US3570446A

US3570446A - Fire detection alarm means

Info

Publication number: US3570446A
Application number: US761433A
Authority: US
Inventors: Wesley E Buford; Charles G Buford
Original assignee: EMDEKO DISTRIBUTING Inc
Current assignee: EMDEKO DISTRIBUTING Inc
Priority date: 1968-09-23
Filing date: 1968-09-23
Publication date: 1971-03-16
Anticipated expiration: 1988-03-16

Abstract

A fire detection alarm means in which one or more hammers (and speed governors) have pivotal connections to a rotatable driven member and are held by an arcuate wall in backfolded, coiled, or cocked position with respect to the direction of rotation of the driven member for movement through a preselected angle, said arcuate wall ending in spaced relation to a sound pin for permitting uncoiling or uncocking of said hammer member in response to centrifugal forces with increased speed to strike said sound pin to forcibly drive the pin against a sound shell or bell.

Description

United States Patent 1 1 3,570,446

[72] Inventors Wesley E. Buford 1,463,361 7/1923 Georgi et al. l 16/ 143 Covina; 1,563,279 11/1925 Hartley 116/102 Charles G. Buford, Azusa, Calif. 2,197,412 4/1940 Keegin 1 16/102 [21] Appl. No. 761,433 2,246,878 6/1941 Davis 116/102 [22] Filed Sept. 23, 1968 2,609,785 9/1952 Fink 116/102 Patented Mar. 16, 1971 2,999,477 9/1961 Pratt et a1. 116/158X [73] Assignee Emdeko Distributing, Inc. 3,148,658 9/1964 Kaplan 1 16/106 Salt Lake City, Utah [54] FIRE DETECTION ALARM MEANS 15 Claims, 14 Drawing Figs.

[52] US. Cl 116/102,

58/85, 116/158, 185/14 [51] Int. Cl. G08b 17/00 Field ofSearch 116/5, 101,

Primary Examiner-Louis J. Capozi Attorney-Miketta, Glenny, Poms and Smith ABSTRACT: A fire detection alarm means in which one or more hammers (and speed governors) have pivotal connections to a rotatable driven member and are held by an arcuate E 12' i I48 i 23 2 1a 42 145 f 452 13/ 1 1' 5570 L n 1, I 1 I 1 q 1 7 i J U 52 -:-1 29 $0 #1 we /-8P 9? p L 60 66 X 1 Patented March 16, 1971 3,570,446

4 Sheets-Sheet l 45 INVENTO/QS.

WE'SZEV E. Hypo/20 CMQELES G Bap-020 Patenkd March 1%,, WW 3,570,446

4 Sheets-Sheet 2 Ju wm-zz FIRE DETECTION ALARM MEANS BACKGROUND OF THE INVENTION Fire detection alarm means are desirable for the purpose of sounding a warning of a potentially dangerous fire condition. Electrical type alarm devices are subject to power failure and therefore are not completely reliable. Failure of a power source may immediately precede a fire condition so that no warning would be given. Mechanical alarm devices are therefore desirable because they do not rely upon external power sources but instead are self-powered or contain their own power source.

Prior proposed mechanical alarm devices have not been completely satisfactory because of shortness of the warning signal, the signal is not sufficiently loud, the intensity of the warning signal may vary from the beginning to end of the warning cycle, and the reliability of prior proposed complicated mechanical alarm constructions was not completely satisfactory.

The present invention contemplates a fire detection alarm means which overcomes many of the disadvantages of the prior proposed mechanical alarm systems and provides operating characteristics which surpass prior proposed mechanical systems. The present invention contemplates a detection means wherein maximum utilization of the energy stored in a spring motor is used to drive through a gear system one or more freely swingable hammer members which not only serve to forcibly strike a sounding pin but also serve to control or regulate a uniform discharge of energy from the spring motor. The detection alarm means for the present invention provides an alarm-warning sound in the order of 90 to 97 decibels and when fully wound will continue such warning sound with little variation in decibels for a period of from to 9 minutes. The alarm means for the present invention is compact and readily mounted on a supporting surface which may be either vertical or horizontal and is conveniently wound without removal from such surface.

The main object of the present invention, therefore, is to disclose and provide a fire detection alarm means of mechanical type and having an improved effective signal sound intensity and signal-warning life.

An object of the present invention is to disclose and provide a fire detection alarm system including a novel construction wherein one or more hammer members are, in effect, thrown against a sounding pin by centrifugal force imparted to said hammer members by a rotatable member.

