Patent Grant
8563860
The present invention is in the field of extension cords.
Extension cords usually have multiple wire conductors, each of which has its own insulator, which are then contained within an outer jacket covering. Cords with multiple conductors may also be bundled together with tape or a binder prior to jacketing.
Extension cords are sold coiled and uncoiled. Uncoiled extension cords are good for short distances, and can be stored in a retracting wheel device when they are longer. Coiled extension cords rely on their coiling to keep them neat when not extended, and they typically have a coiled diameter of one and one half to two times the cord diameter. In this regard, although it is not an extension cord, telephones commonly have coiled cords.
The present invention is generally directed to a coiled extension cord having a coiled diameter of at least 3.5 times, and preferably approximately 5.0 to 7.0 times, the cord diameter. The primary insulation and jacket of the extension cord has a hardness of approximately 50 D or more (and preferably 55 D or more) and is comprised of a blend of thermoplastic and/or thermoset materials of thermoplastic elastomers (which include polyester, polyurethane, olefin rubber) cross linked polyethylene, polypropylene, polyvinyl chlorine and ethylene vinyl acetate. The coiled portion of the extension cord has a memory that allows the cord to extend out up to approximately 25 to 30 time its retracted length, and then retract back to its retracted position. Memory is imparted to the coiled extension cord by first making the cord (or cable), then winding the cord around a mandrel or other device, backing the cord at a sufficient temperature and length of time to create the memory, and then reversing the winding of the cord.
Accordingly, it is a primary object of the present invention to provide an improved extension cord having a larger coiled diameter relative to the cord diameter with a hard jacket.
This and further objects and advantages will be apparent to those skilled in the art in connection with the drawings and the detailed description of the invention set forth below.
The present invention is generally directed to a coiled extension cord having a hard outer jacket and a larger diameter coil relative to cord diameter than is conventional in the industry.
The present invention will now be discussed in connection with a preferred embodiment illustrated in
In the Figures and the following more detailed description, numerals indicate various features of the invention, with like numerals referring to like features throughout both the drawings and the description. Although the Figures are described in greater detail below, the following is a glossary of the elements identified in the Figures:
As illustrated in
As is illustrated in
Outer protective covering or jacket 21 of cord is important to the present invention. It is especially desirable that the thickness of jacket 21 be kept minimal so as to minimize overall diameter 5 of cord 2, although jacket 21 must still provide suitable insulating properties. To achieve this trade-off, it is especially preferred that jacket 21 have a high Durometer hardness, e.g., a Durometer hardness of approximately 50 D or more, and more especially, approximately 55 D scale or more, which also increases its tensile strength compared to conventional extension cords that have a hardness of 75 to 87 A scale. To achieve such hardness, jacket 21 can be made of a blend of thermoplastic and/or thermoset materials of thermoplastic elastomers (which include polyester, polyurethane, olefin rubber) cross linked polyethylene, polypropylene, polyvinyl chlorine and ethylene vinyl acetate.
An extension cord according to the present invention should have a coiled diameter of at least 3.5 times, and preferably approximately 5.0 times or more, the cord diameter 2, as compared to a conventional coiled diameter of 1.5 to 2.0 times cord diameter.
A coiled extension cord according to the present invention has many advantages over a conventional coiled extension cord.
A coiled extension cord according to the present invention is anti-kinking and has cut resistance due to increased hardness, whereas conventional coiled extension cords can kink and are not cut resistant.
A coiled extension cord according to the present invention has high abrasion resistance and durability, as compared to moderate abrasion resistance and durability of conventional coiled extension cords.
A coiled extension cord according to the present invention has a coil extension force which has less pull force compared to conventional coiled cord which has the benefit of a lower possibility of pulling loose from a power source.
It is important for an extension cord according to the present invention to have a memory that will hold coils 3 in cord 2 tight when the extension cord is not in an extended condition (see
Set forth below in Table 1 is a listing of a few exemplary extension cords according to the present invention. These examples are not meant in any way to be limiting, but merely illustrative examples of a few types of extension cords that can be made according to the present invention, and other types of extension cords, with different gauge sizes, cable diameters, coil diameters, and lengths, can be made according to the present invention.
The practical space-saving extension cord of the present invention can be used with kitchen appliances, vacuum cleaners, hair dryers, cloth irons, recreational vehicles, marine docks, heavy contractor's electrical tools, garden electrical tools, handyman electrical tools, computers, electrical vehicles, and other applications with need of power supply and extension cords/cables.
While the invention has been described herein with reference to certain preferred embodiments, those embodiments have been presented by way of example only, and not to limit the scope of the invention. Additional embodiments thereof will be obvious to those skilled in the art having the benefit of this detailed description.
Accordingly, it will be apparent to those skilled in the art that still further changes and modifications in the actual concepts described herein can readily be made without departing from the spirit and scope of the disclosed inventions as defined by the following claims.
This application is a non-provisional of U.S. Patent Application Ser. No. 61/498,136, filed Jun. 17, 2011, of the same title, the disclosure of which is specifically incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1989066 | Shaw | Jan 1935 | A |
| 2039475 | Campbell | May 1936 | A |
| 2051316 | Shaw | Aug 1936 | A |
| 2206703 | Lowe | Jul 1940 | A |
| 2573439 | Henning | Oct 1951 | A |
| 3240867 | Maddox | Mar 1966 | A |
| 3274329 | Timmons | Sep 1966 | A |
| 3318994 | Perrone et al. | May 1967 | A |
| 3324229 | Ingmanson | Jun 1967 | A |
| 3694279 | Rohrig et al. | Sep 1972 | A |
| 3854002 | Glander et al. | Dec 1974 | A |
| 3993860 | Snow et al. | Nov 1976 | A |
| 4683349 | Takebe | Jul 1987 | A |
| 4852964 | Holland et al. | Aug 1989 | A |
| 4861945 | Buck et al. | Aug 1989 | A |
| 4945191 | Satsuka et al. | Jul 1990 | A |
| 4988833 | Lai | Jan 1991 | A |
| 5763836 | Anastasi et al. | Jun 1998 | A |
| 20100006320 | Tatsumi | Jan 2010 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 61498136 | Jun 2011 | US |
