3-prong electrical connector

The disclosure is directed to a 3-prong grounded electrical connector which has a flexible and resilient grounding prong. The resilient grounding prong helps to maintain the connector in mating engagement with an electrical receptacle when the connector is laterally disturbed.

FIELD OF THE INVENTION 
The invention relates generally to a grounded electrical connector. More 
specifically, the invention relates to a 3-prong grounded electrical 
connector having a translationally elastic and resilient grounding prong 
which aids in retaining the connector within an electrical receptacle. 
DESCRIPTION OF THE PRIOR ART 
The vast majority of modern electrical tools now include an internal 
grounding circuit which establishes a ground contact for the device via a 
third grounding cable contained within the electrical cord. This ground 
contact, in its most familiar form, is the cylindrical grounding prong 
seen in conventional 3-prong grounded electrical plugs. This ground 
circuit greatly increases the safety of the device by grounding the 
electrical motor and frame of the electrical device directly to the 
electricity outlet and attached structure. This greatly reduces the chance 
that the operator himself will serve as a ground contact and thereby be 
electrocuted in the event of a short circuit. 
Nevertheless, the National Safety Council annually records several hundred 
electrical shock incidents caused by non-grounded electrical power tools 
and other appliances. Many of these incidents result in fatalities. While 
a portion of these incidents were due to appliances which were designed 
and built without a grounding circuit, others were caused by appliances 
which contained a grounding circuit, but in which the grounding circuit 
was compromised. As a consequence, the Occupational Safety and Health 
Administration (OSHA) requires that all electrical devices used in a 
commercial setting include a functional grounding circuit. Hefty fines are 
levied against individuals and companies who are found to be in violation 
of this administrative regulation. 
However, in many industrial settings, most notably the residential and 
commercial construction industry, a common problem is encountered with the 
standard 3-prong electrical plug. As is currently standard practice, a 
conventional 3-prong grounded electrical plug includes two electrical 
leads: a "hot" lead and a "neutral" lead. These two leads are in the shape 
of planar blades which are disposed in corresponding parallel planes. A 
third lead, referred to herein as the "grounding prong," or simply "the 
ground," is conventionally in the form of a rigid cylindrical member. 
Problems arise when the 3-prong plug is displaced laterally when matingly 
engaged in a conventional 3-prong grounded electrical receptacle. When 
this happens, the hot and neutral leads are sufficiently flexible that 
they will normally bend within the receptacle, thereby maintaining the 
electrical connection to the appliance being powered. But, because the 
grounding prong is a rigid cylinder, this rough treatment more often than 
not results in the grounding prong being broken away from the plug body. 
This is an extremely dangerous situation because, while the tool will 
still function, the tool is no longer grounded. This greatly increases the 
chances that the tool operator will be accidentally electrocuted. 
In such instances, the above-noted OSHA regulations require that the 
now-ungrounded plug be removed and a new plug installed. This, however, is 
very time consuming. Rather than halting work while the power cord is 
replaced or repaired, the standard, albeit unspoken, practice is to bend 
the hot and neutral electrical leads back into their original position and 
insert the plug back into the receptacle minus the grounding prong. While 
the tool is now ungrounded, it remains fully functional. The damaged plug, 
or the entire power cord, is then replaced at the end of the work day. 
While the above practice is clearly unsafe (as well as subject to heavy 
fines by federal and state regulatory agencies), it is regularly seen in 
the industry as being more cost-effective than to halt production in order 
to fix a damaged plug. Consequently, there is a strongly felt need within 
the home and industrial electrical appliance market for a grounded 3-prong 
connector which can be laterally displaced while disposed in an electrical 
receptacle, without damaging the grounding circuit of the connector. Such 
a connector would increase the safety of electrical equipment and decrease 
the number fines assessed against commercial operators of such equipment 
for the use of ungrounded tools. 
It must be noted, however, that such a connector must satisfy certain 
criteria in order to be acceptable to the relevant purchasing public. For 
instance, a standard electrical receptacle includes inward-acting leaf 
springs which both establish electrical contact with a plug inserted 
therein and which help to maintain the plug within the receptacle. Several 
prior art electrical plugs, described below, include outward-acting spring 
devices which establish a more secure frictional engagement of the plug 
within the receptacle. These devices, however, suffer from the decided 
drawback that the outward-acting forces strain the inward-acting leaf 
springs of the electrical receptacle. Consequently, over time, the ability 
of the electrical receptacle to establish a sure electrical contact with a 
standard plug is eroded. After repeated use, the receptacle will no longer 
securely engage a standard 2- or 3-prong plug due to the loss of spring 
action in the receptacle itself. When this occurs, the receptacle itself 
must be replaced. 
Additionally, for safety purposes, an electrical plug should not lockingly 
engage the receptacle. This is dangerous because in the event that the 
plug must be quickly disconnected, there is the possibility that the plug 
will become permanently lodged within the receptacle. Should a situation 
arise where the electricity must be quickly disconnected, precious time 
may be wasted attempting to disengage a plug locked into a receptacle. 
This increases the risk of serious or fatal electrocution. 
Several different types of electrical plugs, both of the locking variety 
and the non-locking variety, are described in the patent literature. For 
example, U.S. Pat. No. 3,013,242, to Terlinde describes a 2- or 3-prong 
electrical plug in which the entire body of the plug is resilient. The two 
blades of the plug (i.e., the hot lead and the neutral lead) are set into 
a roughly V-shaped body at diverging angles. To insert the plug into a 
receptacle, the plug body is compressed, thereby forcing the blades into 
corresponding parallel planes. The plug is then inserted into the 
receptacle and released. The natural resiliency of the plug body then 
forces the blades to frictionally engage the inner walls of the 
receptacle. The outward force of the plug body thereby "locks" the plug 
into the receptacle. 
As noted above, however, this outward force will have a detrimental effect 
on the ability of the receptacle to matingly engage standard 3-prong 
plugs. Over time, the outward force of the plug body will erode the inward 
force of the electrical contacts within the receptacle. Consequently, the 
use of such a plug is not recommended because it will result in increased 
wear of the electrical receptacle. 
Another locking 3-prong plug is described by Imhoff in U.S. Pat. No. 
4,544,216. Here, a telescoping locking member is disposed within a U- or 
V-shaped grounding prong. The locking member is biased to slide 
telescopingly within the trough defined by the grounding prong. When the 
plug is inserted, the locking member is pushed through the grounding prong 
so that it extends from the end of the grounding prong and frictionally 
engages the inner wall of the electrical receptacle. A spring-biased 
mechanism maintains the locking member in tight frictional engagement with 
the receptacle. Unfortunately, as noted above, this device presents an 
increased danger of serious or fatal electrocution in the event that the 
electric current must be quickly disconnected. 
Torok, U.S. Pat. No. 5,108,301, describes another type of locking 
electrical cord connector which includes both male and female electrical 
contacts. In the same fashion as a standard electrical receptacle, the 
female contacts of the Torok device have inward-oriented leaf spring 
members which frictionally engage a male contact inserted therein. In 
complementary fashion, the male portion of the Torok device has 
outward-oriented leaf spring members which aid in frictionally engaging a 
standard 2- or 3-prong electrical receptacle. As noted above, the outward 
force of the leaf spring members of the Torok device will cause increased 
wear on the inward-oriented leaf spring contacts of a standard electrical 
receptacle. This force will adversely impact the ability of the receptacle 
to matingly engage with a standard electrical plug. 
Several other types of electrical plugs are also described in the prior 
art. McDaniel, U.S. Pat. Nos. 3,786,392 and 3,890,030, describes a 3-prong 
plug in which the grounding prong is a solid member which is mounted upon 
a telescoping spring embedded within the plug body. When the plug is 
inserted into a standard 3-prong receptacle, the spring is sufficiently 
stiff to force the grounding prong into the receptacle. The resiliency of 
the spring, however, allows the prong also to be inserted into a 2-prong 
receptacle. In this case, the spring allows the grounding prong to 
telescope into the body of the plug. It must be noted, however, that if 
the McDaniel plug is laterally displaced while inserted into an electrical 
receptacle, the grounding prong will be damaged in the same fashion as a 
conventional 3-prong electrical plug. 
U.S. Pat. No. 2,049,560 to Ezzo describes a 2-prong ungrounded plug in 
which the electrical leads are "corrugated" blades. The blades are not, 
however, resilient or spring-like. And, as noted above, the increased 
friction caused by the corrugated blades will result in a premature aging 
of the electrical receptacle into which this type of plug is inserted. 
Garrett, U.S. Pat. No. 3,858,956, describes a 3-prong electrical plug in 
which the grounding prong is a longitudinally segmented cylindrical member 
having a number of raised radial ridges along its length. The longitudinal 
slits define a plurality of "somewhat" flexible segments which impart some 
"give" to the grounding prong. However, these segments are not resilient 
and will readily deform if laterally displaced. The raised radial ridges 
function to increase the frictional engagement of the plug within a 
receptacle. 
None of the above references, taken alone or in any combination, describe 
the 3-prong electrical connector disclosed and claimed herein. 
SUMMARY OF THE INVENTION 
It is a principal aim and object of the present invention to provide a 
3-prong grounded electrical connector which operationally maintains a 
grounding prong within an electrical receptacle even when the connector is 
laterally displaced within the electrical receptacle. 
It is a further aim of the present invention to provide a 3-prong 
electrical connector in which the grounding prong is a resilient and 
elastic member. 
Yet another aim of the present invention is to provide a 3-prong grounded 
electrical connector in which the grounding prong is a coil spring which 
is sufficiently stiff to maintain electrical contact with the grounding 
circuit of an electrical receptacle, yet sufficiently flexible and 
resilient to allow lateral and translational displacement of the 
electrical connector without damaging the grounding plug. 
A still further aim of the present invention is to provide a 3-prong 
grounded electrical connector which decreases the likelihood of electric 
shock to the user of an electrical appliance by including a resilient and 
flexible grounding prong which maintains electrical contact with an 
electrical receptacle even when laterally displaced. 
Yet a further aim of the present invention is to provide a 3-prong 
electrical plug adaptor which allows a conventional 3-prong electrical 
plug to be converted into a 3-prong electrical connector of the present 
invention having a flexible and resilient grounding prong. 
In light of the above discussion, the present invention is drawn to a 
3-prong grounded electrical connector which comprises a body of 
electrically-insulated material and a first electrically-conductive lead 
secured in the body and extending therefrom, the first lead dimensioned 
and configured to operationally engage a hot conductor of a 3-conductor 
electrical cord. The connector further includes a second 
electrically-conductive lead secured in the body and extending therefrom, 
the second lead dimensioned and configured to operationally engage a 
neutral conductor of the 3-conductor cord; and an electrically-conductive 
grounding prong secured in the body and extending therefrom, the grounding 
prong dimensioned and configured to operationally engage a ground 
conductor of the 3-conductor cord, and further wherein the grounding prong 
is a translationally elastic and resilient member. 
The present invention is also directed to a 3-prong grounded electrical 
connector comprising: a body of electrically-insulated material; a female 
electric contact disposed within the body; a male electric contact 
disposed within the body, the male electric contact comprising a first 
electrically-conductive lead secured in the body and extending therefrom: 
a second electrically-conductive lead secured in the body and extending 
therefrom; and an electrically-conductive grounding prong secured in the 
body and extending therefrom, and further wherein said grounding prong is 
a translationally elastic and resilient member; and means for electrically 
connecting the male electric contact to the female electric contact. 
The present invention is further drawn to a 3-prong grounded electrical 
connector in combination with a 3-conductor electrical cord, the connector 
comprising: a body of electrically-insulated material; a first and a 
second electrically-conductive lead, the first and second leads secured in 
the body and extending therefrom, the first and second leads electrically 
connected at a point within said body to a hot conductor and a neutral 
conductor of the 3-conductor electrical cord, respectively; and an 
electrically-conductive grounding prong secured in the body and extending 
therefrom, the grounding prong electrically connected at a point within 
the body to a third conductor of the 3-conductor electrical cord which is 
to be grounded, wherein the grounding prong is a translationally elastic 
and resilient member. 
These and other aims, objects, and advantages of the present invention will 
become clear upon a complete reading of the Detailed Description and 
attached claims, below.

DETAILED DESCRIPTION OF THE INVENTION 
Identical reference numerals are used throughout the drawing figures to 
indicate identical or similar features of the claimed electrical 
connector. 
Referring now to FIG. 1, which is a perspective view of a 3-prong grounded 
electrical connector according to the present invention, the connector 
includes a body of electrically-insulated material 10. The body 10 can be 
fabricated from any type of insulated material, such as rubber, 
polyurethane, polyvinyl chloride, or any number of other well known 
thermosetting or thermoplastic materials. So long as the body material 
will shield an operator from electric shock, the material is not critical 
to the operation of the electrical connector. 
Securely fastened or embedded within the body 10 is a first 
electrically-conductive lead 12 and a second electrically-conductive lead 
14 which extend from the body 10. As shown in FIG. 2, which is a front 
elevational, partially cut-away view of the connector shown in FIG. 1, 
both the first lead 12 (hidden from view in FIG. 2) and the second lead 14 
are dimensioned and configured to operationally engage a hot conductor and 
a neutral conductor of 3-conductor cord 22 by means for conducting 
electricity 24. Such means for conducting electricity include conductive 
wires, clips, fasteners, and the like. Such means for conducting 
electricity can be either fixed or releasible. 
The 3-conductor cord 22 shown in the figures is a conventional cord for 
conducting electricity to an electrically powered apparatus which includes 
a "hot" conductor, and "neutral" conductor, and a ground circuit. Such 
cords are conventional and well known in the art. 
An electrically-conductive grounding prong 16 is also securely fastened or 
embedded in body 10 and extends therefrom. Also as shown in FIG. 2, the 
grounding prong 10 is dimensioned and configured to operationally engage a 
ground conductor of the 3-conductor cord 22 by means for conducting 
electricity 24. Of particular note in the present invention is that the 
grounding prong 16 is a translationally elastic and resilient member. 
As shown throughout the drawing figures, the grounding prong 16 is 
preferably a cylindrical coil spring. The grounding prong 16 is 
sufficiently stiff so that when it is inserted into an electrical 
receptacle, it will function in the same fashion as a prior art, 
inflexible, monolithic grounding prong. However, when the body 10 is 
laterally or translationally strained when disposed within an electrical 
receptacle, the grounding prong 16 will reversibly deform to maintain 
contact with a grounding contact of the electrical circuit. Such resilient 
deformation of the grounding prong 16 is shown in FIG. 3. 
While depicted throughout the figures as a coil spring, the grounding prong 
of the present invention can be any suitably flexible and resilient 
electrically-conductive material in any shape, dimension, or 
configuration. As used herein, the term "resilient" has its standard, 
accepted denotation, i.e. the capability of a strained body to recover its 
size and shape after deformation. (Webster's Ninth Collegiate Dictionary, 
Merriam-Webster, Inc., Springfield, Mass.) For instance, the grounding 
prong 16 may comprise several segmented members joined by one or more 
flexible, resilient, and electrically-conductive joints. Or, the grounding 
prong 16 may comprise a unitary, monolithic member of a suitably 
electrically-conductive, flexible, and resilient polymeric material. 
The first and second leads and grounding prong of the present invention may 
be fabricated from any suitable electrical conductor. Such conductors 
preferably are metals such as silver, copy, iron, nickel, aluminum, alloys 
of the same, and the like. 
In a preferred embodiment of the present invention, the first lead 12 and 
the second lead 14, where they extend from the body 10, are elongated 
planar members having flat surfaces. As shown throughout the figures, the 
preferred embodiment of the present invention has the flat surfaces of the 
first lead 12 and the flat surfaces of the second lead 14 oriented in 
corresponding parallel planes. This is best illustrated by the 
superimposition of the first and second leads in the front elevational 
views of FIGS. 2 and 4. 
It is also preferred that the grounding prong 16, where it extends from the 
body 10, is disposed in a plane equidistant from and non-collinear with 
the corresponding parallel planes defined by the first and second leads. 
This is best shown in FIG. 1. It is still more preferable that the first 
lead 12, the second lead 14, and the grounding prong 16, where they extend 
from the body 10, are dimensioned and configured to matingly and 
releasibly engage a conventional 110 Volt, 3-slot grounded electrical 
receptacle such as those used throughout the United States of America. As 
is now becoming standard practice in the United States, the first lead and 
the second lead may be polarized. Here, one of the leads is made slightly 
larger than the other to ensure that the connector can be inserted into a 
receptacle in only one orientation. 
As shown in FIG. 1, the connector body 10 of the present invention and the 
3-conductor electrical cord 22 to which it is attached are oriented in a 
roughly straight 180 degree fashion. The electrical connector of the 
present invention may also be combined with a 3-conductor electrical cord 
in a roughly 90 degree joint 34 as shown in FIG. 4. In all other respects, 
the embodiments depicted in FIGS. 1 and 4 are identical. 
As shown in FIGS. 1 through 4, the electrical connector of the present 
invention is operationally connected to a conventional 3-conductor 
electrical cord 22. However, the present invention may also take the form 
of an electrical connector which functions as an adapter to convert a 
conventional 3-prong electrical connector into a connector according to 
the present invention. In this embodiment, the invention comprises a 
female electric contact disposed within a body which is electrically 
connected to a male electrical contact extending from the body and having 
a flexible and resilient grounding prong. 
Referring now to FIG. 5, this second embodiment of the present invention 
includes a 3-prong grounded electrical connector comprising a body of 
electrically-insulated material 10 which has a female electric contact 
disposed within the body. As shown in FIG. 5, the female electric contact 
comprises a first planar slot 26, and second planar slot 28, and a 
cylindrical slot 30. A preferred embodiment, depicted in FIG. 5, has the 
female electrical contact dimensioned and configured to receive a pair of 
electrical leads and a grounding prong of a cooperating male connector 32 
of another electrical appliance. 
The embodiment shown in FIG. 5 also includes a male electric contact 
disposed within the body, the male electric contact comprising a first 
electrically-conductive lead 12, a second electrically-conductive lead 14, 
and an electrically-conductive grounding prong 16 securely fastened or 
imbedded in the body 10 and extending therefrom. The first lead 12 and the 
second lead 14 are the same as described above. Also as described above, 
the grounding prong 16 is a translationally elastic and resilient member, 
depicted in FIG. 5 as a coil spring. 
The first planar slot 26, second planar slot 28, and a cylindrical slot 30 
of the female electrical contact are operationally connected to the first 
electrically-conductive lead 12, the second electrically-conductive lead 
14, and the electrically-conductive grounding prong 16, respectively, of 
the male electrical contact via means for conducting electricity 24 as 
shown in FIG. 2. 
The most preferred mode of the second embodiment is where the first planar 
slot 26, and the second planar slot 28, and the cylindrical slot 30, 
respectively, are dimensioned and configured to receive a pair of 
electrical leads and a grounding prong of the conventional 110 V, 3-prong 
male connector 32 used throughout the United States. In analogous fashion, 
it is preferred that the first lead 12, the second lead 14, and the 
grounding prong 16, where they extend from the body 10, as shown in FIG. 
5, are dimensioned and configured to matingly and releasibly engage the 
conventional 110 Volt, 3-slot grounded electrical receptacle used 
throughout the United States. 
The present invention is not limited to the embodiments explicitly 
described above, but includes all such modifications, extensions, and 
variations thereof which fall within the scope of the attached claims.