GB2533104A - Method of aquiring fuel injector characteristics - Google Patents

Method of aquiring fuel injector characteristics Download PDF

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Publication number
GB2533104A
GB2533104A GB1421861.4A GB201421861A GB2533104A GB 2533104 A GB2533104 A GB 2533104A GB 201421861 A GB201421861 A GB 201421861A GB 2533104 A GB2533104 A GB 2533104A
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GB
United Kingdom
Prior art keywords
fuel
injected
relationship
pulse
pressure
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Withdrawn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
GB1421861.4A
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GB201421861D0 (en
Inventor
Guerrassi Noureddine
Lienhart Maxime
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.)
Delphi International Operations Luxembourg SARL
Original Assignee
Delphi International Operations Luxembourg SARL
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 Delphi International Operations Luxembourg SARL filed Critical Delphi International Operations Luxembourg SARL
Priority to GB1421861.4A priority Critical patent/GB2533104A/en
Publication of GB201421861D0 publication Critical patent/GB201421861D0/en
Publication of GB2533104A publication Critical patent/GB2533104A/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Withdrawn legal-status Critical Current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
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • 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
    • F02D41/401—Controlling injection timing
    • 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
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • 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
    • 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
    • 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
    • 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
    • F02D2200/0602—Fuel 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
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0618—Actual fuel injection timing or delay, e.g. determined from fuel pressure drop
    • 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

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

Abstract

Disclosed is a fuel injection system for an internal combustion engine, the system having one or more fuel injectors 2, wherein said fuel injectors are operated by sending a drive pulse of duration ΔT to an actuator of said fuel injector. The invention provides a method of updating data relating the duration of the pulse to a corresponding quantity of fuel injected. The method comprises the steps of providing a relationship between the drop in pressure in a common rail/accumulator volume and an injected fuel quantity, performing a series of injections with drive pulses of varying durations and for each of these determining the consequential pressure drop. The pressure drop is used to determine the actual fuel quantity injected and storing/updating the relationship between pulse length ΔT and injected quantity. The method may also comprise steps of correcting the relationship between the fuel pressure drop and fuel quantity injected for fuel temperature.

Description

Method of Aquiring Fuel Injector Characteristics
Field of the Invention
This invention relates to a method of aquiring certain characteristics of fuel injectors, and further a mehtod of controlling operation of fuel injectors based on the aquired characteristics. It has particular application to methods of controlling and correcting fuel injection characteristics which vary during use.
Background to the Invention
Fuel injectors are typically controlled by generating pulses which are sent to the actuators of the fuel injectors. The amount of fuel injected typically depends on the length of a pulse sent to the actuator. Typically an Engine Control Unit adjusts the pulse length as a result of the demand quantity of fuel to be injected. The demand quantity of fuel is typically stored in a map which relates this to engine speed and torque demand.
Characteristics of fuel injectors may vary, as well as change over time for the same fuel injector, e.g. as a result of wear. It is important to calibrate the injection systems/injectors periodically so that variations in their lifetime are catered for, and that the control is adapted to deal with such vaiations. Techniques are known which apply learning strategies, whereby injector characteristics are freshly determined, and the injectors are consequently appropriately controlled. One of the learning techniques involves determining the important parameter of minimum pulse, that is the pulse of shortest duration which is required for any fuel injection.
Pulse lengths of less than this will not cause any fuel to be injected.
Current learning strategy detects the minimum drive pulse separately on each injector using, for example accelerometer sensors or engine speed signals. Some injection equipment suppliers implement a sensor inside the injector to detect the injection event and then correct the injector fuelling drift This however requires extra components. It is one object of the invention to provide a cheaper, and reliable method of updating/gathering fuel injector characteristics and controlling injection using learning strategies which do not require extra components.
Statement of the Invention
In one aspect is provided a method In a fuel injection system having one or more fuel injectors, wherein said fuel injectors are operated by sending a drive pulse of duration AT to an actuator of said fuel injector, a method of providing or updating data relating the duration of the pulse to corresponding the quantity of fuel injected, comprising providing: i) providing a relationship between the drop in pressure in a common rail/accumulator volume consequent to an injected fuel quantity; ii) performing a series of injections with drive pulses of varying durations, and for each of these determining the consequential pressure drop; iii) relating said pressure drop to the quantity of injected fuel using said relationship of i) iv) storing/updating the relationship between pulse length AT and injected quantity.
Said pressure drop may be determined from the fuel rail pressure sensor.
The method may include the step of determining or estimating fuel temperature, and said relationship in i) includes the variable of fuel temperature, such that the determined quantity of fuel injected is adjusted or dependent on said temperature.
The method may include the step of determining or estimating the pressure in the fuel rail/accumulator, and said relationship in i) include this variable of pressure, such that the determined quantity of fuel is adjusted or dependent on said temperatures.
The method is preferably performed in foot-on conditions and/or when it s ensured that the fuel has reached a minimum temperature.
Said relationship in i) preferably takes into account leakage in the fuel injector.
Thus the methodology is capable of learning Injector fuel pulse characteristics using existing common rail pressure sensors. In one aspect, the methodology allows periodic learning of individual injectors pulse maps during foot-on simultaneously on 4 cylinders. This strategy allows fast and robust learning of injector characteristics, as on the same thermodynamic cycle, the learning is made on all the cylinders.
Brief Description of Drawings
The invention will now be described with reference to the following figures of which: to Figure I shows a diagramatic representation of a known fuel injection circuit; Figure 2 shows results of the effect of injection on fuel rail pressure; Figure 3 shows results for the accumulator pressure drop for different injector pulse lengths and thus different quantities of injected fuel at the same initial rail pressure; Figure 4 shows the accumulator pressure drop resulting from different durations of injector drive pulse; Figure 5 shows a calibration curve showing the pressure drop against injection quantity taking into account dynamic leakage.
Figure 6 shows the accumulator pressure drop at different injector drive pulse durations as well as and rail pressure for zero injected quantity for a variety of injectors; Figure 7 shows an injector calibration map which is used in examples of theinvention; and, Figure 8 shows a flow chart of an example of the learning method for a pulse map of an individual injector.
Description of Examples
Figure I shows a diagramatic representation of a known fuel injection circuit showing a common fuel rail I fluidly connecting the fuel therein to a series of injectors 2. The circuit includes an in tank electrical fuel pump 3, a fuel filter 4, and a high pressure pump 5. A high pressure sensor 6 is located on the common rail as shown.
Figure 2 shows results of the effect of injection on fuel rail (or accumulator) pressure. Figure 2a shows typically the current through the actuator of a fuel injector as a result of an actuation pulse of duration AT sent from the ECU. Figure 2b shows the actual volume of fuel dispensed over time; as can be seen there is a delay between the start of the pulse and the opening of the actuator valve to dispense fuel. Figure 2c shows the pressure in the common rail consequent to the injection event; as can be seen a pressure drop is observed.
Figure 3 shows the pressure drop observed in the common rail for different injector pulse lengths and thus different quantities of injected fuel at the same initial rail pressure. As can be seen the pressure drop increases with increasing fuel quantity injected.
Figure 4 shows the pressure drop resulting from different durations (lengths) of injector pulse (fiiel quantity injected) and also how these characteristics vary with rail pressure for a particular injector.
Figure 5 shows a calibration curve showing the pressure drop against injection quantity taking into account dynamic leakage. Effectively it shows a modified linear correlation by removing the change in pressure due to control chamber discharge (MDP) in order to remove the production dispersion this value and kccp only the physics linear correlation duc to Mel discharge Figure 6 shows the pressure drop at different injector pulse durations as well as and rail pressure for zero injected quantity for a variety of injectors. As can be seen dependent on the individual injector and rail pressure, there is a pressure drop threshold before any fuel is injected.
Figure 7 shows a calibration map which is used in examples of the invention. This relates the injection quantity to pressure drop at various rail pressures. This is used according to aspects of the invention to perform calibration which will be explained in more detail later. The calibration map can be provided by appropraite testing or by a more emprical determination knowing the fuel rail/accumulator volume, and fuel bulk modulus. This data can be stored in the ECU.
In one aspect, the calibration map is used to update a stored relationship relating pulse length to fuel quantity injected. At intervals, the pressure drop consequent to a pulse length is measured, and using the calibration curve of figure 7, the relationship between pulse length and injected quantity can be determined/updated. Thus in one aspect the drop in fuel pressure is used to determine injected quantity, and this mapped to pulse length. A stored map of pulse length to injected quantity, is required by the ECU for the normal operation of the injectors.
In one simple example, a learning routine is implemented (this may be preferably performed under certain conditions explained later) where the pressure drop in a fuel (common) rail or accumulator volume is measured by the corresponding common rail/accumulator pressure sensor, consequent to a fuel injection cycle/event with respect to one or more fuel injectors. In such a routine the pulse duration is set and recorded as well as varied, and the consequential pressure drop is recorded. In other words the methodology includes the step of determing the rail pressure drop during the injection event. This is done in preferred examples by using the existing pressure sensors referred to above. This pressure drop is then used with a look-up table or calibration map similar to that described with reference to figure 7, (e.g. stored in the ECU) to determine the corresponding fuel quantity for a set pulse duration. Thus the method allows the fuel injector characteristics to be updated, notably the relationship between pulse duration and the corresponding amount of fuel injected.
This allows e.g. the ECU to correlate/update maps relating fuel pulse length against injected quantity, which are used under normal operation, i.e, to control the operation of the fuel injectors. In other words the determined quantity for each injector drive pulse duration can be stored in the ECU and used for the subsequently controlling injection events.
In a preferred embodiment, fuel temperature is also measured and used to implrove the accuracy of the method e.g. by having a temperature sensor to amend/correct the curve in the calibration map, or apply a correction factor to the determined parameters. All the pulse maps are updated permanently in non volatile memory loaded at each engine start.
Figure 8 shows a flow chart of an example of the learning method for a pulse map of an individual injector. The method statrts at step 1 when a learning mileage has been reached; this may be every 1000 kilometers for example. In step 2, it is checked if the engine is in foot-off conditions. If so the process will be delayed until foot-on conditions are encountered. If so, in Step 3, the learning calibration is set/initialised.
For each engine cycle, the rail pressure drop is measured (step 4). In Step 5 a correction for inlet fuel temperature may be applied. The quantity of fuel for the particular injection event is determined from a calibration curve, such as similar to that of figure 7. The quantity of fuel injected is then recorded and stored along with the corresponding pulse length. This is used to update maps of tables correlating these two parameters.
In step 6 the individual injector fuelling maps are updated. If it is determined that the engine is still in foot off condition (Step 7), the steps 4 to 6 are repeatwed for the next engine cycle.

Claims (6)

  1. Claims 1. In a fuel injection system having one or more fuel injectors, wherein said fuel injectors are operated by sending a drive pulse of duration AT to an actuator of said fuel injector, a method of providing or updating data relating the duration of the pulse to corresponding the quantity of fuel injected, comprising providing: i) providing a relationship between the drop in pressure in a common rail/accumulator volume consequent to an injected fuel quantity; ii) performing a series of injections with drive pulses of varying durations, and for each of these determining the consequential pressure drop; iii) relating said pressure drop to the quantity of injected fuel using said relationship of i) iv) storing/updating the relationship between pulse length AT and injected quantity.
  2. 2. A method as claimed in claim I wherein said pressure drop is determined from the fuel rail pressure sensor.
  3. 3. A method as claimed in claim 1 or 2 including the step of determining or estimating fuel temperature, and said relationship in i) includes the variable of fuel temperature, such that the determined quantity of fuel injected is adjusted or dependent on said temperature.
  4. 4. A method as claimed in claim 1 including the step of determining or estimating the pressure in the fuel rail/accumulator, and said relationship in i) include this variable of pressure, such that the determined quantity of fuel is adjusted or dependent on said temperatures.
  5. 5. A method as claimed in any preceding claim, which is performed in foot-on conditions and/or when it is ensured that the fuel has reached a minimum temperature.
  6. 6. A method as claimed in any preceding claim wherein said relationship in i) takes into account leakage in the fuel injector.
GB1421861.4A 2014-12-09 2014-12-09 Method of aquiring fuel injector characteristics Withdrawn GB2533104A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1421861.4A GB2533104A (en) 2014-12-09 2014-12-09 Method of aquiring fuel injector characteristics

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GB1421861.4A GB2533104A (en) 2014-12-09 2014-12-09 Method of aquiring fuel injector characteristics

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GB2533104A true GB2533104A (en) 2016-06-15

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108071503A (en) * 2016-11-10 2018-05-25 通用汽车环球科技运作有限责任公司 The system and method for controlling fluid injection
WO2023025959A1 (en) 2021-08-26 2023-03-02 Delphi Technologies Ip Limited Method of determining a hydraulic timing of a fuel injector
WO2023036855A1 (en) 2021-09-09 2023-03-16 Delphi Technologies Ip Limited Improved pressure drop analysis strategy

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10760518B2 (en) * 2017-05-10 2020-09-01 Ford Global Technologies, Llc Method and system for characterizing a port fuel injector

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5906188A (en) * 1995-09-21 1999-05-25 Mitsubishi Jidosha Kogyo Kabushiki Kaisha Accumulator type fuel injection control system and the method thereof
JP2000257495A (en) * 1999-03-10 2000-09-19 Isuzu Motors Ltd Fuel injection method for engine and its apparatus
US20070261483A1 (en) * 2006-05-11 2007-11-15 Roger Halleberg Method for adjusting an on-time calculation model or lookup table and a system for controlling an injector of a cylinder in a combustion engine
US20090164086A1 (en) * 2007-12-20 2009-06-25 Mert Geveci System for determining critical on-times for fuel injectors
US20120123703A1 (en) * 2010-11-10 2012-05-17 Gabriele Serra Method for determining the injection law of a fuel injector using a roller-test bench

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5906188A (en) * 1995-09-21 1999-05-25 Mitsubishi Jidosha Kogyo Kabushiki Kaisha Accumulator type fuel injection control system and the method thereof
JP2000257495A (en) * 1999-03-10 2000-09-19 Isuzu Motors Ltd Fuel injection method for engine and its apparatus
US20070261483A1 (en) * 2006-05-11 2007-11-15 Roger Halleberg Method for adjusting an on-time calculation model or lookup table and a system for controlling an injector of a cylinder in a combustion engine
US20090164086A1 (en) * 2007-12-20 2009-06-25 Mert Geveci System for determining critical on-times for fuel injectors
US20120123703A1 (en) * 2010-11-10 2012-05-17 Gabriele Serra Method for determining the injection law of a fuel injector using a roller-test bench

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108071503A (en) * 2016-11-10 2018-05-25 通用汽车环球科技运作有限责任公司 The system and method for controlling fluid injection
WO2023025959A1 (en) 2021-08-26 2023-03-02 Delphi Technologies Ip Limited Method of determining a hydraulic timing of a fuel injector
WO2023036855A1 (en) 2021-09-09 2023-03-16 Delphi Technologies Ip Limited Improved pressure drop analysis strategy

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