EP1138920B1 - Steuerverfahren und Vorrichtung zur Mehrstellungventilbetätigung in einem Kraftstoffeinspritzsystem - Google Patents

Steuerverfahren und Vorrichtung zur Mehrstellungventilbetätigung in einem Kraftstoffeinspritzsystem Download PDF

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Publication number
EP1138920B1
EP1138920B1 EP20000106987 EP00106987A EP1138920B1 EP 1138920 B1 EP1138920 B1 EP 1138920B1 EP 20000106987 EP20000106987 EP 20000106987 EP 00106987 A EP00106987 A EP 00106987A EP 1138920 B1 EP1138920 B1 EP 1138920B1
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Prior art keywords
acting
seat
predefined
monitored
valve
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EP20000106987
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English (en)
French (fr)
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EP1138920A1 (de
Inventor
Johannes-Joerg Rueger
Udo Schulz
Patrick Mattes
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Robert Bosch GmbH
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Robert Bosch GmbH
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Priority to EP20000106987 priority Critical patent/EP1138920B1/de
Priority to DE2000615922 priority patent/DE60015922T2/de
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0026—Valves characterised by the valve actuating means electrical, e.g. using solenoid using piezoelectric or magnetostrictive actuators
    • 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
    • F02D41/2096—Output circuits, e.g. for controlling currents in command coils for controlling piezoelectric injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
    • F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure

Definitions

  • the present invention concerns a method as defined in the preamble of claim 1 and an apparatus as defined in the preamble of claim 23, i.e. a control method and a control apparatus for a multiple-acting valve within a fuel injection system.
  • Fuel injection systems are essential components of internal combustion engines. They may be implemented either with individual or with shared fuel supply lines for each fuel injection nozzle (the second alternative is also referred to as common rail systems, shortly: CR systems). In each case, fuel injections are controlled by means of opening and closing fuel injection nozzles in a predefined way.
  • the multiple-acting valves are used to execute the opening and the closing of the fuel injection nozzles.
  • a piezoelectric element may be used to actuate the multiple-acting valve.
  • Fig. 5 is a schematic representation of a fuel injection system using a piezoelectric element 2010 as an actuator.
  • piezoelectric element 2010 is electrically energized to expand and contract in response to a given activation voltage.
  • Piezoelectric element 2010 is coupled to a piston 2015.
  • piezoelectric element 2010 causes piston 2015 to protrude into hydraulic adapter 2020 which contains a hydraulic fluid, for example fuel.
  • double-acting control valve 2025 is hydraulically pushed away from hydraulic adapter 2020 and valve plug 1000 is extended away from first closed position, or seat, 1.
  • double-acting control valve 2025 and hollow bore 2050 is often referred to as double-acting, double seat valve for the reason that when piezoelectric element 2010 is in an unexcited state, double-acting control valve plug 1000 rests in first closed position 1. On the other hand, when piezoelectric element 2010 is fully extended, valve plug 1000 rests in second closed position, or seat, 2. The later position of valve plug 1000 is schematically represented with ghost lines in Fig. 5.
  • the fuel injection system comprises an injection needle 2070 allowing for injection of fuel from a pressurized fuel supply line 2060 at a pressure p into the cylinder (not shown).
  • the double-acting control valve plug 1000 rests respectively in its first closed position 1 or in its second closed position 2. In either case, the hydraulic rail pressure p maintains injection needle 2070 at a closed position. Thus, the fuel mixture does not enter into the cylinder (not shown).
  • the piezoelectric element 2010 is excited such that double-acting control valve plug 1000 is in the so-called midposition M with respect to the hollow bore 2050, then there is a pressure drop in the pressurized fuel supply line 2060.
  • fuel injection is controlled by means of applying voltages to the piezoelectric actuator which expands or contracts itself as a function of the voltage applied. Resulting thereof (but possibly with further use of transmission elements), the valve plug 1000 moves a corresponding distance ⁇ 1 between the first seat 1 and the open position M, and a distance ⁇ 2 between the open position M and the second seat 2, respectively.
  • a corresponding system can be found at German patent application Nos. DE 197 42 073 A1 which is considered as the closest prior art and DE 1976 29 844 A1.
  • These patent applications disclose piezoelectric elements with double-acting, double seat valves for controlling injection needles in a fuel injection system.
  • This object of the present invention is achieved by an object of method claim 1, i.e. by a control method for a multiple-acting valve within a fuel injection system, characterized in that the multiple-acting valve is controlled by a control unit as according to a predefined control scheme. At least one system parameter is monitored. The predefined control scheme and therefore the control of the multiple-acting valve is modified in case one or more of the monitored system parameters match predefined conditions.
  • a control apparatus for a multiple-acting valve within a fuel injection system characterized in that a control unit is implemented for control of the multiple-acting valve as according to a predefined control scheme.
  • Monitoring means are implemented for monitoring at least one system parameter.
  • Modification means are implemented for modification of the predefined control scheme and therefore the control of the multiple-acting valve in case one or more of the monitored system parameters match predefined conditions.
  • any predefined control scheme and therefore the control of the multiple-acting valve can be done on several ways.
  • an existing control scheme which is "stored" (i.e. the information of which is physically located) in any suitable storage of a control unit can be modified by means of replacing parts of it with new parts.
  • the same result is obtained by means of replacing the whole scheme with a new scheme, for example comprising the in the first case remaining old parts as well as the new parts.
  • modify the treatment and therefore the meaning of the control scheme instead of the scheme as it is stored itself for example, the control unit could move the double-acting control valve 2025 into its first seat 1 no matter if the control scheme requires either the first seat 1 or the second seat 2).
  • any other suitable way of obtaining a modified control of the fuel injection system can be used with the invention.
  • modification of a predefined control scheme any measure is addressed which results in a system control which is different from what it would be without the measure.
  • the multiple-acting control valve is a double-acting control valve which has a first seat corresponding to a first closed position, a second seat corresponding to a second closed position and an open position.
  • the multiple-acting control valve is actuated by means of a piezoelectric element.
  • the first seat corresponds to a first voltage applied to the piezoelectric element.
  • the second seat corresponds to a second voltage applied to the piezoelectric element which is larger than the first voltage.
  • the open position corresponds to a medium voltage applied to the piezoelectric element which is in between the first and the second voltage.
  • the fuel pressure is monitored and the predefined control scheme is modified in case the monitored pressure exceeds a predefined threshold (claim 4).
  • an injection is executed by means of moving the multiple-acting control valve from the first seat into the open position and instead of doing so, the multiple-acting control valve is moved from the second seat into the open position in case the monitored pressure exceeds a predefined threshold (claim 6).
  • the double-acting control valve 2025 is moved from its first seat 1 to the open position M against the pressure force but from its second seat 2 to the open position M with the pressure force.
  • an injection is executed by means of moving the multiple-acting valve from the first seat into the open position, the multiple-acting control valve is placed in its first seat, but, however, in order to execute the injection, the multiple-acting control valve is firstly moved from the first seat into the second seat before it is moved into the open position in case the monitored pressure exceeds a predefined threshold (claim 7).
  • two pre-injections are executed before a main injection takes place and the multiple-acting valve is moved into the first seat between the two pre-injections and instead, the multiple-acting control valve is moved into the second seat between the two pre-injections (claim 8).
  • the system temperature is monitored and the predefined control scheme is modified in case the monitored temperature is below a predefined threshold (claim 9).
  • the time gap between injections is monitored; and the predefined control scheme is modified in case the time gap between injections exceeds a predefined value (claim 10).
  • the status of the synchronicity of the system with respect to the camshaft and the crankshaft signal is monitored and the predefined control scheme is modified in case the system is not finally synchronized (claim 11).
  • the multiple-acting control valve is moved into the second seat after an injection is executed and instead of doing so, the multiple-acting control valve is moved into the first seat in case the monitored temperature and/or the time gap between these injections exceeds a predefined value and/or the system is not finally synchronized (claim 12).
  • an injection is executed by means of moving the multiple-acting control valve from the second seat into the open position and instead of doing so, the multiple-acting control valve is moved from the first seat into the open position in case the monitored temperature and/or the time gap between these injections exceeds a predefined value and/or the system is not finally synchronized (claim 13).
  • the multiple-acting control valve is moved into the second seat between the pre-injection and the main injection and instead of doing so, the multiple-acting control valve is moved into the first seat between the pre-injection and the main injection in case the monitored temperature and/or the time gap between these injections exceeds a predefined value and/or the system is not finally synchronized (claim 14).
  • both the fuel pressure and the system temperature are monitored and in case the pressure exceeds the predefined threshold and at the same time the temperature is below the predefined threshold the multiple-acting valve is controlled as if the pressure would not exceed the predefined threshold (claim 15).
  • the temperature dependency might be of major importance than the pressure dependency is. This in particular holds, in case the reduction of the lifting ability of the piezoelectric element is too large to safely have the double-acting control valve 2025 in its second seat 2. Hence, it is advantageous to ignore the exceeding of the pressure threshold which would lead to a preferred use of the second seat 2 without this rule.
  • the multiple-acting control valve is actuated by means of a piezoelectric element.
  • the buffer voltage in the charging circuit of the piezoelectric element is monitored and the control of the double-acting control valve is accordingly modified.
  • any injection is executed by moving the valve from first seat 1 to the midway portion and back to first seat 1 instead of moving it to second seat 2.
  • This rule has priority over other rules.
  • the monitored system parameters and/or any combination of two or more of the monitored system parameters are ranked in a priority ordering and the predefined control scheme and therefore the control of the multiple-acting valve is modified based on the monitored system parameter or combination of the monitored system parameters having the highest priority ranking.
  • Fig. 6 which shows a schematic diagram of an exemplary piezoelectric element control system for a fuel injection system.
  • the detailed area A comprises a circuit for charging and discharging piezoelectric elements 10, 20, 30, 40, 50 and 60.
  • these piezoelectric elements 10, 20, 30, 40, 50, 60 are actuators in fuel injection nozzles (in particular in so-called common rail injectors) of an internal combustion engine.
  • Piezoelectric elements can be used for such purposes because, as is known, they possess the property of contracting or expanding as a function of a voltage applied thereto or occurring therein.
  • the non-detailed area B comprises a control unit D and an activation IC E by both of which the elements within the detailed area A are controlled, as well as measuring components F for measuring occurring rail pressures.
  • the circuit within the detailed area A comprises six piezoelectric elements 10, 20, 30, 40, 50, 60.
  • the reason to take six piezoelectric elements 10, 20, 30, 40, 50, 60 in the embodiment described is to independently control six cylinders within a combustion engine; hence, any other number of piezoelectric elements might match any other purpose.
  • the piezoelectric elements 10, 20, 30, 40, 50, 60 are distributed into a first group, or bank, G1 and a second group, or bank, G2, each comprising three piezoelectric elements (i.e., piezoelectric elements 10, 20 and 30 in the first group G1 and piezoelectric elements 40, 50 and 60 in the second group G2).
  • Groups G1 and G2 are constituents of circuit parts connected in parallel with one another.
  • Group selector switches 310, 320 can be used to establish which of the groups G1, G2 of piezoelectric elements 10, 20 and 30 and 40, 50 and 60, respectively, will be discharged in each case by a common charging and discharging apparatus (however, the group selector switches 310, 320 are meaningless for charging procedures, as is explained in further detail below).
