EP0051006B1 - Method and devices to transfer electrical charges of opposed signs into a space-field, and its application to static eliminators - Google Patents

Method and devices to transfer electrical charges of opposed signs into a space-field, and its application to static eliminators Download PDF

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Publication number
EP0051006B1
EP0051006B1 EP81401536A EP81401536A EP0051006B1 EP 0051006 B1 EP0051006 B1 EP 0051006B1 EP 81401536 A EP81401536 A EP 81401536A EP 81401536 A EP81401536 A EP 81401536A EP 0051006 B1 EP0051006 B1 EP 0051006B1
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EP
European Patent Office
Prior art keywords
nozzle
generator according
space
charges
electrode
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EP81401536A
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German (de)
French (fr)
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EP0051006A3 (en
EP0051006A2 (en
Inventor
Serge Larigaldie
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Office National dEtudes et de Recherches Aerospatiales ONERA
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Office National dEtudes et de Recherches Aerospatiales ONERA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T23/00—Apparatus for generating ions to be introduced into non-enclosed gases, e.g. into the atmosphere
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • the present invention relates to techniques for modifying the electrical charge of a space area.
  • radioactive eliminators which use the ionizing properties of alpha and beta radiation to slightly ionize the air surrounding a body to be discharged.
  • the effectiveness of these devices is low due to the low degree of ionization which one can hope to achieve without using powerful radioactive sources (several tens of millicuries) including the potential dangers, as regards the risks personnel irradiation as accidental release of radioactive material, are not acceptable in many applications.
  • inductive type crown effect eliminators which consist of one or more conductive wires at ground potential and fitted with tips which are placed near the electrified bodies to be discharged.
  • the high value of the electric field near the tips promotes the transfer of charges between the electrified body and the eliminator.
  • crown Other eliminators with crown effect involve a high voltage electric source which creates an intense electric field in the vicinity of one or more points immersed in a gaseous medium in order to cause the formation of a discharge therein. crown, called corona discharge, generator of ions. The high voltage produced is alternating so as to alternately produce positive and negative ions in the medium surrounding the electrified body to be neutralized.
  • corona discharges into the air are accompanied by the formation of ozone, a highly oxidizing gas, capable of damaging certain materials or presenting harmful effects for people. This phenomenon sometimes obstructs the application of crown effect discharge eliminators.
  • the object of the invention is to provide a generator of electric charges of different signs in a space zone, which allows, in particular when it is applied to the atmosphere surrounding an electrified body, to effectively neutralize the latter.
  • the electric charge generator of the invention is of the type comprising, as in FR-A-2 419 647, an enclosure capable of receiving a gas under pressure and charged with a substance capable of condensing under the effect of the cooling caused by relaxation; a body of nozzle mounted at the end of this enclosure to relax the gas leaving this enclosure, in particular by an ejection nozzle; a tapered electrode whose tip is located near the neck of the nozzle; and a high voltage source as well as connection means suitable for electrically connecting this tapered electrode to a first terminal of said high voltage source and a conductive part of the nozzle body to a second terminal of this source, to produce a discharge by crown effect in the gas between said electrode and the neck of the nozzle.
  • This electric charge generator is essentially characterized in that said source is the secondary of a transformer delivering a high alternating voltage, in that the surface of said nozzle is electrically insulating on the side of the interior of the enclosure, and in that the means for connecting said tapered electrode and said conductive part of the nozzle body comprise a capacitor in series between this electrode and this conductive part.
  • the ions produced by the corona discharge constitute nuclei on which the microparticles of the condensable substance are formed.
  • the ions are thus trapped by the current of microparticles and they are then released by a phase loading of the microparticles to form the charge of the space zone. Thanks to the speed acquired by the microparticles, it is possible to charge an area of space at a relatively large distance from the enclosure inside which the transferred ions are created.
  • the charge level of the capacitor is then established at a value such that the supply voltages of the positive discharge and of the negative discharge are different and, respectively, produce positive and negative ion fluxes with equal yields.
  • the body of the nozzle can be a block of insulating material, the internal surface of which is suitably aerodynamically shaped, and in which a conductor is embedded, which is connected to the alternative power source of the electrode assembly. tapered nozzle, for example through the mass.
  • the above electric charge generator thus makes it possible to obtain balanced concentrations of very high simultaneously positive and negative charges at relatively considerable distances from the enclosure where the ions arise without the recombination of charges during transfer becoming excessive. .
  • the arrangements according to the invention are particularly advantageous when the space area is relatively difficult to access, for example in the case where electrified pulverulent materials are handled during an industrial process; or when it contains a flammable or explosive atmosphere. If the charged particles are ejected by a nozzle outside the enclosure in which they are formed, it is indeed possible to avoid any contact between the external atmosphere and the interior of the enclosure because of the unidirectional nature of the current of microparticles and its relatively high speed in the nozzle.
  • the invention also relates to the application of the generator which has just been defined to the elimination of static electricity from the electrified bodies.
  • the body may neutralize keeps a residual charge of low value and in particular likely to bring the potential of this object to safe values. If it is desired to eliminate this residual charge or to set it at a value different from that which results from the neutralization operation, in accordance with an additional aspect of the invention, the electric field is detected around this body and it is controlled the supply circuit of the discharge crowns the detected field so as to bring it to a desired value, for example zero.
  • an electric charge injector comprises an elongated insulating tubular body 10 closed at one end 12 and extended at its other end 14 by a body of revolution 16 whose internal profile defines a nozzle 18 comprising a narrowed part 20, followed by a neck 22, then by a diverging portion 24, when one moves away from the end 14 of the tubular body 10.
  • the divergent opening through an orifice 26 formed in the anterior face 28 of the body of nozzle 16, in a tube 30 coaxial with the nozzle 18, the end of which forms an ejection nozzle 32 towards the outside towards a space zone.
  • a needle 46 made of a conductive material centered on the axis of the tube 10 and comprising a point 48 at the neck 22 of the nozzle 18.
  • the rear end 49 of the needle 46 is electrically connected to a conductor 50 which passes through the end wall 12 of the body 10 by an insulating bushing 52.
  • a pipe 55 compressed air supply in the direction of arrow 56.
  • the body 10 is made of an insulating material.
  • the nozzle body 16 is conductive and electrically connected to ground by a conductor 60, the conductor 50 being connected to one end 67 of a high voltage secondary winding 62 of a transformer 64 supplied to its primary 66 by the AC mains voltage at 220 v.
  • the other end 68 of the winding 62 is connected to the ground.
  • Line 55 is connected to a compressor (not shown) supplied with moist air in order to inject, in the direction of the arrow 56, inside the injector body 10, moist compressed air which enters the nozzle body 16 and begins to relax at the level of the constriction 20 where it is accelerated by cooling. From the neck 22, it acquires a supersonic speed under the effect of the acceleration which is imparted to it by the diverging portion 24 of the nozzle and then enters the tube 30 to be ejected by the nozzle 32 out of the enclosure formed by inside the tube 10 of the nozzle 18 and of the tube 30.
  • a compressor supplied with moist air in order to inject, in the direction of the arrow 56, inside the injector body 10, moist compressed air which enters the nozzle body 16 and begins to relax at the level of the constriction 20 where it is accelerated by cooling. From the neck 22, it acquires a supersonic speed under the effect of the acceleration which is imparted to it by the diverging portion 24 of the nozzle and then enters the tube 30 to be
  • the high-voltage winding 62 applies an alternating voltage of several thousand volts, for example 20 kV between the point 48 of the needle 46 and the nozzle 18, this voltage being sufficient to allow an alternative corona discharge to be established at neck of this nozzle.
  • This discharge occurs in the air current during expansion in the narrow space which separates the point 48 from the neck of the nozzle 22 where an extremely high electric field prevails.
  • a space charge is formed composed of positive gas ions at the periphery of the corona discharge zone, while during the negative half-waves are formed negative gas ions creating a negative space charge around this discharge area.
  • the compressed air admitted into the tube 55 is supersaturated with water vapor which begins to condense, as soon as the air reaches the converging point of the nozzle, in the form of microdroplets, the gaseous ions formed in the vicinity of the point 48 forming condensation nuclei for these droplets.
  • these microdroplets Crystallize into microparticles of very small diameter ice (approximately 10 nm in diameter), the temperature of the air expanded in the divergent being able to lower up to 'at -90 ° Celsius.
  • the fine particles of aerosol charged alternately positively and negatively are entrained by the gas stream at very high speed inside the tube 30 and projected into the area of space opposite the nozzle 32, as will be explained below. .
  • a suitable air flow for such a device suitable for being used as a static eliminator of particles can be about 20 m 3 per hour, measured under normal conditions of temperature and pressure, and the corresponding pressure in the enclosure of approximately 5 bars.
  • the charge ejection speed inside the tube 30 is approximately 300 m / s.
  • the moist compressed air admitted into the tubing 55 can be obtained from ambient air provided that its humidity is greater than about 10%. In case the ambient air is very dry, a humidifier is provided at the inlet of the compressor. It has been found that the hygrometric degree indicated corresponds to a density of microparticles of ice at the level of the neck of the nozzle which is largely sufficient to come to trap almost all of the ions formed by the discharge.
  • the yields of ionized particles of the positive corona discharge and of the negative corona discharge are generally not the same for a given value of the supply voltage at the secondary 62.
  • the quantity of charges of each sign produced and the current resulting from the driving of these loads through the tube 30 depend on a high number of factors among which the state of the tip 48, the pressure and the hygrometric degree of the air used, the value of the applied voltage .
  • the ice microparticles entrained through the tube 30 escape the action of the electric field prevailing inside the injector thanks to their very low mobility and the high speed of the gas flow. These charges, after leaving the nozzle 32 move away from them to be recovered only at relatively high distance by a body connected to ground or the earth after they are released as will be explained below.
  • the tube 30 is made of a semiconductor material having a very high resistivity. This characteristic makes it possible to avoid the accumulation along this tube of residual charges deposited by the stream of particles during its path towards the orifice 32. Such an accumulation could indeed give rise to sliding discharges along the inner wall of the tube 30 with a substantial loss of the stream of particles reaching the outside of the nozzle.
  • microparticles are several orders of magnitude lower than that of gas ions. Thanks to this lower mobility, the probability of recombination of charges of contrary signs, near the emissive point where the concentration of charged particles is the greatest, is much lower than in the case of a corona discharge without relaxation in the air.
  • An injector 80 (FIG. 2) is very schematically represented with its nozzle 82 and an outlet nozzle 84 from which a jet 86 of air and charged microcrystals of ice gushes out at high speed which tends to become more and more turbulent at as it moves away from this nozzle 86 towards the space zone 90 located downstream. A few tens of centimeters downstream, the ice microparticles begin to evaporate in an intermediate zone 88, releasing the gaseous ions that they had previously trapped. In practice, it has been found that it is possible to obtain by this process high concentrations of positive and negative charges at distances of several meters from the nozzle 84 before the ions thus released recombine.
  • the nozzle body 122 is composed of an insulating material, for example a synthetic resin inside which is embedded a conductive ring or metal guard ring 132 connected to ground by a conductor 134, coated with a coating 137 of insulating resin similar to that which constitutes the nozzle body 122 over at least part of its path to earth or ground.
  • the needle 126 is connected to the capacitor C 130 by a conductor 136, itself coated with an insulator 138.
  • the device schematically illustrated in FIG. 3 supplied with alternating sinusoidal voltage or with rectangular slots with a peak value of 20 kV made it possible to obtain an almost simultaneous flow of charges of different signs at the output of this nozzle whose overall load was strictly zero.
  • this device to an eliminator of static electricity, the flow of charged particles emitted at the outlet and directed towards a zone of space surrounding an electrified body to be discharged is generally neutral.
  • Such an eliminator makes it possible to obtain the formation of a very high concentration of positive and negative ionized particles in the environment of the electrified body which remains completely balanced from the electrical point of view.
  • the insulating nozzle device of FIG. 3 sees the capacitor C 130 being charged at a relatively low potential, ie for example a few hundred volts. If the electrified body to be discharged is placed at a relatively close distance from the injector ejection nozzle, it can be seen that it maintains a level of potential at most equal to that of the needle 126. This level of potential of electrification of the order of 500 volts is completely safe if it is known that the potentials of electrification of the bodies that one seeks to discharge using the present invention can commonly reach several tens of kilovolts. It is noted that, when the body is moved away from the outlet of the injector, the level of this continuous potential on the body drops very appreciably.
  • An embodiment of the invention provides additional means for measuring the potential of the body with respect to a reference mass and means for acting on the value of the DC voltage of the tip 126 to control the electric potential of the body. to that of the reference mass.
  • the insulating material on the internal surface 124 of the nozzle constitutes a resistance of infinite value between the tip 125 and the conductor of the guard ring 132 (which constitutes the second electrode proper), while allowing the electric field to act.
  • the distance between this ring 132 and the surface of the nozzle results from a compromise capable of avoiding the breakdowns of said insulating coating, while making it possible to obtain a sufficient electric field and without requiring prohibitively high voltages.
  • the layer of insulator 137 enclosing the conductor 134 is intended to prevent the establishment of parasitic current paths between the tip 125 and the ground conductor 134.
  • the insulator 128 is intended to prevent the formation of currents interference between the conductor 136 charged to a continuous potential as has been explained, and the rest of the body 120 of the injector.
  • the capacitance of the capacitor C 130 is determined at a relatively low value so as to limit its level of electric charge when it is, in operation, brought to a polarization potential of approximately a few hundred volts. Indeed, when the corona discharge is triggered, any imbalance existing between the production of ions by the positive and negative alternations creates a direct current which gradually diminishes, by charging the capacitor C 130, until the fluxes negative and positive charges are equal. Part of this direct current strikes the electrified body to be discharged and can communicate to it a possible residual charge at most equal to that which the capacitor C 130 acquires. It is preferable to adopt a relatively low capacitance value for this latter capacitor in order to to limit the possible residual charge of the electrified body. Experience shows that in practice this can be limited to some 100 pF.
  • the residual charge is eliminated by means of an electronic device comprising means for measuring the electrical potential of the body and means for acting on the potential of the tip 126 with respect to the reference mass.
  • the electric potential of the body 140 (FIG. 4) is measured by means of a known device for measuring the electric field 141 connected to the reference mass and the signal produced is used to modify the potential relative to the mass of the tip 126 in order to bring back, or maintain the body 140 in the electrically neutral state.
  • an amplifier 142 connected to the output of the device 141 delivers a direct voltage which is of opposite sign to the residual potential of the body 140 and which is applied either to the ring (FIG.
  • the signal delivered by the amplifier 142 controls a variation in the amplitude of the alternating voltage which is applied to the primary winding of the transformer 64.
  • a device such as that which has just been described offers the possibility of transporting a flow of electric charges of different signs over relatively large distances (several meters) which, as explained above, may be advantageous in certain applications.
  • static eliminators especially for bodies in diffuse or powder form.
  • the interior of the enclosure defined by the injector body is practically isolated from the area of space considered by the gas jet which is in escape, no risk of contact between an explosive atmosphere in this area of space and the crown discharge inside this enclosure is to be feared.
  • the electrodes capable of producing the corona discharge can only be energized when the compressed air is admitted into the injector and escapes at high speed through the nozzle 32.
  • no electric arc can be established between the metal tip such as 125 and the ground, due to the insulating nozzle.
  • the device makes it possible to obtain extremely rapid elimination of the electrostatic discharges from a body to be neutralized in order to bring them back to a level of potential presenting no danger.

