EP1423593A1 - Method for controlling a piezo-actuated fuel-injection valve - Google Patents
Method for controlling a piezo-actuated fuel-injection valveInfo
- Publication number
- EP1423593A1 EP1423593A1 EP02760150A EP02760150A EP1423593A1 EP 1423593 A1 EP1423593 A1 EP 1423593A1 EP 02760150 A EP02760150 A EP 02760150A EP 02760150 A EP02760150 A EP 02760150A EP 1423593 A1 EP1423593 A1 EP 1423593A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- time
- injection
- actuator
- piezo
- servo valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000002347 injection Methods 0.000 title claims abstract description 54
- 239000007924 injection Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims description 27
- 239000000446 fuel Substances 0.000 claims description 22
- 238000010586 diagram Methods 0.000 claims description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
Classifications
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- 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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1413—Controller structures or design
- F02D2041/143—Controller structures or design the control loop including a non-linear model or compensator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
-
- 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
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
- F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
- F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
- F02M45/08—Injectors peculiar thereto
-
- 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
- F02M51/00—Fuel-injection apparatus characterised by being operated electrically
- F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
- F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
Definitions
- the invention relates to a method for controlling a piezo-operated fuel pressure valve according to the features of claim 1.
- the fuel injection process in diesel engines is usually carried out in several sections, with one or more pre-injections or post-injections in which the amount of fuel injected is small compared to the main injection amount in order to achieve a smoother combustion process for each main injection.
- Fast-switching valves are required for precise metering of the fuel quantities, in particular the small quantities, and for optimizing the injection times, for which purpose piezoelectric injection valves are increasingly being used.
- the piezo actuator actuates a hydraulic servo valve, which then moves the main valve.
- the control of the piezo actuator is carried out by means of control electronics in such a way that the desired amount of fuel is injected.
- the electrical control signals for the injection of small quantities of fuel are designed with regard to the control duration and amplitude so that a safe injection takes place. Because of the si Safety reservations regarding pressure fluctuations in the fuel supply line, parameter tolerances of the system and the wide operating temperature range are associated with this, particularly in the case of pre-injections and post-injections, of an overdose of fuel. For this purpose, the piezo deflection was previously concluded from the charge or energy fed into the piezo actuator.
- Main or post-injections take place or not, and which enables a more precise determination of the amount of each fuel pre-injection, main or post-injection.
- the method according to the invention is based on a detection and evaluation of the changes in length or forces of the piezo actuator, which are effective on the piezo actuator during a control process and are determined from the electrical signals (of the current supplied to the piezo actuator and the voltage building up on it), with the aid of a non-linear actuator model and an adaptive method for evaluating the length changes on the piezo actuator or the forces occurring on it.
- the actuator model contains the non-linear relationships between charge or voltage and mechanical deflection, and operating point-dependent parameters.
- the actuator model also takes into account the dielectric hysteresis of the piezo actuator. This actuator model allows the inference from the electrical to the mechanical variables and the simulation of the piezo actuator in the area of pulse-shaped deflection.
- FIG. 1 shows the change in length s of a piezo actuator during a control process
- FIG. 2 shows the force F acting on a piezo actuator when the valve is opened, with or without fuel injection, and the variables derived therefrom.
- FIG. 1 shows the basic course of the piezo stroke, i.e. the change in length s of a piezo actuator over time t during a control process of a fuel injection valve. This change in length s is calculated using the measured data of the current supplied to the piezo actuator and the voltage then building up thereon with the aid of an actuator model which simulates the properties of a piezo actuator.
- the curve si shows the basic course of the start of the length change s (expansion) of a piezo actuator with a correct injection process.
- the curve rises from the beginning 0 of the Control on, has a kink at a time t A and then rises faster until it reaches a maximum and then drops again.
- the kink is explained by the fact that the piezo actuator covers an empty travel before it asserts itself against the force of the rail pressure in the servo valve and opens the servo valve.
- the dashed curve SQ shows the basic course of the beginning of the change in length (expansion) of a piezo actuator in the event of an incorrect injection process.
- the curve rises gently without showing a kink, reaches a maximum and then drops again, i.e. the free travel is not measured completely.
- the maximum of the curve of the linear expansion of a piezo actuator depends, among other things. on the energy that is fed to the piezo actuator: the greater the amount of energy, the greater the length s.