An object of the invention is to disclose and provide a detection alarm means wherein said hammer members not only serve to strike a sounding pin but are also cooperable with a frictional wall surface to restrain or retard the rapidity of rotation of the rotatable member on which they are mounted so as to prolong the period of the warning signal.

Other objects and advantages of the presentinvention include the provision of: a novel nonrotatable, inner sealed unit which houses the operating structure of the alarm for environmental protection and for improved assembly thereof; a novel arrangement for interconnecting a thermal-responsive means mounted at the front face of the alarm means with a trigger means mounted adjacent the back face of the alarm means; a manual release means for testing operability of the alarm means; an arrangement of a signal flag which is automatically exposed when the device becomes "partially unwound and which is held in retracted covered position when the alarm is in ready condition for operation; a novel effective construction for striking a sounding pin with a maximum force and with selected rapidity so that a sound alarm of loud attentiondemanding intensity is produced.

A further object of the invention is to provide a mechanical alarm in which the outer shell or bell is rotatable to wind the spring motor without removal from a wall or ceiling mounting. Other objects and advantages of the present invention will be readily apparent from the following description of the drawings in which an exemplary embodiment of the invention is shown.

FIG. 1 is a tiperspective view of a tire detection alarm device embodying bracket;

FIG. 2 is a perspective view of a modification of a mounting bracket for hanging the device on a door;

FIG. 3 is a side elevational view of the device and mounting bracket installed on a wall surface, portions of the device being broken away to better show the mounting arrangement;

FIG. 4 is an enlarge view taken in the plane indicated by line IV-IV of FIG. 3;

FIG. 5 is a transverse sectional view taken along a diametrical plane indicated by line V V of FIG. 4;

FIG. 6 is an enlarged fragmentary sectional view taken in a diametrical plane as indicated by line VI-VI of FIG. 4;

FIG. 7 is a fragmentary sectional view taken in the same plane as FIG. 6 and showing the position of the thermalresponsive means after sensing a preset fire detection temperature;

FIG. 8 is an enlarged fragmentary transverse sectional view taken in the plane indicated by line VIII-VIII of FIG. 6;

FIG. 9 is a back view of the device taken from the plane indicated by line IX-IX of FIG. 5; 1

FIG. 10 is a sectional view taken in the planes indicated by line X-X of FIG. 5;

FIG. 11 is a fragmentary sectional view taken in the plan indicated by line XI-XI of FIG. 5;

FIG. 12 is a schematic view showing successive relative positions of the hammer means in its path of rotation during operation of the device;

FIG. 13 is a perspective bottom view of a hammer member;-

FIG. 14 is a sectional view taken in the plane indicated by line XIV-XIV of FIG. 6

In the drawings an exemplary embodiment of the present invention is indicated at 20 and may be mounted on a supporting surface by a mounting bracket 21. Generally speaking thermal-responsive fire detection alarm means 20 includes an outer rotatable shell means 22 adapted to be struck to produce an alarm sound, an inner nonrotatable sealed unit generally indicated at 25 received within said shell and includ ing an inner housing 24 and a base member 23. Within the inner housing a drive means 26 is operably connected to the outer shell 22 and to a gear train means 27 for driving a strike means 28 for repetitively striking one end of a sounding pin 29. Trigger means 30 (FIG. 6 and FIG. 7) may be cooperably connected with a thermal-responsive device 31 and with the strike means 28. The trigger means 30 may also include a manually actuated alarm release means 32 (FIG. 9). Visual flag means 33 carried by base member 23 is provided to indicate wound or unwound condition of the alarm means.

Mounting bracket 21 briefly comprises an elongated bracket body 36 provided with top and bottom notch means 37 and 38, a keyhole opening 39, and a retention spring 40. Keyhole opening 39 receives a mounting screw 41 (FIG. 3) and notch means 37 and 38 receive top and

bottom buttons

42 and 43 on base member 23. Spring 40 has an opening 44 to receive bottom button 43 to lock the alarm means on the mounting bracket. Depression of spring 40 toward the supporting surface releases button 43 and permits the alarm means to be lifted out of the notch means 37 and 38.

