WO1996027080A1 - Method for diagnosing motor vehicle fuel vapour recovery system operation - Google Patents

Method for diagnosing motor vehicle fuel vapour recovery system operation Download PDF

Info

Publication number
WO1996027080A1
WO1996027080A1 PCT/EP1996/000642 EP9600642W WO9627080A1 WO 1996027080 A1 WO1996027080 A1 WO 1996027080A1 EP 9600642 W EP9600642 W EP 9600642W WO 9627080 A1 WO9627080 A1 WO 9627080A1
Authority
WO
WIPO (PCT)
Prior art keywords
time
pump
membrane
determined
return
Prior art date
Application number
PCT/EP1996/000642
Other languages
French (fr)
Inventor
Dominique Salafia
Original Assignee
Siemens Automotive S.A.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens Automotive S.A. filed Critical Siemens Automotive S.A.
Publication of WO1996027080A1 publication Critical patent/WO1996027080A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/08—Safety, indicating, or supervising devices
    • 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
    • F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/08—Engine-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
    • F02M25/0809—Judging failure of purge control system
    • F02M25/0818—Judging failure of purge control system having means for pressurising the evaporative emission space

Definitions

  • the present invention relates to a method for diagnosing a system for recovering fuel vapors, more particularly making it possible to verify the correct operation of a venting valve for this system.
  • FIG. 1 Such a device, known for example from patent application WO 94/15090, has been represented in FIG. 1. It comprises a fuel tank 1, the vapors of which are collected and directed towards a filter 2 filled with activated carbon which retains hydrocarbons. Under certain operating conditions, the filter 2 is purged under the action of a current of gas sucked in by the vacuum which prevails in the intake manifold 4 of the engine and regulated by a purge valve 3 controlled by an electronic computer 5 The venting of the vapor circuit formed by the tank, the filter and their associated pipes is effected from the filter by means of a pipe 16, a venting valve 15 and an orifice 17 forming part of a pump 10.
  • This pump comprises a diaphragm 11 pressed in the rest position by a spring 14. In this position, the diaphragm maintains in the open position a valve 15 which connects the pipe 16 connected to the filter and the orifice 17 open to the air .
  • the pump 10 comprises means 13, for example a solenoid valve controlled by the computer 5, which make it possible to selectively put in communication an upper chamber delimited by the membrane and the upper part of the pump body with the vacuum prevailing in the manifold. admission 4. When this communication is established, the membrane is raised, compressing the spring 14, thereby releasing the valve 15 which closes under the effect of a spring.
  • the outside air from orifice 17 is then admitted into a lower chamber delimited by the membrane and the lower part of the pump body.
  • the computer 5 controls the switching of the means 13 which bring the upper chamber to atmospheric pressure.
  • the membrane is then pushed back to its rest position by the spring 14, expelling the air from the lower chamber towards the pipe 16.
  • the pump 10 also comprises means 12, for example a switch actuated by a diaphragm guide piece, connected to the computer 5 to generate a signal representative of a determined position of the diaphragm, before the latter reaches its rest position and opens the valve 15.
  • the computer can therefore, when it receives this signal, control the action of the means 13 to raise the membrane and start a pumping cycle.
  • the computer 5 is programmed to close the purge valve 3 and cause the pump 10 to execute a number determined pumping cycles to establish a su ⁇ ression in the circuit. By measuring the time taken by the membrane at the end of these cycles, to return from its high position to the position determined by the means 12, it is thus possible to deduce the existence of leaks in the circuit.
  • the object of the present invention is therefore to propose a method for diagnosing a system for recovering fuel vapors making it possible to verify the proper functioning of the venting valve of the system.
  • a method for diagnosing a fuel vapor recovery system of the type using a membrane pump.
  • said pump comprising in particular means for generating a signal representative of a determined position of the membrane, and a valve for venting the system, normally open when the pump is at rest and closed when activated
  • the said method notably consisting in activating the pump for a determined period in order to establish a pressure in the system, measuring the time taken by the membrane to return to the determined position and deducing therefrom the existence of possible leaks in the system, process characterized in that the operation of the system's venting valve is diagnosed by activating the pump for a first series of pumping cycles in order to establish a first pressure in the system, measuring a first time taken by the membrane to return to the determined position after the establishment of the first pressure, deactivating the pump for a determined period, reactivating the pump during at least one pumping
  • the number of pumping cycles of the first series is determined according to the parameters of the pump (membrane surface and spring) so that the pressure reached at the end of the following pumping cycle allows the membrane to return to its rest position.
  • the duration of deactivation of the pump is determined so that it is greater than the minimum duration necessary allowing the membrane to return to its rest position.
  • two pumping cycles are executed at the end of the deactivation time, and the second time is measured during the second cycle.
  • the first time is also compared with a range of predetermined values and it is concluded that the recovery system has failed if this first time does not belong to said range.
  • FIG. 1 represents the system for recovering fuel vapors described in the preamble
  • FIG. 2 in which the temporal evolution of the pressure in the circuit during the course of the process according to the invention has been represented on curve (a) and on the curve (b) the displacements of the membrane 11 with the same time scale.
  • the computer 5 Prior to the execution of the process, the computer 5 controls the closing of the purge valve 3, thus isolating the vapor circuit from the vacuum existing in the intake manifold 4.
  • the pump 10 being at rest, the valve 15 of venting is open and atmospheric pressure PO prevails in the circuit.
  • the computer controls a first series of ni pumping cycles. As can be seen on curve 2b, where the position of the membrane is indicated on the ordinate, the membrane passes from its rest position denoted R to its upper limit position denoted H in a very short time (neglected in the representation), then descends under the effect of the spring 14 to the determined position (denoted S) at which the switch 12 changes state.
  • the computer 5 receives the signal from the switch 12 and acts on the solenoid valve 13 to restart a pumping cycle.
  • the valve 15 having closed as soon as the membrane has left its rest position, the pressure in the circuit, shown on the ordinate on curve 2a, increases under the effect of the volume of air expelled by the membrane during its descent. It will be noted that the time taken by the membrane to pass from the position H to the position S depends on the pressure prevailing in the circuit and therefore serves as an indirect measurement thereof.
  • the computer 5 controls the next cycle and measures the time TM1 taken by the membrane to pass from position H to position S which is reached at time L2.
  • the number ni of pumping cycles of the first series has been determined so that the product of the surface of the membrane by the pressure P2 reached in a standard circuit in working order after the n1 + 1 th cycle is less than the force developed by the spring when the latter presses the membrane in its rest position. This ensures that the membrane can return to its rest position at the end of the n1 + 1 th cycle.
  • the computer does not control the next pumping cycle, but triggers the counting of a waiting time TA during which the pump will be deactivated.
  • This deactivation time TA is determined so as to be greater than the time necessary for the membrane to reach its rest position R under the pressure conditions P2 mentioned above.
  • the membrane At time t3, prior to the end of this deactivation period, the membrane returns to its rest position, which normally causes the valve 15 to open. If the circuit venting valve 15 opens , the pressure in the circuit drops from P2 to atmospheric pressure PO, which is shown in solid lines on curve 2a. If for any reason the valve 15 is blocked in closing, the pressure in the circuit remains at level P2, which is shown in dotted lines on the curve.
  • the deactivation time TA of the pump is finished, and the computer 5 commands a new series of n2 pumping cycles, with n2 ⁇ ni.
  • n2 2 which has certain advantages which will be described later.
  • the computer measures the time taken by the membrane to reach position S.
  • this time TM2 measured between times t5 and t6 is representative of a pressure lower than the pressure P2 during the measurement of TM1 and is therefore less than TM1.
  • the pressure in the vapor circuit has remained close to the pressure P2 until time t4 and then increased under the effect of the two pumping cycles.
  • the time TM2 " measured between the instants t5 'and t6', is representative of a higher pressure than the pressure P2 during the measurement of TM1 and is therefore greater than TM1. It can therefore be concluded, if the second time measured is less than the first that the valve 15 for venting the vapor circuit works properly.
  • TM1 of descent of the membrane which serves as a reference. range of acceptable values defined by minimum and maximum thresholds. If the time TM1 is less than a predetermined minimum threshold, for example by experimentation, it can be concluded that the vapor circuit has a leak coarse or that valve 15 has not closed. Conversely, if the time TM1 is greater than a maximum threshold, it may be indicative of a circuit anomaly, such as an obstructed pipe for example. In both cases, the diagnostic procedure can be completed, a fault in the integrity of the fuel vapor recovery system can be concluded and the appropriate actions can be taken, such as lighting an alarm light on the vehicle dashboard.

Landscapes

  • 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)

Abstract

A method for diagnosing a fuel vapour recovery system using a pump (10) with a membrane (11) particularly including means (12) for generating a signal indicating a predetermined position of the membrane, and a system venting valve (15) that is normally open when the pump is inoperative and closed when it is operative. According to the method, the operation of the valve is diagnosed by comparing a first time (TM1) taken by the membrane to return to the predetermined position after a first series of pumping cycles with a second time (TM2; TM2') taken by the membrane to return to the predetermined position after a second pumping cycle once the pump has been inoperative for a predetermined time (TA).

Description

Procédé de diagnostic du fonctionnement d'un système de récupération des vapeurs de carburant d'un véhicule automobile Method for diagnosing the operation of a system for recovering fuel vapors from a motor vehicle
La présente invention est relative à un procédé de diagnostic d'un système de récupération des vapeurs de carburant, permettant plus particulièrement de vérifier le bon fonctionnement d'une soupape de mise à l'atmosphère de ce système.The present invention relates to a method for diagnosing a system for recovering fuel vapors, more particularly making it possible to verify the correct operation of a venting valve for this system.
Les réglementations actuelles et futures imposent aux véhicules à essence d'être munis de dispositifs permettant de limiter la pollution atmosphérique par des vapeurs d'hydrocarbures. Ces dispositifs, dont on a représenté un exemple à la figure 1, doivent également être capables d'exécuter un diagnostic de leur fonctionnement afin d'alerter le conducteur en cas de défaillance. En particulier, ils doivent pouvoir détecter une fuite dans le circuit occupé par des vapeurs de carburant, ainsi que le bon fonctionnement de tous les éléments qui le composent.Current and future regulations require petrol vehicles to be fitted with devices to limit atmospheric pollution from hydrocarbon vapors. These devices, an example of which is shown in FIG. 1, must also be capable of carrying out a diagnostic of their operation in order to alert the driver in the event of a failure. In particular, they must be able to detect a leak in the circuit occupied by fuel vapors, as well as the proper functioning of all the elements that compose it.
Un tel dispositif, connu par exemple de la demande de brevet WO 94/15090, a été représenté à la figure 1. Il comporte un réservoir de carburant 1, dont les vapeurs sont collectées et dirigées vers un filtre 2 rempli de charbon actif qui retient les hydrocarbures. Dans certaines conditions de fonctionnement, le filtre 2 est purgé sous l'action d'un courant de gaz aspiré par la dépression qui règne dans le collecteur d'admission 4 du moteur et réglé par une vanne de purge 3 commandée par un calculateur électronique 5. La mise à l'atmosphère du circuit de vapeurs constitué par le réservoir, le filtre et leurs conduites associées est effectuée à partir du filtre par l'intermédiaire d'une conduite 16, d'une soupape de mise à l'atmosphère 15 et d'un orifice 17 formant partie d'une pompe 10. On va maintenant décrire succinctement le fonctionnement de cette pompe 10 qui est par ailleurs détaillé dans la demande de brevet précitée. Cette pompe comporte une membrane 11 pressée en position de repos par un ressort 14. Dans cette position, la membrane maintient en position ouverte une soupape 15 qui met en communication la conduite 16 reliée au filtre et l'orifice 17 ouvert à l'air libre. La pompe 10 comporte des moyens 13, par exemple une électrovanne commandée par le calculateur 5, qui permettent de mettre sélectivement en communication une chambre supérieure délimitée par la membrane et la partie supérieure du corps de la pompe avec la dépression régnant dans le collecteur d'admission 4. Lorsque cette communication est établie, la membrane est soulevée, comprimant le ressort 14, libérant ainsi la soupape 15 qui se ferme sous l'effet d'un ressort. L'air extérieur en provenance de l'orifice 17 est alors admis dans une chambre inférieure délimitée par la membrane et la partie inférieure du corps de la pompe. Après un délai suffisant pour s'assurer que la membrane a atteint sa position limite supérieure, le calculateur 5 commande la commutation des moyens 13 qui mettent la chambre supérieure à la pression atmosphérique. La membrane est alors repoussée vers sa position de repos par le ressort 14, expulsant l'air de la chambre inférieure vers la conduite 16. La pompe 10 comprend encore des moyens 12, par exemple un interrupteur actionné par une pièce de guidage de la membrane, reliés au calculateur 5 pour générer un signal représentatif d'une position déterminée de la membrane, avant que celle-ci n'atteigne sa position de repos et n'ouvre la soupape 15. Le calculateur peut donc, lorsqu'il reçoit ce signal, commander l'action des moyens 13 pour faire remonter la membrane et recommencer un cycle de pompage. On comprend alors qu'afin de vérifier l'étanchéité du circuit de vapeurs constitué par le réservoir 1 , le filtre 2 et leurs conduites associées, le calculateur 5 est programmé pour fermer la vanne de purge 3 et faire exécuter à la pompe 10 un nombre déterminé de cycles de pompage pour établir une suφression dans le circuit. En mesurant le temps mis par la membrane à l'issue de ces cycles, pour revenir de sa position haute jusqu'à la position déterminée par les moyens 12, on peut ainsi déduire l'existence de fuites dans le circuit.Such a device, known for example from patent application WO 94/15090, has been represented in FIG. 1. It comprises a fuel tank 1, the vapors of which are collected and directed towards a filter 2 filled with activated carbon which retains hydrocarbons. Under certain operating conditions, the filter 2 is purged under the action of a current of gas sucked in by the vacuum which prevails in the intake manifold 4 of the engine and regulated by a purge valve 3 controlled by an electronic computer 5 The venting of the vapor circuit formed by the tank, the filter and their associated pipes is effected from the filter by means of a pipe 16, a venting valve 15 and an orifice 17 forming part of a pump 10. We will now briefly describe the operation of this pump 10 which is further detailed in the aforementioned patent application. This pump comprises a diaphragm 11 pressed in the rest position by a spring 14. In this position, the diaphragm maintains in the open position a valve 15 which connects the pipe 16 connected to the filter and the orifice 17 open to the air . The pump 10 comprises means 13, for example a solenoid valve controlled by the computer 5, which make it possible to selectively put in communication an upper chamber delimited by the membrane and the upper part of the pump body with the vacuum prevailing in the manifold. admission 4. When this communication is established, the membrane is raised, compressing the spring 14, thereby releasing the valve 15 which closes under the effect of a spring. The outside air from orifice 17 is then admitted into a lower chamber delimited by the membrane and the lower part of the pump body. After a sufficient time to ensure that the membrane has reached its upper limit position, the computer 5 controls the switching of the means 13 which bring the upper chamber to atmospheric pressure. The membrane is then pushed back to its rest position by the spring 14, expelling the air from the lower chamber towards the pipe 16. The pump 10 also comprises means 12, for example a switch actuated by a diaphragm guide piece, connected to the computer 5 to generate a signal representative of a determined position of the diaphragm, before the latter reaches its rest position and opens the valve 15. The computer can therefore, when it receives this signal, control the action of the means 13 to raise the membrane and start a pumping cycle. It is then understood that in order to check the tightness of the vapor circuit formed by the tank 1, the filter 2 and their associated pipes, the computer 5 is programmed to close the purge valve 3 and cause the pump 10 to execute a number determined pumping cycles to establish a suφression in the circuit. By measuring the time taken by the membrane at the end of these cycles, to return from its high position to the position determined by the means 12, it is thus possible to deduce the existence of leaks in the circuit.
Cependant, comme on l'a noté plus haut, il apparaît nécessaire de diagnostiquer également le bon fonctionnement de tous les éléments du système, et en particulier de la soupape 15. En effet, si celle-ci reste bloquée en fermeture, cela peut engendrer soit une suφression dans le circuit lorsque, le véhicule étant à l'arrêt, des vapeurs de carburant sont générées dans le réservoir sous l'action de la température, soit encore une dépression lorsqu'en fonctionnement normal, la vanne de purge 3 est ouverte.However, as noted above, it appears necessary to also diagnose the proper functioning of all the elements of the system, and in particular of the valve 15. In fact, if the latter remains blocked in closing, this can cause either an increase in the circuit when, with the vehicle stationary, fuel vapors are generated in the tank under the action of temperature, or even a vacuum when in normal operation, the purge valve 3 is open .
La présente invention a donc pour but de proposer un procédé de diagnostic d'un système de récupération des vapeurs de carburant permettant de vérifier le bon fonctionnement de la soupape de mise à l'atmosphère du système.The object of the present invention is therefore to propose a method for diagnosing a system for recovering fuel vapors making it possible to verify the proper functioning of the venting valve of the system.
On atteint ces buts de l'invention, ainsi que d'autres qui apparaîtront dans la suite de la présente description, au moyen d'un procédé de diagnostic d'un système de récupération de vapeurs de carburant, du type utilisant une pompe à membrane pour établir une suφression dans le système, ladite pompe comprenant notamment des moyens pour générer un signal représentatif d'une position déterminée de la membrane, et une soupape de mise à l'atmosphère du système, normalement ouverte quand la pompe est au repos et fermée lorsqu'elle est activée, ledit procédé consistant notamment à activer la pompe pendant une durée déterminée afin d'établir une suφression dans le système, mesurer le temps mis par la membrane pour revenir à la position déterminée et en déduire l'existence d'éventuelles fuites dans le système, procédé caractérisé en ce que l'on diagnostique le fonctionnement de la soupape de mise à l'atmosphère du système en activant la pompe pendant une première série de cycles de pompage afin d'établir dans le système une première pression, mesurant un premier temps mis par la membrane pour revenir à la position déterminée après l'établissement de la première pression, désactivant la pompe pendant une durée déterminée, réactivant la pompe pendant au moins un cycle de pompage, mesurant un deuxième temps mis par la membrane pour revenir à la position déterminée après ce cycle, et concluant au bon fonctionnement de la soupape de mise à l'atmosphère du système si le deuxième temps est inférieur au premier.These objects of the invention are achieved, as well as others which will appear in the remainder of the present description, by means of a method for diagnosing a fuel vapor recovery system, of the type using a membrane pump. to establish a suφression in the system, said pump comprising in particular means for generating a signal representative of a determined position of the membrane, and a valve for venting the system, normally open when the pump is at rest and closed when activated, the said method notably consisting in activating the pump for a determined period in order to establish a pressure in the system, measuring the time taken by the membrane to return to the determined position and deducing therefrom the existence of possible leaks in the system, process characterized in that the operation of the system's venting valve is diagnosed by activating the pump for a first series of pumping cycles in order to establish a first pressure in the system, measuring a first time taken by the membrane to return to the determined position after the establishment of the first pressure, deactivating the pump for a determined period, reactivating the pump during at least one pumping cycle, measuring a second time taken by the membrane to return to the position determined after this cycle, and concluding that the system venting valve is working properly if the second time is less than the first.
Suivant une caractéristique importante de la présente invention, le nombre de cycles de pompage de la première série est déterminé en fonction des paramètres de la pompe (surface de membrane et ressort) afin que la pression atteinte à l'issue du cycle de pompage suivant permette à la membrane de rejoindre sa position de repos.According to an important characteristic of the present invention, the number of pumping cycles of the first series is determined according to the parameters of the pump (membrane surface and spring) so that the pressure reached at the end of the following pumping cycle allows the membrane to return to its rest position.
Suivant une autre caractéristique de l'invention, on détermine la durée de désactivation de la pompe de sorte qu'elle soit supérieure à la durée minimale nécessaire permettant à la membrane de rejoindre sa position de repos. Suivant une autre caractéristique de l'invention, on exécute deux cycles de pompage à l'issue de la durée de désactivation, et on mesure le deuxième temps lors du second cycle.According to another characteristic of the invention, the duration of deactivation of the pump is determined so that it is greater than the minimum duration necessary allowing the membrane to return to its rest position. According to another characteristic of the invention, two pumping cycles are executed at the end of the deactivation time, and the second time is measured during the second cycle.
Suivant une autre caractéristique avantageuse de l'invention, on compare en outre le premier temps à une plage de valeurs prédéterminées et l'on conclut à une défaillance du système de récupération si ce premier temps n'appartient pas à ladite plage.According to another advantageous characteristic of the invention, the first time is also compared with a range of predetermined values and it is concluded that the recovery system has failed if this first time does not belong to said range.
D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description qui va suivre et à l'examen des dessins annexés dans lesquels: - la figure 1 représente le système de récupération des vapeurs de carburant décrit dans le préambule, etOther characteristics and advantages of the invention will appear on reading the description which follows and on examining the appended drawings in which: FIG. 1 represents the system for recovering fuel vapors described in the preamble, and
- la figure 2 représente des courbes temporelles de la pression dans le circuit et du déplacement de la membrane.- Figure 2 shows time curves of the pressure in the circuit and the displacement of the membrane.
On se réfère maintenant à la figure 2 où l'on a représenté sur la courbe (a) l'évolution temporelle de la pression dans le circuit pendant le déroulement du procédé selon l'invention et sur la courbe (b) les déplacements de la membrane 11 avec la même échelle de temps.Reference is now made to FIG. 2 in which the temporal evolution of the pressure in the circuit during the course of the process according to the invention has been represented on curve (a) and on the curve (b) the displacements of the membrane 11 with the same time scale.
Préalablement à l'exécution du procédé, le calculateur 5 commande la fermeture de la vanne de purge 3, isolant ainsi le circuit de vapeurs de la dépression existant dans le collecteur d'admission 4. La pompe 10 étant au repos, la soupape 15 de mise à l'atmosphère est ouverte et la pression atmosphérique PO règne dans le circuit. A l'instant t=0, le calculateur commande une première série de ni cycles de pompage. Comme on peut le voir sur la courbe 2b, où la position de la membrane est indiquée en ordonnée, la membrane passe de sa position de repos notée R à sa position limite supérieure notée H en un temps très bref (négligé dans la représentation), puis redescend sous l'effet du ressort 14 jusqu'à la position déterminée (notée S) à laquelle l'interrupteur 12 change d'état. Le calculateur 5 reçoit le signal de l'interrupteur 12 et agit sur l'électrovanne 13 pour recommencer un cycle de pompage. La soupape 15 s'étant fermée dès que la membrane a quitté sa position de repos, la pression dans le circuit, représentée en ordonnée sur la courbe 2a, augmente sous l'effet du volume d'air expulsé par la membrane lors de sa descente. On notera que le temps mis par la membrane pour passer de la position H à la position S dépend de la pression régnant dans le circuit et sert donc de mesure indirecte de celle-ci. Après le ni ième cycle, à l'instant t1, le calculateur 5 commande le cycle suivant et mesure le temps TM1 mis par la membrane pour passer de la position H à la position S qui est atteinte à l'instant L2.Prior to the execution of the process, the computer 5 controls the closing of the purge valve 3, thus isolating the vapor circuit from the vacuum existing in the intake manifold 4. The pump 10 being at rest, the valve 15 of venting is open and atmospheric pressure PO prevails in the circuit. At time t = 0, the computer controls a first series of ni pumping cycles. As can be seen on curve 2b, where the position of the membrane is indicated on the ordinate, the membrane passes from its rest position denoted R to its upper limit position denoted H in a very short time (neglected in the representation), then descends under the effect of the spring 14 to the determined position (denoted S) at which the switch 12 changes state. The computer 5 receives the signal from the switch 12 and acts on the solenoid valve 13 to restart a pumping cycle. The valve 15 having closed as soon as the membrane has left its rest position, the pressure in the circuit, shown on the ordinate on curve 2a, increases under the effect of the volume of air expelled by the membrane during its descent. It will be noted that the time taken by the membrane to pass from the position H to the position S depends on the pressure prevailing in the circuit and therefore serves as an indirect measurement thereof. After the n th cycle, at time t1, the computer 5 controls the next cycle and measures the time TM1 taken by the membrane to pass from position H to position S which is reached at time L2.
Avantageusement, le nombre ni de cycles de pompage de la première série a été déterminé de façon que le produit de la surface de la membrane par la pression P2 atteinte dans un circuit étalon en ordre de marche après le n1+1 ième cycle soit inférieur à l'effort développé par le ressort lorsque celui-ci plaque la membrane dans sa position de repos. Ceci permet de s'assurer que la membrane pourra rejoindre sa position de repos à l'issue du n1+1 ième cycle. A l'instant t2, le calculateur ne commande pas le cycle de pompage suivant, mais déclenche le comptage d'un temps d'attente TA pendant lequel la pompe sera désactivée. Cette durée de désactivation TA est déterminée de manière à être supérieure à la durée nécessaire à la membrane pour rejoindre sa position de repos R dans les conditions de pression P2 évoquées ci-dessus.Advantageously, the number ni of pumping cycles of the first series has been determined so that the product of the surface of the membrane by the pressure P2 reached in a standard circuit in working order after the n1 + 1 th cycle is less than the force developed by the spring when the latter presses the membrane in its rest position. This ensures that the membrane can return to its rest position at the end of the n1 + 1 th cycle. At time t2, the computer does not control the next pumping cycle, but triggers the counting of a waiting time TA during which the pump will be deactivated. This deactivation time TA is determined so as to be greater than the time necessary for the membrane to reach its rest position R under the pressure conditions P2 mentioned above.
A l'instant t3, antérieur à la fin de cette durée de désactivation, la membrane rejoint sa position de repos ce qui entraîne normalement l'ouverture de la soupape 15. Si la soupape 15 de mise à l'atmosphère du circuit s'ouvre, la pression dans le circuit chute de P2 à la pression atmosphérique PO, ce qui est représenté en trait plein sur la courbe 2a. Si pour une raison quelconque la soupape 15 est bloquée en fermeture, la pression dans le circuit reste au niveau P2, ce qui est représenté en trait pointillé sur la courbe.At time t3, prior to the end of this deactivation period, the membrane returns to its rest position, which normally causes the valve 15 to open. If the circuit venting valve 15 opens , the pressure in the circuit drops from P2 to atmospheric pressure PO, which is shown in solid lines on curve 2a. If for any reason the valve 15 is blocked in closing, the pressure in the circuit remains at level P2, which is shown in dotted lines on the curve.
A l'instant t4, la durée de désactivation TA de la pompe est terminée, et le calculateur 5 commande une nouvelle série de n2 cycles de pompage, avec n2 < ni. Dans l'exemple représenté, on a choisi n2=2, ce qui présente certains avantages que l'on décrira par la suite. Lors du second cycle de cette série, le calculateur mesure le temps mis par la membrane pour rejoindre la position S.At time t4, the deactivation time TA of the pump is finished, and the computer 5 commands a new series of n2 pumping cycles, with n2 <ni. In the example shown, we chose n2 = 2, which has certain advantages which will be described later. During the second cycle of this series, the computer measures the time taken by the membrane to reach position S.
Dans le cas où la soupape 15 s'est ouverte normalement, la pression dans le circuit de vapeurs étant revenue à la pression atmosphérique PO, ce temps TM2, mesuré entre les instants t5 et t6, est représentatif d'une pression plus faible que la pression P2 lors de la mesure de TM1 et est donc inférieur à TM1. Dans le cas où la soupape 15 est restée bloquée, la pression dans le circuit de vapeurs est restée voisine de la pression P2 jusqu'à l'instant t4 puis a augmenté sous l'effet des deux cycles de pompage. De ce fait, le temps TM2", mesuré entre les instants t5' et t6', est représentatif d'une pression plus forte que la pression P2 lors de la mesure de TM1 et est donc supérieur à TM1. On peut donc ainsi conclure, si le deuxième temps mesuré est inférieur au premier que la soupape 15 de mise à l'atmosphère du circuit de vapeurs fonctionne correctement.In the case where the valve 15 has opened normally, the pressure in the vapor circuit having returned to atmospheric pressure PO, this time TM2, measured between times t5 and t6, is representative of a pressure lower than the pressure P2 during the measurement of TM1 and is therefore less than TM1. In the case where the valve 15 has remained blocked, the pressure in the vapor circuit has remained close to the pressure P2 until time t4 and then increased under the effect of the two pumping cycles. As a result, the time TM2 ", measured between the instants t5 'and t6', is representative of a higher pressure than the pressure P2 during the measurement of TM1 and is therefore greater than TM1. It can therefore be concluded, if the second time measured is less than the first that the valve 15 for venting the vapor circuit works properly.
Le choix de deux cycles de pompage dans la deuxième série permet d'obtenir une plus grande sûreté de diagnostic, par rapport au cas minimum où un seul cycle de pompage et de mesure est effectué. En effet, même si la soupape 15 est bloquée, la pression dans le circuit peut avoir légèrement baissé si le circuit de vapeurs présente un léger défaut d'étanchéité, néanmoins acceptable. Si l'on exécute la mesure du deuxième temps T 2" lors du premier cycle qui suit la désactivation de la pompe, ce deuxième temps peut être très voisin ou légèrement au dessous du temps de référence TM1 et conduire à un diagnostic erroné. Cependant, si le volume d'air introduit par la pompe lors d'un cycle est important en regard des fuites acceptables, et/ou si le temps de désactivation TA est court, l'emploi d'un cycle unique donne des résultats satisfaisants et permet d'accélérer le diagnostic. On va décrire maintenant une étape optionnelle du procédé qui peut être avantageusement effectuée dès que l'on a mesuré le premier temps TM1 de descente de la membrane, qui sert de référence. On peut en effet comparer ce temps à une plage de valeurs acceptables définie par des seuils minimum et maximum. Si le temps TM1 est inférieur à un seuil minimum prédéterminé par exemple par expérimentation, on peut en conclure que le circuit de vapeurs comporte une fuite grossière ou que la soupape 15 ne s'est pas fermée. A l'inverse, si le temps TM1 est supérieur à un seuil maximum, ce peut être révélateur d'une anomalie du circuit, telle qu'une conduite obstruée par exemple. Dans les deux cas, on peut terminer la procédure de diagnostic, conclure à un défaut d'intégrité du système de récupération des vapeurs de carburant et prendre les actions appropriées, comme allumer un voyant d'alarme sur le tableau de bord du véhicule. The choice of two pumping cycles in the second series makes it possible to obtain greater diagnostic reliability, compared to the minimum case where a single pumping and measurement cycle is carried out. Indeed, even if the valve 15 is blocked, the pressure in the circuit may have dropped slightly if the vapor circuit has a slight, nevertheless acceptable, defect in sealing. If the measurement of the second time T 2 "is carried out during the first cycle following the deactivation of the pump, this second time may be very close to or slightly below the reference time TM1 and lead to an incorrect diagnosis. if the volume of air introduced by the pump during a cycle is large with regard to acceptable leaks, and / or if the deactivation time TA is short, the use of a single cycle gives satisfactory results and allows accelerate the diagnosis. We will now describe an optional step in the process which can be advantageously carried out as soon as the first time TM1 of descent of the membrane has been measured, which serves as a reference. range of acceptable values defined by minimum and maximum thresholds. If the time TM1 is less than a predetermined minimum threshold, for example by experimentation, it can be concluded that the vapor circuit has a leak coarse or that valve 15 has not closed. Conversely, if the time TM1 is greater than a maximum threshold, it may be indicative of a circuit anomaly, such as an obstructed pipe for example. In both cases, the diagnostic procedure can be completed, a fault in the integrity of the fuel vapor recovery system can be concluded and the appropriate actions can be taken, such as lighting an alarm light on the vehicle dashboard.

Claims

REVENDICATIONS
1. Procédé de diagnostic d'un système de récupération de vapeurs de carburant, du type utilisant une pompe (10) à membrane (11) pour établir une suφression dans un circuit de vapeurs (1 ;2), ladite pompe comprenant notamment : . des moyens (12) pour générer un signal représentatif d'une position déterminée de la membrane, et1. A method for diagnosing a fuel vapor recovery system, of the type using a diaphragm pump (10) (11) to establish a suφression in a vapor circuit (1; 2), said pump comprising in particular:. means (12) for generating a signal representative of a determined position of the membrane, and
• une soupape (15) de mise à l'atmosphère du système, normalement ouverte quand la pompe est au repos et fermée lorsqu'elle est activée, ledit procédé consistant notamment à• a valve (15) for venting the system, normally open when the pump is at rest and closed when it is activated, said method consisting in particular of
• activer la pompe pendant une durée déterminée afin d'établir une suφression dans le système,• activate the pump for a specific period of time to establish a suφression in the system,
• mesurer le temps mis par la membrane pour revenir à la position déterminée et en déduire l'existence d'éventuelles fuites dans le système, procédé caractérisé en ce que l'on diagnostique le fonctionnement de la soupape de mise à l'atmosphère du système en • activant la pompe pendant une première série (ni) de cycles de pompage afin d'établir dans le système une première pression (P1), . mesurant un premier temps (TMl) mis par la membrane pour revenir à la position déterminée après l'établissement de la première pression (P1),• measure the time taken by the membrane to return to the determined position and deduce therefrom the existence of possible leaks in the system, a process characterized in that the operation of the system's venting valve is diagnosed by • activating the pump during a first series (ni) of pumping cycles in order to establish in the system a first pressure (P1),. measuring a first time (TMl) taken by the membrane to return to the position determined after the establishment of the first pressure (P1),
• désactivant la pompe pendant une durée déterminée (TA) • réactivant la pompe pendant au moins un cycle de pompage,• deactivating the pump for a determined period (TA) • reactivating the pump for at least one pumping cycle,
• mesurant un deuxième temps (TM2; TM2') mis par la membrane pour revenir à la position déterminée après ce cycle,• measuring a second time (TM2; TM2 ') put by the membrane to return to the position determined after this cycle,
• concluant au bon fonctionnement de la soupape de mise à l'atmosphère du système si le deuxième temps est inférieur au premier. • concluding that the system venting valve is working properly if the second time is less than the first.
2. Procédé selon la revendication 1, caractérisé en ce que le nombre de cycles2. Method according to claim 1, characterized in that the number of cycles
(ni) de la première série est déterminé en fonction des paramètres de la pompe (surface de membrane et ressort) afin que la pression atteinte à l'issue du cycle de pompage suivant permette à la membrane de rejoindre sa position de repos.(ni) of the first series is determined according to the parameters of the pump (membrane surface and spring) so that the pressure reached at the end of the following pumping cycle allows the membrane to return to its rest position.
3. Procédé selon la revendication 2, caractérisé en ce que la durée (TA) de désactivation de la pompe est supérieure à la durée minimale nécessaire permettant à la membrane de rejoindre sa position de repos.3. Method according to claim 2, characterized in that the duration (TA) of deactivation of the pump is greater than the minimum duration necessary allowing the membrane to reach its rest position.
4. Procédé selon la revendication 1, caractérisé en ce que l'on exécute deux cycles de pompage à l'issue de la durée de désactivation, et en ce que l'on mesure le deuxième temps (TM2; T 2') lors du second cycle. 4. Method according to claim 1, characterized in that two pumping cycles are executed at the end of the deactivation time, and in that the second time (TM2; T 2 ') is measured during the second cycle.
5. Procédé selon la revendication 1, caractérisé en ce que, immédiatement après la mesure du premier temps (TM1), on le compare à une plage de valeurs prédéterminées et en ce que l'on conclut à une défaillance du système de récupération si ce premier temps n'appartient pas à ladite plage. 5. Method according to claim 1, characterized in that, immediately after the measurement of the first time (TM1), it is compared with a range of predetermined values and in that one concludes that the recovery system has failed if this first time does not belong to said range.
6. Procédé selon la revendication 5, caractérisé en ce que l'on arrête la procédure de diagnostic si la comparaison permet de conclure à une défaillance du système. 6. Method according to claim 5, characterized in that the diagnostic procedure is stopped if the comparison makes it possible to conclude that the system has failed.
PCT/EP1996/000642 1995-02-28 1996-02-14 Method for diagnosing motor vehicle fuel vapour recovery system operation WO1996027080A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9502459A FR2731047B1 (en) 1995-02-28 1995-02-28 METHOD FOR DIAGNOSING THE OPERATION OF A FUEL VAPOR RECOVERY SYSTEM OF A MOTOR VEHICLE
FR95/02459 1995-02-28

Publications (1)

Publication Number Publication Date
WO1996027080A1 true WO1996027080A1 (en) 1996-09-06

Family

ID=9476684

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1996/000642 WO1996027080A1 (en) 1995-02-28 1996-02-14 Method for diagnosing motor vehicle fuel vapour recovery system operation

Country Status (2)

Country Link
FR (1) FR2731047B1 (en)
WO (1) WO1996027080A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6253598B1 (en) * 1999-12-16 2001-07-03 Siemens Automotive Inc. Method and system for predicting stabilized time duration of vapor leak detection pump strokes
US6282945B1 (en) * 1999-12-16 2001-09-04 Siemens Automotive, Inc. Method and system for aggressive cycling of leak detection pump to ascertain vapor leak size

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992016734A2 (en) * 1991-03-22 1992-10-01 Robert Bosch Gmbh Process and device for tank ventilation
FR2681098A1 (en) * 1991-09-10 1993-03-12 Siemens Automotive Sa Method and device for checking the operational state of a system for collecting vapours coming from the fuel tank of a motor vehicle with internal-combustion engine
DE4132055A1 (en) * 1991-09-26 1993-04-01 Bosch Gmbh Robert METHOD AND DEVICE FOR TESTING THE FUNCTIONALITY OF A TANK BLEEDING SYSTEM
US5297529A (en) * 1993-01-27 1994-03-29 Siemens Automotive Limited Positive pressure canister purge system integrity confirmation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992016734A2 (en) * 1991-03-22 1992-10-01 Robert Bosch Gmbh Process and device for tank ventilation
FR2681098A1 (en) * 1991-09-10 1993-03-12 Siemens Automotive Sa Method and device for checking the operational state of a system for collecting vapours coming from the fuel tank of a motor vehicle with internal-combustion engine
DE4132055A1 (en) * 1991-09-26 1993-04-01 Bosch Gmbh Robert METHOD AND DEVICE FOR TESTING THE FUNCTIONALITY OF A TANK BLEEDING SYSTEM
US5297529A (en) * 1993-01-27 1994-03-29 Siemens Automotive Limited Positive pressure canister purge system integrity confirmation

Also Published As

Publication number Publication date
FR2731047A1 (en) 1996-08-30
FR2731047B1 (en) 1997-04-18

Similar Documents

Publication Publication Date Title
FR2670721A1 (en) METHOD AND INSTALLATION FOR OPERATING A DEVICE FOR DERATING A TANK, IN PARTICULAR A FUEL TANK OF A MOTOR VEHICLE.
WO2018002550A1 (en) Method for checking a pressure measurement in a fuel tank
FR2705626A1 (en) Tank degassing installation for a motor vehicle, as well as a process for its operation.
JP5976071B2 (en) Method and apparatus for detecting the open time of a selective catalytic reduction injector
JP2004156498A (en) Evaporated fuel treatment device of internal combustion engine
KR20190071330A (en) Canister purge system and method for diagnising purge valve thereof
FR2909714A1 (en) METHOD AND DEVICE FOR MANAGING TRAINING UNITS.
FR2734213A1 (en) METHOD FOR DIAGNOSING THE SEALING OF A TANK VENTILATION SYSTEM
FR2635823A1 (en) Device for checking the operating state of a system for recovering vapour coming off a motor vehicle petrol tank
FR2897105A1 (en) Internal combustion engine`s exhaust gas processing device diagnosing method for vehicle, involves measuring pressure of reactive agent between valves and between one of valves and injector
WO1996030641A1 (en) Method for sensing excess pressure in a motor vehicle fuel vapour recovery system
FR2881179A1 (en) METHOD FOR CONTROLLING A DEGASSING VALVE OF THE RESERVOIR OF A MOTOR VEHICLE DURING SEALING CHECK
FR2832758A1 (en) Diagnostic for state of exhaust system of internal combustion engine, uses measurement of pressure difference over particle filter to evaluate diagnostic at set stable engine operating points
WO1996027080A1 (en) Method for diagnosing motor vehicle fuel vapour recovery system operation
WO1996027738A1 (en) Method for diagnosing the operation of the drain valve of a fuel vapor recovery system for a motor vehicle
WO2011124358A1 (en) Method and device for detecting the blockage of a gasoline vapor filter bleed valve
FR2681098A1 (en) Method and device for checking the operational state of a system for collecting vapours coming from the fuel tank of a motor vehicle with internal-combustion engine
FR2817915A1 (en) System for controlling an IC engine fuel system and detecting leakage of fuel in the closed fuel system, used in common rail type direct fuel injection system for automotive vehicles
WO2017098126A1 (en) Method for controlling depressurisation in a motor vehicle fuel tank
EP3212920B1 (en) Diagnostic method of the ventilation operation of a canister
WO2016207556A1 (en) Method and computer for controlling the pressure inside a motor vehicle fuel tank
EP2142406B1 (en) Method for diagnosing brake pedal contactors
WO2007031669A1 (en) System and method for regenerating a catalytic particulate filter located in a diesel engine exhaust line
FR3035965A1 (en) DEVICE FOR DETECTING A LEAK POINT ON A RESERVOIR
FR3104672A3 (en) Process for filling a set of several pressurized gas storage facilities

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): KR US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase