EP1497543A1

EP1497543A1 - Fuel injection system for an internal combustion engine and method for operating a fuel injection system

Info

Publication number: EP1497543A1
Application number: EP03720258A
Authority: EP
Inventors: Andreas Huber; Andreas-Juergen Rohatschek; Udo Schulz; Rolf Ellwein
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-04-09
Filing date: 2003-04-04
Publication date: 2005-01-19
Also published as: CN1630777A; JP2005522614A; DE10215627A1; US20050284443A1; WO2003085245A1

Abstract

The invention relates to a fuel injection system for an internal combustion engine, particularly for a diesel engine, comprising at least two cylinders. The fuel injection system comprises at least two actuator units, and at least one actuator element for injecting fuel into the cylinder is assigned to each cylinder. The fuel injection system additionally comprises an injection control for monitoring and/or for resolving a conflict when controlling the actuator elements. The invention is characterized in that the injection control controls the actuator elements earlier and/or later or not at all according to charging and/or discharging flanks of the injection elements during injections.

Description

Fuel injection system for an internal combustion engine and method for operating a fuel injection system

The invention relates to a fuel injection system for an internal combustion engine, in particular a diesel engine, with at least two cylinders, the fuel injection system having at least two actuator elements, and each cylinder being assigned at least one actuator element for injecting fuel into the cylinder. The invention further relates to a method for operating such a fuel injection system.

DE 100 33 343 A1 discloses a fuel injection system for an internal combustion engine, in particular a diesel engine, which has an injection control system for monitoring and / or solving a conflict when actuating the actuator elements, in particular conflict management for overlapping injection profiles of piezo actuators. With piezo common rail actuators, only one control edge can be executed at the same time. For reasons of combustion technology, however, it is necessary to apply controls to complementary banks in such a way that injections overlap. This is possible with the circuit device known from DE 100 33 343 A1 for interconnecting piezoelectric elements if the charging / discharging edges of the piezoelectric elements have no overlap. In the case of overlapping edges, it is provided in the fuel injection system resulting from DE 100 33 343 AI that the control with low priority (hereinafter referred to as low priority control) is shifted or shortened.

According to DE 100 33 343 AI, however, there is only a reaction in the case of low-priority injections, namely a shortening of the low-priority injection in such a way that not one actuator is charged while another is to be loaded or unloaded, or a displacement of the low-priority injection in such a way that Flanks of injections from different actuators do not overlap, or a delay in low-priority injection in such a way that edges of different injections do not overlap.

The object of the invention is to develop a fuel injection system for an internal combustion engine and a method for operating a fuel injection system so that any collisions, in particular also Collisions of injections of the same priority can be prevented.

This object is achieved in a fuel injection system for an internal combustion engine of the type described in the introduction in that the injection control controls the actuator elements earlier and / or later or not as a function of the loading and / or unloading edges of the injection elements.

The object is further achieved by a fuel injection system for an internal combustion engine, in particular a diesel engine, with at least two cylinders, the fuel injection system having at least two piezoelectric elements and each cylinder having at least one piezoelectric element for injecting fuel into the cylinder by charging or discharging the piezoelectric element is assigned, with the piezoelectric elements being assigned a single supply unit for charging or discharging the piezoelectric element, the fuel injection system also having an injection control for monitoring a possible overlap of a time interval in which a piezoelectric element is to be charged or discharged, with a time interval in to which the other piezoelectric element is to be charged or discharged, and wherein at least two injections are assigned different priorities such that one injection e higher priority (high-priority injection) than at least one injection (low-priority injection) is assigned, solved in that the injection control shifts and / or deletes the at least one injection with the lower priority and / or the at least one injection with the higher priority depending on the loading and / or unloading edges of the injection elements in the case of injections early and / or late.

The object is further achieved according to the invention by a method according to claim 5 and a method according to claim 6.

In an advantageous embodiment of the invention it is provided that the shift is dependent on the priority of the injection.

However, in another advantageous embodiment of the invention, the shift can also take place independently of the priority.

The shift may also depend on the type of injection, i.e. depending on whether there is a pre-injection, a main injection or a post-injection.

In a further advantageous embodiment of the invention, the shift is dependent on previous shifts.

