Patent Abstract:
Disclosed is a self-locking hitch pin for joining a hitch device to a receiver hitch in a quick and easy manner using a single, self-contained mechanism. The hitch pin is comprised of shaft with a locking member on one end and a handle and weight on the other end and a spring and retainers to keep the hitch pin in place. The self-locking hitch pin allows for single-handed installation and securing of a hitch device to a receiver hitch with no pin or locking mechanism to be lost or dropped. The self-locking hitch pin can be inserted into the hitch orifice, have pressure applied to the spring, rotate the hitch pin allowing gravity to engage the locking member and then release pressure on the spring coupling both devices together.

Full Description:
BACKGROUND 
     The present invention relates generally to the field of hitch pins and other locking or securing devices used for the coupling of receiver members to a receiver hitch. Many vehicles are equipped with receiver style hitch assemblies made from 1 or 2 inch square tubing mounted to the undercarriage of a vehicle. A second tube slides inside the receiver and is secured by a hitch pin. Conventional hitch pins for securing a ball mount to a receiver hitch rely on a pin and clip to physically secure the two items together. Pin and clip securing systems typically rely on an angled end to prevent movement in the hitch assembly and rely on a locking pin or clip to prevent the pin from exiting the system. A major disadvantage of this type of system is the installation requires two hands, good visibility and a need to keep track of an, easily lost, locking mechanism. A hitch pin may also be lost during transport of a trailer resulting in the trailer being forcibly removed from the towing vehicle resulting in loss of property or worse. 
     SUMMARY 
     An embodiment of the present invention may therefore comprise a self locking hitch pin comprising: a locking member comprising a distal cylindrical portion connected to a proximal locking member plate; a shaft with a channel pivotally connected to the locking member plate; a shaft abutment surface on a distal end of the shaft that engages with a mating surface on the locking member such that the shaft and the locking member are fixed in a coaxial orientation when the axis of the shaft is rotated to a first position, and the locking member that may freely pivot to a perpendicular orientation to the shaft when the axis of the shaft is rotated to a second position; and, a retainer compressively held in place with respect to the shaft on the proximal side of the shaft with a compressive mechanism. 
     An embodiment of the present invention may also comprise a method of securing a hitch device to a receiver hitch comprising the steps: providing a self-locking hitch pin comprising a locking member with a distal cylindrical portion connected to a proximal plate that is pivotally connected to a shaft within a channel, the locking member that engages with the shaft in a coaxial orientation to form a substantially cylindrical rod when an axis of the shaft is rotated in a first position, and the locking member that may freely pivot to a perpendicular orientation to the shaft when the axis of the shaft is rotated in a second position; inserting the locking member and then the shaft of the self-locking hitch pin while oriented in the first position through a first side of a receiver orifice and hitch orifice to a sufficient distance such that the locking member may freely pivot on an opposite side of the receiver orifice from the first side; rotating the shaft to the second position thereby allowing the locking member to pivot to the perpendicular orientation on the opposite side of the receiver orifice thereby preventing extraction of the shaft from the receiver orifice and the hitch orifice; and, retaining the shaft on the first side of the receiver orifice with a retainer compressively held in place with a compressive mechanism with respect to the shaft. 
     An embodiment of the present invention may also comprise a self-locking hitch pin for securing a hitch device to a receiver hitch: a means for providing a self-locking hitch pin comprising a locking member with a distal cylindrical portion connected to a proximal plate that is pivotally connected to a shaft within a channel, the locking member that engages with the shaft in a coaxial orientation to form a substantially cylindrical rod when an axis of the shaft is rotated in a first position, and the locking member that may freely pivot to a perpendicular orientation to the shaft when the axis of the shaft is rotated in a second position; a means for inserting the locking member and then the shaft of the self-locking hitch pin while oriented in the first position through a first side of a receiver orifice and hitch orifice to a sufficient distance such that the locking member may freely pivot on an opposite side of the receiver orifice from the first side; a means for rotating the shaft to the second position thereby allowing the locking member to pivot to the perpendicular orientation on the opposite side of the receiver orifice thereby preventing extraction of the shaft from the receiver orifice and the hitch orifice; and, a means for retaining the shaft on the first side of the receiver orifice with a retainer compressively held in place with a compressive mechanism with respect to the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric illustration of an embodiment of a self-locking hitch pin. 
