EP1285159B1 - Method for operating a diesel motor and a diesel motor - Google Patents

Method for operating a diesel motor and a diesel motor Download PDF

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Publication number
EP1285159B1
EP1285159B1 EP01931666A EP01931666A EP1285159B1 EP 1285159 B1 EP1285159 B1 EP 1285159B1 EP 01931666 A EP01931666 A EP 01931666A EP 01931666 A EP01931666 A EP 01931666A EP 1285159 B1 EP1285159 B1 EP 1285159B1
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EP
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Prior art keywords
engine
engine torque
setting
operating
accordance
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EP01931666A
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German (de)
French (fr)
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EP1285159A1 (en
Inventor
Holger Adler
Nicholas Fekete
Michael Lenz
Thomas Liebscher
Ulrich Merten
Sven PFÖRTSCH
Norbert Ruzicka
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Daimler AG
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DaimlerChrysler AG
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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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/0275—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a NOx trap or adsorbent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1497—With detection of the mechanical response of the engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/1002—Output torque
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/18—Control of the engine output torque
    • F02D2250/21—Control of the engine output torque during a transition between engine operation modes or states
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/32—Air-fuel ratio control in a diesel engine

Definitions

  • the invention relates to a method for operating a diesel engine, in which between a lean operation with more than stoichiometric Combustion air ratio ⁇ > 1 and a rich operation with substoichiometric combustion air ratio ⁇ ⁇ 1 is switched.
  • NO x adsorber systems For exhaust gas purification of diesel engines adsorption devices for nitrogen oxides (NO x ) are used. Under certain conditions, NO x adsorber systems store, for example, free storage capacity, an active temperature window, the nitrogen oxides of internal combustion engines during lean combustion, ie, superstoichiometric combustion with ⁇ > 1 and residual oxygen in the exhaust gas. NO x adsorber systems also store the sulfur contained in the fuel and engine oil in the form of sulfates (SO x ). The sulfates undesirably occupy the storage sites for the nitrogen oxides due to the higher chemical binding forces.
  • SO x sulfates
  • the published patent application DE 196 36 790 A1 describes the setting a rich exhaust gas mixture of a diesel engine, wherein a performance loss should be prevented by the rich exhaust gas mixture only at low load, in shear phases or idle.
  • the published patent application DE 199 14 787 A1 describes an exhaust gas purification system for a diesel engine in which reducing agent is injected into the exhaust gas line for the regeneration of an NO x storage and an exhaust gas flow rate with an exhaust gas throttle valve is reduced. Since such a regeneration operation increases the pumping loss of the engine, reduces the engine output and thereby causes a torque shock, the amount of fuel injected into the combustion chamber and an opening degree of an exhaust gas recirculation valve are increased to ensure the same engine performance as before the reduction of the exhaust gas flow rate.
  • the invention is based on the technical problem of a method for operating a diesel engine and a diesel engine in which a switch between a lean operation and a rich operation of the diesel engine unnoticed by the driver and without sacrificing ride comfort.
  • determining one delivered at the detected driving state in lean operation Engine torque and setting a in the detected driving condition engine torque delivered in rich operation to that for lean operation Determined engine torque is a comparison between rich operation and lean operation allows.
  • the engine torque influencing parameters can be set in rich operation the same engine torque as a corresponding one Driving condition can be achieved in lean operation, leaving a driver the set mode is not noticed.
  • the driving condition can be determined by the speed and the accelerator pedal position be. Such a method also allows manufacturing tolerances between different engines and wear by comparing lean and rich operation.
  • the Change from a fuel-guided mixture formation process on an air-mass-guided mixture formation process can also change the load in wide ranges in rich operation be achieved.
  • a control in rich operation via the setting the air mass instead of adjusting the amount of fuel as in lean operation is advantageous because at one Diesel engine in rich operation hardly any load changes by a Variation of fuel mass can be achieved.
  • the change between fuel-guided mixture formation process and air-mass-guided Mixture formation process can be continuous or discontinuously.
  • the setting of the parameters influencing the engine torque involves adjusting an assigned air mass. This can via a throttle device in the intake, e.g. an electric one or pneumatically actuated valve or throttle, be effected.
  • a device for determining the air mass e.g. a hot film air mass flowmeter may be provided be.
  • Exhaust gas recirculation rate Another parameter influencing the engine torque is a Exhaust gas recirculation rate, which via an electrically or pneumatically actuated Exhaust gas recirculation valve can be adjusted.
  • An exhaust gas recirculation cooler may also be provided.
  • the engine torque is also due to the adjustment of an intake manifold pressure influenced, for example, by a throttle device in the intake, an exhaust gas recirculation and a charging device, like a turbocharger, is set.
  • the engine torque influencing parameters are exhaust back pressure, Injection start and injection quantity. variations of the injection process consist of a pre-, Main and post injection, for example, so that nacheingespritzter Fuel ceases to participate in combustion can.
  • a comfortable driving is also achieved by that in the presence of unfavorable boundary conditions, switching between Lean operation and fat operation is delayed in time.
  • a neutral transition is favored by the fact that before the Change from the fuel-guided mixture formation process on the air mass-guided mixture formation process a setting is carried out by an air path parameters. So For example, a throttle and an exhaust gas recirculation valve already before switching to the air mass-driven Mixture formation process in the then required position driven.
  • a diesel engine according to the invention has a speed sensor and / or an engine torque sensor. So, especially with a high resolution speed sensor, is the starting point for an accurate determination of engine torque fluctuations available.
  • a throttle device with a first actuator in the intake and / or an exhaust gas recirculation device with an exhaust gas recirculation valve with a second actuator the assigned Air mass, the intake manifold pressure and / or the exhaust gas recirculation rate to be influenced.
  • Motor torque fluctuations and the for keeping the engine torque constant settings necessary the engine torque influencing parameters are in one Engine control unit determines which also the actuators controlled by appropriate signals, between lean operation and Grease mode switches, engine torque fluctuations determined and the engine torque regulates.
  • the exhaust gas recirculation valve can be upstream or downstream of the throttle device in the intake path be arranged.
