US3015811A - Portable fire alarm unit - Google Patents

Description

Jan. 2, 1962 R. RUBIN 3,01

PORTABLE FIRE ALARM UNIT Filed March 9, 1959 g 54 52 Fig. 2

3 P lB L as INVENTOR. LEONARD R. RUBIN M. SLJML United States Patent 3,015,811 PORTABLE FIRE ALARM UNIT Leonard R. Rubin, Wynnewood, Pa., assignor to Harry Rubin & Sons Inc., Philadelphia, Pa., a corporation of Pennsylvania Filed Mar. 9, 1959, Ser. No. 797,958 2 Claims. (Cl. 340-227) It is another object of-the present invention to provide a self-contained fire alarm unit which can be easily mounted on a wall, ceiling, or other surface of a room without the necessity for-electric wiring or the need of special tools or special skill.

It is still another object of the present invention to provide a portable fire alarm unit which is of simple constructionso that the batteries -for operating the unit can be easily and quickly replaced when necessary.

It is a further object of the present invention to provide a portable fire alarm unit which can be easily tested from time-to-time to determine whether the unit is in good operating condition.

Other objects will appear hereinafter.

For the purpose of illustrating the invention there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is a perspective view of the portable fire alarm unit of the present invention mounted on a wall or like surface.

FIGURE 2 is a sectional view, partly in elevation, of the portable fire alarm unit of the present invention.

FIGURE 3 is an elevational view taken along line 33 of FIGURE 2.

Referring initially to FIGURE 2, the portable fire alarm unit of the present invention is generally designated as 10.

Fire alarm unit 10 comprises a hollow, cylindrical, metal casing 12 having a bottom wall 14. The top end portion 16 of the casing 12 is flared radially outwardly, and is threaded on its external surface. Casing 12 has a keyhole slot 18 therethrough just below the flared top end portion 16 of the casing 12. A doubleheaded, metal contact 20 extends through the center of the bottom wall 14 of the casing 12, and is secured to the bottom wall 14. A bushing 22 of an electrical insulating material fits between the contact 20 and the bottom wall 14 so as to electrically insulate the contact 20 from the bottom wall 14. A headed, metal pin 24 extends through the bottom wall 14 spaced radially from the contact 20. A bimetal switch arm 26 is secured at one end to the end of the pin 24 which is outside the casing 12. Switch arm 26 extends across the contact 20. A contact button 27 is secured to the outer end of the switch arm 26 in alignment with the contact 20. Washers 28 of electrical insulating material surround the pin 24 between the bottom wall 14 and the switch arm 26. the switch arm 26 from the bottom wall 14 a distance so that the switch arm 26 is normally spaced from the contact 20.

A pair of standard 1.5 volt dry cell batteries 30 and 32 are mounted one above the other in the casing 12. The batteries 30 and 32 are arranged in series with the bottom battery 30 seated on the contact 20. An electrically actuated alarm device 34 is mounted in the top end por- Washers 28 space tion 16 of the casing 1 2. Alarm device 34 may be of any well known sound producing type, but preferably comprises an electric horn. The metal casing of the alarm device 34 has an annular flange 36 which is seated on the top end of the top portion 16 of the casing 12. A metal spring contact 38 is secured to the alarm device 34 by a screw 40. Washers 42 and 44 of electrical insulating material surround the screw 40 on opposite sides of the spring contact 30 to electrically insulate the spring contact 38 from the alarm device 34. Spring contact'38 engages the top terminal of the battery 32 with sufiicient pressure to hold the battery 32 tightly against the battery 30, and the battery 30 tightly against the contact 20. A wire 46 electrically connects one side of the sound producing mechanism of the alarm device 34 to the spring contact 38. The other side of the sound producing mechanism of the alarm device 34 is internally connected to the casing of the alarm device 34, which in turn is electrically connected to the switch arm 26 through the casing 12.

