EP0127645A1 - Fire alarm and electrode device therefor. - Google Patents

Fire alarm and electrode device therefor.

Info

Publication number
EP0127645A1
EP0127645A1 EP83903778A EP83903778A EP0127645A1 EP 0127645 A1 EP0127645 A1 EP 0127645A1 EP 83903778 A EP83903778 A EP 83903778A EP 83903778 A EP83903778 A EP 83903778A EP 0127645 A1 EP0127645 A1 EP 0127645A1
Authority
EP
European Patent Office
Prior art keywords
electrode
measuring
arrangement
electrodes
fire detector
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.)
Granted
Application number
EP83903778A
Other languages
German (de)
French (fr)
Other versions
EP0127645B1 (en
Inventor
Hans-Christoph Siegmann
Heinz Burtscher
Andreas Schmidt-Ott
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.)
SLM Investissements SA
Original Assignee
LANGATRONIC SA
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 LANGATRONIC SA filed Critical LANGATRONIC SA
Priority to AT83903778T priority Critical patent/ATE38732T1/en
Publication of EP0127645A1 publication Critical patent/EP0127645A1/en
Application granted granted Critical
Publication of EP0127645B1 publication Critical patent/EP0127645B1/en
Expired 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
    • 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

Definitions

  • the invention relates to a fire detector with at least two electrodes, between which an electric field is generated by a DC voltage source, the opposite electrode surfaces delimiting a measuring space through which the air moved by convection of a room to be monitored can pass, and one of the Electrodes as the measuring electrode and the other as the counter electrode, and a current measuring arrangement and evaluation circuit is provided.
  • Fire detectors of a similar type are known and used in various designs.
  • US Pat. No. 2,408,051 (Donelian) shows a fire detector with two measuring rooms, small particles and small ions being "filtered out" electrically in the first measuring room and the air being ionized in the second measuring room with the aid of a radioactive preparation.
  • the resulting conductivity is reduced when smoke is present because ions attach to the difficult-to-move smoke particles. If the reduction in conductivity in the ionization chamber reaches a threshold, the alarm is extinguished.
  • the electrodes which delimit the measuring spaces are connected in series in the manner of a capacitive voltage divider between the positive and negative poles of a DC voltage source.
  • Fire detector is practically unusable. The same applies to the fire and smoke detector according to US Pat. No. 3,470,551 (Jaffe et al).
  • Ion measuring devices or measuring arrangements for determining the mobility of particles are known, as is the case e.g. from US Pat. No. 4,114,088, but so far neither the use of such measuring devices as fire detectors has been proposed, nor are they suitable for such use due to the design. Rather, fire detectors with ionization chambers dominate, especially using radioactive preparations, although the need for simplified fire detectors that are less polluting and, above all, work without radioactive substances has been constant and has existed for a long time. This is also evident from Scheidweiler's article in "Staub-Reinhalt.Luft, Vol. 32 No.11 November, 1972".
  • the invention is accordingly based on the object of providing an improved, highly sensitive and substantially simplified fire detector and a dedicated electrode arrangement which can be used for ionization without radioactive preparations.
  • this is primarily achieved in that at least one of the electrodes with a circula tion openings for the ambient air to be monitored and / or consists of a plurality of partial electrodes arranged with spaces in such a way that ambient air can flow into the measuring space through these spaces that the DC voltage source on the one hand directly or indirectly with the counter electrode and on the other hand with the current -Measuring arrangement is connected, and that the measuring electrode is connected to the input of the current measuring arrangement without a direct connection to the DC voltage source.
  • the invention is based for the first time in an optimally simple manner on the principle that smoke particles from burns are principally strongly electrically charged. This is due to the fact that positive and negative small ions attach to the particles. These are constantly formed in the air even in normal surroundings, especially through cosmic rays and natural radioactivity.
  • the concentration of the particles of radius R with p elementary charges is accordingly
  • n R is the total concentration of the neutral particles with radius R
  • k is the Boltzmann constant
  • T is the absolute temperature.
  • charge of the smoke means the average of the amount of the particle charge.
  • the fire detector according to the invention measures the amount of
  • Particle charge of a certain sign also works if the net charge of the smoke is zero. With such a charge distribution, there are the same number of posi tive as negative ions on the smoke particles.
  • reliable detection of the smoke in the field between the measuring electrode and counterelectrode is now ensured by electrostatically separating positive and negative particles and measuring the charge of a sign or by measuring the change in conductivity caused by the smoke.
  • the electric current thus generated is relatively small at field strengths which do not yet lead to glow discharge, but at least amount to 100 volts / cm, but can easily be measured with electronic amplifiers or small electroscopes.
  • the electrode spacing is advantageously less than 10 mm, but more than 1 mm. It has been shown that a number of advantageous properties can be achieved through this special dimensioning: the relatively small measuring space provides a good shielding of the measuring electrode against influence by net charge; on the other hand, the distance is large enough to avoid false reports from possibly deposited dust or soot particles. In addition, it has been shown that with such an electrode spacing, it is also possible to work with voltages in an optimal range, which on the one hand ensure reliable separation and separation of charged particles and on the other hand avoid contamination by constant attraction and deposition of dust particles.
  • the invention is advantageously not based on the measurement of the excess or net charge practiced in known devices, but on the charge measurement after electrostatic separation of positive and negative particles.
  • an auxiliary electrode arrangement can be provided which pre-separates small and / or charged particles carried by slow flow before they can get into the measuring space. That way the sensitivity to small smoke sources that cause small particles and / or only slow convective flow (cigarettes) are reduced.
  • the net charge suppression can also be achieved or further improved by providing a compensation space which is delimited on the one hand by the measuring electrode and on the other hand by a compensation electrode.
  • the measuring electrode is influenced by the influence of net charge e.g. shielded in large smoke clouds on both sides and only that in a relatively small volume limited by the measuring space and / or the compensation space is measured.
  • the compensation electrode can simultaneously be designed as a shield for the electrode arrangement.
  • the influences described above by the net charge or by influence can even be completely compensated for if the compensation space is arranged at approximately the same distance from the measuring electrode as the measurement space and is also able to absorb approximately the same volume of ambient air flowing through. This means that the influence of gases flowing in the measuring space with a high net charge is compensated for by the influence of reversed polarity caused by gases flowing away in the compensation space.
  • Compensation can also advantageously be achieved if the measuring electrode is arranged with respect to the air flow in such a way that the air flow sweeps the measuring electrode twice, but strikes it from opposite sides, respectively, or flows through the electrode, so that influence currents caused by the net charge of the passing through Ambient air or smoke clouds appear in the measuring electrode can be compensated. Influence currents are evidently counteracted by the charged smoke hitting the electrode from different sides generated opposite polarity, which is simplest
