Abstract:
A trailer hitch positioning apparatus is provided for directing the driver of a vehicle that is backing up to a trailer. The apparatus includes an infrared light and sensor unit mounted on the bumper or receiver of the towing vehicle for transmitting a light beam of predetermined vertical and horizontal width toward the trailer. A reflecting device mounted under the trailer tongue returns infrared light impulses with information back to the sensors which are analyzed by a microprocessor that controls a transmitter. The transmitter audibly guides the driver&#39;s ball to the trailer hitch for coupling. A stop tone warns the driver to stop when the ball and hitch are accurately positioned for coupling.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention generally relates to a positioning apparatus for use during hitching a pickup truck or other towing vehicle to a trailer or other towed vehicle. More particularly, this invention relates to a positioning apparatus for aligning the coupling elements or the two vehicles as the towing vehicle is backed up or driven toward the towed vehicle and for indicating when the coupling elements are properly positioned for coupling. 
     2. Discussion 
     Hitching a vehicle to a trailer can be a long and frustrating process, especially when attempted by a single person. Because the coupling elements (i.e., ball and hitch) on the vehicle and trailer are normally not visible from the driver&#39;s seat, the driver must periodically stop the vehicle and inspect the alignment and position of the ball and hitch before moving the vehicle closer to the trailer. Even with frequent visual inspections, some misalignment of the ball and hitch normally results. A driver must then repeat the process or, if possible, manually shift the tongue and thus the hitch of the trailer over the ball so that the two vehicles can be hooked up. Complicating the maneuvering is the fact that a driver can become easily confused as to which direction to turn the front wheels in order to back the vehicle in the desired direction. 
     In an attempt to improve on this manual method, prior guidance systems have been designed for assisting a driver in maneuvering a vehicle toward a trailer. U.S. Pat. No. 4,938,495 to Beasley et al., for example, discloses a trailer hitch guide that uses an infrared light emitter mounted on a trailer and powered by a battery in the isolated unit. A support bar with alignment sensors is mounted on the back of a towing vehicle. The emitted infrared light produces a light field which can be detected by the receiving sensors on the vehicle. Beasley recites that depending on the orientation of the receiving sensors to the field, the alignment and position of the vehicle relative to the trailer can be determined from a direction indicator visible to the driver. The Beasley device, however, has a number of drawbacks. For example, the isolated light emitter mounted on the trailer runs on a battery in the unit and needs to be turned on before use and shut off after use. The same is true with the second sensor needed for the positioning of coupling. This leaves a great margin for human error as well as replacement and maintenance of the battery. Some vehicles may not have a support bar located in the rear bumper for mounting and this is cumbersome in design. Also, it is believed that the Beasley device may not always indicate accurately the relative position of the hitch and ball due to limitations of the Beasley approach. 
     Other exemplary prior devices for guiding the backing of a vehicle to a trailer are disclosed in U.S. Pat. No. 4,199,756 to Dito, and U.S. Pat. No. 3,418,628 to Fenner. These devices rely on mechanical contact switches or visual alignment mechanisms that are cumbersome and/or which must be mounted temporarily to a vehicle and trailer for use when attempting to back up and hitch the two together. 
     SUMMARY OF THE INVENTION 
     An object of the invention, therefore, is to provide an improved guiding apparatus for use in aligning and positioning a coupling element of a towing vehicle in hitching relation to a coupling element of a trailer or other towed vehicle. 
     A further object of the present invention is to provide a compact, easily installed, durable and reliable guiding apparatus with an audible indicator that indicates when the coupling elements of the vehicles are aligned and when their respective coupling elements are in position for coupling together. 
     Another object of the invention is to provide such an apparatus that indicates to the driver the direction in which to turn the steering wheel of the towing vehicle relative to the towed vehicle. 
     Still another object of the invention is to provide such an apparatus capable of detecting certain objects and people between the towed and towing vehicle thereby reducing the risk of accidents during use and enhancing the overall safety during use of the apparatus. 
     To achieve these objects, an apparatus in accordance with the present invention comprises an emitting means mounted under the ball on a towing vehicle for transmitting two focused optical beams toward a trailer or other towing utility vehicle. A reflecting means for receiving the two beams is mounted under the hitching tongue of the towed utility vehicle. The towing vehicle includes a plurality of sensors in predetermined locations relative to a towed coupling element, such as a hitch coupler for receiving pulsed infrared light information from the mounted reflector on the towed vehicle. These sensors discretely detect the presence of the first or second beam relative to the towing coupling element. When the ball coupler is in hitching relation to a towing coupling element, such as a trailer hitch on the tongue of the trailer, an alarm sounds. Further, an indicator is electrically coupled to the plurality of sensing means. The indicator comprises means for indicating alignment and misalignment of the truck ball and trailer hitch as the truck is backed up and also for indicating the direction in which the truck steering wheel should be turned to align these coupling elements in the event of any misalignment. In addition, the indicator comprises means for indicating when the coupling elements are in hitching relation. 
