EP0937203A1

EP0937203A1 - Fuel injection valve

Info

Publication number: EP0937203A1
Application number: EP98916807A
Authority: EP
Inventors: Detlev Potz; Stephan Haas; Thomas Kuegler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-09-11
Filing date: 1998-02-27
Publication date: 1999-08-25
Anticipated expiration: 2018-02-27
Also published as: JP2001504915A; WO1999013214A1; US6105879A; DE59804130D1; EP0937203B1; DE19739905A1

Abstract

The invention relates to a fuel injection valve for internal combustion engines comprising a valve member (5) moving outwards from the valve body (1). At least two axially superimposed rows of injection holes (23) are provided for on said valve member, which holes can be controlled in sequence during the opening stroke directed towards the outside of the valve member (5). The valve further comprises a two-stage hydraulic valve lift stop which delimits the opening stroke path of the valve member (5) and is configured as a hydraulic damping chamber (39) with controllable relief. Relief is obtained by means of at least two ground faces (51, 59) on the valve member (5) which can be controlled in sequence during the opening stroke of the valve member (5). At least one of said ground faces can be connected to a low-pressure chamber via a relief channel (63) containing a valve (65).

Description

Fuel injector

State of the art

The invention is based on a fuel injection valve for internal combustion engines according to the preamble of claim 1. In such a fuel injector, known from an earlier German patent application with the file number DE-196 42 440.2, a piston-shaped valve member is axially displaceable outwardly against a return spring in a bore of the valve body projecting into the combustion chamber. The valve member on its combustion chamber end has a closing head which projects from the bore and forms a valve closing member and which has a valve sealing surface on its side facing the valve body. With this valve sealing surface, the valve member interacts with a valve seat surface arranged on the end face of the valve body on the combustion chamber side. Furthermore, two rows of injection openings arranged one above the other are provided on the closing head of the valve member, the outlet openings of which are covered by the valve body in the closed position of the valve member and are released in succession during the outward opening stroke. For a defined control of the individual rows of spray holes, the known fuel injection valve has a two-stage that limits the opening stroke of the valve member hydraulic stroke stop, which is designed as a hydraulic damping chamber with controllable relief. The relief line can be connected to the damping chamber via two recesses on the valve member, this connection being able to be controlled in succession during the opening stroke movement of the valve member. For this purpose, the recesses in the known fuel injection valve are designed as two surface grindings on the valve member which protrude with their upper ends into the damping space. The upper ends of the bevels form control edges, which successively emerge from the overlap with the damping space during the valve member opening stroke movement and are closed by the wall of the valve body. A first bevel is permanently connected to the relief line with its lower end, while the second bevel with its lower boundary edge only dips into the overlap with the relief line after a certain opening stroke movement has been completed. In this way, a known two-stage hydraulic blocking of the valve member is achieved in the known fuel injection valve, a first

The control position on the damping chamber corresponds to the opening of the first spray hole row, while the final hydraulically blocked end position of the valve member corresponds to the opening of both spray hole rows and thus the opening of the entire injection cross section.

However, the known fuel injection valve has the disadvantage that the recesses on the valve member have to be made very precisely in order to ensure precise control of the rows of spray holes via the precise arrangement of the many control edges. In addition, in the known fuel injection valve, the injection pressure-dependent blocking of the valve member in intermediate positions cannot be adjusted for operational reasons, which requires complex geometric adaptation work on the hydraulic stroke strikes. Thus, the control of a multi-stage opening stroke course of the valve member, which is necessary for the so-called vario register nozzles, can only be implemented in a very complex manner in terms of production technology, depending on the fuel injection pressure applied to the valve.

Advantages of the invention

The fuel injector according to the invention for

Internal combustion engines with the characterizing features of claim 1 have the advantage that the second opening stroke phase of the valve member is adjustable and controllable via a valve inserted into the relief line. In addition, a third control edge, which controls the start of the second opening stroke phase, can be dispensed with, so that the manufacturing outlay of the recesses on the valve member can be greatly reduced compared to the known solution. The reduction of the control edges also causes a stable one

Long-term operating behavior due to the lower influenceability due to geometric inaccuracies in the control recesses. Furthermore, the configuration of the recesses according to the invention also has the advantage that both control edges are each arranged at the upper end of the recesses and can therefore be easily manufactured. The time of the beginning of the second opening stroke phase of the valve member can be easily determined by designing the bore diameter of the relief line and the valve design, e.g. adjust the design of the valve spring strength of the valve in the relief line.

However, it is particularly advantageous if the opening time or the closing characteristic of the valve, which is preferably designed as a pressure valve, in the relief line to be able to adjust as a function of the map during operation of the injection valve, in order to be able to continuously control the second opening stroke phase on the valve member of the injection valve. For this purpose, the pressure valve can advantageously be controlled directly by an electrical actuator, which can be designed, for example, as a piezo actuator. Another alternative to this is the direct connection of the valve member of the pressure valve to the armature in a current-carrying coil (solenoid valve), the basic settings being able to be made in each case via a spring. Furthermore, direct control of the pressure valve in the relief line is hydraulically possible, with a regulated hydraulic back pressure being applied to the back of the pressure valve, by means of which the pressure valve can be opened or closed as a result of the pressure difference between the pressure upstream of the pressure valve and the back pressure behind it.

Another advantageous setting option of the valve in the relief line is the map-controllable adjustment of the spring preload of the valve spring

Pressure valve. For this purpose, the spring preload can be continuously adjusted by means of an adjustable spring support surface, which can be axially displaced, for example, electrically by a piezo actuator or the armature in a magnetic coil or hydraulically by a piston in a working area. In order to ensure a safe refilling of the damping chamber acting as the control chamber with fuel during the closing movement of the valve member of the injection valve, a check valve is also advantageously used in an inlet line of the damping chamber, which on the other hand is connected to the low-pressure fuel circuit, preferably the spring chamber of the injection valve is. This check valve also prevents the creation of a negative pressure in the damping chamber and thus cavitation damage and a unintentional reverberation of the injection valve member when closing.

Another advantageous alternative embodiment of the valve in the relief line is its design as an evasive piston. The valve member of the valve in the relief line, designed as an evasive piston, releases a defined evasive volume during its opening stroke movement, by means of which the pressure in the damping space of the injection valve drops and thus the second Opening stroke path allows. This embodiment variant has the advantage that the control volume is refilled in a simple form from the evasive volume during the closing stroke of the injection valve member. In addition, the pressure drop in the damping chamber can be precisely limited, which means that when the damping chamber is finally closed when the injection valve member reaches the end stroke position, the pressure builds up faster, which shortens the stopping distance of the valve member of the injection valve. Another advantage of this variant is that the sealing function from the escape volume to the leak oil chamber (e.g. spring chamber) is ensured by the outer surface of the escape piston and from the relief line to the escape volume by a conical seat.

A further advantage is achieved by the oblique formation of the upper ends of the surface grindings in the valve member, which cause the opening cross-section to gradually decrease towards the damping chamber and thus avoid pressure vibrations and the resulting vibrations on the valve member. The valve spring is designed to be block-proof in order to ensure that the damping chamber has emergency running shadow on the fuel injection valve for the first filling. A further advantage is achieved by arranging the damping space in an intermediate disk between the valve body and a valve holding body, as a result of which the manufacture or manufacture of the damping space and relief channel is relatively simple.

The damping or control chamber is bounded on its side facing away from the end face of the valve body by a piston which can be displaced axially with the valve member and which is advantageously formed by a sealing ring pressed onto the valve member. This sealing ring attached to the valve member slides sealingly with its outer circumference in a bore in the intermediate disk which forms the damping space. The sealing ring is advantageously open to the damping chamber

U-shaped sealing ring, which is preferably made of a PTFE material. In addition, a spring for basic sealing is inserted into this sealing ring, the sealing of the sealing ring against the wall of the intermediate disk increasing with increasing due to the U-shaped hollow profile

Hydraulic pressure in the damping chamber is increased. A relief channel which relieves the damping space is likewise advantageously integrated into the intermediate disk, the pressure valve controlling this relief channel also being provided in the intermediate disk. This pressure valve is preferably designed as a piston check valve, the opening pressure or the opening time being adjustable as the start of the second valve member opening stroke phase via the design of the pressure valve spring. A throttle point is also advantageously connected upstream of the pressure valve. The stroke of the piston in the pressure valve is advantageously limited to the minimum necessary stroke and the piston is also made of light materials in order to keep wear and vibrations on the pressure valve as low as possible. In order to ensure a secure connection between the ground bevels and the relief duct, it is necessary to secure the valve member against unintentional twisting. This anti-rotation device is advantageously arranged in a lightly loaded area, preferably between the upper valve member guide and the fuel injection valve spring or between this spring and the valve member end. For this purpose, the valve member has recesses, preferably an even number of cuts, which engages in a molded part arranged in the valve body holder with complementary formations. This fitting can be easily adapted to the actual position of the valve member during assembly of the fuel injection valve and thus enables a small distance between the valve member and the rotational position fixing, so that very precise guidance with little wear on the valve member is possible. It is particularly advantageous to integrate this fitting into the intermediate disc between the valve body and the valve holding body.

Further advantages and advantageous configurations of the subject matter of the invention can be gathered from the description, the drawing and the patent claims.

drawing

Nine exemplary embodiments of the fuel injection valve according to the invention for internal combustion engines are shown in the drawing and are explained in more detail in the following description.

FIGS. 1 and 2 show a known fuel injection valve of the vario-register nozzle type in various Sectional views, Figures 3 and 4 enlarged sections of a first embodiment of the fuel injection valve of Figure 1 in the area of the damping chamber with a valve in the relief line, the sectional view of Figure 4 by 90 ° from the

3, FIGS. 5 and 6 an anti-rotation device on the valve member of the fuel injection valve in two views, FIG. 7 shows a second exemplary embodiment analogous to the representation of FIG. 3, in which the valve in the relief line is directly controlled via a piezo actuator FIG. 8 shows a third exemplary embodiment in which the valve member is actuated by a solenoid valve, FIG. 9 shows a fourth exemplary embodiment in which the opening of the valve in the relief line can be adjusted by means of a hydraulic counterpressure on the pressure valve, and FIG. 10 shows a fifth exemplary embodiment 11, in which the spring pretensioning force of the valve in the relief line is adjusted via a piezo actuator, FIG. 11 shows a sixth exemplary embodiment in which the adjustment of the

The spring preload force of the relief valve takes place via a magnet armature, FIG. 12 shows a seventh exemplary embodiment in which the spring preload force of the relief valve is adjusted via a hydraulic actuating piston; FIGS. 13 and 14 show an eighth exemplary embodiment in two views, in which an additional check valve is fed into an inlet line of the Damping chamber is used and Figure 15 is a ninth embodiment in which the valve member of the valve in the relief line is designed as an escape piston.

Description of the embodiments

Figures 1 and 2 show a known fuel injection valve of the outward opening type with two successively controllable rows of spray holes (vario register nozzle) on which the control of the valve member stroke according to the invention is implemented.

For this purpose, the fuel injection valve has a valve body 1, which projects with its lower free end into the combustion chamber of the internal combustion engine to be supplied. The valve body 1 has an axial through bore 3, in which a piston-shaped valve member 5 is axially displaceably guided. At its lower end on the combustion chamber side, the valve member 5 has a closing head 7, which projects out of the bore 3 and has an enlarged cross section, which forms a valve closing member. This closing head 7, shown enlarged in FIG. 2, forms with its annular end face facing the valve body 1 a valve sealing face 9, which cooperates with a stationary valve seat face 11, which is formed on the end face of the valve body 1 on the combustion chamber side, surrounding the bore 3. The valve sealing surface 9 and the valve seat surface 11 that result in a sealing cross section are conical, the cone angles of the two contact surfaces 9, 11 differing slightly from one another, so that a defined sealing edge is formed. Between the wall of the bore 3 and the stem of the valve member 5, an annular pressure chamber 13 is formed, which on the combustion chamber side is enlarged by a widening of the diameter of the valve member 5 forming an annular shoulder 15 at its transition into the closing head 7 and on the other hand by a cross-sectional expansion 17 of the valve member 5 the bore 3 is limited. This pressure chamber 13 can be filled with high-pressure fuel via a pressure channel 19, for which purpose the pressure channel 19 is connected in a manner not shown to an injection line of an injection pump. Injection channels 21 lead from the annular shoulder 15 delimiting the pressure space 13 and are initially designed as a longitudinal bore in the closing head 7 of the valve member 5 and from which control bores are then located at the level of the sealing edge dissipate. The outlet openings 23 (spray holes) of the injection channels (21) are arranged above the valve sealing surface 9 on the lateral surface of the closing head 7 so that they are covered by the wall of the bore 3 in the closed position of the injection valve, that is to say when the valve member 5 is in contact with the valve seat 11 can only be opened during the outward opening stroke of the valve member 5 by emerging from the bore 3 of the valve body 1. In addition, two rows of rows (spray hole rows) of outlet openings 23, which are arranged one above the other in the axial direction of the valve member 5, are preferably provided, which are opened one after the other during the valve member opening stroke movement. Alternatively, instead of the rows of spray holes lying one above the other, longitudinal slots are also possible as injection openings, the cross-section of which is then opened analogously in at least two stages.

