GB2427933A - Correction of fuelling errors in a fuel-injected engine - Google Patents

Correction of fuelling errors in a fuel-injected engine Download PDF

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Publication number
GB2427933A
GB2427933A GB0513289A GB0513289A GB2427933A GB 2427933 A GB2427933 A GB 2427933A GB 0513289 A GB0513289 A GB 0513289A GB 0513289 A GB0513289 A GB 0513289A GB 2427933 A GB2427933 A GB 2427933A
Authority
GB
United Kingdom
Prior art keywords
fuel
engine
interval
scheduled
consumed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0513289A
Other versions
GB0513289D0 (en
Inventor
Trevor Charles Taylor
Robert Anthony Marshall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ford Global Technologies LLC
Original Assignee
Ford Global Technologies LLC
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 Ford Global Technologies LLC filed Critical Ford Global Technologies LLC
Priority to GB0513289A priority Critical patent/GB2427933A/en
Publication of GB0513289D0 publication Critical patent/GB0513289D0/en
Priority to GB0612801A priority patent/GB2427936B/en
Publication of GB2427933A publication Critical patent/GB2427933A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • F02D41/22—Safety or indicating devices for abnormal 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
    • F02D41/24—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
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2464—Characteristics of actuators
    • F02D41/2467—Characteristics of actuators for injectors
    • F02D41/247—Behaviour for small quantities
    • 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
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F9/00—Measuring volume flow relative to another variable, e.g. of liquid fuel for an 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
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0625—Fuel consumption, e.g. measured in fuel liters per 100 kms or miles per gallon
    • 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
    • F02D41/008—Controlling each cylinder individually
    • 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
    • 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
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2441—Methods of calibrating or learning characterised by the learning 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
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

A method is described for compensating for fuelling errors in a fuel injected engine in which demand signals are produced by a control unit 18 to determine the opening times of fuel injectors 16 of the engine 10 to deliver a scheduled quantity of fuel to each cylinder of the engine during a combustion cycle. The method comprises calculating the fuel quantity scheduled by the processor to be supplied to the engine during an operating interval, directly measuring the quantity of fuel consumed by the engine during the same interval, calculating an error corresponding to the difference between the scheduled and measured quantities of consumed fuel during the interval and applying to the demand signals a correction factor based on the calculated error. Preferably, the operating interval is measured between topping up events of a fuel tank 12 or when a vehicle is running in a steady state on level ground. The direct measurement of the quantity of fuel consumed is derived from a fuel level gauge 20 of the fuel tank or by electronic and/or manual input, via a keypad 22, the quantity of fuel added to the fuel tank.

Description

CORRECTION OF FUELLING ERRORS
IN A FUEL-INJECTED ENGINE
Field of the invention
The present invention relates to a method of compensating for fuelling errors in a fuel injected engine in which demand signals are produced by a control unit to determine the opening times of fuel injectors of the engine to deliver a scheduled quantity of fuel to each cylinder of the engine during a combustion cycle.
Background of the invention
In modern diesel engines, a programmed engine control unit (ECU) determines the quantity of fuel to be injected into each cylinder during each engine operating cycle based on a variety of operating parameter. The quantity of fuel scheduled by the ECU for delivery to the cylinders varies not only with operating parameters such as engine load and speed but also on the mode in which the engine is operating.
For example, the engine may normally be designed to operate in a lean burn mode but it may have a variety of other operating modes with different fuelling strategies aimed at accelerating the warming of a catalyst, purging a NOx trap or a catalyst of NOx or SOx or burning off soot from a particulate trap.
To achieve these objectives, it has been proposed to use multiple injection events in each combustion cycle to give control not only over the total amount of fuel introduced into the cylinder but the timing with which different proportions of the total charge are injected during each combustion cycle. A group of events is referred to as a state and within each state there may be as many as six separate injection events.
It can thus be seen that increasing demands are being placed on the responsiveness of the injectors and even if the injectors deliver the scheduled fuel quantity when they are new, it is likely that wear in the injectors will affect the accuracy of the fuel metering over a period of time.
Object of the invention The invention therefore seeks to provide a method of operating an engine which will compensate for inaccuracies in fuelling caused by wear in the injectors.
Summary of the invention
According to the present invention, there is provided a method of compensating for fuelling errors in a fuel injected engine in which demand signals are produced by a control unit to determine the opening times of fuel injectors of the engine to deliver a scheduled quantity of fuel to each cylinder of the engine during a combustion cycle, which method comprises calculating the fuel quantity scheduled by the processor to be supplied to the engine during an operating interval, directly measuring the quantity of fuel consumed by the engine during the same interval, calculating an error corresponding to the difference between the scheduled and measured quantities of consumed fuel during the interval and applying to the demand signals a correction factor based on the calculated error.
Because of the small quantities involved, it is not possible to make a direct measurement of the fuel delivered during each cylinder combustion cycle in a diesel engine. In a spark ignition cycle, such a measurement can be derived indirectly by monitoring levels of oxidants and reductants in the exhaust gases and feedback from such a measurement can be used to correct for errors caused by improper operation or calibration of injectors.
The same cannot however he done in the case of a diesel engine which under normal circumstances run lean and small differences in the quantity of fuel burnt does not have a major effect on the chemistry of the exhaust gases. The present invention overcomes the problem by integrating the quantity of fuel scheduled for delivery to the engine over a long period operation and comparing this with a fuel quantity that may be measured more easily or even entered by the user.
Hence, in one embodiment of the invention, the interval over which scheduled fuel consumption is integrated is set between topping up events of a fuel tank and the direct measurement of the quantity of fuel consumed is derived from a fuel level gauge of the fuel tank. When being filled, a vehicle normally stands on level ground and under such conditions the electrical output of a fuel gauge can be used to indicate the quantity of fuel in the tank with an acceptable degree of accuracy. One can therefore derive an accurate measurement of fuel consumed to be compared with the quantity of fuel scheduled for delivery during the intervening interval.
Instead of relying on the fuel gauge, it is alternatively or additionally possible to require the operator to key in the quantity of fuel added to the tank.
As an alternative to such data being keyed in by the operator, it may be uploaded from a memory chip in the ignition key or by signal transmitted by the fuel dispensing pump. After several such measurements any inaccuracies in the readings of a fuel gauge will become insignificant.
It is also alternatively possible to commence and terminate the integration interval at instants when the vehicle is running in a steady state on level ground.
Brief description of the drawing
The invention will now be described further, by way of example with reference to the accompanying drawing which is a block diagram of a diesel engine.
Description of the preferred embodiment
In the drawing, fuel from a fuel tank 12 is pressurised by a pump 14 and applied to injectors 16 by way of a supply rail. The injectors 16 are opened and closed by demand signals from an electronic control unit 18 to inject fuel from the supply rail into the cylinders of the engine 10.
As this layout is entirely conventional, it need not be described in detail in the present context. Essentially, the ECU 18 receives signals from a variety of sensors (not shown), which sense such parameters as crankshaft angular position, speed, load, engine temperature, exhaust back pressure, and catalyst temperature, this list not being intended to be comprehensive. The ECU determines the mode in which the engine should be operating, switching as necessary between modes for normal running, for purging a NOx trap, for rapid heating of a catalyst, for desuiphation of a catalyst or regeneration of a particulate trap. Within each mode, the ECU determines the amounts of fuel that should be injected into the engine cylinders and the timing of the injection events. The ECU then sends demand signals to the injectors to deliver these scheduled quantities of fuel to the engine cylinders. The injection events may be fairly complex, with the injectors being sometimes called upon to open and close several times within the same combustion cycle.
The control of the injectors is conventionally open loop control, that is to say instructions sent to the injectors are assumed to be obeyed correctly and there is no feedback signal to ensure that this it the case. For this reason, with ageing of the injectors and the fuel pump, it is possible for the engine to receive more or less fuel than was scheduled, leading to its incorrect operation.
Because it is not simple in a diesel engine to provide a feedback signal indicative of the quantity of fuel delivered to each cylinder on a cycle by cycle basis, the ECU 18 in the preferred embodiment of the invention is programmed to execute a program to evaluate a correction factor to the taken into consideration in creating the demand signals sent to the injectors 16.
The ECU 18 first detects when the vehicle is on level ground either from the fact that it has just been refuelled or from the fact that the engine is operating in a steady state. At this time a reading is taken from a fuel gauge 20 to indicated the quantity of fuel in the tank. Once such a reading has been taken with the vehicle standing or travelling on level ground, it is stored in memory and an integration period is commenced during which the ECU keeps track of the total amount of fuel scheduled for delivery to the engine.
After the interval has lasted sufficiently to yield a meaningful result, the interval is terminated by the ECU while the vehicle is again travelling or standing on level ground. At the termination of the interval, a second reading is taken from the fuel gauge 20 to indicate the quantity of fuel remaining in the tank. The difference between the two fuel gauge readings should be equal to the scheduled quantity delivered to the engine evaluated by the ECU. In the event of a mismatch, the ECU can ascertain from the error the difference between the scheduled fuel quantities and the quantities actually injected into the engine and apply a correction to the demand signals to reduce the value of the error. Thus, if less fuel is being injected than scheduled, the duration of each demand signal can be increased to prolong the time that the injector remains open and conversely if too much fuel is being injected then the demand pulses can be shortened.
The correction factor applied by the ECU will commence as 1 and will drift only slowly as the injectors and the fuel pump are subjected to wear. It is not therefore essential for it to be updated at frequent intervals and it suffices for it to be based on a long term rolling average of the difference between the scheduled and actual fuel consumption of the engine. Readings may therefore be averaged over intervals corresponding to several full tanks of fuel. In this case, improved accuracy can be achieved by having the operator enter the quantity of fuel added to the tank 12 each top up by keying the volume of fuel using a keypad 22. This reduces any inaccuracy resulting from incorrect calibration of the fuel gauge 20.
In it simplest application the correction factor is applied equally across the speed/load map. However, the ECU can keep track of the speed load duty cycle. In this case a weight correction factor can be applied to the map based upon the mass of fuel used in each band of the speed/load map. The weight factor can be a simple linear or more complex function based upon calibration experience.
If a faster and more accurate update to the fuel correction is required, then a long thin measuring cylinder may be provided within the main fuel tank to which the engine supply and return lines are connected. When not in measuring mode, a valve allows the fuel contents of the main tank to communicate with the measuring cylinder. When in measuring mode, on the other hand, the valve is closed and the scheduled fuel is compared with used fuel between two set points in the cylinder. When the fuel level reaches the lower of these set points, the foot valve is opened again and if the fuel level is below the upper of the two set points then the measurement routine is not requested.

Claims (6)

1. A method of compensating for fuelling errors in a fuel injected engine in which demand signals are produced by a control unit to determine the opening times of fuel injectors of the engine to deliver a scheduled quantity of fuel to each cylinder of the engine during a combustion cycle, which method comprises calculating the fuel quantity scheduled by the processor to be supplied to the engine during an operating interval, directly measuring the quantity of fuel consumed by the engine during the same interval, calculating an error corresponding to the difference between the scheduled and measured quantities of consumed fuel during the interval and applying to the demand signals a correction factor based on the calculated error.
2. A method as claimed in claim 1, wherein the interval is measured between topping up events of a fuel tank.
3. A method as claimed in claim 1, wherein the measurement interval is commenced and terminated while the vehicle is running in a steady state on level ground.
4. A method as claimed in any preceding claim, wherein the direct measurement of the quantity of fuel consumed is derived from a fuel level gauge of the fuel tank.
5. A method as claimed in any preceding claim, in which the quantity of fuel added to the fuel tank at each topping up of the fuel tank is manually or electronically uploaded.
6. A method as claimed in claim 1, wherein a measuring cylinder is provided within the main fuel tank to which the engine supply and return lines are connected, the cylinder communicating with the fuel in the main tank by way of a valve that is closed while measurement of consumed fuel is being effected.
GB0513289A 2005-07-01 2005-07-01 Correction of fuelling errors in a fuel-injected engine Withdrawn GB2427933A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0513289A GB2427933A (en) 2005-07-01 2005-07-01 Correction of fuelling errors in a fuel-injected engine
GB0612801A GB2427936B (en) 2005-07-01 2006-06-28 Correction of fuelling errors in a fuel-injected engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0513289A GB2427933A (en) 2005-07-01 2005-07-01 Correction of fuelling errors in a fuel-injected engine

Publications (2)

Publication Number Publication Date
GB0513289D0 GB0513289D0 (en) 2005-08-03
GB2427933A true GB2427933A (en) 2007-01-10

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GB0513289A Withdrawn GB2427933A (en) 2005-07-01 2005-07-01 Correction of fuelling errors in a fuel-injected engine
GB0612801A Expired - Fee Related GB2427936B (en) 2005-07-01 2006-06-28 Correction of fuelling errors in a fuel-injected engine

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4313412A (en) * 1979-03-19 1982-02-02 Nissan Motor Company Limited Fuel supply control system
EP1336745A2 (en) * 2002-02-19 2003-08-20 C.R.F. Società Consortile per Azioni Method and device for controlling injection in an internal combustion engine, in particular a diesel engine with a common rail injection system.
EP1375888A2 (en) * 2002-06-20 2004-01-02 Denso Corporation Fuel injection quantity control system for engine

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7900635A (en) * 1979-01-26 1980-07-29 Doornes Bedrijfswagen Fab DEVICE FOR MEASURING ENGINE FUEL CONSUMPTION.
JPS588262A (en) * 1981-07-08 1983-01-18 Nissan Motor Co Ltd Diagnostic device of trouble in automobile
DE3224919A1 (en) * 1982-07-03 1984-01-05 Bayerische Motoren Werke AG, 8000 München Measuring device for supplies of operating liquid in motor vehicles
DE19727923B4 (en) * 1997-07-01 2006-08-03 Siemens Ag tank system
IT1298951B1 (en) * 1998-02-26 2000-02-07 Tecnoblock Italia S R L DEVICE AND RELATED PROCEDURE FOR THE CONTROL OF FUEL CONSUMPTION IN A VEHICLE
DE19901532B4 (en) * 1999-01-16 2007-02-08 Daimlerchrysler Ag Device and method for detecting and diagnosing increased fuel consumption of a vehicle
FR2871912B1 (en) * 2004-06-21 2007-03-30 Sofide Soc En Commandite Par A SYSTEM FOR MONITORING THE FILLING OPERATIONS OF A TANK, AND ITS LEVEL, FROM A CONTROLLED INFORMATION SYSTEM, BETWEEN VEHICLES AND A MONITORING CENTER

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4313412A (en) * 1979-03-19 1982-02-02 Nissan Motor Company Limited Fuel supply control system
EP1336745A2 (en) * 2002-02-19 2003-08-20 C.R.F. Società Consortile per Azioni Method and device for controlling injection in an internal combustion engine, in particular a diesel engine with a common rail injection system.
EP1375888A2 (en) * 2002-06-20 2004-01-02 Denso Corporation Fuel injection quantity control system for engine

Also Published As

Publication number Publication date
GB2427936A (en) 2007-01-10
GB2427936B (en) 2008-09-10
GB0513289D0 (en) 2005-08-03
GB0612801D0 (en) 2006-08-09

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