  • the diesel engine has one with the intake path connected charging device, for example a turbocharger, with a third actuator coming from the engine control unit is controllable.
  • the third actuator may be in an exhaust gas turbocharger a boost pressure in the intake, an exhaust back pressure, a perfused cross-section and a flowing exhaust gas volume be set.
  • An accurate adjustment of the allocated air mass is through a device for changing an intake cross section of a each cylinder with a fourth actuator coming from the engine control unit is taxable, favors.
  • Such Device can, for example, as a single throttle in the intake every cylinder be realized.
  • the diesel engine 10 shown schematically in FIG. 1 has a speed sensor 12 and an engine torque sensor 14. Of the Torque sensor 12 and the engine torque sensor 14 are provided with a Motor control unit 16 connected. Based on the signals from the The speed sensor 12 and the engine torque sensor 14 determine the engine control unit 16 possible engine torque fluctuations.
  • the engine control unit 16 controls an injection system 18, a throttle valve 22 via a first actuator 20, an exhaust gas recirculation valve 26 via a second actuator 24, the exhaust gas turbine 30 of an exhaust gas turbocharger 31 via a third actuator 28 and individual throttles 34 in the intake path of each cylinder via a fourth actuator 32.
  • the exhaust gas recirculation valve 26 opens and closes an exhaust gas recirculation passage 36, which starts from an exhaust manifold 38, passes through an exhaust gas recirculation cooler 40 and opens into the intake path 42 of the diesel engine 10. The entry of fresh air into the intake passage 42 of the diesel engine 10 is indicated by an arrow 44.
  • the incoming at 44 fresh air passes through a compressor turbine of the exhaust gas turbocharger 31, passes through the throttle valve 22 and the exhaust gas recirculation valve 26 and passes past the individual throttle valves 34 in the intake tract of each cylinder in the combustion chambers of the cylinder.
  • From the combustion chamber discharged exhaust gas passes into the exhaust manifold 38 into the exhaust gas turbine 30 passes a NOx adsorbent 46 and exits the diesel engine 10 at the position indicated with an arrow 48 point.
  • the diesel engine 10 can be switched between a lean operation with a superstoichiometric combustion air ratio ⁇ > 1 and a rich operation with a substoichiometric combustion air ratio ⁇ ⁇ 1.
  • the engine control unit 16 increases the amount of fuel injected by the injection system 18 and simultaneously reduces the supplied air mass via the actuator 20 and the throttle valve 22.
  • a temporary rich operation of the diesel engine 10 is required for regeneration of the NO x adsorber 46.
  • the engine controller 16 determines from the signals of the rotational speed sensor 12 and / or the signals of the engine torque sensor 14 engine torque fluctuations that occur during the switching. If the engine control unit 16 detects fluctuations in the engine torque that occur, it keeps the engine torque constant during the changeover by transmitting signals to the first, second, third and fourth actuators 20, 24, 28, 32 and to the injection system for adjusting parameters influencing the engine torque 18 issues.
  • Such parameters are an allocated air mass which can be adjusted by adjustment the throttle valve 22, the individual throttle valves 34, the Exhaust gas recirculation valve 26 and the exhaust gas turbocharger 31 changed can be.
  • a measurement of the assigned air mass takes place for example, via a hot-film air mass flow meter, not shown in the intake 42.
  • the engine torque is also affected by the intake manifold pressure in the intake path 42, that of the engine control unit 16 by adjusting the exhaust gas recirculation valve 26, the throttle 22, the throttle valves 34 and the exhaust gas turbocharger 31 is changed.
  • the engine torque is influenced by the exhaust gas recirculation rate, that of the engine control unit 16 by adjustment the exhaust gas recirculation valve 26, the throttle valve 22 and the Exhaust gas turbocharger 31 can be changed.
  • the diesel engine 10 is controlled by the engine control unit 16 with a fuel-guided mixture formation process operated. In this case, a control of the engine torque takes place by adjusting the allocated amount of fuel.
  • the engine control unit 16 sets the engine control unit 16 to an air mass guided Mixture formation method um. In this case, the regulation of the Engine torque via an adjustment of the allocated air mass.
  • rich operation of the diesel engine 10 only such allows Heilmassenumblees mixture formation method, the regulation of Engine torque over the entire operating range of the diesel engine 10, because in the fat operation, a load change of the diesel engine barely can be achieved by a variation of the fuel mass.
  • the engine control unit 16 can also be used in transient operating states and / or high engine load between lean operation and switch over to rich operation without switching by switching Torque shock would be felt.
  • the transition from the fuel mass-guided to the air mass-guided mixture formation process and back is done by continuously tracking all or individual actuators 20, 24, 28, 32nd
  • FIG. 2 schematically illustrates the sequence of the method according to the invention for operating the diesel engine 10.
  • the engine control unit 16 checks switching criteria for switching between lean operation and rich operation and vice versa. These concern, for example, the existing storage capacity of the NO x adsorber 46 and the present exhaust gas temperature, both of which are determined by suitable sensors and transmitted to the engine control unit 16. If the switching criteria are not met, the diesel engine 10, as shown in step 52, further operated by the engine control unit 16 in lean operation.
  • the engine torque control in lean operation is indicated by steps 54, 56 ... 58 in which individual parameters influencing the engine torque, such as intake manifold pressure in the intake path 42 and the amount of fuel injected by the fuel injection system 18, are set according to the fuel-guided mixture formation method used in lean operation become.
  • step 50 the engine control unit 16 switches to rich operation in step 52 of the diesel engine 10 um and changes to an air mass Mixture formation method via.
  • the regulation of engine torque during the switching, i. until reaching one stoichiometric air ratio ⁇ ⁇ 1, and in Fat operation by adjusting the engine torque influencing Parameters such as the assigned air mass and the exhaust gas recirculation rate, according to the method used in rich operation air-mass-guided mixture formation process, is characterized by the Steps 60, 62 ... 64 indicated.
  • the engine control unit switches 16 in step 52 again on lean operation of the diesel engine 10 um. Even with this switching back is the engine torque kept constant, so that the switching operation not noticed by the driver.
  • the control of the engine torque in steps 54, 56, 58 and 60, 62, 64 is done in an adaptive manner.
  • the parameters By adaptation the parameters to be set to values from an expected one Range preset so that small changes to the scheme suffice.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The invention relates to a method for operating a diesel motor. Said method switches between a lean-mixture operation with a leaner than stoichiometric combustion air ratio μ > 1 and a rich-mixture operation with a richer than stoichiometric combustion air ratio μ < 1. The inventive method consists of the following steps: determining the motor torque fluctuations during the switch and maintaining the motor torque during the switch by adjusting the parameters that influence the motor torque. The method can be used, for example, in motor vehicles.

Description

Die Erfindung betrifft ein Verfahren zum Betreiben eines Dieselmotors, bei dem zwischen einem Magerbetrieb mit überstöchiometrischem Verbrennungsluftverhältnis λ > 1 und einem Fettbetrieb mit unterstöchiometrischem Verbrennungsluftverhältnis λ < 1 umgeschaltet wird.The invention relates to a method for operating a diesel engine, in which between a lean operation with more than stoichiometric Combustion air ratio λ> 1 and a rich operation with substoichiometric combustion air ratio λ <1 is switched.

Zur Abgasreinigung von Dieselmotoren werden Adsorptionseinrichtungen für Stickoxide (NOx) verwendet. NOx-Adsorbersysteme speichern unter bestimmten Voraussetzungen, z.B. freie Speicherkapazität, aktives Temperaturfenster, die Stickoxide von Verbrennungskraftmaschinen bei magerer Verbrennung, d.h. überstöchiometrischer Verbrennung mit λ > 1 und Restsauerstoff im Abgas. NOx-Adsorbersysteme speichern auch den im Kraftstoff und Motoröl enthaltenen Schwefel in Form von Sulfaten (SOx). Die Sulfate belegen durch die höheren chemischen Bindungskräfte unerwünscht die Speicherstellen für die Stickoxide. Zur Regeneration solcher NOx-Adsorbersysteme, also eine Desorption von NOx und ein gleichzeitiger NOx-Umsatz sowie eine Desorption von SOx und gleichzeitiger SOx-Umsatz, wird sauerstofffreies Abgas mit λ < 1 und möglichst hohem Reduktionsmittelgehalt benötigt. Eine solche Regeneration eines NOx-Adsorbersystems kann durch zeitweisen fetten Motorbetrieb, d.h. mit unterstöchiometrischer Verbrennung mit λ < 1, realisiert werden.For exhaust gas purification of diesel engines adsorption devices for nitrogen oxides (NO x ) are used. Under certain conditions, NO x adsorber systems store, for example, free storage capacity, an active temperature window, the nitrogen oxides of internal combustion engines during lean combustion, ie, superstoichiometric combustion with λ> 1 and residual oxygen in the exhaust gas. NO x adsorber systems also store the sulfur contained in the fuel and engine oil in the form of sulfates (SO x ). The sulfates undesirably occupy the storage sites for the nitrogen oxides due to the higher chemical binding forces. For the regeneration of such NO x adsorber systems, ie a desorption of NO x and a simultaneous NO x conversion and a desorption of SO x and simultaneous SO x conversion, oxygen-free exhaust gas with λ <1 and the highest possible reducing agent content is needed. Such a regeneration of a NO x adsorber system can be realized by temporarily rich engine operation, ie with substoichiometric combustion with λ <1.

In der Patentschrift DE 195 43 219 C1 ist ein Verfahren zum Betreiben eines Dieselmotors beschrieben, bei dem zwischen einem Magerbetrieb mit überstöchiometrischem Verbrennungsluftverhältnis λ > 1 und einem Fettbetrieb mit unterstöchiometrischem Verbrennungsluftverhältnis λ < 1 umgeschaltet wird. Die Umschaltung erfolgt zur Regeneration einer Abgasreinigungsanlage mit einem NOx-Adsorbersystem. Das Umschalten von Magerbetrieb auf Fettbetrieb erfolgt durch elektronisch geregelte Abgasrückführung, Ansaugluftdrosselung, zusätzliche Nacheinspritzung von Kraftstoff sowie Erhöhung des Abgasgegendrucks.In the patent DE 195 43 219 C1, a method for operating a diesel engine is described in which is switched between a lean operation with superstoichiometric combustion air ratio λ> 1 and a rich operation with substoichiometric combustion air ratio λ <1. Switching takes place for regeneration of an emission control system with a NO x adsorber system. The switchover from lean operation to rich operation is carried out by electronically controlled exhaust gas recirculation, intake air throttling, additional post-injection of fuel and increase of the exhaust back pressure.

In der Patentschrift DE 197 50 226 C1 ist ein Motorregelsystem für einen Dieselmotor beschrieben, bei dem mit dem Umschalten zwischen Magerbetrieb und Fettbetrieb gleichzeitig zwischen gespeicherten Kennfeldern für den Magerbetrieb und Kennfeldern für den Fettbetrieb umgeschaltet wird. Damit soll unter anderem erreicht werden, dass der Fahrer das Umschalten zwischen Magerbetrieb und Fettbetrieb nicht als störend empfindet bzw. nicht bemerkt. Der Dieselmotor liefert aber nur in einem begrenzten Bereich des Fettbetriebes etwa die gleiche Leistung wie in dem entsprechenden Magerbetrieb, so dass ein unbemerkter Wechsel zwischen den Betriebsarten nur in diesem begrenzten Bereich erfolgen kann.In the patent DE 197 50 226 C1 is a motor control system for a diesel engine described in which with the switching between lean operation and rich operation simultaneously stored between Characteristic maps for lean operation and maps is switched for the rich operation. This should, among other things be achieved that the driver switching between lean operation and fat operation does not feel annoying or not noticed. The diesel engine delivers but only in a limited Range of rich operation about the same performance as in the corresponding lean operation, leaving an unnoticed change between the operating modes only in this limited area can.

In der Patentschrift DE 197 53 718 C1 ist ein Verfahren zum Betreiben eines Dieselmotors beschrieben, bei dem nur bei Vorliegen eines stationären oder quasi stationären Motorbetriebszustandes von Magerbetrieb auf Fettbetrieb des Dieselmotors umgeschaltet wird. Dadurch soll erreicht werden, dass beim Umschalten hinsichtlich der Leistungsentfaltung des Dieselmotors vom Fahrer keine Veränderung bemerkt wird. Bei Vorliegen eines instationären Motorbetriebszustandes im Fettbetrieb wird vom Fettbetrieb in den Magerbetrieb zurückgeschaltet. In einem Speicher der Motorsteuerung sind sowohl Kennfelder für den Magerbetrieb als auch für den Fettbetrieb des Dieselmotors abgespeichert.In the patent DE 197 53 718 C1 is a method for Operating a diesel engine described in which only exist a stationary or quasi-stationary engine operating condition switched from lean operation to rich operation of the diesel engine becomes. This is intended to ensure that when switching in terms of the power delivery of the diesel engine no change is noticed by the driver. In the presence of a transient engine operating state in rich operation is from the Grease mode switched back to lean operation. In one Memory of the engine control are both maps for lean operation as well as for the rich operation of the diesel engine stored.

Die Offenlegungsschrift DE 196 36 790 A1 beschreibt das Einstellen eines fetten Abgasgemisches eines Dieselmotors, wobei eine Leistungseinbuße dadurch verhindert werden soll, dass das fette Abgasgemisch lediglich bei niedriger Belastung, in Schubphasen oder im Leerlauf eingestellt wird. The published patent application DE 196 36 790 A1 describes the setting a rich exhaust gas mixture of a diesel engine, wherein a performance loss should be prevented by the rich exhaust gas mixture only at low load, in shear phases or idle.

In der Offenlegungsschrift DE 196 36 040 A1 wird vorgeschlagen, ein fettes Abgasgemisch zur Regeneration eines NOx-Speichers durch Anheben einer Abgasrückführungsrate zu erreichen. Bei höheren Lasten der Brennkraftmaschine, insbesondere ≥ 20% der Nennleistung, wird vorgeschlagen, das Verhältnis von rückgeführtem Abgasstrom zur Ansaugluft zu verkleinern, um einem Leistungsabfall entgegenzuwirken.In the published patent application DE 196 36 040 A1 it is proposed to achieve a rich exhaust gas mixture for the regeneration of a NO x storage tank by raising an exhaust gas recirculation rate. At higher loads of the internal combustion engine, in particular ≥ 20% of the rated power, it is proposed to reduce the ratio of recirculated exhaust gas flow to the intake air in order to counteract a power loss.

Die Offenlegungsschrift DE 199 14 787 A1 beschreibt ein Abgasreinigungssystem für einen Dieselmotor, bei dem zur Regeneration eines NOx-Speichers Reduktionsmittel in den Abgasstrang eingespritzt wird und eine Abgasdurchflussmenge mit einer Abgasdrosselklappe reduziert wird. Da ein solcher Regenerationsbetrieb den Pumpverlust des Motors erhöht, die Motorleistung reduziert und dadurch einen Drehmomentstoß verursacht, wird die in die Verbrennungskammer eingespritzte Kraftstoffmenge sowie ein öffnungsgrad eines Abgasrückführungsventils erhöht, um dieselbe Motorleistung wie vor der Reduzierung der Abgasdurchflussmenge sicherzustellen.The published patent application DE 199 14 787 A1 describes an exhaust gas purification system for a diesel engine in which reducing agent is injected into the exhaust gas line for the regeneration of an NO x storage and an exhaust gas flow rate with an exhaust gas throttle valve is reduced. Since such a regeneration operation increases the pumping loss of the engine, reduces the engine output and thereby causes a torque shock, the amount of fuel injected into the combustion chamber and an opening degree of an exhaust gas recirculation valve are increased to ensure the same engine performance as before the reduction of the exhaust gas flow rate.

Der Erfindung liegt das technische Problem zugrunde, ein Verfahren zum Betreiben eines Dieselmotors und einen Dieselmotor anzugeben, bei denen eine Umschaltung zwischen einem Magerbetrieb und einem Fettbetrieb des Dieselmotors für den Fahrer unbemerkt und ohne Einbußen an Fahrkomfort geschehen kann.The invention is based on the technical problem of a method for operating a diesel engine and a diesel engine in which a switch between a lean operation and a rich operation of the diesel engine unnoticed by the driver and without sacrificing ride comfort.

Erfindungsgemäß ist hierzu ein Verfahren zum Betreiben eines Dieselmotors mit den Merkmalen von Anspruch 1 und ein Dieselmotor mit den Merkmalen von Anspruch 13 vorgesehen.According to the invention, a method for operating a Diesel engine with the features of claim 1 and a diesel engine provided with the features of claim 13.

Indem Motormomentschwankungen während des Umschaltens bestimmt werden, kann unmittelbar auf den Fahrkomfort beeinträchtigende Drehmomentstöße reagiert werden. In Verbindung mit dem Konstanthalten des Motormoments mittels einer Motormomentregelung während des Umschaltens durch Einstellen von das Motormoment beeinflussende Parametern ist es möglich, auch bei hoher Motorlast und instationären Betriebszuständen in den Fettbetrieb umzuschalten, ohne dass dies von einem Fahrer bemerkt wird. Durch die Bestimmung tatsächlich auftretender Motormomentschwankungen können auch die Auswirkungen von Fertigungstoleranzen und Verschleiß auf Drehmomentstöße beim Umschalten ausgeglichen werden.By determining engine torque fluctuations during the shift can be directly affecting the ride comfort Torque shocks are reacted. In connection with keeping constant the engine torque by means of an engine torque control during the shift by adjusting the engine torque influencing parameters, it is possible even at high engine load and switch transient operating states to rich operation, without this being noticed by a driver. By the determination of actually occurring engine torque fluctuations Also, the effects of manufacturing tolerances and wear be compensated for torque shocks when switching.

Durch Erfassen eines Fahrzustandes im Fettbetrieb, Ermitteln eines bei dem erfassten Fahrzustand im Magerbetrieb abgegebenen Motormoments und Einstellen eines bei dem erfassten Fahrzustand im Fettbetrieb abgegebenen Motormoments auf das für den Magerbetrieb ermittelte Motormoment ist ein Vergleich zwischen Fettbetrieb und Magerbetrieb ermöglicht. Indem die das Motormoment beeinflussenden Parameter eingestellt werden, kann im Fettbetrieb das gleiche Motormoment wie bei einem entsprechenden Fahrzustand im Magerbetrieb erreicht werden, so dass ein Fahrer die eingestellte Betriebsart nicht bemerkt. Der Fahrzustand kann dabei durch die Drehzahl und die Fahrpedalstellung bestimmt sein. Ein solches Verfahren ermöglicht es auch, Fertigungstoleranzen zwischen verschiedenen Motoren und Verschleiß durch einen Vergleich von Magerbetrieb und Fettbetrieb zu detektieren.By detecting a driving condition in rich operation, determining one delivered at the detected driving state in lean operation Engine torque and setting a in the detected driving condition engine torque delivered in rich operation to that for lean operation Determined engine torque is a comparison between rich operation and lean operation allows. By the the engine torque influencing parameters can be set in rich operation the same engine torque as a corresponding one Driving condition can be achieved in lean operation, leaving a driver the set mode is not noticed. The driving condition can be determined by the speed and the accelerator pedal position be. Such a method also allows manufacturing tolerances between different engines and wear by comparing lean and rich operation.

Indem beim Umschalten von Magerbetrieb auf Fettbetrieb der Wechsel von einem kraftstoffgeführten Gemischbildungsverfahren auf ein luftmassengeführtes Gemischbildungsverfahren erfolgt, kann auch im Fettbetrieb eine Laständerung in weiten Bereichen erreicht werden. Eine Regelung im Fettbetrieb über die Einstellung der Luftmasse, anstatt über die Einstellung der Kraftstoffmenge wie im Magerbetrieb, ist vorteilhaft, da bei einem Dieselmotor im Fettbetrieb kaum noch Laständerungen durch eine Variation der Kraftstoffmasse erreichbar sind. Der Wechsel zwischen kraftstoffgeführtem Gemischbildungsverfahren und luftmassengeführtem Gemischbildungsverfahren kann dabei kontinuierlich oder diskontinuierlich erfolgen.By switching from lean operation to rich operation the Change from a fuel-guided mixture formation process on an air-mass-guided mixture formation process, can also change the load in wide ranges in rich operation be achieved. A control in rich operation via the setting the air mass instead of adjusting the amount of fuel as in lean operation, is advantageous because at one Diesel engine in rich operation hardly any load changes by a Variation of fuel mass can be achieved. The change between fuel-guided mixture formation process and air-mass-guided Mixture formation process can be continuous or discontinuously.

Das Einstellen der das Motormoment beeinflussenden Parameter beinhaltet das Einstellen einer zugeteilten Luftmasse. Dies kann über eine Drosseleinrichtung im Ansaugweg, z.B. ein elektrisch oder pneumatisch betätigtes Ventil oder eine Drosselklappe, bewirkt werden. Eine Vorrichtung zur Bestimmung der Luftmasse, z.B. ein Heißfilm-Luftmassen-Durchflußmesser, kann vorgesehen sein.The setting of the parameters influencing the engine torque involves adjusting an assigned air mass. This can via a throttle device in the intake, e.g. an electric one or pneumatically actuated valve or throttle, be effected. A device for determining the air mass, e.g. a hot film air mass flowmeter may be provided be.

Ein weiterer das Motormoment beeinflussender Parameter ist eine Abgasrückführrate, die über ein elektrisch oder pneumatisch betätigtes Abgasrückführventil eingestellt werden kann. Ein Abgasrückführungskühler kann ebenfalls vorgesehen sein.Another parameter influencing the engine torque is a Exhaust gas recirculation rate, which via an electrically or pneumatically actuated Exhaust gas recirculation valve can be adjusted. An exhaust gas recirculation cooler may also be provided.

