Abstract:
A hydraulically damping rubber bush bearing suitable for absorbing cardanic loads in the vertical installed position and yet has a simple geometry and construction. The bearing has chambers receiving the damping agent and has an undercut in the direction of the bearing axis at least in the area of one of their axial ends. An inner cage and the elastomeric bearing body are axially shortened in the corresponding circumferential section compared to the rest of their circumferential sections.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a continuation of and claims the benefit (35 U.S.C. § 120 and 365(c)) of copending International Application PCT/DE 2004/000671 of Mar. 30, 2004, which designated inter alia the United States and which claims the priority of German Application DE 103 15 645.3 of Apr. 4, 2003. The entire contents of each application is hereby incorporated by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention pertains to a hydraulically damping rubber bush bearing, preferably for mounting the control arm of a motor vehicle axle, which is designed for vertical mounting and for absorbing cardanic loads in this installed position. 
   BACKGROUND OF THE INVENTION 
   Hydraulically damping rubber bearings, so-called hydrobushes, are installed, in general, horizontally, i.e., lying in relation to their bearing axis, in connection with the mounting of parts of the wheel suspension of a motor vehicle. The currently common horizontal mounting of the hydrobushes has the drawback that mounting in the vehicle is relatively expensive. This is linked with the fact that automatic feeding of the bolt used to fasten the bush is basically not possible and fully automatic mounting is therefore very extensively ruled out. The bearings are therefore mounted usually manually, which leads to an increase in the manufacturing costs. 
   In case of vertical installation, which is more favorable for automatic mounting, most of the hydrobushes used so far have problems in terms of service life. Above all, cardanic loads lead to increased wear in this case and, as a consequence of this, to reduced service life of the bearings. Prior-art constructions show especially great problems in the transmission of cardanic angles of up to ±20°. 
   DE 100 57 191 A1 describes a hydraulically damping rubber bearing, whose cardanic loadability was also increased in case of vertical installation by special design measures. The metallic inner part has bulging, approximately spherical outer surfaces for this purpose in its axially middle area. The rubber springs connected with it by vulcanization, as well as an intermediate sleeve arranged in the bearing are adapted to this shape of the contour of the inner part. A comparatively complicated bearing geometry is obtained as a result, which leads to increased costs for the manufacture of the bearing. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is therefore to design a bearing that is suitable for absorbing cardanic loads in case of a vertically installed position such that this has a simple geometry and construction. As a result, the bearing is said to be able to be manufactured at low cost despite the advantage that fully automatic mounting of the bearing is possible in case of appropriate use. 
   The hydraulically damping rubber bush bearing proposed according to the present invention, which is designed for vertical mounting, first comprises, in the known manner, an essentially cylindrical, metallic inner part, a metallic sleeve (inner cage) arranged concentrically therewith, and an elastomeric bearing body, which is arranged between the inner part and the inner cage and is connected with them by vulcanization. Distributed over its circumference, at least two chambers connected with one another by a channel are arranged in the elastomeric bearing body for receiving a fluid damping agent. In a manner that is essential for the present invention, the radially inner wall of each chamber (inner chamber wall) passes over from a section that follows the bearing axis essentially in parallel in an area of at least one of the axial ends of the chamber into a section having a shape that is sloped against the bearing axis. As a result, an undercut extending in the direction of the bearing axis is formed. At the same time, the inner cage and the elastomeric bearing body are axially shortened compared to the rest of their circumferential sections corresponding to each axial end of a chamber, which end is provided with such an undercut, in a circumferential section corresponding essentially to the extension of the particular chamber. This bearing construction, which is characterized above all by the combination of the features of an undercut chamber inner wall and an inner cage correspondingly shortened axially as well as an axially shortened bearing body, enables the bearing in an especially advantageous manner to absorb cardanic effects by a corresponding spring deflection via the chambers filled with the damping agent. Up to a cardanic angle of ±20°, cardanic forces cause a markedly lower wear on the bearing than in case of, e.g., vertically installed bush bearings of the conventional construction. Moreover, it shall be stressed as an especially advantageous feature that especially the inner part or the inner tube of the bearing can remain unchanged in its usually cylindrical shape, which leads to a simpler construction than in the case of the bearing designed for vertical installation, which was described in the description of the state of the art. The preparation of the undercut during the casting of the bearing with the elastomer as well as the axial shortening of the elastomeric bearing body in this area are not critical anyway from the viewpoint of the manufacturing technology, but the manufacture of the inner cage shaped correspondingly at the axial front ends also leads to an insignificant increase in the costs only. 