The piston-shaped valve member 5 protrudes with its stem part facing away from the combustion chamber from the valve body 1 into a bore which forms a spring chamber 25 and is enlarged in cross section in a valve holding body 27 which is clamped axially against the valve body 1 by means of a clamping nut 29. A valve closing spring 31 is clamped in the spring chamber 25 in such a way that its end near the combustion chamber is supported against the valve body 1 and with its end remote from the combustion chamber it acts on a valve plate 33 on the valve member 5 and the valve member 5 is thus pressed against the valve seat 11 in contact holds. Furthermore, the valve holding body 27 is axially penetrated by the pressure channel 19, a fuel filter 35 being inserted into the pressure channel 19 at the upper end of the valve holding body 27.

In order to limit the outward opening stroke movement of the valve member 5, the valve member 5 points out of the valve body 1 into the valve body 1 facing away from the combustion chamber Valve holding body 27 projecting end a piston 37 projecting radially from the valve member shaft, which delimits a hydraulic damping space 39.

This is the damping space 39, as in the first

Embodiment shown in Figures 3 and 4, provided according to the invention in an intermediate plate 41 which is clamped axially between an end surface 43 of the valve body 1 remote from the combustion chamber and the end surface of the valve holding body 27 on the combustion chamber side. The washer

41 has a part of the pressure channel 19 in the form of an axial through hole. Furthermore, the intermediate disk 41 has a central through opening 45, through which the stem of the valve member 5 projects and which delimits the damping space 39 radially outward. The damping space 39 in the intermediate disk 41 is axially delimited on the one hand by the end face 43 of the valve body 1 and on the other hand by the valve member piston 37. This piston 37 is formed by a sealing ring pressed onto the stem of the valve member 5, which is designed as a U-sealing ring 47 that is open to the damping chamber 39. A spring 49 is inserted in this U-sealing ring 47 for basic sealing.

The damping chamber 39 is filled and relieved via the fuel channels shown in FIGS. 3 and 4, which are connected to the low-pressure circuit of the injection system and for the explanation of which the fuel injection valve in FIG. 4 is rotated by 90 ° in relation to the illustration in FIG. 3.

The damping chamber 39 is filled and relieved via two cuts on the valve member 5, which connect the damping chamber 39 to a low-pressure chamber, preferably the fuel-filled spring chamber 25, via relief channels. A first bevel 51 is arranged on the valve member 5 so that when the injection valve is closed, that is to say when the valve member 5 is in contact with the valve seat 11, its upper end projects into the damping chamber 39, while its lower end opens into an annular groove 53 on the valve member 5. As shown in more detail in FIG. 4, this annular groove 53 sweeps over the mouth of a first relief channel 55, which opens into the spring chamber 25 and penetrates the valve body 1, the intermediate disk 41 and the valve holding body 27. The upper end of the first, away from the combustion chamber

The bevel 51 forms with its upper boundary edge a first control edge 57 which interacts with the end face 43 of the valve body 1. Passing over the first control edge 57 over the end face 43 corresponds to a valve member opening stroke position in which the first row of spray holes located below is opened, so that the distance between the control edge 57 and the end face 43 corresponds to a first opening stroke path in a first opening stroke phase of the valve member 5. In order to avoid vibrations in the system, the first bevel 51 runs obliquely in the direction of the first control edge 57. Offset to the first bevel 51, the valve member 5 has a second bevel 59, the upper boundary edge remote from the combustion chamber forming a second control edge 61. With its lower end facing the combustion chamber of the internal combustion engine to be supplied, the second bevel 59 continuously covers the mouth of a second relief channel 63, which also extends through the valve body 1, the intermediate disk 41 and the valve holding body 27 to the spring chamber 25. The second control edge 61 is at a greater distance from the end face 43 of the valve body 1 than the first control edge 57. The passage of the second control edge 61 over the end face 43 corresponds to the opening stroke position of the valve member 5, in which both rows of spray holes are controlled at the injection cross section, whereby to Driving over the second control edge 61 over the end face 43 of the damping chamber 39 is finally closed hydraulically and thus determines the maximum opening stroke position of the valve member. To adjust the second opening stroke phase following the first opening stroke phase and an intermediate delay, a valve 65 is inserted into the second relief line 63, which in the first exemplary embodiment is designed as a check valve. This valve 65, which is inserted in the part of the second relief channel 63 that runs in the intermediate disk 41, has an axially displaceable, piston-shaped valve member 67, which has a conical sealing surface 69 at its end facing the second ground section 59, with which it cooperates with a valve seat surface 71 . A valve spring 72 acts on the rear side of the valve member 67, which on the other hand is supported in a stationary manner on the valve holding body 27 and by means of the design of which the opening pressure on the valve 65 can be adjusted. The opening pressure at valve 65 can be used to set the point in time at which the second opening stroke phase is to begin at valve member 5, during which the complete opening cross section is opened at the injection valve. Furthermore, the second relief channel 63 between the valve 65 and the second bevel 59 is at least partially designed as a throttle cross section.

In order to prevent the valve member 5 from rotating independently and thus to ensure the connection between the grindings 51, 59 and the inlet opening to the relief channels 55, 63, a rotation lock is also provided on the valve member 5. This anti-rotation device is, as shown in the two views in FIGS. 5 and 6, formed as a profile 73 on the valve member 5, with which the valve member 5 projects into a complementary recess 75 in the intermediate disk 41. The fuel injection valve according to the invention works in the following way. In the closed position of the injection valve, the valve spring 31 holds the valve member 5 with its valve sealing surface 9 in contact with the valve seat 11, the piston 37 delimiting the damping chamber 39 is in its starting position and the damping chamber 39 is via the first bevel 51, the annular groove 53 and the first relief channel 55 connected to the fuel-filled spring chamber 25 (low pressure chamber) and filled by this with fuel that serves as a hydraulic working fluid.

At the start of the injection, fuel under high pressure passes through the pressure channel 19 into the pressure chamber 13, where it acts in a known manner on the valve member 5 on the annular shoulder 15 in the opening direction. When a certain injection pressure in the pressure chamber 13 is reached, the pressure force of the fuel acting on the valve member 5 exceeds the restoring force of the valve spring 31 and the valve member 5 lifts outwards from the valve seat 11. After a short idle stroke of the valve member 5, the outlet openings 23A of the lower row of injection holes in the injection channels 21 are released, so that the fuel is injected into the combustion chamber of the internal combustion engine to be supplied. This first opening stroke phase is ended by driving over the first control edge 57 on the first bevel 51 over the end face 43 of the valve body 1, the damping chamber 39 being closed briefly when the first bevel 51 is completely immersed in the valve body 1 and thereby acting as a hydraulic damper, which blocks a further opening stroke movement of the valve member 5. In this position, which opens a partial cross-section on the injection valve, the valve member 5 remains in a first operating mode of the injection valve, which is the idling range and corresponds to a partial load range of the internal combustion engine to be supplied.

If the entire opening cross-section on the injection valve is to be opened at higher load or speed of the internal combustion engine, the second operating mode is selected on the injection valve. In this case, the valve member 5 remains only briefly in the intermediate position with a simultaneously increasing fuel injection pressure in the pressure chamber 13 of the injection valve. When a second opening pressure limit value in the pressure chamber 13 is exceeded, the force acting on the annular shoulder 15 in the opening direction on the valve member 5 or, proportionally, the pressure in the damping chamber 39 exceeds the locking force on the valve 65 in the second relief channel 63, which has so far been constantly connected to the damping chamber 39.

When the valve 65 is opened, part of the pressure medium is relieved again from the damping chamber 39 via the second bevel 59 and the second relief channel 63 into the spring chamber 25, so that the valve member 5 continues the opening stroke movement in a second opening stroke phase. The upper outlet openings 23B of the injection channels 21 are now opened, so that both rows of spray holes and thus the entire injection cross section are opened. In order to be able to control this second opening stroke phase more precisely, the fuel flowing out via the second bevel 59 is throttled in front of the valve 65 in the second relief channel 63. The opening stroke movement of the valve member 5 is ended when the second control edge 61 is passed over on the second bevel 59 over the end face 43 of the valve body 1, the damping chamber 39 now being finally closed hydraulically and thus limiting the opening stroke movement of the valve member. This reaching the maximum opening stroke stop takes place in an advantageous manner damped, the degree of damping on the valve member depending on the modulus of elasticity of the fuel.

When the closing stroke of the valve member 5 follows after the high-pressure fuel supply has ended, the bevels 51 and 59 are again immersed in the overlap with the damping chamber 39, so that this is again filled with fuel from the spring chamber 25 via the first bevel 51 and the first relief channel 55.

The arrangement according to the invention of a valve in the second relief channel allows the pause between the two opening stroke phases and the second opening stroke phase of the valve member to be set very precisely, with at least one injection taking place between the two operating modes of the injection valve (half injection cross section - total opening cross section). Alternatively, further intermediate positions of the opening stroke position of the valve member are possible by providing further hydraulic stops.

The second exemplary embodiment shown in FIG. 7, analogous to the representation in FIG. 3, differs from the first exemplary embodiment by the direct control of the valve 65 in the relief channel 63

Valve member 67 has a piston rod 77, which is fastened to an actuator 79 of a piezo actuator, which is supported in the housing valve in the closing direction of the valve member 67. The valve spring 72 acts on the piezo actuator 79, prestresses it and holds the valve member 67 in contact with the valve seat. The electrical actuation of the piezo actuator 79 takes place as a function of a characteristic diagram of the internal combustion engine to be supplied and as a function of the instantaneous injection, an adjustment being possible even during an injection process. The connection between the piezo actuator 79 and the valve member 67, 77 can also be made via transmission elements.

In the third shown in Figure 8

In the exemplary embodiment, the valve member 67 of the valve 65 is actuated in the second relief channel 63 via a solenoid valve, the rod 77 of the pressure valve member 67 being connected to an armature 81 or forming part of it. This armature 81 projects into a current-carrying coil 83 of the solenoid valve, so that the position of the armature 81 and thus of the valve member 67 can be adjusted by the controlled change in the applied electrical voltage. The basic setting of the valve can be carried out by an additional adjusting spring 85 in addition to the valve spring 72.

In the fourth exemplary embodiment of the fuel injection valve according to the invention shown in FIG. 9, the setting of the

Valve 65 in the second relief channel 63 by the application of an adjustable hydraulic counterpressure to the spring-side rear side of the valve member 67. In this case, this pressure, which counteracts the pressure in the damping chamber 39, is built up in an additional hydraulic system in a manner not shown, and the valve 65 via the control line 87 fed. The opening movement of the valve member 67 can thus be adjusted by the pressure difference between the damping chamber 39 and the back pressure in the control line 87 in addition to the force of the valve spring 72.

In the exemplary embodiments shown in FIGS. 10 to 12, the opening time or the closing characteristic is set on the valve 65 in the second relief channel 63 via the characteristic map. dependent adjustment of the spring preload force of the valve spring 72.

In this case, in a fifth exemplary embodiment shown in FIG. 10, this adjustment of the spring pretensioning force takes place by means of a piezo actuator 89 which is inserted above the valve member 67 into the spring chamber of the valve 65 and which is pretensioned by the valve spring 72, the valve spring 72 being over a Adjusting washer 91 is supported directly on piezo actuator 89.

By means of a correspondingly controlled energization of the piezo actuator 89, its axial extension and thus the spring preload force of the valve spring 72 can now be set.

In the sixth shown in FIG. 11

In the exemplary embodiment, the spring preload of the valve spring 72 of the valve 65 is set in the second relief channel 63 by a magnet armature 93, which is axially displaceably guided in a current-carrying coil 95. In this case, the piston-shaped armature 93 forms with its valve-side end face a spring support surface on which the valve spring 72 is supported, which on the other hand engages an annular shoulder of the valve member 67. The axial position of the armature 93 and thus the pretensioning force of the valve spring 72 can now be set by varying the electrical voltage of the coil 95

FIG. 12 shows a seventh exemplary embodiment in which the axial adjustment of the spring contact surface of the valve spring 72 of the valve 65 in the second relief channel 63 is carried out hydraulically. For this purpose, the spring support surface is provided on a piston 97, on one end face of which the valve spring 72 rests and the other end face of which limits a hydraulic working space 99. This work space 99 is from a control line 101 a hydraulic system can be filled with a pressurized hydraulic fluid, the pressure supply being adjustable depending on the operating map of the internal combustion engine. The axial adjustment of the piston 97 and thus the adjustment of the biasing force of the valve spring 72 now takes place through the controlled pressure supply or relief in the working space 99.

The eighth exemplary embodiment shown in FIGS. 13 and 14 in two views has, in addition to the previous exemplary embodiments, a further inlet line 103 in the intermediate disk 41, which continuously opens into the damping chamber 39 starting from the spring chamber 25 filled with lower pressure fuel. A check valve 105, which opens in the direction of the damping chamber 39 and whose valve member is designed as a stepped piston 107, is inserted into this inlet line 103. The stepped piston 107 forms with its end face on the spring chamber side a sealing face 109 with which it is held in contact with a valve seat face 113 by a check valve spring 111. The

Check valve spring 111 is supported in a stationary manner on valve body 1 and acts on stepped piston 107 on its end face facing away from spring chamber 25. The stepped piston 107 is designed so that it is already in contact with the valve seat 113 with its larger one

Seals circumferentially sealingly in the smaller diameter of a stepped receiving bore 115, so that the check valve 105 closes before contact with the valve seat 113. The biasing force of the check valve spring 111 is so small that the

Step piston 107 is only moved when the pressure between the spring chamber 25 and the damping chamber 39 is in contact with the valve seat 113. The check valve 105 thus opens as long as the pressure in the damping chamber 39 is lower than the leakage oil pressure in the Spring chamber 39, so that a safe filling of the damping chamber 39 and avoidance of negative pressure during the closing stroke movement of the valve member 5 of the injection valve is ensured. If there is pressure equalization between the spring chamber 25 and the damping chamber 39, the check valve 105 closes, the stepped piston being pressure-balanced at this point in time.

In the ninth exemplary embodiment shown in FIG. 15, the valve member of the valve 65 in the second relief channel 63 is designed as an escape piston 117. For this purpose, the valve seat of the valve 65 is designed as a conical protuberance 119, against which the evading piston 117 comes into contact with its flat end face in such a way that a residual volume remains in the valve chamber. The escape piston 117 is sealingly guided on its circumferential surface on the wall of a valve chamber 121 receiving the valve 65 and is acted upon in a known manner by the valve spring 72 in the closing direction, which is supported on an adjusting disk 91.

When the valve 65 opens, the evasive piston 117 releases an evasive volume in the valve chamber 121, through which the pressure in the damping chamber 39 drops in such a way that the second opening stroke phase can take place on the valve member 5 and the entire injection cross section of the injection valve is opened.

With the return movement of the valve member 5 and the closing of the valve 65, the evasive volume is now conveyed back into the damping space 39, so that the refilling of the damping space 39 is supported, with the evasive piston 117 also taking over the function of a check valve.

Claims

Expectations

1. Fuel injection valve for internal combustion engines with a valve member 5 which can be displaced axially outwards against a restoring force in a bore (3) of a valve body (1) and has a closing head (7) protruding from the bore (3) at its combustion chamber end who is on his the

Valve body (1) facing side has a valve sealing surface (9) with which it interacts with a valve seat surface (11) arranged on the end face of the valve body (1) on the combustion chamber and with at least one injection opening (21) on the closing head, which emanates from a pressure chamber (13) (7) whose outlet opening (23) in the closed position of the valve member (5) is covered by the valve body (1) and released during the outward opening stroke, as well as with a two-stage hydraulic valve that limits the opening stroke of the valve member (5)

Stroke stop, which is designed as a hydraulic damping chamber (39) with a controllable relief line, the relief line being connectable to the damping chamber (39) via at least two recesses on the valve member (5), which can be controlled in succession during the opening stroke movement of the valve member (5), characterized in that at least one of the recesses can be connected to a low-pressure chamber via a relief channel (63) containing a valve (65).

2. Fuel injection valve according to claim 1, characterized in that the outlet openings (23) of the injection channels (21) during the opening stroke movement of the valve member (5) variably controllable and preferably as 2 axially arranged rows of spray holes on

Valve member (5) are formed, of which only a first lower row of outlet openings (23A) close to the combustion chamber is opened after passing through a first opening stroke phase of the valve member (5), while the second upper row of outlet openings (23B) only in the course of a second

Opening stroke phase of the valve member (5) is controlled.

3. Fuel injection valve according to claim 1, characterized in that the recesses on the valve member (5) are formed as surface grindings whose upper ends remote from the combustion chamber form control edges which have an end face (43) of the valve body (1) which axially delimits the damping chamber (39). work together.

4. Fuel injection valve according to claim 3, characterized in that a first bevel (51) is designed as an oblique surface bevel, the combustion chamber facing lower, more deeply worked end in a between the valve member (5) and bore (3) formed, connected to the low-pressure chamber annulus

(53) protrudes and opens into the damping chamber (39) with its tapering, axially upward end when the valve member (5) is in contact with the valve seat (11), the edge at the upper end of the first bevel (51) remote from the combustion chamber having a first control edge (57) forms.

5. Fuel injection valve according to claim 3, characterized in that a second bevel (59) is provided, the combustion chamber remote, axially located end forms a second control edge (61) and the The lower axial end facing the combustion chamber is permanently connected to the relief channel (63) containing the valve (63).

6. Fuel injection valve according to claim 4 and 5, characterized in that the first and second control edge (57, 61) on the valve member (5) are axially offset from one another in such a way that the first control edge (57) after passing through a first opening stroke phase of the valve member (5 ) can be controlled, while the second control edge (61) only after

Running through a total opening stroke of the valve member (5) through the end face (43) of the valve body (1) is closed.

7. Fuel injection valve according to claim 1, characterized in that the damping space (39) is provided in an intermediate disc (41) clamped between the valve body 1 and a valve holding body (27).

8. Fuel injection valve according to claim 3 and 7, characterized in that the damping space (39) on its the end face (43) of the valve body (1) opposite axial end by a valve member (5) attached to the piston (37) is limited to its outer circumference is sealingly slidably guided on the wall of the damping space (39).

9. Fuel injection valve according to claim 8, characterized in that the piston (37) is designed as an open to the damping chamber (39) U-sealing ring (47) which is pressed onto the stem of the valve member (5).

10. Fuel injection valve according to claim 9, characterized in that a spring (49) is inserted in the U-sealing ring (47).

11. Fuel injection valve according to claim 7, characterized in that the valve (65) in the washer

(41) is arranged.

12. Fuel injection valve according to claim 5, characterized in that the valve (65) in the relief channel (63) is preceded by a throttle point.

13. Fuel injection valve according to claim 1, characterized in that an anti-rotation device is provided on the valve member (5) of the injection valve against independent rotation.

14. Fuel injection valve according to claim 13, characterized in that the anti-rotation device is formed by a profile (73) on the valve member (5) and a complementary recess (75) in the housing, preferably in an intermediate plate (41).

15. Fuel injection valve according to claim 1, characterized in that the valve (65) in the relief channel (63) is adjustable by means of an electrical actuator.

16. Fuel injection valve according to claim 15, characterized in that the actuator is designed as a piezo actuator (79).

17. Fuel injection valve according to claim 15, characterized in that the actuator is designed as a solenoid valve, wherein the armature (81) of the solenoid valve projecting into a current-carrying coil (83) is connected to a valve element (67) of the pressure valve (65).

18. Fuel injection valve according to claim 1, characterized in that the opening of the valve (65) in the relief channel (63) by an adjustable hydraulic back pressure on the damping chamber (39) facing away from a valve member (67) of the valve (65) is controllable.

19. Fuel injection valve according to claim 1, characterized in that the opening pressure at the valve (65) in the relief channel (63) via an adjustment of the

Spring biasing force of a valve spring (72) is continuously adjustable.

20. Fuel injection valve according to claim 19, characterized in that the adjustment of the spring biasing force on the valve (65) is carried out by an axial displacement of a spring support surface.

21. Fuel injection valve according to claim 20, characterized in that the spring contact surface by means of a

Piezo actuator (89) is moved.

22. Fuel injection valve according to claim 20, characterized in that the spring support surface is displaced by means of an electro-magnetic armature (93) arranged in a coil (95).

23. Fuel injection valve according to claim 20, characterized in that the spring bearing surface is displaced by means of a hydraulic piston (97).

24. Fuel injection valve according to claim 1, characterized in that a check valve (105) opening in the direction of the damping chamber (39) into a preferably from Low pressure chamber outgoing inlet line (103) of the damping chamber (39) is used.

25. Fuel injection valve according to claim 1, characterized in that the valve member of the valve (65) in the relief channel (63) is designed as an escape piston (117) which releases a defined escape volume in the valve chamber (121) of the valve (65) during its opening stroke movement.

26. Fuel injection valve according to claim 25, characterized in that a valve seat surface of the sealing piston guided in the valve chamber (121) is designed as a conical protuberance (119).