EP0583195A1 - Dispositif d'élaboration d'un signal pour une alarme - Google Patents

Dispositif d'élaboration d'un signal pour une alarme Download PDF

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Publication number
EP0583195A1
EP0583195A1 EP93402017A EP93402017A EP0583195A1 EP 0583195 A1 EP0583195 A1 EP 0583195A1 EP 93402017 A EP93402017 A EP 93402017A EP 93402017 A EP93402017 A EP 93402017A EP 0583195 A1 EP0583195 A1 EP 0583195A1
Authority
EP
European Patent Office
Prior art keywords
detector
input
voltage
output
receiving
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Withdrawn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
EP93402017A
Other languages
German (de)
English (en)
French (fr)
Inventor
Michel Iscla
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of EP0583195A1 publication Critical patent/EP0583195A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/20—Actuation by change of fluid pressure

Definitions

  • the device according to the invention overcomes these drawbacks. It uses the fact that each movement of human beings or objects, the breaking of windows and in general any human action causes the setting of the surrounding air.
  • the device according to the invention comprises a detector proper, an associated electrical and electronic device.
  • DE-A-3 029 905 discloses a leak detector which includes a heat-sensitive resistor 14.
  • the voltage difference ⁇ Uf between the voltage across this resistor and a reference voltage Uf is amplified by an operational amplifier, the value thus amplified actuating a display device.
  • Such a device which detects leakage rates in a preferred direction may have its operation disturbed depending on the temperature of the blown fluid, in addition, it does not require great sensitivity.
  • an omnidirectional detector is required and sensitive because the convection currents that we want to detect are currents of low dynamic pressure and very slow.
  • the object of the invention is to provide a device producing a signal for an alarm, the device being insensitive to climatic variations and having no particular detection direction.
  • the device can provide a signal despite certain destructions.
  • the invention relates to the device according to claim 1.
  • the device comprises a detector (1) consisting of a metal wire of very small section operating according to the known principle known as "hot wire”.
  • This principle is generally used for the production of anemometers, that is to say to measure the speed of a fluid. This use makes it necessary to compensate the anemometer for fluctuations in the temperature of the fluid, to seek a fairly wide measurement range and to restore an aerodynamic flow, if possible laminar, at the level of the hot wire.
  • the detector (1) consisting of such a conductor is placed in series with a resistor (2) whose value is close to that of (1) in equilibrium mode by natural convection. Indeed, this condition allows, for a given variation of the resistance of the detector (1) to obtain the greatest variation of the voltage across (2)
  • the resistance (5) placed in parallel with (1) has a value very large compared to that of (1) and (2). Its role will be explained later. It can be overlooked for the following. Under these conditions, the temperature of the detector at equilibrium is written:
  • the sensitivity of the detector is therefore all the more important the larger the product ( ⁇ o . A) and the smaller the product (p. S). It is therefore advantageous for this application to use a detector made of iron, steel, titanium or one of its alloys. In fact, in addition to their electrical characteristics, these materials have excellent mechanical and corrosion resistance. It is also possible to have them in the form of wires with diameters less than eight hundredths of a millimeter, which is entirely suitable for the present application.
  • the device which is the subject of the invention can also be used to detect a change in the nature of the ambient fluid and in particular a liquid / gas transition or vice versa.
  • This application relates in particular to the cooling circuits, for example of an automobile engine, for detect a pipe break and trigger an alarm well before the engine temperature reaches an excessive value, or to detect the level of a fluid.
  • the detector is optimized to detect relatively rapid variations in the exchange coefficient K. It is therefore not necessary to equip the device with any temperature compensation as is generally provided in anemometers using the principle of hot wire.
  • the temperature variations of the ambient fluid in the present applications of the invention are slow.
  • the resistor (5) in parallel with (1) makes it possible to carry out a simple test on the state of the detector (1). In the event of a break in the metal wire (12), the voltage across (2) will become much lower than E / 2, in the event of a short circuit, it will become much higher than E / 2.
  • the voltage at the terminals of (4) is possibly amplified by means of (6) and compared by means of (7) to an adjustable reference voltage Uref which allows the adjustment of the overall sensitivity of the device.
  • the output S will, for example, be a logic level.
  • the principle of the invention makes it possible, in the same circuit, to mount several detectors (1) (10) (11) in series as shown in FIG. 2.
  • Figure 3 shows the principle of realization of the detector (1). It consists of metal wire (12) connected at each end to electrical contacts (13), the whole being fixed on an electrically and thermally insulating support. The metal wire (12) is protected by a grid (15) against mechanical attack.
  • This grid is permeable to fluids. It can be metallic to form a Faraday cage type protection against electromagnetic radiation.
  • metal wire (12) it is advantageous for the metal wire (12) to be distant from the insulating support (14), however it is possible that it is directly in contact with it as illustrated in FIG. 5, at the cost of a slight loss of sensitivity.
  • This particular configuration may be preferred for detecting the nature of the ambient fluid for, for example, a fluid level detector.
  • the wire (12) can be installed either horizontally, vertically, or in any intermediate position. To reduce the dimensions of the detector, it is possible, as illustrated in Figure 4, to fold the wire in the shape of an "S" around insulating pads (16) possibly mounted on a tensioning device, one of the possible solutions of which is shown in Figure 6.
  • This tensioning device comprises the insulating stud (16) sliding and guided, provided with a spring (17) which keeps the wire in tension to compensate for thermal expansions and possible length dispersions.
  • the electrical contacts (13) can be transferred to any side of the detector, either each on a different side as in figure n ° 4, or both on the same side as illustrated in figure n ° 7 and this in the plane of the support (14) or perpendicular thereto.
  • a variant consists in adding a convergent device of the "Venturi" type as illustrated in FIG. 8 and which makes it possible to accelerate the flow of fluid.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
EP93402017A 1992-08-11 1993-08-05 Dispositif d'élaboration d'un signal pour une alarme Withdrawn EP0583195A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9210064A FR2694810A1 (fr) 1992-08-11 1992-08-11 Dispositif pour détecter les variations du coefficient d'échange thermique par convection avec un fluide notamment destiné aux systèmes d'alarme anti-intrusion et anti-vol.
FR9210064 1992-08-11

Publications (1)

Publication Number Publication Date
EP0583195A1 true EP0583195A1 (fr) 1994-02-16

Family

ID=9432884

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93402017A Withdrawn EP0583195A1 (fr) 1992-08-11 1993-08-05 Dispositif d'élaboration d'un signal pour une alarme

Country Status (2)

Country Link
EP (1) EP0583195A1 (enrdf_load_stackoverflow)
FR (1) FR2694810A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107807145A (zh) * 2016-09-09 2018-03-16 中核兰州铀浓缩有限公司 一种无热源型检测uf6介质气体流向的传感器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3029905A1 (de) * 1980-08-07 1982-03-11 Stumpp + Kurz Gmbh + Co, 7000 Stuttgart Lecksuchgeraet
DE3118060A1 (de) * 1981-05-07 1982-11-25 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt "verfahren und anordnung zur ueberwachung eines nominell gasdichten hohlkoerpers"

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3029905A1 (de) * 1980-08-07 1982-03-11 Stumpp + Kurz Gmbh + Co, 7000 Stuttgart Lecksuchgeraet
DE3118060A1 (de) * 1981-05-07 1982-11-25 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt "verfahren und anordnung zur ueberwachung eines nominell gasdichten hohlkoerpers"

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107807145A (zh) * 2016-09-09 2018-03-16 中核兰州铀浓缩有限公司 一种无热源型检测uf6介质气体流向的传感器

Also Published As

Publication number Publication date
FR2694810B1 (enrdf_load_stackoverflow) 1997-02-07
FR2694810A1 (fr) 1994-02-18

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