US1735907A - Fire alarm - Google Patents

Description

Nov. 19, 1929. H. T. MITCHELL FIRE ALARM Filed Dec. 19, 1925 Wkuamo .4 g).

Patented Nov. 19, 1929 UNITED STATES PATENT OFFICE HENRY TRICE MITCHELL, OF KANSAS CITY, MISSOURI, ASSIGNOR 'IO THEODORE G. JOHNSON, OF KANSAS CITY, MISSOURI FIRE ALARM Application filed December 19, 1925. Serial No. 76,502.

My invention relates to fire alarms and my object is to provide a simple, reliable and inexpensive apparatus of this character which can be installed at small cost in private dwellings, hotels, factories, etc.

A further object is to provide a novel switch for controlling the circuits of the alarm apparatus, and in order that the invention may be readily understood reference will now be had to the accompanying drawing, in which:

Fig. 1 is a side elevation of the apparatus constituting the invention with the parts in normal position in full lines and in dotted position after having transmitted an alarm.

Fig. 2 is a front elevation of the apparatus in the position it occupies after transmitting an alarm.

Fig. 3 is a longitudinal section of a container employed in carrying out the invention.

Referring in detail to the different parts, 1 designates a metallic or other fire resistant holder of semitubular form connected at one end by a pivot 13 to the lowerend of a suitable support such as a bracket 2 which is adapted to be secured to a ceiling or other support with screws 12. The opposite end of the holder 1 is provided with a hook 14: for engagement with one end of an alloy or other fuse 3, the opposite end of which is adapted to engage over a hook 16 depending from the upper portion of the bracket 2 as shown by Fig. 1.

4 designates a container consisting of glass or other suitable nonconducting material and secured in the holder 1 by metallic straps 6. The container 4 is provided with a quantity of conducting material, consisting preferably of mercury, which is free to travel from one end of said container to the other.

7 designates a pair of contacts extending through the end of the container 4. nearest the pivoted end 13 of the holder 1. Said contacts 7 together with the mercury 5, constitute a part of a normally closed circuit including binding posts 9 and circuit wires 10 and 15. The binding posts 9 are supported by but insulated from the bracket 2 and have the respective circuit wires 10 and 15 connected thereto as shown by Figs. 1 and 2.

The end of the container 1 nearest the fuse 3 has a pair of contacts 8 extending therethrough and forming a portion of a normally open circuit including a pair of binding posts 9 circuit wires 11 and circuit wires 17. The binding posts 9 are supported by but insulated from the bracket 2.

In practice the holder 1 is suspended in an inclined position by the fuse 3 as shown by Fig. 1. This causes the mercury 5 to flow to the lower end of said container 1 and uncover the inner ends of the contacts 8 and submerge the inner ends of the contacts 7, thereby opening the circuit through the wires 11, binding posts 9 and the wires 17 and closing the circuit through the wires 10, the binding posts 9 and the wires 15.

Should a fire occur in the vicinity of the appara-tus and cause the temperature to rise sufficiently to destroy the fuse 3, the holder 1 and the container 1 will immediately swing downwardly to the dotted line position Fig. 1, whereupon the mercury 5 will uncover the inner ends of the contacts 7 and submerge the inner ends of the contacts 8, thereby closing the signal circuit through the wires 11, the binding posts 9 and the wires 17, and open the circuit through the wires 10, the binding posts 9 and the wires 15.

After the fire has been extinguished the apparatus may be reset by swinging the hold er 1 upwardly to its former position and supporting its raised end with a new fuse engaged over the hook 17.

From the foregoing description it is apparent that I have provided an apparatus embodying the advantages above pointed out, and while I have shown and described one form of the invention I reserve all rights to such changes and modifications as properly fall within the spirit and scope of the invention as claimed.

I claim:

In a fire alarm, a thermal switch consisting of a rightangular support, a semitubular holder pivotally connected at one end to the lower end of said support, a hook at the opposite end of said holder, a hook on the upper portionofthe support, afusiblelink connected to said hooks for supporting the holder in an upwardly inclined position, a container carried by and having its lower portion inclosed in said holder and provided with a liquid conductor, contacts projecting into one end of the container which are covered by said conductor when the holder is held in upward- 1y inclined position, and contacts projecting into the opposite end of said container which are engaged bv the conductor when the holder swings downwardly on destruction of the fusible link.

HENRY TRICE MITCHELL.

Images