     In accordance with one specific aspect of the invention, the sensing means comprises at least three sensors in the rear of the towing vehicle under the ball or receiving coupler. In the illustrated embodiment, these three sensors are positioned along a line normal to the longitudinal vehicle axis. Also, the first and second optical beams are of a predetermined horizontal width and are centered about a vertical plane through the center of the ball and containing the longitudinal axis of the towing vehicle. In addition, the three sensors are directly under the ball or receiver coupling, spaced apart a distance slightly greater than the width of each focused beam. Therefore, the hitch and ball are aligned when the beams strike the third sensor spaced between the other two sensors. 
     In the illustrated embodiment, and as a more specific aspect of the present invention, the emitting means comprises two pulsed infrared light emitters for projecting infrared light to the reflecting means which reflects information back to the sensors as to the location of, and/or centering of, both light emitters. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to appreciate the manner in which the advantages and objects of the invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings only depict preferred embodiments of the present invention and are not therefore to be considered limiting in scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a perspective view of a trailer hitch positioning apparatus according to the invention with the towing and towed vehicles shown properly aligned; 
     FIG. 2 is a side view of the apparatus of FIG. 1 showing the vehicles entering a position for being hitched together; and 
     FIG. 3 is a schematic diagram of one form of a two optical beam emitter with three sensors used in the apparatus of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 and 2 of the drawings, a portion of a trailer  10  or other towed vehicle is shown having an elongated tongue  11  which terminates in a towed coupling element such as hitch  12 . A truck  14  or other towing vehicle is also shown with a towing coupling element such as a matching ball coupler  16  mounted on the rear bumper  17  or hitch receiver  18  mounted under towing vehicle  14 . The ball coupler  16  and hitch  12  exemplify one type of conventional mechanism for coupling the trailer  10  and truck  14  together. 
     An emitting means  19  is mounted under the ball  16  on the bumper  17  or on towing hitch  18   b  of receiver tongue  18   a . Infrared and sensor unit  20  emits optical beams  21  rearwardly from the truck  14  toward the trailer  10 . This means comprises means for projecting a focused beam  21  to a reflecting means  22  from a location forward of hitch  12 . In the illustrated embodiment, the emitting means comprises an infrared light transmitting unit  20  mounted, as by a magnet or fastener (not shown) to the receiver tongue  18   a  or bumper  17  for projecting the first and second focused beams with an infrared position emitter to reflector  22  on hitch tongue  11  for reflecting pulsed infrared information back to unit  20  powered by a lithium battery when mounted to the bumper  17 . As can be seen in FIG. 1, the two beams are of a circular cross-section and have a circumference of horizontal width and vertical width that diverges as the beam projects and is expanding with distance. The light unit  20  produces this beam by projecting infrared light from plural emitters (described below) through commercially available infrared L.E.D. emitters which are positioned within emitter means  19 . The light unit  20  is situated such that the first collimated beam is centered in a vertical plane containing the longitudinal trailer axis and bisecting the reflector  22  which transmits the second focused beam  23  back to sensor unit  20  beyond the front end of the hitch  12  and centered in this same vertical plane. 
     Turning now also to FIG. 3 means  19  for receiving the beam from light unit  20  is mounted to the rear of the truck  14  and includes an enclosed unit which carries three infrared alignment sensors  30   a ,  30   b , and  30   c  spaced apart laterally thereon and positioned under or on either side of the ball coupler  16 . The sending and receiving unit  19 / 20  is mounted to the rear of the truck  14 , preferably to the base of the bumper or ball bracket  17  or  18   a , so as to be perpendicular to the longitudinal axis of the towed trailer  10 . The alignment sensors  30   a ,  30   b ,  30   c  are typically laterally spaced equidistantly from the center of the ball coupler  16 . More specifically, and for reasons explained more fully below, the sensors  30   a ,  30   b ,  30   c  are spaced apart a distance equal to the infrared beam and more preferably slightly greater than the width of the infrared beam. The respective sensors  30   a  and  30   c  represent right and left to the center of the ball coupler sensor  30   b . In the present embodiment, the distance between sensors  30   a  and  30   c  is 2½ inches or smaller, with the predetermined width of the beam being about 2½ inches up to about 3 feet. The alignment sensor  30   b , spaced between the two sensors  30   a  and  30   c , is for detecting the presence of the reflected beam  23  between the other two sensors. The sensor  30   b  may be positioned in alignment with the towing vehicle axis and thus the center of ball coupler  16 . Also, sensors  30   a ,  30   b , and  30   c  are topically coated with a purple transparent film to provide better filtering of undesired fluorescent light from the environment. The use of the infrared signals minimizes interference from ambient light sources and also results in a highly accurate apparatus. 
