WO2002025098A1

WO2002025098A1 - Control valve for fuel injectors

Info

Publication number: WO2002025098A1
Application number: PCT/EP2001/010819
Authority: WO
Inventors: Wolfgang Scheibe; Hans-Joachim Koch; Rolf Prillwitz; David Charles Jay; Kai Antero Lehtonen
Original assignee: L'orange Gmbh
Priority date: 2000-09-20
Filing date: 2001-09-19
Publication date: 2002-03-28
Also published as: ATE310161T1; EP1320678A1; EP1320678B1; DE10046829A1; JP3796219B2; DE10046829C2; DE10066102A1; JP2004509282A; DE50108105D1; DE10066102B4

Abstract

According to the invention, a control plunger (9) is provided for a control valve (8) of fuel injectors (1) for internal combustion engines. Said control plunger is provided with a support plunger (25), which is guided in an axially displaceable manner inside the control plunger (9), in order to achieve a pressure compensation in an opened and closed state and in both stroke directions. The support plunger forms a spool valve, which is located inside the connection of two channel ports, in order to configure the control valve (8) as a three/two-way directional control valve.

Description

Control valve for injection injectors

The invention relates to a control valve for injection injectors of internal combustion engines, in particular internal combustion engines operating with accumulator pressure injection and operated with diesel or heavy oil.

Injection injectors for internal combustion engines with accumulator pressure injection, with an injection nozzle and a control valve assigned to it and actuated via an actuator are known from EP 0 657 642 A2. The control valve has connection connections to the pressure accumulator, the injection nozzle and the return line and, in the function of a 3/2-way valve, connects the injection nozzle to the pressure accumulator or the return line, depending on the switching position, and, in a transition phase between the two switching positions, the injection nozzle, pressure accumulator and return line , The nozzle needle of the injection nozzle is loaded with pressure on the injection medium in the direction of its open position and with pressure on the return side in the direction of its closed position, and it opens when the connection between the pressure accumulator and the injection nozzle is switched. When pressure is applied on the return side, the closing force exerted by a closing spring on the nozzle needle is increased depending on the pressure via the pressure given on the return side, and the nozzle needle is held in its closed position as long as it is not connected to the injection nozzle when the pressure accumulator is connected, and thus the connection to the return is disconnected by pressing on the pressure side against the closing force of the spring into the opening ^' slage lifted from the seat. In this known solution, the control valve is dimensioned with respect to its pressure application surfaces in such a way that it is pressure-balanced in both stroke directions, in the open and closed state, so that only the spring forces loading the nozzle needle in the direction of its closed position can be overcome via the forces to be applied by the actuator ,

Furthermore, control valves for injection injectors are known from practice, the control piston of which controls the through connection between two channel connections in the sense of a 2/2-way valve, and with regard to pressure compensation in both stroke directions, in the open and closed state, is provided with a support piston which lies in a receiving bore which is coaxial with the control piston and is supported against a stop against which the control piston is displaceable. In the

The receiving bore is adjacent to the support piston at the through connection of the Duct connections connected support chamber, so that the chamber pressure acts on the control piston and the support piston in opposite directions and differences in the cross-sectional area of the support piston or the receiving bore can be compensated for in the control piston-side pressure application areas.

The invention has for its object to provide a control valve of the type mentioned in such a way that further channel connections can be controlled.

According to the invention, this is achieved by the features of claim 1, specifically by using the support piston as a control slide, the support piston controlling a connection between the support chamber and a further channel connection, so that the function of a 3 / 2- Directional control valve results, which extends the structural freedom with regard to the design of the control piston by the possibility of balancing the pressure application surfaces via the support piston while simultaneously using it as a control slide.

In the context of the invention, it proves to be expedient to assign the area of the control piston which receives the support piston to the area of the control piston which bears the sealing edge and which is expediently surrounded by a valve chamber as part of the passage connection between the channel connections, so that short connection paths can be realized as well as one appropriate design of the connection to the support chamber.

Appropriately, with respect to the sealing edge, a further annular chamber is delimited opposite the valve chamber via the control piston, which is preferably formed by a region of the control piston with a reduced diameter and which is assigned a channel connection, so that two of the channel connections are controlled via the sealing edge, and the third via the support piston as a control slide valve, which results in favorable conditions for influencing the flow conditions in the short circuit phase, in which the control piston moves with its sealing edge from one sealing limit to the other.

With regard to the use of the injection injector in an injection system working with accumulator pressure injection, it is particularly expedient if the high pressure is supplied to the ring area lying on the one hand of the sealing edge and the high pressure side Connection to the injection nozzle branches off from the valve chamber, from which the return branch, which is controlled via the support piston, branches, the cross-section of the return-side channel connection being determined as a function of the axial relative position of the support piston with respect to the control piston.

For the formation of the support piston it proves to be expedient if it has a sealing surface which is assigned to the receiving bore and which is designed as a conical sealing zone.

Further details and features of the invention emerge from the claims. Furthermore, the invention is explained below with the aid of an exemplary embodiment with further details. Show it:

Figure 1 is a schematic sectional view showing the basic structure of an injection injector according to the invention, Figure 2 is a highly schematic sectional view of a section of the

Injection injector in the control piston area of the control valve, this section being indicated by A in FIG. 1, and FIG. 3 is a further enlargement of section, now section B in FIG

Second

In the figures, 1 denotes the injection injector, which, as the schematic representation according to FIG. 1 shows, has an injection nozzle 2 with a nozzle needle 3, which is loaded in the direction of its closed position via a spring arrangement 5 provided in a spring chamber 4, whereby at the Spring chamber 4 connects a pressure chamber 6 in the opposite direction to the nozzle needle 3, in which a hold-down piston 7 loading the spring arrangement 5 in the direction of the closed position of the nozzle needle 3 is arranged when pressure is applied.

Furthermore, the injection injector 1 comprises a control valve 8 with a control piston 9. The connections to the high and low pressure side are controlled via the control valve 8, the injection injector 1 being connected on the high pressure side to a high pressure accumulator (not shown), as is the case for accumulator pressure systems, in the form of common -Rail systems, for example, is known.

The control valve 8 is actuated via a magnetic actuator 10, with a servo control valve 11 being used in the exemplary embodiment for power amplification is interposed, as can be used in particular when the required control forces cannot be made available via magnetic adjuster 10 and / or the switching operations are too slow. If such a servo control valve 11 is used, then a separate pressure supply is preferably assigned to it, which is not discussed in more detail here.

The supply channel connections assigned to the control valve 8 and controlled via the control piston 9 are designated 12 to 14 and are illustrated in particular in FIG. 2, the channel connection 12 representing the inlet on the high-pressure side and establishing the connection to the high-pressure accumulator. The connection 13 lies in the connection to the injection nozzle 2, the associated channel 15, as illustrated schematically in FIG. 1, opening out onto the pressure chamber 16, so that the pressure needle 17 of the nozzle needle 3 counteracts the latter with a corresponding pressurization in the opening direction, inter alia through the spring assembly 5 applied closing force is raised.

The return takes place via the channel connection 14, the associated return channel 18 opening out via a pressure holding valve 19 onto a storage tank (not shown) and being connected to the pressure chamber 6 via a spur line 20. From the pressure chamber 6 there is also a throttle duct 21 leading to the low-pressure side, which on the low-pressure side at least up to the pressure chamber 6 ensures a predetermined minimum pressure which is dependent on the inflow onto the duct 14 and / or, as a combined throttle valve.

The control piston 9 has, concentrically with the piston axis 22, a receiving bore 24 extending from its end face 23, in which a support piston 25 is axially displaceably supported against a support beam 26 fixed to the housing and bridging the receiving bore 24, which in turn is supported by support fingers 27 of the actuating piston 28 of the servo control valve 11, which is supported against the end face 23 of the control piston 9. The support beam 26 lies in the transition between a lower housing part 29, which forms the receptacle for the control piston 9, and an upper housing part 30. The housing parts 29, 30 are braced against one another via a flat surface.

