CA2246353A1 - Device for the cleaning of exhaust gases from internal combustion engines - Google Patents
Device for the cleaning of exhaust gases from internal combustion engines Download PDFInfo
- Publication number
- CA2246353A1 CA2246353A1 CA002246353A CA2246353A CA2246353A1 CA 2246353 A1 CA2246353 A1 CA 2246353A1 CA 002246353 A CA002246353 A CA 002246353A CA 2246353 A CA2246353 A CA 2246353A CA 2246353 A1 CA2246353 A1 CA 2246353A1
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- Prior art keywords
- electrode
- ceramic
- ceramic body
- megohm
- ducts
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/40—Electrode constructions
- B03C3/60—Use of special materials other than liquids
- B03C3/62—Use of special materials other than liquids ceramics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/66—Applications of electricity supply techniques
- B03C3/70—Applications of electricity supply techniques insulating in electric separators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/01—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust by means of electric or electrostatic separators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/0217—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters the filtering elements having the form of hollow cylindrical bodies
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
- F01N3/027—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using electric or magnetic heating means
- F01N3/0275—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using electric or magnetic heating means using electric discharge means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C2201/00—Details of magnetic or electrostatic separation
- B03C2201/12—Cleaning the device by burning the trapped particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C2201/00—Details of magnetic or electrostatic separation
- B03C2201/30—Details of magnetic or electrostatic separation for use in or with vehicles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2330/00—Structure of catalyst support or particle filter
- F01N2330/06—Ceramic, e.g. monoliths
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Processes For Solid Components From Exhaust (AREA)
- Exhaust Gas After Treatment (AREA)
- Electrostatic Separation (AREA)
Abstract
The invention relates to a device for the cleaning of exhaust gases from internal combustion engines, in particular a diesel exhaust soot filter. Said device has a discharge electrode (8), a counterelectrode (28) opposite thereto for electrical charging of the exhaust gas components, a ceramic structure (1) with a circular cross-section and ducts (20) extending therethrough in the direction of flow, and an internal electrode (5) at high voltage. This electrode is arranged on the inner cylinder wall (21) of the ceramic structure (1) and creates an electrical field at right angles to the ducts (20) passing through said ceramic structure. The soot particles are deposited and oxidised on the walls of the ducts (20), and a separation is provided to prevent flow through the hollow internal space (22) of the ceramic structure (1). To prevent the formation of conductive soot bridges between high-voltage-conducting components and earth the separation of the hollow internal space (22) of the ceramic structure (1) is an electrical insulator, preferably a ceramic stopper (4), arranged at the inlet side of the gas stream.
Description
CA 022463~3 l998-08-ll An apparatus for the cleaning of exhaust gases from internal combustion engines The invention relates to an apparatus for the cleaning of exhaust gases from internal combustion engines, in particular a diesel exhaust particulates filter, pursuant to the preamble of claim 1.
The disadvantages of this filter for diesel exhaust particulates known from EP-A 332609 or EP-A 537219 for example are that the exhaust particulates deposited in the particulates filter outside of the ducts of the ceramic body form conducting bridges between the inner electrode and ground after some time which lead to parasitic currents and permanently forming spark gaps.
It is the object of the present invention to eliminate these disadvantages by constructional measures.
This is achieved in an apparatus of the kind mentioned above by the features as mentioned in the characterizing part of claim 1.
By closing off the hollow chamber which comprises the inner electrode which is under high voltage, the permanent formation of conducting exhaust particulates deposits outside of the ducts of the ceramic body can be prevented.
It is preferably provided that the hollow inner chamber of the ceramic body is also sealed off on the rear side by an insulator, preferably a ceramic plug, which has a pass-CA 022463~3 1998-08-11 through of a diameter of preferably 1 to 2 mm through which the inner electrode is supplied with high voltage.
The supply of high voltage on the rear side has the advantage that in this zone already very small exhaust particulates deposits are present and, in addition, the field strength at the pass-through is already so high as a result of the small diameter of the feed line that there occurs an immediate incineration of the exhaust particulates deposited there, which again prevents the formation of conducting bridges of exhaust particulates.
In order to insulate the discharge electrode especially, the discharge electrode can be carried by the ceramic body and be at the same high voltage potential as the inner electrode.
The inclination towards the formation of sparks in the zone of the discharge electrode by precipitated exhaust particulates is counteracted in accordance with the invention in such a way that the backplate electrode opposi~e of the discharge electrode is provided with a ceramic coating with a high electric resistance.
It has proved to be advantageous that the teeth of the discharge electrode are provided at their tips with a ceramic coating with a thickness of between 0.05 mm and 0.2 mm and have an electric volume resistance per tip of between 1 megohm and 1 gigohm, preferably between 10 megohm and 100 megohm.
It can also be advisable in accordance with the invention that the ceramic coating of the backplate electrode has a thickness of between 0.1 and 0.5 mm and has an electric volume resistance of between 1 megohm.cm2 and 1 gigohm.cm2, preferably between 10 megohm.cm2 and 100 megohm.cm2.
