US2898426A - Fire alarm - Google Patents

Description

Aug. 4, 1959 Filed June 2'7, 1958 A. ROBBINS FIRE ALARM 2 Sheets-Sheet l Asfif/no Robbins INVENTOR.

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A. ROBBINS FIRE ALARM 2 Sheets-Sheet 2 Filed June 27, 1958 R. m NE 3 R F ,m M Z aw mv 0 Mat United States Patent FIRE ALARM Astifino Robbins, Bellbrook, Ohio, assignor of fifty percent to W. J. Amburgey, Means, Ky.

Application June 27, 1958, Serial No. 745,098

1 Claim. (Cl. 200-142) This invention relates to alarms and more particularly to a device for signalling audibly and/or visually when a fire starts in any type of building.

An object of the invention is to provide a mechanically simplified but very effective alarm for a building, the alarm having a unique trigger mechanism sensitive to the first outbreak of the fire in order to close an electrical switch that completes a signal circuit.

A further object of the invention is to provide a highly sensitive alarm for signalling quickly at the beginning of the fire, the alarm device having a control box with highly flammable material therein and a burnable element in the control box that deteriorates very quickly enabling a spring to close an electrical switch so that the signal can be given. The control box and its contents respond very quickly to a fire condition and with a high degree of dependability and certainty.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of an alarm control that is constructed in accordance with the invention.

Figure 2 is a perspective view of the control of Figure 1.

Figure 3 is a sectional view taken on the line 3--3 of Figure 1.

Figure 4 is a cross-sectional view taken on the line 44 of Figure 3.

Figure 5 is a diagrammatic view showing the wiring connected with the control of Figure 1 in a typical signal circuit.

In the accompanying drawings there is a control that constitutes a part of a fire alarm whose typical electrical circuit 12 is shown in Figure 5. The electrical circuit is simplified, being a two wire system extending from a source of electrical potential and having control 10 in series with a siren 14. The siren is only one of numerous audible and/ or visual devices that can be operated by the circuit 12.

Control 10 is made of a casing 14 having side walls, a top wall 16 and a bottom wall 18 connected together by bolts 20. The top and bottom walls are preferably made of non-burnable material, such as asbestos impregnated board so that the switch 24 in the control box is protected from the fire. Switch 24 consists of a fixed contact point 26 on a conductive bar 28, the latter riveted or otherwise secured to the bottom Wall 18 and passing through an opening 30 in one of the side walls of the easing 14. A binding post 32 is at the end of the conductive bar 28 on the exterior of casing 14 and is adapted to connect in the circuit 12. The movable contact point 34 is attached to an end of a conductive spring metal bar 36 whose end is attached to conductive bar 38, the latter riveted or otherwise secured to the bottom 18 of the casing 14. Conductive bar 38 passes through an opening 40 in a wall of the casing 14 and has a binding post 42 on the exterior of the casing and to which a conductor in circuit 12 can be secured.

Switch 24 is held normally open by a structure in control box 44. The control box is made of a small casing attached to the top wall 16 and having a copious supply of highly flammable substance 46 therein, such as phosphorus or any other pyrotechnic material. A plurality of fuses 48 of the type having a substance of gunpowder grain within a thin flammable and flexible tube, are attached to the walls of the control box, terminating in a flammable fuse cap 50 fixed in an opening in the walls of the control box 44. Any number of such caps and fuses 48 can be attached to the control box depending on the size of the area that is to be monitored and controlled by control 10. The fuses 48 are extended to various judiciously selected points in the building that is being pro tected.

In addition, there is at least one pressure sensitive cap 52 in one wall of the box 44. The pressure sensitive cap 52 is adapted to open to assure that combustion will be supported in control box 44, and the cap can be made of a ring of metal with a diaphragm across it or an easily crushed wall, such as wax, paper, etc. extending thereacross.

The control structure for holding switch 24 in the open position consists of a fusible bar 56 mounted on spaced stanchions 58 and 60 attached to wall 16 and contained in box 44. A further fusible rod 62 is attached to bar 56 and has one end secured to bar 36 with a spring 66 concentrically disposed thereon. The spring reacts on the inside surface of wall 16 and seats on bar 36. The spring is held in the compressed state by rod 62.

In operation, as soon as the substance 46 becomes ignited, the rod 62 deteriorates, burns or otherwise loses its strength enabling the stored potential energy in spring 66 to be converted to kinetic energy, forcibly pushing the switch arm, consisting of bar 36 and contact point 34, to the switch closing position at which contacts 34 and 26 touch each other (see dotted line representation in Figure 3). This closes the circuit 12 so that a signal can be given.

The substance 46 is ignited by the ignition of one or more of the caps 50, and these ignite by having one or more of fuses 48 become lit.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

In a fire protective device, a control comprising a casing, a normally open switch in said casing and including a fixed contact and a movable contact, a spring reacting on said movable contact and holding said movable contact spaced from said fixed contact, means including a heat sensitive member for holding said spring under a spring load, a box connected with said casing and in which said member is at least partially disposed, a quantity of flammable substance in said box and in the presence of said member, at least one flammable fuse connected with said box and adapted to be located in the area that is fire protected whereby upon ignition of said fuse said substance becomes ignited in order to subject said member to heat and thereby release said spring so that said switch is moved to the closed position, at least one pressure sensitive member in said box adapted to be ruptured by pressure in order to admit air to said substance to support said combustion.

References Cited in the file of this patent UNITED STATES PATENTS Bailey Sept. 26, 1916 Torchio Sept. 4, 1917 Mathisen Jan. 29, 1946 Colardo Mar. 8, 1949 Mullally May 15, 1956

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