Patent Publication Number: US-2010109424-A1

Title: Axle bearing apparatus

Description:
The present application is a divisional application of U.S. patent application Ser. No. 11/889,424, filed on Aug. 12, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to an axle bearing apparatus, and more particularly to an axle bearing apparatus having muddy water intrusion prevention means for preventing muddy water from intruding into a bearing portion. 
     Recently, unit-type axle bearing apparatuses have increasingly been used even in a pickup truck, etc., and therefore these bearing apparatuses are required to have a higher muddy water-proof ability. 
     There is known an axle bearing apparatus having such a muddy water-proof ability, in which a seal ring comprising a metal core and a seal member is fixed to an outer end portion of an outer ring of a bearing portion, and a slinger is fixed to an axial inner side surface of a rotary flange, and is held in sliding contact with the seal ring, thereby closing an opening of the bearing portion (see, for example, JP-A-2005-233287). 
     In the axle bearing apparatus of JP-A-2005-233287, an annular portion of the slinger is not disposed in intimate contact with the axial inner side surface of the rotary flange, and extends merely to a region disposed radially inwardly of a circle of bolt holes formed in the rotary flange. Therefore, there has been a fear that muddy water might intrude into the bearing portion from the outside of the rotary flange and the bolt holes through a clearance between the rotary flange and the annular portion of the slinger. 
     SUMMARY OF THE INVENTION 
     This invention has been made in order to solve the above problem, and an object of the invention is to provide an axle bearing apparatus in which muddy water is positively prevented from intruding into a bearing portion from an outer periphery, bolt holes, etc., of the flange through a clearance between the flange and a slinger. 
     According to one aspect of the present invention, there is provided an axle bearing apparatus characterized in that the bearing apparatus comprises a hub shaft including a wheel-mounting flange formed at its outer end portion, and a cylindrical portion formed on an inner side surface of the flange; a bearing portion press-fitted on the cylindrical portion of the hub shaft and comprising an inner ring, an outer ring and rolling elements disposed between the inner and outer rings; a slinger having a through hole formed through its central portion, the through hole being fitted on the cylindrical portion such that an outer diameter of the slinger is generally equal to an outer diameter of the flange, and the slinger being press-clamped to the inner side surface of the flange by bolts press-fitted respectively in a plurality of bolt holes formed in the flange; and an O-ring is interposed between the flange and the slinger. 
     According to another aspect of the invention, there is provided an axle bearing apparatus comprising the hub shaft, the bearing portion, and the slinger, wherein the slinger is bonded to the flange by an adhesive. 
     According to a further aspect of the invention, there is provided an axle bearing apparatus comprising the hub shaft, the bearing portion, and the slinger, wherein a seal member is interposed between the flange and the slinger. 
     In any one of the above axle bearing apparatuses, a rib is formed at an outer periphery of the slinger, and is fitted to an outer periphery of the flange. 
     In the present invention, the O-ring or the seal member is interposed between the flange of the hub shaft and the slinger between which muddy water is liable to intrude, and as another alternative, the flange and the slinger are adhesively bonded together by the adhesive. Therefore, muddy water is positively prevented from intruding into the bearing portion through a clearance between the flange and the slinger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a first embodiment of an axle bearing apparatus of the present invention. 
         FIG. 2A  is a cross-sectional view of an important portion of a flange, and  FIG. 2B  is a cross-sectional view of a slinger. 
         FIG. 3  is a cross-sectional view of a portion of a modified example of the first embodiment. 
         FIG. 4  is cross-sectional view of a portion of a second embodiment of an axle bearing apparatus of the invention. 
         FIG. 5  is cross-sectional view of a portion of a third embodiment of an axle bearing apparatus of the invention. 
         FIG. 6  is cross-sectional view of a portion of a fourth embodiment of an axle bearing apparatus of the invention. 
         FIG. 7  is cross-sectional view of a portion of a fifth embodiment of an axle bearing apparatus of the invention. 
         FIGS. 8A to 8C  are views explanatory of modified slingers used in the axle bearing apparatus of the fifth embodiment. 
         FIG. 9  is cross-sectional view of a portion of a sixth embodiment of an axle bearing apparatus of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     First Embodiment 
       FIG. 1  is a vertical cross-sectional view of an axle bearing apparatus according to a first embodiment of the present invention. In the following description, the right side in the drawings will be referred to as “inner side”, while the left side will be referred to as “outer side”. 
