EP0931928A1 - Device for avoiding cavitation in injection pumps - Google Patents

Device for avoiding cavitation in injection pumps Download PDF

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Publication number
EP0931928A1
EP0931928A1 EP99400183A EP99400183A EP0931928A1 EP 0931928 A1 EP0931928 A1 EP 0931928A1 EP 99400183 A EP99400183 A EP 99400183A EP 99400183 A EP99400183 A EP 99400183A EP 0931928 A1 EP0931928 A1 EP 0931928A1
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EP
European Patent Office
Prior art keywords
valve
return
pressure
fuel
injection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP99400183A
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German (de)
French (fr)
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EP0931928B1 (en
Inventor
Edmond Zych
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MAN Energy Solutions France SAS
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SEMT Pielstick SA
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    • 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
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
    • 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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/001—Pumps with means for preventing erosion on fuel discharge
    • 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
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/04—Fuel-injection apparatus having means for avoiding effect of cavitation, e.g. erosion
    • 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
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/40—Fuel-injection apparatus with fuel accumulators, e.g. a fuel injector having an integrated fuel accumulator

Definitions

  • the present invention relates to a device for eliminating cavitation in the excess fuel return port (s) in the compression chamber of a fuel injection pump of an internal combustion engine after the end of the injection phase.
  • This phase of the operation of the injection pump called “Discharge” causes sudden fuel evacuation excess at very high pressure and driven by a very high speed of circulation in return ports where the fuel already present is at low pressure. This leads to the interface of the evacuated fuel jet and fuel at low pressure, the appearance of bubbles due to degassing which, combined with the speed of circulation, cause erosion by cavitation of the wall of the return orifices, these erosions can cause destruction of the injection pump.
  • One of the means to eliminate this cavitation is to increase the pressure prevailing in the return ports of the injection pump at the time of discharge.
  • the invention proposes to remedy these drawbacks by providing a device intended to eliminate cavitation in the return port (s) of excess fuel in the compression chamber of a fuel injection pump of a combustion engine. internal after the end of the injection phase, said injection pump being connected, on the one hand, to a supply duct comprising a non-return valve with low pressure drop authorizing the arrival of the fuel in the compression chamber and, on the other hand, to a return line for excess fuel, characterized in that the return duct comprises in parallel and close to the return port of the injection pump a calibrated valve intended to cause the increase in pressure in said return port of the injection pump and a normally open one-way valve, the closure of which is caused by the appearance of a pressure in the return orifice, greater than that which prevails in the supply duct upstream of said non-return valve.
  • the one-way valve is provided with a spring causing the opening of said valve in the the pressure prevailing upstream of the non-return valve is substantially equal to the pressure in the return port.
  • the conduit return has a bypass accumulator and upstream of the valve calibrated and one-way valve.
  • Another object of the invention is the use of said device for implement fuel injection into a internal combustion.
  • the advantages of this device lie in less wear components of the injection pump, thus allowing the reduction maintenance frequency and minimizing the dispersion of metallic particles in the fuel.
  • FIG. 1 represents a diagram of the device according to the invention.
  • Figures 2, 3 and 4 show the injection pump piston at different stages of compression.
  • the Figure 5 shows the evolution of pressures in the return ports during the injection phases, curve A representing this development for a pump not fitted with the device according to the invention and the curve B representing the same evolution for a pump fitted with the device according to the invention.
  • a duct 2 provided with a non-return valve 3 connects a fuel circulation pump 1 supplied by a tank 9 to a fuel injection pump 4 partially represented by through a supply port 4a.
  • the pressure of delivery of pump 1 is limited by a calibrated valve la.
  • the conduit main return 5 and secondary conduits 5a and 5b connect in parallel the return port 4b of the injection pump 4 to a calibrated valve 6 and a one-way valve 7.
  • the one-way valve 7 is controlled at line 7a by the pressure in line 5b and at line 7b by the pressure prevailing in the duct 2 upstream of the calibrated valve 3.
  • a spring 7c reinforces the piloting action due to the line pressure 7b and keeps the valve 7 in the open position in the absence of a significant pressure difference between the two control lines.
  • the valve 7 implements a driving diaphragm a pressure drop intended to maintain a certain level of pressure fuel upstream of valve 7.
  • Ports 4a and 4b are put selectively in communication with the 4k compression chamber of the injection pump 4 via a peripheral groove 4c of the casing 4j and the orifices 4d and 4e of the piston liner 4f in function of the 4g piston movements including the edges delivery interruption 4h and 4i.
  • a low 8 accumulator volume is installed bypass on duct 5 immediately in downstream of the return port 4b.
  • the calibrated valve 6 and the valve 7 are connected to the tank 9 through conduits 5c and 5d.
  • piston 4g is in bottom dead center and releases the 4d and 4th ports to put them in communication with the 4k compression.
  • the piston 4g is substantially halfway and closes orifices 4d and 4e interrupting communication with the 4k compression chamber.
  • the piston 4g continued its stroke and the edges 4i and 4h clear the 4d and 4th orifices and put them in communication with the 4k compression chamber, via a 4m groove formed according to a generator on the side wall of the piston 4g.
  • the piston 4g is at the start of the compression stroke as shown in FIG. 2.
  • the valve 6 is calibrated at a pressure between 50 and 100 bars
  • the damper 8 has an inflation pressure slightly lower than the calibration of the valve 6 and , in the absence of a significant pressure difference between the conduits 7a and 7b, the valve 7 is kept open in position 7e by the spring 7c.
  • the diaphragm of the valve 7 in the 7th position provides a circulation pressure of the order of 3 bars.
  • the fuel supplied by the pump 1 circulates in the conduit 2 through the non-return valve 3, the orifice 4a, the compression chamber 4k, the orifice 4b, the valve 7 and returns to the tank 9 through the conduit 5d. This situation corresponds in Figure 5 to time T 0 of curve B.
  • the piston 4g continues its compression stroke and the high pressure in the pipe (not shown) connecting the compression chamber 4k to the injector (not shown) causes the closing of the non-return valve 3 and the fuel delivery by the port 4b.
  • the sudden increase in flow in the conduit 5b and the pressure drop in the valve 7 causes a significant increase in pressure in the conduits 5a and 7a, causing the piloting of the valve 7 which passes to position 7d.
  • the pressure continues to rise in the duct 5a until reaching the setting value of the valve 6 which begins to open.
  • the damper 8 fills and rises in pressure, thus reducing the water hammer on the valve 6. This situation corresponds in FIG. 5 to the evolution of the curve B in the vicinity of the point B 1 .
  • discharge corresponds to time T 1 and to pressure P 2 in FIG. 5.
  • This discharge causes a sudden transfer of fuel through the orifices 4d and 4e in the form of jets at very high speed, causing a rapid rise in pressure in the orifices 4d and 4e corresponding to the pressure peak B 3 on the curve B in FIG. 5.
  • the interface of the high speed jet with the fuel present is the seat of turbulence generating gas bubbles if the pressure prevailing in the fuel present in the orifices 4d and 4 e is insufficient, which is minimized by the high level of pressure P 2 , between 50 and 100 bars.
  • the piston After reaching top dead center, the piston performs its stroke back to bottom dead center, the pressure drops in the 4k compression which increases in volume and, when the 4d and 4e orifices are again in communication with the 4k compression chamber, the pressure also drops throughout the circuit between the non-return valve 3, the calibrated valve 6 and the valve 7.
  • the spring 7c causes the valve 7 to pass into position 7d, the damper 8 is emptied and the cycle can start again.
  • Curve A in FIG. 5 represents the same operating phases for a pump not fitted with a device according to the invention.
  • the pressure at point A 1 remains close to the pressure P 0 , ie close to a few bars.
  • the pressure P 1 at point A 2 less than 50 bars, corresponding to the start of the discharge through the orifices 4d and 4e is insufficient to avoid the formation of gas bubbles at the periphery of the jets. These bubbles strike the walls of the orifices 4d and 4e and create an erosion which causes the destruction of the jacket 4f.
  • the residual pressure maintained in the orifices 4d and 4e by the calibrated valve 6 considerably reduces the formation of gas bubbles and minimizes erosion.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Reciprocating Pumps (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Jet Pumps And Other Pumps (AREA)
  • Pipeline Systems (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)

Abstract

The system consists of a calibrated valve (6) in the excess fuel return pipe (5) in parallel with and close to the injection pump return port (4b), designed to give an increase in pressure in the pump port, and a normally-open one-way valve (7). The one-way valve (7), which is springloaded, is closed when the pressure in the port rises above that in the fuel feed pipe (2) before its non-return valve (3).

Description

La présente invention concerne un dispositif destiné à éliminer la cavitation dans le ou les orifices de retour du combustible en excès dans la chambre de compression d'une pompe d'injection de combustible d'un moteur à combustion interne après la fin de la phase d'injection. Cette phase du fonctionnement de la pompe d'injection appelée « décharge » provoque une brusque évacuation du combustible excédentaire à très forte pression et animé d'une très grande vitesse de circulation dans les orifices de retour où le combustible déjà présent est à basse pression. Ceci entraíne à l'interface du jet de combustible évacué et du combustible à faible pression, l'apparition de bulles dues au dégazage qui, combinées à la vitesse de circulation, provoquent des érosions par cavitation de la paroi des orifices de retour, ces érosions pouvant entraíner la destruction de la pompe d'injection. L'un des moyens pour éliminer cette cavitation est d'augmenter la pression régnant dans les orifices de retour de la pompe d'injection à l'instant de la décharge. On connaít des dispositifs tel celui décrit dans le document JP08296528 qui enseigne la mise en place d'un clapet anti-retour en amont de l'alimentation de la pompe d'injection et de deux soupapes en aval de la pompe d'injection, l'une des soupapes étant fortement tarée et autorisant un fort débit, l'autre soupape étant faiblement tarée et destinée à un faible débit. En outre, au moins l'une des soupapes comporte un orifice assurant une circulation permanente du combustible. L'inconvénient de ce dispositif est que la fuite permanente ne permet pas de maintenir une pression élevée et suffisante dans les orifices avant que ne se produise la décharge. Cette pression ne s'installe que lorsqu'apparaít le débit de décharge, ce qui est insuffisant pour éviter efficacement l'érosion des orifices.The present invention relates to a device for eliminating cavitation in the excess fuel return port (s) in the compression chamber of a fuel injection pump of an internal combustion engine after the end of the injection phase. This phase of the operation of the injection pump called "Discharge" causes sudden fuel evacuation excess at very high pressure and driven by a very high speed of circulation in return ports where the fuel already present is at low pressure. This leads to the interface of the evacuated fuel jet and fuel at low pressure, the appearance of bubbles due to degassing which, combined with the speed of circulation, cause erosion by cavitation of the wall of the return orifices, these erosions can cause destruction of the injection pump. One of the means to eliminate this cavitation is to increase the pressure prevailing in the return ports of the injection pump at the time of discharge. We know devices such as that described in the document JP08296528 which teaches the installation of a non-return valve in upstream of the supply of the injection pump and two valves in downstream of the injection pump, one of the valves being highly calibrated and allowing a high flow, the other valve being lightly calibrated and intended for low flow. In addition, at least one of the valves has an orifice ensuring permanent circulation of the combustible. The disadvantage of this device is that the permanent leak does not maintain high and sufficient pressure in the orifices before discharge occurs. This pressure does not installs only when the discharge rate appears, which is insufficient to effectively prevent hole erosion.

L'invention se propose de remédier à ces inconvénients en prévoyant un dispositif destiné à éliminer la cavitation dans le ou les orifices de retour du combustible en excès dans la chambre de compression d'une pompe d'injection de combustible d'un moteur à combustion interne après la fin de la phase d'injection, la dite pompe d'injection étant raccordée, d'une part, à un conduit d'alimentation comportant un clapet anti-retour à faible perte de charge autorisant l'arrivée du combustible dans la chambre de compression et, d'autre part, à un conduit de retour du combustible en excès,
   caractérisé en ce que le conduit de retour comporte en parallèle et à proximité de l'orifice de retour de la pompe d'injection un clapet taré destiné à provoquer l'élévation de la pression dans le dit orifice de retour de la pompe d'injection et une vanne à une voie normalement ouverte dont la fermeture est provoquée par l'apparition d'une pression dans l'orifice de retour, supérieure à celle qui règne dans le conduit d'alimentation en amont dudit clapet anti-retour.The invention proposes to remedy these drawbacks by providing a device intended to eliminate cavitation in the return port (s) of excess fuel in the compression chamber of a fuel injection pump of a combustion engine. internal after the end of the injection phase, said injection pump being connected, on the one hand, to a supply duct comprising a non-return valve with low pressure drop authorizing the arrival of the fuel in the compression chamber and, on the other hand, to a return line for excess fuel,
characterized in that the return duct comprises in parallel and close to the return port of the injection pump a calibrated valve intended to cause the increase in pressure in said return port of the injection pump and a normally open one-way valve, the closure of which is caused by the appearance of a pressure in the return orifice, greater than that which prevails in the supply duct upstream of said non-return valve.

Selon une autre caractéristique de l'invention, la vanne à une voie est munie d'un ressort provoquant l'ouverture de ladite vanne dans le cas où la pression régnant en amont du clapet anti-retour est sensiblement égale à la pression régnant dans l'orifice de retour.According to another characteristic of the invention, the one-way valve is provided with a spring causing the opening of said valve in the the pressure prevailing upstream of the non-return valve is substantially equal to the pressure in the return port.

Selon encore une autre caractéristique de l'invention, le conduit de retour comporte un accumulateur en dérivation et en amont du clapet taré et de la vanne à une voie.According to yet another characteristic of the invention, the conduit return has a bypass accumulator and upstream of the valve calibrated and one-way valve.

Un autre objet de l'invention est l'utilisation du dit dispositif pour mettre en oeuvre l'injection de combustible dans un moteur à combustion interne.Another object of the invention is the use of said device for implement fuel injection into a internal combustion.

Les avantages de ce dispositif résident dans une moindre usure des composants de la pompe d'injection, autorisant ainsi la diminution de la fréquence de maintenance et minimisant la dispersion de particules métalliques dans le combustible.The advantages of this device lie in less wear components of the injection pump, thus allowing the reduction maintenance frequency and minimizing the dispersion of metallic particles in the fuel.

A titre d'exemple non limitatif, la figure 1 représente un schéma du dispositif selon l'invention. Les figures 2, 3 et 4 représentent le piston de la pompe d'injection à différents stades de la compression. La figure 5 représente l'évolution des pressions dans les orifices de retour au cours des phases d'injection, la courbe A représentant cette évolution pour une pompe non munie du dispositif selon l'invention et la courbe B représentant la même évolution pour une pompe munie du dispositif selon l'invention.By way of nonlimiting example, FIG. 1 represents a diagram of the device according to the invention. Figures 2, 3 and 4 show the injection pump piston at different stages of compression. The Figure 5 shows the evolution of pressures in the return ports during the injection phases, curve A representing this development for a pump not fitted with the device according to the invention and the curve B representing the same evolution for a pump fitted with the device according to the invention.

Dans la figure 1, un conduit 2 muni d'un clapet anti-retour 3 relie une pompe de circulation de combustible 1 alimentée par un réservoir 9 à une pompe d'injection de combustible 4 partiellement représentée par l'intermédiaire d'un orifice d'alimentation 4a. La pression de refoulement de la pompe 1 est limitée par un clapet taré la. Le conduit principal de retour 5 et les conduits secondaires 5a et 5b raccordent en parallèle l'orifice de retour 4b de la pompe d'injection 4 à un clapet taré 6 et à une vanne à une voie 7. La vanne à une voie 7 est pilotée au moyen de la ligne 7a par la pression régnant dans le conduit 5b et au moyen de la ligne 7b par la pression régnant dans le conduit 2 en amont du clapet taré 3. Un ressort 7c renforce l'action de pilotage due à la pression de la ligne 7b et maintient la vanne 7 en position ouverte en l'absence d'écart de pression important entre les deux lignes de pilotage. Dans la position 7e, la vanne 7 met en oeuvre un diaphragme entraínant une perte de charge destinée à maintenir un certain niveau de pression du combustible en amont de la vanne 7. Les orifices 4a et 4b sont mis sélectivement en communication avec la chambre de compression 4k de la pompe d'injection 4 par l'intermédiaire d'une gorge périphérique 4c de l'enveloppe 4j et des orifices 4d et 4e de la chemise de piston 4f en fonction des mouvements du piston 4g comportant les arêtes d'interruption de refoulement 4h et 4i. Un accumulateur 8 de faible volume est installé en dérivation sur le conduit 5 immédiatement en aval de l'orifice de retour 4b. Le clapet taré 6 et la vanne 7 sont reliés au réservoir 9 par les conduits 5c et 5d.In FIG. 1, a duct 2 provided with a non-return valve 3 connects a fuel circulation pump 1 supplied by a tank 9 to a fuel injection pump 4 partially represented by through a supply port 4a. The pressure of delivery of pump 1 is limited by a calibrated valve la. The conduit main return 5 and secondary conduits 5a and 5b connect in parallel the return port 4b of the injection pump 4 to a calibrated valve 6 and a one-way valve 7. The one-way valve 7 is controlled at line 7a by the pressure in line 5b and at line 7b by the pressure prevailing in the duct 2 upstream of the calibrated valve 3. A spring 7c reinforces the piloting action due to the line pressure 7b and keeps the valve 7 in the open position in the absence of a significant pressure difference between the two control lines. In the 7th position, the valve 7 implements a driving diaphragm a pressure drop intended to maintain a certain level of pressure fuel upstream of valve 7. Ports 4a and 4b are put selectively in communication with the 4k compression chamber of the injection pump 4 via a peripheral groove 4c of the casing 4j and the orifices 4d and 4e of the piston liner 4f in function of the 4g piston movements including the edges delivery interruption 4h and 4i. A low 8 accumulator volume is installed bypass on duct 5 immediately in downstream of the return port 4b. The calibrated valve 6 and the valve 7 are connected to the tank 9 through conduits 5c and 5d.

Dans la figure 2, le piston 4g est au point mort bas et dégage les orifices 4d et 4e pour les mettre en communication avec la chambre de compression 4k.In Figure 2, the piston 4g is in bottom dead center and releases the 4d and 4th ports to put them in communication with the 4k compression.

Dans la figure 3, le piston 4g est sensiblement à mi-course et obture les orifices 4d et 4e interrompant la communication avec la chambre de compression 4k.In FIG. 3, the piston 4g is substantially halfway and closes orifices 4d and 4e interrupting communication with the 4k compression chamber.

Dans la figure 4, le piston 4g a poursuivi sa course et les arêtes 4i et 4h dégagent les orifices 4d et 4e et les met en communication avec la chambre de compression 4k, via une rainure 4m ménagée selon une génératrice sur la paroi latérale du piston 4g.In FIG. 4, the piston 4g continued its stroke and the edges 4i and 4h clear the 4d and 4th orifices and put them in communication with the 4k compression chamber, via a 4m groove formed according to a generator on the side wall of the piston 4g.

Dans la figure 5, sur un graphique d'abscisse T représentant le temps, et d'ordonnée P représentant la pression, la courbe A représente l'évolution de la pression du combustible dans les orifices de retour 4d et 4e lors d'un cycle d'injection pour une pompe non munie du dispositif selon l'invention et la courbe B représente la même évolution pour une pompe munie du dispositif selon l'invention.In FIG. 5, on a graph of abscissa T representing the time, and on the ordinate P representing the pressure, the curve A represents the evolution of the fuel pressure in the 4d return orifices and 4th during an injection cycle for a pump not fitted with the device according to the invention and curve B represents the same evolution for a pump fitted with the device according to the invention.

Le fonctionnement du dispositif est décrit ci-après.The operation of the device is described below.

Le piston 4g est en début de course de compression tel que représenté sur la figure 2. Le clapet 6 est taré à une pression comprise entre 50 et 100 bars, l'amortisseur 8 présente une pression de gonflage légèrement inférieure au tarage du clapet 6 et, en l'absence de différence de pression importante entre les conduits 7a et 7b, la vanne 7 est maintenue ouverte en position 7e par le ressort 7c. Le diaphragme de la vanne 7 en position 7e assure une pression de circulation de l'ordre de 3 bars. Le combustible fourni par la pompe 1 circule dans le conduit 2 à travers le clapet anti-retour 3, l'orifice 4a, la chambre de compression 4k, l'orifice 4b, la vanne 7 et retourne au réservoir 9 par le conduit 5d. Cette situation correspond sur la figure 5 au temps T0 de la courbe B.The piston 4g is at the start of the compression stroke as shown in FIG. 2. The valve 6 is calibrated at a pressure between 50 and 100 bars, the damper 8 has an inflation pressure slightly lower than the calibration of the valve 6 and , in the absence of a significant pressure difference between the conduits 7a and 7b, the valve 7 is kept open in position 7e by the spring 7c. The diaphragm of the valve 7 in the 7th position provides a circulation pressure of the order of 3 bars. The fuel supplied by the pump 1 circulates in the conduit 2 through the non-return valve 3, the orifice 4a, the compression chamber 4k, the orifice 4b, the valve 7 and returns to the tank 9 through the conduit 5d. This situation corresponds in Figure 5 to time T 0 of curve B.

Le piston 4g poursuit sa course de compression et la forte pression dans la conduite (non représentée) reliant la chambre de compression 4k à l'injecteur (non représenté) provoque la fermeture du clapet anti-retour 3 et le refoulement du combustible par l'orifice 4b. La brusque augmentation de débit dans le conduit 5b et la perte de charge dans la vanne 7 provoque une augmentation significative de pression dans les conduits 5a et 7a, entraínant le pilotage de la vanne 7 qui passe en position 7d. La pression continue de monter dans le conduit 5a jusqu'à atteindre la valeur de tarage du clapet 6 qui commence à s'ouvrir. Dans le même temps, l'amortisseur 8 se rempli et monte en pression atténuant ainsi le coup de bélier sur le clapet 6. Cette situation correspond sur la figure 5 à l'évolution de la courbe B au voisinage du point B1.The piston 4g continues its compression stroke and the high pressure in the pipe (not shown) connecting the compression chamber 4k to the injector (not shown) causes the closing of the non-return valve 3 and the fuel delivery by the port 4b. The sudden increase in flow in the conduit 5b and the pressure drop in the valve 7 causes a significant increase in pressure in the conduits 5a and 7a, causing the piloting of the valve 7 which passes to position 7d. The pressure continues to rise in the duct 5a until reaching the setting value of the valve 6 which begins to open. At the same time, the damper 8 fills and rises in pressure, thus reducing the water hammer on the valve 6. This situation corresponds in FIG. 5 to the evolution of the curve B in the vicinity of the point B 1 .

Lorsque le piston 4g atteint la position représentée sur la figure 3, les orifices 4a et 4b sont obturés et le combustible est contenu entre le clapet anti-retour 3 et le clapet taré 6 à une pression voisine de la pression de tarage du clapet anti-retour 6. Cette pression règne donc également dans la gorge circulaire 4c et dans les orifices 4d et 4e. L'isolement de la chambre de compression 4k des orifices 4d et 4e permet la montée en pression dans ladite chambre de compression jusqu'à la valeur prévue pour l'injection qui peut être de l'ordre de 1000 bars. Cette situation correspond sur la figure 5 à l'évolution de la courbe B entre les points B1 et B2.When the piston 4g reaches the position shown in FIG. 3, the orifices 4a and 4b are closed and the fuel is contained between the non-return valve 3 and the calibrated valve 6 at a pressure close to the setting pressure of the anti-valve back 6. This pressure therefore also prevails in the circular groove 4c and in the orifices 4d and 4e. The isolation of the compression chamber 4k from the orifices 4d and 4e allows the pressure build-up in said compression chamber to the value provided for injection which can be of the order of 1000 bars. This situation corresponds in FIG. 5 to the evolution of the curve B between the points B 1 and B 2 .

Lorsque le piston 4g atteint la position représentée sur la figure 4, les arêtes 4h et 4i ont découvert les orifices 4d et 4e, les mettant à nouveau en communication avec la chambre de compression 4k. Le début de cette ouverture appelé « décharge » correspond au temps T1 et à la pression P2 sur la figure 5. Cette décharge provoque un brusque transfert de combustible à travers les orifices 4d et 4e sous forme de jets à très haute vitesse, entraínant une rapide montée en pression dans les orifices 4d et 4e correspondant au pic de pression B3 sur la courbe B de la figure 5. L'interface du jet à haute vitesse avec le combustible présent est le siège de turbulences génératrices de bulles de gaz si la pression régnant dans le combustible présent dans les orifices 4d et 4e, est insuffisante, ce qui est minimisé par le niveau élevé de pression P2, compris entre 50 et 100 bars.When the piston 4g reaches the position shown in FIG. 4, the edges 4h and 4i have discovered the orifices 4d and 4e, putting them again in communication with the compression chamber 4k. The start of this opening called “discharge” corresponds to time T 1 and to pressure P 2 in FIG. 5. This discharge causes a sudden transfer of fuel through the orifices 4d and 4e in the form of jets at very high speed, causing a rapid rise in pressure in the orifices 4d and 4e corresponding to the pressure peak B 3 on the curve B in FIG. 5. The interface of the high speed jet with the fuel present is the seat of turbulence generating gas bubbles if the pressure prevailing in the fuel present in the orifices 4d and 4 e is insufficient, which is minimized by the high level of pressure P 2 , between 50 and 100 bars.

Après avoir atteint le point mort haut, le piston effectue sa course de retour vers le point mort bas, la pression chute dans la chambre de compression 4k qui augmente de volume et, lorsque les orifices 4d et 4e sont à nouveau en communication avec la chambre de compression 4k, la pression chute également dans l'ensemble du circuit compris entre le clapet anti-retour 3, le clapet taré 6 et la vanne 7. Lorsque la pression dans le conduit 7a est voisine de la pression dans le conduit 7b, le ressort 7c provoque le passage de la vanne 7 en position 7d, l'amortisseur 8 se vide et le cycle peut recommencer.After reaching top dead center, the piston performs its stroke back to bottom dead center, the pressure drops in the 4k compression which increases in volume and, when the 4d and 4e orifices are again in communication with the 4k compression chamber, the pressure also drops throughout the circuit between the non-return valve 3, the calibrated valve 6 and the valve 7. When the pressure in the duct 7a is close to the pressure in the duct 7b, the spring 7c causes the valve 7 to pass into position 7d, the damper 8 is emptied and the cycle can start again.

La courbe A de la figure 5 représente les mêmes phases de fonctionnement pour une pompe non munie d'un dispositif selon l'invention. La pression au point A1 reste voisine de la pression P0, soit proche de quelques bars. La pression P1 au point A2, inférieure à 50 bars, correspondant au début de la décharge par les orifices 4d et 4e est insuffisante pour éviter la formation de bulles gazeuses à la périphérie des jets. Ces bulles heurtent les parois des orifices 4d et 4e et créent une érosion qui entraíne la destruction de la chemise 4f. Dans le dispositif selon l'invention, la pression résiduelle maintenue dans les orifices 4d et 4e par le clapet taré 6 réduit considérablement la formation des bulles de gaz et minimise l'érosion.Curve A in FIG. 5 represents the same operating phases for a pump not fitted with a device according to the invention. The pressure at point A 1 remains close to the pressure P 0 , ie close to a few bars. The pressure P 1 at point A 2 , less than 50 bars, corresponding to the start of the discharge through the orifices 4d and 4e is insufficient to avoid the formation of gas bubbles at the periphery of the jets. These bubbles strike the walls of the orifices 4d and 4e and create an erosion which causes the destruction of the jacket 4f. In the device according to the invention, the residual pressure maintained in the orifices 4d and 4e by the calibrated valve 6 considerably reduces the formation of gas bubbles and minimizes erosion.

Claims (4)

Dispositif destiné à éliminer la cavitation dans le ou les orifices de retour (4b) du combustible en excès dans la chambre de compression (4k) d'une pompe d'injection de combustible (4) d'un moteur à combustion interne après la fin de la phase d'injection, ladite pompe d'injection étant raccordée, d'une part, à un conduit d'alimentation (2) comportant un clapet anti-retour (3) à faible perte de charge autorisant l'arrivée du combustible dans la chambre de compression et, d'autre part, à un conduit de retour (5) du combustible en excès,
   caractérisé en ce que le conduit de retour comporte en parallèle et à proximité de l'orifice de retour de la pompe d'injection, un clapet taré (6) destiné à provoquer l'élévation de la pression dans ledit orifice de retour de la pompe d'injection et une vanne (7) à une voie normalement ouverte dont la fermeture est provoquée par l'apparition d'une pression dans l'orifice de retour, supérieure à celle qui règne dans le conduit d'alimentation en amont dudit clapet anti-retour.Device for eliminating cavitation in the return port (s) (4b) of excess fuel in the compression chamber (4k) of a fuel injection pump (4) of an internal combustion engine after completion of the injection phase, said injection pump being connected, on the one hand, to a supply duct (2) comprising a non-return valve (3) with low pressure drop allowing the fuel to arrive in the compression chamber and, on the other hand, to a return pipe (5) for excess fuel,
characterized in that the return duct comprises in parallel and near the return port of the injection pump, a calibrated valve (6) intended to cause the increase in pressure in said return port of the pump injection valve and a normally open one-way valve (7), the closure of which is caused by the appearance of a pressure in the return orifice, greater than that which prevails in the supply duct upstream of said check valve -return. Dispositif selon la revendication 1, caractérisé en ce que la vanne (7) à une voie est munie d'un ressort (7c) provoquant l'ouverture de ladite vanne dans le cas où la pression régnant en amont du clapet anti-retour (3) est sensiblement égale à la pression régnant dans l'orifice de retour (4b).Device according to claim 1, characterized in that the one-way valve (7) is provided with a spring (7c) causing the opening of said valve in the case where the pressure prevailing upstream of the valve non-return valve (3) is substantially equal to the pressure prevailing in the orifice back (4b). Dispositif selon la revendication 1, caractérisé en ce que le conduit de retour (5) comporte un accumulateur (8) en dérivation et en amont du clapet taré (6) et de la vanne (7) à une voie.Device according to claim 1, characterized in that the return duct (5) comprises an accumulator (8) in bypass and in upstream of the calibrated valve (6) and the one-way valve (7). Utilisation du dispositif selon l'une quelconque des revendications précédentes pour mettre en oeuvre l'injection de combustible dans un moteur à combustion interne.Use of the device according to any one of the previous claims for implementing the injection of fuel in an internal combustion engine.
EP99400183A 1998-01-27 1999-01-27 Device for avoiding cavitation in injection pumps Expired - Lifetime EP0931928B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9800836 1998-01-27
FR9800836A FR2774132B1 (en) 1998-01-27 1998-01-27 DEVICE FOR AVOIDING CAVITATION IN INJECTION PUMPS

Publications (2)

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EP0931928A1 true EP0931928A1 (en) 1999-07-28
EP0931928B1 EP0931928B1 (en) 2003-09-03

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US (1) US6065453A (en)
EP (1) EP0931928B1 (en)
JP (1) JPH11280597A (en)
KR (1) KR100625891B1 (en)
CN (1) CN1118622C (en)
AT (1) ATE248988T1 (en)
BR (1) BR9900355A (en)
DE (1) DE69910850T2 (en)
DK (1) DK0931928T3 (en)
FR (1) FR2774132B1 (en)
HK (1) HK1021655A1 (en)
NO (1) NO322999B1 (en)
PL (1) PL194133B1 (en)

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DE102006037174A1 (en) * 2006-08-09 2008-02-14 Robert Bosch Gmbh Apparatus and method for controlling a fuel flow rate in a low pressure circuit system for an internal combustion engine
US7481204B2 (en) * 2007-06-26 2009-01-27 Deere & Company Internal combustion engine flow regulating valve
DE102008059289A1 (en) * 2008-11-27 2010-06-02 Andreas Stihl Ag & Co. Kg Fuel supply device with an electromagnetic fuel valve
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USD679292S1 (en) 2012-04-27 2013-04-02 S.P.M. Flow Control, Inc. Center portion of fluid cylinder for pump
KR101338805B1 (en) * 2012-06-14 2013-12-06 현대자동차주식회사 Feul supply apparatus for gdi engine having reduced pressure pulsation
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EP2351929A4 (en) * 2008-10-27 2013-12-18 Hyun Dai Heavy Ind Co Ltd Apparatus for preventing cavitation damage to a diesel engine fuel injection pump

Also Published As

Publication number Publication date
PL331056A1 (en) 1999-08-02
KR19990068166A (en) 1999-08-25
FR2774132A1 (en) 1999-07-30
NO990368D0 (en) 1999-01-27
NO990368L (en) 1999-07-28
NO322999B1 (en) 2006-12-18
CN1224802A (en) 1999-08-04
EP0931928B1 (en) 2003-09-03
HK1021655A1 (en) 2000-06-23
DE69910850D1 (en) 2003-10-09
KR100625891B1 (en) 2006-09-20
US6065453A (en) 2000-05-23
FR2774132B1 (en) 2000-04-07
DK0931928T3 (en) 2004-01-05
JPH11280597A (en) 1999-10-12
PL194133B1 (en) 2007-04-30
CN1118622C (en) 2003-08-20
ATE248988T1 (en) 2003-09-15
BR9900355A (en) 2000-02-29
DE69910850T2 (en) 2004-07-29

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