Security coupling

An electrical apparatus for securing a connection between an electrical plug and an electrical socket formed by a hollow elastically expandable and rolled tube which is rubber-like and has a longitudinal axis extending to opposed ends with an elastically rolled ring at each end for securing the tube to the plug and socket.

BACKGROUND OF THE INVENTION 
This invention relates to the secure coupling of devices, and more 
particularly, to the secure coupling of electrical plugs to mating 
sockets. 
The coupling of an electrical plug of one electrical line to a mating 
socket of another electrical line ordinarily is accomplished by inserting 
conductors of one line,that extend from the plug, into socket recesses 
containing internal conductors of the other line, so that the conductors 
of the plug are mated to those of the socket. Unfortunately, since the 
plug conductors are easily inserted into socket recesses, they are easily 
detached, for example by someone who accidentally comes into contact with 
coupled lines or trips on them. 
In addition, it is important to avoid having the coupling come into contact 
with contaminants, such as moisture, which can interfere with the 
coupling, or in the case of an electrical coupling, cause a short-circuit. 
One form of "Protective Enclosure for Electrical Plug Connection" is the 
flexible sheath disclosed by L. W. Nelson in U.S. Pat. No. 4,869,683, 
which issued Sep. 26, 1989. The sheath in Nelson has two separated 
longitudinal edges. These edges are interengageable by a zipper to form a 
tubular sheath with limiting straps at the tubular extremities of the 
sheath. The limiting straps apply compressive force to underlying sealing 
bands which grip electrical cords beyond the position of plug connection. 
The Nelson device has the evident disadvantage of requiring a zipper to 
form the protective sheath. To overcome this disadvantage, M. J. Shotey in 
U.S. Pat. No. 5,147,216 issued Sep. 15, 1992, discloses a "Shroud for 
In-line Electrical Plug". Shotey's shroud or sheath encircles an in-line 
electrical connector and has opposed ends that are closed about the lines 
that extend from the connector. Prior to the connection, the shroud or 
sheath is positioned on one of the lines. After the connection, the shroud 
is moved over the mid-point and the ends of the shroud are bunched or 
crimped over the lines. Straps are then wrapped about the ends. 
Unfortunately if the straps become accidentally disengaged, either by 
inadvertent contact or as a result of strap wear, the shroud no longer 
affords any protection to the line connection. In particular the presence 
and requirement of straps for completing the closure increases the chances 
of accidental disengagement. In addition when the closure straps become 
frayed, they can be pulled away, leaving the sheath without a facility for 
closure. 
Accordingly, it is an object of the invention to enhance the security that 
can be afforded to the coupling of two devices, such as an electrical plug 
and mating socket. A related object is to eliminate the need for the 
straps that are required in both the Nelson and Shotey protectors of the 
prior art. 
Another object of the invention is to enhance the protection that can be 
afforded against contaminants, such as moisture and dust, as well as 
inadvertent contact with conductors. 
Still another object is to enhance the range of plug and receptacle sizes 
that can be accommodated by a coupling protector. 
A further object of the invention is to simplify the structure of 
protective devices for couplings, thus reducing their cost and simplifying 
their manufacturing procedure. 
SUMMARY OF THE INVENTION 
In accomplishing the foregoing and related objects, the invention provides 
for the secure intercoupling of devices by elastically expandible means 
having opposed ends; and engagement means at one of the ends for securing 
the apparatus to one of the devices. 
In accordance with one aspect of the invention the elastically expandible 
means is a tube with a longitudinal axis and an interior with ribs to 
strengthen the elastically expandible means. The ribs can take a variety 
or forms, which can be plain of uniform material or a non-overlapping 
spiral. The ribs can be exteriorly or interiorly positioned, and the tube 
can have a thickness dimension with reinforcing threads inlaid therein. 
The elastically expandible means can be an elastomer, including rubber, and 
the engaging means can comprise a ring that is rollable over one of the 
devices. 
The devices can be electrical connectors, comprising a plug and a socket, 
and the engaging means can be a starter lip for facilitating the 
positioning of the tube over one of the devices. 
In a method of the invention for the secure intercoupling of devices, the 
steps include (a) positioning an elastic member or tube on one of the 
devices; and engaging one of the devices at one of its ends. The elastic 
tube has a longitudinal axis and can have ribs that are positioned 
interiorly or exteriorly to strengthen the tube. The tube further can be 
reinforced by inlaid threads. 
The elastic tube can be formed of rubber with engaging means formed by a 
ring that is rollable over one of the devices.

DETAILED DESCRIPTION 
With reference to FIG. 1, the security coupling device 10 of the invention 
is an elastic tube 11 with rollable ends 12-1 and 12-2. While the tube 11 
has a circular cross-section, it will be appreciated that other forms of 
closed cross-section may be used as well, for example elliptical and 
polygonal. In addition the tube is desirably of elastomeric material which 
allows the tube 11 to accommodate various protuberances on the devices 
being interconnected. As indicated in FIG. 1 the coupling device 11 is 
intended for the secure fastening of a plug 13 to a socket 14 by moving 
the plug 13 in the direction indicated by the arrow 13A into the coupling 
device 11, and by moving the socket 14 in the direction indicated by the 
arrow 14A into the coupling device 11. To accomplish this movement the 
coupling device 11 is expanded over the plug 13 and the socket 14 and the 
plug is inserted into the socket in conventional fashion to produce the 
end result indicated in FIG. 2, which is a perspective view of the 
security coupling device 11 of FIG. 1 after the plug and socket have been 
coupled. 
In another method of coupling, the security coupling device of the 
invention can have a tapered body and be positioned over a dummy plug or 
socket to its outer edge. Then a socket or plug to be coupled is inserted 
into the dummy plug or socket and coupling device rolled over the inserted 
socket or plug and beyond the dummy plug or socket. 
Alternatively, the taper of the dummy plug or socket can be used to expand 
the coupling device appropriately. The coupling device is positioned below 
the taper on the dummy plug or socket, and is unrolled and rolled up over 
the taper to the outer end of the dummy plug or socket, so that when the 
real socket or plug is temporarily connected to the dummy plug or socket, 
coupling device can be positioned on the real socket or plug. Thereafter 
the dummy plug or socket is disconnected and the plug or socket that is to 
be coupled to the previously inserted socket or plug is joined to the plug 
or socket being coupled. The protective coupling is completed by partial 
rolling back over the new plug or socket. 
The use of a dummy plug or socket provides a convenient way of storing the 
security coupling device of the invention until it is ready for use. When 
the body of the coupling device is tapered, it can be either 
unidirectionally tapered or bidirectionally tapered, with the taper 
increasing from the ends of the device towards its center. 
An enlarged elevation view of the security coupling device 11 of FIG. 1 is 
shown in FIG. 3 with a comparatively thin wall 11w to facilitate radial or 
lateral expansion of the coupling device 11 over objects to be coupled. In 
addition the thin wall 11w provides rolled ends 12-1 and 12-2 which can 
facilitate the secure coupling procedure. An end view of the rolled end 
12-1 for the security coupling device 11 is shown in FIG. 4. 
In section the security coupling device 11 of FIG. 3 is as shown in FIG. 
5A, with the end 12-1 fully unrolled, and the end 12-2 partially rolled. 
In the sectional view of FIG. 5B the security coupling device 11 of FIG. 
5A is seen to have reinforcing filaments 15 which extend longitudinally 
and thus do not inhibit lateral expansion of the kind illustrated in FIG. 
2. The reinforcing filaments may be of any suitable metallic or polymeric 
material. 
In FIGS. 5C through 5E partial sectional views for the coupling device 11 
have various alternative ends 12-a through 12-c for providing suitable 
engagement members on at least one of the ends 12-1 or 12-2 for securing 
the coupling device 11 to a device. In FIG. 5C the end 12-a is fully 
rounded, while in FIG. 5-b the end 12-b is partially rounded. In FIG. 5E 
the end 12-c is rectangular and coincident with the wall 11w. In all cases 
the ends 12-a through 12-b are rollable as indicated in FIGS. 1 through 3. 
It will be appreciated that other suitable ends may be provided for the 
coupling device 11. 
In the alternative security coupling device 11', shown in longitudinal 
section in FIG. 6A, the wall 11w' is provided with reinforcement ribs 15' 
that are non-overlapping when end rolling takes place and are further 
illustrated in the end view of FIG. 6B, before sectioning. 
FIG. 7A shows the coupling device 11 of the invention positioned on a cord 
16 attached to the socket 14 preparatory to coupling to a plug. This 
positioning of the coupling device 11 provides convenient storage when the 
coupling device 11 is not being used. As shown in FIG. 7B, when the 
coupling device 11 is to be used, it is pushed forwardly and rolled over 
the socket 14. The plug 13 is pushed into the socket 14 and the end 12-2 
of coupling device 11 is rolled forwardly over the plug 13 to achieve the 
configuration shown in FIG. 7C. 
An alternative security position for the coupling device 11 of the 
invention on the plug of FIG. 7C is shown in FIG. 7D where the end 12-1' 
is proportioned to snugly surround the cord 16, as opposed to having a gap 
between the the end 12-1 and the cord 16 as shown in FIG. 7C. 
With reference to FIGS. 8A through 8D, a preferred technique is illustrated 
for the intercoupling of the plug 13 and the socket 14 making use of a 
dummy socket (or plug) 17. The dummy socket 17 is shown in FIG. 8A with a 
taper 17-t extending from a shank 17-s. A coupling device 11 of the 
invention is initially positioned on the shank 17-s and taper 17-t as 
shown in FIG. 8B. Thereafter the coupling device 11 is expanded over the 
taper 17-t of the dummy socket 17 to the outer portion 17-p as shown in 
FIG. 8C. Then, as indicated in FIG. 8D, the coupling device 11 is 
transferred from the dummy socket 17 to the plug 13. In the final step the 
dummy socket is removed and replaced by an actual socket 14, and the 
coupling device 11 positioned as shown in FIG. 7C. 
It will be appreciated that the foregoing detailed description is 
illustrative only and that modifications and alterations, including 
equivalents, may be made without departing from the spirit and scope of 
the invention as defined in the appended claims.