Note: Descriptions are shown in the official language in which they were submitted.
~lZ7!735
INTERLOCK OF BLADE AND HOUSING SIDE
The present invention relates-to an electrical
,
connector and more specifically~to a connector which
has;a so-cal}ed~"dead front" construction.
, ~ ~ Electrical connectors which have dead front con- ~-
struction have no exposed parts to which wires are
attached other than the electric blades which are to
receive power from a receptacle or the openings to the
~ contacts of a receptacle itself.
,;~ The concept of the use of a dead front type of
construction is that~lt increases the safety asuociated
~ with the use of connectors including both plugs for
-~ receiving electric power and receptacles for delivering
-~ electri:c power to plugs. In prior art devices there was
access to the screws to which~wires were connected through
the face of the plug having the power blades extending
therefrom. For many such prior art plugs there were
variou8 forms of covers that were to be placed over the
; face and to have the blades extending through the cover,
but these covers were not always employed by the users
of the plug so that when the cover was absent the screws
to which wires were attached were accessible from the face.
Further, any wire attached to the screws which became
loose or unravelled could extend out from the plug to
make contaat with a user or with a metal plate into
which the plug was inserted.
In recent times the standard making
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organizations, particularly the Underwriters Laboratories,
have studied this problem and have determined that
connectors, and particularly plugs, should have a dead
front construction. The mandating of the use of dead
front plugs by UL was subject of a standard and this
standard is now in force.
One patent which described a dead front plug
construction is the Hoffmann U.S. patent 4,010,999 dated
March 8, 1977. Such a construction was known piror to the
Hoffmann patent and was in fact shown and described in
British patent 676,144.
It is one object of the present invention to
provide a connector which is economical to manufacture
and which is reliable in use.
Another object is to provide a connector
having a clam shell type construction and having a
reinforcement between the blade and sides of the clam
shell.
A further object is to provide a connector
having a clam shell type construction with an interlock
between the blade and the folding sides of the clam shell
type structure.
Other objects and advantages of the invention
will be in part apparent and in part pointed out in the
description which follows.
The present invention concerns a dead front
connector as the term dead front is employed in this
art. The dead front connector has an outer housing in
the general form of a clam shell structure and has
electrical contacts mounted at least partially within
the structure. The contacts themselves are oversized in
at least some portion thereof and there are internal portions
of the clam shell like housing structure which are
adapted to receive the oversi2ed blade portions to form
an interlock between the blade and housing. The interlock
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between blade and housing prevents a separation of the
contacts from the portion of the housing constituting
the sides of the clam shell even in the event that the
sides are severed from the bottom of the clam shell.
The present invention will be better understood
by reference to the accompanying drawings in which:
Figure 1 is a perspective view of a plug and
power supply wire as provided pursuant to the present
invention.
Figure 2 is a perspective side view of the
housing of the plug of Figure 1 shown in an opened
position with power blades posed for entry into the
housing.
Figure 3 is a partial plan view of the exterior
of the housing of the plug of Figure 1 also shown in
an opened position.
Figure 4 is a sectional view taken along the
line Figure 4-4 of Figure 3.
Figure 5 is a sectional view taken along
the line Figure 5-5 of Figure 3.
Figure 6 is an end elevation of the insulating
housing of the plug as illustrated in Figure 1 in part
broken away and portraying the housing in a partially
opened position.
Figure 7 is an end elevational view similar
to that of Figure 6 with the housing shown in the closed
position and with the housing partially broken away to
show a portion of the interior thereof.
Figure 8 is a side elevational view of the plug
of Figure 1 with portions broken away to illustrate the
relationship of the parts therein.
Figure 9 is a perspective view of a power blade
as used pursuant to the present invention.
Figure 10 is a top plan view of the insulating
housing of the plug of Figure 1 showing the housing in
a fully opened position to view the interior thereof.
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With reference co che Figures structural details
and features of the present invention are pointed out.
In Figure 1 a plug as provided pursuant to the
present invention is illustrated in perspective view.
The plug 10 is provided with a power supply conductor 12.
The conductor has an outer insulation 14 covering two
inner wires 16 and 18, each of which is provided with
insulating sheaths 20 and 22. For essentially all con-
nectors of the present invention, provision is made for
receiving and retaining a conductor, such as 12, in the
mechanism of the connector and for making electrical
connection within the device between the conductors 16
and 18 and the electrical contacts of the device. In
the case of plug 10 the contacts have the external
power blades 24 and 26 which are connected respectively
with the conductors 16 and 18.
The insulating housing into which the blades 24
and 26 as well as the wire 12 enters is a plastlc
insulating housing made up of three portions, two of
which are side portions 30 and 32, and the other of
which is a base portion 34. The side and base portions
are connected by thin sections of the material which
serve as webs or hinges 36 and 38. The two side
portions 30 and 32 are held together by a screw
member, the head of which 40 is shown in place in side
30 of housing 10. The screw head 40 is shown in
phantom as 40', which with its shank 42', is poised
directly above the hole in housing 10 where screw
40 is positioned to close sides 30 and 32 of the housing
10.
Referring next to Figure 2, the insulating
housing 11 of plug 10 is shown in an opened position
with a perspective view of the interior thereof, and
with che power blades 24 and 26 of the contacts 60 and 62
shown poised for insertion into receiving openings in
the base 34 of the housing 11. The side portions 30 and
112'~735
32 of the housing ll are made up of cord re~training
portions 44 and 46 near the point where the cord
enters housing ll and contact retaining portions 48 and
50 adjacent to the respective cord retaining portions.
The base 34 is also adjacent to the contact retaining
portions 48 and 50.
This base 34 receives. the two contacts 60
and 62 as the blades 24 and 26 respectively are inserted
through the base to occupy the position illustrated in
Figure l.
The base 34 is illustrated from the bottom
in Figure 3 with the webs 36 and 38 extending QUt from
the base 34 to portions of the side structures 30
and 32. The blade ports 52 and 54 are the ports
through which the blades 24 and 26 are inserted
during assembly of the connector 10. The two latch
wells 56 and 58 adjacent to the blade ports 52 and 54
respectively receive and hold a latch element to hold
the blades in place once they are inserted. The
portion of the housing illustrated in Figure 3 is
shown in section in Figures 4 and 5.
The Figure 4 is a transverse sectional view
taken along the lines 4-4 of Figure 3 and showing the
base 34 in vertical section. Figure 5 is a longitudinal
sectional view taken along the line 5-5 of Figure 3
and showing the base 34 and adjoining portions in
section.
It will be noted particularly from contact 60
of Figure 2 that a latch is formed by stamping the
tab 64 out of a portion of contact 60 which portion
is immediately above the elongated blade portion 24.
The blade 24 is inserted through the blade port 52
in the manner illustrated in Figure 2 and as is evident
from Figure 4 such insertion will bring the tab 64
into the latch well 56 after the tab has been compressed
and squeezed by the well wall 66.
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As is also evident from Figure 4, the base 34
is also provided with internal wells 70 and 72. The
contact 62 has an offset arm 74 which holds the bladed
end 76 of the contact 62. The offset arm 74 extends
from the main axis of the contact 62 by a cross arm
78. The cross arm 78 seats within the internal well
70 on the platform 80 at the bottom of well 70.
The offset arm 74 may rest against the internal side
wall 82 of well 70. Similarly, the contact 60 is
situated in the port 54, latchwell 58 and internal
well 72 of base 34 in essentially a mirror image
fashion to the situation of contact 60 in the base
34. It is evident from consideration of the configuration
of the contacts 60 and 62 as well as the internal
and external wells of the body 34 that when the contact
is inserted in place in the base, the blade will
extend out of the base for its normal purpose of
insertion into a receptacle. Accordingly the contact
itself will be precisely located within and held within
the base 34 in a position which cannot be easily
altered independently of whether or not a wire has
been assembled to the device and whether or not the
device has been assembled as illustrated in Figure 1.
For example, the tendency of the blade to be forced
out of the base 34 as the blades are inserted into
a receptacle is resisted by the tab 64 pressing against
the upper wall of the well 56 and 58. Conversely
where the tension is applied to the outwardly extending
blade portions 24 and 26 the blade cannot be moved out
of its place in the base 34 due to the cross arm 78
of the contact abutting against the platform 80 at
the bottom of the internal well 70 of base 34.
The firm securing of the blade in the base is
accomplished prior to any assembly of the sides of the
housing 11. Accordin~ly,the combination of the con-
figuration of the contacts. taken together with the
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configuration of the base 34 provides a result which
permits the connector to be assembled and contact to
be made with conductors positioned therein with great
ease of manufacture and assèmbly and with great
reliability of operation and performance. The illustration
of the contacts fully assembled into the base 34 iæ
given in Figure 10 which is a top plan view of the
fully opened connector with the contacts pressed into
place and held firmly in place in the base 34 of the
connector.
Turning now to Figure 6, there is illustrated
a side elevational view in part broken away and in section
of a fold up housing 11 being folded in clam shell
fashion to close the two sides of the housing 30 and
32 together above the base 34. The folding action takes
place based on the high flexibility of the web or hinge
portions 36 and 38.
In Figure 7 the side elevational view of the
folded connector and blade combination of the present
invention, in part broken away, is illustrated with
the power blades in place. In this illustration the
blade 26 extends downward from the base 34 of the closed
housing 10. Once the housing is closed the blade is
anchored in place extending from housing 10 by the
upper tab 108.
It will be noted accordingly that a very
important aspect of the present device is the provision
of means by which a wiring device may operate in the
opened condition, and prior to the assembly or full
assembly of the device into the final closed condition
as illustrated in Figure 1.
In Figure 2 the contacts 60 and 62 are illus-
trated in their position poised for entry into the
base 34. Once the contacts are inserted in place they
are firmly retained as part of the base and independent
of the support and assistance of the two side portions 30
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and 32 of the clam shell-like structure of the housing 11
of the connector. Accordingly, while the sides 30 and
32 of the clam shell do lend substantial assistance and
support to the contacts, the base is able to operate and
the combination of the housing 11 and the contacts
60 and 62 serve as a functioning unit for attachment
of a wire such as 12 thereto in a manner to be
described below. However, as furnished to the public,
the unit comprises the insulating body 11 with the
contacts 60 and 62 mounted therein and with an assembly
screw 40 provided for the assembly of the unit to a
wire. The unit is self-sufficient in carrying with it
all of its essential ingredients and in enabling the
potential user to take advantage of the novel features
thereof without any equipment beyond a conventional
screwdriver which is employed conventionally in the
assembly of most such structures.
- Pursuant to the present invention, an inter-
lock is provided between the contacts employed within
the structure and the inner side walls of the structure.
By inner side walls is meant the side wall portion
visible in Figures 2, 8 and 10 in particular, and to a
more limited degree in the other Figures. For example,
in Figure 7 the mode of interlock is evident through
the broken away portion of the lower part of the housing
of the connector shown therein.
With regard to the interlock, this interlock
is accomplished principally between the upper or inner
ends 90 and 92 respectively of the contacts 60 and 62
as illustrated in Figure 2, for example. More specifi-
cally,the interlock occurs between the edges 88 and 94
of upper end 90 and conforming slots in the portions 48
and 50 of the housing 11 and between the edges 96 and 98
of the upper end 92 and other conforming slots in the
portions 48 and 50 of the housing 11. Still more
specifically, the edge 94 interlocks with slot 100 and
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41WD-3180
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edge 88 interlocks with slot 102. Similarly, edge 98
interlocks with slot 104 end edge 96 interlocks with
slot 106.
The actual slots are provided with a ramp
surface on one side as best seen perhaps in Figure 7.
Thus the slot 100 has ramp surface 108 and slot 102 has
ramp surface 110. These ramp surfaces permit the
easy entry of the edges 94 and'88 of the upper end 90
of the contact element'60.
It is noteworthy that the structure of the
present invention is one which permits a rapid, easy,
automatic interIocking between the contacts mounted
within the connector and the side walls of the connector.
In this regard, the specially provided transverse
portion at the upper ends of the contacts are adapted
for entry in a transverse fashion into the set of slots
provided specifically therefor in the sides of the housing.
Accordingly, if the webs 36 and 38,,which are formed
inte;grally with the housing as the housing itself is
formed, are slit or otherwise separated to permit
the side portions 30 and 32 to be separated from the base
portion 34, the assembled connector will not suffer any
separation of portions thereof inasmuch as the blades
through their upper portions 90 and 92 provide an
effective interlock with the slots 100, 102, 104 and
106. A longitudinal pull exerted either on the blades
24 and 26, or on the wire 12, of Figure 1, will not
result in a separation of the base 34 from the sides
30 and 32 due at least in part to the strong interlock
formed between the ends of the contacts as set
forth above and the slots into which they are automatically
positioned as the connector is assembled. This
assembly of the sides 30 and 32 of the connector up
and about the ends 90 and 92 of the blades is accom-
plished as is indicated above as the sides 30 and32 are folded up in clam shell fashion above the base 34
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to enclose the contents of the connector 10 including
the exposed portions of the wire and the inner ends of
the blade from contact with the hands of the user or
with instruments or tools which the user may be employing
S in working with the connector. Accordingly, the
present invention provides a very effective means of
accomplishing an interlocking of portions of the
structure, and particularly a lateral interlocking of
portions of the sides of the housing with upper or
inner portions of the contacts.
