EP1926900B1 - Method and device for monitoring a fuel metering system - Google Patents

Method and device for monitoring a fuel metering system Download PDF

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Publication number
EP1926900B1
EP1926900B1 EP06793414.1A EP06793414A EP1926900B1 EP 1926900 B1 EP1926900 B1 EP 1926900B1 EP 06793414 A EP06793414 A EP 06793414A EP 1926900 B1 EP1926900 B1 EP 1926900B1
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EP
European Patent Office
Prior art keywords
pressure
error
fuel
rail
exponent
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Expired - Fee Related
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EP06793414.1A
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German (de)
French (fr)
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EP1926900A1 (en
Inventor
Hans Georg Bossemeyer
Michael Hackner
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3836—Controlling the fuel pressure
    • F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • 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
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails
    • 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
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F02M65/003—Measuring variation of fuel pressure in high pressure line
    • 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
    • F02D2041/1423—Identification of model or controller parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/224—Diagnosis of the fuel 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
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/224—Diagnosis of the fuel system
    • F02D2041/225—Leakage detection

Definitions

  • the invention is based on a method and a device for monitoring a Kraftstoffzumesssystems according to the preamble of the main claims.
  • From the DE 195 20 300 is a device for detecting a leak in a fuel supply system in an internal combustion engine, in particular a self-igniting internal combustion engine known.
  • the fuel is conveyed from at least one fuel pump under pressure from a fuel tank into a so-called high-pressure area.
  • injectors which are commonly referred to as injectors, enters the individual combustion chambers of the internal combustion engine.
  • the pressure in the high pressure region is detected by means of a pressure sensor.
  • This pressure sensor is usually used to adjust or regulate the pressure in the high pressure range.
  • the pressure is evaluated so that the pressure curve is detected and compared with an expected pressure curve. In the event of a deviation between an expected pressure curve and the actual pressure curve, the device detects a leak.
  • the EP 0974826 A2 describes a method for monitoring a fuel metering system, commonly referred to as a common rail system. Depending on the steepness of the pressure drop, a distinction is made between a large and a small leak. An assignment of the error to a component is not provided.
  • the DE 197 24 794 C1 describes a method and an apparatus for monitoring a common rail system. It is checked whether the pressure drop remains within a tolerance band by an expected value. If this is not the case, the device recognizes errors.
  • FIG. 12 shows a method that detects a defective component due to a deviation of the rail pressure from an expected value.
  • FIG. 1 In the FIG. 1 are exemplary essential elements of a Kraftstoffzumesssystems, in particular a diesel engine, shown.
  • 100 is the Internal combustion engine referred.
  • This fuel is supplied via a first injector 110 and a second injector 120.
  • the injectors 110 and 120 are connected via fuel lines with a rail 130 in connection.
  • At least one sensor 140 which emits a pressure variable p which characterizes the pressure in the high-pressure region, is arranged on the rail.
  • This print size is also referred to as rail pressure in the following.
  • other variables characterizing the rail pressure can be evaluated accordingly.
  • the rail 130 is acted upon by a high-pressure pump 150 with fuel.
  • This high pressure pump is associated with an actuating element 160, with which the amount of fuel delivered by the high pressure pump 150 and thus the rail pressure can be controlled.
  • This control element 160 and the injectors 110 and 120 are acted upon by a control unit 170 with drive signals.
  • the control unit also processes the output signal p of the sensor 140.
  • the rail and the line between the high-pressure pump 150 and the injectors as high-pressure region and the area before the high-pressure pump is referred to as low-pressure region.
  • the procedure is applicable to any number of injectors. For clarity, only two injectors are shown. It can also be provided more adjusting elements.
  • a further adjusting element can be provided by means of which the rail pressure can be controlled.
  • Such an actuating element is designed, for example, as a solenoid valve which connects the high-pressure region with the low-pressure region.
  • the control unit evaluates the signals of further sensors or controls further control elements for controlling the internal combustion engine 100.
  • the approach is not limited to systems with a rail. It can also be used on systems with multiple rails or even on systems without a rail. Instead of the rail pressure then a size corresponding to the rail pressure is evaluated.
  • the high-pressure pump 150 conveys the fuel from the low-pressure region, which in particular comprises the tank, into a high-pressure region, which in particular includes the rail 130.
  • the amount of fuel delivered and thus the rail pressure can be adjusted by means of the first control element 160.
  • this is done by a control that is part of the control unit 170.
  • the control unit 170 detects the rail pressure p via the sensor 140 and compares it with a desired value and controls the actuating element 160 as a function of the deviation between the setpoint and the actual value. From the high pressure region of the fuel passes through the injectors 110 and 120 in the internal combustion engine.
  • the injectors essentially include an actuator that can be designed as a solenoid valve or a piezoelectric actuator.
  • the control unit 170 acts on the Injectors 110 and 120 with such signals that the fuel is supplied at a predetermined time or to the predetermined angular position of the crankshaft of the internal combustion engine in a predetermined amount.
  • the pressure profile is evaluated and compared with different, in particular stored, pressure profiles.
  • the leakage is reliably detected and, on the other hand, the leakage is assigned to a specific component.
  • step 200 it is checked whether an operating state exists in which a check is possible. If this is not the case, query 200 takes place after a waiting time has elapsed. If query 200 recognizes that a check is possible, then in step 210 specific conditions are brought about which are necessary for the check. Thus, inter alia, in step 210, the high-pressure region is subjected to a test pressure. Furthermore, it is ensured by controlling the adjusting elements for regulating the rail pressure, in particular of the actuating element 160 and by controlling the injectors 110 and 120, that no further fuel is conveyed into the rail or removed from the rail. If additional actuators are provided, these must also be controlled accordingly.
  • step 220 the pressure curve over time or over the rotation of the crankshaft is then recorded. Subsequently, in step 230, the exponent of the pressure drop curve is determined.
  • the pressure-dependent leakage flow rates and pressure change rates have power functions to follow the pressure.
  • the pressure drop over time or over the angular position of the crankshaft approximately follows a so-called hyperbolic function with exponent.
  • the query 240 then checks which of these stored values the measured exponent comes closest to and assigns a stored value to the exponent.
  • the corresponding error can then be read from the table based on the stored exponent. In this case, usually a certain range of values of the exponent will be assigned to a type of error.
  • FIG. 3 For example, two curves of the rail pressure with and without pressure-dependent leakage gap widening over time are plotted. It can be seen from this figure that when the pressure value is monitored at a specific point in time t1, the pressure at different pressure curves has fallen to the same value. By means of an evaluation of the pressure at one or a few points in time, an assignment of the error to a component or a type of error is not always possible.