- the opening of the servo valve therefore begins approximately at the time t A of the curve i i. This opening of the servo valve is imperative for a subsequent injection. The actual injection takes place with a considerable delay, because when the servo valve is opened, the pressure in the valve chamber slowly decreases and only then does the actual injection valve open. The presence of the "kink" in the path is an indication that there is sufficient energy in the piezo so that the servo valve opens.
- the method according to the invention for determining this opening time t A of the servo valve is explained below.
- the time t A varies, for example, with the energy E supplied to the piezo actuator and with the counteracting energy Fuel rail pressure p and the actuator temperature T etc. It is therefore known empirically.
- a first straight line - tangent T] _ - is determined by the length changes at times ti and t 2
- a second straight line - tangent Ti ⁇ - is determined by the length changes at times t 3 and t st.
- Time t A which is evaluated as the time of opening of the servo valve. For a correct injection, however, only such a course of the length change s is evaluated, in which the tangent T] _ ⁇ has a definable steeper angle with respect to the abscissa than the tangent Ti. Otherwise an incorrect injection is assumed (To - T 0 ⁇ ).
- the positions of the time t A may shift in the long term. It is therefore provided that the times t1 to t4 stored in the characteristic diagrams, which determine the time windows W1 and W2, are also stored, ie adapted, as a function of the time t A determined in the previous previous injection process. The injection duration is only determined if a correct injection with a defined injection start was previously determined.
- the fuel injection duration D is determined by means of the force F acting on the piezo actuator. Like the length change s, this force F is determined from the electrical signals (from the current supplied to the piezo actuator and the voltage building up on it) with the aid of the non-linear actuator model already mentioned.
- FIG. 2a shows the basic course of the force Fi acting on a piezo actuator in a fuel injection process or in the case of incorrect injection (F 0 , dashed lines).
- the force F increases from the start of the control process and reaches its maximum at about time t A , then changes to an approximately horizontal course (it decreases slowly in the event of a faulty spray) and makes a jump ms negative and then one when switched off Jump into the positive before it goes back to zero.
- the first time derivative dFi / dt of the force F is used to determine the injection duration D.
- the course of the first derivative dF ⁇ / dt of the force F (FIG. 2a) is shown schematically in FIG. 2b.
- this derivative dFi / dt reaches its maximum where the force F ⁇ _ rises steeply, then becomes negative when the force drops and reaches a
- a tolerance band is set for the value of the first derivative in the area of the above-mentioned plateau, with an upper value gl (for dF / dt positive) and a lower value g2 (for dF / dt negative). Both values are shown in broken lines in FIG. 2b. These values, like the windows W1 and W2 in FIG. 1, can also be shown via characteristic maps as a function of the energy supplied, rail pressure, etc. can be varied.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fuel-Injection Apparatus (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
Description
Beschreibungdescription
Verfahren zum Ansteuern eines piezobetriebenen Kraftstoff- EinspritzventilsMethod for driving a piezo-operated fuel injection valve
Die Erfindung betrifft ein Verfahren zum Ansteuern eines piezobetriebenen Kraftstoff-Emspntzventils gemäß den Merkmalen von Anspruch 1.The invention relates to a method for controlling a piezo-operated fuel pressure valve according to the features of claim 1.
Der Kraftstoff-Emspπtzvorgang in Dieselmotoren wird üblicherweise m mehreren Abschnitten durchgeführt, wobei zur Er- zielung eines sanfteren Verbrennungsverlaufs jeder Hauptem- spritzung eine oder mehrere Vor- oder Nacheinspritzungen zugeordnet sind, bei denen die eingespritzte Kraftstoffmenge klein gegenüber der Haupteinspritzmenge ist.The fuel injection process in diesel engines is usually carried out in several sections, with one or more pre-injections or post-injections in which the amount of fuel injected is small compared to the main injection amount in order to achieve a smoother combustion process for each main injection.
Für eine präzise Dosierung der Kraftstoffmengen, insbesondere der Kleinmengen und zur Optimierung der Emspπtz-Zeitpunkte, sind schnell schaltende Ventile erforderlich, wozu zunehmend piezobetπebene Emspπtzventile eingesetzt werden.Fast-switching valves are required for precise metering of the fuel quantities, in particular the small quantities, and for optimizing the injection times, for which purpose piezoelectric injection valves are increasingly being used.
