A tailgate counterbalancing hinge assembly includes a linear torque rod, a first end assembly and a second end assembly. One end assembly pivotally retains the tailgate while permitting the torque rod to be rigidly coupled to the tailgate for movement with the tailgate about a pivot axis. The other end assembly pivotally retains the tailgate and permits the end of the torque rod o be rigidly retained with respect to the vehicle body. The assemblies are easily mounted in the vehicle using brackets that are secured to the tailgate and a vehicle body hinge pin to simplify installation and repair of the assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of International Application No. PCT/US04/06262, filed on Mar. 2, 2004, which is a continuation of U.S. application Ser. No. 10/386,884, filed Mar. 12, 2003, now U.S. Pat. No. 6,796,592 B1. 


   BACKGROUND OF THE INVENTION 
   The present invention relates to vehicle body closure panels, in which a torque rod with end assemblies forms a counterbalanced pivot connection between a tailgate and vehicle body pillars, the counterbalance biasing the torque rod to an unbiased tailgate position permitting tailgate removal from the vehicle body. 
   Vehicle body closure members, such as a tailgate, are pivotally mounted between body side panels forming the pillars at the rear of the vehicle. The tailgate pivots about a hinge axis between a horizontal, open position and a vertical, closed position. The mounting assemblies for the tailgate permit the tailgate to be removed. For example, the tailgate may include hinge pins that extend outwardly along the hinge axis that removably connect into brackets carried on the vehicle body. When the tailgate is pivoted to a predetermined intermediate position between open and closed, at least one of the hinge pins slips through a slot in the connecting bracket as the tailgate is lifted at one end from the truck body. 
   Several known tailgate mounting assemblies include a spring bias for assisting movement and counterbalancing the weight of a tailgate during opening and closing movements. In one example, a torque rod provides spring biasing between the tailgate and the vehicle body side pillars. Disadvantageously, the torque rod forms a portion of the pivot assembly and, therefore, is typically pre-installed into the tailgate before mounting the tailgate between the side pillars. This complicates the assembly procedure. Moreover, the torque rod may require particularly configured ends that complicate production of the parts before assembly. 
   Another known tailgate uses hinge pin trunions for pivoting, and the torque rod is preformed and installed into the tailgate in a complex and intricate procedure. For example, during assembly of the tailgate, one end of the rod has to be aligned with an aperture that exposes the end for attachment outside of the tailgate while the other end is aligned with a reinforcement plate located inside the tailgate. All of the aligning must be performed while the torque rod is carried within the interior of the tailgate and the procedure may be difficult and time consuming. Moreover, numerous auxiliary components are required to assemble the torque rod to the tailgate. 
   Other types of springs that are used in place of the torque rod are difficult to install within the confines of tailgates made of inner and outer panels that are joined together before the hinge assembly is mounted. Moreover, such assemblies may be difficult to repair and replacement parts are complex and expensive. 
   There is a need for a simplified tailgate hinge mechanism that is less complex and less laborious to install. This invention addresses these needs and provides enhanced capabilities while avoiding the shortcomings of the prior art. 
   SUMMARY OF THE INVENTION 
   A tailgate counterbalancing hinge includes a torque rod having first and second end assemblies, at least one of the end assemblies being readily attachable to and removable from the torque rod. The first end assembly includes a first support for pivotally carrying the tailgate adjacent to a body side panel. The first support includes a cup, and a retainer bushing pivotally received by said cup. The bushing includes a stem for locking said bushing with respect to the tailgate. The second end assembly includes a second support for pivotally carrying a tailgate adjacent to an opposite body panel. The second support includes a key and a spriget that combines the key with a mounting stem for securing the key to the body panel. A pivot body includes a slot aligned for reception of the key. A bushing is received in an opening in said tailgate and carries the pivot body. The torque rod has a first end securely received in the first end assembly for movement with the bushing, and a second end securely received in the second end assembly by the pivot body. 
