Abstract:
An elastic bearing bush, particularly for use in a chassis of a motor vehicle, has a housing, a core disposed inside the housing, and an elastomer body connecting the housing to the core. The bearing bush has different damping properties in a first spatial direction and a second spatial direction. The bearing bush has a substantially rectangular base surface. The spring and damping properties are determined in the first spatial direction by at least one air spring element and in the second spatial direction by at least one elastomer spring.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a continuing application, under 35 U.S.C. §120, of copending international application No. PCT/EP2008/053117, filed Mar. 14, 2008, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent application No. DE 10 2007 015 239.8, filed Mar. 29, 2007; the prior applications are herewith incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The present invention relates to an elastic bearing bush having an essentially rectangular base, in particular for use in a chassis of a motor vehicle, containing a housing, a core disposed inside the housing, and an elastomer body connecting the housing to the core. The bearing bush has different springing and damping properties in a first spatial direction and a second spatial direction. 
         [0003]    Such bearing bushes are often used as chassis bushes. For such bearing bushes it is often necessary, that they have different springing and damping properties in different spatial directions. Their use in a chassis makes it necessary, for example, that they have very high stiffness in the vehicle transverse direction, while a substantially smaller stiffness is sufficient in the vehicle longitudinal direction. 
         [0004]    To achieve this, in European patent EP 1 056 962 B1 (corresponding to U.S. Pat. No. 6,378,853), an essentially cylindrical rubber bearing is suggested, wherein the elastomer body varies in its thickness, or has recesses, in the circumferential direction. An inner portion, by which the elastomer body is supported, has its largest radial extension in the area of the recesses. Further, the rubber bearing has channels in its edge area, which allow air to be vented or a liquid damping to be passed from a recess to a respective opposing recess. 
         [0005]    German patent DE 1 159 704 B discloses an elastic bush, wherein a core is supported in a housing via two elastomer bodies abutting against each other. The elastomer bodies have slots which are to enable an axial sliding moveability. 
         [0006]    Published, non-prosecuted German patent application DE 102 00 764 A1 discloses an air spring bearing including a housing with a square basic shape. A core is supported at the housing via an elastomer body having webs. The elastomer body forms four so-called dynamic chambers. The chambers are filled with air or nitrogen, for example. The air can escape from the chambers via a throttle opening. 
       SUMMARY OF THE INVENTION 
       [0007]    It is accordingly an object of the invention to provide an elastic bearing bush which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which has damping properties which are easily adjustable and which can be cheaply and easily manufactured. 
         [0008]    With the foregoing and other objects in view there is provided, in accordance with the invention an elastic bearing bush. The bearing bush contains a housing, a core disposed within the housing, at least one air spring element, at least one elastomer spring, and an elastomer body connecting the housing to the core. The bearing bush has a generally rectangular base. The bearing bush has different springing and damping properties in a first spatial direction and a second spatial direction. The springing and damping properties in the first spatial direction are determined by the at least one air spring element and in the second spatial direction by the at least one elastomer spring. 
         [0009]    To solve this problem, a bearing bush of the initially mentioned type is suggested, which has an essentially rectangular base, wherein the springing and damping properties in the first spatial direction are determined by the least one air spring element and in the second spatial direction are determined by the elastomer spring. 
         [0010]    The bearing bush according to the present invention has the advantage that the springing and damping properties in different spatial directions are determined by respective individually adjustable spring elements. The individual spring elements in turn are easily to dimension and to manufacture. Due to the rectangular base of the bearing bush it is particularly easy to arrange an air spring element in the bearing bush, which has a large pump diameter. 
         [0011]    Advantageously, the long sides of the housing have at least one air spring element associated with them, and the short sides of the housing have at least one elastomer spring associated with them. This has the advantage that the air spring element can have a large pump surface. In combination with a small volume of the air spring element, excellent damping properties can thus be achieved. 
         [0012]    The air spring element can be formed in the first spatial direction between the core and the housing. 