     In the drawings, reference numeral  1  denotes the axle bearing apparatus of the invention, and a flange  3  is formed on an outer periphery of a hub shaft  2  (made of a steel material) at an outer end portion thereof, and a plurality of bolt holes  4  are formed through this flange  3 . Bolts  5  are passed respectively through these bolt holes  4  so as to mount a wheel (not shown) on the flange  3 . A cylindrical portion  5  for the mounting of a bearing portion  10  (described later) thereon is formed on a central portion of the inner side of the flange  3 , and projects therefrom in an axial direction. A cylindrical caulking portion  6  (indicated in broken lines) for fixing the bearing portion  10  is formed in a projecting manner at an inner end of the cylindrical portion  5 . 
     As shown in  FIG. 2A , two ring-like grooves  7   a  and  7   b  for respectively receiving O-rings  16   a  and  16   b  (described later) are formed in the inner side surface of the flange  3  in concentric relation to each other, and are disposed respectively at inner and outer periphery sides of a circle of bolt holes  4 . Similarly, a groove  7   c  for receiving an O-ring  16   c  is formed in an outer peripheral surface of the flange  3 . 
     The bearing portion  10  comprises an inner ring  11  divided into two sections each having a rolling contact surface (raceway surface) formed between ribs formed respectively at opposite ends thereof, an outer ring  12  having two rows of rolling contact surfaces corresponding respectively to the two rolling contact surfaces of the inner ring  11 , and two rows of tapered rollers (rolling elements)  13  disposed between the inner and outer rings  11  and  12 , each row of tapered rollers  13  being disposed between the corresponding rolling contact surfaces of the inner and outer rings  11  and  12 . 
     The bearing portion  10  is press-fitted onto an outer peripheral surface of the cylindrical portion  5  of the hub shaft  2 , and then the caulking portion  6  is bent radially outwardly for caulking purposes as indicated in solid lines, and by doing so, the bearing portion  10  is held between a step portion  8  (formed at that portion of the cylindrical portion  5  disposed close to the flange  3 ) and the caulking portion  6 . Then, the outer ring  12  is mounted on an axle case or other portion (not shown) through a flange  14  formed on the outer periphery of the outer ring  12  in such a manner that the outer ring  12  can not rotate. 
     An externally-mounting dust seal  17  comprises a cylindrical metal core  18  (whose inner diameter is substantially equal to an outer diameter of the outer end portion of the outer ring  12  of the bearing portion  10 ) made of a metal material with excellent corrosion resistance (such as stainless steel, an alloy, etc.), a flange  19  formed on an outer periphery of the metal core  18  at an outer end thereof, and a lip  20  provided at an outer peripheral edge of the flange  19  and made of an elastic material such as rubber. The dust seal  17  is mounted on the bearing portion  10  with the metal core  18  press-fitted on the outer end portion of the outer ring  12 . 
     Reference numeral  30  denotes a slinger which is formed of a metal plate with excellent corrosion resistance such for example as a zinc plated steel plate, a chromium plated steel plate, a stainless steel plate, a titanium plate, etc. As shown in  FIG. 2B , this slinger  30  includes a doughnut-shaped body portion  31  having a through hole  33  (whose diameter is larger than the outer diameter of the cylindrical portion  5 ) formed through a central portion thereof, and having an outer diameter generally equal to the outer diameter of the flange  3 , and a rib  32  formed by bending its outer peripheral portion toward the outer side. A width of the rib  32  is generally equal to or slightly smaller than a width (wall thickness) of the flange  3 . Bolt passage holes  34  are formed through that portion of the body portion  31  lying between the through hole  33  and the rib  32 , so as to be aligned respectively with the bolt holes  4 , the bolt passage holes  34  being slightly larger in diameter than the bolt holes  4 . 
     Next, one example of a procedure of assembling the axle bearing apparatus  1  of the above construction will be described. 
     First, the O-rings  16   a ,  16   b  and  16   c  are fitted respectively into the grooves  7   a ,  7   b  and  7   c  formed in the flange  3  of the hub shaft  2 . Then, the through hole  33  of the slinger  30  is fitted on the cylindrical portion  5  from the inner side, and the rib  32  is fitted on the outer periphery of the flange  3  to be retained thereon, and also the body portion  31  is held against the inner side surface of the flange  3 , and the bolt passage holes  34  of the body portion  31  are aligned respectively with the bolt holes  4  of the flange  3 . 
