US2804609A - Fire alarm - Google Patents

Description

Aug. 27, 1957 s. SUSSMAN 2,804,609

FIRE ALARM Filed April 5, 1955 Hes.

IN VENTOR. SY SUSSMAN BYMWWY United States Patent FIRE ALARM- Sy Sussman, Brooklyn, N. Y.

Application April 5, 1955, Serial No. 499,374

2 Claims. (Cl. 340-227) This invention relates to improvements in electrically operated alarm devices wherein actuation of a signalling unit is initiated by a thermally sensitive switch.

In-the conventional alarm devices of the above mentioned species, a thermally sensitive element causes the closure of a normally open switch upon the occurrence of ambient temperatures of specific magnitudes. Closure of the switch energizes a circuit which controls the operation of a buzzer, bell, gong or the like resulting in the emission of an audible signal.

It is the primary object of this invention to incorporate the components of the above described system into an economical, compact, self-contained unit which can be rapidly installed in any desired location in which an ordinary electric outlet is available.

Another object of this invention is the provision of a solenoid controlled buzzer unit which. can be mounted compactly within a housing wherein a portion of the housing coacts with the buzzer to augment the quantity of emitted sound.

A further object of this invention is the provision of a self-contained electric alarm device comprising a housing, a buzzer, and a thermally sensitive switch which causes buzzer actuation upon the occurrence of predetermined ambient temperatures, wherein the device is operatively installed by merely plugging the casing into an electric outlet.

A still further object of this invention is the provision of an electrically operated alarm unit adapted to be plugged into an electric outlet which will emit a loud audible signal upon the occurrence of predetermined ambient temperatures.

A still further object of this invention is the provision of an improved buzzer unit having a buzzer reciprocally mounted between an actuating solenoid and a supporting plate whereby the buzzer strikes the solenoid core and the plate alternately to produce a loud continuous sound.

A still further object of this invention is the provision of a buzzer adapted to reciprocate at a high frequency.

Further objects and inventive features of the device will become more apparent from the following detailed description when read in conjunction with the attached drawings in which:

Figure 1 is a top plan view of an assembled unit incorporating the invention;

Figure 2 is a top plan view of the unit with the housing removed showing the component assemblies comprising the invention;

Figure 3 is a side elevational view of the assembled unit shown in Figure 1;

Figure 4 is an end view of the unit with the housing removed, partly broken away;

Figure 5 is a rear elevational view of the unit with the housing removed;

Figure 6 is a perspective view of the buzzer assembly; and

Figure 7 is a circuit diagram.

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Referring now to Figures 1 and 2, a complete assenlbly of the alarm unit is depicted comprising a base plate 10 and a housing 11 having a peripheral flange 12 which is removably secured to the base plate 10 by such conventional means as the bolts 13. A central compartment 14 encloses the internal components of the device which are better seen in Figure 2. A port 15 is provided in a side wall of the compartment 14 exposing a thermally sensitive element within the compartment to the temperature of the atmosphere surrounding the housing.

The internal components of the alarm unit, as seen in Figures 2, 4 and 5, generally comprise a solenoid assembly 16, .a buzzer assembly 17, and a switch assembly 18 all mounted on the inner surface of the base plate 10, in a compact arrangement and occupying a minimum of space. Each of these assemblies are of novel design thereby making possible the resulting compact self-contained unit.

In Figures 2, 4 and 5 the solenoid assembly 16 is seen to comprise an E-shaped permeable core 19 having outer parallel legs 20 and a center leg 21 parallel to the legs 20. A solenoid coil 22 is secured to and wound in the conventional manner about the center leg 21 and is connected to a source of electricity by the lead wires 23 and 24. The outstanding ends of the legs 20 and 21 project beyond the corresponding end of the coil 22. The core 19 is mounted in a frame 25 which has a U- shaped cross-section and is crimped about the periphery of the core.1 9. Adjacent the ends of the legs 20 the frame 25 includes flanges 26 which extend at right angles to the legs and bear upon a pair of insulating gaskets 27. The flanges 26, the plate 10 and the gaskets 27 have aligned holes to receive conventional fastening means which secure the frame to the plate 10. The ends of the legs 20 and 21 are spaced from the plate 10 for the insertion therebetween of the buzzer assembly (Figure 3).

