CA1304464C - Low-voltage, high current capacity connector assembly - Google Patents

Abstract

The cylindrical plug of a low-voltage, high current capacity connector assembly has an axially positioned sleeve wiping contact and a transversely positioned U-shaped channel member to provide two pairs of planar wiping contact surfaces parallel to the plug axis and substantially perpendicular to the plug housing surface. The socket component, which will accept standard low-voltage, low current car appliance plugs, includes an internally mounted, closed face pin contact and a barrel contact having depending ears positioned to engage the protruding sides of the plug U-shaped channel member. The socket also has an internal boss and housing lip to prevent electrical activation of a standard automotive cigarette lighter plug, and the plug component of the connector assembly has the sleeve contact recessed to prevent contact following insertion into a conventional cigarette lighter socket.

Description

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LOW-VOLTAGE, HIGH CURRENT CAPACII'Y CONNECTOR ASSEMBLY

_ield of the Invention:
The present invention relates to low-voltage type connectors having a high direct current capacity for use with battery-powered heavy duty appliances.
Desc~t _ n of the Prior Art:
In recent years, low-voltage direct current (e.q., 12 VDC) hand-held appliances and tools have proliferated for use in the car and around the home. Some appliances, such as the hand-held car vacuum cleaners and car polishers,-are intended for operatior using power supplied from the car battery. These appliances, which are relatively low current devices (i.e., 2-6 amps), typi-cally employ a plug connector compatible with the socket compo-nent of a conventional, dash-mounted automotive cigarette lighter. The necessity for use of these appliances in close proximity to a vehicle having a lighter socket has restricted somewhat the utilization of the same appliances around the home.
Many hand-held tools used around the home, in comparison, require relatively high current levels (i.e., 8-20 amps). These high current appliances include hedge trimmers, grass trimmers, etc~, which can seriously tax the capacity of self-contained ba~-tery packs which typically are of the NiCd variety. A portable, lead-acid battery pack has been proposed as offering increased power capacit.~ and lonyer operation times between charging. See .

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co-pending application of Gierke et al. entitled "Mobile Power Tool and Appliance operating System't Canadian Patent Application 546,274 filed 8 September, 1987. As the proposed battery pack would not be self-contained with the power kool or appliance itself, an important feature of the proposed system would be a low-voltage high current capacity connector assembly that would enable the battery pack to be connected and disconnected to a variety of different tools.
Moreover, because of the existence of a variety of automotive appliances having cigarette lighter socket-compatible low current plug connectors, a high current capacity connector assembly that could, without modification, accommodate existing low-voltage, low current plug connectors would extend the usefulness of the proposed system.

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~L3~ 4 S~Jl`fM.A~Y O_T_P,_NVENT I ON
In accordance with the purpose of the invention, as embodied and broadly described herein, the socket for a low-voltage, high direct current connector of the plug-and-socket type of this invention comprises a non-conductive, generally cylindrical hous-ing having an axis and a plu~-receiving axial end, and a first wiping electrical contact element positioned within the housing at the other housing axial end proximate the axis. The socket further includes a second wiping electrical contact element elec-trically isolated from the first element and proximate the outer housing periphery at a preselected circumferential position~ The second wiping contact element has at least one wiping contact surface parallel to the axis and substantially perpendicular to the housing outer periphery at the circumferential position. The first and second wiping contact elements are configured for mating with complementary wiping contact members carried by a high current plug during plug insertion to a predetermined axial location.
: Preferably, the socke~ is fur~her configured to optionally receive conventional low current automotive appliance plugs of the type having an a~ially positioned abuttable contact member at : the insertable plug end and a spring contact member positioned at the low curren~ plug periphery. In this case the first wiping contact element includes means for electrica~ly connecting to the ., ~,, ~ . ., ~.3~4~

abuttable contact mernber and the second wiping contact element includes means for electrically connecting to the spring contact member when the erld of the low current plug is inserted in the socket to a predetermined axial location.
It is also preferred that the second wiping contact ele~ent comprises a barrel support portion positioned ~ithin the housing and opposed integral ear portions extendiny substantially radi-ally outward from the barrel portion parallel to said housing axis and substantially perpendicular to the housing periphery.
The socket further includes a socket lead comprising a tab ex-tending from, and integral with, the barrel portion, and spring means comprising a second tab integral with the barrel portion, the second tab being configured and positioned for engaging re-cesses in the periphery o~ a plug to restrain the inserted plug against axial movement counter to the insertion direction.
It is s~ill further preferred that the socket include lock-out means for preventing electrical connection to at least one of ~he first and second wiping contact elements upon insertion into the socket of a conventional automotive cigarette lighter plug o~
a kind having a generally cylindrical housing with an axially in-sertable end and having a heating element coiled in the axial face of the insertable lighter plug housing end~
Further in accordance with the present invention, the plug for a low-voltage, high direct current connector assembi~ of the , ~3~ ;4 plug-and-socket type of this invention comprises a generally cy-lindrical housing forrned ~rom a non-conductive material and havin~ an axis and a housing axial end insertable in a socket.
The plug has a first wiping ccntact member positioned at the in-sertable housing end and a second wiping contact member electri-cally isolated from the first member and extending radially out-ward from the periphery of the plug housing. The second member has at least one planar wiping contact surface disposed parallel to the housing axis and substantially perpendicular to the plug housing periphery.
Preferably, the second member is U-shaped and protrudes ra-dially outward of the plug housing at diametrically opposed loca-tions, the bottom of the U-shaped member being oriented toward the housing insertion end, and the protruding sides of the U-shaped member forming two pairs of planar wiping contact sur-faces.
It is further preferred that the plug include safeguard means for preventing electrical connection to at least one of the first and second wiping contact members upon inadverten~ inser-tion of the plug into a conventional automotive cigarette lighter socket of the type having a contact face disposed in a plane axially spaced from a plug-receivin~ end and perpendicular ~:o the direction of plug insertion.

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Still further in accordance with the preSerlt in~ention, the low-voltage, high direct currerlt connector assembly of this invention comprises an elollgated, hollow socket having an axis of elongation, a pair of socket leads, and a plug-receiving axial end; a plug receivable in the socket end upon insertion along the axis and having a pair of plug leads; and means for retaining the plug in the socket at a predetermined axial insertion position.
The assembly also includes a first wiping contact means for elec-trically connecting a respective one of the pair of socket leads to a respective one of the plug leads at the insertion position, the first wiping contact means including first mating contact surfaces positioned proximate the axis. The assembly also in-cludes second wiping contact means electrically interconnecting the other of the pair of socket leads to the other of the pair of plug leads at the insertion position, the second ~iping contact means including second mating contact surfaces positioned distant the axis.
Preferably, the second wiping contact means also comprises means for orienting the pluq circumferentially with respect to the axis, and vherein the socket includes an axial socket exten-sion cooperating with the second wiping contact means for ori-enting the plug.
The accompanying drawing, which is incorporated in and con-stitutes a part of this specification, illustrates one embodimenc ; -6-, ., ~304464 of the invention and, together with the description, serves to explain the principles of the invention.

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_RrE.`F IlES~-RIPTI_N OF T~F, DRAWING
Fig. 1 is a schematic sidc view of a connector assembly of the plug-and-socket type made in accordance with the present invention;
Fig. 2 is a cut-away depiction of the connector assembly shown in Fig. l;
Fig. 3 is a cut-away view of the socket component shown in Fig. l;
Fig. 4 is a cut-away view of ~he socket of Fig. 1 also showing insertion of low-voltage type plug connector;
Fig. 5 is a cut-away view showing the high current plug com-ponent of Fig. 1 mated with the high current socket component of Fig. l;
Pig. 6 is a frontal vew taken along the line 6-6 in Fig. 3;
Fig. 7 ls a sectional top view of the plug component of Fig. 1 taken along the line 7-7;
Figs. 8 and 9 are sectional side views of the socket compo-nent of Fig. 1 showing details of structure for preventing ~lec-trical contact during insertion of an automotive cigarette lighter plug;
Fig. 10 is a sectional view~of plug component of Fig. 1 showing details of str~cture for preventing electrical contact during insertion into automotive cigarette lighter socket;

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~3~ 64 Figs. 11 and 12 are top and side views, respectively, of the pin contact used in the socket component of Fig. l;
Figs. 13 and 14 are side and top detail views of the barrel contact used in the socket component of Fig. 1;
and Figs. 15-17 are top, side, and end views, respectively, of th~ U-shaped member contact of the plug component shown in Fig. 1.
(It is noted here that Figs. 14, 16 and 17 are taken along line 14-14 in Fig. 13 and lines 16-16 and 17-17 in Fig. 15 respectively.

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_ES R I PT 10 ~ OF T_IF. _RF.E:`F,RREI?_F.MBOD I ~r F.NT
Reerence will now be made in detail to the present pre-erred embodiment of the invention, an example of which is illus-trated in the accompanying drawing.
The preferred embodiment o~ the low-voltage, high current capacity connector assembly of the present invention is shown in Figure 1 and is represented generally by the numeral 20. Con-nector assembly 20, which is of the plug-and-socket type, in turn includes a plug component, designated generally as 22, and a socket component designated generally by the numeral 24. Also shown in Figure 1, ~or reasons that will become apparent from the succeeding discussion, is a broken-line representation of a lo~-voltage, low current plug connector such as is conventionally used to power automotive appliances from a cigarette lighter socket, the conventional plug connector being designated general-ly by the numeral 26.
In accordance with the preseni invention, the plug component of the low-voltage, high direct current capacity connector assem-bly includes a generally cylindrical housing having an axis and an axially end intended to be insertable in a socket component~
As embodied herein, and as shown particularly in F'igures 1 and 2, plug 22 includes cylindrical housing 30 having an axis 32 and an axial end 34 intended to be inserted into socket 24. Piug 22 also includes an opposed axial end designated generally 36 which -10~

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can be configured for gripping by a user and from which power cord ~7 having plug leads 39, 40 extends for connection to a suitable appliance or po~er tool (not shown). Housing 30 prefer-ably is formed of an appropriate non-conductive mat~rial such as a moldable, impact-resistant plastic and can be formed in two mating halves, for permitting "clamshell" type assembly or molded as one piece around internal parts (~insert molded"J. It is pre-ferred that plug end 34 include a face member ~2, also formed of a non-conductive material. Face member 42 can be formed inte-grally with cylindrical housing 30 and can be provided ~ith a shape suitable for providing a ~lead in" function to assist in insertion into socket 24, such as the truncated conical "lead-in"
shape used in the embodiment pictured in Figure 1.
Further in accordance with the present invention, the plug component includes a first wiping electrical contact ~ember posi-tioned at the insertable housing end. By the terrn "~iping con-tact~ it is meant that the contact member has a si~nificant con-tiguous contact surface area which comes into sliding contact with an opposing contact member also having a signi~icant contig-uous contacting surface during the course of establishing the electrical connection between the two members. The "wiping" er,-gagement acts to rejuvenate the metal contact surface by removing at least in part any oxide or other non-conductive layer that may have built up on the contact surface. The completed contact is ~ :
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characterized by electrical conduction across the maL ing con-tacting areas thereby affording high current capacity and minimizing ohmic heat;n9 due to cont~ct imperfections and contam-ination.
As embodied herein, and with initial reference to Figure 2, a hollow conductive sleeve 44 is positioned in port 46 fornled in plug face 42. Again, these elements can be insert molded in a one-piece molding. Sleeve 44 can be made of brass or similar conductive, resilient material and is shown with a crimped con-nection to plug lead 38. Sleeve 44 is aligned on plug axis 32 for reasons that will beeome apparent in the subsequent discus-sion regarding the mating contact element positioned in socket

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~ urther in accordance ~ith the present invention, a second wipin~ contact member is provided in the plug isolated from the first wiping contact member and extending radially outvar~ from ~he periphery of the plug housing. The second wiping contact member includes at least one planar wip;ng surface disposed par-allel to the housing axis and perpend;cular to the plug housing periphe~ry. As embodied herein, and with initial reference to Fi~ure ~, plug 22 includes "U~-shaped channel member 46 pos i-tioned transverse to plug housing axis 32 and extending through apertures g~a,b Eormed at diametrically opposed positions in housing 30, See Figure 7. Tab portion ~7 of U-shaped contact ~ ~ ' :~ :

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member 46 is electrica]ly conn~`cted to plug lead 40 by conven-tional means such as crimping or soldering. As best seen in Fig-ure 7 and Figures 15-17, the U-shaped wiping contact member ~6 can be economically formed rom a single piece of sheet metal, such as brass or other resilient material, and includes appropri-ate reliefs to permit captive assembly into housing ~0 if a "clamshell~ construction is utilized.
Importantly, U shaped wiping contact member 46 is sized to have a transverse length extending beyond the outer peripheral surface 50 of plug housing 30 such that portions 52 and 54 of the U-shaped~member extend outside of housing 30 in a "wingn-like configuration. As thus configured, U-shaped contact member 46 provides two pairs of planar wiping contact surfaces for engage-ment by a suitable mating contact element in socket component 24, to be discussed henceforth. Specifically, and as best seen in Figure I5, mernber portion 52 includes a first pair of mating con-tact surfaces 56a,b while mem~er portion 54 provides a second pair sf wiping contact surfaces 58a,b which would be disposed on the opposite side of housing 30 from wiping surface pair 56a,b.
Also, as best seen in Figure 2, U-shaped wiping contact member is disposed with the bottom of the U oriented in the direction of insertion to provide a "lead in" to the mating wiping contact el-ement of socket componen~ 24. ~lthough not shown in the draw-ings, th~ balance of the intern~l configuration of plug component ~l3-~3~

22 can include suitable structure for providin~ strain relief for plug leads 38, 40, as well as appropriate support structure to provide internal rigidity to housing 30.
It is also preferred that plug 22 include a shoulder 60 in hou~ing 30 to provide an engagement surface for resilient spring fingers 106, 10~ provided with socket component 24, which fin-gers, as will be discussed henceforth, act to restrain movement of plug 22 counter to the insertion direction whenever plug 22 has been inserted to a predetermined axial insertion depth. As best seen in Figure 7, housing 30 preferably has a pair of ~langes 62, 64 integrally formed with housing 30 at an axial lo-cation between the protruding portions 52, 54 of U-shaped member 46 and the gripping location 66 on pluq housing 30. Flange mem-bers 62, 64 are sized to ~shadow~ protruding U-shaped member por-tions 52, 54 to protect the user's hand during the insertion operation.
Further in accordance with the present invention, the socket component of the low-voltage, high direct current connector assembly includes a non-conductivc, generally cylindrical housing havi~g an axis and a plug-receiving axial end. As embodied here-in, and ~ith initial reference to Figures 1 and 2, socket compo-nent 24 in,_ludes cylindrical socket housing 70 having an axis 72 ar,d end 74 configured for receiving plug component 22. Socket housin~ 70 also can be m~de from an impact-resistant, moldable ~:
~ -14-~3~a~464 plastic material and can be made in two joinable halves in a ~clamshell" like construction.
Further in accordance with the present invention, the socket component includes a first wiping electrical contact element positioned within said housing, proximate the housing axis, at the housing axial end distant the plug-receiving end. As ern~odied herein and as best seen in Figure 2, plug 24 includes conductive pin 7~ having a cylindrical shape and aligned along socket housing axis 72 at housing axial end 78. Pin 76 is sized to provide an interference fit between outer cylindrical surface 80 of pin 76 and cylindrical surface ~5 of sleeve member 4~ when-ever plug component 22 is inser~ed into socket component 24 to the predetermined axial insertion location, as is depicted in Figure 5. Preferably, and as best seen in Figures 11 and 12, pin 76 can be formed from a single piece of sheet metal to provide integral base support 82 which can ~e captured with the ~clam-shell~ construction of socket housing 70 using techniques well-known to those skilled in the art. Also, a tab portion 8~
can be formed on Lhe same sheet metal piece extending from base portion 82 to prov;de a socket lead to connect pin 76 electri-cally to one terminel of an external power source ~not shown).
Further in accordance with the present invention, the socket component further incllldes a second wlping electrical contact el-ement electricallv iso.ated from ~ irst element and positioned ;~:

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~3~ 4 proximate the outer periphery of the housing at a preselected circumferential position. The second wiping contact element has at least one wiping contact surface oriented substantially per-pendicular to the housing outer periphery at the circumferential position. As embodied herein, and with initial reerence to Fig-ure 2, socket component 24 includes second contact element 85 having conductive, barrel shaped support member a6 positioned within the cylindrical housing 70 proximate plug-receiving end 74. Second contact 85 further includes two pairs of ears 88a,b and 90a,b (see Figure 6) integrally formed from, and extending substantially radially outward from, barrel portion 86 and posi-tionable in corresponding slots 92, 94 formed in housing 70. The inwardly facinq surfaces of opposing ears a8a,b and 90a,b provide the complementary mating wiping contact surfaces for engagement with surfaces 56a,b and 58a,b of U-shaped contact ~ember 46 carried by plug component 22. Specifically with reference to Figure 6, ears ~aa,b have corresponding planar mating surfaces 96a,b while ears 90a,b have mating surfaces 98a,b. When plug : component 22 is inserted into socket component 24 to the pre-scribed axial insertion location as depicted in Figure 5, the re-spective complementary mating surfOces of the contact elements associated with socket member 24 are seen to engage the corre-sponding surfaces in the contact members associated with plug ~ component 22. Thus, cylindrical surface 80 of pir. ?6 is seen to : ~ -16-: ~ :
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engage cylindrical surface 45 of sleeve 44 while planar mating surfaces 96a,b of ears ~a,b can be seen to enqage surfaces 58a,~
of pro~ruding portion 54 of U-shaped member 46.
The protruding portions 52, 54 of the U-shaped contact mem-ber 46 in plug 22 in conjunction with the slots 92, 94 in socket housing 70 also act to orient plug component 22 circumfe~entially with respect to socket component 24. Additionally, socket hous-ing 70 includes cylindrical extension 100 at housing end 74, which housinq extension includes a pair of "Vn-shaped notches 102, 104 (see Figures 2 and 6) for guiding protruding portions 52, 54 into engagement with ears 96a,b and 98a,b of contact ele-~ ment a 5.
; With initial reference to Figure 3, it is also preferred that socket component 24 include a pair of spring ~ingers 106, 108 resiliently mounted in socket housing 70. Spring fingers 106, 108 have radially inwardly depending portions 110, 112 which cooperate with shoulder 60 on plug component 22 to retain plug 22 n socket 24 at the predetermined axial insertion position as is shown in Figure 5. Housing axial extension 100 of socket compo-: nent 2~ can be enlarged to accommodate the radially outward ; flexing of spring fingers 106, 108 during the l.nsertion process.
Also, and wlth reference to Figures 13 and 14 of tlle drawing, sprinq~fingers 106, 108 can conveniently be integrally formed ; f:rom the~same sheet metal piece used to form barrel portion ~b, : : :
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136D41~64 and ears 96~,h and 98a,b where spring fingers 106, lO~ ~ould com-prise tab portions. Still further, and as best seen in Figure 14, a further tab portion 114 can be formed with contact element 85 and used as the second socket electrical lead, tab ~4 o~ pin 76 being the first socket electrical lead.
It is also highly preferred that the socket component of the low-voltage, high current connector assembly of the present invention be configured to optionally receive conventional low current automotive appliance plugs. These plugs, an exarnple of which is shown as 26 in dotted lines in Figures 1 and 2, typi-cally have an axially positioned, abuttabl~ contact mem~er such as spring loaded contact pin 1~0, shown positioned on low current plug axis 122, together with a spring contact member, such as a bent wire spring contact 124, located at the periphery of plug 26. For these embodiments of the socket component of the present invention, pin 76 specifically includes a closed pin face 12 sized and positioned for providing abutting engagement with abuttable contact member 120 upon insertion of low current plug : 26 into socket component 24. See Figure 4. Additionally, barLel portion 86 of second contact 85 which~is conductive and electri-cally connected to socket lead 114 is e~tended axially toward socket end ~8 a distance suf~icient to provide engagement with spring contact member 124 when plug 26 is inserted. Further, to insure compatibility with car appliances having plug connf:ctors :
, ~3~L4~4 like plugs 26, pin 76 prefer~bly has a positive polarity and sec-ond contact element 85 a negative polarity.
As stated previously, the low-voltage, high curr~nt con-nector assembly of the present invention is intended to be uti-li~ed in ~he "Mobile Po~er Tool and Appliance Operating System"
disclosed in co-pending application of Gierke et al. secause of the compatibility of the socket component of the connector assem-bly of the currently preferred embodiment of the present inven-tion with conventional low current plugs used with automotive appliances, there is the potential for inadvertent operation of the high current plug component 22 in a standard cigarette lighter socket in an automobile. ~ecause the fusing system of an automobile often is set for low current lighter operation (e.~., 6 amps), if a user attempts to operate a high current power tool or appliance from the car battery utilizing plug component 22 there is a possibility of blowing the fuse or possibly causing damage to the automobile's electrical wlring system.
Consequently, it is preferred that safeguard ~eans be in-cluded in the construction of plug component 22 for pre~entinq electrical connection to at least one of sleeve ~4 and U-shaped contact member 46 during inadvertent insertion of plug 22 into a conventional automotive cigarette~:lighter socket. With initial reference to Figure 10, conventional cigarette lighter socket (shovn in broken lînes) designated generally by the numeral 130 : :

, ~3~ 4 and shown mounted in a dashboard 132 includes an electrical con-tact face ].34 contactable ~ith end 152 of the cigarette lighter designated generally by the numeral 138. As embodied herein, a~d as shown in Figure 10, tapered pluq face 42 includes a cylindri-cal extension 140 defining port ~6 in which sleeve 4~ is mounted.
Importantly, sleeve g4 is pos;tioned recessed from tip 144 of ex-tension 1~0 a distance designated "d2" in Figure 10 sufficient to preclude contact between sleeve 44 and socket face 134 following inadvertent insertion of plug into cigarette socket 130.
It is also possible that a user may attempt to activate the plug portion of a conventional cigarette lighter by inserting it into socket component 24 of the present connector assembly inven-tion. Althoush socket component 2g is capable of handling the current load imposed by cigarette lighter plug 138 if electri-cally ac.ivated, the internal heat generated could damage socket component ~4, particularly non conductive housing 70. Therefore, it is ~lso preferred that socket component 24 include lockout means for preventing electrical connection to at least one of pin 76 and second contact ~S.
As embo~ied herci,l, and with initial reference to Fi~ure 8, socket component 2~ is provided with boss 148 ormed on the in-side periphery oE socket housing 70 surrounding pin 76. ~oss 148 is made of a non-concluctive material, preferably Eormed inte-grally with housing 70, and extends axially toward plug-receiving ~20-~^304~

end 74 a distance greater than the comparable axial extent o~ pin 76, ~he diffe~nce in axial extent b~ing designated by ~dl~ in Figure 8. Also, the inner diameter 150 of boss 14a is sized to be less than the outer diameter o~ axial face 152 of lighter plug 138 to preclude electrical contact between pin 76 and heating el-ement 146. For conventional cigarette lighter plugs having a flange element surrounding the plug, such as flange 154 sur-rounding plug 13a' (see Figure 9), the inwardly turned lip por-tion 156 of socket housing extension 100 is sized to have a mini-m~n inner diameter 158 less than the outer diameter of lighter plug flange 154. Moreover, the axial extent of housinq extension 100 is sized so that lip portion 156 is spaced from pin 76 a dis-tance ~reater than the distance between flange 154 and heating coil 146, thus precluding electrical contact between pin 76 and coil 146.
It will be apparen~ to those skilled in the art that variou.~
modifications and ~-~riati~ns can be made in the low-voltage, high current connector assembl~ of the present invention ~ithout departing ~rom the scope or spirit o~ the invention. Thus, it is intended tha~ the present ~.nvention cover the modifications and variation~ of this invention provid~2d they come within the scope of the appFnded claims and their equivalent~.

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Claims (22)

1. WHAT IS CLAIMED IS:
   l. A low-voltage, high direct current connector assembly, comprising:
   an elongated, hollow socket having an axis of elongation, a pair of socket leads, and a plug-receiving axial end;
   a plug receivable in said socket plug-receiving axial end upon insertion along said axis and having a pair of plug leads;
   means for retaining said plug in said socket at a predetermined axial insertion position;
   first wiping contact means for electrically connecting a respective one of said pair of socket leads to a respective one of said plug leads at said insertion position, said first wiping contact means including first mating contact surfaces positioned proximate said axis: and second wiping contact means electrically interconnecting the other of said pair of socket leads to the other of said pair of plug leads at said insertion position, said second wiping contact means including second mating contact surfaces positioned distant said axis; and wherein said second wiping contact means also comprises means for orienting said plug circumferentially with respect to said axis, and wherein said socket includes an axial socket extension having at least one axial slot with a circumferentially tapering width, said slot cooperating with said second wiping contact means for orienting said plug.
2. 2. The connector assembly as in Claim 1, wherein said second wiping contact means includes said plug having a conductive member protruding radially from said plug and said socket having a conductive element positioned on the periphery of said socket for receiving said radially protruding member during plug insertion to said insertion position, said second mating contact surfaces being located on respective opposing portions of said radially protruding member and said conductive element and being oriented substantially perpendicular to a tangent drawn to said housing outer periphery.
3. 3. The connector assembly as in Claim 1, wherein said retaining means includes a shoulder formed on said plug and at least one spring finger resiliently supported on said socket, said spring finger being engageable with said plug shoulder at said insertion position to restrain movement counter to the insertion direction.
4. 4. The connector assembly as in Claim 2, wherein said retaining means includes a shoulder formed on said plug and at least one spring finger integral with said conductive element and resiliently supported on said socket, said spring finger being engageable with said plug shoulder at said insertion position to restrain movement counter to the insertion direction.
5. 5. The connector assembly as in Claim 2, further including means for shielding a user's hand from said radially protruding member during insertion of said plug into said socket.
6. 6. A low-voltage, high direct current connector assembly, comprising:
   an elongated, hollow socket having an axis of elongation, a pair of socket leads, a plug-receiving axial end and another axial end;
   a plug receivable in said socket plug-receiving end upon insertion along said axis and having a pair of plug leads;
   means for retaining said plug in said socket at a predetermined axial insertion position;
   first wiping contact means for electrically connecting a respective one of said pair of socket leads to a respective one of said plug leads at said insertion position, said first wiping contact means including first making contact surfaces positioned proximate said axis; and second wiping contact means electrically interconnecting the other of said pair of socket leads to the other of said pair of plug leads at said insertion position, said second wiping contact means including second mating contact surfaces positioned distant said axis, wherein said second wiping contact means includes a pin-and-sleeve contact, and wherein said pin component is positioned within said socket at said other axial end and said sleeve component is attached to said plug in axial alignment with said pin component.
7. 7. A socket for a low-voltage, high direct current connector of the plug-and-socket type, comprising:
   a non-conductive, generally cylindrical housing having an outer periphery, an axis, a plug-receiving axial end and another axial end;
   a first wiping electrical contact element comprising a pin component of a pin-and-sleeve contact positioned within said housing at said other housing axial end proximate said axis:
   a second wiping electrical contact element electrically isolated from said first element and proximate said outer housing periphery at a preselected circumferential position, said second wiping contact element having at least one wiping contact surface parallel to said axis and substantially perpendicular to a tangent drawn to said housing outer periphery at said circumferential position;
   wherein said first and second wiping contact elements are configured for mating with complementary wiping contact members carried by a high current plug during plug insertion to a predetermined axial location; and wherein the socket is further configured to optionally receive conventional low current automotive appliance plugs of the type having a periphery, an insertable plug end, an axially positioned abuttable contact member at said insertable plug end and a spring contact member positioned at the low current plug periphery, said first wiping contact element including means for electrically connecting to the abuttable contact member, and said second wiping contact element including means for electrically connecting to the spring contact member when the end of the low current plug is inserted in the socket to a predetermined axial location.
8. 8. A socket for a low-voltage, high direct current connector of the plug-and-socket type, comprising:
   
   a non-conductive, generally cylindrical housing having an outer periphery, an axis, a plug-receiving axial end and another axial end;
   a first wiping electrical contact element positioned within said housing at said another housing axial end proximate said axis;
   a second wiping electrical contact element electrically isolated from said first element and proximate said outer housing periphery at a preselected circumferential position, said second wiping contact element having at least one wiping contact surface parallel to said axis and substantially perpendicular to a tangent drawn to said housing outer periphery at said circumferential position;
   wherein said first and second wiping contact elements are configured for mating with complementary wiping contact members carried by a high current plug during plug insertion to a predetermined axial location;
   wherein the socket is further configured to optionally receive conventional low current automotive appliance plugs of the type having a periphery, an insertable plug end, an axially positioned abuttable contact member at said insertable plug end and a spring contact member positioned at the low current plug periphery; said first wiping contact element including means for electrically connecting to the abuttable contact member, and said second wiping contact element including means for electrically connecting to the spring contact member when the end of the low current plug is inserted in the socket to a predetermined axial location; and wherein said first wiping contact element is a pin component of a pin-and-sleeve contact and wherein said abuttable contact connecting means includes a conductive pin end face sized and positioned for abutting engagement with the abuttable contact upon insertion of the low current plug.
9. 9. The socket is in Claim 8, the socket further including a socket lead electrically connected to said pin component, said lead comprising a tab extending from, and integral with, said pin component.
10. 10. The socket is in Claim 7, wherein said second wiping contact element includes a barrel portion positioned within said housing, said barrel portion having an inner peripheral surface, and wherein said spring contact connecting means includes said barrel inner peripheral surface being conductive and extending axially to the position of the spring contact member when the low current plug is at said predetermined insertion location.
11. 11. The socket as in Claim 7, wherein said second wiping contact element comprises a barrel portion positioned within said housing, having opposed integral ear portions extending substantially radially outward from said barrel portion parallel to said housing axis, and also having planar contact surfaces oriented substantially perpendicular to a tangent drawn to said housing periphery, wherein said socket further includes a socket lead comprising a tab extending from, and integral with, said barrel portion.
12. 12. The socket as in Claim 11 further including spring means configured and positioned for engaging recesses in the periphery of a plug for restraining the inserted plug against axial movement counter to the insertion direction, said spring means comprising a second tab integral with said barrel portion.
13. 13. The socket as in Claim 7, further including lockout means for preventing electrical connection to at least one of said first and second wiping contact elements upon insertion into the socket of a conventional automotive cigarette lighter plug of the kind having a generally cylindrical housing with an axially insertable end and an axial face, the plug also having a heating element coiled in said axial face of said insertable lighter plug housing end.
14. 14. The socket as in Claim 13, wherein said lockout means includes a boss formed on the inside periphery of said socket housing surrounding said first wiping contact element, said boss configured to have an inner diameter less than that of the insertable lighter plug housing end and extending axially toward said plug receiving end a distance greater than the comparable axial extent of said first wiping contact element for abuttably engaging said lighter plug axial face before said first wiping contact element can engage said face.
15. 15. The socket as in Claim 13, wherein the cigarette lighter plug is of the type having a flange extending radially outward of the lighter plug housing at an axial location spaced from the heating element, the socket further including a socket housing axial extension having a radially inwardly turned lip portion, the inner diameter of said lip portion being less than the outer diameter of the lighter plug flange, said socket housing axial extension being configured to space said lip portion from said first wiping contact element a distance greater than the spacing between the lighter plug flange and the heating element.
16. 16. The socket as in Claim 7, wherein said housing includes an axial extension having tapering slots cooperating with said second wiping contact element for guiding a plug complementary wiping member.
17. 17. A plug for a low-voltage, high direct current connector assembly of the plug-and-socket type, comprising:
    a generally cylindrical housing formed from a non-conductive material and having an axis and a housing axial end insertable in a socket;
    a first wiping contact member positioned at said insertable housing end;
    a second wiping contact member electrically isolated from said first member and extending transversely across said housing and radially outward from the periphery of said plug housing at opposed diametrical locations, said second member having at least two planar wiping surfaces each disposed parallel to said housing axis and substantially perpendicular to a respective tangent drawn to said plug housing periphery.
18. 18. A plug for a low-voltage, high direct current connector assembly of the plug-and-socket type, comprising:
    a generally cylindrical housing formed from a non-conductive material and having an axis and a housing axial end insertable in a socket;
    a first wiping contact member positioned at said insertable housing end;
    
    a second wiping contact member electrically isolated from said first member and extending radially outward from the periphery of said plug housing, said second member having at least one planar wiping surface disposed parallel to said housing axis and substantially perpendicular to a tangent drawn to said plug housing periphery; and wherein said second member is U-shaped and has a portion that protrudes radially outward of said plug housing at diametrically opposed locations, the bottom of said U-shaped member being proximate the housing inserting end, and the sides of the U-shaped member forming two pairs of planar wiping surfaces.
19. 19. The plug as in Claim 17, wherein said first wiping contact member is a sleeve component of a pin-and-sleeve contact.
20. 20. The plug as in Claim 17, further including safeguard means for preventing electrical connection to at lest one of said first and second wiping contact members upon inadvertent insertion of the plug into a conventional automotive cigarette lighter socket of the type having a contact face disposed in a plane axially spaced from a plug-receiving end and perpendicular to the direction of plug insertion.
21. 21. The plug as in Claim 20, wherein said safeguard means includes a non-conductive end wall connected to said plug housing at said insertable housing end, said end wall having a port, and said first wiping contact member being positioned in said port axially recessed from the outer surface of said non-conductive wall.
22. 22. The plug as in Claim 18, including a pair of flange members connected to said plug housing and positioned between a user's hand and said protruding portion of said second wiping contact member.