  • an electrode arrangement for the fire detector according to the invention is a measuring electrode and / or compensation electrode designed as a grid; this facilitates convection and prevents the im
  • the measuring electrode can also be constructed from several electrically connected partial electrodes, which are caused by air. or gas clouds are flowed through in such a way that the influence of influence is canceled out by the net charge in the partial electrodes.
  • the measuring electrode is arranged between two counter electrodes, the two
  • Counter electrodes are connected to the DC voltage source and the measuring electrode is provided between the counter electrodes and is connected to the input of the measuring arrangement. This ensures that the fields in the two measuring rooms between the two counter electrodes and the
  • Measuring electrode run symmetrically to it, i.e. in other words, particles of the same polarity charged from both measuring rooms hit the measuring electrode. This guarantees high sensitivity in particular.
  • the measuring electrode is connected to the input of the measuring arrangement and is therefore virtually at the potential of the other side of the measuring arrangement. She lets herself down partially mechanically rigidly connect by means of insulation elements with an electrode housing and / or the counter electrodes, the insulation elements being interrupted by electrically conductive parts which are connected to the other side of the measuring electrode. This prevents leakage currents from being measured on the insulation elements.
  • FIG. 1 shows the basic illustration of a fire detector with the features of the invention
  • FIG. 2 shows a fire detector with a modified one
  • Electrode, Figure 3 shows a fire detector with a further modified
  • FIG. 4 shows a fire detector according to the invention with two measuring rooms and external shielding
  • Figure 5 shows a modified embodiment of a measuring electrode.
  • FIG. 1 shows the basic illustration of a fire detector according to the invention with a measuring electrode 1, a counter electrode 2, a schematically illustrated measuring arrangement 3, which at the same time serves to trigger the alarm in a known manner, and a DC voltage source 4.
  • Measuring electrode 1 and counter electrode 2 are connected to a holder 7 by means of insulation elements 6 attached, which in turn is connected to a base plate 8.
  • the holder 7 is electrically conductive and lies on ground, so that over the insulation elements 6 can flow no leakage currents between the measuring electrode 1 and the counter electrode 2, since the measuring electrode via the measuring arrangement 3 - but only virtually - is at ground potential. This is advantageous in view of the extremely low flowing currents.
  • the distance between the measuring electrode 1 and counter electrode 2 is 5 mm, the voltage of the direct voltage source 4 is 500 volts, so that there is a field strength of 1000 volts / cm between the two electrodes 1 and 2. Now charged smoke particles get into the measuring space 9 between the measuring electrode 1 and counter electrode 2 .
  • Measuring electrode 1 and counter electrode 2 the electric field causes the positive and negative particles to move to the two electrodes. This charge movement (charge drift) influences a current into the measuring electrode 1, which is measured in the measuring arrangement 3.
  • the measuring electrodes 1 and the counter electrode 2 are designed as approximately square plates with an area of 40 cm 2 each.
  • the area of the electrodes can be changed depending on the requirement and the desired sensitivity of the measuring arrangement, as can also be seen, for example, from the exemplary embodiment according to FIG.
  • the overall arrangement is surrounded by a shield 5, which is also grounded. This not only ensures mechanical protection of the arrangement, but also influences of errors caused by net charging of a schematically indicated smoke cloud 30 are compensated to the extent that influences from the charge cloud outside the shield 5 are kept away from the measuring electrode 1 and thus no influence currents can arise
  • both the measuring electrode 1 and the counter electrode 2 are provided with a multiplicity of holes 11, which allow the smoke to flow through the measuring space 9 coming from the horizontal direction as well as from the vertical direction solely due to the convection.
  • Figure 2 shows an arrangement in which the base plate 8 is arranged as a compensation electrode parallel and at the same distance as the counter electrode 2 to the measuring electrode 1.
  • Base plate 8, measuring electrode 1 and counter electrode 2 are (in some cases not shown) each in the form of a perforated plate. Due to the arrangement, flowing gas clouds with a net charge are initially shielded from the outside by the shield 5.
  • there is approximately the same amount of gas flowing through each in the measuring space 9 and in the compensation space 10 as a result of which the amount of influence by net charge is approximately the same.
  • gas flowing through in the direction of the arrow moves towards the measuring electrode 1 in the measuring space 9, but moves away from the measuring electrode 1 in the compensation space 10
  • the resulting influence currents each have opposite polarity, so that the effects of net charge are compensated for.
  • FIG. 3 shows an exemplary embodiment in which two counter electrodes 2 enclose a measuring electrode 1 between them and thereby delimit two measuring spaces 9 and 9 '.
  • the counter electrodes 2 are designed as perforated plates, lie on ground and at the same time serve to shield the arrangement from the outside.
  • the measuring electrode 1 is attached to the base plate 8 by an insulator arrangement, not shown. Since both counter electrodes 2 are at the same potential with respect to the measuring electrode 1, the field distribution is symmetrical, that is to say that ions of negative polarity drift both in the measuring space 9 and in the measuring space 9 and the resulting influencing current is determined in the measuring arrangement 3 can be.
  • the sensitivity of the arrangement is increased due to the two measuring rooms 9 and 9. In addition, compensation of net charge influences is ensured by the symmetry of the arrangement.
  • Figure 4 shows an arrangement in which a cylindrical, symmetrical design of all parts, ie the shield 5, the measuring electrode 1 and the counter electrodes 2 is provided.
  • the outer of the two counter electrodes 2 is fastened to the shield 5 by means of bolts 12 made of insulation material.
  • the measuring electrode 1 and the second counter electrode 2 are mechanically connected to one another by means of insulation elements 13a, 13b, which are also bolt-shaped.
  • a metal disk 14 is arranged between the insulation elements 13a and 13b, which lies on ground. Leakage currents between the counter electrodes 2 and the measuring electrode 1 are thus avoided.
  • the cylindrical configuration of the counter electrode 2 with a base plate 2a which also corresponds to the configuration of the other counter electrode 2 or the measuring electrode 1 and the shield 5, is shown schematically in the upper section of FIG. 4.
  • This arrangement also has the advantage that the insulation elements are not directly exposed to the air flow and are therefore protected against contamination.
  • a gas cloud with charged smoke particles flowing through the arrangement in the direction of the arrow strikes the outside of the measuring electrode 1 (at A) coming from the right and the inside of the measuring electrode 1 (at B) before leaving the arrangement. Since the measuring electrode 1 is cylindrical and constitutes a closed circuit, influent currents due to net charge will accordingly have opposite polarity and will be automatically compensated.
  • shield 5 which is also designed as a perforated plate
  • outer counter electrode 2 thus delimit an annular compensation space 14, which, however, has a smaller field strength than the two measurement spaces 9 and 9 due to the greater distance.
  • compensation space 14 small, slowly flowing charged are therefore Particles already separated before they get into the measuring room 9 or 9. This results in a size-selective pre-separation, which can be of great advantage to reduce false alarms.
  • FIG. 5 shows an exemplary embodiment of a measuring electrode which consists of a plurality of stamped-out sheet metal strips 15 which are connected to one another by means of an electrically conductive rail 16.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Abstract

