EP0215205B1 - Device for the removal of combustible particles from the exhaust gas of a combustion engine - Google Patents

Device for the removal of combustible particles from the exhaust gas of a combustion engine Download PDF

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Publication number
EP0215205B1
EP0215205B1 EP86108625A EP86108625A EP0215205B1 EP 0215205 B1 EP0215205 B1 EP 0215205B1 EP 86108625 A EP86108625 A EP 86108625A EP 86108625 A EP86108625 A EP 86108625A EP 0215205 B1 EP0215205 B1 EP 0215205B1
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EP
European Patent Office
Prior art keywords
additional
combustion chamber
fuel
air
combustion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP86108625A
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German (de)
French (fr)
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EP0215205A1 (en
Inventor
Rolf Dr. Leonhard
Hubert Dettling
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Robert Bosch GmbH
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Robert Bosch GmbH
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Filing date
Publication date
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Priority to AT86108625T priority Critical patent/ATE42800T1/en
Publication of EP0215205A1 publication Critical patent/EP0215205A1/en
Application granted granted Critical
Publication of EP0215205B1 publication Critical patent/EP0215205B1/en
Expired legal-status Critical Current

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Classifications

    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/38—Arrangements for igniting
    • 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
    • F01N3/025—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 fuel burner or by adding fuel to exhaust
    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/26—Construction of thermal reactors
    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/30—Arrangements for supply of additional air
    • F01N3/306—Preheating additional air
    • 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
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/36—Arrangements for supply of additional fuel