Description

Die Erfindung geht aus von einem Verfahren und einer Vorrichtung zur Überwachung eines Kraftstoffzumesssystems nach der Gattung der Hauptansprüche.The invention is based on a method and a device for monitoring a Kraftstoffzumesssystems according to the preamble of the main claims.

Aus der DE 195 20 300 ist eine Einrichtung zur Erkennung einer Leckage in einem Kraftstoffversorgungssystem bei einer Brennkraftmaschine, insbesondere einer selbstzündenden Brennkraftmaschine bekannt. Bei der dort beschriebenen Einrichtung wird der Kraftstoff von wenigstens einer Kraftstoffpumpe unter Druck aus einem Kraftstoffbehälter in einen sogenannten Hochdruckbereich gefördert. Vom Hochdruckbereich gelangt der Kraftstoff über Einspritzventile, die üblicherweise als Injektoren bezeichnet sind, in die einzelnen Brennräume der Brennkraftmaschine. Üblicherweise wird der Druck im Hochdruckbereich mittels eines Drucksensors erfasst. Dieser Drucksensor wird üblicherweise dazu verwendet um den Druck im Hochdruckbereich einzustellen bzw. einzuregeln. Im Stand der Technik wird der Druck dahingehend ausgewertet, dass der Druckverlauf erfasst und mit einem erwarteten Druckverlauf verglichen wird. Bei einer Abweichung zwischen einem erwarteten Druckverlauf und dem tatsächlichen Druckverlauf erkennt die Einrichtung eine Leckage.From the DE 195 20 300 is a device for detecting a leak in a fuel supply system in an internal combustion engine, in particular a self-igniting internal combustion engine known. In the device described therein, the fuel is conveyed from at least one fuel pump under pressure from a fuel tank into a so-called high-pressure area. From the high pressure region of the fuel via injectors, which are commonly referred to as injectors, enters the individual combustion chambers of the internal combustion engine. Usually, the pressure in the high pressure region is detected by means of a pressure sensor. This pressure sensor is usually used to adjust or regulate the pressure in the high pressure range. In the prior art, the pressure is evaluated so that the pressure curve is detected and compared with an expected pressure curve. In the event of a deviation between an expected pressure curve and the actual pressure curve, the device detects a leak.