Avertisseur d'incendie avec une chamber de mesures (9, 9') limitée par deux électrodes (1, 2), un champ électrique étant produit entre les électrodes par une source de tension continue. L'électrode de mesure (1) n'a pas de liaison directe avec la source de tension continue (4) à l'entrée d'une installation de mesure du courant (3). Dès que des particules chargées de fumée pénètrent dans la chambre de mesures (9) entre les électrodes, le champ électrique provoque un déplacement des particules positives et négatives. En raison de ce déplacement de charge (dérive de charge), un courant est induit dans l'électrode de mesure, courant qui est mesuré.Fire alarm with a measurement chamber (9, 9 ') limited by two electrodes (1, 2), an electric field being produced between the electrodes by a DC voltage source. The measurement electrode (1) has no direct connection with the DC voltage source (4) at the input of a current measurement installation (3). As soon as smoke charged particles enter the measurement chamber (9) between the electrodes, the electric field causes a displacement of the positive and negative particles. Due to this charge displacement (load drift), a current is induced in the measuring electrode, which current is measured.

Description

Brandmelder und dafür bestimmte Elektrodenanordnung Fire detector and electrode arrangement intended for it
Die Erfindung betrifft einen Brandmelder mit wenigstens zwei Elektroden, zwischen denen durch eine Gleichspannungsquelle ein elektrisches Feld erzeugt wird, wobei die einander gegenüberliegenden Elektroden-Oberflächen einen Messraum begrenzen, durch welchen die durch Konvektion bewegte Luft eines zu überwachenden Raumes streichen kann, und wobei eine der Elektroden als Messelektrode und die andere als Gegenelektrode ausgebildet ist, und eine Strom-Messanordήung und Auswertungsschaltung vorgesehen ist.The invention relates to a fire detector with at least two electrodes, between which an electric field is generated by a DC voltage source, the opposite electrode surfaces delimiting a measuring space through which the air moved by convection of a room to be monitored can pass, and one of the Electrodes as the measuring electrode and the other as the counter electrode, and a current measuring arrangement and evaluation circuit is provided.
Brandmelder vergleichbarer Art sind in verschiedenen Ausführungen bekannt und gebräuchlich. So zeigt z.B. die US-PS 2,408,051 (Donelian) einen Brandmelder mit zwei Messräumen, wobei im ersten Messraum Kleinteilchen und Klein-Ionen elektrisch "herausgefiltert" werden und im zweiten Messraum die Luft mit Hilfe eines radioaktiven Präparats ionisiert wird. Die so entstehende Leitfähigkeit wird beim Vorhandensein von Rauch reduziert , weil sich Ionen an die schwer beweglichen Rauchteilchen anlagern. Erreicht die Reduktion der Leitfähigkeit in der Ionisationskammer eine Schwelle, so wird der Alarm ausgelbst. Bei der genannten US-PS 2,408,051 sind dabei die Elektroden, welche die Messräume begrenzen, nach Art eines kapazitiven Spannungsteilers in Serie zwischen den Plus- bzw. den Minuspol einer Gleichspannungsquelle angeschlossen. Ausserdem sind relativ niedrige Feldstärken von etwa 40 oder 50 Volt/cm im ersten Messraum vorgesehen. Der Brandmelder gemäss dieser US-PS benötigt zwingend die beiden Messkammern, wobei der Kachteil der mit radioaktivem Stoff versehenen zweiten Messkammer schon im Hinblick auf Umwelteinflüsse bekannt ist. Die Anordnung ist ausserdem aufwendig in der Konstruktion.Fire detectors of a similar type are known and used in various designs. For example, US Pat. No. 2,408,051 (Donelian) shows a fire detector with two measuring rooms, small particles and small ions being "filtered out" electrically in the first measuring room and the air being ionized in the second measuring room with the aid of a radioactive preparation. The resulting conductivity is reduced when smoke is present because ions attach to the difficult-to-move smoke particles. If the reduction in conductivity in the ionization chamber reaches a threshold, the alarm is extinguished. In the aforementioned US Pat. No. 2,408,051, the electrodes which delimit the measuring spaces are connected in series in the manner of a capacitive voltage divider between the positive and negative poles of a DC voltage source. In addition, relatively low field strengths of about 40 or 50 volts / cm are provided in the first measuring room. The fire detector in accordance with this US PS requires the two measuring chambers, the cache part of the second measuring chamber provided with radioactive material being already known with regard to environmental influences. The arrangement is also complex in construction.
Aus der US-PS 3,754,219 (Klein) ist ein Gerät zur Ermittlung von Luftverschmutzung oder Rauch ersichtlich, bei welchem die Überschussladung ("net Charge") gemessen wird. Die Überschussladung schwankt aber bei Bränden derart stark, dass ein auf diesem Prinzip arbeitenderFrom US Pat. No. 3,754,219 (Klein) a device for determining air pollution or smoke can be seen, in which the excess charge ("net charge") is measured. The excess charge fluctuates so much in the event of fire that a person working on this principle
Brandmelder praktisch nicht einsetzbar ist. Gleiches gilt für den Feuer- und Rauchdetektor gemäss US-PS 3,470,551 (Jaffe et al) .Fire detector is practically unusable. The same applies to the fire and smoke detector according to US Pat. No. 3,470,551 (Jaffe et al).
Zwar sind Ionenmessgeräte oder Messanordnungen zur Ermittlung der Beweglichkeit von Partikeln bekannt, wie dies z.B. aus der US-PS 4,114,088 hervorgeht, doch ist bislang weder der Einsatz derartiger Messgeräte als Brandmelder vorgeschlagen worden, noch eignen sie sich aufgrund der konstruktiven Ausbildung für einen solchen Einsatz. Vielmehr dominieren Feuermelder mit Ionisationskammern, insbesondere unter Verwendung radioaktiver Präparate, obwohl der Bedarf nach vereinfachten, die Umwelt weniger belastenden und vor allem ohne radioaktive Stoffe arbeitenden Brandmeldern konstant und seit langem besteht. Dies geht auch aus dem Aufsatz von Scheidweiler in "Staub-Reinhalt.Luft, Vol. 32 No.11 November , 1972" hervor .Ion measuring devices or measuring arrangements for determining the mobility of particles are known, as is the case e.g. from US Pat. No. 4,114,088, but so far neither the use of such measuring devices as fire detectors has been proposed, nor are they suitable for such use due to the design. Rather, fire detectors with ionization chambers dominate, especially using radioactive preparations, although the need for simplified fire detectors that are less polluting and, above all, work without radioactive substances has been constant and has existed for a long time. This is also evident from Scheidweiler's article in "Staub-Reinhalt.Luft, Vol. 32 No.11 November, 1972".
Der Erfindung liegt dementsprechend die Aufgabe zugrunde, einen verbesserten, hoch sensitiven und wesentlich vereinfachten Brandmelder sowie eine dafür bestimmte Elektrodenanordnung zu schaffen, die ohne radioaktive Präparate zur Ionisation einsetzbar ist.The invention is accordingly based on the object of providing an improved, highly sensitive and substantially simplified fire detector and a dedicated electrode arrangement which can be used for ionization without radioactive preparations.
Erfindungsgemäss wird dies in erster Linie dadurch erreicht, dass wenigstens eine der Elektroden mit Zirkula tions-Öffnungen für die zu überwachende Umgebungsluft versehen ist und/oder aus einer Mehrzahl von derart mit Zwischenräumen angeordneten Teilelektroden besteht, dass durch diese Zwischenräume Umgebungsluft in den Messraum strömen kann, dass die Gleichspannungsquelle einerseits direkt oder indirekt mit der Gegenelektrode und andererseits mit der Strom-Messanordnung verbunden ist, und dass die Messelektrode ohne direkte Verbindung mit der Gleichspannungsquelle an den Eingang der Strom-Messanordnung angeschlossen ist.According to the invention, this is primarily achieved in that at least one of the electrodes with a circula tion openings for the ambient air to be monitored and / or consists of a plurality of partial electrodes arranged with spaces in such a way that ambient air can flow into the measuring space through these spaces that the DC voltage source on the one hand directly or indirectly with the counter electrode and on the other hand with the current -Measuring arrangement is connected, and that the measuring electrode is connected to the input of the current measuring arrangement without a direct connection to the DC voltage source.