Wegen der geringen maximalen Langenanderung der eingesetzten Piezoelemente (Stacks) betätigt der Piezoaktor ein hydraulisches Servoventil, welches dann das Hauptventil bewegt. Mit- tels einer Ansteuerelektronik wird die elektrische Ansteue- rung des Piezoaktors so vorgenommen, daß die gewünschte Kraftstoffmenge eingespritzt wird.Due to the small maximum length change of the used piezo elements (stacks), the piezo actuator actuates a hydraulic servo valve, which then moves the main valve. The control of the piezo actuator is carried out by means of control electronics in such a way that the desired amount of fuel is injected.
Da es nicht möglich ist, Kraftstoffmengen oder mechanische Bewegungen im Emspritzventil zu erfassen, werden die elektrischen Steuersignale bei der Einspritzung kleiner Kraftstoffmengen hinsichtlich Ansteuerdauer und Amplitude so ausgelegt, daß ein sicheres Einspritzen erfolgt. Wegen der Si- cherheitsvorbehalte gegenüber Druckschwankungen in der KraftstoffZuleitung, Parametertoleranzen des Systems und des weiten Betriebstemperaturbereichs ist damit, insbesondere bei Vor- und Nacheinspritzungen, eine Kraftstoffmengen- Uberdosierung verbunden. Dazu wurde bisher aus der in den Piezoaktor eingespeisten Ladung oder Energie auf die Piezo- auslenkung geschlossen.Since it is not possible to detect fuel quantities or mechanical movements in the injection valve, the electrical control signals for the injection of small quantities of fuel are designed with regard to the control duration and amplitude so that a safe injection takes place. Because of the si Safety reservations regarding pressure fluctuations in the fuel supply line, parameter tolerances of the system and the wide operating temperature range are associated with this, particularly in the case of pre-injections and post-injections, of an overdose of fuel. For this purpose, the piezo deflection was previously concluded from the charge or energy fed into the piezo actuator.
Aus DE 196 44 521 AI ist ein Verfahren zur Ansteuerung eines kapazitiven Stellgliedes eines Kraftstoffeinspritzventils bekannt, welchem zur Erzielung eines konstanten Hubs eine diesem Hub zugeordnete Energiemenge zugeführt wird.From DE 196 44 521 AI a method for controlling a capacitive actuator of a fuel injector is known, which is supplied with an amount of energy associated with this stroke to achieve a constant stroke.
Es ist Aufgabe der Erfindung, ein Verfahren anzugeben, mit dessen Hilfe überwacht werden kann, ob Kraftstoff-Vor-,It is an object of the invention to provide a method by means of which it can be monitored whether fuel pre-
Haupt- oder Nach-Emspritzungen stattfinden oder nicht, und welches eine genauere Festlegung der Menge jeder Kraftstoff- Vor-, Haupt- oder Nach-Emspritzung ermöglicht.Main or post-injections take place or not, and which enables a more precise determination of the amount of each fuel pre-injection, main or post-injection.
Diese Aufgabe wird erfindungsgemaß durch die Merkmale des Anspruchs 1 gelost.This object is achieved according to the invention by the features of claim 1.
Das erfmdungsgemaße Verfahren beruht auf einer Erfassung und Auswertung der am Piezoaktor bei einem Ansteuervorgang wir- kenden, aus den elektrischen Signalen (des dem Piezoaktor zugefuhrten Stromes und der sich an ihm aufbauenden Spannung) ermittelten Langenanderungen oder Kräfte des Piezoaktors, unter Zuhilfenahme eines nichtlmearen Aktormodells und eines adaptiven Verfahrens zur Bewertung der Langenanderungen am Piezoaktor bzw. der an ihm auftretenden Kräfte.The method according to the invention is based on a detection and evaluation of the changes in length or forces of the piezo actuator, which are effective on the piezo actuator during a control process and are determined from the electrical signals (of the current supplied to the piezo actuator and the voltage building up on it), with the aid of a non-linear actuator model and an adaptive method for evaluating the length changes on the piezo actuator or the forces occurring on it.
Das Aktormodell beinhaltet die nichtlinearen Zusammenhange zwischen Ladung bzw. Spannung und mechanischer Auslenkung, sowie Arbeitspunkt-abhangigen Parametern. Ferner berücksichtigt das Aktormodell die dielektrische Hysterese des Piezoaktors. Damit erlaubt dieses Aktormodell den Ruckschluß von den elektrischen auf die mechanischen Großen und die Simulation des Piezoaktors im Bereich pulsformiger Auslenkung.The actuator model contains the non-linear relationships between charge or voltage and mechanical deflection, and operating point-dependent parameters. The actuator model also takes into account the dielectric hysteresis of the piezo actuator. This actuator model allows the inference from the electrical to the mechanical variables and the simulation of the piezo actuator in the area of pulse-shaped deflection.