The shift can also take place depending on or regardless of the type of overlap of at least two injections. In the case of singular primary collisions, that is, when two arbitrary edges with the same or different priority overlap, if no other edge pair overlaps, the following shifts are possible:

a) shifting the edge with low priority (low priority edge) early, or b) shifting the lower priority edge late, or c) shifting the edge higher priority (higher priority edge) early, or d) shifting the higher priority Flank to the late, or e) shifting the higher-priority flank to the early, simultaneous shifting of the lower-priority flank to the late, or f) shifting the higher-priority flank to the late, simultaneous shifting of the lower-priority flank to the early, or g) shifting the higher-priority flank to the late and simultaneous shift of the lower-priority flank to late, or h) shift of the higher-priority flank to early, simultaneous shift of the lower-priority flank to early, whereby the time interval in which a piezoelectric element is to be loaded or unloaded does not overlap with the time interval in which the other piezoelectric element is to be charged or discharged.

Another embodiment of the invention provides that the flanks not involved in the overlap follow be postponed early or late or left unchanged. For example, the injection associated with the high priority flank or the injection associated with the low priority flank cannot be carried out, if causally possible.

With multiple primary collisions, i.e. in the case of a coherent overlap of any three or four flanks, for example if four flanks overlap either coherently or separately, the following shift occurs:

a) Each of the overlapping flanks can be moved early or late. b) Not all overlapping flanks have to be shifted. c) In addition, flanks not involved in the overlap are shifted early or late.

Further advantages, features and details of the invention result from the following description of exemplary embodiments and the drawing.

The drawing shows:

1 shows an interconnection of piezoelectric elements known from the prior art;

2a shows the loading of a piezoelectric element;

2b the loading of a piezoelectric element;

2c ^• the unloading of a piezoelectric element; 2d the discharge of a piezoelectric element;

3 shows a control IC;

4 shows the chronological sequence of interrupts known from the prior art;

5 schematically shows the combination of overlapping flanks of two injections;

Fig. 6 schematically for assigning priorities and

7 shows the measures for displacement in the case of singular primary collisions of flanks.

Fig. 1 shows piezoelectric elements 10, 20, 30, 40, 50, 60 and means for driving them. A denotes a region in a detailed representation and B a region in an undetailed representation, the separation of which is indicated by a dashed line c. The area A shown in detail comprises a circuit for charging and discharging the piezoelectric elements 10, 20, 30, 40, 50 and 60. In the example considered, the piezoelectric elements 10, 20, 30, 40, 50 and 60 are Actuators in fuel injection valves (especially in so-called ACom on Rail injectors≡) of an internal combustion engine. In the described embodiment, six piezoelectric elements 10, 20, 30, 40, 50 and 60 are used to independently control six cylinders within an internal combustion engine; however, any number of piezoelectric elements could be suitable for any other purpose. The area B shown in detail comprises an injection control F with a control unit D and a control IC E which serves to control the elements within the area A shown in detail. The control IC E is supplied with various measured values of voltages and currents from the entire remaining control circuit of the piezoelectric element. According to the invention, the control computer D and the control IC E are designed to regulate the control voltages and the control times for the piezoelectric element. The control computer D and / or the control IC E are also designed to monitor various voltages and currents of the entire control circuit of the piezoelectric element.

In the following description, the individual elements are first introduced within the area A shown in detail. The following is a general description of the processes of charging and discharging the piezoelectric elements 10, 20, 30, 40, 50 and 60. Finally, it will be described in detail how both processes are controlled and monitored by the control computer D and the drive IC E.

The piezoelectric elements 10, 20, 30, 40, 50 and 60 are divided into a first group Gl and a second group G2, each of which comprises three piezoelectric elements (ie, piezoelectric elements 10, 20 and 30 in the first group Gl and piezoelectric elements 40, 50 and 60 in the second group G2). The groups Gl and G2 are components connected in parallel ter circuit parts. The group selection switches 310, 320 can be used to determine which of the groups Gl, G2 of the piezoelectric elements 10, 20 and 30 or 40, 50 and 60 are each discharged with the aid of a common charging and discharging device (the group selection switches 310 are used for charging processes) , 320, as described in more detail below, but without meaning). The piezoelectric elements 10, 20 and 30 of the first group G1 are arranged on an actuator bank and the piezoelectric elements 40, 50 and 60 in the second group G2 are arranged on a further actuator bank. An actuator bank is a block in which two or more actuator elements, in particular piezoelectric elements, are permanently arranged, for example cast.