         [0013]    The at least one air spring element has preferably a throttle opening connecting a hollow chamber of the air element with the ambient. 
         [0014]    Further, the elastomer spring can be formed as a stud arranged between the core and the housing. 
         [0015]    It can also be advantageously provided that the bearing bush has two air chambers whose cavities are connected with each other by a channel. 
         [0016]    Advantageously, the channel is formed in a channel shell. 
         [0017]    Furthermore, the channel can advantageously be integrated in the core. By these measures, the number of individual components can be reduced and assembly of the bearing bush can be further simplified. 
         [0018]    In an advantageous embodiment, the bearing bush is subdivided in the horizontal direction and has two half bushes. This is to ensure simple manufacture of the bearing bush. 
         [0019]    The half bushes can advantageously have an identical structure. For this reason, the bearing bushes can be manufactured of identical components. 
         [0020]    Advantageously, the elastomer bodies of the half bushes can have air pockets which, in the assembled state of the half bushes, form the hollow chambers of the air spring elements. An additional structure for closing the hollow chambers can thus be omitted. 
         [0021]    The elastomer bodies of the half bushes, in the assembled state, preferably close the hollow chambers of the half bushes in an air-tight manner. Additional sealing devices can thus be omitted, which makes production simpler and cheaper. 
         [0022]    The bearing bush can advantageously have at least one attachment flange. Simple attachment of the bearing bush in a motor vehicle is thus ensured. 
         [0023]    Preferably, it can be provided that the elastomer body forms a stop on the attachment flange. The stop simplifies the attachment of the bearing bush. 
         [0024]    The core can advantageously have an attachment opening. 
         [0025]    Advantageously, it is provided that the elastomer body is inserted between the core and the housing before curing. This ensures secure attachment of the elastomer body on the core and housing. 
         [0026]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0027]    Although the invention is illustrated and described herein as embodied in an elastic bearing bush, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0028]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0029]      FIG. 1  is a diagrammatic, perspective, partially cut-away view of a bearing bush according to a first embodiment of the present invention, wherein a vertical section in a longitudinal and transverse direction is carried out starting from a center of an attachment opening; 
           [0030]      FIG. 2  is a horizontal sectional view of the bearing bush of  FIG. 1 ; 
           [0031]      FIG. 3  is a section view through the bearing bush taken along the line III-III shown in  FIG. 2 ; 
           [0032]      FIG. 4  is a diagrammatic, horizontal sectional view of a channel shell according to a second embodiment of the present invention; 
           [0033]      FIG. 5  is a vertical sectional view of the bearing bush according to the second embodiment; and 
           [0034]      FIG. 6  is a horizontal sectional view of the bearing bush according to a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a bearing bush  10  that has a housing  18  having an essentially rectangular basic shape, which is formed with an attachment flange  20 . The housing  18  is of metal sheet. A core  22  of metal is arranged in an interior of the housing. Extruded aluminum can be used, for example, to manufacture the core  22 . The core  22  is connected with the housing  18  by an elastomer body  24 . 
         [0036]    The elastomer body  24  is inserted between the core  22  and the housing  18  before curing, so that there is a frictional engagement between the elastomer body  24  and the housing  18 , and the core  22 . 
         [0037]    The bearing bush  10  is composed of two half bushes  12 ,  14  abutting each other on a contact plane  16  and having an identical structure. 
         [0038]    As can be seen, in particular, from  FIG. 2 , air spring elements  26   a ,  26   b  are disposed along longitudinal sides  19   a ,  19   b  of housing  18 . The air spring elements  26   a ,  26   b  each have a hollow chamber  28 . The hollow chamber  28  is filled with air in the present embodiment. The hollow chamber  28  of the air spring elements  26   a ,  26   b  communicates with the ambient via a throttle channel  34 , as can be seen from  FIG. 3 . 
         [0039]    Between end faces  17   a ,  17   b  of the core  22  and the housing  18 , the elastomer body  24  has an elastomer spring  30  formed as a stud. Further, the elastomer body  24  has stops  32  along the attachment sides of the attachment flanges  20 , as can be clearly seen from  FIGS. 1 and 3 . 
