CN115614167A - Method and device for controlling the gas temperature at the outflow of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation - Google Patents

Method and device for controlling the gas temperature at the outflow of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation Download PDF

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Publication number
CN115614167A
CN115614167A CN202210825619.0A CN202210825619A CN115614167A CN 115614167 A CN115614167 A CN 115614167A CN 202210825619 A CN202210825619 A CN 202210825619A CN 115614167 A CN115614167 A CN 115614167A
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China
Prior art keywords
air cooler
charge air
exhaust gas
temperature
gas temperature
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CN202210825619.0A
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Chinese (zh)
Inventor
B·希普
C·施韦泽
F·霍夫曼
M·勃兰特
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
    • F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
    • F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
    • 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
    • F02D41/0002—Controlling intake air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F02B29/0406—Layout of the intake air cooling or coolant circuit
    • F02B29/0437—Liquid cooled heat exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F02B29/0493—Controlling the air charge temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B47/00—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
    • F02B47/04—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only
    • F02B47/08—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only the substances including exhaust gas
    • 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
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
    • F02D41/0055—Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2409—Addressing techniques specially adapted therefor
    • F02D41/2422—Selective use of one or more tables
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/23—Layout, e.g. schematics
    • F02M26/25—Layout, e.g. schematics with coolers having bypasses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
    • F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
    • F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
    • F02D2021/083—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine controlling exhaust gas recirculation electronically
    • 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
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0406—Intake manifold pressure
    • 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
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0414—Air temperature
    • 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
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0418—Air humidity
    • 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
    • F02D2200/70—Input parameters for engine control said parameters being related to the vehicle exterior
    • 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
    • F02D2200/70—Input parameters for engine control said parameters being related to the vehicle exterior
    • F02D2200/703—Atmospheric pressure
    • 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
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
    • 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
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1448—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an exhaust gas pressure
    • 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
    • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
    • F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Abstract

Method for controlling the gas temperature at the outflow opening of a charge air cooler of an internal combustion engine having low-pressure exhaust gas recirculation, wherein the exhaust gas is recirculated back by low-pressure exhaust gas recirculation, wherein a consumption-optimized gas temperature at the outflow opening of the charge air cooler is determined for the internal combustion engine as a function of the current rotational speed and the current target cylinder charge, the consumption-optimized gas temperature is set by the charge air cooler in such a way according to a condensation avoidance strategy that it is continuously increased until the current ignition angle efficiency falls below a predeterminable ignition angle efficiency or exceeds a predeterminable maximum permissible gas temperature, wherein if the current ignition angle efficiency falls below the predeterminable ignition angle efficiency, the return guidance of the exhaust gas by low-pressure exhaust gas recirculation and/or the gas temperature at the outflow opening of the charge air cooler is reduced in order to avoid further moisture ingress as a result of the exhaust gas recirculated back by low-pressure exhaust gas recirculation.

Description

Method and device for controlling the gas temperature at the outflow of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation
Technical Field
The invention relates to a method and a device for controlling the gas temperature at the outlet of a charge air cooler of an internal combustion engine having low-pressure exhaust gas recirculation.
Background
The task of a charge air cooler in a supercharged internal combustion engine is to cool the air after compression and before supply to the combustion chamber in order to achieve an increase in the air density. More fuel can be converted and the power of the engine can be increased. In the case of a correspondingly high air humidity of the fresh air drawn in, cooling can lead to condensation. This effect is additionally intensified in systems with installed low-pressure exhaust gas recirculation, since a portion of the exhaust gas (which contains an additional share of the water from the combustion) is mixed with fresh air and then flows through the charge air cooler. In order to avoid damage to the engine due to excessive condensed water entering the combustion chamber or damage to the charge air cooler due to corrosion, the amount of condensation must be limited in the charge air cooler.
Condensation should not occur upstream of the compressor, for example in an AGR cooler or at the mixing location with fresh air, since otherwise the compressor wheel could be damaged by the impinging droplets.
Disclosure of Invention
The present invention relates to a method and a device for controlling the gas temperature at the flow outlet of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation, and to a computer program for implementing the method on a storage medium.
