Abstract:
A wire connector applicator is capable of holding a clip of interconnected twist-on wire connectors in a tube which can be rotated by an electric motor. The connectors rotate with the tube for installation on the ends of stripped electrical wires. The invention is also directed to an interlocking twist-on wire connector which prevents axial separation and relative rotation of similarly configured group or clip of interlocked connectors.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application No. 60/517,168, filed on Nov. 4, 2003, which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   This invention is directed to an apparatus for installing twist-on wire connectors onto the ends of stripped electrical wires. The invention also concerns a twist-on wire connector whose shape has been optimized for use with the applicator of the present invention. 
   Twist-on or screw-on wire connectors have been used for many years to provide a simple and efficient means of mechanically and electrically joining stripped ends of two or more electrical wires. Such connectors typically have a frusto-conical housing or shell with a metallic spring disposed in the interior of the shell. The process of installing one of these twist-on wire connectors usually includes the step of first stripping the insulation off the ends of a number of wires. Next, the twist-on wire connector is placed onto the stripped ends of the wires. Once the connector is in place, it is rotated or twisted, typically by hand, until the wires are joined together. As a result of this process the electrical wires are electrically and mechanically joined, with the outer insulating shell of the connector providing protection for the stripped wire ends. 
   Many twist-on wire connectors include opposing, outwardly-extending wings or fins to provide a comfortable and accessible surface to facilitate twisting by hand. However, applying large numbers of these connectors by hand can lead to fatigue or repetitive stress injuries. Furthermore, the several steps involved in terminating or connecting wires makes the process slow and inefficient where numerous connections need to be made. 
   Devices have been made to address the need for repetitive twisting motion. These devices, which may be referred to as “twist assist” devices, have a conically shaped cup which receives the wire connecter&#39;s shell. At the other end of the twist assist device there is an axially-extending shaft, which is inserted into a driver of some sort. The driver can be either a hand-operated tool or a powered drill or screw-driver. While these twist assist devices address the problem of repetitive motion injury, the many steps still required to apply connectors keep the process relatively slow and in need of improvement in production situations where large numbers of connectors have to be applied. 
   Other devises are also known for attaching twist-on connectors. One such apparatus is shown in U.S. Pat. No. 3,016,774 to Minobe, the disclosure of which is herein incorporated by reference. It includes a receptacle or hopper for holding a large number of twist-on connectors. The connectors are serially fed from the hopper through a tube or semi-flexible hose to the hand-operated applicator. A switch initiates the rotating motion to apply the connector onto the stripped ends of the wires. Devices of this type are typically used at a fixed workstation in an assembly line operation. 
   While this type of apparatus addresses repetitive stress problems and helps to speed up the process of applying connectors by automatically feeding a new connector to the applicator, these devices are bulky and not easily transportable. In addition, these devices cannot assist tradespeople who quickly move from one location to another. While the twist assist drivers mentioned above are fully portable, they operate on only one connector at a time. What is still needed in the art is a device, which combines the advantages of serially feeding connectors and with the portability of hand-held twist assist drill/drivers. 
   SUMMARY OF THE INVENTION 
   The present invention is an applicator which automatically feeds and installs twist-on wire connectors. The applicator is lightweight, compact, and portable. In one embodiment, the housing of the device is preferably gun-shaped with an elongated barrel portion, a handle portion and a central case between the barrel and the handle. Within the elongated barrel is a rotatable tube with an opening at one end for receiving a plurality of wire connectors. These connectors are preferably disengagably interlocked wing-type twist-on wire connectors. A spring is disposed in the tube and is compressed when a clip of interlocked wire connectors is fed into the tube. The spring urges the connectors toward the opening of the tube. 
   A retaining cap attached to or integral with the barrel is positioned adjacent the opening of the tube and prevents the clip of connectors from prematurely exiting before the connector has been applied to the stripped ends of the wires. Bearings surround a portion of the tube to mount it for rotation within the barrel. 
