US2724752A - Portable safety lamp - Google Patents

Description

Nov. 22, 1955 Filed July 6, 1954 D. D. DENN|s 2,724,752

PORTABLE SAFETY LAMP 2 Sheets-Sheet 1 llllll D 'T/gw@ one I .DerwllsI @jmd Attar-nej Nov. 22, 1955 D. D. DENNIS PORTABLE SAFETY LAMP 2 Sheets-Sheet 2 Filed July 6, 1954 55 /NVEH TOR United States Patent Oiiice 2,724,752 Patented Nov. 22, 1955 PORTABLE SAFETY LAMP Donald D. Dennis, Indianapolis, Ind., assigner to Denley f Corporation, Indianapolis, Ind., a corporation of lndiana Application `luly 6, 1954,.Serial No. 441,58()

9 Claims. (Cl. Zilli- 117) This invention relates to a fuse device for preventing overheating of electrically operated units, such as in motors, electric lamps, and in general in any device wherein there is an electrical circuit which may under certain conditions causeva generation of an undue amount of heat, which undue amount may become serious either to the unit itself or tend to start combustion of surrounding materials. The invention is herein described in the one particular form as embodied inl a portable lamp such as is usually carried about on the end of an extension cor-d. Lamps suspended from such cords generate considerable heat, and' particularly where those lamps are enclosed in a safety dome v.used to `protect the lamp itself. There have been fires started by reason of the use .of such a portable lamp where the lamp has been left hanging in a grain bin in an elevator, and then `the lamp being forgotten, the 'bin is .filled with grainA to such a depth that `the lamp is covered over while still burning.

lt is the primary purpose of my invention to break the electrical circuit to a device which may become unduly heated so as to set up a heated atmosphere therearound beyond the `kindling temperature of the surrounding materials.

In addition Vto that general over-all purpose, there is the purpose .of providing an exceedingly simple but most effective structure to accomplish the breaking of the electrical circuit in a very positive and certain manner so that the circuit willwbe broken beyond any doubt when a certain temperature is reached in the zone wherein the fusing structure is located.

A still further important object of the invention resides in the fact that fuse links may be q uite readily replaced after breaking under the iniiuence of the heat above a predetermined temperature, coupled with the fact that the fuse element itself cannot be removed before such fusing without mechanical injury tothe device.

A still further important object of the invention is to provide a structure wherein the fuse elements will break the circuit regardless of in what position the device carr'ying `the fuse elements may be positioned, such for example'in reference to a portable lamp, whether or not the jlamp is `suspended to hang downwardly, is hung up to extend vertically, or is allowed to lie upon its side.

4These and many other objects and advantages of the invention will become apparent to those versed in the att-in the following description of the invention as illustrateti -in the one particular form in the accompanying drawings, vin which 'Fig. `l is a view in side elevation and partial section of a-portable-lamp structure embodying the invention;

Fig. 2 is a transverse section on the line 2-2 in Fig. 1 n anenlarged scale;

Fig. 3 isa view in top plan of the lamp base and carrier;

Fig. 4 is a view in end elevation of a fuse holding bracket;

-Fig. '5 is a view in top plan of a fuse element;

Fig. 6 is a view in side elevation and partial section of the fuse assembly unit;

Fig. 7/is a view in bottom plan of the fuse assembly;

Fig. 8 is a modified form of circuit breaker and circuit maker in top plan View; and

Fig. 9 is a view in end elevation.

