US2206783A - Fuse indicator - Google Patents

Description

FUSE INDICATOR Filed March 6, 1959 70 14 ly ql @4 4. as I 526 m w. c. LINTON 2,206,783

Patented July 2, 1940 UNETED STATES FUSE INDICATOR William C. Linton, Washington, D. C., assignor.

to Fuse Indicator Corporation, Washington, D. #0., a corporation of Delaware Application March 6,

3 Claims.

The present invention relates to indicators which visibly point out the power ratings and integrity of electrical fuses, having amongst its principal objects to provide a casing for such indicators which may be economically constructed and the parts thereof easily and readily assembled without the aid of additional fastening elements, thereby rendering the same commercially desirable.

Other objects of the invention will be in part obvious and in part pointed out hereinafter.

In order that the invention and its mode of operation may be readily understood by persons skilled in the art, I have in the accompanying drawing and in the detailed following description based thereupon, set out an embodiment of the same.

In the drawing:

Fig. l is a vertical section through a plug fuse embodying the present invention.

Fig. 2 is a bottom plan view of the cover section of the indicator casing.

Fig. 3 is a top plan view of the body portion of the casing.

Fig. 4 is a vertical section through the cover of the casing.

Fig. 5 is a vertical section through the body portion of the casing.

Fig. 6 is a vertical section through an indicator attachment for cartridge type fuses.

Fig. '7 is a detailed vertical section through the cover of the indicator attachment.

Fig. 8 is a detailed vertical section through the base portion of the indicator attachment, and

Fig. 9 is a vertical section taken on the line 9-9 of Fig. 6 in the direction of the arrow points.

Referring now more particularly to Figs. 1 to 5 inclusive of the drawing, I have illustrated a plug type fuse consisting of a base I having a tubular extension 2 and an annular flange 4 formed therewith. An. explosive chamber 3 is formed within this base and attached thereto is a rivet or central contact terminal 5. The fuse link 6 has one end connected to the rivet 5 i and is supported by the tubular extension 2 of the base. The casing for housing the explosive chamber and fuse link 5 has a tubular wall 1 which rests upon the annular flange 4 of the base and is connected to the latter by means of the threaded contact shell 8. The opposite end of the fuse link 6 is also connected to the contact terminal 8 and should this fuse link become blown or ruptured, the pressure of the given off would tend to separate the base I 1939, Serial No. 260,158 (01. 200- 121) and the cover in order that the gases may escape therebetwcen and around the shell 8.

The casing for the fuse is divided into an upper'or cover section 9 and a lower section Ill.

The cover section 9 has a recess H formed in the lower face'thereof, whereas, the outer. face of the section it has a companion recess l2 formed therein so that when the sections 9 and is are together, they will house a. glow lamp I3 111- the manner as is best illustrated in Fig. 1 of the drawing. This glow lamp has the lead wires M and 15 connected thereto and a leak resistance I6 is arranged between the sections of the lead wire l5. This leak resistance 15 is preferably made from a plastic composition containing a suitable conductive material and a binder, which latter will adhere to metals whereby when the lead wires I l and I5 are embedded therein, these Wires will be electrically and mechanically connected to the resistance. The lead s wire Hi extends through a vertical opening ll formed within the body portion of the section It and itsouter extremity is connected to the threaded contact shell 8'. A portion of the lead wire l5 and the leak resistance [5 arranged therein is seated within the recess l8 also formed within the upper face of the section IU of the casing from where the lead wire I5 extends through a vertical opening l9 also formed in this section In, and this lead wire l5, after extending through a slot formed within the tubular portion of the base I, is connected to the central contact terminal or rivet 5.

The lower face of the cover 9 is provided With one 'or more recesses 2| which receive corresponding knobs or projections 22 formed with the upper face of the section ID of the cover. The lower face 23 of the cover and the outer face 210i the base ID are subjected to polishing, resulting in a highly and brilliantly polished surface.

' From the above arrangement, it will be obvious that the fuse link 6 is connected in series with the terminals 5 and 8 and that the lamp [3 and the leak resistance I6 are also connected in series with the terminals 5 and '8 but in parallel to the fuse link 6, whereby, should this fuse link become blown or ruptured, electrical current will pass through the conductors l4 and I5 for causing the lamp 13 to glow and in this manner,-indicate the integrity of the fuse link 6.

' In Figs. 6 to 9, inclusive, I have illustrated an indicator attachment for cartridge type fuses which consists of a sectional casing comprising a-lower or base section and an upper or cover section 26. These sections have companion recesses 27 and 28 formed therein so that the glow lamp l3 may be completely housed within the casing of the indicator. A recess 30 is also formed within the base section 25 of the casing for receiving the resistor l6 and the cover section 30 is provided with knobs or projections 3| capable of being seated within aligning recesses formed within the base 25 in the manner as best shown in Fig. 9 of the drawing. Prongs or similar fastening members 32 may be connected to the casing of the indicator whereby the latter may be not only attached to a cartridge type fuse but may be electrically connected to the terminals of the fuse whereby electrical energy may be supplied from the terminals of the fuse through the members 32 to the lead wires 14 and 15 of the glow lamp.

