Abstract:
A trailer hitch coupler to couple a trailer to a trailer hitch includes a socket adapted for receiving a trailer hitch ball; a clamp associated with the socket and operable for engaging the trailer hitch ball; a sensor operatively connected with the socket and operable for determining a distance between an inner surface of the socket and an outer face of the trailer hitch ball when the trailer hitch ball is positioned within the socket; a clamp prevention device operatively connected with the socket and with the clamp and operable to prevent engagement of the clamp with the trailer hitch ball; and a release mechanism operatively connected with the sensor and the clamp prevention device and operable to release the clamp prevention device to allow the clamp to engage the trailer hitch ball when the sensor communicates a desired hitch condition.

Description:
CROSS REFERENCE 
     This application claims priority to U.S. Provisional Patent Application No. 61/431,691, filed Jan. 11, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     Many existing trailer hitches implement a hitch ball and socket connection to provide a connection of a trailer to a vehicle for towing. The trailer hitch connected to the vehicle is generally a hitch ball of a certain diameter and having a certain shank diameter to carry a desired load. Common hitch ball sizes include ball diameters of 1⅞″, 2″, and 2 5/16″. Hitch balls usually include a shank that distances the hitch ball above the hitch and provides a threaded connection to the vehicle. Common shanks have a round cross-section and have 3/4″, 1″, or 1¼″ diameters. A user will select a hitch ball of a certain diameter and a shank of a certain diameter to achieve a certain towing load capacity. 
     A trailer generally includes a trailer hitch coupler that includes a socket that receives the hitch ball. The coupler also includes a mechanical device to bring a clamping member into contact with the bottom of the hitch ball. Common mechanical devices include a hand crank and a lever. When the mechanical device is disengaged, the clamping member is loose and the coupler can be lifted over the hitch ball. When the mechanical device is engaged, a clamping member is raised into contact or near contact to the bottom of the hitch ball securing the trailer to the hitch ball. The clamping device and the socket generally form an opening that is smaller than the hitch ball diameter to prevent the hitch ball from being disengaged from the coupler while towing. In one commonly used coupler, a hand crank or lever includes a hook or latch that locks the hand crank or lever in an engaged position while towing to prevent the accidental loosening of the hand crank or lever resulting in an accidental release of the clamp. As an additional safety measure, it is also common to further secure a lever latch with a pin or a padlock. The hitch ball and coupler assembly provides force transfer in both lateral and vertical directions and provides a pivot point allowing the vehicle to turn, bank, and yaw while towing the trailer and maintaining a secure attachment to the towing vehicle. 
     SAE International has specified classes of hitch and coupler connections to be certified to pull a trailer having a trailer Gross Vehicle Weight (“GVW”). The GVW is the total weight of the load carried by the trailer including the trailer weight. For example, Class 1 assemblies include all trailers that carry a GVW of 2000 lbs., Class 2 includes all trailers that carry a GVW from 2000 lbs to 3500 lbs., Class 3 includes all trailers that carry a GVW from 3500 lbs. to 5000 lbs.; and Class 4 includes all types of trailers with a GVW between 5000 lbs. and 10,000 lbs. The trailer hitch assembly of the hitch ball, shank, and coupler are generally selected to be able to tow trailers of a certain weight class. Generally, the larger the hitch ball and shank diameter, the greater the load that may be transferred through the trailer hitch assembly. A coupler is selected having a material thickness sufficient to transfer the pull force to tow the desired GVW of the trailer. Thus, using the correct combination of hitch ball, shank diameter, and a coupler is fundamental to the safe and effective towing of trailers carrying various loads. 
     One shortcoming in the prior art is that it is possible for a coupler configured for a larger sized hitch ball may be placed over a smaller hitch ball. For example, a coupler configured to receive a 2 5/16″ hitch ball to be placed over a 2″ or 1⅞″ diameter hitch ball. The coupler will also latch when a coupler configured for a larger hitch ball is placed over a hitch ball of a smaller size giving the operator the false impression that the trailer is securely coupled to the vehicle. This situation can be very dangerous. If the trailer hitch connection is subjected to a vertical force by hitting a bump, or even rapid deceleration, the trailer can become detached from the hitch ball as the ball diameter is smaller than the opening provided when the clamp has been engaged by the lever or other mechanism. If a trailer becomes disengaged from the hitch ball, serious property damage and personal injury is probable and even deaths have occurred as a result. 
     Thus, there is a need in the art for a trailer hitch coupler that senses the size of the hitch ball and prevents the lever from latching or the clamp from being fully engaged when the hitch ball is of a smaller size than the coupler is configured to receive to prevent a user from coupling a trailer to a hitch ball that is too small. There is a further need in the art for a trailer hitch coupler to provide the operator a visual signal of whether the coupler is receiving a hitch ball of the correct diameter. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention generally pertains to a trailer hitch coupler that senses the size of a hitch ball positioned within a hitch coupler socket and prevents a clamp or lever of the coupler from being fully engaged when the hitch ball is of a smaller size than the coupler is configured to receive. 
     Another aspect of the invention pertains to a trailer hitch coupler that provides the operator with a visual signal of whether the coupler is receiving a hitch ball of the correct diameter. 
     In accordance with one or more of the above aspects, there is provided a trailer hitch coupler to couple a trailer to a trailer hitch that includes a socket adapted for receiving a trailer hitch ball; a clamp associated with the socket and operable for engaging the trailer hitch ball; a sensor operatively connected with the socket and operable for determining a distance between an inner surface of the socket and an outer face of the trailer hitch ball when the trailer hitch ball is positioned within the socket; a clamp prevention device operatively connected with the socket and with the clamp and operable to prevent engagement of the clamp with the trailer hitch ball; and a release mechanism operatively connected with the sensor and the clamp prevention device and operable to release the clamp prevention device to allow the clamp to engage the trailer hitch ball when the sensor communicates a desired hitch condition. 
     In accordance with one or more of the above aspects, there is provided a trailer hitch coupler to couple a trailer to a trailer hitch that includes a socket adapted for receiving a trailer hitch ball; a clamp associated with the socket and operable for engaging the trailer hitch ball; a sensor operatively connected with the socket and operable for determining a distance between an inner surface of the socket and an outer face of the trailer hitch ball when the trailer hitch ball is positioned within the socket; a clamp prevention device operatively connected with the socket and with the clamp and operable to prevent engagement of the clamp with the trailer hitch ball; a release mechanism operatively connected with the sensor and the clamp prevention device and operable to release the clamp prevention device to allow the clamp to engage the trailer hitch ball when the sensor communicates a desired hitch condition; and a status display associated with said clamp prevention device that is operable to indicate whether the clamp prevention device is engaged or released. 
     These aspects are merely illustrative of the innumerable aspects associated with the present invention and should not be deemed as limiting in any manner These and other aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the referenced drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawing forms a part of the specification and is to be read in conjunction therewith, in which like reference numerals are employed to indicate like or similar parts in the various views, and wherein: 
         FIG. 1  is a cross-sectional view of a trailer hitch coupler in accordance with one embodiment of the present invention; 
         FIG. 2A  is perspective view of a trailer hitch coupler in accordance with one embodiment of the present invention; 
         FIG. 2B  is a side view of a trailer hitch coupler in accordance with one embodiment of the present invention; 
         FIG. 2C  is a front view of a trailer hitch coupler in accordance with one embodiment of the present invention; 
         FIG. 2D  is a bottom view of a trailer hitch coupler in accordance with one embodiment of the present invention; 
         FIG. 2E  is a cross-sectional view of the trailer hitch coupler of  FIG. 2C  taken along the line  2 E- 2 E; 
         FIG. 3A  is a perspective view of a clamp prevention device for a safety trailer hitch coupler in accordance with one embodiment of the present invention, wherein the clamp prevention device is engaged; 
         FIG. 3B  is a perspective view of a clamp prevention device for a safety trailer hitch coupler, wherein the clamp prevention device is released; 
         FIG. 3C  is a top view of a clamp prevention device for a safety trailer hitch coupler, wherein the clamp prevention device is engaged; 
         FIG. 3D  is a top view of a clamp prevention device for a safety trailer hitch coupler, wherein the clamp prevention device is released; 
         FIG. 3E  is a side view of a clamp prevention device for a safety trailer hitch coupler, wherein the clamp prevention device is engaged; and 
         FIG. 3F  is a top view of a clamp prevention device for a safety trailer hitch coupler, wherein the clamp prevention device is released. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The following description of the invention illustrates specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. 
     The present invention is directed toward a safety trailer hitch coupler that prevents a trailer hitch coupler from being coupled to a smaller diameter hitch ball. Now turning to  FIGS. 1-3 , the safety trailer hitch coupler  10  of the present invention includes a neck  12 , socket  14 , clamp  16 , a securing lever  18 , a latch  20 , and a lock-out assembly  22 . 
     Neck  12  includes a first side wall  24 , a second side wall  26 , a top wall  28 , flange  30 , a first end  32  and a second end  34 . Neck  12  is generally sheet steel that is pressed or machined into its final shape. Neck  12  may be sheet steel of gauge thickness ranging from 16 gauge to 6 gauge. Neck  12  may also be fabricated from plate steel ½″ thick or greater depending upon the class of hitch and the desired load capacity. Neck  12  is generally a “U” shape defined by first side wall  24 , second side wall  26 , and top wall  28  wherein flange  30  is substantially perpendicular to side walls  24  and  26  to reinforce neck  12 . The width W of side walls  24  and  26  and top wall  28  will be selected to match the dimensions of a tongue (not shown) of the trailer. Stock tube or pipe members are commonly used for trailer tongues. Rectangular or square tube members having outer dimensions of 2″, 2½″, 3″, 3½″, and 4″ are commonly used. Neck  12  may also be sections of tube or pipe members having an inner dimension slightly greater than the outer dimension of the tongue section. Neck  12  is configured to fit snugly over the trailer tongue and bolted or welded to the trailer tongue. Neck  12  may include apertures  36  to facilitate neck  12  being bolted or welded to tongue (not shown). Neck  12  may be zinc plated, galvanized or painted to provide resistance to corrosion. 
     Socket  14  has a substantially spherical shape to receive a hitch ball and is integral or coupled to second end  34  of neck  12 . Socket  14  has an inner surface  38  configured to a radius R. Socket  14  is generally configured to receive a hitch ball of a given diameter and radius R generally is equal to or slightly greater than the radius of the hitch ball. Socket  14  may be welded or bolted to neck  12 ; however, it is common for socket  14  and neck  12  to be included in a single press form during fabrication of safety trailer hitch coupler  10  from sheet steel as described above or welded to neck  12  if safety trailer hitch coupler  10  is fabricated from plate steel. Many configurations of neck  12  and socket  14  are known in the art, all of which are included in the scope of the present invention. 
     Clamp  16  generally comprises a lever arm  40 , a body  42 , a pivot point  44 , and a rod  46 . Clamp  16  is configured to removably engage the bottom and/or side of the hitch ball as shown in  FIG. 1 . Lever arm  40  has a first end  50  and a second end  52 . Generally pivot point  44  is proximate first end  50  of lever arm  40 . Body  42  of clamp  16  is operably coupled to second end  52  of lever arm  40  as shown. Body  42  may be rotated about pivot point  44  to bear against or be in close proximity to the hitch ball. When body  42  is engaged and proximate hitch ball, an opening width W o  is present. When the correct size hitch ball is received by socket  14  and clamp  16  is engaged, opening width W o  is appreciably less than the diameter of the hitch ball. Thereby, the trailer is prevented from lateral or vertical displacement such that the coupler disengages from the hitch ball. Clamp  16  and related mechanisms are well known in the art and all known configurations of clamp  16  for trailer hitch couplers are within the scope of the present invention. 
     Securing lever  18  includes handle  54  and leg  56 . Generally, lever  18  is operably coupled to lever arm  40  of clamp  16  by link arm  58 . Link arm  58  is pivotally coupled to leg  56  at pivot point  60 . Handle  54  and leg  56  are levered about fulcrum  62 . When handle  54  is in a generally horizontal position, lever  18  is considered to be engaged. When lever  18  is engaged, leg  56  is configured to provide engaged lever arm LA E . When handle  54  is in a substantially vertical position, lever  18  is considered to be disengaged. When lever  18  is disengaged, leg  56  is configured to provide disengaged lever arm LA D . Generally, engaged lever arm LA E  is greater than LA D  and when lever  18  is engaged, link arm  58  causes clamp  16  to engage the hitch ball. 
     Other embodiments of securing lever  18  are known in the art and all such known embodiments are within the scope of the present invention. In addition, other known mechanisms used to cause clamp  16  to engage the hitch ball are also within the scope of the present invention. For example, one embodiment of the present invention may include a threaded securing mechanism that includes a handle above top wall  28  of neck  12 . The handle can be rotated thereby causing clamp  16  to engage the hitch ball by changing the relative position of clamp  16  using a screw mechanism. 
     Latching mechanism  20  is generally configured to prevent securing lever  18  or other securing mechanism from disengaging while towing the trailer. Latching mechanism  20  can also be used as a theft prevention device to store a trailer with the clamp engaged to prevent the coupler from being able to receive the hitch ball. Latching mechanism includes a latch body  64 , a latch hook arm  66 , a hook receiving member  68 , and a lock-out arm  70 . A portion of body  64  of latching mechanism  20  is pivotally coupled to securing lever  18  at pivot point  72 . Latch hook arm  66  has a first end  74  and a second end  76  wherein the first end is integral with or coupled to body  64  and second end  76  may be configured with latch hook  78 . Latch hook  78  is configured to be received by hook receiving member  68 . In addition, lock-out arm  70  of latching mechanism  20  has a first end  80  and a second end  82 . First end  80  of lock-out arm  70  is integral with or coupled to body  64  and second end  82  may include a hook  84 . There are many known latching mechanisms in the art and all such latching mechanisms lend themselves for use in the safety trailer hitch coupler of the present invention and shall be within the scope of the present invention. 
     Lock-out system  22  is generally configured to prevent one or more of clamp  16 , lever  18 , or latching mechanism  20  from engaging when safety trailer hitch coupler  10  of the present invention receives a hitch ball that is smaller than what socket  14  is configured to receive. Lock-out system  22  generally includes a sensor  86 , a clamp prevention device  88 , and a release mechanism  90 . Lock-out system  22  may also include a status display  92  that provides a user a visual indication of whether safety trailer hitch coupler  10  of the present invention is receiving the proper sized hitch ball. 
     Sensor  86  generally determines the distance between inner surface  38  of socket  14  and an outer face of a hitch ball. Any mechanism that is known in the art to measure this distance is within the scope of the present invention. An embodiment of sensor  86  includes a spring activated plunger that extends into socket  14  and is caused to be translated outwardly from inside surface  38  of socket  14  when the hitch ball is received by socket  14 . An alternative embodiment of sensor  86  may include another known mechanical tab or member that is caused to translate due to displacement when socket  14  receives the hitch ball and returns to its original position when the hitch ball is removed. In an alternate embodiment, sensor  86  may comprise a ball plunger electromechanical switch or similar device, such as a roller plunger, chisel plunger, or push button. In this embodiment, the ball plunger is forced outwardly from the inside surface  38  of the socket  14  when the proper size hitch ball is received in the socket  14 . This translation of the ball plunger activates the associated electrical switch in the device to trigger a signal to the release mechanism  90  as discussed below. In another embodiment, sensor  86  includes measuring a distance between the received hitch ball and the inner surface  38  of socket  14  using electronic, electro-magnetic, transducer, ultrasonic, laser, or other known non-contact distance measuring method known in the art. 
     Clamp prevention device  88  generally prevents one or more of clamp  16 , securing lever  18 , or latching mechanism  20  from functioning when safety trailer hitch coupler  10  of the present invention receives a hitch ball that is smaller than socket  14  is configured to receive. Any device that is known in the art to prevent one or more of clamp  16 , securing lever  18  and clamping mechanism from functioning to close around a hitch ball that is too small is within the scope of the present invention. An embodiment of clamp prevention device  88  includes a latch arm receiving plate  94 , at least one flag  96  pivotally coupled to latch arm receiving plate  94  with pin  98 . An embodiment may include flag  96  being spring loaded so that it will return to a default position when not released. This embodiment may further include spacer  100  to position flag  96  above latch arm receiving plate  94 . Further, an embodiment may include at least one stop  102  that prevents flag  96  from being displaced too far in a certain direction. Latch arm receiving plate  94  generally includes at least one aperture  104  configured to allow lock-out arm  70  to pass through. 
     Release mechanism  90  is generally in mechanical or electronic communication with sensor  86 . If sensor  86  determines the correct hitch ball size is being received by socket  14 , it communicates to release mechanism to cause the release of clamp prevention device  88 . Release mechanism  90  generally releases the clamp prevention device  88  to allow clamp  16 , securing lever  18 , and latching mechanism  20  to be fully engaged to secure clamp  16  in position to secure safety trailer hitch coupler with respect to the hitch ball. 
     One embodiment of release mechanism  90  includes a high strength cable  106  with a first end  112  coupled to socket  14 , and a second end  116  coupled to flag  96 . Cable  106  is coupled to sensor  86  being a spring loaded plunger  86  along its length. When the proper size hitch ball is received into socket  14 , the plunger  86  is displaced outwardly causing cable  106  to be displaced outwardly and to apply a force to flag  96  pivotally coupled to said latch receiving plate  94 . The displacement of cable  106  pulls on and causes rotation of flag  96  about pin  98  thereby displacing flag  96  from its default position covering aperture  104  of latch arm receiving plate  94 . If the hitch ball is the correct size, sensor  86 , clamp prevention device  88  and release mechanism  90  are configured to displace flag  96  such that lock-out arm  70  may pass through aperture  104  of latch arm receiving plate  94  allowing hook  78  to engage hook receiving member  68 . If the hitch ball does not cause the full displacement of sensor  86 , flag  96  will not be sufficiently displaced thereby preventing lock-out arm  70  from passing through aperture  104  of latch arm receiving plate  94  and preventing the latching mechanism  20  from being fully engaged. The inability of a user to fully engage latching mechanism  20  will indicate to user that the wrong size of hitch ball is being received into socket  14  of safety trailer hitch coupler  10 . 
     Other mechanical methods of preventing clamp  16 , securing lever  18 , and/or latching mechanism  20  to only be fully engaged when the correct size of hitch ball is received into socket  14 . Spring loaded plunger  86  may be journaled for spiral rotation when spring loaded plunger  86  is displaced outwardly causing plunger to rotate away from flag  96  whereby cable  106  applies a pulling force upon flag  96 . If spring loaded plunger  86  is sufficiently displaced, flag  96  will be rotated to uncover aperture  104 . 
     Another embodiment includes sensor  86  tripping an electronic switch that causes an electronic or magnetic release of clamp prevention device  88 . The clamp preventing device  88  may be motorized and release mechanism  90  may send an electronic signal to the motor of clamp preventing device  88  wherein motor of claim preventing device  88  acts to allow clamp  16 , securing lever  18 , and/or latching mechanism  20  to be fully engaged. The trailer may have its own battery system to power an electronic sensor  86 , clamp preventing device  88 , and release mechanism  90 , or an electronic sensor  86 , clamp preventing device  88 , and release mechanism  90  may be powered through the electrical connection with a towing vehicle. This configuration may also provide an additional safeguard to ensure that the trailer is electronically connected to the tow vehicle prior to the trailer being securely coupled to the towing vehicle. 
     An embodiment of the present invention may also include a status display  92  that provides a visual indicator to the operator that the clamp prevention device  88  is activated and the hitch ball is the wrong size. One embodiment of status display  92  may provide a window  108  that a user can view a portion of flag  96  that is painted red. When the red portion is visible, the clamp prevention device  88  is activated and when no red portion is visible, the clamp prevention device  88  has been released to allow clamp  16 , securing lever  18 , and latching mechanism  20  to be fully engaged. 
     From the foregoing, it may be seen that the continuous passive motion device of the present invention is particularly well suited for the proposed usages thereof. Furthermore, since certain changes may be made in the above invention without departing from the scope hereof, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense.