EP1226355B1 - Method and device for the diagnosis of a fuel supply system - Google Patents

Method and device for the diagnosis of a fuel supply system Download PDF

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Publication number
EP1226355B1
EP1226355B1 EP00984821A EP00984821A EP1226355B1 EP 1226355 B1 EP1226355 B1 EP 1226355B1 EP 00984821 A EP00984821 A EP 00984821A EP 00984821 A EP00984821 A EP 00984821A EP 1226355 B1 EP1226355 B1 EP 1226355B1
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EP
European Patent Office
Prior art keywords
fuel
supply system
fuel supply
frequency
frequency spectrum
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Expired - Lifetime
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EP00984821A
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German (de)
French (fr)
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EP1226355A1 (en
Inventor
Thomas Frenz
Hansjoerg Bochum
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Robert Bosch GmbH
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Robert Bosch GmbH
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D41/221—Safety or indicating devices for abnormal conditions relating to the failure of actuators or electrically driven elements
    • 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
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—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
    • F02D2041/1432—Controller structures or design the system including a filter, e.g. a low pass or high pass filter
    • 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
    • F02D41/22—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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/28—Interface circuits
    • F02D2041/286—Interface circuits comprising means for signal processing
    • F02D2041/288—Interface circuits comprising means for signal processing for performing a transformation into the frequency domain, e.g. Fourier transformation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F02D2200/0604—Estimation of fuel pressure

Definitions

  • a fuel supply system of an internal combustion engine serves to fuel the engine from a Supply fuel tank.
  • the fuel is here from a fuel pump from the fuel tank a pressure line to one of the internal combustion engine located fuel rail with injectors pumped.
  • At the fuel rail or elsewhere in the fuel supply system is usually a Pressure sensor arranged.
  • the pressure sensor is the Fuel pressure measured in the fuel supply system and forwarded to a scheme.
  • the regulation holds the Pressure in the fuel supply system, in particular in the fuel rail, to a predetermined value.
  • the Not required by the internal combustion engine amount of fuel is usually from the fuel rail over a Return line led back into the fuel tank.
  • the fuel supply system may be referred to as a high pressure fuel delivery system, in particular as a common rail accumulator injection system for a direct injection Internal combustion engine, be formed in the one High-pressure fuel storage as fuel distributor is provided.
  • a high pressure fuel delivery system in particular as a common rail accumulator injection system for a direct injection Internal combustion engine, be formed in the one High-pressure fuel storage as fuel distributor is provided.
  • Fuel is removed from the fuel tank by a Electric fuel pump trained prefeed pump initially fed to a downstream high-pressure pump.
  • the High-pressure pump then delivers the fuel with a very high pressure in the high-pressure fuel storage, from where from he about the trained as injectors Injectors in a combustion chamber of the internal combustion engine ' arrives.
  • Pressure sensors arranged to control the fuel pressure in the High-pressure fuel storage for the regulation of To measure fuel pressure.
  • Such Fuel supply system is, for example, from the DE 195 39 885 A1.
  • the invention proposes starting from the method for diagnosing a Fuel supply system of the type mentioned suggest that when the amplitude of the Frequency component of the n-times the fundamental frequency of Fuel pump the deviation than from a fault of the Fuel pump is called, where n the number of cylinders of the fuel pump corresponds.
  • the course of the fuel pressure in the Fuel supply system can, for example, on the basis of a physical model of the fuel supply system be determined. This will be the physical model State variables of the fuel supply system and / or supplied to the internal combustion engine, from which the course of the Fuel pressure is modeled.
  • the fuel pressure in the Fuel supply system by means of a Pressure sensor measured.
  • a pressure sensor is usually in the fuel supply system for Detecting the fuel pressure for a control of Fuel pressure in the fuel supply system already available and can also be used to hold the Fuel pressure curve according to the present invention be used.
  • the frequency spectrum of the Fuel pressure curve formed is advantageously by means of a Fourier transformation of the Fuel pressure curve formed.
  • a characteristic frequency spectrum of the Fuel pressure curve By the way of working the fuel pump in the fuel supply system it comes to a characteristic frequency spectrum of the Fuel pressure curve.
  • a failure of the fuel supply system is the Frequency spectrum analyzed.
  • the frequency spectrum of the Fuel pressure curve in a faultless Fuel supply system one for each Fuel supply system characteristic course. Change certain errors of the fuel supply system the characteristic course of the frequency spectrum in a certain way. As part of the analysis of Frequency spectrum is trying these changes of the to recognize characteristic course and from the To close changes on the causative error. To recognize the changes of the characteristic Gradually, the frequency spectrum is, for example, with Thresholds compared. An increase or a fall The amplitude of the frequency spectrum can by a Comparison with corresponding amplitude thresholds be recognized. Similarly, a move of characteristic frequency components towards higher or lower frequencies by comparing with corresponding frequency thresholds are detected. The Linking a certain change in the characteristic course of the frequency spectrum with the causing error can, for example, by means of a Expert system. With the invention Procedure is thus a differentiated diagnosis of a Fault of the fuel supply system possible.
  • the course of the recorded Frequency spectrum is preferably with the course of the Frequency spectrum of a fault-free at this operating point working fuel supply system compared.
  • a Fuel supply system in which an n-cylinder fuel pump with a certain fundamental frequency is arranged, with a decrease in the amplitude of the Frequency component of the n-times the fundamental frequency of Fuel pump the deviation than from a fault of the Fuel pump caused classified.
  • a direct injection Internal combustion engine arise during operation of the Fuel pump pressure pulsations with n times Fundamental frequency of a work cycle.
  • the invention is prior to classifying the deviations the nature of the error the relevance of the deviations assessed. Slight deviations of the characteristic Course of the frequency spectrum, which is the cause in Temperature fluctuations or tolerances of Fuel supply system may have so remain unconsidered. Only such deviations as be judged significantly in the diagnosis of the Fuel supply system considered.
  • Invention is proposed that with an increase in the Amplitude of the frequency component of the 1-fold fundamental frequency the fuel pump's deviation than from a fault one of the pump cylinder of the fuel pump caused is classified.
  • the fundamental frequency of Fuel pump In the characteristic course of the Frequency spectrum of a faultless working Fuel supply system is at the fundamental frequency of Fuel pump only a frequency share with a to recognize relatively low amplitude.
  • the frequency component at the fundamental frequency of the fuel pump increases is This is a sure sign that a mistake is one of Pump cylinder of the fuel pump is present.
  • the present invention relates to a method for Diagnosis of a fuel supply system of a Internal combustion engine.
  • Method a differentiation of the error to individual Components of the fuel supply system.
  • an error of Fuel pump of the fuel supply system be diagnosed.
  • the fuel supply system in which the inventive method is used is preferably as a common rail accumulator injection system a direct-injection internal combustion engine is formed.
  • Common rail accumulator injection systems become fuel from a fuel tank by an as Electric fuel pump trained prefeed pump initially fed to a downstream high-pressure pump.
  • the High-pressure pump promotes the fuel with a very high pressure in a high-pressure fuel storage, from where from he injectors into a combustion chamber of the Internal combustion engine passes.
  • the of the internal combustion engine Unnecessary fuel quantity usually flows through the high-pressure fuel storage via a return line back into the fuel tank.
  • High-pressure fuel storage is a high-pressure sensor arranged, the fuel pressure in the High-pressure fuel storage measures and one High pressure control feeds the fuel pressure in the High-pressure fuel storage to a predetermined value regulates.
  • a function block 1 in Figure 1 is the inventive method started.
  • the recording of the course of the fuel pressure can be continuous, at regular times or too selected times.
  • a functional block 3 the frequency spectrum of the measured fuel pressure curve formed.
  • the Frequency spectrum is, for example, by means of a Fourier transform formed. Subsequently, the Frequency spectrum analyzed. This is done in one Function block 4, first, the frequency component of n times Basic frequency of the fuel pump with a speed-dependent amplitude threshold compared. Of Furthermore, the frequency component of the fundamental frequency of Fuel pump with another speed-dependent Amplitude threshold compared.
  • a diagnosis of a common rail storage injection system performed in which a 3-cylinder high-pressure pump is working.
  • the pressure pulsations are in the Frequency spectrum of the fuel pressure curve at 3 times Basic frequency of the high pressure pump with a Recognize frequency component with a relatively large amplitude.
  • An error in the high-pressure pump causes a drop the amplitude of this frequency component being detected.
  • an error causes one of the pump cylinders of the High pressure pump in addition to an increase in Amplitude of the frequency component at the fundamental frequency of High pressure feed pump.
  • the decrease or increase in the amplitudes of these Frequency components can be determined by amplitude thresholds be determined, which fell below or exceeded become. For this purpose, it is checked in a query block 5, if the Course of the frequency spectrum at 1-fold and 3-fold Basic frequency of the high-pressure pump above or is below a predetermined amplitude threshold. If No, the high-pressure pump is OK (Function block 6) and the inventive method returns back to the function block 1.
  • the dashed line between the function block 6 and the function block 1 should clarify that the method according to the present Embodiment not continuous, but cyclic or triggered.
  • Function block 7 If the frequency spectrum recorded Fuel pressure curve has deviations in the 1-fold or at the 3-fold fundamental frequency of High-pressure pump the predetermined amplitude thresholds exceed or fall short, is the High pressure pump defective (function block 7). In one Function block 8 is then set a fault memory.
  • FIG. 2 shows the measured course of the fuel pressure in the high-pressure fuel storage over a period of 0.5 seconds.
  • the fuel pressure was at a speed of the internal combustion engine of 2080 U / min measured.
  • the fundamental frequency of the working cycle of the 3-cylinder high-pressure pump of the common rail storage injection system is 17.3 Hz.