   The device further includes an electric motor disposed in the case portion of the housing for rotating the tube. Preferably the motor is connected to a variable speed controller and a planetary gear assembly to provide for variable speed and torque. The motor is powered by a standard power drill/driver rechargeable battery pack, a portion of which is disposed in the handle portion of the housing. The device further includes an easily accessible switch for activating and deactivating the motor and preferably a switch for the user to set the operating speed of the motor. 
   The tube includes at least one protrusion extending radially inwardly from the inside wall of the tube. As the electric motor rotates the tube, the protrusion contacts the wing or other radially extending rib of a wire connector causing it to rotate. 
   The invention is also directed to twist-on wire connectors, preferably detachably interlocking wing-type connectors. In one embodiment, the wire connector has opposing wings that extend radially outwardly from the outer surface of the wire connector preferably adjacent the open end of the shell. The outer surface of the wire connector also includes at least one projecting member which extends radially outwardly from the outer surface and is preferably positioned near the closed end of the shell. The interior surface preferably near the open end of the shell also includes at least one slot. The outer projecting member is adapted to engage the slot. 
   In another embodiment, the wire connector has opposing wings that extend radially outwardly from the outer surface of the wire connector preferably adjacent the open end of the shell. The outer surface of the wire connector also includes at least one rib or thread, preferably a circumferential rib or thread, and at least one projecting member both of which extend radially outwardly from the outer surface and are preferably positioned near the closed end of the shell. The interior surface preferably near the open end of the shell also includes at least one groove or thread, preferably a circumferential groove or thread, and at least one slot. 
   The outer circumferential rib or thread and the outer projecting member are adapted to engage the inner groove or thread, or slot respectively. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic sectional view of a preferred embodiment of the wire connector applicator of the present invention. 
       FIG. 2  is a front elevation view of the applicator with the right half of the housing removed to expose the interior components. 
       FIG. 3  is a perspective view of the applicator with portions of the housing removed and showing an alternate configuration of the reservoir tube interior. 
       FIG. 4  is a perspective view of a preferred embodiment of a wire connector of the present invention. 
       FIG. 5  is a side elevation view of a pair of interlocked wire connectors of the present invention with the uppermost wire connector shown in section. 
       FIG. 6  is a side elevation view of an alternative embodiment of the wire applicator of the present invention shown attached to a cordless drill and having part of the housing removed to expose the gear assembly. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A wire connector applicator  10  according to the present invention is shown in  FIGS. 1-3 . Its housing  12  has an appearance generally resembling a standard power drill/driver. The applicator  10  has an elongated barrel  14  which is preferably made of a hard, durable plastic. Extending at about a right angle and slightly off center of the barrel  14  is a handle  18 . A central case  16  is disposed between the handle and the barrel. At the lower most end of the handle  18  is an opening to accept a portion  20  of a standard rechargeable battery pack  22 . The battery pack is retained by clips  24  ( FIG. 2 ). A trigger  26  extends through an opening  28  in the handle and is biased to extend out from the handle. The trigger is positioned to be accessible by a user&#39;s index finger such that the trigger can be squeezed towards the housing to activate a switch  30  for controlling power to an electric motor  32 . The electrical circuit between the electric motor, switch and the battery is provided through a switch connector  34  which is disposed in the handle portion of the housing. 
   Additionally, a variable speed controller  36  is positioned above the switch connector  34 . It is included in the electrical circuit to allow the user to vary the speed of the motor and thereby control the rotation speed applied to the wire connector. A planetary gear assembly  38  is connected to the electric motor  32 . Both the motor  32  and planetary gear assembly  38  are contained within the case portion  16  of the housing. Extending axially out from the planetary gear assembly is a driveshaft  40 . A pinion  42  is mounted on the end of the driveshaft. The driveshaft terminates at a bearing  44  which is mounted in the case to support the driveshaft. A ring gear  46  engages the pinion. A central opening  47  ( FIG. 3 ) in the ring gear receives an elongated connector reservoir tube  48  which is not required to be cylindrically shaped. The tube  48  may or may not extend the entire length of the barrel. The ring gear  46  can be either a separate part attached to the tube  48  or it can be integrally formed therewith. In either case, when the pinion  42  is driven by the motor  32 , it causes the ring gear  46  to rotate which in turn causes the tube  48  to rotate with the ring gear. 
