US2137342A

US2137342A - Self-indicating plug fuse

Info

Publication number: US2137342A
Application number: US167009A
Authority: US
Inventors: Reginald W King
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-10-02
Filing date: 1937-10-02
Publication date: 1938-11-22
Anticipated expiration: 1955-11-22

Description

Nov. z2, 1938.

sa@ e R. w. KING 2,137,342

SELF INDICATING PLUG TUSE Filed Oct. 2, 1937 Patented Nov. 22, 1938 UNITED I STATES PATENT OFFICE 6 Claims.

This invention relates to fuse plugs for electrical circuits, and more particularly to selfindicating fuse plugs, so-called, constructed to indicate when they are blown.

In the drawing of one embodiment of my novel invention selected for illustration and description herein:

Fig. 1 is a plan;

Fig. 2, a vertical section on, the line 2-2, Fig. 1, with the parts in normal position;

Fig. 3, a similar view with the parts in abnormal or inoperative position, and indicating that the fuse has blown;

Fig. 4, a horizontal section on the line 44, Fig. 2, looking down; and

Fig. 5, a detail of a portion of Fig. 4, on an enlarged scale.

Referring first to Figs. l and 2 oi the drawing, -my novel fuse plug comprises a chambered shell I, of any suitable material, as hard rubber, porce lain and the like, with an opening 2 at its upper end.

The lower end of the shell is threaded as at 3, 'to engage the usual block or other receptacle therefor, on a support not shown, and is provided with a similarly shaped conductor sleeve 4 of metal or other suitable material, to conduct the current from the block to the fuse, and it also is fashioned to carry the cap member 5 for the shell, with the conductor post 6.

This post carries, in turn, the conveniently shaped fuse element 1, of suitable material, as metal, and the fuse is secured between` the lower edge of the shell, a gasket 8 and the cap 5, with the opposite fuse end soldered or suitably secured to the conductor sleeve 4 at 9.

Adjacent the bridge portion I0 of the fuse, there is mounted an inverted U-shaped strip of any suitablegas-producing, inflamm-iable and deagrating, button-ejecting material I2, which is retained in close proximity to the fuse 'l by being secured at its ends between the gasket 8 and the cap 5.

The strip I2 should not only be of an inflammable and deagrating nature, but should also be of such chemical composition as to include sufficient oxygen to support the combustion of the strip in the absence of atmospheric oxygen, for it may be that there will be insufficient atmospheric oxygen confined in the plug to consume any appreciable quantity of a combustible material. Furthermore, not only should the mate rial I2 be of such nature as to ignite and burn readily, or deflagrate in its chamber I9 when ignited by the flash from the fuse 1 when it blows,

but the button projecting member should also possess the characteristic of producing, in its combustion, such a large volume of gases as to cause them, when confined in the plug, to develop sufiicient pressure to force a button I4 forward and project it through the opening 2, which also serves as an exit for the escape of air from the plug when it ejects the button. Cellulose nitrate is satisfactory under all prevailing conditions in which it has been tried. I can think of no condition where it would not answer the purpose satisfactorily, unless where the current was flowing through the fuse in such quantity and under such continuous use as to raisel the temperature of the chamber of the plug to a degree suflicient to cause decomposition of the cellulose nitrate. Such a condition is not to be anticipated, and would be most unusual, and probably due to faulty construction.

If one wished to guard against such extreme or unexpected conditions, a gas-producing, inflammable strip of material, analogous in all essential respects to cellulose nitrate, but less responsive to a long-continued, high degree of heat, such as a strip of heavy paper, carrying a coating of granules of gunpowder, might be used. This would be a natural substitute for the nitrate cellulose in its form of action, but not so convenient for use, as it would need to be specially prepared.

The button I4 should be provided with a cup shaped or other suitably-shaped base I5, as a contact area for the gas tol ensure the projection of the button. In this instance, I have provided the base with a skirt or housing I6 to more reliably ensure the action of the gas on the button by reducing the volume of the combustion chamber to a smaller area. The clearance space I'I between the housing I6 and the shell I may be closed practically air-tight by sealing it with a washer or bushing I8 on the housing outer wall, thus providing a closed combustion chamber I9, and also ensuring that the button will remain in any adjusted position in the shell.

The button may be of the same color and material as the shell, b-ut preferably has its side wall 28 of a contrasting color, as blue, for instance, to attract attention.

It is a very desirable qualification to the successful operation of a device of this kind that the gas-producing, inflammable and deflagrating material I2, partially surrounding the bridge portion I0 of the fuse, shall unfailingly ignite the instant the fuse blows. Now it is known that a sharp point or edge of any combustible material is more readily ignited than is a ilattened or smooth surface of the same. Therefore, in recognition of this fact, that portion of the strip I2, if of a material having a smooth surface, immediately surrounding the bridge portion of the fuse is so pierced as to create a number of sharp points or teeth 2l and edges, all projecting inwardly and thence effectively subjected to the ame and molten metal of the arc formed at the instant of the blowing of the fuse.

The button I6 may be provided with guides 22 to retain the element I2 in proper position.

My invention is not restricted to the particular embodiment thereof herein described and illustrated, but may bemodied in many details, without departing from the spirit of the claims, and within the scope thereof.

I claim:

1. A self-indicating chambered fuse plug with a fuse and conductor member therefor in the chamber, the chamber having one end closed with a conductor member therein, an opening in one plug end, a button movable therein, and a pressure producing member in the chamber and ignitable by the fuse to produce vapor to project the button through said opening.

2. A self-indicating fuse plug with a chamber and an opening thereto, a fuse therein with conductor members therefor, a button with an eX- panded inner end movable in said opening, and a gas-producing member in said plug and ignitable by the fuse when it blows, to project the button through said opening.

3. A self-indicating fuse plug with a chamber having a fuse therein, and conductor members therefor, an opening in one plug end, a housing in the shell chamber with a bushing and having a button thereon with a distinctively colored end projectable through said opening, a gas-producing member in said plug adjacent the fuse and ignitable thereby when it blows, to move said housing and project said button end through the opening.

4. A self-indicating fuse plug comprising a shell with a chamber having an opening in one end, a housing with a button thereon in the shell, the housing tting closely in the chamber and movable therein, receptacle-engaging means on the plug, with a conductor member connected thereto, a fuse-carrying conductor member on said shell end with a fuse thereon connected also to the first-named conductor means; a rough-surfaced, gas producing member adjacent said fuse and ignitable by the blowing of the fuse to create pressure to project said button from the shell chamber and through said opening.

5. A self-indicating fuse plug comprising a shell with a chamber having an opening in one end, a housing with a button thereon in the shell, the housing fitting closely in the chamber and movable therein, receptacle-engaging means on the plug, with a conductor member connected thereto, a fuse-carrying conductor member on said shell end with a fuse thereon connected also to the first-named conductor means; a toothed gasproducing member adjacent said fuse and ignitable by the blowing of the fuse to create pressure to project said button from the shell chamber and through said opening.

6. A self-indicating fuse plug with a chamber and an opening thereto, a fuse therein with conductor members therefor, a button with an expanded inner end movable in said opening, and a cellulose nitrate member in said plug and ignitable by the fuse when it blows, to project the button through said opening.

REGINALD W. KING.