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Publication numberUS2999477 A
Publication typeGrant
Publication dateSep 12, 1961
Filing dateJun 9, 1959
Priority dateJun 9, 1959
Publication numberUS 2999477 A, US 2999477A, US-A-2999477, US2999477 A, US2999477A
InventorsPratt Edmund C, Pratt Verneur E
Original AssigneePratt Edmund C, Pratt Verneur E
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fire alarm
US 2999477 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Sept. 12, 1961 v. E. PRATT ETAL 2,999,477

FIRE; ALARM Filed June 9, 1959 2 Sheets-Sheet 1 y JNVENTORS 4C MWA/Em? .E Pff/277 [0MM/V0 C /Q/P/lrr 2 Sheets-Sheet 2 Sept. 12, 1961 v. E. PRATT ETAL FIRE ALARM Filed June 9, 1959 2,999,477 rma ALARM Verneur E. Pratt, 2000 Skyline Drive, Fullerton, Calif., and Edmund C. Pratt, 3591/2 West Road, La Habra,


Filed June 9, 1959, Ser. No. 819,163 7 Claims. (Cl. 116-406) "Ihis invention relates to alarms and in one of its more particular aspects to lire alarms.

Many types of alarms have been proposed and/or used in the past. Electrical alarms are the most advanced type of Valarm particularly in the tire alarm field. Electrical alarms, however, are relatively expensive and have the disadvantage that they are rendered inoperative by loss of electrical power and which power loss is usually a result of the very tire for which the alarm was installed to detect. As a result, alarms having selfcontained power sources, such as spring wound alarms have been proposed to avoid both the diliiculties and the expense of the electrical alarms.

l'Ihis invention relates to an improved and inexpensive and easy to install alarm which is of the self-contained power type and of a light weight construction for use in houses, offices, industrial plants, warehouses, boats and the like. rThe alarm is substantially housed within the bell therefor and has its operating mechanism further encased to allow the alarm to be used in any environment, including a corrosive environment. This encasing is further arranged to permit the operating mechanism to be free from tampering or being rendered inoperative by foreign matter such as bugs, insects, and the like accumulating therein.

The invention is best described in its embodiment as a re alarm and which re alarm includes a cup-shaped bell deiined to house the complete mechanical operating mechanism within the bell. The heatsensitive element for detecting the preselected increase in ambient temperature, such as produced by a fire, is mounted on the outside of the bell in a position to be readily visible as well as accessible. The self-contained operating mechanism for the alarm is encased within a sub-assembly dened to completely seal ott the mechanism. The mechanism is powered by means of a spring motor arranged to provide a continuous driving action for a hammer to sound or ring the bell.

In one specitic embodiment of the invention spring means in the form of a constant tension spring is normally wound on a rotatable storage drum and connected to a rotatable drive drum to 'oe wound thereon whereby the stored energy thereof is utilized to continuously drive ahammer with a constant torque for sounding the alarm. The spring is wound on the drive drum by manually winding the spring thereon through the provision of a winding knob accessible at the back of the alarm.` The storage and drive drums are both rotatably mounted on shafts with the shaft for the latter drum being provided with a drive gear to be rotatably responsive to the unwinding of the spring from the drive drum and thereby through suitable gearing transmit this driving action to the hammer for sounding or ringing the bell.

The hammer is rotatably mounted to be continuously responsive to the driving action of the gearing and is constructed and arranged to thereby continuously sound the bell at substantially the same sound level. The hammer includes an arm having heads very loosely mounted at opposite ends thereof. The hammer is mounted on the subassernbly but outside of the sealed interior or chamber housing the operating mechanism proper and which sub-assembly is defined to provide a hammer chamber wherein the hammer rotates. The bell is pro- Patented Sept. 12, 1961- arranged hammer at a high rotary speed to produce a` loud and distinctive ringing sound and which ringing4 sound is easily distinguished from the usual environmental noises or sounds.

he lhigh rotary driving speed of the hammer is' achieved by the provision of step-up gearing arranged intermediate the drive gear and the driven shaft mountingV The driving action of this transmissivegearing is selectively controlled by a control means in-Y' the hammer.

