EP1993083A2 - Vorrichtung und Verfahren zur Raucherkennung - Google Patents

Vorrichtung und Verfahren zur Raucherkennung Download PDF

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Publication number
EP1993083A2
EP1993083A2 EP08156302A EP08156302A EP1993083A2 EP 1993083 A2 EP1993083 A2 EP 1993083A2 EP 08156302 A EP08156302 A EP 08156302A EP 08156302 A EP08156302 A EP 08156302A EP 1993083 A2 EP1993083 A2 EP 1993083A2
Authority
EP
European Patent Office
Prior art keywords
radiation
chamber
smoke
detector
emitter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08156302A
Other languages
English (en)
French (fr)
Other versions
EP1993083A3 (de
Inventor
Domenico Arancio
Antonio Caldiroli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Elkron SpA
Original Assignee
Elkron SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Elkron SpA filed Critical Elkron SpA
Publication of EP1993083A2 publication Critical patent/EP1993083A2/de
Publication of EP1993083A3 publication Critical patent/EP1993083A3/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
    • 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
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors
    • G08B29/185—Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system

Definitions

  • the present invention relates to a smoke detection device according to the preamble of claim 1, as well as to a related smoke detection method.
  • the invention relates to optical smoke detectors based on Tyndall's effect, and it specifically tackles two problems which are commonly found in detectors of this type.
  • the first problem concerns the uniformity of the detector response as a function of the direction and speed of the smoke entering the detection chamber.
  • the second problem concerns the possibility of discriminating true alarms from false alarms caused by foreign bodies entering the detection chamber.
  • Smoke detectors based on Tyndall's effect consist of a detection chamber, called “smoke chamber”, characterized in that (thanks to a labyrinth located on the edge of the chamber) light cannot enter the chamber from the outside, while smoke can.
  • the detection chamber houses a receiver diode and an emitter diode, the respective reception and emission fields intersecting within the chamber.
  • the reciprocal positioning of the emitter and receiver diodes typically forms an angle between 95 and 150 degrees.
  • the intersection between the emission beam and the reception cone creates within the chamber a space portion which represents the sensitive zone of the smoke chamber.
  • This arrangement of the emitter and receiver diodes is normally used in order to obtain that, in the absence of smoke, the receiver diode detects a very low radiation (used as a control signal for the correct operation of the detector), which is not sufficient to trigger the smoke alarm.
  • the receiver diode will detect a high quantity of radiation and a detector control unit will trigger the alarm.
  • the sensitivity of the detector depends on the direction of the intake smoke.
  • An alarm triggered in a fire detection system may give way to a number of very expensive actions, such as calling the Fire Department, evacuation plans, and the activation of automatic systems in order to extinguish the fire.
  • the invention is based on the idea of arranging the device that emits the electromagnetic radiation in line with the device that receives it. De facto, this alignment translates into the emitter and detector devices being arranged in a manner such that they are crossed by a median plane extending between the base and the ceiling of the detection chamber.
  • the emitter device is adapted to emit radiation in a symmetrical manner with respect to said median plane, thus ensuring a uniform detection within the chamber.
  • This solution allows to eliminate all blind spots in the detection chamber, since the beam emitted by the emitter device illuminates the whole chamber in a substantially uniform manner.
  • the emitter device advantageously comprises two radiation sources, in particular two LED diodes which can be controlled separately in order to choose which part of the chamber must be sensed.
  • the two sources are controlled in such a manner that they are turned on one at a time, and each time it is verified if the quantity of radiation received by the detector exceeds the alarm threshold over which it is determined that smoke is present. If the quantity of received radiation does not exceed the threshold when either source is off, then a false alarm will be detected.
  • smoke detection device 1 (hereafter also called “smoke detector”) comprises a cap 2 enclosing a detection chamber 3, which will be described in detail with reference to Figs. 2a and 2b .
  • Detection chamber 3 comprises a base 4, a ceiling (not shown in the drawing for simplicity's sake), and a side wall 5 adapted to allow smoke and not allow light to enter chamber 3.
  • side wall 5 comprises a labyrinth 6 which follows the chamber perimeter and which consists of a plurality of V-shaped elements (designated by reference numeral 7) that let air and smoke into the chamber while blocking light.
  • Labyrinth 6 is wound by a thin-mesh grid 8 which prevents any foreign bodies from entering chamber 3.
  • Chamber 3 takes up a volume having a substantially axial symmetry, with an axis of symmetry y.
  • housings 9 and 10 Inside chamber 3 there are two housings 9 and 10, which accommodate a device 11 emitting an electromagnetic radiation and a device 12 capable of receiving said radiation, respectively.
  • the emitter and receiver devices have been schematically drawn with a dashed line inside the respective housings.
  • the emitter device consists of a pair of smd LEDs (light emitting diodes) that emit a radiation within the infrared range, while receiver device 12 consists of a photodiode that detects radiation within the same band.
  • Emitter device 11 and receiver device 12 are aligned along median plane ⁇ extending between the base and the ceiling of chamber 3 and crossing devices 11 and 12.
  • the LEDs are preferably mounted to a PCB (printed circuit board) arranged vertically in the housings and connected electrically to a motherboard (not shown) installed under the chamber, as described in patent application TO2006A000676 in the name of the present Applicant.
  • PCB printed circuit board
  • the radiation emitted by the LEDs spreads inside chamber 3 in a symmetrical manner with respect to median plane ⁇ and is detected by the photodiode.
  • the photodiode preferably THT (through hole technology) type, is also connected to the motherboard.
  • a photodiode generates a current signal, the amplitude of which is proportional to the radiation detected.
  • the photodiode detects a quantity of radiation exceeding a preset value (alarm threshold)
  • a control unit e.g. a microprocessor mounted to the motherboard.
  • Such a signal is interpreted as an alarm for the possible presence of smoke in the chamber.
  • a dimmer device 13 Between the emitter device and the receiver device there is a dimmer device 13.
  • Dimmer device 13 is positioned and sized in such a manner that it can intercept a portion of the radiation emitted by the emitter LEDs, so that in the absence of smoke the quantity of radiation received by the detector is below the alarm threshold over which the signal generated by the photodiode has such an amplitude that it is interpreted as an alarm signal indicating the presence of smoke in the chamber.
  • the photodiode detects a radiation having such an intensity that the signal generated by said photodiode is read by the control unit as an alarm signal.
  • Dimmer device 13 has a symmetry plane which coincides with median plane ⁇ .
  • the dimmer device has preferably a cylindrical shape, or anyway a profile which is convex in the emitter direction.
  • the dimmer device may have a knurled surface.
  • both emitter LEDs are on and emit infrared radiation.
  • control unit When the control unit receives a signal having such an amplitude that it is interpreted as an alarm signal, the control unit activates a procedure for detecting false alarms.
  • the two emitter LEDs are turned off alternatively, therefore keeping only one switched on at the time , in order make the two chamber portions C1 and C2 alternatively sensitive.
  • control unit verifies whether the amplitude of the signal transmitted by the photodiode is such that said signal must be read as an alarm signal or not.
  • the emitter LEDs may be replaced with THT diodes or other sources which can be used for exploiting Tyndall's effect.
  • the detection device may consist of a plurality of photodiodes or CCD sensors.
  • the LED diodes may be replaced with a single electromagnetic radiation source (e.g. a single diode).
  • the arrangement of the emitter and receiver devices is nonetheless such as to ensure a good sensitivity of the smoke detector.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
EP08156302A 2007-05-18 2008-05-15 Vorrichtung und Verfahren zur Raucherkennung Withdrawn EP1993083A3 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT000355A ITTO20070355A1 (it) 2007-05-18 2007-05-18 Dispositivo e metodo per rilevare fumo

Publications (2)

Publication Number Publication Date
EP1993083A2 true EP1993083A2 (de) 2008-11-19
EP1993083A3 EP1993083A3 (de) 2009-07-29

Family

ID=39643811

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08156302A Withdrawn EP1993083A3 (de) 2007-05-18 2008-05-15 Vorrichtung und Verfahren zur Raucherkennung

Country Status (2)

Country Link
EP (1) EP1993083A3 (de)
IT (1) ITTO20070355A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106441395A (zh) * 2016-11-17 2017-02-22 天津航联迪克科技有限公司 快速更换迷宫的可拆卸式探测器

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1188178A (en) * 1967-12-05 1970-04-15 Pyrene Co Ltd Smoke Detectors
USRE32105E (en) * 1980-12-31 1986-04-01 American District Telegraph Company Forward scatter smoke detector
CH656474A5 (de) * 1981-11-11 1986-06-30 Cerberus Ag Rauchdetektor.
JPS6013449U (ja) * 1983-03-31 1985-01-29 ホーチキ株式会社 散乱光式煙感知器の検煙部構造
GB2327752B (en) * 1997-07-26 2001-05-02 Rafiki Prot Ltd Optical scatter smoke sensor
GB2342987B (en) * 1998-10-20 2003-03-19 David Appleby Improved smoke sensor with a fault monitoring capability
GB2397122B (en) * 2003-01-03 2006-02-08 David Appleby Fire detector with low false alarm rate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106441395A (zh) * 2016-11-17 2017-02-22 天津航联迪克科技有限公司 快速更换迷宫的可拆卸式探测器
CN106441395B (zh) * 2016-11-17 2019-03-26 天津航联迪克科技有限公司 快速更换迷宫的可拆卸式探测器

Also Published As

Publication number Publication date
EP1993083A3 (de) 2009-07-29
ITTO20070355A1 (it) 2008-11-19

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