US3832552A - Dual chamber ionization smoke detector - Google Patents

Dual chamber ionization smoke detector Download PDF

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Publication number
US3832552A
US3832552A US00372552A US37255273A US3832552A US 3832552 A US3832552 A US 3832552A US 00372552 A US00372552 A US 00372552A US 37255273 A US37255273 A US 37255273A US 3832552 A US3832552 A US 3832552A
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United States
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electrode
electrodes
chamber
invention according
inverted
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Expired - Lifetime
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US00372552A
Inventor
L Larsen
G Rork
J Pekarek
A Kompelien
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Honeywell Inc
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Honeywell Inc
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Application filed by Honeywell Inc filed Critical Honeywell Inc
Priority to US00372552A priority Critical patent/US3832552A/en
Priority to CA200,346A priority patent/CA1015072A/en
Priority to JP49062460A priority patent/JPS5829459B2/en
Priority to AU69886/74A priority patent/AU6988674A/en
Priority to DE19742428325 priority patent/DE2428325A1/en
Priority to CH827974A priority patent/CH567310A5/xx
Priority to GB2689774A priority patent/GB1439448A/en
Application granted granted Critical
Publication of US3832552A publication Critical patent/US3832552A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
    • G01N27/66—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber and measuring current or voltage
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
    • G08B17/113—Constructional details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/02—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas
    • H01J41/08—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas with ionisation by means of radioactive substances, e.g. alphatrons

Definitions

  • FIG. 1 is a cross-section of a preferred embodiment of the dual chamber assembly
  • FIGS. 2 through 6 are drawings of various internal parts of the structure of FIG. 1, and
  • FIG. 7 is an electrical block diagram of the chamber assembly in a circuit.
  • FIG. 1 there is generally disclosed a dual chamber assembly for an ionization smoke detector.
  • the upper ionization chamber 11 is a reference chamber which is substantially or nearly sealed and does not freely admit the surrounding air.
  • the lower ionization chamber 12 is the sensing chamber which is designed to freely allow through it circulation of the surrounding air so that when smoke is present in the air it can be rapidly detected.
  • a cup-like electrode 13 defines the reference chamber.
  • a flange 14 extending around the perimeter of the cup electrode 13 serves as a mounting means.
  • An ionizing source 15 of radioactive material enclosed in a rivet-like container is fastened in the upper surface or section 16 of the electrode I3.
  • the section 16 has a dimple or recess 17 stamped into the surface so that the radioactive source 15, which is mounted in the recess, does not extend out into the chamber but instead the radiation surface of the radioactive source is substantially flush with the general internal contour of the electrode 13 at the surface 16.
  • the sensing chamber 12 is defined by a circular cuplike electrode 13' which is identical to the previously described electrode 13 except that an additional stamping step opens a plurality of louvers 20 to allow the free exchange of the surrounding air into the sensing chamber.
  • the dual chamber assembly is mounted to a circuit board 21 which has a circular cutout to accomodate the ionization chambers.
  • the reference and sensing chamber are separated by a fluorocarbon plastic (such as fluorinated ethylene-propylene (PE?) or polytetrafluoroethylene (TFE); by DuPont named Teflon) disc or wafer 22 shown in FIGS. 1 and 2 which forms a non wettable insulating common wall of each chamber.
  • a metallic insert i.e., an electrically conductive electrode support 23, the details of which are more clearly seen in FIGS. 3 and 4.
  • the conductive insert 23 includes a disc portion 24 and an extension or tail portion 25 extending through the wafer to a connection point 25' at the edge.
  • the disc portion 24 has an offset section 26 to be described further below.
  • the second electrode of the reference chamber 11' is a metal disc 27 and it together with an identical part 2.7" in sensing chamber 12 are both fastened to the offset section 26 of the insert 23.
  • the details of the electrodes 27, 27' are shown in FIGS. 5 and 6 and it will be apparent from FIG. 6 that these electrodes have an offset center portion 28 to provide for the proper mounting of the electrodes.
  • the fluorocarbon material is used because of the high impedance circuit of electrodes 27 and 27 and the electrode support means 23.
  • the non wetting nature of the surface of wafer 22 ensures that there will be no tendency for a film of moisture to form on the surface of the wafer to reduce the effective electrical insulation capabilities of wafer 22.
  • the chamber dimension from electrode section 16 to electrode 27 be the same as the dimension from electrode section 16' to electrode 27'.
  • the insert conductor 23 has a sufficient offset in the center mounting portion 26 to achieve dimensional symmetry. This offset raises electrode 27' above the surface of wafer 22.
  • the electrodes 27 and 27' and the conductive mounting means 23 being staked together are all electrically common to each other and the terminal 25 provides for connection of the signal potential at these electrodes to the high impedance signal input terminal of a suitable electrical measuring circuit 30 shown substantially in FIG. 7.
  • an improved chamber assembly comrpising in combination:
  • a first cup like electrode for defining a substantially sealed reference chamber
  • an inverted cup like electrode like said first electrode but also having louvers for admitting air to be sensed, for defining a sensing chamber
  • a fluorocarbon plastic member of wafer like shape providing a non wettable insulating divider between said first and inverted electrodes and providing a common wall of said reference chamber and sensing chamber;
  • an electrically conductive electrode support embedded into said wafer like member said support having an extension extending through said wafer like member to a connection point at the edge thereof;
  • third and fourth electrodes mounted one on either side of said wafer like member to said electrode support, whereby said electrodes, electrode support and connection point are electrically common;
  • fluorocarbon plastic member is fluorinated ethylene propylene (FEP).
  • said electrode support has an offset at the mounting point of said third and fourth electrodes to account for the thickness of said printed circuit board in said assembly and provide equal inter electrode spacing in said two chambers,

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Abstract

An improved chamber assembly for a dual chamber ionization smoke detector. A fluorocarbon plastic insulation member provides a non wettable insulating dividing wall between the two chambers.

Description

United States Patent Larsen et a1.
[ Aug. 27, 1974 DUAL CHAMBER IONIZATION SMOKE DETECTOR Inventors: Larry D. Larsen, Palatine; Joseph C.
Pekarek, Mt. Prospect, both of 111.; Arlon D. Kompelien, Richfield; Gerald D. Rork, Bloomington, both of Minn.
Assignee: Honeywell Inc., Minneapolis, Minn.
Filed: June 22, 1973 Appl. No.: 372,552
U.S. C1. 250/381, 313/54 Int. Cl. G01f 1/18 Field of Search 250/381; 313/54;
[56] References Cited UNITED STATES PATENTS 3,582,646 6/1971 Ponsar 313/54 X 3,710,] 10 1/1973 Lampart et a1. 250/381 3,725,011 4/1973 Primary Examiner-Archie R. Borchelt Attorney, Agent, or FirmOmund R. Dahle [57] ABSTRACT An improved chamber assembly for a dual chamber ionization smoke detector. A'fluorocarbon plastic insulation member provides a non wettable insulating dividing wall between the two chambers.
9 Clairm, 7 Drawing Figures Purt et a1 250/381 X DUAL CHAMBER IONIZATION SMOKE DETECTOR SUMMARY OF THE INVENTION An improved chamber assembly for an ionization smoke detector which has dual chambers separated by a fluorocarbon plastic divider which non wettable insulating divider has embedded therein conductive mounting means for an electrode of each of the chambers and to provide a signal output terminal.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-section of a preferred embodiment of the dual chamber assembly,
FIGS. 2 through 6 are drawings of various internal parts of the structure of FIG. 1, and
FIG. 7 is an electrical block diagram of the chamber assembly in a circuit.
DESCRIPTION Referring now to FIG. 1 there is generally disclosed a dual chamber assembly for an ionization smoke detector. The upper ionization chamber 11 is a reference chamber which is substantially or nearly sealed and does not freely admit the surrounding air. The lower ionization chamber 12 is the sensing chamber which is designed to freely allow through it circulation of the surrounding air so that when smoke is present in the air it can be rapidly detected. A cup-like electrode 13 defines the reference chamber. A flange 14 extending around the perimeter of the cup electrode 13 serves as a mounting means.
An ionizing source 15 of radioactive material enclosed in a rivet-like container is fastened in the upper surface or section 16 of the electrode I3. The section 16 has a dimple or recess 17 stamped into the surface so that the radioactive source 15, which is mounted in the recess, does not extend out into the chamber but instead the radiation surface of the radioactive source is substantially flush with the general internal contour of the electrode 13 at the surface 16.
The sensing chamber 12 is defined by a circular cuplike electrode 13' which is identical to the previously described electrode 13 except that an additional stamping step opens a plurality of louvers 20 to allow the free exchange of the surrounding air into the sensing chamber.
The dual chamber assembly is mounted to a circuit board 21 which has a circular cutout to accomodate the ionization chambers. The reference and sensing chamber are separated by a fluorocarbon plastic (such as fluorinated ethylene-propylene (PE?) or polytetrafluoroethylene (TFE); by DuPont named Teflon) disc or wafer 22 shown in FIGS. 1 and 2 which forms a non wettable insulating common wall of each chamber. Embedded in the center of wafer 22 is a metallic insert, i.e., an electrically conductive electrode support 23, the details of which are more clearly seen in FIGS. 3 and 4. The conductive insert 23 includes a disc portion 24 and an extension or tail portion 25 extending through the wafer to a connection point 25' at the edge. The disc portion 24 has an offset section 26 to be described further below.
The second electrode of the reference chamber 11' is a metal disc 27 and it together with an identical part 2.7" in sensing chamber 12 are both fastened to the offset section 26 of the insert 23. The details of the electrodes 27, 27' are shown in FIGS. 5 and 6 and it will be apparent from FIG. 6 that these electrodes have an offset center portion 28 to provide for the proper mounting of the electrodes.
The fluorocarbon material is used because of the high impedance circuit of electrodes 27 and 27 and the electrode support means 23. The non wetting nature of the surface of wafer 22 ensures that there will be no tendency for a film of moisture to form on the surface of the wafer to reduce the effective electrical insulation capabilities of wafer 22.
It is desired that the chamber dimension from electrode section 16 to electrode 27 be the same as the dimension from electrode section 16' to electrode 27'. In order to compensate for the thickness of the PC board 21 in the assembly, which would otherwise unbalance the dimensional symmetry of the two chambers, the insert conductor 23 has a sufficient offset in the center mounting portion 26 to achieve dimensional symmetry. This offset raises electrode 27' above the surface of wafer 22. The electrodes 27 and 27' and the conductive mounting means 23 being staked together are all electrically common to each other and the terminal 25 provides for connection of the signal potential at these electrodes to the high impedance signal input terminal of a suitable electrical measuring circuit 30 shown substantially in FIG. 7.
The embodiments of the invention in which an exclusive property or right is claimed are defined as follows:
1. In an ionization smoke detector of the type having a reference chamber and a smoke sensing chamber, an improved chamber assembly comrpising in combination:
A first cup like electrode for defining a substantially sealed reference chamber;
an inverted cup like electrode like said first electrode but also having louvers for admitting air to be sensed, for defining a sensing chamber;
means causing ionization within each chamber;
a fluorocarbon plastic member of wafer like shape providing a non wettable insulating divider between said first and inverted electrodes and providing a common wall of said reference chamber and sensing chamber;
an electrically conductive electrode support embedded into said wafer like member, said support having an extension extending through said wafer like member to a connection point at the edge thereof;
third and fourth electrodes mounted one on either side of said wafer like member to said electrode support, whereby said electrodes, electrode support and connection point are electrically common;
and fastening means for affixing together said first electrode, said fluorocarbon plastic member with its electrodes, and said inverted electrode.
2. The invention according to claim 1 in which said third and fourth electrodes are disc shaped electrodes mountedcoaxially one on either side of said wafer like member.
3. The invention according to claim 1 in which said fluorocarbon plastic member is fluorinated ethylene propylene (FEP).
4. The invention according to claim 1 in which said fluorocarbon plastic member is polytetraflusaid fluorocarbon plastic member, said printed circuit board having a cutout area within the sensing chamber.
8. The invention according to claim 7 in which said third and fourth electrodes are dimensionally alike and in which said first and inverted electrodes are dimensionally alike except for the louvers of said inverted electrode. 7
9. The invention according to claim 8 in which said electrode support has an offset at the mounting point of said third and fourth electrodes to account for the thickness of said printed circuit board in said assembly and provide equal inter electrode spacing in said two chambers,

Claims (9)