The group selection switches 310, 320 are arranged between a coil 240 and the respective groups Gl and G2 (their coil-side connections) and are implemented as transistors. Drivers 311, 321 are implemented which convert control signals received from the control IC E into voltages which can be selected as required for closing and opening the switches.

Diodes 315 and 325 (referred to as group selection diodes) are provided in parallel to the group selection switches 310, 320. If the group selection switches 310, 320 are designed as MOSFETs or IGBTs, these group selection diodes 315 and 325 can, for example, be formed by the parasitic diodes themselves. During charging, the group selection switches 310, 320 are bridged by the diodes 315, 325. The functionality of the group The selector switch 310, 320 is therefore reduced to the selection of a group Gl, G2 of the piezoelectric elements 10, 20 and 30 or 40, 50 and 60 only for one discharge process.

The piezoelectric elements 10, 20 and 30 or 40, 50 and 60 are arranged within the groups G1 and G2 respectively as components of the piezo branches 110, 120 and 130 (group G1) and 140, 150 and 160 (group G2) connected in parallel. Each piezo branch comprises a series circuit consisting of a first parallel circuit with a piezoelectric element 10, 20, 30, 40, 50 and 60, and a resistor (referred to as a branch resistor) 13, 23, 33, 43, 53 and 63 and a second Parallel connection with a selector switch designed as a transistor 11, 21, 31, 41, 51 or 61 (referred to as a branch selector switch) and a diode 12, 22, 32, 42, 52 or 62 (referred to as a branch diode).

The branch resistors 13, 23, 33, 43, 53 and 63 have the effect that the respective corresponding piezoelectric element ent 10, 20, 30, 40, 50 and 60 discharges continuously during and after a charging process, since they each do both Connect the connections of the capacitive piezoelectric elements 10, 20, 30, 40, 50 and 60 to one another. The branch resistors 13, 23, 33, 43, 53 and 63, however, are of sufficient size to make this process slow compared to the controlled charging and discharging processes, as described below. Therefore, the charge of any piezoelectric Elements 10, 20, 30, 40, 50 and 60 within a relevant time after a charging process can be regarded as unchangeable.

The branch selector switches / branch diode pairs in the individual piezo branches 110, 120, 130, 140, 150 and 160, ie, selector switch 11 and diode 12 in piezo branch 110, selector switch 21 and diode 22 in piezo branch 120 etc., can be implemented as electronic switches (ie Transistors) with parasitic diodes, for example MOSFETs or IGBTs (as indicated above for the group selector switch / diode pairs 310 and 315 or 320 and 325).

The branch selection switches 11, 21, 31, 41, 51 and 61 can be used to determine which of the piezoelectric elements 10, 20, 30, 40, 50 and 60 are to be charged with the aid of a common charging and discharging device: all are charged those piezoelectric elements 10, 20, 30, 40, 50 and 60, respectively, whose branch selection switches 11, 21, 31, 41, 51 and 61 are closed during the charging process described below. Usually only one of the branch selection switches is closed.

The branch diodes 12, 22, 32, 42, 52 and 62 serve to bridge the branch selection switches 11, 21, 31, 41, 51 and 61 during unloading processes. Therefore, in the example under consideration, each individual piezoelectric element can be selected for charging processes, while for discharging processes either the first group Gl or the second group G2 of the piezoelectric elements 10, 20 and 30 or 40, 50 and 60, or both must be selected.

Returning to the piezoelectric elements 10, 20, 30, 40, 50 and 60 themselves, the branch selection piezo connections 15, 25, 35, 45, 55 and 65 can either be operated using the branch selection switches 11, 21, 31, 41, 51 or 61 or via the corresponding diodes 12, 22, 32, 42, 52 or 62 and in both cases additionally via resistor 300 to ground.

The resistance 300 measures the currents flowing during the charging and discharging of the piezoelectric elements 10, 20, 30, 40, 50 and 60 between the branch selection piezo connections 15, 25, 35, 45, 55 and 65 and ground. Knowledge of these currents enables controlled charging and discharging of the piezoelectric elements 10, 20, 30, 40, 50 and 60. In particular, by closing and opening the charging switch 220 or discharging switch 230 depending on the amount of the currents, it is possible to determine the charging current or to set the discharge current to predetermined mean values and / or to prevent them from exceeding or falling below predetermined maximum values and / or minimum values.

In the example under consideration, a voltage source 621, which supplies a voltage of, for example, 5 V DC, and a voltage divider in the form of two resistors 622 and 623 are also required for the measurement itself. The control IC E (which measures the gen)) are protected against negative voltages that could otherwise occur at measuring point 620 and that cannot be controlled with the control IC E: Such negative voltages are obtained by adding one of the voltage sources 621 and the voltage dividing resistors 622 and 623 delivered positive voltage arrangement changed.

The other terminal of the respective piezoelectric element 10, 20, 30, 40, 50 and 60, i.e. the respective group selection piezo connection 14, 24, 34, 44, 54 or 64 can be made via the group selection switch 310 or 320 or via the group selection diode 315 or 325 as well as via a coil 240 and a parallel connection consisting of a charging switch 220 and a charging diode 221 can be connected to the positive pole of a voltage source, or alternatively or additionally via the group selector switch 310 or 320 or via the diode 315 or 325 as well as via the coil 240 and a parallel connection consisting of a discharge switch 230 and a discharge diode 231 to ground be placed. Charge switch 220 and discharge switch 230 are implemented, for example, as transistors which are controlled via drivers 222 and 232, respectively.

The voltage source comprises a capacitor 210. The capacitor 210 is charged by a battery 200 (for example a motor vehicle battery) and a downstream DC / DC converter 201. The DC voltage converter 201 forms the battery voltage (for example 12 V) into essentially any desired their DC voltages (for example 250 V), and charges the capacitor 210 to this voltage. The DC-DC converter 201 is controlled via the transistor switch 202 and the resistor 203, which is used to measure currents tapped at the measuring point 630.

For the purpose of counter-control, the control IC E as well as the resistors 651, 652 and 653 and for example a 5 V DC voltage source 654 enable a further current measurement at the measuring point 650; Furthermore, the control IC E and the voltage-dividing resistors 641 and 642 make it possible to measure the voltage at the measuring point 640.

Finally, a resistor 330 (called a total discharge resistor), a switch 331 (called a stop switch) and a diode 332 (called a total discharge diode) serve to discharge the piezoelectric elements 10, 20, 30, 40, 50 and 60 (if they are outside the normal operator) , as described below, cannot be discharged through the abnormal ≤ discharge process). The stop switch 331 is preferably closed after abnormalities Ent discharge processes (cyclical discharge via discharge switch 230) and thereby connects the piezoelectric elements 10, 20, 30, 40, 50 and 60 to the resistors 330 and 300 to ground. This eliminates any residual voltages that may remain in the piezoelectric elements 10, 20, 30, 40, 50 and 60. The total discharge diode 332 prevents the occurrence of negative voltages on the piezoelectric elements 10, 20, 30, 40, 50 and 60, which could possibly be damaged by the negative voltages.

The loading and unloading of all piezoelectric elements 10, 20, 30, 40, 50 and 60, or a specific piezoelectric element 10, 20, 30, 40, 50 or 60, is carried out with the aid of a single one (all groups and their piezoelectric elements common) loading and unloading device. In the example considered, the common charging and discharging device comprises the battery 200, the DC / DC converter 201, the capacitor 210, the charging switch 220 and the discharging switch 230, charging diode 221 and discharging diode 231 and the coil 240.

Each piezoelectric element is charged and discharged in the same way and is explained below with reference to only the first piezoelectric element 10.

The states occurring during the charging and discharging processes are explained with reference to FIGS. 2A to 2D, of which FIGS. 2A and 2B illustrate the charging of the piezoelectric element 10, and FIGS. 2C and 2D illustrate the discharging of the piezoelectric element 10.

Controlling the selection of one or more piezoelectric elements 10 to be charged or discharged, 20, 30, 40, 50 and 60, the charging process described below and the discharging process are carried out by the control IC E and the control device D by opening or closing one or more of the switches 11, 21, 31, 41, 51 introduced above , 61; 310, 320; 220, 230 and 331. The interactions between the elements within the detailed area A on the one hand and the control IC E and the control computer D on the other hand will be explained in more detail below.

