WO2019177522A1 - System and method for controlling operation of a dosing unit of a fluid dosing system - Google Patents

System and method for controlling operation of a dosing unit of a fluid dosing system Download PDF

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Publication number
WO2019177522A1
WO2019177522A1 PCT/SE2019/050216 SE2019050216W WO2019177522A1 WO 2019177522 A1 WO2019177522 A1 WO 2019177522A1 SE 2019050216 W SE2019050216 W SE 2019050216W WO 2019177522 A1 WO2019177522 A1 WO 2019177522A1
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WO
WIPO (PCT)
Prior art keywords
time period
dosing
voltage
unit
coil
Prior art date
Application number
PCT/SE2019/050216
Other languages
French (fr)
Inventor
Joakim SVANTESSON
Kurt KÄLLKVIST
Original Assignee
Scania Cv Ab
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 filed Critical Scania Cv Ab
Priority to DE112019000809.9T priority Critical patent/DE112019000809T5/en
Publication of WO2019177522A1 publication Critical patent/WO2019177522A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating 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
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
    • H01F7/1805—Circuit arrangements for holding the operation of electromagnets or for holding the armature in attracted position with reduced energising current
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
    • H01F7/1844—Monitoring or fail-safe circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • F01N2610/146—Control thereof, e.g. control of injectors or injection valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806—Properties of reducing agent or dosing system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806—Properties of reducing agent or dosing system
    • F01N2900/1821—Injector parameters
    • 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
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2034—Control of the current gradient
    • 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
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2048—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit said control involving a limitation, e.g. applying current or voltage limits
    • 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
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2055—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit with means for determining actual opening or closing time
    • 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
    • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2058—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using information of the actual current value
    • 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
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • 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 for controlling operation of a dosing unit of a fluid dosing system.
  • the invention relates also to a computer program product comprising program code for a computer for implementing a method according to the invention. It relates also to a system for controlling operation of a dosing unit of a fluid dosing system and a motor vehicle equipped with the system.
  • a reducing agent dosing system being installed in vehicles for purposes of emission control.
  • a valve unit is electrically controlled and a sealing member position is alternated for setting the valve unit in an open state and a closed state, alternately.
  • a pressurized reducing agent is dosed into an exhaust gas stream of a combustion engine for emission control.
  • an inductive member In a case where an inductive member is used for controlling the position of the sealing member it is common to initially apply a peak voltage followed by a hold voltage during a dosing cycle. Hereby an excessive amount of electrical energy may be contained in the inductive member. This is resulting in an unpredictable behaviour of the operation of the valve unit.
  • US4238813 relates to a method for stabilizing operation of a solenoid manoeuvred injector. Energy of a coil may hereby be discharged at a controlled or constant rate.
  • An object of the present invention is to propose a novel and advantageous method for controlling operation of a dosing unit of a fluid dosing system.
  • Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program for controlling operation of a dosing unit of a fluid dosing system.
  • Another object of the present invention is to propose a novel and advantageous method providing a cost effective and reliable operation control of a dosing unit of a fluid dosing system.
  • Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program providing a cost effective and reliable operation control of a dosing unit of a fluid dosing system.
  • Yet another object of the invention is to propose a method, a system and a computer program achieving a robust, accurate and automated controlling operation of a dosing unit of a fluid dosing system.
  • Yet another object of the invention is to propose an alternative method, an alternative system and an alternative computer program for controlling operation of a dosing unit of a fluid dosing system.
  • a method for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, the method comprising the steps of:
  • the proposed method is energy efficient because of a shortened time period for applying said hold voltage.
  • the method advantageously provides a robust and accurate dosing control.
  • the proposed method is applicable to situations where relatively short time periods of dosing are at hand. In these situations it is possible to shift from the peak voltage to zero voltage directly so as to achieve predictable actual end of injection time periods.
  • the step of shifting from said hold voltage to zero voltage may be performed prior to a steady state situation regarding said current in the coil and the energy state of said coil has occurred.
  • a steady state situation regarding said current in the coil and the energy state of said coil has occurred.
  • the proposed method is energy efficient because of a shortened time period for applying said hold voltage.
  • the method may comprise the step of:
  • a system for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, the system comprising:
  • - means being arranged for determining an actual discharge time period on the basis of said thus determined prevailing current; - means being arranged for determining a compensation value on the basis of said actual discharge time period and a nominal discharge time period;
  • - means being arranged for controlling operation of said dosing unit taking into account said determined actual end of injection time period.
  • the system may comprise means being arranged for shifting from said hold voltage to zero voltage prior to an steady state situation regarding the current in said coil and the energy state of said coil has occurred.
  • the system may comprise means being arranged for controlling operation of said dosing unit on the basis of a time difference between a point in time when said peak voltage is applied and a point of time when said hold voltage is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period and a start of injection time period.
  • a vehicle comprising a system according to what is presented herein.
  • the vehicle may be any from among a truck, bus or passenger car.
  • the system is provided for a marine application or industrial application.
  • a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position
  • the computer program comprises program code for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein, when run on the electronic control unit or the computer.
  • a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position
  • the computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein.
  • a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position
  • the computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein, when run on the electronic control unit or the computer.
  • a computer program product containing a program code stored on a computer-readable medium for performing any one of the method steps depicted herein, when the computer program is run on an electronic control unit or a computer connected to the electronic control unit.
  • a computer program product containing a program code stored non-volatile on a computer-readable medium for performing any one of the method steps depicted herein, when the computer program is run on an electronic control unit or a computer connected to the electronic control unit.
  • a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out any one of the steps of the method depicted herein.
  • a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out any one of the steps of the method depicted herein.
  • Figure 1 schematically illustrates a vehicle according to an embodiment of the invention
  • Figure 2a schematically illustrates a system according to an embodiment of the invention
  • Figure 2b schematically illustrates a system according to an embodiment of the invention
  • Figure 2c schematically illustrates a system according to an embodiment of the invention
  • Figure 3a schematically illustrates a diagram presenting an applied voltage over a dosing unit member, as well as a prevailing current in said dosing unit member, as a function of time;
  • Figure 3b schematically illustrates a diagram according to an embodiment of the invention
  • Figure 3c schematically illustrates a diagram according to an embodiment of the invention
  • Figure 4a is a schematic flowchart of a method according to an embodiment of the invention.
  • Figure 4b is a schematic function diagram of a method according to an embodiment of the invention.
  • Figure 5 schematically illustrates a computer according to an embodiment of the invention.
  • FIG. 1 depicts a side view of a vehicle 100.
  • the exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112.
  • the vehicle 100 may be a heavy vehicle, e.g. a truck or a bus. It may alternatively be a car.
  • the proposed method and system are applicable to various vehicles, such as e.g. a mining machine, tractor, dumper, wheel-loader, platform comprising an industrial robot, forest machine, earth mover, road construction vehicle, road planner, emergency vehicle or a tracked vehicle.
  • a mining machine e.g. a mining machine, tractor, dumper, wheel-loader, platform comprising an industrial robot, forest machine, earth mover, road construction vehicle, road planner, emergency vehicle or a tracked vehicle.
  • the proposed method and system are applicable to various dosing units of fluid dosing systems, such as reducing agent dosing systems or fuel dosing systems for regenerating emission control systems.
  • the proposed method and system are applicable to any suitable dosing unit of a fluid dosing system, which dosing unit comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position.
  • the proposed method and system are applicable for application in various systems comprising a combustion engine and an associated emission control arrangement comprising a reducing agent dosing system.
  • the proposed method and system are applicable for application in various systems comprising a combustion engine and a catalytic
  • the catalytic configuration may comprise at least one reducing agent dosing unit, each dosing unit being arranged for providing a reducing agent upstream of a corresponding SCR unit.
  • the catalytic configuration may comprise one or more DOC units.
  • the catalytic configuration may comprise one or more DPF units. It should be noted that the invention is applicable to various catalytic configurations and is therefore not confined to catalytic configurations for motor vehicles.
  • the proposed method and the proposed system according to one aspect of the invention are well suited to other platforms which comprise a combustion engine and a catalytic configuration, e.g. watercraft.
  • the watercraft may be of any kind, e.g. motorboats, steamers, ferries or ships.
  • the proposed method and the proposed system according to one aspect of the invention are also well suited to, for example, systems which comprise industrial combustion engines and/or combustion engine-powered industrial robots and an associated emission control arrangement comprising at least one SCR unit and at least one reducing agent dosing unit.
  • the proposed method and the proposed system according to one aspect of the invention are also well suited to various kinds of power plants, e.g. an electric power plant which comprises a combustion engine-powered generator and an associated emission control arrangement comprising at least one reducing agent dosing unit for catalytic operation of an SCR unit.