Damit ist es möglich, eine fehlerhafte oder korrekte Einspritzfunktion sowie die Einspritzdauer (-menge) des Einspritzventils sicher festzustellen und die Ansteuersignale a- daptiv so zu gestalten, daß die gewünschten minimalen Kraftstoffeinspritzungen ohne Uberdosierung erfolgen.This makes it possible to reliably determine a faulty or correct injection function and the injection duration (quantity) of the injection valve and to adaptively design the control signals so that the desired minimum fuel injections take place without overdosing.
Nachstehend wird ein Ausfuhrungsbeispiel nach der Erfindung anhand einer schematischen Zeichnung naher erläutert.An exemplary embodiment according to the invention is explained in more detail below with the aid of a schematic drawing.
In der Zeichnung zeigen:The drawing shows:
Figur 1 die Langenanderung s eines Piezoaktors bei einem Ansteuervorgang, und Figur 2 die an einem Piezoaktor bei einem Offnungsvorgang des Ventils mit oder ohne Kraftstoffeinspritzung wirkende Kraft F und die daraus abgeleiteten Großen.1 shows the change in length s of a piezo actuator during a control process, and FIG. 2 shows the force F acting on a piezo actuator when the valve is opened, with or without fuel injection, and the variables derived therefrom.
Figur 1 zeigt den prinzipiellen Verlauf des Piezohubs, d.h., der Langenanderung s eines Piezoaktors über der Zeit t bei einem Ansteuervorgang eines Kraftstoffemspπtzventils . Diese Langenanderung s wird mittels der gemessenen Daten des dem Piezoaktor zugefuhrten Stromes und der sich daraufhin an ihm aufbauenden Spannung mit Hilfe eines Aktormodells, welches die Eigenschaften eines Piezoaktors nachbildet, errechnet.FIG. 1 shows the basic course of the piezo stroke, i.e. the change in length s of a piezo actuator over time t during a control process of a fuel injection valve. This change in length s is calculated using the measured data of the current supplied to the piezo actuator and the voltage then building up thereon with the aid of an actuator model which simulates the properties of a piezo actuator.
Die Kurve si zeigt den prinzipiellen Verlauf des Beginns der Langenanderung s (Ausdehnung) eines Piezoaktors bei einem korrekten Einspritzvorgang. Die Kurve steigt vom Beginn 0 der Ansteuerung an, weist zu einem Zeitpunkt tA einen Knick auf und steigt danach schneller an, bis sie ein Maximum erreicht und dann wieder abfällt. Der Knick erklärt sich daraus, dass der Piezoaktor einen Leerweg zurücklegt, bevor er sich gegen die Kraft des Raildrucks im Servoventil durchsetzt und das Servoventil öffnet.The curve si shows the basic course of the start of the length change s (expansion) of a piezo actuator with a correct injection process. The curve rises from the beginning 0 of the Control on, has a kink at a time t A and then rises faster until it reaches a maximum and then drops again. The kink is explained by the fact that the piezo actuator covers an empty travel before it asserts itself against the force of the rail pressure in the servo valve and opens the servo valve.
Die gestrichelt dargestellte Kurve SQ zeigt zum Unterschied von der Kurve si den prinzipiellen Verlauf des Beginns der Längenänderung (Ausdehnung) eines Piezoaktors bei einem nicht korrekten Einspritzvorgang. Die Kurve steigt flach an, ohne einen Knick aufzuweisen, erreicht ein Maximum und fällt dann wieder ab, d.h., der Leerweg wird nicht zur Gänze durchmessen. Das Maximum der Kurve der Längenausdehnung eines Piezo- aktors hängt u.a. von der Energie ab, die dem Piezoaktor zugeführt wird: je größer der Energiebetrag, desto größer die Längenausdehnung s .In contrast to the curve si, the dashed curve SQ shows the basic course of the beginning of the change in length (expansion) of a piezo actuator in the event of an incorrect injection process. The curve rises gently without showing a kink, reaches a maximum and then drops again, i.e. the free travel is not measured completely. The maximum of the curve of the linear expansion of a piezo actuator depends, among other things. on the energy that is fed to the piezo actuator: the greater the amount of energy, the greater the length s.