A cap, generally designated as 48, is secured to the top end portion 16 of the casing 12, and extends across the open end of the casing 12. Cap 48'comprises a cylindrical rim 50, anda cover 52. The rim 50 of cap 48 is internally threaded to match the external threads on the top end portion 16 of the casing 12. The cover 52 of the cap 48 has a flat peripheral portion 52a which is secured to the rim S0, and a raised central portion 52b. The raised central portion 52b of the cover 52 of cap 48 has a plurality of holes 54 therethrough. The cap 48 is secured to the casing 12 by threading the rim 50 around the top end portion 16 of the casing 12 until the peripheral portion 52a of the cover 52 of cap 48 engages the top surface of the flange 36 of the alarm device 34. Thus, the alarm device 34 is securedly mounted to the casing 12.

The fire alarm unit 10 of the present invention is used in the following manner:

As shown in FIGURE 1, the fire alarm unit 10 is mounted on a nail or hook 56 secured to a wall 58 by inserting the outer end of the nail or hook 56 through the keyhole slot 18 in the casing 12 of the fire alarm unit 10. The fire alarm unit 10 is thus supported on the wall 58 with the cover 52 of the cap 48 facing upwardly, and the bottom wall 14 of the casing 12 facing downwardly. Since the fire alarm unit 10 is self-contained, it can be easily and quickly mounted anywhere in a room without the necessity for special electrical wiring or the need of special tools or special skill. Also, since the fire alarm unit 10 is relatively small and compact, it can be easily carried from place to place if necessary.

In the event of a fire, the heated air from the fire heats the bimetal switch arm 25 so that the switch arm 26 moves the contact button 27 into engagement with the contact 20. This completes the electrical circuit through the batteries 30 and 32 and the alarm device 34 so that the alarm device 34 is operated to sound an alarm signal. After the fire has been extinguished, and the air around the fire alarm unit 10 has cooled down, the switch arm 26 will return to its normal position with the contact button 27 spaced from the contact 20.

To insure that the fire alarm unit 10 is always in good operating condition, it is desirable from time-to-time to test the fire alarm unit 10, particularly to determine whether the batteries 30 and 32 have suflicient voltage to operate the alarm device 34. This can be easily ac complished without the necessity of removing the fire alarm unit 10 from the wall 58 by merely pressing the contact button 27 against the contact 20 to complete the electrical circuit through the batteries 30 and 32 and the alarm device 34. When the pressure applied to the conthe casing 12 and replaced with fresh batteries.

tact button 27 is released the resiliency of the switch arm 26 automatically moves the contact button 27 away from the contact 20. In the event that the batteries 30 and 32 become worn out, they can be easily replaced by removing the cap 48 and lifting out the alarm device 34. The batteries 30 and 33 can then be removed from Since there are no wires permanently connecting the alarm device 3.4 with the batteries 30 and 32, and with the easing 12, the batteries 30 and 32 can be easily replaced without the need of any special tools or special skill.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

I claim:

1. A fire alarm unit comprising a hollow metal casing,

a contact extending through and secured to said casing,

means electrically insulating said contact from said casing, a bimetal switch arm mechanically and electrically secured to the outside of said casing, said switch arm extending across and normally spaced from said contact,

batteries in series within said casing, one of said batteries being in direct abutting electrical engagement with 4 ing, said resilient contact being electrically connected to said alarm device, and at least one perforation in a portion of said casing to admit audible signals from said alarm device.

2. A fire alarm unit in accordance with claim 1 wherein said means for mechanically and electrically securing said alarm device includes a removable cover on said casing, said alarm device having a radially outwardly extending flange of sufiicient size so that said flange may be clamped to said casing by said removable cover, and

said cover being the portion of said casing having the perforation to admit audible signals from said alarm device.

References Cited in the file of this patent UNITED STATES PATENTS 1,562,574 Maud Nov. 24, 1925 2,289,128 Kopf July 7, 194-2 7 2,446,794 Thornton Aug. 10, 1948 2,514,807 Shaw July 11, 1950 2,786,195 Colette Mar. 19, 1957 2,809,368 Ehlers Oct. 8, 1957 2,816,280 Detweiler Dec. 10, 1957 2,819,367 Ouellette Jan. 7, 1958 2,832,949 Pivetz Apr. 29, 1958 2,911,637 Wortmann Nov. 3, 1959 2,916,915 Burgert Dec. 15, 1959 2,954,548 I Gould Sept. 27, 1960

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