US2456038A - Portable fire alarm device - Google Patents

Description

Dec. 14, 1948. R. E. YOUNG 2,456,038

PORTABLE FIRE ALARM DEVICE lFiled May 29, 1947 Patented Dec. 14, 1948 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to improvements in alarm signal devices and more particularly to an improved unitary. electrically operated fire alarm signal device adapted to be plugged into an electrical convenience outlet and supported thereby to give an audible alarm ii subjected to a temperature indicating the presence of fire in the space contiguous thereto.

It is among the objects oi. the invention to provide an improved, electrically operated, portable signal device which may be plugged into a conventional electrical convenience outlet to be bodily supported by the outlet or which may be supported at some location remote from an outlet and electrically-connected thereto by a suitable extension cord, which will give a loud, clear, continuous and distinctive audible signal when the temperature in the space contiguous thereto exceeds a predetermined value, which is simple in construction and includes a minimum number of simple parts most of which are of conventional design readily available on the market, which is neat and attractive in appearance and may be installed without any changes in or additions to the wiring of the building or other structure in which it is used.

Other objects and advantages will become apparent from a consideration of the following description in conjunction with the accompanying drawing wherein:

Figure l is a longitudinal cross-section of an alarm signal device illustrative of the invention taken substantially on the lines i-i of Figure 2.

Figure 2 is a transverse cross-section taken substantially on the line 2-2 of Figure 1.

Figure 3 is a fragmentary cross-section taken substantially on the line 3-4 of Figure 2, and including an end elevation of a thermostatic switch constituting an operative component of the device. 7

Figure 4 is a fragmentary cross-section taken substantially on the line 4-4 of Figure 2 including a top plan view of the thermostatic switch shown in Figure 3.

Figure 5 is a fragmentary cross-section on the line H of Figure 1 showing an end elevation of an electro-magnetic vibrator constituting an operative component of the device.

Figure 6 is a diagrammatic wiring diagram of the electrical components of the device.

Figure 7 is a rear elevation of a fragmentary portion of the device showing the adjustment of the thermostatic switch shown in Figures 3 and 4.

With continued reference to the drawings the device has an enclosing casing comprising a hol- 2 low ventilated front cover member l0 detachably secured to a flat backing plate ll preferably formed of insulating material. The backing plate may be centrally provided on its rear back side with a re-inforcing plate l2 providing a second plate portion through which extends a pair of prongs or fingers l3 adapted to be received in a conventional electrical convenience outlet to electrically energize the alarm device and simultaneously support the device from the convenience outlet.

A transformer generally indicated at It is secured to the casing and has one side of its primary winding l5 electrically connected by a conductor It with one of the fingers It. The other finger i3 is electrically connected by a conductor I! with one contact l8 of a thermostatic switch generally indicated at it, the other contact 20 of which is connected by a conductor 2i with the opposite side of the transformer primary winding l5.

In the thermostatic switch illustrated the contact i8 is a fixed contact supported on the backing plate ii and the contact 20 is a movable contact carried at the outer end of a coiled bi-metallic strip 22 the opposite end of which is secured to a rotatable pin 23 Journaled in a bushing provided in the backing plate i I and having at the outside of the backing plate a head provided with a transverse slot 24 by means of which the pin may be rotated to adjust the switch. A dial 2! is mounted on the outside of the backing plate surrounding the pin 23 and is properly indexed to indicate the setting of the thermostatic switch. A pointer 20 may be attached to the pin and movable over the dial indicia to accurately indicate the switch setting.

With the arrangement above described, when the bi-metallic element 22 brings the contact 20 against the fixed contact ill the circuit including the primary winding I! of the transformer ll will be closed.

A pair of parallel solenoid coils 21 are secured to the casing and a vibrator bar-28 extends across the outer ends of these coils. One end oi the bar 28 is rigidly connected to the corresponding end of a leaf spring 29 the opposite end of which is secured to a fixed bracket 30. A movable contact 3| is carried by the bar 28 opposite a fixed contact member 32" which provides a limit stop for movement of the bar away from the adjacent end of the coils 21. An electrical conductor 33 connects the fixed contact 32 with one side of the secondary winding of the transformer i4 and a conductor connects one side of the coils 21 mucosa ductor It connects the opposite side of the coils with the opposite side of the secondary winding. Thus, when the circuit including the primary winding ll of the transformer is closed the secondary winding will be energized and when the contacts Ii and 82 are together current will flow 4 is quickly and positively responsive to any temperature rise above the temperature value tor which it is set.

' The invention 'may be embodied in other specinc, terms without departing from the spirit or essential characteristics thereof. The presthrough the secondary winding and throughthe coil. 21 energizing the cells to attract the bar It thereby separating the contact 8! from the contact 02 and interrupting the coil energizing circuit. This causes the bar 20 to vibrate in the conventional manner of bumers, bell ringers. and similar devices. 7

Bar 10 is resiliently urged away from the coils 21 by a compression spring interposed between the outer end of the bar and a fixed bracket or abutment 38, the strength oi. spring 31 being suiiicient to quickly move the bar away from the coils but insumcient to prevent movement of the bar by the magnetic attraction of the coils when energized. This spring has the effect of increasing the rapidity of vibration oi the bar 20 and thereby raising the pitch oi the audible signal produced by the device. A flat plate 8. is secured to the bar II and projectslaterally therefrom to magnify the sound effect produced by vibration or the bar.

While the device is particularly useful as a portable ilre alarm. it maybe given a sumciently wide range of adjustment, as for example, the range included between 70 and 220 Fahrenheit as indicated in Figure 7, which would render it'usei'ul for various other purposes. For example, the device might be placed in a broader house to give an alarm if the temperature within the house reached a value dangerous to the health 0! chicks housed therein or could be used in a green-hoube, tobacco curing bar, or any other structure or building in which it is necessary or desirable to keep the temperature below a predetermined maximum value.. Y r

The device is light in weight, neatsndattractive .in appearance, and completely portable -so that it may be quickly and easily installed in any out embodiments are. therefore. to be considered in all respects as illustrative and not restrictive, the scope oi the invention being indicated by the appended claim rather than by the ioregoing description, and all changes which come within the meaning and range of equivalency of the claim are, therefore, intended to be embraced therein.

What is claimed:

A portable. unitary alarm device for indicating a temperature above a predetermined value in the space contiguous thereto comprising a casing having a back plate and a front cover detachablv secured to said back plate. a pair of fingers projecting from the back side of said plate for reception in an electrical convenience outlet to 4 support and electrically energize said device, a

location in which there is a conventional electrical convenience outlet plug. It requires nochanges in or additions to the ordlnaryhouse wiring and transformer mounted at the front side of said plate, an electrical connection between one oi said fingers and one side 01' the primary winding of said transformer, an adjustable thermostatic switch mounted on theiront side oi said plate. an electrical connection between one contact of said switch and the other side of said primary winding, an electrical connection between the other contact 01" said switch and the other of said fingers. an electro-maanetic vibrator mounted at the front side 01' said plate, and electrical connections between said vibrator and the opposite sides of the secondary winding of said transformer to operate said vibrator upon closing of said thermostatic switch.

RICHARD a. YOUNG.

REFEREivcEs crrrm The following references are of record in the file of this patent:

UNITEDSTATES PATENTS

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