CA 022463~3 1998-08-11 Preferably, the coating of the discharge electrode and/or backplate electrode consists of one of the materials Al203, TiO, ZrO and CrO or mixtures thereof.
It is provided in accordance with a further feature in accordance with the invention that the inner electrode arranged on the inner side of the ceramic body is arranged at a distance from the inlet side and pre~erably also from the outlet side of the ducts of the ceramic body. In this way the formation of bridges of exhaust particulates in the inlet and outlet zone o~ the ducts o~ the ceramic body is prevented.
Pursuant to a further embodiment o~ the invention it is provided that between the inner electrode which is at high voltage and the inner cylindrical surface of the ceramic body there is arranged a posistor. Pre~erably, the posistor increases its volume resistance from values below 10 megohm.cm2 to at least 100 megohm.cm2, preferably 300 megohm.cm2, at a temperature rise of 100~C to 500~C.
If at higher temperatures the resistance of the ceramic body decreases too strongly, the high voltage on the inner electrode needs to be reduced because only a limited amount of power can be taken from the onboardmain power supply which supplies the high voltage power supply unit. In this way the discharge or backplate electrode which is switched electrically parallel to the inner electrode would cease to ~ operate in the case o~ a lack of a posistor. The posistor, on the other hand, compensates by increasing its resistance the resistance o~ the ceramic body which decreases at higher temperatures, thus ensuring that the function of the discharge or backplate electrode is not impaired. If an inhomogeneous current distribution occurs in the ceramic body there will further be a local heatup of the ceramic body which can lead to thermal damage to the ceramic body.
The local heatup regulates the local current supply back by CA 022463~3 1998-08-11 way of the rising resistance of the posistor, thus leading to an even distribution of the supplied power.
The invention is now explained in closer detail by reference to the drawings, in which:
Fig. 1 shows a longitudinal sectional view through a first embodiment of an apparatus in accordance with the invention.
Fig. 2 shows a longitudinal sectional view through a further embodiment of an apparatus in accordance with the lnvent lon .
Fig. 3 shows a sectional view along the line III-III in fig. 2.
A ceramic body 1 of annular shape is fastened in a cylindrical tube 2 made of metal by press mats, wire meshes 3 or the like. The hollow cylindrical inner chamber 22 of ceramic body 1 is closed off on either side by plugs 4, 4'.
A preferably metallic layer 5 which is electrically conducting is arranged on the inner wall 21 of the ceramic body 1, which layer is used as an inner electrode which is connected with high voltage. A metallic layer 6 is arranged on the outer cylinder wall of ceramic body 1, which layer is used as an outer electrode and is connected to ground.
The ceramic body 1 is provided with continuous ducts 20 which extend in the longitudinal direction and which preferably are provided with the brick structure known from EP-A 537219. The two plugs 4, 4' are each provided with a pass-through 23, 23', with an axially extending metallic tube 7 reaching through the same, which tube is as thin as possible in its diameter and carries on the inlet side the backplate electrode 28. In order to be able to positionally fix the tube 7, inserts (not shown) with waves or ribs extending in the axial direction of the tube are provided CA 022463~3 1998-08-11 in the pass-throughs 23, 23' between tube 7 and insulators 4, 4'. Tube 7 tapers on the outlet side towards a connecting end 12 which engages in a receiving opening 13 of a cylindrical ceramic holding means 10 and is supplied with high voltage by way of a conduc~or 11 guided in the holding means 10. The inner electrode 5 is connected with high voltage via the conductor 11, the connecting end 12, the tube 7 and a contact spring 9 attached on tube 7. An electric field builds up in the ceramic body 1 transversally to the continuous ducts 20 between the inner electrode 5 which is at high voltage and the outer electrode 6 connected to ground. In order to support this field the tube 7 can be arranged between the insulators 4, 4' as an emission electrode. The ceramic body 1 is preferably made of a cordierite mass by high-pressure extrusion and is then ~ired at high temperatures. The ceramic body 1 is to have a very low porosity, preferably lower than 0.5 %. The height of the ducts is usually between 0.6 and 1 mm and the width of the ducts 20 is between 3 and 6 mm, depending on radial position.
The discharge electrode is ~ormed by a cylindrical tube body 8 which emits electrons, is provided with spray teeth 24 and rests on tube 2. The backplate electrode 28 which is opposite o~ the discharge electrode 8 comprises a cylindrical basic body which tapers conically on the inlet side. The backplate electrode 28 comprises a ceramic coating 14. The coating has a thickness of 0.1 to 0.5 mm and comprises an electric volume resistance relating to cm2 o~ 1 megohm.cm2 to 1 gigohm.cm2, preferably 10 megohm.cm2 to 100 megohm.cm2. The high voltage at the inner electrode 5 and thus the backplate electrode 28 is approx. + 8 to 12 kV. Pre~erably, the high voltage is regulated proportional to the volume or mass flow o~ the exhaust gas within an interval from 2 kV/cm to 6 kV/cm relating to the distance between inner electrode 5 and outer electrode 6.