Die EP 0974826 A2 beschreibt ein Verfahren zur Überwachung eines Kraftstoffzumesssystems, dass üblicherweise als Common-Rail-System bezeichnet wird. Abhängig von der Steilheit des Druckabfalls wird zwischen einem großen und einem kleinen Leck unterschieden. Eine Zuordnung des Fehler zu einer Komponente ist nicht vorgesehen.The EP 0974826 A2 describes a method for monitoring a fuel metering system, commonly referred to as a common rail system. Depending on the steepness of the pressure drop, a distinction is made between a large and a small leak. An assignment of the error to a component is not provided.

Die DE 197 24 794 C1 beschreibt ein Verfahren und eine Vorrichtung zur Überwachung eines Common-Rail-System. Es wird überprüft, ob der Druckabfall innerhalb eines Toleranzbandes um einen erwarteten Wert verbleibt. Ist dies nicht der Fall, so erkennt die Vorrichtung auf Fehler.The DE 197 24 794 C1 describes a method and an apparatus for monitoring a common rail system. It is checked whether the pressure drop remains within a tolerance band by an expected value. If this is not the case, the device recognizes errors.

Die JP 10-089135 A zeigt eine Verfahren, das eine defekte Komponente aufgrund einer Abweichung des Raildrucks von einem erwarteten Wert erkennt.The JP 10-089135 A FIG. 12 shows a method that detects a defective component due to a deviation of the rail pressure from an expected value.

Nachteilig bei dieser Art der Fehlerüberwachung ist, dass lediglich erkannt wird, ob eine Leckage auftritt bzw. ob keine Leckage vorliegt.The disadvantage of this type of error monitoring is that it is only recognized whether a leak occurs or whether there is no leakage.

Erfindungsgemäß wurde erkannt, dass unterschiedliche Fehler unterschiedliche Druckverläufe zur Folge haben. Insbesondere wurde erkannt, dass sich die Leckagen durch die Art der Strömung unterscheiden. Dabei wird insbesondere zwischen laminarenAccording to the invention, it has been recognized that different errors result in different pressure profiles. In particular, it was recognized that the leakages differ by the type of flow. It is especially between laminar

