FR2839262A1 - PLASMA STERILIZER DEVICE FOR THE TREATMENT OF GASEOUS MEDIA CONTAINING CONTAMINANT PARTICLES OF MICROORGANISM, BACTERIA OR VIRUS TYPE - Google Patents

Abstract

The present invention relates to a device forming a plasma sterilizer for the treatment of gaseous medium containing contaminating particles. The device is characterized in that it comprises a central rod (51) extending into the processing chamber (34) and a coil (52) mounted coaxially on the rod (51). The invention finds application in particular in the food industry.

Description

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 The present invention relates to a device forming a plasma sterilizer intended for the treatment of gaseous medium containing contaminating particles of microorganism, bacteria or virus type.

 It also relates to a refrigerated appliance with at least one food preservation compartment and with which the device forming the plasma sterilizer is associated.

 Figures 1 and 2 show a refrigerated appliance with food storage compartment as it currently exists.

 In FIG. 1, the door 1 of the refrigerated appliance is closed so that the storage compartment for a volume Vo is at an internal temperature TO of approximately OC and at an internal pressure PO of a value lower than the outdoor atmospheric pressure P1 due to cooling in the compartment.

 The surrounding atmosphere in which the refrigerated appliance is located is generally humid because the appliance is often located in a kitchen and is extremely loaded with contaminating particles, for example microorganisms such as bacteria, yeasts, molds , listeria, salmonella, staphilococci, spores and various germs that can cause food poisoning as well as volatile organic compounds.

 This charged atmosphere can also include various viscous constituents resulting from cooking fumes.

 When the door 1 of the refrigerated appliance is open, as shown in FIG. 2, the surrounding atmosphere, the pressure P1 of which is higher than the internal pressure Po of the storage compartment of the appliance before the door is opened, engulfs itself in this compartment with all the contaminating particles and volatile organic compounds which it may contain, risking thereby contaminating the food products contained in the refrigerated appliance.

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 In addition, the surrounding atmosphere generally having a temperature Tl close to 20 C causes an increase in temperature in the refrigerated appliance and therefore in the foodstuffs which it contains, thereby promoting the microbial development of the bacterial elements projected into the compartment. conservation.

 Under these conditions, the internal temperature TO goes from around 0 C to a significantly higher average temperature T2 and which can reach around 10 to 12 C depending on the type of refrigerated appliance. The humidity of the kitchen also enters the storage compartment to cause a significant worsening of the conditions of food storage by promoting microbial development.

 Figure 3 is a curve showing an example of change in the internal temperature of the storage compartment over a period of repeated opening and closing of the door of this compartment. Thus, for a volume VO of the compartment of approximately 100 liters, an internal temperature TO of approximately 0 C, an external temperature Tl of 20 C at normal atmospheric pressure and frequent repeated openings of door 1 of the compartment over a period one hour, the curve in Figure 3 shows that at the end of the one hour period, the internal temperature of the storage compartment is at a value close to 12 C.

 This curve shows that in fact the internal temperature To of 12 C is already reached practically after approximately 40 minutes of repeated opening of the door of the refrigerated appliance and remains at this temperature value for approximately 20 minutes. In normal operation of the refrigerated appliance, door closed, the internal temperature To will return to its food preservation value of approximately 0 C practically after a period of one hour. The curve in Figure 3 thus shows a significant break in the cold chain in the storage compartment of the device

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 refrigerated during frequent repeated door openings, promoting significant microbial pollution of the food it contains.

 This problem of contamination of food products contained in a refrigerated appliance is aggravated in the case of refrigerated appliances of the type with internal ventilation which causes an even greater dispersion of the contaminating particles on the food stored in this appliance.

 The object of the present invention is to solve the above-mentioned problems of known refrigerated appliances by proposing a plasma sterilizer device allowing efficient purification and sterilization of the internal atmosphere of the refrigerated appliance and also by proposing a refrigerated appliance arranged so as to avoid a vacuum in the refrigerated appliance when opening its door and thereby prevent any possible contamination of the food products stored in this appliance.

 To this end, the plasma sterilizer device allowing the treatment of gaseous medium containing contaminating particles, comprising a casing made of an electrically insulating material delimited at its ends by two axially spaced first and second parallel perforated parallel walls made of an electrically insulating material allowing respectively the inlet and outlet of the gaseous medium and in which at least one treatment chamber is produced, is characterized in that it comprises a central rod made of an electrically conductive material extending longitudinally in the treatment chamber from the perforated wall for entering the gaseous medium by being connected to an alternating high-voltage power supply and having its conical free end to generate a flow of electrons ionizing the gaseous medium, and a coil mounted coaxially on the rod approximately all along of it, connected to an ali low mentation

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 voltage to create an axial magnetic field increasing the ionization of the gaseous medium by the flow of electrons.