Der Beginn der Öffnung des Servoventils liegt also etwa im Zeitpunkt tA der Kurve ≤i. Diese Öffnung des Servoventils ist zwingende Voraussetzung für eine anschließende Einspritzung. Die eigentliche Einspritzung erfolgt deutlich verzögert, da mit dem Öffnen des Servoventils der Druck in der Ventilkammer langsam abgebaut wird und dann erst das eigentliche Ein- spritzventil öffnet. Das Vorhandensein des „Knicks" im Wegverlauf ist ein Indiz dafür, dass genügend Energie im Piezo vorhanden ist, damit das Servoventil öffnet.The opening of the servo valve therefore begins approximately at the time t A of the curve i i. This opening of the servo valve is imperative for a subsequent injection. The actual injection takes place with a considerable delay, because when the servo valve is opened, the pressure in the valve chamber slowly decreases and only then does the actual injection valve open. The presence of the "kink" in the path is an indication that there is sufficient energy in the piezo so that the servo valve opens.
Das erfindungsgemäße Verfahren zur Ermittlung dieses Öff- nungszeitpunkts tA des Servoventils wird nachstehend erklärt. Der Zeitpunkt tA variiert beispielsweise mit der dem Piezoaktor zugeführten Energie E und dem ihm entgegenwirkenden Kraftstoff-Raildruck p sowie der Aktortemperatur T etc.. Er ist also empirisch bekannt.The method according to the invention for determining this opening time t A of the servo valve is explained below. The time t A varies, for example, with the energy E supplied to the piezo actuator and with the counteracting energy Fuel rail pressure p and the actuator temperature T etc. It is therefore known empirically.
Über Kennfelder, die diesen Zusammenhang berücksichtigen, werden ein erstes Zeitfenster Wl (festgelegt durch Zeitpunkte ti und t2) kurz vor dem Zeitpunkt tA [tA=f(E, p, T ...)] und ein zweites Zeitfenster W2 (festgelegt durch Zeitpunkte t3 und t„) kurz nach diesem Zeitpunkt tA, definiert.A first time window W1 (determined by times ti and t 2 ) shortly before the time t A [t A = f (E, p, T ...)] and a second time window W2 ( defined by times t 3 and t ") shortly after this time t A , defined.
Durch die Langenanderungen zu den Zeitpunkten ti und t2 ist eine erste Gerade - Tangente T]_ - bestimmt, und durch die Langenanderungen zu den Zeitpunkten t3 und t st eine zweite Gerade - Tangente Ti Λ - bestimmt. Diese beiden Tangenten, in Figur 1 fett hervorgehoben, schneiden sich in einem mittels einer einfachen trigonometrischen Rechnung ermittelbarenA first straight line - tangent T] _ - is determined by the length changes at times ti and t 2 , and a second straight line - tangent Ti Λ - is determined by the length changes at times t 3 and t st. These two tangents, highlighted in bold in FIG. 1, intersect in a manner that can be determined using a simple trigonometric calculation
Zeitpunkt tA, der als Zeitpunkt der Öffnung des Servoventils gewertet wird. Für eine korrekte Einspritzung wird jedoch nur ein solcher Verlauf der Langenanderung s gewertet, bei dem die Tangente T]_ λ einen def nierbar steileren Winkel gegenüber der Abszisse aufweist als die Tangente Ti. Andernfalls wird eine Fehleinspntzung angenommen (To - T0 Λ ) .Time t A , which is evaluated as the time of opening of the servo valve. For a correct injection, however, only such a course of the length change s is evaluated, in which the tangent T] _ λ has a definable steeper angle with respect to the abscissa than the tangent Ti. Otherwise an incorrect injection is assumed (To - T 0 Λ ).
Aufgrund von Verschleißerscheinungen kann es langfristig vorkommen, dass sich die Lage des Zeitpunkts tA verschiebt. Des- halb ist vorgesehen, dass die in den Kennfeldern gespeicherten Zeitpunkte tl bis t4, welche die Zeitfenster Wl und W2 bestimmen, auch von dem in dem jeweils vorhergehenden früheren Einspritzvorgang ermittelten Zeitpunkt tA abhangig gespeichert, d.h., adaptiert werden. Eine Ermittlung der Einspritzdauer wird nur dann vorgenommen, wenn zuvor eine korrekte Einspritzung mit definiertem Einspritzbeginn festgestellt wurde.Due to wear and tear, the position of the time t A may shift in the long term. It is therefore provided that the times t1 to t4 stored in the characteristic diagrams, which determine the time windows W1 and W2, are also stored, ie adapted, as a function of the time t A determined in the previous previous injection process. The injection duration is only determined if a correct injection with a defined injection start was previously determined.