und turbulenten Strömungen unterschieden. Ferner sind druckabhängige Leckaufweitungen oder Leckschrumpfungen möglich. D.h. abhängig vom Druck ändert sich die Querschnittsfläche der Leckageöffnung. Dadurch ergibt sich die Möglichkeit, dass aus der Form der Druckabfallkurve auch die Leckageart erkannt wird. Durch die Zuordnung des gemessenen Druckverlaufs zu vorgegebenen Druckverläufen, die bei bestimmten Leckagen auftreten bzw. die bei einem Defekt verschiedener Komponenten auftreten, kann der Fehler sicher einer bestimmten Fehlerart und damit der defekten Komponente zugeordnet werden. D.h. ausgehend von dem Verlauf des Drucks kann die Art des Fehlers und damit die defekte Komponente sicher erkannt werden. Insbesondere erlaubt diese Vorgehensweise eine deutlich sicherere Leckageerkennung. Mit der herkömmlichen Vorgehensweise wird in jedem Fall bei einer Abweichung auch eine Leckage erkannt. Mit der neuen Erfindung werden bestimmte Druckverläufe, die nicht auf einer Leckage beruhen, im Stand der Technik aber als Leckage identifiziert würden, sicher als solche erkannt. Dadurch können unnötige Fehlerreaktionen, wie beispielsweise der Austausch von Komponenten, vermieden werden.and turbulent flows. Furthermore, pressure-dependent leak widening or leakage shrinkage are possible. That Depending on the pressure, the cross-sectional area of the leakage opening changes. This results in the possibility that from the shape of the pressure drop curve and the leakage type is detected. By assigning the measured pressure profile to predetermined pressure curves that occur in certain leaks or occur in a defect of various components, the error can be safely assigned to a certain type of error and thus the defective component. That Based on the course of the pressure, the type of fault and thus the defective component can be reliably detected. In particular, this approach allows a much safer leakage detection. With the conventional procedure, a leakage is detected in any case in case of a deviation. With the new invention, certain pressure gradients that are not based on leakage, but identified in the prior art as leakage, certainly recognized as such. As a result, unnecessary error reactions, such as the replacement of components, can be avoided.

Besonders vorteilhaft ist es, wenn der Verlauf der Druckgröße über der Zeit mit einer Funktion approximiert wird. Diese Approximation des Druckverlaufs liefert wenigstens eine oder mehrere die Funktion charakterisierende Größen. Das heißt es werden die charakteristischen Größen ermittelt, die den Druckverlauf am besten approximieren. Ausgehend diesen charakterisierenden Größe wird die Art des Fehlers und oder die defekte Komponente erkannt.It is particularly advantageous if the course of the pressure variable over time is approximated by a function. This approximation of the pressure curve yields at least one or more variables characterizing the function. This means that the characteristic quantities which best approximate the pressure curve are determined. Based on this characterizing size, the type of fault and / or the defective component is detected.

Zeichnungdrawing

  • In Figur 1 sind die wesentlichen Elemente eines Kraftstoffzumesssystems als Blockdiagramm dargestellt.In FIG. 1 the essential elements of a Kraftstoffzumesssystems are shown as a block diagram.
  • In Figur 2 ist die erfindungsgemäße Vorgehensweise und inIn FIG. 2 is the procedure according to the invention and in
  • Figur 3 verschiedene Druckverläufe über der Zeit aufgetragen. FIG. 3 various pressure curves over time applied.
Beschreibung des AusführungsbeispielsDescription of the embodiment

In der Figur 1 sind beispielhaft wesentliche Elemente eines Kraftstoffzumesssystems, insbesondere einer Dieselbrennkraftmaschine, dargestellt. Mit 100 ist die Brennkraftmaschine bezeichnet. Dieser werden über einen ersten Injektor 110 und einen zweiten Injektor 120 Kraftstoff zugeführt. Die Injektoren 110 und 120 stehen über Kraftstoffleitungen mit einem Rail 130 in Verbindung. An dem Rail ist wenigstens ein Sensor 140 angeordnet, der eine Druckgröße p abgibt, die den Druck im Hochdruckbereich charakterisiert.In the FIG. 1 are exemplary essential elements of a Kraftstoffzumesssystems, in particular a diesel engine, shown. With 100 is the Internal combustion engine referred. This fuel is supplied via a first injector 110 and a second injector 120. The injectors 110 and 120 are connected via fuel lines with a rail 130 in connection. At least one sensor 140, which emits a pressure variable p which characterizes the pressure in the high-pressure region, is arranged on the rail.

Diese Druckgröße wird im folgenden auch als Raildruck bezeichnet. Anstelle des Ausgangssignals des Sensors 140 können auch andere Größen, die den Raildruck charakterisieren, entsprechend ausgewertet werden.This print size is also referred to as rail pressure in the following. Instead of the output signal of the sensor 140, other variables characterizing the rail pressure can be evaluated accordingly.