  • the group selector switches 310, 320 are arranged between a coil 240 and the respective groups G1 and G2 (the coil-side terminals thereof) and are implemented as transistors.
  • Side drivers 311, 321 are implemented which transform control signals received from the activation IC E into voltages which are eligible for closing and opening the switches as required.
  • Diodes 315 and 325 are provided in parallel with the group selector switches 310, 320. If the group selector switches 310, 320 are implemented as MOSFETs or IGBTs, for example, these group selector diodes 315, 325 can be constituted by the parasitic diodes themselves. The diodes 315, 325 bypass the group selector switches 310, 320 during charging procedures. Hence, the functionality of the group selector switches 310, 320 is reduced to select a group G1, G2 of piezoelectric elements 10, 20 and 30, resp. 40, 50 and 60 for a discharging procedure only.
  • each piezo branch comprises a series circuit made up of a first parallel circuit comprising a piezoelectric element 10, 20, 30, 40, 50 resp. 60 and a resistor 13, 23, 33, 43, 53 resp. 63 (referred to as branch resistors) and a second parallel circuit made up of a selector switch implemented as a transistor 11, 21, 31, 41, 51 resp. 61 (referred to as branch selector switches) and a diode 12, 22, 32, 42, 52 resp. 62 (referred to as branch diodes).
  • the branch resistors 13, 23, 33, 43, 53 resp. 63 cause each corresponding piezoelectric element 10, 20, 30, 40, 50 resp. 60 during and after a charging procedure to continuously discharge themselves, since they connect both terminals of each capacitive piezoelectric element 10, 20, 30, 40, 50, resp. 60 one to another.
  • the branch resistors 13, 23, 33, 43, 53 resp. 63 are sufficiently large to make this procedure slow compared to the controlled charging and discharging procedures as described below.
  • the branch selector switch/branch diode pairs in the individual piezo branches 110, 120, 130, 140, 150 resp.160 i.e., selector switch 11 and diode 12 in piezo branch 110, selector switch 21 and diode 22 in piezo branch 120, and so on, can be implemented using electronic switches (i.e., transistors) with parasitic diodes, for example MOSFETs or IGBTs (as stated above for the group selector switch/diode pairs 310 and 315 resp. 320 and 325).
  • the piezoelectric elements 10, 20, 30, 40, 50 or 60 can be used to establish which of the piezoelectric elements 10, 20, 30, 40, 50 or 60 will be charged in each case by a common charging and discharging apparatus: in each case, the piezoelectric elements 10, 20, 30, 40, 50 or 60 that are charged are all those whose branch selector switches 11, 21, 31, 41, 51 or 61 are closed during the charging procedure which is described below.
  • the branch diodes 12, 22, 32, 42, 52 and 62 serve for bypassing the branch selector switches 11, 21, 31, 41, 51 resp. 61 during discharging procedures.
  • any individual piezoelectric element can be selected, whereas for discharging procedures either the first group G1 or the second group G2 of piezoelectric elements 10, 20 and 30 resp. 40, 50 and 60 or both have to be selected.
  • the branch selector piezo terminals 15, 25, 35, 45, 55 resp. 65 may be connected to ground either through the branch selector switches 11, 21, 31, 41, 51 resp. 61 or through the corresponding diodes 12, 22, 32, 42, 52 resp. 62 and in both cases additionally through resistor 300.
  • resistor 300 The purpose of resistor 300 is to measure the currents that flow during charging and discharging of the piezoelectric elements 10, 20, 30, 40, 50 and 60 between the branch selector piezo terminals 15, 25, 35, 45, 55 resp. 65 and the ground. A knowledge of these currents allows a controlled charging and discharging of the piezoelectric elements 10, 20, 30, 40, 50 and 60. In particular, by closing and opening charging switch 220 and discharging switch 230 in a manner dependent on the magnitude of the currents, it is possible to set the charging current and discharging current to predefined average values and/or to keep them from exceeding or falling below predefined maximum and/or minimum values as is explained in further detail below.
  • the measurement itself further requires a voltage source 621 which supplies a voltage of, for example, 5 V DC and a voltage divider implemented as two resistors 622 and 623.
  • a voltage source 621 which supplies a voltage of, for example, 5 V DC and a voltage divider implemented as two resistors 622 and 623.
  • each piezoelectric element 10, 20, 30, 40, 50 and 60 i.e. the group selector piezo terminal 14, 24, 34, 44, 54 resp. 64
  • the other terminal of each piezoelectric element 10, 20, 30, 40, 50 and 60 may be connected to the plus pole of a voltage source via the group selector switch 310 resp. 320 or via the group selector diode 315 resp. 325 as well as via a coil 240 and a parallel circuit made up of a charging switch 220 and a charging diode 221, and alternatively or additionally connected to ground via the group selector switch 310 resp. 320 or via diode 315 resp. 325 as well as via the coil 240 and a parallel circuit made up of a discharging switch 230 or a discharging diode 231.
  • Charging switch 220 and discharging switch 230 are implemented as transistors which are controlled via side drivers 222 resp. 232.
  • the voltage source comprises an element having capacitive properties which, in the example being considered, is the (buffer) capacitor 210.
  • Capacitor 210 is charged by a battery 200 (for example a motor vehicle battery) and a DC voltage converter 201 downstream therefrom.
  • DC voltage converter 201 converts the battery voltage (for example, 12 V) into substantially any other DC voltage (for example 250 V), and charges capacitor 210 to that voltage.
  • DC voltage converter 201 is controlled by means of transistor switch 202 and resistor 203 which is utilized for current measurements taken from a measuring point 630.
  • a further current measurement at a measuring point 650 is allowed by activation IC E as well as by resistors 651, 652 and 653 and a, for example, 5 V DC voltage source 654; moreover, a voltage measurement at a measuring point 640 is allowed by activation IC E as well as by voltage dividing resistors 641 and 642.
  • a resistor 330 (referred to as total discharging resistor), a stop switch implemented as a transistor 331 (referred to as stop switch), and a diode 332 (referred to as total discharging diode) serve to discharge the piezoelectric elements 10, 20, 30, 40, 50 and 60 (if they happen to be not discharged by the "normal" discharging operation as described further below).
  • Stop switch 331 is preferably closed after “normal” discharging procedures (cycled discharging via discharge switch 230). It thereby connects piezoelectric elements 10, 20, 30, 40, 50 and 60 to ground through resistors 330 and 300, and thus removes any residual charges that might remain in piezoelectric elements 10, 20, 30, 40, 50 and 60.
  • the total discharging diode 332 prevents negative voltages from occurring at the piezoelectric elements 10, 20, 30, 40, 50 and 60, which might in some circumstances be damaged thereby.
  • Charging and discharging of all the piezoelectric elements 10, 20, 30, 40, 50 and 60 or any particular one is accomplished by way of a single charging and discharging apparatus (common to all the groups and their piezoelectric elements).
  • the common charging and discharging apparatus comprises battery 200, DC voltage converter 201, capacitor 210, charging switch 220 and discharging switch 230, charging diode 221 and discharging diode 231 and coil 240.
  • each piezoelectric element works the same way and is explained in the following while referring to the first piezoelectric element 10 only.
  • the selection of one or more particular piezoelectric elements 10, 20, 30, 40, 50 or 60 to be charged or discharged, the charging procedure as described in the following as well as the discharging procedure are driven by activation IC E and control unit D by means of opening or closing one or more of the above introduced switches 11, 21, 31, 41, 51, 61; 310, 320; 220, 230 and 331.
  • activation IC E and control unit D The interactions between the elements within the detailed area A on the on hand and activation IC E and control unit D on the other hand are described in detail further below.
  • any particular piezoelectric element 10, 20, 30, 40, 50 or 60 which is to be charged has to be selected.
  • the branch selector switch 11 of the first branch 110 is closed, whereas all other branch selector switches 21, 31, 41, 51 and 61 remain opened.
  • the charging procedure requires a positive potential difference between capacitor 210 and the group selector piezo terminal 14 of the first piezoelectric element 10.
  • charging switch 220 and discharging switch 230 are open no charging or discharging of piezoelectric element 10 occurs.
  • the circuit shown in Fig. 6 is in a steady-state condition, i.e., piezoelectric element 10 retains its charge state in substantially unchanged fashion, and no currents flow.
  • charging switch 220 In order to charge the first piezoelectric element 10, charging switch 220 is closed. Theoretically, the first piezoelectric element 10 could become charged just by doing so. However, this would produce large currents which might damage the elements involved. Therefore, the occurring currents are measured at measuring point 620 and switch 220 is opened again as soon as the detected currents exceed a certain limit. Hence, in order to achieve any desired charge on the first piezoelectric element 10, charging switch 220 is repeatedly closed and opened whereas discharging switch 230 remains open.
  • a closed circuit comprising a series circuit made up of piezoelectric element 10, capacitor 210, and coil 240 is formed, in which a current i LE (t) flows as indicated by arrows in Fig. 7a.
  • a current i LE (t) flows as indicated by arrows in Fig. 7a.
  • a closed circuit comprising a series circuit made up of piezoelectric element 10, charging diode 221, and coil 240 is formed, in which a current i LA (t) flows as indicated by arrows in Fig. 7b.
  • the result of this current flow is that energy stored in coil 240 flows into piezoelectric element 10.
  • the voltage occurring in the latter, and its external dimensions increase.
  • charging switch 220 is once again closed and opened again, so that the processes described above are repeated.
  • the energy stored in piezoelectric element 10 increases (the energy already stored in the piezoelectric element 10 and the newly delivered energy are added together), and the voltage occurring at the piezoelectric element 10, and its external dimensions, accordingly increase.
  • charging switch 220 has closed and opened a predefined number of times, and/or once piezoelectric element 10 has reached the desired charge state, charging of the piezoelectric element is terminated by leaving charging switch 220 open.
  • the piezoelectric elements 10, 20, 30, 40, 50 and 60 are discharged in groups (G1 and/or G2) as follows:
  • the group selector switch(es) 310 and/or 320 of the group or groups G1 and/or G2 the piezoelectric elements of which are to be discharged are closed (the branch selector switches 11, 21, 31, 41, 51, 61 do not affect the selection of piezoelectric elements 10, 20, 30, 40, 50, 60 for the discharging procedure, since in this case they are bypassed by the branch diodes 12, 22, 32, 42, 52 and 62).
  • the first group selector switch 310 is closed.
  • a closed circuit comprising a series circuit made up of piezoelectric element 10 and coil 240 is formed, in which a current i EE (t) flows as indicated by arrows in Fig. 7c.
  • the result of this current flow is that the energy (a portion thereof) stored in the piezoelectric element is transported into coil 240.
  • the voltage occurring at the piezoelectric element 10 decrease.
  • a closed circuit comprising a series circuit made up of piezoelectric element 10, capacitor 210, discharging diode 231, and coil 240 is formed, in which a current i EA (t) flows as indicated by arrows in Fig. 7d.
  • a current i EA (t) flows as indicated by arrows in Fig. 7d.
  • discharging switch 230 is once again closed and opened again, so that the processes described above are repeated.
  • the energy stored in piezoelectric element 10 decreases further, and the voltage occurring at the piezoelectric element, and its external dimensions, also accordingly decrease.
  • discharging switch 230 Once discharging switch 230 has closed and opened a predefined number of times, and/or once the piezoelectric element has reached the desired discharge state, discharging of the piezoelectric element 10 is terminated by leaving discharging switch 230 open.