In a first aspect, the invention relates to a method for controlling the gas temperature at the outlet of a charge air cooler of a supercharged internal combustion engine having a low-pressure exhaust gas recirculation, wherein the exhaust gas is recirculated by means of the low-pressure exhaust gas recirculation, wherein a consumption-optimized gas temperature at the outlet of the charge air cooler is determined for the internal combustion engine as a function of the current rotational speed and the current target cylinder charge, wherein the gas temperature at the outlet of the charge air cooler is set by means of an adjustment of the charge air cooler in accordance with a condensation-avoiding strategy in such a way that the consumption-optimized gas temperature increases continuously until the current ignition angle efficiency falls below a predeterminable ignition angle efficiency or exceeds a predeterminable maximum permissible gas temperature, wherein if the current ignition angle efficiency falls below the predeterminable ignition angle efficiency, the recirculation of the exhaust gas by means of the low-pressure exhaust gas recirculation is reduced and/or the gas temperature at the outlet of the charge air cooler is reduced in order to avoid the entry of additional moisture as a result of the recirculation of the exhaust gas recirculated by means of the low-pressure exhaust gas.
The condensation can be set in a controlled manner in the charge air cooler by continuously increasing the gas temperature.
This method has particular advantages, namely: depending on the firing angle efficiency, an optimized strategy can be implemented for avoiding condensation in the charge air cooler. By defining the gas temperature at the outflow opening of the charge air cooler, the condensation can be set in a controlled manner in the charge air cooler. The back-directed exhaust rate by intervening in the low-pressure exhaust gas recirculation can prevent the formation of condensation of droplets at the compressor. Furthermore, damage to components, such as, for example, internal combustion engines, in the form of corrosion due to condensation, can be avoided or reduced.
Furthermore, the maximum permissible gas temperature that can be specified can correspond to the gas temperature for which a full load demand of the internal combustion engine is required at the current rotational speed.
The maximum permissible gas temperature is advantageously defined by the full load requirement at the current rotational speed in order to meet optimum operation of the internal combustion engine. Thereby, the necessary cooling performance can be provided by the charge air cooler.
The load-point-dependent gas temperature for optimum fuel consumption can be increased by condensation management up to the gas temperature for maximum engine power.
Furthermore, a predeterminable firing angle efficiency can be determined as a function of the current rotational speed and the current target cylinder charge, and the condensation avoidance strategy is deactivated if the current firing angle efficiency is lower than the predeterminable firing angle efficiency.
This is particularly advantageous, since the condensation can be controlled particularly easily for the internal combustion engine by means of the firing angle efficiency. The ignition angle efficiency represents a particularly advantageous control variable for the internal combustion engine.
Furthermore, the ignition angle efficiency that can be specified can correspond to the ignition angle efficiency at which the knock limit value occurs, preferably to the ignition angle efficiency before the knock limit value is reached.
In this case, the knock limit value of the combustion of the internal combustion engine can be used to control the method or the ignition angle efficiency before the knock limit value is reached.
Furthermore, in the activated condensation avoidance strategy, the consumption-optimized gas temperature for the charge air cooler is increased stepwise by an adjustment difference, wherein the adjustment difference is determined as a function of the difference between the dew point temperature and the corrected consumption-optimized gas temperature and the water rate (Wasserate) for the charge air cooler.
Such a regulation has particular advantages, namely: condensation can be controlled in the charge air cooler. In this case, the adjustment difference is continuously increased as long as the condensation avoidance strategy is active.
Furthermore, the dew point temperature can be determined from the second saturated vapor pressure and the relative humidity downstream of the charge air cooler and upstream of the throttle valve.
Furthermore, the water rate for the charge air cooler can be determined from the first water amount.
Furthermore, the first amount of water can be determined from the mass flow of gas through the charge air cooler, the second pressure downstream of the charge air cooler and upstream of the throttle, and the second specific humidity downstream of the compressor and upstream of the charge air cooler.
Furthermore, the second specific humidity can be found from the first specific humidity at the location of the mixing location, the first pressure and the first saturated vapor pressure downstream of the compressor and upstream of the charge air cooler.
Furthermore, the relative humidity can be determined from the second pressure and a second saturated vapor pressure downstream of the compressor and upstream of the charge air cooler.
Furthermore, a second saturated vapor pressure can be determined as a function of a second temperature downstream of the charge air cooler and upstream of the throttle valve.