Die Erfindung geht dabei erstmals in optimal einfacher Weise von dem Prinzip aus, dass Rauchteilchen aus Verbrennungen prinzipiell stark elektrisch geladen sind. Dies rührt daher, dass sich positive und negative Kleinionen an die Teilchen anlagern. Diese werden schon in normaler Umgebung ständig in der Luft gebildet, insbesondere durch kosmische Strahlung und natürliche Radioaktivität. Die Wahrscheinlichkeit dafür, dass ein Teilchen vom Radius R im thermodynamischen Gleichgewicht die Ladung q = p · e besitzt, ist mit der Coulombenenergie p2e2/2R durch das Boltzmanngesetz gegeben. Die Konzentration der Teilchen vom Radius R mit p Elementarladungen ist demnachThe invention is based for the first time in an optimally simple manner on the principle that smoke particles from burns are principally strongly electrically charged. This is due to the fact that positive and negative small ions attach to the particles. These are constantly formed in the air even in normal surroundings, especially through cosmic rays and natural radioactivity. The probability that a particle of radius R has the charge q = p · e in thermodynamic equilibrium is given by the Coulomb energy p 2 e 2 / 2R by the Boltzmann law. The concentration of the particles of radius R with p elementary charges is accordingly
; wobei nR die Gesamtkonzentration der neutralen Teilchen mit Radius R ist, k die Boltzmannkonstante und T die absolute Temperatur. Daraus folgt für den quadratischen Mittelwert j (2) berücksichtigt allerdings nicht die diskrete Natur der Ladung und ist für Teilchen mit R <0,1 μm, die nur wenige Elementarladungen tragen, ungenau. Bei gleicher Konzentration von gleich beweglichen positiven und negativen Ionen stellt sich eine stationäre Teilchenladungsverteilung ein, die der Boltzmannverteilung entspricht. Die mittlere Partikelladung ist bei Boltzmannverteilung exakt null und in der Luft im stationären Fall wenig verschieden von null, da negative Kleinionen einen ca. 20% höheren Anlagerungskoeffizienten haben als positive.; where n R is the total concentration of the neutral particles with radius R, k is the Boltzmann constant and T is the absolute temperature. From this it follows for the quadratic mean j However, (2) does not take into account the discrete nature of the charge and is only few for particles with R <0.1 μm Carrying elementary charges, imprecise. With the same concentration of equally movable positive and negative ions, a stationary particle charge distribution is obtained which corresponds to the Boltzmann distribution. The mean particle charge is exactly zero for Boltzmann distribution and little different from zero in stationary air, since negative small ions have a 20% higher deposition coefficient than positive ones.
Es ist an sich schon bekannt, dass aus einer Verbrennung stammende Rauchteilchen besonders stark elektrisch geladen sind. Das ist schon dadurch verständlich, dass in einer Flamme infolge verschiedener Prozesse eine grosse Kleinionenkonzentration herrscht und laut Boltzmanngesetz eine hohe Temperatur zu hoher Teilchenladung führt. Ist der Rauch dicht (typ. bei Feuer: 107 Teilchen/cm3), so bleibt eine erhöhte Aufladung noch lang erhalten, bevor sich das Boltzmanngleichgewicht bei Zimmertemperatur einstellt, da die Kleinionennachlieferung zur Neutralisierung der Teilchen klein ist. Obwohl gerade bei Flammenaerosolen noch andere Aufladungsmechanismen in Frage kommen, kann allgemein gesagt werden:It is known per se that smoke particles originating from combustion are particularly strongly electrically charged. This is understandable because a small ion concentration in a flame as a result of various processes is high and according to the Boltzmann law a high temperature leads to a high particle charge. If the smoke is dense (typically in the case of fire: 10 7 particles / cm 3 ), an increased charge is maintained for a long time before the Boltzmann equilibrium is established at room temperature, since the small ion supply to neutralize the particles is small. Although other charging mechanisms can be considered for flame aerosols, it can generally be said:
(1) Jedes in der Umwelt vorkommende Aerosol besitzt nacri langer Zeit mindestens die Aufladung der(1) Every aerosol occurring in the environment has for a long time at least the charge of
Boltzmannverteilung bei Umgebungstemperatur, undBoltzmann distribution at ambient temperature, and
(2) dichter Rauch, der aus einer heissen Zone mit grosser Ionenkonzentration (Flamme) stammt, besitzt eine Aufladung, die grosser ist als die unter (1 ) genannte und behält diese während langer Zeit.(2) Dense smoke that comes from a hot zone with a high ion concentration (flame) has a charge that is greater than that mentioned under (1) and retains it for a long time.
Man beachte, dass hier unter "Aufladung des Rauchs" der Mittelwert des Betrags der Teilchenladung gemeint ist. Der erfindungsgemässe Brandmelder misst den Betrag derNote that the "charge of the smoke" means the average of the amount of the particle charge. The fire detector according to the invention measures the amount of
Teilchenladung eines bestimmten Vorzeichens, funktioniert also auch, wenn die Nettoladung des Rauchs null ist. Bei einer solchen Ladungsverteilung sitzen gleich viele posi tive wie negative Ionen auf den Rauchteilchen. Erfindungsgemäss wird nun eine sichere Detektion des Rauchs im Feld zwischen Messelektrode und Gegenelektrode durch elektrostatische Trennung positiver und negativer Teilchen und Messung der Ladung eines Vorzeichens oder durch Messung der durch den Rauch hervorgerufenen Änderung der Leitfähigkeit gewährleistet. Der so entstehende elektrische Strom ist bei Feldstärken, die noch nicht zu Glimmendladungen führen, wenigstens jedoch 100 Volt/cm betragen, zwar relativ klein, jedoch ohne weiteres mit elektronischen Verstärkern oder kleinen Elektroskopen messbar.Particle charge of a certain sign also works if the net charge of the smoke is zero. With such a charge distribution, there are the same number of posi tive as negative ions on the smoke particles. According to the invention, reliable detection of the smoke in the field between the measuring electrode and counterelectrode is now ensured by electrostatically separating positive and negative particles and measuring the charge of a sign or by measuring the change in conductivity caused by the smoke. The electric current thus generated is relatively small at field strengths which do not yet lead to glow discharge, but at least amount to 100 volts / cm, but can easily be measured with electronic amplifiers or small electroscopes.
Vorteilhafterweise beträgt der Elektrodenabstand weniger als 10 mm, jedoch mehr als 1 mm. Es hat sich nämlich gezeigt, dass durch diese besondere Dimensionierung eine Mehrzahl von vorteilhaften Eigenschaften erreichbar ist: Der relativ kleine Messraum bewirkt eine gute Abschirmung der Messelektrode gegen Influenz durch Nettoladung; andererseits ist der Abstand genügend gross, um Fehlmeldungen durch eventuell abgelagerte Staub- oder Russpartikel zu vermeiden. Zudem hat sich gezeigt, dass bei einem derartigen Elektrodenabstand auch mit Spannungen in einem optimalen Bereich gearbeitet werden kann, die einerseits zuverlässige Trennung und Abscheidung geladener Teilchen gewährleisten und andererseits Verschmutzung durch konstante Anziehung und Ablagerung von Staubpartikeln vermeiden.The electrode spacing is advantageously less than 10 mm, but more than 1 mm. It has been shown that a number of advantageous properties can be achieved through this special dimensioning: the relatively small measuring space provides a good shielding of the measuring electrode against influence by net charge; on the other hand, the distance is large enough to avoid false reports from possibly deposited dust or soot particles. In addition, it has been shown that with such an electrode spacing, it is also possible to work with voltages in an optimal range, which on the one hand ensure reliable separation and separation of charged particles and on the other hand avoid contamination by constant attraction and deposition of dust particles.