  • a fuel injection system with a double-acting control valve 10 as described above (while referring to Fig. 5) is considered.
  • the double-acting control valve 10 has a first seat 1 corresponding to a first closed position, a second seat 2 corresponding to a second closed position and an open position M.
  • any other multiple-acting control valve may be used with the invention.
  • a further double-acting control valve might have one closed position and two open positions; or, generally, the multiple-acting valve might have more open and/or closed positions.
  • the double-acting control valve 2025 is actuated by means of a piezoelectric element (not shown).
  • the first seat 1 corresponds to a first voltage applied to the piezoelectric element
  • the second seat 2 corresponds to a second voltage applied to the piezoelectric element which is larger than the first voltage
  • the open position corresponds to a medium voltage applied to the piezoelectric element which is in between the first and the second voltage.
  • each graph (1), (2), (3) and (4) quantities are depicted as functions of the time during the same time slot.
  • the base axis of each graph (1), (2), (3) and (4) is a time axis t, with the time axes t of the four graphs (1), (2), (3) and (4) being equal one to another.
  • the remaining axis is a amount-of-injection axis I and injections are depicted.
  • the remaining axes are a voltage axes and voltages applied to the piezoelectric actuators are depicted.
  • an exemplary injection profile is depicted, which comprises a first pre-injection starting at a first time t 1 and terminated at a second time t 2 , a second pre-injection starting at a third time t 3 and terminated at a fourth time t 4 , a main injection starting at a fifth time t 5 and terminated at a sixth time t 6 , and a post-injection starting at a seventh time t 7 and terminated at a eighth time t 8 .
  • Each injection is indicated by means of an injection amount I M which corresponds to the injection occurring while the double-acting control valve 2025 is in its open position M and which, for simplicity, is depicted as constant during the starting time and the termination time.
  • any other injection profile as well as any function of the injection amount I over the time can be used without any effect to the invention.
  • a predefined control scheme for the double-acting control valve 2025 is depicted, which is eligible to execute the above described injection profile.
  • the double-acting control valve 2025 is in its first seat 1 and a corresponding low voltage V 1 is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its open position M and a corresponding medium voltage V M is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved back into its first seat 1 and the corresponding low voltage V 1 is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its open position M and a corresponding medium voltage V M is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its second seat 2 and a corresponding high voltage V 2 is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its open position M and a corresponding medium voltage V M is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its first seat 1 and the corresponding low voltage V 1 is applied to the piezoelectric actuator.
  • the double-acting control valve 2025 is moved into its open position M and a corresponding medium voltage V M is applied to the piezoelectric actuator. Finally, at the eighth time t 8 the double-acting control valve 2025 is moved back into its first seat 1 and the corresponding low voltage V 1 is applied to the piezoelectric actuator.
  • any other suitable predefined control scheme for the double-acting control valve 2025 may be used with the invention.
  • the voltages applied to the piezoelectric actuator may be obtained immediately or in accordance with any suitable function of the voltage over the time without any effect to the invention.
  • the voltages may be obtained in steps.
  • the voltages applied to the actuator to realize an injection may differ depending on whether the valve is moved from seat 1 or seat 2 into the midway position.
  • the corresponding modification is executed because the fuel pressure within the fuel injection system, which is monitored for this purpose, exceeds a predefined threshold (p>p- max ).
  • a predefined threshold p>p- max .
  • the double-acting control valve 2025 opens from its first seat 1 against the fuel pressure p but from its second seat 2 with the fuel pressure p.
  • the fuel pressure p is changing over the time in dependence of the operating point of the system.
  • this asymmetry increases in accordance with a raise of the fuel pressure p.
  • large forces and corresponding large medium voltages V M across the piezoelectric actuator are required in order to move the double-acting control valve 2025 out of its first seat 1.
  • the inventive modification of the predefined control scheme helps to reduce the energy consumption of the system. Moreover, the times necessary for charging and discharging the piezoelectric element are reduced. Hence, the ability of the system to quickly afterwards charge another piezoelectric element for another double-acting control valve (not shown) within the system in order to partly drive two (or more) cylinders of the engine in parallel is increased.
  • the reason for a corresponding modification of the control scheme can be a temperature of the system which is below a predefined threshold. This is because the lifting ability of piezoelectric actuators is reduced for low temperatures (for example temperatures which are significantly below 0° C). Hence, it is difficult to properly expand piezoelectric elements to the length required for having the double-acting control valve 2025 in its second seat 2 and for this reason it might be better to switch the double-acting control valve between its first seat 1 and its open position M only. Corresponding situations particularly occur when a car engine is started when the environmental temperature is low. Other reasons for such a control scheme include: 1) the system not being fully synchronized, and 2) the time gap between two injection events, e.g., pre-injection and main injection exceeding a predefined threshold.
  • each graph (1), (2) and (3) quantities are depicted as functions of the time during the same time slot.
  • the base axis of each graph (1), (2) and (3) is a time axis t and the time axes t of the three graphs (1), (2) and (3) are equal one to another.
  • the remaining axis is a amount-of-injection axis I and injections are depicted.
  • the remaining axes are a voltage axes and voltages applied to the piezoelectric actuators are depicted.
  • an exemplary injection profile is depicted, which comprises one injection starting at a first time t 1 and terminated at a second time t 2 .
  • the injection is indicated by means of an injection amount I M which corresponds to the injection occurring while the double-acting control valve 2025 is in its open position M and which, for simplicity, is depicted as constant during the starting time and the termination time.
  • I M which corresponds to the injection occurring while the double-acting control valve 2025 is in its open position M and which, for simplicity, is depicted as constant during the starting time and the termination time.
  • any other injection profile as well as any occurring function of the injection amount I over the time can be used without any effect to the invention.