The base I of the plug fuse and the base sections It and 25 of the indicator casings may all be molded from suitable molding powder to provide an insulator having the required tensile strength and dielectric qualities whereas the top or cover sections 9 and 26 of the indicator casings are made from thermo-plastic molding powders which produce a transparent or translucent cover for the lamp [3 whereby the rays of light therefrom may project through this cover. The thermo-plastic molding powder preferred for producing these covers is a polymerized methyl methacrylate which is available in a wide variety of brilliant translucent colors and which may be molded in the shape and designs as herein shown, through ordinary molding processes which require heat and pressure. The sections l and 25 of the casing may also be made from thermoplastic molding powders but when prepared from thermo-setting materials, the upper part should have mixed therewith a thermo-plastic molding powder similar to the molding powder used in casting the covers 9 and 26, in order that when a cover is placed upon the lower or base section of the casing, it may be cemented thereto by a cement containing a solvent which will render plastic the adjacent faces of the cover sections and base sections of the casings, whereby, the two will be cemented to one piece, thereby eliminating the necessity of additional fastening elements or other means for permanently connecting the covers to the base sections of the casings.

When using polymerized methyl methacrylate and thermo-plastic molding powder, the cement used for connecting the sections of the casing together should be one containing a solvent of the lower ketone and ester solvents, and mixtures of aromatic hydrocarbons with small amounts of alcohol. By highly and brilliantly polishing the surfaces 23 and 24 of the sections of the casing, the joints between the two will be hardly noticeable when the solvent contained within the cement used for connecting these sections together completely evaporates. The joints between these sections are mechanically as strong as the material itself.

The cover sections of the indicator housings may be of various colors for designating the power ratings of the fusible elements of the fuse to which they are connected and when the lamp l3 glows, a brilliant light will be visible from the exterior or outer face of the fuse or fuse casing which extends entirely over the outer face of the translucent cover and is not confined to any particular point within the indicator casing. When these covers of the indicator casing are made of colors, a colored light corresponding with that of the color of the casing will be projected from the fuse to which the indicator is attached for not only indicating the integrity of the fuse but also designating the particular power rating of the blown fuse.

From the foregoing, it is apparent that the upper and lower sections of the indicator casing may be made of the same thermo-plastic molding powders so that when again heating the contacting surfaces 23 and 24 of the sections, they will become plastic. When these sections of the casing are placed together and these plastic surfaces allowed to cool, a welded connection is established between the two sections, thereby eliminating the necessity of solvents, cements 0r fastening elements for connecting the sections of the casing together. When the base sections In or 25 of the indicator casings are prepared from thermo-setting plastic powders, it is necessary, during the molding of these powders, to sprinkle or otherwise place upon the outer face or the face 24 of the casing H! a thermo-plastic molding powder which is cast with the thermo-setting molding powders. When heat or a solvent is applied to the thermoplastic material formed with the outer face 24 of the section ill of the casing so as to render the thermo-plastic materials contained therein again plastic, this surface will adhere to the plastic surface 23 of the cover 9 should heat or a solvent be applied thereto.

Manifestly, the construction herein shown is capable of considerable modification and such modifications as come within the scope of my claims, I consider within the spirit of my invention.

I claim:

1. An indicator for fuses comprising a casing, said casing having a recess formed in the opened upper end thereof, contact terminals, a glow lamp seated within said recess and connected in series with said contact terminals, a cover having a recess formed in one face thereof for receiving and housing said lamp, means for preventing the rotation of said cover upon said casing and means for connecting the opposed faces of said cover and casing together.

2. The combination with a plug fuse having a base and a casing, contact terminals and a fuse link connected in series with said contact terminals, said casing having a recess formed therein and extending horizontally across the outer face thereof, a glow lamp indicator and leak resistor seated within said recess of the casing, said casing having openings formed therein each having one end communicating with said recess and their opposed ends communicating with said contact terminals, lead wires extending through said openings for connecting said glow lamp indicator and leak resistor in series with said contact terminals but in parallel to said fuse link and a cover connected to said casing for housing said glow lamp.

3. An indicating plug fuse comprising a base, a casing fitted to said base forming a combustion chamber therein, a central contact secured to said base, a threaded contact shell connecting said base and casing, a fuse link arranged within said combustion chamber and connected in series with said central contact and said threaded contact shell, said casing having a recess formed within the outer face thereof, a glow lamp and resistor seated within said recess of the casing, said casing having a pair of vertically extending openings formed therein, one end of each of said said glow lamp and leak resistor in series with said central contact and said threaded contact shell but in parallel to said fuse link, a cover for housing said lamp and leak resistor seated upon the outer face of said casing and means 5 for connecting said cover to said casing.

WILLIAM C. LINTON.

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