Das Rail 130 wird von einer Hochdruckpumpe 150 mit Kraftstoff beaufschlagt. Dieser Hochdruckpumpe ist ein Stellelement 160 zugeordnet, mit dem die Menge des von der Hochdruckpumpe 150 geförderten Kraftstoffes und damit der Raildruck gesteuert werden kann. Dieses Stellelement 160 sowie die Injektoren 110 und 120 werden von einer Steuereinheit 170 mit Ansteuersignalen beaufschlagt. Die Steuereinheit verarbeitet auch das Ausgangssignal p des Sensors 140. Üblicherweise wird das Rail sowie die Leitung zwischen Hochdruckpumpe 150 und den Injektoren als Hochdruckbereich und der Bereich vor der Hochdruckpumpe als Niederdruckbereich bezeichnet.The rail 130 is acted upon by a high-pressure pump 150 with fuel. This high pressure pump is associated with an actuating element 160, with which the amount of fuel delivered by the high pressure pump 150 and thus the rail pressure can be controlled. This control element 160 and the injectors 110 and 120 are acted upon by a control unit 170 with drive signals. The control unit also processes the output signal p of the sensor 140. Usually, the rail and the line between the high-pressure pump 150 and the injectors as high-pressure region and the area before the high-pressure pump is referred to as low-pressure region.

Bei der darstellten Ausführungsform sind lediglich zwei Injektoren dargestellt. Die Vorgehensweise ist auf eine beliebige Anzahl von Injektoren anwendbar. Aus Übersichtlichkeitsgründen sind lediglich zwei Injektoren dargestellt. Es können auch weitere Stellelemente vorgesehen sein. So kann insbesondere ein weiteres Stellelement vorgesehen sein, mittels dem der Raildruck steuerbar ist. Ein solches Stellelement ist beispielsweise als Magnetventil ausgebildet, das den Hochdruckbereich mit dem Niederdruckbereich verbindet. Des weiteren wertet die Steuereinheit die Signale weiterer Sensoren aus bzw. steuert noch weitere Stellelemente zur Steuerung der Brennkraftmaschine 100 an. Ferner ist die Vorgehensweise nicht auf Systeme mit einem Rail beschränkt. Sie kann auch bei Systemen mit mehreren Rails oder auch bei Systemen ohne Rail eingesetzt werden. Anstelle des Raildrucks ist dann eine dem Raildruck entsprechende Größe auszuwerten.In the illustrated embodiment, only two injectors are shown. The procedure is applicable to any number of injectors. For clarity, only two injectors are shown. It can also be provided more adjusting elements. Thus, in particular, a further adjusting element can be provided by means of which the rail pressure can be controlled. Such an actuating element is designed, for example, as a solenoid valve which connects the high-pressure region with the low-pressure region. Furthermore, the control unit evaluates the signals of further sensors or controls further control elements for controlling the internal combustion engine 100. Furthermore, the approach is not limited to systems with a rail. It can also be used on systems with multiple rails or even on systems without a rail. Instead of the rail pressure then a size corresponding to the rail pressure is evaluated.

