Abstract:
A torsion hitch receiver is provided having a frame that has a portion that mounts to a vehicle. The frame includes an upper torsion tube that carries an upper torsion bar. Attached to the upper torsion tube is a torsion housing that affixes a lower torsion tube. The upper torsion bar has an upper torsion arm that rotates with the upper torsion bar, and a lower torsion bar, carried within the lower torsion tube, the lower torsion bar has lower torsion arms. Both upper and lower torsion arms attach to a receiver housing that can receive a draw bar. As weight is applied to the receiver housing, the torsion bars allow rotation. As the torsion bars rotate, the receiver housing moves up and down.

Description:
BACKGROUND OF THE INVENTION 
     This present disclosure relates to vehicle mounted hitch receivers and the attachment between a trailer and a towing vehicle. Commonly, when being towed by a vehicle, the trailer is subject to transient forces as the towing vehicle pulls the trailer over various terrain or when loads are moved or placed on the trailer. Trailers have a tongue weight that is borne by the towing vehicle. Some tongue weight is necessary but it is desirable to limit the amount transmitted to the towing vehicle. The transient forces on the trailer can translate to transient tongue forces transmitted to the towing vehicle, at the very least, can be unsettling to the driver. In an extreme situation, the transient tongue forces can create a dangerous loss of control. One option is to use a receiver adapter that can be located between the trailer and the towing vehicle, but the adapter increases the distance between the vehicle and the trailer. An improved receiver is needed. 
     SUMMARY OF THE INVENTION 
     The present disclosure describes a vehicle mounted torsion hitch receiver that will permanently attach to a towing vehicle and absorb transient tongue loading either caused by the towing vehicle or the trailer. By implementing a torsion device, the hitch receiver allows for limited relative vertical motion between the towing vehicle and the trailer tongue. The hitch receiver has multiple receiver holes that are vertically stacked to give the user several height options of where to connect up a ball. The vertical stacking is frequently necessary when the trailer tongue height varies from trailer to trailer, and also the height of the receiver on different towing vehicles is different. An optional indicator measures the displacement between a loaded position and an unloaded position to allow the user to monitor tongue loading. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of this invention has been chosen wherein: 
         FIG. 1  is a front isometric view of the hitch receiver; 
         FIG. 2  is a rear isometric view of the hitch receiver; 
         FIG. 3  is a front view of the hitch receiver; 
         FIG. 4  is a rear view of the hitch receiver; 
         FIG. 5  is a top view of the hitch receiver; 
         FIG. 6  is a bottom view of the hitch receiver; and 
         FIG. 7  is a section view  8 - 8  of the hitch receiver in  FIG. 3 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A vehicle mounted hitch receiver  10  is shown in  FIGS. 1-7  that has a frame  12  with a first mounting portion  14  and a second mounting portion  16 . The mounting portions  14 ,  16  are designed to affix the receiver  10  to a structurally sound part of a vehicle (not shown), commonly a frame or reinforced area of a vehicle&#39;s body. Holes  18  are drilled or stamped into the mounting portions  14 ,  16  to allow the attachment. Typically, the hitch receiver  10  is permanently affixed to the vehicle but it is contemplated the receiver  10  is removable. The location, size, and shape of the holes  18  and mounting portions  14 ,  16  will vary from vehicle to vehicle. Some embodiments can further include tapped holes in addition to or where holes  18  are currently shown. The mounting portions  14 ,  16  are shown as a formed stamping, but other shapes and materials are contemplated. A receiver portion  20  is designed to receive a draw bar with a towing hitch ball (not shown). The draw bar is then affixed to the receiver portion  20  through a pin or other locking feature. Locking draw bars to hitch receivers is well-known in the art. 
     Located between the mounting portions  14 ,  16  is a center section  22  that is attached to the mounting portions  14 ,  16  by flanges  24 ,  26 . The flanges  24 ,  26  attach to their respective mounting portions  14 ,  16  through fasteners  28  or welding. A first upper torsion tube  34  is affixed to flange  24  and a second upper torsion tube  36  is affixed to flange  26 . The torsion tubes  34 ,  36  are coaxial and mechanically connected by a torsion housing  40 . The center section  22  shows torsion tubes  34 ,  36  extending completely between the mounting portions  14 ,  16 , but it is contemplated that the torsion tubes  34 ,  36  only extends partially. For example, some vehicles have obstructions that are not movable, such as exhaust pipes, bumper features, or other frame protrusions that prevent a straight torsion tube from extending across. In this event, the mounting portions  14 ,  16  may further contain a structural piece that connects its respective torsion tube  34 ,  36 . The torsion housing  40  is made up of a curved back  42 , a first side  44 , and a second side  46 , shown in  FIGS. 4-6 . The back  42 , first side  44 , and second side  46  are all mechanically fixed together, typically through welding or fasteners. First side  44  is affixed to torsion tube  34  and second side  46  is affixed to torsion tube  36 . Also located in the torsion housing  40  is a lower torsion tube  50 . The lower torsion tube  50  is affixed to side  44  at a terminal end and affixed to side  46  at the opposite terminal end. 
     The torsion housing  40  is an assembly of a series of parts made from flat or bent sheet metal that is welded or affixed together to the torsion tubes  34 ,  36  to form a single structural component. In addition to the bent and flat sheet metal is a lower torsion tube  50 . Each torsion tube  34 ,  36 ,  50  is mostly square and has a corresponding central axis  86 ,  88 . A section view of the torsion housing is shown in  FIG. 7 . The central axis  86  of the upper tubes  34 ,  36  is parallel to the central axis  88  of the lower tube  32 . The central axes  86 ,  88  do not have to be exactly parallel, only sufficiently parallel for the mechanism to move without binding. The torsion housing  40  and upper tubes  34 ,  36  are fixed with respect to the mounting portions  14 ,  16 . 
     Residing inside the upper tubes  34 ,  36  is an upper torsion bar  52  and inside the lower tube  50  is a lower torsion bar  54 . As shown, the upper torsion bar  52  extends outwardly to the outer ends of the upper torsion tubes  34 ,  36 . The lower torsion bar  54  extends beyond the ends of the lower torsion tube  50 . The torsion bars  52 ,  54  can be seen in the cross section of  FIG. 7 . Surrounding the torsion bars  52 ,  54  are resilient cords  56 . The resilient cord  56  supports the torsion bars  52 ,  54  and centers them about their corresponding axis  86 ,  88 . As shown, the torsion bars  52 ,  54  are angled with respect to their corresponding tube  34 ,  36 ,  50  with the flats facing corners of the tube. This creates substantially triangular shaped cavities that receive the resilient cords  56 . They fit in the corners of the tubes and overlay the flat surfaces of the torsion bars  52 ,  54 . A torsion bar located inside a torsion tube and surrounded by resilient cords is commonly known in the suspension and spring art. 
     The upper torsion arm  70  is fixed to and rotates with the upper torsion bar  52 . The upper torsion arm  70  is affixed in the middle and is wide enough to be close to both sides  44 ,  46  to prevent excessive axial movement of the upper torsion bar  52  and upper torsion arm  70  along the upper central axis  86 . At the end of the upper torsion arm  70  is an upper pivot point  90 . The upper pivot point  90  forms an upper pivot axis  92 . The upper pivot axis  92  is parallel to and offset from the upper central axis  86 , shown in  FIG. 1 . The axes  92 ,  86  do not have to be exactly parallel, only sufficiently parallel for the mechanism to move without binding. As shown in  FIG. 7 , the upper torsion arm  70  has a rear piece  71  that attaches to the upper torsion arm  70  and the two affix around the upper torsion bar  52 . 
     Attached to ends of the lower torsion bar  54  are lower torsion arms  94 ,  96 . The lower torsion arms  94 ,  96  overlay a portion of the sides  44 ,  46  and rotate with the lower torsion bar  54  as shown in  FIG. 1 . The lower torsion arms  94 ,  96  are affixed to the terminal ends of the lower torsion bar  54  sufficiently close to the sides  44 ,  46  to prevent excessive axial movement of the lower torsion bar  54  and lower torsion arms  94 ,  96  along the lower central axis  88 . At the end of each lower torsion arm  94 ,  96  is a corresponding lower pivot point  98 ,  100 . Both lower pivot points  98 ,  100  align to form a lower pivot axis  102 . The lower pivot axis  102  is parallel to and offset from the lower central axis  88 . The axes  88 ,  102  do not have to be exactly parallel, only sufficiently parallel for the mechanism to move without binding. 
     The receiver portion  20  has an upper pivot tube  60  and a lower pivot tube  62  that are spaced similarly to the pivot points. The receiver portion  20 , as shown in all FIGS. shows a series of receivers  64 - 68  for example. Each receiver  64 - 68  is made from a rectangular tube, visible in  FIG. 3 , and is sized to receive a slide-in ball hitch or similar device and has transverse holes  72  that are adapted to receive a pin to affix the slide-in ball hitch (not shown). While three receivers are shown, it is contemplated that a single receiver or several receivers are affixed to the receiver portion  20 . The receiver portion  20  has sides  74 ,  76  that reinforce and align the receivers  64 - 68 . The pivot tubes  60 ,  62  extend through the sides  74 ,  76  and the uppermost  64  and lowermost  68  receivers. The pivot tubes  60 ,  62  are long enough to fit between the pivot arms without allowing excessive axial movement along the pivot axes  92 ,  102 . 
     Due to the resilient nature of the cords  56 , the torsion bars  52 ,  54  are held in a neutral or resting position (as shown in all FIGS) where all of the cords  56  equally apply pressure to the outside flat surfaces of the torsion bar  52 ,  54 . The cords  56  are shown in  FIG. 7 . When a load is applied and the torsion bar  52 ,  54  begins to rotate, the torsion bar  52 ,  54  is urged toward the neutral position by the cords  56 . 
     As weight is added to the receiver portion  20  (by the separate towing hook or ball), the entire receiver portion  20  moves down and the pivot arms rotate. The cords  56  become distorted by the flat surfaces of the torsion bars  52 ,  54  as they rotate. The resiliency of the cord  56  resists the distortion. The more the torsion bar rotates, the more the cords resist. The spacing of the pivot arms, pivot points  90 ,  98 ,  100  and central axis  86 ,  88  causes the receiver portion  20  to move vertically with minimal to no rotation or angular change with respect to the mounting portions  14 ,  16 . 
     An optional displacement or load indicator (not shown) can be implemented to show the user the amount of tongue weight or displacement of the receiver portion  20  with respect to the fixed portion  12 . The indicator has a needle that is fixed to one of the pivot arms. As the weight on the receiver portion  20  increases, the displacement indicator shows the user how much load is present. The torsion housing  40  may have a reference line or feature. As the pivot arm rotates, the needle moves with respect to the feature, showing the user the amount of load on the hitch receiver  10 . A fastener holds the needle and allows adjustment of the needle to set a desired number or zero reference. 
     It is understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects. No specific limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Modifications may be made to the disclosed subject matter as set forth in the following claims.