In the control piston 9, the channel connection 12 is assigned an annular space 31 with a reduced diameter, which acts against the valve chamber 32 assigned to the channel connection 13 is delimited by a sealing edge 33 of the control piston 9, which, with a corresponding valve seat on the housing, forms the sealing boundary between the channel connections 12 and 13, which releases the connection between the channel connections 12 and 13 when the support piston 9 is raised in the direction of the upper housing part 30 and thereby releases the injection medium feeds the channel 15 to the pressure chamber 16 so that the nozzle needle 3 is raised in the opening direction against the force of the spring arrangement 5.

According to the stroke of the control piston 9, there is an axial offset between the control piston 9 and the support piston 25 arranged in the receiving bore 24, which is designed as a control slide and controls the connection between the valve chamber 32 and the return-side channel connection 14. For this purpose, the support chamber 34, which is delimited via the support piston 25 opposite the support beam 26 in the receiving bore 24 and is connected to the valve chamber 32 via a transverse channel 35, is controllably connected to the return-side channel connection 14, for which purpose the support piston 25 as a control slide is conical in the exemplary embodiment Sealing surface 36 is assigned, which corresponds to a seat surface 37 in the transition to the transverse channel 35 on the part of the receiving bore 24, so that when the support piston 25 is retracted into the control piston 9 in the direction of the seat surface 37 of the receiving bore 24, the flow connection between the valve chamber 32 and the channel connection 14 Is blocked. When the sealing boundary formed by the sealing surface 36 and the seating surface 37 is open, the support chamber 34 is connected via connecting channels 38 to an annular channel 39 which is arranged in the circumference of the supporting piston 25 and which lies in the axial overlap region to radial connecting bores 40 which run out onto the channel connections 14.

With respect to the stroke of the support piston 25 as a control slide relative to the control piston 9, the opening cross section 41 in the described solution can be in the sealing zone formed by the sealing surface 36 and the seat surface 37 and the overlap cross section 42 of the annular channel 39 to the connecting bores 40 both in terms of their maximum size and also vary in relation to each other depending on the stroke, so that the connection from the valve chamber 32 to the return-side connection 4 can not only be throttled, but can also be controlled in a stroke-dependent manner with regard to the degree of throttle, which influences the opening and closing behavior of the nozzle needle 3 when the control valve 8 is switched over can be, but in particular also influence the opening and Closing behavior of the nozzle needle 3 can be taken in the changeover phase if both the connection between the connections 12 and 13 and between the connections 13 and 14 is released, so that a short-circuit condition is given.

It can be assumed here that when an injection is initiated, the control piston 9 releases an increasingly larger flow cross-section via the sealing edge 33, so that the pressure in the duct 15 rises rapidly. The flow connection to the connection 14 on the low pressure side is also still open, but via the pressure holding valve 19 and the throttle duct 21 it is ensured that the holding piston 7 is pressurized accordingly and thus, in addition to the spring arrangement 5, the nozzle needle 3 still holds in its closed position. This also applies to other operating conditions with a corresponding pressurization of the hold-down piston 7, even if the function of the quantity-limiting valve mentioned below has not yet been activated, that is, it has not yet shut off, but instead only assumes a reversible intermediate position upstream of the shut-off position.

With a further stroke of the control piston 9, the flow cross-section between the channel connections 12 and 13 increases, but at the same time the connection between the channel connections 13 and 14 is increasingly controlled by the support piston 25 acting as a control slide. The return-side pressure drops accordingly and the closing force / pressure component applied via the hold-down piston 7 decreases. Since the pressure in the duct 15 increases at the same time, the nozzle needle 3 can lift off and the injection can begin.

This point in time (start of injection) is selected and the corresponding cross sections are coordinated such that if the control piston 9 remains in a corresponding stroke position due to a malfunction, or in an intermediate stroke division going beyond this, and consequent continuous injection, the fuel quantity flowing through, preferably including the portion flowing out via the return flow is greater than the amount of fuel that would result from the functionally timed injection of the maximum permissible injection amount, so that an unillustrated flow control valve located in the high-pressure side inlet would respond and shut off the high-pressure side inlet. A particularly sensitive control is possible by taking into account the portion flowing off via the return. At the end of the injection, the control piston 9 is spring-loaded, indicated by the spring 43 in FIG. 2, and moved by the pressure applied by the servo control valve 11 in the direction of its starting position shown in the drawings, in which the connection between the channel connections 12 and 13 is made the sealing edge 33 is shut off. This also moves the support piston 25 with respect to the control piston 9, so that the hold-down piston 7 is acted upon by the pressure build-up in the pressure chamber 6 and superimposed on the force of the spring arrangement 5, the nozzle needle 3 is loaded in the closing direction, thus controlling the injection.

