FIRE AND SMOKE ALARM DEVICE
United States Patent 3659278
A fire and smoke alarm device which is activated by the presence of smoke and/or excessive heat. The device includes a housing having an air sampling chamber and means therein to induce the flow of air therethrough. A fire sensing means is provided in the air sampling chamber which will activate an alarm circuit when the temperature in the chamber reaches a predetermined level. A sealed and insulated temperature controlled compartment is also provided in the housing and has a photoelectric cell therein which will activate an alarm circuit upon the cell sensing a predetermined light intensity in the air sampling chamber. The air sampling chamber has a light source mounted therein which illuminates a portion of the chamber. A clear lens is positioned between the air sampling chamber and the compartment for admitting light into the compartment so that the photoelectric cell can sense the light intensity in the air sampling chamber. Means is provided for maintaining the temperature in the compartment at 120° F. so that the photoelectric cell will function with the required sensitivity.
US Patent References:
Signalling apparatus incorporating a differential relay
Giuffrida - December 1965 - 3222662
Smoke and heat detection unit
Roberts - May 1968 - 3383670
Thermal compensation system
Downey - September 1951 - 2568435
Temperature control oven
Craiglow et al. - May 1967 - 3322982
Signalling apparatus incorporating a differential relay
Giuffrida - December 1965 - 3222662
Smoke and heat detection unit
Roberts - May 1968 - 3383670
Thermal compensation system
Downey - September 1951 - 2568435
Temperature control oven
Craiglow et al. - May 1967 - 3322982
Application Number:
05/028865
Publication Date:
04/25/1972
Filing Date:
04/15/1970
View Patent Images:
Export Citation:
Assignee:
Jensen Industries, Inc. (Des Moines, IA)
Primary Class:
Other Classes:
250/577, 340/630
International Classes:
G08B17/107; G08B17/103; G08B21/00
Field of Search:
340/237S 250/218,238 331/69 356/207
Primary Examiner:
Caldwell, John W.
Assistant Examiner:
Myer, Daniel
Claims:
I claim
1. A heat and smoke alarm device, comprising,
2. The device of claim 1 wherein said compartment has a thermostatically controlled heating element therein adapted to maintain the temperature in said compartment at a predetermined temperature.
3. The device of claim 2 wherein a heat conductive bracket means connects said heating element and said photoelectric cell so that heat is conducted to said cell to maintain said cell at a predetermined temperature.
4. The device of claim 2 wherein said predetermined temperature is 120° F.
5. The device of claim 3 wherein said bracket means maintains said photoelectric cell in position adjacent said lens.
1. A heat and smoke alarm device, comprising,
2. The device of claim 1 wherein said compartment has a thermostatically controlled heating element therein adapted to maintain the temperature in said compartment at a predetermined temperature.
3. The device of claim 2 wherein a heat conductive bracket means connects said heating element and said photoelectric cell so that heat is conducted to said cell to maintain said cell at a predetermined temperature.
4. The device of claim 2 wherein said predetermined temperature is 120° F.
5. The device of claim 3 wherein said bracket means maintains said photoelectric cell in position adjacent said lens.
Description:
The smoke and fire alarm of this invention is an improvement over applicant's earlier device which was disclosed in U.S. Pat. No. 3,447,152, which issued on May 27, 1969. Applicant's earlier device functioned quite satisfactorily but the sensitivity range of the sensing elements therein varied somewhat as the components were subjected to varying temperatures. In order for a device of this type to receive Underwriters Laboratory's certification, it must function within a prescribed sensitivity range.
Therefore, it is the principal object of this invention to provide a combined fire and smoke alarm which is activated by the presence of smoke and/or excessive heat.
A further object of this invention is to provide a combined fire and smoke alarm which functions within the prescribed sensitivity range.
A further object of this invention is to provide a fire and smoke alarm including an air sampling chamber and means therein to induce the flow of air therethrough so that the air is properly sampled.
A further object of this invention is to provide a fire and smoke alarm having a temperature controlled compartment therein which houses a photoelectric cell, and other temperature effected components.
A further object of this invention is to provide a fire and smoke alarm which is electrical and which may be powered by an ordinary household wiring circuit.
A further object of this invention is to provide a fire and smoke alarm which is economical to manufacture, durable in use, efficient in operation and refined in appearance.
These and other objects will be apparent to those skilled in the art.
This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:
FIG. 1 is a perspective view of the device of this invention mounted on a wall surface.
FIG. 2 is a sectional view of the device with portions thereof cut away to more fully illustrate the invention.
FIG. 3 is an enlarged sectional view as seen along line 3--3 of FIG. 2.
FIG. 4 is an enlarged sectional view as seen along line 4--4 of FIG. 2.
FIG. 5 is a schematic drawing of the electrical circuity of this invention.
The numeral 10 generally designates the device of this invention comprising a housing 12 in which the operating components of the device of this invention may be fully housed and, for example, may be composed of metal, certain plastics, etc. Housing 12 is provided with a back 14, front 16, top 18, bottom 20, and opposite sides 22 and 24. Housing 12 is provided with an opening 26 in its bottom 20 which communicates with an air sampling chamber generally designated by the reference numeral 28. Air sampling chamber 28 includes a vertically disposed chamber portion 30 which is in communication with opening 26, and inclined chamber portion 32 which extends upwardly and laterally from chamber portion 30, vertically disposed chamber portion 34 extending upwardly from the upper end of chamber portion 32, and chamber portion 36 which is in communication with the upper end of chamber portion 34 and opening 38 formed inside 22. Air sampling chamber 28 is provided with screens 40 and 42 which prevent bugs or the like from entering the chamber but which permit the flow of air therethrough.
The numeral 44 refers to a heat sensing switch mounted in chamber portion 32 which is adapted to activate an alarm circuit upon the temperature in chamber 28 reaching a predetermined level. The numeral 46 refers generally to a heat resistor positioned in chamber portion 34. Heat resistor 46 heats the air in the chamber portion 34 to create convection currents therein which pulls the air through the opening 26, chamber portion 30, chamber portion 32, chamber portion 34, chamber portion 36 and outwardly through opening 38. A light source 48 having a focusing lens 48A thereon is mounted in the upper end of chamber portion 32 and is adapted to direct light downwardly therefrom as indicated by the arrow in FIG. 2. The numeral 50 refers to a piece of reflective material which is provided in the chamber portion 32 as illustrated in FIGS. 2 and 4.
Housing 12 also includes a sealed temperature controlled compartment or oven 52 having an insulating material extending therearound which is generally designated by the reference numeral 54. Compartment 52 includes a tubular portion 56 which extends between chamber portion 32 and the interior of compartment 52 as illustrated in FIGS. 2 and 4. A lens 58 is mounted in tubular portion 56 and is designed to permit light to pass therethrough into the interior of compartment 52. Lens 58 keeps dust off of cell 60 and seals the compartment 52. Cell 60 is a photoelectric cell mounted at the inner end of tubular portion 56 in compartment 52 adapted to sense the light intensity passing through lens 58. Cell 60 is maintained in position by the heat conductive metal bracket 62 extending thereover as illustrated in FIG. 3. Bracket 62 maintains cell 60 in proper position as well as serving as a heat conductor. Bracket 62 is secured to a heat conductive bracket 64 which supports a heating element 66 thereon as illustrated in FIG. 3. Heating element 66 is controlled by an adjustable thermostat 68 positioned in the compartment 52 so as to maintain the temperature within the compartments 52 at 120° F. plus or minus 11/4percent. The brackets 64 and 62 conduct heat from the heating element 66 to the photoelectric cell 60 so as to insure that the photoelectric cell will be maintained at the proper precise operating temperature.
In FIG. 2, the numeral 70 refers to the main or primary audio signal or horn with the numeral 72 referring to the trouble audio signal or horn. In FIG. 2, the numeral 74 refers to a transformer with the numerals 76 and 78 identifying capacitors. Numeral 80 refers to an adjustable potentiometer which is also illustrated in FIG. 2. A switch 82 is provided in bottom 20 of the housing and is movable from "test" to "reset" positions.
The wiring circuitry of the device is illustrated in FIG. 5 and merely shows the circuitry which permits the device to function. The circuitry does not form an essential part of this invention and for that reason will not be described in detail. The heart of the invention of this device is the structure and method by which the compartment 52 is maintained at 120 degrees so that the photoelectric cell 60 and other temperature effected components will function within the prescribed sensitivity range.
In operation, the device is plugged into any ordinary household circuit. The circuitry of FIG. 5 includes a trouble circuit which causes the ordinary household current to activate the horn 72 if the lamp 48 should fail. In order for a device of this type to receive Underwriters Laboratory's certification, a trouble circuit for the lamp 48 is required with a trouble circuit for power failure being an optional feature.
The operation of the device causes the heat resistor 46 to create convection currents in the air sampling chamber 28 so that the air will be drawn through the chamber 28 and properly sampled. If the temperature in chamber portion 32 rises above a predetermined level, the heat switch 44 causes the horn 70 to be activated thereby signalling that a dangerous condition exists. If smoke exists in the area around the device 10, it will be drawn into the air sampling chamber 28 as indicated by the arrows. In the absence of smoke in chamber portion 32, a certain amount of light passes through the lens 58 with the photoelectric cell 60 sensing that light intensity without activating the alarm circuit. If approximately 10 percent or less black smoke is introduced into chamber portion 32 or if 4 percent or less light smoke is introduced into chamber portion 32, the light intensity therein increases so that a greater light intensity passes through the lens 58 thereby activating the photoelectric cell 60 which in turn activates the alarm circuit so as to activate horn 70. By precisely controlling the temperature within compartment 52, it is possible to achieve the prescribed range of sensitivity necessary to obtain certification of the device. The device of this invention functions within a tolerance of 21/2 percent smoke obscurity at 70° F., and this sensitivity will not vary over a plus or minus 50 percent at either 32° F. or 120° F. Thus, the tolerance factor at 32° F. or 120° F. must be between 11/4 percent and 33/4 percent. The fact that the temperature within the compartment 52 is maintained at the 120° temperature and the fact that means is provided for conducting heat to the photoelectric cell 60 insures that the proper sensitivity range will be achieved.
It should be noted that the electrical circuit of FIG. 5 includes two voltage regulators (4.7 volts and 10 volts) to achieve 50 percent plus or minus sensitivity.
Thus it can be seen that a unique fire and smoke alarm has been provided which senses heat and smoke within a proper sensitivity range. The sensitivity is achieved by the sealed and temperature controlled compartment 52 together with the means for insuring that convection currents will be created in the chamber 28 so that the air is properly sampled. Therefore it can be seen that the device accomplishes at least all of its stated objectives.
Therefore, it is the principal object of this invention to provide a combined fire and smoke alarm which is activated by the presence of smoke and/or excessive heat.
A further object of this invention is to provide a combined fire and smoke alarm which functions within the prescribed sensitivity range.
A further object of this invention is to provide a fire and smoke alarm including an air sampling chamber and means therein to induce the flow of air therethrough so that the air is properly sampled.
A further object of this invention is to provide a fire and smoke alarm having a temperature controlled compartment therein which houses a photoelectric cell, and other temperature effected components.
A further object of this invention is to provide a fire and smoke alarm which is electrical and which may be powered by an ordinary household wiring circuit.
A further object of this invention is to provide a fire and smoke alarm which is economical to manufacture, durable in use, efficient in operation and refined in appearance.
These and other objects will be apparent to those skilled in the art.
This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:
FIG. 1 is a perspective view of the device of this invention mounted on a wall surface.
FIG. 2 is a sectional view of the device with portions thereof cut away to more fully illustrate the invention.
FIG. 3 is an enlarged sectional view as seen along line 3--3 of FIG. 2.
FIG. 4 is an enlarged sectional view as seen along line 4--4 of FIG. 2.
FIG. 5 is a schematic drawing of the electrical circuity of this invention.
The numeral 10 generally designates the device of this invention comprising a housing 12 in which the operating components of the device of this invention may be fully housed and, for example, may be composed of metal, certain plastics, etc. Housing 12 is provided with a back 14, front 16, top 18, bottom 20, and opposite sides 22 and 24. Housing 12 is provided with an opening 26 in its bottom 20 which communicates with an air sampling chamber generally designated by the reference numeral 28. Air sampling chamber 28 includes a vertically disposed chamber portion 30 which is in communication with opening 26, and inclined chamber portion 32 which extends upwardly and laterally from chamber portion 30, vertically disposed chamber portion 34 extending upwardly from the upper end of chamber portion 32, and chamber portion 36 which is in communication with the upper end of chamber portion 34 and opening 38 formed inside 22. Air sampling chamber 28 is provided with screens 40 and 42 which prevent bugs or the like from entering the chamber but which permit the flow of air therethrough.
The numeral 44 refers to a heat sensing switch mounted in chamber portion 32 which is adapted to activate an alarm circuit upon the temperature in chamber 28 reaching a predetermined level. The numeral 46 refers generally to a heat resistor positioned in chamber portion 34. Heat resistor 46 heats the air in the chamber portion 34 to create convection currents therein which pulls the air through the opening 26, chamber portion 30, chamber portion 32, chamber portion 34, chamber portion 36 and outwardly through opening 38. A light source 48 having a focusing lens 48A thereon is mounted in the upper end of chamber portion 32 and is adapted to direct light downwardly therefrom as indicated by the arrow in FIG. 2. The numeral 50 refers to a piece of reflective material which is provided in the chamber portion 32 as illustrated in FIGS. 2 and 4.
Housing 12 also includes a sealed temperature controlled compartment or oven 52 having an insulating material extending therearound which is generally designated by the reference numeral 54. Compartment 52 includes a tubular portion 56 which extends between chamber portion 32 and the interior of compartment 52 as illustrated in FIGS. 2 and 4. A lens 58 is mounted in tubular portion 56 and is designed to permit light to pass therethrough into the interior of compartment 52. Lens 58 keeps dust off of cell 60 and seals the compartment 52. Cell 60 is a photoelectric cell mounted at the inner end of tubular portion 56 in compartment 52 adapted to sense the light intensity passing through lens 58. Cell 60 is maintained in position by the heat conductive metal bracket 62 extending thereover as illustrated in FIG. 3. Bracket 62 maintains cell 60 in proper position as well as serving as a heat conductor. Bracket 62 is secured to a heat conductive bracket 64 which supports a heating element 66 thereon as illustrated in FIG. 3. Heating element 66 is controlled by an adjustable thermostat 68 positioned in the compartment 52 so as to maintain the temperature within the compartments 52 at 120° F. plus or minus 11/4percent. The brackets 64 and 62 conduct heat from the heating element 66 to the photoelectric cell 60 so as to insure that the photoelectric cell will be maintained at the proper precise operating temperature.
In FIG. 2, the numeral 70 refers to the main or primary audio signal or horn with the numeral 72 referring to the trouble audio signal or horn. In FIG. 2, the numeral 74 refers to a transformer with the numerals 76 and 78 identifying capacitors. Numeral 80 refers to an adjustable potentiometer which is also illustrated in FIG. 2. A switch 82 is provided in bottom 20 of the housing and is movable from "test" to "reset" positions.
The wiring circuitry of the device is illustrated in FIG. 5 and merely shows the circuitry which permits the device to function. The circuitry does not form an essential part of this invention and for that reason will not be described in detail. The heart of the invention of this device is the structure and method by which the compartment 52 is maintained at 120 degrees so that the photoelectric cell 60 and other temperature effected components will function within the prescribed sensitivity range.
In operation, the device is plugged into any ordinary household circuit. The circuitry of FIG. 5 includes a trouble circuit which causes the ordinary household current to activate the horn 72 if the lamp 48 should fail. In order for a device of this type to receive Underwriters Laboratory's certification, a trouble circuit for the lamp 48 is required with a trouble circuit for power failure being an optional feature.
The operation of the device causes the heat resistor 46 to create convection currents in the air sampling chamber 28 so that the air will be drawn through the chamber 28 and properly sampled. If the temperature in chamber portion 32 rises above a predetermined level, the heat switch 44 causes the horn 70 to be activated thereby signalling that a dangerous condition exists. If smoke exists in the area around the device 10, it will be drawn into the air sampling chamber 28 as indicated by the arrows. In the absence of smoke in chamber portion 32, a certain amount of light passes through the lens 58 with the photoelectric cell 60 sensing that light intensity without activating the alarm circuit. If approximately 10 percent or less black smoke is introduced into chamber portion 32 or if 4 percent or less light smoke is introduced into chamber portion 32, the light intensity therein increases so that a greater light intensity passes through the lens 58 thereby activating the photoelectric cell 60 which in turn activates the alarm circuit so as to activate horn 70. By precisely controlling the temperature within compartment 52, it is possible to achieve the prescribed range of sensitivity necessary to obtain certification of the device. The device of this invention functions within a tolerance of 21/2 percent smoke obscurity at 70° F., and this sensitivity will not vary over a plus or minus 50 percent at either 32° F. or 120° F. Thus, the tolerance factor at 32° F. or 120° F. must be between 11/4 percent and 33/4 percent. The fact that the temperature within the compartment 52 is maintained at the 120° temperature and the fact that means is provided for conducting heat to the photoelectric cell 60 insures that the proper sensitivity range will be achieved.
It should be noted that the electrical circuit of FIG. 5 includes two voltage regulators (4.7 volts and 10 volts) to achieve 50 percent plus or minus sensitivity.
Thus it can be seen that a unique fire and smoke alarm has been provided which senses heat and smoke within a proper sensitivity range. The sensitivity is achieved by the sealed and temperature controlled compartment 52 together with the means for insuring that convection currents will be created in the chamber 28 so that the air is properly sampled. Therefore it can be seen that the device accomplishes at least all of its stated objectives.