   In the design according to the present invention as shown, the rubber bush bearing can be mounted either directly at the corresponding point, for example, in the area of the wheel suspension of a motor vehicle, or it may be received for mounting by a preferably metallic outer sleeve. In the latter case, the outer sleeve is likewise shortened axially in the area of the undercuts of the chamber inner walls analogously to the bearing body and to the inner cage. 
   Depending on the intended use of the bearing, different embodiment variants of the bearing according to the present invention are possible while the basic idea of the invention is maintained. Corresponding to a possible embodiment, the bearing has two damping agent chambers, which have an undercut in the area of one of their axial ends. To make it possible to absorb cardanically acting forces, the undercuts of the two chambers are arranged diametrically in relation to one another relative to the axial extension of the bearing. 
   In an embodiment of the rubber bush bearing according to the present invention that is especially relevant for practice, two chambers, which have an undercut axially on both sides, are formed in the elastomeric bearing body of the rubber bush bearing. The two chambers are preferably arranged at an angle of 180° in relation to one another relative to the circumference of the bearing, but this also depends on the states of load to be expected during the use of the bearing. 
   The undercut of the inner chamber walls can already be obtained, in principle, by their corresponding shape. This also leads already to an improvement of the cardanic properties. However, the walls of the chambers located radially on the outside (outer chamber walls) preferably also have a shape sloped against the bearing axis in the area of the undercut formed by the corresponding shape of the corresponding inner chamber wall. In the area of a section led in parallel to the bearing axis and through the center of the circumferential extension of a chamber, the shape of the outer chamber walls follows essentially that of the inner chamber walls. The inner and outer chamber walls are optionally located at a constant distance from one another in the area in which they have basically the same shape. 
   However, corresponding to an advantageous variant, the distance between the inner and outer chamber walls increases in the areas that are the outer areas relative to the circumferential extension of the chambers. The chambers consequently expand toward these outer areas and form an opening at an angle of 90° in relation to the direction of damping. At the same time, rubber stops are formed due to the reduced distance between the inner and outer chamber walls in the area of the center of the circumferential extension of the chambers. However, it is also possible to make the stops out of plastic. 
   Insofar as this is necessary based on the intended use and the requirements associated therewith, special insert parts may be arranged between the bearing body and the inner part and/or the inner cage corresponding to possible variants of the bearing according to the present invention to shorten the radial path of the bearing body of the bearing. Such insert parts, which preferably consist of metal or plastic, are introduced during the mounting of the bearing. 
   According to another possible embodiment of the bearing according to the present invention, the metallic inner tube of the bearing has a flattened area extending over its entire axial length in the areas adjoining an inner chamber wall. 
   The present invention shall be explained once again in greater detail below on the basis of an exemplary embodiment. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which the preferred embodiment of the invention is illustrated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a three-dimensional view of the bearing according to the present invention; 
       FIG. 2  is a sectional view of the bearing according to  FIG. 1  with a section along line A-A of  FIG. 1  and showing two opposing long sections of the an outer sleeve; 
       FIG. 3  is a sectional view along section line B-B of  FIG. 2 , showing the bearing according to  FIG. 1  or according to  FIG. 2  and showing two opposing short sections of the an outer sleeve; 
       FIG. 4  is a sectional view along section line C-C of  FIG. 2 , showing the bearing according to the above figures; and 
       FIG. 5  is a three-dimensional view of a bearing according to  FIG. 1  with an outer sleeve (a channel carrier element). 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  pertains to a three-dimensional view of an exemplary embodiment of the bearing according to the present invention. However, a more detailed explanation of the individual parts of the bearing shall be offered on the basis of the sectional views in  FIGS. 2 through 4 . 