  • a predefined control scheme for the double-acting control valve 2025 is depicted, which is eligible to execute the above described injection profile.
  • the low voltage V 1 is applied to the piezoelectric element and hence the double-acting control valve 2025 is in its first seat 1.
  • a medium voltage V M is applied to the piezoelectric element and hence the double-acting control valve 2025 is moved into its open position M.
  • the low voltage V 1 is applied to the piezoelectric element and hence is returned into its first seat 1.
  • the predefined control scheme is modified as follows: the double-acting control valve 2025 is moved from its first seat 1 into its second seat 2 at a time t 0 which is in advance to the first time t 1 and hence the high voltage V 2 is applied to the piezoelectric element which initially was on the low voltage V 1 . However, since this happens immediately and with no or no substantial time in which the voltage remains on the level of the medium voltage V M , no (or basically no) injection occurs while doing so. Then, the injection is executed by means of reducing the high voltage V 2 to the medium voltage V M at the first time t 1 and therefore moving the double-acting control valve 2025 into its open position M.
  • Fig. 3 Another reason for the profile depicted in Fig. 3 may be when, in contrast to the usual profile, a main injection with no pre-injection is to be performed. This may be desirable in certain situations. In such a case, in order to leave unchanged conditions for the main injection, it may also be desirable to realize a profile as shown in Fig. 3.
  • each graph (1), (2) and (3) quantities are depicted as functions of the time during the same time slot.
  • the base axis of each graph (1), (2) and (3) is a time axis t and the time axes t of the three graphs (1), (2) and (3) are equal one to another.
  • the remaining axis is a amount-of-injection axis I and injections are depicted.
  • the remaining axes are a voltage axes and voltages applied to the piezoelectric actuators are depicted.
  • an exemplary injection profile is depicted, which comprises one injection starting at a first time t 1 and terminated at a second time t 2 .
  • the injection is indicated by means of an injection amount I M which corresponds to the injection occurring while the double-acting control valve 2025 is in its open position M and which, for simplicity, is depicted as constant during the starting time and the termination time.
  • I M which corresponds to the injection occurring while the double-acting control valve 2025 is in its open position M and which, for simplicity, is depicted as constant during the starting time and the termination time.
  • any other injection profile as well as any occurring function of the injection amount I over the time can be used without any effect to the invention.
  • a predefined control scheme for the double-acting control valve 2025 is depicted, which is eligible to execute the above described injection profile.
  • the high voltage V 2 is applied to the piezoelectric element and hence the double-acting control valve 2025 is in its second seat 2.
  • a medium voltage V M is applied to the piezoelectric element and hence the double-acting control valve 2025 is moved into its open position M.
  • the high voltage V 2 is applied to the piezoelectric element and hence is returned into its second seat 2.
  • the predefined control scheme is modified as follows: the double-acting control valve 2025 is moved from its second seat 2 into its 1 at a time t 0 which is in advance to the first time t 1 and hence the low voltage V 1 is applied to the piezoelectric element which initially was on the high voltage V 2 . However, since this happens immediately and with no or no substantial time in which the voltage remains on the level of the medium voltage V M , no (or basically no) injection occurs while doing so. Then, the injection is executed by means of increasing the low voltage V 1 to the medium voltage V M at the first time t 1 and therefore moving the double-acting control valve 2025 into its open position M. Finally, the double-acting control valve 2025 is returned into its first seat 1 at the second time t 2 while applying the low voltage V 1 to the piezoelectric element.
  • V B the voltage across a buffer capacitor in the charging circuit for the piezoelectric element used to actuate the double-acting control valve may be monitored. See the description above regarding the piezoelectric element control system with reference to Figs. 6 and 7a to d.
  • Fig. 4 shows a block diagram of an exemplary embodiment of a control system in which the invention is implemented.
  • first determination components 100 for the determination and monitoring of the system temperature, particularly for the determination of the temperature occurring at piezoelectric elements 140, 141 and 142.
  • a second determination component 105 provided for indicating the status of synchronicity St sync of the system.
  • a third determination component 110 is provided for determination and monitoring of the fuel pressure occurring in the fuel injection system.
  • fourth determination component 135 for monitoring buffer capacitor voltage V B
  • a fifth determination component 115 for monitoring the time gap between two injections ⁇ T
  • a sixth determination component 125 for monitoring the kind of injections to be realized at the actual operating point of the fuel injection system.
  • St inj describes this actual status of injections. All determination components 100, 105,110, 115, 125 and 135 are connected to a control unit 120 which may control piezoelectric elements according to a predefined control scheme as well modify the control scheme in response to values of the determination components, either alone or in combination, mentioned above.
  • the control scheme may be modified, for example, if: 1) the status of synchronicity St sync indicates that the system is not finally synchronized; 2) the status of injections (St inj ) indicates that no pre-injection is to be performed; and/or 3) the time gap between injections ( ⁇ T) exceeds a predefined value ( ⁇ T MAX ) and/or values of any of the other determination components mentioned above exceeding a threshold value.
  • the control unit 120 immediately controls an activation IC 130 which again activates the piezoelectric elements 140, 141 and 142.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Fuel-Injection Apparatus (AREA)

Claims (23)

  1. Steuerverfahren für ein Mehrstellungsventil (Fig. 5) innerhalb eines Kraftstoffeinspritzsystems, bei dem das Mehrstellungsventil mindestens zwei Alternativen zum Bewegen des Mehrstellungsventils aus einer geschlossenen Position in eine offene Position und/oder aus einer offenen Position in eine geschlossene Position zuläßt, dadurch gekennzeichnet, daß
    a) das Mehrstellungsventil durch eine Steuereinheit (Fig. 4) gemäß einem vordefinierten Steuerplan gesteuert wird;
    b) mindestens eine Temperatur (T), die an einem piezoelektrischen Element zum Antreiben des Mehrstellungsventils auftritt, eine Spannung (VB) an einem Pufferkondensator zum Laden des piezoelektrischen Elements oder ein Zustand des Gleichlaufs (Stsync) im Verhältnis zu einem Nockenwellen- und einem Kurbelwellensignal überwacht wird; und
    c) der vordefinierte Steuerplan, und damit die Steuerung des Mehrstellungsventils, modifiziert wird, falls mindestens die Temperatur (T), die am piezoelektrischen Element auftritt, die Spannung (VB) am Pufferkondensator oder der Zustand des Gleichlaufs (Stsync) vordefinierten Bedingungen entspricht.
  2. Steuerverfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Mehrstellungssteuerventil (10) ein Doppelstellungssteuerventil ist, das einen ersten Sitz (1), der einer ersten geschlossenen Position entspricht, einen zweiten Sitz (2), der einer zweiten geschlossenen Position entspricht, sowie eine offene Position (M) hat.
  3. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) das Mehrstellungssteuerventil (10) mittels eines piezoelektrischen Elements (140, 141, 142) betätigt wird;
    b) der erste Sitz (1) einer an das piezoelektrische Element (140, 141, 142) angelegten ersten Spannung (V1) entspricht;
    c) der zweite Sitz (2) einer an das piezoelektrische Element (140, 141, 142) angelegten zweiten Spannung (V2) entspricht, die größer als die erste Spannung (V1) ist; und
    d) die offene Position (M) einer an das piezoelektrische Element (140, 141, 142) angelegten mittleren Spannung (VM) entspricht, die zwischen der ersten und der zweiten Spannung (V2, V1) liegt.
  4. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) der Kraftstoffdruck (p) überwacht wird; und
    b) der vordefinierte Steuerplan modifiziert wird, falls der überwachte Druck (p) einen vordefinierten Grenzwert (pmax) überschreitet.
  5. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) die Zahl und Art von Einspritzungen (Stinj) überwacht werden; und
    b) der vordefinierte Steuerplan modifiziert wird, falls keine Voreinspritzungen durchzuführen sind.
  6. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan eine Einspritzung mittels Bewegen des Mehrstellungssteuerventils (10) aus dem ersten Sitz (1) in die offene Position (M) durchgeführt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) aus dem zweiten Sitz (2) in die offene Position (M) bewegt wird, falls der überwachte Druck (p) den vordefinierten Grenzwert (pmax) überschreitet.
  7. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan eine Einspritzung mittels Bewegen des Mehrstellungssteuerventils (10) aus dem ersten Sitz (1) in die offene Position (M) durchgeführt wird;
    b) das Mehrstellungssteuerventil (10) in seinem ersten Sitz (1) plaziert ist; und
    c) das Mehrstellungssteuerventil (10), um die Einspritzung durchzuführen, zuerst aus dem ersten Sitz (1) in den zweiten Sitz (2) bewegt wird, bevor es in die offene Position (M) bewegt wird, falls der überwachte Druck (p) einen vordefinierten Grenzwert (pmax) überschreitet.
  8. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan zwei Voreinspritzungen durchgeführt werden, bevor eine Haupteinspritzung stattfindet, und das Mehrstellungssteuerventil (10) zwischen den beiden Voreinspritzungen in den ersten Sitz (1) bewegt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) zwischen den beiden Voreinspritzungen in den zweiten Sitz (2) bewegt wird.
  9. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) die Systemtemperatur (T) überwacht wird; und
    b) der vordefinierte Steuerplan modifiziert wird, falls die überwachte Temperatur (T) unter einem vordefinierten Grenzwert (Tmin) liegt.
  10. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) der Zeitspalt zwischen Einspritzungen (ΔT) überwacht wird; und
    b) der vordefinierte Steuerplan modifiziert wird, falls der Zeitspalt zwischen Einspritzungen (ΔT) einen vordefinierten Wert überschreitet.
  11. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) der Zustand des Gleichlaufs des Systems im Verhältnis zum Nockenwellen- und Kurbelwellensignal (Stsync) überwacht wird; und
    b) der vordefinierte Steuerplan modifiziert wird, falls das System nicht in endgültigem Gleichlauf ist.
  12. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan das Mehrstellungssteuerventil (10) nach einer durchgeführten Einspritzung in den zweiten Sitz (2) bewegt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) in den ersten Sitz (1) bewegt wird, falls die überwachte Temperatur (T) unter einem vordefinierten Grenzwert (Tmin) liegt und/oder der Zeitspalt (ΔT) zwischen diesen Einspritzungen einen vordefinierten Wert (ΔTMAX) überschreitet und/oder das System nicht in endgültigem Gleichlauf ist.
  13. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan eine Einspritzung mittels Bewegen des Mehrstellungssteuerventils (10) aus dem zweiten Sitz (2) in die offene Position (M) durchgeführt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) aus dem ersten Sitz (1) in die offene Position (M) bewegt wird, falls die überwachte Temperatur (T) unter einem vordefinierten Grenzwert (Tmin) liegt und/oder der Zeitspalt (ΔT) zwischen diesen Einspritzungen einen vordefinierten Wert (ΔTMAX) überschreitet und/oder das System nicht in endgültigem Gleichlauf ist.
  14. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan eine Voreinspritzung vor einer Haupteinspritzung durchgeführt und das Mehrstellungssteuerventil (10) zwischen der Voreinspritzung und der Haupteinspritzung in den zweiten Sitz (2) bewegt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) zwischen der Voreinspritzung und der Haupteinspritzung in den ersten Sitz (1) bewegt wird, falls die überwachte Temperatur (T) unter dem vordefinierten Grenzwert (Tmin) liegt und/oder der Zeitspalt (ΔT) zwischen diesen Einspritzungen einen vordefinierten Wert (ΔTMAX) überschreitet und/oder das System nicht in endgültigem Gleichlauf ist.
  15. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) sowohl der Kraftstoffdruck (p) als auch die Systemtemperatur (T) überwacht werden; und
    b) das Mehrstellungsventil (10), falls der Druck (p) den vordefinierten Grenzwert (pmax) überschreitet und gleichzeitig die Temperatur (T) unter dem vordefinierten Grenzwert (Tmin) liegt, so gesteuert wird, als ob der Druck (p) nicht den vordefinierten Grenzwert (pmax) überschreiten würde.
  16. Steuerverfahren nach einem der Ansprüche 1, 2 und 4 bis einschließlich 12, dadurch gekennzeichnet, daß
    a) das Mehrstellungssteuerventil (10) mittels eines piezoelektrischen Elements betätigt wird;
    b) die Pufferspannung (VB) im Ladestromkreis des piezoelektrischen Elements überwacht wird; und
    c) der vordefinierte Steuerplan modifiziert wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  17. Steuerverfahren nach einem der Ansprüche 1, 2 und 4 bis einschließlich 12, dadurch gekennzeichnet, daß
    a) das Mehrstellungssteuerventil (10) mittels eines piezoelektrischen Elements betätigt wird;
    b) gemäß dem vordefinierten Steuerplan das Mehrstellungssteuerventil (10) nach einer durchgeführten Einspritzung in den zweiten Sitz (2) bewegt wird; und
    c) statt dessen das Mehrstellungssteuerventil (10) in den ersten Sitz (1) bewegt wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  18. Steuerverfahren nach einem der Ansprüche 1, 2 und 4 bis einschließlich 12, dadurch gekennzeichnet, daß
    a) das Mehrstellungssteuerventil (10) mittels eines piezoelektrischen Elements betätigt wird;
    b) gemäß dem vordefinierten Steuerplan eine Einspritzung mittels Bewegen des Mehrstellungssteuerventils (10) aus dem zweiten Sitz (2) in die offene Position (M) durchgeführt wird; und
    c) statt dessen das Mehrstellungssteuerventil (10) aus dem ersten Sitz (1) in die offene Position (M) bewegt wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  19. Steuerverfahren nach Anspruch 3, dadurch gekennzeichnet, daß
    a) die Pufferspannung (VB) im Ladestromkreis des piezoelektrischen Elements überwacht wird; und
    b) der vordefinierte Steuerplan modifiziert wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  20. Steuerverfahren nach Anspruch 3, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan das Mehrstellungssteuerventil (10) nach einer durchgeführten Einspritzung in den zweiten Sitz (2) bewegt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) in den ersten Sitz (1) bewegt wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  21. Steuerverfahren nach Anspruch 3, dadurch gekennzeichnet, daß
    a) gemäß dem vordefinierten Steuerplan eine Einspritzung mittels Bewegen des Mehrstellungssteuerventils (10) aus dem zweiten Sitz (2) in die offene Position (M) durchgeführt wird; und
    b) statt dessen das Mehrstellungssteuerventil (10) aus dem ersten Sitz (1) in die offene Position (M) bewegt wird, falls die überwachte Pufferspannung (VB) unter einem vordefinierten Grenzwert (VB min) liegt.
  22. Steuerverfahren nach einem der vorstehend aufgeführten Ansprüche, dadurch gekennzeichnet, daß
    a) die überwachten Systemparameter (p, T, VB, Stsync, ΔT, Stinj) und/oder eine beliebige Kombination von zwei oder mehr der überwachten Systemparameter nach ihrer Priorität eingestuft sind; und
    b) der vordefinierte Steuerplan, und damit die Steuerung des Mehrstellungsventils, auf der Basis des überwachten Systemsparameters (p, T, VB, Stsync, ΔT, Stinj) oder einer Kombination der überwachten Systemparameter mit der höchsten Prioritätseinstufung modifiziert wird.
  23. Steuervorrichtung für ein Mehrstellungsventil (Fig. 5) innerhalb eines Kraftstoffeinspritzsystems, wobei das Mehrstellungsventil mindestens zwei Alternativen zum Bewegen des Mehrstellungsventils aus einer geschlossenen Position in eine offene Position und/oder aus einer offenen Position in eine geschlossene Position zuläßt, dadurch gekennzeichnet, daß
    a) eine Steuereinheit (120) vorgesehen ist, um das Mehrstellungsventil gemäß einem vordefinierten Steuerplan zu steuern;
    b) Überwachungsmittel (100, 110) vorgesehen sind, um mindestens entweder eine Temperatur (T), die an einem piezoelektrischen Element zum Antreiben des Mehrstellungsventils auftritt, eine Spannung (VB) am Pufferkondensator zum Laden des piezoelektrischen Elements oder einen Zustand des Gleichlaufs (Stsync) im Verhältnis zu einem Nockenwellen- und einem Kurbelwellensignal zu überwachen; und
    c) Modifizierungsmittel (120) vorgesehen sind, um den vordefinierten Steuerplan, und damit die Steuerung des Mehrstellungsventils, zu modifizieren, falls mindestens entweder die Temperatur (T), die am piezoelektrischen Element auftritt, die Spannung (VB) am Pufferkondensator oder der Zustand des Gleichlaufs (Stsync) vordefinierten Bedingungen entspricht.
EP20000106987 2000-04-01 2000-04-01 Steuerverfahren und Vorrichtung zur Mehrstellungventilbetätigung in einem Kraftstoffeinspritzsystem Expired - Lifetime EP1138920B1 (de)

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US5924403A (en) * 1997-06-06 1999-07-20 Detroit Diesel Corporation Method for enhanced split injection in internal combustion engines
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