   A compression spring  50  is disposed in the tube  48 . Preferably the spring  50  is attached to the closed end  52  of the tube. Alternatively, if the end  52  of the tube is open, the spring  50  may contact or be connected to the closed end of the barrel. The spring is compressed by the introduction of wire connectors  54  from the front opening  56  of the reservoir tube. The spring biases the connectors toward the opening  56 . A retention spring at the front of the tube prevents unwanted, premature release of the connectors from the tube. 
   The rotating action of the reservoir tube  48  can be imparted to the wire connectors  54  in a number of ways. In the embodiment shown in  FIG. 3 , the inner surface  55  of the front opening  56  of the reservoir tube  48  includes opposing slots  58  which accept the wings  60  of a wire connector  54 . In the embodiment shown in  FIG. 2 , the front opening  56  of the reservoir tube  48  includes at least one protruding member  62  which extends radially inwardly to engage a surface of the wing  60 . The embodiment shown in  FIG. 2  is preferred since the wings of the wire connector do not have to be aligned with the slots during loading of a clip of connectors into the reservoir tube  48 . 
     FIG. 1  shows a retaining mechanism  64  attached to the front of the reservoir tube to restrain the ejecting force on the wire connectors created by the spring  50 . This mechanism includes a spring retained in a slot in the front cap of the barrel. However, once the foremost wire connector has been twisted on to the stripped ends of the wires and the device is pulled away from the just terminated wires, the restraining action of the spring is overcome, allowing the wire connector to exit the tube. This pulling away adds enough force to the urging force of the compression spring  50  so that the retaining mechanism can no longer hold the wire connector, which is thereby released from the reservoir tube and front cap. 
   The wire connectors can be inserted one by one through the opening of the retention mechanism and into the reservoir tube. If the reservoir tube is closed at end  52 , the wire connectors will be housed and stored in the reservoir tube. However, if the reservoir tube is open at end  52 , the wire connectors inserted into the tube may pass through the tube and be housed and stored in the elongated barrel  14 . In either case, it would be more efficient and desirable to be able to load, feed or insert a group or clip of wire connectors in one motion. In another aspect, the invention is directed to interlocking wire connectors designed for this purpose. 
     FIG. 6  illustrates an alternate embodiment of the present invention wherein the drive motor and its associated battery and controls are deleted. In  FIG. 6 , an input shaft  45  extends from the planetary gear assembly  38  and through an opening  49  in the case  16 . The input shaft  45  may be engaged by a standard chuck  51  of a cordless electric drill  53 . The housing  12  includes anti-rotation straps or restraints  57  which are releasably connected to the drill housing  59  to prevent the housing  12  from rotating with the drill&#39;s chuck  51 . The anti-rotation straps may include a buckle or a standard Velcro cinch strap for adjusting and tightening the strap. The cordless drill  53  is used to cause rotation of the planetary gear assembly&#39;s input shaft  45 , which in turn causes the pinion  42  and ring gear  46  to rotate, thereby rotating the reservoir tube. This embodiment provides a more economical tool which takes advantage of the fact that it is common for tradespeople to carry their own general purpose cordless electric drill with its own rechargeable battery pack. 
     FIGS. 4 and 5  show one embodiment of an interlocking wire connector  66 . The interlocking wire connector  66  includes opposing wings  68  and a circumferential rib  70 , both of which extend radially outwardly from the outer surface of the shell  72 . Preferably, the wings  68  are adjacent the open end  74  of the wire connector and at least one rib  70  is near the closed end  76  of the wire connector. Also on the outer surface of the shell  72  is at least one projecting member  78 . The projecting member also extends radially outwardly from the outer surface, preferably extending as far as the rib  70 . In addition, the projecting member preferably is positioned adjacent the rib and closer to the closed end of the connector than the rib. 
   The inner surface  80  of the shell includes at least one groove  82 . The groove preferably circumscribes the inner surface and is near the open end of the connector. The circumferential groove  82  is adapted to engage the rib  70  of a similarly configured wire connector. The inner surface  80  also includes at least one axially-extending slot  84  preferably near the groove and closer to the closed end of the connector than the groove. 
   The projecting member  78  is adapted to engage the slot  84  and the rib  70  is adapted to engage the groove  82  of a similarly configured wire connector. Preferably, the projecting member, rib, groove and slot are aligned circumferentially at the same position as the wings to facilitate the interlocking of the wire connectors. The wire connectors can be detachably interlocked by forcing the closed end of one connector into the open end of a similarly configured wire connector until the rib and projecting member mate with groove and slot respectively. An interference fit is created between the rib and groove and the projecting member and the slot. 
   This fit or engagement of rib and groove and projecting member and slot prevents the interlocked wire connectors from being axially separated before the desired time. The fit between the projecting member and the slot also prevents relative rotation between the interlocked wire connectors. In other words, the engagement of the projection member and slot forces the clip to rotate as a single unit. This feature prevents unnecessary friction and wearing of the wire connecters among other things. 
   The operation of the wire connector applicator and the detachably interlocking wire connectors of the present invention is as follows. The wire connectors can be interlocked by the user by first aligning the wings of two wire connectors and then pushing the closed end of one into the opening of the other until the rib snaps into the groove and the projecting member snaps into the slot. Preferably a plurality of wire connectors is provided in an interlocked condition. This may alternately be done at the factory so a fully formed clip is supplied to the user. 
   The clip of interlocked wire connecters is positioned so that either the wings  60  are aligned with slots  58  of the reservoir tube or aligned to avoid contacting the protruding member  62 , depending on the configuration of the reservoir tube. The wire connector with an exposed closed end is first inserted into the reservoir tube. The spring  50  is compressed as the clip is pushed into the reservoir tube  48 . The open end of the last wire connector of the clip to enter the reservoir tube is pushed past the retaining spring which contacts the shell of this last wire connector of the clip and prevents the spring  50  from pushing the clip back out of the reservoir tube. 
   The number of wire connectors that can be loaded into the application depends on the size of the connectors and the length of the reservoir tube or the barrel. These can be chosen to fit a particular application. Preferably, the reservoir tube can hold ten interlocked wire connectors. Once the reservoir tube has been loaded with a clip of wire connectors, the process of applying the wire connectors to the exposed ends of electrical wire can proceed quickly. The stripped wires are inserted past the opening of the retaining mechanism and into the open end of the outermost wire connecter. The wires can be brought to the applicator, or vice versa, to effect this insertion. The openings of the wire connectors are coaxially aligned with the opening of the reservoir tube and retention mechanism. Once the stripped wires contact the inside surface of the shell and can be inserted no further, the trigger  26  is depressed to activate the electric motor which causes the planetary gear assembly  38 , the shaft  40 , the pinion  42 , the ring gear  46  and the reservoir tube  48  to rotate. As the tube rotates, the protruding member  62  or slots contact the wing or wings of the outmost wire connector causing the entire clip of connectors to rotate. This rotation fixes the outermost connector on the electrical wires. After the outermost connector has been applied to the wires, the applicator is pulled away from the terminated wires, releasing the applied connector from the reservoir tube and remaining wire connectors. As the outermost wire connector exits the tube, the spring  50  urges the clip forward so that the next wire connecter contacts the retaining mechanism preventing the clip from exiting the tube. The next connector can then be applied in a similar manner.