Patent Publication Number: US-6341979-B1

Title: Electrical connector

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to electrical connectors and, more specifically, to connectors for smaller electrical wires such as used for lower voltage, lower current electrical systems. 
     BACKGROUND OF THE INVENTION 
     Electrical connections for removably connecting electrical wires to devices to be supplied with lower voltage (i.e., less than 240 volts) lower current (i.e., less than 30 amperes) electricity are conventionally made by one of two methods. The first method involves bending the wire around a threaded post and securing the wire to the post by tightening-down a nut onto the wire. A common variation of this method is replacing the post with a bolt, forming the nut as a portion of the device to which the wire is to be connected, and tightening the bolt into the nut portion, thereby clamping the wire tightly (e.g., connecting a bulb whose lower portion comprises a “wire” to an incandescent lamp socket). However, a major disadvantage of this connection method is that the wires are susceptible to breakage in the event of disconnection/reconnection. The second method involves fastening the wire to an intermediary device, which is then, in turn, connected to the subject device (e.g., soldering or crimping the wire to a spade or ring lug, which is then, in turn, fastened to the post or bolt, as described with respect to the first method). Another variation is soldering or crimping the wire to a spade connector which is then, in turn, inserted into a socket, the socket being electrically connected to the device for receiving power (e.g., plug connections used in automobile wiring harnesses). However, a disadvantage of this method is that an extra component, a tool, such as a soldering iron or crimper, is required to secure the wire to the intermediary device. Therefore, a need exists for a method and apparatus of quickly and efficiently connecting and disconnecting a wire to a peripheral device while maintaining the wire&#39;s integrity. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides an apparatus and method for quickly and efficiently connecting and disconnecting a wire to a peripheral device using a minimal number of components while preserving the wire&#39;s integrity. The present invention comprises a ferrule having two ends, a fork or ring lug being disposed at one end and a hollow truncated conical threaded portion around which the strands of an electrical wire are wound disposed at the other end. The threaded portion is then hand-tightened into a matched strain relief boot which secures the wire to the ferrule. The ferrule can then be removably connected to the peripheral device for making and breaking an electrical coupling. The present invention provides a reliable connector for applications where the electrical connection requires frequent disassembly/reassembly, such as in wiring of portable audio equipment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the present invention, reference is below made to the accompanying drawings in the following section entitled Detailed Description of the Invention. 
     FIG. 1 is a longitudinal cross section of a pair of mating components, in accordance with the present invention. 
     FIG. 2 is a plan view of a ferrule (male component), in accordance with the present invention. 
     FIG. 3 is an end view of the ferrule, in accordance with the present invention. 
     Reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, a pair of mating components of connector  1  are shown in longitudinal cross section. A strain relief boot  10  (i.e., a female component of the connector  1 ) is configured to receive a ferrule  20  (i.e., a male component of the connector  1 ) and a suitable electrical wire (not shown). The boot  10  comprises a body  11  constructed from a suitable insulating material, such as a moldable plastic. The body  11  can be color coded in either solid or patterned colors to aid in identifying particular electrical wires. The boot  10  has a threaded portion  12  configured to receive a threaded portion  22  of ferrule  20 , below described, and a cavity  14  configured to receive an insulated electrical wire through an open end  15  having a given diameter. The threaded portions  12 ,  22  are optionally tapered (e.g., conical or frusto-conical). Gripper lugs  13  are annular ridges around body  11 . The gripper lugs  13  provide a degree of flexibility and purchase for positioning and holding the body  11 . An optional throat  16  has a restricted diameter (i.e., dimensioned smaller than the given diameter of the open end  15 ) in cavity  14  which is sized to snugly receive a specified wire diameter. Thus, the boot  10  is constructed in a variety of sizes, adapted for use on specific wire gauges, such as standard wire sizes. The throat  16  provides a measure of grip on an insulated jacket of the wire, thereby absorbing some of any subsequent longitudinal strain or bending stress on the wire. 