         FIG. 2  is a side view of a self-locking hitch pin in insertion position. 
         FIG. 3  is a side view of a self-locking hitch pin in lockable position. 
         FIG. 4  is illustrates the receiver hitch orifice and receiver hitch assembly fixed in place with respect to one another with a self-locking hitch pin. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     While this invention is susceptible to embodiment in many different forms, it is shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments described. 
       FIG. 1  is an isometric illustration of a self-locking hitch pin in insertion position. The hitch pin  100  comprises a dual-diameter cylindrical shaft that engages the hitch and receiver with a standard hitch pin diameter engagement shaft  110  (typically ⅝″ but not limited by example) and a spring retainer shaft  120  which is an addition to the shaft  110  that extends beyond the confines of the receiver orifice. This spring retainer shaft  120  is, in this particular embodiment, smaller in diameter, and coaxial with the engagement shaft  110 . However, in an alternate embodiment, spring retainer shaft  120  and engagement shaft  110  may be the same diameter. The spring retainer shaft  120  connects at an approximately normal angle with a handle member  102  which extends away from the shaft angle and contains an orienting weight  104  at the distal end of the handle member  102 . 
     In this embodiment, a pair of retainers  108  are placed on either side of a spring  106  which all lie coaxially around the spring retainer shaft  120 . These retainers  108  are retained in relaxed position by the perpendicular surface of the handle portion  102  on the distal end and by a shoulder  122  (the larger diameter interface of the engagement shaft  110 ) on the proximal end of the spring retainer shaft  120 . Although this is referred to as a relaxed position or state, there will typically be a small amount of compressive load by the retainers  108  as they retain the spring  106 . Typically, the inner diameter of the retainers  108  are closely matched to the outer diameter of the spring retainer shaft  120  so as allow movement of the proximal washer in relation to the spring retainer shaft  120 , while preventing a sloppy interface and orientation between the two parts as they engage. Additionally, spring retainers  108  or equivalent mechanism for retaining the spring  106 , may be integrated into the spring retainer shaft  120  or the handle  102 . In an alternate embodiment, retainer  108  could be incorporated into the spring or omitted entirely. 
     The proximal end of the engagement shaft  110  contains a locking member  114  which is pivotally connected to engagement shaft  110  via pivot  112  which allows free pivot motion of the locking member  114  on the proximate end of the engagement shaft  110 . The locking member  114  contains a cylindrical portion which typically matches the diameter of the engagement shaft  110  on the proximal end, and pivotally interfaces with the engagement shaft  110  with a locking member plate  118 , which is shown as a flat rectangular cross section retained within a matching channel  116  on the engagement shaft  110  and pivotally anchored with pivot  112 . 
     The channel  116  is centrally aligned on the engagement shaft  110  in an orientation such that the slot extends approximately parallel to the handle axis. In this manner, the locking member  114  may freely pivot from a coaxial orientation with the engagement shaft  110  (acting as if it were a longer constant diameter shaft), to a perpendicular orientation with the engagement shaft  110  and extending in the same direction, and parallel to, the handle and orienting weight  104 . In order to control the positioning of the cylindrical locking member  114  with respect to the cylindrical engagement shaft  110 , at least one of the lateral distal surfaces of the locking member plate  118  and a matching proximal lateral surface of the engagement shaft  110 , are matched or mated, to prevent motion of the locking member  114  past 180 degree (coaxial) alignment establishing an “insertion” position or state ( FIG. 2 ). In this insertion state, the mating surface on the locking member  114  is a mating surface  124  which approximately matches and engages the surface of the shaft abutment  122 . 
