EP1483499A1

EP1483499A1 - Installation for the pressure-modulated formation of the injection behavior

Info

Publication number: EP1483499A1
Application number: EP03701469A
Authority: EP
Inventors: Jaroslaw Hlousek
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-03-04
Filing date: 2003-01-07
Publication date: 2004-12-08
Anticipated expiration: 2023-01-07
Also published as: CN100379980C; JP2005519222A; EP1483499B1; WO2003074865A1; US20050115539A1; US7096857B2; CN1639458A; DE10209527A1; DE50302960D1

Abstract

The invention relates to an installation for injecting fuel into the combustion chamber of a self-igniting combustion engine, comprising a control unit (6, 80) that impinges a spring-controlled injection device (56). Said spring-controlled injection device is provided with a jet needle (58) via which one or several injection ports (57) are opened or closed. The control unit (6, 80) comprises a first valve (10) and a second valve (11), each of which is provided with a pressure chamber (28, 36). Said pressure chambers (28, 36) are connected to each other via a pressure pipe (32, 81). The first valve (10) and second valve (11) are serially connected. The first valve (10) controls pressurization of the pressure chamber (36) of the second valve (11). The amount (91, 92) of injection pressure during the injection periods (86, 90) is controlled by the second valve (11).

Description

Device for pressure-modulated injection injection molding

10

Technical field

The term “injection course” denotes the course of the amount of K-fuel injected into the combustion chamber as a function of the crankshaft or camshaft angle. The 15th essential variables are the injection duration and the injection amount. These represent the course of the injection in degrees / crankshaft angles , Camshaft angle or ms, while the injectors are open and fuel enters the interior of the combustion chamber.

20 State of the art

DE 198 37 332 AI relates to a control unit for controlling the pressure build-up in a pump unit. The control unit has a control valve and a valve actuation inlet connected to it. The control valve is designed as

25 NEN opening I-shaped valve, which has a valve body axially displaceably mounted in a housing of the control unit, which sits on the inside of a valve seat of the control valve when the control valve is closed. It is a throttling arrangement provided by _which, h is the flow through the control valve in order emen small stroke. open control valve is throttled. When the control valve is open by this stroke, the is

30 valve seat still open, but another valve seat closed, so that the pumped medium through the throttle bores through the control valve Hießen π ss. Due to the throttled flow through the control valve, a lower pressure is built up in a high-pressure area of the system. When the control valve is completely closed, however, both the first valve seat and the further valve seat are

35 locks, whereby the bypass connection is interrupted. This leads to the build-up of a high pressure from the pump unit to the low pressure area of the system in the high pressure area of the system. DE 42 38 727 AI relates to a solenoid valve. The solenoid valve is used to control the passage of a connection between a high-pressure chamber, at least temporarily brought to high fluid pressure, in particular a pump working chamber of a fuel injection pump and a low-pressure chamber. A valve body inserted into a valve housing and a bore arranged therein are provided, in which a valve closing member in the form of a piston can be displaced by an electromagnet against the force of a return spring. The piston tapers, starting from a circular cylindrical outer surface via a conical surface to a reduced diameter, the conical surface interacting with a conical high pressure space surrounding the circular cylindrical outer surface of the piston with a connecting valve seat surrounding the reduced diameter of the piston on the valve body. Its cone angle is smaller than the cone angle of the conical surface of the piston, so that the piston interacts with the valve seat via a sealing edge which is created at the transition between its cylindrical outer surface and the conical surface. The sealing edge is connected in the overflow direction from the high-pressure chamber to the low-pressure chamber, a throttle point which becomes effective at the start of the opening stroke. The throttle point is formed by a throttle section in the overlap area between the angular surface of the piston and the valve seat surface, the angle of the conical surface of the piston being slightly, preferably 0.5 to 1 °, larger than the angle of the valve seat surface, so that the passage cross section between the The tapered surface of the piston and the valve seat surface steadily decreases over the entire circumference in the overflow direction to the eder pressure chamber at the beginning of the opening stroke. Due to the high flow velocities of the fuel between the injection phases - be it pre-, main or post-injection phases, cavitation damage can be prevented with this solution.

Presentation of the invention

In addition to the control parameters injection start, injection quantity, injection pressure and the number of injections, which are mentioned in this context as the usual control parameters of a common rail injection system, the solution proposed according to the invention permits the first phase of the injection process (the so-called "bootplias") with regard to to control the length and the pressure level. Depending on the speed and the load of the self-igniting internal combustion engine, the NO _x emissions can be influenced very favorably by influencing the boot phase. The boot phase upstream of the main injection serves to condition the mixture to be reacted during the main injection phase with regard to an optimal, ie as complete as possible combustion with an optimal exhaust gas composition. The possibility of influencing the duration of the boot phase independently of the control parameters injection start, injection quantity and injection pressure etc. allows the injection process to be adapted to the fuel used during the boot phase. Heavy oil is frequently used as a fuel in stationary diesel engines or diesel engines for propelling ships, the atomization behavior of which, for example, is significantly less favorable than that of diesel oil which is injected into the combustion chambers of passenger car diesel engines. The preparation of the mixture by means of a controlled injection of fuel enables the compressed mixture to be prepared better, regardless of the fuel quality, so that favorable conditions with regard to emissions are established in the combustion chamber during the combustion phase. In a particularly advantageous manner, the more favorable NO _x emissions can be achieved with the same fuel consumption of the combustion lcraft machines. This concept also enables the combination of multiple injections (pre-injection phases) to achieve mixture preheating and a post-injection phase to lower smoke values with the shaping of the injection process.

The proposed solution also takes into account the use of heavy oil as fuel for diesel engines in that the actuators, for example solenoids of electromagnets or piezo actuators with hydraulic translators, are separated from the fuel by a membrane. The membrane shield, for example, from the anchor ^plates' and magnets from the fuel, which may be to improve its flow properties at temperatures of up to 140 ° C and preheated it.

drawing

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

It shows:

1 shows a control unit with a combination of a 3/2 way valve and a 2/2 way valve connected in series,

FIG. 2 shows the control unit according to FIG. 1, fastened to a high-pressure collector (common rail),

FIG. 3 the control unit according to FIG. 1, directly assigned to an injector (DHK), Figure 4 is a split version of the control unit according to

1, wherein part of the control unit is assigned to the high-pressure alarm chamber and the other part of the control unit to the injector (DHK) and

Figures 5.1,

5.2 ^' the course of the nozzle needle stroke and injection pressure, each plotted over the time axis,

Figure 5.3 different activation times of a 3/2-way valve,

5.4 the activation time of a 2/2

Way valve,

Figure 6 shows the curves of pressure, needle stroke and control times of a 3/2 and a 2/2-way valve and

FIG. 7 shows the courses of pressure, needle stroke and activation times of a 3/2 and a 2/2 way valve with multiple injection, combined with the "boot rate shaping".

Ausfυhrungsvarianten

Figure 1 shows a control unit with a series combination of a 3/2-way valve and a 2/2-way valve.

The control unit 6, which can be seen in FIG. 1, is supplied with fuel under high pressure by means of a high-pressure inlet 1 via a high-pressure accumulation chamber (common rail), not shown here, or another high-pressure source. The control unit 6 comprises an unpressurized outlet 3 and a drain on the high-pressure side 2. The control unit 6 is of modular construction and comprises an upper part 7, in which a first actuating device 4 and a second actuating device 5 are accommodated next to one another. Below the upper part 7 of the control unit 7 there is a central part 8, to which a lower part 9 is connected.

The control unit 6 comprises a first valve 10 and a second valve 11. The first valve 10 is designed as a 3/2-way valve, the pressure chamber 28 of which is pressurized with fuel under high pressure via the high-pressure inlet 1. The opposite Via the second valve 11 is designed as a 2/2-way valve. The first valve 10 is controlled by the first actuating device 4, which is designed as an electromagnet in the illustration according to FIG. 1. The magnet coil 13 of the electromagnet is accommodated in the upper part 7 of the control unit 6. An actuating arrangement 21, 22 for relieving pressure in a control chamber 24 of the first valve 10 acts on a closing element 20, which in turn releases or closes an outlet throttle 23 for relieving pressure in the control chamber 24 of the first valve 10. In the embodiment of the control unit 6 shown in FIG. 1, the first actuating device 4 is designed as an electromagnet. Alternatively, the configuration of the first actuating device 4 as a piezo actuator is possible, which can be followed by a hydraulic translator to increase the travel. The actuation arrangement 21, 22 - configured as an anchor plate 21 and pin 22 connected to it in the illustration according to FIG. 1 - is acted upon by a return spring 12, which the anchor plate 21 of the actuation arrangement 21, 22 at a distance from the lower end face of the magnet coil 13 first actuator 4 holds. The pin 22 of the actuating arrangement 21, 22 comprises a contact surface 19 which partially encloses the spherical locking element 20 and presses it into the seat within the middle part 8 which closes the outlet of the control chamber 24. The reference line 18 designates the line of symmetry of the first actuating device 4 and the first valve 10.

Below the first actuating device 4, a first cavity 15 is formed in the upper part 7 of the control unit 6, which serves to receive the anchor plate 21 of the actuating arrangement 21, 22. In the area above the parting line of the upper part 7 and the middle part 8 of the control unit 6, the first cavity 15 is sealed against the entry of fuel by means of a flexible membrane element 17. When using the control unit 6 on large diesel engines, such as those e.g. heavy fuel oil is used as a stationary diesel engine or to propel ships, which is preheated to temperatures of up to 140 ° C and above to improve its flow properties. In order to protect the first actuating device 4 - and analogously the second actuating device 5, which actuates the second valve 11 - from damage and viscous fuel entering, the first cavity 15 and analogously the second cavity 16 of the second actuating device 5 are in the region by means of flexible membrane elements 17 the parting line to the central part 8 of the control unit 6 is protected against the entry of hot fuel.

The one controlled when the pressure in the control chamber 24 of the first valve 10, which is preferably designed as a 3/2-way valve, penetrates into the annular space surrounding the pin 22 of the actuating arrangement 21, 22 and flows from there into an overflow bore 25 running horizontally in the middle part 8. From the horizontally extending overflow bore 25 in the central part 8 of the control unit 6, both an overflow bore 26 extending in the vertical direction in the central part 8 and an outflow line 34 branch off. Via the outflow line 34, the controlled fuel volume flowing out of the control chamber 24 can be introduced into the unpressurized outlet 3, from which the controlled fuel volume flows back into the fuel tank.

The first valve 10 comprises a valve body 27, the upper end of which delimits the control chamber 24. The control chamber 24 is also delimited by the lower part 9 of the control unit 6 and a partial area of the lower surface of the central part 8 of the control unit 6, in which the outlet throttle 23 is accommodated, which can be closed or released by the spherically configured closing element 20. The valve body 27 of the first valve 10 also includes, in the area which is enclosed by the annularly configured pressure chamber 28, an inlet throttle point 30 which is connected to a longitudinal bore opening on the upper end face of the valve body 27. Via the high pressure inlet 1, the inlet throttle point 30 and the aforementioned longitudinal bore shown in broken lines in FIG. 1, it is ensured that the control chamber 24 of the first valve 10 is always acted upon by a control volume. In addition, the valve body 27 of the first valve 10 comprises a conical seat 29 which interacts with a corresponding seat surface of the lower part 9. In FIG. 1, the conical seat 29 of the valve body 27 is inserted into a corresponding seat surface of the lower part 9 of the control unit 6 and closes both the unpressurized outlet 3 as well as the transverse bore 32 branching below the annular pressure chamber 28 to the pressure chamber 36 of the second valve 11, which is preferably designed as a 2/2-way valve. The valve body 27 of the first valve 10 further comprises an extension 31, which is arranged below the conical seat 29 and corresponding to the stroke of the valve body 27 in the lower part 9 of FIG. Control unit 6 closes or releases the unpressurized drain 3. When the control chamber 24 is relieved of pressure by energizing the first actuating unit 4, the control chamber 24 is relieved of pressure, and consequently the valve body 27 moves upwards in the vertical direction until its upper end face rests on the contact surface 18 of the middle part 8. Corresponding to this vertical stroke movement, the conical seat 29 moves out of its seat in the lower part 9 of the control unit 6 and the extension 31 partially extends into the bore adjoining the pressure chamber 28 to such an extent that the high pressure 1 and the pressure chamber via the annular pressure chamber 28 36 of the second valve 11 acting cross bore 32 is supplied with high pressure.

The second actuating unit 5, which is likewise accommodated in the upper part 7 of the control unit 6 and which, in the embodiment variant according to FIG. is executed, actuates a valve body 35 of the second valve 11. Below the magnet coil 13 of the second actuating device 5 there is a second cavity 16 formed in the upper part 7, which is secured against the inflow of preheated fuel via the membrane element 17. When fuel flows in and then cools, operation would no longer be possible with the required precision due to the short stroke distances, the required travel distances required by the electromagnets to actuate the first valve 10 and the second valve 11 if preheated heavy oil is used as fuel, which is quite common with stationary large diesel engines and with diesel engines that are already used to propel ships.

The pressure chamber 36 of the second valve 11, which is acted upon via the transverse bore 32, opens into a high-pressure outlet 2, which is connected to an injection device, such as a nozzle holder combination or an injector, with a nozzle chamber (not shown in FIG. 1). At the end of the valve body 35 of the second valve 11 facing the high-pressure outlet 2, a conical seat 39 is formed which interacts with a corresponding seat surface in the lower part 9 of the control unit 6. In the lower region of the valve body 35, a throttle point 37 is formed in connection with the pressure chamber 36, which is connected to a longitudinal bore 38 within the valve body 35.

The first actuating device 4 and the second actuating device 5 are controlled by means of a control part 40, which is connected via control lines 14 to the solenoids 13 of the first actuating device 4 and the second actuating device 13, respectively.

The operating mode of the embodiment variant shown in FIG. 1 is as follows:

The valve body 27 of the hydraulic 3/2-way valve 10 is controlled by means of the first actuating device 4 designed as an electromagnet. The opening and closing of the valve body 27 is controlled by the pressure relief of the control chamber 24 via the first actuating device 4. The pressure drop or the pressure rise is dependent on the diameters of the inlet throttle parts 30 in the lower part of the valve body 27 or the design of the outlet throttle 23 above the control chamber 24. If the solenoid 13 of the first actuating device 4 is deenergized, the valve body 27 closes by retracting its conical seat 29 the high-pressure inlet 1 via the transverse bore 22 to the pressure chamber 36 of the second valve 11 into the corresponding seat surface within the lower part 9 of the control unit 6. In this state, the high-pressure outlet 2 of the second valve 11 is connected to the unpressurized outlet 3 below the first valve 10. prevented. The one controlled from the control chamber 24 when the pressure is relieved also flows through this. Control volume amount via the horizontally extending overflow bore 25 or the outflow line 34 from the low pressure side of the control unit 6. In this state, a nozzle needle of an injection device remains closed, compare FIGS. 2 and 3. When the first actuating device 4 is activated via the control part 40, ie the solenoid coil 13 is energized, the valve body 27 is moved as far as the stop 18. By moving the extension 31 into the bore below the pressure chamber 28 in accordance with the stroke path, the pressure-free outlet 13 is closed, the high-pressure inlet 1 being connected via the pressure chamber 28 to the pressure chamber 36 of the second control valve 11. Now the injection process begins. The injection pressure is controlled via the second actuating device 5, which actuates the valve body 35 of the second valve 11, the solenoid coil of which is activated by the control part 40 via a control line 14. In the closed state of the second valve 11, ie when the solenoid 13 of the second actuating device 5 is not activated, the inlet to the injection nozzle is throttled via the throttle point 37 formed in the valve body 35. With the control sequence described, ie energizing the solenoid 13 of the first actuating device 4 and then relieving the pressure in the control chamber 24, the high-pressure outlet 1 is connected via the pressure chamber 28 and ^" via the transverse bore 32 to the pressure chamber 36 of the second valve 11, however, in this phase of the injection there is only a throttled action on the high pressure inlet 2 to the injection nozzle (see illustration in Figure 2.) Depending on the actuation of the second actuating device 5 via the control part 40, an unthrottled action on the nozzle space 59 of a nozzle holder combination 56 can take place (see illustration according to FIG. 2) depending on the control, ie the stroke of the valve body 35 of the second valve 11 takes place within the lower part 9 of the control unit 6. When the second valve 11 is opened, the injection nozzle on the nozzle holder combination (compare FIGS. 2 and 3) is also throttled d em above the high pressure inlet 1, the pressure chamber 28 of the first valve 10, the transverse bore 32, which connects the pressure chamber 36 of the second valve 11. To end the injection, the high-pressure outlet 2 leading to the nozzle holder combination or to the injector 56 (see illustration according to FIG. 2) is actuated by actuating the valve body 27 of the first valve 10, which is preferably designed as a 3/2-way valve, ie moving the conical seat 29 into the Lower part 9 located seat surface, whereby the high-pressure outlet 2 with the drainless outlet 3 for Druckentlastimg the Einrichtimg for injecting fuel 56 is relieved of pressure. The second valve 11 is then closed via the return spring 12, which is enclosed in the upper part 7 of the control unit 6 and is enclosed by the magnetic coil 13. FIG. 2 shows the control unit according to FIG. 1 attached to a high-pressure collecting room (Cornmon Rail).

In the illustration according to FIG. 2, the control unit 6 is only represented by the upper part 7, the middle part 8 and the lower part 9. The Hochdmcksa melraum 50 is configured essentially tubular. The high-pressure collecting space 50 (cornmon rail) and the control unit 6 are connected to one another along a butt joint 51. Above the control unit 6, the control lines 14 of the first actuating device 4 and the second actuating device 5 are shown in the upper part 7 of the control unit 6, via which the solenoid coils for actuating the first valve 10 and the second valve 11 are actuated by means of the actuating part 40.

The high-pressure plenum 50 (Cornmon Rail) is connected to the tank 55 via a fuel feed 53 and comprises a high-pressure fuel pump 52, which pumps the fuel from the tank 55 to an arbitrary pressure level, e.g. brings between 600 and 1800 bar.

The unpressurized outlet 3 on the control unit 6 is also connected to the tank 55 via a return line 54, so that the fuel quantity discharged from the control chamber 24 of the first valve 10 can flow back into the fuel reservoir. At the high-pressure outlet 2 of the control unit 6, caused by pressurizing the pressure chamber 36 of the second valve 11, there is high pressure, which is present at the control chamber 59 of the nozzle holder combination 56 in accordance with the further course of the high-pressure outlet 2. Reference number 56 denotes a nozzle holder combination which comprises a nozzle needle 58 which is acted upon within the nozzle holder combination 56 by a compression spring. Depending on the pressurization of the nozzle chamber 59, injection openings 57 arranged at the end of the nozzle holder combination 56 on the combustion chamber side are supplied with fuel or closed. The spring chamber of the nozzle holder combination 56 is connected to the return 54 into the fuel tank 55 via a further pressure-free outlet 60, so that excess fuel volume can also flow back into the tank 55. In the illustration according to FIG. 2, the control unit 6 is assigned directly to the high-pressure collecting space 50 (Cornmon Rail), as a result of which a short overall length of the high-pressure inlet 1 from the high-pressure collecting space 50 (Cornmon Rail) to the control unit 6 can be achieved.

The representation according to FIG. 3 shows the control unit according to FIG. 1 which is arranged directly above an injector (DHK). The integrated version, designated by reference numeral 70, of a control unit 6 in the upper region of a nozzle holder combination 56 or a differently configured device for injecting fuel into the combustion chambers of a self-igniting internal combustion engine is controlled analogously to the illustration according to FIG. 2 via control lines 14 by means of a control part 40. Analogously to the illustration according to FIG. 2, the high-pressure collecting chamber 50 is acted upon by a high-pressure fuel volume 52 via a high-pressure fuel pump 52, which in turn conveys the high-pressure fuel pump 52 from the tank 55 via a flow 53. A pressure-free outlet 60 of the egg device for injecting fuel 56 opens out in the tank 55, which is designed here as a nozzle holder combination. From the unpressurized outlet 3 of the control unit 6, which in the embodiment variant according to FIG. 3 opens into the spring chamber of the nozzle holder combination 56, the leakage oil volume flows back into the tank 55 via the unpressurized outlet 60 and the return 54. The integrated version 70 of the control unit 6 above a device for injecting fuel 56 advantageously results in a particularly short high-pressure outlet 2, via which the high pressure can be applied to the nozzle chamber 59, which encloses the nozzle needle 58. The control unit 6 in its integrated version 70 also has an upper part 7, the central part 8 and the lower part 9 receiving the first valve 10 and the second valve 11, not shown in FIG. 3.

FIG. 4 shows a variant embodiment of the control unit which is divided, with part of the control unit on the high-pressure collecting space (Cornmon Rail) and the other part of the control unit being directly assigned to the injector.

The divided embodiment variant of the control unit 6 is designated by reference number 80. In this embodiment variant, the control unit 80 comprises two components, the first valve 10 and the first actuating device 4 actuating it being accommodated in the upper part 7.1, in the middle part 8.1 and in the lower part 9.1. The high-pressure collecting space 50 (Cornmon Rail) is directly connected to the lower part 9.1 of the control unit 80. From the lower part 9.1 of the divided control unit 6, i.e. From the pressure chamber 28 of the first valve 10, a connecting line 81 branches off, via which the pressure chamber 36 of the second valve 11, which is contained in the second part of the divided control unit 80, is pressurized with fuel under high pressure.

The second valve 11, preferably designed as a 2/2-way valve, is accommodated in the upper part 7.2, middle part 8.2 and lower part 9.2 of the split version of the control unit 80. The high-pressure outlet 2 branches off from the pressure chamber 36 of the second valve 11 and pressurizes the nozzle chamber 59 of the nozzle holder combination 56 with high pressure. According to the stroke movement of the nozzle needle 58 against the spring preload tion, the injection openings 57 at the combustion chamber end of the nozzle holder combination 56 are either acted upon by fuel or closed. Reference numeral 60 denotes an unpressurized outflow via which excess fuel volume flows back into a tank, not shown here.

Figure 5.1 and 5.2 show the courses of the nozzle needle stroke and the injection pressure, each plotted over the time axis.

The representation according to FIG. 5.1 shows the needle stroke path 23 plotted over the time axis 84. As can be seen from the illustration according to FIG. 5.1, with the solution proposed according to the invention, both short boot phases 87 of a main injection 90 and longer boot phases 88 can be connected up. The curves in FIG. 5.2 show the pressure level 92, which during the main injection 90 upstream boot phase 86, be it as a short boot phase 87 or be measured as a long boot phase 88, is reached. The pressure level 92 during the boot phase 86 is with the throttle 37 shown in Figure 1 in relation to the system pressure 91, i.e. adjustable to the maximum pressure and depending on the stroke and throttle size.

In comparison to the pressure level 89 prevailing during the main injection phase 90, at which the maximum level is present, the injection pressure during the boot phases 86 runs at a lower pressure level 92. During the boot phase, a small amount of fuel is injected into the combustion chamber, which essentially improves the swirl serves the compressing air within the combustion chamber and the aim of conditioning the air mixture to bring about a subsequent optimal combustion during the main injection phase 90. The course of the main injection phase 90 is characterized by a pressure maximum 89, a falling pressure flank 93 and a steeply rising pressure flank 94 at the beginning of the main injection phase 90. The maximum pressure level 91 which arises during the main injection phase 90 corresponds essentially to the pressure maximum 89, which is within the high Dracksammelraumes 50 (Cornmon Rail) sets.

Figure 5.3 shows different activation times of a 3/2-way valve, which define the injection duration and the injection quantity.

Reference numeral 95 marks a first start of injection of the first valve 10, which is designed as a 3/2 way valve, while reference numeral 103 identifies the end of a first injection duration 98. The first start of injection 95 is triggered by the control line point of the electromagnet 13 which controls the first valve 10. Depending on the control A second injection start 96 or a third injection start 97 can also be represented, whereby - while maintaining the injection end 103 - injection durations 98, 99, 100 of different lengths can be realized, by means of which the fuel quantity supplied to the combustion chamber of an internal combustion engine is determined.

The pressure level which is reached by the electromagnet 13 when the first valve 10 is activated is identified by reference symbol 101.

Figure 5.4 shows the activation time of the second valve 11, which is designed as a 2/2-way valve. This is opened by the electromagnet 13 at time 102 and closed at time 103. During the period identified by reference number 100, both valves are open, so that during this phase the pressure maximum 89 is established according to FIG. 5.3, at which the two pressure levels 101 and 105 on the 3/2-way valve and on the 2/2 -Way valve, ie overlay on the first valve 10 and the second valve 11. According to the activation time 90, the boot phase 86 upstream of the main injection phase 50 can be shaped as a short boot phase 87 or as a long boot phase 88, in which the first pressure level 101 prevailing when the 3/2-way valve designed as the first valve 10 is opened.

If, according to FIG. 5.4, the first valve 10 and the second valve 11 are opened and closed at the same time, according to the curve 104, a main injection takes place without an upstream boot phase 86 as in FIG. 5.2.

FIG. 6 shows the courses of pressure and needle stroke and the activation times of a 3/2-way valve and a 2/2-way valve with multiple injection with boot rate shaping.

FIG. 6 shows the parameters mentioned above in relation to the top dead center (TDC) 106 of a piston in the cylinder of an internal combustion engine. It can be seen from the upper curve of FIG. 7 that a main injection phase 90 with an upstream boot phase 86 is assigned a pre-injection 108 and a post-injection 109. During the pre-injection 108, the nozzle needle, which, for example, represents the injection valve element of an injector, is partially open, see reference number 110; During the period marked 111, the nozzle needle is completely open in accordance with the needle stroke path 83 in FIG. 7. With the 2/2-way valve 11, the length of the boot phase 86 can be controlled synchronously with the first valve 10 in the event of changes in injection. During the pre-injection 108, the first valve 10, designed as a 3/2-way valve, is briefly opened for the duration 112 and then closed again, as a result of which a small amount of fuel is injected into the combustion chamber of the internal combustion engine for preconditioning. At the point in time marked with reference number 95, the 3/2-way valve opens for the duration of the main injection phase 113 and closes again at point in time 103. During the post-injection phase 109, the 3/2-way valve, ie the first valve 10, is opened for the duration 114. Moved to the opening time 95 or the closing time 103 of the first valve 10, the 2/2-way valve, ie the second valve 11, is opened at time 116 and only closed at time 117, which according to the shifted opening duration curve shown in FIG 2/2-way valves 115 can coincide with the end of the post-injection phase 114.

By shifting the opening and closing times 116 and 117 of the 2/2-way valve, ie the second valve 11, boot rate shaping can be achieved, ie the injection pressure curve and thus the injection quantity can be shaped according to certain conditions and criteria , Furthermore, from the curve profiles shown in FIG. 7, it follows that a main injection phase 90, be it with or without boot phase 86, both a pre-injection 108 and a post-injection 109 can be connected upstream or downstream.

LIST OF REFERENCE NUMBERS

High-pressure inlet High-pressure outlet Unpressurized outlet first actuating device second actuating device control unit upper part middle part lower part first valve (3/2) second valve (2/2) return spring solenoid control line first cavity second cavity membrane element stop surface contact surface closing element plate pin drain valve control chamber horizontal overflow hole vertical overflow hole valve body (3/2 ) Pressure chamber cone seat Inlet throttle shoulder cross hole Drain oil drain outlet line valve body (2/2) Pressure chamber drilling

longitudinal bore

Seat

^' Control part

High pressure collecting room (Cornmon Rail)

butt joint

High pressure fuel pump

leader

returns

tank

Nozzle holder combination (DHKV injector

Injection opening 99 second injection period 3/2-WV

Nozzle needle 100 third injection period 3/2-WV

Nozzle chamber 101 first pressure level 312- WV pressure-free outlet 102 opening time 2/2-WV

103 Closing time 2/2-WV integrated version 104 simultaneous opening 3/2-WV, 2/2-WV without boat divided version (Rail DHK) 105 second pressure level 2/2-WV

Connection line 106 top dead center engine piston

107 start of spraying before O.T.

Needle stroke 108 pre-injection

Timeline 109 post-injection

Injection pressure curve 110 Partial opening of the needle

Boot phase 111 nozzle needle fully open short boot phase 112 opening time pre-injection long boot phase 113 opening time main input

Pressure maximum injection

Main injection phase 114 opening time afterwards

Maximum pressure injection

Boat pressure 115 Postponed opening duration falling pressure flank 2/2-WV rising pressure flank 116 Opening time 2/2-WV first injection start 3/2-WV 117 Closing time 2/2-WV second injection start 3/2-WV third injection start 3/2-WV first injection duration 3/2-WV

Claims

claims

1. Device for injecting fuel into the combustion chamber of a self-igniting internal combustion engine with a control unit (6, 80) which acts on a spring-controlled injection device (56) which comprises a nozzle needle (58) and which

Control unit (6, 80) contains a first valve (10) and a second valve (11), each comprising a pressure chamber (28, 36) which are connected to one another via a pressure line (32, 81), characterized in that the first valve (10) and the second valve (11) are connected in series, the first valve (10) controlling the pressurization of the pressure chamber (36) of the second valve (11) and the height

(91, 92) of the injection pressure during the injection phases (86, 87, 88; 90) is controlled by the second valve (11).

2. Device for injecting fuel according to claim 1, characterized in that the first valve (10) is a 3/2-way valve whose pressure chamber (28) acts on a high pressure inlet (1) and is below the pressure chamber (28) a closable, pressure-free outlet (3) and the pressure line (32, 81) branches off.

3. Device for injecting fuel according to claim 1, characterized in that the second valve (11), which can be acted upon via the first valve (10), as 2/2

Directional valve is formed, from the pressure chamber (36) of which a high-pressure outlet (3) runs to the nozzle chamber (59) of the injection device (56).

4. Device for injecting fuel according to claim 1, characterized in that the control unit (6, 80) actuating devices (4, 5) for the first valve

(10) and the second valve (11), which are each separated from the fuel via a membrane element (17).

5. Device for injecting fuel according to claim 4, characterized in that the membrane elements (17) on an upper part (7, 7.1, 7.2) of the control unit

(6) above a joint to a central part (8, 8.1, 8.2) of the control part (6, 80).

6. Device for injecting fuel according to claim 2, characterized in that the first valve (10) contains a valve body (27) whose conical seat (29) closes the pressure line (32) and the unpressurized outlet (3).

7. ^" Device for injecting fuel according to Claim 6, characterized in that the valve body (27) contains an inlet throttle (30) which is connected via a channel to a control chamber (24) which can be relieved of pressure by an actuating device (4).

8. Device for injecting fuel according to claim 6, characterized in that the valve body (27) comprises an extension (31) which closes or releases the unpressurized outlet (3) according to the stroke of the valve body (27).

9. Device for injecting fuel according to claim 6, characterized in that the stroke away from the valve body (27) of the first valve (10) is limited by a stop surface (18) which is formed by a central part (8) of the control unit (6, 80) is formed.

10. The device for injecting fuel according to claim 7, characterized in that a control quantity which is discharged via a discharge throttle (23) when the control chamber (24) is relieved of pressure via an overflow bore (25), an outflow line (34) into the unpressurized discharge (3). is derived.

11. Device for injecting fuel according to claim 3, characterized in that the second valve (11) has a valve body (35) which contains a conical seat (39), above which a throttle point (37) is arranged, which with a High-pressure drain (2) facing longitudinal bore (38) is connected.

12. Device according to claim 1, characterized in that the control unit (6, 80) is accommodated on the high-pressure collecting space (50).

13. The device according to claim 1, characterized in that the control unit (6) is arranged directly above the injection device (56).

14. The device according to claim 1, characterized in that the control unit (80) is divided, the part (7.1, 8.1, 9.1) receiving the first valve (10) on the high-pressure collection chamber (50) and the second valve (11). receiving part (7.2, 8.2, 9.2) is assigned to the injection device (56).

15. Device according to claim 14, characterized in that the pressure spaces (28, 36) of the first valve (10) and the second valve (11) are connected via a line connection (81).

6. Device according to claim 1, characterized in that a control unit (6, 80) and an injection device (56) are assigned to each cylinder of a self-igniting internal combustion engine.