EP0949415B1 - A fuel injection device for internal combustion engines - Google Patents

Description

State of the art

The invention relates to a fuel injection device for internal combustion engines according to the preamble of the patent claim 1 off. In such a case, by DE 196 24 001 A1 The known fuel injection device is the valve chamber in a first version with no reduction in cross section connected to the control room. The control valve contributes Actuation by the piezo actuator to the drain cross section Drain channel either completely or closes it. In Another version is the valve chamber over a Connection channel connected to the control room, this Connection channel coaxial to the valve seat on the side of the Drain channel is. By operating the control valve member through the piezo actuator either the Drain cross-section from the valve chamber to the drain channel completely opened or closed or it is used to achieve a Pre-injection the control valve member from the valve seat to Drain channel away to the entry of the connecting channel in the valve chamber moves, as a result of this movement the control room for a short time via the valve room Drain channel is open. For a subsequent one The main valve injection into a control valve Moves middle position, in which both the cross section to Drain channel out as well as the cross section of the Connection channel in the valve chamber fully open are. This configuration has the disadvantage that Relief of the pressure in the control room only one geometrically defined discharge cross-section to the discharge channel there exists. The amount of pre-injection is in the second described embodiment so that the Adjustment speed of the control valve member by the Piezo actuator and the geometrically defined path of the Control valve member determining quantities for the degree of Relieve the pressure in the control room. In particular is the maximum relief cross section for both Relief for the pre-injection as well as for the Relief for the main injection the same size, what a fine tuning of the opening speed of the Injector in different operating conditions from Disadvantage is.

From DE 196 24 001 A 1 a fuel injection device is known in which the Drain cross-section is controlled by a valve member which is actuated by a piezo actuator becomes.

Fuel injection valves are known from EP 0 745 764 A2 and EP 0 829 641 A2, which have an outflow cross section which is controlled by a flat seat valve which can be actuated by means of an electromagnet.

Advantages of the invention

The fuel injection device according to the invention with the characterizing features of claim 1 has against it the advantage that the control valve according to the invention sequentially two drain cross sections in succession are taxable. Thus a gradation of the Drain cross-section can be achieved depending on the stroke. Especially for low relief of the control pressure in the Control room can have a first smaller discharge cross-section come into effect with which the Pre-injection can be set. For the The main injection is then a large drain cross section available for a quick movement of the Injector member allowed. It is advantageous according to claim 2, a sleeve-shaped Drag valve member provided that a second Drainage cross section of the drainage channel controls if that Control valve member a first, relieving the control room Stroke. The one before the opening of the second Outflow cross-section through the drag valve member Pressure reduction in the valve room or control room facilitates a quick opening of the second Drain cross section in succession to the opening of the first discharge cross section at the first movement of the Trolling valve member. This can be particularly fast Opening the injection valve member at the beginning of the Main injection can be achieved.

In the further embodiment according to patent claims 3 to 5 are advantageous types of drainage cross-section formation proposed. To open the second Final cross section through the drag valve member can this advantageous according to claim 6 by a Driver on the control valve member from its main valve seat be lifted off. In an alternative embodiment according to Claim 8, the drag valve member can be advantageous also by a compression spring with a corresponding lowering of the Pressure in the valve chamber are moved into the open position, by lowering the pressure on the control valve member can follow. It is in an end position of the Control valve member of the discharge cross section through the Cross-section determined at the main valve seat. The design according to claim 9 provides accurate guidance of Drag valve member on the valve lifter. Furthermore, the This increases the guiding quality of the valve lifter be that according to claim 11 on the valve lifter a sleeve is provided, the outer diameter of which is larger than the diameter of the inner boundary surface of the Trolling valve member. It is advantageous according to Claim 12 this sleeve after threading the Drag valve member pressed onto the plunger on this and can then be installed as a whole. Claim 13 shows an alternative attachment of the sleeve on the Valve tappet. Further embodiments of the invention with their advantages are the following description in Take connection with the drawing.

drawing

In the drawing, six embodiments of the Invention shown, they are in the following Description explained in more detail. 1 shows a schematic representation of a Fuel injector with fuel supply off a high pressure fuel accumulator and one Fuel injection valve of known type, Figure 2 a first embodiment of the invention with a Control valve member on which a drag valve member is arranged is that of a driver on the valve lifter of his Valve seat is moved away, Figure 3 shows a modification of the Embodiment of Figure 2 with a Control valve member having improved guidance Figure 4 shows a third embodiment of the invention in Further development of the embodiment of Figure 2, wherein instead of a driver to take the drag valve member a compression spring is provided, Figure 5 is a fourth Embodiment of the invention in the Drag valve member a third valve seat is provided, Figure 6 shows a fifth embodiment with a Control valve member that both the discharge cross section from Valve space to the drainage channel as well as the connecting channel controls between the valve space and the control space, and FIG sixth embodiment in which the control valve in analogous configuration to Figure 2, the pressure of a Controls the control room with the help of a 3/2-valve design, whereby a connection to the valve chamber cannot be closed Control room exists and coaxially to the control valve member High pressure flow to the control room is provided, which by an extreme position of the control valve member can be closed is.

Description of the embodiments

A fuel injector with which at high Injection pressures a large variation with little effort the fuel injection with respect to the injection quantity and Injection time is possible by a so-called Common Rail System implemented. This represents another Kind of high pressure fuel source available as it through the usual high pressure fuel injection pumps is given. However, the invention is also in principle conventional fuel injection pumps can be used. However, use with one is particularly advantageous Common rail injection system.