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  • Elimination Of Static Electricity (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Description

La présente invention concerne les techniques qui permettent de modifier la charge électrique d'une zone d'espace.The present invention relates to techniques for modifying the electrical charge of a space area.

On connaît des procédés pour créer une charge électrique de signe déterminé dans une zone d'espace, en y favorisant une concentration d'ions du même signe. On sait également que dans certaines situations, au lieu de chercher à charger une zone d'espace selon une polarité déterminée, il est utile d'élever son degré d'ionisation mais non sa charge globale en augmentant simultanément sa concentration en charges positives et négatives.Methods are known for creating an electric charge of a given sign in an area of space, by promoting a concentration of ions of the same sign. We also know that in certain situations, instead of trying to charge an area of space according to a determined polarity, it is useful to raise its degree of ionization but not its overall charge by simultaneously increasing its concentration in positive and negative charges .

L'élimination de l'électricité statique accumulée sur un corps électrisé représente un cas d'application de cette dernière technique. En effet, lorsqu'un tel corps est plongé dans un milieu contenant des charges positives et négatives, le champ électrique créé par ce corps attire les charges électriques de polarité contraire qui viennent neutraliser les charges accumulées sur le corps et repousse les charges de même polarité que le corps électrisé.The elimination of static electricity accumulated on an electrified body represents a case of application of the latter technique. Indeed, when such a body is immersed in a medium containing positive and negative charges, the electric field created by this body attracts electric charges of opposite polarity which neutralize the charges accumulated on the body and repels charges of the same polarity than the electrified body.

Le problème de l'élimination des charges électrostatiques revêt une grande importance dans divers domaines. De nombreux corps ont en effet tendance à accumuler des charges électriques positives ou négatives, soit par influence, lorsqu'ils sont disposés dans un champ électrique, soit sous l'effet des frottements mécaniques qui s'exercent entre surfaces de nature différente. Lorsque ces corps sont isolants, ou lorsqu'ils sont conducteurs mais non reliés à la terre, les charges tendent à s'accumuler sur ces corps pour les porter à des potentiels qui peuvent atteindre parfois des valeurs extrêmement élevées. Ces phénomènes d'électrisation sont responsables d'un certain nombre de dommages qui peuvent être d'ordre mécanique, effets de collage par exemple, ou d'ordre électrique, tels que les risques de choc électrique pour le personnel manipulant les corps électrisés ou bien risques d'étincelle suivie d'explosion dans des milieux inflammables, l'apparition d'effluves voilant les pellicules photographiques, etc...The problem of eliminating electrostatic charges is of great importance in various fields. Many bodies have a tendency to accumulate positive or negative electric charges, either by influence, when they are placed in an electric field, or under the effect of mechanical friction which is exerted between surfaces of different nature. When these bodies are insulating, or when they are conductive but not connected to the ground, the charges tend to accumulate on these bodies to bring them to potentials which can sometimes reach extremely high values. These electrification phenomena are responsible for a certain number of damages which can be mechanical, sticking effects for example, or electrical, such as the risks of electric shock for the personnel handling the electrified bodies or else risk of sparks followed by explosion in flammable environments, the appearance of aromas obscuring photographic film, etc.

Divers types de dispositifs éliminateurs de charges électriques fondés sur le principe d'une combinaison de charges d'un milieu environnant le corps avec les charges de signe opposé accumulées sur celui-ci ont déjà été proposés et utilisés.Various types of devices for eliminating electric charges based on the principle of a combination of charges from a medium surrounding the body with charges of opposite sign accumulated thereon have already been proposed and used.

Parmi ces dispositifs, on peut citer les éliminateurs radioactifs qui mettent en oeuvre les propriétés ionisantes des radiations alpha et bêta pour ioniser légèrement l'air environnant un corps à décharger. L'efficacité de ces dispositifs est faible en raison du degré d'ionisation peu élevé que l'on peut espérer atteindre sans faire appel à des sources radioactives puissantes (plusieurs dizaines de millicuries) dont les dangers potentiels, tant en ce qui concerne les risques d'irradiation du personnel que ceux de dissémination accidentelle de la matière radioactive, ne sont pas acceptables dans de nombreuses applications.Among these devices, mention may be made of radioactive eliminators which use the ionizing properties of alpha and beta radiation to slightly ionize the air surrounding a body to be discharged. The effectiveness of these devices is low due to the low degree of ionization which one can hope to achieve without using powerful radioactive sources (several tens of millicuries) including the potential dangers, as regards the risks personnel irradiation as accidental release of radioactive material, are not acceptable in many applications.

Il existe également des éliminateurs à effet couronne du type inductif qui sont constitués par un ou plusieurs fils conducteurs au potentiel de la terre et garnis de pointes que l'on dispose à proximité des corps électrisés à décharger. La forte valeur du champ électrique à proximité des pointes favorise le transfert de charges entre le corps électrisé et l'éliminateur.There are also inductive type crown effect eliminators which consist of one or more conductive wires at ground potential and fitted with tips which are placed near the electrified bodies to be discharged. The high value of the electric field near the tips promotes the transfer of charges between the electrified body and the eliminator.

D'autres éliminateurs à effet couronne mettent en jeu une source électrique à haute tension qui crée un champ électrique intense au voisinage d'une ou plusieurs pointes plongée(s) dans un milieu gazeux afin d'y provoquer la formation d'une décharge en couronne, appelée décharge corona, génératrice d'ions. La haute tension produite est alternative de façon à produire alternativement des ions positifs et négatifs dans le milieu environnant le corps électrisé à neutraliser.Other eliminators with crown effect involve a high voltage electric source which creates an intense electric field in the vicinity of one or more points immersed in a gaseous medium in order to cause the formation of a discharge therein. crown, called corona discharge, generator of ions. The high voltage produced is alternating so as to alternately produce positive and negative ions in the medium surrounding the electrified body to be neutralized.

On a constaté cependant que même ces éliminateurs à effet couronne souffraient d'insuffisances, et dans certains cas, pouvaient présenter des dangers.However, it has been found that even these crown eliminators suffer from shortcomings, and in some cases can be dangerous.

En particulier, on a reconnu que les dispositifs utilisés jusqu'à présent ne fonctionnent efficacement que lorsqu'ils sont disposés à proximité immédiate du corps à décharger. A défaut, les ions formés tendent à se recombiner, en raison de leur grande mobilité avant d'avoir pu entrer en contact avec ce corps et ceci d'autant plus rapidement que le niveau d'ionisation que l'on cherche à créer autour du corps est élevé. On a en outre constaté que la neutralisation était souvent imparfaite ou même que, dans certains cas, le corps tendait à acquérir une charge de signe contraire à celle qu'il avait avant la mise en oeuvre de l'éliminateur.In particular, it has been recognized that the devices used up to now only work effectively when they are placed in close proximity to the body to be discharged. Failing this, the ions formed tend to recombine, due to their great mobility before being able to come into contact with this body and this all the more quickly than the level of ionization that one seeks to create around the body is high. It has also been found that the neutralization was often imperfect or even that, in certain cases, the body tended to acquire a charge of sign contrary to that which it had before the implementation of the eliminator.

Par ailleurs, l'utilisation de ce type d'éliminateur est à proscrire dans les milieux inflammables ou explosifs car les décharges en couronne peuvent donner naissance à des étincelles propres à provoquer alors l'ignition du milieu dans lesquelles elles ont lieu.Furthermore, the use of this type of eliminator is to be avoided in flammable or explosive environments because corona discharges can give rise to sparks capable of causing ignition of the environment in which they take place.

Enfin, on sait que les décharges corona dans l'air s'accompagnent de la formation d'ozone, gaz très oxydant, susceptible de détériorer certains matériaux ou de présenter des effets nocifs pour les personnes. Ce phénomène fait parfois obstacle à l'application des éliminateurs de décharge à effet couronne.Finally, it is known that corona discharges into the air are accompanied by the formation of ozone, a highly oxidizing gas, capable of damaging certain materials or presenting harmful effects for people. This phenomenon sometimes obstructs the application of crown effect discharge eliminators.

L'invention a pour objet de fournir un générateur de charges électriques de signes différents dans une zone d'espace, qui permette, notamment lorsqu'il est appliqué à l'atmosphère environnant un corps électrisé, de neutraliser efficacement ce dernier.The object of the invention is to provide a generator of electric charges of different signs in a space zone, which allows, in particular when it is applied to the atmosphere surrounding an electrified body, to effectively neutralize the latter.

Le générateur de charges électriques de l'invention est du type comprenant, comme dans FR-A-2 419 647, une enceinte propre à recevoir un gaz sous pression et chargé d'une substance propre à se condenser sous l'effet du refroidissement occasionné par une détente ; un corps de tuyère monté à l'extrémité de cette enceinte pour détendre le gaz sortant de cette enceinte, en particulier par une buse d'éjection ; une électrode effilée dont la pointe est située à proximité du col de la tuyère ; et une source de haute tension ainsi que des moyens de connexion propres à raccorder électriquement cette électrode effilée à une première borne de ladite source de haute tension et une partie conductrice du corps de tuyère à une deuxième borne de cette source, pour produire une décharge par effet couronne dans le gaz entre ladite électrode et le col de la tuyère.The electric charge generator of the invention is of the type comprising, as in FR-A-2 419 647, an enclosure capable of receiving a gas under pressure and charged with a substance capable of condensing under the effect of the cooling caused by relaxation; a body of nozzle mounted at the end of this enclosure to relax the gas leaving this enclosure, in particular by an ejection nozzle; a tapered electrode whose tip is located near the neck of the nozzle; and a high voltage source as well as connection means suitable for electrically connecting this tapered electrode to a first terminal of said high voltage source and a conductive part of the nozzle body to a second terminal of this source, to produce a discharge by crown effect in the gas between said electrode and the neck of the nozzle.

Ce générateur de charges électriques est essentiellement caractérisé en ce que ladite source est le secondaire d'un transformateur délivrant une haute tension alternative, en ce que la surface de ladite tuyère est électriquement isolante du côté de l'intérieur de l'enceinte, et en ce que les moyens de connexion de ladite électrode effilée et de ladite partie conductrice du corps de tuyère comprennent un condensateur en série entre cette électrode et cette partie conductrice.This electric charge generator is essentially characterized in that said source is the secondary of a transformer delivering a high alternating voltage, in that the surface of said nozzle is electrically insulating on the side of the interior of the enclosure, and in that the means for connecting said tapered electrode and said conductive part of the nozzle body comprise a capacitor in series between this electrode and this conductive part.

Les ions produits par la décharge en couronne constituent des noyaux sur lesquels se forment les microparticules de la substance condensable. Les ions sont ainsi piégés par le courant de microparticules et ils sont ensuite libérés par un chargement de phase des microparticules pour former la charge de la zone d'espace. Grâce à la vitesse acquise par les microparticules, il est possible de charger une zone d'espace à une distance relativement importante de l'enceinte à l'intérieur de laquelle sont créés les ions transférés.The ions produced by the corona discharge constitute nuclei on which the microparticles of the condensable substance are formed. The ions are thus trapped by the current of microparticles and they are then released by a phase loading of the microparticles to form the charge of the space zone. Thanks to the speed acquired by the microparticles, it is possible to charge an area of space at a relatively large distance from the enclosure inside which the transferred ions are created.

Par ailleurs, la mobilité de microparticules non gazeuses, même de dimensions très faibles, est toujours très inférieure en pratique à celle des ions qui peuvent être engendrés par la décharge corona. Il en résulte que la probabilité d'interaction et de recombinaison des charges sous l'effet de la diffusion desdites microparticules est beaucoup plus faible que dans le cas des ions libres.Furthermore, the mobility of non-gaseous microparticles, even of very small dimensions, is always very much lower in practice than that of the ions which can be generated by the corona discharge. It follows that the probability of interaction and recombination of the charges under the effect of the diffusion of said microparticles is much lower than in the case of free ions.

On a cependant constaté que les dispositifs générateurs d'ions à effet couronne antérieurs avaient un rendement différent selon que le champ électrique appliqué pour engendrer la décharge était positif ou négatif.However, it has been found that the prior ion-generating devices with crown effect had a different efficiency depending on whether the electric field applied to generate the discharge was positive or negative.

Ainsi, les dispositifs de l'art antérieur qui mettent en oeuvre des décharges corona alimentées par des tensions alternatives ne permettent pas d'obtenir véritablement des flux de charges de signes opposés dont la neutralité globale soit respectée. Le déséquilibre entre les flux de charges positives et négatives ainsi créés ne permet pas, en l'absence de précautions particulières, d'obtenir la neutralisation de corps électrisés dans le cas d'une application à l'élimination de particules électrostatiques. Au contraire, ce déséquilibre perturbe les tentatives de neutralisation, voire même les rend dangereuses, dans la mesure où l'objet à décharger peut lui-même se charger sous l'effet du courant de déséquilibre.Thus, the devices of the prior art which use corona discharges supplied by alternating voltages do not make it possible to genuinely obtain charge flows of opposite signs whose overall neutrality is respected. The imbalance between the flows of positive and negative charges thus created does not allow, in the absence of special precautions, to obtain the neutralization of electrified bodies in the case of an application to the elimination of electrostatic particles. On the contrary, this imbalance disrupts attempts to neutralize, or even makes them dangerous, insofar as the object to be unloaded can itself charge under the effect of the current of imbalance.

On aurait pu penser éliminer simplement la composante continue du courant global de charge ainsi produit par filtrage, par exemple à l'aide d'un condensateur. L'expérience a montré qu'une telle mesure n'était pas efficace pour résoudre le problème posé. Un tel condensateur se trouve en effet shunté par le courant de charge qui circule entre les électrodes utilisées pour produire la décharge. Le générateur de charges électriques de l'invention permet d'empêcher qu'un tel courant ne vienne contre-carrer les mesures prises pour alimenter les décharges corona négatives et les décharges corona positives en appliquant aux électrodes des tensions différentes en valeur absolue.One could have thought of simply eliminating the direct component of the global charge current thus produced by filtering, for example using a capacitor. Experience has shown that such a measure is not effective in solving the problem posed. Such a capacitor is in fact shunted by the charge current which flows between the electrodes used to produce the discharge. The electric charge generator of the invention makes it possible to prevent such a current from coming against the measures taken to supply the negative corona discharges and the positive corona discharges by applying different voltages to the electrodes in absolute value.

Grâce au condensateur disposé en série entre l'électrode effilée et la partie conductrice du corps de tuyère, le niveau de charge du condensateur s'établit alors à une valeur telle que les tensions d'alimentation de la décharge positive et de la décharge négative sont différentes et, respectivement, produisent des flux d'ions positifs et négatifs avec des rendements égaux.Thanks to the capacitor arranged in series between the tapered electrode and the conductive part of the nozzle body, the charge level of the capacitor is then established at a value such that the supply voltages of the positive discharge and of the negative discharge are different and, respectively, produce positive and negative ion fluxes with equal yields.

Avantageusement, le corps de la tuyère peut être un bloc de matériau isolant dont la surface interne est convenablement conformée du point de vue aérodynamique, et dans lequel est noyé un conducteur, lequel est raccordé à la source d'alimentation alternative de l'ensemble électrode effilée tuyère, par exemple à travers la masse.Advantageously, the body of the nozzle can be a block of insulating material, the internal surface of which is suitably aerodynamically shaped, and in which a conductor is embedded, which is connected to the alternative power source of the electrode assembly. tapered nozzle, for example through the mass.

Le générateur de charges électriques ci-dessus permet ainsi d'obtenir des concentrations équilibrées de charges simultanément positives et négatives très élevées à des distances relativement considérables de l'enceinte où les ions prennent naissance sans que les recombinaisons de charges au cours du transfert deviennent excessives.The above electric charge generator thus makes it possible to obtain balanced concentrations of very high simultaneously positive and negative charges at relatively considerable distances from the enclosure where the ions arise without the recombination of charges during transfer becoming excessive. .

On a constaté qu'on obtenait notamment des flux globalement neutres de charges de signes opposés avec une grande efficacité en utilisant comme gaz comprimé de l'air chargé d'humidité, même faiblement. Il est, en outre remarquable que ce mode de réalisation ne s'accompagne pas de transfert notable d'ozone dans la direction de la zone d'espace à traiter.It has been found that, in particular, globally neutral flows of charges of opposite signs are obtained with great efficiency by using air compressed with humidity, even slightly. It is also remarkable that this embodiment is not accompanied by a significant transfer of ozone in the direction of the area of space to be treated.

Les dispositions selon l'invention sont notamment intéressantes lorsque la zone d'espace est relativement difficile d'accès, par exemple dans le cas où des matières pulvérulentes électrisées sont manipulées au cours d'un processus industriel ; ou lorsqu'elle contient une atmosphère inflammable ou explosible. Si les particules chargées sont éjectées par une buse en dehors de l'enceinte dans laquelle elles sont formées, on peut éviter en effet tout contact entre l'atmosphère extérieure et l'intérieur de l'enceinte en raison du caractère unidirectionnel du courant de microparticules et de sa vitesse relativement élevée dans la buse.The arrangements according to the invention are particularly advantageous when the space area is relatively difficult to access, for example in the case where electrified pulverulent materials are handled during an industrial process; or when it contains a flammable or explosive atmosphere. If the charged particles are ejected by a nozzle outside the enclosure in which they are formed, it is indeed possible to avoid any contact between the external atmosphere and the interior of the enclosure because of the unidirectional nature of the current of microparticles and its relatively high speed in the nozzle.

L'invention a également pour objet l'application du générateur qui vient d'être défini à l'élimination de l'électricité statique des corps électrisés.The invention also relates to the application of the generator which has just been defined to the elimination of static electricity from the electrified bodies.

Dans certains cas, il peut arriver que le corps à neutraliser conserve une charge résiduelle de faible valeur et en particulier de nature à porter le potentiel de cet objet à des valeurs sans danger. Si l'on désire éliminer cette charge résiduelle ou la fixer à une valeur différente de celle qui résulte de l'opération de neutralisation, conformément à un aspect supplémentaire de l'invention, on détecte le champ électrique aux alentours de ce corps et on asservit le circuit d'alimentation de la décharge couronne au champ détecté de façon à l'amener à une valeur recherchée, par exemple nulle.In some cases, the body may neutralize keeps a residual charge of low value and in particular likely to bring the potential of this object to safe values. If it is desired to eliminate this residual charge or to set it at a value different from that which results from the neutralization operation, in accordance with an additional aspect of the invention, the electric field is detected around this body and it is controlled the supply circuit of the discharge crowns the detected field so as to bring it to a desired value, for example zero.

La description qui suit est donnée à titre d'exemple, en référence aux dessins annexés, dans lesquels :

  • la figure 1 est une vue en coupe longitudinale d'un générateur ou injecteur de charges électriques de signes opposés dans une zone d'espace de type connu, alimenté par une source délivrant une haute tension alternative ;
  • la figure 2 illustre schématiquement le fonctionnement de l'injecteur de la figure 1 utilisé pour élever la concentration en charges électriques de signes différents d'une zone d'espace ;
  • la figure 3 représente une forme de réalisation préférée du montage électrique d'un injecteur du type de la figure 1 modifié conformément à l'invention ;
  • la figure 4 représente une première variante de réalisation du montage électrique d'un injecteur utilisé comme éliminateur d'électricité statique ;
  • la figure 5 représente une deuxième variante de réalisation du montage électrique ;
  • la figure 6 représente une troisième variante de réalisation ; et
  • la figure 7 représente une autre variante du montage électrique.
The following description is given by way of example, with reference to the accompanying drawings, in which:
  • FIG. 1 is a view in longitudinal section of a generator or injector of electric charges of opposite signs in a space of known type, supplied by a source delivering a high alternating voltage;
  • Figure 2 schematically illustrates the operation of the injector of Figure 1 used to raise the concentration of electrical charges of different signs of a space area;
  • FIG. 3 represents a preferred embodiment of the electrical assembly of an injector of the type of FIG. 1 modified in accordance with the invention;
  • FIG. 4 represents a first alternative embodiment of the electrical assembly of an injector used as an eliminator of static electricity;
  • FIG. 5 represents a second alternative embodiment of the electrical assembly;
  • Figure 6 shows a third alternative embodiment; and
  • FIG. 7 shows another variant of the electrical assembly.

Un mode de réalisation d'un injecteur de charges électriques (figure 1) comprend un corps tubulaire allongé isolant 10 fermé à une extrémité 12 et prolongé à son autre extrémité 14 par un corps de révolution 16 dont le profil interne définit une tuyère 18 comportant une partie rétrécie 20, suivie d'un col 22, puis d'un divergent 24, lorsqu'on s'éloigne de l'extrémité 14 du corps tubulaire 10. Le divergent débouche, par un orifice 26 ménagé dans la face antérieure 28 du corps de tuyère 16, dans un tube 30 coaxial à la tuyère 18, dont l'extrémité forme une buse d'éjection 32 vers l'extérieur en direction d'une zone d'espace.One embodiment of an electric charge injector (FIG. 1) comprises an elongated insulating tubular body 10 closed at one end 12 and extended at its other end 14 by a body of revolution 16 whose internal profile defines a nozzle 18 comprising a narrowed part 20, followed by a neck 22, then by a diverging portion 24, when one moves away from the end 14 of the tubular body 10. The divergent opening, through an orifice 26 formed in the anterior face 28 of the body of nozzle 16, in a tube 30 coaxial with the nozzle 18, the end of which forms an ejection nozzle 32 towards the outside towards a space zone.

A l'intérieur du corps 10 est fixée par une monture étoilée isolante 45, raccordée à la paroi interne du corps cylindrique 10, une aiguille 46 en un matériau conducteur centrée sur l'axe du tube 10 et comportant une pointe 48 au col 22 de la tuyère 18. L'extrémité postérieure 49 de l'aiguille 46 est reliée électriquement à un conducteur 50 qui traverse la paroi d'extrémité 12 du corps 10 par une traversée isolante 52. Dans la paroi latérale postérieure du corps 10 débouche une canalisation 55 d'amenée d'air comprimé dans le sens de la flèche 56.Inside the body 10 is fixed by an insulating star mount 45, connected to the internal wall of the cylindrical body 10, a needle 46 made of a conductive material centered on the axis of the tube 10 and comprising a point 48 at the neck 22 of the nozzle 18. The rear end 49 of the needle 46 is electrically connected to a conductor 50 which passes through the end wall 12 of the body 10 by an insulating bushing 52. In the rear side wall of the body 10 opens a pipe 55 compressed air supply in the direction of arrow 56.

Le corps 10 est constitué en un matériau isolant. Dans cet exemple, le corps de tuyère 16 est conducteur et relié électriquement à la masse par un conducteur 60, le conducteur 50 étant relié à une extrémité 67 d'un enroulement secondaire haute tension 62 d'un transformateur 64 alimenté à son primaire 66 par la tension alternative du secteur à 220 v. L'autre extrémité 68 de l'enroulement 62 est raccordée à Îa masse.The body 10 is made of an insulating material. In this example, the nozzle body 16 is conductive and electrically connected to ground by a conductor 60, the conductor 50 being connected to one end 67 of a high voltage secondary winding 62 of a transformer 64 supplied to its primary 66 by the AC mains voltage at 220 v. The other end 68 of the winding 62 is connected to the ground.

La canalisation 55 est raccordée à un compresseur non représenté alimenté en air humide pour injecter, dans le sens de la flèche 56, à l'intérieur du corps d'injecteur 10, un air comprimé humide qui pénètre dans le corps de tuyère 16 et commence à se détendre au niveau du rétrécissement 20 où il est accéléré en se refroidissant. A partir du col 22, il acquiert une vitesse supersonique sous l'effet de l'accélération qui lui est impartie par le divergent 24 de la tuyère puis pénètre dans le tube 30 pour être éjecté par la buse 32 hors de l'enceinte formée par l'intérieur du tube 10 de la tuyère 18 et du tube 30.Line 55 is connected to a compressor (not shown) supplied with moist air in order to inject, in the direction of the arrow 56, inside the injector body 10, moist compressed air which enters the nozzle body 16 and begins to relax at the level of the constriction 20 where it is accelerated by cooling. From the neck 22, it acquires a supersonic speed under the effect of the acceleration which is imparted to it by the diverging portion 24 of the nozzle and then enters the tube 30 to be ejected by the nozzle 32 out of the enclosure formed by inside the tube 10 of the nozzle 18 and of the tube 30.

L'enroulement haute tension 62 applique une tension alternative de plusieurs milliers de volts, par exemple 20 kV entre la pointe 48 de l'aiguille 46 et la tuyère 18, cette tension étant suffisante pour permettre à une décharge corona alternative de s'établir au col de cette tuyère. Cette décharge se produit dans le courant d'air en cours de détente dans l'espace étroit qui sépare la pointe 48 du col de la tuyère 22 où règne un champ électrique extrêmement élevé. Pendant les alternances positives, il se forme une charge d'espace composée d'ions gazeux positifs à la périphérie de la zone de décharge corona, tandis que pendant les alternances négatives se forment des ions gazeux négatifs créant une charge d'espace négative autour de cette zone de décharge.The high-voltage winding 62 applies an alternating voltage of several thousand volts, for example 20 kV between the point 48 of the needle 46 and the nozzle 18, this voltage being sufficient to allow an alternative corona discharge to be established at neck of this nozzle. This discharge occurs in the air current during expansion in the narrow space which separates the point 48 from the neck of the nozzle 22 where an extremely high electric field prevails. During the positive half-waves, a space charge is formed composed of positive gas ions at the periphery of the corona discharge zone, while during the negative half-waves are formed negative gas ions creating a negative space charge around this discharge area.

L'air comprimé admis dans la tubulure 55 est sursaturé en vapeur d'eau qui commence à se condenser, dès que l'air atteint le convergent 20 de la tuyère, sous forme de microgouttelettes, les ions gazeux formés au voisinage de la pointe 48 formant des noyaux de condensation pour ces gouttelettes. Sous l'effet du refroidissement qui accompagne la détente à travers la tuyère, ces microgouttelettes se cristallisent en microparticules de glace de très faible diamètre (environ 10 nm de diamètre), la température de l'air détendu dans le divergent pouvant s'abaisser jusqu'à -90° Celsius. Les fines particules d'aérosol chargées alternativement positivement et négativement sont entraînées par le courant gazeux à très grande vitesse à l'intérieur du tube 30 et projetées dans la zone d'espace en regard de la buse 32, comme il sera expliqué ci-après.The compressed air admitted into the tube 55 is supersaturated with water vapor which begins to condense, as soon as the air reaches the converging point of the nozzle, in the form of microdroplets, the gaseous ions formed in the vicinity of the point 48 forming condensation nuclei for these droplets. Under the effect of the cooling which accompanies the expansion through the nozzle, these microdroplets crystallize into microparticles of very small diameter ice (approximately 10 nm in diameter), the temperature of the air expanded in the divergent being able to lower up to 'at -90 ° Celsius. The fine particles of aerosol charged alternately positively and negatively are entrained by the gas stream at very high speed inside the tube 30 and projected into the area of space opposite the nozzle 32, as will be explained below. .

Un débit d'air convenable pour un tel dispositif propre à être utilisé comme un éliminateur de particules d'électricité statique peut être d'environ 20 m3 par heure, mesuré dans les conditions normales de température et de pression, et la pression correspondante dans l'enceinte d'environ 5 bars. La vitesse d'éjection des charges à l'intérieur du tube 30 est d'environ 300 m/s. L'air comprimé humide admis dans la tubulure 55 peut être obtenu à partir d'air ambiant pourvu que son degré hygrométrique soit supérieur à environ 10 %. Pour le cas où l'air ambiant est très sec, un humidificateur est prévu à l'entrée du compresseur. On a trouvé que le degré hygrométrique indiqué correspondait à une densité de microparticules de glace au niveau du col de la tuyère largement suffisante pour venir piéger la quasi- totalité des ions formés par la décharge.A suitable air flow for such a device suitable for being used as a static eliminator of particles can be about 20 m 3 per hour, measured under normal conditions of temperature and pressure, and the corresponding pressure in the enclosure of approximately 5 bars. The charge ejection speed inside the tube 30 is approximately 300 m / s. The moist compressed air admitted into the tubing 55 can be obtained from ambient air provided that its humidity is greater than about 10%. In case the ambient air is very dry, a humidifier is provided at the inlet of the compressor. It has been found that the hygrometric degree indicated corresponds to a density of microparticles of ice at the level of the neck of the nozzle which is largely sufficient to come to trap almost all of the ions formed by the discharge.

Les rendements en particules ionisées de la décharge corona positive et de la décharge corona négative ne sont pas en général les mêmes pour une valeur donnée de la tension d'alimentation au secondaire 62. En pratique, la quantité de charges de chaque signe produite et le courant résultant de l'entraînement de ces charges à travers le tube 30 dépendent d'un nombre de facteurs élevé parmi lesquels l'état de la pointe 48, la pression et le degré hygrométrique de l'air utilisé, la valeur de la tension appliquée.The yields of ionized particles of the positive corona discharge and of the negative corona discharge are generally not the same for a given value of the supply voltage at the secondary 62. In practice, the quantity of charges of each sign produced and the current resulting from the driving of these loads through the tube 30 depend on a high number of factors among which the state of the tip 48, the pressure and the hygrometric degree of the air used, the value of the applied voltage .

Les microparticules de glace entraînées à travers le tube 30 échappent à l'action du champ électrique régnant à l'intérieur de l'injecteur grâce à leur très faible mobilité et la grande vitesse de l'écoulement gazeux. Ces charges, après avoir quitté la buse 32 s'en éloignent pour n'être récupérées qu'à distance relativement élevée par un corps relié à la masse ou la terre après qu'elles sont libérées comme il sera expliqué ci-après. Le tube 30 est constitué en un matériau semi-conducteur possédant une très forte résistivité. Cette caractéristique permet d'éviter l'accumulation le long de ce tube de charges résiduelles déposées par le courant de particules au cours de son trajet vers l'orifice 32. Une telle accumulation pourrait en effet donner naissance à des décharges glissantes le long de la paroi interne du tube 30 avec une perte sensible du courant de particules parvenant à l'extérieur de la buse.The ice microparticles entrained through the tube 30 escape the action of the electric field prevailing inside the injector thanks to their very low mobility and the high speed of the gas flow. These charges, after leaving the nozzle 32 move away from them to be recovered only at relatively high distance by a body connected to ground or the earth after they are released as will be explained below. The tube 30 is made of a semiconductor material having a very high resistivity. This characteristic makes it possible to avoid the accumulation along this tube of residual charges deposited by the stream of particles during its path towards the orifice 32. Such an accumulation could indeed give rise to sliding discharges along the inner wall of the tube 30 with a substantial loss of the stream of particles reaching the outside of the nozzle.

La mobilité des microparticules est de plusieurs ordres de grandeur inférieure à celle des ions gazeux. Grâce à cette plus faible mobilité, la probabilité de recombinaison de charges de signes contraires, à proximité de la pointe émissive où la concentration en particules chargées est la plus importante, est beaucoup plus faible que dans le cas d'une décharge corona sans détente dans l'air.The mobility of microparticles is several orders of magnitude lower than that of gas ions. Thanks to this lower mobility, the probability of recombination of charges of contrary signs, near the emissive point where the concentration of charged particles is the greatest, is much lower than in the case of a corona discharge without relaxation in the air.

Un injecteur 80 (figure 2) est très schématiquement représenté avec sa tuyère 82 et une buse de sortie 84 d'où jaillit à grande vitesse un jet 86 d'air et de microcristaux de glace chargés qui tend à devenir de plus en plus turbulent au fur et à mesure qu'il s'éloigne de cette tuyère 86 vers la zone d'espace 90 située en aval. A quelques dizaines de centimètres en aval, les microparticules de glace commencent à s'évaporer dans une zone intermédiaire 88 en libérant les ions gazeux qu'elles avaient préalablement piégés. En pratique, on a constaté que l'on pouvait obtenir par ce procédé des concentrations élevées de charges positives et négatives à des distances de plusieurs mètres de la buse 84 avant que les ions ainsi libérés ne se recombinent.An injector 80 (FIG. 2) is very schematically represented with its nozzle 82 and an outlet nozzle 84 from which a jet 86 of air and charged microcrystals of ice gushes out at high speed which tends to become more and more turbulent at as it moves away from this nozzle 86 towards the space zone 90 located downstream. A few tens of centimeters downstream, the ice microparticles begin to evaporate in an intermediate zone 88, releasing the gaseous ions that they had previously trapped. In practice, it has been found that it is possible to obtain by this process high concentrations of positive and negative charges at distances of several meters from the nozzle 84 before the ions thus released recombine.

On a constaté toutefois qu'un éliminateur d'électricité statique fonctionnant selon le principe rappelé précédemment avec un tel injecteur ne procurait souvent qu'une décharge imparfaite des corps électrisés placés dans la zone 90 et parfois, dans certains cas, était capable de charger ces derniers avec une polarité opposée à leur polarité initiale. Ces phénomènes résultent d'un déséquilibre entre les concentrations en charges positives et en charges négatives injectées dans la zone d'espace dans laquelle se trouve plongé le corps à décharger. En effet, si ce déséquilibre existe en faveur des charges de même signe que celles du corps à neutraliser, il est possible que toutes les charges portées par le corps ne puissent être neutralisées avant que les phénomènes de recombinaison ne reprennent le dessus. Si, au contraire, le déséquilibre est en faveur des charges qui ont un signe opposé à celles du corps électrisé, celui-ci peut se décharger puis se charger en sens contraire.However, it has been found that a static eliminator operating according to the principle recalled previously with such an injector often only provides an imperfect discharge of the electrified bodies placed in the zone 90 and sometimes, in certain cases, was capable of charging these last with a polarity opposite to their initial polarity. These phenomena result from an imbalance between the concentrations of positive charges and negative charges injected into the area of space in which the body to be discharged is immersed. Indeed, if this imbalance exists in favor of charges of the same sign as those of the body to be neutralized, it is possible that all the charges carried by the body cannot be neutralized before the phenomena of recombination take over. If, on the contrary, the imbalance is in favor of the charges which have a sign opposite to those of the electrified body, the latter can discharge and then charge in the opposite direction.

Un tel déséquilibre entre les concentrations de charges transférées hors de l'injecteur résulte d'une inégalité des rendements de la production en ions par les décharges corona positives et négatives successives au cours des alternances de la tension d'alimentation des électrodes constituées par la pointe 48 et le corps de tuyère 16 (figure 1). Ce rendement est déterminé par de très nombreux facteurs sur lesquels il est difficile d'agir de façon directe afin de corriger les déséquilibres.Such an imbalance between the concentrations of charges transferred out of the injector results from an inequality of the yields of the production of ions by successive positive and negative corona discharges during the alternations of the supply voltage of the electrodes formed by the tip. 48 and the nozzle body 16 (FIG. 1). This return is determined by numerous factors which it is difficult to act on directly in order to correct imbalances.

On s'est rendu compte qu'il était possible d'éliminer ce courant de déséquilibre en utilisant un dispositif d'injecteur analogue à celui de la figure 1 avec quelques modifications représentées de façon très schématique à la figure 3.We realized that it was possible to eliminate this imbalance current by using an injector device similar to that of FIG. 1 with some modifications shown very schematically in FIG. 3.

Il comprend alors un tube d'injecteur 120 à l'extrémité duquel est monté un corps de tuyère supersonique 122. Aucune buse n'est prévue à la sortie de cette tuyère. Au col 124 de la tuyère est disposée la pointe 125 d'une électrode-aiguille 126 qui est reliée à une source de haute tension, constituée par le transformateur 64 de la figure 1, par l'intermédiaire d'un condensateur C 130. Contrairement à la réalisation de la figure 1, le corps de tuyère 122 est composé d'une matière isolante, par exemple une résine synthétique à l'intérieur de laquelle est noyé un anneau conducteur ou anneau de garde métallique 132 relié à la masse par un conducteur 134, enrobé d'un revêtement 137 de résine isolante semblable à celle qui constitue le corps de tuyère 122 sur une partie au moins de son trajet à la terre ou à la masse. L'aiguille 126 est reliée au condensateur C 130 par un conducteur 136, lui-même enrobé d'un isolant 138.It then comprises an injector tube 120 at the end of which is mounted a body of supersonic nozzle 122. No nozzle is provided at the outlet of this nozzle. At the neck 124 of the nozzle is disposed the tip 125 of a needle electrode 126 which is connected to a high voltage source, constituted by the transformer 64 of FIG. 1, by means of a capacitor C 130. Unlike in the embodiment of Figure 1, the nozzle body 122 is composed of an insulating material, for example a synthetic resin inside which is embedded a conductive ring or metal guard ring 132 connected to ground by a conductor 134, coated with a coating 137 of insulating resin similar to that which constitutes the nozzle body 122 over at least part of its path to earth or ground. The needle 126 is connected to the capacitor C 130 by a conductor 136, itself coated with an insulator 138.

En fonctionnement, on a constaté que le dispositif schématiquement illustré par la figure 3, alimenté en tension alternative sinusoïdale ou en créneaux rectangulaires avec une valeur de crête de 20 kV permettait d'obtenir un écoulement quasi simultané de charges de signes différents à la sortie de cette tuyère dont la charge globale était rigoureusement nulle. Dans l'application de ce dispositif à un éliminateur d'électricité statique, le flux de particules chargées émises à la sortie et dirigées vers une zone d'espace entourant un corps électrisé à décharger est globalement neutre. Un tel éliminateur permet d'obtenir la formation d'une très forte concentration de particules ionisées positives et négatives dans l'environnement du corps électrisé qui reste tout à fait équilibrée au point de vue électrique. Les essais effectués montrent que l'on obtient alors une décharge complète extrêmement rapide de corps électrisés portés à des potentiels de plusieurs dizaines de milliers de volts. Par exemple, un corps chargé à 30 kV et placé à 3 m d'un injecteur alimenté dans les conditions décrites ci-dessus à propos de la figure 1 est déchargé dans un temps de l'ordre d'une seconde.In operation, it has been found that the device schematically illustrated in FIG. 3, supplied with alternating sinusoidal voltage or with rectangular slots with a peak value of 20 kV made it possible to obtain an almost simultaneous flow of charges of different signs at the output of this nozzle whose overall load was strictly zero. In the application of this device to an eliminator of static electricity, the flow of charged particles emitted at the outlet and directed towards a zone of space surrounding an electrified body to be discharged is generally neutral. Such an eliminator makes it possible to obtain the formation of a very high concentration of positive and negative ionized particles in the environment of the electrified body which remains completely balanced from the electrical point of view. The tests carried out show that an extremely rapid complete discharge of electric bodies brought to potentials of several tens of thousands of volts is then obtained. For example, a body charged at 30 kV and placed 3 m from an injector supplied under the conditions described above with respect to FIG. 1 is discharged in a time of the order of one second.

D'autres essais ont confirmé ces résultats. Ainsi, on place un corps métallique qui est frappé par le jet à la sortie de l'injecteur de la figure 3 dans une zone correspondant à la zone 90 de la figure 2. Ce corps est relié à la masse par un conducteur dans lequel on monte en série un galvanomètre ultra sensible pour détecter le passage éventuel d'un courant. On constate qu'aucun courant décelable ne traverse ce galvanomètre, ce qui est bien l'indication que le bilan des charges captées par le corps conducteur est effectivement nul. En effet, si on renouvelle la même expérience avec un injecteur du type décrit à la figure 1, c'est-à-dire ne comportant ni un condensateur tel que C 130 pour l'alimentation de l'aiguille 46 ni une tuyère dont la surface en regard de la pointe 48 de l'aiguille 46 est isolante, on décèle en général un courant continu non négligeable dû au déséquilibre entre les flux de charges positives et négatives qui frappent le corps.Other tests have confirmed these results. Thus, a metallic body which is struck by the jet at the outlet of the injector of FIG. 3 is placed in an area corresponding to zone 90 of FIG. 2. This body is connected to ground by a conductor in which mounts an ultra sensitive galvanometer in series to detect the possible passage of a current. It can be seen that no detectable current flows through this galvanometer, which is an indication that the balance of charges picked up by the conductive body is effectively zero. Indeed, if the same experiment is repeated with an injector of the type described in FIG. 1, that is to say comprising neither a capacitor such as C 130 for supplying the needle 46 nor a nozzle whose facing surface of the tip 48 of the needle 46 is insulating, in general a non-negligible direct current is detected due to the imbalance between the flows of positive and negative charges which strike the body.

En fonctionnement, le dispositif à tuyère isolante de la figure 3 voit le condensateur C 130 se charger à un potentiel relativement faible, soit par exemple de quelques centaines de volts. Si le corps électrisé à décharger est placé à distance relativement proche de la buse d'éjection de l'injecteur, on constate qu'il maintient un niveau de potentiel au plus égal à celui de l'aiguille 126. Ce niveau de potentiel d'électrisation de l'ordre de 500 volts est tout à fait sans danger si on sait que les potentiels d'électrisation des corps que l'on cherche à décharger à l'aide de la présente invention peuvent couramment atteindre plusieurs dizaines de kilovolts. On constate que, lorsqu'on éloigne le corps de la sortie de l'injecteur, le niveau de ce potentiel continu sur le corps baisse très sensiblement.In operation, the insulating nozzle device of FIG. 3 sees the capacitor C 130 being charged at a relatively low potential, ie for example a few hundred volts. If the electrified body to be discharged is placed at a relatively close distance from the injector ejection nozzle, it can be seen that it maintains a level of potential at most equal to that of the needle 126. This level of potential of electrification of the order of 500 volts is completely safe if it is known that the potentials of electrification of the bodies that one seeks to discharge using the present invention can commonly reach several tens of kilovolts. It is noted that, when the body is moved away from the outlet of the injector, the level of this continuous potential on the body drops very appreciably.

Pour certaines applications, on souhaite cependant réduire le potentiel résiduel du corps placé à distance pour l'amener à un niveau électrique rigoureusement neutre. Un mode de réalisation de l'invention prévoit alors des moyens complémentaires de mesurer le potentiel du corps par rapport à une masse de référence et des moyens d'agir sur la valeur de la tension continue de la pointe 126 pour asservir le potentiel électrique du corps à celui de la masse de référence.For certain applications, however, it is desired to reduce the residual potential of the body placed at a distance to bring it to a strictly neutral electrical level. An embodiment of the invention then provides additional means for measuring the potential of the body with respect to a reference mass and means for acting on the value of the DC voltage of the tip 126 to control the electric potential of the body. to that of the reference mass.

On peut tenter d'expliquer la remarquable neutralité globale du flux de charges électriques transféré hors du dispositif éliminateur en constatant qu'aucun courant électrique continu ne peut circuler entre la pointe 125 de l'aiguille 126 et le corps de tuyère 122. Le champ électrique en chaque point de l'espace entre ces deux éléments, qui provoque la décharge corona alternative au col de la tuyère, présente des alternances positives et négatives dissymétriques. La différence d'amplitude entre ces alternances correspond à une composante de tension continue entre les armatures du condensateur C 130. Cette composante continue agit comme une polarisation tendant à compenser la dissymétrie entre les courants de charges produits par les alternances de signes opposés du système. En effet, on a indiqué précédemment que le rendement de production ionique des décharges corona de chaque signe dépend de la tension appliquée entre les électrodes entre lesquelles se produit cette décharge. Par le circuit selon l'invention, on réalise un déséquilibre entre la tension d'alimentation de la décharge positive et celle de la décharge négative pour égaliser automatiquement les rendements en particules des deux signes. A l'équilibre, toute composante continue qui tendrait à naître dans le courant de charges transmis par l'aiguille 126 sous l'influence d'un déséquilibre de ces rendements se traduit par une action de charge ou décharge du condensateur C 130 qui vient compenser la tension d'alimentation de décharge corona dans un sens qui tend à supprimer ce déséquilibre des rendements de production de charges.We can try to explain the remarkable overall neutrality of the flow of electric charges transferred out of the eliminator device by noting that no direct electric current can flow between the tip 125 of the needle 126 and the nozzle body 122. The electric field at each point of the space between these two elements, which causes the alternative corona discharge at the neck of the nozzle, presents asymmetric positive and negative alternations. The difference in amplitude between these half-waves corresponds to a DC voltage component between the plates of the capacitor C 130. This DC component acts as a polarization tending to compensate for the asymmetry between the charge currents produced by the alternations of opposite signs of the system. Indeed, it has been indicated previously that the ionic production yield of the corona discharges of each sign depends on the voltage applied between the electrodes between which this discharge occurs. By the circuit according to the invention, there is an imbalance between the supply voltage of the positive discharge and that of the negative discharge to automatically equalize the particle yields of the two signs. At equilibrium, any continuous component which would tend to arise in the charge current transmitted by the needle 126 under the influence of an imbalance of these yields results in a charge or discharge action of the capacitor C 130 which compensates the corona discharge supply voltage in a direction which tends to eliminate this imbalance in the yields of charge production.

Si, par exemple, un déséquilibre tend à se manifester dans le sens d'une augmentation du courant d'ions positifs, il en résulte une composante continue de courant dans le circuit de l'aiguille 126 qui tend à décharger le condensateur C 130, si celui-ci était chargé positivement. La tension aux bornes du condensateur C 130 tend alors à baisser et la tension d'alimentation des électrodes au cours des alternances positives tend également à s'abaisser en entraînant une réduction du rendement de la production d'ions positifs qui compense le déséquilibre.If, for example, an imbalance tends to manifest itself in the direction of an increase in the current of positive ions, this results in a continuous component of current in the circuit of the needle 126 which tends to discharge the capacitor C 130, if it was positively charged. The voltage across the capacitor C 130 then tends to drop and the supply voltage of the electrodes during positive half-waves also tends to drop, leading to a reduction in the yield of the production of positive ions which compensates for the imbalance.

On peut compléter cette explication en considérant ce qui se passerait si la surface de la tuyère, au lieu d'être isolante, était conductrice comme dans le cas de l'injecteur de la figure 1. La zone d'avalanche de la décharge corona joue alors le rôle d'une résistance entre l'aiguille 126 et la surface, conductrice dans cette hypothèse, de la tuyère 122. Tout déséquilibre entre les flux de charges positives et négatives se traduit par un courant qui, au lieu de charger ou décharger le condensateur C 130 jusqu'à ce qu'il s'annule, tend à circuler en court-circuitant les armatures du condensateur C 130 à travers la tuyère et la masse.We can complete this explanation by considering what would happen if the surface of the nozzle, instead of being insulating, was conductive as in the case of the injector of figure 1. The avalanche zone of the corona discharge plays then the role of a resistance between the needle 126 and the surface, conductive in this hypothesis, of the nozzle 122. Any imbalance between the flows of positive and negative charges results in a current which, instead of charging or discharging the capacitor C 130 until it cancels, tends to circulate by short-circuiting the armatures of capacitor C 130 through the nozzle and the ground.

Dans le mode de réalisation de la figure 3, le matériau isolant sur la surface interne 124 de la tuyère constitue une résistance de valeur infinie entre la pointe 125 et le conducteur de l'anneau de garde 132 (qui constitue la deuxième électrode proprement dite), tout en laissant agir le champ électrique. La distance entre cet anneau 132 et la surface de la tuyère résulte d'un compromis propre à éviter les claquages dudit revêtement isolant, tout en permettant d'obtenir un champ électrique suffisant et sans nécessiter des tensions prohibitivement élevées. La couche d'isolant 137 enfermant le conducteur 134 est destinée à empêcher l'établissement de trajets de courants parasites entre la pointe 125 et le conducteur de masse 134. De la même façon, l'isolant 128 est destiné à éviter la formation de courants parasites entre le conducteur 136 chargé à un potentiel continu comme il a été expliqué, et le reste du corps 120 de l'injecteur.In the embodiment of FIG. 3, the insulating material on the internal surface 124 of the nozzle constitutes a resistance of infinite value between the tip 125 and the conductor of the guard ring 132 (which constitutes the second electrode proper), while allowing the electric field to act. The distance between this ring 132 and the surface of the nozzle results from a compromise capable of avoiding the breakdowns of said insulating coating, while making it possible to obtain a sufficient electric field and without requiring prohibitively high voltages. The layer of insulator 137 enclosing the conductor 134 is intended to prevent the establishment of parasitic current paths between the tip 125 and the ground conductor 134. Likewise, the insulator 128 is intended to prevent the formation of currents interference between the conductor 136 charged to a continuous potential as has been explained, and the rest of the body 120 of the injector.

La capacité du condensateur C 130 est déterminée à une valeur relativement faible de façon à limiter son niveau de charge électrique lorsqu'il est, en fonctionnement, porté à un potentiel de polarisation d'environ quelques centaines de volts. En effet, lorsqu'on déclenche la décharge corona, tout déséquilibre existant entre la production d'ions par les alternances positive et négative crée un courant continu qui s'atténue progressivement, en chargeant le condensateur C 130, jusqu'à ce que les flux de charges négatives et positives soient égaux. Une partie de ce courant continu frappe le corps électrisé à décharger et peut lui communiquer une charge résiduelle éventuelle au maximum égale à celle qu'acquiert le condensateur C 130. Il est préférable d'adopter une valeur de capacité relativement faible pour ce dernier condensateur afin de limiter la charge résiduelle éventuelle du corps éiec- trisé. L'expérience montre qu'en pratique celle-ci peut être limitée à quelques 100 pF.The capacitance of the capacitor C 130 is determined at a relatively low value so as to limit its level of electric charge when it is, in operation, brought to a polarization potential of approximately a few hundred volts. Indeed, when the corona discharge is triggered, any imbalance existing between the production of ions by the positive and negative alternations creates a direct current which gradually diminishes, by charging the capacitor C 130, until the fluxes negative and positive charges are equal. Part of this direct current strikes the electrified body to be discharged and can communicate to it a possible residual charge at most equal to that which the capacitor C 130 acquires. It is preferable to adopt a relatively low capacitance value for this latter capacitor in order to to limit the possible residual charge of the electrified body. Experience shows that in practice this can be limited to some 100 pF.

Pour les applications dans lesquelles on souhaite aboutir à un état électrique du corps rigoureusement neutre, on élimine la charge résiduelle au moyen d'un dispositif électronique comprenant des moyens de mesurer le potentiel électrique du corps et des moyens d'agir sur le potentiel de la pointe 126 par rapport à la masse de référence. Le potentiel électrique du corps 140 (figure 4) est mesuré au moyen d'un appareil connu de mesure de champ électrique 141 relié à la masse de référence et le signal produit est utilisé pour modifier le potentiel par rapport à la masse de la pointe 126 afin de ramener, ou maintenir le corps 140 à l'état électriquement neutre. A cet effet, un amplificateur 142, relié à la sortie de l'appareil 141 délivre une tension continue qui est de signe opposé au potentiel résiduel du corps 140 et que l'on applique soit sur l'anneau (figure 4) soit à l'extrémité de l'enroulement secondaire du transformateur 64 (figure 6) ou encore à l'entrée d'un condensateur de liaison 143 dont la sortie est connectée à la pointe 126 (figure 5). En variante (figure 7), le signal délivré par l'amplificateur 142 commande une variation de l'amplitude de la tension alternative qui est appliquée à l'enroulement primaire du transformateur 64.For applications in which it is desired to achieve an electrical state of the body strictly neutral, the residual charge is eliminated by means of an electronic device comprising means for measuring the electrical potential of the body and means for acting on the potential of the tip 126 with respect to the reference mass. The electric potential of the body 140 (FIG. 4) is measured by means of a known device for measuring the electric field 141 connected to the reference mass and the signal produced is used to modify the potential relative to the mass of the tip 126 in order to bring back, or maintain the body 140 in the electrically neutral state. To this end, an amplifier 142, connected to the output of the device 141 delivers a direct voltage which is of opposite sign to the residual potential of the body 140 and which is applied either to the ring (FIG. 4) or to the 'end of the secondary winding of the transformer 64 (Figure 6) or at the input of a connecting capacitor 143 whose output is connected to the tip 126 (Figure 5). As a variant (FIG. 7), the signal delivered by the amplifier 142 controls a variation in the amplitude of the alternating voltage which is applied to the primary winding of the transformer 64.

Un dispositif tel que celui qui vient d'être décrit offre la possibilité de transporter un flux de charges électriques de signes différents sur des distances relativement grandes (plusieurs mètres) ce qui, comme on l'a expliqué précédemment, peut être intéressant dans certaines applications aux éliminateurs d'électricité statique, notamment pour des corps sous forme diffuse ou pulvérulente. En outre, en raison à la fois de cette grande distance et surtout du fait que l'intérieur de l'enceinte définie par le corps de l'injecteur se trouve pratiquement isolé de la zone d'espace considérée par le jet gazeux qui s'en échappe, aucun risque de contact entre une atmosphère explosive dans cette zone d'espace et la décharge couronne à l'intérieur de cette enceinte n'est à craindre. On peut d'ailleurs prévoir, conformément à une caractéristique supplémentaire de l'invention, d'établir un interrupteur 110 (figure 1) sur le circuit d'alimentation électrique du dispositif de décharge couronne qui fonctionne en réponse au signal de sortie 113 d'un pressostat 112 placé sur la conduite d'alimentation 55 de l'injecteur en air comprimé. De cette façon, les électrodes propres à produire la décharge corona ne peuvent être mises sous tension que lorsque l'air comprimé est admis dans l'injecteur et s'en échappe à grande vitesse par la buse 32. En outre, aucun arc électrique ne peut s'établir entre la pointe métallique telle que 125 et la terre, en raison de la tuyère isolante.A device such as that which has just been described offers the possibility of transporting a flow of electric charges of different signs over relatively large distances (several meters) which, as explained above, may be advantageous in certain applications. static eliminators, especially for bodies in diffuse or powder form. In addition, due both to this great distance and above all to the fact that the interior of the enclosure defined by the injector body is practically isolated from the area of space considered by the gas jet which is in escape, no risk of contact between an explosive atmosphere in this area of space and the crown discharge inside this enclosure is to be feared. One can also provide, in accordance with an additional characteristic of the invention, to establish a switch 110 (FIG. 1) on the electrical supply circuit of the crown discharge device which operates in response to the output signal 113 of a pressure switch 112 placed on the supply line 55 of the injector with compressed air. In this way, the electrodes capable of producing the corona discharge can only be energized when the compressed air is admitted into the injector and escapes at high speed through the nozzle 32. In addition, no electric arc can be established between the metal tip such as 125 and the ground, due to the insulating nozzle.

On a constaté, en outre, qu'avec des injecteurs du type décrit précédemment, on n'obtenait, de façon surprenante, pratiquement aucun dégagement d'ozone dans l'atmosphère extérieure à l'éliminateur, ce qui présente des avantages dans certaines applications.It has also been found that, with injectors of the type described above, there was, surprisingly, practically no release of ozone in the atmosphere outside the eliminator, which has advantages in certain applications. .

Enfin, et de façon essentielle, le dispositif dont le principe est représenté schématiquement à la figure 3 permet d'obtenir une élimination extrêmement rapide des décharges électrostatiques d'un corps à neutraliser pour les ramener à un niveau de potentiel ne présentant pas de danger.Finally, and essentially, the device, the principle of which is shown diagrammatically in FIG. 3, makes it possible to obtain extremely rapid elimination of the electrostatic discharges from a body to be neutralized in order to bring them back to a level of potential presenting no danger.

Claims (14)

1. A generator for generating electric charges of different sign in a zone of space, the generator being of the type comprising :
an enclosure (10) suitable for receiving a gas under pressure and charged with a substance suitable for condensing under the effect of the cooling caused by expansion ;
a nozzle body (122) mounted at the end of said enclosure for expanding the gas leaving said enclosure, in particular via an ejection nozzle (32) ;
a tapering electrode (126) whose point (125) is situated in the proximity of the nozzle throat (124) ; and
a high tension source (64) together with connection means (134, 136) suitable for electrically connecting said tapering electrode to a first terminal of said high tension source and a conductive portion of the nozzle body (122) to a second terminal of said source, in order to produce a corona effect discharge in the gas between said electrode (126) and the throat (124) of the nozzle ;
characterized in that said source is the secondary winding (62) of a transformer (64) delivering high tension AC, in that the surface of said nozzle is electrically insulating adjacent the inside of the enclosure (10) and in that the connection means (136, 134) for said tapering electrode and for the conductive portion (132) of the nozzle body include a capacitor (C130) in series between said electrode and said conductive portion.
2. A generator according to claim 1, characterized in that the nozzle body (122) is made of an insulating material in which a conductor (132) constituting said conductive portion is disposed and connected to said second terminal.
3. A generator according to claim 2, characterized in that the conductor is a metal ring (132) coaxial with said nozzle and coated in insulating material.
4. A generator according to any one of claims 1 to 3, characterized in that the connection means for the conductive portion of the nozzle body (122) include a conductor (134) which is insulated over at least a portion of its length from the nozzle.
5. A generator according to any one of claims 1 to 4, characterized in that said capacitor (C130) is interposed in the circuit connecting the tapering electrode (126) to the AC tension source (64).
6: A generator according to any one of claims 1 to 5, characterized in that the connection between the tapering electrode (126) and the AC tension source is surrounded with insulating protection (138) over at least a portion of its length.
7. A generator according to any one of claims 1 to 6, characterized in that it includes pressure sensitive means (112) responsive to the pressure of the gas admitted into the enclosure, and means (110) suitable for preventing the supply of electricity to the discharge so long as said pressure sensitive means has not detected the gas pressure exceeding a predetermined threshold.
8. A generator according to any one of claims 1 to 7, wherein the connection means (134, 136) for the tapering electrode and the conductive portion of the nozzle body include means for detecting unbalance between the positive charge current and the negative charge current produced at the outlet from said enclosure, and means suitable for modifying the respective amplitudes of the positive and negative alternations of the AC tension in order to maintain a chosen relationship between said currents of positive charges and negative charges ejected towards the zone of space, characterized in the it includes means (141) for measuring the potential of the zone of space, means (142) for generating a DC voltage of opposing sign as a function of the potential measured by the means (141) and connected to modify the potential of the tapering electrode (126) as a function of said DC voltage in order to bring said zone of space to a neutral condition.
9. A generator according to claim 8, characterized in that the means (142) of generating said DC voltage are connected to the tapering electrode (126) via a capacitor (143).
10. A generator according to claim 8, characterized in that the means (142) for generating said DC voltage are connected to the conductive portion (132) of the nozzle.
11. A generator according to claim 8, characterized in that the means for generating said DC voltage are connected directly to the primary or the secondary winding of the transformer of said AC tension source (64).
12. A method of eliminating electric charge from a charged body, characterized in that the concentration of positive and negative electric charges in the space surrounding said body is increased by injecting a current of electric charges of opposite sign therein, by means of a generator according to any one of claims 1 to 11.
13. A method according to claim 12, characterized in that the electric field extending in the proximity of the body to be discharged is detected and in that the AC supply to said corona discharge is controlled as a function of the detected field in such a manner as to maintain said field at a predetermined value, e. g. nil.
EP81401536A 1980-10-14 1981-10-02 Method and devices to transfer electrical charges of opposed signs into a space-field, and its application to static eliminators Expired EP0051006B1 (en)