As is seen in Figure 5 the buzzer assembly 17 comprises a thin highly resilient and durable rectangular spring plate 28, to which is secured at one end a head 29. Although the plate 28 is preferably formed of a beryllium copper, other materials having equivalent properties may be used. The head 29 which is U-shaped is secured to the plate 28 by press fit, brazing, or the like and is fabricated from a magnetic substance such as iron, steel, nickel or the like. The end remote from the head 29 is provided with holes 30 to receive conventional means 31 for mounting the plate 28 on the plate 10. In Figure 4 the buzzer assembly 17 is shown in its operative position relative to the solenoid assembly.-

The end of the plate 28 which is secured to the base plate 10 is spaced from core legs 20 and 21, whereas the head 29 underlies the legs and is midway between the legs and the plate 10. Consequently when the solenoid periodically attracts the magnetic head 29, a vibration will be induced causing the head to alternately strike both the core legs and the base plate 10 causing thereby the emission of a loud audible signal.

As will be more fully described later, the solenoid is energized only when a thermally sensitive switch is in the circuit-making position. This switch is included in the switch assembly 18 (see Figure 2) which comprises an elongated insulator 32 secured to the base plate 10 parallel to and spaced from the core 19. A bimetallic bar 33 is secured at one end to the insulator 32 and the other end 34 is normally spaced from the insulator. The means for securing the bar end 35 to the insulator 32 also electrically connects the bar to the lead wire 24 via a terminal post 36. Lead Wire 24 is connected to one lead of the solenoid coil. The free bar end 34 is normally spaced from an electrical contact 37 which is electrically connected to wire 38 by means of terminal post 39. The other end of lead wire 38 is connected to Patented Aug- 27, 1957 V plug connection 41. Solenoid lead wire 23 is connected to the other plug connection 42. Plug connections 41 and 42 are integrally connected to the plug prongs 43 and 44 which project through the base plate 10 to provide a means for connecting the alarm unit to an ordinary electric outlet (see Figures 4 and 5). It is apparent then, that when the bar end 34 engages the contact 37 a complete circuit will be formed enabling current to flow from plug 43 to plug 44 serially through the solenoid and the bimetallic bar 33. Thus the bar 33 provides a normally open switch in the electric circuit controlling the energization of the solenoid. The circuit is schematically represented by Figure 6 wherein S denotes the switch, E the source of current, M the solenoid, and B the reciprocable buzzer.

In operation the assembled unit is plugged into an outlet socket connected to a source of alternating current. Should the ambient temperature, due to fire or other causes, reach a predetermined magnitude, the bar 33 whichis exposed through port 15 to the ambient temperature, defiects sutficiently to engage the contact 37, thereby forming a complete circuit. Alternating current will then flow through the device to energize the solenoid in a sinusoidal fashion imparting periodic magnetic properties to the core '16. At a rate governed by the frequency of the current, the buzzer head will be alternately attracted to the core 16 and released. During the period of maximum attraction by the core, the buzzer head will strike the legs 20 and 21 and emit thereby an audible signal. When the magnetic force is insufficient to maintain contact between the core and the head 29, against the resiliency of the plate 28, the head 29 will spring back and strike the base plate emitting a further audible signal. Therefore when the circuit is made, the buzzer head 29 will oscillate alternately between the core. and the base plate generating a loud continuous signal. 7

It isto be noted that due to the specific designs of the buzzer and solenoid assemblies, the solenoid assembly can be operatively superimposed over the buzzer assembly thereby reducing the space requirements to a minimum. Moreover, the base plate, in addition to serving as a housing support for the various components, also functions as an anvil for the buzzer head providing thereby a greater quantity of sound emission. The vital components of the device are enclosed and protected from tampering by unauthorized persons and accidental damage.

It should be further noted that the switch assembly, due to the specific form provided herein, is conveniently located within the housing in relation to the other components without increasing materially the space demands.

Although the embodiment described hereinabove relates to a unit provided with a plug connection, the substitution of an extension cord is within the contemplated scope, of the invention.

In summary, the instant invention provides an alarm which isa complete compact unit, adapted for rapid installation involving minimum fabricating costs and capable of emitting a loud audible signal without significant deterioration of the buzzer assembly.

It should also be understood that although the embodiment disclosed herein is preferred, many changes involving size, shape, material and juxtaposition of parts can be affected without departing from the scope of the invention.

Having fully disclosed the nature of the invention, a grant of Letters Patent is solicited for the novelty as defined in the appended claims below:

1. A compact self-contained electric alarm unit comprising a base plate, a housing enclosure mounted on said. base plate, a solenoid assembly, a buzzer assembly and a switch assembly all mounted on the inner surface of said base plate, said solenoid assembly comprising an E-shaped permeable core having outer parallel legs and a center leg, a solenoid coil wound around and secured to said center leg, said coil having lead wires for connection to a source of electricity, a frame for securing said solenoid to said base plate, said frame retaining said solenoid so that said legs are positioned in spaced relation to said base plate, a buzzer assembly positioned in the space between said ends and said base plate, said buzzer assembly comprising a thin substantially rectangular plate of resilient material, a head of magnetically attractable material secured along one of the edges of said plate, said head comprising a U-shaped member encompassing said side edge, said plate being secured to said base plate along the opposing side edge thereof, said head being free for vibratile movement and being positioned in operative relation with respect to the ends of said core whereby upon the actuation of said switch assembly an alternating current may be applied to said solenoid coil whereby said solenoid attracts said head inducing a vibratory movement in said head and said plate and causing said plate to alternately strike the core legs and the base plate thereby causing the emission of a loud alarm signal.

2. A compact self-contained electric alarm unit com prising a base plate, a housing enclosure mounted on said base plate, a solenoid assembly, a buzzer assembly and a switch assembly all mounted on the inner surface of said base plate, said solenoid assembly comprising an E-shaped permeable. core having outer parallel legs and a center leg, a solenoid coil wound around and secured to said center leg, said coil having lead wires for connection to a source. of electricity, a frame for securing said solenoid to said base plate, said frame retaining said solenoid so that said legs are positioned in spaced relation to said base plate, a buzzer assembly positioned in the space between said ends and said base plate, said buzzer assembly comprising a thin substantially rectangular plate. of resilient material, a head of magnetically attractable material secured along one of the edges of said plate, said headcomprising a U-shaped member encompassing said side edge, said plate being secured to said base plate along the opposing side edge thereof, said head being free for-vibratile movement and being positioned in operative relation with respect to the ends of said core, said switch assembly comprising an elongated insulator secured to the base plate parallel to and spaced from said core, a bimetallic bar secured at one end to said insulator, the other end thereof being normally spaced from a terminal carried by said insulator said switch assembly being serially connected between a source. of alternating. current and said solenoid core and beingresponsive to a temperature above a predetermined value to close the. circuit therebetween, said switch; being normally open, said housing including a port adjacent to said switch whereby said switch is exposed to the ambient temperature of said housing and whereby upon the actuation of said switch assembly an alternating current may be. applied to said solenoid coil whereby said solenoid attracts said head inducing a vibratory movement in said head and said plate and causing said plate to alternately strike the core legs and the base plate thereby causing the emission of a loud alarm signal.

References Citedin the file of this patent UNITED STATES PATENTS 1,232,745 WOOd July 10, 1917 2,456,038 Young Dec. 14, 1948 2,611,016 Nuccio" Sept. 16, 1952

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