PatentDe  


Dokumentenidentifikation EP1111229 31.05.2007
EP-Veröffentlichungsnummer 0001111229
Titel Kraftstoffeinspritzventil für Hubkolbenbrennkraftmaschine
Anmelder Wärtsilä Finland Oy, Vaasa, FI
Erfinder Lehtonen, Kai, 65280 Vaasa, FI
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 60034417
Vertragsstaaten AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LI, LU, MC, NL, PT, SE, TR
Sprache des Dokument EN
EP-Anmeldetag 12.12.2000
EP-Aktenzeichen 003111085
EP-Offenlegungsdatum 27.06.2001
EP date of grant 18.04.2007
Veröffentlichungstag im Patentblatt 31.05.2007
IPC-Hauptklasse F02M 47/04(2006.01)A, F, I, 20051017, B, H, EP
IPC-Nebenklasse F02M 63/00(2006.01)A, L, I, 20051017, B, H, EP   F02M 61/20(2006.01)A, L, I, 20051017, B, H, EP   

Beschreibung[en]

This invention relates to a fuel injection valve arrangement to be connected with a common line of a fuel feeding system of a reciprocating internal combustion engine.

Needle valves, in which the valve member is elongate and quite thin, are commonly used to control fuel injection. Specifically fuel injection arrangements based on a common line and using, for example, heavy oil are often employed. In such a known arrangement, injection control is achieved using a positively controlled needle valve or a separate control valve positioned before a spring loaded needle valve. If, in an arrangement based on positive control, a sealing surface of the needle valve leaks or the valve needle sticks in its open position, or, in an arrangement based on a pre-control valve, a sealing surface of the pre-control valve leaks, fuel may leak into the cylinder and serious engine damage may result.

An aim of the present invention is to provide an injection valve arrangement, preferably based on a common fuel supply line, which is reliable, with which the injection procedure is better controllable and by means of which drawbacks of known arrangements are substantially eliminated.

According to one aspect of the present invention, there is provided an injection valve arrangement as claimed in the ensuing claim 1. An injection valve arrangement according to the preamble of claim 1 is disclosed in FR 2 478 205 A.

The provision of two needle valves in series, with injection taking place only when both of the valves are simultaneously open, makes the arrangement considerably safer than an arrangement having only one valve, because the possibility of leakage or of both valves sticking at the open position simultaneously is substantially less. The two needle valves operate under different conditions. During opening of the first needle valve, the pressure difference across the first valve needle is very small, because the second needle valve is still closed. During opening of the second needle valve, the conditions correspond to those during opening of a conventional injection valve with one needle in a common line system.

Preferably, the valve arrangement is controlled so that, after fuel injection, the first needle valve closes last. Thus the second needle valve always controls the fuel injection and there is no fuel flow over the sealing surface of the first needle valve as it closes because the second needle valve has already been closed. In this manner, simultaneous malfunction of the two needle valves due to different operation conditions is rendered even more improbable, thereby resulting in accurate control of the injection process and increased safety.

In practice each piston arrangement preferably comprises a main piston device to be connected with a valve needle, and an auxiliary piston connected to the main piston device so that a pressure chamber, which has been connected with control pressure through a constriction channel, is formed therebetween. The auxiliary piston is preferably spring loaded in direction away from the main piston device.

A preferred expedient for causing the first needle valve to open first, is for the main piston device of the first needle valve to be of smaller diameter than the main piston device of the second needle valve.

The constriction channel may advantageously be formed in the auxiliary piston. The auxiliary piston may be influenced by another pressure chamber, into which the constriction channel opens.

The other pressure chamber is connected to control pressure through a constriction channel and it is additionally connectable to control pressure over a separate constriction channel, which the auxiliary piston opens for closing the needle valve. Since the diameter of the constriction channel associated with the piston arrangement of the first needle valve, opened by the auxiliary piston, is preferably smaller than the diameter of the corresponding constriction channel associated with the piston arrangement of the second needle valve, the first needle valve closes after the second needle valve. Because in this manner the opening and closing of the needle valves are accomplished by substantially different means, they can be effected independently of each other.