A. base 10 Vmade out of rubber in the usual manner carries a lamp socket 11 from which there flares outwardly a dome base 12 which screw-threadedly engages a lamp cover dome 13`. The usual incandescent lamp 14 is l,screw-threaded into the receptacle 11 before the dome 13 is engaged with the base 12. This much of the structure is standard and well known. The invention is provided in an assembly which is applied to this structure by mounting it inside otthe dome 13 and fixingy it to the floor 15 of the base 1,2. outside of the socket 11'. The assembly is generally designated by the numeral 16. In this assembly there is a base annular plate 17 made out of any suitable insulating material having a yhigh dielectric strength. A reector annular plate 18 preferably made out of metal and having a high degree of heat and light reflection is mounted concentrically of the plates. 17 and spaced a .distance thereabove. In order to achieve the spacing between the plates, there is provided a plurality of spacing posts 19, having a screw 20 entered through the plates 18 and screw-threadedly engaged in the. upper end of the post 19, Fig. 6 in each instance. An insulating sleeve 21 snugly surrounds the post 19 over its major length- -between the plates 18 and 17 and then` a lower screw 22 is entered through a spacer thimble 23 to screwthreadedly engage in the lower end of the post 19. lWashers 24 and 25 are placed on the `opposite sides of the plates 18 between the post 19 and sleeve 2.1 on the one side and the plates 17 and the spacer 23 on the other side. There are four of these spacing devices employed inv the structure as illustrated.

There is a plurality of brackets 26 mounted around the plates' 17, the brackets 26 being mounted in pairs such as 27Vand 28, one on each side of a post 19 and spaced circumferentially therefrom at equal distances. Each bracket 26 s rockably mounted by any suitable means, herein shown as by a rivet 29 extending through a foot 30 and down through the plate 17. The foot 30 is preferably rockable about the rivet 29.

Referring toFig. 4, each bracket 26 has the mounting foot 430 from which the bracket extends by a leg I3.1 at right angles and upwardly to an upper bend 32 from which the vmetal of the bracket extends downwardly through a length 33 in intimate contact with the leg 31, down to a lower bend 34. From the lower bend 34a leg extends upwardly parallel to the legs 31 and 33, but in spaced relation therefrom. This leg 35 extends upwardly to a top bend 36 at approximately the same elevation as the bend 32 and then there is a very short foot 37 turned downwardly between the leg 35 and the leg 33. This leaves in effect a slot through the bracket between the legs 3'3 and 35, and between the lower end of the foot 37 and the bend 34.

A spring 38 interconnects by its ends with a bracket 27 on one side and a bracket 28 on `the other side between adjacent posts 19, the spring 38 tending to pull the two brackets 27 and 28 apart. There are threeof these springs 38 arranged around the ring 17 between the corresponding brackets, Fig. 2. A shorter spring 39 interengages the bracket 28 and a sleeve 40 of insulating material which sleeve 40 in turn interengages or interconnects with the next bracket 27.

A fuse link1 Fig. 5, is made outrof two strips of metal 42 and 43 in eifect soldered one to the other in overlapping end relation by a suitable fuse material. The material will vary in its make-up depending upon the degree at which it is supposed to melt. Each of the strips 42 and 43 normally tixed one to the other as just indicated has an end leg 44 and 45 respectively turned in the same direction. One of these fuse links generally designated by the numeral 46 is interengaged in each pair of brackets 27, 23 by being slipped downwardly between the legs 32 and 36 by end portions until the bends 42 and 43 slip past the foot 37 to allow that foot to spring back into Contact with the upper portion of the leg 33 so that the fuse then cannot be lifted upwardly and disengaged from the brackets. Also the legs 44 and 45 are positioned on the outer edges of the brackets so that the fuse element 46 as a whole may not slip longiand disengaged from the brackets. Also the legs 44 and in each pair cannot spread apart one from the other circumferentially around the plate 17. On the other hand, the springs 3S and 39 tend to pull the adjacent brackets one toward the other so as to hold them in firm abutment with the legs 44 and 45 of the individual fuses. In oher words, each fuse 46 is held under tension by reason of the springs 38 and 39.

Referring to Fig. 7, adjacent pairs of the brackets are interconnected electrically across the underside of the plate 17 by means of the bus bars 47 interengaging the rivets 29. ri`hat is, these bus bars 47 serve as conductors between the pairs of brackets instead of the springs 38. inasmuch as the insulator sleeve interrupts the circuit between the brackets 27 and 28 interconnected therethrough with the spring 39, leads 48 and 49 are provided to extend inwardly from the rivets 29 of those two adjacent brackets 26. One of these leads 4S extends to the central terminal Sill in the socket l1, and the other lead 49 is in series with one of the wires coming through the cable 5t to the socket 11 so that the entire series of brackets and fuse links are electrically interconnected with the lamp 14 in series arrangement.