  • an electric power plant which comprises a combustion engine-powered generator and an associated emission control arrangement comprising at least one reducing agent dosing unit for catalytic operation of an SCR unit.
  • the proposed method and the proposed system are also well suited to various combustion engine systems comprising an associated emission control arrangement having at least one reducing agent dosing unit for catalytic operation of an SCR unit.
  • the proposed method and the proposed arrangement are well suited to any engine system which comprises an engine, e.g. on a locomotive or some other platform, and an associated emission control arrangement having at least one SCR unit.
  • the proposed method and the proposed system are well suited to any system which comprises a NO x -generator an associated emission control arrangement having at least one SCR units.
  • the proposed method and the proposed system are well suited to various fluid dosing systems having an electrically controlled valve unit, whereby the fluid may be any suitable liquid or gas.
  • link refers herein to a communication link which may be a physical connection such as an opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.
  • line refers herein to a passage for holding and conveying a fluid, e.g. a reducing agent in liquid form or fuel.
  • the line may be a pipe of any size and be made of any suitable material, e.g. plastic, rubber or metal.
  • reductant or "reducing agent” refers herein to an agent used for reacting with certain emissions in an SCR system. These emissions may for example be NO x -gas.
  • reductant and “reducing agent” are herein used synonymously.
  • the reductant is so-called AdBlue.
  • AdBlue is herein cited as an example of a reductant, but one skilled in the art will appreciate that the proposed method and the proposed system are feasible with other types of reductants.
  • the terms "SCR unit” and "SCR configuration" are herein used synonymously.
  • the SCR unit/SCR configuration may also be referred to as "reduction catalyst device".
  • the SCR units of the emission control arrangement may be any suitable SCR units.
  • the SCR unit may comprise an SCRF unit, comprising a coated filter.
  • the SCR unit may according to other examples provide a combination of SCR functionality and at least one additional functionality (other than NO x conversion), such as SCR functionality and DOC functionality, SCR functionality and ammonia slip catalyst functionality, etc.
  • the SCR unit may comprise ceramic materials used as a carrier, such as titanium oxide, and active catalytic components which usually are oxides of base metals, such as vanadium, molybdenum and tungsten.
  • Tdischargeactual refers to the time period t5-t2 as in Figure 3b (which is not nominal).
  • nominal discharge time period Tdischargenominal refers herein to the time period t5-t2 as given in Figure 3a.
  • compensation value COMP may herein refer to the difference Tdischargenominal - Tdischargeactual.
  • actual end of injection time period TEOIactual refers herein to the time period t4-t2 as given in Figure 3b according to the comments above.
  • nominal end of injection time period TEOInominal refers herein to the time period t4-t2 as given in Figure 3a.
  • requested dosing time treq refers herein to the time period during which the dosing unit must be in an open state in order to supply the required amount of fluid.
  • FIG. 2a schematically illustrates a system 289 according to an example embodiment of the invention.
  • the system 289 is situated in the tractor unit 110 and may be part of a catalytic configuration, also denoted exhaust gas processing configuration. It comprises in this example a container 205 arranged to hold a reductant.
  • the container 205 is adapted to holding a suitable amount of reductant and also to being replenishable as necessary.
  • the container may be adapted to hold e.g. 75 or 50 litres of reductant.
  • a first line 271 is provided to lead the reductant to a pump 230 from the container 205.
  • the pump 230 may be any suitable pump.
  • the pump 230 may be arranged to be driven by an electric motor (not depicted).
  • the pump 230 may be adapted to drawing the reductant from the container 205 via the first line 271 and supplying it via a second line 272 to a dosing unit 237.
  • the dosing unit 237 may also be referred to as a reducing agent dosing unit.
  • the dosing unit 237 comprises an electrically controlled dosing valve by means of which a flow of reductant added to the exhaust system can be controlled.
  • the pump 230 is adapted to pressurising the reductant in the second line 272.
  • a third line 273 is provided with a throttle unit (not shown), against which said pressure of the reductant may build up in the system 289. Alternatively said throttle unit is provided within said dosing unit 237.
  • a first control unit 200 is arranged for communication with the pump 230 via a link L230.
  • the first control unit 200 is arranged to send control signals S230 via said link L230.
  • the first control unit 200 is arranged to control operation of said pump 230 so as to for example adjust flows of the reducing agent within the system 289.
  • the first control unit 200 is arranged to control an operation power of the pump 230 e.g. by controlling the electric motor.
  • the dosing unit 237 is adapted to supplying said reductant to an exhaust gas system (see Fig. 2b) of the vehicle 100. More specifically, it is adapted to supplying a suitable amount of reductant in a controlled way to an exhaust system of the vehicle 100. In this version, one SCR unit (see Fig. 2b) is situated downstream of the location in the exhaust system where the supply of reductant takes place.
  • the dosing unit 237 is depicted in greater detail with reference to Figure 2c.
  • the third line 273 running between the dosing unit 237 and the container 205 is adapted to leading back to the container 205 a certain amount of the reductant fed to the dosing unit 237.
  • This configuration results in advantageous cooling of the dosing unit 237.
  • the dosing unit 237 is thus cooled by a flow of the reductant when it is pumped through it from the pump 230 to the container 205.
  • the first control unit 200 is arranged for communication with the dosing unit 237 via a link L237.
  • the first control unit 200 is arranged to send control signals S237 via said link L237.
  • the first control unit 200 is arranged to control operation of said dosing unit 237 so as to for example control dosing of the reducing agent to the exhaust gas system of the vehicle 100.
  • the first control unit 200 is arranged to control operation of the dosing unit 237 so as to for example adjust return flow of said reducing agent to the container 205.
  • a second control unit 210 is arranged for communication with the first control unit 200 via a link L210. It may be releasably connected to the first control unit 200. It may be a control unit external to the vehicle 100. It may be adapted to performing the proposed steps according to the invention. It may be used to cross-load software to the first control unit 200, particularly software for applying the proposed method. It may alternatively be arranged for communication with the first control unit 200 via an internal network on board the vehicle. It may be adapted to performing functions corresponding to those of the first control unit 200, such as e.g. controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position.
  • Figure 2b schematically illustrates a system 290 of the vehicle shown i Figure 1 according to an embodiment of the invention.
  • the system 290 may constitute a part of the proposed system comprising said dosing unit 237.
  • the first control unit 200 is arranged for communication with said combustion engine 231 via a link L231.
  • the first control unit is arranged to control operation of said combustion engine 231 by means of control signals S231.
  • the combustion engine 231 is during operation causing an exhaust gas flow which is lead via a first passage 255 to an SCR-unit 260.
  • a second passage 265 is arranged to convey said exhaust gas flow from said SCR-unit 260 to an environment of the vehicle.
  • the emission control system provided downstream said engine 231 may comprise a DOC- unit (not shown) and/or a DPF-unit (not shown).
  • the emission control system may comprise a number of SCR units and at least one reducing agent dosing unit.
  • Said dosing unit 237 is arranged to provide said reductant to said first passage 255 upstream of said SCR-unit 260.
  • the first control unit 200 is arranged to control operation of said dosing unit 237 so as to, where applicable, dose reducing agent into the first passage 255.
  • Said SCR-unit 260 may comprise a vaporizing module (not shown) which is arranged to vaporize said dosed reducing agent so as to achieve a mixture of exhaust gas and reducing agent for treatment by means of an SCR-portion of the SCR-unit 260.
  • Said vaporizing module may comprise a mixer (not shown) for mixing said vaporized reducing agent with the exhaust gas.
  • Said vaporizing module may be formed in any suitable way.
  • Said vaporizing module is configured to achieve a most effective vaporizing of provided reducing agent as possible.
  • said vaporizing module is providing large surfaces where vaporizing of provided reducing agent may be performed in an effective way.
  • Said vaporizing module may consist of a metal or a metal alloy.
  • Said SCR-unit 260 may according to one possible configuration comprise an ammonia slip catalyst ASC, not illustrated.
  • Said first control unit 200 is arranged to perform the process steps depicted herein, comprising the process steps which are detailed with reference to Figure 4b.
  • Figure 2c schematically illustrates the closing unit 237 in greater detail.
  • the second line 272 is arranged to provide pressurized reducing agent to an opening O of the dosing unit 237.
  • the third line 273 is arranged to lead reducing agent which has not been dosed via said opening O back to the tank 205.
  • the first control unit 200 is arranged to control dosing by means of an electrically controlled valve unit.
  • the valve unit comprises a number of parts of the dosing unit 237.
  • the valve unit is according to this example comprising a sealing member 291.
  • the sealing member 291 is according to this example pin like.