       FIG. 2  is a side view of a lockable hitch pin in insertion position. When the self-locking hitch pin  100  is inserted into a receiver ( FIG. 4 ), the hitch pin  100  is oriented as shown in  FIG. 2 , with weight  104  oriented substantially vertically upwards. In this orientation, the weight of the locking member  114  allows it to rotate about pivot  112  until the mating surface  124  engages the shaft abutment  122 . At this point, the hitch pin  100  effectively forms a cylindrical shaft of approximately constant diameter which is easily inserted into the cylindrical orifice formed between a receiver and a hitch. 
       FIG. 3  is a side view of a self-locking hitch pin in lockable position. When the self-locking hitch pin  100  has been inserted with sufficient force to compress spring  106  and sufficient distance for locking member  114  to clear the receiver, weight  104  may be rotated to a substantially downward orientation ( FIG. 3 ). 
       FIG. 4  is a diagram illustrating the receiver hitch orifice and receiver hitch assembly. Hitch  412  is operatively coupled to receiver  410  and is secured together by shaft  110  through receiver orifice  414 . Hitch  412  is inserted into receiver channel  416  until receiver orifice  414  is aligned with hitch orifice  418  to allow hitch pin  100  to be inserted. In order for hitch pin  110  to be secured in place, receiver abutment surface  422  engages with upper locking member abutment  420  and lower locking member abutment  424  putting hitch pin  100  in insertion position ( FIG. 2 ). 
     When used to retain a hitch, the hitch pin  100  is inserted into the orifice formed between the receiver and hitch, thereby locking these members in place with respect to one another. The length of shaft  110  is set to approximately match or be slightly shorter than the width of the receiver such that when the shaft  110  is inserted to a point beyond the transition from shaft  110  to the spring retainer shaft  120 , the retainer  108  engages the receiver, and compresses spring  106 . Pressure is applied to handle  102  thereby compressing the spring  106 . Sufficient pressure is applied to allow locking member  114 , and subsequently locking member abutment  420 , sufficient space for locking member abutment  420  to clear receiver abutment surface  422 . Once the receiver overlaps the spring retainer shaft  120  and the spring  106  is compressed and upper locking member abutment  420  has cleared receiver abutment surface  422 , the handle  102  is rotated 180 degrees in either direction, and the locking member  114  is free to pivot by 90 degrees on the opposite side of the receiver and released, displayed as  FIG. 3 . At this point, one side of the hitch  412  is retained by retainer  108  which is held by spring  106 , and the other side is captured by the locking member plate  118  which is now perpendicular to the shaft  110  within the receiver  410  and hitch  412 . Upper locking member abutment  420  and lower locking member abutment  424  are interfaced and secured to receiver abutment surface  422  by the pressure from the spring  106 . The weight  104  on the distal end of the handle  102  assists in maintaining the orientation of the hitch pin  100  as shown in  FIG. 3  when retaining a hitch into a receiver. 
     To remove the hitch pin  100  and disengage the hitch from the receiver, the handle  102  is rotated 180 degrees in either direction to orient it upward. Pressure is then or simultaneously applied to the handle  102  towards the receiver  410  thereby displacing the retainer  108  and compressing spring  106 . Once the receiver  410  overlaps the spring retainer shaft  120  and upper locking member abutment  420  and receiver abutment  422  disconnect, the locking member is free to pivot by 90 degrees by gravity, the hitch pin  100  returns to the position shown in  FIG. 2  and can be easily removed from the engagement between the hitch  412  and receiver  416 . 
     In one embodiment, pivot  112  is further enhanced with a hollow orifice of adequate size to allow a locking mechanism to pass through the orifice securing hitch pin  100  to receiver  410 . 
     In the present embodiment, the spring  106  is shown as a helical spring, however, any type of compressive member which exerts and elastic force on retainer  108  may be contemplated (e.g. elastomeric members, elastic hydrocarbon polymers, expansive pins, or the like). 
     The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.

Technology Classification (CPC): 1