US3394675A - Mechanical type residence fire alarm - Google Patents

Description

July 30, 1968 c. J. PALM MECHANICAL TYPE RESIDENCE FIRE ALARM Filed March 51. 1966 rrrnrnr A T TR/VEV United States Patent O 3,394,675 MECHANICAL TYPE RESIDENCE FIRE ALARM Clarence J. Palm, BOX 249, Rte. 1, Cheboygan, Mich. 49721 Filed Mar. 31, 1966, Ser. No. 539,069 4 Claims. (Cl. 116-102) ABSTRACT F THE DISCLOSURE A residence re alarm of the mechanical type is disclosed comprising, in combination, a sounding mechanism for sounding off a warning alarm, a manually windable spring motor having a gear train which it drives by unwinding and by which it operates upon said sounding mechanism to `sound off said alarm, temperature responsive means of the longitudinal type having a longitudinally extending helically coiled bimetallic element, a shaft coaxial with said bimetallic element and having an arm projecting laterally thereof, an end of the bimetallic element fast to the shaft, means including a stationary mount for supporting the shaft and bimetallic element so that said shaft and arm rotate by action of said bimetallic element upon change in temperature of the room in which said lire alarm is located, said arm operative upon said gear train in accordance with the temperature responses of said bimetallic element, and means which can be applied while said bimetallic element is at a predetermined temperature above room temperature to fasten the rotated position of said arm in respect to said gear train, said arm being so positioned and fastened in respect to said stationary mount while said bimetallic element is at said predetermined temperature as to: (l) be positioned just clear of said gear train when said bimetallic element is at said predetermined temperature causing said spring motor to unwind to sound off said alarm; (2) to be moveable into a position of interposition in respect to said gear ytrain to arrest motion of the same thereby preventing unwinding of said spring motor Vand preventing sounding off of said alarm when the temperature of said bimetallie element falls below 'said predetermined temperature; and '(-3) to be moveable out of said position of interposition into a position clear of said gear train causing the spring motor 4to unwind to sound olf said alarm when the temperature of said bimetallic element rises to said predetermined temperature or to 4a temperature above said predetermined temperature.

My invention relates to improvements in mechanical type re alarms for use in homes and the like.

Low cost but reliable lire alarms of this type which do not reply upon electricity or batteries are sorely needed to combat the terrible disasters of home Ifires. They are not `available on the market for the reason that those proposed heretofore have not been practical.

The principal object of the present invention is to provide an entirely practical -and thoroughly reliable low cost mechanical type fire alarm which will find acceptance on the market.

The foregoing object of the invention and its advantages will become apparent during the course of the following description, taken in conjunction with the accompanying drawings, Iin which:

"FIG. l is a perspective view of a re alarm embodying my invention;

FIG. 2 is a plan view partly in section of the Vstructure of FIG. 1;

IFIGS. 3, 4 and 5 are sectional views of the structure of FIG. 2 taken, respectively, along the lines 3 3; 4 4 and 5--5 thereof; and

3,394,675 Patented July 30, 1968 FIG. `6 is a fragmentary view of a portion of FIG. 3.

Referring to the drawings in greater detail, such Ifire alarm is generally designated 10 and comprises a base 12, preferably of metal, and a sounding mechanism mounted thereon in the form of a bell 14 and clapper 16 in the instance. The clapper 16 is actuated by a spring motor 18 of well known construction having a pair of plates 20 for a frame, the lower plate of which is mounted on the base 1'2 as shown. The plates 20 are fastened together by posts 22 and hold a train of gearing between them which comprises ya main gear wheel 24 fast 0n a main shaft 2S which is rotated in one direction (anticlockwise in FIG. 2) by the unwinding of a main spring 26 and in the opposite direction by a key 28 which winds up the main spring 26. The main gear wheel 24 meshes with a pinion gear 30 fast on a shaft 32 together with an intermediate gear wheel 34 which meshes with `a pinion gear 36 fast on a shaft 38 together with another intermediate but smaller gear wheel 40 which in turn meshes with a pinion gear 42 fast on a shaft I44 together with a terminal gear wheel 46 which meshes with a pinion gear 48 fast on a shaft 50 together with a ratchet wheel 52, The teeth of the ratchet wheel 52 alternately engage depending legs 54 and 56 on the clapper 16 which comprises an escapement pawl 58 pivotally mounted on a shaft 60, the free end of which pawl 58 carries a slug. When the spring motor is wound by turning the key 28 clockwise as viewed in FIG. 2 the pinion gear 30 is moved out of the way by the gear wheel 24 which causes the shaft 432 to ride up slots 64 provided in the plates 20. When the spring motor 18 is allowed to unwind as will be described it causes the ratchet wheel 52 to rotate anti-clockwise as viewed in FIG. 6 which throws the pawl 58 back and forth about its pivot so that the weighted free end thereof strikes the bell 14 with repeated blows to make it reverberate loudly. The leg 54 is moved into striking engagement with each succeeding tooth on the ratchet wheel 52 by the leg 56 being struck by each tooth and being thrown clear thereof and vice versa, i.e. the leg v56 is moved into striking engagement with each succeeding tooth by the leg 54 being struck by each tooth and being thrown clear thereof.

The clapper 16 is held in braking engagement with the ratchet wheel 52 preventing it from rotating and the spring motor 18 from unwinding by an arm 66 which holds the leg l54 in locking engagement against a tooth of the ratchet wheel. The arm 66 is carried on the bent end of ya shaft 67 of a temperature responsive mechanism 68 of the longitudinal type which is disposed longitudinally of the base 12 and transversely of the path of air flow thereover between and over the plates 20 developed by air openings '69 in opposite side walls of a case 72 which ts over the bell 14, the spring motor 18, the key 28, the thermal responsive mechanism 68 and fastens to the base 12 by well known means not shown. The thermal responsive mechanism 68 is the key to the successful functioning of my device and comprises a longitudinally extending heat expandable rotational member Asuch as a bimetallic element 70 in the form of a helical metal ribbon disposed about and extending over `the length of the shaft 67 which is supported for rotation near its bent end by a bearing 73. The ends of the bimetallic member 70 are made fast to the bearing 73 and to the end of the shaft 67 opposite its bent end. I have found that this type of temperature responsive mechanism is necessary to develop the torque required for reliable braking and releasing of the spring motor. An adjustable mounting mechanismfor the thermal responsive element is provided which comprises a member 76 fastened to the base 12 by a screw as shown and a member 18 fastened to the member 76 by a pair of screws 80 which extend through apertures in the member 78 and threadably engage the member 76. The members 76 and 78 form a split yoke for the bearing 72 to permit it to be moved to any desired longitudinal and rotational position and to lock it therein. This is vit-al to the proper functioning of the fire alarm as it must be set to go off within a degree of the desired maximum temperature. The average room would call for an alarm to sound when the temperature therein reaches 120 degrees Fahrenheit while the average attic would call for an alarm to sound when the temperature therein reaches 140 degrees Fahrenheit. Particular applications or the particular owner of the fire alarm may call for a different predetermined temperature at which the alarm is desired to be sounded. A temperature controlled heating device in the form of a sleeve may be slipped over the thermal responsive mechanism 68 to bring its temperature to the desired predetermined value. A simple way is to set the base 12 in a temperature controlled oven and allow it to remain there long enough to bring the parts mounted thereon including the temperature responsive mechanism 68 to the desired temperature. The spring motor 18 is first wound, of course. With the parts at this temperature the bearing 73 is rotated within the split yoke formed by the members 76 and 78 until the arm 66 just misses the clapper 16 (as shown by the dotted outline position for the arm 66 in FIG. 4) and the bell 14 rings. When this happens the screws 80 are tightened to secure the bearing 73 against further rotation within the split yoke as the sounding of the bell 14 insures the desired position for the arm 66 of just missing the clapper 16 when the bimetallic element 70 is at 120 degrees Fahrenheit. As the element 70 cools one degree, as from being removed from the oven, the arm 66 moves into the path of the clapper 16 and locks it in engagement with the ratchet wheel 52 as explained. A stop 82 which is fastened to the base 12 as shown limits the travel of the arm 66 as the bimetallic element 70 cools so that the clapper 16 is held in braking engagement with the ratchet wheel 52 and prevents the spring motor 18 from unwinding no matter how much below 120 degrees Fahrenheit the room temperature falls. The fire alarm can be tested at any time by heating the air which passes between the openings 69 (or by heating the bimetallic element 70 by passing a heated sleeve thereover, as described) until the temperature of the bimetallic element 70 is 120 degrees Fahrenheit and the bell 14 sounds. The alarm can be tested as often as desired. If the spring motor 18 winds down too far from testing it can be rewound at any time.