     Still referring to FIG. 1, the ferrule  20  is shown in longitudinal cross section. The ferrule  20  is constructed of an electrically conducting material such as copper, brass, aluminum, or the like. In some applications, such as connectors for audio equipment, the ferrule  20  could be constructed of a non-conducting resilient base material plated with an electrically conducting material. In other applications, constructing the ferrule  20  of an electrically conducting material plated with an electrically conducting non-oxidizing material such as gold, platinum, or the like may be desirable. The ferrule  20  is preferably constructed with a flat-end blade  21 , and a tapered truncated hollow cone-end threaded portion  22 . In use, the subject wire is first inserted through the open end  15 , the throat  16 , and the cavity  14  of the boot  10 . The length of the insulating jacket of the wire is then removed from the end of the wire, thereby exposing a length of the wire, such length being related to the approximate circumference of the threaded portion  22  and also being preferably sufficient to wrap two to three times around the threaded portion  22 . The exposed wire, preferably being stranded wire, is then wound around the threaded portion  22 . The threaded portion  22  of the ferrule  20  is then hand-tightened into the threaded portion  12  of the boot  10 , thus securing the exposed wire onto the ferrule  20 . The blade  21  of the ferrule  20  is then ready for connection to the device to receive electricity. While the present invention is directed at manual connection of a wire to a contact, such process could also be automated and performed by a machine. 
     Referring now to FIG. 2, the ferrule  20  is shown in plan view. The blade  21  is preferably configured in a flat arcuate fork, as shown, forming a contact  24  with an opening  25 . In this configuration, the blade  21  can be detachably inserted between a bolt head and a nut without disassembling the bolt from the nut. In a first embodiment, the contact  24  can be formed as a flat ring by eliminating opening  25 . In a second embodiment, the blade  21  could be formed as a solid pin for detachably insertion into a suitable socket. In a third embodiment, the blade  21  could be formed as a solid flat spade for inserting into a suitable socket. In any of possible embodiment, the contact  24  is removably secured to the subject device for receiving power, thereby allowing for frequent connect-disconnect cycles without loosening the good wire-ferrule connection achieved at the threaded portion  22  of the ferrule  20 . 
     Referring to FIGS. 2 and 3, a compression slot  23  is illustrated. The threaded portion  22  of the ferrule  20  is hand-tightened into the threaded portion  12  of the boot  10 . In order for the ferrule  20  and the boot  10  to mate properly, the dimensions of the threaded portion  12  must be approximately the same as that of the threaded portion  22  (i.e., little or no tolerance). When the subject wire is wound around the threaded portion  22 , a combinational diameter of the subject wire as combined with the threaded portion  22  is greater than the diameter of the threaded portion  22  alone. The combinational diameter depends on the wire gauge and the number of wraps made. In order for the threaded portion  22  to mate efficiently and properly with the threaded portion  12 , the combinational diameter is readjusted to approximately the original diameter of the threaded portion  22 . The compression slot  23  facilitates the threaded portion  22  being compressed, independent of the wire gauge and the number of wraps by allowing itself to close slightly as the threaded portion  22  is hand-tightened into the threaded portion  12 , thereby effecting a compression-fit (i.e., an interference-fit) between the portions  12 ,  22  using the wire, and, thus, forming a secure tight electrical connection between the subject wire and the ferrule  20 . In addition, the wire may experience a nominal deformation into the compression slot  23  during hand-tightening which furthers the interference-fit and improves electrical contact between the wire and the ferrule  20 . 
     Information as herein shown and described in detail is fully capable of attaining the above-described object of the invention, the presently preferred embodiment of the invention, and is, thus, representative of the subject matter which is broadly contemplated by the present invention. The scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and is to be limited, accordingly, by nothing other than the appended claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment and additional embodiments that are known to those of ordinary skill in the art are hereby expressly incorporated by reference and are intended to be encompassed by the present claims. Moreover, no requirement exists for a device or method to address each and every problem sought to be resolved by the present invention, for such to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. However, it should be readily apparent to those of ordinary skill in the art that various changes and modifications in form, semiconductor material, and fabrication material detail may be made without departing from the spirit and scope of the inventions as set forth in the appended claims. No claim herein is to be construed under the provisions of 35 U.S.C. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.”