Note: Descriptions are shown in the official language in which they were submitted.
~3~4~
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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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
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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
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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
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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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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
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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
2~.
~ 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
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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
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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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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
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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
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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
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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-
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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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