A modification of the mounting bracket for use on a door or the like is shown in FIG. 2 in which a bracket member 36 is provided with top and bottom notch means 37' and 38' for reception of

buttons

42 and 43 in a manner similar to that above described. Bracket member 36'U-shaped is extended upwardly to form a downwardly facing top U-shaped portion 46 having

walls

47 and 48 spaced sufficiently to receive the top edge margin of a door. The alarm means 20 may thus be readily removably mounted on the top of a door.

The outer shell means 22 may be of suitable configuration and made of suitable metal material to provide successively increasingly tapered frustoconical portions 50 an 51 which terminate in a cylindrical skirt portion 52 which may extend slightly beyond the back face of base member 23. The central portion of shell means 22 may be provided with an inturned is invention and associated with a mounting internally threaded boss 53 adapted to position a ratchet member 54 secured to shell 22 by screw bolts 55a. Ratchet member 54 may be integral with an axially extending hollow hub portion 55 having a longitudinally extending keyway 56. Boss 53 may be internally threaded to receive a bushing 58 having an enlarged circular head 59 for covering screw bolts 55a and for suitable decoration of the front face of shell means 22. Bushing 58 may carry a headed axially movable spacer element 60 for cooperation with thermal-responsive means 31 and a rearwardly extending axial transfer pin 61 as later described.

The inner nonrotatable unit comprising the inner housing 24 and base member 23 is mounted coaxially with the outer shell means 22. Inner housing 24 includes

frustoconical portions

64, 65 and a cylindrical portion 66 corresponding generally to those portions of shell means 22 and of slightly different angular relationship so as to provide a suitable space between the

cylindrical portions

52 and 66 for movement of sound pin 29. Inner housing 24 may have a central opening to receive ratchet member 54 and between inner housing 24 and shell means 22 may be provided a suitable spacer O-ring 68 to permit relative rotational movement between the inner housing and shell means 22.

Base member 23 covers the back opening of inner housing 24 and extends therebeyond into close spaced relation with the opening defined by the cylindrical portion 52 of shell means 22. Base member 23 includes an annular forwardly facing rib 70 received within a rabbetted internal edge 71 of cylindrical portion 66 of inner housing 24. Base member 23 and housing 24 may be secured by suitable screw means 72.

Base member 23 carries on its inner face a suitable frame means 74 for supporting various component parts of the mechanical alarm within housing 24. As best seen in FIG. 6 transverse wall 75 of frame 74 may be provided with a central axial opening 76 and washers 77 through which a rotatable shaft 78 may extend. A spacer member 79 is positioned between one face of front washer 77 and a spring motor casing 80.

Means for driving in rotation strike means 28 may comprise a suitable spiral spring motor 82 carried within motor casing 80 which may comprise flat metal straps 83 arranged in 90 spaced relation and each bent to form a U-shaped enclosure for spring motor 82 with ends of straps 83 terminating in spaced relation to hub 55 (FIG. 6). One of straps 83 may have secured thereto in any suitable manner, as by a stamped out tooth and opening at 84, the end of the outer turn of spring 82 (FIG. 4). The inner end of spring 82 is received within key slot 56 provided in hub 55. Motor casing 80 is provided with a spline connection 86 to rotatable shaft 78 which is partially received as at 87 within the bore of hub 55.

Spring motor 80 may thus be wound by turning outer shell 22 which transmits such rotational movement through hub 55 to the inner turn of the spring 82. Hub 55 includes ratchet 54 provided with ratchet teeth 90 (FIG. 11) which are held against rotation in a clockwise direction as indicated by a dog 91 pivotally mounted on inner housing 24 and biased into engagement with teeth 90 by a suitable spring 92 having one end secured at 93 and its other end slidable in a slot 94 provided in dog 91. Slot 94 and spring 92 may be substantially aligned in normal position as shown in FIG. 11. Thus when the outer shell 22 is turned in a clockwise direction, the spring will be deflected, motor housing 80 being restrained against turning by trigger means 30 as hereafter described.

Spring motor 80 is thus operably connected to gear train means 27 through rotatable shaft 78 which may include a threaded connection 96 to a gear 97. Gear 97 meshes with gear teeth 98 provided on the hub of a second gear member 99 whose teeth mesh with hub gear teeth 100 on a gear member 101 rotatable about a reduced end portion 102 of shaft 78. The gear members 101 and a shoulder 104 upon which seats the strap construction of motor casing 80.

