U.S. patent number 3,596,019 [Application Number 04/855,577] was granted by the patent office on 1971-07-27 for safety plug and outlet.
Invention is credited to Henry W. Koester.
United States Patent |
3,596,019 |
Koester |
July 27, 1971 |
SAFETY PLUG AND OUTLET
Abstract
Disclosed herein is a safety plug and outlet which may be
readily interchanged for a standard electrical outlet and which has
a unique safety arrangement whereby it is practically impossible
for a person employing the device of this invention to get an
electrical shock when inserting the plug of an appliance or other
equipment into the outlet. The device contemplates the use of a
depressor in the plug which operates a switch in the positive line
to the outlet so that no current flows to the positive contact
blades of the outlet until the plug is practically completely
inserted in the socket. By this arrangement, it is practically
impossible for one to touch a prong of the plug which could be
partially inserted in the socket and thus receive an electrical
shock. The switch in the positive line may operate through the use
of a snap-acting spring so that the connection in the switch is
positively and securely made or else is biased open so that the
switch will not flicker between an off and on position. The
invention further contemplates an adapter which may be inserted
into the standard junction box of an ordinary wall outlet so that
the device of the present invention may be used without any
significant structural changes in any area where its use may be
desired.
Inventors: |
Koester; Henry W. (Cos Cob,
CT) |
Family
ID: |
25321606 |
Appl.
No.: |
04/855,577 |
Filed: |
September 5, 1969 |
Current U.S.
Class: |
200/51.09;
439/188 |
Current CPC
Class: |
H01R
13/7036 (20130101); H01R 13/453 (20130101) |
Current International
Class: |
H01R
13/70 (20060101); H01R 13/703 (20060101); H01R
13/44 (20060101); H01R 13/453 (20060101); H01v
033/30 () |
Field of
Search: |
;200/51.07--.09 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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167,931 |
|
Aug 1959 |
|
SW |
|
607,126 |
|
Jul 1960 |
|
IT |
|
Primary Examiner: Smith, Jr.; David
Claims
What I claim is:
1. A safety electrical outlet device for use with a plug having
first and second spaced electrically conductive prongs and a
depressor prong centrally disposed between said first and second
prongs, said device including
a socket having first and second prong receiving openings spaced
therein to receive said first and second prongs of said plug and a
third depressor receiving opening centrally disposed between said
first and second openings to receive said depressor prong of said
plug when said first and second prongs of said plug are inserted in
said first and second openings; and
an adapter attached to said socket, said adapter including first
contact blades aligned with said first opening in said socket to
receive said first prong of said plug, second contact blades
aligned with said second opening in said socket to receive said
second prong of said plug, an elongated, nonconducting peg having a
first end slidable in said third opening in said socket and a
second end, a first terminal connected with said first contact
blades and adapted to be connected with a source of electricity, a
second terminal adapted to be connected with said source of
electricity, and snap-acting switch means aligned with said third
opening in said socket and selectively connecting said second
terminal with said second contact blades,
said snap-acting switch means including a stationary contact
connected with said second contact blades, a switch arm connected
with said second terminal and carrying a movable contact, and a
spring blade affixed to said switch arm and having a normal
position and an operative position, said movable contact being
placed in electrical contact with said stationary contact when said
spring blade is in said operative position, said movable contact
being spaced from said stationary contact when said spring blade is
in said normal position, and said second end of said peg
operatively engaging said snap-acting switch means such that said
peg is forced against said snap-acting switch means to place said
spring blade in said operative position when said depressor prong
of said plug is inserted completely in said third opening in said
socket whereby electricity from said source is supplied to said
second contact blades.
2. The device as recited in claim 1 wherein said second end of said
peg engages said switch arm to force said switch blade to said
operative position.
3. The device as recited in claim 1 wherein said plug includes a
prong adapter having first and second spaced slots therein to
receive first and second prongs and carrying said depressor prong
at a central position between said first and second slots.
Description
This invention relates to electrical connectors and particularly to
electrical connectors including a socket and plug with safety
provisions for preventing the user thereof from getting an
electrical shock when the plug is inserted into the socket.
Electrical connectors in the form of plug and sockets having safety
features represent a highly developed art. However, there is a
continuing effort on the part of industry and individuals to
produce a safety plug of greater efficiency and one which is more
economical to produce. The present invention is a product of such
continuing effort and represents an improvement over prior art
devices in its simplicity of design and ease of manufacture.
The device of the present invention assures that its user cannot
receive an electrical shock while connecting the plug of an
appliance to an electrical outlet and is particularly advantageous
in applications where children are present and by their curious
nature likely to attempt to use the plug. In these applications,
children may often insert the plug in the socket only partially and
thus leave an exposed prong of the plug which is connected to a
live power source and thereafter contact such a live prong with
some type of a cylindrical or slender instrument such as a
screwdriver, toy or any other device which is susceptible to
insertion in a narrow opening. If such a device is electrically
conductive, the child could receive a severe shock, resulting in
sometimes fatal injury.
With this situation in mind, I have devised a safety plug and
outlet which avoids the possibility of a live prong of an
electrical plug being exposed and which device may be readily
interchanged into a standard home outlet or may be supplied as
original structure in a home or other building where children are
likely to attempt use of such devices.
The advantages of my safety plug and outlet over prior art devices
are numerous. The device may be readily interchanged with standard
wall outlets and adapters for standard plugs can be easily
provided. The device is easily constructed and can be manufactured
in great quantities at significant cost savings over other safety
connectors. Construction of the device does not require any highly
specialized or complicated components and most of the components of
the device are available in the present market. The switch member
in the positive power source of the socket is preferably controlled
by a snap-acting spring so that there is no chance of sparking or
shorting and the power supplied through the plug will not flicker
or cut on and off in response to any jarring or other vibration
that might be imposed upon the plug.
From this brief description of some of its advantages, it will be
recognized that the invention has as its primary object the
provision of a simple and efficient safety plug and socket.
Another object of this invention is to provide a safety plug and
outlet that can be readily interchanged for a standard plug and
outlet with a minimum amount of time and effort.
Still a further object of this invention is to provide a safety
plug and outlet including a depressor element carried by the plug
which operates a switch in the positive line power source to
control the power passed to the positive contact blades.
Yet a further object of this invention is to provide a safety plug
and outlet as above described wherein the switching mechanism
includes a snap-acting spring so that the current is switched
either full on or full off.
Still a further object of this invention is to provide a safety
plug and outlet wherein no power will be supplied to the prongs of
the plug until the plug is in the outlet to the extent that the
prong is protected by the face of the plug.
These and other objects of the invention will become apparent to
those of ordinary skill in the related art, when consideration is
given to the following detailed description of a preferred
embodiment, which is set forth as exemplary only, which description
is given in conjunction with the accompanying drawings wherein:
FIG. 1 illustrates an exploded perspective of a device manufactured
according to the present invention;
FIG. 2 illustrates in perspective the switch carried in the
positive power line by the adapter of t present invention;
FIG. 3 illustrates partially in cross section an assembled device
manufactured according to the present invention;
FIG. 4 is a cross section taken along line 44 of FIG. 3 and
illustrates an assembled device constructed according to the
present invention;
FIG. 5 is an exploded perspective of a standard plug and the false
bottom adapter which may be provided in connection with the present
invention; and
FIG. 6 illustrates in cross section a modified mounting arrangement
in connection for the adapter and socket of the invention.
Referring now to FIG. 1, the plug 1, socket 2 and adapter 3 are
shown in exploded relationship. The plug 1 may be a standard
appliance plug connected through the cord 4 to any electrical
appliance (not shown). The plug includes prongs 5 and has been
modified with respect to a standard plug to include a depressor 6
which is provided for a purpose which will become apparent
hereinafter.
The socket 2 is substantially a standard unit and includes the
prong openings 7 and dog ears 8 having slots 9 through which screws
10 pass for connecting the socket to the adapter. The socket 2 is
normally constructed of a plastic material which is nonconductive
to electricity and a standard socket is modified to the extent that
in the center of each plug face between the prong openings 7 is
provided depressor opening 11.
The depressor openings extend completely through the socket and
provide a channel for carrying the pegs 12 which are positioned in
the channels for slidable movement axially of the opening.
The adapter 3 includes the contact blades for the prongs of the
plug 1 which extend into hollowed portions of the socket 2.
Switches 13 are recessed in pockets 14 of the adapter and are
connected between the positive power source and the positive
contact blades 15.
The positive contact blades 15 and the negative contact blades 16
are separated from the switch 13 by an insulator 17. The connection
between the positive blades 15 and the contact 18 (FIG. 2) of the
switch 13 is illustrated schematically by the line 19.
A stop 20 is provided on the adapter to position the switch arm 21
of the switch when the switch is in its open position as
illustrated in FIG. 3. The adapter also includes channels 22 which
are provided to receive the screws 10 for connecting the socket to
the adapter. Tabs 23 having openings 24 are also provided on the
extremity of the adapter for connecting the adapter to a standard
junction box.
The insulator 17 has a hole 25 through which passes the peg 12 for
depressing the switch arm 21. As is apparent, the depressor 6 and
peg 12 could be a continuous unit passing through the depressor
opening 11 and the hole 25 to depress the switch on 21. However,
the arrangement illustrated in FIG. 1 is preferable since the use
of a recessed depressor prevents the depressor from becoming bent
or broken through use.
Referring to FIG. 3, the switch preferred for use in the present
invention is illustrated. The switch includes a switch arm 21 which
has an over center, snap-acting spring 30 integral therewith. The
switch arm is connected to a bracket 31 as shown in FIG. 2 by a
rivet or like structure 32 and the bracket includes a lip 33
beneath which the spring 30 is caught. Contact 18 on member 34 is
provided for passing current when the connection is made with
contact 35 on the underside of the switch arm 21. The member 34 is
connected to the positive contact blades 15 through the line 19
illustrated schematically in FIG. 1 so that when the peg 12
depresses on the point 36 of the switch arm, the contact 35 is
sprung into engagement with the contact 18 and the power input is
thus connected to the positive contact blades.
By providing a snap-type spring 30 in the switch 13, when a slight
amount of pressure is applied to the point 36, the connection
between contacts 35 and 18 is assured through the bias of the
spring. When the peg is removed so that no pressure is applied to
the point 36, the spring 30 operates in the opposite or up
direction so that the switch arm 21 is biased into contact with the
stop 20. By this arrangement the connection between contacts 35 and
18 will not flutter or flip from off to on and so forth since the
slight amount of pressure applied by the peg 36 is amplified
through the spring and switch arm to ensure the connection between
the contacts.
Referring now to FIGS. 3 and 4, the device of the present invention
in assembled relation is illustrated. A wall junction box 40 is
shown mounted on a wall joist 41, by screws, nails, etc., 42. In
substituting the device of the present invention for a standard
wall socket, the positive line source is connected at point 43
which is secured in the conductor 44 for passing current to the
switch 13. There is a separate switch for each of the two outlets.
The body structure of the adapter 3 is of insulation material to
keep the socket from shorting out.
The negative line is connected to the negative contact blades 16 as
at 45. Once the positive and negative lines have been connected to
the adapter, the adapter may be mounted in the junction box by
screws 46 passing through the tabs 23 and connected to the flange
47. As can be seen from FIGS. 3 and 4, the contact 18 of the member
34 is connected as at 50 to the positive contact blades 15.
Once the adapter 3 is mounted in the junction box 40, the socket 2
having the peg 12 within the channel 51, is connected to the
adapter. The socket may be connected through the dog ears 8 with a
screw 10 passing through the slot 9 and threaded into the
internally threaded channel 22. When the socket 2 is mounted on the
adapter 3, the insulator 17 is positioned between the contact
blades and the switch 13 to assure that the contact blades are
insulated from the power source connected to the switch. A plate 53
may then be mounted over the socket by a screw 54 and the device is
ready for insertion of the plug 1. If the plug 1 is provided with a
depressor 6, the depressor will force the peg 12 axially downward
and cause same to apply pressure on the point 36 and make
connection between the contacts 35 and 18. The snap-acting spring
30 will amplify the pressure applied to the peg 12 and bias the
contact 35 against the contact 18. As the plug 1 is removed, the
depressor no longer applies force to the peg 12 and the force of
the spring 30 will operate in the up direction to open the switch
and break the power supply to the positive contact blades 15. The
dimensions of the peg and depressor can of course be regulated so
that the depressor will operate the switch by force on the peg only
when the plug is substantially flush with the face of the socket.
The upward movement of the switch arm 21 is limited by the stop 20
which is insulated to prevent the device from shorting out.
If a standard plug is to be employed with the device of the present
invention, an adapter in the form of a false bottom as is
illustrated in FIG. 5 is necessary. The false bottom includes a
plate 60 having slots 61 and a depressor 6. The false bottom or
plate is slid over the prongs 5 of the plug 1, with the prongs
passing through the slots 61 so that a standard plug is easily
adapted for use with the device of this invention.
An alternative arrangement for the mounting of the device of the
present invention is illustrated in FIG. 6. In this arrangement,
the tab 23 is offset upwardly from the adapter so that it may be
connected to the flange 47 along with the dog ear 8 of the socket.
Since the flange of a standard junction box is usually provided at
the mouth of the box as opposed to recessed within the box as
illustrated in FIG. 3, a conversion unit will preferably have the
mounting structure illustrated in FIG. 6.
As it is apparent, the device described as a preferred embodiment
is exemplary only and various modifications will become apparent to
those skilled in the art. For example, the switch 13 could be any
of a standard variety including a pivoted lever depressing a
contact member in response to pressure of the peg 12 on the lever.
The units 2 and 3 may also be of a one-piece construction. Further,
the invention is readily adaptable for use in conjunction with
three-pronged plugs, it being merely necessary to realign the
components of the adapter in order to receive the peg and depressor
provided on the plug.
The present invention can be adjusted to provide any degree of
safety that is desired and the plate 53 may be constructed such
that it would be practically impossible for any object to be
inserted between the plug and the socket while the switch 13 is
actuated to supply power to the positive contact blades. Further, a
child would not receive a shock merely by inserting a conductive
instrument within the opening leading to the positive contact
blades since no power is supplied to the contact blades until the
peg 12 has been depressed to actuate the switch. In order to
receive a shock from the safety plug of this device, one would have
to insert some type of an instrument in the depressor openings 11
and while holding the depressor in a compressed position, at the
same time insert some type of an instrument into the positive
contact blade openings. When the plug of the device is used to
connect an electrical appliance, the dimensions of the depressor 6
and peg 12 are such that the plug must be substantially flush with
the face of the socket before any power is supplied to the positive
contact blades from which one could receive a shock by touching the
positive prong 5. However, when the depressor is sufficiently
inserted into the socket to depress the switch and cause power to
pass to the positive contact blades, the plug is so close to the
face of the socket that it is substantially impossible, without
extreme effort and agility, to contact the prongs since the body of
the plug fits over the face of the socket and may be recessed
therein if desired.
The preferred embodiment of the invention has been described in
detail and several modifications have been discussed. However, it
is to be understood that the preferred embodiment is exemplary only
and is not intended to limit the range of equivalents that are
within the scope of the invention as defined by the terms of the
appended claims. Further, the alternatives and modifications of the
device of the invention as discussed herein previously are by no
means exhaustive of the modifications that will become apparent to
those of ordinary skill in the art and which will be equivalent of
the express terms of the appended claims.
* * * * *