Electrical terminal with arc arresting region

An electrical terminal (20) including a body (22) having first and second connecting portions (30, 50). The first connecting portion (30) includes two beams defining a terminal-receiving slot (44) therebetween. Each beam (32) has a primary contact surface (38) and at least one beam includes a secondary contact surface (40) extending orthogonally into the terminal-receiving slot (44). The primary and secondary contact surfaces on the one beam are spaced both vertically and horizontally from each other. Upon mating a pin terminal (70) to electrical terminal (20) the secondary contact surface (40) engages the pin terminal (70) at a first location (74) thereon defining an electrical arc- arresting region. Upon further insertion the pin terminal (70) engages the primary contact surfaces (38) at second locations (76) thereon spaced at least horizontally from the first locations (74).

FIELD OF THE INVENTION
 This invention relates to electrical connectors and more particularly to
 electrical terminals having a region to accommodate deterioration owing to
 electrical arcing.
 BACKGROUND OF THE INVENTION
 Electrical connectors are sometimes used in applications wherein the
 connectors need to be mated and unmated without first disconnecting the
 power source. When an electrical potential exists between the terminals of
 the connectors, arcing can occur as they are mated and unmated, thus
 causing deterioration of the terminals. Various approaches have been used
 to reduce such deterioration or to fabricate terminals that can withstand
 deterioration.
 U.S. Pat. No. 5,176,528 discloses a pin and socket connector assembly in
 which each of a pair of power lines is connected to a pair of mating
 terminals such that one of each pair of mating terminals are allowed to
 deteriorate or be "sacrificed" while the integrity of the other of the
 pair is maintained. The use of a pair of "sacrificial" terminals for each
 power line increases the number of terminals that must be included in a
 connector housing and the overall dimensions of the connector.
 U.S. Pat. No. 5,591,039 discloses the use of an arc arresting or
 sacrificial ring located near the opening of each socket terminal in the
 connector. The mating pin terminal engages the ring, which receives any
 electrical arc before the pin terminal engages the socket terminal. This
 approach requires an extra member for each receptacle terminal and
 additional steps to assemble the connector.
 It is desirable and more cost effective, however, to have an electrical
 terminal that can provide a sacrificial function as well as maintain the
 integrity of the electrical connection.
 SUMMARY OF THE INVENTION
 The present invention is directed to a socket terminal that overcomes the
 problems of the prior art. The electrical terminal includes a body having
 first and second connecting portions. The first connecting portion is
 adapted to mate with a pin terminal and includes two beams extending
 substantially parallel to one another from an edge of the body and
 defining a terminal-receiving slot therebetween. Each beam has a primary
 contact surface spaced inwardly form leading ends of the beams and
 extending orthogonally into the terminal-receiving slot. At least one of
 the beams includes a secondary or sacrificial contact surface proximate
 the leading end thereof. The primary and secondary contact surfaces on the
 at least one beam are spaced both vertically and horizontally from each
 other. The corresponding primary contact surfaces of the two beams are
 substantially opposed to each other. Upon inserting a pin terminal into
 the terminal-receiving slot, the secondary or sacrificial contact surface
 engages the pin terminal at at least one first location thereon. Upon
 further insertion of the pin, the pin engages the primary contact surfaces
 at second locations thereon, the second locations being spaced at least
 horizontally from the at least one first location on the pin. The
 secondary or sacrificial contact surface on the at least one beam and the
 at least one first locations on the pin terminal define an electrical arc
 arresting region thereby preventing deleterious electrical arcing between
 the pin terminal at the second locations and the primary contact surfaces
 on the beams.
 For purposes of illustrating the invention, the terminal is being shown in
 a terminal block for use in a control panel.
 It is an object of the invention to provide an electrical terminal that
 includes a structure that provides at least one electrical arc-arresting
 region and a separate region for electrical connection when the connectors
 having the terminals are fully mated.
 It is another object of the invention to provide an electrical terminal
 having the above capabilities that is cost effective to manufacture.
 It is a further object of the invention to provide electrical terminals for
 terminating to stripped wire ends that prevent the wires from entering the
 socket that is to be mated to a pin terminal.
 Embodiments of the invention will now be described by way of example with
 reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS
 Referring first to FIGS. 1 through 8, electrical terminal 20 includes a
 body 22 having first and second connecting portions 30, 50. The first
 connecting portion 30 includes two beams 32 that extend from body edge 24
 to leading ends 34, each beam further including a C-shaped bend 36
 intermediate the leading end 34 and terminal body 22. Beams 32 are
 essentially parallel to each other and define a terminal-receiving slot 44
 therebetween. Each beam 32 includes a primary contact surface 38 on the
 C-shaped bend. At least one of the beams 32 includes a secondary or
 sacrificial contact surface 40 proximate the leading end 34 thereof. In
 the embodiment shown, both of the beams 32 include secondary contact
 surfaces 40. It is to be understood that only one of the beams needs the
 sacrificial contact surface. The primary and secondary contact surfaces
 38, 40 of each beam extend orthogonally into slot 44 and are spaced both
 vertically and horizontally from one another. The primary and secondary
 contact surfaces 38, 40 of one of the two beams 32 are opposed to the
 corresponding primary and secondary contact surfaces of the other of the
 two beams 32.