Die Erfindung beruht vorteilhafterweise nicht auf der bei bekannten Geräten praktizierten Messung der Überschussoder Nettoladung, sondern auf der Ladungsmessung nach elektrostatischer Trennung positiver und negativer Teilchen.The invention is advantageously not based on the measurement of the excess or net charge practiced in known devices, but on the charge measurement after electrostatic separation of positive and negative particles.
Vorteilhafterweise kann eine Hilfs-Elektrodenanordnung vorgesehen werden, welche kleine und/oder durch langsame Strömung getragene geladene Teilchen vorabscheidet, bevor sie in den Messraum gelangen können. Auf diese Weise kann die Empfindlichkeit auf kleine Rauchquellen, die kleine Teilchen und/oder nur langsame konvektive Strömung hervorrufen (Zigaretten), reduziert werden.Advantageously, an auxiliary electrode arrangement can be provided which pre-separates small and / or charged particles carried by slow flow before they can get into the measuring space. That way the sensitivity to small smoke sources that cause small particles and / or only slow convective flow (cigarettes) are reduced.
Die Nettoladungsunterdrückung lässt sich auch dadurch erreichen oder noch weiter verbessern, dass ein Kompensationsraum vorgesehen ist, der einerseits durch die Messelektrode und andererseits durch eine Kompensationselektrode begrenzt wird. Dadurch wird die Messelektrode von der Influenz durch Nettoladung z.B. in grossen Rauchwolken auf beiden Seiten abgeschirmt und es wird nur diejenige in einem relativ kleinen, durch den Messraum und/oder den Kompensationsraum beschränkten Volumen gemessen. Vorteilhafterweise kann dabei die Kompensationselektrode gleichzeitig als Abschirmung der Elektrodenanordnung ausgebildet sein.The net charge suppression can also be achieved or further improved by providing a compensation space which is delimited on the one hand by the measuring electrode and on the other hand by a compensation electrode. As a result, the measuring electrode is influenced by the influence of net charge e.g. shielded in large smoke clouds on both sides and only that in a relatively small volume limited by the measuring space and / or the compensation space is measured. Advantageously, the compensation electrode can simultaneously be designed as a shield for the electrode arrangement.
Die vorstehend beschriebenen Einflüsse durch die Nettoladung bzw. durch Influenz lassen sich sogar vollständig kompensieren, wenn der Kompensationsraum mit etwa gleichem Abstand zur Messelektrode angeordnet ist wie der Messraum und auch etwa das gleiche Volumen durchströmender Umgebungsluft aufzunehmen imstande ist. Dadurch wird nämlich erreicht, dass die Influenz durch im Messraum zuströmende Gase mit hoher Nettoladung ausgeglichen wird durch die Influenz mit umgekehrter Polarität durch im Kompensationsraum wegströmende Gase.The influences described above by the net charge or by influence can even be completely compensated for if the compensation space is arranged at approximately the same distance from the measuring electrode as the measurement space and is also able to absorb approximately the same volume of ambient air flowing through. This means that the influence of gases flowing in the measuring space with a high net charge is compensated for by the influence of reversed polarity caused by gases flowing away in the compensation space.
Vorteilhaft lässt sich auch Kompensation erreichen, wenn die Messelektrode in bezug auf den Luftstrom derart angeordnet ist, dass der Luftstrom die Messelektrode zweimal bestreicht, dabei jedoch von jeweils gegenüberliegenden Seiten auftrifft, bzw. die Elektrode durchströmt, so dass Influenzströme, die durch Nettoladung der durchtretenden Umgebungsluft bzw. von Rauchwolken in der Messelektrode auftreten, kompensiert werden. Durch das Auftreffen des geladenen Rauches von unterschiedlichen Seiten her auf die Elektrode werden ersichtlicherweise Influenzströme entge gengesetzter Polarität erzeugt, die sich auf einfachsteCompensation can also advantageously be achieved if the measuring electrode is arranged with respect to the air flow in such a way that the air flow sweeps the measuring electrode twice, but strikes it from opposite sides, respectively, or flows through the electrode, so that influence currents caused by the net charge of the passing through Ambient air or smoke clouds appear in the measuring electrode can be compensated. Influence currents are evidently counteracted by the charged smoke hitting the electrode from different sides generated opposite polarity, which is simplest
Weise in der Elektrode selbst aufheben. Dieses Prinzip lässt sich erfindungsgemäss vervollkommnen, wenn die Elektrode als quer zur Strömungsrichtung elektrisch geschlossener Kreis ausgebildet ist.Pick up in the electrode itself. This principle can be perfected according to the invention if the electrode is designed as a circle which is electrically closed transversely to the direction of flow.
Als Elektrodenanordnung für den erfindungsgemässen Brandmelder eignet sich besonders eine als Gitter ausgebildete Messelektrode und/oder Kompensationselektrode; dies erleichtert die Konvektion und verhindert, dass die imParticularly suitable as an electrode arrangement for the fire detector according to the invention is a measuring electrode and / or compensation electrode designed as a grid; this facilitates convection and prevents the im
Messraum befindliche Luft bzw. das Gas an Ladungen verarmt. Ausserdem wird sichergestellt, dass vor allem im Zusammenhang mit dem vorstehend beschriebenen Prinzip der Kompensation durch einen Kompensationsraum und/oder zweifaches Durchströmen der Messelektrode einfache Kompensation von Nettoladungs-Einflüssen ermöglicht wird. Dabei lässt sich die Messelektrode auch aus mehreren elektrisch verbundenen Teilelektroden aufbauen, die durch Luft. bzw. Gaswolken derart durchströmt werden, dass sich die Influenz-Einflüsse durch Nettoladung in den Teilelektroden aufheben.Air or gas in the measuring room is depleted of charges. In addition, it is ensured that, especially in connection with the principle of compensation through a compensation space and / or double flow through the measuring electrode described above, simple compensation of net charge influences is made possible. The measuring electrode can also be constructed from several electrically connected partial electrodes, which are caused by air. or gas clouds are flowed through in such a way that the influence of influence is canceled out by the net charge in the partial electrodes.
Besonders hervorragende Messergebnisse lassen sich erfindungsgemäss erreichen, wenn die Messelektrode zwischen zwei Gegenelektroden angeordnet ist, wobei die beidenParticularly excellent measurement results can be achieved according to the invention if the measuring electrode is arranged between two counter electrodes, the two
Gegenelektroden an die Gleichspannungsquelle angeschlossen sind und die Messelektrode zwischen den Gegenelektroden vorgesehen und mit dem Eingang der Messanordnung verbunden ist. Dadurch wird erreicht, dass die Felder in den beiden Messräumen zwischen den beiden Gegenelektroden und derCounter electrodes are connected to the DC voltage source and the measuring electrode is provided between the counter electrodes and is connected to the input of the measuring arrangement. This ensures that the fields in the two measuring rooms between the two counter electrodes and the