Die Kraftstoff-Einspritzdauer D wird mittels der am Piezoaktor wirkenden Kraft F ermittelt. Diese Kraft F wird - wie die Langenanderung s -aus den elektrischen Signalen (aus dem dem Piezoaktor zugefuhrten Strom und der sich an ihm aufbauenden Spannung) unter Zuhilfenahme des bereits erwähnten, nichtli- nearen Aktormodells ermittelt.The fuel injection duration D is determined by means of the force F acting on the piezo actuator. Like the length change s, this force F is determined from the electrical signals (from the current supplied to the piezo actuator and the voltage building up on it) with the aid of the non-linear actuator model already mentioned.
Figur 2a zeigt den prinzipiellen Verlauf der an einem Piezoaktor wirkenden Kraft Fi bei einem Kraftstoffemspπtzvorgang bzw. bei einer Fehleinspritzung (F0, strichliert) .FIG. 2a shows the basic course of the force Fi acting on a piezo actuator in a fuel injection process or in the case of incorrect injection (F 0 , dashed lines).
Die Kraft F steigt vom Beginn des Ansteuervorgangs an und erreicht etwa im Zeitpunkt tA ihr Maximum, geht anschließend in einen etwa horizontalen Verlauf über (bei einer Fehlemsprit- zung nimmt sie langsam ab) und macht beim Abschalten zunächst einen Sprung ms Negative und anschließend einen Sprung ins Positive, bevor sie wieder zu Null wird.The force F increases from the start of the control process and reaches its maximum at about time t A , then changes to an approximately horizontal course (it decreases slowly in the event of a faulty spray) and makes a jump ms negative and then one when switched off Jump into the positive before it goes back to zero.
Zur Ermittlung der Einspritzdauer D wird erfmdungsgemaß die erste zeitliche Ableitung dFi/dt der Kraft F herangezogen. Der Verlauf der ersten Ableitung dFχ/dt der Kraft F (Figur 2a) ist schematisch in Figur 2b dargestellt.According to the invention, the first time derivative dFi / dt of the force F is used to determine the injection duration D. The course of the first derivative dFχ / dt of the force F (FIG. 2a) is shown schematically in FIG. 2b.
Bei einem korrekten Einspritzvorgang erreicht diese Ableitung dFi/dt ihr Maximum da, wo die Kraft Fι_ am steilsten ansteigt, wird dann negativ, wenn die Kraft abfallt und erreicht einIf the injection process is correct, this derivative dFi / dt reaches its maximum where the force Fι_ rises steeply, then becomes negative when the force drops and reaches a
Plateau um den Wert Null da, wo die Kraft Fi horizontal ver- läuft, bevor sie beim Abschalten zunächst negativ und dann positiv und schließlich zu Null wird.Plateau around zero where the force Fi is horizontal runs before it turns negative and then positive and finally zero when switched off.
Bei einer Fehleinspritzung würde die Ableitung dF0/dt (in Fi- gur 2b strichliert) ein geringeres Maximum erreichen und anschließend negativ werden, bevor sie beim Abschalten wieder zu Null würde.In the event of an incorrect injection, the derivative dF 0 / dt (dashed line in FIG. 2b) would reach a lower maximum and then become negative before it would become zero again when it was switched off.
Erfindungsgemäß wird im Bereich des oben genannten Plateaus ein Toleranzband für den Wert der ersten Ableitung gelegt, mit einem oberen Wert gl (für dF/dt positiv) und einem unteren Wert g2 (für dF/dt negativ) . Beide Werte sind in Figur 2b strichliert dargestellt. Auch diese Werte können, wie die Fenster Wl und W2 in Figur 1, über Kennfelder in Abhängigkeit von zugefuhrter Energie, Raildruck u.s.w. variiert werden.According to the invention, a tolerance band is set for the value of the first derivative in the area of the above-mentioned plateau, with an upper value gl (for dF / dt positive) and a lower value g2 (for dF / dt negative). Both values are shown in broken lines in FIG. 2b. These values, like the windows W1 and W2 in FIG. 1, can also be shown via characteristic maps as a function of the energy supplied, rail pressure, etc. can be varied.
Solange sich nun die erste Ableitung dFι_/dt - nach dem Zeitpunkt tA - innerhalb dieses Toleranzbandes befindet, was zwischen den Zeitpunkten ts und tζ in Figur 2b festgestellt wird, wird angenommen, dass die Kraftstoffeinspritzung, die allerdings erst zeitversetzt dazu erfolgt, eine Dauer D (D=tg-t5) aufweist.As long as the first derivative dFι_ / dt - after the point in time t A - is within this tolerance band, which is determined between the points in time ts and tζ in FIG. 2b, it is assumed that the fuel injection, which takes place only after a delay, takes a duration D (D = tg-t 5 ).
Auf die beschriebene Weise kann für jede Ansteuerung eines Piezoaktors für eine Vor-, Haupt- oder Nacheinspritzung festgestellt werden, ob eine korrekte oder eine Fehl-Einspritzung stattfindet, wann die Einspritzung beginnt und wie lange sie dauert . In the manner described, it can be determined for each activation of a piezo actuator for a pre-injection, main injection or post-injection whether correct or incorrect injection takes place, when the injection begins and how long it lasts.
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10143501A DE10143501C1 (en) | 2001-09-05 | 2001-09-05 | Method for controlling a piezo-operated fuel injection valve |
DE10143501 | 2001-09-05 | ||
PCT/DE2002/003226 WO2003023212A1 (en) | 2001-09-05 | 2002-09-02 | Method for controlling a piezo-actuated fuel-injection valve |
Publications (2)
Publication Number | Publication Date |
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EP1423593A1 true EP1423593A1 (en) | 2004-06-02 |
EP1423593B1 EP1423593B1 (en) | 2006-11-02 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP02760150A Expired - Lifetime EP1423593B1 (en) | 2001-09-05 | 2002-09-02 | Method for controlling a piezo-actuated fuel-injection valve |
Country Status (5)
Country | Link |
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US (1) | US7040297B2 (en) |
EP (1) | EP1423593B1 (en) |
JP (1) | JP4047809B2 (en) |
DE (2) | DE10143501C1 (en) |
WO (1) | WO2003023212A1 (en) |
Families Citing this family (22)
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DE10301822B4 (en) * | 2003-01-20 | 2011-04-07 | Robert Bosch Gmbh | Method for determining the linear expansion of a piezoelectric actuator |
DE10345226B4 (en) * | 2003-09-29 | 2006-04-06 | Volkswagen Mechatronic Gmbh & Co. Kg | Method and device for controlling a valve and method and device for controlling a pump-nozzle device with a valve |
DE10349307B3 (en) * | 2003-10-23 | 2005-05-25 | Siemens Ag | Diagnostic procedure for an electromechanical actuator |
DE10357481A1 (en) * | 2003-12-09 | 2005-07-14 | Siemens Ag | Operating method for an actuator of an injection valve |
DE102004020937B4 (en) * | 2004-04-28 | 2010-07-15 | Continental Automotive Gmbh | Method for determining a closing time of a closing element and circuit arrangement |
DE102004023545A1 (en) * | 2004-05-13 | 2005-12-08 | Daimlerchrysler Ag | Method for determining the position of a movable closure element of an injection valve |
DE102004029907A1 (en) * | 2004-06-21 | 2006-02-02 | Siemens Ag | Method and data processing device for simulating a piezo actuator and computer program |
DE102004063294B4 (en) * | 2004-12-29 | 2006-11-16 | Siemens Ag | Method and device for controlling an injection valve |
DE102005037361B4 (en) * | 2005-08-08 | 2007-05-24 | Siemens Ag | Method for determining a valve opening time |
DE102005046743B3 (en) * | 2005-09-29 | 2007-05-16 | Siemens Ag | Method for determining time point of stopper of valve body in drain valve actuated by electromechanical actuator, involves electrical control of actuator during load phase, so that stroke produced by actuator opens drain valve mechanically |
JP4475331B2 (en) | 2008-01-10 | 2010-06-09 | 株式会社デンソー | Fuel injection device |
DE102008023373B4 (en) * | 2008-05-13 | 2010-04-08 | Continental Automotive Gmbh | Method of controlling an injector, fuel injection system and internal combustion engine |
JP5284005B2 (en) * | 2008-08-25 | 2013-09-11 | 本田技研工業株式会社 | Control method of piezoelectric actuator |