     In this condition, the bolts  15  are passed through the respective bolt passage holes  34  of the slinger  30 , and are press-fitted into the respective bolt holes  4  of the flange  3 . By doing so, the slinger  30  is press-clamped to the inner side surface of the flange  3  through the O-rings  16   a  and  16   b , so that a water-tight seal is formed between the inner side surface of the flange  3  and the slinger  30 . Also, the rib  32  is press-clamped to the outer peripheral surface of the flange  3  through the O-ring  16   c , so that a water-tight seal is formed between the outer peripheral surface of the flange  3  and the slinger  30 . 
     Then, the bearing portion  10  having the metal core  18  of the externally-mounting dust seal  17  press-fitted on the outer end portion of the outer ring  12  is press-fitted onto the outer peripheral surface of the cylindrical portion  5  from the inner side. Then, the caulking portion  6  is bent to extend radially outwardly, so that the bearing portion  10  is held between the step portion  8  and the caulking portion  6 . At this time, the lip  20  of the externally-mounting dust seal  17  is held in sliding contact with an inner side surface of the slinger  30 . In the above description, although the bearing portion  10  pressed-fitted on the cylindrical portion  5  is fixed by bending the caulking portion  6 , the fixing means is not limited to this construction, and there can be used any other suitable fixing means such for example as one in which an externally-threaded portion is formed on the outer peripheral surface of the inner end portion of the cylindrical portion  5 , and a nut is threaded on this externally-threaded portion, thereby fixing the bearing portion  10 . 
       FIG. 3  is a cross-sectional view of a half portion of a modified example of the axle bearing apparatus according to the first embodiment on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the axle bearing apparatus of  FIG. 1  will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     In this modified example, among the O-rings  16   a  to  16   c  (see  FIG. 1 ) provided between the flange  3  of the hub shaft  2  and the slinger  30 , the O-ring  16   b  (at the outer periphery side of the circle of bolt holes  4 ) and the O-ring  16   c  (at the outer peripheral surface of the flange  3 ) are omitted, and only the O-ring  16   a  is provided at the inner periphery side of the circle of bolt holes  4 . The other construction is the same as that of  FIG. 1 . 
     In this embodiment, the slinger  30  is provided at the inner side of the flange  3  of the hub shaft  2 , and the O-rings  16   a  and  16   b  form a seal between the slinger  30  and the inner side surface of the flange  3 , and also the O-ring  16   c  forms a seal between the slinger  30  and the outer peripheral surface of the flange  3 . In the modified form of the invention, the O-ring  16   a  forms a seal between the slinger  30  and the inner side surface of the flange  3 . Therefore, muddy water is positively prevented from intruding into the bearing portion  10  from the outer periphery, the bolt holes  4 , etc., of the flange  3  through a clearance between the flange  3  and the slinger  30 . And besides, the rib  32  formed at the outer periphery of the slinger  30  is retained on the outer periphery of the flange  3 , and therefore the slinger  30  will not be displaced out of position during the assembling operation. 
     Second Embodiment 
       FIG. 4  is a cross-sectional view of a half portion of an axle bearing apparatus according to a second embodiment of the invention on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the first embodiment will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     In this embodiment, a slinger  30  is composed solely of a body portion  31 , and therefore does not have the rib  32  as described above for the first embodiment. Furthermore, the O-rings  16   a  to  16   c  as described above for the first embodiment are not interposed between a flange  3  of a hub shaft  2  and the slinger  30  (Therefore, the grooves  7   a  to  7   c  are not formed in the flange  3 ), and the slinger  30  is adhesively bonded to an inner side surface of the flange  3  by an adhesive  36 . In this embodiment, the rib  32  may be formed at the outer periphery of the body portion  31  as in the first embodiment. 
     In this embodiment, also, similar advantageous effects to those of the first embodiment can be obtained. 
     Third Embodiment 
       FIG. 5  is a cross-sectional view of a half portion of an axle bearing apparatus according to a third embodiment of the invention on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the second embodiment will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     In this embodiment, a seal member  37  made of an elastic material such as rubber is interposed between a slinger  30  (which has the same structure as that of the slinger  30  of the second embodiment) and an inner side surface of a flange  3  of a hub shaft  2 . The seal member  37  may be provided over an entire area of contact between the slinger  30  and the flange  3 , or may be provided only at an area disposed radially inwardly of a circle of bolt holes  4  or only at areas disposed respectively around the bolt holes  4 . 
     In this embodiment, also, similar advantageous effects to those of the first embodiment can be obtained. 