cluding a control member engageable and disengageable with the gearing and which locks or unlocks the spring wound on the drive drum. This control operation is.

aected, in this instance, through the provision of a stopmember or lip dened on the face of a transmitting gear 'to restrain the rotation thereof.` This control member is further arranged to extend outwardly oiI the subassembly and through the bell proper where it cooperates with a latch which may be centrally mounted on thel outside ot the bell. The operation of the latch governs; whether the spring is locked or unlocked. When the alarm is to be used for detecting tires the latch may be in the form of a heat responsive link arranged to deform at a preselected temperature and allow the control member to disengage from the gearing and thereby allow the spring to unwind for sounding the alarm.

The alarm also includes means for visually indicating when the alarm is not in operating condition and the spring should be wound onto the drive drum. This indicating means measures the length of spring wound on the storage drum and signals the need for a rewinding operation when all of the spring is wound on the storage drum whereby the alarm is inoperative. This indicating means comprises a spring biased arm engaging the outer wrap of the spring on the storage drum and mounting aliag which is rotatable into a visible position when the spring is stored on the storage drum and is in la nonf visible position within the bell when substantially all of the spring is stored on the drive drum. This indicating means signals the operating condition of the alarm independently of the condition or position of the heat responsive element which may be readily detected by an observer.

The invention is explained in more detail in the following description and in the accompanying drawings, in which: l

FIG. 1 is a side elevational View, with the bell partially broken away and the exposed control mechanism shown in cross-section of the alarm embodying the in-` vention shown mounted in a horizontal position;

FIG. 2 is a bottom plan view of the alarm of FIG. l, with the back cover removed, and showing a portion of the bell and the positions of the visual indicating means and of the hammers in dotted outline;

FIG. 3 is a partial, cross-sectional view taken along the line 3 3 of FIG. 2 with the spring removed from the drive drum, the bell broken away and the back cover shown in position; and

FIG. 4 is a sectional view, with parts in section md' parts broken away, taken along line 4 4 of FIG. 3.

Now, referring to the drawings, the alarm 10 will be described in more detail. The alarm 10 comprises a bell 12 housing a sub-assembly 14 for the operating mechanism and which sub-assembly is substantially housed the bell. 'Ihe sub-assembly 14 is dened to mount essere??? atwinding knob 16 anda visualindicating means or tiag. 18 in a manner to render them readily accessible when the alarm is unmounted. A hammer 17 for sounding thefbell 121 protrudes `from one side of the sub-assembly 14. Thev sub-assembly'lll and the bell 12 are intercon-v nected by means including control operating means arranged on the exterior of the bell 12 to allow the bell to be either manually or ztutonnaticallyV sounded depending; on the application thereof. When the alarm is to be used as a". re' alarm, the control. operating means includes a heat sensitive latch 20. The alarm 10 is controllably locked or unlocked to an operating relationship by meansof the-heat sensitive element 20.

The bell 12 is of a cup-shaped construction with. a skirt of suicient length to house the sub-assembly 14 almost completely therein. The bell 12 is constructed of a material that will provide a loud sound upon being struck. The bell 12 includes a sounding or striking pin 122L formed integral with the bell or irrnly fastened thereto. The provision. of the striking pin 1291 allows the bell 12 tov be sounded without striking the bell proper as will become more apparent hereinafter. A central aperture for the b ell 12 is deiined to receive an operating control member or pin 22 cooperating with the heat sensitive element aswill ybe more evident hereinafter.

The sub-assembly 1d is 'arranged to house the operating mechanism for the alarm lil in a sealed chamber defined by a substantially cup-shaped member 24 and a cover member 26. cooperating therewith. The cup-shaped member 24 is of a smaller diameter. than the inside diameter oi thev bell. 12 to allow the sub-assembly 14 to be readily positioned therein. The cup-shaped member 24 is also provided with a central aperture to slidably receive thev operating control member. 22 when it is axially aligned with the bellv 12.