   In one example, the torque rod includes a faceted cross-section at least at one end. The cross-section may be longitudinally continuous for ease of manufacture of the torque rod or may be formed only on parts of the rod. 
   One example method for assembling a selectively removable tailgate between vehicle body panels receiving a first end of the torque rod in a retainer bushing with a faceted cross-section receiver, receiving a second end of the torque rod in a cup with a faceted cross-section receiver, retaining the retainer bushing with respect to the tailgate, and retaining the cup by slidably receiving the cup with respect to a spriget fixed to a body pillar. By sliding the retainer bushing over a spriget's key, fixed to the vehicle body pillar, the pillar pivotally supports a retainer bushing. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more clearly understood by reference to the following detailed description of a preferred embodiment when read in conjunction with the accompanying drawing in which like reference characters refer to like parts throughout the views and in which: 
       FIG. 1  shows a perspective view of a vehicle having a tailgate assembly. 
       FIG. 2  shows a cross-sectional view of selected portions of an example hinge assembly. 
       FIG. 3  shows an exploded view of the hinge assembly of  FIG. 2 . 
       FIG. 4  shows an exploded view of selected portions of another example hinge assembly embodiment. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , an example motor vehicle  10  is shown having a vehicle body  12  that includes a rear compartment or bed  14  enclosed by side panels  16  and  18  as well as a tailgate  20 . A counterbalance hinge assembly  22  pivotally supports the tailgate  20  between the side panels  16  and  18  in a manner to be described in greater detail below. 
   The tailgate  20  is pivotally supported between pillars formed by the side panels  16  and  18 . In the example shown, side panels  16  and  18  and the tailgate  20  are formed by respective inner and outer panels  24  and  26  of sheet metal joined at the ends by overlapping flanges or the like. In other examples, other materials may be used in constructing the side panels  16  and  18  and the tailgate  20 . 
   The example counterbalance hinge assembly  22  includes a torque rod  30 , which is linear and aligned along a pivotal axis between the side panels  16  and  18 . The torque rod  30  carries first and second end assemblies  32  and  34 . The first and second end assemblies  32  and  34  enable the torque rod  30  to be secured with respect to the tailgate  20  at one end, and with respect to the side panels  16  and  18  at a second end. 
   In the example shown in  FIG. 2 , the first end assembly  32  pivotably supports the tailgate  20  at the left body pillar including inner panel  24 . The first end assembly  32  forms a left side vehicle hinge pin that includes a pivot member  40  having a cylindrical boss  42  and a mounting stem  44 . The mounting stem  44  secures the pivot member  40  to the vehicle pillar at the inner panel  24 . In one example, the stem  44  may be a square housing received in a square opening in the inner panel  24  of the left side panel  16 , and secured in position by welds, adhesive or other fasteners. In other examples, the stem  44  may include a threaded member that is received in a weld nut  45  mounted on a surface of the inner panel  24 . 
   The first end assembly  32  receives an end of the torque rod to be secured to the tailgate  20 . This connection includes a bushing  46 , which is pivotally or rotatably received about the cylindrical boss  42 . In one example, the bushing  46  includes a cylindrical receptacle  48  and a stem  50 . The stem  50  includes an exterior configuration that is faceted to be retained in an opening  52  in a tailgate wall  23  of the tailgate  20 . As used herein, a facet refers to any cross-section having at least one surface discontinuity that prevents rotation within a correspondingly shaped, compatible piece. In other examples, the bushing  46  is welded or otherwise attached to the tailgate wall  23 . 
   One example stem  50  is modified or faceted to mount to the tailgate  20 . 
   In another example, the surface of the receptacle  48  may fit in an enlarged opening in the tailgate wall  23  aligned with the pivotal axis and extending through a portion of the tailgate wall  23 . The receptacle  48 , or the stem  50  may be configured exteriorly or otherwise fastened to avoid relative rotation between the bushing  46  and tailgate wall  23  so that the bushing  46  that receives the torque rod pivots with the tailgate  20 . 
