Patent Publication Number: US-2007111841-A1

Title: Axle assembly bearing positioning and preload adjustment tool and method of implementing same

Description:
This application claims the benefit of U.S. provisional application Ser. No. 60/727,861 filed on Oct. 19, 2005 and is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to the adjustment of a bearing support in a differential assembly and more particularly to threaded adjuster for adjusting preload and setting the differential case.  
      2. Discussion of the Related Art  
      There has been a long felt need in the art for threaded adjusters for differential bearing pre-load and the setting of the differential case. Many differentials have been made with no way to adjust bearing pre-load or setting the case other than to assemble the differential with a prescribed number of shims and then check the ring and pinion alignment, if the alignment is incorrect, the differential must be disassembled, the shims changed and the differential reassembled. This type of pre-load adjustment system can be very time consuming, costly and frustrating for the person doing the assembly. An alternative to shims and trial and error are threaded adjusters. However, the current generation of threaded adjusters has caused many artisans to have less than a proactive approach in implementing them. Currently, the only way to adjust the threaded adjusters present in the art is to go into the tube bore with a driver or modify the carrier casting with a window that would allow the use of a spanner type wrench for adjustment through the cover plate opening. These current adjustment devices are difficult and time consuming to use especially in a Salisbury type axle assembly. The following references are each incorporated herein by reference: U.S. Pat. Nos. 6,532,660; 5,947,252; 6,318,201; 6,478,709; 6,357,927; 6,595,085; 5,624,345; 6,736,544; 6,318,201; 6,093,127; 6,088,910; 6,000,134; 5,806,371; 5,579,570; 5,115,558; 4,406,179.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a motor vehicle differential axle assembly. The assembly includes a differential case driven by an input shaft and having a gear assembly disposed therein for allowing differential speed rotation between a pair of output shafts. The case is rotatably supported in a housing by a pair of bearing assemblies. The bearing assemblies are disposed about a respective one of the shafts. The housing includes an opening to provide access therein. A pair of threaded adjusters having a substantially cylindrical body are disposed within and threadingly engaging the housing. The threaded adjusters each are selectively positionable along a central axis by selective relative rotation relative to the housing. The cylindrical bodies each include gear teeth positioned proximate the opening of the housing for engaging a rotatable tool to facilitate selective positioning. The threaded adjusters are each positioned between the housing and a respective one of the bearing assemblies. The threaded adjusters are simultaneously adjustable to provide for either selective positioning of the differential case relative to the housing or establishing a preload to said bearing assemblies. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:  
       FIG. 1  is a sectional view of a differential housing assembly incorporating the present invention with the preload/setting adjuster installed into the differential housing.  
       FIG. 2  is an isolated view of the engagement of the rotary tool head and gearing of the adjuster according to an alternate embodiment employing a beveled gear.  
       FIG. 3  is a side view of the rotary tool engaging he threaded adjuster of  FIG. 2 .  
       FIG. 4  is a schematic view of an indexing machine with dual rotary tool heads.  
       FIG. 5  is an isolated partial exposed view of a differential axle assembly with threaded adjuster disposed between the housing and case bearings. 
    
    
     DESCRIPTION OP THE PREFERRED EMBODIMENT  
      The present invention is directed to a bearing adjuster  1  for a differential. The threaded adjuster  1  is a cylindrical body having threads  3  on the outer surface which engage corresponding teeth/threads  5  formed in the axle housing  7 . The adjuster  1  also has a ring of gears  9  preferably spur gears, on the outer diameter of the adjuster  1 . A bearing thrust surface  11  is provided to seat a set of bearings  31  to rotatably support components of the axle assembly. Bevel gear teeth or helical or splined teeth may also be employed. In the beveled gear embodiment, the teeth are similar to the kind found on a drill chuck or side gear, commonly referred to as bevel gear type teeth. The carrier housing  7  includes a removable cover (not shown) exposing an opening to access the gear face  9  of the threaded adjuster. This allows for a rotary tool  21  to be inserted perpendicular to the rotation of the treaded adjuster  3  with sufficient clearance.  
