Abstract:
A single-pole electrical connector includes an insulating sleeve and a retention ring positioned in the insulating sleeve. The retention ring defines an inner channel and a groove in a surface of the inner channel. The retention ring also includes a threaded hole intersecting the groove. A screw positioned in the threaded hole blocks the groove when in an extended position and leaves the groove unblocked when in a retracted position. A contact positioned in the inner channel includes a drive pin positioned in the groove. The contact is secured within the insulating sleeve when the screw is in the extended position and movable relative to the insulating sleeve when the screw is in the retracted position.

Description:
TECHNICAL FIELD 
     The invention relates to single pole cable connectors. 
     BACKGROUND 
     Single-pole connectors are used to connect a single wire or cable. One type of known connector uses a retention screw to secure a contact of the connector in an insulating sleeve of the connector. The contact includes a threaded hole that receives the retention screw, which also passes through the insulating sleeve. The contact attaches to an electrical cable on one end and the contact is configured to connect to another contact on the other end. 
     Another type of connector uses a contact having a locking drive pin. After a cable is connected to the contact, the contact is inserted into an insulated sleeve until the locking drive pin engages a locking structure in the sleeve. 
     SUMMARY 
     In one general aspect, a single-pole electrical connector includes an insulating sleeve defining an inner channel and a groove defined in a surface of the inner channel. A blocking mechanism is operable to be positioned to block the groove. 
     Embodiments may include one or more of the following features. For example, the connector may include a retention ring positioned in the insulating sleeve and defining at least a portion of the inner channel. The groove may be defined in an inner surface of the retention ring. The retention ring may carry the blocking mechanism, which may be, for example, a screw. To this end the retention ring may include a threaded hole that perpendicularly intersects the groove. The blocking mechanism also may be, for example, a snap in retaining pin, a rotating member, or a component glued or snapped into place in the groove. 
     The connector also includes an electrical contact sized to fit within the inner channel. A drive pin extending from an outer surface of the contact is sized to fit within the groove. Generally, the channel and contact have circular cross sections. 
     The screw may be a nonconductive screw having a nonconductive head and a nonconductive threaded portion. This offers advantages over screws having nonconductive heads and conductive threaded portions in that the screws are inexpensive to manufacture and pose no risk of exposed conductive material in the event that the head of the screw is broken. 
     In general, the screw is accessible from outside the insulating sleeve through a hole in the insulating sleeve. A cross section of at least a portion of the hole is smaller than a maximum cross section of the screw to prevent separation of the screw from the electrical connector. This ensures that the screw will not be lost and thereby eliminates a major source of inconvenience and user frustration. 
     The invention provides a single pole electrical connector that provides safe operation, that is inexpensive to manufacture, and that is easy to reuse. In particular, assembly and disassembly of the connector requires only a screwdriver. 
     The drive pin-and-groove connection arrangement provides considerable advantages over approaches that use a screw threaded into the contact to secure the contact in the insulating sleeve. In particular, the contact only needs to be positioned in the channel of the insulating sleeve with the drive pin aligned with the groove. The contact is then pushed completely into the insulating sleeve and secured in place by tightening the screw to block the groove. By contrast, to thread the screw into the contact, the contact needs to be carefully aligned, both radially and axially, with the screw in order to insert the screw into the hole in the contact. 
     Other features and advantages will be apparent from the following description, including the drawings, and from the claims. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIGS. 1A-1C are top, side and end views of a cable connector. 
     FIGS. 2A-2C are front, top and side views of a retaining ring of the connector of FIG.  1 A. 
     FIGS. 3A-3C are top, front and end views of a contact of the connector of FIG.  1 A. 
     FIGS. 4A-4D are sequential views showing assembly of the connector. 
     FIG. 4E is a sectional view taken along line  4 E— 4 E of FIG.  4 D. 
     FIG. 4F is a sectional view taken along line  4 F— 4 F of FIG.  4 D. 
     FIGS. 4G-4J are sequential, upper-half sectional views showing assembly of the connector. FIGS. 4G and 4H are sectional views taken along line  4 G— 4 G of FIG.  4 C. FIGS. 4I and 4J are sectional views taken along line  4 E— 4 E of FIG.  4 D. 
     FIGS. 5A and 5B are side and end views of a connector for use with the connector of FIG.  1 A. 
     FIGS. 5C and 5D side and end views of a contact of the connector of FIG.  5 A. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS. 1A-1C, a single pole cam-type cable connector  100  includes an insulating sleeve  105 . The sleeve  105  is generally cylindrical and includes a tapered end  110  from which an insulated cable  115  extends. The tapered end  110  is positioned opposite a cylindrical connection portion  120 . The portion  120  has an open end  125  that permits access to a conductive contact  130  and interacts with a connection portion of, for example, a mating connector or a supply panel to isolate the contact  130  from the external environment. 
     The insulating sleeve  105  includes a central portion  135  between the tapered end  110  and the connection portion  120 . The central portion  135  is grasped to manipulate the connector  100 . For this purpose, the central portion  135  includes raised ridges  140  that provide gripping surfaces. The central portion  135  also includes an expanded ring portion  145  having a protrusion  150 . The protrusion  150  includes an opening  155  through which a nonconductive screw  160  may be accessed. The opening  155  is sized to prevent removal of the screw  160 . As discussed in detail below, the screw  160  secures the contact  130  in place within the sleeve  105  and allows for removal of the contact  130  and reuse of the connector  100 . 
     The insulating sleeve  105  is made from an insulating material such as rubber. The sleeve  105  is generally rigid, but has slight flexibility at the ends  110 ,  125 . 
     Referring to FIGS. 2A-2C, the insulating sleeve  105  contains a retention ring  200  formed from a rigid material, such as plastic. The retention ring  200 , which is generally cylindrical, is positioned in the sleeve  105  in a region defined by the expanded ring portion  145 , and includes a protrusion  205  corresponding to the protrusion  150 . The protrusion  205  includes a threaded opening  210  that receives the screw  160 . The retention ring  200  retains the contact  130  within the sleeve  105 . 
     The retention ring  200  defines a central channel  215  sized to receive the contact  130 . A groove  220  is formed in a surface of the channel underlying the protrusion  205 . The groove extends from a first end  225  of the channel. The groove  220  terminates before reaching the second end  230  of the channel  215 . The groove  220  is intersected by the threaded opening  210 . 
     Referring to FIGS. 3A-3C, the contact  130  includes a generally cylindrical body portion  305  from which extends a generally cylindrical connection portion  310 . The body portion  305  defines a channel  315  along most of its length. The channel  315  extends from an end  320  opposite the connection portion  310  to just short of the connection portion  310 . In use, an electrical cable is positioned in the channel  315 . Two recessed holes  325  in the outer wall of channel are threaded to receive two set screws  330  used in securing the electrical cable in place. In other implementations, the cable may be secured using a single set screw, or by crimping or soldering. The contact  130  is made from a conductive material such as copper, copper alloys, or brass. Other conductive materials may be used. 
     A drive pin  335  extends from the body position  305 . As discussed below, and as shown in FIGS. 4G-4J the drive pin fits within the groove  220  of the retention ring  200  and is used in securing the contact  130  in the insulating sleeve  105 . 
     The connection portion  310  has a smaller diameter than the body portion  305 . The connection portion  310  includes a gap  340  that extends from an end  345  of the connection portion  310  to a hole  350  in the body portion  305 . The gap  340  allows for thermal expansion of the connection portion  310 . 
     The end  345  of the connection portion  310  is circular with a flattened section  355 . The flattened section  355  extends a short distance along the length of the connection portion  310  until it terminates in a circumferential groove  360  that extends partially around the circumference of the connection portion  310 . In use, the flattened section  355  permits insertion of the end  345  into a similarly-shaped opening in a mating contact. The contacts are then rotated relative to each other until the lip  365  is between the circumferential groove  360  and the end  345  locks with the corresponding circumferential groove in the mating contact. Thereafter, a front wall  370  of the groove  360  prevents axial movement of the contacts relative to each other. 
     Assembly of the contact  100  is illustrated in FIGS. 4A-4J. Referring to FIG. 4A, the electrical cable  115  is inserted into the tapered end  110  of the insulating sleeve  105  until the cable  115  extends from the end  125 , as shown in FIG.  4 B. As shown in FIG. 4A, the cable  115  includes multiple conductive elements  400  surrounded by an insulating sleeve  405 . 
     Referring to FIG. 4C, insulation is stripped from the end  410  of the electrical cable  115 , and the conductive elements  400  at the end  410  are placed in the channel  315  of the contact  130 . The two cable retaining plugs  330  then are tightened to secure the electrical cable  115  to the contact  130 . Once the contact  130  is attached to the end  410  of the electrical cable  115 , the electrical cable  115  is pulled back into the insulating sleeve  105 . The contact  130  is positioned so that the drive pin  335  fits within the groove  220  of the retention ring  200  as shown in FIGS. 4G and 4H. The contact  130  is pushed into the sleeve  105  until the drive pin  335  abuts the rear of the groove  220 , as shown in FIGS. 4D,  4 I and  4 J. The screw  160  then is turned until the screw  160  extends into the groove  220  and blocks movement of the drive pin  335  to lock the contact  130  in place. As shown in FIGS. 4E,  4 F and  4 J, screw  160  blocks the open end of the groove  220 , which prevents the drive pin  335  from being pulled out of the groove  220  and thereby prevents the contact  130  from being pulled out of the sleeve  105 . The screw hole  155  is positioned relative to the end of the groove  220  so that little, if any, axial motion of the contact  130  relative to the sleeve  105  is permitted once the groove  220  is blocked. Similarly, the groove  220  is sized relative to the drive pin  335  so that little, if any, rotational motion of the contact  130  is permitted. 
     Referring to FIGS. 5A and 5B a female connector  500  for use with the connector  100  includes an insulating sleeve  505  that is similar in shape and operation to the insulating sleeve  105  of the connector  100 . The sleeve  505  differs only in that it includes a connection portion  510  that is of smaller diameter than the connection portion  120  of the sleeve  105 , and is sized to be received within the connection portion  120 . The connector  500  includes a retention ring (not shown) that operates in the same manner as the retention ring  200 . 
     Referring to FIGS. 5C and 5D, a contact  515  of the connector  500  is configured similarly to the contact  130  of the connector  100 . The contacts differ in that the contact  515  includes a connection channel  520  instead of a connection portion  310 . The channel  520  is sized to receive the connection portion  310 . The channel  520  is circular and includes a flattened section  525  that conforms to the flattened section  355  of the contact  130 . The flattened section  525  extends only a short way along the length of the channel and serves to retain the connection portion  310  in the channel  520 , as discussed above. Friction between the connection portions of the insulating sleeves inhibits relative rotation of the connectors. 
     Other embodiments are within the scope of the following claims.