Patent Publication Number: US-6209183-B1

Title: Bushing installation tool

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a rack and pinion steering gear assembly and, in particular, is directed to a tool for installing a rack bushing into a housing of an electric power assisted rack and pinion steering gear assembly. 
     2. Description of the Prior Art 
     A typical electric power assisted rack and pinion steering gear assembly for a vehicle includes a rack which extends axially through a housing. The ends of the rack project from the ends of the housing and are connected with steering linkage which connects to steerable vehicle wheels. The rack is supported at one end of the housing for axial movement within the housing upon actuation of an electric motor. This support is provided by a rack bushing that is received and supported in an outboard end portion of the housing. 
     SUMMARY OF THE INVENTION 
     The present invention is a tool for installing a bushing into a housing of a rack and pinion steering system. The housing has an end portion that includes a ring-shaped bushing chamber and a circular opening into the bushing chamber. The opening has a first diameter, and the bushing chamber has a second diameter greater than the first diameter of the circular opening. The bushing is radially compressible between a first, fully expanded state and a second, fully compressed state. The bushing when in the bushing chamber is partially expanded. 
     The tool comprises a plunger having a first portion with an outer diameter that is less than the first diameter of the opening in the housing. The first portion of the plunger has a circumferential groove defined by a pair of annular end surfaces extending radially inward from the outer surface and a cylindrical base surface extending axially between the end surfaces at a location radially inward of the outer surface. The groove receives the bushing during installation of the bushing in the housing. The annular end surfaces of the groove block axial movement of the bushing along the first portion of the plunger while the bushing is on the plunger. The tool also includes a sleeve slidable along the first portion of the plunger to radially compress the bushing and hold the bushing in the groove during installation of the bushing in the housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein: 
     FIG. 1 is a schematic view of a vehicle rack and pinion steering gear including a housing supporting a rack bushing; 
     FIG. 2 is a sectional view of a portion of the housing including the bushing and also showing a bushing installation tool constructed in accordance with the present invention; 
     FIG. 3 is a view similar to FIG. 2 showing the bushing partially installed; and 
     FIG. 4 is a view similar to FIG. 3 showing the bushing completely installed. 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
     The present invention relates to a rack and pinion steering gear and, in particular, is directed to a tool for installing a bushing in a housing of an electric power assisted rack and pinion power steering gear. The present invention is applicable to various tool constructions. As representative of the present invention, FIG. 2 illustrates a tool  10 . 
     The tool  10  is used for installing a bushing  20  (FIG. 2) in a housing  30  of a rack and pinion power steering gear  32 . The steering gear  32  is connected with a pair of steerable vehicle wheels (not shown) in a known manner by steering linkage  34  at opposite ends of the steering gear. 
     In addition to the housing  30 , the steering gear  32  includes a pinion  36  and a rack  38 . The housing  30  has a rack portion  40  and a transversely extending pinion portion  42 . The pinion  36  is disposed in the pinion portion  42  of the housing  30 . The pinion  36  has teeth (not shown) which meshingly engage teeth  43  on the rack  38  inside the housing  30  at the intersection of the pinion portion  42  and the rack portion  40 . 
     The rack portion  40  of the housing  30  has a tubular, cylindrical configuration centered on an axis  44 . The housing  30  has a main body portion  46  and an outboard end portion. The main body portion  46  of the housing defines a motor chamber  52  (FIG. 2) within the housing  30 . 
     The rack  38  is centered on the axis  44  and extends axially through the motor chamber  52 . The rack  38  has a cylindrical outer surface  54 . Opposite ends of the rack  38  project axially beyond the end portions  48  and  50  of the housing  30  and are connected to the steering linkages  34 . 
     An electric motor shown schematically at  56  is drivingly associated with the rack  38  inside the motor chamber  52 . Upon rotation of the vehicle steering wheel  57 , the motor  56  is actuated, causing the rack  38  to move axially within the housing  30 . Such axial movement of the rack  38  in opposite directions moves the steering linkages  34  in opposite directions, and thus turns the steerable wheels in opposite directions. 
     The outboard end portion  50  of the housing  30  has an outer end surface  58  that extends transverse to the axis  44 . A circular opening  60  is formed in the end surface  58 . The opening  60  is centered on the axis  44 . The opening  60  has a first diameter. The rack  38  (not shown in FIGS. 2-4) extends out of the housing through the opening  60 . 
     The end portion  50  of the housing  30  includes a cylindrical surface  62  that extends axially inward from the opening  60 . The surface  62  defines a cylindrical passage  64  into the housing  30 . The diameter of the passage  64  is the same as the first diameter of the circular opening  60 . 
     The end portion  50  of the housing  30  includes an annular surface  66  that extends radially outward from the inner terminus of the cylindrical surface  62 . Another cylindrical surface  68  extends axially inward from the annular surface  66 , and another annular surface  70  extends radially inward from the cylindrical surface  68 . The two annular surfaces  66  and  70  and the cylindrical surface  68  together define a ring-shaped or an annular bushing chamber  72  in the end portion  50  of the housing  30 . The bushing chamber  72  is centered on the axis  44 . The bushing chamber  72  has a second diameter, defined by the cylindrical surface  68 , that is greater than the first diameter of the circular opening  60 . 
     The tool  10  includes a plunger  80 . The plunger  80  is preferably made from metal and has a central portion  82  with a cylindrical outer surface  84 . The plunger  80  has a cylindrical trailing end portion  86  separated from the central portion  82  by an annular shoulder surface  88 . The trailing end portion  86  of the plunger  80  thus has a larger diameter than the central portion  82 . 
     The plunger  80  has a leading end portion  90  opposite the trailing end portion  86 . A circular, radially extending end surface  91  of the plunger  80  is located on the leading end portion  90 . The leading end portion  90  of the plunger  80  has a cylindrical outer surface  92 . The leading end portion  90  of the plunger is the same diameter as the central portion  82 . The diameter of the leading end portion  90  is less than the first diameter of the housing opening  60  and, therefore, is less than the second diameter of the bushing chamber  72 . 
     A groove  94  is formed in the central portion  82  of the plunger  80  and defines the inner end of the leading end portion  90  of the plunger. The groove  94  extends circumferentially around the plunger  80 . The groove  94  is defined by a pair of annular, radially extending end surfaces  96  and  98  spaced apart at opposite ends of a base surface  100 . The base surface  100  is cylindrical and centered on the axis  44 . 
     The base surface  100  of the groove  94  has a substantially smaller diameter than the central portion  82  and the leading end portion  90  of the plunger  80 . The length of the groove  94 , that is, the axial distance between the end surfaces  96  and  98  of the groove, is the same as or slightly larger than the length of the bushing  20 . The groove  94  is thus long enough to accommodate the bushing  20  but short enough to block axial movement of the bushing along the plunger  80 . 
     The tool  10  includes a sleeve  110 , The sleeve  110  is supported on the central portion  82  of the plunger  80  for axial sliding movement along the plunger. The sleeve  110  has a tubular main body portion  112 . The main body portion  112  has a cylindrical inner surface  113  that is in abutting sliding engagement with the cylindrical outer surface  84  of the central portion  82  of the plunger  80 . 
     The sleeve  110  has a frustoconical cam surface  114  that flares radially outward from the cylindrical surface  113  to an annular, radially extending leading end surface  116  of the sleeve. The inner diameter of the sleeve leading end surface  116  is greater than the first diameter of the housing opening  60 . At the other end of the sleeve  110  a gripping flange  118  extends radially outward from the main body portion  112 . 
     The tool  10  includes a spring  120 . The spring  120  is received in a cylindrical recess  122  in the leading end portion  90  of the plunger  80 , between the groove  94  and the end surface  91 . The outer end of the recess  122  is crimped over to hold the spring  120  and a ball  124  in the recess  122 . The spring  120  biases the ball  124  radially outward in the recess  122  so that a small portion of the ball normally projects from the outer surface  92  of the leading end portion  90  of the plunger  80 . The ball  124  holds the sleeve  110  on the plunger  80 . 
     The bushing  20  is molded as one piece from a resilient plastic material. The bushing has a generally cylindrical shape including cylindrical inner and outer side surfaces  130  and  132  extending parallel to the axis  44 . The bushing  20  also has annular first and second end surfaces  134  and  136  extending radially between the inner and outer side surfaces  130  and  132 . 
     The bushing  20  is a split bushing having a slot  138  that extends between the opposite ends of the bushing. The slot  138  extends at an acute angle to the axis  44 . Because of the presence of the slot  138 , the bushing  20  is radially compressible and expandable. 
     The bushing  20  has a free or unrestrained condition in which it is resiliently expanded to its largest diameter. When the bushing  20  is in the unrestrained condition, the inner diameter of the bushing is greater than the outer diameter of the leading end portion  90  of the plunger  80 . The outer diameter of the unrestrained bushing  20  is greater than the first diameter of the housing opening  60  and also is greater than the second diameter of the bushing chamber  72 . Thus, the bushing  20  can not be installed into the bushing chamber  72  unless it is radially compressed. 
     The bushing  20  has also a fully compressed condition. In this condition, the outer diameter of the bushing  20  is smaller than the outer diameter of the leading end portion  90  of the plunger  80 . 
     The bushing  20  has an installed condition when it is located in the bushing chamber  72 . When the bushing  20  is in the installed condition, the cylindrical outer surface  132  of the bushing  20  is in abutting engagement with the cylindrical outer surface  68  of the bushing chamber  72 . As a result, the outer diameter of the bushing  20  when it is in the installed condition is equal to the second diameter of the bushing chamber  72  and is greater than the first diameter of the housing opening  60 . 
     The cylindrical inner surface  130  of the bushing  20  slidably receives the cylindrical outer surface  54  of the rack  38 . The bushing  20  thus supports the rack  38  for sliding movement relative to the housing  30 . 
     The annular surface  66  and the cylindrical surface  62  on the housing end portion  50  define an annular lip  140  disposed axially outward of the bushing chamber  72 . The lip  140  has an inner diameter, which is the diameter of the opening  60  and of the passage  64 , that is less than the outer diameter of the bushing chamber  72 . Thus, when the bushing  20  is in the bushing chamber  72 , the annular surface  66  on the lip  140  blocks axial movement of the bushing out of the bushing chamber and, therefore, out of the housing  30 . 
     To use the tool  10 , the operator slides the sleeve  110  axially toward the shoulder  88  of the plunger  80 , exposing the groove  94 . The operator then takes a bushing  20  that is in the unrestrained condition and slides it axially over the leading end portion  90  of the plunger  80 , in a direction from the end surface  91  toward the sleeve  110 . 
     The bushing  20  is positioned over the groove  94  in the plunger  80 . The bushing  20  in this unrestrained condition is larger in diameter than the leading end portion  90  and the central portion  82  of the plunger  80 . 
     Thus, the bushing  20  slides freely along the plunger  80  but does not drop into the groove  94 . 
     The sleeve  110  is then moved axially along the central portion  82  of the plunger  80 , toward the leading end portion  90 . As this movement occurs, the cam surface  114  on the sleeve  110  engages the bushing  20  and compresses the bushing radially inward into the groove  94  in the plunger  80 . (It may be necessary to start compressing the bushing manually prior to engaging it with the sleeve  110 .) When the sleeve  110  moves far enough so that the cylindrical inner surface  113  on the sleeve engages the bushing  20 , the bushing is radially compressed completely into the groove  94 . The bushing  20  then has an outer diameter than is less than or equal to the outer diameter of the leading end portion  90  of the plunger  80 . 
     The sleeve  110  holds the bushing  20  in the groove  94  for the next steps of the installation process. The tool  10 , with the bushing  20  in place, is moved into an installation position adjacent the housing end portion  50 , as shown in FIG.  2 . The tool  10  is positioned relative to the housing end portion  50  so that the axis of the tool is collinear with the axis of the housing end portion. The tool  10  is moved along this line toward the housing end portion  50 . 
     The leading end portion  90  of the plunger  80  moves through the opening  60  and into the passage  64  radially inward of the lip  140 . The plunger  80  continues this movement until the leading end surface  116  of the sleeve  110  engages the outer end surface  58  of the housing portion  50 . This engagement stops further movement of the sleeve  110  into the housing  30 . 
     The plunger  80  is then pushed farther into the opening  60 , moving relative to the sleeve  110 . The leading end portion  90  and the central portion  82  of the plunger  80  have outer diameters less than the outer diameter of the opening  60  into the housing  30 . As a result, the plunger  80  freely moves into and through the opening  60  and the passage  64 . This movement of the plunger  80  carries the bushing  20  completely through the opening  60  and the passage  64  and into a position radially inward of the bushing chamber  72 . The bushing  20  then springs radially outward into its installed condition in the bushing chamber  72 . The cylindrical outer surface  132  of the bushing  20  is in engagement with the cylindrical outer surface  68  of the bushing chamber  72 . The annular end surfaces  134  and  136  of the bushing  20  are in engagement with the annular end surfaces  66  and  70 , respectively, of the bushing chamber  72 . The lip  140  blocks axial movement of the bushing  20  out of the bushing chamber  72 . 
     At this point, the tool  10  can be withdrawn from the housing end portion  50 . Because the leading end portion  90  and the central portion  82  of the plunger  80  have outer diameters that are smaller than the outer diameter of the opening  60  into the housing  30 , the tool  10  slides freely out of the opening. 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.