Furthermore, the first saturated vapor pressure can be determined from the first temperature downstream of the compressor and upstream of the charge air cooler.
In a further aspect, the invention relates to a device, in particular a controller, and a computer program which is configured, in particular programmed, for carrying out one of the methods. In a further aspect, the invention relates to a machine-readable storage medium on which the computer program is stored.
Drawings
The invention is explained in more detail below with reference to the figures and according to embodiments. Wherein:
figure 1 shows a schematic view of an internal combustion engine with low-pressure exhaust gas recirculation,
fig. 2 shows an exemplary method sequence for controlling the gas temperature at the outlet of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation.
Detailed Description
Fig. 1 shows a schematic representation of an internal combustion engine 25 having a fresh air system 48, by means of which combustion air is supplied to the internal combustion engine 25, and an exhaust system 49, by means of which exhaust gases 51 are discharged from the internal combustion engine 25 in the flow direction.
In the fresh air installation 48, the following arrangement is made, viewed in the flow direction of the fresh air 50: determining pressurep 0 Pressure sensing ofDevice 1, determining temperatureT 0 Temperature sensor 2, air filter 3, air mass thermal film sensor (HFM) 5, determining temperatureT 10 Temperature sensor 6, determining pressurep 10 Pressure sensor 7, fresh air throttle 8, determination pressurep 11 Pressure sensor 9, determining temperatureT 11 Temperature sensor 10, compressor 12 of an exhaust-gas turbocharger 47, determining a temperatureT 20 And pressurep 20 Pressure and temperature sensor 13, having a volumeV 21 Charge air cooler 14, determining the temperatureT 21 Temperature sensor 16, determining pressurep 21 Pressure sensor 17, throttle valve 19, determining pressurep 22 Pressure sensor 20, and determining temperatureT 22 The temperature sensor 21. The specified values can be present, for example, as sensor values or as model values. In a preferred embodiment, the pressure sensor 1 determines the ambient pressure and the temperature sensor 2 determines the ambient temperature. A fresh air throttle 8 and an ND-AGR-valve 40 for throttling the ND-AGR-mass flow are installed.
Furthermore, the charge air cooler 14 is connected to a coolant system. The coolant system consists here of a controllable coolant pump and a coolant circuit, wherein the coolant is pumped via a cooler 60 connected to the charge air cooler 14. The temperature control of the charge air cooler 14 is carried out by means of a model calculated on the control unit 100, the control unit 100 preferably controlling the coolant pump to control the flow rate or the coolant mass flow.
Furthermore, a fan for cooling the cooler 60 can be installed at the cooler 60, wherein the controller 100 adapts the speed of the fan to the desired coolant temperature. In an alternative embodiment, the cooler 60 can have an adjustable diaphragm structure which covers the cooler 60, wherein the diaphragm structure can be opened or closed by means of the control 100 in order to adjust the coolant temperature.
Furthermore, a 3-way valve 61 can be installed in the coolant circuit, wherein a bypass around the charge air cooler 14 is produced by means of the 3-way valve 61, so that the coolant circuit no longer runs through the cooler 60. Here, the 3-way valve 61 is controlled by the controller 100 to regulate the coolant temperature.
In the exhaust system 49, the following arrangement is made in the flow direction of the exhaust gas 51, starting from the internal combustion engine 25: determining pressurep 3 Pressure sensor 26, determining temperatureT 3 A temperature sensor 27, an exhaust gas turbine 30, a lambda probe 56 for determining the air-fuel ratio in the exhaust system 49, an oxidation catalyst (DOC) 31, a nitrogen oxide storage catalyst 32, a Particle Filter (PF) 33, a defined temperatureT 50 Temperature sensor 34, determining pressurep 50 The pressure sensor 35. In addition, the value of the engine speedn eng And the amount of fuel suppliedm fuel Provided as a sensor value or model value, for example, by the controller 100.
Downstream of the DPF 33, that is to say on the low-pressure side of the exhaust system 49, a low-pressure exhaust gas recirculation line (ND-AGR line) 41 branches off from the exhaust system 49, which leads back into the fresh air system 48 upstream of the compressor 12 and downstream of the air filter 3 or the air mass sensor 5.