Messelektrode symmetrisch zu dieser verlaufen, d.h. also dass auf die Messelektrode von beiden Messräumen her geladene Teilchen gleicher Polarität auftreffen. Dies garantiert insbesondere hohe Empfindlichkeit.Measuring electrode run symmetrically to it, i.e. in other words, particles of the same polarity charged from both measuring rooms hit the measuring electrode. This guarantees high sensitivity in particular.
Die Messelektrode wird an den Eingang der Messanordnung angeschlossen und ist damit virtuell auf dem Potential der anderen Seite der Messanordnung. Sie lässt sich vor teilhaft mittels Isolationselementen mit einem Elektrodengehäuse und/oder den Gegenelektroden mechanisch starr verbinden, wobei die Isolationselemente durch elektrisch leitende Teile unterbrochen sind, die mit der anderen Seite der Messelektrode verbunden sind. Damit wird vermieden, dass Kriechströme an den Isolationselementen mitgemessen werden.The measuring electrode is connected to the input of the measuring arrangement and is therefore virtually at the potential of the other side of the measuring arrangement. She lets herself down partially mechanically rigidly connect by means of insulation elements with an electrode housing and / or the counter electrodes, the insulation elements being interrupted by electrically conductive parts which are connected to the other side of the measuring electrode. This prevents leakage currents from being measured on the insulation elements.
Der technische Fortschritt und der erfinderische Inhalt des Anmeldungsgegenstands werden ersichtlicherweise sowohl durch die neuen Einzelmerkmale als auch insbesondere durch die Kombination und Unterkombination der verwendeten Merkmale gewährleistet.The technical progress and the inventive content of the subject of the application are evidently guaranteed both by the new individual features and in particular by the combination and sub-combination of the features used.
Die Erfindung ist im folgenden in Ausführungsbeispielen anhand der Zeichnungen näher erläutert. Es zeigen:The invention is explained below in exemplary embodiments with reference to the drawings. Show it:
Figur 1 die Prinzipdarstellung eines Brandmelders mit den Merkmalen der Erfindung, Figur 2 einen Brandmelder mit einer abgewandelten1 shows the basic illustration of a fire detector with the features of the invention, FIG. 2 shows a fire detector with a modified one
Elektrode, Figur 3 einen Brandmelder mit einer weiter abgewandeltenElectrode, Figure 3 shows a fire detector with a further modified
Elektrode, Figur 4 einen erfindungsgemässen Brandmelder mit zwei Messräumen und Aussenabschirmung,FIG. 4 shows a fire detector according to the invention with two measuring rooms and external shielding,
Figur 5 ein abgewandeltes Ausführungsbeispiel einer Messelektrode.Figure 5 shows a modified embodiment of a measuring electrode.
Figur 1 zeigt die Prinzipdarstellung eines erfindungsgemässen Brandmelders mit einer Messelektrode 1 , einer Gegenelektrode 2, einer schematisch dargestellten Messanordnung 3, die gleichzeitig der Alarmauslösung in bekannter Weise dient, sowie einer Gleichspannungsquelle 4. Messelektrode 1 und Gegenelektrode 2 sind mittels Isolationselementen 6 an einem Halter 7 befestigt, der seinerseits mit einer Grundplatte 8 verbunden ist. Der Halter 7 ist elektrisch leitfähig und liegt auf Masse, so dass über die Isolationselemente 6 keine Kriechströme zwischen der Messelektrode 1 und der Gegenelektrode 2 fliessen können, da die Messelektrode über die Messanordnung 3 - jedoch nur virtuell - auf Massepotential liegt. Dies ist im Hinblick auf die äusserst geringen fliessenden Ströme von Vorteil. Der Abstand von Messelektrode 1 und Gegenelektrode 2 beträgt 5 mm, die Spannung der Gleichspannungsquelle 4 beträgt 500 Volt, so dass zwischen den beiden Elektroden 1 und 2 eine Feldstärke von 1000 Volt/cm besteht. Gelangen nun geladene Rauchteilchen in den Messraum 9 zwischenFIG. 1 shows the basic illustration of a fire detector according to the invention with a measuring electrode 1, a counter electrode 2, a schematically illustrated measuring arrangement 3, which at the same time serves to trigger the alarm in a known manner, and a DC voltage source 4. Measuring electrode 1 and counter electrode 2 are connected to a holder 7 by means of insulation elements 6 attached, which in turn is connected to a base plate 8. The holder 7 is electrically conductive and lies on ground, so that over the insulation elements 6 can flow no leakage currents between the measuring electrode 1 and the counter electrode 2, since the measuring electrode via the measuring arrangement 3 - but only virtually - is at ground potential. This is advantageous in view of the extremely low flowing currents. The distance between the measuring electrode 1 and counter electrode 2 is 5 mm, the voltage of the direct voltage source 4 is 500 volts, so that there is a field strength of 1000 volts / cm between the two electrodes 1 and 2. Now charged smoke particles get into the measuring space 9 between
Messelektrode 1 und Gegenelektrode 2, so bewirkt das elektrische Feld eine Bewegung der positiven und negativen Teilchen zu den beiden Elektroden. Diese Ladungsbewegung (Ladungs-Drift) influenziert einen Strom in die Messelektrode 1, der in der Messanordnung 3 gemessen wird.Measuring electrode 1 and counter electrode 2, the electric field causes the positive and negative particles to move to the two electrodes. This charge movement (charge drift) influences a current into the measuring electrode 1, which is measured in the measuring arrangement 3.
Beim Ausführungsbeispiel sind die Messelektroden 1 und die Gegenelektrode 2 als etwa quadratische Platten mit einer Fläche von je 40 cm2 ausgebildet. Selbstverständlich lässt sich die Fläche der Elektroden je nach Anforderung und gewünschter Empfindlichkeit der Messanordnung ändern, wie dies z.B. auch aus dem Ausführungsbeispiel gemäss Figur 4 hervorgeht. Die Gesamtanordnung ist von einer Abschirmung 5 umgeben, die ebenfalls auf Masse liegt. Dadurch wird nicht nur ein mechanischer Schutz der Anordnung gewährleistet, sondern es werden auch Fehlereinflüsse durch Nettoaufladung einer schematisch angedeuteten Rauchwolke 30 insoweit kompensiert, als Einflüsse aus der Ladungswolke ausserhalb der Abschirmung 5 von der Messelektrode 1 ferngehalten werden und dadurch keine Influenzströme entstehen könnenIn the exemplary embodiment, the measuring electrodes 1 and the counter electrode 2 are designed as approximately square plates with an area of 40 cm 2 each. Of course, the area of the electrodes can be changed depending on the requirement and the desired sensitivity of the measuring arrangement, as can also be seen, for example, from the exemplary embodiment according to FIG. The overall arrangement is surrounded by a shield 5, which is also grounded. This not only ensures mechanical protection of the arrangement, but also influences of errors caused by net charging of a schematically indicated smoke cloud 30 are compensated to the extent that influences from the charge cloud outside the shield 5 are kept away from the measuring electrode 1 and thus no influence currents can arise