Definitions

  • the invention is based on a device according to the preamble of the main claim.
  • a device known from DE-C-3 424 196 the exhaust gas coming from the internal combustion engine is divided with the aid of an electrostatic soot switch and a downstream centrifugal separator into an exhaust gas stream which is enriched with combustible solid particles, in particular soot, and in a partial exhaust gas stream which is largely freed from such particles.
  • the exhaust gas partial flow enriched with combustible solid particles is fed to a combustion chamber in the known device, preferably with the addition of a fuel-air mixture and both media, soot-laden exhaust gas and fuel-air mixture, passed through an electric heater and burned there.
  • These combustion components are introduced coaxially into the cylindrical combustion chamber via a common immersion tube, the heating element itself being arranged within the immersion tube. The combustion products are then discharged downstream of the electric heater in countercurrent near the mouth of the dip tube from the combustion chamber.
  • This device has the disadvantage that a considerable amount of electrical energy is required for the combustion of the combustible solid particles combined with a complex control of additional air, additional fuel and heating power of the heating element, in which on the one hand the necessary ignition temperature must be maintained and on the other hand overheating due to the danger failure of this heater must be avoided.
  • the temperature load on the heating element is also adversely affected by the amount of fuel-air mixture introduced and the amount of combustible solid particles introduced.
  • everything that leaves the immersion tube is discharged into the environment through the outlet at the end of the combustion chamber. If the soot introduced into the combustion chamber has not been completely burnt, it is filtered out again by an expensive additional filter and the residual gases are fed to the outlet.
  • This additional filter means an additional effort with the risk that the filter will be damaged by high afterburning temperatures over the period of operation. It is then not excluded that unburned solid particles get to the outlet. In addition, the filter increases the back pressure on the exhaust side, which worsens the efficiency of the upstream combustion devices.
  • the device according to the invention with the characterizing features of claim 1 has the advantage that electrical energy is only required to ignite the fuel-air mixture in the pilot burner, which significantly reduces the requirements for the life of the ignition device and also the energy required to operate the device significantly reduces.
  • the energy supply to the pilot burner or to the combustion chamber can furthermore be increased as desired, so that the combustion device can easily be connected to different exhaust gas or. Solid particle rates can be adjusted.
  • the combustion device works with a high degree of efficiency, since it is not necessary to generate electrical energy for a continuously operated ignition device with corresponding losses in order to operate it.
  • the amount of the partial exhaust gas stream flowing into the combustion chamber can be limited and thereby avoided that the calibrated opening becomes clogged by solid particles during operation, since the temperature prevailing in the flame area continuously burns the calibrated opening freely .
  • an optimal swirling of the introduced fuel with the introduced air is achieved, so that a stable pilot flame can be held because of the uniform mixture composition, which burns through the overflow opening into the combustion chamber. Due to the air flow around the lateral surfaces of the pilot burner and also the cylindrical combustion chamber, the heat load on these walls is kept low and the partial exhaust gas flow, which is loaded with the solid particles, is already preheated by the combustion products. A refractory lining of the enveloping walls of the device according to the invention can be dispensed with in this way.
  • a stable ignition of the fuel introduced into the pilot burner with the air introduced is obtained via the incandescent body even in the case of pulsating operation, since the ignition does not occur solely through the continued burning of a flame once ignited, but also on the hot surface of the filament.
  • the incandescent body and the electrically operated ignition device according to claim 7 can be realized by an electrically heated glow plug, as is already available in other applications in the motor vehicle.
  • the ignition chamber is designed according to claim 8, wherein a distance between a central incandescent body and the entry of fuel on the wall of the pilot burner can be kept small and increased turbulence and improved mixture formation is achieved due to the increasing rotational speed in the narrow diameter part.
  • the energy supply to the device according to the invention is kept as small as necessary, wherein for the start of the entire device and as a safeguard for the safe operation of the device according to claim 12, a control of the electrically operated controlled by a flame monitoring device Ignition device is provided.
  • a simple possibility of metering and distributing the additional air to the combustion chamber is obtained on the one hand and to the pilot burner on the other. Due to the configuration according to claim 12, the energy requirement can also be reduced and the amount of additional fuel to be introduced can be reduced because of the increased efficiency of the device.
  • combustion aids can also be mixed in with the fuel, it being advantageous that the amount of fuel required for operating the device is very small and can be stored separately in a fuel tank. In this way, a removal device for fuel from the main fuel reservoir and a metering device for the catalytically active combustion aids to this fuel are dispensed with.
  • the exhaust gas discharged from an internal combustion engine (not shown further) to the exhaust gas collection system passes through a e.g. known from DE-C-3 424 196 electrostatic soot switch to a separating device in the form of a centrifugal separator, at one outlet exhaust gas exits, which is largely freed of soot and solid particles and at the other outlet a partial exhaust gas stream emerges, which is separated with soot and Solid particles are enriched.
  • This partial exhaust gas flow is fed via a first immersion pipe 1 to a combustion device 2, as shown in the figure.
  • the combustion device 2 is divided into a circular-cylindrical combustion chamber 4 and a pilot burner 5 adjoining it coaxially.
  • the combustion chamber 4 has a cylindrical jacket which is closed on one side by a first end face 6 and on the other side by a second end face 7 becomes.
  • This second end face is also the end face of the subsequent pilot burner 5, which in the example shown has a circular-cylindrical part 8, which directly adjoins the second end face 7 and has a truncated-cone-shaped part 9 that tapers thereafter. This is closed by an end wall 10.
  • the pilot burner 5 is connected to the combustion chamber 4 through an overflow opening 12 which is formed by a pipe socket 13 inserted coaxially to the combustion chamber axis 4 in the second end face 7.
  • the dip tube 1 projects from the first end face 6 coaxially into the interior of the combustion chamber 4 up to the vicinity of the overflow opening 12 and has a calibrated opening 15 at its mouth there. Furthermore, a second dip tube 17 protrudes from the first end face 6 into the combustion chamber 4. This second dip tube concentrically surrounds the first dip tube 1 with a much larger diameter and extends only over a small part of the immersion length of the first dip tube inside the combustion chamber 4. Outside the Combustion chamber 4, the first dip tube 1 breaks through the second dip tube 17 serving as an outlet tube, which leads via a heat exchanger 19 to the part of the exhaust system which discharges the cleaned exhaust gases. However, the outlet pipe can also lead directly to the ambient air if necessary with the addition of certain sound-absorbing agents.
  • the medium that is to be warmed up by the warm exhaust gas in the heat exchanger 19 is the additional air to be introduced into the combustion chamber and the pilot burner. This is fed from an air source 22 to the heat exchanger 19 via an air line 21 and is introduced from there into the combustion chamber 4 via a first additional air line 23 and introduced into the pilot burner 5 via a second additional air line 24.
  • An air metering device 26 is also provided in the air line 21, via which the additional air supplied to the combustion device is metered, preferably by means of delivery pressure control.
  • the first additional air line 23 also contains a pressure valve 27 which opens to the combustion chamber 4 when a set pressure is exceeded.
  • the first additional air line opens near the first end face 6 tangentially to the cylindrical wall of the combustion chamber 4.
  • the second auxiliary air line also opens tangentially to the circular-cylindrical part 8 of the pilot burner 5 near the second end face 7 into the pilot burner.
  • a pressure valve and / or a throttle 29 can optionally also be provided in this additional air line.
  • the air distribution between the first additional air line 23 and the second additional air line 24 can advantageously be set with these means.
  • the arrangement of a throttle 30 can also be used for this purpose in the first additional air line 23.
  • a glow body 32 is also provided, which can either be a so-called glow plug, as is known for starting a self-igniting internal combustion engine, or a simple glow body, which is thermally insulated from its attachment point and is heated by the heat generated during combustion in the pilot burner .
  • the glow plug is inserted coaxially to the axis of the pilot burner through the end wall 10 into the pilot burner and is supplied with electrical current by a control device 34.
  • an additional ignition device must be provided in the pilot burner, which is preferably arranged in the vicinity of the third end wall 10, where a fuel line 35 opens in the region of the frustoconical shell of the pilot burner part 9.
  • a fuel reservoir 36 contains a fuel metering device 37 through which the amount of additional fuel introduced into the pilot burner 5 via the fuel line 35 is metered.
  • the additional fuel is introduced at a low pressure level, so that a pressure booster, as is necessary, for example, in fuel injection, is superfluous.
  • the fuel inlet can enter the pilot burner via a plurality of openings in the manner of screen passage openings. For example, the entry point can be covered with a sieve 39. But other means of producing a large fuel dispensing surface such as sintered body can be used here.
  • the fuel metering device 37, the air metering device 26 and the ignition device 40 or the glow plug 32 are controlled with the aid of the control device.
  • the control device 34 is supplied with control values which provide information about the combustible solid particles occurring in the time unit. Such parameters can e.g. the speed and also the load under which the internal combustion engine is operated. However, there can also be signals about turbidity or similar parameters.
  • the control device 34 is supplied with a signal which provides information as to whether a flame is burning in the pilot burner or whether a temperature representative of the proper operation of the combustion device occurs at the outlet 17.
  • These probes can be provided simultaneously or alternatively and they can also be replaced by a timer for the start phase, during which the ignition device is put into operation.
  • a time control device is particularly advantageous when an electrically heated glow plug 32 is provided as an electrically controlled ignition device.
  • These pens require a certain heating phase before the mixture can be ignited on them.
  • the electrical heating of the glow plug is switched off by the control device 34 after the ignition phase and only switched on again when the flame monitoring device e.g. the sensor 41 or the sensor 42 reports an interruption of the combustion process in the pilot burner.
  • the flame monitoring sensor 41 can operate according to various principles. For example, optical sensors, resistance temperature sensors or ion current probes can be used.
  • the glow plug 32 is continuously heated by the fuel-air mixture burning in the pilot burner even when the electric heating is switched off, so that the mixture can ignite immediately on the glow plug if a flame breaks off.
  • another electrically operated ignition device e.g. can be designed as a spark ignition device, with an ignition electrode 40, which insulates into the wall of the pilot burner and ignites towards a ground electrode, the use of an additional incandescent body, which can be designed similarly to the glow plug 32, is advantageous.
  • Such an incandescent body would then likewise project coaxially to the axis of the pilot burner 5 from the third end wall 10 into the pilot burner and in this case advantageously be attached to the wall of the pilot burner in a heat-insulated manner.
  • This incandescent body then also heats up during operation on the burning fuel-air mixture and serves to stabilize the flame.
  • this incandescent body can also be designed as a heat pipe.
  • the fuel-air mixture is ignited within the pilot burner after the combustion device has been started up, it burns as a flame through the overflow opening 12 into the combustion chamber 4 and forms a flame zone 44 downstream of the overflow opening 12 with its calibrated opening 15 and burns together with the combustible solid parts introduced through this opening in the combustion chamber 4.
  • a circular baffle plate 45 to the dip tube 1 near the opening 15 it is achieved that the ignition zone 44 is limited locally (flame retardant effect), which leads to an increase in the temperature in the flame area and thus promotes the soot combustion and that further accelerates unburned soot particles radially outwards are so that they are caught by the external air flow and can reach the ignition zone 44 again.
  • first additional air line 23 additional air, which in turn moves in a rotational movement along the cylindrical wall of the combustion chamber 4 to the second end face.
  • the additional air is supplied, in particular after reversing, on the second end face 7 of the ignition zone 44, so that sufficient oxygen is available for the combustion of the solid particles heated in the ignition zone.
  • the combustion products of the burned solid particles and the remaining residual gases which are free of solid particles are then discharged coaxially to the dip tube 1 or to the axis of the combustion chamber 4 via the second dip tube 17. Because the first immersion tube 1 projects with its calibrated opening 15 directly into the ignition zone 44, there is always sufficient heat available which prevents the calibrated opening 15 from becoming clogged with soot particles or other solid particles.
  • the first immersion tube is heated by the combustion products over a long distance from its entry into the second immersion tube 17, whereby at the same time the supplied partial exhaust gas stream and the solid particles contained therein are preheated will.
  • This device thus fulfills a heat exchange device that works on the countercurrent principle.
  • a pilot flame is advantageously generated in the pilot burner, which burns into the combustion chamber 4 and ensures safe combustion of the combustible solid particles introduced.
  • the control device With the help of the control device, the amount of additional air required for this can be precisely controlled.
  • the pilot flame is maintained with a high level of operational safety by continuously introducing fuel and additional air into the pilot burner in a controlled ratio to one another.
  • flame monitoring and the electrical ignition device safe operation is guaranteed.
  • the combustion device can be operated with very little additional energy and can also be adapted to very different amounts of solid particles to be burned in the unit of time. Since only small amounts of fuel are required as additional energy, a separate fuel reservoir can also be used for this device, with catalytic combustion aids being added to improve the ignition properties of the fuel. If a separate fuel reservoir 36 is used, then a metering device and a reservoir for those substances which would otherwise have to be mixed with the fuel removed from the vehicle fuel reservoir are then dispensed with.
  • the pilot burner can also be designed as a circular-cylindrical chamber, but the shape shown in the drawing is preferable in terms of facilitating the ignition of the fuel-air mixture.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

An apparatus for the burning of solid particles, especially soot particles, separated from the exhaust gas from internal combustion engines has a rotationally symmetrical combustion chamber which coaxially adjoins an ignition burner connected with it by a flame transfer orifice. Fuel and air are metered to the ignition burner through an additional-air line and a fuel line and, as a prepared mixture, they are ignited in the ignition burner and enter the combustion chamber through a flame transfer orifice. In the combustion chamber an exhaust gas partial stream enriched with the solid particles is introduced, and, after the solid particles have been consumed together with the additional air put into the combustion chamber, the exhaust gas is then discharged again as cleaned exhaust together with the remaining combustion products through an outlet tube.

Description

Stand der TechnikState of the art

Die Erfindung geht von einer Einrichtung gemäß der Gattung des Hauptanspruchs aus. Bei einer solchen durch die DE-C-3 424 196 bekannten Einrichtung wird das von der Brennkraftmaschine kommende Abgas mit Hilfe einer elektrostatischen Rußweiche und eines nachgeschalteten Fliehkraftabscheiders in einen Abgasstrom aufgeteilt, der mit brennbaren Festkörperteilchen, insbesondere Ruß angereichert ist und in einem Abgasteilstrom, der weitgehend von solchen Teilchen befreit ist. Der mit brennbaren Festkörperteilchen angereicherte Abgasteilstrom wird bei der bekannten Einrichtung einer Brennkammer zugeleitet, vorzugsweise unter Beigabe eines Kraftstoff-Luft-Gemisches und beide Medien, rußbeladenes Abgas und Kraftstoft-Luft-Gemisch über einen elektrischen Heizkörper geleitet und dort verbrannt. Die Einleitung dieser Verbrennungsbestandteile erfolgt über ein gemeinsames Tauchrohr koaxial in die zylindrische Brennkammer, wobei der Heizkörper selbst innerhalb des Tauchrohres angeordnet ist. Die Verbrennungsprodukte werden dann stromabwärts des elektrischen Heizkörpers im Gegenstrom nahe der Einmündung des Tauchrohres aus der Brennkammer abgeführt.The invention is based on a device according to the preamble of the main claim. In such a device known from DE-C-3 424 196, the exhaust gas coming from the internal combustion engine is divided with the aid of an electrostatic soot switch and a downstream centrifugal separator into an exhaust gas stream which is enriched with combustible solid particles, in particular soot, and in a partial exhaust gas stream which is largely freed from such particles. The exhaust gas partial flow enriched with combustible solid particles is fed to a combustion chamber in the known device, preferably with the addition of a fuel-air mixture and both media, soot-laden exhaust gas and fuel-air mixture, passed through an electric heater and burned there. These combustion components are introduced coaxially into the cylindrical combustion chamber via a common immersion tube, the heating element itself being arranged within the immersion tube. The combustion products are then discharged downstream of the electric heater in countercurrent near the mouth of the dip tube from the combustion chamber.

Diese Einrichtung hat den Nachteil, daß für die Verbrennung der brennbaren Festkörperteilchen eine beträchtliche Menge elektrische Energie erforderlich ist verbunden mit einer aufwendigen Steuerung von Zusatzluft, Zusatzkraftstoff und Heizleistung des Heizelements, bei dem einerseits die notwendige Zündtemperatur eingehalten werden muß und andererseits eine Überhitzung wegen der Gefahr des Versagens dieser Heizeinrichtung vermieden werden muß. Dabei wird die Temperaturbelastung des Heizelementes in nachteiliger Weise auch durch die Menge des eingebrachten Kraftstoff-Luft-Gemisches und die Menge der eingebrachten, brennbaren Festkörperteilchen beeinflußt. Weiterhin wird alles, was das Tauchrohr verläßt, durch den Auslaß an der Stirnseite der Brennkammer in die Umgebung abgeführt. Sollte der in die Brennkammer eingeführte Ruß nicht vollständig verbrannt worden sein, so wird dieser durch einen aufwendigen zusätzlichen Filter nochmals ausgefiltert und die Restgase dem Auslaß zugeführt. Dieses zusätzliche Filter bedeutet einen zusätzlichen Aufwand mit der Gefahr, daß das Filter über die Dauer des Betriebs durch hohe Nachbrenntemperaturen geschädigt wird. Es ist dann auch nicht ausgeschlossen, daß unverbrannte Festkörperteilchen zum Auslaß gelangen. Zudem erhöht das Filter den Gegendruck auf der Abgasseite, was den Wirkungsgrad der vorgeschalteten Brenneinrichtungen verschlechtert.This device has the disadvantage that a considerable amount of electrical energy is required for the combustion of the combustible solid particles combined with a complex control of additional air, additional fuel and heating power of the heating element, in which on the one hand the necessary ignition temperature must be maintained and on the other hand overheating due to the danger failure of this heater must be avoided. The temperature load on the heating element is also adversely affected by the amount of fuel-air mixture introduced and the amount of combustible solid particles introduced. Furthermore, everything that leaves the immersion tube is discharged into the environment through the outlet at the end of the combustion chamber. If the soot introduced into the combustion chamber has not been completely burnt, it is filtered out again by an expensive additional filter and the residual gases are fed to the outlet. This additional filter means an additional effort with the risk that the filter will be damaged by high afterburning temperatures over the period of operation. It is then not excluded that unburned solid particles get to the outlet. In addition, the filter increases the back pressure on the exhaust side, which worsens the efficiency of the upstream combustion devices.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Einrichtung mit den kennzeichnenden Merkmalen des Anspruchs 1 hat demgegenüber den Vorteil, daß elektrische Energie nur zum Zünden des Kraftstoff-Luft-Gemisches im Zündbrenner erforderlich ist, was die Anforderungen an die Lebensdauer der Zündeinrichtung wesentlich herabsetzt und auch den Energiebedarf zum Betreiben der Einrichtung ganz erheblich mindert. Die Energiezufuhr zum Zündbrenner bzw. zur Brennkammer kann weiterhin beliebig gesteigert werden, so daß die Verbrenneinrichtung leicht an unterschiedliche Abgas-bzw. Festkörperteilchenraten angepaßt werden kann. Die Verbrenneinrichtung arbeitet mit hohem Wirkungsgrad, da zu ihrem Betreiben nicht erst elektrische Energie für eine dauernd betriebene Zündeinrichtung mit entsprechenden Verlusten erzeugt werden muß.The device according to the invention with the characterizing features of claim 1 has the advantage that electrical energy is only required to ignite the fuel-air mixture in the pilot burner, which significantly reduces the requirements for the life of the ignition device and also the energy required to operate the device significantly reduces. The energy supply to the pilot burner or to the combustion chamber can furthermore be increased as desired, so that the combustion device can easily be connected to different exhaust gas or. Solid particle rates can be adjusted. The combustion device works with a high degree of efficiency, since it is not necessary to generate electrical energy for a continuously operated ignition device with corresponding losses in order to operate it.

Durch eine vorteilhafte Weiterbildung gemäß Anspruch 2 kann die Menge des in die Brennkammer einströmenden Abgasteilstromes begrenzt werden und dabei vermieden werden, daß sich die kalibrierte Öffnung im Laufe des Betriebs durch sich absetzende Festkörperteilchen zusetzt, da die im Flammbereich herrschende Temperatur die kalibrierte Öffnung laufend frei brennt.Through an advantageous development according to claim 2, the amount of the partial exhaust gas stream flowing into the combustion chamber can be limited and thereby avoided that the calibrated opening becomes clogged by solid particles during operation, since the temperature prevailing in the flame area continuously burns the calibrated opening freely .

Durch eine zusätzliche Weiterbildung der Erfindung gemäß Anspruch 4 wird eine optimale Verwirbelung von eingebrachtem Kraftstoff mit eingebrachter Luft erreicht, so daß wegen der gleichmäßigen Gemischzusammensetzung eine stabile Pilotflamme gehalten werden kann, die über die Überströmöffnung in die Brennkammer hineinbrennt. Durch die Luftumströmung der Mantelflächen des Zündbrenners und auch der zylindrischen Brennkammer wird die Wärmebelastung dieser Wände gering gehalten und dabei wird der Abgasteilstrom, der mit den Festkörperteilchen beladen ist, bereits von den Verbrennungsprodukten vorgewärmt. Eine feuerfeste Auskleidung der ummantelnden Wände der erfindungsgemäßen Einrichtung kann auf diese Weise entfallen. In besonders vorteilhafter Weise gemäß Anspruch 5 erhält man über den Glühkörper auch bei pulsierendem Betrieb eine stabile Entflammung des in den Zündbrenner eingebrachten Kraftstoffs mit der eingebrachten Luft, da die Entflammung nicht allein durch das Weiterbrennen einer einmal gezündeten Flamme erfolgt, sondern auch an der heißen Oberfläche des Glühkörpers.By an additional development of the invention according to claim 4, an optimal swirling of the introduced fuel with the introduced air is achieved, so that a stable pilot flame can be held because of the uniform mixture composition, which burns through the overflow opening into the combustion chamber. Due to the air flow around the lateral surfaces of the pilot burner and also the cylindrical combustion chamber, the heat load on these walls is kept low and the partial exhaust gas flow, which is loaded with the solid particles, is already preheated by the combustion products. A refractory lining of the enveloping walls of the device according to the invention can be dispensed with in this way. In a particularly advantageous manner, a stable ignition of the fuel introduced into the pilot burner with the air introduced is obtained via the incandescent body even in the case of pulsating operation, since the ignition does not occur solely through the continued burning of a flame once ignited, but also on the hot surface of the filament.

In vorteilhafter Weise läßt sich Glühkörper und elektrisch betriebene Zündeinrichtung gemäß Anspruch 7 durch einen elektrisch beheizten Glühstift verwirklichen, wie er auch bei anderer Anwendung beim Kraftfahrzeug bereits zur Verfügung steht. In vorteilhafter Weiterbildung ist die Zündkammer gemäß Anspruch 8 ausgebildet, wobei ein Abstand zwichen einem zentralen Glühkörper und dem Eintritt von Kraftstoff an der Wand des Zündbrenners gering gehalten werden kann und eine erhöhte Turbulenz und verbesserte Gemischbildung erreicht wird aufgrund der im engen Durchmesserteil zunehmenden Rotationsgeschwindigkeit.In an advantageous manner, the incandescent body and the electrically operated ignition device according to claim 7 can be realized by an electrically heated glow plug, as is already available in other applications in the motor vehicle. In an advantageous development, the ignition chamber is designed according to claim 8, wherein a distance between a central incandescent body and the entry of fuel on the wall of the pilot burner can be kept small and increased turbulence and improved mixture formation is achieved due to the increasing rotational speed in the narrow diameter part.

In vorteilhafter Weise ist gemäß Anspruch 10 gewährleistet, daß die Energiezufuhrzu der erfindungsgemäßen Einrichtung so klein wie nötig gehalten wird, wobei für den Start der ganzen Einrichtung und als Sicherung für den sicheren Betrieb der Einrichtung gemäß Anspruch 12 eine von einer Flammüberwachungseinrichtung gesteuerte Steuerung der elektrisch betriebenen Zündeinrichtung vorgesehen ist. Mit der Ausgestaltung gemäß Anspruch 13 erhält man eine einfache Möglichkeit der Dosierung und Verteilung der Zusatzluft zu der Brennkammer einerseits und zum Zündbrenner andererseits. Durch die Ausgestaltung gemäß Anspruch 12 kann weiterhin der Energiebedarf gesenkt und die Menge des einzubringenden Zusatzkraftstoffes reduziert werden wegen des damit erhöhten Wirkungsgrades der Einrichtung. Zur stabilen Flammbildung können ferner auch gemäß Anspruch 15 Abbrennhilfsstoffe dem Kraftstoff zugemischt werden, wobei es von Vorteil ist, daß die für den Betrieb der Einrichtung notwendige Kraftstoffmenge sehr gering ist und gesondert in einem Kraftstoffvorratsbehälter gespeichert werden kann. Auf diese Weise entfällt eine Entnahmevorrichtung von Kraftstoff aus dem Hauptkraftstoffvorratsbehälter und eine Dosiervorrichtung von den katalytisch wirksamen Abbrennhilfsstoffen zu diesem Kraftstoff.Advantageously, according to claim 10 it is ensured that the energy supply to the device according to the invention is kept as small as necessary, wherein for the start of the entire device and as a safeguard for the safe operation of the device according to claim 12, a control of the electrically operated controlled by a flame monitoring device Ignition device is provided. With the configuration according to claim 13, a simple possibility of metering and distributing the additional air to the combustion chamber is obtained on the one hand and to the pilot burner on the other. Due to the configuration according to claim 12, the energy requirement can also be reduced and the amount of additional fuel to be introduced can be reduced because of the increased efficiency of the device. For stable flame formation, combustion aids can also be mixed in with the fuel, it being advantageous that the amount of fuel required for operating the device is very small and can be stored separately in a fuel tank. In this way, a removal device for fuel from the main fuel reservoir and a metering device for the catalytically active combustion aids to this fuel are dispensed with.

Zeichnungdrawing

Die Erfindung wird anhand der Zeichnung dargestellt und im nachfolgenden näher beschrieben.The invention is illustrated by the drawing and described in more detail below.

Beschreibung des AusführungsbeispielsDescription of the embodiment

Das von einer nicht weiter dargestellten Brennkraftmaschine an das Abgassammelsystem abgegebene Abgas gelangt über eine z.B. durch die DE-C-3 424 196 bekannte elektrostatische Rußweiche zu einer Trenneinrichtung in Form eines Fliehkraftabscheiders, an dessen einem Ausgang Abgas austritt, das weitgehendst von Ruß und Festkörperteilchen befreit ist und an dessen anderen Ausgang ein Abgasteilstrom austritt, der mit ausgeschiedenen Ruß-und Festkörperteilchen angereichert ist. Dieser Abgasteilstrom wird über ein erstes Tauchrohr 1 einer Verbrennungseinrichtung 2 zugeführt, wie sie in der Figur dargestellt ist.The exhaust gas discharged from an internal combustion engine (not shown further) to the exhaust gas collection system passes through a e.g. known from DE-C-3 424 196 electrostatic soot switch to a separating device in the form of a centrifugal separator, at one outlet exhaust gas exits, which is largely freed of soot and solid particles and at the other outlet a partial exhaust gas stream emerges, which is separated with soot and Solid particles are enriched. This partial exhaust gas flow is fed via a first immersion pipe 1 to a combustion device 2, as shown in the figure.

Die Verbrennungseinrichtung 2 teilt sich auf in eine kreiszylindrische Brennkammer 4 und einem sich dieser koaxial anschließenden Zündbrenner 5. Die Brennkammer 4 weist einen zylindrischen Mantel auf, der auf der einen Seite durch eine erste Stirnseite 6 und auf der anderen Seite von einer zweiten Stirnseite 7 verschlossen wird. Diese zweite Stirnseite ist zugleich Stirnseite des sich anschließenden Zündbrenners 5, der im ausgeführten Beispiel einen kreiszylindrischen Teil 8 aufweist, der sich unmittelbar an die zweite Stirnseite 7 anschließt und einen sich danach verjüngenden, kegelstumpfförmigen Teil 9 aufweist. Dieser wird von einer Stirnwand 10 verschlossen. Der Zündbrenner 5 ist mit der Brennkammer 4 durch eine Überströmöffnung 12 verbunden, die durch einen koaxial zur Brennkammerachse 4 in die zweite Stirnseite 7 eingesetzten Rohrstutzen 13 gebildet wird.The combustion device 2 is divided into a circular-cylindrical combustion chamber 4 and a pilot burner 5 adjoining it coaxially. The combustion chamber 4 has a cylindrical jacket which is closed on one side by a first end face 6 and on the other side by a second end face 7 becomes. This second end face is also the end face of the subsequent pilot burner 5, which in the example shown has a circular-cylindrical part 8, which directly adjoins the second end face 7 and has a truncated-cone-shaped part 9 that tapers thereafter. This is closed by an end wall 10. The pilot burner 5 is connected to the combustion chamber 4 through an overflow opening 12 which is formed by a pipe socket 13 inserted coaxially to the combustion chamber axis 4 in the second end face 7.

Das Tauchrohr 1 ragt von der ersten Stirnseite 6 her koaxial in das Innere der Brennkammer 4 bis in die Nähe der Überströmöffnung 12 und weist an seiner dort befindlichen Mündung eine kalibrierte Öffnung 15 auf. Weiterhin ragt von der ersten Stirnseite 6 her ein zweites Tauchrohr 17 in die Brennkammer 4. Dieses zweite Tauchrohr umgibt mit wesentlich größerem Durchmesser das erste Tauchrohr 1 konzentrisch und erstreckt sich nur über einen geringen Teil der Eintauchlänge des ersten Tauchrohres innerhalb der Brennkammer 4. Außerhalb der Brennkammer 4 durchbricht das erste Tauchrohr 1 das als Auslaßrohr dienende zweite Tauchrohr 17, das über einen Wärmetauscher 19 zu dem Teil des Abgassystems führt, das die gereinigten Abgase ableitet. Das Auslaßrohr kann aber auch direkt gegebenenfalls unter Zuschaltung gewisser schalldämmender Mittel zur Umgebungsluft führen.The dip tube 1 projects from the first end face 6 coaxially into the interior of the combustion chamber 4 up to the vicinity of the overflow opening 12 and has a calibrated opening 15 at its mouth there. Furthermore, a second dip tube 17 protrudes from the first end face 6 into the combustion chamber 4. This second dip tube concentrically surrounds the first dip tube 1 with a much larger diameter and extends only over a small part of the immersion length of the first dip tube inside the combustion chamber 4. Outside the Combustion chamber 4, the first dip tube 1 breaks through the second dip tube 17 serving as an outlet tube, which leads via a heat exchanger 19 to the part of the exhaust system which discharges the cleaned exhaust gases. However, the outlet pipe can also lead directly to the ambient air if necessary with the addition of certain sound-absorbing agents.

Das Medium, das im Wärmetauscher 19 von dem warmen Abgas aufgewärmt werden soll, ist die in die Brennkammer und den Zündbrenner einzubringende Zusatzluft. Diese wird von einer Luftquelle 22 über eine Luftleitung 21 dem Wärmetauscher 19 zugeführt und wird von dort über eine erste Zusatzluftleitung 23 in die Brennkammer 4 eingeleitet und über eine zweite Zusatzluftleitung 24 in den Zündbrenner 5 eingeleitet. In der Luftleitung 21 ist ferner eine Luftzumeßeinrichtung 26 vorgesehen, über welche vorzugsweise mittels Förderdrucksteuerung die der Verbrennungseinrichtung zugeführte Zusatzluft dosiert wird. Die erste Zusatzluftleitung 23 enthält ferner ein Druckventil 27, das bei Überschreitung eines eingestellten Drucks zur Brennkammer 4 hin öffnet. Die erste Zusatzluftleitung mündet dabei nahe der ersten Stirnseite 6 tangential zur zylindrischen Wand der Brennkammer 4 in diese ein. Auch die zweite Zusatzluftleitung mündet tangential zum kreiszylindrischen Teil 8 des Zündbrenners 5 nahe der zweiten Stirnseite 7 in den Zündbrenner ein. Auch in dieser Zusatzluftleitung kann gegebenenfalls ein Druckventil und/oder eine Drossel 29 vorgesehen werden. Mit diesen Mitteln läßt sich vorteilhaft die Luftverteilung zwischen erster Zusatzluftleitung 23 und zweiter Zusatzluftleitung 24 einstellen. Auch in der ersten Zusatzluftleitung 23 ist die Anordnung einer Drossel 30 zu diesem Zwecke anwendbar.The medium that is to be warmed up by the warm exhaust gas in the heat exchanger 19 is the additional air to be introduced into the combustion chamber and the pilot burner. This is fed from an air source 22 to the heat exchanger 19 via an air line 21 and is introduced from there into the combustion chamber 4 via a first additional air line 23 and introduced into the pilot burner 5 via a second additional air line 24. An air metering device 26 is also provided in the air line 21, via which the additional air supplied to the combustion device is metered, preferably by means of delivery pressure control. The first additional air line 23 also contains a pressure valve 27 which opens to the combustion chamber 4 when a set pressure is exceeded. The first additional air line opens near the first end face 6 tangentially to the cylindrical wall of the combustion chamber 4. The second auxiliary air line also opens tangentially to the circular-cylindrical part 8 of the pilot burner 5 near the second end face 7 into the pilot burner. A pressure valve and / or a throttle 29 can optionally also be provided in this additional air line. The air distribution between the first additional air line 23 and the second additional air line 24 can advantageously be set with these means. The arrangement of a throttle 30 can also be used for this purpose in the first additional air line 23.

Im Zündbrenner ist weiterhin ein Glühkörper 32 vorgesehen, der entweder eine sogenannte Glühstiftkerze sein kann, wie sie für die Starthilfe von selbstzündenden Brennkraftmaschinen bekannt sind oder ein einfacher, gegenüber seinem Befestigungspunkt wärmeisolierter Glühkörper sein, der von der bei der Verbrennung im Zündbrenner entstehenden Wärme beheizt wird. Im erstgenannten Fall wird der Glühstift koaxial zur Achse des Zündbrenners durch die Stirnwand 10 in den Zündbrenner eingeführt und von einer Steuereinrichtung 34 mit elektrischem Strom vorsorgt. Wird statt des Glühstiftes ein ähnlich gestalteter Glühkörper verwendet, so muß in dem Zündbrenner eine zusätzliche Zündeinrichtung vorgesehen werden, die vorzugsweise in der Nähe der dritten Stirnwand 10 angeordnet ist, wo im Bereich des kegelstumpfförmigen Mantels des Zündbrennerteils 9 eine Kraftstoffleitung 35 einmündet. Diese führt von einem Kraftstoffvorratsbehälter 36 ab und enthält eine Kraftstoffzumeßeinrichtung 37, durch die die Menge des über die Kraftstoffleitung 35 in den Zündbrenner 5 eingeführten Zusatzkraftstoffs dosiert wird. Der Zusatzkraftstoff wird dabei mit Niederdruckniveau eingeführt, so daß eine Druckerhöhungseinrichtung, wie sie z.B. bei Kraftstoffeinspritzung notwendig ist, überflüssig ist. Der Kraftstoffeintritt kann dabei über mehrere Öffnungen in der Art von Siebdurchtrittsöffnungen in den Zündbrenner eintreten. Beispielsweise kann die Eintrittsstelle mit einem Sieb 39 verkleidet werden. Aber auch andere Einrichtungen zur Erzeugung einer großen Kraftstoffabgabefläche, wie z.B. Sinterkörper sind hier verwendbar.In the pilot burner, a glow body 32 is also provided, which can either be a so-called glow plug, as is known for starting a self-igniting internal combustion engine, or a simple glow body, which is thermally insulated from its attachment point and is heated by the heat generated during combustion in the pilot burner . In the former case, the glow plug is inserted coaxially to the axis of the pilot burner through the end wall 10 into the pilot burner and is supplied with electrical current by a control device 34. If a similarly designed incandescent body is used instead of the glow plug, an additional ignition device must be provided in the pilot burner, which is preferably arranged in the vicinity of the third end wall 10, where a fuel line 35 opens in the region of the frustoconical shell of the pilot burner part 9. This leads from a fuel reservoir 36 and contains a fuel metering device 37 through which the amount of additional fuel introduced into the pilot burner 5 via the fuel line 35 is metered. The additional fuel is introduced at a low pressure level, so that a pressure booster, as is necessary, for example, in fuel injection, is superfluous. The fuel inlet can enter the pilot burner via a plurality of openings in the manner of screen passage openings. For example, the entry point can be covered with a sieve 39. But other means of producing a large fuel dispensing surface such as sintered body can be used here.

