WO2009020418A1 - A surge control method - Google Patents

A surge control method Download PDF

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Publication number
WO2009020418A1
WO2009020418A1 PCT/SE2008/050545 SE2008050545W WO2009020418A1 WO 2009020418 A1 WO2009020418 A1 WO 2009020418A1 SE 2008050545 W SE2008050545 W SE 2008050545W WO 2009020418 A1 WO2009020418 A1 WO 2009020418A1
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WO
WIPO (PCT)
Prior art keywords
engine
egr valve
compressor
controlling
variable turbine
Prior art date
Application number
PCT/SE2008/050545
Other languages
French (fr)
Inventor
Mats Jennische
Mikael Persson
Original Assignee
Scania Cv Ab (Publ)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scania Cv Ab (Publ) filed Critical Scania Cv Ab (Publ)
Priority to DE112008001300.4T priority Critical patent/DE112008001300B4/en
Publication of WO2009020418A1 publication Critical patent/WO2009020418A1/en

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Classifications

    • 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
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
    • 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
    • F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
    • 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
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • F02B37/12—Control of the pumps
    • F02B37/24—Control of the pumps by using pumps or turbines with adjustable guide vanes
    • 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
    • F02B39/00—Component parts, details, or accessories relating to, driven charging or scavenging pumps, not provided for in groups F02B33/00 - F02B37/00
    • F02B39/16—Other safety measures for, or other control of, pumps
    • 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]
    • 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
    • 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
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/12—Introducing corrections for particular operating conditions for deceleration
    • 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
    • F02M26/09—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine
    • F02M26/10—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F04D27/0246—Surge control by varying geometry within the pumps, e.g. by adjusting vanes
    • 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
    • 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
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to a method and a system for controlling an engine having a turbo charger and provided with an EGR valve.
  • Diesel engines for use in heavy vehicles such as trucks and buses are sometimes provided with a turbo charger that may comprise a Variable Turbine Geometry (VTG) also termed Variable Geometry Turbocharger or Variable Geometry Turbine (VGT).
  • VVT Variable Turbine Geometry
  • Such an engine can typically be provided with an EGR (Exhaust Gas Recirculation) valve.
  • EGR exhaust Gas Recirculation
  • Other engines for other uses may also be provided with a turbo charger in combination with EGR.
  • EGR exhaust Gas Recirculation
  • One reason for employing EGR technology is that it facilitates fulfillment of emission requirements for i.a. diesel engines.
  • a turbo charger comprises a turbine with a variable geometry powering a compressor for feeding the air intake of the combustion engine with compressed air. If the difference in pressure upstream and downstream the compressor, i.e. the pressure difference over the compressor is high, the compressor may be unable to maintain the pressure difference and there will be a reverse gas mass flow through the compressor. This is sometimes termed surging.
  • One scenario that may cause surging is when there is a rapid decrease of fuel feed.
  • the turbine powering the compressor may experience a rapid speed drop resulting in a rapid power drop of the compressor.
  • the turbo pressure downstream the compressor may then be high and at the same time the compressor may be operating at low power. If this occurs there is a risk that the high turbo pressure cannot be maintained and there will be a reverse gas mass flow through the compressor, surging.
  • a reverse gas mass flow through the compressor is highly unwanted for a number of different reasons. Firstly, such an event will generate a bang having a fairly loud volume, which of course is disturbing for a driver of a vehicle propelled by the engine and people in the vicinity of the vehicle.
  • the compressor of the turbo charger will experience an abnormal operation condition that may shorten the life time of the compressor or even directly damage the compressor.
  • the compressor of the turbo charger will experience an abnormal operation condition that may shorten the life time of the compressor or even directly damage the compressor.
  • the control unit of an engine for powering a motor vehicle such as a truck or a bus is provided with a detector for detecting a rapid decrease in fuel feed. If the negative fuel feed rate is below some predetermined threshold value, the control unit triggers a mode where a control unit is adapted to prevent surging through the turbo compressor.
  • the control system when the turbo charger is provided with a Variable Turbine Geometry (VTG), the control system begins to control the VTG to generate a high power when in the mode for preventing compressor surging. The high power generated by the turbine will prevent a fast power drop which could lead to surging.
  • the control system begins to control an EGR valve to a more open position to let gas flow in the reverse direction in the EGR path when in the mode for preventing compressor surging, thereby lowering the charge gas pressure so that surging through the turbo compressor can be prevented.
  • control system stores a map comprising optimal EGR valve positions and optimal closed Variable Turbine Geometry positions for different engine operation states, and controls the Variable Turbine Geometry and / or the EGR valve position to the positions corresponding to the current engine operation conditions of the map.
  • the risk for surging can be further reduced.
  • control method in accordance with the invention will result in smooth reduction in the charge gas pressure, thus preventing surging through the turbo compressor, which otherwise may occur in the event of a rapid fuel feed reduction.
  • - Fig. 1 is a general partial view of engine including a turbo charger with VTG and EGR.
  • Fig. 2 is a flow chart illustrating steps performed in a control procedure when controlling a combustion engine preventing a reverse gas mass flow in accordance with one embodiment.
  • FIG. 3 is a flow chart illustrating steps performed in a control procedure when controlling a combustion engine preventing a reverse gas mass flow in accordance with another embodiment.
  • Fig.l selected parts of an engine 100 of a motor vehicle 10 is schematically depicted.
  • the engine depicted in Fig. 1 can for example be designed to be part of a truck or any other heavy vehicle such as a bus or the like.
  • the exemplary engine 100 in Fig. 1 is a diesel engine provided with a turbocharger and having five cylinders 105.
  • the turbo charger can be of any type for example a turbo charger having a Variable Turbine Geometry (VTG) or another turbo charger having a controllable turbine or not having a controllable turbine.
  • the turbo charger comprises a compressor 102 driven by a turbine 103.
  • the engine comprises an EGR valve 107.
  • the EGR valve 107 controls the amount of exhaust gas that is re-circulated to the air inlet of the engine 100.
  • the engine is controlled by an electronic control unit (ECU) 106.
  • the ECU 106 is connected to the engine to control the engine.
  • the ECU can be adapted to control the EGR valve position and the position of the VTG and also other parameters used for controlling the engine.
  • sensors provide sensor signals to the ECU 106. Using the sensor signals, the ECU 106 exercises control of the engine using some programmed computer instructions or similar means.
  • the programmed computer instructions are provided in the form of a computer program product 110 stored on a readable digital storage medium 108, such as memory card, a Read Only Memory (ROM) a Random Access Memory (RAM), an EPROM, an EEPROM or a flash memory.
  • a flow chart illustrating steps performed in a control procedure performed by an ECU when controlling an engine provided with a VTG to prevent a reverse gas mass flow through a turbo compressor of the engine is shown.
  • the ECU detects a rapid decrease in fuel feed, i.e. the fuel rate change is determined to be below some pre- determined level.
  • the ECU switches control mode and proceeds to a second step 203.
  • the position of the VTG is controlled to generate a maximum turbine speed in order to aid the compressor in maintaining the turbo pressure.
  • the VTG position that the control system is adapted to control to maximize the turbine power / turbine speed can for example be given by a map storing an optimal closed VTG position providing a maximum turbine speed for each different state that the engine can operate in. Because surging most often occurs at high engine load and within a relatively narrow engine speed range, the control system can be adapted to control the VTG to the position corresponding to maximum power at those conditions. In other words, the control system can be simplified to adapt the VTG position providing a maximal turbine power / turbine speed for one gas mass flow, i.e. the gas mass flow corresponding to the operational condition where surging is likely to occur.
  • a third step 205 the ECU checks if a condition for exiting the mode for preventing a reverse gas mass flow through the turbo compressor is fulfilled. If so the procedure returns to step 201, via a fourth step 207 where the control system is reset to the original, regular, control mode, else the procedure stays in the mode for preventing reverse gas mass flow through the turbo compressor and the procedure returns to step 203.
  • a flow chart illustrating steps performed in a control procedure performed by an ECU when controlling an engine provided with an EGR system to prevent a reverse mass flow through a turbo compressor of the engine in accordance with another embodiment of the present invention is shown.
  • the ECU detects a rapid decrease in fuel feed, i.e. the fuel rate change is determined to be below some pre-determined level.
  • the ECU switches control mode and proceeds to a second step 303.
  • the EGR valve is opened to a more open position in order to reduce the turbo pressure by creating another gas outlet path via a reverse gas mass flow through the EGR path.
  • a third step 305 the ECU checks if a condition for exiting the mode for preventing a reverse gas mass flow through the turbo compressor is fulfilled. If so the procedure returns to step 301 via a fourth step 307 where the control system is reset to the original, regular, control mode, else the procedure stays in the mode for preventing reverse gas mass flow through the turbo compressor and the procedure returns to step 203.
  • the condition used to exit the mode for preventing a reverse gas mass flow through the turbo charger can for example be a determination that the negative fuel rate change is determined to be above some pre-determined level. The level can be but does not have to be the same level where the mode for preventing a reverse gas mass flow through the turbo charger is triggered.
  • the control systems as described above in conjunction with Figs. 2 and 3 are combined.
  • the ECU upon detection of a strong negative fuel decrease rate in an engine provided with both a VTG and a an EGR system, the ECU both controls the VTG to a position generating a maximum turbine speed in order to aid the compressor in maintaining the turbo pressure and controls the EGR valve to a more open position in order to reduce the turbo pressure by creating another gas outlet path via a reverse gas mass flow through the EGR path.
  • the control system can be adapted to take into account the higher exhaust gas pressure generated by a more closed VTG position.
  • the control system can be adapted to take into account the higher exhaust gas pressure generated by a more closed VTG position.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Supercharger (AREA)

Abstract

In a method and a system for controlling a combustion engine powering a motor vehicle having a turbo charger and an EGR system the control system is adapted to detecting a strong negative fuel rate exceeding a pre-determined threshold value (301), and controlling the EGR valve to a more open position (303) for letting charge gas exit through the EGR path thereby reducing the risk for surging in the compressor of the turbo charger.

Description

A SURGE CONTROL METHOD
TECHNICAL FIELD
The present invention relates to a method and a system for controlling an engine having a turbo charger and provided with an EGR valve.
BACKGROUND
Diesel engines for use in heavy vehicles such as trucks and buses are sometimes provided with a turbo charger that may comprise a Variable Turbine Geometry (VTG) also termed Variable Geometry Turbocharger or Variable Geometry Turbine (VGT). Such an engine can typically be provided with an EGR (Exhaust Gas Recirculation) valve. Other engines for other uses may also be provided with a turbo charger in combination with EGR. One reason for employing EGR technology is that it facilitates fulfillment of emission requirements for i.a. diesel engines.
A turbo charger comprises a turbine with a variable geometry powering a compressor for feeding the air intake of the combustion engine with compressed air. If the difference in pressure upstream and downstream the compressor, i.e. the pressure difference over the compressor is high, the compressor may be unable to maintain the pressure difference and there will be a reverse gas mass flow through the compressor. This is sometimes termed surging.
One scenario that may cause surging is when there is a rapid decrease of fuel feed. In such a scenario the turbine powering the compressor may experience a rapid speed drop resulting in a rapid power drop of the compressor. The turbo pressure downstream the compressor may then be high and at the same time the compressor may be operating at low power. If this occurs there is a risk that the high turbo pressure cannot be maintained and there will be a reverse gas mass flow through the compressor, surging. A reverse gas mass flow through the compressor is highly unwanted for a number of different reasons. Firstly, such an event will generate a bang having a fairly loud volume, which of course is disturbing for a driver of a vehicle propelled by the engine and people in the vicinity of the vehicle. Secondly, the compressor of the turbo charger will experience an abnormal operation condition that may shorten the life time of the compressor or even directly damage the compressor. Thirdly, there will be a drop in turbo pressure resulting in an instant drop in torque generated by the engine, which will be felt by the driver of the motor vehicle.
It is therefore desirable to avoid a reverse gas mass flow through the compressor of a turbo charged engine powering a motor vehicle. Hence there exists a need for a method of controlling a turbo charged combustion engine which prevents a reverse mass flow through the compressor of the turbo charger.
SUMMARY
It is an object of the present invention to provide a method and a system that is able to prevent a reverse gas mass flow through the compressor of a turbo charged combustion engine for powering a motor vehicle such as a truck or a bus.
This object and others are obtained by the method, system and computer program product as set out in the appended claims. Thus, in order to prevent a reverse gas mass flow through a compressor of a turbo charged combustion engine, the control unit of an engine for powering a motor vehicle such as a truck or a bus is provided with a detector for detecting a rapid decrease in fuel feed. If the negative fuel feed rate is below some predetermined threshold value, the control unit triggers a mode where a control unit is adapted to prevent surging through the turbo compressor.
In one embodiment, when the turbo charger is provided with a Variable Turbine Geometry (VTG), the control system begins to control the VTG to generate a high power when in the mode for preventing compressor surging. The high power generated by the turbine will prevent a fast power drop which could lead to surging. In one embodiment the control system begins to control an EGR valve to a more open position to let gas flow in the reverse direction in the EGR path when in the mode for preventing compressor surging, thereby lowering the charge gas pressure so that surging through the turbo compressor can be prevented.
In one embodiment the control system stores a map comprising optimal EGR valve positions and optimal closed Variable Turbine Geometry positions for different engine operation states, and controls the Variable Turbine Geometry and / or the EGR valve position to the positions corresponding to the current engine operation conditions of the map. Hereby the risk for surging can be further reduced.
Using the control method in accordance with the invention will result in smooth reduction in the charge gas pressure, thus preventing surging through the turbo compressor, which otherwise may occur in the event of a rapid fuel feed reduction.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described in more detail by way of non-limiting examples and with reference to the accompanying drawings, in which:
- Fig. 1 is a general partial view of engine including a turbo charger with VTG and EGR.
- Fig. 2 is a flow chart illustrating steps performed in a control procedure when controlling a combustion engine preventing a reverse gas mass flow in accordance with one embodiment.
- Fig. 3 is a flow chart illustrating steps performed in a control procedure when controlling a combustion engine preventing a reverse gas mass flow in accordance with another embodiment.
DETAILED DESCRIPTION
In Fig.l selected parts of an engine 100 of a motor vehicle 10 is schematically depicted. The engine depicted in Fig. 1 can for example be designed to be part of a truck or any other heavy vehicle such as a bus or the like. The exemplary engine 100 in Fig. 1 is a diesel engine provided with a turbocharger and having five cylinders 105. The turbo charger can be of any type for example a turbo charger having a Variable Turbine Geometry (VTG) or another turbo charger having a controllable turbine or not having a controllable turbine. The turbo charger comprises a compressor 102 driven by a turbine 103. Furthermore the engine comprises an EGR valve 107. The EGR valve 107 controls the amount of exhaust gas that is re-circulated to the air inlet of the engine 100.
The engine is controlled by an electronic control unit (ECU) 106. The ECU 106 is connected to the engine to control the engine. For example, the ECU can be adapted to control the EGR valve position and the position of the VTG and also other parameters used for controlling the engine. In addition sensors provide sensor signals to the ECU 106. Using the sensor signals, the ECU 106 exercises control of the engine using some programmed computer instructions or similar means. Typically, the programmed computer instructions are provided in the form of a computer program product 110 stored on a readable digital storage medium 108, such as memory card, a Read Only Memory (ROM) a Random Access Memory (RAM), an EPROM, an EEPROM or a flash memory.
In Fig. 2 a flow chart illustrating steps performed in a control procedure performed by an ECU when controlling an engine provided with a VTG to prevent a reverse gas mass flow through a turbo compressor of the engine is shown. In a first step 201, the ECU detects a rapid decrease in fuel feed, i.e. the fuel rate change is determined to be below some pre- determined level. Upon determining that the fuel rate is strongly negative and below some pre-determined value, the ECU switches control mode and proceeds to a second step 203. In the second step 203 the position of the VTG is controlled to generate a maximum turbine speed in order to aid the compressor in maintaining the turbo pressure. Hence, by controlling the VTG position such that the turbine speed is maximized at the reduced fuel feed the risk of a rapid fuel feed reduction leading to a reverse gas mass flow through the compressor is reduced and can in most cases be prevented.
The VTG position that the control system is adapted to control to maximize the turbine power / turbine speed, can for example be given by a map storing an optimal closed VTG position providing a maximum turbine speed for each different state that the engine can operate in. Because surging most often occurs at high engine load and within a relatively narrow engine speed range, the control system can be adapted to control the VTG to the position corresponding to maximum power at those conditions. In other words, the control system can be simplified to adapt the VTG position providing a maximal turbine power / turbine speed for one gas mass flow, i.e. the gas mass flow corresponding to the operational condition where surging is likely to occur.
Next in a third step 205 the ECU checks if a condition for exiting the mode for preventing a reverse gas mass flow through the turbo compressor is fulfilled. If so the procedure returns to step 201, via a fourth step 207 where the control system is reset to the original, regular, control mode, else the procedure stays in the mode for preventing reverse gas mass flow through the turbo compressor and the procedure returns to step 203.
In Fig. 3 a flow chart illustrating steps performed in a control procedure performed by an ECU when controlling an engine provided with an EGR system to prevent a reverse mass flow through a turbo compressor of the engine in accordance with another embodiment of the present invention is shown. First in a first step 301 the ECU detects a rapid decrease in fuel feed, i.e. the fuel rate change is determined to be below some pre-determined level. Upon determining that the fuel rate is strongly negative, i.e. below some pre-determined value, the ECU switches control mode and proceeds to a second step 303. In the second step 303 the EGR valve is opened to a more open position in order to reduce the turbo pressure by creating another gas outlet path via a reverse gas mass flow through the EGR path. Hence by controlling the EGR valve to a more open position the risk of a rapid fuel feed reduction leading to a reverse gas mass flow through the compressor is reduced because the high pressure gas of the turbo charger can exit through the EGR path instead of having to exit through the compressor of the turbo charger.
Next in a third step 305 the ECU checks if a condition for exiting the mode for preventing a reverse gas mass flow through the turbo compressor is fulfilled. If so the procedure returns to step 301 via a fourth step 307 where the control system is reset to the original, regular, control mode, else the procedure stays in the mode for preventing reverse gas mass flow through the turbo compressor and the procedure returns to step 203. The condition used to exit the mode for preventing a reverse gas mass flow through the turbo charger can for example be a determination that the negative fuel rate change is determined to be above some pre-determined level. The level can be but does not have to be the same level where the mode for preventing a reverse gas mass flow through the turbo charger is triggered.
In accordance with a third embodiment of the present invention the control systems as described above in conjunction with Figs. 2 and 3 are combined. Thus, upon detection of a strong negative fuel decrease rate in an engine provided with both a VTG and a an EGR system, the ECU both controls the VTG to a position generating a maximum turbine speed in order to aid the compressor in maintaining the turbo pressure and controls the EGR valve to a more open position in order to reduce the turbo pressure by creating another gas outlet path via a reverse gas mass flow through the EGR path.
In such an embodiment where both the VTG and EGR are controlled, the control system can be adapted to take into account the higher exhaust gas pressure generated by a more closed VTG position. Hence, if the exhaust gas pressure is increased above the charger gas pressure, there cannot be a gas flow in the reverse direction of the EGR path. By storing a map in the control system that provides the control system with combined positions for the VTG and EGR for different states of operation of the engine, it can be ensured that there is always higher charge gas pressure than exhaust gas pressure. This is obtained by storing VTG positions that are more open when a VTG position providing maximum turbine power otherwise would result in an exhaust gas pressure exceeding the charger gas pressure.

Claims

1. A method for controlling a combustion engine (100) for powering a motor vehicle (10), the engine having a turbo charger comprising a compressor (102), the engine further comprising a path for recirculating exhaust gas to the engine, the amount of recirculated exhaust gas being controllable by an EGR valve (107) which is controllable by a control unit (106), characterized by the steps of:
- detecting (301) a negative fuel rate exceeding a predetermined threshold value and, if such is the case, entering (303) a mode where the EGR valve is controlled to a more open position and the Variable Turbine Geometry is controlled to a position generating a substantially maximal turbine speed.
2. The method according to claim 1 characterized by the steps of:
- storing a map comprising optimal EGR valve positions and/or optimally closed Variable Turbine Geometry positions for different engine operation states,
- determining the current engine operation state and
- controlling the Variable Turbine Geometry and/or the EGR valve position to the position(s) corresponding to the current engine operation state according to the map.
3. The method according to either of claims 1 and 2, characterized by the step of:
- exiting the mode to prevent a reverse gas mass flow through the compressor when the negative fuel rate is above a predetermined threshold value.
4. A system for controlling a combustion engine (100) for powering a motor vehicle (10), the engine having a turbo charger comprising a compressor (102), the engine further comprising a path for recirculating exhaust gas to the engine, the amount of recirculated exhaust gas being controllable by an EGR valve (107) which is controllable by a control unit (106), characterized by:
- means (106) for detecting a negative fuel rate exceeding a predetermined threshold value, and if such is the case, entering (303) a mode where the EGR valve is controlled to a more open position and the Variable Turbine Geometry is controlled to a position generating a substantially maximal turbine speed.
5. The system according to claim 4, characterized by: - means for storing a map comprising optimal EGR valve positions and/or optimally closed Variable Turbine Geometry positions for different engine operation states,
- determining the current engine operation state, and
- controlling the Variable Turbine Geometry and/or the EGR valve position to the positions(s) corresponding to the current engine operation state according to the map.
6. The system according to either of claims 4 and 5, characterized by:
- means for exiting the mode to prevent a reverse gas mass flow through the compressor when the negative fuel rate is above a predetermined threshold value.
7. A computer program product (110) for controlling a combustion engine (100) for powering a motor vehicle (10), the engine having a turbo charger comprising a compressor (102), the engine further comprising a path for recirculating exhaust gas to the engine, the amount of recirculated exhaust gas being controllable by an EGR valve (107) controllable by a control unit (106), characterized in that the computer program product comprises program segments which when executed on a computer, e.g. the control unit (106) for controlling the internal combustion engine cause the computer to perform the step of:
- detecting (301) a negative fuel rate exceeding a predetermined threshold value and, if such is the case, entering (303) a mode where the EGR valve is controlled to a more open position and the Variable Turbine Geometry is controlled to a position generating a substantially maximal turbine speed.
8. The computer program product according to claim 7, characterized by program segments for:
- storing a map comprising optimally EGR valve positions and/or optimal closed Variable Turbine Geometry positions for different engine operation states,
- determining the current engine operation state, and - controlling the Variable Turbine Geometry and or the EGR valve position to the position(s) corresponding to the current engine operation state according to the map.
9. The computer program product according to either of claims 7 and 8, characterized by program segments for:
- exiting the mode to prevent a reverse gas mass flow through the compressor when the negative fuel rate is above a predetermined threshold value.
10. A digital storage medium (108) on which the computer program product according to any of claims 7-9 is stored.
PCT/SE2008/050545 2007-05-16 2008-05-12 A surge control method WO2009020418A1 (en)

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DE112008001300.4T DE112008001300B4 (en) 2007-05-16 2008-05-12 Compressor suction control technology

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SE0701200A SE531169C2 (en) 2007-05-16 2007-05-16 A method for preventing reverse flow I
SE0701200-8 2007-05-16

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WO2011154636A1 (en) * 2010-06-11 2011-12-15 Peugeot Citroën Automobiles SA Method for preventing the pumping of an engine turbocharger
FR2964416A1 (en) * 2010-09-07 2012-03-09 Peugeot Citroen Automobiles Sa Motor vehicle diesel type four-cylinder engine controlling method, involves opening exhaust gas recirculation and proportioning valves to generate air flow through recirculation valve moving from intake manifold toward exhaust manifold

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DE102021200330A1 (en) 2021-01-14 2022-07-14 Rolls-Royce Solutions GmbH Method for operating an internal combustion engine, control device for carrying out such a method and internal combustion engine with such a control device

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EP1484497A2 (en) * 2003-06-03 2004-12-08 Isuzu Motors Limited Turbocharged engine and method for preventing surging in compressor
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DE10154151A1 (en) * 2001-11-03 2003-05-15 Daimler Chrysler Ag Process for operating an internal combustion engine with an exhaust gas turbocharger comprises producing and carrying out a boost pressure reduction mode
EP1484497A2 (en) * 2003-06-03 2004-12-08 Isuzu Motors Limited Turbocharged engine and method for preventing surging in compressor
US20070068158A1 (en) * 2005-09-28 2007-03-29 Harold Sun System and method for reducing surge
EP1770270A2 (en) * 2005-10-03 2007-04-04 Deere & Company EGR system having reverse flow, internal combustion engine and method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010115386A1 (en) * 2009-04-08 2010-10-14 Man Diesel & Turbo Se Waste gate turbocharger system, drive system equipped therewith and method for operating said drive system
WO2011154636A1 (en) * 2010-06-11 2011-12-15 Peugeot Citroën Automobiles SA Method for preventing the pumping of an engine turbocharger
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FR2964416A1 (en) * 2010-09-07 2012-03-09 Peugeot Citroen Automobiles Sa Motor vehicle diesel type four-cylinder engine controlling method, involves opening exhaust gas recirculation and proportioning valves to generate air flow through recirculation valve moving from intake manifold toward exhaust manifold

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SE0701200L (en) 2008-11-17
SE531169C2 (en) 2009-01-13
DE112008001300T5 (en) 2010-06-10
DE112008001300B4 (en) 2022-09-01

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