EP0089301A1 - Injection control system for diesel engines - Google Patents

Abstract

System for controlling the opening and closing of a diesel engine injector (2), by setting up the suppression of the high pressure in a pipe (23) connected to the upper part of the injector (2). This pipe (23) is alternately connected to a high pressure supply to cause the end of injection or to a discharge to cause the start of injection by medium pressure pulses controlling the relative sliding of a central drawer (12) and a movable liner (17) both relative to each other, as compared to a fixed liner (21).

Description

The present invention relates to a system of a new type, for controlling the start and end of fuel injection into the displacement of a diesel engine.

• - un premier tiroir pour piloter le début d'injection ;
• - un deuxième tiroir pour piloterla fin d'injection.

We know, for example from French patent application n ° 79 31 353, filed on December 14, 1979, in the name of the present Applicant, under the title "Fuel injection device for an internal combustion engine", a device where the start of injection and the end of injection are both controlled by hydraulic means. This known system includes

• - a first drawer to control the start of injection;
• - a second drawer to control the end of injection.

The control of these two drawers is ensured using micro-solenoid valves triggered from an electronic calculator.

Experience has shown that this known device works satisfactorily, but has the disadvantage of having a large size, while requiring for the set of injection members, an organization entirely different from that of conventional devices.

The object of the present invention is to avoid these drawbacks by providing a system with hydraulic control for the start and end of injection, in particular allowing the use of injector holders which have been little modified compared to conventional injector holders.

A system according to the invention, for controlling the start and end of fuel injection into the displacement of a diesel engine, comprises in known manner, an injector holder controlling the closing of the injector when the high pressure is sent on top of it, while when this high pressure stops, the injector opens, and it is characterized in that inside the injector holder are a movable jacket and a central drawer two concentric, capable of sliding relative to each other and relative to a peripheral fixed jacket, under the action of hydraulic pulses distributed from micro-electro-valves actuated by an electronic computer.

• - on peut organiser le système pour qu'après chaque cycle d'injection, le tiroir central et la chemise mobile reviennent à la même position de repos ( autrement dit, chacun d'eux décrit un aller-retour pour chaque cycle d'injection);
• on peut au contraire prévoir qu'un cycle d'injection est terminé après chaque course simple de la chemise mobile et de son tiroir central ( autrement dit_' on décrit deux cycles d'injection suo- cessifs pour chaque aller-retour de la chemise et du tiroir).

Of course, different variants are possible from this same parent idea. In particular

• - we can organize the system so that after each injection cycle tion, the central drawer and the movable folder return to the same rest position (in other words, each of them describes a round trip for each injection cycle);
• we can instead provide an injection cycle is completed after every single stroke of the movable sleeve and its central drawer (ie _we described two injection cycles suo- cessive for each round trip of the sleeve and drawer).

• Figure 1 est un schéma illustrant l'organisation d' un système d'injection selon l'invention.
• figure 2 est une coupe axiale d'un porte-injecteur, montrant la disposition de la chemise fixe, de la chemise mobile et du tiroir central.
• Figure 3 est une vue en plan correspondant à la figure 2.
• Figures 4 et 5 sont des coupes partielles respectivement suivant IV-IV et V-V ( figure 3) .
• Figures 6 à 8 sont des schémas correspondant à la figure 2 , et illustrant les mouvements relatifs de la chemise mobile et du tiroir oentral.
• Figures 9 à 11 correspondent à des variantes .

The appended drawing, given by way of nonlimiting example, will allow a better understanding of the characteristics of the invention.

• Figure 1 is a diagram illustrating the organization of an injection system according to the invention.
• Figure 2 is an axial section of an injector holder, showing the arrangement of the fixed liner, the movable liner and the central drawer.
• Figure 3 is a plan view corresponding to Figure 2.
• Figures 4 and 5 are partial sections respectively along IV-IV and VV (Figure 3).
• Figures 6 to 8 are diagrams corresponding to Figure 2, and illustrating the relative movements of the movable sleeve and the central drawer.
• Figures 9 to 11 correspond to variants.

There is shown in the diagram of Figure 1, an injector holder 1, equipped with an injector 2, the assembly being mounted in the known manner, in the cylinder head of a diesel engine, for injecting into the displacement, the desired dose of fuel at each engine oyle.

• - un embout 3 assurant sa connexion avec une pompe à haute pression 7 ( celle-ci refoule du combustible à une pression constante qui peut être de l'ordre de 700 à 1000 bars) ;
• - deux embouts 4 et 5 , alimentés en combustible à moyenne pression (par exemple de l'ordre de 120 bars) à partir de deux électro-vannes 8 et 9 recevant le combustible d'une pompe à moyenne pression 10 ;
• - un raccord 6 pour décharger la pression du combustible.

At its apex, the injector holder 1 according to the invention has four connection nozzles, namely

• - A nozzle 3 ensuring its connection with a high pressure pump 7 (this delivers fuel at a constant pressure which can be of the order of 700 to 1000 bars);
• - two nozzles 4 and 5, supplied with medium pressure fuel (for example of the order of 120 bars) from two solenoid valves 8 and 9 receiving the fuel from a medium pressure pump 10;
• - a connector 6 for discharging the fuel pressure.

Inside the injector holder 1, the connection to medium pressure 4 opens onto the end 11 of a central drawer 12. The latter is supported by a shuttle 13 on a stop piece 14, to which a compression spring 15 is maintained on an injection valve 16.

Around the drawer 12, there is a movable tubular jacket 17 provided with an elongated lateral opening 18 capable of moving in the axial direction, relative to a fixed indexing pin 19. The latter prevents the mobile jacket 17 from turning on itself, while limiting the amplitude of its movements in the axial direction shown diagrammatically by the double arrow 20.

The pin 19 is secured to a fixed jacket 21 housed in the body of the injector holder 1.

A movable tubular spacer 22 is disposed between the end of the movable jacket 17, and the stop piece 14.

• - au nombre de deux référencés 27 et 28 ( cas de la figure 2) ;
• - au nombre de trois, référencés 29, 30 et 31 ( cas des figures 10 et 11) ;
• - au nombre de quatre, référencés 32, 33, 34 35 ( cas des figures 6 à 9) .

A pipe 23 connects in the known manner the top of the injector 2 to the high pressure supply. According to the invention, the top of the pipe 23 ends in the fixed jacket 21 by transverse holes such as 24, 25 and 26 opening into the bore of the liner 21 where the movable liner 17 slides. The latter also comprises holes which cross it over its entire thickness. These holes can be, as the case may be:

• - the number of two referenced 27 and 28 (case of Figure 2);
• - three in number, referenced 29, 30 and 31 (case of Figures 10 and 11);
• - four in number, referenced 32, 33, 34 35 (case of Figures 6 to 9).

• - au nombre de trois , référencées 38 , 39 et 40 ( cas des figures 10 et 11) ;
• - au nombre de quatre , référencées 41 42 , 43 44 ( cas des figures 6 a 9).

Finally, on the body of the dispenser drawer 12, transverse grooves are machined which can be two in number, referenced 36 and 37 (case of FIG. 2);

• - three in number, referenced 38, 39 and 40 (case of Figures 10 and 11);
• - four in number, referenced 41 42, 43 44 (case of Figures 6 to 9).

• La pompe 7 envoie en permanence la haute pression dans l'embcut 3. Un calculateu électronique 45 , alimenté à partir de plusieurs entrées , qui prennent en compte divers paramètres de fonctionnement du moteur , et notament les instructions du conducteur_' est relié par des lignes électriques 46 et 47 , aux micro-électro-vannes 8 et 9 . En fonction des ordres donnés par le calculateur 45 , chacune des micro-électro-vannes 8 et 9, alimentée par la pompe à moyenne pression 10 , envoie des impulsions à moyenne pression , dans les embouts de raccordement 4 et 5 . Ces impulsions hydrauliques commandent le coulissement du tiroir 12 et de la chemise mobile 17, ausai bien l'un par rapport à l'autre, que par rapport à la chemise fixe 21 .

The operation is as follows:

• The pump 7 permanently sends the high pressure into the nozzle 3. An electronic computer 45, supplied from several inputs, which take into account various operating parameters of the engine, and in particular the instructions of the conduc teur _' is connected by electric lines 46 and 47 to the micro-solenoid valves 8 and 9. Depending on the orders given by the computer 45, each of the micro-solenoid valves 8 and 9, supplied by the medium pressure pump 10, sends pulses at medium pressure, in the connection ends 4 and 5. These hydraulic pulses control the sliding of the slide 12 and of the movable jacket 17, as well with respect to one another as with respect to the fixed jacket 21.

As previously indicated, the start of injection is caused when the line 23 above the injector 2 is connected to the discharge 6, while on the contrary, the end of injection is caused by connecting this same line 23 to the high pressure supply 3.

In the case of the variant of Figures 6 to 8, there is shown in Figure 6, the rest position which corresponds to the end of injection. In this case, the movable sleeve 17 and the drawer 12 are subjected to the sole action of their springs 15 and 48. No pressure pulse is sent into the ends 4 and 5. The high-pressure end 3 communicates with the pipe 23, through the groove 42 of the drawer 12, and the corresponding holes 33 of the movable jacket 17.

In the case of FIG. 7, a medium pressure pulse has been sent by the solenoid valve 8 in the connection end piece 5, so that the jacket 17 is pushed back to the left, against its spring 48. The pipe 23 is connected to the discharge 6 by the groove 44, placed in coincidence with the holes 35 in the jacket 17.

In the case of FIG. 8, a medium pressure pulse is sent in turn through the solenoid valve 9 in the connection end piece 4, so that the slide 12 also moves to the left, at the against the spring 15. This time, the pipe 23 is connected to the high pressure by the groove 41 located opposite the holes 32 of the movable jacket 17: this pulse of the solenoid valve 9 defines. the end of injection.

In the example which has just been described, it can be seen that a complete injection cycle of the engine is defined by a one-way (leftward movement) of the liner 17, then of the drawer 12. This arrangement makes it possible to minimize the length of the high pressure pipes.

In the variant illustrated in FIG. 9, the drawer 12 and the movable jacket 17 are used, not for passing the piloting flow rate from the needle of the injector 2, but directly to the injected flow rate. In this variant, it is not possible to have assisted closing for the injector.

The variant of FIG. 10 is used when the speed of the injection frequency is not critical. In this case, provision is made for the drawer 12 and the jacket 17 to describe a round trip for each injection cycle. This leads to a simplified system comprising only three channels connected to the pipe 23 (see FIG. 10). This variant of FIG. 10 is advantageous for slow engines or when it is desired to integrate the double sheath 12 - 17, into the injector holder 1. The start of injection is defined by the intermediate jacket 17, with passage of the injected flow.

In the variant of FIG. 11, the start of injection is defined by the central drawer 12, while it is the intermediate jacket 17 which defines the end of injection. Indeed, the intermediate jacket 17 having a larger annular section, it can be animated with a faster movement, which. may be of interest on certain types of engines.

Of course, it would not depart from the scope of the invention, by combining as desired the different possibilities illustrated in the variants of FIGS. 6 to 11. Likewise, the control of the drawer 12 and of the movable jacket 17 could be both electronic and mechanical, instead of the hydraulic control illustrated in FIG. 1.

Claims (11)

1 - A system for controlling the start and the end of injected _ti on of the fuel in the engine of a diesel engine, comprising in known manner, a nozzle holder which controls the closure of the injector when the high pressure is sent on top of it, when, when this high pressure ceases, the injector opens, and characterized in that inside the injector holder (1) there is a movable jacket (17) and a central drawer (12) both concentric, capable of sliding relative to each other and to a fixed peripheral jacket (21) under the action of pulses distributed from an electronic computer ( 45). 2 - System according to claim 1, characterized in that the pulses are hydraulic pulses distributed from two micro-solenoid valves (8) and (9), which controls the electronic computer (45). 3 - System according to any one of claims 1 and 2, characterized in that the pipe (23) connecting the top of the injector (2) to the high pressure supply (3), terminates in the fixed sleeve (21) by transverse holes which open into the bore of this sleeve (21) where the movable sleeve (17) slides, the latter ostte in turn comprising holes which pass through it over its entire thickness, while transverse grooves are machined on the body of the distributor drawer (12). 4 - System according to any one of the preceding claims, characterized in that the fixed jacket (21) has three holes (24), (25) and (26), while the movable jacket (17) has two holes (27 ) and (28), the drawer (t2) being provided with two grooves (36) and (37) (FIG. 2) 5 - System according to any one of claims 1 to 3, characterized in that the fixed jacket (21) has four holes connected to (23), while the movable jacket (17) has four holes (3 ² ), ( 33), (34), (35), the drawer (12) being equipped with four grooves (41), (42), (43), (44) (Figures 6, 7 and 8). 6 - System according to any one of claims 1 to 3, characterized in that the fixed jacket (21) has four holes connected to the pipe (23), while the movable jacket (17) has three holes (29), (30), (31), the drawer (12) being provided with three grooves (38), (39), (40). 7 - System according to any one of claims 1 to 3, characterized in that the fixed jacket (21) has three holes connected to the pipe (23), while the movable jacket (17) is provided with three holes (29 ), (30), (31), the drawer (12) comprising three grooves (38), (39), (40). (Figure 11) 8 - Device according to any one of claims 1 to 7 characterized in that a one-way displacement of the drawer (12) and the jacket (21) defines a complete injection cycle. 9 - System according to any one of the preceding claims, characterized in that the drawer (12) and the jacket (17) describe a round trip for each injection cycle, which allows to use only three connected channels to the pipe (23) (FIG. 10), the start of injection being defined by the intermediate jacket (17), with passage of the injected flow. 10 - System according to any one of the preceding claims, characterized in that the start of injection is defined by the central drawer (12), while the intermediate jacket (17) defines the end of injection (Figure 11). 11 - System according to any one of the preceding claims, characterized in that the drawer (12) and the movable jacket (17) directly control the amount of diesel fuel injected (Figure 9).

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