CA 022463~3 1998-08-11 The exhaust gas flowing in ~rom the inlet side A and being charged with diesel exhaust particulates flows into the ring duct 26 against the inlet openings of the ducts 20 o~
the ceramic body 1, which ring duct 26 is formed by the discharge electrode 8 and the backplate electrode 28. The exhaust gas particulates are ionised in the ring duct 26 and penetrate the ducts 20 of the ceramic body 1. As a result of the electric field which is built up transversally to the ducts 20, the exhaust particulates which are contained in the exhaust gas and are charged by the discharge electrode 8 are deposited on the wall sur~aces o~ the ducts 20 and are oxidised electrochemically by a gas plasma of emitted electrons formed as a result of the high electric field strength. Exhaust particulates o~
the exhaust gas leaving the ring chamber 26 cannot reach the inner chamber 22 of ceramic body 1 and thus the inner electrode 5 as a result o~ the plug 4. The majority o~ the exhaust particulates contained in the exhaust gas will penetrate the ducts 20 and will be oxidised by the gas plasma a~ter being deposited on the walls o~ the ducts 20.
Exhaust particulates which deposit on the outer side of the pass-through 23 on plug 4 or tube 5 and thus form conducting bridges o~ exhaust particulates are incinerated by spark formation as a result of the small diameter of tube 7 and the thus prevailing high field strength, so that no longer conducting bridges o~ exhaust particulates can form there. The inner electrode 5 which is at high voltage is also protected ~rom the outlet side B by the plug 4'. At the outlet side B the exhaust gas exiting the ducts has already substantially been cleaned from exhaust particulates. However, i~ residues of exhaust particulates are deposited on tube 7 or closing end 12 at outlet side B, high ~ield strengths will occur as a result of the small diameter o~ tube 7 or the closing end 12, as a result o~
which the exhaust particulates deposited there will incinerate by spark formation. As is shown in fig. 1, the inner electrode 5 and the outer electrode 6 do not extend CA 022463~3 1998-08-11 over the entire length of ceramic body 1, so that a virtually ~ield-~ree zone o~ ~low will be retained in the inlet and outlet zone of ceramic body 1. In this way any short circuiting of the inner electrode 5 with the outer electrode 6 by way o~ any brldges of exhaust particulates occurring at the inlet or outlet openings of the ducts is prevented.
Fig. 2 shows a sectional view along the main axis of another embodiment o~ a converter ~or diesel exhaust particulates. In the converter ~or diesel exhaust particulates pursuant to fig. 2 the ceramic body 1 is electrically and mechanically separated from the discharge electrode 29. The ceramic body 1 having the continuous ducts 20 for the diesel exhaust particulates is also provided with an annular diameter and is ~astened by press mats or wire meshes 3 in an extended tubular portion of the exhaust gas tube 2. The hollow inner part 22 of the ceramic body 1 is closed o~ on the inlet side by a non-conducting, preferably ceramic plug 4. An electrically conducting layer is arranged on the inner and outer cylinder jacket of the ceramic body 1, which layer is used as an inner electrode 5 which is at high voltage or an outer electrode 6 which is at ground. The hollow inner chamber 22 of the ceramic body 1 is closed of~ on the outlet side by a non-conducting, preferably ceramic plug 4'. Plug 4' comprises a thin bore through which extends a metallic tube 7 which is as thin as possible and per~orms the contacting of the inner electrode 5 with the help of a contact spring 9. The high voltage is supplied to tube 7 by a conductor 11 arranged in a ceramic cylindrical holding means 10. The rear-sided end of the tube 7 tapers into a pin 12 which is electrically connected with the conductor 11 and engages in a recess 13 of the holding means 10. The high-voltage values are substantially identical with those of the embodiment according to fig. 1, but the high voltage is provided with a negative polarity on the inner electrode 5 and on the discharge electrode 29.
CA 022463~3 1998-08-11 The discharge electrode 29 is arranged electrically and mechanically separate from the ceramic body 1 in tube 2 of the exhaust gas strand. The discharge electrode 29 comprises a basic body 25 which carries cylindrical spray teeth 24 and is provided on either side with thin pins 18, 18' which preferably have a thickness o~ 2 to 4 mm and by which the discharge electrode 8 is supported in recesses 19, 19' of ceramic holding means 15, 16. The high voltage is supplied to the discharge electrode 29 via pin 18 by a conductor 17 guided in the holding means 16. The backplate electrode 30 encompassing the discharge electrode 29 is formed by a ceramic coating applied to tube 2 which has a thickness of O.lmm to 0.5mm. The electric resistance values correspond to those of the backplate electrode 14 in the embodiment pursuant to ~ig. 1.