Das Motormoment wird auch durch die Einstellung eines Saugrohrdrucks beeinflusst, der beispielsweise durch eine Drosseleinrichtung im Ansaugweg, eine Abgasrückführung und eine Aufladeeinrichtung, wie ein Turbolader, eingestellt wird.The engine torque is also due to the adjustment of an intake manifold pressure influenced, for example, by a throttle device in the intake, an exhaust gas recirculation and a charging device, like a turbocharger, is set.

Weitere, das Motormoment beeinflussende Parameter sind Abgasgegendruck, Einspritzbeginn und Einspritzmenge. Variationsmöglichkeiten des Einspritzvorgangs bestehen bezüglich einer Vor-, Haupt- und Nacheinspritzung, beispielsweise so, dass nacheingespritzter Kraftstoff nicht mehr an einer Verbrennung teilnehmen kann.Further, the engine torque influencing parameters are exhaust back pressure, Injection start and injection quantity. variations of the injection process consist of a pre-, Main and post injection, for example, so that nacheingespritzter Fuel ceases to participate in combustion can.

Ein komfortabler Fahrbetrieb wird auch dadurch erreicht, dass bei Vorliegen ungünstiger Randbedingungen das Umschalten zwischen Magerbetrieb und Fettbetrieb zeitlich verzögert wird.A comfortable driving is also achieved by that in the presence of unfavorable boundary conditions, switching between Lean operation and fat operation is delayed in time.

Ein neutraler Übergang wird dadurch begünstigt, dass vor dem Wechsel von dem kraftstoffgeführten Gemischbildungsverfahren auf das luftmassengeführte Gemischbildungsverfahren eine Einstellung von einen Luftpfad betreffenden Parametern erfolgt. So werden beispielsweise eine Drosselklappe und ein Abgasrückführungsventil bereits vor dem Wechsel auf das luftmassengeführte Gemischbildungsverfahren in die dann benötigte Stellung gefahren. A neutral transition is favored by the fact that before the Change from the fuel-guided mixture formation process on the air mass-guided mixture formation process a setting is carried out by an air path parameters. So For example, a throttle and an exhaust gas recirculation valve already before switching to the air mass-driven Mixture formation process in the then required position driven.

Indem das Verändern der das Motormoment beeinflussenden Parameter durch eine adaptive Regelung oder eine adaptive Steuerung erfolgt, kann eine schnellere Anpassung des Motormoments erreicht werden, da bereits von durch Adaption voreingestellten Werten ausgegangen werden kann.By changing the parameters influencing the engine torque by an adaptive control or an adaptive control takes place, a faster adjustment of the engine torque can be achieved since already pre-set by adaptation Values can be assumed.

Ein erfindungsgemäßer Dieselmotor weist einen Drehzahlsensor und/oder einen Motormomentsensor auf. Damit, insbesondere mit einem hochauflösenden Drehzahlsensor, ist die Ausgangsbasis für eine genaue Bestimmung von Motormomentschwankungen vorhanden. Mit einer Drosseleinrichtung mit einem ersten Stellglied im Ansaugweg und/oder einer Abgasrückführeinrichtung mit einem Abgasrückführventil mit einem zweiten Stellglied können die zugeteilte Luftmasse, der Saugrohrdruck und/oder die Abgasrückführrate beeinflusst werden. Motormomentschwankungen und die für das Konstanthalten des Motormoments notwendigen Einstellungen der das Motormoment beeinflussenden Parameter werden in einer Motorsteuerungseinheit bestimmt, die auch die Stellglieder durch entsprechende Signale steuert, zwischen Magerbetrieb und Fettbetrieb umschaltet, Motormomentschwankungen bestimmt und das Motormoment regelt. Das Abgasrückführungsventil kann stromaufwärts oder stromabwärts der Drosseleinrichtung im Ansaugweg angeordnet sein. Indem die Motorsteuerungseinheit mittels der Motormomentregelung während des Umschaltens zwischen Magerbetrieb und Fettbetrieb das Motormoment konstant hält, kann ein Wechsel zwischen den Betriebsarten Magerbetrieb und Fettbetrieb für einen Fahrer unmerklich durchgeführt werden.A diesel engine according to the invention has a speed sensor and / or an engine torque sensor. So, especially with a high resolution speed sensor, is the starting point for an accurate determination of engine torque fluctuations available. With a throttle device with a first actuator in the intake and / or an exhaust gas recirculation device with an exhaust gas recirculation valve with a second actuator, the assigned Air mass, the intake manifold pressure and / or the exhaust gas recirculation rate to be influenced. Motor torque fluctuations and the for keeping the engine torque constant settings necessary the engine torque influencing parameters are in one Engine control unit determines which also the actuators controlled by appropriate signals, between lean operation and Grease mode switches, engine torque fluctuations determined and the engine torque regulates. The exhaust gas recirculation valve can be upstream or downstream of the throttle device in the intake path be arranged. By the engine control unit by means of Engine torque control during the switchover between lean operation and rich operation keeps the engine torque constant, can Change between the operating modes lean operation and rich operation imperceptible to a driver.

Vorteilhafterweise weist der Dieselmotor eine mit dem Ansaugweg verbundene Aufladeeinrichtung, beispielsweise einen Turbolader, mit einem dritten Stellglied auf, das von der Motorsteuerungseinheit ansteuerbar ist. Über die Motorsteuerungseinheit und das dritte Stellglied kann bei einem Abgasturbolader beispielsweise ein Ladedruck im Ansaugweg, ein Abgasgegendruck, ein durchströmter Querschnitt und ein durchströmendes Abgasvolumen eingestellt werden. Advantageously, the diesel engine has one with the intake path connected charging device, for example a turbocharger, with a third actuator coming from the engine control unit is controllable. About the engine control unit and For example, the third actuator may be in an exhaust gas turbocharger a boost pressure in the intake, an exhaust back pressure, a perfused cross-section and a flowing exhaust gas volume be set.

Eine genaue Einstellung der zugeteilten Luftmasse wird durch eine Vorrichtung zum Verändern eines Ansaugquerschnitts eines jeden Zylinders mit einem vierten Stellglied, das von der Motorsteuerungseinheit ansteuerbar ist, begünstigt. Eine solche Vorrichtung kann beispielsweise als Einzeldrosselklappe im Ansaugtrakt jedes Zylinders realisiert sein. An accurate adjustment of the allocated air mass is through a device for changing an intake cross section of a each cylinder with a fourth actuator coming from the engine control unit is taxable, favors. Such Device can, for example, as a single throttle in the intake every cylinder be realized.

Weitere Merkmale und Vorteile der Erfindung ergeben sich aus der folgenden Beschreibung im Zusammenhang mit den beigefügten Zeichnungen, die folgendes zeigen:

Fig. 1
eine schematische Darstellung eines Dieselmotors gemäß der vorliegenden Erfindung und
Fig. 2
eine schematische Darstellung von Schritten des erfindungsgemäßen Verfahrens.
Further features and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:
Fig. 1
a schematic representation of a diesel engine according to the present invention and
Fig. 2
a schematic representation of steps of the method according to the invention.

Der in der Fig. 1 schematisch dargestellte Dieselmotor 10 weist einen Drehzahlsensor 12 und einen Motormomentsensor 14 auf. Der Drehmomentsensor 12 und der Motormomentsensor 14 sind mit einer Motorsteuerungseinheit 16 verbunden. Anhand der Signale von dem Drehzahlsensor 12 und dem Motormomentsensor 14 bestimmt die Motorsteuerungseinheit 16 eventuell auftretende Motormomentschwankungen.The diesel engine 10 shown schematically in FIG. 1 has a speed sensor 12 and an engine torque sensor 14. Of the Torque sensor 12 and the engine torque sensor 14 are provided with a Motor control unit 16 connected. Based on the signals from the The speed sensor 12 and the engine torque sensor 14 determine the engine control unit 16 possible engine torque fluctuations.

Die Motorsteuerungseinheit 16 steuert eine Einspritzanlage 18, über ein erstes Stellglied 20 eine Drosselklappe 22, über ein zweites Stellglied 24 ein Abgasrückführungsventil 26, über ein drittes Stellglied 28 die Abgasturbine 30 eines Abgasturboladers 31 und über ein viertes Stellglied 32 Einzeldrosselklappen 34 im Ansaugweg jedes Zylinders. Das Abgasrückführungsventil 26 öffnet und verschließt einen Abgasrückführungskanal 36, der von einem Auspuffkrümmer 38 ausgeht, einen Abgasrückführungskühler 40 durchläuft und im Ansaugweg 42 des Dieselmotors 10 mündet. Der Eintritt von Frischluft in den Ansaugweg 42 des Dieselmotors 10 ist mit einem Pfeil 44 bezeichnet. Die bei 44 eintretende Frischluft passiert eine Verdichterturbine des Abgasturboladers 31, passiert die Drosselklappe 22 und das Abgasrückführungsventil 26 und gelangt vorbei an den Einzeldrosselklappen 34 im Ansaugtrakt jedes Zylinders in die Verbrennungsräume der Zylinder. Aus dem Verbrennungsraum ausgestoßenes Abgas gelangt in den Auspuffkrümmer 38, in die Abgasturbine 30, passiert einen NOx-Adsorber 46 und verlässt den Dieselmotor 10 an der mit einem Pfeil 48 bezeichneten Stelle. The engine control unit 16 controls an injection system 18, a throttle valve 22 via a first actuator 20, an exhaust gas recirculation valve 26 via a second actuator 24, the exhaust gas turbine 30 of an exhaust gas turbocharger 31 via a third actuator 28 and individual throttles 34 in the intake path of each cylinder via a fourth actuator 32. The exhaust gas recirculation valve 26 opens and closes an exhaust gas recirculation passage 36, which starts from an exhaust manifold 38, passes through an exhaust gas recirculation cooler 40 and opens into the intake path 42 of the diesel engine 10. The entry of fresh air into the intake passage 42 of the diesel engine 10 is indicated by an arrow 44. The incoming at 44 fresh air passes through a compressor turbine of the exhaust gas turbocharger 31, passes through the throttle valve 22 and the exhaust gas recirculation valve 26 and passes past the individual throttle valves 34 in the intake tract of each cylinder in the combustion chambers of the cylinder. From the combustion chamber discharged exhaust gas passes into the exhaust manifold 38 into the exhaust gas turbine 30 passes a NOx adsorbent 46 and exits the diesel engine 10 at the position indicated with an arrow 48 point.

Mit Hilfe der Motorsteuerung 16 kann der Dieselmotor 10 zwischen einem Magerbetrieb mit überstöchiometrischem Verbrennungsluftverhältnis λ > 1 und einem Fettbetrieb mit unterstöchiometrischem Verbrennungsluftverhältnis λ < 1 umgeschaltet werden. Hierzu erhöht die Motorsteuerung 16 beispielsweise die von der Einspritzanlage 18 eingespritzte Kraftstoffmenge und verringert gleichzeitig über das Stellglied 20 und die Drosselklappe 22 die zugeführte Luftmasse. Ein zeitweiser Fettbetrieb des Dieselmotors 10 ist für eine Regeneration des NOx-Adsorbers 46 erforderlich. Damit eine solche Umschaltung zwischen Magerbetrieb und Fettbetrieb für den Fahrer unbemerkt geschehen kann, bestimmt die Motorsteuerung 16 aus den Signalen des Drehzahlsensors 12 und/oder den Signalen des Motormomentsensors 14 Motormomentschwankungen, die während des Umschaltens auftreten. Detektiert die Motorsteuerungseinheit 16 auftretende Schwankungen des Motormoments, so hält sie das Motormoment während des Umschaltens konstant, indem sie zur Einstellung von das Motormoment beeinflussenden Parametern Signale an das erste, zweite, dritte und vierte Stellglied 20, 24, 28, 32 und an die Einspritzanlage 18 ausgibt.With the aid of the engine control 16, the diesel engine 10 can be switched between a lean operation with a superstoichiometric combustion air ratio λ> 1 and a rich operation with a substoichiometric combustion air ratio λ <1. For this purpose, the engine control unit 16, for example, increases the amount of fuel injected by the injection system 18 and simultaneously reduces the supplied air mass via the actuator 20 and the throttle valve 22. A temporary rich operation of the diesel engine 10 is required for regeneration of the NO x adsorber 46. In order for such a switch between lean operation and rich operation to occur unnoticed by the driver, the engine controller 16 determines from the signals of the rotational speed sensor 12 and / or the signals of the engine torque sensor 14 engine torque fluctuations that occur during the switching. If the engine control unit 16 detects fluctuations in the engine torque that occur, it keeps the engine torque constant during the changeover by transmitting signals to the first, second, third and fourth actuators 20, 24, 28, 32 and to the injection system for adjusting parameters influencing the engine torque 18 issues.

Solche Parameter sind eine zugeteilte Luftmasse, die durch Einstellung der Drosselklappe 22, der Einzeldrosselklappen 34, des Abgasrückführungsventils 26 sowie des Abgasturboladers 31 verändert werden kann. Eine Messung der zugeteilten Luftmasse erfolgt beispielsweise über einen nicht dargestellten Heißfilm-Luftmassen-Durchflußmesser im Ansaugweg 42. Das Motormoment wird auch durch den Saugrohrdruck im Ansaugweg 42 beeinflußt, der von der Motorsteuerungseinheit 16 durch Einstellung des Abgasrückführungsventils 26, der Drosselklappe 22, der Einzeldrosselklappen 34 und des Abgasturboladers 31 verändert wird. Weiter wird das Motormoment durch die Abgasrückführrate beeinflusst, die von der Motorsteuerungseinheit 16 durch Einstellung des Abgasrückführungsventils 26, der Drosselklappe 22 und des Abgasturboladers 31 verändert werden kann. Als weitere Parameter, die das Motormoment beeinflussen, werden von der Motorsteuerungseinheit 16 über die Einspritzanlage 18 ein Einspritzbeginn und eine Einspritzmenge des Kraftstoffs einer Vor-, Haupt- und Nacheinspritzung verändert. Schließlich beeinflusst ein Abgasgegendruck das Motormoment, der von der Motorsteuerungseinheit 16 mit Hilfe des Stellglieds 28 an der Abgasturbine 30 eingestellt werden kann.Such parameters are an allocated air mass which can be adjusted by adjustment the throttle valve 22, the individual throttle valves 34, the Exhaust gas recirculation valve 26 and the exhaust gas turbocharger 31 changed can be. A measurement of the assigned air mass takes place for example, via a hot-film air mass flow meter, not shown in the intake 42. The engine torque is also affected by the intake manifold pressure in the intake path 42, that of the engine control unit 16 by adjusting the exhaust gas recirculation valve 26, the throttle 22, the throttle valves 34 and the exhaust gas turbocharger 31 is changed. Furthermore, the engine torque is influenced by the exhaust gas recirculation rate, that of the engine control unit 16 by adjustment the exhaust gas recirculation valve 26, the throttle valve 22 and the Exhaust gas turbocharger 31 can be changed. As further parameters, which affect the engine torque, are from the engine control unit 16 via the injection system 18 an injection start and an injection amount of the fuel Pre, main and post injection changed. Finally influenced an exhaust backpressure the engine torque generated by the engine control unit 16 with the aid of the actuator 28 on the exhaust gas turbine 30 can be adjusted.

Im Magerbetrieb wird der Dieselmotor 10 durch die Motorsteuerungseinheit 16 mit einem kraftstoffgeführten Gemischbildungsverfahren betrieben. Dabei erfolgt eine Regelung des Motormoments durch Einstellung der zugeteilten Kraftstoffmenge. Beim Umschalten von Magerbetrieb auf Fettbetrieb des Dieselmotors 10 stellt die Motorsteuerungseinheit 16 auf ein luftmassengeführtes Gemischbildungsverfahren um. Dabei erfolgt die Regelung des Motormoments über eine Einstellung der zugeteilten Luftmasse. Im Fettbetrieb des Dieselmotors 10 ermöglicht erst ein solches luftmassengeführtes Gemischbildungsverfahren die Regelung des Motormoments im gesamten Betriebsbereich des Dieselmotors 10, da im Fettbetrieb eine Laständerung des Dieselmotors kaum noch durch eine Variation der Kraftstoffmasse erreichbar ist. Damit kann die Motorsteuerungseinheit 16 auch bei instationären Betriebszuständen und/oder hoher Motorlast zwischen Magerbetrieb und Fettbetrieb umschalten, ohne dass durch das Umschalten ein Drehmomentstoß spürbar würde. Der Übergang von dem kraftstoffmassengeführten auf das luftmassengeführte Gemischbildungsverfahren und zurück erfolgt durch kontinuierliches Nachführen aller oder einzelner Stellglieder 20, 24, 28, 32.In lean operation, the diesel engine 10 is controlled by the engine control unit 16 with a fuel-guided mixture formation process operated. In this case, a control of the engine torque takes place by adjusting the allocated amount of fuel. At the Switching from lean operation to rich operation of the diesel engine 10 sets the engine control unit 16 to an air mass guided Mixture formation method um. In this case, the regulation of the Engine torque via an adjustment of the allocated air mass. In rich operation of the diesel engine 10 only such allows Luftmassengeführtes mixture formation method, the regulation of Engine torque over the entire operating range of the diesel engine 10, because in the fat operation, a load change of the diesel engine barely can be achieved by a variation of the fuel mass. In order to For example, the engine control unit 16 can also be used in transient operating states and / or high engine load between lean operation and switch over to rich operation without switching by switching Torque shock would be felt. The transition from the fuel mass-guided to the air mass-guided mixture formation process and back is done by continuously tracking all or individual actuators 20, 24, 28, 32nd

Auch nach dem Umschalten auf den Fettbetrieb wertet die Motorsteuerungseinheit 16 die Signale von dem Drehzahlsensor 12 und dem Motormomentsensor 14 aus und ordnet das so ermittelte Motormoment dem gerade aktuellen Fahrzustand, beispielsweise Drehzahl und Fahrpedalstellung, zu. Dieses bei einem bestimmten Fahrzustand ermittelte Motormoment im Fettbetrieb wird mit einem Motormoment verglichen, das bei dem erfassten Fahrzustand im Magerbetrieb abgegeben würde. Stellt die Motorsteuerungseinheit eine Abweichung des Motormoments im Fettbetrieb im Vergleich zum Magerbetrieb fest, wird das im Fettbetrieb bei dem erfassten Fahrzustand abgegebene Motormoment auf das für den Magerbetrieb ermittelte Motormoment eingestellt. Durch einen solchen Vergleich der beiden Betriebsarten können sowohl Fertigungstoleranzen von Motoren als auch langfristige Verschiebungen aufgrund von Alterungs- oder Verschleißvorgängen detektiert werden. Auch bemerkt ein Fahrer nicht, ob der Dieselmotor 10 gerade im Magerbetrieb oder im Fettbetrieb läuft.Even after switching to the rich operation evaluates the engine control unit 16, the signals from the speed sensor 12th and the engine torque sensor 14 and assigns the thus determined Engine torque the current driving condition, for example Speed and accelerator pedal position, too. This at a certain Driving condition determined engine torque in rich operation is with a Engine torque compared to the detected driving condition would be delivered in lean operation. Represents the engine control unit a deviation of the engine torque in rich operation in comparison for lean operation, this is in the fat operation at the detected driving condition delivered engine torque on the for the Lean operation determined engine torque set. Through a Such a comparison of the two modes can both manufacturing tolerances of engines as well as long-term shifts due to aging or wear become. Also, a driver does not notice if the diesel engine 10 currently running in lean or rich operation.

Fig. 2 verdeutlicht schematisch den Ablauf des erfindungsgemäßen Verfahrens zum Betreiben des Dieselmotors 10. Im Schritt 50 werden von der Motorsteuerungseinheit 16 Umschaltkriterien für die Umschaltung zwischen Magerbetrieb und Fettbetrieb und umgekehrt abgeprüft. Diese betreffen beispielsweise die vorhandene Speicherkapazität des NOx-Adsorbers 46 und die vorliegende Abgastemperatur, die beide über geeignete Sensoren bestimmt und der Motorsteuerungseinheit 16 übermittelt werden. Sind die Umschaltkriterien nicht erfüllt, wird der Dieselmotor 10, wie im Schritt 52 dargestellt, von der Motorsteuerungseinheit 16 weiter im Magerbetrieb betrieben. Die im Magerbetrieb erfolgende Regelung des Motormoments ist durch Schritte 54, 56 ... 58 angedeutet, in denen einzelne, das Motormoment beeinflussende Parameter, wie Saugrohrdruck im Ansaugweg 42 und Menge des von der Einspritzanlage 18 eingespritzten Kraftstoffs entsprechend dem bei Magerbetrieb angewandten kraftstoffgeführten Gemischbildungsverfahren eingestellt werden.FIG. 2 schematically illustrates the sequence of the method according to the invention for operating the diesel engine 10. In step 50, the engine control unit 16 checks switching criteria for switching between lean operation and rich operation and vice versa. These concern, for example, the existing storage capacity of the NO x adsorber 46 and the present exhaust gas temperature, both of which are determined by suitable sensors and transmitted to the engine control unit 16. If the switching criteria are not met, the diesel engine 10, as shown in step 52, further operated by the engine control unit 16 in lean operation. The engine torque control in lean operation is indicated by steps 54, 56 ... 58 in which individual parameters influencing the engine torque, such as intake manifold pressure in the intake path 42 and the amount of fuel injected by the fuel injection system 18, are set according to the fuel-guided mixture formation method used in lean operation become.

Sind dagegen die Umschaltkriterien im Schritt 50 erfüllt, schaltet die Motorsteuerungseinheit 16 im Schritt 52 auf Fettbetrieb des Dieselmotors 10 um und wechselt auf ein luftmassengeführtes Gemischbildungsverfahren über. Die Regelung des Motormoments während des Umschaltens, d.h. bis zum Erreichen eines unterstöchiometrischen Luftverhältnisses λ < 1, und im Fettbetrieb durch Einstellen von das Motormoment beeinflussenden Parametern, wie die zugeteilte Luftmasse und die Abgasrückführungsrate, entsprechend dem bei Fettbetrieb angewandten luftmassengeführten Gemischbildungsverfahren, ist durch die Schritte 60, 62 ... 64 angedeutet. Ergibt die fortlaufende Überprüfung der Umschaltkriterien im Schritt 50, dass die Umschaltkriterien nicht mehr erfüllt sind, schaltet die Motorsteuerungseinheit 16 im Schritt 52 wieder auf Magerbetrieb des Dieselmotors 10 um. Auch bei dieser Rückumschaltung wird das Motormoment konstant gehalten, so dass der Umschaltvorgang vom Fahrer nicht bemerkt wird.If, on the other hand, the switching criteria are fulfilled in step 50, the engine control unit 16 switches to rich operation in step 52 of the diesel engine 10 um and changes to an air mass Mixture formation method via. The regulation of engine torque during the switching, i. until reaching one stoichiometric air ratio λ <1, and in Fat operation by adjusting the engine torque influencing Parameters such as the assigned air mass and the exhaust gas recirculation rate, according to the method used in rich operation air-mass-guided mixture formation process, is characterized by the Steps 60, 62 ... 64 indicated. Returns the continuous review the switching criteria in step 50 that the switching criteria are no longer satisfied, the engine control unit switches 16 in step 52 again on lean operation of the diesel engine 10 um. Even with this switching back is the engine torque kept constant, so that the switching operation not noticed by the driver.

Die Regelung des Motormoments in den Schritten 54, 56, 58 bzw. 60, 62, 64 erfolgt in adaptiver Weise. Durch Adaption werden die einzustellenden Parameter auf Werte aus einem zu erwartenden Bereich voreingestellt, so dass zur Regelung kleine Veränderungen genügen.The control of the engine torque in steps 54, 56, 58 and 60, 62, 64 is done in an adaptive manner. By adaptation the parameters to be set to values from an expected one Range preset so that small changes to the scheme suffice.

Claims (15)

  1. A process for operating a diesel engine which switches between lean operation with a combustion air ratio (λ > 1) lean of stoichiometry and rich operation with a combustion air ratio (λ < 1) rich of stoichiometry,
    characterised by
    the following steps:
    determination of engine torque fluctuations during the switch and
    maintenance of a constant engine torque by means of an engine torque regulation system during the switch by setting parameters influencing engine torque.
  2. A process for operating a diesel engine in accordance with claim 1,
    characterised by
    the following steps:
    detection of a driving status in rich operation,
    determination of an engine torque developed in lean operation in the driving status detected,
    setting of an engine torque developed in lean operation in the driving status detected to the engine torque determined for lean operation by setting the parameters influencing engine torque.
  3. A process for operating a diesel engine in accordance with claim 1 or 2,
    characterised in that
    when switching from lean operation to rich operation a change from a fuel-led carburetion process to an air mass-led carburetion process takes place.
  4. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of a apportioned air mass.
  5. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of an exhaust gas recirculation rate.
  6. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of an induction pipe pressure.
  7. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of an exhaust gas backpressure.
  8. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of an injection start point.
  9. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque includes the setting of an injection quantity.
  10. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the switch between lean operation and rich operation is time-delayed in the presence of unfavourable boundary conditions.
  11. A process for operating a diesel engine in accordance with claim 3 and one of the preceding claims,
    characterised in that
    prior to the switch from the fuel-led carburetion process to the air mass-led carburetion process parameters relating to an air path are set.
  12. A process for operating a diesel engine in accordance with one of the preceding claims,
    characterised in that
    the setting of the parameters influencing the engine torque takes the form of an adaptive regulation process or an adaptive control process.
  13. A diesel engine for carrying out a process in accordance with one of the preceding claims,
    characterised by
    an engine speed sensor (12) and/or an engine torque sensor (14), a throttle device (22) with a first actuator (20) in the induction path (42) and/or an exhaust gas recirculation device (36, 40) with an exhaust gas recirculation valve (26) with a second actuator (24) and an engine control unit (16) which is linked to the engine speed sensor (12) and/or the engine torque sensor (14) and to the first actuator (20) and the second actuator (24) and is designed for switching between lean operation and rich operation, for determining engine torque fluctuations and for regulating an engine torque, the engine torque being held constant by means of the engine torque regulation system during the switch between lean operation and rich operation.
  14. A diesel engine in accordance with claim 13,
    characterised by
    a supercharger (30) connected to the induction path (42) with a third actuator (28) which can be actuated by the engine control unit (16).
  15. A diesel engine in accordance with claim 13 or 14,
    characterised by
    a device (34) for changing an induction cross-section of each cylinder with a fourth actuator (32) which can be actuated by the engine control unit (16).
EP01931666A 2000-05-31 2001-04-28 Method for operating a diesel motor and a diesel motor Expired - Lifetime EP1285159B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10026806 2000-05-31
DE10026806A DE10026806C1 (en) 2000-05-31 2000-05-31 Operating diesel engine involves determining engine torque fluctuations during changeover and holding torque constant during changeover by adjusting parameters influencing torque
PCT/EP2001/004798 WO2001092706A1 (en) 2000-05-31 2001-04-28 Method for operating a diesel motor and a diesel motor

Publications (2)

Publication Number Publication Date
EP1285159A1 EP1285159A1 (en) 2003-02-26
EP1285159B1 true EP1285159B1 (en) 2005-03-30

Family

ID=7644109

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01931666A Expired - Lifetime EP1285159B1 (en) 2000-05-31 2001-04-28 Method for operating a diesel motor and a diesel motor

Country Status (5)

Country Link
US (1) US6857421B2 (en)
EP (1) EP1285159B1 (en)
JP (1) JP2003535261A (en)
DE (1) DE10026806C1 (en)
WO (1) WO2001092706A1 (en)

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Also Published As

Publication number Publication date
US6857421B2 (en) 2005-02-22
US20030150425A1 (en) 2003-08-14
JP2003535261A (en) 2003-11-25
EP1285159A1 (en) 2003-02-26
DE10026806C1 (en) 2001-09-20
WO2001092706A1 (en) 2001-12-06

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