         [0040]    A throttle opening  34  is formed in the housing  18 , which extends through the elastomer body  24  and the housing  18  up to the outer side wall of the bearing bush  10 . 
         [0041]    Further, the core  22  has a circular attachment opening  36 . 
         [0042]    To construct the bearing bush  10 , two identical half bushes  12 ,  14  are assembled at their contact planes  16  and fixed in a holder so that the two half bushes  12 ,  14  are securely held together. The force pressing the half bushes  12 ,  14  together closes the elastomer bodies  24  of the half bushes  12 ,  14  in an airtight manner. The parts of the core  22  are assembled with a slight bias. 
         [0043]    As seen in  FIG. 3 , each half bush  12 ,  14  has air pockets  38  at its long sides. When the bearing bush  10  is assembled, a hollow chamber  28  is created by two respective air pockets  38  by assembling the elastomer bodies  24  in an airtight manner. 
         [0044]    For assembly, the bearing bush  10  with the housing  18  is pressed into an auxiliary frame, for example. A section of the vehicle chassis is then passed through the attachment opening  36  of core  22  and securely connected to it. The core  22  is thus attached on a part of the vehicle. 
         [0045]    The bearing bush  10  is aligned in such a way that the air spring elements  26   a ,  26   b  are associated with the longitudinal direction x of the vehicle and the elastomer springs  30   a ,  30   b  are associated with the transverse direction y of the vehicle. 
         [0046]    The bearing bush  10  has different springing and damping properties in each of the x and y spatial directions. In the first spatial direction x, the damping properties are determined by the air spring elements  26   a ,  26   b , which have a damping characteristic which becomes disproportionally stiffer as the vibrating amplitude increases. In the second spatial direction y, elastomer springs  30   a ,  30   b  lead to high stiffness in the transverse direction of the vehicle. 
         [0047]    The arrangement of the air spring elements  26   a ,  26   b  along the longitudinal sides  19   a ,  19   b  of the bearing bush  10  causes a large pump cross section of the hollow chamber  28  with an otherwise small hollow chamber volume. 
         [0048]    To handle low frequency vibrations and static displacements of the core  22  with respect to the housing  18 , the throttle openings  34  are formed in such a way that they enable comparatively slow pressure compensation of the hollow chamber  28  with the ambient atmosphere. 
         [0049]      FIG. 5  shows a further embodiment of the bearing bush  10 , wherein for its description the above reference numerals will be used for the same or equivalent parts. The bearing bush  10  has a channel shell  40 , which is shown in  FIG. 4 . The channel shell  40  has an attachment opening  36  in alignment with the attachment openings  36  of cores  22 . A channel  42  is provided in channel shell  40  and extends from one long side  41   a  of channel shell  40  to the opposite long side  41   b.    
         [0050]    The channel shell  40  is arranged between the half bushes  12 ,  14  so that a communicating channel between the hollow chambers  28  of air spring elements  26   a ,  26   b  results through channel  42 . 
         [0051]    In a third embodiment as shown in  FIG. 6 , the channel  42  extends through the core  22 . For this purpose it is also necessary to provide through openings  44  in the elastomer body  24  to connect the hollow chambers  28  by the channel  42 . 
         [0052]    The shape of the hollow chambers  28  can be determined by simple changes in the geometry of the elastomer body  24 . The damping properties of the air spring elements  26   a ,  26   b  can thus be simply and cheaply adjusted. 
         [0053]    Moreover, manufacturing the half bushes  12 , 14  with air pockets  38  is simpler than manufacturing an elastomer spring  24  with a hollow chamber  28  contained therein. 
         [0054]    The bearing bush  10  according to the present invention, which is composed of two half bushes  12 , 14  and which has different springing and damping properties due to air spring elements  26   a ,  26   b  and elastomer studs  30  in the spatial directions x and y, has a simple structure and can therefore be cheaply manufactured.