It will thus be seen that there has been provided by the present invention, improvements relating to mechanical type re alarms, in which the object hereinabove set forth together with many other thoroughly practical advantages has been successfully achieved. While a preferred embodiment of the invention has been shown and described it is to be understood that variations and changes may be resorted to without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. A residence re alarm of the mechanical type comprising, in combination, a sounding mechanism for sounding off a warning alarm, a manually windable spring motor having a gear train which it drives by unwinding and by which it operates upon said sounding mechanism to sound off said alarm, temperature responsive means of the longitudinal type having a longitudinally extending helically coiled bimetallic element, a shaft coaxial with Cil said bimetallic element and having an arm projecting laterally thereof, an end of the bimetallic element fast to the shaft, means including a stationary mount for supporting the shaft and bimetallic element so that said shaft and arm rotate by action of said bimetallic element upon change in temperature of the room in which said. re alarm is located, said arm operative upon said gear train in accordance with the temperature responses of said bimetallic element, and means which can be applied while said bimetallic element is at a predetermined temperature above room temperature to fasten the rotated position of said arm in respect to said stationary mount so that said arm can be selectively positioned in respect to said gear train, said arm being so positioned and fastened in respect to said stationary mount while said bimetallic element is at said predetermined temperature as to: (l) be positioned just clear of said gear train when said bimetallic element is at said predetermined temperature causing said spring motor to unwind to sound off said alarm; `(2) to be moveable into a position of interposition in respect to said gear train to arrest motion of the same thereby preventing unwinding of said spring motor and preventing sounding off of said alarm when the temperature of said bimetallic element falls below said predetermined temperature; and (3) to be moveable out of said position of interposition into a position clear of said gear train causing the spring motor to unwind to sound off said alarm when the temperature of said bimetallic element rises to said predetermined temperature or to a temperature above said predetermined temperature.

2. A residence fire alarm of the mechanical type as claimed in claim 1, a sleeve, the other end of the bimetallic element fast to said sleeve, and means which can be applied while said bimetallic element is at said predetermined temperature to fasten the rotated position of said sleeve in respect to said stationary mount, said shaft rotatably supported in said sleeve.

`3. A residence re alarm of the mechanical type as claimed in claim 2, said sounding mechanism of the bell and clapper type, said arm operative upon the clapper of said sounding mechanism to arrest its motion when said arm is in said position of interposition in respect to said gear train.

4. A residence fire alarm of the mechanical type as claimed in claim 3, cover means enclosing said sounding mechanism, said gear train, said temperature responsive means, and the other operative parts of said fire alarm, and apertures in the cover means to provide a path of air flow therethrough, said temperature responsive means deposed transversely of said path of air flow.

References Cited UNITED STATES PATENTS 117,682 8/1871 Richards 116-101 732,727 7/1903 Fletcher 116--91 846,095 3/1907 Dick 116-102 1,240,618 9/1917 Stevens 116-102 1,617,540 2/1927 Oberreich 116-102 1,629,312 5/1927 'Rumrich 116-91 1,692,301 11/1928 VHeslewood 73--363.9 l1,823,722 9/1931 Birtciel 116-101 1,933,801 11/1933 Hart 73-363.9 2,533,835 12/1950 lPalmer 116-102 2,897,775 8/1959 Thesen 116-102 LOUIS J. CAPOZI, Primary Examiner.

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