Mit Hilfe der Steuereinrichtung werden die Kraftstoffzumeßeinrichtung 37, die Luftzumeßeinrichtung 26 und die Zündeinrichtung 40 bzw. der Glühstift 32 gesteuert. Als Führungsparameter für die Steuerung von Luft und Kraftstoff werden der Steuereinrichtung 34 Steuerwerte zugeführt, die eine Aussage über die in der Zeiteinheit anfallenden brennbaren Festkörperteilchen geben. Solche Parameter können z.B. die Drehzahl und auch die Last sein, unter der die Brennkraftmaschine betrieben wird. Es können aber auch Signale über Abgastrübung oder ähnlicher Parameter sein. Als weiterer Steuerwert wird der Steuereinrichtung 34 noch ein Signal zugeleitet, das Aussage darüber abgibt, ob im Zündbrenner eine Flamme brennt bzw. ob am Auslaß 17 eine für den ordentlichen Betrieb der Verbrennungseinrichtung repräsentative Temperatur auftritt.The fuel metering device 37, the air metering device 26 and the ignition device 40 or the glow plug 32 are controlled with the aid of the control device. As control parameters for the control of air and fuel, the control device 34 is supplied with control values which provide information about the combustible solid particles occurring in the time unit. Such parameters can e.g. the speed and also the load under which the internal combustion engine is operated. However, there can also be signals about turbidity or similar parameters. As a further control value, the control device 34 is supplied with a signal which provides information as to whether a flame is burning in the pilot burner or whether a temperature representative of the proper operation of the combustion device occurs at the outlet 17.

Wird die Verbrennungseinrichtung in Betrieb genommen, so wird einerseits Zusatzluft über die Zusatzluftleitungen 23 und 24 in dosierter Menge in die Verbrennungseinrichtung eingebracht und andererseits eine dieser Luft entsprechende Kraftstoffmenge über die Kraftstoffleitung 35. Die über die Zusatzluftleitung 24 einströmende Luft erzeugt eine rotierende Luftbewegung innerhalb des Zündbrenners 5, deren Winkel-Geschwindigkeit zum sich konisch verjüngenden Teil 9 hin zunimmt. In diese schnell drehende Luftmenge wird der Kraftstoff über das Sieb 39 eingebracht und schnell zu einem gleichmäßigen Verbrennungsgemisch aus Zusatzluft und Kraftstoff aufbereitet. Bei Beginn der Betriebsaufnahme ist eine Zündung dieses Gemisches erforderlich, was mit Hilfe eines Flammüberwachungssensors 41 im Zündbereich erfaßt werden kann oder mit Hilfe einer Temperatursonde 42 erfaßt werden kann, die in den Auslaß 17 stromaufwärts des Wärmetauschers 19 eingesetzt ist. Diese Sonden können gleichzeitig oder alternativ vorgesehen werden und sie können auch für die Startphase durch ein Zeitglied ersetzt werden, während dessen Standzeit die Zündeinrichtung in Betrieb genommen wird. Eine solche Zeitsteuereinrichtung ist insbesondere dann vorteilhaft, wenn ein elektrisch beheizter Glühstift 32 als elektrische gesteuerte Zündeinrichtung vorgesehen ist. Diese Stifte benötigen eine gewisse Aufheizphase, bevor das Gemisch an ihnen gezündet werden kann. Nach dem Start und einer einmal erfolgten Entflammung des aufbereiteten Kraftstoff-Luft-Gemisch im Zündbrenner brennt die Flamme laufend fort und kann dann in Ergänzung zu dem Zeitglied mit Hilfe des Flammüberwachungssensors 41 weiterhin überwacht werden. Die elektrische Beheizung des Glühstiftes wird von der Steuereinrichtung 34 nach der Entflammungsphase abgeschaltet und erst dann wiedereingeschaltet, wenn die Flammüberwachungseinrichtung z.B. der Sensor 41 oder der Sensor 42 eine Unterbrechung des Verbrennungsvorgangs im Zündbrenner meldet. Der Flammüberwachungsensor 41 kann nach verschiedenen Prinzipien arbeiten. Es können z.B. optische Sensoren, Widerstandstemperatursensoren oder lonenstromsonden verwendet werden.When the combustion device is put into operation, on the one hand additional air is introduced into the combustion device in a metered amount via the additional air lines 23 and 24 and on the other hand an amount of fuel corresponding to this air is introduced via the fuel line 35. The air flowing in via the additional air line 24 produces a rotating air movement within the pilot burner 5, whose angular velocity increases towards the conically tapering part 9. The fuel is introduced into this rapidly rotating amount of air via the sieve 39 and is quickly processed into a uniform combustion mixture of additional air and fuel. At the start of operation, ignition of this mixture is necessary, which can be detected with the aid of a flame monitoring sensor 41 in the ignition area or can be detected with the aid of a temperature probe 42 which is inserted into the outlet 17 upstream of the heat exchanger 19. These probes can be provided simultaneously or alternatively and they can also be replaced by a timer for the start phase, during which the ignition device is put into operation. Such a time control device is particularly advantageous when an electrically heated glow plug 32 is provided as an electrically controlled ignition device. These pens require a certain heating phase before the mixture can be ignited on them. After the start and once the ignition of the processed fuel-air mixture in the pilot burner has taken place, the flame continues to burn and can then continue to be monitored in addition to the timer with the aid of the flame monitoring sensor 41. The electrical heating of the glow plug is switched off by the control device 34 after the ignition phase and only switched on again when the flame monitoring device e.g. the sensor 41 or the sensor 42 reports an interruption of the combustion process in the pilot burner. The flame monitoring sensor 41 can operate according to various principles. For example, optical sensors, resistance temperature sensors or ion current probes can be used.

Während des Betriebs wird der Glühstift 32 auch bei ausgeschalteter elektrischer Beheizung laufend durch das im Zündbrenner verbrennende Kraftstoff-Luft-Gemisch erwärmt, so daß bei einem Flammenabriß sich das Gemisch sogleich am Glühstift entzünden kann. Wird statt eines elektrisch beheizten Glühstiftes jedoch eine andere elektrisch betriebene Zündeinrichtung verwendet, die z.B. als Funkenzündeinrichtung ausgeführt sein kann, mit einer Zündelektrode 40, die isoliert in die Wand des Zündbrenners eingesetzt zu einer Masseelektrode hin zündet, so ist die Verwendung eines zusätzlichen Glühkörpers von Vorteil, der ähnlich ausgeführt sein kann wie der Glühstift 32. Ein solcher Glühkörper würde dann ebenfalls koaxial zur Achse des Zündbrenners 5 von der dritten Stirnwand 10 her in den Zündbrenner ragen und dabei vorteilhafterweise gegenüber der Wand des Zündbrenners wärmeisoliert angebracht sein. Dieser Glühkörper heizt sich dann während des Betriebs ebenfalls an dem brennenden Kraftstoff-Luft-Gemisch auf und dient zur Flammenstabilisierung. Zur guten Wärmeverteilung kann dieser Glühkörper auch als Wärmerohr ausgeführt sein.During operation, the glow plug 32 is continuously heated by the fuel-air mixture burning in the pilot burner even when the electric heating is switched off, so that the mixture can ignite immediately on the glow plug if a flame breaks off. If, instead of an electrically heated glow plug, another electrically operated ignition device is used, e.g. can be designed as a spark ignition device, with an ignition electrode 40, which insulates into the wall of the pilot burner and ignites towards a ground electrode, the use of an additional incandescent body, which can be designed similarly to the glow plug 32, is advantageous. Such an incandescent body would then likewise project coaxially to the axis of the pilot burner 5 from the third end wall 10 into the pilot burner and in this case advantageously be attached to the wall of the pilot burner in a heat-insulated manner. This incandescent body then also heats up during operation on the burning fuel-air mixture and serves to stabilize the flame. For good heat distribution, this incandescent body can also be designed as a heat pipe.

Wenn also nach Inbetriebnahme der Verbrennungseinrichtung das Kraftstoff-Luft-Gemisch innerhalb des Zündbrenners gezündet ist, brennt dieses als Flamme durch die Überströmöffnung 12 hindurch in die Brennkammer 4 hinein und bildet stromabwärts der Überströmöffnung 12 eine Entflammungszone 44. Diese umfaßt das Ende des ersten Tauchrohres 1 mit seiner kalibrierten Öffnung 15 und brennt mit den über diese Öffnung eingebrachten brennbaren Festkörperteilen zusammen in der Brennkammer 4 ab. Durch Anbringung einer kreisförmigen Prallplatte 45 am Tauchrohr 1 nahe der Öffnung 15 wird erreicht, daß die Entflammungszone 44 örtlich begrenzt wird (Flammhaltereffekt), was zu einer Anhebung der Temperatur im Flammbereich führt und damit den Rußabbrand fördert und daß weiterhin unverbrannte Rußteilchen radial nach außen beschleunigt werden, so daß sie von der äußeren Luftströmung erfaßt werden und nochmals in die Entflammungszone 44 gelangen können. Auch diese wird ja über die erste Zusatzluftleitung 23 Zusatzluft eingebracht, die sich wiederum in Rotationsbewegung entlang der zylindrischen Wand der Brennkammer 4 zur zweiten Stirnseite hin bewegt. Die Zusatzluft wird insbesondere nach Umkehr an der zweiten Stirnseite 7 der Entflammungszone 44 zugeführt, so daß ausreichend Sauerstoff zur Verbrennung der in der Entflammungszone aufgeheizten Festkörperteilchen zur Verfügung steht. Die Verbrennungsprodukte der verbrannten Festkörperteilchen und die übrigen Restgase, die frei von Festkörperteilchen sind, werden danach koaxial zum Tauchrohr 1 bzw. zur Achse der Brennkammer 4 über das zweite Tauchrohr 17 abgeleitet. Dadurch, daß das erste Tauchrohr 1 mit seiner kalibrierten Öffnung 15 direkt in die Entflammungszone 44 ragt, steht immer ausreichend Wärme zur Verfügung, die verhindert, daß sich die kalibrierte Öffnung 15 eventuell mit Rußteilchen oder anderen Festkörperteilchen zusetzt. Weiterhin wird das erste Tauchrohr über eine lange Strecke von seinem Eintritt in das zweiten Tauchrohr 17 an von den Verbrennungsprodukten erwärmt, wodurch zugleich auch der zugeführte Abgasteilstrom und die darin enthaltenen Festkörperteilchen vorgewärmt werden. Diese Einrichtung erfüllt somit eine Wärmetauscheinrichtung, die im Gegenstromprinzip arbeitet.If the fuel-air mixture is ignited within the pilot burner after the combustion device has been started up, it burns as a flame through the overflow opening 12 into the combustion chamber 4 and forms a flame zone 44 downstream of the overflow opening 12 with its calibrated opening 15 and burns together with the combustible solid parts introduced through this opening in the combustion chamber 4. By attaching a circular baffle plate 45 to the dip tube 1 near the opening 15 it is achieved that the ignition zone 44 is limited locally (flame retardant effect), which leads to an increase in the temperature in the flame area and thus promotes the soot combustion and that further accelerates unburned soot particles radially outwards are so that they are caught by the external air flow and can reach the ignition zone 44 again. This is also introduced via the first additional air line 23 additional air, which in turn moves in a rotational movement along the cylindrical wall of the combustion chamber 4 to the second end face. The additional air is supplied, in particular after reversing, on the second end face 7 of the ignition zone 44, so that sufficient oxygen is available for the combustion of the solid particles heated in the ignition zone. The combustion products of the burned solid particles and the remaining residual gases which are free of solid particles are then discharged coaxially to the dip tube 1 or to the axis of the combustion chamber 4 via the second dip tube 17. Because the first immersion tube 1 projects with its calibrated opening 15 directly into the ignition zone 44, there is always sufficient heat available which prevents the calibrated opening 15 from becoming clogged with soot particles or other solid particles. Furthermore, the first immersion tube is heated by the combustion products over a long distance from its entry into the second immersion tube 17, whereby at the same time the supplied partial exhaust gas stream and the solid particles contained therein are preheated will. This device thus fulfills a heat exchange device that works on the countercurrent principle.

Mit dieser Einrichtung wird in vorteilhafter Weise in dem Zündbrenner eine Pilotflamme erzeugt, die in die Brennkammer 4 hineinbrennt und für eine sichere Verbrennung der eingebrachten, brennbaren Festkörperteilchen sorgt. Mit Hilfe der Steuereinrichtung läßt sich die dafür notwendige Zusatzluftmenge exakt steuern. Es wird weiterhin mit hoher Betriebssicherheit die Pilotflamme aufrechterhalten, indem ununterbrochen Kraftstoff und Zusatzluft im gesteuerten Verhältnis zueinander in den Zündbrenner eingeführt werden. Mit Hilfe der Flammüberwachung und der elektrischen Zündeinrichtung wird ein sicherer Betrieb gewährleistet. Dabei ist die Verbrennungseinrichtung mit sehr geringer Zusatzenergie betreibbar und kann auch auf sehr unterschiedliche Mengen an in der Zeiteinheit zu verbrennenden Festkörperteilchen angepaßt werden. Da nur geringe Kraftstoffmengen als Zusatzenergie notwendig sind, kann für diese Einrichtung auch ein gesonderter Kraftstoffvorratsbehälter verwendet werden, wobei zur Verbesserung der Entflammungseigenschaften des Kraftstoff diesem katalytisch wirkende Abbrennhilfsstoffe zugemischt werden. Wird ein gesonderter Kraftstoffvorratsbehälter 36 verwendet, entfallen dann eine Dosiereinrichtung und ein Vorratsbehälter für solche Stoffe, die im anderen Falle dem vom Fahrzeugkraftstoffvorratsbehälter entnommenen Kraftstoff zugemischt werden müßten.With this device, a pilot flame is advantageously generated in the pilot burner, which burns into the combustion chamber 4 and ensures safe combustion of the combustible solid particles introduced. With the help of the control device, the amount of additional air required for this can be precisely controlled. The pilot flame is maintained with a high level of operational safety by continuously introducing fuel and additional air into the pilot burner in a controlled ratio to one another. With the help of flame monitoring and the electrical ignition device, safe operation is guaranteed. The combustion device can be operated with very little additional energy and can also be adapted to very different amounts of solid particles to be burned in the unit of time. Since only small amounts of fuel are required as additional energy, a separate fuel reservoir can also be used for this device, with catalytic combustion aids being added to improve the ignition properties of the fuel. If a separate fuel reservoir 36 is used, then a metering device and a reservoir for those substances which would otherwise have to be mixed with the fuel removed from the vehicle fuel reservoir are then dispensed with.

Grundsätzlich läßt sich der Zündbrenner auch als kreiszylindrische Kammer ausgestalten, wobei jedoch die in der Zeichnung gezeigte Form bezüglich der Erleichterung der Entflammung des Kraftstoff-Luft-Gemisches vorzuziehen ist.Basically, the pilot burner can also be designed as a circular-cylindrical chamber, but the shape shown in the drawing is preferable in terms of facilitating the ignition of the fuel-air mixture.

Claims (15)

  1. Device for the removal of combustible solid particles from exhaust gases of combustion engines, with a combustion device (2), which has a circular- cylindrical combustion chamber (4), into which, on a first end face (6), a tube (1 conducting a stream of exhaust gases of the combustion engine charged with the combustible solid particles, opens out coaxially of the (sic) axis of the combustion chamber, which furthermore has an inlet (23, 12) for additional air and additional fuel and an outlet (17) for the combustion products of additional air, additional fuel and combustible solid particles and for exhaust gas furthermore contains (sic) with an inflammation zone (44) downstream of the outlet (15) of the solid particles from the tube (1), characterized in that at least one additional-air line opens out into the combustion chamber (4) tangentially to the cylindrical jacket of the combustion chamber, close to the first end face (6), in that the tube (1), conducting the exhaust gas stream with the combustible solid particles, is a first immersion tube which freely enters the combustion chamber (4) coaxially to the axis of the combustion chamber and is surrounded over a part of its length beginning at the first end face (6) by a second immersion tube (17), which forms the outlet for the combustion products and leads away through the first end face (6) from the combustion chamber (4), and in that the additional air and the additional fuel is introduced via an overflow opening (12), provided in the second end face (7) of the combustion chamber (4) and placed coaxially to the first immersion tube, as a combustible mixture, which is formed in a pilot burner (5) adjoining the overflow opening (12) upstream.
  2. 2. Device according to Claim 1, characterized in that the outlet of the first immersion tube (1) is designed as calibrated opening (15) and protrudes into inflammation zone (44) in the region at the overflow opening (12).
  3. 3. Device according to Claim 2, characterized in that the immersion tube (1) has a baffle plate (45) close to the outlet at the calibrated opening (15).
  4. 4. Device according to Claim 2 or 3, characterized in that the pilot burner is a rotationally symmetrical chamber, at the one end (7) of which neighbouring the overflow opening (12), an additional-air line (24) opens out tangentially to the jacket of the chamber and at the other end of which a fuel line (35) opens out, which leads from a fuel metering device (37), and in that an ignition device (32, 40) is provided in the region of the mouth of the fuel line (35) into the pilot burner.
  5. 5. Device according to Claim 4, characterized in that the ignition device is an electrically operated ignition device.
  6. 6. Device according to Claim 5, characterized in that a glow element (32), heated by combustion products, is provided inside the pilot burner.
  7. 7. Device according to Claim 6, characterized in that the glow element and the electrically operated ignition device are formed by an electrically heatable glow pin (32).
  8. 8. Device according to one of Claims 5 to 7, characterized in that the pilot burner (5) is formed from a cylindrical part (8) and a frustoconical part (9), tapering towards the mouth of the fuel line (35).
  9. 9. Device according to one of Claims 5 to 8, characterized in that the additional-air line (23) opening out into the combustion chamber (4) and the additional-air line (24) opening out into the pilot burner (5) are connected via an air metering device (26) to an additional-air source (22).
  10. 10. Device according to Claim 9, characterized in that the air metering device (26) and the fuel metering device (37) are controlled by a control unit (34) in dependence on at least one operating parameter of the combustion engine, which parameter is representative for the content of combustible solid particles in the exhaust gas.
  11. 11. Device according to Claim 9, characterized in that the electrically operated ignition device is operated via the running time of a timing element started by an operation-commencement signal.
  12. 12. Device according to Claim 10 or 11, characterized in that the control unit (34) is provided with a flame-monitoring device, which is connected to at least one flame-monitoring sensor (41, 42), by the signal of which the electrically operated ignition device is controlled.
  13. 13. Device according to one of Claims 5 to 12, characterized in that a pressure valve (27) is arranged in at least the additional-air line (23) opening out into the combustion chamber (4).
  14. 14. Device according to Claim 13, characterized in that the air line (21) from which the additional-air lines (23, 24) branch off is led via a heat exchanger (19) arranged in the outlet (17).
  15. 15. Device according to one of the preceding claims, characterized in that catalytically active burning promoters are mixed in with the additional fuel.
EP86108625A 1985-07-20 1986-06-25 Device for the removal of combustible particles from the exhaust gas of a combustion engine Expired EP0215205B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86108625T ATE42800T1 (en) 1985-07-20 1986-06-25 DEVICE FOR REMOVAL OF FLAMMABLE SOLID PARTICLES FROM EXHAUST GASES FROM COMBUSTION ENGINEERS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3526074 1985-07-20
DE19853526074 DE3526074A1 (en) 1985-07-20 1985-07-20 DEVICE FOR THE REMOVAL OF COMBUSTABLE SOLID PARTICLES FROM THE EXHAUST GAS FROM COMBUSTION ENGINES

Publications (2)

Publication Number Publication Date
EP0215205A1 EP0215205A1 (en) 1987-03-25
EP0215205B1 true EP0215205B1 (en) 1989-05-03

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US (1) US4672808A (en)
EP (1) EP0215205B1 (en)
JP (1) JPS6226313A (en)
AT (1) ATE42800T1 (en)
DE (2) DE3526074A1 (en)

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DE3621913A1 (en) * 1986-06-30 1988-01-07 Bosch Gmbh Robert DEVICE FOR BURNING SOLID PARTICLES IN THE EXHAUST GAS FROM COMBUSTION ENGINES
KR890701872A (en) * 1987-08-03 1989-12-22 마티야스 요반 Method for separating soot particles from internal combustion engine and purifying exhaust gas and apparatus for carrying out the method
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DE3732491A1 (en) * 1987-09-26 1989-04-13 Bosch Gmbh Robert IGNITION BURNER FOR A DEVICE FOR BURNING SOLID PARTICLES IN THE EXHAUST GAS FROM COMBUSTION ENGINES
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Also Published As

Publication number Publication date
JPS6226313A (en) 1987-02-04
DE3526074A1 (en) 1987-01-22
US4672808A (en) 1987-06-16
ATE42800T1 (en) 1989-05-15
EP0215205A1 (en) 1987-03-25
DE3663167D1 (en) 1989-06-08

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