The sealed chamber for the operating mechanism is defined by enclosing the cup-shaped member 24 with. the cover 26 and which cover carries a plurality of securing pins 26 disposed at spaced points around its outer periphery. The cup-shaped member 24 is also provided. with sockets 24a to receive the pinsZoc. The ends 0f the pinsV 26 are of a, length to protrude from the sockets 24a and may be peened over to connect the cup-shaped member 2d and cover 26. The thus arranged cover 26 closely fits the cup-shaped member. 24 to enclose the latter for sealing the operating mechanism proper, except for an opening through which only the hammer 1.7 protrudes. The operating mechanism, however, is sealed from this. hammer opening by the provision of a mounting plate 28.

n The mounting plate 28 is flush with the outer periphery of the cupehaped member 24. The mounting plate 28 is. mounted in this fashion through the provision. of three feet or posts similar to the one identilied by the reference character 24h integral with the; member 24 and defined to receive and support the plate 28. The three supporting feet formed have pins 24C at the ends to be received in the openings 28a for the mounting plate 28 and which pins secure the mounting plate to the cup-shaped member 24 when their ends arev suitably peened. The mounting plate 28 not only seals off. tlre'operating mechanism Within the chamber but also cooperates with an upraised portion 26a defined on the cover 26 to define a hammer chamber: wherein the hammer 17 rotates.

It will now be seen that any operating mechanism housed within this sealed chamber will be free of corrosives inv the ambient air and will not allow insects to enter.

The operating mechanism enclosed within the abovedescribed sealed chamber when a spring motor for providing a constant torque is employed includes the illustrated storage drum 39 having a rotatably mounted shaft.

The storage drum shaft 32 is rotatably mounted between' thei cup-shaped member 24 and the mounting plate 23 through the provision of a socket defined on the cupshaped member 2li'A to rotatably' receive the storage drum shaft32 and which. shaft hasitsnoppos'ite endl deiinedwith.:

4l( a socket to receive a pin provided on the adjacent side of the mounting plate 28 (not shown). A commercially available constant tension spring 34 is wound on the storage drum 30 and which storage drum normally stores the spring when the alarm 1G is rendered inoperative. The essential characteristic of the spring 34 is that it provides a constant torque throughoutits entire lengthyto thereby provide a constant driving action. The spring 34 is mounted onthe storage drum 3) in a manner whereby when it is unwound therefrom it will quickly return thereto.

A drive drum 36 mounted adjacent to the storage drum Btl is connected withv an end of the spring 34; see FIG. 4. The drum 36 is mounted on a rotatable shaft 38 journaled in the same general fashion as the storage drum 30. The drive drum shaft 3S is rotatably positioned in a socket on the cup-shaped member 24 (see FIG. 3) and extends therefrom through the mounting plate 28 and the cover 26 to receive the winding knob 16'; see FIG. 3. The cover. 26 isV defined with a socket 26b arranged adjacent the` raised portion. 26Bl to receive the winding knob 16 which is connected to the drive drum shaft 33 by means of a screw 4i) threaded thereto. The rotation of the knob 16 will cause the spring 34 to be unwound from the storage drum 3i) and onto the drive drum 36 to place the alarm 10 in an. operating condition. A drive gear 42 is mounted on. the rotatableshaft 35 intermediate the drive drum 36 and the winding 'knob 16 withinthe sealed chamber to be rotatable therewith. The unwinding of the spring 34 from the'drive drum 36 willcause the shaft 38 to rotate.. and thereby rotate the drive gearV 42. The drive gear 42v isA arrangedin driving engagement with the splined end' of a. stubY shaft 44 rnountingan intermediate or transmitting'gear 46 rotatable therewith. This transmitting gear 46 is dened to step up the rotary speed of the drive gear 42 and includes a stop member or lip 46a dened integralA therewith on the face adjacent the bell 12.

The drive drum shaft 38 may also be arranged to mount a contr-ol mechanism to lock the gearing and thereby the hammer when the spring/34 is being wound onto the drive drum 36. This control mechanism may be a ratchet 37 mountedto be rotatable with the drive shaft 38 cooperating with a detent 39 mounted on the drive drum 36 and engaging'the ratchet 37. ItV will be recognized that this mechanism will prevent the driving of the gearing and hammer while the spring 34 is being wound onto the drive drum 36but yet' allows the drivingof the hammer when the spring 34 is being unwound from the drive drum 36.

