Bearing device for drive wheel

Abstract

The wheel hub 30 includes a radial swaged portion 37 formed by a radially outward plastic deformation of one end thereof, whereby an inner ring 40 fitted onto the wheel hub 30 is united therewith. An outer joint member 72 of a constant velocity joint 70 is press-fitted into the wheel hub 30 , causing serrations 81 on the inner periphery of the wheel hub 30 and a serrated shaft 82 of the outer joint member 72 to engage with each other. The tooth profile of the serrations 81 on the wheel hub 30 is controlled within a predetermined specified range over the entire axial length thereof, whereby radial contraction of the serrations 81 caused by swaging is reduced.

1 . A drive wheel bearing device comprising: 
 an outer member having double-row outer races on an inner periphery thereof;    an inner member including double-row inner races opposite the outer races of the outer member, a first inner member, and a second inner member formed with at least one of the double-row inner races, the first inner member and the second inner member being inseparably coupled together at a radial swaged portion that is formed by a radially outward plastic deformation of the first inner member;    double-row rolling elements interposed between the outer member and the inner member; and    a constant velocity joint including an outer joint member fitted to an inner periphery of the first inner member such as to transmit torque, the swaged portion being in contact with the outer joint member in an axial direction, wherein 
 part of the swaged portion making contact with the outer joint member is a flat surface, and variations in the axial position of the flat surface are restricted within a specified limit.  
   
     
     
         2 . The drive wheel bearing device according to  claim 1 , wherein the flat surface is formed by machining.  
     
     
         3 . The drive wheel bearing device according to  claim 1 , wherein the specified limit is ±0.2 mm.  
     
     
         4 . The drive wheel bearing device according to  claim 1 , wherein variations in the perpendicularity of the flat surface relative to an axial line are restricted within a specified limit.  
     
     
         5 . The drive wheel bearing device according to  claim 4 , wherein the specified limit is 0.15 mm.  
     
     
         6 . The drive wheel bearing device according to  claim 1 , wherein the flat surface of the swaged portion and a surface portion of the outer joint member making contact therewith have a same hardness.  
     
     
         7 . The drive wheel bearing device according to any one of  claims 1  to  6 , wherein the outer joint member is provided with a torque transmission part for transmitting torque to and from the first inner member, and the outer joint member includes a surface hardened layer formed by heat treatment in a region that includes at least the torque transmission part but does not include a portion making contact with the flat surface.  
     
     
         8 . A drive wheel bearing device comprising: 
 an outer member having double-row outer races on an inner periphery thereof;    an inner member including double-row inner races opposite the outer races of the outer member, a first inner member, and a second inner member formed with at least one of the double-row inner races, the first inner member and the second inner member being inseparably coupled together at a flange-like swaged portion that is formed by a radially outward plastic deformation of one end of the first inner member;    double-row rolling elements interposed between the outer member and the inner member; and    a constant velocity joint including an outer joint member press-fitted to an inner periphery of the first inner member with torque transmission means formed therebetween that transmits torque by engagement of a plurality of axially extending teeth, wherein 
 the torque transmitting teeth of the first inner member have a tooth profile that is controlled within a specified range over the entire axial length of the teeth.  
   
     
     
         9 . The drive wheel bearing device according to  claim 8 , wherein the specified range is determined in accordance with a maximum permissible force required for pres-fitting the outer joint member.  
     
     
         10 . The drive wheel bearing device according to  claim 8 , wherein the specified range is determined such that the torque transmitting teeth have an over pin diameter with a dimensional tolerance of 60 μm.  
     
     
         11 . The drive wheel bearing device according to  claim 8 , wherein the tooth profile control is achieved by a process including primary turning of the first inner member on the inner periphery, swaging of one end of the first inner member, secondary turning of the first inner member on the inner periphery in a region including at least the vicinity of the swaged portion, and broaching of the inner periphery of the first inner member.  
     
     
         12 . The drive wheel bearing device according to  claim 8 , wherein the tooth profile control is achieved by a process including primary turning and broaching of the first inner member on the inner periphery, swaging of one end of the first inner member, and secondary turning of the first inner member in a region including at least the vicinity of the swaged portion.  
     
     
         13 . The drive wheel bearing device according to any one of  claims 8  to  12 , wherein the torque transmitting teeth of the first inner member include a surface that has undergone secondary turning at least in the vicinity of the swaged portion.  
     
     
         14 . The drive wheel bearing device according to any one of  claims 8  to  12 , wherein at least the vicinity of the swaged portion that has undergone secondary turning has a larger diameter than other portions.  
     
     
         15 . The drive wheel bearing device according to  claim 8 , wherein a negative clearance is provided between the rolling elements, and the inner races and the outer races in which the rolling elements roll.  
     
     
         16 . The drive wheel bearing device according to  claim 8 , wherein a pilot part is provided at an inner periphery near the swaged portion of the first inner member.  
     
     
         17 . A drive wheel bearing device for supporting a wheel such as to be rotatable relative to the vehicle body, comprising: 
 an outer member formed with double-row outer races on an inner periphery thereof;    an inner member including double-row inner races opposite the outer races of the outer member and a flange for attachment of a wheel both formed on an outer periphery thereof, and a swaged portion that is formed by a radially outward plastic deformation of one end thereof;    double-row rolling elements interposed between respective races of the outer member and the inner member; and    a constant velocity joint including an outer joint member abutted on the swaged portion of the inner member, the outer joint member having a stem part fitted into the inner member such as to transmit torque via serrations, wherein 
 mating parts of the inner member and the outer joint member have undergone rust proof treatment.  
   
     
     
         18 . The drive wheel bearing device according to  claim 17 , wherein the rust proof treatment includes providing an antirust in the mating parts of the inner member and the outer joint member.  
     
     
         19 . The drive wheel bearing device according to  claim 18 , wherein the antirust is an adhesive containing an elastomer.  
     
     
         20 . The drive wheel bearing device according to  claim 18 , wherein the antirust is a foaming agent containing an elastomer.  
     
     
         21 . The drive wheel bearing device according to  claim 17 , wherein the outer member has the double-row outer races on the inner periphery thereof and a flange for attachment to the vehicle body on an outer periphery thereof, both being formed integrally therewith.  
     
     
         22 . The drive wheel bearing device according to  claim 17 , wherein the inner member includes a wheel hub having a flange for attachment of a wheel on an outer periphery, an outboard side inner race, and a small diameter stepped part, and an inner ring fitted onto the small diameter stepped part of the wheel hub and including an inboard side inner race on an outer periphery thereof, and one end of the small diameter stepped part is plastically deformed radially outward to unite the wheel hub and the inner ring.  
     
     
         23 . The drive wheel bearing device according to  claim 17 , wherein the inner member and the stem part of the outer joint member are fixed to each other in an axial direction in a detachable manner by a retention member.  
     
     
         24 . The drive wheel bearing device according to  claim 23 , wherein the inner member is provided with a cap fitted thereon to seal an opening at one end thereof, the cap having an aperture therein.