Wie schematisch dargestellt, ist sowohl die Messelektrode 1 als auch die Gegenelektrode 2 mit einer Vielzahl von Löchern 11 versehen, welche den Rauch allein aufgrund der Konvektion sowohl aus horizontaler Richtung als auch aus vertikaler Richtung kommend durch den Messraum 9 strömen lassen. Figur 2 zeigt eine Anordnung, bei der die Grundplatte 8 als Kompensationselektrode parallel und im gleichen Abstand wie die Gegenelektrode 2 zur Messelektrode 1 angeordnet ist. Grundplatte 8, Messelektrode 1 und Gegenelektrode 2 sind (teilweise nicht dargestellt) jeweils als Lochblech ausgebildet. Durch die Anordnung strömende Gaswolken mit Nettoladung werden zunächst nach aussen durch die Abschirmung 5 abgeschirmt. Ausserdem befindet sich im Messraum 9 und im Kompensationsraum 10 jeweils etwa die gleiche Menge durchströmenden Gases, wodurch die Influenz durch Nettoladung betragsmässig etwa gleich ist. Da sich jedoch in Pfeilrichtung durchströmendes Gas im Messraum 9 auf die Messelektrode 1 zubewegt, im Kompensationsraum 10 jedoch von der Messelektrode 1 wegbewegt, weisen die daraus resultierenden Influenzströme jeweils entgegengesetzte Polarität auf, so dass die Einflüsse durch Nettoladung kompensiert werden.As shown schematically, both the measuring electrode 1 and the counter electrode 2 are provided with a multiplicity of holes 11, which allow the smoke to flow through the measuring space 9 coming from the horizontal direction as well as from the vertical direction solely due to the convection. Figure 2 shows an arrangement in which the base plate 8 is arranged as a compensation electrode parallel and at the same distance as the counter electrode 2 to the measuring electrode 1. Base plate 8, measuring electrode 1 and counter electrode 2 are (in some cases not shown) each in the form of a perforated plate. Due to the arrangement, flowing gas clouds with a net charge are initially shielded from the outside by the shield 5. In addition, there is approximately the same amount of gas flowing through each in the measuring space 9 and in the compensation space 10, as a result of which the amount of influence by net charge is approximately the same. However, since gas flowing through in the direction of the arrow moves towards the measuring electrode 1 in the measuring space 9, but moves away from the measuring electrode 1 in the compensation space 10, the resulting influence currents each have opposite polarity, so that the effects of net charge are compensated for.
Figur 3 zeigt ein Ausführungsbeispiel, bei welchem zwei Gegenelektroden 2 eine Messelektrode 1 zwischen sich einschliessen und dadurch zwei Messräume 9 und 9' begrenzen. Die Gegenelektroden 2 sind als Lochblech ausgebildet, liegen auf Masse und dienen gleichzeitig der Abschirmung der Anordnung nach aussen. Die Befestigung der Messelektrode 1 an der Grundplatte 8 erfolgt durch eine nicht dargestellte Isolator-Anordnung. Da beide Gegenelektroden 2 in bezug auf die Messelektrode 1 auf gleichem Potential liegen, ist die Feldverteilung symmetrisch, d.h., dass sowohl im Messraum 9 als auch im Messraum 9 Ionen negativer Polarität auf die Messelektrode 1 zudriften und der daraus resultierende Influenzstrom in der Messanordnung 3 ermittelt werden kann. Die Empfindlichkeit der Anordnung ist aufgrund der beiden Messräume 9 und 9 erhöht. Ausserdem ist Kompensation von Nettoladungs-Einflüssen durch die Symmetrie der Anordnung gewährleistet.FIG. 3 shows an exemplary embodiment in which two counter electrodes 2 enclose a measuring electrode 1 between them and thereby delimit two measuring spaces 9 and 9 '. The counter electrodes 2 are designed as perforated plates, lie on ground and at the same time serve to shield the arrangement from the outside. The measuring electrode 1 is attached to the base plate 8 by an insulator arrangement, not shown. Since both counter electrodes 2 are at the same potential with respect to the measuring electrode 1, the field distribution is symmetrical, that is to say that ions of negative polarity drift both in the measuring space 9 and in the measuring space 9 and the resulting influencing current is determined in the measuring arrangement 3 can be. The sensitivity of the arrangement is increased due to the two measuring rooms 9 and 9. In addition, compensation of net charge influences is ensured by the symmetry of the arrangement.
Figur 4 zeigt eine Anordnung, bei welcher eine zylindrische, symmetrische Ausbildung sämtlicher Teile, d.h. der Abschirmung 5, der Messelektrode 1 und der Gegenelektroden 2 vorgesehen ist. Die äus.sere der beiden Gegeneelektroden 2 ist mittels Bolzen 12 aus Isolationsmaterial an der Abschirmung 5 befestigt. Die Messelektrode 1 sowie die zweite Gegenelektrode 2 sind mittels ebenfalls bolzenartig ausgebildeten Isolationselementen 13a, 13b mechanisch miteinander verbunden. Zwischen den Isolationselementen 13a und 13b ist jeweils eine Metallscheibe 14 angeordnet, die auf Masse liegt. Damit werden Kriechströme zwischen den Gegenelektroden 2 und der Messelektrode 1 vermieden. Die zylindrische Ausbildung der Gegenelektrode 2 mit einem Bodenblech 2a, die auch der Ausbildung der anderen Gegenelektrode 2 bzw. der Messelektrode 1 und der Abschirmung 5 entspricht, ist im oberen Abschnitt von Figur 4 schematisch dargestellt.Figure 4 shows an arrangement in which a cylindrical, symmetrical design of all parts, ie the shield 5, the measuring electrode 1 and the counter electrodes 2 is provided. The outer of the two counter electrodes 2 is fastened to the shield 5 by means of bolts 12 made of insulation material. The measuring electrode 1 and the second counter electrode 2 are mechanically connected to one another by means of insulation elements 13a, 13b, which are also bolt-shaped. A metal disk 14 is arranged between the insulation elements 13a and 13b, which lies on ground. Leakage currents between the counter electrodes 2 and the measuring electrode 1 are thus avoided. The cylindrical configuration of the counter electrode 2 with a base plate 2a, which also corresponds to the configuration of the other counter electrode 2 or the measuring electrode 1 and the shield 5, is shown schematically in the upper section of FIG. 4.
Diese Anordnung hat zudem noch den Vorteil, dass die Isolationselemente nicht direkt dem Luftstrom ausgesetzt und dadurch vor Verschmutzung geschützt sind.This arrangement also has the advantage that the insulation elements are not directly exposed to the air flow and are therefore protected against contamination.
Eine in Pfeilrichtung durch die Anordnung strömende Gaswolke mit aufgeladenen Rauchpartikeln trifft einmal von rechts kommend auf die Aussenseite der Messelektrode 1 (bei A) und vor dem Verlassen der Anordnung auf die Innenseite der Messelektrode 1 (bei B) auf. Da die Messelektrode 1 zylindrisch ausgebildet ist und einen geschlossenen Stromkreis darstellt, werden dementsprechend Influenzströme durch Nettoladung entgegengesetzte Polarität aufweisen und automatisch kompensiert.A gas cloud with charged smoke particles flowing through the arrangement in the direction of the arrow strikes the outside of the measuring electrode 1 (at A) coming from the right and the inside of the measuring electrode 1 (at B) before leaving the arrangement. Since the measuring electrode 1 is cylindrical and constitutes a closed circuit, influent currents due to net charge will accordingly have opposite polarity and will be automatically compensated.
Ersichtlicherweise besteht auch zwischen der Abschirmung 5, die ebenfalls als Lochblech ausgebildet ist, und der äusseren Gegenelektrode 2 ein elektrisches Feld. Abschirmung 5 und Gegenelektrode 2 begrenzen damit einen kreisringförmigen Kompensationsraum 14, der allerdings aufgrund des grösseren Abstandes kleinere Feldstärke aufweist als die beiden Messräume 9 bzw. 9 . Im Kompensationsraum 14 werden deshalb kleine, langsam strömende geladene Teilchen bereits abgeschieden, bevor sie in den Messraum 9 bzw. 9 gelangen. Dies bewirkt eine grössenselektive Vorabscheidung, die zur Reduktion von Fehlalarmen von grossem Vorteil sein kann.Obviously, there is also an electric field between the shield 5, which is also designed as a perforated plate, and the outer counter electrode 2. Shield 5 and counter electrode 2 thus delimit an annular compensation space 14, which, however, has a smaller field strength than the two measurement spaces 9 and 9 due to the greater distance. In the compensation space 14, small, slowly flowing charged are therefore Particles already separated before they get into the measuring room 9 or 9. This results in a size-selective pre-separation, which can be of great advantage to reduce false alarms.
Figur 5 zeigt ein Ausführungsbeispiel einer Messelektrode, die aus einer Mehrzahl von ausgestanzten Blechstreifen 15 besteht, die mittels einer elektrisch leitfähigen Schiene 16 miteinander verbunden sind. FIG. 5 shows an exemplary embodiment of a measuring electrode which consists of a plurality of stamped-out sheet metal strips 15 which are connected to one another by means of an electrically conductive rail 16.

Claims

PATENTANSPRÜCHE PATENT CLAIMS
1. Brandmelder mit wenigstens zwei Elektroden, zwischen denen durch eine Gleichspannungsquelle ein elektrisches Feld erzeugt wird, wobei die einander gegenüberliegenden Elektroden-Oberflächen einen Messraum begrenzen, durch welchen die durch Konvektion bewegte Luft eines zu überwachenden Raumes streichen kann, und wobei eine der Elektroden als Messelektrode und die andere als Gegenelektrode ausgebildet ist, und eine Strom-Messanordnung und Auswertungsschaltung vorgesehen ist, d a d u r c h g e k e n n z e i c h n e t, dass wenigstens eine der Elektroden (1,2) mit Zirkulations-Öffnungen (11) für die zu überwachende Umgebungsluft versehen ist und/oder aus einer Mehrzahl von derart mit Zwischenräumen angeordneten Teilelektroden (15) besteht, dass durch diese Zwischenräume Umgebungsluft in den Messraum (9,9a) strömen kann, dass die Gleichspannungsquelle (4) einerseits direkt oder indirekt mit der Gegenelektrode (2) und andererseits mit der Strom-MessanOrdnung (3) verbunden ist, und dass die Messelektrode (1) ohne direkte Verbindung mit der Gleichspannungsquelle (4) an den Eingang der Strom-Messanordnung angeschlossen ist.1. Fire detector with at least two electrodes, between which an electric field is generated by a DC voltage source, the opposite electrode surfaces delimiting a measuring space through which the air moved by convection can sweep through a room to be monitored, and wherein one of the electrodes as Measuring electrode and the other is designed as a counter electrode, and a current measuring arrangement and evaluation circuit is provided, characterized in that at least one of the electrodes (1, 2) is provided with circulation openings (11) for the ambient air to be monitored and / or from one There are a plurality of partial electrodes (15) arranged with gaps such that ambient air can flow into the measuring space (9, 9a) through these gaps, so that the DC voltage source (4) on the one hand, directly or indirectly with the counter electrode (2) and on the other hand with the current Measuring arrangement (3) is connected, un d that the measuring electrode (1) is connected to the input of the current measuring arrangement without a direct connection to the direct voltage source (4).
2. Brandmelder nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, dass die Spannungsquelle (4) und der Elektrodenabstand in Bezug zueinander derart dimensioniert sind, dass die elektrische Feldstärke wenigstens in einem Teil des Messraums mindestens 100 Volt pro Zentimeter beträgt. 2. Fire detector according to claim 1, characterized in that the voltage source (4) and the electrode spacing are dimensioned with respect to one another such that the electrical field strength is at least in one part of the measuring space at least 100 volts per centimeter.
3. Brandmelder nach Anspruch 1 und 2, d a d u r c h g e k e n n z e i c h n e t, dass der Elektrodenabstand kleiner ist als 10 mm und grosser als 1 mm.3. Fire detector according to claim 1 and 2, so that the electrode spacing is less than 10 mm and greater than 1 mm.
4. Brandmelder nach einem der Ansprüche 1 bis 3, d a d u r c h g e k e n n z e i c h n e t, dass im Luftstrom vor dem Messraum (9) wenigstens eine HilfsElektrodenanordnung (Fig.4/Abschirmung 5) vorgesehen ist zum Abscheiden von kleinen und/oder von langsamer Strömung getragenen, geladenen Teilchen aus dem Luftstrom.4. Fire detector according to one of claims 1 to 3, characterized in that at least one auxiliary electrode arrangement (FIG. 4 / shielding 5) is provided in the air flow in front of the measuring space (9) for separating small and / or charged particles carried by slow flow the airflow.
5. Brandmelder nach einem der vorangegangenen Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass als5. Fire detector according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that as
Messanordnung (3) ein mechanisches Elektroskop vorgesehen ist.Measuring arrangement (3) a mechanical electroscope is provided.
6. Brandmelder nach einem der Ansprüche 1 bis 4, d a d u r c h g e k e n n z e i c h n e t, dass als6. Fire detector according to one of claims 1 to 4, d a d u r c h g e k e n n z e i c h n e t that as
Messanordnung (3) ein elektronischer Verstärker vorgesehen ist.Measuring arrangement (3) an electronic amplifier is provided.
7. Brandmelder nach einem der vorangegangenen Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass zusätzlich zum Messraum (9) ein Kompensationsraum (10) vorgesehen ist, der einerseits durch die Messelektrode (1 ) und andererseits durch eine Kompensationselektrode(Fig.2/Grundplatte 8) begrenzt wird.7. Fire detector according to one of the preceding claims, that a compensation space (10) is provided in addition to the measuring space (9), which is limited on the one hand by the measuring electrode (1) and on the other hand by a compensation electrode (Fig. 2 / base plate 8).
8. Brandmelder nach Anspruch 7, d a d u r c h g e k e n n z e i c h n e t, dass die8. Fire detector according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the
Kompensationselektrode (8) als Abschirmung der Elektrodenanordnung (1,2) ausgebildet ist. Compensation electrode (8) is designed as a shield for the electrode arrangement (1, 2).
9. Brandmelder nach Anspruch 7 oder 8, d a d u r c h g e k e n n z e i c h n e t, dass der Kompensationsraum (10) etwa mit gleichem Abstand zur Messelektrode(1) wie der Messraum(9) angeordnet ist und etwa das gleiche Volumen der durchströmenden Umgebungsluft aufzunehmen im Stande ist.9. Fire detector according to claim 7 or 8, so that the compensation chamber (10) is arranged at approximately the same distance from the measuring electrode (1) as the measuring chamber (9) and approximately the same volume of the ambient air flowing through is able to absorb.
10. Brandmelder nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode (1) in Bezug auf den Luftstrom derart angeordnet ist, dass der Luftstrom die Messelektrode zweimal bestreicht, dabei jedoch von jeweils gegenüberliegenden Seiten auftrifft, bzw. die Elektrode durchströmt, so dass Influenzströme, die durch Nettoladung der durchtretenden Umgebungsluft bzw. von10. Fire detector according to one of the preceding claims, characterized in that the measuring electrode (1) is arranged in relation to the air flow in such a way that the air flow sweeps the measuring electrode twice, but in this case strikes from opposite sides, or flows through the electrode, so that Influence flows caused by the net charge of the ambient air passing through or
Rauchwolken in der Messelektrode (1) auftreten, kompensiert werden.Clouds of smoke appear in the measuring electrode (1) are compensated.
11. Brandmelder nach Anspruch 9, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode bzw. die Messelektroden als quer zur Strömungsrichtung elektrisch geschlossener Kreis ausgebildet sind.11. Fire detector according to claim 9, so that the measuring electrode or the measuring electrodes are designed as a circle that is electrically closed transversely to the direction of flow.
12. Elektrodenanordnung, insbesondere für einen Brandmeider nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode(n) (1) und/oder die Gegenelektrode(n) (2) und/oder die Kompensationselektrode als Gitteranordnung ausgebildet sind. 12. Electrode arrangement, in particular for a fire suppressor according to one of the preceding claims, that the measuring electrode (s) (1) and / or the counter electrode (s) (2) and / or the compensation electrode are designed as a grid arrangement.
13. Elektrodenanordnung insbesondere für einen Brandmelder nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode (1) und/oder die Gegenelektrode (2) für durch Konvektion bewegte Luft oder Gase strömungsdurchlässig sind. 13. Electrode arrangement in particular for a fire detector according to one of the preceding claims, characterized in that the measuring electrode (1) and / or the counter electrode (2) are flow-permeable for air or gases moved by convection.
14. Elektrodenanordnung nach Anspruch 12 oder 13, d a d u r c h g e k e n n z e i c h n e t, dass Mittel zum Lenken des durchströmenden Luft- bzw. Gasstroms derart vorgesehen sind und/oder die Messelektrode (1) derart ausgebildet ist, dass der Luftbzw. Gasstrom die Messelektrode wenigstens zweimal an räumlich verschiedenen Stellen bestreicht bzw. durchströmt und dabei einmal auf die Vorderseite und einmal auf die Rückseite der Messelektrode trifft.14. Electrode arrangement according to claim 12 or 13, so that means for directing the flowing air or gas flow are provided and / or the measuring electrode (1) is designed such that the air or. Gas flow brushes or flows through the measuring electrode at least twice at spatially different locations and thereby hits once on the front and once on the back of the measuring electrode.
15. Elektrodenanordnung nach Anspruch 14, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode (1) aus wenigstens zwei Teilelektroden (1) besteht, die von entgegengesetzten Seiten her vom Luft- bzw. Gasstrom durchströmt bzw. beaufschlagt werden.15. Electrode arrangement according to claim 14, so that the measuring electrode (1) consists of at least two partial electrodes (1) through which the air or gas flow flows or acts on from opposite sides.
16. Elektrodenanordnung nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass die Messelektrode (1) zwischen zwei Gegenelektroden (2) angeordnet ist, wobei die beiden Gegenelektroden an die Gleichspannungsquelle (4) angeschlossen sind und die Messelektrode zwischen den Gegenelektroden vorgesehen und mit dem Eingang der Messanordnung(3) verbunden ist. 16. Electrode arrangement according to one of the preceding claims, characterized in that the measuring electrode (1) is arranged between two counter electrodes (2), the two counter electrodes being connected to the direct voltage source (4) and the measuring electrode being provided between the counter electrodes and with the input of the Measuring arrangement (3) is connected.
17. Elektrodenanordnung nach Anspruch 16, d a d u r c h g e k e n n z e i c h n e t, dass die beiden Gegenelektroden (2) auf gleichem Potential liegen.17. Electrode arrangement according to claim 16, so that the two counter electrodes (2) are at the same potential.
18. Elektrodenanordnung nach Anspruch 6, d a d u r c h g e k e n n z e i c h n e t, dass die Messanordnung18. Electrode arrangement according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the measuring arrangement
(3) einerseits mit der Messelektrode (1) und anderseits mit dem anderen Potential der Spannungsquelle(3) on the one hand with the measuring electrode (1) and on the other hand with the other potential of the voltage source
(4) verbunden ist. (4) is connected.
19. Elektrodenanordnung nach einem der vorangehenden Ansprüche, d a d u r c h g e k e nn z e i c h n e t, dass die Messelektrode (1) mittels Isolationselementen (6,13,13a) mit einem Elektrodengehäuse (Grundplatte 8) und/oder den Gegenelektroden (2) verbunden ist, wobei die Isolationselemente durch elektrisch leitenden Teile (Halter 7, Metallscheiben 14) unterbrochen sind, die mit der nicht an die Messelektrode angeschlossenen Seite der Messanordnung (3) verbunden sind.19. Electrode arrangement according to one of the preceding claims, characterized in that the measuring electrode (1) is connected by means of insulation elements (6, 13, 13 a) to an electrode housing (base plate 8) and / or the counter electrodes (2), the insulation elements being connected by electrically conductive parts (holder 7, metal disks 14) are interrupted, which are connected to the side of the measuring arrangement (3) that is not connected to the measuring electrode.
20. Elektrodenanordnung nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass Messelektroden, (1 , 15) und Gegenelektroden (2) als strömungsdurchlässige Körper ausgebildet und ineinander angeordnet sind, wobei im Bereich des Messraums (9,9a) etwa konstanter Abstand zwischen Messelektroden und Gegenelektroden besteht.20. Electrode arrangement according to one of the preceding claims, characterized in that measuring electrodes (1, 15) and counter electrodes (2) are designed as flow-permeable bodies and are arranged one inside the other, with an approximately constant distance between measuring electrodes and counter electrodes in the region of the measuring space (9, 9a) consists.
21. Elektrodenanordnung nach Anspruch 20, d a d u r c h g e k e n n z e i c h n e t, dass Messelektroden (1,15) und Gegenelektroden (2) rotationssymmetrisch ausgebildet sind. 21. The electrode arrangement as claimed in claim 20, so that measuring electrodes (1, 15) and counter electrodes (2) are designed to be rotationally symmetrical.
EP83903778A 1982-12-03 1983-12-02 Fire alarm and electrode device therefor Expired EP0127645B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83903778T ATE38732T1 (en) 1982-12-03 1983-12-02 FIRE ALARM AND RELATED ELECTRODE ASSEMBLY.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH7028/82A CH666135A5 (en) 1982-12-03 1982-12-03 FIRE DETECTORS.
CH7028/82 1982-12-03

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EP0127645A1 true EP0127645A1 (en) 1984-12-12
EP0127645B1 EP0127645B1 (en) 1988-11-17

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EP83903778A Expired EP0127645B1 (en) 1982-12-03 1983-12-02 Fire alarm and electrode device therefor

Country Status (7)

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US (1) US4652866A (en)
EP (1) EP0127645B1 (en)
JP (1) JPS60500073A (en)
AU (1) AU572517B2 (en)
CH (1) CH666135A5 (en)
DE (1) DE3378505D1 (en)
WO (1) WO1984002215A1 (en)

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DE102014019773A1 (en) 2014-12-17 2016-06-23 Elmos Semiconductor Aktiengesellschaft Apparatus and method for distinguishing solid objects, cooking fumes and smoke by means of the display of a mobile telephone

Also Published As

Publication number Publication date
JPS6356596B2 (en) 1988-11-08
US4652866A (en) 1987-03-24
EP0127645B1 (en) 1988-11-17
JPS60500073A (en) 1985-01-17
CH666135A5 (en) 1988-06-30
DE3378505D1 (en) 1988-12-22
AU2983784A (en) 1986-01-02
WO1984002215A1 (en) 1984-06-07
AU572517B2 (en) 1988-05-12

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