The hammer 17 is mounted to be rotated by a stub shaft 48 having a splined end arranged in driving relationship with the transmitting gear 46. The hammer 17 is defined by means of a pair of spaced arms 50 and 52', one of which is dened with a pairof pins adjacent thek opposite ends to be received in suita'ble apertures in the other arm, as shown in FIG. 3. The arm 50 is defined with ther pins 505 to be received in a suitable aperture of the arm S2; as shown in FIG. 3`. The pins 50a mount hammerheads 54 in a very loose relationship. This a1'.- rangement is clamped together by the provisionv of a screw threaded' into the end ofthe shaft 32.

The liammerheads 54 are tubular members having a large internal diameter relative to the diameter of the pins 50a whereby they will move outwardly relative to the arms 5t) and 52 under the inuence of centrifugal force' and inwardly in response to an inwardly directed force.

The hammer17 is mounted over the mounting plate 28 It should be noted that this hammer and bell arrange-- ment is useful to provide a governing. action to control' the release of the stored energy of. the spring. The actionof the hamm'erheads 54 upon striking the` pin 12a andv traveling; beyond the pin under the urging ofthe spring.

t is such as to govern 'or delay the release of the energy stored in the spring. Thisfc'oaction causes the energy of the spring to be released at a lower rate and the speed of the hammer 17 to be reducedrelative to a bell not provided with a strikingpin. This governing action causes the bell 12 to befsoundedover -a longer period of time lfor a given length of spring, whether the spring be a coiled spring, constant tension spring o'r otherwise. Accordingly, a lon'g sounding period may be provided with a length of 'spring readily housed within the bell proper.

The operating control-means for sounding the alarm 1t! includes the control 'pin l22V andi the heat sensitive latch 20. The control member! 22 'isarranged Vwith a spring 62. seated in acentral s'oc'ket'fo'ri the cup-shaped member 24 and labutting a shoulder dend intermediate the ends of the pin whereby the spring constantly urges the control pin through the central aperture for the cup-'shaped member 24 and o'n th'c' outside of the bell 1-2. The stop memb'er 46El is located oh the transmitting gear 46 whereby it will be rotated into engagement with the control pin Z2 when the latter is in a depressed position. This depressed or locked position is achieved by securing the latch 2d between the 'clips `'defined on an ornamental star 64 mounted on the outside face of the bell 12. The star 64 is secured to the Abell 1'2 by means of a pair oflscrews connected to lthe cup-shaped member 24, The latch 26 when clipped forces 'the control pin r22 to the depressed position whereby the transmitting gear is prevented Vfrom rotating until the control pin 2'2 is positioned out of the path of the gear 46.

The relative Ilocation of the spring 34, that `is whether it is stored on the storage drum 30 or on the drive drum 36 is indicated through the provision of the ag 1S. The Hag 18 is mounted to be rotatable with a shaft 65 carrying a sensing arm 68 adjacent its other end. The shaft 65 extends through the mounting plate 28 and the cover 26. This exposed end of the shaft 65 is threaded to secure the ag 18 thereto by means of a screw. A biasing spring 67 is wound around the portion of the shaft 65 extending between the mounting plate 28 and the cover 26 to urge the spring sensing arm 68 continuously against the outer Wrap of the spring 34 wound on the storage drum 30. The sensing arm 68 arranged in this fashion also functions as a stop to prevent the winding of spring 34 in such a manner so as to disengage it from drum 3i) and from deforming it by reverse bending. The flag 18 is in this manner positioned to be within the outer peripheral edge of the bell 12, when the spring 34 is completely wound on the drive drum 36 and is rotated outwardly beyond the peripheral edge of the bell 12 when the sensing arm 68 is moved away from the storage drum 30 as a result of the spring 34 being rewound thereon; as shown in FIG. 2 in dotted outline. The flag 18 may be marked with a legend such as Rewind to indicate even more readily the condition of the alarm.

A mounting clip 70, as shown in FlG. l, is connected to the cover 26 by means of a pair of screws over the socket 26b defined for the winding knob 16. This mounting clip 70 allows the alarm 10 to be readily mounted and dismounted in either a horizontal or vertical position.

With the above structure in mind, the operation of the alarm will now be described assuming the latch Ztl is a heat sensitive element selected to deform at an elevated temperature in a manner to allow the control pin 2,2 to disengage the transmitting gear 46. The spring 34 is manually wound onto the drive drum 36 by rotating the knob 16. The flag 18 at this time will be rotated within the periphery of the bell 12 and therefore not visible when the spring 34 is stored on the drum 36. When the ambient temperature of the room in which the alarm 1i) is to protect reaches a preselected elevated temperature, the latch 20 will al-low the control pin 22 to disengage the transmitting gear 46 and thereby allow the spring 34 to wind back onto the storage drum 30. The unwinding of the spring 34 from the drive drum 36 provides the 6 rotary driving action of the drive gear 42. The rotation of the drive gear 42 drives the stub shaft 44 which in turn rotates the intermediate gear 46. Since the control `pin 22 is disengagedl from the transmitting gear 46 this driving action is coupled to thershaft 48 for driving the hammer 17. The hammer' 17 is then rotated at a high speed whereby the hammerheads 54 are driven to their outer extreme under the inuence of centrifuga-l force and upon being rotated into engagement with the sounding pin 12a strike it a glancing blow, are then forced inwardly by the pin 12a, and in passing by the pin, once again are forced outwardly under the inuence of centrifugal force; see FIG. 2. This glancing blow of the sounding pin 12a is effective to loudly sound the bell 12. The hammer 17 continuously sounds the bell in this fashion as the hammerheads 54 are rotated to strike the pin 12a. This sounding action continues at high speed and at the same loudness until the spring=34 is wound back on the storage drum 30. After the spring 34 i's relocated on the storage drum 30 the sensing ann 68 will have moved the flag 18 to indic`a`te a rewin'd is necessary. It should be noted that this rewind signal provided by the liag 18 is in addition to the indication of the condition of the alarm which is revealed by the condition of the latch or heat sensitive element 20. l

The continuous sound ofthe bell llt) in this fashion has been arranged to provide an extremely loud sound level of a nature readily distinguished by a normal sleeper from other environmental sounds emanated by sirens, telephones, buzzers, whistles, doorbells and the like. The bell 10 'providesdthis continuous sound for many minutes.

What is claimed is:

1. An alarm comprising a Ibell having a sounding pin formed integral therewith, a sealed sub-assembly substantially housed within said bell comprising a cup-shaped member and a cover member enclosing the latter, a storage -drum rotatably mounted in said sub-assembly for storing a spring, a constant tension spring normally stored on said storage `drum and adapted to return to same when unwound therefrom, a drive drum rotatably mounted in said sub-assembly and having one end of the spring connected thereto for winding the spring onto same from said storage drum, a hammer having movable sounding heads at opposite ends thereof and rotatabiy mounted in said sub-assembly adjacent the sounding pin to allow a sounding pin to extend outwardly therefrom for striking the pin, step-up transmission gearing mounted in said sub-assembly in a driven relationship with said drive drum to be responsive to the rotation of same provided by the unwinding of the spring from said drive drum and having a driving connection with the hammer for continuously driving same at a constant rate throughout substantially the whole length of the spring, means mounted externally of said sub-assembly and connected to the drive drum for winding the spring thereon, and control means extending outwardly of said sub-assembly and said bell engageable and disengageable with the gearing to selectively control the operation of the gearing, and latch means mounted on the bell operable to lock and unlock the control means into and out of engagement with the gearing to selectively control the sounding of the bell.

2. An alarm as defined in claim l wherein said latch means includes a heat sensitive element visibly mounted on the bell to be completely exposed to the ambient air and engageable with the control means to position the latter into engagement with the gearing at normal ambient temperatures and responsive to a preselected ambient temperature to disengage the gearing.

