US3905027A

US3905027A - Anti-false fire alarm system

Info

Publication number: US3905027A
Application number: US536652A
Authority: US
Inventors: James Mcwilliams
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-12-26
Filing date: 1974-12-26
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

A fire alarm system for discouraging false alarms, including a fine-mesh cage with a gate, a conventional fire alarm box within the cage slightly modified by having a cam fixed inside the fire alarm box door and by having the bottom of the fire alarm box slotted, a cam follower lever extending through the slot and responsive to the cam when the fire alarm box door is opened, a simple and rugged interlock system co-acting with the cam follower lever to prevent the fire alarm box door from being opened until the cage gate is fully closed, and then locking the fully closed cage gate when the fire alarm box is opened, and a key-actuated release for the interlock system, located exterior to the cage; fail safe operation is provided by gravitation because of vertical component-orientation, should any of the elements of the system fail.

Description

United States Patent McWilliams Sept. 9, 1975 [54] ANTI-FALSE FIRE ALARM SYSTEM [57] ABSTRACT [76] Inventor: James McWilliams, Oak Hill Rd A fire alarm system for discouraging false alarms, in-

Baltimore, Md. 21239 cluding a fine-mesh cage with a gate, a conventional Filed: Dec. 26, 1974 fire alarm box within the cage slightly modified by Appl. No.: 536,652

Primary ExaminerHarold I. Pitts Attorney, Agent, or Firm lohn F. McClellan, Sr.

having a cam fixed inside the fire alarm box door and by having the bottom of the fire alarm box slotted, a

cam follower lever extending through the slot and responsive to the cam when the fire alarm box door is opened, a simple and rugged interlock system coacting with the cam follower lever to prevent the fire alarm box door from being opened until the cage gate is fully closed, and then locking the fully closed cage gate when the fire alarm box is opened, and a keyactuated release for the interlock system, located exterior to the cage; fail safe operation is provided by gravitation because of vertical component-orientation, should any of the elements of the system fail.

12 Claims, 6 Drawing Figures OPEN DOOR FOR FlRE FIG. 2

FIG. 3

FIG.4

ANTll-FALSE FIRE ALARM SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to fire apparatus and particularly to fire alarm systems for preventing false alarms.

In the prior art, various fire alarm systems have been disclosed which inhibit the turning in of false alarms by detaining the person actuating the alarm to make identification of the person verification of the cause of the alarm easier.

However, today, in spite of the very large numbers of false alarms turned-in in many areas, particularly in large cities, no alarm system of the type described has come into widespread use in the United States.

An apparent reason for this is that although detention-type fire alarm systems are known, the prior art systems are too elaborate and expensive to be installed in the thousands of locations where they would be ef* fective.

SUMMARY OF THE INVENTION Accordingly a principal object of the present invention is to provide an alarm system which will reliably but very economically detain the person turning in an alarm until identification of the person or verification of the cause of the alarm can be made.

Further objects of the invention are to provide an alarm system as described which requires a minimum of space, materials, and workmanship, which affords optimum visibility, which is simple, familiar and automatic in operation, which is attractive in appearance, and which is durable and easy to maintain.

In brief summary given for cursive description only, the invention includes in a preferred embodiment, an enclosure with a gate, any standard fire alarm box having a door and mounted within the enclosure, a linkage closing the gate and locking it on opening of the fire alarm box door, and a lock, preferably key-operated, accessible from the exterior of the enclosure, for opening the gate.

BRIEF DESCRlPTlON OF THE DRAWING The above and other objects and advantages of the invention will become more readily apparent on examination of the following description, including the drawings in which, like reference numerals referring to like parts:

FIG. 1 is an isometric view of the invention; FIG. 2 is a section adapted from 2-2, FIG. 1', FIG. 3 is a modified section adapted from 3-3, FIG.

FIG. 4 is a view like that of FIG. 2, showing another position of operation; and

FIGS. 5 and 6 are sections taken at 5-5, FlG. 2, showing two positions of operation.

DESCRIPTION .OF THE PREFERRED EMBODIMENT Referring in detail to the Figures, FlGv 1 is an overall view of the invention 10 showing the simplicity and economy of design, and that the operation is readily apparent to one who would turn in a fire alarm.