     Means are also provided for detecting the positioning emitters  31   a  and  31   b  when the hitch  12  is over the ball coupler  16  in hitching relationship thereto. The sensor  30   b  is aligned with the center of the reflector that is in full spectrum of infrared light information of per calibrated hitching and coupling coordinates. The sensor  30   b  receives light from position reflector  22  when the hitch  12  is immediately above the ball coupler  16 . Position reflector  22  and position sensor  30   b  may be at any other convenient location on the respective trailer and truck as long as the hitch is over the ball when the position sensor receives the desired light signal from the position emitter. 
     The outputs of the alignment sensors  30   a ,  30   b ,  30   c  are coupled via circuits, described below, to a transmitter  24  mounted within the unit  20 . The transmitter  24  broadcasts RF signals to the vehicle&#39;s radio which emits corresponding tones. As best shown in FIG. 3, transmitter  24  is coupled to the position sensors  30   a ,  30   b , and  30   c . The transmitter  24  is engaged by the action of mounting it to the vehicle and a respective audible tone of right or left from center will indicate to the driver the position of steering needed to find center. Once a positioning sensor captures a reflection from reflector  22 , the transmitter  24  changes emitted frequencies to indicate right or left to center by high and low pitch tones from the vehicle radio moving in unison from both high and low to center and indicates the truck  14  is aligned or “centered” with the trailer  10 . Because of the spacing of sensors  30   a ,  30   c  and the width of the alignment beam  21 , the desired alignment exists only when the light  23  on and the sensors  30   a ,  30   b ,  30   c  indicates that the beam is positioned between the two sensors  30   a ,  30   c  and that hitch  12  is centered on the ball coupler  16 . A stop frequency is emitted from the transmitter  24  to indicate when the hitch  12  is immediately over the ball coupler  16 . When the stop tone sounds, the trailer  10  and truck  14  are ready to be coupled together. The transmitter  24  also indicates if an object is between the trailer  10  and truck  14  by blocking the beam from reaching any of the sensors  30   a ,  30   b ,  30   c . In this case, an interference frequency causes an interference tone to be emitted from the radio and the driver is alerted to stop the truck and check for obstructions. 
     The operation of the invention is best understood with reference to FIGS. 1 and 3. With the light unit  20  operational, two beams having predetermined circumferences are projected toward the trailer and bisecting the hitch  12 . With the truck  14  and trailer  10  properly aligned, as shown in FIGS. 1 and 3, the reflected beam strikes the position between outer alignment sensors  30   a ,  30   c  such that the sensor  30   b  receives the light. Consequently, the sensor  30   b  generates a signal which is coupled via circuitry to the transmitter  24  which emits an RF signal causing the radio to sound the centering tone. The center tone indicates that the driver need only back up in a straight line toward the trailer  10 . When the truck  14  is positioned relative to the trailer  10  as shown in FIG. 2, the focused beam from position reflector  22  strikes the position sensors  30   a ,  30   b ,  30   c  indicating that the hitch  12  is over the ball coupler  16 . The sensor  30   c  then generates a signal to transmitter  24  which emits an RF signal causing the radio to sound the stop tone. The stop tone signals the driver to stop the truck  14 . 
     If the truck  14  is approaching the trailer  10  from somewhat of an angle or is otherwise misaligned with the trailer, the reflected beam  23  strikes one or the other of the sensors  30   a  or  30   c . The sensor  30   a  or  30   c  that receives light generates a signal which causes the corresponding RF signal to be emitted by the transmitter  24 . The radio then sounds a tone having a pitch or rhythm that indicates which way the driver should turn the steering wheel to align the truck and trailer. For example, if the beam strikes the sensor  30   c  shown in FIG. 3, the truck  14  is laterally displaced to the right of the trailer  10  (looking from the trailer  10  towards the truck  14 ) and the turn left tone is sounded. The turn left tone, associated with sensor  30   c  indicates that the driver should turn the steering wheel counterclockwise as the truck is backed up. This action will turn the front wheels of the truck to the left and cause the rear of the truck to swing toward proper alignment with the trailer. 
     The respective sensor  30   a ,  30   b ,  30   c  are wired in parallel so that the corresponding tone is sanded if either of the interconnected sensors is struck by the collimated beams. The spacing between these additional sensors and the adjoining sensor is typically slightly less than the width of the beam  23  so that the beam cannot miss these sensors when it is slightly to the right of the sensor  30   a  or to the left of sensor  30   c.    
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims.