Abstract:
The invention relates to a wheel bearing arrangement which enables a hub to be mounted in at least one non-rotating external ring such that it can rotate about the rotational axis of the hub. The wheel bearing arrangement comprises at least one sealing arrangement and one encoder and the sealing arrangement is secured to the hub side on the side of the wheel bearing arrangement whereon a radial flange extends in a radial manner from the hub. The encoder is actively connected to the sealing arrangement.

Description:
FIELD OF THE INVENTION 
     The invention relates to a wheel bearing arrangement comprising a hub mounted rotatably about the rotational axis of the hub in at least one non-rotating outer ring, the wheel bearing having an encoder, and the encoder being fixed to that side of the wheel bearing arrangement at the hub side, from which side a radial flange leads radially away from the hub and the encoder being operatively connected to the sealing arrangement. 
     BACKGROUND OF THE INVENTION 
     A wheel bearing arrangement of this type is described in U.S. Pat. No. 4,864,231. The vehicle wheel is, as a rule, fastened to the radial flange of the hub by way of bolts. In this case, the radial flange is configured integrally with the hub. 
     The wheel bearing is as a rule a roller bearing having two or more rows of rolling bodies. Inner rings having the raceways for the rows are seated optionally on the hub. At least one raceway of two or more of the rows of rolling bodies is optionally incorporated directly into the material of the hub. The wheel bearing has one or more outer rings, on which the inner raceways for the rows are formed. The outer rings are either seated in the wheel support, or the outer ring is, as in the underlying prior art, the wheel support itself. The wheel support is provided with a flange, which has, for example, a plurality of fastening holes, for fastening the wheel support on the vehicle side. The outer ring is accordingly fixed in terms of rotation. The hub and therefore the vehicle wheel are mounted in the wheel bearing so as to rotate with respect to the wheel support. 
     The wheel bearing is, as a rule, sealed with two seals against environmental influences from the outside. One of the seals protects the wheel bearing as well as the encoder and at the same time has a sealing operative connection to the encoder. To this end, the seal has a sealing element in the form of a covering plate which is seated on the outer ring. One sealing lip on the covering plate bears sealingly against the encoder. 
     The sensor system is often arranged on the side of the radial flange, as the installation space on the vehicle side between the articulation bell and the wheel carrier is small for passing through the connecting lines of the sensor system and as the sensor system is exposed sometimes, to extreme contaminations at this location. The expenditure for sealing the wheel bearing and for simultaneously protecting the sensor system is therefore relatively high. The connecting lines are endangered by mud or ice accumulations on the side of the articulation bell. 
     However, in contrast, little installation space is available on the side of the vehicle wheel for the sensor system, for the components seal, encoder and sensor/sensors per se. In addition, the heads/threaded ends of the bolts which protrude axially out of the radial flange for fastening the wheel project in a disruptive manner into the installation space and also influence the signals of the sensor system by interfering signals. 
     The encoder is seated directly on the hub by means of a press fit and rotates with the latter relative to the sensor. In the arrangement according to U.S. Pat. No. 4,864,231, the sensor which belongs to the sensor system is held in a hole of the wheel carrier and protrudes through the hole into the interior of the wheel bearing. The seat of the sensor in the outer ring is to be manufactured and sealed separately and therefore causes additional costs. During the mounting of the sensor, and also during repair and maintenance, there is the risk that dirt particles pass into the interior of the roller bearing during insertion of the sensor. Those sealing lips of known sealing arrangements which lie on the outside of wheel bearing arrangements are, as a rule, directly exposed to environmental influences and fail prematurely. Dirt and moisture pass under the seal and penetrate into the roller bearing. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide a wheel bearing arrangement, with which the above-described disadvantages are avoided. In particular, a simple and inexpensive sealing arrangement having an integrated encoder is to be provided. Furthermore, sufficient installation space for the sealing arrangement and the encoder is to be provided on the wheel flange side. 
     This object is achieved in that:
         the wheel bearing arrangement of the invention has a gap seal on that side of the wheel bearing which faces the radial flange, there being an operative connection in the gap seal between the encoder and a sealing element. The gap seal is formed by at least one sealing gap which extends around the rotational axis between the encoder and a sealing element of the sealing arrangement,
 
or optionally in that:
   the encoder which is fixed on the huh side surrounds contact-free an annular section of the outer ring in a circumferential manner radially on the outside,       

     or as an alternative:
         by a combination of the preceding features.       

     Additional installation space for the wheel-side sealing of the wheel bearing and for the sensor system is provided by a wheel bearing arrangement of this type. The encoder is sufficiently protected by the seal. The sensor is arranged in a spatially separate manner from the interior of the wheel bearing. The bearing arrangement and, particularly, the sealing arrangement can be manufactured inexpensively, in particular, when the covering plate and the sensor with the carrier are cold-formed sheet metal parts. The encoder and the sensor are arranged far enough away from the interfering influences of the wheel bolts on the sensor signals. The active surface of the encoder (the encoding section which communicates with the sensor) can be of generous configuration in a manner which is free and independent of the dimensions of the axial installation space between the end side of the wheel bearing and the radial flange. The quality of the signals is improved. The axial installation space therefore can be used for the design of the sealing arrangement according to the invention with sufficient sealing action. 
     The invention is suitable for the use of all conceivable magnetized encoders (with changing polarity), such as pulse generators having magnetized particles in elastomers, or for the use of nonmagnetized encoders, such as pulse generator rings made from sheet metal. The protective sleeve, optionally also made from plastic, is preferably a protective plate made from nonferromagnetic material. The encoder is protected against stone chipping or other hard particles. Spray water and ferromagnetic particles from the surroundings are kept away by the protective sleeve. 
     The dimension of the gap of the gap seal is smaller than or at most equal to one millimeter. The corresponding orientation of the protective sleeve and the position of the sealing gap ensure that fluid which has penetrated via the gap into the interior of the seal drips out of the gap or is conveyed through the gap to the outside during operation as a result of centrifugal force on the rotating encoder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Refinements and exemplary embodiments of the invention are explained in greater detail in the following text. 
         FIG. 1  shows perspective view of one exemplary embodiment of a wheel bearing arrangement which is sectioned along the rotational axis  1   a;    
         FIG. 1   a  shows a segment of an encoder of the wheel-flange-side sealing arrangement from the wheel bearing arrangement according to  FIG. 1 ; 
         FIG. 2  shows a partial view of a radial-flange-side sealing arrangement of the wheel hearing arrangement which is sectioned along the rotational axis; 
         FIGS. 3 and 4  show radial-flange-side sealing arrangements partially in illustrations sectioned along the rotational axis; and 
         FIGS. 5-7  show alternative sealing arrangements in the wheel bearing arrangement. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show a wheel bearing arrangement  1  with a radial flange  2  and a wheel support  5 . The radial flange  2  is configured integrally with a hub  6  and is mounted in the wheel support  5  such that it can rotate about the rotational axis  1   a . The wheel bearing is formed from two rows of rolling bodies  10 , an inner ring  11 , optionally two inner rings, two raceways  12  and  13  and an outer ring  18  which has two raceways  14  and  15  in the form of the wheel support  5 . The raceway  12  is formed on the inner ring  11  and the other raceway  13  is formed directly on the hub  6 . The hub  6  with the radial flange  2  is mounted rotatably in the wheel support  5  via the two rows of rolling bodies  10 . A vehicle wheel (not shown) is fastened to the radial flange  2  by way of the wheel bolts  16 . 
     Furthermore, the wheel bearing arrangement  1  has a sealing arrangement  27  with a protective sleeve  7  from a nonferromagnetic sheet, with an elastic seal  8  and with an encoder  9 . At least one sensor  17  lies opposite the encoder  9 . The encoder  9  and the sensor  17  are separated from one another by the protective sleeve  7 . 
     The encoder  9  is shown partially as an individual part in  FIG. 1   a  and is a component which is cold-formed from sheet metal comprising a support  9   b  with a collar  9   c  and the encoding section  9   a  which communicates with the sensor  17  for signal generation. The encoding section  9   a  is constructed for alternating signals, in this case wave-shaped, in such a way that peaks  9   e  alternate with trough bottoms  9   f  in the circumferential direction and with an identical pitch with respect to one another. 
     It is also conceivable that, as shown in  FIG. 3 , the sealing arrangement  3  has an encoder  21 , the encoding section  21   a  of which, which communicates with the sensor  17 , is a hollow-cylindrical section having window-like radial apertures  21   b . The apertures  21   b  are separated from one another in the circumferential direction by webs  21   c  of identical dimensions and are arranged with a uniform pitch with respect to one another. 
     As an alternative,  FIG. 4  shows an encoder  22 , the encoding section  22   a  of which, which communicates with the sensor  17  for signal generation, is substantially a body made from elastomer with multipolar magnetized additives. 
     The encoder  9  is fixed on the inner ring  11  by a press fit of the collar  9   c  on the support  9   b  and is therefore fixed on the hub side. The encoding section  9   a  of the encoder  9  which is relevant for the signal generation of the sensor  17  extends, from the support  9   b , axially away from the radial flange  2  in the direction of the wheel support  5  and reaches over the latter at the annular section  5   a . The encoder  9  surrounds the annular section  5   a  of the outer ring  18  or of the support  5  without contact, by way of the communicating encoding section  9   a.    
     In this case, the projections  16   a  of the wheel bolts  16  are the heads of the wheel bolts  16  and they protrude axially from the radial flange  2 . The communicating encoding section  9   a  is spaced radially apart from the projections and is not protruded beyond axially. The radial spacing of the projections from the hub  6  is greater than the radial spacing of the radially outermost body edge of the encoding section  9   a  from the hub  6 . 
     The protective sleeve  7  is cup-shaped, cold-formed from sheet metal and nonferromagnetic. A first hollow-cylindrical section  7   a  of the protective sleeve  7  which lies radially on the outside covers the encoder  9  from the outside against environmental influences. A second hollow-cylindrical section  7   b  which is formed integrally with the first section  7   a  is seated fixedly on the annular section  5   a  of the outer ring  18 , with the result that the protective sleeve  7  is fixed in terms of rotation together with the outer ring  18  during the operation of the wheel bearing, the encoder  9  extends axially along an entire length of the second hollow-cylindrical section  7   b . A gap seal. A gap seal  20  is formed by a sealing gap  19  between the first section  7   a  which functions as a sealing element and the circumferentially extending edge  9   d  on the axial end of the encoder  9  ( FIG. 1   a ,  FIG. 2 ), or between the outer contour  21   d  of the interrupted circumferential face and the first section  7   a  ( FIG. 3 ) and between the outer contour  22   b  of the cylindrical circumferential face of the elastomer body and the first section  7   a  ( FIG. 4 ). The radial dimension of the gap seal, which is formed by the sealing gap  19 , is less than 1 mm and preferably 0.5 mm. 
     The sealing arrangements  3  and  27  optionally have a further gap seal  21  with a sealing gap  23  which is formed axially between the protective sleeve  7  and the radial flange  2 . In this case, an elastic seal  25  is fixed with a sealing lip  26  on the protective sleeve  7  of the sealing arrangement  4  according to  FIG. 4 . The sealing lip  26  bears sealingly against the radial flange  2 . 
     In the operative connection in the sequence from the outside to the inside, the gap seal  20  follows the gap seal  21  or the seal  25  on the bearing side. Accordingly, in this sequence, the gap seal  20  is followed by the seal  8  in the sealing arrangement  27  according to  FIGS. 1 and 2  and by the seal  28  in the sealing arrangements  3  and  4 . The seals  8  and  28  have in each case two of the sealing lips  29  and one sealing lip  30  or  31 . The seals  8 ,  28  are fixed in each case on one disk section  32 . The disk section  32  is configured integrally with the protective sleeve  7 . The sealing lips  29  are prestressed axially against the support  9   b  or  33  of the respective encoder  9  or  21 ,  22 . The sealing lip  30  of the sealing arrangement  27  is prestressed radially against the inner ring  11  and seals the wheel bearing to the outside. The sealing lip  31  bears sealingly, in a radial and direct manner, against the hub  6  and seals the latter to the inside. 
     The encoder  21 ,  22  is fixed directly on the hub  6  by a press fit of the collar  33   a  on the support  33 . The encoding section  21   a  or  22   a  of the encoder  21 ,  22  which is relevant for the signal generation of the sensor  17  extends from the support  33  axially away from the radial flange  2  in the direction of the wheel support  5  and reaches over the latter at the annular section  5   a . The encoder  21  or  22  surrounds the annular section  5   a  of the outer ring  18  or the support  5  without contact, by way of the communicating encoding section  21   a  or  22   a.    
       FIGS. 5 to 7  show alternative sealing arrangements in the wheel bearing arrangement  1 , having a preliminary seal with respect to the gap seal. The preliminary seal is formed by at least one sealing lip  34  on modifications of the encoders  9 ,  21  and  22 . The sealing lip  34  bears sealingly against the protective sleeve  7 . In the sealing arrangement according to  FIG. 5 , the sealing lip is attached separately to the support  9   b  or  33  by vulcanization or the like. In the refinement according to  FIG. 6 , the sealing lip  34  is configured integrally with a body  35 , the elastomer material of which also fills the apertures  21   b  of the encoding section  21   a .  FIG. 7  shows an encoder  22  made from elastomer and with magnetized particles, in which the sealing lip  34  is formed from the elastomer integrally with the encoding section  22   a.    
     LIST OF DESIGNATIONS 
     
         
           1  Wheel bearing arrangement 
           1   a  Rotational axis 
           2  Radial flange 
           3  Sealing arrangement 
           4  Sealing arrangement 
           5  Wheel support 
           5   a  Annular section 
           6  Hub 
           7  Protective sleeve 
           7   a  First section 
           7   b  Second section 
           8  Seal 
           9  Encoder 
           9   a  Encoding section 
           9   b  Support 
           9   c  Collar 
           9   d  Edge 
           9   e  Peak 
           9   f  Trough bottom 
           10  Rolling body 
           11  Inner ring 
           12  Raceway 
           13  Raceway 
           14  Raceway 
           15  Raceway 
           16  Wheel bolt 
           16   a  Projection 
           17  Sensor 
           18  Outer ring 
           19  Sealing gap 
           21  Encoder 
           21   a  Encoding section 
           21   b  Aperture 
           21   c  Web 
           21   d  Outer contour 
           22  Encoder 
           22   a  Encoding section 
           22   b  Outer contour 
           23  Sealing gap 
           25  Seal 
           26  Sealing lip 
           27  Sealing arrangement 
           28  Seal 
           29  Sealing lip 
           30  Sealing lip 
           31  Sealing lip 
           32  Disk section 
           33  Support 
           33   a  Collar 
           34  Sealing lip 
           35  Body