Die Hochdruckpumpe 150 fördert den Kraftstoff von dem Niederdruckbereich, der insbesondere den Tank umfasst, in einen Hochdruckbereich, der insbesondere das Rail 130 beinhaltet. Die Menge an gefördertem Kraftstoff und damit der Raildruck kann mittels des ersten Stellelements 160 eingestellt werden. Vorzugsweise erfolgt dies durch eine Regelung, die Teil der Steuereinheit 170 ist. Hierzu erfasst die Steuereinheit 170 über den Sensor 140 den Raildruck p und vergleicht diesen mit einem Sollwert und steuert abhängig von der Abweichung zwischen Soll- und Istwert das Stellelement 160 an. Von dem Hochdruckbereich gelangt der Kraftstoff über die Injektoren 110 bzw. 120 in die Brennkraftmaschine. Die Injektoren beinhalten im wesentlichen einen Aktor, der als Magnetventil oder als Piezoaktor ausgebildet sein kann. Die Steuereinheit 170 beaufschlagt die Injektoren 110 bzw. 120 mit solchen Signalen, dass der Kraftstoff zum vorgegebenen Zeitpunkt bzw. zur vorgegebenen Winkelstellung der Kurbelwelle der Brennkraftmaschine in vorgegebener Menge zugeführt wird.The high-pressure pump 150 conveys the fuel from the low-pressure region, which in particular comprises the tank, into a high-pressure region, which in particular includes the rail 130. The amount of fuel delivered and thus the rail pressure can be adjusted by means of the first control element 160. Preferably, this is done by a control that is part of the control unit 170. For this purpose, the control unit 170 detects the rail pressure p via the sensor 140 and compares it with a desired value and controls the actuating element 160 as a function of the deviation between the setpoint and the actual value. From the high pressure region of the fuel passes through the injectors 110 and 120 in the internal combustion engine. The injectors essentially include an actuator that can be designed as a solenoid valve or a piezoelectric actuator. The control unit 170 acts on the Injectors 110 and 120 with such signals that the fuel is supplied at a predetermined time or to the predetermined angular position of the crankshaft of the internal combustion engine in a predetermined amount.

Bei einem solchen System können eine Vielzahl von Fehlern auftreten. So kann der Fall eintreten, dass im Hochdruckbereich eine Leckage auftritt, d.h. dass Kraftstoff vom Hochdruckbereich in den Niederdruckbereich bzw. in die Umgebung gelangt. Ferner kann der Fall eintreten, dass durch die Injektoren eine erhöhte Kraftstoffmenge in die Brennkraftmaschine gelangt. Solche Fehler müssen sicher erkannt werden. Üblicherweise werden diese Fehler erkannt und dem Fahrer signalisiert bzw. in der Steuereinheit abgelegt und im Rahmen der Wartung ausgelesen. Tritt nun ein solcher Fehler auf, muss im Rahmen der Wartung der Fehler aufwändig gesucht werden. Erfindungsgemäß wurde nun erkannt, dass anhand des Druckverlaufs der Fehler einer bestimmten Komponente des Systems zugeordnet werden kann. Insbesondere wurde erkannt, dass bei Leckagen unterschiedlicher Komponenten unterschiedliche Druckverläufe auftreten.In such a system, a variety of errors may occur. Thus, the case may occur that leakage occurs in the high pressure region, i. that fuel from the high pressure area in the low pressure area or in the environment passes. Furthermore, the case may occur that an increased amount of fuel enters the internal combustion engine through the injectors. Such errors must be reliably detected. Usually, these errors are detected and signaled to the driver or stored in the control unit and read out as part of the maintenance. If such an error occurs, the error must be carefully searched during maintenance. According to the invention, it has now been recognized that the error can be assigned to a specific component of the system on the basis of the pressure profile. In particular, it was recognized that different pressure gradients occur with leaks of different components.

Erfindungsgemäß ist nun vorgesehen, dass der Druckverlauf ausgewertet wird und mit verschiedenen insbesondere abgespeicherten Druckverläufen verglichen wird. Anhand dieses Vergleichs wird zum einen die Leckage sicher erkannt und zum anderen die Leckage einer bestimmten Komponente zugeordnet.According to the invention, it is now provided that the pressure profile is evaluated and compared with different, in particular stored, pressure profiles. On the basis of this comparison, on the one hand, the leakage is reliably detected and, on the other hand, the leakage is assigned to a specific component.

