Abstract:
A wheel hub magnetic filter fits within a wheel hub mounted for rotation on an end of the axle. The lubricating oil filter is positioned in a lubricating oil path upstream from the wheel hub bearings and is mounted with the wheel hub for rotation. The lubricating oil filter comprising a circular ring section which fits into an annular plenum in the wheel hub and includes flow directing barriers positioned radially inwardly from an outer edge of the circular ring section.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an apparatus for filtering metallic shavings from liquid lubricant in an axle, and more particularly to lubricant circulating through the wheel hubs mounted on at the axle ends.  
           [0003]    2. Description of the Problem  
           [0004]    Rear drive axles for motor vehicles provide lubrication for moving parts within the axle, including the power distribution gears (the differential) and the bearings located in the axle ends for the wheel hubs. Lubricating oil circulates outwardly from the differential housing through the axle to the wheel hubs and returns by the same channel in the axle to the differential housing during cornering. During vehicle operation metal shavings may form off the differential gears and become suspended in the lubricating oil due to the continuing agitation of the differential ring gear. These metallic shavings can circulate to and through the wheel hubs, causing damage to or wear of the roller bearings located there through abrasion. The shavings may foul the bearings reducing the flow of lubricant, accelerating these negative effects.  
           [0005]    Filtration of metallic shavings in the differential housing to protect the differential is known in the art. For example, U.S. Pat. No. 3,847,249 to Oehring teaches providing a lubricant filtration system located in the differential housing. The filtration system was simple to construct, easy to service and reliable in operation, requiring only infrequent service. During vehicle operation oil is splashed against the interior of the differential housing by action of the differential gears. Oehring provides a filter comprising a lubricant receptacle positioned between the periphery of the large differential ring gear and the top of the differential housing to collect oil dripping from the interior housing surface. The filter unit provides a relatively large area for lubricant flow, a large area for filtered lubricant distribution, and a particle collection cavity in which separated solid particles can accumulate without adversely affecting the filtration function by filter media blockage. In one form, mechanical filtration was supplemented by magnetic separation of metallic particles from the lubricant. Such a filtration system provides no guarantee of thorough filtering of the oil, and the rate of exchange between oil in the wheel hubs and the differential housing may be very slow, with the consequence that oil reaching the wheel hubs may not be filtered. This can allow metal bearing oil to reach the hubs with the consequential risk of damage to the wheel bearings.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the invention there is provided a magnetic filter for installation in a wheel hub. The magnetic filter fits within the wheel hubs, which are mounted for rotation on each end of the axle. The wheel hub rotates on a plurality wheel hub bearings disposed on the end of the axle in contact with the wheel hub. The axle includes a channel allowing lubricating oil to reach the wheel hub bearings. The lubricating oil filter is positioned in the lubricating oil path between the wheel hub bearings and the channel, so that all oil reaching the bearings passes through the hub, and is mounted with the wheel hub for rotation. The lubricating oil filter comprises a circular ring section which fits into an annular plenum in the wheel hub and includes flow directing barriers positioned radially inwardly from an outer edge of the circular ring section. Centripetal acceleration will promote separation of the more massive metal shavings from the lubricating oil. Constructing the ring of a magnetic material promotes retention of the metal shavings on the ring. Construction of the ring from a spring material, and the provision of gaps or holes through the filter, allow fitting the ring into the plenum without fasteners.  
           [0007]    Additional effects, features and advantages will be apparent in the written description that follows.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:  
         [0009]    [0009]FIG. 1 is a top view of a vehicle drive axle;  
         [0010]    [0010]FIG. 2 is a view in partial section of an end of a drive axle for a vehicle;  
         [0011]    [0011]FIG. 3 is a view in section of a wheel hub;  
         [0012]    [0012]FIG. 4 is a perspective view of a magnetic ring filter according to a first preferred embodiment of the invention;  
         [0013]    [0013]FIG. 5 is a top plan view of the magnetic ring filter of FIG. 4;  
         [0014]    [0014]FIG. 6 is a side elevation of the magnetic ring filter of FIG. 4;  
         [0015]    [0015]FIG. 7 is a perspective view of an alternative ring filter;  
         [0016]    [0016]FIG. 8 is a perspective view of another ring filter;  
         [0017]    [0017]FIG. 9 is a perspective view of still another ring filter; and  
         [0018]    [0018]FIG. 10 is a perspective view of another filter.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    Referring now to the figures and in particular to FIG. 1, a vehicle drive axle assembly  10  of a general type is illustrated. Axle assembly  10  includes an elongated housing  12  and a central expanded enclosure  14 , which contains a drive differential. The drive differential may be reached by removal of a differential cover plate  16 . Each end  18  (only one shown) of axle housing  12  supports a wheel hub as illustrated below.  
         [0020]    [0020]FIG. 2 illustrates mounting of a wheel hub  20  on an axle end section  18 . Wheel hub  20  rotates on axle end section  18  supported by outer roller bearings  28  and inner roller bearings  24 . Bearings  28  and  24  contact lubricating oil supplied from the differential at the bottom of a bearing race. Lubricating oil from the differential is supplied through the axle housing out of end  20  to the wheel bearings in the direction indicated by arrow A. During turns where axle end  20  is to the outside of the turn additional oil will flow out of the axle and into plenum  21  including bearings  28  and  24 . Turns in the opposite direction reverse the direction of oil flow. An inner ring of bolts  26  secure attachment of wheel hub  20  to support the mounting of wheels to the hub.  
         [0021]    Referring now to FIG. 3, wheel hub  26  is mounted around axle end  18 , on which it is supported by bearings  28 , attached to powered axle shaft  40  by a plurality of mounting studs  42 . A magnetic filter ring  50  having an “L” shaped cross sectional area is illustrated positioned inside an annular opening  51  in a wheel hub  26 , just outside of a plurality of wheel bearing adjusting nuts  52  and backed up against a shoulder  53 . Outer bearing  28  is positioned in an annular plenum inside of the shoulder  53 . Axle shaft  40  ends in a flattened disk section  41  which is sealed against hub  26  along a ring seal  54 . The lubricating oil level inside of shaft end  18 , supplied from the differential, assures that a portion bearing  28  is submerged in the oil. As bearings  28  move through the oil the are coated with a layer of lubrication. Lubricating oil may circulate through the axle as a result of turns with the differential acting as a sort of pump to mix the oil. Bearings  28  and  24  are located in races  57  and  59  in a dead end plenum, so that the positioning of filter  50  forces any oil which reaches the bearings to pass through filter.  
         [0022]    Magnetic ring filter  50  rotates with wheel hub  26 , resulting in greater force from centripetal acceleration being applied to the denser particles suspended in the lubricating oil then to the oil, driving them toward the outer portion of the ring, where, if they a ferro-metallic, they adhere due to the magnetic properties of the ring. The inner portion of ring  50  includes openings which allow oil to pass in either direction.  
         [0023]    FIGS.  4 - 6  illustrate the magnetic filter ring  50  in detail from perspective, side elevation and top views. Ring  50  includes a solid outer section  60 , the opposite major surfaces of which are parallel to a central axis of the ring. An inner major surface  61  of outer section  60  provides a surface to which metal shavings under magnetic attraction adhere. A second major portion of ring  50  is provided by an inner ring  62 , which is perpendicular to outer section  60 . Inner ring  62  is pierced by a plurality of holes  64  through which oil passes. Filter ring  50  is broken by a relatively narrow gap  66  aligned with the central axis through both the outer and inner major sections  60  and  62 . Ring  50  is preferably made of a spring grade steel, and is slightly oversized when untensioned compared to the annular space into which it is intended to fit. Pressing ring  50  into a wheel hub compresses the spring, closing gap  66  as required, to fit into the intended space. Spring tension holds ring  50  holds in the annular space. Obviously then, ring  50  does not need fit the annular wheel hub opening perfectly. In some applications, gap  66  may be omitted and the holes through ring filter  50  compressed to achieve the desired fit.  
         [0024]    FIGS.  7 - 9  illustrate alternative configurations for magnetic filters. In FIG. 7 a ring filter  750  is formed as a ring having a rectangular cross section. A plurality of holes  764  pass the length of the ring, allowing oil to pass through the ring. No gap is illustrated in the ring, although one may be provided. Again the preferred material is ferromagnetic, allowing the material to be permanently magnetized to cause shavings from the differential to adhere to the upstream surface of the ring. In FIG. 8 a ring  850  is illustrated formed with inwardly oriented teeth  821  from an outer ring  85 . A fitting gap  86  in the ring allows compression and generation of spring tension for fitting and retaining the ring  850  in an annular gap. FIG. 9 illustrates yet another possibility for a ring  950  based on an outer ring  89  and a plurality of inwardly oriented posts  921  for channeling and disrupting oil flow to allow centripetal acceleration to separate the shavings from the oil.  
         [0025]    An alternative magnetic filter is depicted in FIG. 10, where a strip  110  supports a plurality of upright vanes  112  on one major surface thereof. Strip  110  is flexible, allowing it to be coiled and inserted into an annular plenum. The major surface of strip  110  opposite the strip supporting the vanes  112  may be made tacky to retain it in place in a plenum. The material may be loaded with magnetic material to attract metallic shavings separating from the lubricating oil along vanes  112 . The strip may be cut to the desired length for a given application.  
         [0026]    The invention provides a simple, easily serviceable filter for wheel hubs. No tools are required for fitting the device and in its preferred embodiment may be made to retrofit to many existing wheel hubs. In a flexible tape form it is widely usable.  
         [0027]    While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.