 Terminal 20 is stamped from an iron copper alloy or other suitable metal
 stock having a thickness of about 0.5 millimeters and is selectively
 plated at the contact surfaces with a noble metal such as a gold alloy, as
 known in the art. The beams of terminal 20 generate a sufficient normal
 force to interconnect to signal carrying terminals and the terminal has
 sufficient thickness and current carrying capability to transmit power.
 FIGS. 1, 2, and 4 illustrate the position of terminals 20 in
 terminal-receiving passageways 62 of a terminal block housing 60. Body 22
 of terminal 20 includes barbs 28 extending from side edges 26 for securing
 the terminal 20 in the passageway 62. For purposes of illustration,
 terminal block housing 60 is of the type disclosed in U.S. patent
 application Ser. No. 08/899,458. It is to be understood that terminal 20
 may be used in other connector housings and terminal block configurations.
 As can be seen in these Figures. the primary contact surfaces 38 are
 adjacent one side of passageway 62, the secondary contact surfaces 40 are
 adjacent the opposite side of passageway 62, and slot 44 is open to the
 mating face 63 of the housing.
 The second connecting portion 50 of terminal 20 is shown as a flat member
 extending orthogonally from body 22. Portion 50 includes aperture 52 and
 is adapted to be received on an upper surface of the housing 60 and
 secured thereto with screw 64 and nut 66, or other devices as known in the
 art. The collar 65 of screw 64 is adapted to engage a stripped end of a
 wire (not shown), as known in the art.
 FIGS. 5 through 8 illustrate the mating sequence of a pin terminal 70 in
 housing 78 with the socket terminal 32 in housing passageway 62. For
 purposes of illustration the portions of beams 32 underlying pin terminal
 70 are shown in phantom. As the leading end 72 of pin terminal 70 enters
 passageway 62, it is received in terminal-receiving slot 44 and is moved
 into physical and electrical engagement with secondary or sacrificial
 contact surfaces 40 of terminal 30 at first locations 74 on two sides of
 pin terminal 70, as shown in FIGS. 5 and 6. Upon further insertion of the
 pin terminal 70 into slot 44, the pin terminal 70 engages primary contact
 surfaces 38 at second pin locations 76, as shown in FIGS. 7 and 8. As can
 best be seen in FIGS. 5 and 7, the first and second pin locations 74, 76
 are along opposite edges of pin terminal 70 and are at least spaced
 horizontally from one another. The secondary or sacrificial contact
 surfaces 40 and first pin terminal locations 74 define electrical
 arc-arresting regions that receive any arcing that may occur as the
 respective terminals 20, 70 are mated or unmated while power is applied to
 the connector assembly. The electrical arc-arresting regions prevent
 deleterious electrical arcing between the pin terminal at second locations
 76 and primary contact surfaces 38. The two beams 32 of the socket
 terminal 20 provide multiple points of contact at each of the locations
 74, 76, which is desirable for carrying power. FIGS. 9 and 10 illustrate
 another embodiment 120 of a terminal made in accordance with the
 invention. In this embodiment, the first connecting portion 130 is
 identical to that of terminal 20. The second connecting portion 150 is
 adapted to cooperate with a spring clamp 154 of the type disclosed in U.S.
 patent application Ser. No. 09/092,473. FIG. 10 illustrates one wire 80
 mated with a terminal 120. The body 122 of second connecting portion 150
 is configured to be received in a terminal-receiving passageway 162 of
 terminal block housing 160 such that body 122 provides a stop surface for
 the stripped end 82 of wire 80, thereby preventing the bare wire from
 being inserted too far into the passageway and into the first connecting
 section. FIGS. 11 and 12 illustrate a further embodiment 220 of a terminal
 made in accordance with the invention. In this embodiment the first
 connecting portion 230 is identical to that of terminal 20. The second
 connecting portion 250 is a cage design, as known in the art. FIG. 12
 illustrates one wire 80 mated with a terminal 220. As best seen in FIG.
 12, the body 222 of second connecting portion 250 and terminal-receiving
 passageway 262 of terminal block housing 260 are configured such that
 passageway surface 263 provides a stop surface for the stripped end 82 of
 wire 80, thereby preventing the bare wire from being inserted too far into
 the passageway and into the first connecting section.
 The present invention has the advantage of providing two separate
 electrical connecting areas for each mating pair of terminals. The initial
 connection at a first location defines an arc-arresting region that
 protects the integrity of the electrical connection between the pair at a
 second location. The terminal has the capability to transmit power as well
 as signals.
 It is thought that the electrical terminal of the present invention and
 many of its attendant advantages will be understood from the foregoing
 description. It is apparent that various changes may be made in the form,
 construction, and arrangement of the parts thereof without departing from
 the spirit or scope of the invention, or sacrificing all of its material
 advantages.