In Figur 2 ist die erfindungsgemäße Vorgehensweise detailliert als Flussdiagramm dargestellt. In einem ersten Schritt 200 wird überprüft, ob ein Betriebszustand vorliegt, in dem eine Prüfung möglich ist. Ist dies nicht der Fall, so erfolgt nach Ablauf einer Wartezeit die Abfrage 200. Erkennt die Abfrage 200, dass eine Prüfung möglich ist, so werden in Schritt 210 gezielt Bedingungen herbeigeführt, die zur Prüfung notwendig sind. So wird unter anderem in Schritt 210 der Hochdruckbereich mit einem Prüfdruck beaufschlagt. Des Weiteren wird durch Ansteuerung der Stellelemente zur Regelung des Raildrucks, insbesondere des Stellelements 160 und durch Ansteuerung der Injektoren 110 und 120 gewährleistet, dass kein weiterer Kraftstoff in das Rail gefördert oder dem Rail entnommen wird. Sind weitere Steller vorgesehen, müssen diese ebenfalls in entsprechender Weise angesteuert werden. Im Schritt 220 wird dann der Druckverlauf über der Zeit bzw. über der Umdrehung der Kurbelwelle aufgezeichnet. Anschließend wird in Schritt 230 der Exponent der Druckabfallkurve ermittelt. Erfindungsgemäß wurde erkannt, dass bei einer Leckage die druckabhängigen Leckagedurchflüsse und Druckänderungsraten Potenzfunktionen des Druckes folgen. Entsprechend folgt bei einer Leckage der Druckabfall über der Zeit oder über der Winkelstellung der Kurbelwelle näherungsweise einer so genannten Hyperbelfunktion mit Exponent.In FIG. 2 the procedure according to the invention is shown in detail as a flow chart. In a first step 200, it is checked whether an operating state exists in which a check is possible. If this is not the case, query 200 takes place after a waiting time has elapsed. If query 200 recognizes that a check is possible, then in step 210 specific conditions are brought about which are necessary for the check. Thus, inter alia, in step 210, the high-pressure region is subjected to a test pressure. Furthermore, it is ensured by controlling the adjusting elements for regulating the rail pressure, in particular of the actuating element 160 and by controlling the injectors 110 and 120, that no further fuel is conveyed into the rail or removed from the rail. If additional actuators are provided, these must also be controlled accordingly. In step 220, the pressure curve over time or over the rotation of the crankshaft is then recorded. Subsequently, in step 230, the exponent of the pressure drop curve is determined. According to the invention, it has been recognized that, in the case of a leak, the pressure-dependent leakage flow rates and pressure change rates have power functions to follow the pressure. Correspondingly, in the event of a leakage, the pressure drop over time or over the angular position of the crankshaft approximately follows a so-called hyperbolic function with exponent.

Dies bedeutet, es werden verschiedene Druckwerte zu verschiedenen Zeitpunkten oder Winkelstellungen der Kurbel- oder Nockenwelle erfasst. Anschließend wird die Potenzfunktion der Druckänderungsrate über dem Druck ermittelt, mit dem die Potenzfunktion den Messwerten am nächsten kommt. Dabei eine Anpassung einer Hyperbelfunktion an den Druckverlauf über der Zeit eingesetzt.This means that different pressure values are recorded at different times or angular positions of the crankshaft or camshaft. Subsequently, the power function of the pressure change rate is determined above the pressure with which the power function comes closest to the measured values. An adaptation of a hyperbolic function to the pressure course over time is used.

Erfindungsgemäß wurde erkannt, dass unterschiedliche Strömungen, insbesondere Strömungen mit und ohne druckabhängiger Leckspaltaufweitung, unterschiedliche Exponenten aufweisen. Es gibt unterschiedliche Fehler, die Leckageströmungen mit und ohne druckabhängiger Leckspaltaufweitung entsprechen. Dies bedeutet, anhand des Exponenten kann die Fehlerart erkannt und damit einer bestimmten Komponente oder einer geringen Anzahl von Komponenten zugeordnet werden. Diese Zuordnung erfolgt in der Abfrage 240. In dieser wird beispielsweise abhängig von dem Wert des Exponenten ein erster Fehler 250 oder ein zweiter Fehler 260 erkannt. Vorzugsweise erfolgt dies dadurch, dass in einem Kennfeld oder in einer Kennlinie bzw. in einer Tabelle die Werte des Exponenten für verschiedene Fehler und/oder für den fehlerfreien Zustand abgelegt sind. Die Abfrage 240 überprüft dann, welchem dieser abgelegten Werte der gemessene Exponent am nächsten kommt und ordnet dem Exponenten einen abgelegten Wert zu. Aus der Tabelle kann dann ausgehend von dem abgelegten Exponenten der entsprechende Fehler ausgelesen werden. Dabei wird üblicherweise ein bestimmter Wertebereich des Exponenten einer Fehlerart zugeordnet sein.According to the invention, it has been recognized that different flows, in particular flows with and without pressure-dependent leakage gap widening, have different exponents. There are various errors that correspond to leakage flows with and without pressure-dependent leakage gap widening. This means that the type of error can be detected on the basis of the exponent and thus assigned to a specific component or a small number of components. This assignment takes place in the query 240. In this example, depending on the value of the exponent, a first error 250 or a second error 260 is detected. This is preferably done by storing the values of the exponent for different errors and / or for the error-free state in a characteristic field or in a characteristic curve or in a table. The query 240 then checks which of these stored values the measured exponent comes closest to and assigns a stored value to the exponent. The corresponding error can then be read from the table based on the stored exponent. In this case, usually a certain range of values of the exponent will be assigned to a type of error.