In the invention, the support piston 25 used to compensate for differently sized pressurized surfaces of the control piston and the resulting actuating forces is used as a control slide, so that pressure support is achieved via the support piston 25 not only in both stroke directions, in the open and in the closed state, but at the same time additional control functions are performed, which leads to a simplified overall construction.

Claims

claims

1.Control valve for injection injectors of internal combustion engines, in particular internal combustion engines operating with accumulator pressure injection, operated with diesel or heavy oil, with a control piston which is displaceable in a guide bore and which controls the passage connection between two channel connections with a sealing edge and in turn guides the guide for a support piston lying in a coaxial receiving bore forms, which is supported on the one hand against a stop against which the control piston is displaceable, and on the other hand delimits a support chamber connected to the passage connection in the receiving bore, characterized in that the support piston (25) for the function of the control valve as a 3/2-way valve forms a control slide which controls a connection between the support chamber (34) and a further channel connection (14).

2. Control valve according to claim 1, characterized in that the support piston (25) is assigned to the area of the control piston (9) carrying the sealing edge (33).

3. Control valve according to claim 2, characterized in that the area of the control piston (9) receiving the support piston (25) has a larger diameter than the guide area of the control piston (9) opposite in relation to the sealing edge (33).

4. Control valve according to claim 2 or 3, characterized in that the control piston (9) in its enlarged in diameter, to the sealing edge (33) adjoining area is enclosed by a valve chamber (32) as part of the passage connection.

5. Control valve according to claim 4, characterized in that the valve chamber (32) is assigned a channel connection (13) and the connection to the support chamber (34).

6. Control valve according to claim 4 or 5, characterized in that the control piston (9) in the, in the guide area, a reduced diameter ring area (annular space 31) is assigned.

7. Control valve according to claim 6, characterized in that a channel connection (12) is assigned to the reduced diameter ring area (annular space 31).

8. Control valve according to claim 6 or 7, characterized in that the annular space (31) is provided adjacent to the sealing edge (33).

9. Control valve according to one of the preceding claims, characterized in that the support piston (25) in its position in the control piston (9) retracted position controls the connection between the valve chamber (32) and the further channel connection (14).

10. Control valve according to claim 9, characterized in that the connection running via the support piston (25) to the further channel connection (14) forms a throttle section.

11. Control valve according to claim 9 or 10, characterized in that the sealing boundary between the supporting piston (25) and the receiving bore (24) is formed by a seat (seat surface 37) of the receiving bore (24) associated sealing surface (36) of the supporting piston (25) ,

12. Control valve according to claim 11, characterized in that the sealing surface (36) of the support body (25) is conical.

13. Control valve according to claim 11 or 12, characterized in that the seat surface (37) of the receiving bore (24) is conical.

14. Control valve according to one of claims 11 to 13, characterized in that the sealing boundary (sealing surface 36, seating surface 37) between the supporting piston (25) and the receiving bore (24) is assigned an annular space (supporting chamber 34) which is connected to an axially spaced annular channel ( 39) lies in the transition between the support piston (25) and control piston (9) to the further channel connection (14).

15. Control valve according to claim 14, characterized in that the annular channel (39) lies in the axial overlap area with radial connecting bores (40).

16. Control valve according to one of claims 11 to 15, characterized in that the free overflow cross-sections of the connection running via control piston (9) and support piston (25) are variable depending on the stroke.

17. Control valve according to one of the preceding claims, characterized in that the connection of the high-pressure side channel connection (12) with the injection nozzle (2) leading channel connection (13) of the injection injector via the sealing edge (33) of the control piston (9) and that further duct connection (14) forms a return connection.

18. Control valve according to claim 17, characterized in that the return connection (14) is connected to a pressure chamber (6) which is assigned to the rear of the nozzle needle (3) of the injection nozzle (2), such that the pressure chamber (6) pressure pending loads the nozzle needle (3) in the closing direction.