Patent Publication Number: US-8540305-B2

Title: Hollow torque rod for a closure panel

Description:
TECHNICAL FIELD 
     The present disclosure is drawn to a hollow torque rod for a closure panel. 
     BACKGROUND 
     A panel may be employed as a cover for a defined area to generate an enclosed compartment. Such a closure panel may be pivotably attached to the compartment for improved convenience during the panel&#39;s operation. Pivotable closure panels are commonly employed in vehicles for covering passenger, powertrain, and cargo compartments. A pivotable closure panel may be aided by a force-assist mechanism to facilitate the panel&#39;s operation during opening and/or closing of a compartment. Accordingly, a force-assist mechanism may increase operator convenience by reducing the effort required to open or close a compartment and may permit the use of a heavier closure panel. 
     SUMMARY 
     A compartment includes a plurality of side walls and a floor configured to define a storage area. The compartment also includes a panel operatively connected to the floor or to at least one of the plurality of side walls. The panel is configured to selectively expand and restrict access to the storage area. The compartment additionally includes a torque rod having a wall thickness, a hollow interior, a first end fixed relative to the storage area and a second end fixed relative to the panel. The torque rod is configured to store energy by being twisted when the panel is pivoted in a first direction relative to the storage area and release the stored energy when the panel is pivoted in a second direction that is opposite to the first direction to thereby assist operation of the panel. 
     The compartment may be a bed of a pick-up truck. In such a case, the panel may be a tailgate configured to selectively open and close access to the bed. The compartment may also be a trunk area of a vehicle, and, in such a case, the panel may be a trunk lid configured to selectively open and close access to the trunk area. 
     At least one of the first and second ends of the torque rod may include a compressed, substantially flat section. In such a case, the substantially flat section may be fixed relative to the storage area or to the panel, respectively. 
     Additionally, at least one of the first and second ends of the torque rod may include a solid segment, wherein the solid segment is at least one of pressed and welded into the hollow interior. The solid segment may include a keyed section, wherein the keyed section may be fixed relative to the storage area or to the panel, respectively. 
     The second end of the torque rod may include a formed loop and the formed loop of the second end may then be secured to the panel. 
     The compartment may also include a bracket fixed to at least one of the plurality of side walls and the floor. The first end of the torque rod may then be inserted into and be fixedly engaged by the bracket. 
     The first end of the torque rod may include a flange. The flange may then be fastened to at least one of the plurality of side walls and the floor. 
     The compartment may additionally include a hinge mechanism configured to pivotably connect the panel to one of the plurality of side walls and the floor. In such a case, the second end of the hollow torque rod may be fixed to the hinge mechanism. 
     A vehicle employing such a compartment is also provided. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cut-away rear perspective view of a vehicle having a storage compartment that includes a pivotable panel and a torque rod providing an assist force during operation of the panel, wherein the compartment is configured as a pick-up truck bed and the panel is configured as a tailgate; 
         FIG. 2  is a detailed close-up partially exploded perspective view of the torque rod shown in  FIG. 1 ; 
         FIG. 3  is a cut-away rear perspective view of a vehicle having a compartment that includes a pivotable panel and an alternative embodiment of the torque rod shown in  FIG. 1 , wherein the compartment is configured as a trunk area and the panel is configured as a trunk lid; and 
         FIG. 4  is a detailed close-up partially exploded perspective view of the torque rod shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  shows a vehicle  10  depicted as a pick-up truck. The vehicle  10  includes a vehicle body  12 . The vehicle body  12  defines a passenger compartment  14  and a storage compartment  16 . As shown in  FIG. 1 , the storage compartment  16  is configured as a bed of a pick-up truck and is generally adapted to carry bulky cargo. 
     The storage compartment  16  of  FIG. 1  is enclosed on four sides but, as shown, may be arranged without a top cover, and therefore remain unrestricted from above. The storage compartment  16  includes a plurality of generally vertical perimeter walls, shown as a side wall  18 , a side wall  20 , and a side wall  22 . The storage compartment  16  also includes a floor  24 . The side walls  18 ,  20 ,  22 , and the floor  24  are together configured to define a storage area  26 . The storage compartment  16  also includes a panel  28 . As shown in  FIG. 1 , the panel  28  is configured in one possible embodiment as a tailgate that is pivotably connected to the side walls  18  and  22  via bearing flanges  30  and  32 , respectively. Each of the flanges  30 ,  32  may be fastened to the respective walls  18 ,  22  via any appropriate fastener(s), such as a pair of screws (not shown). Alternatively, the panel  28  may also be pivotably connected to the floor  24  via an appropriate hinge mechanism (not shown). Accordingly, when pivoted, the panel  28  selectively expands and restricts access to the storage area  26 . 
     The storage compartment  16  additionally includes a torque rod  34 . The torque rod  34  is characterized by a cross-section having an outer diameter  35 , a wall thickness  36 , and a hollow interior  38 . The torque rod  34  also has a first end  40  fixed relative to the storage area  26 , a second end  42  fixed relative to the panel  28 , and a predetermined length  43  that spans the distance between the first end  40  and the second end  42 . The torque rod  34  is configured to store energy by being twisted when the panel  28  is pivoted in a first direction relative to the storage area  26 , wherein the first direction is identified by an arrow  44 . The torque rod  34  is formed from a suitable material that is capable of elastically withstanding torsion without taking a permanent set while being worked during operation of the panel  28 , for example spring steel. The torque rod  34  is also configured to release the stored energy when the panel  28  is pivoted in a second direction after being previously twisted in the first direction  44 , wherein the second direction is identified by an arrow  46 . As may be seen from  FIG. 1 , the second direction  46  is opposite to the first direction  44 . Accordingly, the release of the stored energy by the torque rod  34  when the panel  28  is pivoted in the second direction  46  provides a force assist for the operation of the panel. 
     In order to achieve the desired force to assist the operation of the panel  28 , each of the first end  40  and the second end  42  is specifically configured in order to fix the first end relative to the storage area  26  and second end relative to the panel  28 . As shown in  FIG. 2 , the first end  40  may include a solid segment  48  with a keyed section  50 , wherein the solid segment is fixed inside the hollow interior  38 . The solid segment  48  may first be inserted into the hollow interior  38 , and then be either pressed or welded therein. The first end  40  is then fixed to the bearing flange  32  via the keyed section  50 , such that the flange  32  effectively becomes part of the first end. As additionally shown in  FIG. 2 , the second end  42  of the torque rod  34  may include a compressed, substantially flat section  52 . The substantially flat section  52  may then be clamped to the panel  28  via a fastening device  54 , thus restricting movement of the second end  42  relative to the panel. Furthermore, each of the first and second ends  40  and  42  may include either the solid segment  48  with a keyed section  50  or the compressed, substantially flat section  52  fixed inside the hollow interior  38  depending on the retention requirements of each end. 
     When the panel  28  is pivoted in the first direction  44  from the position where access to the storage area  26  is restricted, the torque rod  34  is twisted because while the first end  40  is securely tied to the side wall  18 , the second end  42  is rotated with the panel. The action of operating the panel  28  to expand the storage area  26  stores energy in the torque rod  34  under the mass of the panel being lowered in the first direction  44 . Conversely, when then panel  28  is operated in the second direction  46  to restrict access to the storage area  26 , the torque rod  34  is permitted to release the stored energy and thus assist with raising the panel. The overall diameter  35 , the wall thickness  36 , and the length  43  are all selected to provide the torque rod  34  with a desired spring rate such that the twisting of the torque rod may generate a useful force assist in raising the panel  28 . 
       FIG. 3  illustrates a vehicle  60  including a vehicle body  62  that has a passenger compartment  64  and a storage compartment  66  that is configured as a trunk area  66 . The storage compartment  66  includes a plurality of generally vertical perimeter walls, shown as a side wall  68 , a side wall  70 , and a side wall  72 . The storage compartment  66  also includes a floor  74 . The side walls  68 ,  70 ,  72 , and the floor  24  are together configured to define a storage area  76 . The storage compartment  66  also includes a panel  78 . As shown in  FIG. 3 , the panel  78  is configured as a trunk lid that is pivotably connected to the wall  70  via a hinge mechanism that includes hinges  80  and  82 . Accordingly, when pivoted, the panel  78  selectively expands and restricts access to the storage area  76 . 
     The storage compartment  66  additionally includes a pair of torque rods  84 . Each of the torque rods  84  has a generally similar function and structure to the torque rod illustrated and described with respect to  FIGS. 1-2 . Two torque rods  84  are being used in the application of  FIG. 3  in order to balance out the reaction forces being seen at each hinge  80  and  82  from the twisting action of the respective torque rods, such that the panel  78  is not being lifted or raised unevenly. Each torque rod  84  is characterized by a cross-section having an outer diameter  85 , a wall thickness  86 , and a hollow interior  88 . Each torque rod  84  also has a first end  90  fixed relative to the storage area  76 , a second end  92  fixed relative to the panel  78 , and a predetermined length  93  that spans the distance between the first end  90  and the second end  92 . 
     The torque rods  84  are configured to store energy by being twisted when the panel  78  is pivoted in a first direction relative to the storage area  76 , wherein the first direction is identified by an arrow  94 . Like the torque rod  34  of  FIGS. 1-2 , each torque rod  84  is formed from a material capable of elastically withstanding torsion without taking a permanent set while being worked during operation of the panel  78 . Torque rods  84  are also configured to release the stored energy when the panel  78  is pivoted in a second direction after being previously twisted in the first direction  94 , wherein the second direction is identified by an arrow  96  and is opposite to the first direction  44 . Accordingly, similar to the torque rod  34 , the release of the stored energy by torque rods  84  when the panel  78  is pivoted in the second direction  96  provides a force assist for the operation of the panel. 
     As shown in  FIG. 3 , the storage compartment  66  additionally includes a pair of brackets  98 . Each bracket is fixed to the side wall  70 , as shown, or may be fixed to a shelf (not shown) that spans the distance between the side walls  68  and  72 . Each first end  90  includes a shape that is specifically configured to be inserted into and be fixedly engaged by the respective bracket  98 . Each second end  92  of the torque rods  84  is rotatably fixed to the respective hinge  80  and  82  via a link  100 . Each link  100  captures an individual second end  92  and is configured to urge the respective second end in the first direction  94  to thereby twist the respective torque rod  84  during operation of the panel  78 . Either of the second ends  92  may also be directly connected to the respective hinge  80  without using the link  100  such that the hinge itself induces the required twist in the torque rod  84 . To facilitate the capture of the second end  92  by the respective link  100 , each second end may include a formed loop that is engaged by the respective link. Accordingly, each first end  90  is fixed relative to the storage area  76  and each second end  92  is fixed relative to the panel  78  such that a desired assist force may be achieved during operation of the panel  78  in the second direction  96 . Additionally, as shown in  FIG. 3 , the storage compartment  66  may also include a holder  102 . The holder  102  may be fixed relative to the storage area  76  by being fastened to the side wall  70  in order to contain the torque rods  84  and prevent the torque rods from rubbing against one another during operation of the panel  78 . 
     When necessary for retention of the first and second ends  90 ,  92 , the first and second ends of the torque rods  84  may be provided with the configurations disclosed above for the first and second ends  40 ,  42  of the torque rod  34 . Accordingly, each of the first and second ends  90  and  92  may include either a compressed, substantially flat section  48  or a solid segment  50  with a keyed section  52  fixed inside the hollow interior  88 . 
     When the panel  78  is pivoted in the first direction  94  from the position where access to the storage area  76  is expanded, each torque rod  84  is twisted. The twisting of each torque rod  84  is induced in response to each second end  92  being rotated with the panel while each first end  90  is securely tied to the stationary part of the compartment  66 , such as the side wall  70 . The action of operating the panel  78  to restrict the storage area  76  stores energy in the torque rod  34  under the mass of the panel being lowered in the first direction  94 . Conversely, when then panel  78  is operated in the second direction  96  in order to restrict access to the storage area  66 , each torque rod  84  is permitted to release the stored energy and thus assist with raising the panel. The overall diameter  85 , the wall thickness  86 , and the length  93  are all selected to provide the torque rod  84  with a desired spring rate such that the twisting of the torque rod may generate a useful force assist in raising the panel  78 . 
     Generally, either storage compartment  16  or  66  may employ the torque rod configuration and attachment method disclosed with respect to the other compartment. However, despite all the possible configurations, each of the torque rods  34  and  84  employ a hollow interior,  38  and  88 , respectively. The hollow interiors  38  and  88  permit the torque rods  34  and  84  to generate appropriate force assist for operation of the respective panels  28  and  78  at reduced weight but without loss in durability as compared with a torque rod having a solid core. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.