EP1520095B1 - Control of a pressure exchanger by displacement of an injection valve member - Google Patents

Description

Technical area

To supply combustion chambers of self-igniting internal combustion engines with Fuel can be used both pressure-controlled and stroke-controlled injection systems become. As fuel injection systems come next to pump-nozzle units, pump-line-nozzle units also storage injection systems are used. accumulator injection (Common Rail) allow advantageously the injection pressure to load and to adjust the speed of the self-igniting internal combustion engine. To achieve high specific power and to reduce the emissions of the internal combustion engine In general, the highest possible injection pressure is required.

State of the art

For strength reasons, the achievable pressure level in today used storage injection systems currently limited to about 1600 bar. For further pressure increase On accumulator injection systems, common-rail systems are used for pressure booster Commitment.

DE 199 10 970 A1 relates to a fuel injection device. This fuel injection device has one between an accumulator chamber and a nozzle chamber arranged pressure booster unit, whose pressure chamber via a pressure line connected to the nozzle chamber. Furthermore, a connected to the pressure accumulator space Bypass line provided. The bypass line is directly connected to the pressure line connected. The bypass line is suitable for pressure injection and is parallel arranged to the pressure chamber, so that the bypass line regardless of the movement and position of a displaceable pressure medium of the pressure booster unit throughout is. This measure increases the flexibility of the injection. A difference room is connected via a 2/2-way valve with a leakage line and it is a connection from the differential space to the pressure storage room. The pressure booster unit is a valve assembly for controlling the same outside the injector at any one Place assigned between the accumulator chamber and the injector.

DE 100 40 526 A1 also relates to a fuel injection device. This one has between a pressure accumulator space and a nozzle chamber arranged pressure booster unit on, comprising a displaceable piston unit to the pressure of the To increase nozzle space to be supplied fuel. The piston unit points to the control the pressure intensifier unit a transition from a larger to a smaller one Piston cross-section and a differential space formed thereby. The difference space is connected via a filling path with a filling valve to the pressure storage space. There will be a reduction in the amount of control during the activation of the Pressure booster unit and performing a quick reset of the piston unit reached.

In view of further increasing demands on emissions and noise self-igniting internal combustion engines are further measures on the injection system necessary to meet the more stringent limits expected in the near future fulfill.

Presentation of the invention

With the proposed solution according to the invention is a control of a Kraussstoffinjektors a fuel injection system with an actuator possible, reducing the manufacturing cost and the production costs can be significantly reduced. In particular it is possible with the solution proposed by the invention, a pressure intensifier under Dispensing with a separate actuator directly via the movement of an injection valve member, which is designed in an advantageous manner as a nozzle needle to achieve. Of the Pressure booster can be switched on during the opening movement of the injection valve member become. The pressure booster comprises a working space and control room separating it Piston unit on which a partial stroke is adjustable, after passing through the pressure booster can be switched on. This can be with regard to the design of a fuel injector achieve considerable advantages with a pressure intensifier. They are, for example multiple pilot injections into the combustion chamber of a self-igniting internal combustion engine possible without activating the pressure intensifier. It can therefore a pilot injection is generated, which takes place at a pressure level which is in the essentially in the interior of a high-pressure accumulator space (common rail) prevailing Pressure levels corresponds. After passing through the on the piston unit of the pressure booster set stroke can be a main injection with activated pressure booster achieved during which the main injection during the emissions the self-igniting internal combustion engines adjusts favoring high pressure level, which is higher than that in the interior of a high-pressure storage space (Common rail) prevails. This can be a boat-shaped injection achieve since the first injection phase (pre-injection phase) takes place at a lower pressure and then followed by a pressure increase to translated injection pressure. By the Activation of the intensifier can build up pressure during the main injection phase to the maximum allowable pressure with the injection valve member in the open position be achieved. Furthermore, can be with the inventively proposed solution the pressure booster before closing the injection valve member, which preferably as a nozzle needle is formed reach, causing pressure peaks above the maximum Avoid injection pressure when closing the needle. This has a favorable effect the life of the fuel injection system on a self-igniting internal combustion engine out. Furthermore, with the solution according to the invention, a main injection phase can be achieved reach downstream post-injection phase under very high injection pressure, as well as a remote post-injection, which in a slightly longer sized Time interval follows the main injection.

drawing

With reference to the drawing, the invention will be described below in more detail.

Figur 1

eine Ausführungsvariante eines über ein Einspritzventilglied betätigten Druckübersetzers in einem ersten Zustand,

Figur 2

die Ausführungsvariante der erfindungsgemäß vorgeschlagenen Lösung gemäß Figur 1 mit einem Druckübersetzer in einem zweiten Zustand,

Figur 3

eine weitere Ausführungsvariante eines über ein Einspritzventilglied betätigbaren Druckübersetzers mit zwei ineinandergeführten Ventilelementen und

Figur 4

eine Ausführungsvariante eines über ein Einspritzventilglied betätigten Druckübersetzers mit zwei Ventilelementen, von denen eines federbeaufschlagt gestaltet ist.

It shows:

FIG. 1

an embodiment of an actuated via an injection valve member pressure booster in a first state,

FIG. 2

the embodiment of the solution proposed according to the invention according to FIG. 1 with a pressure booster in a second state,

FIG. 3

a further embodiment of an actuatable via an injection valve member pressure booster with two nested valve elements and

FIG. 4

an embodiment of an actuated via an injection valve member pressure booster with two valve elements, one of which is designed spring-loaded.

variants

FIG. 1 is a first embodiment of an actuatable via an injection valve member Removable pressure intensifier, which is shown in a first state, in which the Control chamber of the pressure booster from the return, i. from the low pressure area of the fuel injection system is disconnected.

From a high-pressure source 1, which, for example, as a high pressure storage space (Common Rail) may be formed, a high-pressure inlet 2 extends to a Pressure Translator 3. The high pressure inlet 2 comprises a high pressure line 7, in a Check valve 8 may be included. Parallel to the high pressure line 7 is through the high pressure inlet 2 from the high pressure source 1 from a parallel branch 11 is applied, in which a filling valve 10 may be included. To this runs another parallel branch 12, which includes a throttle 13. The former, the filling valve 10 receiving Parallel branch opens as well as the other parallel branch 12, the throttle point 13 receives, in a control chamber 15 of the pressure booster 3. The pressure booster 3 comprises In addition, a working space 14, which also via the high-pressure inlet 2 is in communication with the high pressure source 1.

In the pressure booster 3 are the working space 14 and the control chamber 15 by a piston unit 17 separated from each other. The piston unit 17 can be both on and be formed in several parts and includes a portion having a larger diameter is formed and with its front side the working space 14 of the pressure booster third limited, as well as a contrast formed with a reduced diameter piston part, whose lower end side limits a compression space 18 of the pressure booster 3. From the compression chamber 18 of the pressure booster 3 from a compression line extends 20, which in the further course of the high-pressure inlet 7, the Check valve 8 contains, combined and together with this in a nozzle chamber inlet 9 passes. Within the control chamber 15 of the pressure booster 3 is a spring element 16th received, which acts on a bottom of the piston unit 17 and on Floor of the control room 15 is supported. The pressure booster 3 is located within the injector body 5, wherein the control chamber 15 of the pressure booster 3, a control line 19th which in turn is connected to an annular space 33 of a valve element 27.

The nozzle inlet 9, in which both the high pressure line 7 and the compression line 20, which extends from the compression chamber 18, opens, opens at a Orifice 37 into a nozzle space 36.

From the nozzle chamber inlet 9 branches off a high-pressure branch 22, which is an inlet throttle element 23 includes. The high-pressure branch 22 opens into a control chamber 21 within a Nozzle body 6 of the fuel injector 4. The control chamber 21 is via a 2/2-way valve trained control valve 25 pressure relieved. Between the control valve 25 (2/2-way valve) and the control chamber 21, an outlet throttle element 24 is received. On the low pressure side of the control valve 25 (2/2-way valve) is a low-pressure side Return 26, which in a fuel tank, not shown here of a motor vehicle empties. The control valve 25 can procure both as a solenoid valve and as a valve be, which is actuated with a piezoelectric actuator. In addition, the control valve 25 also be a servo valve as well as a directly operable valve.

The fuel injector 4 shown in Figure 1 comprises an injection valve member 34, which is advantageously designed as a nozzle needle. The injection valve member 34 is acted upon in the embodiment of Figure 1 by a one-piece valve element 27, which may be designed as a valve piston. The end face 29 of the integrally formed valve element 27 limits the control chamber 21, which can be filled via the inlet throttle point 23 and pressure relief via the outlet throttle point 24. Below the control chamber 21 formed as a valve piston one-piece valve element 27 is surrounded by an annular space 33, in which the control line 19 opens, which connects the annular space 33 with the control chamber 15 of the pressure booster 3. On the annular space 33, a control edge 31 is formed, which cooperates with a control edge 30, which is embodied on the one-piece valve element 27. In the illustration according to FIG. 1, the control edges 30 and 31 are at a stroke h ₁ , cf. Reference numeral 32, in overlap. Below the one-piece valve element 27, a further hydraulic space is formed within the nozzle body 6, from which also a second low-pressure side return 26.2 branches off to the not shown in Figure 1 fuel tank of the motor vehicle.

The nozzle chamber inlet 9 acts on the nozzle chamber 36 of the fuel injector 4 within the nozzle body 6 with high pressure fuel, so that at a formed on the peripheral surface of the injection valve member 34 pressure shoulder 35 a in Opening direction acting hydraulic force sets. From the nozzle chamber 36 within the Nozzle body 6, an annular gap 38 extends to a combustion chamber-side seat 40 of the Injection valve member 34. Below the combustion chamber side seat 40 are injection openings 39 arranged, for example, as an annular rows of holes, as one or more may be formed concentrically with each other extending hole circles. In the in Figure 1 shown position of the injection valve member 34, the injection openings 39th closed by the driven in the combustion chamber side seat 40 injection valve member 34, so that no fuel in a combustion chamber 41 of the self-igniting internal combustion engine can get. The closed position of the injection valve member 34 with respect to Injection openings 39 are identified by the reference numeral 42 in the illustration according to FIG. In this position of the injection valve member 34 is no injection of Fuel in the combustion chamber 41 of the self-igniting internal combustion engine instead.

According to the number of cylinders of the self-igniting internal combustion engine comprises the fuel injection system includes a number of fuel injectors 4, each of which Fuel injectors 4 comprises a pressure booster 3 and each fuel injector 4 a Control valve 25 is assigned. In the working condition shown in Fig. 1, i. sealed Injection openings 42, there is the control valve 25, which preferably as a 2/2-way control valve is configured, in its closed position, i. the control room 21 of Injection valve member 34 and the low-pressure side return 26 are separated from each other. By the overlap of the control edge 31 on the nozzle body 6 and the control edge 30 on the one-piece valve element 27 is formed by the control edges 30 and 31, respectively Slide seal closed. The injection valve member 34 is located in his combustion chamber side injection openings 39 occluding position 42, the piston unit 17 of the pressure booster 3 is pressure balanced, so that no pressure gain takes place. In this state shown in Figure 1, the filling valve 10 in the first parallel line 11, which branches off from the high-pressure inlet 2, opened and the piston unit 17 of the Pressure booster 3 is in its initial position. The interior of a high-pressure storage room (Common Rail) prevailing pressure, to provide an example of a high pressure source To call 1, is about the open filling valve 10 at the rear of the 15 Pressure Translator 3 and passes through the recorded in the high-pressure line 7 Check valve 8 to the control chamber 21 of the fuel injector 4 and to the nozzle chamber 36. In this operating state can at any time an injection with the in the High pressure source 1 prevailing pressure level, the rail pressure level, take place.

If the control valve 25, which can be preferably formed as a 2/2-way valve, however, switched to its open position, a pressure relief of the control chamber 21 via the outlet throttle 24 in the first low-pressure side return 26.1 to the low pressure side of the fuel injector 4. Due to decreasing pressure in the control chamber 21 of the fuel injector 4 outweigh the acting on the pressure shoulder 35 of the injection valve member 34 hydraulic forces and the injection valve member 34 opens. An injection of fuel through the combustion-chamber-side injection openings 39 into the combustion space 41 of the self-igniting internal combustion engine begins at the pressure level which the high-pressure source 1 provides. Due to the series connection of the one-piece valve element 27 with the injection valve member 34, the one-piece valve element 27 moves with an opening movement of the injection valve member 34 with its end face 29 in the control chamber 21 of the fuel injector 4 a. If, during this lifting movement, the stroke h ₁ (reference numeral 32) is exceeded, the control edges 30 and 31 are no longer in the state shown in FIG. 1, ie in their covered state, but open, so that the slide seal is open. As a result, the control chamber 15 of the pressure booster 3 is connected via the control line 19, which connects the control chamber 15 with the annular space 33, with the second low-pressure side return 26.2. Since the control chamber 15 of the pressure booster 3 is now depressurized in the low pressure and filling valve 10 closes, the piston unit 17 of the pressure booster 3 is no longer pressure balanced, so that the pressure within the working chamber 14 of the pressure booster 3 outweighs and the piston unit 17 with its lower end face in the compression space 18 retracts. Corresponding to the pressure surface conditions on the piston unit 17 of the pressure booster 3, the piston unit 17 enters the compression space 18, so that via the compression space line 20, which opens together with the high pressure line 7 from the high pressure source 1 into the nozzle inlet 9, in the nozzle chamber 36 a translated ie higher pressure is present than the high-pressure source 1 is able to apply on its own. The fuel in the compression chamber 18 is compressed during retraction of the piston unit 17 with its lower end side in this, so that above the nozzle inlet 9 in the nozzle chamber 36 is a higher, ie translated pressure is present.

The injection takes place from the exceeding of the stroke h ₁ (see reference numeral 32) with a translated, ie higher pressure. This can be a boat-shaped injection achieve. The first injection phase, for example the pre-injection phase, takes place at the pressure level which is available, for example, as a high-pressure reservoir (common rail) high-pressure source 1, followed by another injection phase at a much higher injection pressure level, which is due to the pressure surface conditions the piston unit 17 of the pressure booster 3 results and is present on the compression space line 20 in the nozzle chamber 36 in the nozzle body 6 of the fuel injector 4.

Figure 2 shows the embodiment of a fuel injector according to Figure 1 with a Pressure intensifier in a second state.

In Figure 2 it is shown that the housing-side control edge 31 in the nozzle body 6 and the control edge 30 of the one-piece valve element 27 are out of overlap, whereby There is a low-pressure side connection 50 between the control chamber 15 of the pressure booster 3 via the control line 19, in the annular space 33, which is the one-piece design Valve element 27 surrounds, adjusts. The control chamber 15 is in this way on the second low-pressure side return 26.2 relieved, so that the piston unit 17 due of the pressure prevailing in the working space 14 of the pressure booster 3 pressure in the compression space 18 of the pressure booster 3 contained fuel volume and compressed over the Compression space line 20, the nozzle inlet 9 in the nozzle chamber 36 of the nozzle body 6 promotes. The injection valve member 34 of the fuel injector 4 is now in its raised position 51, i. its open position, so that fuel accordingly the pressure-translated elevated pressure level via the nozzle chamber 36, the annular gap 38 and the released injection ports 39 with very high pressure in the combustion chamber 41st the self-igniting internal combustion engine is injected.

To end the injection, the control valve 25, which preferably as a 2/2-way valve is formed, closed, so that in the control chamber 21 of the injection valve member 34 sets a pressure build-up. Due to the application of the end face 29 of the one-piece Valve element 27 moves with this cooperating injection valve member 34 in the closing direction. Upon reaching the control edge 31 on the nozzle body 6 takes place an overlap of the control edges 30 and 31 with each other, so that the formed by them Slider seal is closed. As a result, the connection of the control room 15 via the control line 19 and the annular space 33 in the low-pressure side return 26th closed and the pressure booster 3 thus deactivated. The injection valve member 34 moves further into its combustion chamber side seat 40 and thereby closes to a later time in the combustion chamber 41 of the self-igniting internal combustion engine opening injection openings 39. Since the pressure booster 3 is already deactivated, Pressure peaks that occur when closing the injection valve member 34, compensated.

By the stroke h ₁ (reference numeral 32) and the closing speed of the injection valve member 34 and the valve member 27 can be the shutdown time of the pressure booster 3, that is, the timing of the overlap of the control edges 30 and 31, tune optimally to the end of the respective injection phase. For small injection quantities, for example as part of a pre-injection, the injection valve member 34, which is preferably designed as a nozzle needle, not completely along the entire stroke h ₁ (reference numeral 32) are opened, so that the pressure booster 3 remains deactivated. Thus, any number of pilot injections can be realized without activated pressure booster 3. The pressure level within the scope of the pilot injection for conditioning the combustion mixture contained in the combustion chamber 41 is within the scope of these pilot injections at the pressure level which the high-pressure source 1, for example a high-pressure reservoir (common rail), provides and can not be increased to that achievable by the pressure booster 3 pressure level. The number and duration of the respective pilot injection phases and the duration of the main injection at an elevated pressure level can be adjusted by the activation time of the control valve 25.

From the illustration according to FIG. 3, a further embodiment variant of FIG Injector valve operated pressure intensifier with two valve elements in one another out.

Also, the Ksaftstoffinjektor 4 shown in Figure 3 for fuel supply of a self-igniting Internal combustion engine comprises an integrated in the injector body 5 Compressor 3. From a high pressure source 1 via a high-pressure inlet 2 a high-pressure line 7, a first parallel branch 11 and a further parallel branch 12 and the working space 14 of the pressure booster 3 acted upon. In the first parallel branch 11 is a filling valve 10, 12 further included a throttle point 13 in parallel branch. In the high-pressure line 7, a check valve 8 is received.

The pressure intensifier 3 according to the further embodiment in Figure 3 comprises analog for the pressure booster 3 shown in FIG. 1, a piston unit 17 which houses the working space 14 separates from the control room 15. With the underside of the piston unit 17, the compression space 18 in the injector body 5 of the pressure booster 3 is acted upon by the compression space line 20 branches off to the nozzle chamber inlet 9 and with the high pressure line 7 united by the high pressure source 1.

In contrast to the embodiment of the solution proposed according to the invention shown in FIGS. 1 and 2, the injection valve member 34 is acted on by a multipart valve element 28, as shown in FIG. The multi-part valve element 28 comprises a first valve element 28.1 and a further, second valve element 28.2 surrounding this. The first valve element 28.1 and the further valve element 28.2 can be formed in the shape of a piston. An annular surface 60 on the second valve element 28.2 partially delimits the control chamber 21. In the second valve element 28.2, an opening 61 is formed, via which an end face 62 of the first valve element 28.1 can be acted upon by the pressure prevailing in the control chamber 21. According to this embodiment, a stroke h ₁ (reference numeral 32) is set between the inner, first valve element 28. 1, ie its end face 62, and a collar at the opening 61 in the second valve element 28. 2 of the multi-part valve element 28. On the second valve element 28.2 is the control edge 30, which cooperates with a seat of a valve chamber 63. In the valve chamber 63 opens above the seat, the control line 19 from the control chamber 15 of the pressure booster 3. From the valve chamber 63 branches off a first return line 64 to the low pressure side of the fuel supply system. On the first valve element 28.1, a piston extension 66 is formed, which has a smaller diameter than the piston part of the first valve element 28.1. The piston extension 66 passes through a further, arranged below the valve chamber 63 in the nozzle body 6 cavity in which a closing spring 67 is received. The end face of the piston extension 66 bears against the end face of the injection valve member 34, which is preferably in the form of a nozzle needle.

When pressure relief of the control chamber 21 by preferably designed as a 2/2-way valve Control valve 25 and simultaneous loading of the nozzle chamber 36 of the injection valve member 34, is above the nozzle chamber inlet 9 in the nozzle chamber 36 a the Pressure shoulder 35 of the injection valve member 34 acting on a hydraulic force. The injection valve member 34 opens, so that, for example, a pilot injection via the injection port 39 in a combustion chamber, not shown here, of an internal combustion engine achieve. However, the pilot injection takes place only at the pressure level instead, which rests in the high-pressure source 1, since the pressure booster 3 at this time not yet activated. Upon further pressure relief of the control chamber 21 drives the End face 62 of the internally arranged, the first valve element 28.1 to the collar-shaped Stop the second, outer valve element 28.2 and takes the outside, second valve element 28.2 in the opening direction with. This gives the control edge 30 on the outer circumference of the second valve element 28.2 the connection of the control chamber 15 via the control line 19 and the valve chamber 63 in the first return line 64th free, so that a pressure relief of the control chamber 15 of the pressure booster 3 takes place. The piston unit 17 of the pressure booster 3 thus moves into the compression space 18th a, so that the compression space line 20, the nozzle space inlet 9 at the discharge point 37 under high pressure fuel in the nozzle chamber 36 in the nozzle body 6 is headed. It can now one on a corresponding to the pressure gain the pressure booster 3 increased pressure level lying subsequent injection in the Combustion chamber of the self-igniting internal combustion engine done. The illustrated in Figure 3, further embodiment variant of a fuel injector according to the invention comprises in addition to the first return line 64, which branches off from the valve chamber 63, a second return line 65 in the low pressure region of the fuel supply system, which of the closing spring member 67 receiving cavity above the injection valve member 34 branches off. The stop point from which the end face 62 of the inner, first Valve element 28.1 abuts the outer, second valve element 28.2 and this entrains with further pressure relief of the control chamber 21 in the opening direction, is identified in the illustration of Figure 3 with reference numeral 68.

The remaining, not individually described components of the fuel injector 4 according to the embodiment shown in Figure 3, correspond substantially the components that in the embodiment of the fuel injector according to the invention have already been described according to Figure 1 and 2.

FIG. 4 shows a variant of an embodiment of an injection valve member actuated Pressure booster with two valve elements, one of which is spring-loaded is.

From the high-pressure source 1, the high-pressure inlet 2 extends over both High-pressure line branch 7, which contains a check valve 8 as well as a first Parallel branch 11 and another parallel branch 12 to the control chamber 15 of the pressure booster 3. In addition, the high-pressure source 1, for example, acts on a high-pressure storage space (Common rail), the working space 14 of the pressure booster 3 directly. The working chamber 14 and the control chamber 15 of the pressure booster 3 are via a piston unit 17 separated from each other, wherein the working space 14 zuweisende end face the piston unit 17 has a larger diameter than that end face of the Piston unit 17, which limits the compression space 18 of the pressure booster 3. From the compression space 18 within the injector body 5 of the fuel injector 4 extends a compression space line 20, which is connected to the check valve. 8 receiving high pressure line 7 combined and merges into the nozzle chamber inlet 9.

The control chamber 21 within the fuel injector 4 is via a high-pressure branch 22 pressurized with inlet throttle point 23 and is via an outlet throttle point 24th upon actuation of a control valve 25 in the low-pressure side return 26 pressure relieved.

Also comes in the embodiment of the fuel injector 4 shown in Figure 4 a multipart valve element 28 is used. The multi-part trained Valve element 28, which the injection valve member 34 in the nozzle body 6 of the fuel injector 4 acted upon, comprises a first valve element 28.1, whose end face 62 the control chamber 21 limited. The first valve element 28.1 comprises a piston extension 66, which with its lower end face abuts the end face of the injection valve member 34. The first Valve element 28.1 is surrounded by a second, further valve element 28.2, wherein between the first valve element 28.1 and the second valve element 28.2 a Passage gap 72 sets. In contrast to the embodiment shown in Figure 3 does not limit the second valve element 28.2 the control chamber 21, but is below of the first valve element 28.1 arranged and on its annular surface 60 of a spring element 70 charged. The spring element 70 is supported on the top 71 of the valve chamber 63 in the nozzle body 6 of the fuel injector 4 from.

By arranged in the valve chamber 63 spring element 70 is the second, sleeve-shaped trained valve element 28.2 pressed with its control edge 30 in its closed position, so that the valve seat between the control edge 30 and housing edge 31 of the valve chamber 63 is closed in the rest position and the pressure booster 3 is deactivated. Since the Seat by the control edges 30 on the second valve element 28.2 and the control edge 31 am Valve chamber 63 is closed, a pressure relief of the control chamber 15 via the line 19 in the valve chamber 63 is not possible, so that the piston unit 17 between the working space 14 and the control chamber 15 of the pressure booster 3 in their starting position located. To increase the closing force on the control edge 30 may be a closing hydraulic pressure force by a corresponding pressure level within the valve chamber 63 are generated.

After activation of the control valve 25, which is preferably designed as a 2/2-way valve, there is a pressure relief of the control chamber 21, so that the first valve element 28.1 with its end face 62 enters this. If the control chamber 21 above the end face 62 of the first valve element 28.1 as long pressure relieved that the end face of the injection valve member 34 abuts the lower annular surface of the second valve element 28.2, ie the stroke is exceeded h ₁ (reference numeral 32), the pressure booster 3 through the injection valve member 34 activated because due to the force acting on the pressure shoulder 35 hydraulic force in the nozzle chamber 36 of the sealing seat between the control edges 30 on the second valve element 28.2 and the control edge 31 of the valve chamber 63 is opened and a pressure reduction in the control chamber 15 of the pressure booster 3 via the line 19 in the first low-pressure side return 64 can take place. As a result, the fuel compressed in the compression space 18 of the pressure booster 3 is in the nozzle space 36 via the compression space line 20 to the nozzle chamber inlet 9 at the discharge point 37 of the nozzle chamber inlet 9 in the nozzle chamber 36. With the solution shown in Figure 4 can be given a certain pressure relief of the control chamber 21 of the injection valve member 34 within certain limits, ie so that the Auffahrweg of the injection valve member 34 below the stroke h ₁ (reference numeral 32), pilot injection phases on the pressure prevailing in the high pressure source 1 pressure level represent, from a further sustained pressure relief of the control chamber 21 via the injection valve member 34, an activation of the pressure booster 3 takes place, and a main injection phase can be realized with rate-shaping at an elevated pressure level. According to the Ansteuerzyklus' of the control valve 25, one or more pilot injection phases can be made, only depending on the drive times and the control program of the control valve 25, which can be preferably designed as a 2/2-way valve. With the proposed embodiments according to the invention shown in Figures 1 and 2 or 3 and 4, an injection of fuel into the combustion chamber 41 of a self-igniting internal combustion engine below a Nadelhubes h ₁ (reference numeral 32) carried out with a first pressure level, for example, the pressure level of a high-pressure source. 1 equivalent. From exceeding a stroke h ₁ (reference numeral 32) effected by the injection valve member 34 activation of a pressure booster 3, so that a follow-up injection at an elevated pressure level follows This allows on the one hand a boat-shaped injection, since the first injection phase (pre-injection) at a lower Pressure level takes place as the subsequent main injection. By the activation of the pressure booster 3 by the vertical lifting movement of the injection valve member 34, the concern of an increased pressure level takes place precisely when it is process-technically necessary according to the combustion progress in the combustion chamber 41 of the self-igniting internal combustion engine. For small injection quantities, a pre-injection of the injection valve member 34 by a controlled pressure relief of the control chamber 21 with respect to its discharge duration not until reaching the stroke h ₁ (reference numeral 32), so that the pressure booster 3 remains disabled. It is therefore possible with the inventively proposed solution any number of pilot injections on a low compared to the activated pressure booster 3 pressure level, the fuel injector 4 according to the invention proposed solution only with a control valve 25 is operable.

LIST OF REFERENCE NUMBERS

1

High pressure source (common rail)

2

High-pressure inlet

3

Pressure intensifier

4

fuel injector

5

injector

6

nozzle body

7

High-pressure line

8th

check valve

9

Branch nozzle space inlet

10

filling valve

11

first parallel branch

12

another parallel branch

13

restriction

14

working space

15

control room

16

spring element

17

piston unit

18

compression chamber

19

Control line for control room

20

Compression chamber line

21

control room

22

High pressure branch to the control room

23

Inlet restrictor

24

Flow restrictor

25

Control valve (2/2-way valve)

26.1

first low-pressure side return

26.2

second low-pressure side return

27

one-piece valve element

28

multi-part valve element

28.1

first valve element

28.2

second valve element

29

End face one-piece valve element

30

Control edge valve element

31

Control edge housing

32

Stroke h ₁

33

Annular valve element

34

Injection valve member

35

pressure shoulder

36

nozzle chamber

37

Discharge point nozzle chamber inlet

38

annular gap

39

Injection port

40

combustion chamber side seat

41

combustion chamber

42

closed injection port

50

Low-pressure side connection

51

Injector member 34 (raised position)

52

released injection openings

60

Ring surface second valve element

61

Through opening

62

Front side first valve element

63

valve chamber

64

first return line

65

second return line

66

Piston extension

67

closing spring

68

Stop first valve element on the second valve element

70

Spring element for second valve element

71

Stop spring element

72

overflow gap

Claims (17)

1. Device for the injection of fuel into a combustion space (41) of an internal combustion engine, with an injector body (5, 6) receiving an injection-valve member (34) which can be actuated by a control space (21) subjected to/relieved of pressure, this brought about via a control valve (25), and with a pressure intensifier (3) comprising a piston unit (17) which separates a working space (14) and a control space (15) and which acts upon a compression space (18) connected (9, 20) to a nozzle space (36) surrounding the injection-valve member (34), characterized in that the control space (15) of the pressure intensifier (3) is subjected to (2, 11, 12)/relieved of (19, 26, 64) pressure as a function of the stroke movement of the injection-valve member (34).
2. Device for the injection of fuel according to Claim 1, characterized in that the injection-valve member (34) is assigned a valve element (27, 28) which is movable within a hydraulic space (33, 63) into which a control line (19) from the control space (15) of the pressure intensifier (3) issues.
3. Device for the injection of fuel according to Claim 2, characterized in that the valve element (27, 28) arranged within the hydraulic space (33, 63) acts upon that end face of the injection-valve member (34) which faces away from the injection orifices (39) located on the combustion-space side.
4. Device for the injection of fuel according to Claim 2, characterized in that the valve element (27, 28) projects with a face (29, 60, 62) capable of being acted upon hydraulically into a control space (21) subjecting the injection-valve member (34) to pressure.
5. Device for the injection of fuel according to Claim 2, characterized in that the valve element (27) is of one-part design and has a control edge (30) which, with a control edge (31) on the hydraulic space (33), forms a slide seal.
6. Device for the injection of fuel according to Claim 2, characterized in that a return line (26.2, 64) branches off from the hydraulic space (33, 63) into the low-pressure region.
7. Device for the injection of fuel according to Claims 5 and 6, characterized in that, in the event of a stroke movement of the injection-valve member (34) which is triggered by the control space (21) being relieved of pressure and which is smaller than a stroke travel h₁ (32) - the overlap of the control edges (30, 31) -, the slide seal (30, 31) remains closed and an injection of fuel into a combustion space (41) at a first pressure level takes place.
8. Device for the injection of fuel according to Claims 5 and 6, characterized in that, in the event of a stroke movement of the injection-valve member (34) which is triggered by the control space (21) being further relieved of pressure and which exceeds the stroke travel h₁ (32), the control space (15) of the pressure intensifier (3) can be connected via the control line (19) and the open control edges (30, 31) to the second return (26.2) located on the low-pressure side and an injection of fuel into a combustion space (41) at a second higher pressure level takes place.
9. Device for the injection of fuel according to Claim 2, characterized in that the valve element (28) is of multi-part design and comprises a first valve part (28.1) and a second valve part (28.2), at least one of which is subjected to the pressure prevailing in the control space (21) of the injection-valve member (34).
10. Device for the injection of fuel according to Claim 9, characterized in that the first valve part (28.1) is guided in the second valve part (28.2), and a stroke travel h₁ (32) is set between one end face (29) of the first valve part (28.1) and a stroke stop (68) of the second valve part (28.2).
11. Device for the injection of fuel according to Claim 10, characterized in that the second valve part (28.2) has a control edge (30) which cooperates with a sealing seat in the hydraulic space (63).
12. Device for the injection of fuel according to Claims 10 and 11, characterized in that, when the control space (21) is relieved of pressure, the first valve part (28.1) moves up against the stop (68) by the amount of the stroke travel h₁ (32), and the injection-valve member (34) executes an injection of fuel into the combustion space (41) at a first pressure level.
13. Device for the injection of fuel according to Claims 10 and 11, characterized in that, when the control space (21) is further relieved of pressure, the first valve part (28.1) opens the second valve part (28.2) at the sealing seat in the hydraulic space (63) after the completion of the stroke travel h₁ (32) and relieves the control space (15) on the low pressure side via the control line (19) and the hydraulic space (63), and an injection of fuel at a second higher pressure level takes place.
14. Device for the injection of fuel according to Claim 9, characterized in that one of the valve parts (28.1, 28.2) of the multi-part valve element (28) is placed into a sealing seat in the hydraulic space (63) under the load of a spring element (70).
15. Device for the injection of fuel according to Claims 9 and 14, characterized in that a piston extension (66) of the first valve part (28.1) passes through the second valve part (28.2) so as to form an annular gap (72), and the piston extension (66) of the first valve part (28.1) acts upon the injection-valve member (34) on the end face.
16. Device for the injection of fuel according to Claims 9 and 14, characterized in that, between the second valve part (28.2) and the injection-valve member (34), a stroke travel h₁ (32) can be predetermined, by the amount of which the injection-valve member (34) can be moved for the injection of fuel at a first pressure level when a control space (21) is relieved of pressure.
17. Device for the injection of fuel according to Claims 9 and 16, characterized in that, when the control space (21) is further relieved of pressure and in the event of an opening movement of the injection-valve member (34) exceeding the stroke travel h₁ (32), the said injection-valve member moves the second valve part (28.2) out of its seat in the hydraulic space (63) and relieves the control space (15) of the pressure intensifier (3) on the low-pressure side via a control line (19), so that an injection of fuel into the combustion space (41) at a second higher pressure level takes place.

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