 The device advantageously comprises four radial partitions perforated in an electrically conductive material two to two diametrically opposite in the treatment chamber by extending longitudinally so that their longitudinal free edges surround the rod parallel and close to the latter, the radial partitions being connected to a high voltage alternating power supply in phase opposition to that of the rod supply to create in the spaces between partitions a magnetic resonance generating a circular and pulsed wave increasing the destruction of contaminating particles.

 The device further comprises four other radial perforated partitions of smaller dimensions made of an electrically conductive material extending longitudinally in the chamber being two to two diametrically opposed, a partition of smaller dimension being located between two successive partitions of larger dimensions , and having their longitudinal free edges relatively distant from the central rod by surrounding the latter, the partitions of smaller dimensions being connected to the same power supply as that of the partitions of large dimensions to thereby increase the magnetic resonance in the spaces between radial partitions.

 The downstream transverse edge of each larger partition is approximately at the same level as the conical end of the central rod and the downstream transverse edge of each smaller partition is located at a longitudinal distance between one third and the half the length of a large partition.

 Preferably, the partitions of small and large dimensions have teeth along their longitudinal edges and their downstream transverse edges.

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 The device further comprises a third intermediate transverse perforated wall defining a second downstream processing chamber in which there are two concentric longitudinal cylinders made of an electrically conductive material respectively an upstream cylinder integral with the intermediate wall and comprising at least three circumferential series of bores at from its free downstream end and a downstream cylinder of smaller diameter secured to the downstream end wall, partially penetrating into the cylinder of larger diameter and comprising at least three circumferential series of perforations from its upstream free end located in the cylinder larger diameter, the latter being connected to the high voltage power supply of the central rod while the smaller diameter cylinder is connected to the high voltage power supply of the radial partitions to thereby create a plasma participating in the destruction of contaminating particles in the gaseous medium circulating in the downstream chamber.

 Preferably, the two small and large diameter cylinders have at their edges of circular ends teeth extending coaxially to the longitudinal axis passing through the rod.

 The device also comprises a third cylinder of an electrically conductive material concentrically surrounding the other two concentric cylinders and comprising several circumferential series of radially internal teeth preferably four in number, the third cylinder being connected to the high voltage supply of the radial partitions.

 Advantageously, the envelope is cylindrical and the inlet wall of the gaseous medium is circular and fixed transversely in the envelope, the central rod is integral with a first perforated metal disc connected to the high voltage supply and sandwiched Between

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 the entry wall and a fourth transverse perforated wall of an electrically insulating material fixed in the envelope being traversed by the rod and the coil and the radial partitions are integral with the interior of a metal cylinder connected to its upstream end to a second perforated metal disc connected to the high-voltage supply of opposite phase and fixed between the fourth insulating wall and an insulating sleeve integral with the casing, the central rod and the coil freely passing through a central bore of the second metal disc in s 'extending to the vicinity the downstream end of the support cylinder for the radial partitions.

 The third perforated intermediate wall is fixed between the first insulating sleeve and a second insulating sleeve fixed in the envelope, the third wall comprising a circular central part made of insulating material and two perforated metal discs fixed respectively to the two opposite lateral faces of the part central, the upstream metal cylinder of the second chamber being integral with the downstream metal disc of the third wall transversely to this disc.

 The downstream cylinder and the third cylinder are integral with a fifth perforated metal disc fixed between the second insulating sleeve and the second circular wall for the outlet of the gaseous medium fixed in the envelope, the fifth disc being connected to the high voltage supply of opposite phase.

 The coil is connected to its low voltage power supply by its two wires electrically isolated through the central part of the first perforated disc and the first input wall.

 Preferably, each high voltage supply is between approximately 2,000 and approximately 20,000 volts for a frequency between approximately 5 and approximately 1000 Hz, preferably 50 Hz, and in that the voltage

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 The coil supply is approximately 220 Volts for a frequency of approximately 50 Hz.

 The refrigerated appliance comprising at least one food preservation compartment is characterized in that it is associated with a plasma sterilizer device, as defined above, placed on a ventilation circuit comprising a suction duct in the compartment of the gaseous medium to be treated present in this compartment and a reintroduction conduit into the compartment of the gaseous medium treated by the sterilizing device.

 The apparatus comprises in at least one of the side and rear walls of the storage compartment at least one through passage for balancing the internal pressure of the compartment with atmospheric pressure and comprising a first lower channel oriented obliquely downwards opening out to the exterior extended by a second vertical upper channel opening into the conservation compartment, thus also configuring the pressure balancing passage in thermal barrier.

 Advantageously, the pressure balancing passage communicates in the preservation compartment through a filter made of an active porous material causing the adsorption of atmospheric air which penetrates into the porosities of the material and then the absorption of this air. , during which a chemical reaction takes place between volatile organic compounds in atmospheric air and the material itself which transforms volatile organic compounds into non-toxic gas, in particular CO2 or SO2.