In der Figur 3 sind beispielhaft zwei Kurvenverläufe des Raildrucks mit und ohne druckabhängige Leckspaltaufweitung über der Zeit aufgetragen. Anhand dieser Figur ist zu erkennen, dass bei einer Überwachung des Druckwerts zu einem bestimmten Zeitpunkt t1 der Druck bei unterschiedlichen Druckverläufen auf den gleichen Wert abgefallen ist. Mittels einer Auswertung des Druckes an einem oder an wenigen Zeitpunkten ist eine Zuordnung des Fehlers zu einer Komponente oder einer Fehlerart nicht immer möglich.In the FIG. 3 For example, two curves of the rail pressure with and without pressure-dependent leakage gap widening over time are plotted. It can be seen from this figure that when the pressure value is monitored at a specific point in time t1, the pressure at different pressure curves has fallen to the same value. By means of an evaluation of the pressure at one or a few points in time, an assignment of the error to a component or a type of error is not always possible.

Claims (3)

  1. Method for monitoring a fuel metering system, in which fuel is fed from a low-pressure region into a high-pressure region, a pressure variable that characterizes the pressure in the high-pressure region being sensed and an error being detected on the basis of the variation of the pressure variable, characterized in that the type of error is detected on the basis of the variation of the pressure variable, the variation of the pressure variable over time being approximated by a hyperbolic function, an exponent of the hyperbolic function being determined and the type of error being detected on the basis of the exponent of the hyperbolic function.
  2. Method according to Claim 1, characterized in that the defective component is detected on the basis of the variation of the pressure variable.
  3. Device for monitoring a fuel metering system, in which fuel is fed from a low-pressure region into a high-pressure region, with means which sense a pressure variable that characterizes the pressure in the high-pressure region and detect an error on the basis of the variation of the pressure variable, characterized in that means which approximate the variation of the pressure variable over time with a hyperbolic function, determine an exponent of the hyperbolic function and detect the type of error on the basis of the exponent of the hyperbolic function are provided.
EP06793414.1A 2005-09-15 2006-09-11 Method and device for monitoring a fuel metering system Expired - Fee Related EP1926900B1 (en)

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DE102005043971A DE102005043971A1 (en) 2005-09-15 2005-09-15 Method and device for monitoring a fuel metering system
PCT/EP2006/066234 WO2007031492A1 (en) 2005-09-15 2006-09-11 Method and device for monitoring a fuel metering system

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JP (1) JP4646261B2 (en)
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EP1926900A1 (en) 2008-06-04
JP2009508054A (en) 2009-02-26
JP4646261B2 (en) 2011-03-09
DE102005043971A1 (en) 2007-03-22
WO2007031492A1 (en) 2007-03-22
US20090199627A1 (en) 2009-08-13
US8191411B2 (en) 2012-06-05
CN101263291A (en) 2008-09-10
KR20080055832A (en) 2008-06-19
CN101263291B (en) 2012-04-25
KR101046825B1 (en) 2011-07-06

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