EP1520095A1

EP1520095A1 - Control of a pressure exchanger by displacement of an injection valve member

Info

Publication number: EP1520095A1
Application number: EP03718646A
Authority: EP
Inventors: Hans-Christoph Magel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-06-29
Filing date: 2003-04-03
Publication date: 2005-04-06
Anticipated expiration: 2023-04-03
Also published as: WO2004003373A1; JP2005531714A; EP1520095B1; DE50301573D1; US20050116058A1; DE10229413A1

Abstract

The invention relates to a device for injecting fuel into a combustion chamber (41) of an internal combustion engine, said device comprising an injection body (5, 6) which receives an injection valve member (34) that can be actuated by subjecting a control chamber to pressure or relieving said control chamber (21) of pressure by means of a control valve (25). Said device also comprises a pressure exchanger (3) provided with a piston unit (17) which separates a working chamber (14) and a control chamber (15) of the pressure exchanger (3), said piston unit acting on a compression chamber (18) which is connected (9, 20) to an injector chamber (36) surrounding the injection valve member (34). The control chamber (15) of the pressure exchanger (3) is either subjected to pressure (2, 11, 12) or relieved of pressure (19, 26.2, 64) according to the reciprocating motion of the injection valve member (34).

Description

Pressure intensifier control by moving an injection valve member

Technical field

Both pressure-controlled and stroke-controlled injection systems can be used to supply the combustion chambers of self-igniting internal combustion engines with fuel. In addition to pump-injector units, pump-line-injector units, accumulator injection systems are also used as fuel injection systems. Accumulator injection systems (common rail) advantageously make it possible to adapt the injection pressure to the load and speed of the self-igniting internal combustion engine. In order to achieve high specific outputs and to reduce the emissions of the internal combustion engine, the highest possible injection pressure is generally required.

State of the art

For reasons of strength, the achievable pressure level is currently limited to around 1600 bar in the case of accumulator injection systems used today. Pressure intensifiers are used on common rail systems to further increase the pressure on accumulator injection systems.

DE 199 10 970 AI relates to a fuel injection device. This fuel injection device has a pressure translation unit arranged between a pressure storage chamber and a nozzle chamber, the pressure chamber of which is connected to the nozzle chamber via a pressure line. A bypass line connected to the pressure storage space is also provided. The bypass line is connected directly to the pressure line. The bypass line can be used for a pressure injection and is arranged parallel to the pressure chamber, so that the bypass line is continuous regardless of the movement and position of a displaceable pressure medium of the pressure translation unit. This measure increases the flexibility of the injection. A differential room can be connected to a leakage line via a 2/2-way valve and it exists a connection from the differential space to the pressure storage space. The pressure translation unit is assigned a valve arrangement for controlling the same outside of the injector at any point between the pressure storage space and the injector.

DE 190 40 526 AI also relates to a fuel injection device. This has a pressure translation unit which is arranged between a pressure storage chamber and a nozzle chamber and which comprises a displaceable piston unit in order to increase the pressure of the fuel to be supplied to the nozzle chamber. To control the pressure booster unit, the piston unit has a transition from a larger to a smaller piston cross section and a differential space formed thereby. The differential space is connected to the pressure storage space via a filling path with a filling valve. A reduction in the control quantity is achieved during the actuation of the pressure booster unit and the piston unit is quickly reset.

In view of the continuously increasing demands on the emission and noise development of self-igniting internal combustion engines, further measures are necessary on the injection system in order to meet the tightened limit values to be expected in the near future.

Presentation of the invention

With the solution proposed according to the invention, control of a fuel injector of a fuel injection system with an actuator is possible, as a result of which the manufacturing outlay and the manufacturing costs can be considerably reduced. In particular, with the solution proposed according to the invention, it is possible to achieve a pressure intensifier without a separate actuator directly via the movement of an injection valve member, which is advantageously designed as a nozzle needle. The pressure intensifier can be switched on when the injection valve member opens. The pressure intensifier comprises a piston unit separating its working space and control space, on which a partial stroke can be set, after the passage of which the pressure intensifier can be activated. This allows considerable advantages to be achieved with regard to the design of a fuel injector with a pressure intensifier. For example, multiple pre-injections into the combustion chamber of a self-igniting internal combustion engine are possible without activating the pressure intensifier. Accordingly, a pre-injection can be generated which takes place at a pressure level which essentially corresponds to that in the interior of a high-pressure storage space (common rail). seeing pressure levels. After driving through the stroke path set on the piston unit of the pressure booster, a main injection with activated pressure booster can be achieved, whereby during the main injection a high pressure level which favors the emissions of the self-igniting internal combustion engines is set, which is higher than that which is in the interior of a high-pressure storage space (common -Rail) prevails. This enables a boat-shaped injection to be achieved, since the first injection phase (pre-injection phase) takes place at a lower pressure and then a pressure increase to the translated injection pressure follows. By activating the pressure intensifier, a pressure build-up to the maximum permissible pressure with the injection valve member in the open position can be achieved during the main injection phase. Furthermore, with the solution proposed according to the invention, the pressure intensifier can be achieved before the injection valve member, which is preferably designed as a nozzle needle, is closed, as a result of which pressure peaks above the maximum injection pressure when the needle is closed can be avoided. This has a favorable effect on the service life of the fuel injection system on a self-igniting internal combustion engine. Furthermore, with the solution according to the invention, a post-injection phase following a main injection phase can be achieved under very high injection pressure, as can a remote post-injection which follows the main injection in a somewhat longer period.

drawing

The invention is described in more detail below with reference to the drawing.

It shows:

FIG. 1 shows an embodiment variant of a pressure booster operated via an injection valve member in a first state,

FIG. 2 shows the embodiment variant of the solution proposed according to the invention according to FIG. 1 with a pressure intensifier in a second state,

FIG. 3 shows a further embodiment variant of a pressure booster which can be actuated via an injection valve member and has two valve elements and which are inserted into one another Figure 4 is a Ausfurrungs Variants of a pressure booster operated via an injection valve member with two valve elements, one of which is designed spring-loaded.

variants

FIG. 1 shows a first embodiment variant of a pressure booster that can be actuated via an injection valve member, which is shown in a first state in which the control chamber of the pressure booster is separated from the return, i.e. is separated from the low pressure area of the fuel injection system.

A high-pressure inlet 2 extends to a pressure booster 3 from a high-pressure source 1, which can be designed, for example, as a high-pressure storage space (common rail). The high-pressure inlet 2 includes a high-pressure line 7, in which a check valve 8 can be accommodated. Parallel to the high-pressure line 7, the high-pressure inlet 2 acts on the parallel branch 11 from the high-pressure source 1, in which a filling valve 10 can be accommodated. A further parallel branch 12, which includes a throttle point 13, runs to this. The first-mentioned parallel branch, which accommodates the filling valve 10, and the further parallel branch 12, which accommodates the throttle point 13, open into a control chamber 15 of the pressure intensifier 3. The pressure intensifier 3 also includes a working chamber 14, which likewise communicates via the high-pressure inlet 2 with the High pressure source 1 is connected.

In the pressure intensifier 3, the working space 14 and the control space 15 are separated from one another by a piston unit 17. The piston unit 17 can be of single or multi-part design and comprises a section which is designed with a larger diameter and with its end face delimits the working space 14 of the pressure booster 3, and a piston part which is designed with a reduced diameter, the lower end face thereof limited a compression space 18 of the pressure booster 3. A compression line 20 extends from the compression chamber 18 of the pressure booster 3, which later unites with the high-pressure inlet 7, which contains the check valve 8, and merges with this into a nozzle chamber inlet 9. A spring element 16 is received within the control chamber 15 of the pressure booster 3, which acts on an underside of the piston unit 17 and is supported on the bottom of the control chamber 15. The pressure booster 3 is located within the injector body 5, the control chamber 15 of the pressure booster 3 having a control line 19, which in turn is connected to an annular space 33 of a valve element 27. The nozzle inlet 9, into which both the high-pressure line 7 and the compression line 20, which extends from the compression space 18, opens, opens into a nozzle space 36 at an outlet point 37.

A high-pressure branch 22, which comprises an inlet throttle element 23, branches off from the nozzle chamber inlet 9. 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 can be relieved of pressure via a control valve 25 designed as a 2/2-way valve. An outlet throttle element 24 is accommodated between the control valve 25 (2/2-way valve) and the control chamber 21. On the low-pressure side of the control valve 25 (2/2-way valve) runs a low-pressure side return 26, which opens into a fuel tank of a motor vehicle, not shown here. The control valve 25 can be designed both as a solenoid valve and as a valve which can be actuated by a piezo actuator. In addition, the control valve 25 can also be a servo valve as well as a directly actuable valve.

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

The nozzle space inlet 9 acts on the nozzle space 36 of the fuel injector 4 within the nozzle body 6 with fuel under high pressure, so that a hydraulic force acting in the opening direction is established on a pressure shoulder 35 formed on the peripheral surface of the injection valve member 34. An annular gap 38 extends from the nozzle chamber 36 within the nozzle body 6 to a seat 40 on the combustion chamber side Injection valve element 34. Below the seat 40 on the combustion chamber side, there are arranged injection openings 39, which can be designed, for example, as ring-shaped rows of holes, or as one or more circles of holes running concentrically to one another. In the position of the injection valve member 34 shown in FIG. 1, the injection openings 39 are closed by the injection valve member 34 moved into the seat 40 on the combustion chamber side, so that no fuel can get into a combustion chamber 41 of the self-igniting internal combustion engine. The closed position of the injection valve member 34 with respect to the injection openings 39 is identified in the illustration according to FIG. 1 by reference numeral 42. In this position of the injection valve member 34, there is no injection of fuel into the combustion chamber 41 of the self-igniting internal combustion engine.

Corresponding to the number of cylinders in the self-igniting internal combustion engine, the fuel injection system comprises a number of fuel injectors 4, each of the fuel injectors 4 comprising a pressure intensifier 3 and a control valve 25 being assigned to each fuel injector 4. In the working state shown in Figure 1, i.e. closed injection openings 42, the control valve 25, which is preferably designed as a 2/2-way control valve, is in its closed position, i.e. the control chamber 21 of the injection valve member 34 and the low-pressure return 26 are separated from each other. Due to the overlapping of the control edge 31 on the nozzle body 6 and the control edge 30 on the one-piece valve element 27, the slide seal formed by the control edges 30 and 31 is closed. The injection valve member 34 is in its position 42 which closes the injection openings 39 on the combustion chamber side, the piston unit 17 of the pressure booster 3 is pressure-balanced, so that no pressure amplification takes place. In this state shown in FIG. 1, the filling valve 10 in the first parallel line 11, which branches off from the high-pressure inlet 2, is open and the piston unit 17 of the pressure booster 3 is in its initial position. The pressure prevailing in the main chamber of a high-pressure storage chamber (common rail), to name an example of a high-pressure source 1, is applied to the rear chamber 15 of the pressure booster 3 via the open filling valve 10 and reaches the control chamber 21 via the check valve 8 accommodated in the high-pressure line 7 of the fuel injector 4 and to its nozzle chamber 36. In this operating state, an injection can take place at any time with the pressure level prevailing in the high-pressure source 1, the rail pressure level.

If, on the other hand, the control valve 25, which can preferably be designed as a 2/2-way valve, is switched to its open position, the pressure in the control chamber 21 is relieved via the outlet throttle 24 into the first low-pressure side return 26.1 to the low-pressure side of the fuel injector 4 falling pressure in the control chamber 21 of the fuel injector 4 outweigh the pressure shoulder 35 of the Injection valve member 34 attacking hydraulic forces and the injection valve member 34 opens. An injection of fuel through the combustion chamber-side injection openings 39 into the combustion chamber 41 of the self-igniting internal combustion engine begins at the pressure level that 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 its end face 29 into the control chamber 21 of the fuel injector 4 during an opening movement of the injection valve member 34. If the stroke distance hi (reference numeral 32) is exceeded during this stroke movement, the control edges 30 and 31 are no longer in the state shown in FIG. 1, ie in their covered state, but are open so that the slide seal is open. As a result, the control chamber 15 of the pressure booster 3 is connected to the second return 26.2 on the low-pressure side via the control line 19, which connects the control chamber 15 to the annular chamber 33. Since the control chamber 15 of the pressure booster 3 is now depressurized to the low pressure and the 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 predominates and the lower end face of the piston unit 17 is in enters the compression space 18. Corresponding to the pressure area conditions on the piston unit 17 of the pressure booster 3, the piston unit 17 moves into the compression chamber 18, so that via the compression chamber line 20, which opens together with the high pressure line 7 from the high pressure source 1 into the nozzle inlet 9, enters the nozzle chamber 36 translated, ie higher pressure is present than the high pressure source 1 can apply alone. When the piston unit 17 is retracted, the lower end face of the fuel in the compression chamber 18 is compressed into the latter, so that a higher, ie translated pressure is present in the nozzle chamber 36 via the nozzle inlet 9.

The injection takes place from the exceeding of the stroke h] (see reference number 32) with a translated, i.e. higher pressure. This enables a boat-shaped injection to be achieved. The first injection phase, for example the pre-injection phase, takes place at the pressure level available at the high pressure source 1, which is designed, for example, as a high-pressure storage space (common rail), which is followed by a further injection phase at a substantially higher injection pressure level, which is due to the pressure area conditions of the piston unit 17 of the pressure intensifier 3 and is present via the compression space line 20 in the nozzle chamber 36 in the nozzle body 6 of the fuel injector 4.

FIG. 2 shows the embodiment variant of a fuel injector according to FIG. 1 with a pressure intensifier in a second state. -OE-

In FIG. 2 it is shown that the control edge 31 on the housing side in the nozzle body 6 and the control edge 30 of the one-piece valve element 27 are out of overlap, as a result of which there is a connection 50 on the low pressure side between the control chamber 15 of the pressure booster 3 via the control line 19 which leads into the annular space 33, which surrounds the one-piece valve element 27. In this way, the control chamber 15 is relieved of pressure via the second low-pressure return 26.2, so that the piston unit 17 compresses the fuel volume contained in the compression chamber 18 of the pressure booster 3 due to the pressure prevailing in the working chamber 14 of the pressure booster 3 and via the compression chamber line 20, the nozzle inlet 9 in the nozzle space 36 of the nozzle body 6 calls. The injection valve member 34 of the fuel injector 4 is now in its open position 51, i.e. its open position, so that fuel is injected at very high pressure into the combustion chamber 41 of the self-igniting internal combustion engine via the nozzle chamber 36, the annular gap 38 and the released injection openings 39 in accordance with the pressure-increased pressure level.

To end the injection, the control valve 25, which is preferably designed as a 2/2-way valve, is closed, so that a pressure build-up occurs in the control chamber 21 of the injection valve member 34. Due to the action on the end face 29 of the one-piece valve element 27, the injection valve member 34 which cooperates with it moves in the closing direction. When the control edge 31 on the nozzle body 6 is reached, the control edges 30 and 31 overlap with one another, so that the slide seal formed by this is closed. As a result, the connection of the control chamber 15 via the control line 19 and the annular space 33 into the low-pressure-side return 26 is closed and the pressure intensifier 3 is thus deactivated. The injection valve member 34 moves further into its seat 40 on the combustion chamber side and thereby closes the injection openings 39 opening into the combustion chamber 41 of the self-igniting internal combustion engine at a later time. Since the pressure intensifier 3 is already deactivated, pressure peaks occur when the injection valve member closes 34 occur, compensated.

Through the stroke hi (reference numeral 32) and the closing speed of the injection valve member 34 and the valve element 27, the switch-off time of the pressure booster 3, ie the time at which the control edges 30 and 31 overlap, can be optimally coordinated with the end of the respective injection phase. In the case of small injection quantities, for example as part of a pre-injection, the injection valve member 34, which is preferably designed as a nozzle needle, cannot be opened completely along the entire stroke path hi (reference numeral 32), so that the pressure intensifier 3 remains deactivated. This means that any number of pre-injections can be carried out without activated pressure Realize translator 3. The pressure level in the context of the pre-injection for conditioning the combustion mixture contained in the combustion chamber 41 lies within the scope of these pre-injections at the pressure level which the high-pressure source 1, for example a high-pressure storage space (common rail), makes available and not on the level provided by the pressure booster 3 achievable increased pressure level. The number and the duration of the respective pre-injection phases and the duration of the main injection at an increased pressure level can be set by the control time of the control valve 25.

3 shows a further embodiment of a pressure intensifier actuated via an injection valve member with two valve elements inserted into one another.

The fuel injector 4 shown in FIG. 3 for supplying fuel to a self-igniting internal combustion engine also comprises a pressure booster 3 integrated in the injector body 5. A high-pressure source 1, 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. A filling valve 10 is accommodated in the first parallel branch 11 and a throttle point 13 in the further parallel branch 12. A check valve 8 is accommodated in the high-pressure line 7.

The pressure intensifier 3 according to the further embodiment variant in FIG. 3 comprises, analogously to the pressure intensifier 3 shown in FIG. 1, a piston unit 17 which separates the working space 14 from the control space 15. The underside of the piston unit 17 acts on the compression space 18 in the injector body 5 of the pressure booster 3, from which the compression space line 20 branches off to the nozzle space inlet 9 and merges with the high pressure line 7 from the high pressure source 1.

In contrast to the embodiment variant of the solution proposed according to the invention shown in FIGS. 1 and 2, the injection valve member 34 is acted upon by a multi-part valve element 28 as shown in FIG. 3. The multi-part valve element 28 comprises a first valve element 28.1 and a further, second valve element 28.2 surrounding it. The first valve element 28.1 and the further valve element 28.2 can be made piston-shaped. An annular surface 60 on the second valve element 28.2 partially delimits the control chamber 21. An opening 61 is formed in the second valve element 28.2, through 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 variant, 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 set a stroke hi (reference numeral 32). The control edge 30, which cooperates with a seat of a valve chamber 63, is located on the second valve element 28.2. The control line 19 from the control chamber 15 of the pressure booster 3 opens into the valve chamber 63 above the seat. A first return line 64 branches off from the valve chamber 63 to the low-pressure side of the fuel supply system. A piston extension 66 is formed on the first valve element 28.1, which has a smaller diameter than the piston part of the first valve element 28.1. The piston extension 66 passes through a further cavity, located below the valve chamber 63 in the nozzle body 6, 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 designed as a nozzle needle.

When the pressure in the control chamber 21 is relieved by the control valve 25, which is preferably designed as a 2/2-way valve, and the nozzle chamber 36 of the injection valve member 34 is simultaneously acted upon, a hydraulic force acting on the pressure shoulder 35 of the injection valve member 34 is generated via the nozzle chamber inlet 9 in the nozzle chamber 36 on. The injection valve member 34 opens, so that, for example, a pre-injection can be achieved via the injection opening 39 into a combustion chamber (not shown here) of an internal combustion engine. However, the pilot injection only takes place at the pressure level that is present in the high-pressure source 1, since the pressure intensifier 3 has not yet been activated at this time. When the pressure in the control chamber 21 is further relieved, the end face 62 of the internally arranged first valve element 28.1 approaches the collar-shaped stop of the second, externally located valve element 28.2 and takes the outer, second valve element 28.2 with it in the opening direction. As a result, the control edge 30 on the outer circumference of the second valve element 28.2 releases the connection of the control chamber 15 via the control line 19 and the valve chamber 63 into the first return line 64, so that pressure relief of the control chamber 15 of the pressure booster 3 takes place. The piston unit 17 of the pressure booster 3 accordingly moves into the compression space 18, so that fuel under increased pressure is conducted into the nozzle space 36 in the nozzle body 6 via the compression space line 20, the nozzle space inlet 9 at the mouth parts 37. Subsequent injection into the combustion chamber of the self-igniting internal combustion engine can now take place at an increased pressure level corresponding to the pressure amplification of the pressure booster 3. The further embodiment variant of a fuel injector according to the invention shown in FIG. 3 comprises, in addition to the first return line 64, which branches off from the valve chamber 63, a second return line 65 into the low-pressure region of the fuel supply system, which branches off from the cavity above the injection valve element 34, which contains the closing spring element 67. The stop point from which the end face 62 of the inner Most valve element 28.1 strikes the external, second valve element 28.2 and takes it along with further pressure relief of the control chamber 21 in the opening direction is identified in the illustration according to FIG. 3 with reference numeral 68.

The other components of the fuel injector 4, according to the embodiment variant shown in FIG. 3, which have not been described individually above, essentially correspond to the components which have already been described in the embodiment variant of the fuel injector according to the invention according to FIGS. 1 and 2.

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

From the high-pressure source 1, the high-pressure inlet 2 extends both via a high-pressure line branch 7, which contains a check valve 8, and also via a first parallel branch 11 and a further parallel branch 12 to the control chamber 15 of the pressure booster 3. In addition, the high-pressure source 1 acts, for example, on High-pressure storage space (common rail), the working space 14 of the pressure intensifier 3 directly. The working space 14 and the control space 15 of the pressure intensifier 3 are separated from one another by a piston unit 17, the end face of the piston unit 17 facing the working space 14 having a larger diameter than that end face of the piston unit 17 which delimits the compression space 18 of the pressure intensifier 3 , A compression chamber line 20 extends from the compression chamber 18 within the injector body 5 of the fuel injector 4 and unites with the high pressure line 7 receiving the check valve 8 and merges into the nozzle chamber inlet 9.

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

A multi-part valve element 28 is also used in the embodiment variant of the fuel injector 4 shown in FIG. The multi-part valve element 28, which acts on the injection valve member 34 in the nozzle body 6 of the fuel injector 4, comprises a first valve element 28.1, the end face 62 of which delimits the control chamber 21. The first valve element 28.1 comprises a piston extension 66, which rests with its lower end face on the end face of the injection valve member 34. The first valve element 28.1 is enclosed by a second, further valve element 28.2, where -ι - a passage gap 72 is set between the first valve element 28.1 and the second valve element 28.2. In contrast to the embodiment variant shown in FIG. 3, the second valve element 28.2 does not delimit the control chamber 21, but is arranged below the first valve element 28.1 and a spring element 70 acts on its annular surface 60. 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.

By means of the spring element 70 arranged in the valve chamber 63, the second, sleeve-shaped valve element 28.2 is pressed with its control edge 30 into its closed position, so that the valve seat between the control edge 30 and the housing edge 31 of the valve chamber 63 is closed in the rest position and the pressure intensifier 3 is deactivated , Since the seat is closed by the control edges 30 on the second valve element 28.2 and the control edge 31 on the valve chamber 63, pressure relief of the control chamber 15 via the line 19 into the valve chamber 63 is not possible, so that the piston unit 17 is between the working chamber 14 and the Control room 15 of the pressure booster 3 is in its starting position. To increase the closing force on the control edge 30, a closing hydraulic pressure force can be generated by a corresponding pressure stage within the valve chamber 63.

After actuation of the control valve 25, which is preferably designed as a 2/2-way valve, the control chamber 21 is depressurized so that the end face 62 of the first valve element 28.1 moves into the latter. If the control chamber 21 above the end face 62 of the first valve element 28.1 is depressurized so long that the end face of the injection valve member 34 strikes the lower ring surface of the second valve element 28.2, ie if the stroke hi (reference number 32) is exceeded, the pressure intensifier 3 is replaced by the Injection valve member 34 is activated because, due to the hydraulic force acting on the pressure shoulder 35 in the nozzle chamber 36, the sealing seat between the control edges 30 on the second valve element 28.2 and on 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 device 19 can take place in the first low-pressure side return 64. As a result, in the nozzle chamber 36, the fuel compressed in the compression chamber 18 of the pressure booster 3 is in contact with the nozzle chamber inlet 9 at the mouth 37 of the nozzle chamber inlet 9 into the nozzle chamber 36 via the compression chamber line 20. With the solution shown in FIG. 4, with appropriate pressure relief of the control chamber 21 of the injection valve member 34, pre-injection phases on the prevailing in the high-pressure source 1 can be carried out within certain limits, ie so that the drive-up path of the injection valve member 34 is below the stroke distance hi (reference numeral 32) Represent pressure level, with an activation from a further relief of pressure in the control chamber 21 via the injection valve member 34 of the pressure intensifier 3, and a main injection phase with rate shaping can be implemented at an elevated pressure level. According to the control cycle of the control valve 25, one or more pre-injection phases can be carried out, solely depending on the control times and the control program of the control valve 25, which can preferably be designed as a 2/2-way valve. With the embodiment variants proposed according to the invention according to FIGS. 1 and 2 or 3 and 4, fuel can be injected into the combustion chamber 41 of a self-igniting internal combustion engine below a needle stroke h ₁ (reference numeral 32) with a first pressure level which, for example, corresponds to the pressure level one High pressure source 1 corresponds. When a stroke distance hi (reference numeral 32) is exceeded, a pressure booster 3 is activated by the injection valve member 34, so that a subsequent injection at an increased pressure level follows. On the one hand, this allows a boat-shaped injection, since the first injection phase (pre-injection) takes place at a lower pressure level than the subsequent main injection. By activating the pressure booster 3 by the vertical stroke movement of the injection valve member 34, an increased pressure level occurs precisely when this is required in terms of process technology in accordance with the progress of combustion in the combustion chamber 41 of the self-igniting internal combustion engine. In the case of small injection quantities, the injection valve member 34 cannot be pre-injected by means of a controlled pressure relief of the control chamber 21 in terms of its relief duration until the stroke stroke hi (reference numeral 32) is reached, so that the pressure intensifier 3 remains deactivated. Accordingly, with the solution proposed according to the invention, any number of pre-injections are possible at a pressure level which is low in comparison to the activated pressure intensifier 3, the fuel injector 4 according to the solution proposed according to the invention being operable only with one control valve 25.

_

LIST OF REFERENCE NUMBERS

1 high pressure source (common rail)

2 high pressure inlet 3 pressure intensifier

4 fuel injector

5 injector bodies

6 nozzle bodies

7 High pressure line 8 Check valve

9 Branch nozzle inlet

10 filling valve

11 first parallel branch

12 further parallel branch 13 choke point

14 work space

15 control room

16 spring element

17 piston unit 18 compression chamber

19 Control line for control room

20 compression space line

21 control room

22 High pressure branch to the control room 23 Inlet throttle

24 outlet throttle

25 control valve (2/2-way valve)

26.1 first low-pressure 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

33 Annulus valve element _ Injection valve member Pressure shoulder Nozzle area Mouth point Nozzle area inlet Annular gap Injection opening Seat on the combustion chamber side Combustion chamber closed injection opening

connection on the low-pressure side of the injection valve member 34 (open position), opened injection openings

Annular surface of the second valve element, through opening, end face, first valve element, valve chamber, first return line, second return line, piston extension, closing spring, stop, first valve element on the second valve element

Spring element for second valve element Stop spring element overflow gap

Claims

- - Claims

1. Device for injecting fuel into a combustion chamber (41) of an internal combustion engine with an injector body (5, 6), in which an injection valve member (34) is accommodated, which is depressurized / pressure relieved

Control chamber (21) can be actuated, which is effected via a control valve (25) and with a pressure intensifier (3) which comprises a piston unit (17) which separates a working chamber (14) and a control chamber (15) and which has a compression chamber (18). acted upon, which is in connection (9, 20) with a nozzle space (36) surrounding the injection valve member (34), characterized in that the pressurization (2,

11, 12) / pressure relief (19, 26, 64) of the control chamber (15) of the pressure booster (3) takes place depending on the stroke movement of the injection valve member (34).

2. Device for injecting 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 room (15) of the pressure intensifier (3) opens.

3. Device for injecting fuel according to claim 2, characterized in that the valve element arranged within the hydraulic space (33, 63)

(27, 28) acts on the end face of the injection valve member (34) facing away from the combustion chamber-side injection openings (39).

4. Device for injecting fuel according to claim 2, characterized in that the valve element (27, 28) with a hydraulically actuated surface (29,

60, 62) protrudes into a control chamber (21) which pressurizes the injection valve member (34).

5. Device for injecting fuel according to claim 2, characterized in that the valve element (27) is formed in one piece and has a control edge (30) which forms a slide seal with a control edge (31) on the hydraulic space (33).

6. Device for injecting 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 injecting fuel according to claims 5 and 6, characterized in that upon a pressure movement of the control chamber (21) triggered stroke movement of the injection valve member (34) that is smaller than a stroke hi (32) - the overlap of the control edges ( 30, 31) - the slide seal (30, 31) remains closed and fuel is injected into a combustion chamber (41) at a first pressure level.

8. Device for injecting fuel according to claims 5 and 6, characterized in that upon a further pressure relief of the control chamber (21) triggered stroke movement of the injection valve member (34), which exceeds the stroke hi (32), the control chamber (15) of the pressure booster (3) can be connected to the second low-pressure side return (26.2) via the control line (19) and the open control edges (30, 31) and fuel is injected into a combustion chamber (41) at a second, higher pressure level.

9. Device for injecting fuel according to claim 2, characterized in that the valve element (28) is constructed in several parts and comprises a first valve part (28.1) and a second valve part (28.2), at least one of which through the in the control chamber (21) pressure prevailing in the injection valve member (34).

10. The device for injecting fuel according to claim 9, characterized in that the first valve part (28.1) is guided in the second valve part (28.2) and between an end face (29) of the first valve part (28.1) and a stroke stop (68) of the second Valve part (28.2) a stroke hi (32) is set.

11. The device for injecting 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. The device for injecting fuel according to claims 10 and 11, characterized in that when the pressure in the control chamber (21) is relieved, the first valve part (28.1) moves by the stroke hi (32) against the stop (68) and the injection valve member (34 ) carries out an injection of fuel into the combustion chamber (41) at a first pressure level.

13. Device for injecting fuel according to claims 10 and 11, characterized in that with further pressure relief of the control chamber (21) the first _

After measuring the stroke hi (32), the valve part (28.1) opens the second valve part (281.2) on the sealing seat in the hydraulic chamber (63), the control chamber (15) via the control line (19), and the hydraulic chamber (63) relieves pressure and fuel is injected at a second, higher pressure level.

14. Device for injecting fuel according to claim 9, characterized in that one of the valve parts (28.1, 28.2) of the multi-part valve element (28) acted upon by a spring element (70) is placed in a sealing seat in the hydraulic space (63).

15. Device for injecting 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) forming an annular gap (72) and the piston extension (66) of the first Valve part (28.1) acts on the injection valve member (34) on the end face.

16. A device for injecting 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 path _\ (32) can be predetermined, by which the injection valve member (34) when a pressure relief Control room (21) for injecting fuel is movable at a first pressure level.

17. Device for injecting fuel according to claims 9 and 16, characterized in that with a further pressure relief of the control chamber (21) and a stroke movement hi (32) exceeding the opening movement of the injection valve member (34), this the second valve part (28.2) moved from its seat in the hydraulic chamber (63), and the control chamber (15) of the pressure booster (3) via a control line (19) relieved on the low-pressure side, so that fuel is injected into the combustion chamber (41) at a second, higher pressure level ,