In the common rail injection system shown in FIG. 1 is a high pressure fuel source High-pressure fuel reservoir 1 provided by a High-pressure fuel delivery pump 2 from one Fuel tank 4 is supplied with fuel. The pressure in the high-pressure fuel accumulator 1 is determined by detects a pressure sensor 6 and an electrical one Control device 8 supplied via a Pressure control valve 5 the pressure in the high-pressure fuel reservoir controls. The control device also controls this Opening and closing of high-pressure fuel injection valves 9, used to inject fuel from the high-pressure fuel accumulator be supplied.

In a known embodiment, the Fuel injection valve 9 on a valve housing 11, the one end that is for installation on the internal combustion engine is determined, has injection openings 12, the outlet from inside the fuel injector by a Injection valve member 14 is controlled. This is in the executed example as an elongated valve needle trained that a conical at one end Has sealing surface 15 with an inner Valve seat cooperates on the valve housing from which the Remove injection openings 12. The valve needle is in one Longitudinal bore 13 on its upper, sealing surface 15 end facing away and is on the sealing surface 15th facing away from the longitudinal bore 13 end acted upon by a compression spring 18 in the closing direction. Between the guide in the longitudinal bore 13 and the The valve seat is the valve needle 14 from an annular space 19 surrounded, which opens into a pressure chamber 16, which in turn via a pressure line 17 in constant connection with the High-pressure fuel accumulator 1 stands. In the area of this Pressure chamber, the valve needle 14 has a pressure shoulder 20 on, over which they oppose the pressure in the pressure chamber 16 Force of the spring 18 is applied in the sense of lifting the sealing surface 15 from the valve seat.

The valve needle continues to be driven by a plunger 21 applied, the valve needle 14 facing away End face 22 in a tappet guide bore 23 Control room 24 limited. This is via an inlet channel 26, in which an inlet throttle 28 is provided, always with the pressure line 17 or the High-pressure fuel accumulator 1 connected. The inlet channel opens into the control room 24 in a non-closable manner. Coaxial to the plunger 21 leads from the control room 24 Connecting channel 29 from the one in a valve chamber 30 Control valve 31 opens. In the connecting channel that also represents a drainage channel is one Diameter restriction, preferably in the form of a Drain throttle 32 is provided. The detailed structure of the Control valve 31 is in the different Embodiments 2 to 7 shown in more detail. These embodiments have in common that the Control valve 31 has a control valve member 34, consisting from a valve tappet 35 which is in a tappet bore 36 is guided, and a valve head 37 on the in the Valve chamber 30 protruding end of the control valve member 34. An the end of the valve lifter opposite the valve head 35, a spring plate 38 is provided, on which a Compression spring 39, which strives to Bring the control valve member into the closed position. In opposite direction, the control valve member 34th acted upon by a piston 40 which is part of a Piezo actuator 41 is and when the piezo is excited depending on the degree of excitation the control valve member in different Can bring opening positions. The piston can be connected directly to the piezo of the piezo actuator or by means of a hydraulic or mechanical transmission be moved by this.

For a more precise representation of the invention Design of the control valve 31 is based on Figure 2 described in more detail. There is again the end of the Tappet 21, which actuates the valve needle 14, shown. The Tappet 21 closes in the tappet guide bore 23 its end serving as a movable wall 22 den Control room 24 a. The adjustment of the plunger 21 is after limited at the top by a stop 42, the one leaves outside annular space 43 into which the inlet 26th empties. Axial leads in the area of the stop 42 Connection channel 29 from which contains the discharge throttle 32 and opens into the valve chamber 30. This has one circular cylindrical peripheral wall 45, which has a conical Valve seat 46 in a valve tappet 35 surrounding Annulus 48 merges. From this leads a drain channel 49 a fuel return or a relief chamber.

The valve head 37 arranged at the end of the valve tappet 35 has a conical entry to the connecting channel 29 in the valve head sealing surface 51 facing away from the valve chamber 30, which with a valve seat 52 to form a Valve 58 cooperates. This valve seat 52 is located at the transition to an inner through hole 53 of a sleeve-shaped drag valve member 54 that the Valve tappet surrounds at a distance. The inner peripheral wall of the inner through hole 53 thus forms together with the Shell surface 55 of the valve lifter 35 a Passage cross section 56. To determine the location of the sleeve-shaped towing member 54, this is over Spacer ribs 57 guided on the valve lifter 35. These ribs leave the adequately dimensioned passage cross section 56 free.

At the valve seat 52 axially opposite end the sleeve-shaped towing member 54 a Valve member sealing surface 59, which is also conical is formed with a smaller cone tip angle than the cone tip angle of the conical valve seat 46 and with the valve seat 46 cooperates. The conical Valve seat 46 a main valve seat of a main valve 61 represents a much larger passage cross-section limited from the valve space 30 to the annular space 48 than that Passage cross section between the valve head 37 and The valve seat 52 of the valve 58 is limited. Farther are for better guidance of the sleeve-shaped Drag valve member between this and the peripheral wall 45th of the valve chamber 30 also longitudinal ribs 60 with in between lying grooves provided that are sufficiently large Leave passage cross-section 56 to main valve 61 free.

In Figure 2, the control valve 31 is in the closed position shown, the valve head 37 with its sealing surface 51 comes to rest on the valve seat 52 and has over this the sleeve-shaped drag valve member 54 with its Drag valve sealing surface 59 for contact with the Main valve seat 46 brought so that a connection between Valve chamber 30 and annular chamber 48 or drain channel 49 is prevented.

In this closed position of the control valve member Control room 24 through the constant inflow of High pressure fuel quantities on the pressure of the High pressure fuel accumulator 1 held, which causes the plunger 21 the injection valve member 14 in its Holds the closed position on the valve seat. This follows from the fact that the area of the movable wall 22 is essential is larger than the area with the same pressure pressurized pressure shoulder 20 of the injection valve member 14. This high pressure in the control room 24 also acts on the Valve head 37 and the sleeve-shaped towing member 54 in in each case their closing direction.

The piezo actuator is used to initiate an injection controlled by the control valve member by one Opening stroke adjusted. First, the pilot valve 58 opened by the valve head 37 from the pilot valve seat 52 takes off. There can be a subset of fuel for Drain channel 49 through the passage cross section 56 from the Drain off the valve chamber or control chamber. Nevertheless, the remains Pressure in the valve chamber 30 is so great that the drag valve member with its valve member sealing surface in the closed position on Main valve seat 46 remains. Only when the stroke of the Control valve member is so large that a driver 63, the Valve tappet 35 e.g. in the form of a U-shaped clamping element is attached to the end face 64 of the sleeve-shaped drag valve member, this is with the further movement of the valve lifter 35 from the Main valve seat 46 lifted off, so that now a larger one Drain cross section is released to relieve the Valve chamber 30 or the control room 24. With If the excitation of the piezo actuator drops, the valve lifter arrives 35 under the action of the spring 39 together with the dragged sleeve-shaped drag valve member 54 back in the initial closed position shown back.

The great advantage of a piezo drive is the fact that a control valve member actuated thereof corresponding to the Excitation of the actuator can be brought into defined positions can. This makes it easy and exact Injections into a pre and a main injection divide. A pre-injection is required for the above presented construction of the fuel injector only a slight relief of the control room 24 so that the Injector valve member only a short opening Injection openings 12 causes. For a main injection on the other hand, to carry out a large, fast stroke of the injection valve member 14, the control chamber 24 quickly and be relieved effectively. The faster the injector can open or close, the more precise the Injection phase can be determined. In that the inlet 26 Includes inlet throttle 28 and this is smaller than that Cross section on the outflow side of the control chamber 24, in particular the cross section of the discharge throttle 32, the effective relief of the control room can be achieved. The final control of the cross-section to the drain channel 49 takes over the control valve. This must first against the high pressure in the control room 24 or Work on valve chamber 30. But now the cross section of the drain at the pre-valve 58 is small in relation to the main valve 61, will be a relatively minor job for opening the Valve 58 required. By opening the pilot valve the pressure in the valve chamber 30 is already significantly reduced, so that when a larger pressure in the valve chamber 30th wall must be adjusted against this pressure, the force to be applied is already lower. With this less force than required for one-step opening the cross section of the main valve is opened quickly, what for a correspondingly quick relief of the valve space and control room leads. The control of the control valve can take place so that the opening of the valve 58 of the Pressure in the control room 24 is already lowered so that a short opening stroke of the injection valve member 14 allows is. Following this, the control valve member 35 be moved again and over the drag valve member 54 open the larger discharge cross-section in order to use the then following rapid relief the opening of the Injection valve member 14 for the main injection initiate. The completion of the main injection is through Controlled closing of the control valve and thus the Injection quantity.

In an alternative embodiment of the control of the control valve according to the invention, the pressure after Opening the valve should only be relieved to the extent that Injection valve member 14 remains closed, but one only little further relief of opening it causes. By subsequently adjusting the Valve tappet 35 can then by increasing the Degree of opening of the pilot valve and / or by dragging Opening the drag valve member a short further relief the pressure in the control chamber 24 or valve chamber 30 be made to generate a pilot injection and then by taking back the valve lifter stroke Termination of the same. This is followed by a larger one Valve tappet stroke in which the drag valve member 54 again a full relief of the control room 24 Carrying out the main injection is effected.

With the help of the stroke h1 of the valve lifter 35, the necessary is so that the driver 63 for abutment on the end face 64 of the drag valve member 54, the opening stroke of the Preventil be defined. The end face 64 is so designed that even when the annular driver 63 the sufficient passage cross section 56 from the valve chamber 30 to the annular space 48 is available. The Front side, for example, can be designed with a crown radial passage cross sections. Limiting the Drain cross section through the drain throttle 32, which in the executed example is arranged in the connecting channel 29, can also follow in another place, for example in Drain channel 49 or by dimensioning a maximum Flow cross section 56 therebetween.