  • the valve unit is spring biased by means of a spring 293.
  • the first control unit 200 is arranged to control a position of the sealing member 291 by means of an electrical wiring 292 comprising a coil surrounding the sealing member 291.
  • the coil is arranged for shifting said valve unit between an open state OS and a closed state CS by moving the sealing member 291 between a first position PI and a second position P2.
  • the movement of the sealing member 291 between the first position PI and the second position P2Th is performed by means of an electromagnetic force.
  • a voltage U By applying a voltage U by means of said first control unit 200 a current I is generated.
  • an electromagnetic force is overcoming the force applied by the spring 293 and the sealing member 291 is moved from the second position P2 to the first position PI.
  • dosing of reducing agent is controlled.
  • Dosing of the pressurized reducing agent is performed when the valve unit is in said open state OS.
  • the applied voltage U is shut off, the spring 293 will affect the valve unit to change from said open state OS to said closed state CS.
  • the first control unit 200 is arranged to continuously determine the prevailing current I in said electrical wiring 292.
  • FIG. 3a is illustrating a diagram wherein a voltage U being applied over the coil 292 is given as a function of time t. In the diagram also a prevailing current in the coil 292 is given as a function of time t.
  • the voltage U is given in Volt (V)
  • the prevailing current I is given in milliampere (mA)
  • the time t is given in milliseconds (ms).
  • V Volt
  • mA milliampere
  • ms milliseconds
  • the peak voltage Ul may be any suitable voltage sufficient for achieving the sealing member 291 to move from the second position P2 to the first position PI, i.e. to set the valve unit of the dosing unit 237 in the open state OS.
  • the peak voltage Ul is according to one example a predetermined voltage, e.g. 24V. According to one embodiment the peak voltage Ul is 12V. This value may be relevant in case the vehicle 100 is a car. According to one embodiment the peak voltage Ul is 60V.
  • the prevailing current I in the coil is hereby initially increasing and at a time point when the sealing member 291 is actually moved a first temporarily dip is observed.
  • the current I is increasing to a top level before a point of time tl.
  • the peak voltage Ul is applied during a time period tO-tl. At the point of time tl the peak voltage Ul is shifted to a hold voltage U2.
  • the hold voltage U2 may be any suitable voltage sufficient for maintaining the sealing member 291 in the first position PI, i.e. to keep the valve unit in the open state OS.
  • the hold voltage U2 is lower than the peak voltage Ul.
  • the hold voltage U2 is according to one example a predetermined voltage, e.g. 18V (e.g. in a case where the peak voltage Ul is 24V). According to one example the hold voltage U2 is any suitable voltage being lower than the peak voltage Ul and higher than 0V.
  • the hold voltage U2 is applied during a certain time period. During this time period the prevailing current I in said coil 291 is stabilized at a certain level.
  • the hold voltage U2 is shifted to a level of zero (0) voltage and hereby the prevailing current I is decreasing from said certain level to a value of zero (0) mA.
  • the current I has reached 0V.
  • the sealing member 291 is moved from the first position PI to the second position P2 by means of the applied spring force, i.e. the valve unit of the dosing unit 237 is set to the closed state CS. The movement of the sealing member 291 is affecting the course of the current I (at t3 and t4).
  • Figure 3b is illustrating a diagram wherein the principles of the present invention according to an embodiment are depicted.
  • the voltage U applied over the coil 292 is given as a function of time t.
  • a prevailing current in the coil 292 is given as a function of time t.
  • the voltage U is given in Volt (V)
  • the prevailing current I is given in milliampere (mA)
  • the time t is given in milliseconds (ms).
  • a peak voltage Ul is applied over the coil 292.
  • the peak voltage Ul may be any suitable voltage sufficient for achieving the sealing member 291 to move from the second position P2 to the first position PI, i.e. to set the valve unit of the dosing unit 237 in the open state OS.
  • the peak voltage Ul is according to one example a predetermined voltage, e.g. 24V.
  • the prevailing current I in the coil is hereby initially increasing and at a time point (t3) when the sealing member 291 is actually moved a first temporarily dip is observed.
  • the current I is increasing to a top level before a point of time tl.
  • the peak voltage Ul is applied during a time period tO-tl. At the point of time tl the peak voltage Ul is shifted to a hold voltage U2.
  • the hold voltage U2 may be any suitable voltage sufficient for maintaining the sealing member 291 in the first position, i.e. to keep the valve unit in the open state OS.
  • the hold voltage U2 is lower than the peak voltage Ul.
  • the hold voltage U2 is according to one example a predetermined voltage, e.g. 18V.
  • the prevailing current I in the coil 292 is continuously detected by means of the first control unit 200.
  • the prevailing current I in the coil 292 is continuously detected by means of the first control unit 200 only after the point of time tl.
  • the hold voltage U2 is applied during a time period tl-t2. During this time period the prevailing current in said coil 291 has not necessarily been stabilized at a certain level but may be changing.
  • the hold voltage U2 is shifted to a level of zero (0) voltage and hereby the prevailing current I is decreasing from said certain level to a value of zero (0) mA (which is reached at t5).
  • the sealing member 291 is moved from the first position PI to the second position P2, i.e. the valve unit of the dosing unit 237 is set to the closed state CS (at t4).
  • the prevailing current I in said coil 292 is determined just prior to shifting from said hold voltage U2 to zero voltage.
  • an actual discharge time period Tdischargeactual is determined on the basis the thus determined prevailing current, which current value lx is associated with a time point just prior to shifting from said hold voltage U2 to zero voltage.
  • a compensation value COMP may be determined on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period
  • a difference between the nominal discharge time period Tdischargenominal and actual discharge time period Tdischargeactual is equal the compensation value COMP:
  • the actual end of injection time period TEOIactual may be adjusted the basis on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP.
  • the nominal end of injection time period may be empirically determined for a given nominal discharge time period TEOInominal.
  • the operation of said dosing unit 237 is advantageously controlled taking into account said determined actual end of injection time period
  • point of time t2 is substantially earlier than a corresponding point of time t2, which is related to the diagram of Figure 3a.
  • the point of time t2 is earlier according to this example than the point of time as given with reference to Figure 3a.
  • the applied hold voltage U2 is set to 0 voltage before, or at an early stage, of a steady state condition of the current I.
  • the steady state condition of the current I and the applied hold voltage U2 as given with reference to Figure 3a is depicted with broken lines in Figure 3b for comparison reasons.
  • Figure 3c is illustrating a diagram wherein a position P of the sealing member 291 is a presented as a function of time t.
  • the position P is given in millimetres (mm) and the time is given in milliseconds (ms).
  • the diagram also presents voltage U applied over the coil 292 is given as a function of time t in accordance with the teachings in Figure 3b. It is illustrated that there is a time delay associated with the actual opening process of the sealing member 291 from the time point tO when the peak voltage Ul is applied to a point of time t3 when the sealing member 291 is actually moved to the first position PI from the second position P2. In a similar way there is a time delay associated with the actual closing process of the sealing member 291 from the time point t2 when the hold voltage U2 is reduced to zero voltage to a point of time t4 when the sealing member 291 is actually moved to the second position P2 from the first position PI.
  • the peak voltage Ul is shifted to the hold voltage U2 at the point of time tl.
  • the current in the coil 292 becomes 0mA.
  • treq refers to the time period during which the dosing unit must be in the open state (OS) in order to supply the required amount of fluid; tstartofinjection is herein denoted t3;
  • Figure 4a schematically illustrates a flow chart of a method for controlling operation of a dosing unit 237 of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
  • the method comprises a first method step s401.
  • the method step s401 comprises the steps of: - applying a peak voltage Ul over said coil 292;
  • Figure 4b schematically illustrates a method for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
  • the method comprises a first method step s410.
  • the method step s410 comprises the step of
  • the peak voltage Ul may be any suitable voltage.
  • the peak voltage Ul may be a predetermined voltage, e.g. 24V.
  • a current I is increasing in the coil 292, and by means of the electromagnetic force the sealing member is moved to the second position P2 from the first position PI at a point of time t3 (see Figure 3c) when the electromagnetic force is overcoming the force of the spring 293.
  • a subsequent method step s420 is performed.
  • the method step s420 comprises the step of shifting said applied peak voltage Ul to a hold voltage U2. This is performed by means of the first control unit 200.
  • the voltage shifting is performed at a point of time tl (see Figure 3b and 3c).
  • the hold voltage U2 may be any suitable voltage.
  • the hold voltage U2 is lower than the peak voltage Ul.
  • the hold voltage U2 may be a predetermined voltage, e.g. 18V.
