US2421915A

US2421915A - Fire alarm

Info

Publication number: US2421915A
Application number: US613633A
Authority: US
Inventors: Tousignant Joseph Wilfrid
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-08-30
Filing date: 1945-08-30
Publication date: 1947-06-10
Anticipated expiration: 1964-06-10

Description

Juhe 10, 1947.

J. w. TOUSIGNANT FIRE ALARM Filed Aug. 30, 1945 Patented June 10, 1947 UNITED STATES PATENT OFFICE FIRE ALARM Joseph Wilfrid Tousignant, Plattsburg, N. Y. Application August 30, 1945, Serial N0. 613.633

6 Claims. 1 The present invention pertains to a novel fire alarm wherein the alarm circuitis closed through the unequal expansion of a pair of wires. The

- principal object of the invention is to provide a simple and inexpensive device of this character operating on the stated principle.

Another object is to provide such a device wherein expansion of the wires due to a rise in the climatic temperature does not sound the alarm.

In the accomplishment of these objects the device comprises a pair of parallel wires, one of which is shielded in a perforated tube. Both wires have one end connected to a lever mounted in the tube near one end thereof and their remaining ends fastened at relatively fixed points at the remote end of the tube. The wires are joined intermediate their ends by a conducting clip passing through one of the apertures in the tube. The clip carries a contact finger cooperating with a normally spaced contact finger disposed therebeneath and fastened on the tube but insulated therefrom. The insulated finger is connected into the circuit of the alarm which also includes the clip and a portion of the external wire. As stated, the circuit is normally open at the contact fingers.

On sudden rise of temperature, the external or exposed wire expands mor rapidly than the wire shielded within the tube. Consequently the shielded wire is tensioned and pulls down the clip and its contact finger engages the fixed finger, thereby completing the circuit. During slow temperature changes, however, the shielded Wire is heated through the apertures in the tube at substantially the same rate as the exposed wire. A spring drawing on the aforementioned lever maintains the wires in a taut condition, with the result that there is no displacement of the clip and finger carried thereby.

The invention is fully disclosed by way of example in the following description and in the accompanying drawings in which:

Figure 1 is a, longitudinal section of the device;

Figure 2 is a side elevation;

Figure 3 is a section on the line 33 of Figure 1;

Figure 4 is a detail perspective view, and

Figure 5 is a corresponding cross section.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figure 1 is shown a suitable support I, such as a ceiling, from which the device is supported by a, pairof brackets 2. Between the brackets is mounted a tube 3 having a series of apertures I for a purpose that will presently by described. Near one end of the tube is mounted a U-shaped arm or lever 5 extending transversely of the tube, as shown in Figure 3, and having one of its legs 6 pivotally supported in the tube. The other leg 1 is somewhat shorter and extends into one of the apertures '4. A thermally expansive wire 8 has'on'e end fastened to the swinging leg I of the member 5 and its opposite end fastened at 9 to'the opposite bracket 2, the wire being disposed externally of the tube 3, as shown inFigures l to 4.

' A similar wire 18 is disposed within the tube and also has one end fastened to the free or swinging leg 1 of the lever 5. In the opposite end of the tube 3 is pivotally mounted a, bell crank lever I I to which the other end of the wire 10 is fastened. The tension of the wire can be adjusted by a set screw 12' threaded in the tube and bearing on'one leg of the bell crank lever. At th opposite 'end of the tube, a coil spring 13 has its ends attached respectively to the swinging leg 1 and to the adjacent bracket 2, drawing on the leg '1 to maintain the Wires in a. taut condition.

A clip l4 connects both wires '8 and I2 substantially at their mid-points by passing through one of the apertures 4. A contact finger 15 extends laterally from the clip externally of the tube 3. Adjacent to the finger l5, anoth'er contact finger I6 is fastened to the tube 3 in a position to lie perpendicular to the finger [5. The contact i6 is insulated from the tube 3 and is spaced from the finger 45 in the normal position of the device, as shown in Figure 2.

At a suitable location on the tube 3 are mount- 'ed two binding posts l1 and I8 insulated from each other. The contact I8 is joined to the post H by a, conductor l9. To the post 11 is also attached a conductor 20 comprised in an alarm circuit. The other side of the circuit is represented by a conductor 22 fastened to the post l8 and grounded if the alarm device is also grounded.

In the operation of the device a gradual rise of temperature due to climatic conditions does not affect the alarm circuit which is normally open. This is due to the fact that the Wire 10, although shielded by the tube 3, is heated at the same slow rate through the apertures 4 as the exposed wire 8 and, since the wires expand equally and the slack is taken up by the spring I3, the position of the clip l4 and the contact arm 5 is not changed. However, in a sudden rise of temperature due to fire, the wire 8 expands more rapidly than the wire l0. Consequently the wire 8 is pulled down by shielded wire l tensioned by spring [3 as shown in the dotted line position shown in Figure l, bringing the finger it into contact with the finger IS. The alarm circuit includes the tube, which is not insulated from the post !8, and also the nearer bracket 2, the portion of the wire 8 between the bracket and the clip l4, and the clip itself. Consequently, the engagement of the contacts I5, l6 closes the alarm circuit.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various alterations in the details of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim as my invention is:

1. A fire alarm comprising an apertured tube, a lever mounted near one end of said tube, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube, another wire disposed Within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the apertures of said tube, a contact finger extending from said clip, another contact finger mounted on said tube below the first finger and normally spaced therefrom.

2. A fire alarm comprising an apertured tube, a lever mounted near one end of said tube, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube, another wire disposed within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the apertures of said tube, a contact finger extending from said clip, another contact finger mounted on said tube below the first finger and normally spaced therefrom, and a spring bearing on said lever in the direction to tighten said wires.

3. A fire alarm comprising an apertured tube, r

a lever mounted near one end of said tube, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube,

another wire disposed within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the apertures of said tube, a contact finger extending from said clip, another contact finger mounted on said tube below the first finger and normally spaced therefrom, a pair of binding posts mounted on said tube and insulated from each other, a conductor joining the second finger to one of said posts, and conductors attached to said posts and adapted for connection to a current source and an alarm.

4. A fire alarm comprising an apertured tube, a lever mounted near one end of said tube, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube, another wire disposed within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the amrtures of said tube, a contract finger extending from said clip, another contact finger mounted on said tube below the first finger and normally spaced therefrom, a spring bearing on said lever in a direction to tighten said wires, a pair of binding posts mounted on said tube and insulated from each other, a conductor joining the second finger to one of said posts, and conductors attached to said posts and adapted for connection to a current source and an alarm.

5. A fire alarm comprising an apertured tube, U-shaped lever having one leg pivot-ally mounted in said tube near an end thereof, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube, another wire disposed within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the apertures of said tube. a contact finger extending from said clip, an other contact finger mounted on said tube below the first finger and normally spaced therefrom.

(i. A fire alann comprising an apertured tube, a U-shaped lover having one leg pivotally mount ed in said tube near an end thereof, a wire having one end fastened to said lever and the other end fixed near the remote end of the tube, said wire being disposed externally of said tube, an-

' other wire disposed within said tube and having its ends fixed respectively to said lever and near the remote end of said tube, a conductive clip joining said wires intermediate their ends and passing through one of the apertures of said tube, a contact finger extending from said clip, another contact finger mounted on said tube below the first finger and normally spaced therefrom, and a spring bearing on said lever in a direction to tighten said wires.

JOSEPH W ILFRID TOUSIGNANT.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 1,145 Australia Mar. 25, 1926