Protected electrical connector

A spring mounts a protective cover on an electrical outlet connector body for non-sliding, swinging movement along an arcuate path between a plug-blocking position, in which the cover blocks slots formed in the connector body, and a plug-passing position, in which openings in the cover are aligned with the connector slots. The spring includes an anchored portion securely mounted on the connector and a movable cantilever portion which is inclined relative to the anchored portion, and which is dimensioned so as to maintain the cover out of frictional engagement with the connector body between the aforementioned positions. Manual displacement of the cover is facilitated by the reduction of frictional drag.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to electrical outlets having a 
guard against electrical shock and burn and, more particularly, to a cube 
tap having protective plates mounted thereon. 
2. Description of the Prior Art 
It has long been recognized that electrical outlets present a substantial 
hazard to children. Children are by nature curious and this curiosity 
leads them to insert metallic objects into prong-admitting passageways 
which lead to female contacts housed in a connector. Seeing their parents 
insert objects into electrical outlets and imitating them, children insert 
what they believe to be similar objects without realizing the dangers 
involved. As a result, they are shocked or burned, sometimes seriously 
and, upon occasion, fatally. 
The increading concern for child safety has led to a safety requirement for 
cube taps of electrical cords. The requirement is that all, or all but 
one, of the pairs of prong-receiving slots of the cube taps be shielded or 
protected in some manner. 
A number of devices have been devised for satisfying this requirement 
including pseudo-plugs of electrically non-conductive material which are 
plugged into the outlet in a manner analogous to that shown in U.S. Pat. 
No. 3,989,334. 
Other approaches utilize a protective cover plate which is moved between a 
plug-blocking and a plug-receiving position by a spring. U.S. Pat. Nos. 
4,094,569; 3,865,456; 3,068,442; 3,222,631; 2,820,842; 2,710,382; 
2,477,803 are representative of constructions which utilize separate coil 
or leaf springs to slide a cover plate between the aforementioned 
positions. 
Due to the fact that the constructions with separate springs utilize a 
multitude of parts and require great skill to assemble such connectors, it 
has been proposed in U.S. Pat. No. 3,810,070 to slide a protective cover 
plate directly against the elastomeric connector body itself. However, 
this construction is not entirely satisfactory in situations where the 
elastomeric material hardens due to age or due to cold temperatures. In 
such cases, the hard elastomeric body becomes so stiff due to the cold 
temperatures, that the user must exert a great amount of force to push the 
plate relative to the body. Another construction which eliminates separate 
springs is disclosed in U.S. Pat. No. 3,980,371. This patent teaches a 
slidable cover plate which has a one-piece spring mounted in a cavity of a 
connector body. Although generally satisfactory for its intended purpose, 
this cover has not proven to be altogether reliable in operation. First of 
all, the sliding movement of the cover generates a high degree of 
frictional drag, thereby generating a large magnitude force at the point 
of interconnection of the spring with the cover. This interconnection 
becomes progressively more stressed during repeated operation and 
eventually the interconnection is broken. Secondly, the spring has a very 
thin tip which engages a smaller flange in the cavity. It has been found 
that the spring does not remain in the cavity because it is not 
effectively restrained therein, since the tip slips off the flange by the 
force generated during the aforementioned sliding movement. Finally, the 
cover is not reliably registered in its end-limiting positions relative to 
the connector body. 
SUMMARY OF THE INVENTION 
1. Objects of the Invention 
Accordingly, it is the general object of the present invention to overcome 
the aforementioned drawbacks of the prior art. 
Another object of the present invention is to eliminate frictional drag 
during the movement of the protective cover between its positions. 
Another object of the present invention is to effectively anchor a spring 
relative to a connector body. 
Still another object of the present invention is to move a cover plate in a 
non-sliding, swinging-type motion. 
Another object of the present invention is to provide a protected 
electrical connector which has a long working lifetime. 
It is an object of the invention to provide a terminal connector of the 
character described which constitutes relatively few and simple parts and 
readily lends itself to mass production and easy, rapid assembly. 
Another object of the invention is to provide a terminal connector of the 
character described which has an attractive appearance and which has a 
safety guard that, despite its ease of manipulation, still presents a 
sufficiently difficult problem, to provide an effective safety device for 
children. 
Another object of the invention is to provide a terminal connector of the 
character described which utilizes a safety guard that, although easily 
assemblable to the terminal, is, when once installed, only removable with 
difficulty so that, in effect, it becomes a permanent part of the 
terminal. 
Still another object of the present invention is to provide a terminal 
connector of the character described which incorporates a suitable 
arrangement for cooperating with polarized, i.e. different width prongs. 
2. Features of the Invention 
In keeping with these objects and others which will become apparent 
hereinafter, one feature of the invention resides, briefly stated, in an 
improved electrical outlet connector for connection with at least two 
electrical conductors. The outlet connector is of the type which includes 
a connector body which has electrically-insulating wall portions defining 
a wall surface, and which bounds at least one pair of open-ended slots 
spaced apart of each other, each slot being elongated in direction 
generally normally of the wall surface for receiving the prongs of an 
electrical plug. The connector body also includes at least one pair of 
electrical contacts in electrical connection with the two electrical 
conductors, each contact being located in a respective slot and being 
slidably engageable with a respective prong when the latter is inserted 
into the respective slot. The connector body further includes a protective 
cover which overlies the wall surface of the body and which has a pair of 
prong-receiving openings extending through the cover. 
In accordance with the present invention, the improvement is embodied in 
anti-friction means for mounting the cover on the body for non-sliding, 
swinging movement along an arcuate path and about a swing axis which 
extends normally of the elongation of the slots between an end-limiting 
prong-blocking position, in which the cover engages the connector body and 
blocks the slots, and an end-limiting prong-passing position, in which the 
openings on the cover register with the slots and expose the open ends of 
the latter for insertion of the prongs therethrough. This improved 
anti-friction means constitutes a resilient spring in force-transmitting 
engagement with the cover, and is operative for swinging the cover out of 
frictional engagement with the connector body during the swinging 
movement. The resilient spring is dimensioned to maintain the cover out of 
frictional engagement with the connector body during the swinging movement 
along the arcuate path between the above-mentioned positions. Thus, 
frictional drag is eliminated during the swinging movement thereby 
facilitating manual displacement of the cover. 
In accordance with this invention, the non-sliding movement of the cover 
along an arcuate path effectively obviates the generation of any large 
frictional force, as is common with prior art constructions which employ 
sliding covers which rub against the connector bodies. The cover of the 
present invention is easier to manipulate and does not stick against the 
connector bodies during use. Moreover, the spring of the present invention 
is not subjected to counter-forces which tend to snap the spring from the 
cover thereby destroying the entire utility of the connector. 
Furthermore, this invention provides positive end-limiting stops to 
reliably register the prong-receiving openings of the cover with the 
prong-receiving slots of the body in one end-limiting position, as well as 
properly orienting the cover relative to the body in the other 
end-limiting position. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1 of the drawings, the electrical outlet connector 10 
is a terminal connector, i.e. a cube tap, for an electrical extension cord 
12. The particular cube tap illustrated has three sets of parallel 
prong-receiving slots. These are illustrated as two pairs of 
prong-receiving slots 14a, 14b, 16a, 16b on the top face of the cube tap 
as shown in FIG. 1, and as a third pair of slots 18a, 18b on the opposite 
bottom face of the tap as shown in FIG. 5. 
Top slot pairs 14a, 14b and 16a, 16b are polarized. Slots 14a, 16a are 
wider than their associated slots 14b, 16b. A non-illustrated polarized 
electrical plug having male-type prongs of different widths can therefore 
be properly inserted in the top slot pairs. Of course, the top slot pairs 
need not be polarized and can have the same width as exemplified by the 
bottom slot pair 18a, 18b. 
It will be expressly understood that any number of slot pairs can be 
provided on either the top and/or the bottom and/or side walls of the cube 
tap without departing from the spirit of this invention. If desired, each 
slot pair can be provided with a third slot for reception of a ground 
prong of a three-wire, three-prong grounded plug. Although this invention 
will be described in connection with a cube tap, it is to be expressly 
understood that this invention is not intended to be so limited, but also 
includes electrical convenience wall outlets and any other electrical 
device having female-type sockets in electrical connection to at least two 
wire conductors, and to which access is to be respectively barred and 
permitted, as required. 
The cube tap 10 comprises a connector body 20 of a molded plastic 
construction. The plastic body 20 has a predetermined hardness, preferably 
polyvinyl chloride having a Shore durometer characteristic in the vicinity 
of 40-70 is employed. The electrically insulating walls of the body 20 
form a generally rectangular parallelepiped configuration having a top 
wall surface 22, a bottom wall surface 24 and side walls 26, 28. Top slot 
pairs 14a, 14b, 16a, 16b, extend from their open ends at the top surface 
22 towards the lower surface 24 but terminate short thereof. Bottom slot 
pair 18a, 18b extends from its open ends at the bottom surface 24 towards 
the top surface 22, but terminates short thereof. All of the slots are in 
mutual parallelism and are each elongated generally normally of the 
respective top and bottom walls. 
As shown in FIG. 4, a pair of parallel conductor strips 30, 32 are embedded 
within body 20. Each strip has a plurality of pairs of metal contact 
portions arranged lengthwise of the respective strip. Each pair of metal 
contact portions is located in a respective slot and bounds a 
prong-receiving slit which is aligned with each prong-receiving slot. 
Thus, representative metal contact parts 34a, 34b, are located in slot 16a 
and are spaced apart of each other to define a prong-receiving slit 34' 
which is aligned with slot 16a. Upon insertion of a prong of an electrical 
plug into slot 16a, this prong slidably and frictionally engages the metal 
contact portions 34a, 34b and establishes an electro-mechanical connection 
therewith. The same structural and functional relationships are present 
for the metal contact parts 36, 38 of the strip 30 and for the metal 
contact parts 40, 42, 44 of the strip 32. The extension cord 12 has two 
conductors 12a and 12b which are electrically connected to the strips 30, 
32 in conventional manner such as by soldering or mechanical crimping on 
the inboard ends of the conductors. 
The top wall 22 is grooved to form two wide and generally parallel grooves 
to function as guideways 46, 48 of the generally planar protective cover 
plates 50, 52. Upstanding end guides 60, 62 at opposite ends of the body, 
and central guide 64 located midway between the end guides all serve to 
guide the protective covers 50, 52 along their respective guideways 46, 48 
in a manner to be described below, as well as serving to prevent the 
covers from rotating about an axis which extends parallel to the 
elongation of the slots. 
Covers 50, 52 have respective pairs of openings 54a, 54b, 56a, 56b which 
extend through the cover and which overlie the top wall 22 of the body. 
Each pair of cover openings is spaced apart of each other at the same 
distance as the prong-receiving slots formed in the body in order to 
receive the electrical plug prongs. Openings 54a, 56a are slightly wider 
than their associated openings 54b, 56b in order to accommodate polarized 
prongs. 
The cover 50 at the right side of FIG. 1 is in its normal position and 
shows the cover openings offset from the body slots, i.e. in a 
plug-blocking position, so as to safeguard a child from injury. The cover 
52 at the left side of FIG. 1 is in the displaced position and shows the 
cover openings in registration with the body slots, i.e. in a plug-passing 
position. The present invention is concerned with effecting this movement 
between these positions in a novel manner as described below. 
Before turning to a description of this unique movement, the body 20 is 
further formed with semi-circular bosses 66, 68 at opposite ends thereof. 
The bosses serve as abutments for the ground prong of a three-wire 
three-prong connector. This prevents a user from interchanging two-and 
three-prong cord connectors. If desired, the width of the cover itself can 
be increased so that the ground prong is effectively barred from being 
connected to the cube tap. 
The prong-receiving slots 18a, 18b have not been provided with an overlying 
cover. If desired, a cover can be provided which overlies the bottom wall 
of the cube tap. 
Turning now more particularly to FIG. 3, anti-friction means 70 are 
provided for mounting each protective cover on the body for non-sliding, 
swinging movement along an arcuate path in direction of the arrow A, and 
about a swing axis P--P, which extends normally of the elongation of the 
slots. The anti-friction means 70 constitute a resilient spring for each 
cover, and the spring is in force-transmitting engagement with, and 
preferably is of one-piece with, each cover. As will be shown herein, a 
spring 70 is operative for swinging each cover out of frictional 
engagement with the body and for maintaining each cover out of frictional 
engagement with the body during the swinging movement between the two 
aforementioned end-limiting positions of the cover. This feature 
eliminates frictional drag during the swinging movement and facilitates 
manual displacement of the cover during use. 
Each spring 70 comprises an anchored portion which consists of a mounting 
portion 72, and an enlarged portion 76 at the end of the spring that is 
most remote from the cover. Each spring also comprises a cantilever 
portion 74 which is movable relative to the anchored portion and which is 
pivotable about the point P' which lies on the swing axis P--P. 
For each spring, the body 20 is formed with a corresponding cavity 80 in 
which the cantilever portion 74 is received with clearance so as to 
accommodate the cantilever portion during its entire range of movement. 
The body is also formed with a pair of mounting holes 82 in which the 
respective mounting portions 72 are frictionally received. Each mounting 
hole 82 and each mounting portion 72 is preferably of non-circular 
configuration, i.e. rectangular, as shown. Of course, other complementary 
cross sections such as circular, hexagonal, etc., could also be employed. 
The cantilever portion 74 is also preferably of rectangular configuration, 
but other configurations such as circular and other non-circular 
configurations can be used. The body is also formed with a bore 84 having 
a base wall 86 and in which the enlarged portion 76 is received. The 
enlarged section 76 may have a generally rectangular parallelepiped 
configuration, as shown, or a generally conical configuration or any other 
three-dimensional configuration. The enlarged portion 76 forms a shoulder 
with the mounting portion 72, and this shoulder engages base wall 86 to 
thereby prevent undesired axial withdrawal of the enlarged portion from 
the bore. Concomitantly, this engagement of the enlarged section and the 
base wall anchors the spring 70 in proper position on the body. In the 
embodiment shown, the shoulder has a rectangular face, whereas for 
conically-shaped enlarged sections, the shoulder would have an annular 
face. Of course, other differently configurated abutment faces can be 
utilized. 
Each cover and its associated spring is of one-piece molded plastic having 
a hardness which is harder than said predetermined hardness of the body. 
Preferably, a hard polycarbonate or nylon material, having a Shore 
durometer characteristic of about 100, is employed. In order to assemble 
the combined spring and cover unit on the body, enlarged portion 76 is 
passed first through the cavity 80, and thereupon through mounting hole 
82, wherein the walls bounding the hole 82 are deformed and pushed 
radially aside due to the relatively larger-sized cross-sectional 
dimension of the enlarged section and also due to the different hardness 
of the spring relative to the connector body material. 
Finally, the enlarged portion snaps into the space in the bore 84. The 
walls bounding the mounting hole 82 resume their initial position in tight 
frictional engagement with the mounting portion 72 after the enlarged 
portion 76 has cleared the mounting hole 82. 
In FIG. 3, the spring is shown in its non-working end-limiting position. 
The cover has a stop flange 90 which extends downwardly from the planar 
cover. The stop 90 is preferably located at a distance away from the 
spring 70 such that the stop 90 abuts against the abutment surface 92 of 
the notch 94 under the influence of a force which tends to constantly urge 
the stop 90 with an affirmative frictional engagement against the abutment 
surface 92. In a preferred embodiment, the spring 70 is so molded of 
resilient plastic that the cantilever portion is inclined at a large 
obtuse angle relative to the mounting portion 72. In this case, the spring 
normally assumes the solid line, illustrated, slightly stressed position, 
thereby always biasing the cover to the illustrated offset or 
prong-blocking position. In this end-limiting position, the lower surface 
of the cover either engages, or is spaced slightly from, the body at a top 
wall portion 22, and the stop 90 is affirmatively and constantly urged 
against abutment surface 92. 
The purpose of the stop flange 90 is to reliably insure that the outer 
surface 96 of the stop 90 is substantially flush or in a desired 
orientation relative to the outer side surface 98 of the body 28. We have 
found that manufacturing tolerances in the curing and fabrication of the 
plastic molded spring are such that the flange 90 may in certain instances 
overhang or improperly register with the body, thereby imparting an 
unattractive cosmetic appearance to the overall connector. Therefore, by 
molding the cantilever portion 74 at an obtuse angle slightly greater than 
that illustrated, the finally cured and molded cover and spring 
sub-assembly will always be constantly urged in a direction towards the 
right in FIG. 3. The stop 90 thus will not improperly register with the 
body and will always be located in a predetermined orientation, thereby 
providing uniformity of appearance which is especially important in mass 
production and when more than one cover is used on a single connector. 
The cantilever portion of the spring shown in FIG. 3 is in the slightly 
stressed state as described above. Of course, the cantilever portion could 
also be molded so as to be normally unstressed or in a relaxed state. The 
important criterion for the relaxed cantilever portion is that the 
prong-receiving slots are blocked by the cover. 
In use, the cover is manually displaced and the cantilever portion (which 
is either slightly stressed or completely relaxed) is moved from its 
initial inclined position to a final position in which the cantilever 
portion is approximately co-planar with the mounting portion. Preferably, 
the cantilever portion 74 passes through the plane in which the mounting 
portion 72 lies and defines an obtuse angle relative to the other side of 
the mounting portion 72. In this final position, as shown in phantom 
lines, the cantilever portion is in a highly stressed state, i.e. is more 
highly stressed as compared to its initial non-working position. The 
cantilever portion, therefore, always exerts a restoring torque in which 
the cantilever portion seeks to return to its less stressed state. 
Additionally, the softer resilient material of the connector body may also 
be slightly displaced and stressed during the displacement of the cover. 
Thus, the material of the body itself may also generate a restoring torque 
and assist the cantilever portion in moving the cover back to its initial 
position. 
During this movement, the cantilever portion pivots or swings about the 
pivot point P' along the arcuate path A. As it moves from its inclined to 
its more aligned orientation relative to the mounting portion 72, the 
cover is lifted in direction both slightly upwardly away from the top wall 
portion 22 and also circumferentially of the pivot point P'. The cover 
never frictionally engages the connector body during this swinging 
movement between the aforementioned plug-blocking and plug-passing 
positions because the length of the cantilever portion, and the pivoting 
of the latter about pivot point P', insures that the cover is always 
spaced above the body during this swinging movement. As noted above, this 
lack of friction permits a user to more easily displace the cover, as 
compared to prior art constructions. Moreover, no great stress forces are 
generated at the interconnection between the cantilever portion and the 
cover to thereby cause the spring to snap off the cover during repetitive 
use. 
In order to facilitate registration of the cover openings with the body 
slots, movement of the cover may be stopped at the prong-passing position 
by engagement of the cover, or by engagement of the cantilever portion, 
with a portion of the connector body. The stop serves to insure that the 
cover openings align with the body slots. 
Displacement of the cover is facilitated by hand-gripping means 100 on a 
cover end region which overhangs the body. Hand-gripping means 100 
constitutes a roughened surface such as the sequence of notches formed at 
the edge of covers 50, 52. Other hand-gripping means, such as a single 
indentation which can accomodate a finger, may also be utilized. In 
addition, indicia such as "PRESS" and/or the representation of an arrow on 
the top surface of the covers serve as aids to indicate to a user which 
way the cover is to be pushed. 
It is also within the spirit of this invention to mold the cover and spring 
sub-assembly such that the cantilever portion is not inclined relative to 
its mounting portion, i.e. such that the cantilever portion is at a right 
angle relative to the plane of the cover. In this case, the cantilever 
portion will be displaced from an initial, upright, prong-blocking 
position to a final inclined prong-passing position. During the 
displacement of the cantilever portion, the body will yield to the force 
applied to the cover due to the much softer resilient material of the body 
as compared to the cover. In this case, the body material itself is 
displaced and stressed so that the tensed body will cooperate with the 
stressed cantilever portion to return the latter to its initial position. 
It will be understood that each of the elements described above, or two or 
more together, may also fine a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
protected electrical outlet, it is not intended to be limited to the 
details shown, since various modifications and structural changes may be 
made without departing in any way from the spirit of the present 
invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention and, 
therefore, such adaptations should and are intended to be comprehended 
within the meaning and range of equivalence of the following claims.