     Fourth Embodiment 
       FIG. 6  is a cross-sectional view of a half portion of an axle bearing apparatus according to a fourth embodiment of the invention on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the second embodiment will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     In this embodiment, a slinger  30  does not have the rib  32  as described above for the first embodiment, and a peripheral edge portion of a through hole  33  formed through the slinger  30  is bent toward the inner side to form a bent portion  35  of a generally L-shaped cross-section. The slinger  30  is held against an inner side surface of the flange  3 , and a seal member  38  made of an elastic material such as rubber is interposed between the bent portion  35  and the flange  3 . 
     In this embodiment, also, similar advantageous effects to those of the first embodiment can be obtained. 
     Fifth Embodiment 
       FIG. 7  is a cross-sectional view of a half portion of an axle bearing apparatus according to a fifth embodiment of the invention on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the first embodiment will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     A slinger  30  is fixedly held between a flange  3  of a hub shaft  2  and heads of bolts  15  press-fitted in respective bolt holes  4  as described above. When the bolts  15  are press-fitted into the respective bolt holes  4 , the slinger  30  is, in some cases, deformed, so that a lip  20  of an externally-mounting dust seal  17  fails to be disposed in uniform contact with a sliding contact surface (inner side surface) of the slinger  30 , and as a result muddy water may intrude into a bearing portion  10  through a clearance. 
     In this embodiment, an outer peripheral edge portion of the slinger  30  is bent toward the inner side to form a bent portion  39 , thereby increasing the rigidity of the slinger  30  so as to prevent deformation of the slinger  30 . Instead of forming this bent portion  39 , a peripheral edge portion of a through hole  33  in the slinger  30  may be bent toward the inner side to form a bent portion  39   a  as shown in  FIG. 8A , or in addition to the bent portion  39 , the inner peripheral edge portion of the through hole  33  may be bent toward the inner side to form a bent portion  39   a  as shown in  FIG. 8B . 
     In a further modified example, the outer peripheral edge portion of the slinger  30  may be bent toward the outer side to form a bent portion  39   b , and also the peripheral edge portion of the through hole  33  may be bent toward the inner side to form a bent portion  39   a  as shown in  FIG. 8C . 
     In this embodiment, the rigidity of the slinger  30  can be increased, and therefore when the bolts  15  are press-fitted into the respective bolt holes  4 , the deformation of the slinger can be suppressed. Therefore, the lip  20  of the externally-mounting dust seal  17  is positively held in sliding contact with the side surface of the slinger  30 , thereby preventing the intrusion of muddy water. The bent portion or portions  39 ,  39   a ,  39   b  for increasing the rigidity of the slinger  30  can be formed at the slingers  30  of the above second to fourth embodiments and also at the slinger  30  of the modified example (in which the provision of the rib  32  is omitted) of the first embodiment. 
     Sixth Embodiment 
       FIG. 9  is a cross-sectional view of a half portion of an axle bearing apparatus according to a sixth embodiment of the invention on one side of a centerline (longitudinal axis) thereof. Those portions identical to those of the first embodiment will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. 
     Conventionally, when the metal core  18  of the externally-mounting dust seal  17  was press-fitted onto the bearing portion  10 , the metal core  18  was, in some cases, deformed, and the area of contact of the metal core  18  with the bearing portion  10  was reduced, so that the metal core  18  was liable to be withdrawn from the bearing portion  10 . And besides, the roundness of the lip  20  was, in some cases, lowered by the deformation of the metal core  18 , and the lip  20  was not properly held in sliding contact with the surface of the flange  2  or the surface of the slinger  30 , so that the muddy water-proof ability was lowered. 
     In this embodiment, an inner end portion of a metal core  18  of a dust seal  17  is bent radially outwardly to form a bent portion  21 , thereby increasing the rigidity of the metal core  18  so as to prevent the metal core  18  from being deformed when it is press-fitted onto a bearing portion  10 . 
     With this construction, the metal core  18  is positively press-fitted on the bearing portion  10 , and will not be withdrawn therefrom, and besides the lip  20  is positively held in sliding contact with the surface of the flange  3  or the surface of the slinger  30  over the entire periphery thereof, thereby preventing the intrusion of muddy water. 
     Although the specific embodiments of the present invention have been described above, the invention is not limited to the illustrated axle bearing apparatuses, and can be applied also to any other suitable axle bearing apparatus within the scope of the technical ideas of the invention. Furthermore, the rolling elements  30  can be replaced by balls. 
     Applicants hereby incorporate by reference the complete subject matter of Japanese priority document JP 2006-220942.