Applications Claiming Priority (2)

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FR8021977A FR2492212A1 (en) 1980-10-14 1980-10-14 METHOD AND DEVICES FOR TRANSFERRING ELECTRIC LOADS OF DIFFERENT SIGNS IN A SPACE AREA AND APPLICATION TO STATIC ELECTRICITY ELIMINATORS
FR8021977 1980-10-14

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EP0051006A2 EP0051006A2 (en) 1982-05-05
EP0051006A3 EP0051006A3 (en) 1983-06-08
EP0051006B1 true EP0051006B1 (en) 1986-10-01

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Families Citing this family (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4544382A (en) * 1980-05-19 1985-10-01 Office National D'etudes Et De Recherches Aerospatiales (Onera) Apparatus for separating particles in suspension in a gas
FR2583579B1 (en) * 1985-06-14 1987-08-07 Thomson Csf PROCESS FOR OBTAINING A PIEZOELECTRIC MATERIAL AND IMPLEMENTING DEVICE
JPH02119396U (en) * 1989-03-10 1990-09-26
US5121286A (en) * 1989-05-04 1992-06-09 Collins Nelson H Air ionizing cell
FR2690302A1 (en) * 1992-04-17 1993-10-22 Kodak Pathe Cleaning device for strip of unexposed photosensitive product.
US5409418A (en) * 1992-09-28 1995-04-25 Hughes Aircraft Company Electrostatic discharge control during jet spray
US5388769A (en) * 1993-09-20 1995-02-14 Illinois Tool Works Inc. Self-cleaning ionizing air gun
JP3910501B2 (en) * 2002-07-17 2007-04-25 浜松ホトニクス株式会社 Aerosol particle charger
JP4059153B2 (en) * 2003-06-23 2008-03-12 ソニー株式会社 Manufacturing method of display device
JP4114573B2 (en) 2003-08-13 2008-07-09 株式会社村田製作所 Ion generating component, ion generating unit and ion generating apparatus
DE10348217A1 (en) * 2003-10-16 2005-05-25 Brandenburgische Technische Universität Cottbus Device and method for Aerosolauf- or aerosol transfer into a defined state of charge of a bipolar diffusion charging by means of an electrical discharge in the aerosol space
JP4540043B2 (en) * 2004-04-05 2010-09-08 一雄 岡野 Corona discharge ionizer
US8063336B2 (en) * 2004-04-08 2011-11-22 Ion Systems, Inc. Multi-frequency static neutralization
US7057130B2 (en) * 2004-04-08 2006-06-06 Ion Systems, Inc. Ion generation method and apparatus
FR2870082B1 (en) * 2004-05-07 2006-07-07 Valitec Soc Par Actions Simpli STATIC ELECTRICITY ELIMINATOR, IN PARTICULAR FOR THE TREATMENT OF POLYMERS
US7212393B2 (en) * 2004-09-30 2007-05-01 Ion Systems, Inc. Air ionization module and method
JP4345060B2 (en) * 2004-11-30 2009-10-14 Ｓｍｃ株式会社 Ionizer
EP1833131B1 (en) * 2004-12-28 2018-10-10 Murata Manufacturing Co., Ltd. Ion generating unit and ion generating apparatus
DE102005013987B3 (en) * 2005-03-26 2006-07-20 Topas Gmbh Technologie-Orientierte Partikel-, Analysen- Und Sensortechnik Apparatus for neutralizing electrically charged aerosol particles flowing in tube, comprising ante-chamber(s) supplied with ionized gas over gas-permeable region(s) of tube side(s)
US8885317B2 (en) 2011-02-08 2014-11-11 Illinois Tool Works Inc. Micropulse bipolar corona ionizer and method
US8773837B2 (en) 2007-03-17 2014-07-08 Illinois Tool Works Inc. Multi pulse linear ionizer
DE102007042436B3 (en) * 2007-09-06 2009-03-19 Brandenburgische Technische Universität Cottbus Method and device for charging, reloading or discharging of aerosol particles by ions, in particular into a diffusion-based bipolar equilibrium state
JP4575948B2 (en) * 2007-12-18 2010-11-04 春日電機株式会社 Tube static eliminator
DK2238678T3 (en) 2008-01-22 2016-02-01 Accio Energy Inc Electro-hydrodynamic wind energy system
US8502507B1 (en) 2012-03-29 2013-08-06 Accio Energy, Inc. Electro-hydrodynamic system
US8878150B2 (en) 2008-01-22 2014-11-04 Accio Energy, Inc. Electro-hydrodynamic wind energy system
US9380689B2 (en) 2008-06-18 2016-06-28 Illinois Tool Works Inc. Silicon based charge neutralization systems
US20090316325A1 (en) * 2008-06-18 2009-12-24 Mks Instruments Silicon emitters for ionizers with high frequency waveforms
US8410784B1 (en) 2009-11-12 2013-04-02 The Boeing Company Method and device for measuring static charge
FR2955628B1 (en) * 2010-01-27 2013-10-04 Centre Nat Rech Scient METHOD AND DEVICE FOR MODULATING THE MASS FLOW OF A GAS FLOW
EP2630724A4 (en) 2010-10-18 2018-01-03 Accio Energy, Inc. System and method for controlling electric fields in electro-hydrodynamic applications
US9918374B2 (en) 2012-02-06 2018-03-13 Illinois Tool Works Inc. Control system of a balanced micro-pulsed ionizer blower
USD743017S1 (en) 2012-02-06 2015-11-10 Illinois Tool Works Inc. Linear ionizing bar
US9125284B2 (en) 2012-02-06 2015-09-01 Illinois Tool Works Inc. Automatically balanced micro-pulsed ionizing blower
JP5894021B2 (en) * 2012-06-26 2016-03-23 旭サナック株式会社 Charge amount measurement method for spray droplets, charge amount measurement device, and charge amount control device for spray droplets using them
CN106769739B (en) * 2017-01-19 2024-01-23 兰州大学 System for determining percentage of haze charged particles
JP6960582B2 (en) * 2017-10-19 2021-11-05 Smc株式会社 Ionizer
CN113163564B (en) * 2021-04-30 2024-06-04 中国科学院电工研究所 Electron beam processing device with static electricity eliminating function

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2419647A1 (en) * 1978-03-10 1979-10-05 Onera (Off Nat Aerospatiale) DEVICE FOR PRODUCING A GAS JET CARRIING ELECTRIC CHARGES
DE3121054A1 (en) * 1980-05-29 1982-02-25 Office National d'Etudes et de Recherches Aérospatiales, O.N.E.R.A., 92320 Châtillon-sous-Bagneux, Hauts-de-Seine "METHOD AND DEVICE FOR ELECTROSTATIC DUST SEPARATION

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3083318A (en) * 1959-04-27 1963-03-26 Frank E Hanscom Brushes with means for neutralizing static charges
US3317790A (en) * 1960-08-29 1967-05-02 Univ Minnesota Sonic jet ionizer
GB1071337A (en) * 1964-05-12 1967-06-07 Decca Ltd Improvements in or relating to the manufacture of gramophone records
FR1450650A (en) * 1965-07-01 1966-06-24 Statitrol Corp Ion generator
US3795839A (en) * 1967-09-01 1974-03-05 Graco Inc Method for preventing arcing in an electrostatic coating system
DE1960519A1 (en) * 1968-12-03 1970-08-27 Secretary Technology Brit Device for discharging bodies that are undesirably charged with static electricity
US3821603A (en) * 1971-03-31 1974-06-28 Cierva J De Electrostatic discharging system
FR2191819A5 (en) * 1972-07-04 1974-02-01 Topley Charles
GB1429821A (en) * 1973-02-02 1976-03-31 Ici Ltd Electrostatic charge controller
SU439078A1 (en) * 1973-03-19 1974-08-05 В. В. Ушаков , Г. М. Франчук AEROSOL ELECTRO-GAS DYNAMIC NEUTRALIZER
SU446956A1 (en) * 1973-04-12 1974-10-15 Neutralizer
SU480202A1 (en) * 1973-06-11 1975-08-05 Московский Полиграфический Институт Charging device
US4064548A (en) * 1976-01-27 1977-12-20 Burlington Industries, Inc. Means for improving ionization efficiency of high-voltage grid systems
DE2646798C2 (en) * 1976-10-16 1982-12-16 Haug & Co KG, 7022 Leinfelden-Echterdingen Device for the electrical charging of liquid or solid particles in a gas, especially air flow and application of the charged particles to surfaces

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2419647A1 (en) * 1978-03-10 1979-10-05 Onera (Off Nat Aerospatiale) DEVICE FOR PRODUCING A GAS JET CARRIING ELECTRIC CHARGES
DE3121054A1 (en) * 1980-05-29 1982-02-25 Office National d'Etudes et de Recherches Aérospatiales, O.N.E.R.A., 92320 Châtillon-sous-Bagneux, Hauts-de-Seine "METHOD AND DEVICE FOR ELECTROSTATIC DUST SEPARATION

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JPH0317199B2 (en) 1991-03-07
EP0051006A3 (en) 1983-06-08
EP0051006A2 (en) 1982-05-05
FR2492212A1 (en) 1982-04-16
DE3175417D1 (en) 1986-11-06
US4417293A (en) 1983-11-22
JPS57154800A (en) 1982-09-24
CA1172307A (en) 1984-08-07
SU1258342A3 (en) 1986-09-15
FR2492212B1 (en) 1983-10-21

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