DE112011101723B4 (en) * | 2010-05-20 | 2020-02-20 | Cummins Intellectual Property, Inc. | Piezoelectric fuel injector system, method for estimating timing characteristics of a fuel injection event |
DE102010039841B4 (en) * | 2010-08-26 | 2014-01-09 | Continental Automotive Gmbh | Method for adjusting the injection characteristic of an injection valve |
DE102010041320B4 (en) * | 2010-09-24 | 2021-06-24 | Vitesco Technologies GmbH | Determination of the closing time of a control valve of an indirectly driven fuel injector |
DE102012204278A1 (en) * | 2012-03-19 | 2013-09-19 | Continental Automotive Gmbh | Method for operating fuel injection system of internal combustion engine, involves determining force acting on passive piezo area, and applying signal of force sensor for detection and regulation of movement of closure element |
DE102012204272B4 (en) * | 2012-03-19 | 2021-10-28 | Vitesco Technologies GmbH | Method for operating a fuel injection system with control of the injection valve to increase the quantity accuracy and fuel injection system |
DE102013223750B3 (en) * | 2013-11-21 | 2015-02-19 | Continental Automotive Gmbh | Method for determining the valve opening time for piezoservo driven injectors |
DE102013226849B3 (en) * | 2013-12-20 | 2015-04-30 | Continental Automotive Gmbh | Method for operating an injection valve |
DE102014212377B4 (en) * | 2014-06-27 | 2016-07-21 | Continental Automotive Gmbh | Method for determining a state of an injection valve |
DE102015206286B4 (en) * | 2015-04-09 | 2019-05-29 | Continental Automotive Gmbh | Method and device for operating an injector |
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DE4308811B9 (en) * | 1992-07-21 | 2004-08-19 | Robert Bosch Gmbh | Method and device for controlling a solenoid-controlled fuel metering device |
GB9225622D0 (en) * | 1992-12-08 | 1993-01-27 | Pi Research Ltd | Electromagnetic valves |
DE19644521A1 (en) | 1996-10-25 | 1998-04-30 | Siemens Ag | Method and device for controlling a capacitive actuator |
DE19652801C1 (en) * | 1996-12-18 | 1998-04-23 | Siemens Ag | Driving at least one capacitive positioning element esp. piezoelectrically driven fuel injection valve for IC engine |
CN1290206C (en) * | 1998-06-25 | 2006-12-13 | 西门子公司 | Process and device for controlling capacitive actuator |
DE19930309C2 (en) * | 1999-07-01 | 2001-12-06 | Siemens Ag | Method and device for regulating the injection quantity in a fuel injection valve with a piezo element actuator |
DE19960971A1 (en) * | 1999-12-17 | 2001-03-08 | Bosch Gmbh Robert | Piezoactuator e.g. for fuel injector in IC engine, is connected mechanically in series with sensor with stack of interacting piezo elements that produces signal proportional to mechanical displacement |
EP1138912A1 (en) * | 2000-04-01 | 2001-10-04 | Robert Bosch GmbH | Online optimization of injection systems having piezoelectric elements |
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2001
- 2001-09-05 DE DE10143501A patent/DE10143501C1/en not_active Expired - Fee Related
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2002
- 2002-09-02 WO PCT/DE2002/003226 patent/WO2003023212A1/en active IP Right Grant
- 2002-09-02 DE DE50208611T patent/DE50208611D1/en not_active Expired - Lifetime
- 2002-09-02 JP JP2003527256A patent/JP4047809B2/en not_active Expired - Fee Related
- 2002-09-02 EP EP02760150A patent/EP1423593B1/en not_active Expired - Lifetime
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2004
- 2004-03-05 US US10/795,015 patent/US7040297B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
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Also Published As
Publication number | Publication date |
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DE10143501C1 (en) | 2003-05-28 |
JP4047809B2 (en) | 2008-02-13 |
EP1423593B1 (en) | 2006-11-02 |
US7040297B2 (en) | 2006-05-09 |
JP2005501999A (en) | 2005-01-20 |
WO2003023212A1 (en) | 2003-03-20 |
DE50208611D1 (en) | 2006-12-14 |
US20050072854A1 (en) | 2005-04-07 |
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