Figures 8a to 8c are the control processes of this Control valve. In Figure 8a the stroke of the Injection valve member 14 on the angle of rotation of the Internal combustion engine or the time applied. you recognizes the smaller forward stroke V of the injection valve needle 14 to carry out the pre-injection, the intermediate one Pause P at which the control valve is fully or as far it is concluded that the injection valve member pressure in the control chamber 24 bringing it back into the closed position sets, and the subsequent stroke H, via the Duration the main injection is defined. Is triggered this is shown by the sequence shown below Strokes of the control valve member. You can see the stroke V1, by when reaching the maximum opening position at stroke h1 of the plunger 35, for example before that Drag valve member is lifted from the main valve seat, the Control chamber 24 is relieved that the stroke of Injection valve member 14 for the stroke V can begin. about Relief for pre-injection remains at stroke V1 consist. In the actuation pause P1 of the control valve member, i.e. if the piezo is not excited, this remains Injection valve member 14 closed. Begins at the end of P1 the re-actuation of the control valve member 35 by the Piezo up to a stroke h2 in which the entire Discharge cross-section after opening the main valve 61 the drag valve member 54 is opened and the Control room 24 is relieved to a maximum. Already in the area between h1 and h2, the injection valve member opens stays in for the length of the control valve opening Open position until the closing movement of the Control valve member again the pressure in the control chamber 24 is below, who is able to do that Keep injection valve member open.

The diagram 8c below shows the pressure curve shown in the control room 24 with corresponding Pressure drops when, according to diagram 8b Control valve member h1 has opened.

A modification of the control valve according to FIG. 2 is shown in Figure 3 shown. As far as this configuration with Figure 2 matches, the same reference numbers are used. Reference is made to the corresponding description for FIG. 2 directed. Deviates from the embodiment according to FIG. 2 in Figure 3 in the area in which in Figure 2 the Valve tappet 135 is guided in the tappet bore 36, a Sleeve 166 arranged on the plunger 135. In Figure 3 is this sleeve axially between a stop 167 and one Holding disc 168 fixed on the plunger. The attack is made by a shoulder of the plunger formed at the end of the from the sleeve-shaped drag link 54 protruding spacing ribs 57 is provided. The holding disc can, for example, as Snap ring in an annular groove 69 of the plunger at its out Ram bore 136 protruding end can be realized. Alternatively, however, the sleeve can also be placed on the plunger 135 be pressed on. The stroke 167 is also the stroke h1 defines from which the plunger, which is together with the Sleeve 166 moves to abut the sleeve-shaped Towing member 54 arrives. The sleeve 166 also has their lower end facing the drag valve member 54 Reduction in diameter with which to replace the annular space 48 an annular space 148 is again formed here from FIG. 2, who is constantly in communication with the drain channel 49. The Towing member 54 is as in the previous embodiment designed according to Figure 2 on its end face so that a Overflow cross section is released in the Magnitude of the passage cross section 56 is.

This configuration has the advantage that the Guide surface within the tappet bore 136 is larger and thus the control valve member is guided more precisely. Since the Tappet 135 for assembly by the inner one Through hole 53 must be passed, would be one Enlargement of the ram guide diameter in the area the tappet bore according to FIG. 2 is actually a limit set. By adding the sleeve 166 can still the guide surface can be enlarged, the sleeve subsequently after threading the drag valve member 54 on the valve lifter is installed. The outside diameter of the The sleeve is larger than the diameter of the inner one Through hole 53 of the drag valve member and smaller than the diameter of the valve chamber 30.

Another variant of a control valve in a modification to The exemplary embodiment according to FIG. 2 is shown in FIG. 4 played. Again, two are different Drain cross sections of the drain channel in succession turned on. As in FIG. 2, the one from limited the plunger 21 of the injection valve member 14 Control chamber 24 is provided, through which the throttle 32nd contained connection channel 29 with the valve chamber 30th connected is. The tappet 235 also projects into this valve space the valve head 237 and the valve head sealing surface 251, which in Closed state of the control valve in contact with the valve seat 52 of the sleeve-shaped drag valve member 54 is below Formation of the pilot valve 58. Via the valve head 237 this additionally with its valve member sealing surface 59 in System held on the main valve seat 46 of the main valve 61. Beyond this valve seat 46 is again the Annulus 48, which is penetrated by the plunger 235 and in permanent connection with the drain channel 49. As in the exemplary embodiments according to FIGS. 2 and 3 sleeve-shaped drag valve member 54 on its outer circumference over longitudinal ribs 60 which are formed by grooves between them are formed on the peripheral wall 45 of the valve chamber 30 guided. These longitudinal ribs leave the flow cross section to the main valve 61 free. The inner through hole 53 of the drag valve member 54 is from the valve lifter 35 spaced so that starting from the pilot valve corresponding flow cross-section 56 to the annular space 48 or drain channel 49.

The connecting channel 29 lies coaxially with the valve head 237 opposite and ends in an axial boundary wall 270 of the valve chamber 30. The junction of the connecting channel 29 opposite the valve head 237 on his End face provided with a sealing surface 271, either can be conical or conical. Is accordingly the area of the exit of the connecting channel 29 on the axial boundary wall 270 formed as a valve seat, so that the connecting channel through the sealing surface 271st can be locked. The axial boundary wall is thus as the valve seat of a third valve 279 with the Valve head 237 designed as a valve member.