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

Abstract

The invention relates to a method and a device for the diagnosis of a fuel supply system pertaining to an internal combustion engine. The aim of the invention is to enable differentiation of an error with regard to the individual components of the fuel supply system. The invention provides a method which is characterised by the following steps: detecting the course of the fuel pressure in the fuel supply system (2), producing the frequency spectrum of the fuel pressure course (3) and analysing the frequency spectrum (4, 5). The analysis of the frequency spectrum preferably comprises the following steps: comparing the course of the detected frequency spectrum to the course of the frequency spectrum of a flawlessly working fuel supply system in this operating point and classifying the deviations according to the kind of error in the fuel supply system by which said errors were produced, when there are deviations between the courses of the frequency spectrums.

Description

Stand der TechnikState of the art

Die vorliegende Erfindung betrifft ein Verfahren zur Diagnose eines Kraftstoffversorgungssystems einer Brennkraftmaschine, wobei in dem Kraftstoffversorgungssystems eine n-Zylinder-Kraftstoffpumpe mit einer bestimmten Grundfrequenz angeordnet ist, umfassend die nachfolgenden Schritte:

  • Aufnahme des Verlaufs des Kraftstoffdrucks in dem Kraftstoffversorgungssytem;
  • Bilden des Frequenzsprektrums des Kraftstoffdruckverlaufs;
  • Vergleich des Verlaufs des aufgenommenen Frequenzsprektrums mit dem Verlauf des Frequenzspektrums eines fehlerfrei arbeitenden Kraftstoffversorgungssystems; und
  • falls Abweichungen zwischen den Verläufen der Frequenzspektren vorliegen, Klassifizieren der Abweichungen nach der Art der Fehler in dem Kraftstoffversorgungssystem, durch die sie hervorgerufen werden. Die Erfindung betrifft außerdem eine Vorrichtung zur Diagnose eines Kraftstoffversorgungssystems einer Brennkraftmaschine, wobei in dem Kraftstoffversorgungssystems eine n-Zylinder-Kraftstoffpumpe mit einer bestimmten Grundfrequenz angeordnet ist, mit
  • Mitteln zur Aufnahme des Verlaufs des Kraftstoffdrucks in dem Kraftstoffversorgungssytem;
  • Mitteln zum Bilden des Frequenzsprektrums des Kraftstoffdruckverlaufs;
  • Mitteln zum Vergleich des Verlaufs des aufgenommenen Frequenzsprektrums mit dem Verlauf des Frequenzspektrums eines fehlerfrei arbeitenden Kraftstoffversorgungssystems; und
  • falls Abweichungen zwischen den Verläufen der Frequenzspektren vorliegen, Mitteln zum Klassifizieren der Abweichungen nach der Art der Fehler in dem Kraftstoffversorgungssystem, durch die sie hervorgerufen werden.
The present invention relates to a method for diagnosing a fuel supply system of an internal combustion engine, wherein an n-cylinder fuel pump with a specific basic frequency is arranged in the fuel supply system, comprising the following steps:
  • Recording the course of the fuel pressure in the fuel supply system;
  • Forming the frequency spectrum of the fuel pressure waveform;
  • Comparison of the course of the recorded frequency spectrum with the course of the frequency spectrum of a faultless fuel supply system; and
  • if there are deviations between the traces of the frequency spectra, classifying the deviations according to the nature of the faults in the fueling system causing them. The invention also relates to a device for diagnosing a fuel supply system of an internal combustion engine, wherein in the fuel supply system, an n-cylinder fuel pump is arranged with a certain fundamental frequency, with
  • Means for recording the progress of the fuel pressure in the fuel supply system;
  • Means for forming the frequency spectrum of the fuel pressure waveform;
  • Means for comparing the course of the recorded Frequenzsprektrums with the course of the frequency spectrum of an error-free operating fuel supply system; and
  • if there are deviations between the traces of the frequency spectra, means for classifying the deviations according to the nature of the faults in the fueling system causing them.