3. An alarm comprising a bell having a sounding pin formed integral therewith, a constant tension spring ,a storage drum rotatably mounted for storing said spring, a drive drum rotatably mounted and having one end of the spring connected thereto for winding the spring onto same from said storage drum, means connected to the -mounted hammer having a pair of striking heads loosely Ymounted thereon, said hammer being mounted.- adjacent the sounding pin for striking the pin and thereby sound- 'in'g the bell, transmission gearing mounted in a driven j relationship to be responsive to the rotation 'of said drive drum provided by the unwinding of the.' springther'efrom Aand having a driving connection with the vhammer for rotating same at a constant rate, said gearing including at least a single gear having a stop member defined thereon, and control means engageable and disengageable with the stop member for locking -and unlocking the transmission gearing to selectively control the sounding ofthe bell. g

I 4. A fire alarm comprising a bell, a rotatable drum `having a constant tension spring Wound thereon, a rotat- 'Sable drive drum connected'with one end of the spring,

'f said gearing to control the unvvinding of the spring from the drive drum.

5. A fire alarm as defined in claim 4 including a 'separate housing forsealing said rotatable drm'srincluding the spring and the gearing from corrosive environments.-

6. A re alarm as deined in claim 5 including means responsivelto the length ofi-'spring wound on ythe'storage drum for visually indicating the operating condition of the alarm. e

7. A re alarm inclu-ding a bell having a striking pin formed integral therewith; a sealedsub-assembly snbst'an tially housed Within the bell comprising a rotatable harnfmer extending therefrom for sounding the bell, and spring means connected to said hammer for continuously rotating same; said hammer having anl arm loosely mounting striking members adjacent each end of the arm, the striking members being mounted on the arm whereby upon rotation of the hammer under urging or" the spring means the members -move relative to the arm intofthe path of the striking vpin to strike the bell a glancing blow and are moved out of the path of the pin by thepin to govern the release of energystoredl in the spring and thereby extend the length of time the bell is sounded, and heat sensitive control means Within the sealed subassembly connectedA to the spring means for controllably actuating the release of energy from said spring means.

References Cited int-he tile of this patent' 'UNITED STATESlATENTS 565,306 strain Aug. 4, ,1896

815,1111 Meyers et al.l Mar. 13, 1906 1,415,207 Swanberg .V May 9, 1922 2,625,902 Sorensen a.. Jan. 20, 1953 2,871,815 Krieger -4.7----7 Feb. 3, 1959 FOREIGN PATENTS 526,262 June 28, 1921

Patent Citations
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US565306 *Mar 25, 1896Aug 4, 1896 Bell-ringing mechanism
US815111 *Aug 25, 1905Mar 13, 1906Schmidt Charles CThermostatic alarm.
US1415207 *Jan 13, 1919May 9, 1922Fabart Instr CompanyAutomatic alarm
US2625902 *Jul 17, 1950Jan 20, 1953Sorensen Harold CFire and burglar alarm
US2871815 *May 2, 1957Feb 3, 1959Krieger Alan TFire detecting device
FR526262A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3148658 *Aug 6, 1962Sep 15, 1964Ruth KaplanMechanical sound-producing fire alarm device
US3192890 *Jul 30, 1963Jul 6, 1965Interstate Engineering CorpFuse for fire alarms
US3552350 *Jul 14, 1969Jan 5, 1971Emdeko Distributing IncVisual signal means for a fire detection alarm
US3570446 *Sep 23, 1968Mar 16, 1971Emdeko Distributing IncFire detection alarm means
US3804054 *Sep 7, 1971Apr 16, 1974Ato IncWarning device for fire protection system
US5589824 *Nov 9, 1995Dec 31, 1996Lynch Adam QMulti-sensor detection system
US7097531May 21, 2004Aug 29, 2006Brent DuchonSelf powered fire alarm
US20050258970 *May 21, 2004Nov 24, 2005Brent DuchonSelf powered fire alarm
U.S. Classification116/106, 116/158
International ClassificationG10K1/074, G08B17/02, G10K1/00
Cooperative ClassificationG10K1/074, G08B17/02
European ClassificationG10K1/074, G08B17/02