 Preferably, the suction pipe opens into the lower part of the storage compartment and the reintroduction pipe of the treated gaseous medium opens into the upper part of this compartment and is also connected to at least two separate pipes located in the vicinity of the storage part. framing of

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 the access opening to the compartment so as to propel, through a multitude of micro-orifices made along the two pipes, jets of pressurized air situated approximately in the same vertical plane parallel to the opening to form a sterile air barrier preventing depression as soon as the access door to the storage compartment is opened.

 The two pipes are arranged vertically opposite one another or horizontally opposite one another or one of the pipes is horizontal and the other is vertical.

 The apparatus further comprises a fan mounted in the ventilation circuit upstream of the sterilizing device and a sensor for detecting the opening of the door is connected to an electronic circuit for controlling the fan at high speed and at high efficiency of the device. sterilizer as soon as the sensor detects the opening of the door.

 The invention will be better understood and other objects, advantages and characteristics thereof will appear more clearly on reading the description which follows and which is given with reference to the appended drawings which represent nonlimiting examples of embodiment of the invention and in which: Figure 1 shows in perspective a closed door refrigerated appliance of the prior art; Figure 2 shows the refrigerated appliance with open door of Figure 1; FIG. 3 represents an example of a curve illustrating the evolution of the internal temperature of the refrigerated appliance of FIGS. 1 and 2, in particular over a determined period of repeated opening and closing of the door of this appliance; - Figure 4 is a perspective view of a refrigerated appliance according to the invention with two food storage compartments;

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 - Figure 5 is an enlarged partial view in section along the line V-V of Figure 4; - Figure 6 is a cross-sectional view of a storage compartment of the refrigerated appliance provided with a circuit of the invention allowing the recirculation of the internal atmosphere contained in this compartment; - Figure 7 is a perspective view of the compartment of Figure 6, the door is open; - Figure 8 shows an example of a curve illustrating the evolution of the internal temperature of the refrigerated appliance of Figures 4 to 7, in particular over a determined period of repeated opening and closing of the door of each compartment for storing this apparatus; - Figure 9 shows an electronic circuit for controlling the various components of the refrigerated appliance of the invention; - Figure 10 is a perspective view with partial cutaway of the plasma sterilizer device of the invention; - Figure 11 is a reduced view in longitudinal section of the plasma sterilizer device of Figure 10; - Figure 12 is a sectional view along line XII-XII of Figure 11.

 The invention will be described in the application to a refrigerated device for storing food products which it is sought to protect against any type of contaminating element, but it is understood that it can be applied to the treatment of any gaseous medium present in a closed enclosure other than a storage compartment of a refrigerated appliance.

 Referring firstly to FIGS. 4 to 7, the refrigerated appliance to which the invention applies is of the type comprising two separate and superimposed compartments 2, in which food products are stored,

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 each compartment 2 being normally closed by a door 1. Of course, the invention also applies to refrigerated appliances having a single compartment or more than two storage compartments.

 According to the invention, at least one of the lateral 3 and rear 4 walls associated with each storage compartment 2 comprises at least one passage 5 passing through the wall 3 or 4 so as to allow balancing of the internal pressure PO of the corresponding compartment 2 with external atmospheric pressure to prevent the call of atmospheric air by vacuum in compartment 2 as soon as door 1 is opened.

 For this, as can be seen more clearly from FIG. 5, the passage 5 comprises a first lower channel 6 oriented obliquely downwards, opening outwards through an orifice 7 closed by a grid 8 secured to the external face of the corresponding wall. 3 or 4 and comprising superimposed parallel strips 9 defining parallel air passage openings in the channel 6 and extending, in this case, parallel to the plane of the bottom wall 10a of the compartment 2, and a second channel upper 11 vertically extending the channel 6 and opening into the compartment 2 through an outlet orifice 12 formed in the internal face of the wall 3 or 4. Preferably, the outlet orifice is closed by a filter 13 housed in interchangeably in a housing 14 integral with the internal face of the wall 3 or 4 and which is made of an active porous material causing the adsorption of atmospheric air which penetrates into the porosities of e the matter then the absorption of this air during which a chemical reaction takes place between the volatile organic compounds of atmospheric air originating for example from the environment of the kitchen in which the refrigerated appliance is located and the

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 matter itself which transforms volatile organic compounds into non-toxic gas, in particular into C02 or SO2.

 The passage 6 thus configured makes it possible to sufficiently cool the atmospheric air entering the compartment 2 to a temperature approximately equal to that of the gaseous medium present in the compartment 2 by condensation of water on a part of the internal cold wall 3a or 4a delimiting the oblique 6 and vertical 11 channels, the oblique channel 6 ensuring the evacuation of water to the outside by runoff as represented by the dotted arrow in FIG. 5. Of course, a small recovery tank can be provided surface water fixed to the wall 4 below the oblique channel 6.

 It is thus understood that the internal pressure of each compartment 2 being at atmospheric pressure, the opening of the door 1 of the refrigerated appliance no longer produces a vacuum in the compartment capable of causing particles to enter it which can contaminate food. stored in this enclosure and the active material filter 13 protects these food products from any contamination by volatile organic compounds contained in atmospheric air passing through the passage 5. The filter 13 can be of the type as described in the published international application WO 00/64499 and therefore need not be described further.

 Of course, it is possible to provide a pressure balancing passage 5 for each of the rear 2 and side 3 walls.

 FIG. 8 is a curve representing an example of evolution of the internal temperature of the preservation compartment over a period of repeated opening and closing of the door of the compartment of the refrigerated appliance when the latter comprises at least the passage 5 in at least one of the side and rear walls of this storage compartment. Thus, for a volume VO of the compartment of approximately 100 liters, a temperature

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 internal TO of about 0 C, an outside temperature Tl of 20 C at normal atmospheric pressure and frequent repeated opening of door 1 of compartment 2 over a period of one hour, the curve in Figure 8 shows that at the end of the one hour period, the internal temperature of the storage compartment is maintained at a value close to 0 C.

The absence of a significant increase in the internal temperature of compartment 2 after opening of door 1 results from the absence of vacuum in this compartment each time the door is opened since the internal pressure PO is at atmospheric pressure .

 FIGS. 4 to 7 represent a ventilation circuit 15 of the gaseous medium present in the compartment 2 and adapted to form an air barrier or curtain situated in a vertical plane near the opening frame of the compartment 2.

 The function of this air barrier is to maintain the internal temperature TO of compartment 2 at a value approximately equal to 0 C and can be used in addition to passage 5 described above or independently when the refrigerated appliance does not have passage 5 .

 The ventilation circuit 15 comprises a duct 16 for suction of the gaseous medium in the compartment 2 and a duct 17 for reintroducing the treated gaseous medium in the compartment 2.

 A fan 18 and a plasma treatment device 19 for the gaseous medium which will be described in detail later, are connected in series in the ventilation circuit constituted by the two conduits 16 and 17.

 Preferably, the suction pipe 16 crosses the rear wall 4 of the refrigerated appliance in the lower part thereof and the reintroduction pipe 17 is connected to the upper wall 10b so as to reintroduce the treated gaseous medium through 'a

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 orifice 19 passing through the wall lOb to diffuse the gaseous medium treated in the compartment 2 towards the rear wall 4.

 The reintroduction conduit 17 is connected to a vertical pipe 20 by means of a pipe 21 sealingly passing through the rear wall 4, the pipe 20 being located in the compartment in the vicinity of one of the vertical framing parts. of the opening of compartment 2 and being pierced with a plurality of micro-orifices 22 to thereby propel jets of pressurized air formed by the sterilized gaseous medium, located in the same vertical plane and directed towards the vertical part of opposite frame in a direction as symbolized by the arrows in Figure 6.

 The reintroduction conduit 17 is also connected to another vertical conduit 23, by means of a conduit 24, being located in the compartment 2 in the vicinity of the opposite framing part of the opening of this compartment, c is to say with regard to the pipe 20.

 Line 23 also includes a plurality of micro-orifices 25 along it and making it possible to propel jets of pressurized air formed by the sterilized gaseous medium and situated in the same vertical plane as the jets of air propelled by the pipe 20 to constitute a barrier forming a curtain as soon as the door 1 of the compartment 2 is opened.

 Preferably, the orifices 22 of the pipe 20 are vertically offset with respect to the orifices 25 of the pipe 23 to form crossed or intertwined air jets constituting the sealing curtain.

According to an alternative embodiment not shown, the pipes 20 and 23 can be arranged horizontally in the vicinity respectively of the upper and lower framing parts of the opening of the compartment 2 so as to propel vertical air jets of

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 forming the sealing curtain. It is also possible to provide both vertical and horizontal conduits located in the vicinity of the frame of the opening of the compartment 2, being suitably connected to the reintroduction conduit 17 for diffusing vertical and horizontal air jets of construction of the sealing curtain behind the door frame.

 Thus, as soon as the door 1 opens, a sterilized air sealing curtain forms to form a barrier preventing the penetration of the surrounding atmospheric air into the compartment 2, thereby avoiding any contamination of the products stored in this compartment.

 FIG. 9 represents an exemplary embodiment of an electronic circuit for controlling the fan 18 and the plasma sterilizer device 19.

 This circuit comprises a central processing unit 26, for example constituted by a microprocessor connected to one of its inputs to a sensor 27 making it possible to supply a signal for detecting the opening of the door 1 of the compartment 2.

 Preferably, the sensor 27 is constituted by a proximity detector fixed to the door 1 opposite the operating handle (la) of this door, but of course the sensor 27 can also be constituted by any other type of detector. , for example with contact opening when door 1 is opened.

 Thus, the sensor 27 can supply the central unit 26 with an electrical signal allowing the latter to control the fan 18 at a relatively high speed to propel the jets of pressurized air in the frame of the opening of the compartment 2 .

 The central unit 26, upon opening the door 1, also controls the plasma sterilizer device 19 at a high operating speed (overpower) at the same time as it controls the fan 18 at high speed.

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 high rotation. For example, the air jets are propelled at a high speed of between 0.6 m / s to 0.8 m / s when the door 1 is opened while in the closed position of this door , the air jets are propelled at a lower speed between 0.2 m / s to 0.4 m / s during normal operation of the plasma sterilizer device 19.

 FIGS. 4 and 9 also show that the door 1 comprises, visible from the outside, an indicator 28 of the speed of circulation of the gaseous medium, an indicator 29 of the operating regime of the plasma sterilizer device 19, a control means 30 by example of the push button control type in automatic operation of the assembly constituted by the fan 18 and the device 19, a means 31 for example constituted by a control push button in manual operation of this assembly, and a setting means 32 the internal temperature To of compartment 2.

 In closed door operation of compartment 2, the central unit 26 controls the fan 18 permanently or periodically to diffuse in the compartment 2 the gaseous medium treated, ensuring sufficient mixing for good homogenization of the temperature of the products to be stored and, consequently, , good conservation of these. In addition, this fan control in closed door operation ensures energy savings.

 The use of at least one balancing passage 5 and / or a sealing barrier for each compartment of a refrigerated appliance comprising several, makes it possible to maintain the internal temperature of each compartment at a constant and optimal value. and thus selectively allocate a compartment to a given type of product to be stored. For example, for a refrigerated appliance with two independent refrigerated compartments, the lower compartment could be used to store meat, fish and

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 cold meats and kept at a storage temperature of around 1 C, while the upper compartment could be used for the storage of dairy products at a temperature of around 6 C.

 The plasma sterilizer device 19 as shown in Figures 10 to 12 is arranged in the circulation circuit 15 in particular of Figure 6 so as to remove the contaminating particles contained in the gaseous medium passing therethrough.

 This device comprises a rigid cylindrical envelope 33 made of an electrically insulating material, such as a plastic material, in which two upstream treatment chambers 34 and downstream 35 are preferably defined in the direction of flow of the gaseous medium passing through them and which are arranged coaxially in extension of one another.

 The two upstream 34 and downstream 35 chambers are delimited between two first and second extreme circular walls 36, 37 made of electrically insulating material and fixed in the envelope respectively at its two ends. The first wall 36 has through holes 38 in the present case made along two circumferences of small and large diameters concentrically with the longitudinal axis XX 'of the envelope 33 for the entry of the gaseous medium to be treated.

The holes 38 preferably have the same diameter.

 The other end wall 37 has two annular passages of small diameter 39 and large diameter 40 concentric with the longitudinal axis XX ′ for the outlet from the treated gaseous medium.

 The two chambers 34 and 35 are separated from each other by a third circular wall 41 fixed in the casing 33 and parallel to the two end walls 36, 37 perpendicular to the axis XX '.

 The intermediate wall 41 is made of an electrically insulating material and has through holes 42 preferably arranged in the same way

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 that the holes 38 of the first plate 36 for the passage of the gaseous medium from the chamber 34 to the chamber 35. The intermediate wall 41 further comprises two discs made of an electrically conductive material 43,44 fixed respectively to the two lateral faces of the wall 41, the two discs being connected to the same high alternating supply voltage HT1. The two discs 43, 44 have identical through bores 43a, 44a and coaxial with the bores 42 of the wall 41.

 Preferably, each disc 43 and 44 is metallic and their connection to the high-voltage power source is effected respectively by two conductive wires each welded to the external peripheral edge of the corresponding disc by crossing the wall of the envelope 33.

 The device 19 further comprises another transverse disc perforated in an electrically conductive material 46 fixed to the internal face of the end wall 36 and connected to a high supply voltage HT2 of the same value as the voltage HT1 and of opposite phase.

 The holes 47 of the disc 46, preferably metallic, are identical to the holes 38 of the end wall 36 and are arranged coaxially with the holes 38.

The disc 46 is sandwiched between the wall 36 and a fourth circular transverse wall 48 made of an electrically insulating material by being fixed in the cylindrical casing 33. The circular wall 48 also has through bores 49 of the same diameter as the bores 38 and coaxial with the holes 38 located on the larger diameter circle. The wall 48 has a central through hole 50 coaxial with the longitudinal axis XX ′ and of a diameter equal to the diameter of the circle in which the holes 38 inscribed on the circle of smallest diameter of the wall 36 are inscribed.

 The device 19 also comprises a central rod 51 made of an electrically conductive material and extending along the longitudinal axis XX ′ of the envelope 33 in the chamber 34. The rod 51, of

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 preferably metallic, is fixed, for example by welding, to the center of the metal disc 46 so as to be connected to the high voltage HT1 and to its free end of conical shape to generate a flow of electrons ionizing the gaseous medium passing through the chamber 34 .

 A coil 52 is coaxially wound on the rod 51 practically all along the latter and is connected to a low voltage power source, for example of 220 V, to create an axial magnetic field increasing the ionization of the gaseous medium by the electron flow.

 The device 19 further comprises an electrically conductive perforated transverse disc 53, connected to the high voltage HT2 and sandwiched between the wall 48 and a sleeve 54 of an electrically insulating material fixed in the envelope 33. The disc 53 has holes 55 of diameter identical to that of the holes 38 in the wall 36 being arranged coaxially with the latter and a central bore 55a concentric with the axis XX ′, the rod 51 and the coil 52 passing through the bore 55a.

 The upstream chamber 34 comprises a cylinder made of an electrically conductive material 56, preferably metallic, fixed in the sleeve 54 concentrically with the axis XX ′ and integral with the disc 53 perpendicularly to the latter. The downstream end of the cylinder 56 is approximately at the same level as the conical end of the rod 51.

 The metal cylinder 56 comprises four radially internal perforated partitions made of an electrically conductive material 57, two by two diametrically opposite in the chamber 54 and extending longitudinally so that their longitudinal free edges parallel to the axis XX 'surround the rod 51 and the coil 52 in the vicinity thereof. Each radial partition 57 extends from the disc 53 to the vicinity of the free end of the cylinder 56.

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 The cylinder 56 also comprises four radially internal partitions perforated in an electrically conductive material 58 also two by two diametrically opposite and having dimensions in radial and longitudinal direction smaller than those of the radial partitions 57. A smaller partition 58 is located between two successive large partitions 57 and the longitudinal free edges of the radial partitions 58 are relatively distant from the central rod 51 by surrounding the latter, each partition 58 also starting from the disc 53.

 Preferably, the partitions 57 and 58 have teeth 57a and 58a along their longitudinal edges and their downstream transverse edges. The toothed downstream transverse edge of each partition 57 is located approximately at the same level as the conical end of the central rod 51 and the downstream transverse edge of each partition 58 is located at a distance from the disc 53 of between one third and half of the length of a partition 57 from the disc 53.

 The fact that the radial partitions 57 are connected to the high voltage alternating power supply HT2 in phase opposition to that of the high voltage alternative supply of the rod 51 makes it possible to create between the spaces between partitions 57 a magnetic resonance generating a circular wave and pulsed increasing the destruction of contaminating particles.

 The partitions of smaller dimensions 58, being connected to the same supply voltage as that of the partitions of large dimensions 57, make it possible to increase the phenomenon of magnetic resonance in the spaces between radial partitions 57. Preferably, the holes 57b of the partitions 57 and 58b partitions 58 are arranged near the longitudinal and transverse toothed edges of these partitions, extending in directions parallel to these edges, so as to further increase the phenomenon of magnetic resonance and, by

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 Consequently, to further increase the destruction efficiency of the contaminating particles.

 The second chamber 35 of the plasma sterilizer device comprises a second cylinder 59 made of an electrically conductive material, preferably metallic, fixed to the perforated disc 44 concentrically to the longitudinal axis XX 'of the device and comprising a series of at least three transverse rows of holes 59a made circumferentially through the side wall of this cylinder. The cylinder 59 further comprises teeth 59b projecting from its circular free edge while extending axially.

 The chamber 35 further comprises a third cylinder 60 made of an electrically conductive material, preferably metallic, fixed to a perforated transverse disc 61 concentrically with the axis XX ′, made of an electrically conductive material, preferably metallic, and connected to the high alternating voltage HT2 by means of a conducting wire fixed by welding to the circular edge of the disc 61 and passing radially through the insulating envelope 33. The disc 61 is sandwiched between a second sleeve 62 made of an electrically material insulator fixed in the casing 33 concentrically to the axis XX 'and the downstream end transverse wall 37. The sleeve 62 also axially maintains the perforated disc 44 against the intermediate wall 41. The holes 61a of the disc 61 coincide respectively with the holes 40 of the end wall 37 and are therefore preferably of concentric annular shape to ensure the exit of the gaseous medium .

 The cylinder 60 has a diameter less than the diameter of the cylinder 59 and is situated opposite the latter by partially penetrating the cylinder 59 as far as the vicinity of the third row of bores 59a from the toothed free end of the cylinder 59.

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 The cylinder 60 also comprises a series of at least three transverse rows of holes 60a produced circumferentially through its side wall from the free circular end of this cylinder. This free end also comprises teeth 60b extending axially in the opposite direction to the teeth 59b of the cylinder 59.