Ein Kraftstoffversorgungssystem einer Brennkraftmaschine dient dazu, der Brennkraftmaschine Kraftstoff aus einem Kraftstoffbehälter zuzuführen. Der Kraftstoff wird dabei von einer Kraftstoffpumpe aus dem Kraftstoffbehälter über eine Druckleitung zu einem an der Brennkraftmaschine befindlichen Kraftstoffverteiler mit Einspritzventilen gepumpt. An dem Kraftstoffverteiler oder an anderer Stelle in dem Kraftstoffversorgungssystem ist üblicherweise ein Drucksensor angeordnet. Durch den Drucksensor wird der Kraftstoffdruck in dem Kraftstoffversorgungssystem gemessen und an eine Regelung weitergeleitet. Die Regelung hält den Druck in dem Kraftstoffversorgungssystem, insbesondere in dem Kraftstoffverteiler, auf einem vorgegebenen Wert. Die von der Brennkraftmaschine nicht benötigte Kraftstoffmenge wird üblicherweise aus dem Kraftstoffverteiler über eine Rücklaufleitung zurück in den Kraftstoffbehälter geführt.A fuel supply system of an internal combustion engine serves to fuel the engine from a Supply fuel tank. The fuel is here from a fuel pump from the fuel tank a pressure line to one of the internal combustion engine located fuel rail with injectors pumped. At the fuel rail or elsewhere in the fuel supply system is usually a Pressure sensor arranged. By the pressure sensor is the Fuel pressure measured in the fuel supply system and forwarded to a scheme. The regulation holds the Pressure in the fuel supply system, in particular in the fuel rail, to a predetermined value. The Not required by the internal combustion engine amount of fuel is usually from the fuel rail over a Return line led back into the fuel tank.

Das Kraftstoffversorgungssystem kann als ein Hochdruck-Kraftstoffversorgungssystem, insbesondere als ein Common-Rail-Speichereinspritzsystem für eine direkteinspritzende Brennkraftmaschine, ausgebildet sein, bei dem ein Kraftstoffhochdruckspeicher als Kraftstoffverteiler vorgesehen ist. Bei Common-Rail-Speichereinspritzsystemen wird Kraftstoff aus dem Kraftstoffbehälter durch eine als Elektrokraftstoffpumpe ausgebildete Vorförderpumpe zunächst einer nachgeordneten Hochdruckförderpumpe zugeführt. Die Hochdruckförderpumpe fördert den Kraftstoff dann mit einem sehr hohen Druck in den Kraftstoffhochdruckspeicher, von wo aus er über die als Injektoren ausgebildeten Einspritzventile in einen Brennraum der Brennkraftmaschine ' gelangt. In dem Kraftstoffhochdruckspeicher sind Drucksensoren angeordnet, um den Kraftstoffdruck in dem Kraftstoffhochdruckspeicher für die Regelung des Kraftstoffdrucks zu messen. Ein solches Kraftstoffversorgungssystem ist bspw. aus der DE 195 39 885 A1 bekannt.The fuel supply system may be referred to as a high pressure fuel delivery system, in particular as a common rail accumulator injection system for a direct injection Internal combustion engine, be formed in the one High-pressure fuel storage as fuel distributor is provided. In common-rail storage injection systems Fuel is removed from the fuel tank by a Electric fuel pump trained prefeed pump initially fed to a downstream high-pressure pump. The High-pressure pump then delivers the fuel with a very high pressure in the high-pressure fuel storage, from where from he about the trained as injectors Injectors in a combustion chamber of the internal combustion engine ' arrives. In the high-pressure fuel storage are Pressure sensors arranged to control the fuel pressure in the High-pressure fuel storage for the regulation of To measure fuel pressure. Such Fuel supply system is, for example, from the DE 195 39 885 A1.

Aus der US 5,499,538 ist ein Verfahren zur Diagnose eines Kraftstoffversorgungssystems einer Brennkraftmaschine, insbesondere zur Diagnose der Fehlfunktion einer Kraftstoffpumpe eines Kraftstoffversorgungssystems, der eingangs genannten Art bekannt. Der Verlauf des Kraftstoffdrucks in dem Kraftstoffversorgungssystem aufgenommen und durch eine Fast Fourier Transformation (FFT) das Frequenzspektrum des Kraftstoffdruckverlaufs gebildet. Zur Diagnose wird eine Resonanzfrequenz des Kraftstoffversorgungssystems und eine Resonanzfrequenz der Kraftstoffpumpe des aufgenommenen Frequenzspektrums hinsichtlich Frequenz und Amplitude mit dem Frequenzspektrum eines fehlerfrei arbeitenden Kraftstoffversorgungssystems verglichen.From US 5,499,538 is a method for diagnosing a Fuel supply system of an internal combustion engine, in particular for diagnosing the malfunction of a Fuel pump of a fuel supply system, the known type. The course of the Fuel pressure in the fuel supply system recorded and through a Fast Fourier transformation (FFT) the frequency spectrum of the fuel pressure curve educated. For diagnosis, a resonance frequency of the Fuel supply system and a resonance frequency of Fuel pump of the recorded frequency spectrum in terms of frequency and amplitude with the Frequency spectrum of a faultless working Fuel supply system compared.

Aus dem Stand der Technik ist es bekannt, aus einer Regelabweichung der Regelung des Kraftstoffdrucks in dem Kraftstoffversorgungssystem ganz allgemein einen Fehler des Kraftstoffversorgungssystems abzuleiten. Eine differenzierte Diagnose des Fehlers auf einzelne Komponenten des Kraftstoffversorgungssystems ist nicht möglich. Es wäre jedoch wünschenswert, insbesondere einen Defekt der Kraftstoffpumpe des Kraftstoffversorgungssystems diagnostizieren zu können. Eine defekte Kraftstoffpumpe kann dazu führen, dass der geforderte Kraftstoffdruck in dem Kraftstoffversorgungssystem nicht mehr erreicht werden kann uns es damit in bestimmten Betriebspunkten der Brennkraftmaschine zu abgasrelevanten und leistungsrelevanten Fehlern in der Gemischbildung kommt.From the prior art it is known from a Control deviation of the control of the fuel pressure in the Fuel supply system in general an error of the Derive fuel supply system. A differentiated diagnosis of the error on individual Components of the fuel supply system is not possible. However, it would be desirable, especially one Defective fuel pump of fuel supply system to be able to diagnose. A defective fuel pump can cause the required fuel pressure in the fuel supply system can not be achieved it can be us in certain operating points of the Internal combustion engine to exhaust gas relevant and performance-relevant errors in the mixture formation comes.

Deshalb ist es die Aufgabe der vorliegenden Erfindung, bei einer Diagnose eines Kraftstoffversorgungssystems einer Brennkraftmaschine innerhalb kurzer Zeit eine zuverlässige und differenzierte Diagnose eines Fehlers des Kraftstoffversorgungssystems zu ermöglichen.Therefore, it is the object of the present invention, at a diagnosis of a fuel supply system of a Internal combustion engine within a short time a reliable and differentiated diagnosis of a fault of the Fuel supply system to enable.

Zur Lösung dieser Aufgabe schlägt die Erfindung ausgehend von dem Verfahren zur Diagnose eines Kraftstoffversorgungssystems der eingangs genannten Art vor, dass bei einem Absinken der Amplitude des Frequenzanteils der n-fachen Grundfrequenz der Kraftstoffpumpe die Abweichung als von einem Fehler der Kraftstoffpumpe hervorgerufen klassifiziert wird, wobei n der Anzahl der Zylinder der Kraftstoffpumpe entspricht. To solve this problem, the invention proposes starting from the method for diagnosing a Fuel supply system of the type mentioned suggest that when the amplitude of the Frequency component of the n-times the fundamental frequency of Fuel pump the deviation than from a fault of the Fuel pump is called, where n the number of cylinders of the fuel pump corresponds.

Der Verlauf des Kraftstoffdrucks in dem Kraftstoffversorgungssystem kann bspw. an Hand eines physikalischen Modells des Kraftstoffversorgungssystems bestimmt werden. Dazu werden dem physikalischen Modell Zustandsgrößen des Kraftstoffversorgungssystems und/oder der Brennkraftmaschine zugeführt, aus denen der Verlauf des Kraftstoffdrucks modelliert wird.The course of the fuel pressure in the Fuel supply system can, for example, on the basis of a physical model of the fuel supply system be determined. This will be the physical model State variables of the fuel supply system and / or supplied to the internal combustion engine, from which the course of the Fuel pressure is modeled.

Vorteilhafterweise wird der Kraftstoffdruck in dem Kraftstoffversorgungssytem jedoch mittels eines Drucksensors gemessen. Ein solcher Drucksensor ist üblicherweise in dem Kraftstoffversorgungssystem zum Erfassen des Kraftstoffdrucks für eine Regelung des Kraftstoffdrucks in dem Kraftstoffversorgungssystem bereits vorhanden und kann auch zur Aufnahme des Kraftstoffdruckverlaufs gemäß der vorliegenden Erfindung herangezogen werden.Advantageously, the fuel pressure in the Fuel supply system, however, by means of a Pressure sensor measured. Such a pressure sensor is usually in the fuel supply system for Detecting the fuel pressure for a control of Fuel pressure in the fuel supply system already available and can also be used to hold the Fuel pressure curve according to the present invention be used.

Zur Diagnose wird das Frequenzspektrum des Kraftstoffdruckverlaufs gebildet. Das Frequenzspektrum wird vorteilhafterweise mittels einer Fouriertransformation des Kraftstoffdruckverlaufs gebildet. Durch die Arbeitsweise der Kraftstoffpumpe in dem Kraftstoffversorgungssystem kommt es zu einem charakteristischen Frequenzspektrum des Kraftstoffdruckverlaufs. Für eine differenzierte Diagnose eines Fehlers des Kraftstoffversorgungssystems wird das Frequenzspektrum analysiert.For diagnosis, the frequency spectrum of the Fuel pressure curve formed. The frequency spectrum is advantageously by means of a Fourier transformation of the Fuel pressure curve formed. By the way of working the fuel pump in the fuel supply system it comes to a characteristic frequency spectrum of the Fuel pressure curve. For a differentiated diagnosis a failure of the fuel supply system is the Frequency spectrum analyzed.

Im Einzelnen hat das Frequenzspektrum des Kraftstoffdruckverlaufs in einem fehlerfreien Kraftstoffversorgungssystem einen für das jeweilige Kraftstoffversorgungssystem charakteristischen Verlauf. Bestimmte Fehler des Kraftstoffversorgungssystems verändern den charakteristischen Verlauf des Frequenzspektrums in einer bestimmten Weise. Im Rahmen der Analyse des Frequenzspektrums wird versucht, diese Veränderungen des charakteristischen Verlaufs zu erkennen und aus den Veränderungen auf den verursachenden Fehler zu schließen. Zum Erkennen der Veränderungen des charakteristischen Verlaufs wird das Frequenzspektrum bspw. mit Schwellenwerten verglichen. Ein Anstieg bzw. ein Abfallen der Amplitude des Frequenzspektrums kann durch einen Vergleich mit entsprechenden Amplitudenschwellenwerten erkannt werden. Ebenso kann ein Verschieben von charakteristischen Frequenzanteilen hin zu höheren bzw. niedrigeren Frequenzen durch einen Vergleich mit entsprechenden Frequenzschwellenwerten erkannt werden. Die Verknüpfung einer bestimmten Veränderung des charakteristischen Verlaufs des Frequenzspektrums mit dem verursachenden Fehler kann bspw. mittels eines Expertensystems erfolgen. Mit dem erfindungsgemäßen Verfahren ist somit eine differenzierte Diagnose eines Fehlers des Kraftstoffversorgungssystems möglich.Specifically, the frequency spectrum of the Fuel pressure curve in a faultless Fuel supply system one for each Fuel supply system characteristic course. Change certain errors of the fuel supply system the characteristic course of the frequency spectrum in a certain way. As part of the analysis of Frequency spectrum is trying these changes of the to recognize characteristic course and from the To close changes on the causative error. To recognize the changes of the characteristic Gradually, the frequency spectrum is, for example, with Thresholds compared. An increase or a fall The amplitude of the frequency spectrum can by a Comparison with corresponding amplitude thresholds be recognized. Similarly, a move of characteristic frequency components towards higher or lower frequencies by comparing with corresponding frequency thresholds are detected. The Linking a certain change in the characteristic course of the frequency spectrum with the causing error can, for example, by means of a Expert system. With the invention Procedure is thus a differentiated diagnosis of a Fault of the fuel supply system possible.

Die Analyse des Frequenzspektrums umfasst die nachfolgenden Schritte:

  • Vergleich des Verlaufs des aufgenommenen Frequenzspektrums mit dem Verlauf des Frequenzspektrums eines fehlerfrei arbeitenden Kraftstoffversorgungssystems; und
  • falls Abweichungen zwischen den Verläufen der Frequenzspektren vorliegen, Klassifizieren der Abweichungen nach der Art der Fehler in dem Kraftstoffversorgungssystem, durch die sie hervorgerufen werden.
The analysis of the frequency spectrum includes the following steps:
  • Comparison of the course of the recorded frequency spectrum with the course of the frequency spectrum of a faultless fuel supply system; and
  • if there are deviations between the traces of the frequency spectra, classifying the deviations according to the nature of the faults in the fueling system causing them.

Bestimmte Fehler des Kraftstoffversorgungssystems verändern den charakteristischen Verlauf des Frequenzspektrums des Kraftstoffdruckverlaufs in einer definierten Weise. So kann insbesondere ein Fehler der Kraftstoffpumpe des Kraftstoffversorgungssystems und bei mehrzylindrigen Kraftstoffpumpen ein Fehler in einem der Pumpenzylinder aus dem Verlauf des aufgenommenen Frequenzspektrums diagnostiziert werden. Der Verlauf des aufgenommenen Frequenzspektrums wird vorzugsweise mit dem Verlauf des Frequenzspektrums eines in diesem Betriebspunkt fehlerfrei arbeitenden Kraftstoffversorgungssystems verglichen.Change certain errors of the fuel supply system the characteristic course of the frequency spectrum of the Fuel pressure curve in a defined manner. So can in particular a failure of the fuel pump of Fuel supply system and multi-cylinder Fuel pumps fail in one of the pump cylinders the course of the recorded frequency spectrum be diagnosed. The course of the recorded Frequency spectrum is preferably with the course of the Frequency spectrum of a fault-free at this operating point working fuel supply system compared.

Gemäß der vorliegenden Erfindung wird bei einem Kraftstoffversorgungssystem, in dem eine n-Zylinder-Kraftstoffpumpe mit einer bestimmten Grundfrequenz angeordnet ist, bei einem Absinken der Amplitude des Frequenzanteils der n-fachen Grundfrequenz der Kraftstoffpumpe die Abweichung als von einem Fehler der Kraftstoffpumpe hervorgerufen klassifiziert. Bei einer n-Zylinder-Kraftstoffpumpe, insbesondere bei einer n-Zylinder-Hochdruckförderpumpe eines Common-Rail-Speichereinspritzsystems einer direkteinspritzenden Brennkraftmaschine, entstehen beim Betrieb der Kraftstoffpumpe Druckpulsationen mit der n-fachen Grundfrequenz eines Arbeitsspiels. Durch die Aufnahme des Verlaufs des Kraftstoffdrucks und das Bilden des Frequenzspektrums des Kraftstoffdruckverlaufs ist in dem Verlauf des Frequenzspektrums deutlich ein Frequenzanteil bei der n-fachen Grundfrequenz der Kraftstoffpumpe zu erkennen. Falls die Amplitude des Frequenzanteils der n-fachen Grundfrequenz der Kraftstoffpumpe absinkt, ist dies ein sicheres Zeichen für das Vorliegen eine Fehlers der Kraftstoffpumpe. Durch eine Auswertung des Frequenzspektrums bei der n-fachen Grundfrequenz der Kraftstoffpumpe kann somit eine differenzierte Diagnose von Fehlern des Kraftstoffversorgungssystems dahingehend durchgeführt werden, dass zwischen Fehlern der Kraftstoffpumpe und sonstigen Fehlern des Kraftstoffversorgungssystems unterschieden wird.According to the present invention is in a Fuel supply system in which an n-cylinder fuel pump with a certain fundamental frequency is arranged, with a decrease in the amplitude of the Frequency component of the n-times the fundamental frequency of Fuel pump the deviation than from a fault of the Fuel pump caused classified. In an n-cylinder fuel pump, in particular in an n-cylinder high-pressure pump a common rail storage injection system a direct injection Internal combustion engine, arise during operation of the Fuel pump pressure pulsations with n times Fundamental frequency of a work cycle. By taking the History of the fuel pressure and forming the Frequency spectrum of the fuel pressure curve is in the Course of the frequency spectrum clearly a frequency component at n times the fundamental frequency of the fuel pump detect. If the amplitude of the frequency component of the n-times Base frequency of the fuel pump drops, this is a sure sign of the existence of an error Fuel pump. By an evaluation of the Frequency spectrum at n times the fundamental frequency of Fuel pump can thus have a differentiated diagnosis of Failures of the fuel supply system to the effect be done that between mistakes of the Fuel pump and other errors of the A fuel supply system is distinguished.

Gemäß einer vorteilhaften Weiterbildung der vorliegenden Erfindung wird vor dem Klassifizieren der Abweichungen nach der Art der Fehler die Erheblichkeit der Abweichungen beurteilt. Geringe Abweichungen des charakteristischen Verlaufs des Frequenzspektrums, die ihre Ursache in Temperaturschwankungen oder in Toleranzen des Kraftstoffversorgungssystems haben können, bleiben somit unberücksichtigt. Nur solche Abweichungen, die als erheblich beurteilt werden, werden bei der Diagnose des Kraftstoffversorgungssystems berücksichtigt.According to an advantageous embodiment of the present The invention is prior to classifying the deviations the nature of the error the relevance of the deviations assessed. Slight deviations of the characteristic Course of the frequency spectrum, which is the cause in Temperature fluctuations or tolerances of Fuel supply system may have so remain unconsidered. Only such deviations as be judged significantly in the diagnosis of the Fuel supply system considered.

Gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung wird vorgeschlagen, dass bei einer Zunahme der Amplitude des Frequenzanteils der 1-fachen Grundfrequenz der Kraftstoffpumpe die Abweichung als von einem Fehler eines der Pumpenzylinder der Kraftstoffpumpe hervorgerufen klassifiziert wird. In dem charakteristischen Verlauf des Frequenzspektrums eines fehlerfrei arbeitenden Kraftstoffversorgungssystems ist bei der Grundfrequenz der Kraftstoffpumpe lediglich ein Frequenzanteil mit einer relativ geringen Amplitude zu erkennen. Falls zusätzlich zu einem Absinken der Amplitude des Frequenzanteils bei der n-fachen Grundfrequenz der Kraftstoffpumpe der Frequenzanteil bei der Grundfrequenz der Kraftstoffpumpe ansteigt, ist dies ein sicheres Zeichen dafür, dass ein Fehler eines der Pumpenzylinder der Kraftstoffpumpe vorliegt.According to a preferred embodiment of the present invention Invention is proposed that with an increase in the Amplitude of the frequency component of the 1-fold fundamental frequency the fuel pump's deviation than from a fault one of the pump cylinder of the fuel pump caused is classified. In the characteristic course of the Frequency spectrum of a faultless working Fuel supply system is at the fundamental frequency of Fuel pump only a frequency share with a to recognize relatively low amplitude. In addition to a decrease in the amplitude of the frequency component at n times Fundamental frequency of the fuel pump the frequency component at the fundamental frequency of the fuel pump increases is This is a sure sign that a mistake is one of Pump cylinder of the fuel pump is present.

Vorteilhafterweise wird das Absinken oder die Zunahme der Amplitude des Frequenzanteils an Hand von Amplitudenschwellen ermittelt, die unterschritten bzw. überschritten werden. Die Amplitudenschwellenwerte sind üblicherweise abhängig von der Last und der Drehzahl der Kraftstoffpumpe des Kraftstoffversorgungssystems, d. h. die Analyse des Frequenzspektrums sollte sowohl last- als auch drehzahlabhängig durchgeführt werden. Um einen Gleichanteil in dem aufgenommenen Frequenzspektrum zu vermeiden, wird gemäß einer anderen bevorzugten Ausführungsform der vorliegenden Erfindung vorgeschlagen, dass vor der Analyse des Frequenzsprektrums der Mittelwert des aufgenommenen Kraftstoffdrucks subtrahiert wird:

  • Als weitere Lösung der Aufgabe der vorliegenden Erfindung wird ausgehend von der Vorrichtung zur Diagnose eines Kraftstoffversorgungssystems der eingangs genannten Art vorgeschlagen, dass die Mittel zum Klassifizieren der Abweichungen bei einem Absinken der Amplitude des Frequenzanteils der n-fachen Grundfrequenz der Kraftstoffpumpe die Abweichung als von einem Fehler der Kraftstoffpumpe hervorgerufen klassifiziert, wobei n der Anzahl der Zylinder der Kraftstoffpumpe entspricht.
  • Ein bevorzugtes Ausführungsbeispiel der vorliegenden Erfindung wird im Folgenden an Hand der Zeichnungen näher erläutert. Es zeigen:
    Figur 1
    ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens gemäß einer bevorzugten Ausführungsform;
    Figur 2
    den Verlauf des aufgenommenen Kraftstoffdrucks;
    Figur 3
    den Verlauf des Frequenzspektrums eines fehlerfrei arbeitenden Kraftstoffversorgungssystems; und
    Figur 4
    den Verlauf des Frequenzspektrums eines Kraftstoffversorgungssystems, in dem eine defekte Kraftstoffpumpe arbeitet.
    • Advantageously, the decrease or increase in the amplitude of the frequency component is determined by means of amplitude thresholds which are undershot or exceeded. The amplitude thresholds are usually dependent on the load and the speed of the fuel pump of the fuel supply system, ie the analysis of the frequency spectrum should be performed both load- and speed-dependent. In order to avoid a DC component in the recorded frequency spectrum, it is proposed according to another preferred embodiment of the present invention that before the analysis of the frequency spectrum the mean value of the recorded fuel pressure be subtracted:
  • As a further solution to the object of the present invention is proposed starting from the device for diagnosing a fuel supply system of the type mentioned that the means for classifying the deviations in a decrease in the amplitude of the frequency component of the n-times the fundamental frequency of the fuel pump, the deviation as from an error classified as fuel pump, wherein n corresponds to the number of cylinders of the fuel pump.
  • A preferred embodiment of the present invention will be explained in more detail below with reference to the drawings. Show it:
    FIG. 1
    a flow diagram of a method according to the invention according to a preferred embodiment;
    FIG. 2
    the course of the recorded fuel pressure;
    FIG. 3
    the course of the frequency spectrum of a faultless fuel supply system; and
    FIG. 4
    the course of the frequency spectrum of a fuel supply system in which a defective fuel pump operates.

    • Die vorliegende Erfindung betrifft ein Verfahren zur Diagnose eines Kraftstoffversorgungssystems einer Brennkraftmaschine. Bei Fehlern des Kraftstoffversorgungssystems erlaubt das erfindungsgemäße Verfahren eine Differenzierung des Fehlers auf einzelne Komponenten des Kraftstoffversorgungssystems. Insbesondere kann mit dem erfindungsgemäßen Verfahren ein Fehler einer Kraftstoffpumpe des Kraftstoffversorgungssystems diagnostiziert werden.The present invention relates to a method for Diagnosis of a fuel supply system of a Internal combustion engine. In case of errors of the Fuel supply system allows the invention Method a differentiation of the error to individual Components of the fuel supply system. Especially can with the inventive method an error of Fuel pump of the fuel supply system be diagnosed.

    Das Kraftstoffversorgungssystem, bei dem das erfindungsgemäße Verfahren eingesetzt wird, ist vorzugsweise als ein Common-Rail-Speichereinspritzsystem einer direkteinspritzenden Brennkraftmaschine ausgebildet. Bei Common-Rail-Speichereinspritzsystemen wird Kraftstoff aus einem Kraftstoffbehälter durch eine als Elektrokraftstoffpumpe ausgebildete Vorförderpumpe zunächst einer nachgeordneten Hochdruckförderpumpe zugeführt. Die Hochdruckförderpumpe fördert den Kraftstoff mit einem sehr hohen Druck in einen Kraftstoffhochdruckspeicher, von wo aus er über Injektoren in einen Brennraum der Brennkraftmaschine gelangt. Die von der Brennkraftmaschine nicht benötigte Kraftstoffmenge strömt üblicherweise durch den Kraftstoffhochdruckspeicher über eine Rücklaufleitung zurück in den Kraftstoffbehälter. In dem Kraftstoffhochdruckspeicher ist ein Hochdrucksensor angeordnet, der den Kraftstoffdruck in dem Kraftstoffhochdruckspeicher misst und einer Hochdruckregelung zuführt, die den Kraftstoffdruck in dem Kraftstoffhochdruckspeicher auf einen vorgegebenen Wert regelt.The fuel supply system in which the inventive method is used is preferably as a common rail accumulator injection system a direct-injection internal combustion engine is formed. Common rail accumulator injection systems become fuel from a fuel tank by an as Electric fuel pump trained prefeed pump initially fed to a downstream high-pressure pump. The High-pressure pump promotes the fuel with a very high pressure in a high-pressure fuel storage, from where from he injectors into a combustion chamber of the Internal combustion engine passes. The of the internal combustion engine Unnecessary fuel quantity usually flows through the high-pressure fuel storage via a return line back into the fuel tank. By doing High-pressure fuel storage is a high-pressure sensor arranged, the fuel pressure in the High-pressure fuel storage measures and one High pressure control feeds the fuel pressure in the High-pressure fuel storage to a predetermined value regulates.

    In einem Funktionsblock 1 in Figur 1 wird das erfindungsgemäße Verfahren gestartet. Zunächst wird in einem Funktionsblock 2 mittels des Hochdrucksensors der in dem Kraftstoffhochdruckspeicher herrschende Kraftstoffdruck gemessen. Die Aufnahme des Verlaufs des Kraftstoffdrucks kann kontinuierlich, zu regelmäßigen Zeitpunkten oder zu ausgewählten Zeitpunkten erfolgen.In a function block 1 in Figure 1 is the inventive method started. First, in a functional block 2 by means of the high pressure sensor of in the fuel high pressure accumulator prevailing fuel pressure measured. The recording of the course of the fuel pressure can be continuous, at regular times or too selected times.

    In einem Funktionsblock 3 wird das Frequenzspektrum des gemessenen Kraftstoffdruckverlaufs gebildet. Das Frequenzspektrum wird bspw. mittels einer Fouriertransformation gebildet. Anschließend wird das Frequenzspektrum analysiert. Dazu wird in einem Funktionsblock 4 zunächst der Frequenzanteil der n-fachen Grundfrequenz der Kraftstoffpumpe mit einem drehzahlabhängigen Amplitudenschwellenwert verglichen. Des Weiteren wird der Frequenzanteil der Grundfrequenz der Kraftstoffpumpe mit einem weiteren drehzahlabhängigen Amplitudenschwellenwert verglichen.In a functional block 3, the frequency spectrum of the measured fuel pressure curve formed. The Frequency spectrum is, for example, by means of a Fourier transform formed. Subsequently, the Frequency spectrum analyzed. This is done in one Function block 4, first, the frequency component of n times Basic frequency of the fuel pump with a speed-dependent amplitude threshold compared. Of Furthermore, the frequency component of the fundamental frequency of Fuel pump with another speed-dependent Amplitude threshold compared.

    Im Einzelnen wird in dem vorliegenden Ausführungsbeispiel eine Diagnose eines Common-Rail-Speichereinspritzsystems durchgeführt, in dem eine 3-Zylinder-Hochdruckförderpumpe arbeitet. Beim Einsatz der 3-Zylinder-Hochdruckförderpumpe entstehen Druckpulsationen mit der 3-fachen Grundfrequenz eines Arbeitsspiels. Die Druckpulsationen sind in dem Frequenzspektrum des Kraftstoffdruckverlaufs bei der 3-fachen Grundfrequenz der Hochdruckförderpumpe mit einem Frequenzanteil mit relativ großer Amplitude zu erkennen. Ein Fehler der Hochdruckförderpumpe führt zu einem Absinken der Amplitude dieses Frequenzanteils, der ermittelt wird. Des Weiteren führt ein Fehler eines der Pumpenzylinder der Hochdruckförderpumpe zusätzlich zu einem Anstieg der Amplitude des Frequenzanteils bei der Grundfrequenz der Hochdruckförderpumpe.More specifically, in the present embodiment a diagnosis of a common rail storage injection system performed in which a 3-cylinder high-pressure pump is working. When using the 3-cylinder high-pressure pump arise pressure pulsations with 3 times the fundamental frequency a working game. The pressure pulsations are in the Frequency spectrum of the fuel pressure curve at 3 times Basic frequency of the high pressure pump with a Recognize frequency component with a relatively large amplitude. An error in the high-pressure pump causes a drop the amplitude of this frequency component being detected. Furthermore, an error causes one of the pump cylinders of the High pressure pump in addition to an increase in Amplitude of the frequency component at the fundamental frequency of High pressure feed pump.

    Das Absinken oder die Zunahme der Amplituden dieser Frequenzanteile kann an Hand von Amplitudenschwellen ermittelt werden, die unterschritten bzw. überschritten werden. Dazu wird in einem Abfrageblock 5 überprüft, ob der Verlauf des Frequenzspektrums bei der 1-fachen bzw. der 3-fachen Grundfrequenz der Hochdruckförderpumpe oberhalb bzw. unterhalb einer vorgegebenen Amplitudenschwelle ist. Falls nein, ist die Hochdruckförderpumpe in Ordnung (Funktionsblock 6) und das erfindungsgemäße Verfahren kehrt zu dem Funktionsblock 1 zurück. Die gestrichelte Linie zwischen dem Funktionsblock 6 und dem Funktionsblock 1 soll verdeutlichen, dass das Verfahren gemäß dem vorliegenden Ausführungsbeispiel nicht kontinuierlich, sondern zyklisch oder getriggert aufgerufen wird.The decrease or increase in the amplitudes of these Frequency components can be determined by amplitude thresholds be determined, which fell below or exceeded become. For this purpose, it is checked in a query block 5, if the Course of the frequency spectrum at 1-fold and 3-fold Basic frequency of the high-pressure pump above or is below a predetermined amplitude threshold. If No, the high-pressure pump is OK (Function block 6) and the inventive method returns back to the function block 1. The dashed line between the function block 6 and the function block 1 should clarify that the method according to the present Embodiment not continuous, but cyclic or triggered.

    Falls das Frequenzspektrum aufgenommenen Kraftstoffdruckverlaufs Abweichungen aufweist, die bei der 1-fachen bzw. bei der 3-fachen Grundfrequenz der Hochdruckförderpumpe die vorgegebenen Amplitudenschwellen überschreiten bzw. unterschreiten, ist die Hochdruckförderpumpe defekt (Funktionsblock 7). In einem Funktionsblock 8 wird dann ein Fehlerspeicher gesetzt.If the frequency spectrum recorded Fuel pressure curve has deviations in the 1-fold or at the 3-fold fundamental frequency of High-pressure pump the predetermined amplitude thresholds exceed or fall short, is the High pressure pump defective (function block 7). In one Function block 8 is then set a fault memory.

    In Figur 2 ist der gemessene Verlauf des Kraftstoffdrucks in dem Kraftstoffhochdruckspeicher über einen Zeitraum von 0,5 Sekunden dargestellt. Der Kraftstoffdruck wurde bei einer Drehzahl der Brennkraftmaschine von 2080 U/min gemessen. Die Grundfrequenz des Arbeitsspiels der 3-Zylinder-Hochdruckförderpumpe des Common-Rail-Speichereinspritzsystems beträgt 17,3 Hz.FIG. 2 shows the measured course of the fuel pressure in the high-pressure fuel storage over a period of 0.5 seconds. The fuel pressure was at a speed of the internal combustion engine of 2080 U / min measured. The fundamental frequency of the working cycle of the 3-cylinder high-pressure pump of the common rail storage injection system is 17.3 Hz.

    In Figur 3 ist das Frequenzspektrum des gemessenen Kraftstoffdruckverlaufs aus Figur 2 dargestellt. Deutlich ist der Frequenzanteil der Hochdruckförderpumpe mit 3-facher Grundfrequenz (52 Hz) und der Frequenzanteil der Einspritzungen (4-Zylinder-Brennkraftmaschine, 69 Hz) zu erkennen. Bei der 1-fachen Grundfrequenz (17,3 Hz) ist kein auffälliger Frequenzanteil zu erkennen.In Figure 3, the frequency spectrum of the measured Fuel pressure curve shown in Figure 2. Clear is the frequency component of the high-pressure pump with 3 times Fundamental frequency (52 Hz) and the frequency component of Injections (4-cylinder engine, 69 Hz) too detect. At the 1-fold fundamental frequency (17.3 Hz) is no to recognize a noticeable frequency component.

    In Figur 4 ist das Frequenzspektrum des gemessenen Kraftstoffdrucks bei einer defekten Hochdruckförderpumpe dargestellt. Durch die defekte Hochdruckförderpumpe sinkt der Wirkungsgrad der Kraftstoffpumpe, was zu einem Absinken der Amplitude des Frequenzanteils bei der 3-fachen Grundfrequenz führt. Die Amplitude ist von knapp 300 (Figur 3) auf etwa 120 (Figur 4) abgesunken. Ist nur ein einzelner Pumpenzylinder der Hochdruckförderpumpe defekt, sinkt die Amplitude des Frequenzanteils der 3-fachen Grundfrequenz ebenfalls. Zusätzlich kommt zu dem Frequenzspektrum ein Frequenzanteil bei der 1-fachen Grundfrequenz der Hochdruckförderpumpe hinzu. Die Amplitude dieses Frequenzanteils ist von etwa 20 (Figur 3) auf über 100 (Figur 4) angestiegen.In Figure 4, the frequency spectrum of the measured Fuel pressure at a defective high pressure pump shown. Due to the defective high pressure pump sinks the efficiency of the fuel pump, causing a drop the amplitude of the frequency component at 3 times Fundamental frequency leads. The amplitude is just under 300 (fig 3) dropped to about 120 (Figure 4). Is only a single one Pump cylinder of the high pressure pump defective, the sinks Amplitude of the frequency component of 3 times the fundamental frequency also. In addition, comes to the frequency spectrum Frequency component at 1 times the fundamental frequency of Added high-pressure pump. The amplitude of this Frequency component is from about 20 (Figure 3) to over 100 (Figure 4) increased.

    Claims (8)

    1. Method for the diagnosis of a fuel supply system of an internal combustion engine, wherein an n-cylinder fuel pump with a specific natural frequency is arranged in the fuel supply system, comprising the following steps:
      recording of the profile of the fuel pressure in the fuel supply system (2);
      formation of the frequency spectrum of the fuel pressure profile (3);
      comparison of the profile of the recorded frequency spectrum with the profile of the frequency spectrum of a fuel supply system which operates free of faults; and
      if deviations occur between the profiles of the frequency spectrums, the deviations are classified according to the type of faults in the fuel supply system which cause them,
      characterized in that when the amplitude of the frequency component of the n-multiple natural frequency of the fuel pump drops, the deviation is classified (4) as being caused by a fault in the fuel pump, with n corresponding to the number of cylinders of the fuel pump.
    2. Method according to Claim 1, characterized in that the fuel pressure in the fuel supply system is measured by means of a pressure sensor.
    3. Method according to Claim 1 or 2, characterized in that the severity of the deviations is assessed according to the type of fault before the deviations are classified.
    4. Method according to one of Claims 1 to 3,
      characterized in that the frequency spectrum of the fuel pressure profile is formed by means of a Fourier transformation of the fuel pressure profile.
    5. Method according to one of Claims 1 to 4,
      characterized in that when the amplitude of the frequency component of the 1-multiple natural frequency of the fuel pump increases, the deviation is classified (4) as having been caused by a fault in one of the pump cylinders of the fuel pump.
    6. Method according to one of Claims 1 to 5,
      characterized in that the reduction or the increase in the amplitude of the frequency component is determined by reference to amplitude thresholds which are undershot or overshot (5).
    7. Method according to one of Claims 1 to 6,
      characterized in that before the frequency spectrum is analysed the mean value of the recorded fuel pressure is subtracted.
    8. Device for the diagnosis of a fuel supply system of an internal combustion engine, wherein an n-cylinder fuel pump with a specific natural frequency is arranged in the fuel supply system, having
      means for recording the profile of the fuel pressure in the fuel supply system (2);
      means for forming the frequency spectrum of the fuel pressure profile (3);
      means for comparing the profile of the recorded frequency spectrum with the profile of the frequency spectrum of a fuel supply system which operates free of faults; and
      if deviations occur between the profiles of the frequency spectrums, means for classifying the deviations according to the type of faults in the fuel supply system which cause them,
      characterized in that when the amplitude of the frequency component of the n-multiple natural frequency of the fuel pump drops, the means for classifying the deviations classify the deviation as having been caused by a fault in the fuel pump, with n corresponding to the number of cylinders of the fuel pump.
    EP00984821A 1999-10-19 2000-10-07 Method and device for the diagnosis of a fuel supply system Expired - Lifetime EP1226355B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    DE19950222A DE19950222A1 (en) 1999-10-19 1999-10-19 Procedure for diagnosis of fuel supply system of IC engine has recording of variation of fuel pressure in system, formation of frequency spectrum of fuel pressure variation and analysis thereof
    DE19950222 1999-10-19
    PCT/DE2000/003531 WO2001029411A1 (en) 1999-10-19 2000-10-07 Method and device for the diagnosis of a fuel supply system

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    EP1226355A1 EP1226355A1 (en) 2002-07-31
    EP1226355B1 true EP1226355B1 (en) 2005-08-31

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    US (1) US6901791B1 (en)
    EP (1) EP1226355B1 (en)
    JP (1) JP2003512566A (en)
    KR (1) KR100668576B1 (en)
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    WO (1) WO2001029411A1 (en)

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    KR100668576B1 (en) 2007-01-18
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    EP1226355A1 (en) 2002-07-31
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    WO2001029411A1 (en) 2001-04-26
    KR20020038957A (en) 2002-05-24

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