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EP1013917B1 - Method for testing a tank purge system - Google Patents

Method for testing a tank purge system Download PDF

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Publication number
EP1013917B1
EP1013917B1 EP99123162A EP99123162A EP1013917B1 EP 1013917 B1 EP1013917 B1 EP 1013917B1 EP 99123162 A EP99123162 A EP 99123162A EP 99123162 A EP99123162 A EP 99123162A EP 1013917 B1 EP1013917 B1 EP 1013917B1
Authority
EP
European Patent Office
Prior art keywords
tank
cross
correlation
filter device
testing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP99123162A
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German (de)
French (fr)
Other versions
EP1013917A2 (en
EP1013917A3 (en
Inventor
Jens Dr. Drückhammer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Volkswagen AG
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Volkswagen AG
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Filing date
Publication date
Priority claimed from DE19908138A external-priority patent/DE19908138B4/en
Application filed by Volkswagen AG filed Critical Volkswagen AG
Publication of EP1013917A2 publication Critical patent/EP1013917A2/en
Publication of EP1013917A3 publication Critical patent/EP1013917A3/en
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Publication of EP1013917B1 publication Critical patent/EP1013917B1/en
Anticipated expiration legal-status Critical
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M25/00Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/08Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
    • F02M25/0809Judging failure of purge control system
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2200/00Input parameters for engine control
    • F02D2200/02Input parameters for engine control the parameters being related to the engine
    • F02D2200/04Engine intake system parameters
    • F02D2200/0406Intake manifold pressure

Definitions

  • the invention relates to a method for testing a tank ventilation system, in particular a motor vehicle, with the mentioned in the preamble of claim 1 Features.
  • a pressure compensation This will be in volatile hydrocarbon gases present in the tank through the filter medium (Activated carbon) retained as filter material. If there is a negative pressure in the tank, this is done Pressure equalization also via the filter device.
  • a rinse of the filter device To remove the filter material takes place through the opening of the switching means. hereby the filter device by the in the intake system of the motor vehicle subjected to prevailing negative pressure, so that the filter material on the open Switching means is guided in the intake and the combustion air of the Internal combustion engine is supplied.
  • DE-A-4 122 975 shows a tank ventilation system for a motor vehicle and a method and a Device for checking their functionality.
  • the invention has for its object to provide a method of the generic type create, with the simple way a review of a tank ventilation system is possible.
  • this object is achieved by a method with the in claim 1 solved mentioned features.
  • correlation method for determining the similarity of two curves, here the drive signal and the the suction system defining measured value, are reliable and easy to handling procedures known.
  • DE-A-4 122 975 shows e.g. such a procedure.
  • FIG. 1 shows a tank ventilation system 10.
  • the tank ventilation system 10 comprises a tank ventilation system 10 Connecting line 12, a tank 14 with an intake 16 of a Combustion engine 18 connects.
  • the suction system 16 has a suction tube 20, so that by means of negative pressure from a source 22 combustion air can be sucked.
  • the Combustion air supply is adjustable with a throttle valve 24.
  • a tank vent valve 26 is integrated in the connecting line 12.
  • the Tank vent valve 26 is designed as an electromagnetic proportional valve, the is driven by a drive signal 28.
  • the drive signal 28 is from a Motor control unit provided and has a variable duty cycle. According to the duty cycle becomes a cross section of the connecting line 12th opened or closed.
  • the duty cycle of the drive signal 28 is proportional to the opening cross-section of the connecting line 12th
  • connection 30 branches to a filter device 32 from.
  • the filter device 32 is, for example, an activated carbon container 34, within the a bed of activated carbon 36 is arranged as a filter means. From one of the Activated carbon 36 downstream collecting space 38 performs a connection 40 to the outside.
  • a pressure sensor 42 is arranged, by means of which a Saugrohrdruck is measured as measured variable 44.
  • the general function of the tank venting system 10 is as follows:
  • a pressure P 1 Within the tank 14 there is a pressure P 1 .
  • a pressure P 2 In the intake manifold 20 there is a pressure P 2 , while an ambient pressure P 3 is present. If the pressure P 1 in the tank 14 rises above the ambient pressure P 3 , venting of the tank 14 takes place via the connecting line 12 and the connection 30 and the filter device 32. Fuel vapors are passed over the activated carbon 36 and filtered by the same and collected as filter material , The cleaned air exits via the connection 40 to the outside. If a negative pressure prevails in the tank 14, that is to say the pressure P 1 is less than the pressure P 3 , the filter device 32, the connection 30 and the connecting line 12 are sucked in air via the connection 40 and transferred into the tank 14. This possibly entrained filter material from the activated carbon 36 is not a problem, since the tank 14 is sealed pressure-tight.
  • the tank venting valve 26 opens according to the duty ratio of the drive signal 28. As a result, the pressure P 2 is applied to the tank 14 and to the filter device 32. Since a negative pressure prevails in the intake manifold 20, the pressure P 2 is less than the pressure P 1 and the pressure P 3 . As a result of this pressure gradient, the fuel vapors from the tank 14 and the fuel vapors stored in the activated carbon 36 are sucked in via the opened tank-venting valve 26 and supplied to the combustion air of the internal combustion engine 18. These thus burn during the combustion process.
  • the tank venting valve 26 To a safe venting of the tank 14 and cleaning of the filter device 32 to ensure the function of the tank vent valve 26 must be checked. Possible errors of the tank venting valve 26 could, for example, a clamping Be valve member, so that the tank vent valve 26 either no longer opens or no longer closes. Furthermore, dirt could in the connecting line 12th be deposited, which lead to cross-sectional constrictions and thus the function affect. In addition, it is known that the connecting line 12 as flexible Form line (hose) so that any kinks or the like could also lead to cross-sectional constrictions.
  • hose flexible Form line
  • the method according to the invention for testing the tank ventilation system 10 will be explained with reference to FIG.
  • the test procedure is initialized (field 52).
  • it is checked via a query 54 whether release conditions 56 are given for the test method.
  • release conditions 56 include, for example, parallel-running control actions or parallel-running diagnostic procedures of other devices of the motor vehicle that could be affected by the test method 48.
  • the release check 56 includes, for example, the query 58 about the current suction pressure P 2 according to the measurement result 44. For example, differences between a maximum and a minimum suction pressure are evaluated.
  • a stimulation signal 64 is supplied, which corresponds to the duty cycle of the drive signal 28.
  • a stimulation signal +1 for actuated tank venting valve 26 and of -1 for not activated tank venting valve 26 can be supplied.
  • a repeat check 68 is triggered by means of a signal 66.
  • the number of measuring cycles performed is compared with a predetermined number.
  • the repeat check is triggered via the signal 70. If the number of measuring cycles carried out is equal to the predetermined number, the diagnosis 74 is carried out via the signal 72. In the diagnosis 74, a correlation coefficient of the correlation calculation 62 performed is checked. If this correlation coefficient has a value of 1, the drive signal 28 and the measured variable 44 (intake manifold pressure) are identical in the sense of the correlation calculation. If, on the other hand, the correlation coefficient has a value of 0, there is no correlation between the sampling signal 28 and the measured variable 44, so that an error 76 is detected. Upon detection of the error 76, for example, a driver can be given an information by an optical signal that the tank ventilation system 10 is faulty.
  • An abort 78 of the process takes place, for example, when the examination of the Release condition 56 a signal 80 is generated, which is the absence of the defined release conditions includes. Furthermore, during stimulation of the Control signal 28 or during the detection of the measured variable 44 a Signal 82 are generated, which also leads to abort 78.
  • the signal 82 can be an error signal, for example, if the measured variable 44 is missing or implausible, Expiration of a planned total service life of the tank venting valve 26 and / or at Reaching the predetermined number of measuring cycles to be performed during the Repeat test 68.
  • a Timers are started, the test method 48 by reinitialization 52 again starts.
  • the test method 48 with each Restart of the internal combustion engine 18 is running.
  • a signal for example via a potentiometer, can be tapped, which corresponds to the position of the throttle valve 24.
  • Cross-correlation can be passive or active. At the passive Cross correlation are the signals to be evaluated, here the drive signal 28 and the measurand 44, processed unaffected. In active cross correlation, the in the cross-correlation incoming control signals 28 and 44 measured Stimulation signals stimulated, so that a sensitivity of the test method 48 can be increased.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Supplying Secondary Fuel Or The Like To Fuel, Air Or Fuel-Air Mixtures (AREA)
  • Testing Of Engines (AREA)

Abstract

The method involves feeding volatile gas containing. hydrogen emanating from the tank (14) via a filter arrangement (32) in which it is collected. The filter arrangement is subjected to a vacuum to feed the filter material via a induction system (16) of an induction process into an internal combustion engine, whereby the connection between the filter arrangement and induction system is opened and closed by a clocked switching device. A drive signal for the switching device is cross-correlated with a measurement parameter defining the state of the induction system, and a correlation coefficient is evaluated as a diagnostic signal for the tank venting system.

Description

Die Erfindung betrifft ein Verfahren zum Prüfen eines Tankentlüftungssystems, insbesondere eines Kraftfahrzeuges, mit den im Oberbegriff des Anspruchs 1 genannten Merkmalen.The invention relates to a method for testing a tank ventilation system, in particular a motor vehicle, with the mentioned in the preamble of claim 1 Features.

Es ist bekannt, in Kraftfahrzeuge Tankentlüftungssysteme vorzusehen, mittels denen ein Druckausgleich sowie eine Be- und Entlüftung eines Kraftstofftanks erfolgt. Hierbei ist der Tank über eine Leitung mit einer Sauganlage einer Verbrennungskraftmaschine verbunden. In diese Leitung ist ein getaktes ansteuerbares Schaltmittel, beispielsweise ein elektromagnetisches Ventil, eingebunden, mittels dem die Verbindung definiert geöffnet beziehungsweise geschlossen werden kann. Das Magnetventil wird hierbei mit einem Ansteuersignal mit einem einstellbaren Tastverhältnis angesteuert, so daß sich ein Öffnungsquerschnitt proportional zum Ansteuertastverhältnis ergibt. Die Verbindung zwischen dem Tank und der Sauganlage steht femer mit einer Filtereinrichtung, beispielsweise einem Aktivkohlebehälter, in Verbindung. Diese Filtereinrichtung besitzt eine dem Filtermittel nachgeordnete Öffnung ins Freie. Steigt beispielsweise der Druck in dem Tank an, erfolgt über die Filtereinrichtung ein Druckausgleich. Hierbei werden in dem Tank sich befindende flüchtige kohlenwasserstoffhaltige Gase durch das Filtermittel (Aktivkohle) als Filtergut zurückgehalten. Herrscht im Tank ein Unterdruck, erfolgt ein Druckausgleich ebenfalls über die Filtereinrichtung. Eine Spülung der Filtereinrichtung zum Entfemen des Filtergutes erfolgt durch die Öffnung des Schaltmittels. Hierdurch wird die Filtereinrichtung durch den in der Sauganlage des Kraftfahrzeuges herrschenden Unterdruck beaufschlagt, so daß das Filtergut über das geöffneten Schaltmittel in die Sauganlage geführt wird und der Verbrennungsluft der Verbrennungskraftmaschine zugeführt wird.It is known to provide in motor vehicles tank ventilation systems, by means of which a Pressure equalization and a ventilation of a fuel tank takes place. Here is the tank via a line with an intake system of an internal combustion engine connected. In this line is a clocked controllable switching means, for example an electromagnetic valve, integrated, by means of which the connection is defined can be opened or closed. The solenoid valve is here with a drive signal driven with an adjustable duty cycle, so that an opening cross-section proportional to the Ansteuertastverhältnis results. The connection between the tank and the suction system furthermore stands with a filter device, for example, an activated carbon container in conjunction. This filter device has a downstream of the filter medium opening to the outside. If, for example, the pressure increases in the tank, takes place via the filter device, a pressure compensation. This will be in volatile hydrocarbon gases present in the tank through the filter medium (Activated carbon) retained as filter material. If there is a negative pressure in the tank, this is done Pressure equalization also via the filter device. A rinse of the filter device To remove the filter material takes place through the opening of the switching means. hereby the filter device by the in the intake system of the motor vehicle subjected to prevailing negative pressure, so that the filter material on the open Switching means is guided in the intake and the combustion air of the Internal combustion engine is supplied.

Aus Gründen des Umweltschutzes ist es erforderlich, daß die Funktion des Tankentlüftungssystems überwacht wird. Insbesondere ist ein sicheres getaktetes Schalten des Schaltmittels (Magnetventil) notwendig, damit die Filtereinrichtung in regelmäßigen Abständen gespült (gereinigt) werden kann.For reasons of environmental protection, it is necessary that the function of the Tank venting system is monitored. In particular, a secure clocked Switching the switching means (solenoid valve) necessary to allow the filter device in can be rinsed (cleaned) at regular intervals.

DE-A-4 122 975 zeigt eine Tankentlüftungsanlage für ein Kraftfahrzeug und ein Verfahren und eine Vorrichtung zum Überprüfen von deren Funktionsfähigkeit. DE-A-4 122 975 shows a tank ventilation system for a motor vehicle and a method and a Device for checking their functionality.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren der gattungsgemäßen Art zu schaffen, mit dem in einfacher Weise eine Überprüfung eines Tankentlüftungssystems möglich ist.The invention has for its object to provide a method of the generic type create, with the simple way a review of a tank ventilation system is possible.

Erfindungsgemäß wird diese Aufgabe durch ein Verfahren mit den im Anspruch 1 genannten Merkmalen gelöst. Dadurch, daß ein Ansteuersignal für das Schaltmittel mit einem, einen Zustand der Sauganlage definierenden Meßwert kreuzkorreliert wird und ein Korrelationskoeffizient als Diagnosesignal des Tankentlüftungssystems ausgewertet wird, wird vorteilhaft ein sehr sicheres Diagnoseergebnis erhalten. Korrelationsverfahren zur Ermittlung der Ähnlichkeit zweier Kurvenverläufe, hier des Ansteuersignals und der die Sauganlage definierenden Meßgröße, sind als zuverlässige und einfach zu handhabende Verfahren bekannt. DE-A-4 122 975 zeigt z.B. solch ein Verfahren. Diese Verfahren üben keinen relevanten Einfluß auf die zu korrelierenden Meßgrößen aus, so daß ein Einfluß auf den Betrieb des Tankentlüftungssystems beziehungsweise der gesamten Verbrennungskraftmaschine bei Kraftfahrzeugen nicht gegeben ist. Derartige Kreuzkorrelationsverfahren sind ferner sehr robust, so daß einzuhaltende Freigabebedingungen für die Durchführung des Verfahrens auf ein Minimum reduziert werden können. Derartige Freigabebedingungen sind insbesondere parallel verlaufende Diagnoseverfahren beziehungsweise Steueroder Regelungsverfahren, die durch die hier angesprochene Kreuzkorrelation beeinträchtigt werden könnten.According to the invention this object is achieved by a method with the in claim 1 solved mentioned features. Characterized in that a drive signal for the switching means with a, a state of the intake system defining measured value is cross-correlated and a correlation coefficient is evaluated as a diagnostic signal of the tank ventilation system is, is advantageously obtained a very secure diagnosis result. correlation method for determining the similarity of two curves, here the drive signal and the the suction system defining measured value, are reliable and easy to handling procedures known. DE-A-4 122 975 shows e.g. such a procedure. These methods have no relevant influence the measured variables to be correlated, so that an influence on the operation of the Tank ventilation system or the entire internal combustion engine in motor vehicles is not given. Such cross-correlation methods are further very robust, so that to be observed release conditions for the implementation of Procedure can be reduced to a minimum. Such release conditions are in particular parallel diagnostic methods or Steueroder Regulatory procedure, by the cross-correlation mentioned here could be affected.

In bevorzugter Ausgestaltung der Erfindung ist vorgesehen, daß als den Zustand der Sauganlage definierende Meßgröße ein Saugrohrdruck oder eine Drosselklappenposition verwendet wird. Diese Meßgrößen sind einfach abzugreifen und stehen bei üblichen Ausstattungen von Kraftfahrzeugen bereits zur Verfügung. Insbesondere, wenn die Kreuzkorrelation durch ein Motorsteuergerät des Kraftfahrzeugs durchgeführt wird, können die Meßgrößen in einfacher Weise abgegriffen werden.In a preferred embodiment of the invention it is provided that as the state of Suction system defining variable an intake manifold pressure or a Throttle position is used. These quantities are easy to access and are already available for conventional equipment of motor vehicles. In particular, when the cross-correlation by an engine control unit of the motor vehicle is carried out, the measured variables can be tapped in a simple manner.

Weitere bevorzugte Ausgestaltungen der Erfindung ergeben sich aus den übrigen, in den Unteransprüchen genannten Merkmalen.Further preferred embodiments of the invention will become apparent from the others, in the subclaims mentioned features.

Die Erfindung wird nachfolgend in einem Ausführungsbeispiel anhand der zugehörigen Zeichnungen näher erläutert. Es zeigen:

Figur 1
eine schematische Ansicht eines Tankentlüftungssystems und
Figur 2
ein Blockschaltbild für die Durchführung eines Verfahrens zum Prüfen des Tankentlüftungssystems.
The invention will be explained in more detail in an embodiment with reference to the accompanying drawings. Show it:
FIG. 1
a schematic view of a tank ventilation system and
FIG. 2
a block diagram for carrying out a method for testing the tank ventilation system.

Figur 1 zeigt ein Tankentlüftungssystem 10. Das Tankentlüftungssystem 10 umfaßt eine Verbindungsleitung 12, die einen Tank 14 mit einer Sauganlage 16 einer Verbrennungskraftmaschine 18 verbindet. Die Sauganlage 16 besitzt ein Saugrohr 20, so daß mittels Unterdruck von einer Quelle 22 Verbrennungsluft ansaugbar ist. Die Verbrennungsluftzufuhr ist mit einer Drosselklappe 24 regelbar.FIG. 1 shows a tank ventilation system 10. The tank ventilation system 10 comprises a tank ventilation system 10 Connecting line 12, a tank 14 with an intake 16 of a Combustion engine 18 connects. The suction system 16 has a suction tube 20, so that by means of negative pressure from a source 22 combustion air can be sucked. The Combustion air supply is adjustable with a throttle valve 24.

In die Verbindungsleitung 12 ist ein Tankentlüftungsventil 26 integriert. Das Tankentlüftungsventil 26 ist als elektromagnetisches Proportionalventil ausgeführt, das von einem Ansteuersignal 28 angesteuert wird. Das Ansteuersignal 28 wird von einem Motorsteuergerät bereitgestellt und besitzt ein veränderbares Tastverhältnis. Entsprechend dem Tastverhältnis wird ein Querschnitt der Verbindungsleitung 12 geöffnet beziehungsweise geschlossen. Das Tastverhältnis des Ansteuersignals 28 ist proportional zum Öffnungsquerschnitt der Verbindungsleitung 12.In the connecting line 12, a tank vent valve 26 is integrated. The Tank vent valve 26 is designed as an electromagnetic proportional valve, the is driven by a drive signal 28. The drive signal 28 is from a Motor control unit provided and has a variable duty cycle. According to the duty cycle becomes a cross section of the connecting line 12th opened or closed. The duty cycle of the drive signal 28 is proportional to the opening cross-section of the connecting line 12th

Von der Verbindungsleitung 12 zweigt eine Verbindung 30 zu einer Filtereinrichtung 32 ab. Die Filtereinrichtung 32 ist beispielsweise ein Aktivkohlebehälter 34, innerhalb dem eine Schüttung von Aktivkohle 36 als Filtermittel angeordnet ist. Von einem der Aktivkohle 36 nachgeordneten Sammelraum 38 führt eine Verbindung 40 ins Freie.From the connecting line 12, a connection 30 branches to a filter device 32 from. The filter device 32 is, for example, an activated carbon container 34, within the a bed of activated carbon 36 is arranged as a filter means. From one of the Activated carbon 36 downstream collecting space 38 performs a connection 40 to the outside.

In dem Saugrohr 20 ist ein Drucksensor 42 angeordnet, mittels dem ein Saugrohrdruck als Meßgröße 44 abgegriffen wird.In the suction pipe 20, a pressure sensor 42 is arranged, by means of which a Saugrohrdruck is measured as measured variable 44.

Die allgemeine Funktion des Tankentlüftungssystems 10 ist folgende:The general function of the tank venting system 10 is as follows:

Innerhalb des Tanks 14 herrscht ein Druck P1. Im Saugrohr 20 herrscht ein Druck P2, während ein Umgebungsdruck P3 anliegt. Steigt der Druck P1 im Tank 14 über den Umgebungsdruck P3 an, erfolgt über die Verbindungsleitung 12 sowie die Verbindung 30 und die Filtereinrichtung 32 eine Entlüftung des Tanks 14. Hierbei werden Kraftstoffdämpfe über die Aktivkohle 36 geführt und von dieser gefiltert und als Filtergut gesammelt. Die gereinigte Luft tritt über die Verbindung 40 ins Freie aus. Herrscht im Tank 14 ein Unterdruck, das heißt der Druck P1 ist kleiner als der Druck P3, wird über die Verbindung 40 die Filtereinrichtung 32, die Verbindung 30 und die Verbindungsleitung 12 Luft angesaugt und in den Tank 14 überführt. Hierbei eventuell mitströmendes Filtergut aus der Aktivkohle 36 ist unproblematisch, da der Tank 14 druckdicht verschlossen ist.Within the tank 14 there is a pressure P 1 . In the intake manifold 20 there is a pressure P 2 , while an ambient pressure P 3 is present. If the pressure P 1 in the tank 14 rises above the ambient pressure P 3 , venting of the tank 14 takes place via the connecting line 12 and the connection 30 and the filter device 32. Fuel vapors are passed over the activated carbon 36 and filtered by the same and collected as filter material , The cleaned air exits via the connection 40 to the outside. If a negative pressure prevails in the tank 14, that is to say the pressure P 1 is less than the pressure P 3 , the filter device 32, the connection 30 and the connecting line 12 are sucked in air via the connection 40 and transferred into the tank 14. This possibly entrained filter material from the activated carbon 36 is not a problem, since the tank 14 is sealed pressure-tight.

Soll eine Reinigung der Filtereinrichtung 32 erfolgen, öffnet das Tankentlüftungsventil 26 entsprechend dem Tastverhältnis des Ansteuersignals 28. Dadurch liegt der Druck P2 am Tank 14 und an der Filtereinrichtung 32 an. Da im Saugrohr 20 ein Unterdruck herrscht, ist der Druck P2 geringer als der Druck P1 und der Druck P3. Durch dieses Druckgefälle werden die Kraftstoffdämpfe aus dem Tank 14 und die in der Aktivkohle 36 gespeicherten Kraftstoffdämpfe über das geöffnete Tankentlüftungsventil 26 angesaugt und der Verbrennungsluft der Verbrennungskraftmaschine 18 zugeführt. Diese verbrennen somit während des Verbrennungsprozesses.If a cleaning of the filter device 32 take place, the tank venting valve 26 opens according to the duty ratio of the drive signal 28. As a result, the pressure P 2 is applied to the tank 14 and to the filter device 32. Since a negative pressure prevails in the intake manifold 20, the pressure P 2 is less than the pressure P 1 and the pressure P 3 . As a result of this pressure gradient, the fuel vapors from the tank 14 and the fuel vapors stored in the activated carbon 36 are sucked in via the opened tank-venting valve 26 and supplied to the combustion air of the internal combustion engine 18. These thus burn during the combustion process.

Um eine sichere Entlüftung des Tanks 14 und Reinigung der Filtereinrichtung 32 zu gewährleisten, muß die Funktion des Tankentlüftungsventils 26 überprüft werden. Mögliche Fehler des Tankentlüftungsventils 26 könnten-beispielsweise ein klemmendes Ventilglied sein, so daß das Tankentlüftungsventil 26 entweder nicht mehr öffnet oder nicht mehr schließt. Ferner könnten Verschmutzungen in der Verbindungsleitung 12 abgelagert sein, die zu Querschnittsverengungen führen und somit die Funktion beeinträchtigen. Darüber hinaus ist bekannt, die Verbindungsleitung 12 als flexible Leitung (Schlauch) auszubilden, so daß eventuelle Abknickungen oder dergleichen ebenfalls zu Querschnittsverengungen führen könnten.To a safe venting of the tank 14 and cleaning of the filter device 32 to ensure the function of the tank vent valve 26 must be checked. Possible errors of the tank venting valve 26 could, for example, a clamping Be valve member, so that the tank vent valve 26 either no longer opens or no longer closes. Furthermore, dirt could in the connecting line 12th be deposited, which lead to cross-sectional constrictions and thus the function affect. In addition, it is known that the connecting line 12 as flexible Form line (hose) so that any kinks or the like could also lead to cross-sectional constrictions.

Anhand von Figur 2 wird das erfindungsgemäße Verfahren zum Prüfen des Tankentlüftungssystems 10 erläutert. Bei einem Start 50 des Kraftfahrzeugs, beispielsweise durch Betätigen der Zündung, wird das Prüfungsverfahren initialisiert (Feld 52). Anschließend wird über eine Abfrage 54 geprüft, ob Freigabebedingungen 56 für das Prüfverfahren gegeben sind. Diese Freigabebedingungen 56 beinhalten beispielsweise parallel ablaufende Steuerungsvorgänge oder parallel ablaufende Diagnoseverfahren anderer Einrichtungen des Kraftfahrzeugs, die durch das Prüfungsverfahren 48 beeinflußt werden könnten. Die Freigabeprüfung 56 beinhaltet beispielsweise die Abfrage 58 über den momentanen Saugdruck P2 entsprechend dem Meßergebnis 44. Beispielsweise werden Differenzen zwischen einem maximalen und einem minimalen Saugdruck ausgewertet. Ist diese Differenz oberhalb einer vorgebbaren Differenz, ist der Saugrohrdruck P2 nicht stabil, so daß über das Signal 60 die Freigabe 56 für das Verfahren nicht erteilt wird. Ist die Differenz jedoch innerhalb eines vorgebbaren Bereiches, kann das eigentliche Prüfverfahren, die Kreuzkorrelation 62, erfolgen. Hierbei wird ein Stimulationssignal 64 zugeführt, das dem Tastverhältnis des Ansteuersignals 28 entspricht. Hierbei kann beispielsweise ein Stimulationssignal +1 für angesteuertes Tankentlüftungsventil 26 und von -1 für nicht angesteuertes Tankentlüftungsventil 26 geliefert werden. Nach Durchführung der Kreuzkorrelation wird mittels eines Signals 66 eine Wiederholungsprüfung 68 ausgelöst. Hierbei wird die Anzahl der durchgeführten Meßzyklen mit einer vorgebbaren Anzahl verglichen. Ist die Anzahl der durchgeführten Meßzyklen kleiner als die vorgegebene Zahl, wird über das Signal 70 die Wiederholungsprüfung ausgelöst. Ist die Anzahl der durchgeführten Meßzyklen gleich der vorgegebenen Anzahl, wird über das Signal 72 die Diagnose 74 durchgeführt. Bei der Diagnose 74 wird ein Korrelationskoeffizient der durchgeführten Korrelationsrechnung 62 überprüft. Weist dieser Korrelationskoeffizient einen Wert von 1 auf, sind das Ansteuersignal 28 und die Meßgröße 44 (Saugrohrdruck) im Sinne der Korrelationsrechnung identisch. Weist der Korrelationseffizient hingegen einen Wert von 0 auf, besteht kein Zusammenhang zwischen dem Abtastsignal 28 und der Meßgröße 44, so daß auf einen Fehler 76 erkannt wird. Bei Erkennen des Fehlers 76 kann beispielsweise einem Fahrzeugführer durch ein optisches Signal eine Information gegeben werden, daß das Tankentlüftungssystem 10 fehlerhaft ist.The method according to the invention for testing the tank ventilation system 10 will be explained with reference to FIG. At a start 50 of the motor vehicle, for example by actuating the ignition, the test procedure is initialized (field 52). Subsequently, it is checked via a query 54 whether release conditions 56 are given for the test method. These release conditions 56 include, for example, parallel-running control actions or parallel-running diagnostic procedures of other devices of the motor vehicle that could be affected by the test method 48. The release check 56 includes, for example, the query 58 about the current suction pressure P 2 according to the measurement result 44. For example, differences between a maximum and a minimum suction pressure are evaluated. If this difference is above a predefinable difference, the intake pipe pressure P 2 is not stable, so that the release 60 for the method is not issued via the signal 60. However, if the difference is within a predefinable range, the actual test method, the cross-correlation 62, can take place. Here, a stimulation signal 64 is supplied, which corresponds to the duty cycle of the drive signal 28. In this case, for example, a stimulation signal +1 for actuated tank venting valve 26 and of -1 for not activated tank venting valve 26 can be supplied. After carrying out the cross-correlation, a repeat check 68 is triggered by means of a signal 66. Here, the number of measuring cycles performed is compared with a predetermined number. If the number of measuring cycles carried out is less than the predetermined number, the repeat check is triggered via the signal 70. If the number of measuring cycles carried out is equal to the predetermined number, the diagnosis 74 is carried out via the signal 72. In the diagnosis 74, a correlation coefficient of the correlation calculation 62 performed is checked. If this correlation coefficient has a value of 1, the drive signal 28 and the measured variable 44 (intake manifold pressure) are identical in the sense of the correlation calculation. If, on the other hand, the correlation coefficient has a value of 0, there is no correlation between the sampling signal 28 and the measured variable 44, so that an error 76 is detected. Upon detection of the error 76, for example, a driver can be given an information by an optical signal that the tank ventilation system 10 is faulty.

Ein Abbruch 78 des Verfahrens findet beispielsweise statt, wenn über die Prüfung der Freigabebedingung 56 ein Signal 80 generiert wird, das das Nichtvorhandensein der definierten Freigabebedingungen beinhaltet. Ferner kann während der Stimulation des Ansteuersignals 28 beziehungsweise während der Erfassung der Meßgröße 44 ein Signal 82 generiert werden, das ebenfalls zum Abbruch 78 führt. Das Signal 82 kann beispielsweise ein Fehlersignal sein, bei fehlender oder unplausibler Meßgröße 44, Ablauf einer vorgesehenen Gesamtstandzeit des Tankentlüftungsventils 26 und/oder bei Erreichen der vorgegebenen Anzahl der durchzuführenden Meßzyklen während der Wiederholungsprüfung 68. Nach Abbruch des Prüfverfahrens 48 kann beispielsweise ein Timer gestartet werden, der das Prüfverfahren 48 durch Neuinitialisierung 52 wieder startet. Gegebenenfalls kann vorgesehen sein, daß das Prüfverfahren 48 mit jedem Neustart der Brennkraft der Verbrennungskraftmaschine 18 abläuft.An abort 78 of the process takes place, for example, when the examination of the Release condition 56 a signal 80 is generated, which is the absence of the defined release conditions includes. Furthermore, during stimulation of the Control signal 28 or during the detection of the measured variable 44 a Signal 82 are generated, which also leads to abort 78. The signal 82 can be an error signal, for example, if the measured variable 44 is missing or implausible, Expiration of a planned total service life of the tank venting valve 26 and / or at Reaching the predetermined number of measuring cycles to be performed during the Repeat test 68. After termination of the test method 48, for example, a Timers are started, the test method 48 by reinitialization 52 again starts. Optionally, it may be provided that the test method 48 with each Restart of the internal combustion engine 18 is running.

Nach einem weiteren Ausführungsbeispiel kann anstelle des Saugrohrdrucks P2 als Meßgröße 44 auch eine andere Meßgröße, beispielsweise die Stellung der Drosselklappe 24, für die Kreuzkorrelation herangezogen werden. Hierbei ist ein Signal, beispielsweise über ein Potentiometer, abgreifbar, das der Stellung der Drosselklappe 24 entspricht. According to a further embodiment, instead of the intake manifold pressure P 2 as a measured variable 44 and a different measured variable, for example, the position of the throttle valve 24, are used for the cross-correlation. Here, a signal, for example via a potentiometer, can be tapped, which corresponds to the position of the throttle valve 24.

Die Kreuzkorrelation kann passiv oder aktiv durchgeführt werden. Bei der passiven Kreuzkorrelation werden die auszuwertenden Signale, hier das Ansteuersignal 28 und die Meßgröße 44, unbeeinflußt verarbeitet. Bei der aktiven Kreuzkorrelation werden die in die Kreuzkorrelation eingehenden Ansteuersignale 28 und Meßgröße 44 mit Stimulationssignalen angeregt, so daß eine Empfindlichkeit des Prüfverfahrens 48 gesteigert werden kann.Cross-correlation can be passive or active. At the passive Cross correlation are the signals to be evaluated, here the drive signal 28 and the measurand 44, processed unaffected. In active cross correlation, the in the cross-correlation incoming control signals 28 and 44 measured Stimulation signals stimulated, so that a sensitivity of the test method 48 can be increased.

Claims (7)

  1. Method for testing a tank venting system (10), in particular of a motor vehicle, in which hydrocarbon-containing volatile gases which escape from a tank (14) are conducted via a filter device (32) and collected in it and the filtered material (36) is fed via a suction system (16) for a combustion process in an internal combustion engine (18) of the motor vehicle by applying a portable vacuum to the filter device (32), a connection between the filter device (32) and the suction system (16) being opened or closed by switching means (26) which can be actuated in a clocked fashion, characterized in that an actuation signal (28) for the switching means is cross-correlated with a measurement variable which defines a state of the suction system (16), and a correlation coefficient is evaluated as a diagnostic signal of the tank venting system (10).
  2. Method according to Claim 1, characterized in that an intake manifold pressure is used as the measurement variable.
  3. Method according to Claim 1, characterized in that a position of a throttle valve (24) of the suction system is evaluated as the measurement variable.
  4. Method according to one of the preceding claims, characterized in that the cross-correlation is repeated for a predefinable number of measurement cycles.
  5. Method according to one of the preceding claims, characterized in that the testing of the tank venting system (10) is repeated at predefinable time intervals.
  6. Method according to one of the preceding claims, characterized in that the testing of the tank venting system (10) is repeated whenever the internal combustion engine is restarted.
  7. Method according to one of the preceding claims, characterized in that enabling conditions for the test method are checked before the cross-correlation is carried out.
EP99123162A 1998-12-23 1999-11-22 Method for testing a tank purge system Expired - Lifetime EP1013917B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19860750 1998-12-23
DE19860750 1998-12-23
DE19908138A DE19908138B4 (en) 1998-12-23 1999-02-25 Method for testing a tank ventilation system
DE19908138 1999-02-25

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EP1013917A2 EP1013917A2 (en) 2000-06-28
EP1013917A3 EP1013917A3 (en) 2000-11-22
EP1013917B1 true EP1013917B1 (en) 2004-02-18

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AT (1) ATE259935T1 (en)
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Publication number Priority date Publication date Assignee Title
DE10038444B4 (en) 2000-08-07 2014-07-31 Volkswagen Ag Method for checking a fuel injection system
DE10150420A1 (en) * 2001-10-11 2003-04-30 Bosch Gmbh Robert Method for checking the functionality of a tank ventilation valve of a tank ventilation system
ITBO20120538A1 (en) * 2012-10-02 2014-04-03 Magneti Marelli Spa FUNCTIONAL DIAGNOSIS OF A CANISTER SOLENOID VALVE IN AN INTEGRATED CIRCUIT FOR AN INTERNAL COMBUSTION ENGINE
FR3027956B1 (en) * 2014-10-31 2016-11-04 Renault Sa METHOD FOR DIAGNOSING THE OPERATION OF THE PURGE OF A CANISTER

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140961A (en) * 1990-01-12 1992-08-25 Nissan Motor Co., Ltd. System and method for self diagnosing an engine control system
DE4122975A1 (en) * 1991-07-11 1993-01-14 Bosch Gmbh Robert TANK VENTILATION SYSTEM FOR A MOTOR VEHICLE AND METHOD AND DEVICE FOR CHECKING THEIR FUNCTIONALITY
US5696317A (en) * 1996-09-11 1997-12-09 Ford Global Technologies, Inc. Method for controlling rate of purging of evaporative fuel vapors

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ES2214799T3 (en) 2004-09-16
EP1013917A3 (en) 2000-11-22
ATE259935T1 (en) 2004-03-15

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