All of the fuse links 46 are freely confined between the lower and upper plates t7 and 18 so that they are not normally in direct line of wave-travel from the heat source of the lamp I4. The upper plate I8 is substantially of the same internal and external diameters as those of the lower plate 17. The assembly carrying the fuse links 46 is mounted on the iioor 1S by allowing the screw heads 22 to rest on that floor and there are a plurality of screws 53 passing through the lower plate 17 and scre.vthreadedly engaging the member 12, Fig. 1.

The structure described is substantially moisture and dust tight in respect to the lamp 14 and the fuse assembly. Normally there is a wire guard fixed to the member 12 around the groove 54, but not herein shown since it is a standard element and does not enter into the inventron per se.

Assuming that the lamp i4 is energized, and that it is left burning and becomes covered over with dust or other material until heat builds up within the dome 13 to that temperature at which the fusing material between the members 42 and 43 will melt, heat from the lamp I4 will have been reected and diffused in effect from direct radiation on the fuses 46, so that it is really the ambient temperature within the dome 13 which controls. The reflector plate 18 operates to intercept heat directly radiating from the lamp 14 to prevent the straight line radiation from reaching the fuses 46, so that it is the temperature of the air within the dome 13 which constitutes the ambient temperature about the fuses 46, rather than the directly radiated heat. When that critical temperature is reached, and the two members 42 and 43 are released one from the other by the melting of the intervening fuse material, the springs 38 on either side of the brackets 27 and 28 which carry that particular released element will cause those brackets to quickly rock to the positions as indicated in the dash lines, Fig. 2, whereupon the fuse members 42 and 43 will likewise be rocked until they are practically parallel under the pull of those springs. That is, when the fuse material melts, there is initially a wiping and pulling apart action of the members 42 and 43 in CII respect one to the other, so that there is a clean break between the members causing a positive interruption of the circuit. Any one or all of the links may release at the same time depending upon the characteristics of the fuse material, the slight variations there may have been in the over-all structure, but more particularly depending upon the position of the lamp 14 whether it be vertically positioned upwardly or downwardly or extending horizontally or inclined. In any event, regardless of the position of the lamp t4, there will be at least one of the fuse members 46 released at the critical temperature for which the fuse material has been selected.

As indicated in Figs. 8 and 9, the fuse device may be employed not only to break a circuit, but in adidtion to breaking a circuit, to completing a second or third circuit as may be desired. In this modied form, a pair of the brackets 27 and 28 are rockably mounted on a base 5S to swing around their rivets 29. A fuse link 46 is inserted across and into these brackets 27 and 2S, and the springs 38 tend to pull apart those brackets 27 and 28 to the positions at least as indicated by the dash lines. When the fuse 46 is subjected to an ambient temperature which causes the fusing metal to let loose between the members 42 and 43, the springs 38 will kick the brackets 27 and 28 around to those dash line positions and carry the fuse elements 42 and 43 against fixed brackets 56 and 57 which have the upturned legs 58 and 59. Since the brackets 56 and 57 are iixed in position on the member 55, they will effectively stop both of the fuse elements 42 and 43 in those dash line positions as shown in Fig. 8. Normally there would be a circuit completed between the brackets 27 and 2S, and when the fuse element 46 is separated, then selectively, a circuit may be completed between one of the brackets such as bracket 27 and a stop bracket 56, or another circuit between the bracket 28 and the bracket 57 completed, either selectively or both circuits at the same time as may be desired. In this manner, not only is the primary circuit interrupted between the brackets 27 and 28, but also a second circuit may be completed between the brackets 27 and the bracket 56 to some suitable alarm or indicating device (not shown) and likewise another signaling circuit or other device operating circuit may be completed between the brackets 28 and 57 through those fuse members 42 and 43 respectively.

Therefore, while I have described my invention in the one particular form, it is obvious that structural changes may be employed without departing from the spirit of the invention, and I therefore do not desire to be limited to that precise form beyond the limitations which may be imposed by the following claims.

I claim:

l. A fuse structure protecting against a predetermined rise in ambient temperature from a heat source, comprising a base member, a plurality of pairs of brackets rockably mounted around the member with axes in a generally circumferential line; a heat separable fuse link interconnecting the brackets in each pair; means interengaging the links and the brackets limiting swinging of the brackets one from the other in each pair; a spring normally under tension interconnecting a bracket of one pair with the next adjacent bracket of the next adjacent pair maintaining said links under tension; and insulating means interposed between one of said springs and a bracket interrupting an electrical circuit through the brackets and fuses.

2. The structure of claim l in which said brackets each have a slot thereacross, and each link is inserted by end portions across the slots, said link carried means comprising legs turned from the ends of the links to abut the outer sides of the brackets preventing travel of the bracket from the link.

3. The structure of claim l in which each link is in two parts with central overlapping end portions adhered one face thereof against the other through an intervening fuse material, the fuse material being limited in area to the area of the overlapping of said parts.

4. The structure of claim l in which there is a heat reflector and diffuser plate mounted in spaced relation between said links and said heat source.

5. The structure of claim 4 in which said reflector is mounted on said base member with said links in spaced relation between the reector and the base member.

6. The structure of claim 5 in which said base member is a ring and said retiector is also a ring wherein said links are confined within the circumferential boundaries thereof.

7. A circuit breaker structure comprising a base member; a pair of spaced apart brackets carried by said base rockably mounted on substantially parallel axes; a fuse link engaging both of said brackets; spring means normally tending to rock apart said brackets; said fuse link normally holding said brackets against rocking under action of said spring means; said fuse link being separable upon a predetermined ambient temperature being reached to release said brackets from being held by the link; said fuse link comprising two relatively rigid members overlapping by end portions between said brackets; and a metal melting at said predetermined temperature below the melting point of said members, said metal normally interengaging said end portions.

8. A circuit breaker structure comprising a base member; a pair of spaced apart brackets carried by said base rockably mounted on substantially parallel axes; a fuse link engaging both of said brackets; spring means normally tending to rock apart said brackets; said fuse link normally holding said brackets against rocking under action of said spring means; said fuse link being separable upon a predetermined ambient temperature being reached to release said brackets from being held by the link; a terminal post iixedly carried by said base in the path of and abutted by one of said end portions when said members separate under action of said spring means rocking its carrying bracket, whereby a second circuit may be closed between said carrying bracket and said terminal.

9. A circuit breaker structure comprising a base member; a pair of spaced apart brackets carried by said base rockably mounted on substantially parallel axes; a fuse link engaging both of said brackets; spring means normally tending to rock apart said brackets; said fuse link normally holding said brackets against rocking under action of said spring means; said fuse link being separable upon a predetermined ambient temperature being reached to release said brackets from being held by the link; an external heat source producing said ambient temperature; a heat reilector member carried in spaced relation between and intercepting direct radiation from said heat source and extending over said fuse link; and said reflector member being opened beyond said extent and providing free access therearound between said source and said fuse link for conducted and convected heat from said source to said link, such conducted and convected heat setting up said ambient temperature.

References Cited in the iile of this patent UNITED STATES PATENTS 465,046 McLain Dec. 15, 1891 601,492 Blackwell Mar. 29, 1898 726,605 Wilson Apr. 28, 1903 850,334 Anderson et al Apr. 16, 1907 982,281 Lincoln et al Ian. 24, 1911 1,734,230 Roe Nov. 5, 1929 1,934,244 Steinmayer Nov. 7, 1933 2,071,067 Gizzarelli Feb. 16, 1937 2,538,574 Kolisch Ian. 16, 1951 FOREIGN PATENTS 325,285 Great Britain Feb. 17, 1930

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