     FIG. 2  shows the bearing according to  FIG. 1  in a sectional view with a section led along line A-A. The essential parts of the bearing, which are already known as such from the state of the art, can be recognized in the view. Thus, the bearing comprises a metallic, essentially cylindrical inner part or inner tube  1 , a sleeve  2  arranged concentrically therewith (inner cage), and the elastomeric bearing body  3 , which is arranged between these parts and is connected with them by vulcanization. The chambers  4 ,  4 ′ formed in the elastomeric bearing body  3  for receiving the fluid damping agent are not recognizable in this view because of the sectional plane. However, it can be seen that upper and lower edges of the inner cage  2  provide two opposing long sections of the inner cage  2  that can be recognized in this view have approximately the same axial length as the inner part or inner tube  1 . 
   However, as is shown in  FIG. 3 , the conditions are completely different in respect to a section led along line B-B. The upper and lower edges of the inner cage  2  provide two opposing short sections of the inner cage  2  and of the bearing body  3  that can be recognized in  FIG. 3  and are markedly shortened concerning their axial extension compared to the inner tube  1 . As can be seen in  FIGS. 1 ,  2  and  3 , the bearing body  3  has an upper surface following a path of an upper edge of the inner cage  2  from long sections to adjacent short sections and has a lower surface following a path of the inner cage  2  from long sections to adjacent short sections to provide shortened axial extent portions respectively adjacent to the short sections of the cage  2  and longer axial extent portions respectively adjacent to the long sections of the cage  2 . In  FIG. 3 , the chambers  4 ,  4 ′ for receiving the damping agent can be recognized in the view. The chambers  4 ,  4 ′ show, as can be clearly recognized here, a special geometry for accomplishing the object of the present invention. An undercut  5 ,  5 ′,  6 ,  6 ′ each, extending in the direction of the bearing axis  14 , is formed in the area of their axial ends. The inner and outer chamber walls pass over at the axial ends of the chambers from a shape or section  7  following the bearing axis essentially in parallel into a section  8 ,  8 ′,  9 ,  9 ′ having a shape sloped against the bearing axis  14  (and generally following the upper and lower surfaces of the bearing body  3 ). The chambers  4  and  4 ′ are in the shortened axial extent portions, in the region of the axially shorter sides of the inner cage  2 . It can be recognized that the shape of the respective outer chamber wall  10 ,  10 ′ follows essentially the inner chamber wall in the exemplary embodiment being shown. The improved stability of the bearing in respect to cardanic loads is achieved in case of vertical installation due to the formation of the undercuts  5 ,  5 ′,  6 ,  6 ′. The axially middle areas of the chambers  4 ,  4 ′ advantageously form stop faces  15 ,  15 ′ (see  FIG. 4 ). With this design, the bearing can absorb cardanic loads with a cardanic angle of ±20° without problems. 
   As it becomes apparent from  FIG. 4  in connection with  FIG. 1 , chamber openings ( 13 ,  13 ′), which are arranged at right angles to the direction of load that is given in case of a vertical installation position, are formed due to the shape of the contour of the inner chamber walls and of the outer chamber walls  10 ,  10 ′ with an expansion of the chambers  4 ,  4 ′ in the outer areas of their circumferential extension. To complement the bearing, a channel carrier element  18 , which is shown in  FIG. 5  only, is clipped into the recesses  17  recognizable in  FIG. 1  during the manufacture of the bearing, so that the chambers  4 ,  4 ′ are connected by the channel  12  formed in them in such a way that they conduct flow and the damping agent can flow to and fro between the chambers  4 ,  4 ′ during loading of the bearing. However, a corresponding channel  12  may also be vulcanized into the elastomeric bearing body  3 . A separate channel carrier is dispensable in this case. The bearing according to the present invention may be mounted in the exemplary embodiments shown in  FIGS. 1 through 4  either directly at a corresponding point determined by its intended use or also surrounded by an additional outer sleeve  11 , preferably one made of metal. The latter is illustrated once again in  FIG. 5 , again in a three-dimensional view, the bearing being shown with a partial section in the outer sleeve  11 . The inner part  1  of the bearing has, as can be recognized in  FIGS. 1 and 5 , a flattened area  16 ,  16 ′ in the areas of the respective chambers  4 ,  4 ′. 
   While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.