Gear member 101 meshes with hub teeth 106 of a rotatable member 107 associated with striking means 28. Rotatable member 107 and gear member 99 are pivoted about an axis provided by a suitable stub shaft 108 carried by plate 75 and extending to base member 23. Member 107 may be provided with an integral spacer hub 107a to limit rearward displacement of member 107 so that the operative relationship of member 107, gears 106, 101, trigger member 130 and hammers 110 will not be disturbed by varying the position of the alarm device. 7 I

Strike means 28 includes in addition to rotatable member 107 a pair of hammer members 110 each having a pivotal connection 111 adjacent one end of rotatable member 107. Each hammer member 110 may be provided with a stop shoulder 112 on the bottom face thereof as viewed in FIG 13 for limiting backfolded or rearward movement of hammer member 110 when the direction of rotation is clockwise as viewed in FIG. 8. In FIG. 8, one (lower) hammer member 110 is shown with stop shoulder 112 engaged with a longitudinal side edge of rotatable member 107 which may be in the form of an elongated rectangle. The other (upper) member 110 of FIG. 8 shows stop shoulder 112 clearing the end face of rotatable member 107 to permit movement of hammer member 110 in the direction of rotation of member 107.

Hammer members 110 are confined or restrained in backfolded relation to rotatable member 107 during a selected portion of the angular path of rotation of the rotatable member 107 by an arcuate wall surface 114 formed on a plate 115 carried by frame 74 in spaced relationship to base member 23 and wall 75. Arcuate wall 114 is spaced a selected distance as at 115 from the correspondingly curved end edge face of the rotatable member 107. As described hereinafter each hammer member 110 upon rotation of rotatable member 107 by the motor means 80 will disengage arcuate wall 114 and will be flung at an accelerated rate of speed by centrifugal force about its pivotal connection 111 against end face 118 of sound pin 29 to strike pin 29 on the inner surface of cylindrical portion 52 as indicated in FIG. 6 and 9.

Sound pin 29 may include a head 119 adapted to seat in retracted position against a sleeve bushing 120 carried in a thickened section 121 of annular rib 70. Pin 29 is provided a loose sliding fit with bushing 120 and in this example is disposed with the axis of the pin lying along a diameter of the unit. The outer face of head 119 may be part spherical form having a radius slightly less than the radius of the internal surface of cylindrical portion 52 so that pin 29 will strike such surface on a small area thereof to produce a clear sound.

The thermal-responsive means 31 and the trigger means 30 may be best explained from consideration of FIGS. 6 and 7. Thermal-responsive means 31 may include an outer circular member 125 which may be secured in suitable manner to bushing 58 and which may include a bimetallic normally convex thermal-responsive element 126 disposed forwardly of bore 127 which carries slidable pistonlike headed element 60. The forward end of pin 61 has a rounded or tapered shape to cooperate with a correspondingly shaped recess in element 60 for alignment therewith. Extending rearwardly from element 60 is the axial pin 61 which extends through an axial bore in shaft 78 and out of contact with said bore to a collar means 128.

Collar means 128 (FIG. 14) includes a flanged bushing having an internal annular shoulder 129 upon which is seated a trigger member 130 having a port through which the sell sleeve 1290 of the bushing extends. Sleeve 129a also extends through an opening in base member 23 and is secured by a suitable nut which is seated on bar 131. The collar means is held against rotation by suitable flats 12% on sleeve 129a and on edges of ports in member 130 and bar 131. An adjustment screw 129a is threaded in sleeve 129a and has a conical recessed end 129d to receive a pointed top end 610 for axial alignment of pin 61. Thus pin 61 virtually floats between element 60 and collar means 128. When'the thermal-responsive means is actuated, axial alignment of pin 61 is provided and free unrestrained and nonbinding shifting of the pin is assured.

One end of trigger member 130 may be secured to base member 23 as at 132 (FIG. Trigger member 130 has adjacent its point of securement an inward offset 133 and beyond collar 120 a second inward offset 134 which normally positions trigger end 135 to engage hammer member 110 as at 136 (FIG. 4). Thus in wound condition of spring motor 00 and in normal ambient temperatures the thermal-responsive means 31 permits floating pin 61 to be forwardly displaced by the resiliency of trigger member130 so that trigger end 135 restrains the rotatable member 107. from rotation by contact with a hammer member.

