The pivot axis  2  of the suspension strut support bearing  1  is oriented in the axial direction. A cup-shaped retainer  9  for a not-shown limit bumper sits in the lower housing  3 . 
         [0038]    The cup-shaped retainer  9  is shown in  FIG. 7  in a perspective overall view and has a base  10  that is perforated and extends essentially in the radial direction and a side wall  11 . At the opening of the cup-shaped retainer  9 , at least one edge  12  projects from the side wall  11 , wherein this edge can be seen especially from  FIGS. 7 and 8 .  FIG. 8  shows a section diagram of the retainer  9  according to  FIG. 7  in a plane cut perpendicular to the pivot axis  2 . The retainer  9  has windows  13  formed in the side wall  11  on the peripheral side around the pivot axis  2  with spacing relative to each other. The windows  13  are passage holes of rectangular cross section directed in the radial direction. 
         [0039]    The retainer  9  has a position orientation element for the oriented installation of the retainer  9  in the lower housing part  3 . The position orientation element is formed by two parallel flattened sections  14  running perpendicular to the axial direction at the edge  12  of the retainer  9 . Two of the flattened sections  14  lie parallel to each other. 
         [0040]    As shown in  FIG. 2 , the lower housing part  3  has an opening  15  directed in the axial direction, wherein the retainer  9  with the base  10  is inserted into this opening. The retainer  9  is thus inserted into the lower housing part  3  so far that its side wall  11  is surrounded about the pivot axis  2  by the material of the lower housing part  3 . In addition, the retainer  9  is supported in the axial direction by the edge  12  on the lower housing part  3 . 
         [0041]      FIG. 4  shows a perspective overall view of the lower housing part  3 .  FIG. 5  shows the view Y on the lower housing part  3  according to  FIG. 4  and  FIG. 6  shows a longitudinal section along the line VI-VI from  FIG. 5  of the lower housing part  3 . On the lower housing part  3 , individual holding elements  16  and  17  are constructed. 
         [0042]    A first type of holding elements  16  has a construction that is flexible in the radial direction. A second type of holding elements  17  is rigid. Both types of the holding elements  16  and  17  on the lower housing part  3  extend in the form of radial projections  18  in the radial direction into the opening  15  of the lower housing part  3  and the retainer  9  is in the way when inserted into the opening  15 , because the radial distance R of the inner edges  19  of the associated projections  18  relative to the pivot axis  2  is less than the outer diameter D A  of the retainer  9  or the guide diameter D A  in the circular opening  15  ( FIG. 3 ). 
         [0043]    The first type of holding elements  16  and the second type of holding elements  17  are constructed in the ratio of 1:2 with respect to quantities and are distributed around the pivot axis  3  such that, in this case, two holding elements  17  of the rigid type lie opposite each other on the pivot axis  3  and on the peripheral side, two adjacent, elastically flexible holding elements  16  in-between with uniform spacing relative to each other. 
         [0044]    The holding elements  16  of the first type are each formed by at least one snap tab  20  that is constructed on the end of an elastically flexible lever  21 . Each snap tab  20  is connected in an elastically flexible way to the lower housing part  3  by the lever  21  fixed on one side on the lower housing part  3 . So that the lever  21  and thus the associated snap tab  20  can deflect freely by the necessary path elastically in the radial directions, this is released by air gaps  22  and  23  relative to the other material of the lower housing part  3  in the direction about the pivot axis  2  between the lever  21  and housing part  3  as well as between snap tab  20  and housing part  3 . The holding elements  17  of the second type are, in contrast, rigid projections of snap tabs  24  that extend directly from the wall  25  of the lower housing  3 . 
         [0045]    Referring again to  FIGS. 1 and 2 , the holding elements  16  and  17  are arranged around the retainer  9 . The holding elements  16  and  17  engage behind the retainer  9  with a positive fit in an axial direction, such that one of the holding elements  16  or  17  engages in each of the windows  13  with a positive fit in the radial direction and thus the side wall  11  engages behind an edge  26  of the window  13  in one direction. 
         [0046]    The position orientation elements are oriented to the second type of holding elements  17  in that the flattened sections  14  are allocated to windows  13   a , wherein the snap tabs  24  lock onto the mounted suspension strut support bearing  1  in these windows. 
       REFERENCE SYMBOLS 
       [0000]    
       
           1  Suspension strut support bearing 
           2  Pivot axis 
           3  Lower housing part 
           4  Upper housing part 
           5  Rolling bearing 
           6  Seal 
           7  Seal 
           8  Spring retainer 
           8   a  Winding 
           9  Retainer 
           10  Base 
           11  Side wall 
           12  Edge 
           13  Window 
           14  Flattened section 
           15  Opening 
           16  Holding element 
           17  Holding element 
           18  Projection 
           19  Inner edge 
           20  Snap tab 
           21  Lever 
           22  Air gap 
           23  Air gap 
           24  Snap tab 
           25  Wall 
           26  Edge