Along the ND-AGR line 41, the following arrangement is made in the flow direction of the mass flow, starting from the branch of the exhaust system 49: ND-AGR-COOLER 37 WITH ND-AGR-BYPASS 38, TEMPERATURE DETERMINATIONT LPEGR The temperature sensor 39. The pressure drop across the ND-AGR valve 40 can be determined by means of the differential pressure sensor 42. The specified values can be present, for example, as sensor values or as model values. Alternatively or additionally, the exhaust valve 8 can also be installed in the exhaust system 49 instead of the fresh air throttle valve 8. This position is also referred to as the mixing position 43, in which the returned exhaust air 51 is mixed with fresh air 50 from the air supply system.
In this case, the pressure is preferably determined in a region downstream of the mixing point 43 and upstream of the compressor 12p 11 And temperatureT 11 . Furthermore, the pressure is preferably determined downstream of the compressor 12 and upstream of the charge-air cooler 14p 20 And temperatureT 20 。
The pressure is preferably determined downstream of the charge air cooler 14 and upstream of the throttle flap 19p 21 And temperatureT 21 . Furthermore, the pressure is determined downstream of the throttle valve 19 and upstream of the internal combustion engine 25p 22 And temperatureT 22 。
An exemplary flow of the method is shown in fig. 2. In a first step 200, a first temperature is read in by the controller 100T 20 And according to a first model stored on the controller 100M 1 To find the first saturated vapor pressurep Sat,20 . Alternatively, the first characteristic map can also be usedK 1 According to the first temperatureT 20 To find the saturated steam pressurep Sat,20 Wherein the saturation pressure is stored in a characteristic diagram as a function of the temperatureK 1 In (1). Downstream of the compressor 12 and upstream of the charge-air cooler 14, a first temperature is determinedT 20 。
Subsequently in step 205, according to a second model stored on the controller 100M 2 From the first saturated steam pressure determined in step 200p Sat,20 First pressurep 20 And a first specific humidityφ 12 To obtain a second specific humidityφ 20,mdl . Here, the second specific humidityφ 20,mdl Corresponding to the particular humidity modeled at a location downstream of the compressor 12 and upstream of the charge air cooler 14.
The first pressure is preferably determined between the compressor 12 and the charge air cooler 14p 20 . Preferably at mixing location 43A first specific humidity is determined downstream of the junction point 43 and upstream of the compressor 12φ 12 。
Alternatively, it is possible to use a second characteristic mapK 2 According to the first saturated steam pressurep Sat,20 First pressurep 20 And a first specific humidityφ 12 To obtain a second specific humidityφ 20,mdl Wherein a specific humidityφ 20,mdl Stored in a second characteristic diagram according to these variablesK 2 In (1).
In step 210, according to a third model stored on the controller 100M 3 From the second temperatureT 21 Calculating a second saturated steam pressurep Sat,21 。
The second temperature is determined downstream of the charge air cooler 14 and upstream of the throttle valve 19T 21 。
Alternatively, it is possible to use a third family of characteristic curvesK 3 From the second temperatureT 21 Calculating a second saturated vapor pressurep Sat,21 Wherein the second saturated vapor pressurep Sat,21 According to the second temperatureT 21 Stored in a third characteristic diagram family K 3 In (1).
In step 215, the second saturation steam pressure determined in step 210p Sat,21 Second pressurep 21 And the second specified humidity determined in step 205φ 20,mdl Evaluating from a fourth model stored on the controller 100M 4 Of the modeled relative humidityφ 21,mdl . At the second pressurep 21 Corresponding to the pressure at a location downstream of the charge air cooler 14 and upstream of the throttle valve 19. Here, the second relative humidityφ 21,mdl Corresponding to positions downstream of the charge air cooler 14 and upstream of the throttle valve 19Relative humidity.
Alternatively, it is possible to use a fourth characteristic mapK 4 From the found second saturated steam pressurep Sat,21 A second pressurep 21 And a second specific humidityφ 20,mdl Determining a modeled relative humidityφ 21,mdl Wherein the modeled relative humidityφ 21,mdl Stored in a fourth characteristic diagram according to these variablesK 4 In (1).