1. In an ionization smoke detector of the type having a reference chamber and a smoke sensing chamber, an improved chamber assembly comrpising in combination: A first cup like electrode for defining a substantially sealed reference chamber; an inverted cup like electrode like said first electrode but also having louvers for admitting air to be sensed, for defining a sensing chamber; means causing ionization within each chamber; a fluorocarbon plastic member of wafer like shape providing a non wettable insulating divider between said first and inverted electrodes and providing a common wall of said reference chamber and sensing chamber; an electrically conductive electrode support embedded into said wafer like member, said support having an extension extending through said wafer like member to a connection point at the edge thereof; third and fourth electrodes mounted one on either side of said wafer like member to said electrode support, whereby said electrodes, electrode support and connection point are electrically common; and fastening means for affixing together said first electrode, said fluorocarbon plastic member with its electrodes, and said inverted electrode.
2. The invention according to claim 1 in which said third and fourth electrodes are disc shaped electrodes mounted coaxially one on either side of said wafer like member.
3. The invention according to claim 1 in which said fluorocarbon plastic member is fluorinated ethylene propylene (FEP).
4. The invention according to claim 1 in which said fluorocarbon plastic member is polytetrafluoroethylene (TFE).
5. The invention according to claim 2 in which said fastening means affixes together in coaxial alignment said first electrode, said fluorocarbon plastic member with its disc shaped electrodes and said inverted electrode.
6. The invention according to claim 1 in which said means causing ionization comprises a radioactive source affixed within each chamber.
7. The invention according to claim 1 in which the chamber assembly is mounted on a printed circuit board, the chamber assembly further comprising: a printed circuit board positioned between the perimeter region of said inverted cup like electrode and said fluorocarbon plastic member, said printed circuit board having a cutout area within the sensing chamber.
8. The invention according to claim 7 in which said third and fourth electrodes are dimensionally alike and in which said first and inverted electrodes are dimensionally alike except for the louvers of said inverted electrode.
9. The invention according tO claim 8 in which said electrode support has an offset at the mounting point of said third and fourth electrodes to account for the thickness of said printed circuit board in said assembly and provide equal inter electrode spacing in said two chambers.
US00372552A 1973-06-22 1973-06-22 Dual chamber ionization smoke detector Expired - Lifetime US3832552A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00372552A US3832552A (en) 1973-06-22 1973-06-22 Dual chamber ionization smoke detector
CA200,346A CA1015072A (en) 1973-06-22 1974-05-21 Dual chamber ionization smoke detector
JP49062460A JPS5829459B2 (en) 1973-06-22 1974-06-01 Aeon Shiki Kemuri Kantiki
AU69886/74A AU6988674A (en) 1973-06-22 1974-06-07 Smoke detector
DE19742428325 DE2428325A1 (en) 1973-06-22 1974-06-12 IONIZATION FIRE ALARM
CH827974A CH567310A5 (en) 1973-06-22 1974-06-17
GB2689774A GB1439448A (en) 1973-06-22 1974-06-18 Ionization smoke detector

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075487A (en) * 1976-05-14 1978-02-21 Patent Development & Management Company Ionization chamber assembly
US4282519A (en) * 1977-10-06 1981-08-04 Honeywell Inc. Interconnection of alarms of smoke detectors with distinguishable alarms

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3582646A (en) * 1967-02-09 1971-06-01 Vigifeu Aubervilliers Ionization fire detection device
US3710110A (en) * 1969-05-19 1973-01-09 Cerberus Ag Ionization fire alarm device with shielding for its electrical circuitry
US3725011A (en) * 1969-03-28 1973-04-03 Cerberus Ag Automatic fire alarm with at least one measuring chamber

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3582646A (en) * 1967-02-09 1971-06-01 Vigifeu Aubervilliers Ionization fire detection device
US3725011A (en) * 1969-03-28 1973-04-03 Cerberus Ag Automatic fire alarm with at least one measuring chamber
US3710110A (en) * 1969-05-19 1973-01-09 Cerberus Ag Ionization fire alarm device with shielding for its electrical circuitry

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075487A (en) * 1976-05-14 1978-02-21 Patent Development & Management Company Ionization chamber assembly
US4282519A (en) * 1977-10-06 1981-08-04 Honeywell Inc. Interconnection of alarms of smoke detectors with distinguishable alarms

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