To actuate an alarm, the user simply enters openwork cage 14, which preferably is a l X 1 inch mesh or close mesh steel cage, through which fire alarm box 16 is visible from all sides, and closes the cage gate 18 behind him, then opens the door 20 on the fire alarm box. For reasons which will be seen, the fire alarm box door cannot be opened until the cage gate is shut completely.

Opening the door on the fire alarm box automatically locks the completely shut cage gate, and sounds the fire alarm by conventional means not further detailed but diagrammatically represented by plunger-switch 22 which closes when the fire alarm box door opens. The fire alarm box is preferably of the non-latching type.

Locking the cage gate is accomplished by cam 24 on the fire alarm box door which thrusts aside camfollower lever 26, bringing into play a simple but effective linkage held in first vertical casing or guide 28 near the gate, second vertical casing 30 on'the far side of the fire alarm box from the gate and parallel-spaced from the first vertical casing, and in horizontal casing 32 connecting lower portions of the vertical casings and passing proximately below the fire alarm box.

The cam actuated linkage retains the cage gate shut by means of cable 34 which passes over a fairlead or pulley 36 and downward into the vertical casing proximate the gate.

FIG. 2 illustrates in sectional view the position of the elements of the invention when the gate is open, and the fire alarm box door is shut, the normal or no-alarm position.

Cage gate 18 is open, holding square-section weight or slider 38 at the upward limit of travel in squaresection casing 28, preventing rotation as shown, with transverse aperture 40 in the slider upper end well above horizontal plunger 42, the first end 4211 of which terminates proximate the slider. Spring 44 urges the horizontal plunger away from the slider, and thus urges cam follower lever 26, which is integral with the slider, against cam 24.

Communicating slot 46 between the fire alarm box and the horizontal casing permits the necessary longitudinal motion of the cam follower lever, and is safely shielded from the weather by the alarm box.

Keep 48 is slidably retained in the second vertical casing which communicates with the horizontal casing and is urged downward against the second end 42b of the horizontal plunger by spring 50. This arrangement provides maximum strength, rigidity, and wear.

FIG. 3 illustrates in plan view the same operational position as FIG. 2 and better shows why the fire alarm box door cannot be opened until the gate of the enclosure is shut. Cam 24 extends inward as an integral part of the door 20, and has an arcuate cam-follower-lever engaging face, but the fire alarm box door swings about hinges 52 on an are a which causes the arcuate cam face to thrust-cam follower lever longitudinally away from it. In the position shown, the cam follower lever cannot yield, however, because the first end 420 of the horizontal slider is unable to pass through slider 38, and therefore the fire alarm box door cannot be opened to sound an alarm.

H6. 4 shows that closing the cage gate feeds cable over the pulley permitting the suspended heavy slider to descend to the lower limit, at which point the gate is fully closed and transverse aperture 40 in the slider aligns with the first end 42a of the horizontal plunger. Now the cam follower lever will yield, forcing the horizontal plunger first end into the slider aperture as the fire alarm box door opened.

As noted, opening the fire alarm box door sounds the alarm by conventional means diagrammatically indicated in the first Figure, and simultaneously locks the cage gate by means of keep 48 which descends behind the second end 42b of the horizontal plunger under the bias of spring 50, preventing the keep from rising. The fire alarm box door can be closed in this position but closing it does not release the occupant.

FIGS. 5 and 6 show how the occupant is released from outside the cage by key-actuation of camlock 54 with an eccentric bolt in housing 56 raises lug 58 integral with the keep raising the keep.

Key 60 is carried by police, firemen, and similarly authorized officials, who upon verifying the alarm, can release the cage occupant by raising the keep, permitting the spring bias of the horizontal plunger to retract it to the initial position, after which the cage occupant can at any time push open the cage gate.

It can be seen that by use of a simple, protective casing arrangement with two springs and two rods having short transverse projections, a perforate section of bar, a cable, a pulley, a cage with door, a slightly modified fire alarm box, and a lock and a key, essentially a dozen elements proeurable from standard stock almost anywhere, a simple rugged, clean cut, attractive looking mechanism of the type described is provided at very reasonable cost.

The interlock mechanism is very compact and largely self-contained, the size of the entire assembly need occupy no more than 4 square feet of sidewalk space, and can be easily lifted by two men and loaded or unloaded from a truck. On site. the cage is easily strapped or 0th erwise secured to a pole, or bolted to the sidewalk using expansion bolts.