     FIG. 3  illustrates an exploded view of the example counterbalance hinge assembly  22  of  FIG. 2 . The stem  50  includes a chamber  66  that receives an end portion of the torque rod  30 . The end portion is faceted and corresponds to the chamber  66  as shown to lock the bushing  46  to the torque rod  30 . In one example, the torque rod  30  comprises a hexagonal shaft end and the opening  66  is compatibly configured to avoid relative rotation between the bushing  46  and the torque rod end  67 . 
   The second end assembly  34  includes a vehicle hinge pin for pivotally carrying the tailgate  20  adjacent to the right side panel  18  and includes a spriget  70 . The spriget  70  combines a key  78  with a mounting stem  72  for securing the key  78  to the right hand side panel  18 . The mounting stem  72  is received in an opening  76 . A fastener such as nut  77  ( FIG. 2 ) or the like may be used to fasten the stem  72  to the side panel  18 . The key  78  has an elongated shape, the elongated shape being aligned in a direction intermediate the vertical, closed and the horizontal, open positions of the tailgate  20  to define a removal direction along the elongated axis of the key body  78 . The key  78  is received in the slot  83  of a bushing  90  and in the slot  84  of the pivot body  80 . 
   The second end assembly  34  also includes a pivot body  80  having a cylindrical body  82  with a radial slot  84  aligned for reception of the key  78 . The pivot body  80  includes a stem  86  having a chamber  88  adapted to receive and secure the right end  87  of the torque rod  30 . The assembly  34  also includes a bushing  90  which can be mounted within an opening  85  of the tailgate wall  23 . The bushing  90  includes a chamber  92  adapted to pivotally receive body  82  of the pivot body  80 . In one example, the bushing  90  includes a stem  94  received in the correspondingly configured opening  85 . The configuration of the opening  85  may non-rotatably retain the bushing  90  in the inner wall of the tailgate  20 . The bushing  90  may be retained in the opening  85  by a retainer, for example, a snap ring  91  engaged in a groove on the stem  94 . In one example, the stem  86  includes a groove  89  that receives a snap ring  91  at a position adjacent the end of stem  94 . 
   When assembled, the right hand end  87  of the torque rod  30  is retained in a stationary position by the pivot body  80  passing through the bushing  90  mounted in the tailgate  20 . The rigid connection to the body side panel  18  is made by the bracket  74  and spriget  70  as assembled as discussed above. The left hand end  67  of the torque rod  30  is retained by the tailgate wall  23  to move with the tailgate  20 . Thus, as the tailgate  20  is moved between the upright, closed position and the horizontal, open position, the torque rod  30  twists. 
   In one example, the unbiased position of the torque rod  30  occurs when the tailgate  20  is aligned with the elongated axis of the key  78 , whereby spring tension is introduced to pivot the tailgate  20  away from the closed position when it is unlatched, and to raise it to the closed position when it has been unlatched from its open position. 
     FIG. 4  is an exploded view of another example counterbalance hinge assembly  22  with demonstrates a modification that eases assembly and repair. The stem  50  of the bushing  46  is correspondingly sized to fit in the opening  85  of a tailgate panel attachment bracket  54 . The attachment bracket  54  may provide the benefit of reinforcing the end panel of the tailgate and simplifying the formation of opening  52  that receives the bushing  46 . Rather than trying to form a properly sized and configured opening  56  in the tailgate wall  23 , the bracket  54  with opening  85  is placed next to an enlarged opening  56  in the tailgate wall  23 . The openings  85  and  56  are aligned with the pivotal axis extending through the tailgate  20 . In one example, an upper flange  58  is bolted to the tailgate wall  23  of the tailgate  20  with a bolt and nut  60  and  62 . In other examples, welds or other fasteners secure the flange  58 . The opening  85  is configured to avoid relative rotation between the stem  50  and the opening  56  such that when assembled, both the installation bracket  54  and the bushing  46  pivot with the tailgate  20 . 
   The bracket  54  includes a releasable engagement clamp  104  on a flange  64  that is angled relative to the flange  58 . The clamp  104  includes a clamp seat  106  raised up through the tailgate wall  23  to align the clamp  104  on the pivotal axis. In the example shown, the bracket  54  includes an offset arm, bent as shown, to provide a raised position for the clamp  104  above the plane of the flange  64 . 
   The seat  106  includes a cavity  108  which is aligned with the pivotal axis extending through the opening  56  and the bushing  46 . A clamping flange  110  includes a recess  112  configured in compliance with the faceted segment of the torque rod  30  such that clamping of the flange  110  against the clamping seat  106  rotationally fixes the torque rod  30  with respect to the bracket  54 , and thus the tailgate  20 . 
   The raising of the clamp  104  to align the axis of the torque rod  30  with the pivotal axis by the raised seat  106  provides room for fasteners, such as the head of a rivet extending through aligned apertures in the seat  106  and the flange  110 . In one example, a single rivet  114  is used to retain one side of the flange  110  with the seat  106 . On the opposite side, the flange  110  includes a weld nut  116  that threadably receives a fastener  118  extending from beneath the seat  106 . 
   The opening  119  in a bracket  96  is aligned with opening  98 , and mounted to the outside of the tailgate wall  23 . The bushing  90  carried by the bracket includes a chamber  92  adapted to pivotally receive body  82  of the pivot body  80 . In one example, the bushing  90  includes a stem  94  received in the correspondingly configured opening  119 . The configuration of the opening  119  rotationally fixes the bushing  90  to the tailgate wall  23 . As a result, the counterbalance hinge assembly  22  may provide the benefit of loose assembly, and thus can be positioned before spring tension is applied to the counterbalance hinge assembly  22 . 
   In one example assembly method, brackets  54  and  96  are attached to the tailgate  20 , by welding such that configured openings  85  and  119  align with the openings  52  and  98  in the tailgate wall  23 . This may beneficially enable configured openings  85  and  119  to be preferably sized, shaped and positioned after the tailgate has been manufactured, and overcomes the difficulty of shaping, sizing and aligning the apertures of the original tailgate panel stampings. The fastener  118  is initially installed in a pre-production or fabrication assembly procedure, for example, and left loose for tightening at the assembly plant. At the assembly plant, the entire bracket  54  is secured by welding or other fastening means to the tailgate  20 . An aperture at the bottom of the tailgate receives the clamp  104  of the bracket  54 . The torque rod  30 , carrying pivot body  80  at end  87 , is positioned such that end  67  is inserted through opening  98  to extend across the vehicle body  12  through the tailgate  20  and into the faceted, complementary hole formed by the recesses  112  and  108 . The torque rod  30  is inserted through the bushing  90 , which is already attached to bracket  96  in a prior operation. The fastener  118  is then tightened to provide proper biasing between the vertical, closed and horizontal, open positions. 
   The assembly discussed above provides an assembly for simply removably mounting a closure member between spaced apart body side panels of a vehicle body by using a linear torque rod extending across the tailgate. The assemblies provide means for connecting the torque rod in driving engagement with the vehicle body hinge pin within the bushing and independently of the rotatable support of the bushing on the hinge pin. The illustrative examples permit the bushing  90  to be received laterally downwardly over at least a portion of the vehicle body hinge pin when the tailgate  20  is in the removal position. Accordingly, the torque rod  30  is twisted in tension when the closure member is pivoted to either the closed or open positions from the removal position. This tension provides a counterbalancing effort to assist with pivotal movement of the tailgate  20 . The counterbalance hinge assembly  22  may permit facile removal of the closure member from the vehicle body when the closure member is in the removal position. 
   Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.