With regard to the charging process, a piezoelectric element 10, 20, 30, 40, 50 or 60 to be charged must first be selected. In order to charge only the first piezoelectric element 10, the branch selection switch 11 of the first branch 110 is closed, while all other branch selection switches 21, 31, 41, 51, and 61 remain open. In order to load only any other piezoelectric element 20, 30, 40, 50, 60, or to load several at the same time, its selection would be made by closing the corresponding branch selection switches 21, 31, 41, 51, and / or 61 ,

The charging process can then take place itself:

Within the example considered, a positive potential difference between the capacitor 210 and the group selection piezo connection 14 of the first piezoelectric element 10 is generally required for the charging process. However, as long as the charging switch 220 and discharging switch 230 are open, there is no charging or discharge of the piezoelectric element 10. In this state, the circuit shown in FIG. 1 is in a stationary state, ie the piezoelectric element 10 maintains its state of charge essentially unchanged, with no currents flowing.

Switch 220 is closed to charge the first piezoelectric element 10. Theoretically, the first piezoelectric element 10 could be charged by this alone. However, this would result in large currents that could damage the elements in question. Therefore, the currents that occur are measured at measuring point 620 and switch 220 is opened again as soon as the detected currents exceed a certain limit value. In order to achieve any charge on the first piezoelectric element 10, charge switch 220 is therefore repeatedly closed and opened, while discharge switch 230 remains open.

On closer inspection, resulting in the closed charging switch 220, the conditions shown in Fig. 2A, it ie, a closed circuit comprising a series circuit consisting of the piezoelectric element 10, capacitor 210 and coil 240, wherein iτ_ in the circuit, a current _I (t ) flows, as indicated by arrows in FIG. 2A. Because of this current flow, positive charges are both supplied to the group selection piezo connection 14 of the first piezoelectric element 10 and energy is stored in the coil 240. If the charging switch 220 opens shortly (for example a few μs) after closing, the conditions shown in FIG. 2B result: a closed circuit is formed comprising a series circuit consisting of the piezoelectric element 10, discharge diode 231 and coil 240, in the circuit a current i _LA (t) flows, as indicated by arrows in FIG. 2B. Because of this current flow, energy stored in the coil 240 flows into the piezoelectric element 10. Corresponding to the energy supply to the piezoelectric element 10, the voltage occurring in it increases and its external dimensions increase. When the energy has been transferred from the coil 240 to the piezoelectric element 10, the stationary state of the circuit shown in FIG. 1 and already described is reached again.

At this point in time or earlier or later (depending on the desired time profile of the charging process), charging switch 220 is closed again and opened again, so that the processes described above run again. Due to the closing and reopening of the charging switch 220, the energy stored in the piezoelectric element 10 increases (the energy already stored in the piezoelectric element 10 and the newly supplied energy add up), and the voltage occurring at the piezoelectric element 10 increases and its external dimensions increase accordingly. If the above-mentioned closing and opening of the charging switch 220 is repeated many times, the voltage occurring at the piezoelectric element 10 is increased and the piezoelectric element 10 is expanded in steps.

When the charging switch 220 has been closed and opened a predetermined number of times and / or the piezoelectric element 10 has reached the desired charge state, the charging of the piezoelectric element is ended by leaving the charging switch 220 open.

With regard to the discharge process, in the example under consideration the piezoelectric elements 10, 20, 30, 40, 50 and 60 are discharged in groups (Gl and / or G2) as described below:

First, the group selector switches 310 and / or 320 of the group Gl and / or G2, the piezoelectric elements of which are to be discharged, are closed (the branch selector switches 11, 21, 31, 41, 51, 61 have no influence on the selection of the piezoelectric elements 10, 20, 30, 40, 50, 60 for the discharge process, since in this case they are bridged by the diodes 12, 22, 32, 42, 52 and 62). In order to discharge the piezoelectric element 10 as part of the first group Gl, the first group selection switch 310 is therefore closed.

When the discharge switch 230 is closed, the conditions shown in FIG. 2C result: a closed circuit comprising a rice circuit consisting of the piezoelectric element 10 and the coil 240, wherein a current iκ _E () flows in the circuit, as indicated in FIG. 2C by arrows. Because of this current flow, the energy stored in the piezoelectric element (part of it) is transferred to the coil 240. Corresponding to the energy transfer from the piezoelectric element 10 to the coil 240, the voltage occurring at the piezoelectric element 10 drops and its outer dimensions decrease.

If the discharge switch 230 opens shortly (for example, a few μs) after closing, the conditions shown in FIG. 2D result: a closed circuit comprising a series connection consisting of the piezoelectric element 10, capacitor 210, charging diode 221 and the coil 240 is created , wherein a current i _EA () flows in the circuit, as indicated by arrows in FIG. 2D. Because of this current flow, energy stored in coil 240 is returned to capacitor 210. When the energy has been transferred from the coil 240 to the capacitor 210, the stationary state of the circuit shown in FIG. 1 and already described is reached again.

At this point in time or earlier or later (depending on the desired time profile of the discharge process), discharge switch 230 is closed again and opened again, so that the processes described above run again. Due to the reclosing and reopening of the discharge switch 230, the in energy stored in the piezoelectric element 10 continues to decrease, and the voltage occurring at the piezoelectric element and its external dimensions also decrease accordingly.

If the above-mentioned closing and opening of the discharge switch 230 is repeated a number of times, the voltage occurring at the piezoelectric element 10 and the expansion of the piezoelectric element 10 decrease in stages.

When the discharge switch 230 has been closed and opened a predetermined number of times and / or the piezoelectric element has reached the desired charge state, the discharge of the piezoelectric element is ended by leaving the discharge switch 230 open.

The interaction between the control IC E and the control computer D on the one hand and the elements within the area A shown in detail on the other hand takes place with the aid of control signals which via branch selection control lines 410, 420, 430, 440, 450, 460, group selection control lines 510, 520, stop switch control - Lead 530, charge switch control line 540 and discharge switch control line 550 as well as control line 560 elements are supplied from the control IC E within the region A shown in detail. On the other hand, sensor signals are detected at the measuring points 600, 610, 620, 630, 640, 650 within the region A shown in detail, which signals the control IC E can be supplied via the sensor lines 700, 710, 720, 730, 740, 750.

To select the piezoelectric elements 10, 20, 30, 40, 50 and 60 for carrying out charging or discharging processes of individual or more piezoelectric elements 10, 20, 30, 40, 50, 60 by opening and closing the corresponding switches such as As described above, voltages are or are not applied to the transistor bases by means of the control lines. The sensor signals are used in particular to determine the resulting voltage of the piezoelectric elements 10, 20 and 30, or 40, 50 and 60 on the basis of the measuring points 600 and 610 and the charge and discharge currents on the basis of the measuring point 620.

3 shows some of the components contained in the control IC E: a logic circuit 800, memory 810, digital-to-analog converter module 820 and comparator module 830. Furthermore, it is stated that the fast parallel bus 840 (used for control signals) is connected to the logic circuit 800 of the drive IC E, while the slower serial bus 850 is connected to the memory 810. The logic circuit 800 is connected to the memory 810, to the comparator module 830 and to the signal lines 410, 420, 430, 440, 450 and 460; 510 and 520; 530, 540, 550 and 560 connected. The memory 810 is connected to the logic circuit 800 and to the digital-to-analog converter module 820. Furthermore, the digital-to-analog converter module 820 with the comparator block 830 connected. In addition, the comparator module 830 is connected to the sensor lines 700 and 710, 720, 730, 740 and 750 and - as already mentioned - to the logic circuit 800.

The injection of the piezoelectric elements is characterized by a charging and a discharging flank, as can be seen, for example, from FIG. 4. In the following, the loading flank is referred to as the starting flank B and the unloading flank as the end flank E. As mentioned above, with piezo elements it is a conceptual restriction that only one charging or discharging flank can take place at the same time. Therefore, if an overlap is identified, a reaction must take place according to a defined strategy. First, any combination of overlapping flanks of two injections is assumed, as is shown schematically in FIG. 5.

The possible strategies are any combination of the following measures:

1. Any four priorities are assigned to the four edges, as can be seen in FIG. 6. All four edges can either have a) only different or b) partially different or c) the same priority.

2. A measure for singular primary collisions is described below. As a singular primary col lision is an overlap of any two edges with the same or different priority if no other edge pair overlaps at the same time. The following shifts are possible:

a) Shifting the lower-priority flank to early, or b) Shifting the lower-priority flank to late, or c) Shifting the higher-priority flank to early, or d) Shifting the higher-priority flank to late, or e) Shifting the higher-priority flank after early, simultaneous shifting of the lower priority flank to late, or f) shifting of the higher priority flank to late, simultaneous shifting of the higher priority flank to early, or g) shifting of the higher priority flank to late, simultaneous shifting of the lower priority flank to late, or h) Shifting the higher-priority edge earlier, simultaneously shifting the lower-priority edge earlier,

so that the time interval in which a piezoelectric element is to be charged or discharged does not overlap with the time interval in which the other piezoelectric element is to be charged or discharged.

If the priority of both edges is the same, the higher or lower priority injection can be postponed early or late in any way.

If the flank shifted earlier is a start flank, the measure corresponds to a shift in the injection early, provided the associated end flank is shifted early with the same amount.

If the flank shifted towards early is an end flank, the measure corresponds to a reduction in the injection duration, provided the associated starting flank remains unchanged.

If the flank shifted to the late is a start flank, the measure corresponds to a shift in the injection late, provided the associated end flank is shifted late by the same amount.

If the flank shifted towards the end is an end flank, the measure corresponds to an extension of the injection duration, provided the associated starting flank remains unchanged. It is also possible to move the flanks that are not involved in the overlap early or late. All possible combinations are shown in Fig. 7. If both overlapping flanks are shifted early, the degree of the shift must be different, the same applies to the shifting of both overlapping flanks late.

3. Measures in the event of a singular secondary collision

A singular secondary collision is the result of an overlap of any two edges with the same or different priority resulting from the displacement of the primary collision if no other pair of edges overlaps at the same time. The same displacement measures are possible as for a singular primary collision. The measure for displacement in the case of a singular secondary collision should be chosen so that no further subsequent collision occurs. Otherwise, a tertiary or higher-value collision is possible, to which the primary and secondary collision must be reacted accordingly.

4. Measures in the event of a multiple primary collision

A multiple primary collision is a continuous overlap of any three or four edges. If four edges overlap, they can overlap either contiguously or separately. Any measures for shifting are possible while observing the following boundary conditions: a) Each of the overlapping flanks can be moved early or late; b) not all overlapping flanks have to be shifted. c) After the shift, the previously overlapping flanks are free of overlap, so that the time interval in which one piezoelectric element is to be loaded or unloaded does not overlap with the time interval in which the other piezoelectric element is to be loaded or unloaded. d) In addition, flanks not involved in the overlap can be shifted early or late.

5. Measures in the event of multiple secondary collisions

A multiple secondary collision is a coherent overlap of three or four edges resulting from the measure for shifting a primary collision. The same measures are possible as for multiple primary collisions. The measure in the case of a multiple secondary collision should be sensible so that a further subsequent collision does not occur. Otherwise, a tertiary or higher-value collision is possible, to which you have to react analogously to the primary and secondary collision. Variants of these measures are possible, whereby in addition to the measures for postponement mentioned under points 2 to 5, the following must also be taken into account:

a) When selecting the displacements, not only the priorities but also the types of colliding injections are taken into account; b) when selecting the shifts, the shifts of the past are taken into account with the same and / or different type of overlap than the one under consideration; c) the injection associated with the high-priority flank is not carried out, if causally possible; d) the injection associated with the lower-priority flank is not carried out, if causally possible; e) one or more injections are added so that, for example, the target quantity is reached when shortened; f) If an injection is postponed early or late and / or shortened or lengthened, then one or more other injection (s) not affected by the overlap are changed in the same or a different way, for example with one modified first post-injection, the second post-injection, which is then not affected, can be changed. Under certain circumstances, the injection cannot be carried out. It is also conceivable that flanks of ^• more than two injections overlap or that a measure results in a collision with another injection. Here too, the measures for displacement described under point 4. a) to d) are possible.

Claims

claims

1. A fuel injection system for an internal combustion engine, in particular a diesel engine, with at least two cylinders, the fuel injection system having at least two actuator elements, and with each cylinder being assigned at least one actuator element for injecting fuel into the cylinder, and wherein the fuel injection system is equipped with an injection control unit - Monitoring and / or to solve a conflict when driving the actuator elements, characterized in that the injection control controls the actuator elements depending on the loading and / or unloading edges of the injection elements earlier and / or later or not at injections.

2. Fuel injection system according to claim 1, characterized in that the actuator elements are piezoelectric elements.

3. Fuel injection system according to claim 1, characterized in that the actuator elements are solenoid valves.

Fuel injection system for an internal combustion engine, in particular a diesel engine, with at least two cylinders, the fuel injection system having at least two piezoelectric elements and at least one for each cylinder. piezoelectric element for injecting fuel into the cylinder by charging or discharging the piezoelectric element is assigned, and wherein the piezoelectric elements are assigned a single supply unit for charging or discharging the piezoelectric element, the fuel injection system being an injection control system for monitoring a possible overlap a time interval in which one piezoelectric element is to be loaded or unloaded, with a time interval in which the other piezoelectric element is to be loaded or unloaded, and wherein at least two injections are assigned different priorities such that one injection has a higher one Priority (high-priority injection) is assigned as at least one other injection (low-priority injection), characterized in that the injection control means the injection of the same or different priority depending on the loading and unloading d / or the discharge flanks of the injection elements in the case of injections are shifted early and / or late and / or are deleted in such a way that one piezoelectric element is not charged when the other piezoelectric element is to be charged or discharged.

Method for operating a fuel injection system for an internal combustion engine with at least two cylinders, in particular for operating a fuel injection system according to one of the preceding claims, wherein the fuel injection system has at least two actuating oil elements, and wherein each cylinder has at least one actuating element for injecting fuel into each Cylinder is assigned, and possible conflicts during the actuation of the actuating elements are monitored and / or resolved, characterized in that the actuating elements are dependent on the course of the loading and / or unloading flanks of the injection elements earlier and / or later or at all in the case of injections cannot be controlled.

Method for operating a fuel injection system for an internal combustion engine with at least two cylinders, in particular for operating a fuel injection system according to claim 4, wherein the fuel injection system has at least two piezoelectric elements and each cylinder has at least one piezoelectric element for injecting fuel into the cylinder by charging or Discharge is associated with the piezoelectric element, and wherein the piezoelectric elements are assigned a supply unit for charging or discharging the piezoelectric element, and monitoring is carried out to determine whether an overlap of a time interval in which a piezoelectric element is being charged or discharged, with a time interval in which the other piezoelectric element is to be charged or discharged, characterized in that an injection of the same or different priority depending on the loading and / unloading edges of the injection elements during an injection shifted early and / or late and / or deleted in such a way that one piezoelectric element is not charged when the other piezoelectric element is to be charged or discharged.

7. The method according to claim 6, characterized in that the shift is dependent on the priority of the injections.

8. The method according to claim 6, characterized in that the shift is independent of the priority of the injections.

9. The method according to any one of claims 6 to 8, characterized in that the displacement takes place depending on the type of overlap at least two injections.

10. The method according to any one of claims 6 to 8, characterized in that the displacement takes place regardless of the type of overlap of at least two injections.

11. The method according to any one of claims 6 to 10, characterized in that the displacement depends gig of the type of injection (pre-injection, main injection, post-injection).

12. The method according to any one of claims 6 to 11, characterized in that the shift is dependent on previous shifts.

13. The method according to any one of claims 5 to 12, characterized in that in the case of singular primary or secondary collisions, the displacement takes place on the basis of one of the following measures:

a) shifting the lower-priority flank towards the beginning, or b) shifting the lower-priority flank towards the end, or c) shifting the higher-priority flank towards the end, or d) shifting the higher-priority flank towards the end, or e) moving the higher-priority flank towards the end, simultaneously Shifting the lower-priority edge late, or f) Shifting the higher-priority edge late, simultaneously shifting the lower-priority edge late, or g) Shifting the higher-priority edge late, simultaneously shifting the lower-priority edge late, or h) Shifting the higher-priority flank early, simultaneously shifting the lower-priority flank early.

14. The method according to any one of claims 5 to 13, characterized in that the edges not involved in the overlap are moved to early or late or left.

15. The method according to any one of claims 5 to 14, characterized in that in the case of multiple primary or secondary collision, the displacement is carried out while observing the following boundary conditions:

a) each of the overlapping flanks can be moved early or late; b) not all overlapping flanks have to be shifted; c) after a shift, the previously overlapping flanks are free of overlap so that the time interval in which one piezoelectric element is to be loaded or unloaded does not overlap with the time interval in which the other piezoelectric element is to be loaded or unloaded; d) in addition, flanks not involved in the overlap can be shifted early or late.