With this valve, valve tappet 235 is actuated so that the realization of a pilot injection Valve head 237 in one go from its installation on The valve seat 52 is moved away until it touches Sealing surface 271 on the valve seat 270 of the third valve 279 or on the axial boundary wall 270 the valve head is relieved for a short time of the valve chamber 30 and the control chamber 24, which at appropriate dimensioning is sufficient, an opening of the Injection valve member 14 for performing a To effect pre-injection. Is the valve head 237 with its sealing surface 271 close to the axial boundary wall 270, the connecting channel 29 is completely closed, so the pressure in the valve chamber can continue to relax, meanwhile the pressure in the control room 24 via the inlet 26 is rebuilding what a closing the Injector needle 14 follows. The pressure relief in the valve chamber 30 in turn leads to the Return forces arranged in the annular space 48 Compression spring 272, which is between the housing and the end face of the drag valve member 54 on the annulus side supports, predominates and the drag valve member 54 of the Adjustment of the valve head 237 up to the turn tight system on the valve head sealing surface 251. If then by controlling the Piezo actuator the valve head in an intermediate position between the valve seats 270 and 46 is moved, the control room 24 over the valve chamber 30 and the large opening cross section of the main valve 61 very quickly to the fullest extent possible be relieved, so that here to carry out a Main injection a maximum, quick adjustment of the Injection valve member can take place in the opening direction. The Decoupling the control room 24 from the pressure source 1 via the Inlet throttle 28 allows relief to almost full relief pressure, favored by the large Outflow cross section on the outer circumference of the drag valve member. To complete the main injection, the valve head returned together with the drag valve member 54, with tight sealing of the valve 58 and the Main valve 61. The great advantage of this design is that to perform the pre-injection only a single movement of the control valve member in one Direction is required and to carry out the The main injection continues to be just a return movement in shape a partial stroke in the direction of the starting position and one itself subsequent final repatriation.

While in the exemplary embodiments FIGS. 2 and 3 only two valves each in connection with the Control valve member and the drag valve member realized were in the above-described embodiment 4 realized a total of three valves, the valve 58 with the valve seat 52, the main valve 61 with the Main valve seat 46 and the third valve 279 with the Valve seat 270. In an alternative embodiment according to FIG. 5 three valves are also implemented here. This execution However, builds on the configuration according to Figure 3. As in 3, the valve chamber 30 is again provided here, in the coaxial to the valve lifter 35 of the connecting channel 29 Coming from the control room 24, flows out.

It is here again at the end of the projecting into the valve chamber 30 Tappet 335 of the valve head 337 provided with the Valve head sealing surface 351, which with the valve seat 52 on Drag valve member 354 forming the pilot valve 58 interacts. This in turn has the valve head on its 337 facing away from the outside conical to its peripheral wall arranged inclined or spherical Valve member sealing surface 59 that mates with the main valve seat 46 forming the main valve 61 at the transition between Valve chamber 30 cooperates to the annular space 48. The Drag valve member is on the outer circumference by longitudinal ribs 60 guided on the peripheral wall of the valve chamber. Is on too the valve lifter 335 pressed a sleeve 366, the one has an enlarged outer circumference over which the Valve tappet is guided in the tappet bore 336. This Sleeve 366 protrudes into that connected to the drain channel 49 Annular space 48 into it and projects over an annular groove 374 there Tappet 335 axially from the valve head sealing surface of the Valve head 337 is limited and the radial distance to inner through hole 53 of the towing member 54 holds and thus forms the flow cross section 56. The sleeve 366 has now in their area overlapping the annular groove 374 on the front side a conical sealing surface 375, which at corresponding movement of the valve lifter 335 to the system a conical valve seat 376 on the front of the Drag valve member 354 can be brought. This valve seat 376 thus forms 375 together with the conical sealing surface a third valve 379. The conical valve seat is 376 thereby to the inside of the inner through hole 53 of the Drag valve member 354 inclined, so in the opposite direction the inclination of the valve member sealing surface 59 of the main valve 61st

In the closed position of the control valve shown, the Valve head with its valve head sealing surface in contact with the Brought valve seat 52 and continue that Drag valve member 354 with its valve member sealing surface 59 brought into contact with the main valve seat 46. So that's it Connection between the valve chamber 30 and the drain channel 49 prevented and it can the control room 24 on the of the Pressure source given high pressure can be brought up with the success of closing the injector member 14. At a subsequent actuation of the control valve for The plunger 335 is used to carry out a pilot injection the sleeve 366 moved so far that the conical Sealing surface 375 of the sleeve 366 in close contact with the conical valve seat 376 of the drag valve member 354 arrives. This stroke h5 is brief Relief of the valve chamber 30 and the control chamber 24, the is sufficient, the injection valve member 14 in a Pre-injection position to move. With closing the third Valve 379 by contacting the sealing surface 375 on the conical valve seat 376 after stroke h5, is the pilot injection by building up pressure in the control chamber 24 completed. For the main injection, the following is the Control valve member moved on. This will make it Drag valve member 354 lifted from the main valve seat 46, see above that there is a full maximum relief of the control room 24 is coming. There is a much larger one for this relief Cross section available as that of performing the Pre-injection was available by opening the Pre-valve until the third valve closes. The advantage in this embodiment is that by a staged energization of the piezo actuator for the pre and Main injection can be switched in only one direction got to. This results in very short switching times, in particular by switching through the one Valve seat 52 to the other valve seat 376 a very short Relief and therefore a very small pre-injection quantity realizable. To end the injection, the Tappet returned to the starting position shown. For there is a separate injection process Relief cross-section available to match the corresponding Can be adapted to requirements.

A fifth exemplary embodiment of the invention is shown in FIG. 6 shown that a further development of Representing embodiment of Figure 4. As with Embodiment according to Figure 4 are in cooperation of Valve head 437 and drag valve member 454 three valves realized. As in Figure 4, the mouth opens again Connection channel 29 coaxial to the valve lifter 435 in the Valve chamber 30 a. As in the embodiment according to FIG. 4 is the axially directed wall 470 of the valve chamber 30 at the entrance of the connecting channel 29 as the valve seat of the third valve 479 formed on which as a sealing surface trained end face 471 of the valve head 437 in contact is feasible. The valve head 437 carries the Valve head sealing surface 51, which with the valve seat 52 on Transition from the front of the drag valve member 454 to its inner through hole 53 to form the Valve 58 cooperates. At the opposite end the drag valve member 454 carries a conical Valve member sealing surface 459 that mates with the main valve seat 46 at the transition from the valve chamber 30 to the annular chamber 48 Formation of the main valve 61 cooperates. As with the The embodiment of Figure 4 is the drag valve member 454 by a compression spring 472 in the direction of opening the Main valve 61 loaded. The spring 472 overrides a thrust washer 477 on a neck-shaped extension 478 of the drag valve member 54. In the area of this nozzle-shaped extension 478 becomes the drag valve member 454 tight on the outer jacket 455 of the valve lifter 435 guided so that between the valve head 437 and the Drag valve member 454 has an annular recess 480 which is included through a by the Throttle bore 481 in constant trailing valve member Connection to the annular space 48 is.

In this embodiment, there are three chokes realized, on the one hand, the inlet throttle 28 in Inlet 26 to the control room 24, the second is the Drain throttle 32 in the connecting channel 29 and the third Throttle bore 81 mentioned above.

As in the embodiment of Figure 4 is to achieve a pilot injection actuates the control valve member so that the valve head 437 is lifted from the valve seat 52 and is moved until its sealing surface 471 touches Valve seat 470 of the third valve 479. About this The control room is relieved for a short period of time 24, which is determined by the cross section of the Throttle bore 481 as the only connection between Control room 24 and annulus 48 at initially still Main valve seat 46 adjacent drag valve member. Then in the closed position of the third valve 479 in contact with the axial boundary wall 470 of the valve chamber 30 the valve chamber continues via the throttle bore 481 relieved. It arises in the valve chamber 30 Relief pressure that allows the drag valve member 454 by spring 472 away from the main valve seat 46 System on the valve head sealing surface 51 of the valve head is moved. But this also becomes the main valve 61 opened so that the control chamber 30 continue to relieve pressure can. To carry out the main injection on it again the valve head 437 together with the Drag valve member 454 moved to an intermediate position, in which is the large connection cross section of the main valve 61 opened between the drain channel 49 and the control chamber 24 is.

Deviating from the embodiment according to FIG. 4 offers itself here the possibility of a targeted use of chokes to determine the relief dynamics of the control room 24. The discharge is used to carry out the pilot injection determined by the throttle bore 481 and at The main injection is the relief of the control room 24 determined by the larger discharge throttle 32, which is smaller than the outflow cross section of the main valve 61. Together with the inlet throttle 29 then turns to the definition of Main injection in the desired gradation of pressure in the Control room 24 a. The main injection will eventually by moving plunger 435 back into the one shown Starting position achieved in Figure 6, in which the pilot valve 58 and the main valve 61 are closed and the third Valve 479 is open. One can in this way in End stroke range of the valves the tolerance influence of Minimize valve lift. The cross sections can be used for the preliminary and Main injection can be customized.

In the diagram, Figure 9a to 9c is recorded as the Motion sequences of the injector needle 14, the Valve head 437 and the drag valve member 454 formed are. In the above diagram 9a is about the stroke and the Time the movement of the injector needle is recorded, with a small stroke for pre-injection V, one intermediate pause P in which the injector is closed and a subsequent main injection H. The pilot injection is triggered according to the underlying diagram 9b by adjusting the Valve head 437. Starting from the closed position according to 6, the valve head is moved through by the valve seat 52 up to the valve seat 470 of the third valve, which in represented by the number 470 on the ordinate is. At this point the control room 24 is again closed, so that the break, in which also that third valve 479 is closed, the high closing pressure in Control room 24 adjusts and the injector 14th keeps closed. During this period, however, moves accordingly Diagram 9c the towing member 454 from closing the third Valve 479 to rest on valve head 437. This position is in the diagram with the number 52 on the abscissa shown. This also persists after investment Drag valve member 454 in this end position to the end the pause P. Then the control valve member is back again is moved to an intermediate position. Here move the valve head 437 and the drag valve member in synchronism in an intermediate position Z, which to fully relieve the Control room 24 leads. With the return of the valve head 437 and drag valve member 454 is finally the Relief of the control room 24 again interrupted it builds the closing of the injector member effecting control pressure again.

The foregoing have been in various embodiments of the control valve shown that to control the pressure in the control room 24 a connection to the drain channel 49 is produced, which relieves the pressure on the control chamber 24 leads. Only the load on the control room becomes Control valve brought back into the closed position and the constant supply of high fuel pressure via the supply channel 26 set. In principle, such valves work as 2/2-way valves. In the present, such a 2/2 valve was used modified the drag valve member 54. According to Figure 7 can such a valve is also designed as a 3/2 valve be, with a in a first position of the valve Connection from the high-pressure fuel reservoir from the control room is manufactured with simultaneous closure of the Drain channel and in a second position of the valve Connection between high-pressure fuel accumulator 1 and Control room can be prevented, producing the Connection of the control room to the relief channel. Figure 7 shows a very similar one in this context Design as Figure 2 with the difference that the Valve chamber 530 in permanent connection channel 529 Connection to the control room not shown here stands. This connecting channel branches from the peripheral wall of the cylindrical valve space 530. The inflow of high pressure fuel takes place here on the axial End wall 570 of valve chamber 530, this inlet 526 coaxial to the axis of the valve chamber 530 or the Ram 535 opens. The end face 570 forms in Mouth area of the inlet 526 a valve seat with an end sealing surface 571 on the valve head 537 in analogous configuration to FIG. 4 as third valve 479, but here in a different function, interacts. How is also in the previous embodiments Valve tappet 535 guided in a tappet bore 36 and penetrates the annular space 48, which in turn over the Main valve seat 46 the valve chamber larger in diameter 530 passes. One acts with the main valve seat 46 Valve member sealing surface 59 in the same way as in FIG 2 trained drag valve member 54, these Valve member sealing surface is conical, analogous to that conical transition between valve space 530 and annulus 48 and at one end of the sleeve-shaped drag valve member 54 is inclined to the outer periphery. At the opposite end of the sleeve-shaped valve member 54 is in turn to the inner through hole 53 inclined a conical valve seat 52, which with a Valve head sealing surface 551, which is also conical is formed, cooperates on the valve head 537. In the area of the annular space 48, the valve lifter 535 also has one Driver 563, which, for example, as a snap ring in a Ring groove 583 of the valve lifter can be clipped. The valve head is in contact with the valve seat 52 of the valve 58 and the valve member sealing surface 59 in System on the main valve seat 46 of the main valve 61, is the Driver 563 by a stroke h1 from an end face 564 of the Drag valve member spaced. Even when the Driver 563 on the end face 564 remains sufficient Cross-section free to allow fuel flow from valve compartment 530 when the pilot valve is open through the between valve tappet 535 and the inner through hole Passage cross section 56 can flow to the annular space 48 and from there via the drainage channel to the discharge side.

When the valve lifter 535 is actuated by the actuator this is lifted off the valve seat 52 with the valve head be so that with simultaneous inflow of fuel via the inlet channel 536 and outflow of fuel via the Passage cross section 56 to the drain channel 49 in the Control room sets an average pressure that is sufficient is to pre-injection by opening the Injector member 14 to effect. For the Main injection is the control valve member with the Valve head 537 switched through until the Sealing surface 571 on valve seat 570 or closing of the third valve 579. The inflow of High pressure fuel in the valve compartment and thus in the Control room prevented and the control room can to Drain channel 49 are completely relieved. In the course of this In addition, the driver 563 is in contact with the movement Front side 564 arrives and has the drag valve member 54 from Main valve seat 46 lifted off, so that a very large one Relief cross section from control chamber 24 to drain channel 49 is made. To finish the main injection then the valve lifter with valve head 537 back into the shown starting position moved back, in which the third Valve 579 opened and the pilot valve 58 and the main valve 61 are closed. It can then be characterized by the incoming High pressure fuel again the high pressure in the control room build up and the injection valve member 14 in the closed position bring. In an analogous manner, with such a 3/2 control valve also analogously to the configurations according to FIGS. 3 and 5 apply.

Claims (22)

1. Fuel injection device for internal combustion engines, having a high-pressure fuel source (1), from which a fuel injection valve (9) is supplied with fuel, which valve has an injection valve member (14) for controlling an injection opening (12) and a control space (24), which is delimited by a moveable wall (22) that is at least indirectly connected to the injection valve member (14) and which has an inlet passage (26) leading from a high-pressure source, preferably from the high-pressure fuel source (1), and an outlet passage (29) leading to a relief space, and the pressure in which is controlled by a control valve (31), which controls the inlet passage (26, 126) or the outlet passage (29, 49) and is actuated by a piezo actuator (41), the control valve (31) having a control valve member (34) with a valve plunger (35) which is guided in a housing and at the end of which there is a valve head (37, 137) that projects into a valve space (30), has a valve head sealing surface (51) facing a valve seat (52) and controls an outlet cross section of an outlet passage (49), the valve space (30, 130) being connected to the control space (24) and, when the outlet cross section is closed, being exposed to the pressure of the high-pressure fuel source (19), characterized in that the control valve can be used to successively open two outlet cross sections of different sizes, a first outlet cross section being controlled by a pilot valve (58) and a second outlet cross section being controlled by a main valve (61).
2. Fuel injection device according to Claim 1, characterized in that inside the valve space (30, 530), the valve plunger (35) is surrounded by a sleeve-like follower valve member (54), having an inner delimiting surface (53) between which and the valve plunger (35, 135) there is an internal passage cross section (56), and in that the follower valve member (54) has, at its axial end on the side of the valve head sealing surface (51), a pilot valve seat (52), which together with the valve head sealing surface (51) forms the pilot valve (58) which controls the first outlet cross section, connected to the outlet passage (49) via the inner passage cross section (56), and at its other axial end has a valve member sealing surface (59), which interacts with a main valve seat (46) fixed to the housing, so as to form the main valve (61), which controls a second outlet cross section of the outlet passage (49) and from which the outlet passage (49) leads onwards in the downstream direction.
3. Fuel injection device according to Claim 2, characterized in that there is an outer passage cross section to the main valve seat (46) between the wall (45) of the valve space (30) and the follower valve member (54).
4. Fuel injection device according to Claim 3, characterized in that the main valve seat (46) is formed at the transition of the valve space (30) to an annular space (48) through which the valve plunger (35) penetrates and from which the outlet passage (49) leads onwards.
5. Fuel injection device according to Claim 4, characterized in that the control valve member (34) can be moved over defined strokes by the piezo actuator (41), and when the control valve member (34) is actuated in order to relieve the pressure in the valve space (30) via the first outlet cross section of the outlet passage during a first stroke the valve head sealing surface (51) of the pilot valve (58) is lifted off the pilot valve seat (52), and during a subsequent further stroke of the control valve member (34) the follower valve member (54) is lifted off the main valve seat (46) and the second outlet cross section of the outlet passage (49) is opened.
6. Fuel injection device according to Claim 5, characterized in that the follower valve member (54) is lifted off the main valve seat (46) by a driver (63) arranged on the control valve member (34).
7. Fuel injection device according to Claim 6, characterized in that the driver (63) is a ring which is inserted into an annular groove in the plunger (35) and, when the pilot valve (58) is closed, is at a distance h1, which defines a pilot control stroke, from the end side (64) of the follower valve member (54).
8. Fuel injection device according to Claim 5, characterized in that the follower valve member (54) is loaded towards the valve head sealing surface (251, 451) by a compression spring (272, 472) which is supported in a fixed position on the housing, and, after the pilot valve (58) has opened and there has been a corresponding drop in pressure upstream of the pilot control valve, is moved away from the main valve seat (46) towards the valve head sealing surface (251, 451), so as to follow the latter.
9. Fuel injection device according to Claim 6 or 7, characterized in that the follower valve member (54) is spaced apart from the adjacent plunger (35), so as to form the inner passage cross section, and guided by means of longitudinal spacer ribs (57).
10. Fuel injection device according to Claim 6, 7 or 9, characterized in that the follower valve member (54), on its outer lateral surface, has longitudinal spacer ribs (60), by means of which it is guided on a cylindrical circumferential wall (45) of the valve space (30), so as to form the outer passage cross section.
11. Fuel injection device according to one of the preceding Claims 2 to 10, characterized in that the valve plunger (135, 335) is provided, in the region of its part which leads away from the annular space (48) and is guided in the housing, with a sleeve (166, 366), the external diameter of which is larger than the diameter of the inner delimiting surface (53) of the follower valve member (54).
12. Fuel injection device according to Claim 11, characterized in that the sleeve (166, 366) is pressed onto the valve plunger (135, 335).
13. Fuel injection device according to Claim 11, characterized in that the sleeve (166) is clamped onto the valve plunger (135) between a holding disk (168), which is fixed to the valve plunger outside its guidance, and a stop (167) on the valve plunger (135).
14. Fuel injection device according to Claim 8, characterized in that the follower valve member (54) is guided by means of a cylindrical inner delimiting surface (453) on the cylindrical outer surface (455) of the plunger (453), and an annular recess (480), which is in constant communication with the annular space (48), is provided in the region of overlap between the inner delimiting surface and the outer surface of the plunger (435).
15. Fuel injection device according to one of Claims 11 to 13, characterized in that a sealing surface (375) is provided at the end side of the sleeve (366), and the opposite side of the follower valve member (354) likewise has an additional sealing surface (376), which sealing surfaces together form a third valve (379), which opens towards the inner passage cross section and is closed when the valve plunger (335) has covered its stroke for opering the first outlet cross section of the pilot valve (58) (Figure 5).
16. Fuel injection device according to Claim 15, characterized in that the sealing surfaces of the third valve (479) are conical in form.
17. Fuel injection device according to one of the preceding claims, characterized in that the control space (24) is constantly connected to the high-pressure source (1) via an entry restrictor (28), the cross section of flow of the entry restrictor being smaller than the first outlet cross section (32) of the outlet passage (29, 49).
18. Fuel injection device according to Claim 17, characterized in that the effective outlet cross section of the outlet passage (49) is limited by an outlet restrictor (32).
19. Fuel injection device according to Claim 17 or 18, characterized in that the control space (24) is connected to the valve space (30) via a connecting passage (29) which leads out coaxially with respect to the axis of the valve plunger (35).
20. Fuel injection device according to Claim 19, characterized in that the exit of the connecting passage (29) into the valve space (30) can be closed off from the control space by an end side (271, 471), designed as a sealing surface, of the valve head (235, 435) of the control valve (231, 431) and is closed at the end of the pilot control stroke of the control valve member after a duration of the relief of the control space (24) which is determined by the actuating movement of the control valve member.
21. Fuel injection device according to Claim 20, characterized in that the outlet restrictor (32) is arranged in the connecting passage (29).
22. Fuel injection device according to one of Claims 1 to 16, characterized in that the valve space (530) is connected to the high-pressure fuel store (1) via a pressure passage (526) that enters the valve space (530) coaxially with respect to the axis of the valve plunger (535) and to the control space via a non-closeable connecting passage (529), it being possible to close off the entry of the pressure passage (526) into the valve space by an end side (571), designed as a sealing surface, of the valve head (537) of the control valve member at the end of the stroke of the control valve member which is used to relieve the control space (530), in order to define the start of relief of the control space for the main injection.

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