When a selected temperature is reached indicating a tire condition, such as 134 F., the bimetallic disc snaps into reverse configuration to provide a forwardly facing concave shape as shown in FIG. 7. Depression of the bimetallic disc causes headed element 60 to be displaced rearwardly to contact pin 61 as at 130 and to push and displace trigger member 130 rearwardly to lift the trigger end 135 away from hammer member 110 to release rotatable member 107 for rotation an to thereby sound the alarm.

Manual release means for testing the alarm is best shown in FIG. 9 wherein a radially extending member 140 is slidably mounted within a rear generally simicircular back chamber 141 defined by a back wall 142 spaced from base member 23. Member 140 U-shaped an inner tapered wedge end face 143 which engages an upturned end 144 of manual release member 131. When the came face is urged radially inwardly,

the member 131 is lifted away from base 23 and engages outer A nut 145 of collar means 128 to cause collar 128 to lift trigger member 130 out of its engaged position with hammer member 110. Member 140 may be normally biased radially outwardly by a U-shaped spring 147 (FIG. 9) having one end engaged with a partition wall 148 of the rear chamber as at 149 and the other end of the U-shaped spring being engaged in a notch 150 formed in a crossbar 151 formed integrally with member 140. Crossbar 151 seats against outer wall 152 of the chamber and serves as a stop to limit outward movement of member 140. Externally of wall 152, member 140 is provided with a suitable finger tab for readily grasping the same to push the member 140 inwardly to test and release the trigger member. Member 140 may be guided by partition 148 and by outer wall 152 in suitable manner.

Means to visually indicate that the alarm is in wound or unwound condition is best shown in FIGS. 4, 9 and 10. Flag member 155 is normally retracted behind an extension of wall 142 when the alarm is in wound condition. Flag member 155 includes an enlarged circular end 156 and a staff 157 connected at its end to a forwardly extending pin 150 pivotally mounted in a ported boss 159 on base 23. The lower end 160 of pin 158 may be laterally disposed for contact with the spring housing 80. In wound condition of the alarm, the end 160 may be positioned in the space between straps 03 and resting on the outer turn of the spring as shown in FIG. with flag member 155 inwardly of the periphery of the alarm device. When the motor casing 00 commences to rotate upon operation of the alarm, a strap 83 of the motor casing 00 will strike end 160 and cause the flag to be ejected out of the opening in the back chamber (FIG. 4). Thus, when the alarm is in unwound condition, the flag is shown, and when it is partially unwound, such as by a one-fourth turn of the motor casing, the flag 155 will be exposed and visible from the front of the alarm.

Operation of the fire detection alarm means and particularly the operation of the strike means 28 should be particularly noted. Generally, the spring motor 80 may be wound by turning the outer shell means 22 in a clockwise direction under ambient temperature conditions wherein the trigger end 135 is normally in position to contact hammer member 110. Ratchet member 54 holds the spring motor in wound condition through the dog 91. In such wound condition the outer diameter of the coil spring is reduced and the visual flag 155 is retracted with its lateral end 160 in contact with the outer turn of the spring as shown in FIG. 11. Upon winding the spring to full tension, the flag may be pushed into retracted position in its chamber. In the event a strap 83 is in the way of end 160, the manual release bar may be actuated to permit the spring casing to turn just enough to avoid contact of end 160 with strap 03.

When the bimetallic disc 126 senses a fire temperature condition and its response thereto is transmitted through floating pin 61 to trigger member 130 to release trigger end 135 from hammer member 110, the spring motor will commence to unwind and will expose flag 155. During unwinding the motor casing rotates and drives the gear train to rotate rotatable member 107. In a start position as shown in FIG. 4 the heads of both hammer members 110 are in frictional contact with wall 114 and thereby produce a frictional drag resisting turning of rotatable member 107. As rotatable member 107 rotates through approximately 60 the head of the leading hammer member reaches a point of escapement at 170 (FIG. 12). At this point in its path of rotation the head of the leading hammer member 110 becomes free to move in response to centrifugal forces imparted to the hammer members by rotation of rotatable member.107. Also at this point in the path of rotation the center of inertia of the head 110a of hammer member 110 lies approximately from end face 118 of sound pin 29, the vertex of the angle measured being the axis of rotation of rotatable member 107. Before the point of escapement of hammer member is reached it will be noted that hammer 110 is in backfolded, coiled, or cocked position or relationship with member 107. From start position member 107 has turned through approximately 60 or more, and as hammer 110 leaves the point of escapement 170, the hammer member is rapidly accelerated by centrifugal forces to move about is pivotal connection relative to rotatable member 107 so that the center of inertia of the hammer head will move through a linear path approximately three times that of the end of member 107. During such movement from a coiled, cocked position the hammer member rapidly accelerates so as to produce a sharp forceful blow on end 118 of sound pin 29. The relationship between the rotation of member 107 and accelerated rotation relative thereto of hammer member 110 is such that the direction of the force at the moment when the hammer head strikes end 118 lies approximately in the direction of and in alignment with the longitudinal axis of pin 129 so that pin'129 is driven through bushing to strike the inner surface of out shell means 22. This particular relationship is important because if the direction of force of hammer member 110 were at a substantial angle to the axis of pin 29, pin 29 would become bent .or damaged after repetitive blows so that the pin would not freely slide in bushing 120.