A posistor 27 is arranged between the inner electrode 5 and the inner wall 21 of the ceramic body 1, which posistor increases its resistance in the case of any increase of temperature. By the increase of its resistance, the posistor 27 compensates the resistance of the ceramic body 1 which decreases at higher temperatures.
The exhaust gas entering at A is ionised in the ring chamber 26 between the discharge electrode 29 and the backplate electrode 30 and flows through the ducts 20 of ceramic body 1 and leaves the exhaust particulates filter at B. As a result of the electric field which is built up between the inner electrode 5 and the outer electrode 6, there will be a separation of the exhaust gas particulates contained in the exhaust gas on the side walls of ducts 20.
Electrons will emit from the walls of ducts 20 as a result of the temperature, which electrons are accelerated in the direction towards the deposits of exhaust particulates by the electric field prevailing there and trigger an oxidation of the deposits of exhaust particulates on impact.
The disadvantages of this filter for diesel exhaust particulates known from EP-A 332609 or EP-A 537219 for example are that the exhaust particulates deposited in the particulates filter outside of the ducts of the ceramic body form conducting bridges between the inner electrode and ground after some time which lead to parasitic currents and permanently forming spark gaps.
It is the object of the present invention to eliminate these disadvantages by constructional measures.
This is achieved in an apparatus of the kind mentioned above by the features as mentioned in the characterizing part of claim 1.
By closing off the hollow chamber which comprises the inner electrode which is under high voltage, the permanent formation of conducting exhaust particulates deposits outside of the ducts of the ceramic body can be prevented.
It is preferably provided that the hollow inner chamber of the ceramic body is also sealed off on the rear side by an insulator, preferably a ceramic plug, which has a pass-CA 022463~3 1998-08-11 through of a diameter of preferably 1 to 2 mm through which the inner electrode is supplied with high voltage.
The supply of high voltage on the rear side has the advantage that in this zone already very small exhaust particulates deposits are present and, in addition, the field strength at the pass-through is already so high as a result of the small diameter of the feed line that there occurs an immediate incineration of the exhaust particulates deposited there, which again prevents the formation of conducting bridges of exhaust particulates.
In order to insulate the discharge electrode especially, the discharge electrode can be carried by the ceramic body and be at the same high voltage potential as the inner electrode.
The inclination towards the formation of sparks in the zone of the discharge electrode by precipitated exhaust particulates is counteracted in accordance with the invention in such a way that the backplate electrode opposi~e of the discharge electrode is provided with a ceramic coating with a high electric resistance.
It has proved to be advantageous that the teeth of the discharge electrode are provided at their tips with a ceramic coating with a thickness of between 0.05 mm and 0.2 mm and have an electric volume resistance per tip of between 1 megohm and 1 gigohm, preferably between 10 megohm and 100 megohm.
It can also be advisable in accordance with the invention that the ceramic coating of the backplate electrode has a thickness of between 0.1 and 0.5 mm and has an electric volume resistance of between 1 megohm.cm2 and 1 gigohm.cm2, preferably between 10 megohm.cm2 and 100 megohm.cm2.
CA 022463~3 1998-08-11 Preferably, the coating of the discharge electrode and/or backplate electrode consists of one of the materials Al203, TiO, ZrO and CrO or mixtures thereof.
It is provided in accordance with a further feature in accordance with the invention that the inner electrode arranged on the inner side of the ceramic body is arranged at a distance from the inlet side and pre~erably also from the outlet side of the ducts of the ceramic body. In this way the formation of bridges of exhaust particulates in the inlet and outlet zone o~ the ducts o~ the ceramic body is prevented.
Pursuant to a further embodiment o~ the invention it is provided that between the inner electrode which is at high voltage and the inner cylindrical surface of the ceramic body there is arranged a posistor. Pre~erably, the posistor increases its volume resistance from values below 10 megohm.cm2 to at least 100 megohm.cm2, preferably 300 megohm.cm2, at a temperature rise of 100~C to 500~C.
If at higher temperatures the resistance of the ceramic body decreases too strongly, the high voltage on the inner electrode needs to be reduced because only a limited amount of power can be taken from the onboardmain power supply which supplies the high voltage power supply unit. In this way the discharge or backplate electrode which is switched electrically parallel to the inner electrode would cease to ~ operate in the case o~ a lack of a posistor. The posistor, on the other hand, compensates by increasing its resistance the resistance o~ the ceramic body which decreases at higher temperatures, thus ensuring that the function of the discharge or backplate electrode is not impaired. If an inhomogeneous current distribution occurs in the ceramic body there will further be a local heatup of the ceramic body which can lead to thermal damage to the ceramic body.
The local heatup regulates the local current supply back by CA 022463~3 1998-08-11 way of the rising resistance of the posistor, thus leading to an even distribution of the supplied power.
The invention is now explained in closer detail by reference to the drawings, in which:
Fig. 1 shows a longitudinal sectional view through a first embodiment of an apparatus in accordance with the invention.
Fig. 2 shows a longitudinal sectional view through a further embodiment of an apparatus in accordance with the lnvent lon .
Fig. 3 shows a sectional view along the line III-III in fig. 2.
A ceramic body 1 of annular shape is fastened in a cylindrical tube 2 made of metal by press mats, wire meshes 3 or the like. The hollow cylindrical inner chamber 22 of ceramic body 1 is closed off on either side by plugs 4, 4'.
A preferably metallic layer 5 which is electrically conducting is arranged on the inner wall 21 of the ceramic body 1, which layer is used as an inner electrode which is connected with high voltage. A metallic layer 6 is arranged on the outer cylinder wall of ceramic body 1, which layer is used as an outer electrode and is connected to ground.
The ceramic body 1 is provided with continuous ducts 20 which extend in the longitudinal direction and which preferably are provided with the brick structure known from EP-A 537219. The two plugs 4, 4' are each provided with a pass-through 23, 23', with an axially extending metallic tube 7 reaching through the same, which tube is as thin as possible in its diameter and carries on the inlet side the backplate electrode 28. In order to be able to positionally fix the tube 7, inserts (not shown) with waves or ribs extending in the axial direction of the tube are provided CA 022463~3 1998-08-11 in the pass-throughs 23, 23' between tube 7 and insulators 4, 4'. Tube 7 tapers on the outlet side towards a connecting end 12 which engages in a receiving opening 13 of a cylindrical ceramic holding means 10 and is supplied with high voltage by way of a conduc~or 11 guided in the holding means 10. The inner electrode 5 is connected with high voltage via the conductor 11, the connecting end 12, the tube 7 and a contact spring 9 attached on tube 7. An electric field builds up in the ceramic body 1 transversally to the continuous ducts 20 between the inner electrode 5 which is at high voltage and the outer electrode 6 connected to ground. In order to support this field the tube 7 can be arranged between the insulators 4, 4' as an emission electrode. The ceramic body 1 is preferably made of a cordierite mass by high-pressure extrusion and is then ~ired at high temperatures. The ceramic body 1 is to have a very low porosity, preferably lower than 0.5 %. The height of the ducts is usually between 0.6 and 1 mm and the width of the ducts 20 is between 3 and 6 mm, depending on radial position.
The discharge electrode is ~ormed by a cylindrical tube body 8 which emits electrons, is provided with spray teeth 24 and rests on tube 2. The backplate electrode 28 which is opposite o~ the discharge electrode 8 comprises a cylindrical basic body which tapers conically on the inlet side. The backplate electrode 28 comprises a ceramic coating 14. The coating has a thickness of 0.1 to 0.5 mm and comprises an electric volume resistance relating to cm2 o~ 1 megohm.cm2 to 1 gigohm.cm2, preferably 10 megohm.cm2 to 100 megohm.cm2. The high voltage at the inner electrode 5 and thus the backplate electrode 28 is approx. + 8 to 12 kV. Pre~erably, the high voltage is regulated proportional to the volume or mass flow o~ the exhaust gas within an interval from 2 kV/cm to 6 kV/cm relating to the distance between inner electrode 5 and outer electrode 6.
CA 022463~3 1998-08-11 The exhaust gas flowing in ~rom the inlet side A and being charged with diesel exhaust particulates flows into the ring duct 26 against the inlet openings of the ducts 20 o~
the ceramic body 1, which ring duct 26 is formed by the discharge electrode 8 and the backplate electrode 28. The exhaust gas particulates are ionised in the ring duct 26 and penetrate the ducts 20 of the ceramic body 1. As a result of the electric field which is built up transversally to the ducts 20, the exhaust particulates which are contained in the exhaust gas and are charged by the discharge electrode 8 are deposited on the wall sur~aces o~ the ducts 20 and are oxidised electrochemically by a gas plasma of emitted electrons formed as a result of the high electric field strength. Exhaust particulates o~
the exhaust gas leaving the ring chamber 26 cannot reach the inner chamber 22 of ceramic body 1 and thus the inner electrode 5 as a result o~ the plug 4. The majority o~ the exhaust particulates contained in the exhaust gas will penetrate the ducts 20 and will be oxidised by the gas plasma a~ter being deposited on the walls o~ the ducts 20.
Exhaust particulates which deposit on the outer side of the pass-through 23 on plug 4 or tube 5 and thus form conducting bridges o~ exhaust particulates are incinerated by spark formation as a result of the small diameter of tube 7 and the thus prevailing high field strength, so that no longer conducting bridges o~ exhaust particulates can form there. The inner electrode 5 which is at high voltage is also protected ~rom the outlet side B by the plug 4'. At the outlet side B the exhaust gas exiting the ducts has already substantially been cleaned from exhaust particulates. However, i~ residues of exhaust particulates are deposited on tube 7 or closing end 12 at outlet side B, high ~ield strengths will occur as a result of the small diameter o~ tube 7 or the closing end 12, as a result o~
which the exhaust particulates deposited there will incinerate by spark formation. As is shown in fig. 1, the inner electrode 5 and the outer electrode 6 do not extend CA 022463~3 1998-08-11 over the entire length of ceramic body 1, so that a virtually ~ield-~ree zone o~ ~low will be retained in the inlet and outlet zone of ceramic body 1. In this way any short circuiting of the inner electrode 5 with the outer electrode 6 by way o~ any brldges of exhaust particulates occurring at the inlet or outlet openings of the ducts is prevented.
Fig. 2 shows a sectional view along the main axis of another embodiment o~ a converter ~or diesel exhaust particulates. In the converter ~or diesel exhaust particulates pursuant to fig. 2 the ceramic body 1 is electrically and mechanically separated from the discharge electrode 29. The ceramic body 1 having the continuous ducts 20 for the diesel exhaust particulates is also provided with an annular diameter and is ~astened by press mats or wire meshes 3 in an extended tubular portion of the exhaust gas tube 2. The hollow inner part 22 of the ceramic body 1 is closed o~ on the inlet side by a non-conducting, preferably ceramic plug 4. An electrically conducting layer is arranged on the inner and outer cylinder jacket of the ceramic body 1, which layer is used as an inner electrode 5 which is at high voltage or an outer electrode 6 which is at ground. The hollow inner chamber 22 of the ceramic body 1 is closed of~ on the outlet side by a non-conducting, preferably ceramic plug 4'. Plug 4' comprises a thin bore through which extends a metallic tube 7 which is as thin as possible and per~orms the contacting of the inner electrode 5 with the help of a contact spring 9. The high voltage is supplied to tube 7 by a conductor 11 arranged in a ceramic cylindrical holding means 10. The rear-sided end of the tube 7 tapers into a pin 12 which is electrically connected with the conductor 11 and engages in a recess 13 of the holding means 10. The high-voltage values are substantially identical with those of the embodiment according to fig. 1, but the high voltage is provided with a negative polarity on the inner electrode 5 and on the discharge electrode 29.
CA 022463~3 1998-08-11 The discharge electrode 29 is arranged electrically and mechanically separate from the ceramic body 1 in tube 2 of the exhaust gas strand. The discharge electrode 29 comprises a basic body 25 which carries cylindrical spray teeth 24 and is provided on either side with thin pins 18, 18' which preferably have a thickness o~ 2 to 4 mm and by which the discharge electrode 8 is supported in recesses 19, 19' of ceramic holding means 15, 16. The high voltage is supplied to the discharge electrode 29 via pin 18 by a conductor 17 guided in the holding means 16. The backplate electrode 30 encompassing the discharge electrode 29 is formed by a ceramic coating applied to tube 2 which has a thickness of O.lmm to 0.5mm. The electric resistance values correspond to those of the backplate electrode 14 in the embodiment pursuant to ~ig. 1.
A posistor 27 is arranged between the inner electrode 5 and the inner wall 21 of the ceramic body 1, which posistor increases its resistance in the case of any increase of temperature. By the increase of its resistance, the posistor 27 compensates the resistance of the ceramic body 1 which decreases at higher temperatures.
The exhaust gas entering at A is ionised in the ring chamber 26 between the discharge electrode 29 and the backplate electrode 30 and flows through the ducts 20 of ceramic body 1 and leaves the exhaust particulates filter at B. As a result of the electric field which is built up between the inner electrode 5 and the outer electrode 6, there will be a separation of the exhaust gas particulates contained in the exhaust gas on the side walls of ducts 20.
Electrons will emit from the walls of ducts 20 as a result of the temperature, which electrons are accelerated in the direction towards the deposits of exhaust particulates by the electric field prevailing there and trigger an oxidation of the deposits of exhaust particulates on impact.
Claims (14)
1. An apparatus for the cleaning of exhaust gases from internal combustion engines, in particular a filter for diesel exhaust particulates, with a discharge electrode (8; 29) and a backplate electrode (28, 30) opposite thereto for electrically charging the exhaust gas particulates and a ceramic body (1) of annular cross section and with continuous ducts (20) extending in the direction of flow and with an inner electrode (5) which is at high voltage and is arranged on the inner cylinder wall (21) of the ceramic body (1) and builds up an electric field transversally to the continuous ducts (20), with the exhaust particulates being deposited and oxidised on the walls of the ducts (20) and a separation being provided for preventing any flowing through of the hollow inner chamber (22) of the ceramic body by the exhaust gas, characterized in that the separation of the hollow chamber (22) of the ceramic body (1) is formed by an electric insulator, preferably a ceramic plug (4), which is arranged on the inlet side of the exhaust gas stream.
2. An apparatus as claimed in claim 1, characterized in that the hollow inner chamber (22) of the ceramic body (1) is also closed off on the rear side by an insulator, preferably by a ceramic plug (4'), which is provided with a pass-through (23') of a diameter of preferably 1 to 2 mm through which the inner electrode (5) is supplied with high voltage.
3. An apparatus as claimed in claim 1 or 2, characterized in that the insulator (4) is also provided with a pass-through (23) on the inlet side of the exhaust gas stream through which passes an electrically conducting connecting element (7) which is preferably tube-like and carries the backplate electrode (28) (fig. 1).
4. An apparatus as claimed in claim 3, characterized in that the pass-through (23) of the insulator (4) is provided with a diameter of not more than 10 mm on the inlet side of the exhaust gas stream.
5. An apparatus as claimed in claim 1, characterized in that the discharge electrode (29) tapers off on either end into thin pins (18, 18') which have a preferable thickness of 2 to 4 mm and are held in ceramic holding means (15, 16) which penetrate the tubular backplate electrode (30) on either side and/or rest on the same and at least one of the two ceramic holding means (16) comprises a high-voltage supply (17) for the discharge electrode (29).
6. An apparatus as claimed in one of the claims 1 to 5, characterized in that the discharge electrode (8; 29) and/or the backplate electrode which is opposite thereto (28; 30) comprises a ceramic coating with high electric resistance.
7. An apparatus as claimed in claim 6, characterized in that the spray teeth (24) of the discharge electrode (8; 29) are provided at their tips with a ceramic coating with a thickness of between 0.05 mm and 0.2 mm and thereby have an electric volume resistance per tip of between 1 megohm and 1 gig ohm, preferably between 10 megohm and 100 megohm.
8. An apparatus as claimed in claim 6, characterized in that the ceramic coating of the backplate electrode (28; 30) has a thickness of between 0.1 and 0.5 mm and comprises an electric volume resistance of between 1 megohm.cm2 and 1 gigohm.cm2, preferably between 10 megohm.cm2 and 100 megohm.cm2.
9. An apparatus as claimed in claim 6, characterized in that the coating of the discharge electrode (8; 29) and/or backplate electrode (28; 30) consists of one of the materials Al2O3, TiO, ZrO and CrO or mixtures thereof.
10. An apparatus as claimed in one of the claims 1 to 9, characterized in that the inner electrode (5) arranged on the inner side of the ceramic body (1) is arranged at a distance from the inlet side and, preferably, also from the outlet side of the ducts (20) of the ceramic body (1).
11. An apparatus as claimed in one of the claims 1 to 10, characterized in that a posistor (27) is arranged between the inner electrode (5) which is at high voltage and the inner cylindrical surface (21) of the ceramic body (1).
12. An apparatus as claimed in claim 11, characterized in that the posistor (27) increases its volume resistance from values below 10 megohm.cm2 to at least 100 megohm.cm2, preferably 300 megohm.cm2, at a temperature increase from 100°C to 500°C.
13. An apparatus as claimed in claim 3, characterized in that the tubular connecting element (7) in the inner chamber (22) of the ceramic body (1), which element carries the backplate electrode (28) and is electrically conducting, is arranged between the insulators (4, 4') as an emission electrode.
14. An apparatus as claimed in claim 3 or 13, characterized in that inserts with waves or ribs extending in the axial direction are provided in the pass-throughs (23, 23') of the insulators (4, 4') between the tubular connecting element (7) and the insulators (4, 4').
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT0024696A ATA24696A (en) | 1996-02-12 | 1996-02-12 | DEVICE FOR PURIFYING EXHAUST GASES FROM INTERNAL COMBUSTION ENGINES |
| ATA246/96 | 1996-02-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2246353A1 true CA2246353A1 (en) | 1997-08-21 |
Family
ID=3485438
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002246353A Abandoned CA2246353A1 (en) | 1996-02-12 | 1997-02-10 | Device for the cleaning of exhaust gases from internal combustion engines |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0880642B1 (en) |
| JP (1) | JP4005137B2 (en) |
| AT (2) | ATA24696A (en) |
| AU (1) | AU1711997A (en) |
| BR (1) | BR9707497A (en) |
| CA (1) | CA2246353A1 (en) |
| CZ (1) | CZ254898A3 (en) |
| DE (1) | DE59700888D1 (en) |
| HU (1) | HUP9901677A3 (en) |
| PL (1) | PL328241A1 (en) |
| WO (1) | WO1997030274A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2781690B1 (en) * | 1998-08-03 | 2002-04-12 | Ecia Equip Composants Ind Auto | DEVICE FOR REGENERATING A PARTICLE FILTER FOR PURIFYING EXHAUST GASES OF A MOTOR VEHICLE |
| GB2351923A (en) | 1999-07-12 | 2001-01-17 | Perkins Engines Co Ltd | Self-cleaning particulate filter utilizing electric discharge currents |
| GB2358149A (en) * | 2000-01-14 | 2001-07-18 | Quantum Fuel Technology Ltd | Ionising chamber for reducing exhaust emissions |
| DE10102491C2 (en) * | 2001-01-19 | 2003-04-17 | Walter Hofmann | Method for operating a device in the exhaust system of an internal combustion engine for checking the pollution of the exhaust gas flow with soot particles, and this device |
| AT410761B (en) * | 2001-03-26 | 2003-07-25 | Meier Stauffer Gerd Dr | Soot filter and catalyst for diesel engines includes differential pressure measurement controlling high voltage discharge to burn-off soot |
| US7514047B2 (en) * | 2003-01-15 | 2009-04-07 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying apparatus |
| AT500959B1 (en) * | 2004-11-09 | 2007-05-15 | Carl M Dr Fleck | METHOD AND FILTER ARRANGEMENT FOR SEPARATING RUSSIAN PARTICLES |
| AT501888B1 (en) | 2005-06-08 | 2006-12-15 | Fleck Carl M Dr | WAVE FILTER WITH PLANAR ELECTRODES |
| AT503022B1 (en) * | 2006-06-29 | 2007-07-15 | Fleck Carl M Dr | Filter arrangement for separating soot particles from an exhaust flow, comprises electrode arrangement through which exhaust gas flows and which charges soot particles, which are removed from exhaust flow by electrical field or mechanically |
| FR2907843B1 (en) * | 2006-10-26 | 2009-01-23 | Renault Sas | ELECTRIC SOFT PARTICLE CAPTURING DEVICE OF EXHAUST GAS OF INTERNAL COMBUSTION ENGINE. |
| CH702125B1 (en) * | 2007-03-27 | 2011-05-13 | Rudolf Bolliger Dipl. Ei. Ing. Htl | An electrostatic dust filter. |
| DE102010044252B4 (en) * | 2010-09-02 | 2014-03-27 | Reinhausen Plasma Gmbh | Apparatus and method for generating a barrier discharge in a gas stream |
| DE102010044343A1 (en) * | 2010-09-03 | 2012-03-08 | Emitec Gesellschaft Für Emissionstechnologie Mbh | Device with an annular electrode for reducing soot particles in the exhaust gas of an internal combustion engine |
| CN107684976A (en) * | 2016-08-05 | 2018-02-13 | 刘景文 | Air electrostatic branner |
| TWI678233B (en) * | 2019-03-29 | 2019-12-01 | 劉景文 | Combined structure of electrostatic dust cleaning machine |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4979364A (en) * | 1988-03-11 | 1990-12-25 | Fleck Carl M | Diesel fuel exhaust gas filter |
| DE3834920A1 (en) * | 1988-10-13 | 1990-04-19 | Man Nutzfahrzeuge Ag | METHOD AND DEVICE FOR ELIMINATING SOOT SEPARATED IN AN EXHAUST FILTER OF AN INTERNAL COMBUSTION ENGINE |
| EP0537219B1 (en) * | 1990-07-02 | 1994-03-02 | Fleck, Carl Maria, Prof. Dr. | Process and device for cleaning exhaust gases |
| DE4200343C2 (en) * | 1992-01-09 | 1993-11-11 | Metallgesellschaft Ag | Electrostatic separator |
| JPH05277313A (en) * | 1992-03-31 | 1993-10-26 | Teikoku Piston Ring Co Ltd | Fine particle separating device |
-
1996
- 1996-02-12 AT AT0024696A patent/ATA24696A/en unknown
-
1997
- 1997-02-10 WO PCT/AT1997/000024 patent/WO1997030274A1/en not_active Application Discontinuation
- 1997-02-10 DE DE59700888T patent/DE59700888D1/en not_active Expired - Fee Related
- 1997-02-10 CA CA002246353A patent/CA2246353A1/en not_active Abandoned
- 1997-02-10 PL PL97328241A patent/PL328241A1/en unknown
- 1997-02-10 BR BR9707497-7A patent/BR9707497A/en not_active Application Discontinuation
- 1997-02-10 JP JP52881497A patent/JP4005137B2/en not_active Expired - Fee Related
- 1997-02-10 AT AT97904288T patent/ATE188015T1/en not_active IP Right Cessation
- 1997-02-10 AU AU17119/97A patent/AU1711997A/en not_active Abandoned
- 1997-02-10 EP EP97904288A patent/EP0880642B1/en not_active Expired - Lifetime
- 1997-02-10 HU HU9901677A patent/HUP9901677A3/en unknown
- 1997-02-10 CZ CZ982548A patent/CZ254898A3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ATE188015T1 (en) | 2000-01-15 |
| DE59700888D1 (en) | 2000-01-27 |
| PL328241A1 (en) | 1999-01-18 |
| EP0880642B1 (en) | 1999-12-22 |
| HUP9901677A2 (en) | 1999-08-30 |
| BR9707497A (en) | 2000-01-04 |
| AU1711997A (en) | 1997-09-02 |
| EP0880642A1 (en) | 1998-12-02 |
| CZ254898A3 (en) | 1998-11-11 |
| ATA24696A (en) | 2000-10-15 |
| HUP9901677A3 (en) | 2000-03-28 |
| JP2000504805A (en) | 2000-04-18 |
| WO1997030274A1 (en) | 1997-08-21 |
| JP4005137B2 (en) | 2007-11-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |