US1740480A - Self-soldering heat-coil fuse for switchboard protection - Google Patents

Description

H, F. SKIDMORE SELF SOLDERING HEAT COIL FUSE FOR SWITQHBOARD PROTECTION Filed March 25, 1927 Patented Dec. 24, 1929 UNITED STATES;

PATENT OFFICE HENRY I. SKIDMORE, OF CHIGAGQAILLINOIS, ASSIGNOI TO ELECTRIC 00.,

OF-CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS Y BELF-SOLDERIIIG HEAT-COIL FUSE FOB SVVITCIIIBOAIBID PROTECTION a lication filed March 25, 192i. Serial No. 17am.

My invention relates to thermal protective devices adapted to be inserted in an' electric circuit for breaking the circuit when an excessive amount of current flows in the circuit. I

More particularly my invention relates to the type of thermal protector known as a heat coil fuse wherein current in the circuit passes through a coil in the fuse and heats a portion of the device, the heating of this portion above a certain temperature causing the device to open the circuit.

It is a purpose of the invention to apply fuses of this character which maybe rea ily re-set by hand after it has been opened without removing the fuse from its mounting and without heating it up or using any particular tools.

Another purpose of this invention is to rovide a fuse of this character which may, y manual operation, be caused to open the circuit regardless of the amount of current flowing in said circuit.

Other objects and advantages of the invention will appear when taken in connection 7 with the accompanying drawings. However, I wish it to be distinctly understood that I do not intend to limit myself to the exact details shown and described, but that I intend to avail myself of all such modifications as would occur to one skilled in this art and.

as would fall within the scope of the claims.

In the drawings:

Fig. 1 is a sectional view taken longitudinally through the device;'and I Fig. 2 is a detail view illustratin the engagement between electrodes of the use,

Referring now in detail to the drawings,

the numeral 5 indicates an elongated shell which may be of any suitable insulatin terial, such for instance as glass, an this shell is provided at its opposite ends with the terminal members ,6 and 7, which as shown, fit down over the, ends of the shell and maybe secured thereon by any suitablecement or other means. Within the terminal 6, I provide the insulating washer 8 which is held in engagement with the end of the shell 5 by the terminal and which carries the inwardly extending rod or stem 9. This stem as shown has a squared shank portion extending through the washer 8 and at theouter end thereof is soldered down againstthe metal washer 11 by means of the solder 12. This structure retains the stem 9 rigidly in place and prevents rotation thereof relative to the washer 8. To further prevent any loosenin of the washer 8 within the terminal 6, preferably fill thespace around the washer 11 and solder 12 with a suitable cement as illustrated at 13.

A conductor extends from the tip 14 of the terminal 6 inwardly through an opening in the washer 8 and is coiled around the stem 9 as shown at 15 to provide a heating coil which, upon passage of current therethrough, will heat the stem 9. The end of this conductor is then passed through the washer 8 in the opposite direction and is secured in the solder 12.

From this point the circuit extends through the stem 9 to the ratchet wheel 16 which, as illustrated, is pivotallymounted in the slotted end 17 of the stem 9. This wheel is provided before assembly with a plurality of openings indicated at 18 and these openmgs are filled with the suitable soft solder having a desired melting point and the Wheel is soldered in place so that when the stem 9 is heated up, the solder will soften and release the ratchet 16 to permit it to be turned. When the stem 9 cools after the circuit is broken, the wheel 16 is again soldered against rotation by means of the solder in the holes 18in contact with both the wheel and the stem. v

The otherfelectrode'for completing the circuit' consists of the strip, 19 having the slot 20 therein, which slot is adapted to receive the edge of the wheel 16 and thus hook the member 19 over the teeth of the wheel. The strip 19 is formed integral with the tubular member 21 which extends outwardly through the open end of the terminal 7 and projects slightly thereheyond when the electrodes 16 and 19 are in contact. The stem 21 as shown, is rather loosely mounted, as shown at 22, in. the end of the terminal 7 so as to permit it to rock back and forth and in this manner be manipulated to engage the strip 19 with the ratchet wheel 16. I, i

To provide meansfor withdrawing the electrode 19 and opening thecircuit automatically when the stem 9 is heated so as to permit rotation of the wheel 16, I provide the spring 23, which as shown, is soldered by "spring withdraws the electrode 19 away from e wheel 16 to open a wide gap in the circuit and retains it in this position until it is again closed by pushing the rod 21 inwardly and manipulating it so as to engage slot 20 over the ratchet teeth of the wheel 16. When this is done, the fuse is again in condition for further use.

The advantages of this structure,-it is thought, will be readily apparent from the above description since it provides a fuse which'may be reset any indefinite number of times after opening the circuit by merely pressing in on the rod 21 without removing the tubefrom its mounting or in any way disturbing its use. Furthermore, if it is desired to open a circuit for any particular purpose, this may be done by manipulating the rod 21 to release the electrode 19 from the wheel 16 so as to make it unnecessary to remove the fuse or overheat it to separate the electrodes. The fuse in this way 'acts somewhat as a switch which may be manually operated.

Having thus described my invention, what I claim-as new and desire to secure by U. S. Letters Patent is:

1. A thermal protector of the character described comprising a pair of electrodes, heat j responsive means normally retaining said electrodes in electrical engagement and adapted upon undue increase in heat to permit separation of said electrodes, spring means normally under stress adapted to cause a wide separation of said electrodes upon softening of said heat responsive means, an

enclosing shell housing said electrodes, heat responsive means and spring means, and

. means projecting outside said shell for again setting said electrodes into operative engagement without re-softening said heat responsive means, said means projecting outside the shell also being manually operable to disjacent one of said terminals, said electrode comprising a stem having a ratchet wheel rotatably secured thereto, heat responsive means normally preventing rotation of said wheel. but adapted upon undue increase in heat to permit rotation thereof, a second electrode normally engaging said ratchet wheel but releasable therefrom'on rotation of said wheel, and'a spring normally under stress adaptedto rotate said wheel and separate said electrodes upon softening said heat responsive means. H

" 3. A thermal protector of the character described comprising an enclosing shell having terminals at opposite ends-thereof, an electrode rigidly secured to said shell. adjacent one of said terminals, said electrode comprising. a-stem having a ratchet wheel rotatably secured thereto, heat responsive means normally preventing rotation of said wheel but adapted upon undue increase in heat to permit rotation thereof, a second electrode normallyengaging said ratchet wheel but releasable therefrom on rotation of said wheel, a spring normally under stress adapted to rotate said wheel and. separate said electrodes upon softening said heat responsive means, and ano erating member connected with said second electrode 'projectin externally of said shell for re-setting said second electrode in engagement with said ratchet wheel.

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4. A- thermal protector of the character described comprising an enclosing shell having terminals at opposite ends thereof, an electrode'rigidly secured to said shell adjacent one of said terminals, said electrode comprising a stem;ha'ving a ratchet wheel rotatably secured thereto, heat responsive means normally preventing rotation of said wheel but adapted upon nndue'increase in heat to permit rotation thereof, a second electrode normally engaging said ratchet wheel but releasable therefrom on rotation of said wheel, and a spring normally under stress adapted to rotate said wheel and separate said electrodes upon softening said heat responsive means,- said spring electrically connecting said second electrode with the other of said terminals.

5. A thermal protector of the character described comprising. an enclosing shell having terminals at opposite ends thereof,

an electrode rigidly secured to said shell ad jacent one of said terminals, said electrode comprising a stem havingfa ratchet wheelrotatably secured; thereto, heatresponsive means normally preventing rotation of said wheel but adapted upon'u'ndue increase in heat to permit rotation thereof, a second electrode normally engaging said ratchet wheel but releasable therefrom on rotation of said Wheel, and a spring normally under stress adapted to rotate said Wheel and separate said electrodes upon softening said heat responsive means, said spring electrically connecting said second electrode with the other of said terminals, and an operating member projecting from said second eleetrodethrough said last named terminal for manually engaging or separating said electrodes.

1n witness whereof, I hereunto subscribe my7name this 25th day of February, A. D 192 HENRY F. SKIDMORE.

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