During the strike cycle ,of the leading hammer member 110 it will be apparent that the second hammer member 110 will be frictionally engaging arcuate wall 114 and thus still serving to restrain rotation of the various elements of the gear train. Restrained rotation is desirable in order to lengthen the time cycle of the alarm. During the movement of the hammer member 110'in engagement with the arcuate wall 114 the center of mass or inertia of the hammer head lies a distance from the axis of rotation of member 107 which distance is approximately equal to the distance between the axis of rotation of member 107 and the pivotal connection of the hammer member thereto. In such coiled or cocked position of the hammer members 110 with their center of mass at such distance from the axis of rotation of member 107 it will be apparent that the hammer heads 110a also serve as governors to regulate, control or to modify the rate of rotation of the rotatable member 107. In this respect it should be noted that the weight distribution of each hammer member is such that the hammer head 110a has approximately two-thirds of the weight of the hammer member and the other one-third of the weight is disposed in the remaining shank portion of the hammer member. As noted in FIG. 13 the hammer head has additional thickness as compared to the shank portion.

It should also be noted that when one of the hammer members is freely swinging about its pivotal connection prior to striking the end of pin 29, that the inertia mass of the head 110a becomes increasingly spaced from the axis of rotation of member 107 and thereby likewise tends to produce an accelerating effect upon the driven rotation of the member 107.

When hammer 110 strikes pin 29 it is preferable that the impact occurs on the radius of the head just beyond the shank as at 174 Thus the impact action includes a hitting and swiping action because of the curvature of the head. After impact the hammer bounces back almost to its precoiled or cocked position. As member 167 continues to rotate during the hitting action, the hammer head may then engage arcuate wall 114 at about 175(F1G. 12). The effective are through which hammer heads frictionally engage wall 114 may be between 180 to 190.

To exemplarily illustrate the action occurring during unwinding of the alarm a selected rate of rotation of member 107 may be about 180 r.p.m. When a hammer leaves point 170 the speed increases momentarily as by a jerk, to about 200 r.p.m. Such irregular rotation continues until the spring is exhausted to about 20 r.p.m. However, during the major portion of the alarm cycle, the rate of rotation is uniform (i.e., 180 rpm. 120 r.p.m.). Since such speed of rotation is related to the striking force of the hammer on the pin, it is also related to the sound or decibel level produced. In the exemplary cycle of about 7 minutes variation in decibels was small, e.g., about 2 decibels. lt will be understood that the above characteristics are illustrative only and are not limiting.

In an exemplary embodiment of the invention, it has been found that the hammer approximately triples its speed immediately prior to striking pin 29 and after leaving the point of escapement 170. It has also been found that by decreasing the weight mass of the hammer head, the time cycle decreases so that the alarm rings for a shorter period of time. When the weight of the hammer head mass was increased, the time period of the alarm was increased. Such response illustrates the action of the hammer members as governor members.

The alarm means of the present invention may be readily wound without removal from its mounting bracket by turning the outer shell 22 and the chance of possible damage thereto by dropping or handling is substantially lessened. The alarm may be quickly manually tested for operation by the manual release means while the alarm is on the mounting bracket. It will also be apparent that the construction of the alarm permits mounting and operation thereof in any desired position.

It will also be apparent that various means may be employed to increase the friction between the arcuate wall 114 and the hammerhead portion in contact therewith so as to retard the dissipation of energy of the spring motor and that the relationship between the axis of rotation of member 107, end face of pin 109 in retracted position, and radius of arcuate wall 114 may be varied in order to produce selected results.

It will be understood by those skilled in the art that various modifications and changes may be made in the alarm means described above which may come within the sphere of this invention and all such changes coming within the scope of the appended claims are embraced thereby.

We claim:

1. In a fire detection alarm means, the combination of:

an outer rotatable shell means adapted to be struck to produce an alarm sound;

an inner nonrotatable sealed unit received within said shell and comprising an inner housing and a base member;

a sounding pin slidably mounted on said inner housing and movable to strike the shell means;

drive means within said inner housing and connected to and energized by rotation of said outer shell member;

strike means within said inner housing for repetitively striking one end of said pin and for controlling discharge of energy from said drive means;

said strike means including a driven member rotatable by said drive means,

a hammer member having a pivotal connection on said driven member for pivotal movement relative thereto;

and means to maintain said hammer in a cocked position during movement of said driven member through a selected angle of rotation and to release said hammer at a selected position in the path of rotation of said driven member whereby said hammer will be thrown against said pin at a speed greater than the speed of rotation of the driven member.

2. In a device as stated in claim 1 wherein said hammer member includes a shank portion and a head portion,

said shank portion having at one end said pivotal connection to said driven member,

and said head portion having a weight greater than said weight of the shank portion.

3. In a device as stated in claim 1 wherein one of said hammer members is pivotally mounted at each end of said driven member.

4. In a device as stated in claim 2 wherein, in hammercocked position, the distances between the center of mass of said head portion, the pivotal axis of said hammer member, and the pivotal axis of said driven member are substantially equal.

5. In a device as stated in claim 4 wherein said means for cocking said hammer positions the center of mass of said head portion from said drive axis the same distance as the center of mass of said head portion is spaced from the pivotal axis of said hammer member.

6. ln a device as stated in claim 1 wherein said means for maintaining said hammer member in cocked position frictionally engages and restrains rotation of said driven member.

7. In a device as stated in claim 1 wherein an end face of said hammer member in normal retracted position lies along a diameter passing through the drive axis of said link member,

said hammer member being confined by said position maintaining means through an arcuate path extending beyond a diameter normal to said first-mentioned diameter whereby upon release of said head portion of said hammer, said hammer is swung in response to centrifugal forces at increased speed toward the end face of the hammer member.

8. In a device as stated in claim 1 wherein said drive means includes a spiral spring motor contained within a motor cas- 8;

said motor casing being connected with said outer housing for rotation therewith,

said motor casing being normally restrained against rotation and being rotatable upon release.

9. In a device as stated in claim 1 including a normally exposed signal member,

and means to retract said signal member upon operation of said alarm.

10. In a device as stated in claim 1 including a thermalresponsive means carried on the said shell;

a trigger means on said base member in normally holding engagement with a hammer member;

and means interconnecting said thermal-responsive means and said trigger means.

11. In a fire detection alarm means the combination of:

an outer sound shell means;

an inner housing and a base member associated therewith;

a sounding pin movably mounted on said inner housing to strike said shell means;

drive means within said inner housing;

and means within said inner housing, connected with said drive means, and rotatable thereby for repetitively striking one end of said pin and for regulating speed of rotation of said rotatable means;

said rotatable means including a hammer member held in a cocked position during movement through a selected angle of rotation and released into an uncocked position whereby in response to centrifugal forces said hammer member is forcibly driven against said pin.

12. in combination with an alarm means having a movable sounding pin and a drive means including a driving axis of rotation, the provision of:

a driven member rotatable aboutsaid driven axis of rotation; V

an arcuate wall spaced from the periphery of the path of rotation of said rotatable member;

hammer means having a pivotal connection to said rotatable member and in spaced relation to said driven axis;

said hammer member having a head portion slidably frictionally engageable with said arcuatewall and swingable relative to said rotatable member for striking said pin when said head portion is out of engagement with said arcuate wall.

13. In a device as stated in claim 12 wherein said hammer member includes a head portion with a center of mass spaced from said pivotal connection a distance substantially equal to the distance between said pivotal connection and said driven axis.

14. In a device as stated in claim 12 wherein said arcuate wall terminates in the angular path of rotation about said driven axis approximately before the end of said pin to be struck by said hammer member.

15. In a device as stated in claim 10 wherein said interconnecting means includes a floating pin; and

means for adjusting the longitudinal displacement of said UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,570,446 Dated March 16, 1971 Inve t r Wesley E. Buford and Charles G. Butorcl I It is certified that error appears in the aboveidentified patent and that said Letters Patent is hereby corrected as shown below:

Column 2, line 9, delete [enlar e] and insert --enlarged-- same column 2, line 36, delete Fthermal-respons ive] and insert --the-- same column 2, line 65, delete [U-shaped] same column 2, line 72, delete [an] and insert --and-- Column 4, line 63, delete [sell] Column 5, line 19, delete [an] and insert --and-- same. column 5, line 23, delete [simicircular] and insert --semicircular-- same column 5, line 25, delete [U- shaped] and insert "includes-- same column 5, line 27 delete [came] and insert --cam-- Column 6, line +6, delete [out] and insert --outer-- Signed and sealed this 7th day of March 1972.

( E Attest:

EDWARD M.F'LETCHIER,JR. ROBERT GOT'I'SCHALK Atte sting Officer Commissioner of Patents

Claims

1. In a fire detection alarm means, the combination of: an outer rotatable shell means adapted to be struck to produce an alarm sound; an inner nonrotatable sealed unit received within said shell and comprising an inner housing and a base member; a sounding pin slidably mounted on said inner housing and movable to strike the shell means; drive means within said inner housing and connected to and energized by rotation of said outer shell member; strike means within said inner housing for repetitively striking one end of said pin and for controlling discharge of energy from said drive means; said strike means including a driven member rotatable by said drive means, a hammer member having a pivotal connection on said driven member for pivotal movement relative thereto; and means to maintain said hammer in a cocked position during movement of said driven member through a selected angle of rotation and to release said hammer at a selected position in the path of rotation of said driven member whereby said hammer will be thrown against said pin at a speed greater than the speed of rotation of the driven member.

2. In a device as stated in claim 1 wherein said hammer member includes a shank portion and a head portion, said shank portion having at one end said pivotal connection to said driven member, and said head portion having a weight greater than said weight of the shank portion.

4. In a device as stated in claim 2 wherein, in hammer-cocked position, the distances between the center of mass of said head portion, the pivotal axis of said hammer member, and the pivotal axis of said driven member are substantially equal.

6. In a device as stated in claim 1 wherein said means for maintaining said hammer member in cocked position frictionally engages and restrains rotation of said driven member.

7. In a device as stated in claim 1 wherein an end face of said hammer member in normal retracted position lies along a diameter passing through the drive axis of said link member, said hammer member being confined by said position maintaining means through an arcuate path extending beyond a diameter normal to said first-mentioned diameter whereby upon release of said head portion of said hammer, said hammer is swung in response to centrifugal forces at increased speed toward the end face of the hammer member.

8. In a device as stated in claim 1 wherein said drive means includes a spiral spring motor contained within a motor casing; said motor casing being connected with said outer housing for rotation therewith, said motor casing being normally restrained against rotation and being rotatable upon release.

9. In a device as stated in claim 1 including a normally exposed signal member, and means to retract said signal member upon operation of said alarm.

10. In a device as stated in claim 1 including a thermal-responsive means carried on the said shell; a trigger means on said base member in normally holding engagement with a hammer member; and means interconnecting said thermal-responsive means and said trigger means.

11. In a fire detection alarm means the combination of: an outer sound shell means; an inner housing and a base member associated therewith; a sounding pin movably mounted on said inner housing to strike said shell means; drive means within said inner housing; and means within said inner housing, connected with said drive means, and rotatable thereby for repetitively striking one end of said pin and for regulating speed of rotation of said rotatable means; said rotatable means including a hammer member held in a cocked position during movement through a selected angle of rotation and released into an uncocked position whereby in response to centrifugal forces said hammer member is forcibly driven against said pin.

12. In combination with an alarm means having a movable sounding pin and a drive means including a driving axis of rotation, the provision of: a driven member rotatable about said driven axis of rotation; an arcuate wall spaced from the periphery of the path of rotation of said rotatable member; hammer means having a pivotal connection to said rotatable member and in spaced relation to said driven axis; said hammer member having a head portion slidably frictionally engageable with said arcuate wall and swingable relative to said rotatable member for striking said pin when said head portion is out of engagement with said arcuate wall.

14. In a device as stated in claim 12 wherein said arcuate wall terminates in the angular path of rotation about said driven axis approximately 90* before the end of said pin to be struck by said hammer member.

15. In a device as stated in claim 10 wherein said interconnecting means includes a floating pin; and means for adjusting the longitudinal displacement of said pin.