Abstract:
A sealing arrangement ( 14   a ) on an axial roller bearing ( 10 ) which includes two race rings ( 12, 13 ) with rolling elements ( 4 ) guided therebetween, the sealing arrangement ( 14   a ) sealing off a rolling element chamber ( 16 ) of the axial roller bearing ( 10 ). The sealing arrangement ( 14   a ) has, as reinforcement, a rotationally symmetrical reinforcing sleeve ( 15   a ) that externally encloses both race rings ( 12, 13 ), the sealing arrangement ( 14   a ) being fixed in position by at least one securing section ( 20   a ), and some sections of the reinforcing sleeve ( 15 ) being covered by or connected to an elastic sealing material ( 17 ), in a connected manner, in sealing sections ( 19   a,    19   b ) of said sealing arrangement ( 14   a ).

Description:
BACKGROUND 
       [0001]    The invention relates to an axial roller bearing including two ball races between which roller bodies guided in a roller body cage are arranged, and the axial roller bearing is enclosed on the outside by a sealing arrangement for sealing a roller body space. 
         [0002]    Axial roller bearings that are also called longitudinal or compression bearings take on forces in the longitudinal direction of the shaft or axle and are known in many different embodiments. In motor vehicle wheel suspension systems, typically axle journals are used to attach steerable wheels to an axle body of the chassis in a pivoting manner. The connection between the axle journal and the axle body is realized by an axle journal pin that is inserted into corresponding holes of the axle journal and the axle body. Axial forces between the axle journal and the axle body are transmitted via an axial roller bearing mounted on the axle journal pin. An effective seal is required over the service life of the axial roller bearing and for the axial roller bearing to function. This seal prevents, on one side, a discharge of lubricant out of the bearing and, on the other side, the penetration of contaminants into the axial roller bearing. This seal is provided, in particular, for axial journal bearings in which the lubricant remains permanently in the bearing without the need for relubrication. Relubrication could also be provided for axial journal bearings, wherein the bearing is filled with lubricant until there is visible discharge in the area of the seal. 
         [0003]    DE 21 02 656 A shows the use of an axial roller bearing in an axle journal bearing of a vehicle axle. An axle body is here supported by means of an axial roller bearing on a lower mount of the fork-shaped end of an axle journal and enables rotation of the axle journal. The upper ball race of the axial roller bearing is arranged in a pot-shaped housing whose sleeve-shaped edge surrounds the lateral surface of the lower washer with clearance. Between an inclined face of the lower ball race and the end face of the lower mount of the fork-shaped end of an axle journal forming the contact face for the lower ball race, a sealing ring with a bead-shaped section is fixed in place. An elastic ring part extends starting from the bead into the space between the sleeve-shaped part and the circumferential surface of the ball race. At the same time, the roller body space or the bearing interior of the axial roller bearing is sealed by the elastic ring part. 
       SUMMARY 
       [0004]    The invention is based on the object of creating a component-optimized sealing arrangement in a simple, compact construction for an axial roller bearing with an improved retaining function and high sealing quality, wherein this arrangement can be produced in a cost-effective manner. 
         [0005]    This objective is achieved by one or more features of the invention. The claims also provide advantageous refinements of the invention. The sealing arrangement according to the invention and designed for an axial roller bearing comprises, as reinforcement, a rotationally symmetric reinforcing sleeve that is connected in some areas with a material fit connection to an elastic sealing material. In the installed state, the rotationally symmetric reinforcing sleeve encloses two ball races of the axial roller bearing, wherein the sealing arrangement can be fixed in position on a ball race by at least one fastening section, preferably constructed as an interference fit. 
         [0006]    Through the direct material fit connection of the sealing material on the reinforcing sleeve, the components are connected integrally to each other, which produces a desired one-piece construction of the sealing arrangement. By means of the sealing material preferably cured or attached by an adhesive to the reinforcing sleeve, sealing sections can be realized. The sealing material can have a special construction or shape according to the invention or can be supported in a sealing manner on the ball races in connection with the reinforcing sleeve, in order to effectively seal the roller body space of the axial roller bearing. 
         [0007]    Through the measures according to the invention, such as the defined retaining function of the reinforcing sleeve, due to the direct connection to the sealing material, an exact installed position of the sealing sections is produced at the same time. This effect is advantageous with respect to the sealing quality relative to previously known two-part sealing arrangements in which the sealing ring was inserted with a certain degree of freedom relative to a sleeve surrounding the axial roller bearing on the outside. The simple component-optimized, compact construction of the sealing arrangement according to the invention also can be produced in a cost-effective way and easily assembled. 
         [0008]    According to a preferred construction of the invention, it is provided that a fastening section of the sealing arrangement is formed in which an end zone of the reinforcing sleeve is fixed in place on a diagonal or inclined outer contour of a ball race. Alternatively or additionally, the invention includes a fastening section that is formed in connection with the sealing material of the reinforcing sleeve. For this purpose, a bead formed by the sealing material and extending over the reinforcing sheet is supported in the installed state on the inclined outer contour of a roller bearing ball race. 
         [0009]    The construction of the sealing arrangement according to the invention further comprises a reinforcing sleeve that is supported with a non-positive connection on a ball race of the axial roller bearing for forming a first sealing section by means of the elastic sealing material. For this purpose, the reinforcing sleeve encloses the ball race in a pretensioned way with a non-positive connection. A second sealing section interacting with the other ball race forms a sealing lip that is formed from the sealing material and is supported on the ball race in a sealing manner. 
         [0010]    Advantageously, the invention offers the ability to directly join the two ball races of the axial roller bearing over the sealing arrangement with the help of the fastening sections. All parts of the roller bearing are thus held captively and form a unit that can be preassembled and simplifies, for example, automated assembly. For achieving an unimpaired relative motion between two ball races, it is provided that a fastening section is fixed in place with clearance relative to the inclined outer contour of a ball race. 
         [0011]    Another construction of the sealing arrangement according to the invention includes a stabilization section for the reinforcing sleeve. This comprises a circumferential or partially circumferential step that is oriented axially in the roller body space and can also be constructed as a bead. In one preferred position, the stabilization section is supported in the installed state with a positive fit connection on an inner zone of a ball race. In this way, at the same time a sealing zone can be created in which the stabilization section forms a sealing contact on the ball race by the sealing material. 
         [0012]    The reinforcing sleeve of the sealing arrangement is preferably completely covered on one side with the sealing material in the area of the fastening sections, the sealing sections, and the stabilization section. Alternatively, the reinforcing sleeve could have a sealing material completely on one side, wherein this sealing material is fixed to the inside of the reinforcing sleeve with a material fit, in particular, by curing or adhesion. 
         [0013]    As the material for the reinforcing sleeve, according to the invention preferably a sheet material is used from which, in a non-cutting process, in particular, by a deep-drawing method, the reinforcing sleeve could also be produced economically in large quantities. For this purpose, in particular, a corrosion-resistant steel sheet with a thickness greater than 0.3 mm, preferably 0.6 mm, and less than 1.0 mm is suitable. 
         [0014]    According to another construction of the invention, the invention includes a mounting aid. For this purpose, the reinforcing sleeve can comprise, for example, several symmetrically arranged, radially outward directed journals distributed circumferentially. The journals can be used to simplify the assembly of the sealing arrangement with the help of a tool. 
         [0015]    For the sealing arrangement, a rubber-like elastomer is provided as a suitable elastic sealing material according to the invention, for example, NBR or EPM (ethylene-propylene-rubber). This synthetic material is distinguished by a high temperature resistance, wherein the permanent elasticity remains nearly unchanged over the entire temperature range from −40° to +50° in which motor vehicles are operated. 
         [0016]    Preferably the axial roller bearings sealed according to the invention are used in steering axles of motor vehicles, in particular, commercial vehicles. Here, in the installed state, an axle body is supported by the axial roller bearing on an axle journal that can be pivoted about an axle journal pin. 
     
    
     
       BRIEF DESCRIPTION OF THE CLAIMS 
         [0017]    Additional features of the invention are given in the following description and from the drawings in which an embodiment is shown in a simplified form. The invention is not limited to this embodiment. If not mentioned otherwise, components that are identical or that have identical functions are provided with identical reference numbers in the description. Shown are: 
           [0018]      FIG. 1  a cross-section of a vehicle steering axle in which an axle body is supported by an axial roller bearing on an axle journal, 
           [0019]      FIG. 2  schematically, an axial roller bearing with a first embodiment of a sealing arrangement according to the invention, 
           [0020]      FIG. 3  schematically, an axial roller bearing with a second embodiment of a sealing arrangement according to the invention, and 
           [0021]      FIG. 4  schematically, an axial roller bearing with a third embodiment of a sealing arrangement according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    In  FIG. 1 , a cut-out of a wheel suspension system  1  is shown for a steerable front wheel of a motor vehicle. An axle journal  2  together with associated wheel bearing  3 , wheel hub, and not-shown vehicle wheel are supported so that they can pivot relative to an axle body  5 . The axle journal  2  and the axle body  5  are connected to each other so that they can pivot by an axle journal pin  6 . The axle journal pin  6  fitted in the axle body  5  is supported so that it can rotate by a bearing  7 , for example, a plain bearing, in an upper mount  9   a  and also by two needle bearings  8   a,    8   b  in the lower mount  9   b  of the axle journal  2 . The axle body  5  is supported by an axial roller bearing  10  through which the axle journal pin  6  is guided on a projection of the lower mount  9   b  of the axle journal  2 . An upper ball race  12  of the axial roller bearing  10  is here allocated to the axle body  5  and a lower ball race  13  is allocated to the axle journal  2 . Between the ball races  12 ,  13 , roller bodies  4  preferably inserted in a roller body cage are guided. On the outside, the axial roller bearing  10  is enclosed by a sealing arrangement  11  that protects a roller body space  16  from contaminants penetrating from the outside into the roller bearing  10  and also from the loss of lubricant. 
         [0023]    In  FIG. 2  to  FIG. 4 , sealing arrangements  14   a,    14   b,    14   c  with different constructions are shown in connection with the schematically shown axial roller bearing  10  of which the ball races  12 ,  13  are shown. 
         [0024]    The sealing arrangement  14   a  according to  FIG. 2  is comprised of a reinforcing sleeve  15   a  forming reinforcement, which surrounds the two ball races  12 ,  13  of the axial roller bearing  10  on the outside. The reinforcing sleeve  15   a  is in active connection with the ball races  12 ,  13  by sealing sections  19   a,    19   b  and also a fastening section  20   a.  On the inside, the reinforcing sleeve  15   a  is covered with a sealing material  17  up to an axial contact on the ball race  12 . A first sealing section  19   a  is formed by the stabilization section  18  that is supported indirectly by the sealing material  17  on an axial inner wall  21  of the ball race  12 . A sealing lip  22  starting from the stabilization section  18  and supported with a non-positive connection on the inner wall  23  of the ball race  13  forms the second sealing section  19   b.  Between the ball races  12 ,  13 , the reinforcing sleeve  15   a  forms a stabilization section  18  that improves the stiffness of the sleeve  15   a  and is formed as a rectangular step oriented toward the roller body space  16  of the axial roller bearing  10 . One end of the reinforcing sleeve  15   a  allocated to the ball race  13  is provided as a fastening section  20   a  that contacts, in its end position, an inclined outer contour  24  of the ball race  13  by a shaping or fixing process. As a measure for sealing the produced annular gap  25  relative to the ball race  13 , the sealing material  17  forms a sealing lip  26  spread out relative to the ball race  13 . 
         [0025]    The axial roller bearing  10  can be completed with the sealing arrangement  14   a  according to  FIG. 2  in subsequent mounting steps. The reinforcing sleeve  15   a  is initially shifted until it contacts the stabilization section  18  on the ball race  12 . The inner diameter of the reinforcing sleeve  15   a  and the outer diameter of the ball race  12  can be selected so that when these parts are joined, a transition or interference fit is produced. Then the roller bodies  4  are allocated with or without the roller body cage to the ball race  12  before the other ball race  13  is set axially into the reinforcing sleeve  15   a.  Finally the fastening section  20   a  is fixed in place contacting the inclined outer contour  24  of the ball race  13 . Alternatively, a sealing arrangement  14   a  can be used in which, after successful mounting of the stabilization section  18 , for example, by a radially fed shaping tool, it is shaped into the reinforcing sleeve  15   a.    
         [0026]      FIG. 3  shows the sealing arrangement  14   b  that differs from the sealing arrangement  14   a  according to  FIG. 2  by a differently shaped fastening section  20   b.  A bead  27  that is formed by the sealing material  17  and forms the fastening section  20   b  and is in active connection with the inclined outer contour  24  of the ball race  13  connects to the lower end of the reinforcing sleeve  15   b.    
         [0027]    In  FIG. 4 , the sealing arrangement  14   c  is shown whose reinforcing sleeve  15   c  does not include a stabilization section. The fastening section  20   b  of the sealing arrangement  14   c  interacting with the ball race  13  matches the design according to  FIG. 3 . Another fastening section  20   c  of the sealing arrangement  14   c  connected to the ball race  12  is comparable to the fastening section  20   a  shown in  FIG. 2 . The fastening section  20   c  is formed by the end of the reinforcing sleeve  15   c  that is allocated to the ball race  12  and corresponds to an inclined outer contour  28  of the ball race  12  through shaping in its end position. To seal the annular gap  29  relative to the ball race  12 , the sealing material  17  forms a sealing lip  30  spread out relative to the ball race  12 . Additionally or alternatively, for creating an effective seal it is possible for the reinforcing sleeve  15   c  to be statically sealed in the contact area of the ball race  12  first by the elastic sealing material  17  and then for the reinforcing sleeve  15   c  to contact directly on the outer contour of the ball race  12 . For the sealing arrangement  14   c,  a mounting aid  31  could also be provided. For this purpose, the reinforcing sleeve  15   c  preferably comprises multiple journals that are directed radially outward and by which the sealing arrangement  14   c  can be easily mounted, for example, in connection with a separate tool. 
       LIST OF REFERENCE NUMBERS 
       [0028]      1  Wheel suspension 
         [0029]      2  Axle journal 
         [0030]      3  Wheel bearing 
         [0031]      4  Roller body 
         [0032]      5  Axle body 
         [0033]      6  Axle journal pin 
         [0034]      7  Bearing 
         [0035]      8   a  Needle bearing 
         [0036]      8   b  Needle bearing 
         [0037]      9   a  Receptacle 
         [0038]      9   b  Receptacle 
         [0039]      10  Axial roller bearing 
         [0040]      11  Sealing arrangement 
         [0041]      12  Ball race 
         [0042]      13  Ball race 
         [0043]      14   a  Sealing arrangement 
         [0044]      14   b  Sealing arrangement 
         [0045]      14   c  Sealing arrangement 
         [0046]      15   a  Reinforcing sleeve 
         [0047]      15   b  Reinforcing sleeve 
         [0048]      15   c  Reinforcing sleeve 
         [0049]      16  Roller body space 
         [0050]      17  Sealing material 
         [0051]      18  Stabilization section 
         [0052]      19   a  Sealing section 
         [0053]      19   b  Sealing section 
         [0054]      20   a  Fastening section 
         [0055]      20   b  Fastening section 
         [0056]      20   c  Fastening section 
         [0057]      21  Inner wall 
         [0058]      22  Sealing lip 
         [0059]      23  Inner wall 
         [0060]      24  Outer contour 
         [0061]      25  Ring gap 
         [0062]      26  Sealing lip 
         [0063]      27  Bead 
         [0064]      28  Outer contour 
         [0065]      29  Ring gap 
         [0066]      30  Sealing lip 
         [0067]      31  Mounting aid