Because of vertical orientation of the interlock components for the horizontal bar, bringing gravitational forces into play should an interlock component fail, in operation the device is virtually failsafe. Should the failsafe operation not be required in a particular application, the second vertical guide need not be vertical, but in any event is preferably vertical to provide this feature. Closing the gate cannot jam the interlock, because of the flexible cable. Should the keep spring fail, the keep will operate under gravity. Should the horizontal plunger spring fail, the plunger can be retracted by hand, using the cam follower lever, when the key-lock is actuated to raise the keep. Should the cable fail, the occupant is not trapped but instead can open the gate. However even if it were possible to cut the tempered high-alloy steel cable, a false alarm could not be turned-in, since the length of the slider relative to the casing prevents this. The length of the slider exceeds the distance from the casing bottom to the horizontal plunger, and the transverse aperture is misaligned with the plunger when the slider rests on the bottom of the casing, blocking the horizontal plunger.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be secured by United States letters patent is:

1. In an alarm system having an enclosure with a gate, an alarm within the enclosure, means for locking the gate in closed position on acuation of the alarm, and means for unlocking the gate from the exterior of the enclosure, the improvement Comprising: first and second vertical guides secured to the enclosure, a horizontal guide secured between portions of the vertical guides, an alarm box proximate the horizontal guide and having an opening communicating therewith, a slider associated with the first vertical guide, means for operatively connecting the slider with the gate for causing the slider to travel between a gate-open position and a gate-closed position, the slider having a transverse aperture therein in position for alignment with the horizontal guide at the gate-closed position, a horizontal plunger in the horizontal guide having first and second ends, the first end proportioned for entering the slider transverse aperture, means biasing the horizontal plunger away from the slider transverse aperture, the alarm box having a door with cam fixed thereon, the horizontal plunger having a cam follower lever positioned for operative contact with the cam through the alarm box opening, whereby the horizontal plunger first end is forced into the slider aperture on opening the door of the alarm box, a keep within the second vertical guide positioned to descend and contact a portion of the horizontal plunger and prevent retraction thereof from the slider aperture, locking the gate; and a lock operatively associated with the keep in position to raise the keep and release the horizontal plunger from the slider transverse aperture, releasing the gate.

2. In an alarm system as recited in claim I, the portion of the first vertical guide having connection to the horizontal guide being a mid-portion, and the gateopen position of the slider being at an upper portion of the travel thereof.

3. In an alarm system as recited in claim 2, the gateclosed position of the slider being at a lower end of the travel thereof.

4. In an alarm system as recited in claim 3, the means for operatively connecting the slider with the gate including an elongate flexible member.

5. In an alarm system as recited in claim 4, and a fairlead for the flexible elongate member positioned above the first vertical guide.

6. In an alarm system as recited in claim 5, the slider having a polygonal cross section, and the first vertical guide comprising a casing having a cross section fitting to that of the slider.

7. In an alarm system as recited in claim 6, the second vertical guide and the horizontal guide comprising casings.

8. In an alarm system as recited in claim 1, the alarm box being l cated above the horizontal guide, the horizontal guide comprising a casing, the cam follower lever projecting upward through said opening, and the cam projecting inwardly from the fire alarm box door.

9. In an alarm system as recited in claim 1, the portion of the horizontal plunger contacted by the keep being the second end thereof.

10. lnan alarm system as recited in claim 1, the enclosure comprising a substantially close-mesh steel cage.

11. In an alarm system as recited in claim 1, spring means biasing to keep towards the horizontal plunger, and said lock having an eccentric bolt contacting a lug on the keep in opposition to said spring means.

12. In an alarm system as recited in claim 1, the first vertical guide having a bottom, and the slider proportioned for resting on the bottom and blocking the horizontal plunger when the means for operatively connecting the slider with the gate fails to retain the slider.

Claims

2. In an alarm system as recited in claim 1, the portion of the first vertical guide having connection to the horizontal guide being a mid-portion, and the gate-open position of the slider being at an upper portion of the travel thereof.

3. In an alarm system as recited in claim 2, the gate-closed position of the slider being at a lower end of the travel thereof.

8. In an alarm system as recited in claim 1, the alarm box being located above the horizontal guide, the horizontal guide comprising a casing, the cam follower lever projecting upward through said opening, and the cam projecting inwardly from the fire alarm box door.

10. In an alarm system as recited in claim 1, the enclosure comprising a substantially close-mesh steel cage.