  • the hold voltage U2 is sufficient to overcome the force of the spring 293 and thus keep the sealing member 291 in the first position PI whereby dosing is achieved.
  • the method step s430 comprises the step of just prior to shifting from said hold voltage U2 to zero voltage, determining a prevailing current lx in said coil 292. This is performed by means of the first control unit 200.
  • the point of time t2 when the shifting from the hold voltage U2 to zero voltage is determined by means of the first control unit 200.
  • the step of shifting from said hold voltage U2 to zero voltage may be performed prior to an steady state situation regarding the current I in the coil 291 and the energy state of the coil has occurred.
  • the point of time t2 is hereby relatively close in time to the point of time tl.
  • the term "just prior" is any suitable point of time before the point of time t2.
  • just prior may be determined to be a point of time defined by a predetermined time interval before the point of time t2.
  • the term “just prior” may be e.g. 1, 3 or 5 milliseconds before the point of time t2.
  • the term “just prior” may be parts of 1 millisecond before the point of time t2, such as 0.5 milliseconds or 0.3 milliseconds.
  • the method step s440 comprises the step of determining an actual discharge time period Tdischargeactual on the basis of the thus determined prevailing current lx. This may be performed by means of the first control unit 200. According to one example the actual discharge time period Tdischargeactual is performed substantially in real time. According to one example the actual discharge time period Tdischargeactual is determined by using a table which is stored in a memory of the first control unit 200. Hereby a number of empirically determined values of actual discharge time period Tdischargeactual are stored in the memory and a most relevant value is selected on the basis of the determined prevailing current lx. After the method step s440 a subsequent method step s450 is performed.
  • the method step s450 comprises the step of determining a compensation value COMP on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period Tdischargenominal. This is performed by means of the first control unit 200. By determining a difference between nominal discharge time period Tdischargenominal and the actual discharge time period Tdischargeactual the compensation value COMP may be determined.
  • the nominal discharge time period Tdischargenominal may be a predetermined value. This is also depicted with reference to Figure 3c.
  • the method step s460 comprises the step of adjusting an actual end of injection time period TEOIactual on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP. This is performed by means of the first control unit 200.
  • the actual end of injection time period TEOIactual is equal to the nominal end of injection time period TEOInominal added to the compensation value COMP.
  • the method step s470 comprises the step of controlling operation of said dosing unit taking into account said determined actual end of injection time period TEOIactual.
  • the method step s470 may comprise the step of controlling operation of said dosing unit on the basis of a time difference between a point in time tO when the peak voltage Ul is applied and a point of time t2 when said hold voltage U2 is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period TEOIactual and a start of injection time period TSOI.
  • step s470 the method is returned/ended.
  • FIG. 5 is a diagram of one version of a device 500.
  • the control units 200 and 210 described with reference to Figure 2a and Figure 2b may in one version comprise the device 500.
  • the device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550.
  • the non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500.
  • the device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted).
  • the non-volatile memory 520 has also a second memory element 540.
  • the computer program P comprises routines for controlling operation of a dosing unit 237 of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
  • the computer program P may comprise routines for applying a peak voltage Ul over said coil 292.
  • the computer program P may comprise routines for shifting said applied peak voltage Ul to a hold voltage U2.
  • the computer program P may comprise routines for just prior to shifting from said hold voltage U2 to zero voltage, determining a prevailing current in said coil.
  • the computer program P may comprise routines for determining an actual discharge time period Tdischargeactual on the basis of the thus determined prevailing current.
  • the computer program P may comprise routines for determining a compensation value COMP on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period Tdischargenominal.
  • the computer program P may comprise routines for adjusting an actual end of injection time period TEOIactual on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP.
  • the computer program P may comprise routines for controlling operation of said dosing unit taking into account said determined actual end of injection time period TEOIactual.
  • the computer program P may comprise routines for shifting from said hold voltage U2 to zero voltage prior to an steady state situation regarding the current in the coil and the energy state of the coil 292 has occurred.
  • the computer program P may comprise routines for controlling operation of said dosing unit on the basis of a time difference between a point in time when the peak voltage Ul is applied and a point of time when said hold voltage U2 is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period TEOIactual and a start of injection time period TSOI.
  • the computer program P may comprise routines for performing any of the process steps detailed with reference to Figure 4a and Figure 4b.
  • the program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550.
  • the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is stored in the read/write memory 550.
  • the data processing device 510 can communicate with a data port 599 via a data bus 515.
  • the non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512.
  • the separate memory 560 is intended to communicate with the data processing unit via a data bus 511.
  • the read/write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514.
  • the links L210, L230, L231 and L237 for example, may be connected to the data port 599 (see Fig. 2a and 2b).
  • the data processing unit 510 will be prepared to conduct code execution as described above.
  • Parts of the methods herein described may be conducted by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550.
  • the device 500 runs the program, method steps and process steps herein described are executed.

Abstract

The invention relates to a method for controlling operation of a dosing unit (237) of a fluid dosing system comprising an electrically controlled valve unit having a coil (292) arranged for shifting said valve unit between an open state and a closed state by moving a sealing member (291) between a first position (PI) and a second position (P2), the method comprising the steps of: - applying (s410) a peak voltage (U1) over said coil (292); - shifting (s420) said applied peak voltage (U1) to a hold voltage (U2); -just prior to shifting from said hold voltage (U2) to zero voltage, determining (s430) a prevailing current (lx) in said coil (292); - determining (s440) an actual discharge time period (Tdischargeactual) on the basis of the thus determined prevailing current (lx); - determining (s450) a compensation value (COMP) on the basis of said actual discharge time period (Tdischargeactual) and a nominal discharge time period (Tdischargenominal); - adjusting (s460) an actual end of injection time period (TEOIactual) on the basis of a nominal end of injection time period (TEOInominal) and said compensation value (COMP); - controlling (s470) operation of said dosing unit taking into account said determined actual end of injection time period (TEOIactual).

Description

System and method for controlling operation of a dosing unit of a fluid dosing system
TECHNICAL FIELD
The present invention relates to a method for controlling operation of a dosing unit of a fluid dosing system. The invention relates also to a computer program product comprising program code for a computer for implementing a method according to the invention. It relates also to a system for controlling operation of a dosing unit of a fluid dosing system and a motor vehicle equipped with the system.
BACKGROUND ART
Today many different fluid dosing systems are known. One such fluid dosing system is a reducing agent dosing system being installed in vehicles for purposes of emission control. According to one variant a reducing agent dosing unit a valve unit is electrically controlled and a sealing member position is alternated for setting the valve unit in an open state and a closed state, alternately. Hereby a pressurized reducing agent is dosed into an exhaust gas stream of a combustion engine for emission control.
In a case where an inductive member is used for controlling the position of the sealing member it is common to initially apply a peak voltage followed by a hold voltage during a dosing cycle. Hereby an excessive amount of electrical energy may be contained in the inductive member. This is resulting in an unpredictable behaviour of the operation of the valve unit.
US4238813 relates to a method for stabilizing operation of a solenoid manoeuvred injector. Energy of a coil may hereby be discharged at a controlled or constant rate. SUMMARY OF THE INVENTION
An object of the present invention is to propose a novel and advantageous method for controlling operation of a dosing unit of a fluid dosing system.
Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program for controlling operation of a dosing unit of a fluid dosing system.
Another object of the present invention is to propose a novel and advantageous method providing a cost effective and reliable operation control of a dosing unit of a fluid dosing system.
Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program providing a cost effective and reliable operation control of a dosing unit of a fluid dosing system.
Yet another object of the invention is to propose a method, a system and a computer program achieving a robust, accurate and automated controlling operation of a dosing unit of a fluid dosing system.
Yet another object of the invention is to propose an alternative method, an alternative system and an alternative computer program for controlling operation of a dosing unit of a fluid dosing system.
Some of these objects are achieved with a method according to claim 1. Other objects are achieved with a system in accordance with what is depicted herein. Advantageous embodiments are depicted in the dependent claims. Substantially the same advantages of method steps of the proposed method hold true for corresponding means of the proposed system. According to an aspect of the invention there is provided a method for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, the method comprising the steps of:
- applying a peak voltage over said coil;
- shifting said applied peak voltage to a hold voltage;
- just prior to shifting from said hold voltage to zero voltage, determining a prevailing current in said coil;
- determining an actual discharge time period on the basis of said thus determined prevailing current;
- determining a compensation value on the basis of said actual discharge time period and a nominal discharge time period;
- adjusting an actual end of injection time period on the basis of a nominal end of injection time period and said compensation value;
- controlling operation of said dosing unit taking into account said determined actual end of injection time period.
Hereby an improved dosing procedure is achieved. The proposed method is energy efficient because of a shortened time period for applying said hold voltage.