 The application on the two cylinders 59 and 60 of the two alternating high voltages of opposite phases and by the proper configuration of these two cylinders 59 and 60 as well as their nesting one in the other, leads to the formation of a plasma in the downstream chamber 35 making it possible to destroy the substituting particles in the gaseous medium having passed through the upstream chamber 34.

The downstream chamber 35 finally comprises a fourth cylinder 63 made of an electrically conductive material, preferably metallic, integral with the perforated disc 61 concentrically with the longitudinal axis XX 'extending towards the perforated disc 44. The cylinder 63 has a diameter greater than the diameter of the cylinder 59 by partially surrounding the latter and comprises therein a series of at least two parallel rows of radially internal teeth 63a, each row preferably comprising four radially internal teeth two with two diametrically opposite. Of course, it is possible to provide three rows of teeth 63a or four rows of such teeth as shown in FIG. 11.

 Because the cylinder 63 is connected to the high alternating voltage HT2, the teeth 63a generate a transverse plasma improving the destruction of the remaining contaminating particles.

 The plasma sterilizer device effectively purifies and sterilizes any gaseous medium containing contaminating particles and finds applications in many fields such as the food industry, hospitals, building air conditioning, aeronautics and more

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 generally all environments with particulate and bacterial risks.

Claims (19)

1. Device forming a plasma sterilizer (19) allowing the treatment of gaseous medium containing contaminating particles, comprising a casing (33) of an electrically insulating material delimited at its ends by two first and second parallel perforated parallel walls (36, 37) axially spaced apart from an electrically insulating material allowing respectively the entry and exit of the gaseous medium and in which at least one treatment chamber (34) is produced, characterized in that it comprises a central rod (51) made of an electrically conductive material extending longitudinally in the treatment chamber (34) from the perforated wall entering the gaseous medium (36) while being connected to a high voltage alternating supply (HT1) and having its free end of conical shape to generate an electron flow ionizing the gaseous medium, and a coil (52) mounted coaxially on the rod (51) approximately all along it, connected to a low voltage power supply to create an axial magnetic field increasing the ionization of the gaseous medium by the flow of electrons.  2. Device according to claim 1, characterized in that it comprises four perforated radial partitions (57) of an electrically conductive material two to two diametrically opposite in the treatment chamber (34) extending longitudinally so that their edges free longitudinal surround the rod (51) parallel and close to it, the radial partitions (57) being connected to a high voltage AC supply (HT2) in phase opposition to that of the supply (HT1) of the rod (51) for creating in the spaces between partitions (57) a magnetic resonance generating a circular and pulsed wave increasing the destruction of the contaminating particles. <Desc / Clms Page number 24>  3. Device according to claim 2, characterized in that it comprises four other radial perforated partitions of smaller dimensions (58) in an electrically conductive material extending longitudinally in the chamber (34) being two to two diametrically opposite, one partition of smaller dimension (58) being located between two successive partitions of larger dimensions (57), and having their longitudinal free edges relatively distant from the central rod (51) by surrounding the latter, the partitions of smaller dimensions ( 58) being connected to the same power supply (HT2) as that of the large partitions (57) so as to increase the magnetic resonance in the spaces between radial partitions.  4. Device according to claim 3, characterized in that the downstream transverse edge of each bulkhead of larger dimension (57) is located approximately at the same level as the conical end of the central rod (51) and the downstream transverse edge of each smaller partition (58) is located at a longitudinal distance between one third and half the length of a large partition (57).  5. Device according to claim 3 or 4, characterized in that the partitions of small and large dimensions (58,57) have teeth along their longitudinal edges and their transverse downstream edges.  6. Device according to one of the preceding claims, characterized in that it comprises a third intermediate transverse perforated wall (41) defining a second downstream treatment chamber (35) in which there are two concentric longitudinal cylinders (59), ( 60) in an electrically conductive material respectively an upstream cylinder (59) integral with the intermediate wall (41) and comprising at least three circumferential series of bores (59a) from its free downstream end and a downstream cylinder <Desc / Clms Page number 25>  (60) of smaller diameter integral with the downstream end wall (37), partially penetrating into the cylinder of larger diameter (59) and comprising at least three circumferential series of perforations (60a) from its free upstream end located in the larger diameter cylinder (59), the latter being connected to the high voltage power supply (HT1) of the central rod (51) while the smaller diameter cylinder (60) is connected to the high voltage power supply ( HT2) radial partitions (57,58) to thereby create a plasma participating in the destruction of contaminating particles from the gaseous medium circulating in the downstream chamber (35).  7. Device according to claim 6, characterized in that the two small cylinders (60) and large (59) diameters have at their edges of circular ends of the teeth (60b), (59b) extending coaxially to the longitudinal axis passing through the rod (51).  8. Device according to claim 7, characterized in that it also comprises a third cylinder (63) of an electrically conductive material concentrically surrounding the two other concentric cylinders (59) and (60) and comprising several circumferential series of radially internal teeth (63a) preferably four in number, the third cylinder (63) being connected to the high voltage supply (HT2) of the radial partitions (57,58).  9. Device according to one of the preceding claims, characterized in that the envelope (33) is cylindrical and in that the inlet wall of the gaseous medium (36) is circular and fixed transversely in the envelope (33) , the central rod (51) is integral with a first perforated metal disc (46) connected to the high voltage supply (HT1) and sandwiched between the inlet wall (36) and a fourth transverse perforated wall ( 48) electrically material <Desc / Clms Page number 26>  insulator fixed in the casing (33) being traversed by the rod (51) and the coil (52) and in that the radial partitions (57,58) are integral with the interior of a metal cylinder (56) connected at its upstream end to a second perforated metal disc (53) connected to the high-voltage opposite phase supply (HT2) and fixed between the fourth insulating wall (48) and an insulating sleeve (54) integral with the envelope, the central rod (51) and the coil (52) freely passing through a central bore (55a) of the second metal disc (53) extending to the vicinity of the downstream end of the cylinder (56) for supporting the radial partitions ( 57), (58).  10. Device according to claim 9 when considered in combination with one of claims 6 to 8, characterized in that the third perforated intermediate wall (41) is fixed between the first insulating sleeve (54) and a second insulating sleeve (62 ) fixed in the envelope (33), the third wall (41) comprising a circular central part made of an insulating material and two perforated metal discs (43), (44) fixed respectively to the two opposite lateral faces of the central part, the upstream metal cylinder (59) of the second chamber being integral with the downstream metal disc (44) of the third wall (41) transverse to this disc (44).  11. claim 10, characterized in that the downstream cylinder (60) and the third cylinder (63) are integral with a fifth perforated metal disc (61) fixed between the second insulating sleeve (62) and the second circular outlet wall (37) of the gaseous medium fixed in the envelope (33), the fifth disc (61) being connected to the high voltage supply (HT2) of opposite phase.  12. Device according to one of claims 9 to 11, characterized in that the coil (52) is connected to its low voltage supply by its two through wires <Desc / Clms Page number 27>  electrically insulated the central part of the first perforated disc (46) and the first inlet wall (36).  13. Device according to one of the preceding claims, characterized in that each high voltage supply (HT1, HT2) is between approximately 2,000 and approximately 20,000 Volts for a frequency between approximately 5 and approximately 1000 Hz, preferably 50 Hz, and in that the supply voltage of the coil is approximately 220 Volt for a frequency of approximately 50 Hz.  14. Refrigerated appliance comprising at least one food preservation compartment (2), characterized in that it is associated with a plasma sterilizer device (19) according to one of the preceding claims, placed on a ventilation circuit (15) comprising a suction conduit (16) in the compartment of the gaseous medium to be treated present in this compartment and a reintroduction conduit (17) in the compartment of the gaseous medium treated by the sterilizing device (19).  15. Apparatus according to claim 14, characterized in that it comprises in at least one of the side walls (3) and rear (4) of the storage compartment (2) at least one through passage (5) for balancing of the internal pressure of the compartment (2) with the atmospheric pressure and comprising a first lower channel oriented obliquely downwards (6) opening to the outside extended by a second vertical upper channel (11) opening into the storage compartment (2 ), thus also configuring the pressure balancing passage in thermal barrier.  16. Apparatus according to claim 15, characterized in that the pressure balancing passage (5) communicates in the preservation compartment (2) through a filter made of an active porous material (13) causing the adsorption of atmospheric air which penetrates into the porosities of matter then <Desc / Clms Page number 28>  the absorption of this air, during which a chemical reaction takes place between the volatile organic compounds in atmospheric air and the material itself which transforms the volatile organic compounds into non-toxic gas, in particular into C02 or S02.  17. Apparatus according to one of claims 14 to 16, characterized in that the suction pipe (16) opens out in the lower part of the preservation compartment (2) and the reintroduction pipe (17) of the treated gaseous medium opens out in upper part of this compartment (2) and is also connected to at least two separate conduits (20,23) located in the vicinity of the framing part of the compartment access opening (2) so as to propel, at through a multitude of micro-orifices (22,25) produced along the two pipes (20,23), jets of pressurized air situated approximately in the same vertical plane parallel to the opening to form an air barrier sterile preventing depression as soon as the door (1) is opened to access the storage compartment (2).  18. Apparatus according to claim 17, characterized in that the two pipes (20,23) are arranged vertically opposite one another, or horizontally opposite one another or one of the pipes (20) or (23) is horizontal and the other is vertical.  19. Apparatus according to claim 17 or 18, characterized in that it comprises a fan (18) mounted in the ventilation circuit (15) upstream of the sterilizing device (19) and in that it comprises a detection sensor (27) of the opening of the door (1) connected to an electronic control circuit at high speed of the fan (18) and at high efficiency of the sterilizing device (19) as soon as the sensor (27) detects the opening of the door (1).