The control of the piston arrangements may advantageously be accomplished by means of a hydraulic oil arrangement or the like, which acts on both of the piston arrangements, and by means of a separate control valve, by means of which the pressure chambers influencing the piston arrangements are connectable selectively to substantially lower pressure, preferably to atmospheric pressure. In practice the hydraulic oil arrangement may, for example, be part of a lubrication system of the engine. Because the pressure of the lubrication oil circuit is typically about 7 bar, a booster pump, by means of which the pressure may be increased to a level of about 200 bar, is thus required.

The pressure chambers influencing the first piston arrangement and the pressure chambers influencing the second piston arrangement are conveniently separated from each other and connected to the control valve by separate constriction channels. Since there are two separate constriction channels in the arrangement according to the invention, only one control valve, which is preferably a solenoid valve, is needed.

An embodiment of the invention will now be described, by way of example only, with particular reference to the accompanying drawings, in which:

  • FIG. 1 is a diagrammatic sectional view of a fuel injection valve arrangement according to the invention in a closed initial position;
  • FIG. 2 is an enlarged view of the upper section of the valve body of the fuel injection valve arrangement shown in FIG. 1; and
  • FIGS. 3-6 are diagrammatic sectional views showing the valve arrangement of FIG. 1 at different operation positions.

In the drawings, reference 1 designates a valve body in which two separate needle valve units are housed and operationally arranged in series. A first needle valve unit includes a first valve needle 2a and is connected via a channel 6 to a supply of fuel under pressure, preferably supplied via a common line indicated by an arrow in the drawings. The needle valve 2a controls the feeding of fuel from a chamber 6a over a first valve sealing surface 7a, along a connecting channel 8, to a chamber 8a, from which a second valve needle 2b of a second needle valve unit controls the feeding of fuel over a second valve sealing surface 7b to a cylinder of the engine (not shown).

The first needle valve further comprises a control element 3a, a piston device 4a, and an auxiliary piston 5a, which are operationally connected with each other. A compression spring 11a is arranged between the control element 3a and the piston device 4a, the elements 3a and 4a being movable against the spring force of the spring. Similarly, a compression spring 12a is arranged between the piston device 4a and the auxiliary piston 5a. The second needle valve unit is constructed in a manner corresponding to that of the first needle valve unit and comprises a valve needle 2b, a control element 3b, a piston device 4b, an auxiliary piston 5b and springs 11b and 12b.

The needle valves are controlled by a hydraulic oil circuit 9, which provides a basic control pressure for the needle valve units, and by a solenoid valve 10, with the assistance of which the opening and closing of the needle valve units are achieved through various chambers and constriction channels by utilizing pressure differences. Timing differences between the needle valves are effected by dimensioning factors, as will be later described in more detail.

The hydraulic oil circuit 9 acts directly on chambers 13a and 13b, which are connected through constriction channels 14a and 14b to chambers 15a and 15b. In this manner the pressure of the hydraulic oil is communicated to chambers 16a and 16b and thus acts on auxiliary pistons 5a and 5b. In addition, the chamber 16a is connected through a constriction channel 17a to a chamber 18a between the piston device 4a and the auxiliary piston 5a. Similarly the chamber 16b is connected through a constriction channel 17b to a chamber 18b between the piston device 4b and the auxiliary piston 5b. Furthermore, the chambers 15a and 15b are connected to a chamber 20 through constriction channels 19a and 19b, which chamber 20 is connected to the solenoid valve 10. The chambers 13a and 13b are connected to channels 21a and 21b, respectively. The channels 21a and 21b are blocked by the auxiliary pistons 5a and 5b when the latter are in their uppermost positions (see FIGS. 1-5), but otherwise the channels 21a and 21b debouch into the chambers 16a and 16b, respectively.

The needle valves operate as follows. In the situation shown in FIG. 1, where the solenoid valve 10 is closed, the pressure of the hydraulic oil in the circuit 9 acts on all the chambers and channels connected to the hydraulic oil system. The pressures in the chambers 18a and 18b, aided by the springs 12a and 12b, force the auxiliary pistons to their uppermost positions, blocking the channels 21a and 21b, and force the piston devices 4a and 4b downwards thereby urging the valve needles 2a and 2b into closed positions. When the solenoid valve 10 is opened (FIG. 3), the chamber 20 is connected through the valve 10 to substantially lower pressure, for example to atmospheric pressure, so that the pressure in the chamber 20 decreases rapidly. Because the constriction channel 19a is of greater diameter than the constriction channel 14a and similarly because the constriction channel 19b is of greater diameter than the constriction channel 14b, the pressure also decreases rapidly in chambers 15a and 16a and in chambers 15b and 16b, thereby allowing hydraulic oil to flow from the chambers 18a and 18b through the constriction channels 17a and 17b, respectively.

The feed pressure of the fuel in the chamber 6a tends to lift the valve needle 2a and, and on the other hand, the pressure of the fuel remaining in the chamber 8a tends to lift the valve needle 2b. The velocities at which the valve needles 2a and 2b rise depend on how fast the oil in the chambers 18a and 18b is able to flow through the constriction channels 17a and 17b, allowing upward movement of the piston devices 4a and 4b. Because, according to the invention, the first needle valve is opened first, the diameter or cross sectional area of the piston device 4a is chosen so as to be smaller than the diameter of the piston device 4b. Consequently, in the event that the diameters of the constriction channels 17a and 17b correspond to each other, the piston device 4a moves faster upwards (as viewed in the figures) and the first needle valve opens first. The situation corresponds to that shown in FIG. 3.

Similarly, flow of oil from the chamber 18b through the constriction channel 17b to the chamber 16b allows upward movement of the piston device 4b thereby opening the second needle valve. Because both of the needle valves are then open, injection of fuel takes place from the common feed line past the sealing surfaces 7a and 7b of the valves into cylinder of the engine. The situation corresponds to that shown in FIG. 4.

FIGS. 5 and 6 show the situation upon closing of the needle valves. When the solenoid valve 10 closes and the connection of the chamber 20, and thereby also of the other chambers, to lower pressure is cut off, the pressures in the chambers 20, 15a and 15b, and 16a and 16b, begin to rise. Thus the pressure in chamber 16a is greater than that in chamber 18a and the pressure in chamber 16b is greater than that in chamber 18b. As a result, the auxiliary pistons 5a and 5b start moving downwards, simultaneously opening the constriction channels 21a and 21b. Because the constriction channel 21b is selected to be of greater diameter than the constriction channel 21a, the pressure applied to the auxiliary piston 5b increases at a faster rate causing the second needle valve to close first whereupon the injection of fuel ends, cf. the situation in FIG. 5. Because of the constriction channels 19a and 19b, this greater pressure communicated through the constriction channel 21b is not communicated to the chamber 16a and does not act on the auxiliary piston 5a. Thus the downward movement of the auxiliary piston 5a and thereby the closing of the first needle valve are mainly dependent on the increased pressure being communicated through the constriction channel 21a. When the pressure has risen sufficiently, the first needle valve closes. The situation corresponds to that shown in FIG. 6.

After closure of the needle valves, the pressure in the hydraulic oil circuit 9 is communicated to the chambers 18a and 18b through the constriction channels 17a and 17b, whereupon the increasing pressures in the chambers 18a and 18b and the force of the springs 12a and 12b move the auxiliary pistons 5a and 5b back to their initial positions shown in FIG. 1 in which the constriction channels 21a and 21b are again closed.

In the embodiment described the diameters of the constriction channels 14a and 14b are equal. The same applies also to the diameters of the constriction channels 19a and 19b and to the diameters of the constriction channels 17a and 17b. The control in relative timing of the opening and closing of the needle valves is achieved through a difference in diameter of the piston device 4a relative to the piston device 4b and a difference in diameter of the constriction channel 21a relative to the constriction channel 21b. Alternatively, however, if the constriction channel 17a were of greater diameter then the constriction channel 17b, it would be possible to ensure that the first needle valve opens before the second needle valve even if the diameters of the piston devices 4a and 4b were equal. Accordingly it is possible to alter the respective diameters and precise positions of the channels to ensure that the first needle valve opens first and closes last, which is advantageous for the operation of the system.

The described structure operates so that the needle valves may open if the pressure in the hydraulic oil system goes down. For this reason it is advantageous to provide the common fuel supply line used for fuel injection with a safety device which quickly depressurizes the common line if the pressure of the hydraulic oil decreases to too low a level. Such a safety device is shown in EP-A-0964153.

The hydraulic oil circuit may advantageously, for example, be part of the lubrication oil circuit of the engine, as long as the pressure of the lubrication oil is increased, for example by means of a booster pump, to a suitable level for controlling the valves, e.g. to about 200 bar. The solution according to the invention is particularly advantageous if heavy oil is used as the fuel being injected. In the illustrated embodiment, each needle valve comprises several discrete parts operationally connected with each other. This construction is advantageous with respect to manufacture and assembly. However, other types of alternative constructions are also possible. For example the valve needles 2a and 2b may be attached to the control elements 3a and 3b if so desired.

In normal operation, the piston device 4 and the control element 3 of each needle valve move together as a unit unless the pressure of the fuel line and the pressure of the hydraulic oil circuit fall, in which case the spring 11 pushes the element 3 away from the piston device 4 and the needle valve closes. This feature ensures that the needle valves are closed when the system is not activated for use. For example, before starting the engine the pressure in the common line is low and there is no pressure in the hydraulic oil circuit 9. In this case the actions of the springs 11 close the needle valves and prevent entry of fuel into the cylinder.

The invention is not restricted to the embodiment shown, but several modifications are feasible within the scope of the attached claims.


Anspruch[de]
Einspritzventilanordnung für eine Brennkraftmaschine, die ein Kraftstoffzuleitungssystem mit einer gemeinsamen Leitung aufweist, wobei die Einspritzventilanordnung umfasst: ein Ventilgehäuse (1), das einen Kraftstoffeinlass (6) zur Verbindung mit der gemeinsamen Leitung des Kraftstoffzuleitungssystems und einen Kraftstoffauslass aufweist; ein erstes Nadelventil innerhalb des Ventilgehäuses (1) und mit einer ersten Ventilnadel (2a); eine erste Kolbenanordnung (4a, 5a), die mit dem ersten Nadelventil (2a) zusammenwirkt und dessen Betrieb steuert; ein zweites Nadelventil innerhalb des Ventilgehäuses (1) und mit einer zweiten Ventilnadel (2b); und eine zweite Kolbenanordnung (4b, 5b), die mit dem zweiten Nadelventil (2b) zusammenwirkt und dessen Betrieb steuert; wobei das erste und zweite Nadelventil (2a, 2b) in Reihe angeordnet betrieben werden, wobei das erste Nadelventil (2a), mit dem Kraftstoffeinlass (6) des Ventilgehäuses (1) verbunden ist, um die Kraftstoffversorgung zum zweiten Nadelventil (2b) zu steuern, und wobei das zweite Nadelventil (2b), mit dem Kraftstoffauslass des Ventilgehäuses verbunden ist, um die Kraftstoffeinspritzung in einen Zylinder des Motors zu steuern, und wobei das erste Nadelventil (2a) angeordnet ist, um sich während eines Kraftstoffeinspritzzyklus durch die koordinierte Wirkung der ersten und zweiten Kolbenanordnung (4a, 5a; 4b, 5b) vor dem zweiten Nadelventil (2b) zu öffnen, und

dadurch gekennzeichnet, dass

das Ventilgehäuse (1) einen Steuereinlass (13a, 13b) zur Verbindung mit einem Steuerdruck (9) aufweist, wobei jede dieser ersten und zweiten Kolbenanordnungen (4a, 5a; 4b, 5b) eine Hauptkolbenvorrichtung (4a, 4b) umfasst, die eine Kopplungsdruckkammer (18a, 18b) begrenzt, wobei jede Hauptkolbenvorrichtung (4a, 4b) zwischen ihrer zugehörigen Ventilnadel (2a, 2b) und ihrer zugehörigen Kopplungsdruckkammer (18a, 18b) liegt, sodass Druck in der Kopplungsdruckkammer (18a, 18b), der auf die Hauptkolbenvorrichtung (4a, 4b) wirkt, der Öffnungsbewegung der Ventilnadel (2a, 2b) widersteht, und wobei jede Kopplungsdruckkammer (18a, 18b) über einen zugehörigen Drosselungskanal (17a, 17b) mit dem Steuereinlass (13a, 13b) verbunden ist.
Einspritzventilanordnung nach Anspruch 1, wobei sich das erste Nadelventil (2a) während eines Kraftstoffeinspritzzyklus nach dem zweiten Nadelventil (2b) schließt. Einspritzventilanordnung nach Anspruch 1 oder 2, wobei jede Kolbenanordnung außerdem einen Hilfskolben (5a, 5b) umfasst und jede Kopplungsdruckkammer (18a, 18b) zwischen der zugehörigen Hauptkolbenvorrichtung (4a, 4b) und dem zugehörigen Hilfskolben (5a, 5b) definiert wird. Einspritzventilanordnung nach Anspruch 3, wobei jeder Hilfskolben (5a, 5b) federbelastet ist, um in eine Richtung weg von der zugehörigen Hauptkolbenvorrichtung (4a, 4b) gespannt zu werden. Einspritzventilanordnung nach Anspruch 3, wobei jeder Hilfskolben (5a, 5b) zwischen der zugehörigen Kopplungsdruckkammer (18a, 18b) und einer zugehörigen Steuerdruckkammer (16a, 16b) angeordnet ist und jeder der Drosselungskanäle 17a, 17b) im zugehörigen Hilfskolben (5a, 5b) geformt ist und sowohl zur zugehörigen Kopplungsdruckkammer (18a, 18b) als auch zur zugehörigen Steuerdruckkammer (16a, 16b) hin offen ist. Einspritzventilanordnung nach Anspruch 5, wobei jede Steuerdruckkammer (16a, 16b) durch einen jeweiligen zweiten Drosselungskanal (14a, 14b) und auch durch einen jeweiligen weiteren Drosselungskanal (21a, 21b) mit dem zugehörigen Steuereinlass (13a, 13b) verbunden ist, und wobei jeder Hilfskolben (5a, 5b) zu einer Absperrposition hin bewegt werden kann, in welcher er den zugehörigen weiteren Drosselungskanal (21a, 21b) absperrt, und von dieser Absperrposition weg bewegt werden kann, um den weiteren Drosselungskanal zum Schließen des Nadelventils zu öffnen. Einspritzventilanordnung nach Anspruch 6, wobei der Durchmesser des weiteren Drosselungskanals (21a), der zur Kolbenanordnung (4a, 5a) gehört, die zum ersten Nadelventil (2a) gehört, eine kleinere Querschnittsfläche aufweist als der weitere Drosselungskanal (21b), der zur Kolbenanordnung (4b, 5b) gehört, die zum zweiten Nadelventil (2b) gehört. Einspritzventilanordnung nach einem der vorherigen Ansprüche, wobei das Ventilgehäuse (1) mit einer Steuerdruckkammer (16a, 16b) geformt ist, die durch die Kolbenanordnungen (4a, 5a; 4b, 5b) begrenzt wird, und wobei die Anordnung außerdem Versorgungsmittel (9) umfasst, um die Steuerdruckkammern (16a, 16b) mit unter Druck stehendem Hydrauliköl zu versorgen, und ein Steuerventil (10), um die Steuerdruckkammern (16a, 16b) auf selektive Weise mit einem Raum zu verbinden, der einen wesentlich niedrigeren Druck aufweist als der Versorgungsdruck des Hydrauliköls. Einspritzventilanordnung nach einem der vorherigen Ansprüche, wobei die Hauptkolbenvorrichtung (4a) der ersten Kolbenanordnung einen kleineren Durchmesser hat als die Hauptkolbenvorrichtung (4b) der zweiten Kolbenanordnung. Einspritzventilanordnung nach Anspruch 1 oder 2, wobei das Ventilgehäuse (1) einen Hydraulikeinlass (9) zur Verbindung mit einer Quelle von unter Druck stehendem Hydrauliköl aufweist und mit ersten und zweiten Steuerdruckkammern (16a, 16b) geformt ist, die jeweils durch die erste bzw. zweite Kolbenanordnung begrenzt werden, wobei die erste und zweite Steuerdruckkammer (16a, 16b) mit den Steuereinlässen (13a, 13b) verbunden sind, wodurch die erste und zweite Kolbenanordnung durch Druck am Steuereinlass beeinflusst werden, und wobei die Anordnung außerdem ein Steuerventil (10) umfasst, um die erste und zweite Steuerdruckkammer (16a, 16b) auf selektive Weise mit einem Raum zu verbinden, der einen wesentlich niedrigeren Druck aufweist als der Druck an den Steuereinlässen (13a, 13b). Einspritzventilanordnung nach Anspruch 10, wobei die Steuereinlässe (13a, 13b) jeweils durch erste und zweite Drosselungskanäle (14a, 14b) mit der ersten bzw. zweiten Steuerdruckkammer (16a, 16b) verbunden sind. Einspritzventilanordnung nach Anspruch 10 oder 11, wobei das Steuerventil (10) ein Magnetventil ist.
Anspruch[en]
An injection valve arrangement for a combustion engine having a fuel feeding system with a common line, the injection valve arrangement including: a valve body (1) having a fuel inlet (6) for connection to the common line of the fuel feeding system and a fuel outlet; a first needle valve within the valve body (1) and including a first valve needle (2a); a first piston arrangement (4a,5a) cooperating with, and controlling operation of, the first needle valve (2a); a second needle valve within the valve body (1) and including a second valve needle (2b); and a second piston arrangement (4b,5b) cooperating with, and controlling operation of, the second needle valve (2b); wherein the first and second needle valves (2a,2b) are arranged operationally in series, with the first needle valve (2a) connected to the fuel inlet (6) of the valve body (1) for controlling supply of fuel to the second needle valve (2b) and with the second needle valve (2b) connected to the fuel outlet of the valve body for controlling injection of fuel into a cylinder of the engine, and wherein the first needle valve (2a) is arranged to open before the second needle valve (2b) during a fuel injection cycle by coordinated action of the first and second piston arrangements (4a, 5a; 4b, 5b), and

characterized in that

the valve body (1) has a control inlet (13a,13b) for connection to a control pressure (9), wherein each of said first and the second piston arrangements (4a,5a;4b,5b) comprises a main piston device (4a,4b) bounding a coupling pressure chamber (18a,18b), each main piston device (4a,4b) being between its associated valve needle (2a,2b) and its associated coupling pressure chamber (18a,18b), so that pressure in the coupling pressure chamber (18a,18b) acting on the main piston device (4a,4b) resists opening movement of the valve needle (2a,2b), and wherein each coupling pressure chamber (18a,18b) is connected to the control inlet (13a,13b) via an associated constriction channel (17a,17b).
An injection valve arrangement according to claim 1, wherein the first needle valve (2a) closes after the second needle (2b) valve during a fuel injection cycle. An injection valve arrangement according to claim 1 or 2, wherein each piston arrangement further comprises an auxiliary piston (5a,5b) and each coupling pressure chamber (18a,18b) is defined between the associated main piston device (4a,4b) and the associated auxiliary piston (5a,5b). An injection valve arrangement according to claim 3, wherein each auxiliary piston (5a,5b) is spring loaded to be urged in a direction away from the associated main piston device (4a,4b). An injection valve arrangement according to claim 3, wherein each auxiliary piston (5a,5b) is located between the associated coupling pressure chamber (18a, 18b) and an associated control pressure chamber (16a, 16b) and each of said constriction channels (17a,17b) is formed in the associated auxiliary piston (5a,5b) and opens into both the associated coupling pressure chamber (18a, 18b) and the associated control pressure chamber (16a,16b). An injection valve arrangement according to claim 5, wherein each control pressure chamber (16a,16b) is connected to the associated control inlet (13a,13b) through a respective second constriction channel (14a,14b) and also through a respective further constriction channel (21a,21b), and wherein each auxiliary piston (5a,5b) is movable to a blocking position in which it blocks the associated further constriction channel (21a,21b) and is movable away from said blocking position to open the further constriction channel for closing the needle valve. An injection valve arrangement according to claim 6, wherein the diameter of said further constriction channel (21a) associated with the piston arrangement (4a,5a) associated with the first needle valve (2a) is of smaller cross-sectional area than said further constriction channel (21b) associated with the piston arrangement (4b,5b) associated with the second needle valve (2b). An injection valve arrangement according to any one of the preceding claims, wherein the valve body (1) is formed with a control pressure chamber (16a,16b) which is bounded by the piston arrangements (4a,5a;4b,5b), and wherein the arrangement further comprises supply means (9) for supplying hydraulic oil under pressure to the control pressure chambers (16a,16b) and a control valve (10) for selectively connecting the control pressure chambers (16a, 16b) to a space at a substantially lower pressure than the supply pressure of the hydraulic oil. An injection valve arrangement according to any one of the preceding claims, wherein the main piston device (4a) of the first piston arrangement is of smaller diameter than the main piston device (4b) of the second piston arrangement. An injection valve arrangement according to claim 1 or 2, wherein the valve body (1) has a hydraulic inlet (9) for connection to a source of hydraulic oil under pressure and is formed with first and second control pressure chambers (16a, 16b) which are bounded by the first and second piston arrangements, respectively, the first and second control pressure chambers (16a, 16b) being connected to the control inlets (13a, 13b), whereby the first and second piston arrangements are influenced by pressure at the control inlet, and wherein the arrangement further comprises a control valve (10) for selectively connecting the first and second control pressure chambers (16a, 16b) to a space at a substantially lower pressure than the pressure at the control inlets (13a, 13b). An injection valve arrangement according to claim 10, wherein the control inlets (13a, 13b) are connected to the first and second control pressure chambers (16a, 16b) by first and second constriction (14a, 14b) channels, respectively. An injection valve arrangement according to claim 10 or 11, wherein said control valve (10) is a solenoid valve.
Anspruch[fr]
Configuration de vannes d'injection pour moteur à combustion muni d'un système d'alimentation en carburant doté d'une canalisation commune, la configuration de vannes d'injection comprenant: un corps de vanne (1) doté d'une arrivée de carburant (6) destinée à être reliée à la canalisation commune du système d'alimentation en carburant et une sortie de carburant ; une première vanne à pointeau située à l'intérieur du corps de vanne (1) et comprenant un premier pointeau de vanne (2a) ; une première configuration de pistons (4a, 5a) coopérant avec le premier pointeau de vanne (2a) et commandant le fonctionnement de celui-ci ; une deuxième vanne à pointeau située à l'intérieur du corps de vanne (1) et comprenant un deuxième pointeau de vanne (2b) ; et une deuxième configuration de pistons (4b, 5b) coopérant avec le deuxième pointeau de vanne (2b) et commandant le fonctionnement de celui-ci ; les premier et deuxième vannes à pointeau (2a, 2b) étant disposées fonctionnellement en série, la première vanne à pointeau (2a) étant reliée à l'arrivée de carburant (6) du corps de vanne (1) pour commander l'amenée de carburant de la deuxième vanne à pointeau (2b) et la deuxième vanne à pointeau (2b) étant reliée à la sortie de carburant du corps de vanne pour commander l'injection de carburant dans un cylindre du moteur, et la première vanne à pointeau (2a) étant disposée pour s'ouvrir avant la deuxième vanne à pointeau (2b) au cours d'un cycle d'injection de carburant par l'action coordonnée des première et deuxième configurations de pistons (4a, 5a, 4b, 5b), et

caractérisée en ce que

le corps de vanne (1) est doté d'une entrée de commande (13a, 13b) destinée à être reliée à une pression de commande (9), chacune desdites première et deuxième configurations de pistons (4a, 5a, 4b, 5b) comportant un dispositif de piston principal (4a, 4b) délimitant un compartiment de pression de couplage (18a, 18b), chaque dispositif de piston principal (4a, 4b) étant entre son pointeau de vanne (2a, 2b) associé et son compartiment de pression de couplage (18a, 18b) associé, de sorte que la pression dans le compartiment de pression de couplage (18a, 18b) agissant sur le dispositif de piston principal s'oppose au mouvement d'ouverture du pointeau de vanne (2a, 2b), et chaque compartiment de pression de couplage (18a, 18b) étant relié à l'entrée de commande (13a, 13b) via un canal à rétrécissement (17a, 17b) associé.
Configuration de vannes d'injection selon la revendication 1, la première vanne à pointeau (2a) se refermant après la deuxième vanne à pointeau (2b) au cours d'un cycle d'injection de carburant. Configuration de vannes d'injection selon la revendication 1 ou 2, chaque configuration de pistons comportant en outre un piston auxiliaire (5a, 5b) et chaque compartiment de pression de couplage (18a, 18b) étant défini entre le dispositif de piston principal (4a, 4b) associé et le piston auxiliaire (5a, 5b) associé. Configuration de vannes d'injection selon la revendication 3, chaque piston auxiliaire (5a, 5b) étant muni d'un ressort pour être sollicité dans un sens s'éloignant du dispositif de piston principal (4a, 4b) associé. Configuration de vannes d'injection selon la revendication 3, chaque piston auxiliaire (5a, 5b) étant situé entre le compartiment de pression de couplage (18a, 18b) associé et un compartiment de pression de commande (16a, 16b) associé et chacun desdits canaux à rétrécissement (17a, 17b) étant formé dans le piston auxiliaire (5a, 5b) associé et s'ouvrant à la fois dans le compartiment de pression de couplage (18a, 18b) associé et dans le compartiment de pression de commande (16a, 16b) associé. Configuration de vannes d'injection selon la revendication 5, chaque compartiment de pression de commande (16a, 16b) étant relié à l'entrée de commande (13a, 13b) associée à travers un deuxième canal à rétrécissement (14a, 14b) respectif et également à travers un canal à rétrécissement supplémentaire (21a, 21b) respectif, et chaque piston auxiliaire (5a, 5b) pouvant être amené dans une position de blocage dans laquelle il bloque le canal à rétrécissement supplémentaire (21a, 21b) associé et pouvant être éloigné de cette position de blocage pour ouvrir le canal à rétrécissement supplémentaire afin de fermer la vanne à pointeau. Configuration de vannes d'injection selon la revendication 6, le diamètre dudit canal à rétrécissement supplémentaire (21a) associé à la configuration de pistons (4a, 5a) associée à la première vanne à pointeau (2a) est de section droite plus réduite que ledit canal à rétrécissement supplémentaire (21b) associé à la configuration de pistons (4b, 5b) associée à la deuxième vanne à pointeau (2b). Configuration de vannes d'injection selon l'une quelconque des revendications précédentes, le corps de vanne (1) étant formé avec un compartiment de pression de commande (16a, 16b) délimité par les configurations de pistons (4a, 5a, 4b, 5b) et la configuration comportant en outre des moyens d'amenée (9) destinés à amener en huile hydraulique sous pression aux compartiments de pression de commande (16a, 16b) et une vanne de commande (10) destinée à relier sélectivement les compartiments de pression de commande (16a, 16b) à un espace sous une pression sensiblement inférieure à la pression d'amenée de l'huile hydraulique. Configuration de vannes d'injection selon l'une quelconque des revendications précédentes, le dispositif de piston principal (4a) de la première configuration de pistons étant de diamètre inférieur à celui du dispositif de piston principal (4b) de la deuxième configuration de pistons. Configuration de vannes d'injection selon la revendication 1 ou 2, le corps de vanne (1) étant doté d'une entrée hydraulique (9) destinée à être reliée à une source d'huile hydraulique sous pression et étant formé avec des premier et deuxième compartiments de pression de commande (16a, 16b) délimités respectivement par les première et deuxième configurations de pistons, les premier et deuxième compartiments de pression de commande (16a, 16b) étant reliés aux entrées de commande (13a, 13b), en conséquence de quoi les première et deuxième configurations de pistons sont influencées par la pression à l'entrée de commande, et la configuration comportant en outre une vanne de commande (10) destinée à relier sélectivement les premier et deuxième compartiments de pression de commande (16a, 16b) à un espace sous une pression sensiblement inférieure à la pression aux entrées de commande (13a, 13b). Configuration de vannes d'injection selon la revendication 10, les entrées de commande (13a, 13b) étant reliées aux premier et deuxième compartiments de pression de commande (16a, 16b) respectivement par les premier et deuxième canaux à rétrécissement (14a, 14b). Configuration de vannes d'injection selon la revendication 10 ou 11, ladite vanne de commande (10) étant une électrovanne.






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