The method advantageously provides a robust and accurate dosing control.
By controlling operation of said dosing unit on the basis of an adjusted actual end of injection time period an energy efficient dosing control is achieved.
By determining the compensation value, determining a discharge time of the coil on the basis of the prevailing current just prior to shifting from said hold voltage to zero voltage and put this time in relation to a previously known corresponding discharge time period an improved method for controlling operation of a dosing unit is achieved. According to one example, the proposed method is applicable to situations where relatively short time periods of dosing are at hand. In these situations it is possible to shift from the peak voltage to zero voltage directly so as to achieve predictable actual end of injection time periods.
According to an embodiment, the step of shifting from said hold voltage to zero voltage may be performed prior to a steady state situation regarding said current in the coil and the energy state of said coil has occurred. Hereby an improved dosing procedure is achieved.
The proposed method is energy efficient because of a shortened time period for applying said hold voltage.
The method may comprise the step of:
- controlling operation of said dosing unit on the basis of a time difference between a point in time when said peak voltage is applied and a point of time when said hold voltage is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period and a start of injection time period.
According to an aspect of the invention there is provided a system for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, the system comprising:
- means being arranged for applying a peak voltage over said coil;
- means being arranged for shifting said applied peak voltage to a hold voltage;
- means being arranged for, just prior to shifting from said hold voltage to zero voltage, determining a prevailing current in said coil;
- means being arranged for determining an actual discharge time period on the basis of said thus determined prevailing current; - means being arranged for determining a compensation value on the basis of said actual discharge time period and a nominal discharge time period;
- means being arranged for adjusting an actual end of injection time period on the basis of a nominal end of injection time period and said compensation value;
- means being arranged for controlling operation of said dosing unit taking into account said determined actual end of injection time period.
The system may comprise means being arranged for shifting from said hold voltage to zero voltage prior to an steady state situation regarding the current in said coil and the energy state of said coil has occurred.
The system may comprise means being arranged for controlling operation of said dosing unit on the basis of a time difference between a point in time when said peak voltage is applied and a point of time when said hold voltage is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period and a start of injection time period.
According to an aspect of the invention there is provided a vehicle comprising a system according to what is presented herein. The vehicle may be any from among a truck, bus or passenger car. According to an embodiment the system is provided for a marine application or industrial application.
According to an aspect of the invention there is provided a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, wherein the computer program comprises program code for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein, when run on the electronic control unit or the computer.
According to an aspect of the invention there is provided a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, wherein the computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein.
According to an aspect of the invention there is provided a computer program for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position, wherein the computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform any one of the method steps depicted herein, when run on the electronic control unit or the computer.
According to an aspect of the invention there is provided a computer program product containing a program code stored on a computer-readable medium for performing any one of the method steps depicted herein, when the computer program is run on an electronic control unit or a computer connected to the electronic control unit.
According to an aspect of the invention there is provided a computer program product containing a program code stored non-volatile on a computer-readable medium for performing any one of the method steps depicted herein, when the computer program is run on an electronic control unit or a computer connected to the electronic control unit.
According to an aspect of the invention there is provided a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out any one of the steps of the method depicted herein.
According to an aspect of the invention there is provided a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out any one of the steps of the method depicted herein. Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details, and also by putting the invention into practice. Whereas the invention is described below, it should be noted that it is not confined to the specific details described. One skilled in the art having access to the teachings herein will recognise further applications, modifications and incorporations in other fields, which are within the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
For fuller understanding of the present invention and its further objects and advantages, the detailed description set out below should be read in conjunction with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which:
Figure 1 schematically illustrates a vehicle according to an embodiment of the invention; Figure 2a schematically illustrates a system according to an embodiment of the invention; Figure 2b schematically illustrates a system according to an embodiment of the invention; Figure 2c schematically illustrates a system according to an embodiment of the invention;
Figure 3a schematically illustrates a diagram presenting an applied voltage over a dosing unit member, as well as a prevailing current in said dosing unit member, as a function of time;
Figure 3b schematically illustrates a diagram according to an embodiment of the invention;
Figure 3c schematically illustrates a diagram according to an embodiment of the invention
Figure 4a is a schematic flowchart of a method according to an embodiment of the invention;
Figure 4b is a schematic function diagram of a method according to an embodiment of the invention; and
Figure 5 schematically illustrates a computer according to an embodiment of the invention.
DETAILED DESCRIPTION Figure 1 depicts a side view of a vehicle 100. The exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112. The vehicle 100 may be a heavy vehicle, e.g. a truck or a bus. It may alternatively be a car.
The proposed method and system are applicable to various vehicles, such as e.g. a mining machine, tractor, dumper, wheel-loader, platform comprising an industrial robot, forest machine, earth mover, road construction vehicle, road planner, emergency vehicle or a tracked vehicle.
The proposed method and system are applicable to various dosing units of fluid dosing systems, such as reducing agent dosing systems or fuel dosing systems for regenerating emission control systems. The proposed method and system are applicable to any suitable dosing unit of a fluid dosing system, which dosing unit comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position.
The proposed method and system are applicable for application in various systems comprising a combustion engine and an associated emission control arrangement comprising a reducing agent dosing system. The proposed method and system are applicable for application in various systems comprising a combustion engine and a catalytic
configuration. The catalytic configuration may comprise at least one reducing agent dosing unit, each dosing unit being arranged for providing a reducing agent upstream of a corresponding SCR unit. The catalytic configuration may comprise one or more DOC units. The catalytic configuration may comprise one or more DPF units. It should be noted that the invention is applicable to various catalytic configurations and is therefore not confined to catalytic configurations for motor vehicles. The proposed method and the proposed system according to one aspect of the invention are well suited to other platforms which comprise a combustion engine and a catalytic configuration, e.g. watercraft. The watercraft may be of any kind, e.g. motorboats, steamers, ferries or ships. The proposed method and the proposed system according to one aspect of the invention are also well suited to, for example, systems which comprise industrial combustion engines and/or combustion engine-powered industrial robots and an associated emission control arrangement comprising at least one SCR unit and at least one reducing agent dosing unit.
The proposed method and the proposed system according to one aspect of the invention are also well suited to various kinds of power plants, e.g. an electric power plant which comprises a combustion engine-powered generator and an associated emission control arrangement comprising at least one reducing agent dosing unit for catalytic operation of an SCR unit.
The proposed method and the proposed system are also well suited to various combustion engine systems comprising an associated emission control arrangement having at least one reducing agent dosing unit for catalytic operation of an SCR unit.
The proposed method and the proposed arrangement are well suited to any engine system which comprises an engine, e.g. on a locomotive or some other platform, and an associated emission control arrangement having at least one SCR unit.
The proposed method and the proposed system are well suited to any system which comprises a NOx-generator an associated emission control arrangement having at least one SCR units.
The proposed method and the proposed system are well suited to various fluid dosing systems having an electrically controlled valve unit, whereby the fluid may be any suitable liquid or gas.
The term "link" refers herein to a communication link which may be a physical connection such as an opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link. The term "line" refers herein to a passage for holding and conveying a fluid, e.g. a reducing agent in liquid form or fuel. The line may be a pipe of any size and be made of any suitable material, e.g. plastic, rubber or metal.
The term "reductant" or "reducing agent" refers herein to an agent used for reacting with certain emissions in an SCR system. These emissions may for example be NOx-gas. The terms "reductant" and "reducing agent" are herein used synonymously. In one version, the reductant is so-called AdBlue. Other kinds of reductants may of course be used. AdBlue is herein cited as an example of a reductant, but one skilled in the art will appreciate that the proposed method and the proposed system are feasible with other types of reductants.
The terms "SCR unit" and "SCR configuration" are herein used synonymously. The SCR unit/SCR configuration may also be referred to as "reduction catalyst device". The SCR units of the emission control arrangement may be any suitable SCR units. According to one example the SCR unit may comprise an SCRF unit, comprising a coated filter. The SCR unit may according to other examples provide a combination of SCR functionality and at least one additional functionality (other than NOx conversion), such as SCR functionality and DOC functionality, SCR functionality and ammonia slip catalyst functionality, etc. The SCR unit may comprise ceramic materials used as a carrier, such as titanium oxide, and active catalytic components which usually are oxides of base metals, such as vanadium, molybdenum and tungsten.
In case Figure 3a represents a "nominal" closure, i.e. a closure from a state where the energy state in the coil has reached a steady state, the term actual discharge time period
Tdischargeactual refers to the time period t5-t2 as in Figure 3b (which is not nominal).
The term nominal discharge time period Tdischargenominal refers herein to the time period t5-t2 as given in Figure 3a.
The term compensation value COMP may herein refer to the difference Tdischargenominal - Tdischargeactual. The term actual end of injection time period TEOIactual refers herein to the time period t4-t2 as given in Figure 3b according to the comments above.
The term nominal end of injection time period TEOInominal refers herein to the time period t4-t2 as given in Figure 3a.
The term requested dosing time treq refers herein to the time period during which the dosing unit must be in an open state in order to supply the required amount of fluid.
Figure 2a schematically illustrates a system 289 according to an example embodiment of the invention. The system 289 is situated in the tractor unit 110 and may be part of a catalytic configuration, also denoted exhaust gas processing configuration. It comprises in this example a container 205 arranged to hold a reductant. The container 205 is adapted to holding a suitable amount of reductant and also to being replenishable as necessary. The container may be adapted to hold e.g. 75 or 50 litres of reductant.
A first line 271 is provided to lead the reductant to a pump 230 from the container 205. The pump 230 may be any suitable pump. The pump 230 may be arranged to be driven by an electric motor (not depicted). The pump 230 may be adapted to drawing the reductant from the container 205 via the first line 271 and supplying it via a second line 272 to a dosing unit 237. The dosing unit 237 may also be referred to as a reducing agent dosing unit. The dosing unit 237 comprises an electrically controlled dosing valve by means of which a flow of reductant added to the exhaust system can be controlled. The pump 230 is adapted to pressurising the reductant in the second line 272. A third line 273 is provided with a throttle unit (not shown), against which said pressure of the reductant may build up in the system 289. Alternatively said throttle unit is provided within said dosing unit 237.
A first control unit 200 is arranged for communication with the pump 230 via a link L230. The first control unit 200 is arranged to send control signals S230 via said link L230. The first control unit 200 is arranged to control operation of said pump 230 so as to for example adjust flows of the reducing agent within the system 289. The first control unit 200 is arranged to control an operation power of the pump 230 e.g. by controlling the electric motor.
The dosing unit 237 is adapted to supplying said reductant to an exhaust gas system (see Fig. 2b) of the vehicle 100. More specifically, it is adapted to supplying a suitable amount of reductant in a controlled way to an exhaust system of the vehicle 100. In this version, one SCR unit (see Fig. 2b) is situated downstream of the location in the exhaust system where the supply of reductant takes place. The dosing unit 237 is depicted in greater detail with reference to Figure 2c.
The third line 273 running between the dosing unit 237 and the container 205 is adapted to leading back to the container 205 a certain amount of the reductant fed to the dosing unit 237. This configuration results in advantageous cooling of the dosing unit 237. The dosing unit 237 is thus cooled by a flow of the reductant when it is pumped through it from the pump 230 to the container 205.
The first control unit 200 is arranged for communication with the dosing unit 237 via a link L237. The first control unit 200 is arranged to send control signals S237 via said link L237.
The first control unit 200 is arranged to control operation of said dosing unit 237 so as to for example control dosing of the reducing agent to the exhaust gas system of the vehicle 100. The first control unit 200 is arranged to control operation of the dosing unit 237 so as to for example adjust return flow of said reducing agent to the container 205.
A second control unit 210 is arranged for communication with the first control unit 200 via a link L210. It may be releasably connected to the first control unit 200. It may be a control unit external to the vehicle 100. It may be adapted to performing the proposed steps according to the invention. It may be used to cross-load software to the first control unit 200, particularly software for applying the proposed method. It may alternatively be arranged for communication with the first control unit 200 via an internal network on board the vehicle. It may be adapted to performing functions corresponding to those of the first control unit 200, such as e.g. controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil arranged for shifting said valve unit between an open state and a closed state by moving a sealing member between a first position and a second position.
Figure 2b schematically illustrates a system 290 of the vehicle shown i Figure 1 according to an embodiment of the invention. The system 290 may constitute a part of the proposed system comprising said dosing unit 237.
The first control unit 200 is arranged for communication with said combustion engine 231 via a link L231. The first control unit is arranged to control operation of said combustion engine 231 by means of control signals S231.
The combustion engine 231 is during operation causing an exhaust gas flow which is lead via a first passage 255 to an SCR-unit 260. A second passage 265 is arranged to convey said exhaust gas flow from said SCR-unit 260 to an environment of the vehicle.
The emission control system provided downstream said engine 231 may comprise a DOC- unit (not shown) and/or a DPF-unit (not shown). The emission control system may comprise a number of SCR units and at least one reducing agent dosing unit.
Said dosing unit 237 is arranged to provide said reductant to said first passage 255 upstream of said SCR-unit 260. The first control unit 200 is arranged to control operation of said dosing unit 237 so as to, where applicable, dose reducing agent into the first passage 255.
Said SCR-unit 260 may comprise a vaporizing module (not shown) which is arranged to vaporize said dosed reducing agent so as to achieve a mixture of exhaust gas and reducing agent for treatment by means of an SCR-portion of the SCR-unit 260. Said vaporizing module may comprise a mixer (not shown) for mixing said vaporized reducing agent with the exhaust gas. Said vaporizing module may be formed in any suitable way. Said vaporizing module is configured to achieve a most effective vaporizing of provided reducing agent as possible. Herein said vaporizing module is providing large surfaces where vaporizing of provided reducing agent may be performed in an effective way. Said vaporizing module may consist of a metal or a metal alloy.
Said SCR-unit 260 may according to one possible configuration comprise an ammonia slip catalyst ASC, not illustrated. Said first control unit 200 is arranged to perform the process steps depicted herein, comprising the process steps which are detailed with reference to Figure 4b.
Figure 2c schematically illustrates the closing unit 237 in greater detail. Hereby the second line 272 is arranged to provide pressurized reducing agent to an opening O of the dosing unit 237. The third line 273 is arranged to lead reducing agent which has not been dosed via said opening O back to the tank 205.
The first control unit 200 is arranged to control dosing by means of an electrically controlled valve unit. The valve unit comprises a number of parts of the dosing unit 237. The valve unit is according to this example comprising a sealing member 291. The sealing member 291 is according to this example pin like. The valve unit is spring biased by means of a spring 293. The first control unit 200 is arranged to control a position of the sealing member 291 by means of an electrical wiring 292 comprising a coil surrounding the sealing member 291. The coil is arranged for shifting said valve unit between an open state OS and a closed state CS by moving the sealing member 291 between a first position PI and a second position P2.
The movement of the sealing member 291 between the first position PI and the second position P2Th is performed by means of an electromagnetic force. By applying a voltage U by means of said first control unit 200 a current I is generated. Hereby an electromagnetic force is overcoming the force applied by the spring 293 and the sealing member 291 is moved from the second position P2 to the first position PI. Hereby dosing of reducing agent is controlled. Dosing of the pressurized reducing agent is performed when the valve unit is in said open state OS. When the applied voltage U is shut off, the spring 293 will affect the valve unit to change from said open state OS to said closed state CS. The first control unit 200 is arranged to continuously determine the prevailing current I in said electrical wiring 292. The current I is presenting variations over time due to the electromagnetic force. Figure 3a is illustrating a diagram wherein a voltage U being applied over the coil 292 is given as a function of time t. In the diagram also a prevailing current in the coil 292 is given as a function of time t. The voltage U is given in Volt (V), the prevailing current I is given in milliampere (mA) and the time t is given in milliseconds (ms). According to this diagram one general working principle of the dosing unit 237 is depicted. The proposed working principle is depicted with reference to Figure 3b below.
At a point of time tO a peak voltage Ul is applied over the coil 292. The peak voltage Ul may be any suitable voltage sufficient for achieving the sealing member 291 to move from the second position P2 to the first position PI, i.e. to set the valve unit of the dosing unit 237 in the open state OS. The peak voltage Ul is according to one example a predetermined voltage, e.g. 24V. According to one embodiment the peak voltage Ul is 12V. This value may be relevant in case the vehicle 100 is a car. According to one embodiment the peak voltage Ul is 60V.
The prevailing current I in the coil is hereby initially increasing and at a time point when the sealing member 291 is actually moved a first temporarily dip is observed. The current I is increasing to a top level before a point of time tl.
The peak voltage Ul is applied during a time period tO-tl. At the point of time tl the peak voltage Ul is shifted to a hold voltage U2. The hold voltage U2 may be any suitable voltage sufficient for maintaining the sealing member 291 in the first position PI, i.e. to keep the valve unit in the open state OS. The hold voltage U2 is lower than the peak voltage Ul. The hold voltage U2 is according to one example a predetermined voltage, e.g. 18V (e.g. in a case where the peak voltage Ul is 24V). According to one example the hold voltage U2 is any suitable voltage being lower than the peak voltage Ul and higher than 0V.