Subsequently in step 220, by means of a fifth model stored on the controller 100M 5 From the second temperatureT 21 Second pressurep 21 And a second specific humidityφ 20,mdl And a gas mass flow via the charge air cooler 14dm LLK To obtain a first water quantitym H2O,LLK 。
Here, the first amount of waterm H2O,LLK Corresponding to the amount of water stored in the charge air cooler 14.
Alternatively, it is possible to use a fifth family of characteristic curvesK 5 From the second temperatureT 21 A second pressurep 21 And a second specific humidityφ 20,mdl And mass flow of gasdm LLK To obtain a first water quantitym H2O,LLK Wherein the first amount of waterm H2O,LLK Stored in a fifth characteristic diagram according to these variablesK 5 In (1).
In step 225, the first quantity of water determined in step 220 is checkedm H2O,LLK Whether a predeterminable maximum permissible water quantity is exceededm max . If the first amount of waterm H20,LLK Water amount lower than maximum allowablem max Then according to the first water quantitym H20,LLK Calculating water ratiorat H20,LLK And the method continues in step 230.
If the first amount of waterm H20,LLK Exceeding the maximum allowable water quantitym max Then according to the maximum allowable water quantitym max To obtain the first water raterat H20,LLK And the method continues in step 230.
In step 230, it is checked that the ignition angle efficiency of the combustion of the internal combustion engine 25η ZW Whether the ignition angle is at a predeterminable ignition angle efficiency dependent on the operating pointη ZW,Lim Above (b). Furthermore, the consumption-optimized gas temperature is determined from the current engine operating pointT LLKDs,Eco . In this case, the rotational speed is determinedn eng And target cylinder fillrl soll By a sixth model stored on the controller 100M 6 To find the engine operating point. Alternatively, it is possible to use a sixth family of characteristic curvesK 6 From the rotational speedn eng And target cylinder fillrl soll To find the consumption optimized gas temperatureT LLKDs,Eco Wherein the consumption-optimized gas temperatureT LLKDs,Eco Stored in a sixth characteristic diagram according to these variablesK 6 In (1).
If the ignition angle is efficientη ZW Efficiency exceeding a predefinable ignition angle dependent on the operating pointη ZW,Lim Then as a strategy for avoiding condensation effects in the fresh air installation 48, an increase in the temperature of the gas supplied to the internal combustion engine 25 is carried out and the method is continued in step 240.
If the ignition angle is efficientη ZW Efficiency below a predefinable ignition angle dependent on the operating pointη ZW,Lim Then the method continues in step 235 and the low pressure egr rate is reducedrat LPEGR,Lim In order to avoid condensation effects in the fresh air installation 48, preferably at the compressor 14, and in order to reduce condensation effects in the charge air cooler 15.
In step 235, deactivation of the condensation avoidance strategy is carried out in the controller 100 and a reduction of the target low pressure exhaust gas recirculation rate is performedrat LPEGR,Soll . This is preferably done by targeting a low-pressure exhaust gas recirculation raterat LPEGR,Soll Limited to a predeterminable low-pressure exhaust gas recirculation raterat LPEGR,lim The above is performed. Preferred target Low-pressure exhaust gas Recirculation Raterat LPEGR,Soll The setting can be made by fully closing the ND-AGR-valve 40. In this case, the limitation of the low-pressure exhaust gas recirculation rate is preferably carried out for a long time until the firing angle efficiencyη ZW In addition, the efficiency of the ignition angle that can be specified in dependence on the operating point is exceededη ZW,Lim . The process continues in step 255, wherein the consumption-optimized gas temperatureT LLKDs,Eco Corresponding to the corrected gas temperatureT LLKDs,EcoCtl 。
In step 240, the second saturation steam pressure determined in step 210 is used as the steam pressurep Sat,21 And the relative humidity modeled in step 215φ 21,mdl According to a seventh model stored on the controller 100M 7 To find the dew point temperatureT Dew,21 。
Alternatively, it is possible to use a seventh family of characteristic curvesK 7 From the second saturated steam pressurep Sat,21 And modeled relative humidityφ 21,mdl To find the dew point temperatureT Dew,21 Wherein the dew point temperatureT Dew,21 Stored in a seventh characteristic diagram according to these variablesK 7 In (1).
Then in step 245, the water rate is determined according to the water rate determined in step 225rat H2O,LLK And at the determined dew point temperatureT Dew,21 With modified consumption-optimised gas temperatureT LLKDs,EcoCtl Difference value therebetweenDiffTo find out the temperature change deltaT Kond . After repairPositive consumption optimized gas temperatureT LLKDs,EcoCtl The data can be loaded in the first computational grid with predefinable values or with zeros. Preferred water raterat H2O,LLK Sum and differenceDiffIs fed to an integrator I and the temperature change Delta is determined therefromT Kond 。
If the water rate is foundrat H2O,LLK Below a first predeterminable threshold valueS 1 Then the temperature change ΔT Kond The reduction is carried out in predeterminable temperature steps and therefore allows more condensation.
If the water rate is foundrat H2O,LLK Exceeds a first threshold valueS 1 Then the temperature change ΔT Kond The increase is carried out in accordance with a predeterminable temperature step in order to evaporate the condensate. The gas temperature at the outflow opening of the charge air cooler 14 is adapted in particular by presetting the coolant mass flow and/or the coolant temperature of the charge air cooler 14.
Subsequently, in step 250, the determined temperature change Δ is usedT Kond Is added to the consumption optimized gas temperature found in step 230T LLKDs,Eco And obtaining a corrected gas temperatureT LLKDs,EcoCtl 。
In step 255, the corrected gas temperature determined in step 250 is checkedT LLKDs,EcoCtl Whether a predeterminable maximum permissible gas temperature is exceededT LLKDs,Lim . In this case, a maximum permissible gas temperature can be predefinedT LLKDs,Lim Corresponding to the gas temperature which is required in order to obtain the current rotational speed of the internal combustion engine 25n eng The full load requirement is executed in case of (2).
If the found corrected gas temperatureT LLKDs,EcoCtl Exceeding a predeterminable maximum permissible gas temperatureT LLKDs,Lim Then will then be passed throughCorrected gas temperatureT LLKDs,EcoCtl Limited to the maximum allowable gas temperatureT LLKDs,Lim And as the desired target gas temperatureT LLKDs,Soll And (6) outputting.
If the found corrected gas temperatureT LLKDs,EcoCtl Below a predeterminable maximum permissible gas temperatureT LLKDs,Lim Then the found corrected gas temperature is usedT LLKDs,EcoCtl As desired target gas temperatureT LLKDs,Soll And (6) outputting.
In step 260, the desired target gas temperatureT LLKDs,Soll The model for the coolant system on the control unit 100 is preferably set by controlling the coolant mass flow and/or by adapting the coolant temperature.
The coolant temperature can be adapted, for example, by adjusting a fan which flows through the cooler grate with air.
In an alternative embodiment, an adjustable diaphragm covering the cooler grate can be opened or closed in order to further adjust the coolant temperature.
Subsequently, the method is continued from the beginning in step 200.

Claims (15)

1. For controlling the gas temperature at the outlet of a charge air cooler (14) of an internal combustion engine (25) ((T LLKDs，Soll ) Method for controlling an internal combustion engine having a low-pressure exhaust gas recirculation (41), wherein exhaust gas is recirculated by means of the low-pressure exhaust gas recirculation (41), wherein the exhaust gas is recirculated as a function of the current rotational speed (C:)n eng ) And current target cylinder fill: (rl soll ) Determining a consumption-optimized gas temperature at the outlet of the charge air cooler (14) for the internal combustion engine (25) ((T LLKDs,Eco ) Wherein the charge air cooler (14) is so set by adjusting it according to a condensation avoidance strategyTemperature of gas at the flow outlet of the charge air cooler (14) ((T LLKDs,Soll ) Such that the consumption-optimized gas temperature(s) ((T LLKDs,Eco ) Continuously increasing until the current firing angle efficiency (η ZW ) Less than a predefinable firing angle efficiency (η ZW,Lim ) Or a predeterminable maximum permissible gas temperature (f) is exceededT LLKDs,Lim ) Wherein if the current firing angle efficiency (A), (B) is greater thanη ZW,Lim ) Less than the predeterminable firing angle efficiency (η ZW,Lim ) Reducing the return guidance of exhaust gas by the low-pressure exhaust gas recirculation (41) and/or reducing the gas temperature at the outlet of the charge air cooler (14) ((T LLKDs,Soll ) In order to avoid further moisture ingress due to exhaust gases being recirculated (41) by the low-pressure exhaust gas recirculation.
2. Method according to claim 1, characterized in that the predeterminable maximum permissible gas temperature: (T LLKDs,Lim ) Corresponds to the gas temperature for which (at) the current rotational speedn eng ) A full load demand of the internal combustion engine (25) is required.
3. Method according to claim 1, characterized in that (a) is performed depending on the current rotational speedn eng ) And the current target cylinder fill (c) ((c))rl soll ) To obtain a predefinable ignition angle efficiency (η ZW,lim ) And if the current firing angle is efficient (a)η ZW ) Less than the predeterminable firing angle efficiency (η ZW,lim ) The condensation avoidance strategy is deactivated.
4. The method of claim 3, wherein the step of removing the metal oxide layer comprises removing the metal oxide layer from the metal oxide layerIn that the predeterminable firing angle efficiency (A)η ZW,Lim ) The ignition angle efficiency corresponding to where the knock limit occurs, preferably the ignition angle efficiency before the knock limit is reached.
5. Method according to claim 1, characterized in that in the activated condensation avoidance strategy the difference (Δ) is adjusted stepwiseT Kond ) To increase the consumption-optimized gas temperature for the charge air cooler (14) by a certain extent: (T LLKDs,Eco ) Wherein, according to the dew point temperature (C) ((C))T Dew,21 ) With corrected consumption-optimized gas temperature (T LLKDs,EcoCtl ) Difference between and water rate for the charge air cooler (14) ((rat H2O,LLK ) To find the regulating difference value (delta)T Kond ）。
6. A method according to claim 5, characterised in that (C) is adjusted in dependence on the relative humidity downstream of the charge air cooler (14) and upstream of a throttle valve (19) (C)φ 21,mdl ) And a second saturated vapor pressure（p Sat,21 ) To find the dew point temperature (T Dew,21 ）。
7. The method of claim 5, wherein the first amount of water (A), (B), and (C) is based on the first amount of waterm H2O,LLK ) To determine the water rate for the charge air cooler (14) ((rat H2O,LLK ）。
8. Method according to claim 7, characterized in that (C) is adjusted according to the gas mass flow through the charge air cooler (14)dm LLK ) A second pressure (p) downstream of the charge air cooler (14) and upstream of the throttle valve (19) 21 ) Downstream of the compressor (12) and the charge air cooler(14) Upstream of a second specific humidity of (b)φ 20,mdl ) To obtain the first water quantity (m H2O,LLK ）。
9. Method according to claim 7, characterized in that according to a first specific humidity at the location of the mixing location (43), (43)φ 12 ) First pressure (p 20 ) And a first saturated vapor pressure downstream of the compressor (12) and upstream of the charge air cooler (14) ((p Sat,20 ) To find the second specific humidity (φ 20,mdl ）。
10. The method of claim 5, wherein (a) is adjusted according to the second pressurep 21 ) And a second saturated vapor pressure downstream of the compressor (12) and upstream of the charge air cooler (14) ((p Sat,21 ) To find the relative humidity (φ 21,mdl ）。
11. The method of claim 9, according to a first temperature(s) downstream of the compressor (12) and upstream of the charge air cooler (14)T 20 ) To find the first saturated vapor pressure (c: (b))p Sat,20 ）。
12. The method of claim 10, according to a second temperature (C) downstream of the charge air cooler (14) and upstream of the throttle valve (19)T 21 ) To find the second saturated vapor pressure (c: (b))p Sat,21 ）。
13. Computer program arranged to perform the method according to any of claims 1 to 12.
14. Electronic storage medium with a computer program according to claim 13.
15. Device, in particular controller, designed to implement the method according to claims 1 to 12.
CN202210825619.0A 2021-07-15 2022-07-14 Method and device for controlling the gas temperature at the outflow of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation Pending CN115614167A (en)

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DE102021207547.9A DE102021207547A1 (en) 2021-07-15 2021-07-15 Method and device for controlling a gas temperature at the outlet of a charge air cooler of an internal combustion engine with low-pressure exhaust gas recirculation
DE102021207547.9 2021-07-15

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