      In order to set the differential case  51 , and or establish the bearing preload, the rotary tool  21  equipped with a drive head  23  to engage the teeth  9  in the adjuster  1 , is inserted through the housing opening until it mates with the gear teeth  9  on the adjuster  3 . As the rotary tool/gear head rotates, the threaded adjuster  1  rotates within the housing  7  which causes the adjuster  1  to move axially relative to the housing  1 . The tool/gear head  23  may be rotated in either direction to cause axial/longitudinal displacement of the threaded adjuster  1  in either direction along axis  13 . The tool  21  is simply rotated until either the adjuster  1  is in a proper position or bearing preload is established.  
      Dual rotary tools  21   a    21  may be employed to simultaneously engage opposite adjusters (only one shown) during the installation of the differential case  51 . Once the axle assembly is loosely assembled, the rotary tool heads  21   a,    21   b  will engage the adjusters  1  and rotate according to properly set the axle assembly. Position sensors  25  (schematically shown in  FIG. 4 ) may be employed to sense the position of the differential case  51  and sent to a controller  27  which in turn controls the rotary movement of each tool head  21   a,    21   b  and thus control the rotation of the adjuster  1 . A simple control algorithm may be employed to properly control the rotation of the rotary heads  21   a,    21   b  to obtain the desired setting of the differential case  51 . Off course, the rotary tool  21  may be individually and manually manipulated to set/locate the differential case  51 . In either method, the use of a continuously engaging tool with the threaded adjuster  1  by a rotary gear head  21  eliminates the use of a cumbersome spanner wrench.  
      Once the differential case  51  is set in the housing  7  and the tubes pressed, the differential bearing pre-load may be established. Thus this system will allow the Assembly Department to set the pre-load after the tubes have been pressed into the carrier  7 . Furthermore, bearing preload may be simply reset at any time during maintenance. The housing cover simply need be removed to expose the gearing  9  of the adjuster  1  and engaged with the gear head  23  of the rotary tool  21 .  
       FIG. 1  depicts a differential housing  7  with a threaded adjuster  1  threadingly engaging the housing  7  in a corresponding threaded portion  5  formed in the housing. A window  15  may be cut in the threaded portion of the housing  5  to allow exposure of the geared portion  9 . With the cover removed, a simply rotary tool  21  may be inserted to engage the gearing  9  of the adjuster  1  such that rotation of the tool head  21  will cause the adjuster  1  to rotate and translate longitudinally along axis  13  within the housing  7 . A second adjuster is preferably disposed on the opposite side of the housing  7  in a similar fashion (Adjuster not shown) that will facilitate setting of the differential case  51  by selective adjustment of each threaded adjuster  1 .  
       FIG. 2  depicts an isolated view of the threaded adjuster  1  and rotary tool head  23 . In this embodiment a beveled gear is employed much like the chuck of a drill. The rotary tool head  23  is simply inserted perpendicular to the axis of the adjuster  3 . Rotation of the tool head  23  will cause the adjuster  1  to rotate relative to the housing  7  to facilitate precise location of the adjuster  3  along the longitudinal axis  13  of the adjuster  1  and axle assembly.  
       FIG. 3  is an isolated side view showing the engagement of the rotary tool head  23  with the bevel gears formed on the outer diameter of the adjuster  1 .  
       FIG. 4  depicts a schematic view of the rotary too head  21  with associated indexing machine  29 . Two rotary tools  21   a,    21   b  are controllably movably mounted to an indexing machine  29 . The indexing machine  29  is controllably movable relative to the differential housing  7 . Once the differential assembly is loosely assembled, the indexing machine  29  is moved such that the rotary heads  21   a,    21   b  engage an associated one of the two gears of the adjusters  1 . Coordinated movement of the rotary tool head  21  relative to the indexing machine  29  and the indexing machine  29  itself is controlled electronically or manually until the rotary too head  23  engages the adjuster  1 . A plurality of position sensors  25  and load sensors (not shown) may be employed to automatically control the movement of the indexing machine  29  and rotary displacement and rotary movement of the tool heads  21   a,    21   b.  The rotary heads  21   a,    21   b  are first rotated in coordinated fashion to position or set the differential case  51  relative to the housing  7  which can be done manually or controlled by algorithm in response to sensed conditions. Once the differential case  51  is set, the rotary heads  23   a,    23   b  are rotated to achieve the desisted bearing preload.  
       FIG. 5  depicts a treaded adjuster  31  disposed between a bearing assembly  31  and the housing  7 . It is noted that only one threaded adjuster  1  is show. However, a second threaded adjuster is employed between the opposite bearing  33  assembly and the housing  7  in an identical fashion. The threaded adjuster  1  is formed of a substantially cylindrical body having threads  3  which engage corresponding threads  5  formed on the internal surface of the housing  7 . Simple rotation of the threaded adjuster  1  causes the cylindrical body to translate along a common central axis  13  concentric about the output shaft  60 . Thy threaded adjuster  1  includes a beveled gear  9  surface for engaging a corresponding beveled gear tool head  23 . The tool head is inserted to engage the beveled gear teeth  9  of the adjuster  1 . Rotation of the tool head  21  causes the adjuster  1  to rotate about its axis  13 . Rotation of the threaded adjuster  1  in turn causes the adjuster  1  to translate along its axis  13  and move relative to the housing  7  by virtue of the threaded engagement with the housing  7 . The tool head  21  may be rotated in either directed to cause the adjuster  1  to move into and out of engagement with the outer race of the bearing assembly  31 . As the adjuster  1  moves towards the right, the adjuster will increasingly bear against the bearing assembly  31 . One of ordinary skill in the art will recognize that coordinated movement of the two tool heads  21  thereby causes substantially identical rotation of the two threaded adjusters  1  which will cause the differential assembly (case  51 ) to translate parallel to/along the central axis  13  and thereby be selectively positioned to a predetermined positioned relative to the housing  7 . Simple inspection of the assembly of  FIG. 5  reveals that the case  51  may be displaced for selectively positioning and the ring gear  55  in desirable engagement with the pinion gear  57  of the input shaft  59 . The present invention contemplates initially installing the threaded adjusters  1  in a position widest apart from one another. A different case  51  with gear assembly is then roughly set in the housing  7 . Each of the threaded adjusters  1  is then selectively rotated to engage a corresponding bearing assembly  31 ,  33 . The mating tool heads  21   a,    21   b  may then be rotated in a coordinated fashion to simultaneously rotate the threaded adjusters  1  thereby displacing the entire case  51  assembly without significantly affecting bearing preload. Once the differential case  51  is positioned to a desired position, the mating tool heads  23   a,    23   b  are again selectively rotated to establish a predetermined preload to the bearing assemblies  31 ,  33 . Often the mating tool heads  21   a,    21   b  are rotated to cause the threaded adjusters  1  to each translate inward thereby increasing bearing preload without changing the position of the differential case  51 . Of course, the tool heads  21   a,    21   b  can be controllably rotated to reduce a load on the bearing assemblies  31 ,  33  as well. As previously mentioned each of the rotating mating tool heads  21   a,    21   b  are supported and rotatably driven by a common indexing machine  29 . Supporting rotatable tool heads on a common indexing machine is understood to those of skill in the art and need no be elaborated. The two mating tools  21   a,    21   b  simply need to be selectively displaceable relative to one another and selectively rotated on a common supporting tool  29 . The supporting tool  29  then simply needs to be able to move in a controlled fashion. Coordinated movement of such tool heads  21  on indexing machines  29  will be readily apparently top those skilled in the art thus enabling one to employ the present invention. The indexing machine  29  and rotation of the mating tools heads  21   a,    21   b  are then controlled to establish the proper position of the case  51  and bearing preload. For automatic operation, an electronic controller  27  may be employed to process signals from a plurality of position sensors  25  sensing the relative position of the case  51  assembly relative to the housing  7  and pinion gear  57  as well as the location of the indexing machine  27  and mating tool head  21  relative to the housing  7 . Off course manual control of the index machine  29  may also be employed. Load sensors (not shown) may also be employed for precisely sensing the preload in the bearing assemblies. In such instance, the controller processes signals from conventional load sensors and controls rotation of the mating tool heads  21   a ,  21   b  and consequently displacement of the threaded adjusters  1  until a desired preload is established. Such load sensors are known to those skilled in the art and need not be discussed further.  
      While the foregoing invention has been shown and described with reference to a preferred embodiment, it will be understood by those possessing skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. For example, as depicted in  FIGS. 2-3 , a bevel gear engagement is how. However, it is to be understood that spur gears may also be employed. In such instance to rotational axis of the tool head will shift ninety degrees. These and other departures are considered within the spirit and scope of the invention.