The hold voltage U2 is applied during a certain time period. During this time period the prevailing current I in said coil 291 is stabilized at a certain level.
At the point of time t2 the hold voltage U2 is shifted to a level of zero (0) voltage and hereby the prevailing current I is decreasing from said certain level to a value of zero (0) mA. At a point of time t5 the current I has reached 0V. At a point of time t4 the sealing member 291 is moved from the first position PI to the second position P2 by means of the applied spring force, i.e. the valve unit of the dosing unit 237 is set to the closed state CS. The movement of the sealing member 291 is affecting the course of the current I (at t3 and t4).
Figure 3b is illustrating a diagram wherein the principles of the present invention according to an embodiment are depicted.
Herein the voltage U applied over the coil 292 is given as a function of time t. In the diagram also a prevailing current in the coil 292 is given as a function of time t. The voltage U is given in Volt (V), the prevailing current I is given in milliampere (mA) and the time t is given in milliseconds (ms). At a point of time tO a peak voltage Ul is applied over the coil 292. The peak voltage Ul may be any suitable voltage sufficient for achieving the sealing member 291 to move from the second position P2 to the first position PI, i.e. to set the valve unit of the dosing unit 237 in the open state OS. The peak voltage Ul is according to one example a predetermined voltage, e.g. 24V. The prevailing current I in the coil is hereby initially increasing and at a time point (t3) when the sealing member 291 is actually moved a first temporarily dip is observed. The current I is increasing to a top level before a point of time tl.
The peak voltage Ul is applied during a time period tO-tl. At the point of time tl the peak voltage Ul is shifted to a hold voltage U2. The hold voltage U2 may be any suitable voltage sufficient for maintaining the sealing member 291 in the first position, i.e. to keep the valve unit in the open state OS. The hold voltage U2 is lower than the peak voltage Ul. The hold voltage U2 is according to one example a predetermined voltage, e.g. 18V.
According to this embodiment the prevailing current I in the coil 292 is continuously detected by means of the first control unit 200. According to one example the prevailing current I in the coil 292 is continuously detected by means of the first control unit 200 only after the point of time tl. The hold voltage U2 is applied during a time period tl-t2. During this time period the prevailing current in said coil 291 has not necessarily been stabilized at a certain level but may be changing.
At the point of time t2 the hold voltage U2 is shifted to a level of zero (0) voltage and hereby the prevailing current I is decreasing from said certain level to a value of zero (0) mA (which is reached at t5). After the point of time t2 the sealing member 291 is moved from the first position PI to the second position P2, i.e. the valve unit of the dosing unit 237 is set to the closed state CS (at t4).
According to one example the prevailing current I in said coil 292 is determined just prior to shifting from said hold voltage U2 to zero voltage. Hereby an actual discharge time period Tdischargeactual is determined on the basis the thus determined prevailing current, which current value lx is associated with a time point just prior to shifting from said hold voltage U2 to zero voltage.
Hereby a compensation value COMP may be determined on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period
Tdischargenominal.
A difference between the nominal discharge time period Tdischargenominal and actual discharge time period Tdischargeactual is equal the compensation value COMP:
Tdischargenominal - Tdischargeactual COMP
Hereby the actual end of injection time period TEOIactual may be adjusted the basis on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP.
The actual end of injection time period may be defined as: TEOIactual= TEOInominal + COMP TEOInominal is a predetermined value and is valid for a certain degree of charge of said coil 292. The nominal end of injection time period may be empirically determined for a given nominal discharge time period TEOInominal.
According to an embodiment the operation of said dosing unit 237 is advantageously controlled taking into account said determined actual end of injection time period
TEOIactual.
It is noted that the point of time t2 according to this example is substantially earlier than a corresponding point of time t2, which is related to the diagram of Figure 3a.
Comparing the course of the current it is noted that the point of time t2 is earlier according to this example than the point of time as given with reference to Figure 3a. According to this example the applied hold voltage U2 is set to 0 voltage before, or at an early stage, of a steady state condition of the current I. The steady state condition of the current I and the applied hold voltage U2 as given with reference to Figure 3a is depicted with broken lines in Figure 3b for comparison reasons.
According to an alternative embodiment the following may be implemented in the proposed method:
Tdischargeactual/Tdischargenominal= COMP; and thus TEOIactual= TEOInominal*COMP
Figure 3c is illustrating a diagram wherein a position P of the sealing member 291 is a presented as a function of time t. The position P is given in millimetres (mm) and the time is given in milliseconds (ms).
The diagram also presents voltage U applied over the coil 292 is given as a function of time t in accordance with the teachings in Figure 3b. It is illustrated that there is a time delay associated with the actual opening process of the sealing member 291 from the time point tO when the peak voltage Ul is applied to a point of time t3 when the sealing member 291 is actually moved to the first position PI from the second position P2. In a similar way there is a time delay associated with the actual closing process of the sealing member 291 from the time point t2 when the hold voltage U2 is reduced to zero voltage to a point of time t4 when the sealing member 291 is actually moved to the second position P2 from the first position PI.
In accordance with the example in Figure 3b the peak voltage Ul is shifted to the hold voltage U2 at the point of time tl. At a point of time t5 the current in the coil 292 becomes 0mA.
Herein it is given that:
t2— tO = treq + tstartof injection— tendof injection
treq refers to the time period during which the dosing unit must be in the open state (OS) in order to supply the required amount of fluid; tstartofinjection is herein denoted t3;
tendofinjection is herein denoted t4.
Figure 4a schematically illustrates a flow chart of a method for controlling operation of a dosing unit 237 of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
The method comprises a first method step s401. The method step s401 comprises the steps of: - applying a peak voltage Ul over said coil 292;
- shifting said applied peak voltage Ul to a hold voltage U2;
- just prior to shifting from said hold voltage U2 to zero voltage, determining a prevailing current lx in said coil 292; - determining an actual discharge time period Tdischargeactual on the basis of the thus determined prevailing current lx;
- determining a compensation value COMP on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period Tdischargenominal;
- adjusting an actual end of injection time period TEOIactual on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP;
- controlling operation of said dosing unit taking into account said determined actual end of injection time period TEOIactual.
After the method step s401 the method ends/is returned.
Figure 4b schematically illustrates a method for controlling operation of a dosing unit of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
The method comprises a first method step s410. The method step s410 comprises the step of
- applying a peak voltage Ul over said coil 292. This is performed by means of the first control unit 200. The peak voltage Ul may be any suitable voltage. The peak voltage Ul may be a predetermined voltage, e.g. 24V. Hereby a current I is increasing in the coil 292, and by means of the electromagnetic force the sealing member is moved to the second position P2 from the first position PI at a point of time t3 (see Figure 3c) when the electromagnetic force is overcoming the force of the spring 293. After the method step s410 a subsequent method step s420 is performed.
The method step s420 comprises the step of shifting said applied peak voltage Ul to a hold voltage U2. This is performed by means of the first control unit 200. The voltage shifting is performed at a point of time tl (see Figure 3b and 3c). The hold voltage U2 may be any suitable voltage. The hold voltage U2 is lower than the peak voltage Ul.The hold voltage U2 may be a predetermined voltage, e.g. 18V. The hold voltage U2 is sufficient to overcome the force of the spring 293 and thus keep the sealing member 291 in the first position PI whereby dosing is achieved. After the method step s420 a subsequent method step s430 is performed.
The method step s430 comprises the step of just prior to shifting from said hold voltage U2 to zero voltage, determining a prevailing current lx in said coil 292. This is performed by means of the first control unit 200. The point of time t2 when the shifting from the hold voltage U2 to zero voltage is determined by means of the first control unit 200. The step of shifting from said hold voltage U2 to zero voltage may be performed prior to an steady state situation regarding the current I in the coil 291 and the energy state of the coil has occurred. Advantageously the point of time t2 is hereby relatively close in time to the point of time tl. Herein the term "just prior" is any suitable point of time before the point of time t2. Herein the term "just prior" may be determined to be a point of time defined by a predetermined time interval before the point of time t2. The term "just prior" may be e.g. 1, 3 or 5 milliseconds before the point of time t2. The term "just prior" may be parts of 1 millisecond before the point of time t2, such as 0.5 milliseconds or 0.3 milliseconds. After the method step s430 a subsequent method step s440 is performed.
The method step s440 comprises the step of determining an actual discharge time period Tdischargeactual on the basis of the thus determined prevailing current lx. This may be performed by means of the first control unit 200. According to one example the actual discharge time period Tdischargeactual is performed substantially in real time. According to one example the actual discharge time period Tdischargeactual is determined by using a table which is stored in a memory of the first control unit 200. Hereby a number of empirically determined values of actual discharge time period Tdischargeactual are stored in the memory and a most relevant value is selected on the basis of the determined prevailing current lx. After the method step s440 a subsequent method step s450 is performed.
The method step s450 comprises the step of determining a compensation value COMP on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period Tdischargenominal. This is performed by means of the first control unit 200. By determining a difference between nominal discharge time period Tdischargenominal and the actual discharge time period Tdischargeactual the compensation value COMP may be determined. The nominal discharge time period Tdischargenominal may be a predetermined value. This is also depicted with reference to Figure 3c. After the method step s450 a subsequent method step s460 is performed.
The method step s460 comprises the step of adjusting an actual end of injection time period TEOIactual on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP. This is performed by means of the first control unit 200. The actual end of injection time period TEOIactual is equal to the nominal end of injection time period TEOInominal added to the compensation value COMP.
After the method step s460 a subsequent method step s470 is performed.
The method step s470 comprises the step of controlling operation of said dosing unit taking into account said determined actual end of injection time period TEOIactual. By controlling the operation of the dosing unit 237 on the basis of the adjusted actual end of injection time period TEOIactual an improved operation of the dosing unit 237 is achieved. The method step s470 may comprise the step of controlling operation of said dosing unit on the basis of a time difference between a point in time tO when the peak voltage Ul is applied and a point of time t2 when said hold voltage U2 is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period TEOIactual and a start of injection time period TSOI.
After the method step s470 the method is returned/ended.
Figure 5 is a diagram of one version of a device 500. The control units 200 and 210 described with reference to Figure 2a and Figure 2b may in one version comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540.
The computer program P comprises routines for controlling operation of a dosing unit 237 of a fluid dosing system comprising an electrically controlled valve unit having a coil 292 arranged for shifting said valve unit between an open state OS and a closed state CS by moving a sealing member 291 between a first position PI and a second position P2.
The computer program P may comprise routines for applying a peak voltage Ul over said coil 292. The computer program P may comprise routines for shifting said applied peak voltage Ul to a hold voltage U2. The computer program P may comprise routines for just prior to shifting from said hold voltage U2 to zero voltage, determining a prevailing current in said coil. The computer program P may comprise routines for determining an actual discharge time period Tdischargeactual on the basis of the thus determined prevailing current. The computer program P may comprise routines for determining a compensation value COMP on the basis of said actual discharge time period Tdischargeactual and a nominal discharge time period Tdischargenominal. The computer program P may comprise routines for adjusting an actual end of injection time period TEOIactual on the basis of a nominal end of injection time period TEOInominal and said compensation value COMP. The computer program P may comprise routines for controlling operation of said dosing unit taking into account said determined actual end of injection time period TEOIactual.
The computer program P may comprise routines for shifting from said hold voltage U2 to zero voltage prior to an steady state situation regarding the current in the coil and the energy state of the coil 292 has occurred.
The computer program P may comprise routines for controlling operation of said dosing unit on the basis of a time difference between a point in time when the peak voltage Ul is applied and a point of time when said hold voltage U2 is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period TEOIactual and a start of injection time period TSOI.
The computer program P may comprise routines for performing any of the process steps detailed with reference to Figure 4a and Figure 4b.
The program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550.
Where it is stated that the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is stored in the read/write memory 550.
The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit via a data bus 511. The read/write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514. The links L210, L230, L231 and L237 for example, may be connected to the data port 599 (see Fig. 2a and 2b). When data are received on the data port 599, they are stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 will be prepared to conduct code execution as described above.
Parts of the methods herein described may be conducted by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, method steps and process steps herein described are executed.
The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the variants described. Many modifications and variations will obviously suggest themselves to one skilled in the art. The embodiments have been chosen and described in order to best explain the principles of the invention and their practical applications and thereby make it possible for one skilled in the art to understand the invention for different embodiments and with the various modifications appropriate to the intended use.

Claims

Claims
1. A method for controlling operation of a dosing unit (237) of a fluid dosing system comprising an electrically controlled valve unit having a coil (292) arranged for shifting said valve unit between an open state (OS) and a closed state (CS) by moving a sealing member (291) between a first position (PI) and a second position (P2), the method comprising the steps of:
- applying (s410) a peak voltage (Ul) over said coil (291);
- shifting (s420) said applied peak voltage (Ul) to a hold voltage (U2);
- just prior to shifting from said hold voltage (U2) to zero voltage, determining (s430) a prevailing current (lx) in said coil (292);
- determining (s440) an actual discharge time period (Tdischargeactual) on the basis of said thus determined prevailing current (lx);
- determining (s450) a compensation value (COMP) on the basis of said actual discharge time period (Tdischargeactual) and a nominal discharge time period (Tdischargenominal); - adjusting (s460) an actual end of injection time period (TEOIactual) on the basis of a nominal end of injection time period (TEOInominal) and said compensation value (COMP);
- controlling (s470) operation of said dosing unit (237) taking into account said determined actual end of injection time period (TEOIactual).
2. The method according to claim 1, wherein the step of shifting from said hold voltage (U2) to zero voltage is performed prior to an steady state situation regarding said current (I) in said coil (292) and the energy state of said coil (291) has occurred.
3. The method according to claim 1 or 2, comprising the step of: - controlling (470) operation of said dosing unit (237) on the basis of a time difference between a point in time (tO) when said peak voltage (Ul) is applied and a point of time (t2) when said hold voltage (U2) is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time adjusted by said actual end of injection time period (TEOIactual) and a start of injection time period (TSOI).
4. A system for controlling operation of a dosing unit (237) of a fluid dosing system comprising an electrically controlled valve unit having a coil (292) arranged for shifting said valve unit between an open state (OS) and a closed state (CS) by moving a sealing member (291) between a first position (PI) and a second position (P2), the system comprising:
- means (200; 210; 500) being arranged for applying a peak voltage (Ul) over said coil (292);
- means (200; 210; 500) being arranged for shifting said applied peak voltage (Ul) to a hold voltage (U2);
- means (200; 210; 500) being arranged for, just prior to shifting from said hold voltage (U2) to zero voltage, determining a prevailing current (lx) in said coil (292);
- means (200; 210; 500) being arranged for determining an actual discharge time period (Tdischargeactual) on the basis of said thus determined prevailing current (lx);
- means (200; 210; 500) being arranged for determining a compensation value (COMP) on the basis of said actual discharge time period (Tdischargeactual) and a nominal discharge time period (Tdischargenominal);
- means (200; 210; 500) being arranged for adjusting an actual end of injection time period (TEOIactual) on the basis of a nominal end of injection time period (TEOInominal) and said compensation value (COMP);
- means (200; 210; 500) being arranged for controlling operation of said dosing unit (237) taking into account said determined actual end of injection time period (TEOIactual).
5. The system according to claim 4, comprising: - means (200; 210; 500) being arranged for shifting from said hold voltage (U2) to zero voltage prior to an steady state situation regarding said current in said coil (292) and the energy state of said coil (292) has occurred.
6. The system according to claim 4 or 5, comprising:
- means (200; 210; 500) being arranged for controlling operation of said dosing unit (237) on the basis of a time difference between a point in time (tO) when said peak voltage (Ul) is applied and a point of time (t2) when said hold voltage (U2) is shifted to zero voltage, wherein said time difference is calculated as a requested dosing time (treq) adjusted by said actual end of injection time period (TEOIactual) and a start of injection time period (TSOI).
7. A vehicle (100; 110) comprising a system according to any one of claims 4-6.
8. The vehicle (100; 110) according to claim 7, which vehicle is any from among a truck, bus or passenger car.
9. A computer program (P) for controlling operation of a dosing unit (237) of a fluid dosing system comprising an electrically controlled valve unit having a coil (292) arranged for shifting said valve unit between an open state (OS) and a closed state (CS) by moving a sealing member (291) between a first position (PI) and a second position (P2), wherein the computer program (P) comprises program code for causing an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500) to perform the steps according to any one of the claims 1-3.
10. A computer program product containing a program code stored on a computer-readable medium for performing method steps according to any one of claims 1-3, when the computer program is run on an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500).
PCT/SE2019/050216 2018-03-15 2019-03-11 System and method for controlling operation of a dosing unit of a fluid dosing system WO2019177522A1 (en)

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EP2375041A2 (en) * 2010-04-08 2011-10-12 Delphi Technologies, Inc. System and method for controlling an injection time of a fuel injector
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SE544931C2 (en) * 2021-05-20 2023-01-10 Scania Cv Ab Method and circuitry for controlling discharge of a solenoid valve

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SE1850289A1 (en) 2019-09-16
DE112019000809T5 (en) 2020-11-05

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