US2084198A - Fire alarm system - Google Patents

Description

June 15, 1937. A. JOHNSON 2,034,198

' FIRE ALARM SYSTEM Filed Jan. 22. 1956 fi/exawdenJo/msm HIS WM;

Patented June 15, 1937 UNITED STATES PATENT OFFIE 2 Claims.

This invention relates to an improvement in fire alarm systems and more particularly to circuit closing devices therefor.

The preferred embodiment of the invention discloses a circuit closing device which may be connected in any previously installed signal sys tern such as door bell, call bell, telephone, etc. and comprises a device adaptable for wall mounting having means automatically operable to comm plete or close a circuit when the temperature in the room in which the device is installed rises above a predetermined point.

The device as shown in the drawing may, for home installation, be inserted into a door or call bell circuit, being arranged in parallel with the circuit closer already in use in the system, a diagrammatic View of such an installation being shown in the drawing.

One of the objects of the invention lies in the provision of a circuit closing device which may be conveniently installed with its own circuit and alarm or in any other bell ringing system.

Another object of the invention lies in the provision of a circuit closing device which is compact and which when installed presents no unsightly or objectionable appearance.

Another object of the invention lies in the provision of a circuit closing device which is positive in action over an indefinite period of time.

Other and further objects of the invention will be more fully understood from a consideration of the following specification taken in conjunction with the accompanying drawing and in Which Fig. l is a fragmentary view of a building wall showing one possible location of one form of the invention in conjunction with an alarm.

Fig. 2 is a fragmentary, sectional View of the circuit closing device taken substantially on the line 22 of Fig. 4;

Fig. 3 is a bottom view of the device taken substantially as indicated at 3-3 of Fig. 2;

Fig. 4 is a transverse, sectional View taken substantially on the line i4 of Fig. 2;

Fig. 5 is a further transverse, sectional view taken on the line 5-5 of Fig. 2; and

Fig. 6 is a diagrammatic View showing one method of including the circuit closing device in a previously set up signal system.

so Referring to the drawing, the reference numeral I0 is employed to generally indicate a circuit closing device which for purposes of illustration is shown to be mounted on a building Wall II. An alarm in the form of an electric bell or buzzer I2 is shown mounted above the device it. It will be understood, however, that the bell l2 may be located at any point in the room it is desired to protect or may take the form of a light or buzzer on a switchboard employed in hotels, ofiice buildings, schools, etc. Re- 5 ferring particularly to Fig. 6 of the drawing, it will be understood that the contact device It is in parallel with a push button or other signal actuator 13. The common leads M from both contact closures are connected through lead 5 to a source of current supply shown as a battery it. From the battery It lead I? connects one terminal of bell I2. Common leads l8 from the actuator 63 and circuit closing device It connect with the bell l2 through lead [9. It is 15 apparent that the circuit closing device may be arranged in a separate circuit or that several of these devices may be included in one circuit and located in different parts of a building, one or all of them serving to close the circuit and start the alarm bell E2.

The circuit closing device Iii is shown in detail in Figs. 2 to 5 of the drawing inclusive and comprises a receptacle 2|. The receptacle is open along the bottom side only and is interiorly provided with a plate 22 which is secured along flange 23 to the under face of the top 24 of the receptacle. This plate projects downwardly of and terminates slightly beneath the lower edge of the walls of the receptacle. In that portion 30 of the plate located beneath the receptacle a substantially key shaped slot 26 is made. A ball 2'! is mounted in the slot 25, the head 28 thereof preventing lateral withdrawal in one direction and the spread ends 29 preventing withdrawal in the opposite direction. Centrally of the plate 22 a transverse opening 3! is provided, being defined by an annular rim or flange 32. Projecting through the opening 3! is a fiber or other electrical non-conducting cylinder 33. The cylin- 4O der projects slightly past the center of the receptacle 2! and supports a rod 35. One end of the rod 35 is formed into a terminal 36 to which the electrical connector or lead 18 is attached. The other end of the rod 35 projects beyond the cylinder 33 and has secured to its end a member 3?. This member is formed with flanges 38 which serve to prevent lateral twisting with respect to the rod 35, the rod and member being joined together in any suitable manner as by welding or soldering. The member 31 is formed with a flat rectangular portion 40 from three sides of which project contact flanges 4|. On the fourth and lowermost side of the member the flange is omitted for purposes hereinafter more fully ex- 55 plained. Secured to the rear face of the portion 48 is a sleeve 43 which encloses one end of the cylinder 33. Encircling the annular flange 32, cylinder 33 and collar 43, is an expansion 5 spring 44. It is evident from the above description that since one end of the spring 44 is seated against the fixed plate 22, the spring energy will cause collar 43, member 31, and rod 35 to move laterally toward the right of Fig. 2 of the drawing.

Adjacent the opposite end from plate 22 is a further plate 46. This plate is secured along flange 4! to the under face of the top wall 24 of the receptacle. This plate also projects beneath the lower edge of the receptacle, being provided with a key slot 48 and bail 49 which is identical with the bail 21 above described. Centrally of the plate 46 is an opening 5| which is defined by an annular flange 52. The opening 5| receives a fiber or other insulating sleeve 53 through which a stationary rod 54 projects. One end of the rod adjacent the end of the receptacle is l formed with a terminal 56 from which the electrical connection or lead |4 extends. The inner end of the rod 54 terminates in a plate 51' which is welded or otherwise suitably secured thereto. This plate is rectangular in shape and formed with angularly directed contacts 58, being similar to the contacts on the plate 3?. The contacts 58 are preferably three in number, none projecting from the lowermost edge. It will be noted that plate 51 is somewhat smaller than plate 3'! and consequently the contacts 56 are slightly closer together than contacts 4%. Thus, when the spring 44 urges plate 3'! toward the right as shown in Fig. 2 of the drawing, the contacts 4! will have sliding engagement with contacts 58.

In the event that dirt or any other nonconducting substance has accumulated on the contacts,

the sliding action of contacts 4| with respect to contacts 58 will clean the metal and provide proper electrical connection as between lea-d l4 and lead I8 through rod 54, contacts 58 and 4| and rod 35.

,5 It is evident that the rod and plate 31 may have a tendency to rotate during movement thereof through action of spring 44. To prevent this the rod, cylinder 33 and flange 32 may be made rectangular or as shown in the drawing,

said rod may be fitted with a pin 59 which will be slidable longitudinally of a slot in said cylinder.

In order to normally prevent contacts 4! and 58 from completing the circuit, a fuse 653 is inserted between the adjacent faces of plates 31 and 51.

This fuse is preferably formed from a substance or combination of substances which will become soft and flowable when the air surrounding it reaches a predetermined temperature reading. The fuse is held in place solely by pressure con- 60 tact of the two plates through spring 44 and, during the process of changing from solid to flowable state will become thinner and tend to flow downwardly of the straight surfaces of the plate allowing the three contacts 4| to engage corresponding contacts 58.

Directly beneath the receptacle 2| and connected with the bails 21 and 49 is a highly inflammable material Bl such as wool fibers. These fibers may be treated to increase the inflammableness and being beneath the fuse 60, will, when ignited, cause said fuse to more quickly change to a flowable state and thus increase the rapidity with which an alarm is sounded. Thus, should a small flame having insufficient heat to melt the fuse 60, occur adjacent the receptacle 2|, said flame will, however, ignite the material BI and thus melt the fuse to close the circuit and actuate the alarm.

It is evident that the type of receptacle, mountings for the relatively movable rods, and contour and number of contacts, as well as other details of the invention may be modified or altered to suit various requirements and conditions without departing from the spirit and scope of the invention as set forth in the hereunto annexed claims.

Having thus set forth my invention what I claim as new and for which I desire protection by Letters Patent is:-

1. In an alarm system, an electrical circuit closing device comprising a receptacle, aligned relatively fixed and movable rods mounted in said receptacle, means connecting said rods in a circuit of said system, contacts terminating the adjacent ends of said rods, flanges projecting beyond said contacts, the flanges of one contact being inclined to and slidably engageable with the flanges of the other contact, a spring for urging one of said contacts toward the other to engage said flanges and non-conducting means between said contacts, said means, upon a predetermined advance in temperature, becoming plastic and permitting engagement of said flanges and the closing of a circuit in said system.

2. In an alarm system, an electrical circuit closing device comprising a receptacle, plates adjacent opposite ends of said receptacle, a rod rigidly secured to one of said plates, a sleeve formed from non-conducting material projecting through the other of said plates, a rod projecting though said sleeve, means connecting each rod in a circuit of said system, contacts terminating the adjacent ends of the rods, inclined flanges on said contacts, the flanges of one contact being slidable along the flanges of the other contact, a spring encircling said sleeve, said spring being engaged with and urging one of said contacts towards the other, and non-conducting means between said contacts and adapted to space said flanges, said means, upon a predetermined advance in temperature becoming plastic and permitting engagement of said flanges and the closing of a circuit in said system.

ALEXANDER JOHNSON.

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