EP3763933A1 - Method for volumetric flow based pump-synchronous, in particular cylinder-selective rail pressure control for a fuel supply system of a combustion engine with current detection and current regulation of the actuators of the rail pressure control - Google Patents

Abstract

The invention relates to a method for regulating a rail pressure (p7 _Soll) caused by a high-pressure pump (1) in a fuel accumulator (4) for a fuel supply system (100) of an internal combustion engine, with a crank angle-related or cam angle-related fixed angle difference of Internal combustion engine between a top dead center position of a cylinder piston of a cylinder of the internal combustion engine and a top dead center position of the pump piston of the high pressure pump (1) of the fuel supply system (100) is taken into account when metering the delivery volume of the high pressure pump (1). that recurring pump-synchronously per segment, which corresponds to one revolution of a crankshaft and thus to the movement of the pump piston of the high-pressure pump (1) from the top dead center position of the pump piston to the next top dead center position, a discretization of a control deviation (Δp ₇) of the rail pressure (p7) in the fuel accumulator (4) vo r taken and based on the discrete control deviation (Δp ₇) a volume-related discrete volume control difference (ΔV _Rail), in particular a volume-related discrete cylinder-selective volume control difference (ΔV _Rail) is calculated.

Description

The invention relates to a method for regulating a rail pressure caused by a high pressure pump in a fuel accumulator for a fuel supply system of an internal combustion engine, wherein a crank angle-related or cam angle-related fixed angular difference of the internal combustion engine between an upper dead center position of a cylinder piston of a cylinder of the internal combustion engine and an upper dead center Position of the pump piston of the high-pressure pump of the fuel supply system is taken into account when metering the delivery volume of the high-pressure pump.

From the pamphlet DE 10 2016 204 386 A1 a method for regulating a rail pressure caused by a high pressure pump in a fuel rail for an internal combustion engine is already known, in which the rail pressure is regulated in synchronism with an engine speed of the internal combustion engine of the high pressure pump. The regulation of the rail pressure does not take place in the known fixed, time-synchronous calculation grid, but takes place in a time-variable, engine-speed-synchronous calculation grid, the respective grid interval of which is preferably from one top dead center to the next, based on a single cylinder or all cylinders of the internal combustion engine extends. The high-pressure pump provides an amount of fuel with each pump delivery stroke. The sequence of the pump delivery strokes of the high-pressure pump does not follow the fixed scanning pattern of the rail pressure regulator in terms of time, but is determined by the current operating state of the internal combustion engine.

The known fuel supply system comprises a rail pressure regulator for using the proposed method. A high-pressure pump is supplied with fuel from a tank by a pre-feed pump via a low-pressure line. The high-pressure pump pumps fuel into a fuel rail via a high-pressure line. The delivery volume of the high pressure pump is set according to a delivery volume control value that a rail pressure regulator has calculated to regulate the rail pressure in the fuel rail. The rail pressure controller is composed of a PID controller and a pilot control unit. A rail pressure control deviation is sent to the PID controller which has been calculated as the difference between the rail pressure setpoint value calculated synchronously with the engine speed and the actual rail pressure value recorded synchronously with the engine speed with a rail pressure sensor, and calculates an additive correction volume flow synchronously with the engine speed. A calculation carried out synchronously with the engine speed means that this calculation is carried out once for each top dead center of the internal combustion engine that has passed through.

An injection quantity calculated synchronously with the engine speed and a desired pressure change value are fed to the pilot control unit, so that the pilot control unit calculates a pilot control value synchronously with the engine speed. The sum of the additive correction volume flow and the precontrol value is fed to the high-pressure pump as a delivery volume control value in order to specify the delivery volume of the current delivery stroke and to set the rail pressure setpoint ps in the fuel rail.

The invention is based on the object of improving the rail pressure regulation.

The starting point of the invention is that with a classic time-synchronous rail pressure control that works in a 10 ms sampling grid, depending on the engine speed, the engine-synchronous pump event is under- or oversampling. This disadvantageously results in pressure fluctuations in the form of beats and aliasing, which cannot be fully regulated even at stationary operating points.

The conventional rail pressure control is also to be adapted, according to the task, to the newly available high pressure pumps, which can provide a volume flow for each work cycle.

The best possible control performance with deviations between setpoint and actual value of less than 2% of the current setpoint should be achieved. Furthermore, computing time and code memory in the control unit should be saved, the calibration and validation effort should be reduced and simple adaptation to different pump designs, pressure control valve variants and high-pressure components should be made possible.

These effects have a particularly negative effect on modern high-pressure pumps, in which the delivery volume is influenced from one delivery stroke to the next in the entire setting range. So far, the only remedy has been an extremely low loop gain, which is the classic Time-synchronous rail pressure regulator, especially in dynamic pressure change situations, is far inferior to the method according to the invention explained below.

According to the preceding statements, a method for regulating a rail pressure caused by a high-pressure pump in a fuel accumulator for a fuel supply system of an internal combustion engine is known, with a crank angle-related or cam angle-related fixed angle difference of the internal combustion engine between a top dead center position of a cylinder piston of a cylinder of the internal combustion engine and a Top dead center position of the pump piston of the high pressure pump of the fuel supply system is taken into account when metering the delivery volume of the high pressure pump.

According to the invention it is now provided that recurring pump-synchronously per segment, which corresponds to one revolution of a crankshaft and thus the movement of the pump piston of the high-pressure pump from the top dead center position of the pump piston to the next top dead center position, a discretization of a control deviation of the rail pressure in the fuel accumulator and based on the discrete control deviation, a volume-related discrete volume control difference, in particular cylinder-selective, is calculated.

According to the invention, the discrete control deviation is calculated as the difference between the discretized actual rail pressure and the discretized target rail pressure, in particular cylinder-selectively, by combining a discretized pressure information of a rail pressure sensor of the actively detected pump-synchronous segment with the discretized target rail pressure of the previous pump-synchronous segment by one work cycle is compared in order to determine the discrete, in particular cylinder-selective control difference.

Preferably, the volume-related discrete volume control difference is fed as an input variable to a control module for the high-pressure pump and a control module for a pressure control valve assigned to the fuel accumulator, the discrete volume control difference being linked to a pilot control module, whereby the manipulated variables for each segment are pump-synchronized and in particular cylinder-selective the high pressure pump and the pressure regulating valve are calculated in an output module and fed to the actuators of the high pressure pump and the pressure regulating valve for volume-based and, in particular, cylinder-selective setting of the rail pressure.

In the case of the non-cylinder-selective approach and the cylinder-selective approach, it is preferably provided that the manipulated variables of the actuators of the components for regulating the rail pressure in the fuel accumulator are fed to an output module and are calculated in the output module for the volume-based setting of the rail pressure, with current detection and Current control of the actuators is carried out on the basis of an observer model.

In the case of the non-cylinder-selective procedure, it is preferably provided that the volume-related discrete volume control difference is fed as an input variable to a control module for the high-pressure pump and a control module for a pressure control valve assigned to the fuel accumulator, the discrete volume control difference being linked to a pilot control module, whereby pump-synchronously per segment the manipulated variables for the high-pressure pump and the pressure control valve are calculated in an output module and fed to the actuators of the high-pressure pump and the pressure control valve for volume-based adjustment of the rail pressure.

In the case of the non-cylinder-selective approach, it is also provided that the discrete control deviation is calculated as the difference between the discretized actual rail pressure and the discretized target rail pressure by adding discretized pressure information from a rail pressure sensor of the actively detected pump-synchronous segment with the discretized target rail pressure of the is compared to a work cycle preceding the pump-synchronous segment in order to determine the discrete control difference.

In the other, cylinder-selective approach, which extends the basic concept, the volume-related discrete volume control difference is calculated cylinder-selectively by feeding the volume-related discrete volume control difference as cylinder-selective input variables to a control module for the high-pressure pump and a control module for a pressure control valve assigned to the fuel reservoir, the discrete volume -Control difference is linked to a pilot control module, whereby the manipulated variables for the high pressure pump and the pressure control valve are calculated in an output module for each segment in a pump-synchronized and cylinder-selective manner and fed to the actuators of the high-pressure pump and the pressure control valve for volume-based, cylinder-selective adjustment of the rail pressure.

In the case of the cylinder-selective procedure, it is preferably provided that the discrete control deviation is the difference between the discretized actual rail pressure and the discretized Target rail pressure is calculated cylinder-selectively by comparing discretized pressure information from a rail pressure sensor of the actively detected pump-synchronous segment with the discretized target rail pressure of the pump-synchronous segment preceding one work cycle in order to determine the discrete cylinder-selective control difference, as detailed in the description is explained.

According to the invention, the target rail pressure is discretized at a point in time that is established with a trigger start signal that is output repeatedly at the beginning of a pump-synchronous segment. Provision is made for the actual rail pressure within the segment started by the trigger start signal to be repeatedly recorded and discretized.

• in dem Segment maximaler Ist-Raildruck und
• in dem Segment minimaler Ist-Raildruck und
• in dem Segment berechneter Mittelwert

diskretisiert und wahlweise mit dem diskretisierten Soll-Raildruck zur Bestimmung der diskreten, insbesondere zylinderselektiven Regelabweichung verglichen wird.It is preferably provided that the actual rail pressure, which is recurring detected within the pump-synchronous segment, as

• in the segment maximum actual rail pressure and
• in the segment minimum actual rail pressure and
• mean calculated in the segment

is discretized and optionally compared with the discretized target rail pressure to determine the discrete, in particular cylinder-selective control deviation.

It is also preferred that for the regulation, in particular cylinder-selective regulation, the recorded minimum discrete pressure or the recorded maximum discrete pressure or the discrete mean value for comparison with the discrete target rail pressure is used as the actual value, with a pressure build-up depending on the system requirements the maximum discrete pressure and, in the event of a pressure reduction, the minimum discrete pressure is used in order to reduce control oscillations, in particular cylinder-selective control oscillations or to avoid overshoots or undershoots, in particular cylinder-selective overshoots or undershoots.

A special aspect of the invention also provides that the discrete control deviation is converted into the volume flow-based discrete volume control difference or volume flow-based discrete cylinder-selective volume control difference, with a permanent fuel leakage of the high-pressure system of the fuel supply system being taken into account by addition.

berücksichtigt, insbesondere zylinderselektiv berücksichtigt wird.The pressure-based discretized control deviation Δ _PRail or pressure-based discretized cylinder- _selective control deviation Δ _PRail is advantageously converted into a volume flow-based volume control difference ΔV _Rail or a volume flow-based one cylinder-selective volume control difference ΔV _Rail converted, with the conversion the pressure- and temperature-dependent specific modulus of elasticity E of the respective fuel and the volume V _{H of} the high-pressure fuel system of the fuel supply system according to the conversion formula $${\mathrm{\Delta V}}_{\mathrm{Rail}}=\frac{V_{\mathrm{H}}}{\mathrm{E.}\left(p,T\right)}\ast {\mathrm{\Delta p}}_{\mathrm{Rail}}$$

taken into account, in particular taken into account on a cylinder-specific basis.

1. a) die Kraftstoff-Einspritzmengen der Injektoren, insbesondere zylinderselektiv und
2. b) die Kraftstoff-Schaltleckagen der Injektoren, insbesondere zylinderselektiv und
3. c) ein Druckänderungswunsch bezüglich des Soll-Raildrucks des Kraftstoffspeichers, insbesondere zylinderselektiv berücksichtigt,
   wobei ferner
4. d) die Kraftstoff-Dauerleckage des Hochdrucksystems des Kraftstoffversorgungssystems durch eine pumpensynchrone segmentweise wiederkehrende separate Umrechnung mit einer Z-Transformation ermittelt und der volumenbezogenen diskreten Volumen-Regeldifferenz hinzugefügt wird, beziehungsweise bei zylinderselektiver Vorgehensweise, wird die Kraftstoff-Dauerleckage den volumenbezogenen diskreten zylinderselektiven Volumen-Regeldifferenzen anteilig hinzugefügt.

In the case of the pump-synchronous, segment-wise recurring conversion of the pressure-based discrete control deviation, in particular cylinder-selective control deviation into the volume-related discrete volume control difference, in particular cylinder-selective volume control deviation,

1. a) the fuel injection quantities of the injectors, in particular cylinder-selective and
2. b) the fuel switching leaks of the injectors, in particular cylinder-selective and
3. c) a pressure change request with regard to the target rail pressure of the fuel accumulator, in particular taken into account for each cylinder,
   furthermore
4. d) the permanent fuel leakage of the high pressure system of the fuel supply system is determined by a pump-synchronous, segment-wise recurring separate conversion with a Z-transformation and added to the volume-related discrete volume control difference, or in the case of a cylinder-selective approach, the fuel-permanent leakage becomes the volume-related discrete cylinder-selective volume control differences added proportionally.

Specific cylinder-selective approach:

According to the invention, it is provided that the injectors receive the same quantity target values from cylinder to cylinder in stationary operation, which are compared cylinder-selectively with the quantity decreases from the rail, with injection quantity errors being determined for each cylinder, which are assigned to the injectors, one type of quantity deviations being determined Is assigned to error groups. The injection quantity errors are grouped in an advantageous manner depending on the cause, in particular depending on the level of the injection quantity error resulting from the target / actual comparison, the injectors during operation of an error group with an injector defect, an error group with an age-related injector drift or an Error group can be assigned with a changing switching leakage quantity, the injection quantity errors being determined within the cylinder-selective control in the controller and advantageously corrected in the injection system and / or leading to an exchange of the respective injector (s).

A correction in the injection system can be made in various ways. In a preferred embodiment, the correction takes place by changing the injector control duration.

The non-cylinder-selective fuel supply system (basic concept) and the cylinder-selective fuel supply system (extension of the basic concept) differ in terms of the components, as will become clear below.

• einen Sollwertvorgabe-Baustein des Raildrucks und eine zugehörigen Sollwert-Diskretisierungs-Baustein und
• einen Istwert-Signalerfassungs-Baustein des Raildrucks und einen Istwert-Diskretisierungs-Baustein,
• sowie einen Regelfehler-Berechnungs-Baustein und
• einen Umrechnungs-Baustein umfasst, der aus einer druckbasierten diskretisieren Regeldifferenz eine Umrechnung in eine volumenstrombasierte Regeldifferenz vornimmt,
• wobei der Umrechnungs-Baustein mit einer Regler-Zustandsmaschine verknüpft ist, welche die diskrete Eingangsgröße für den Regler-Baustein der Hochdruckpumpe und die diskreten Eingangsgröße für den Regler-Baustein des Druckregelventils ausgibt,
• wobei die Regler-Bausteine mit einem Vorsteuer-Baustein verknüpft sind, wodurch mittels des Vorsteuer-Bausteins und der aufgeschalteten Regler-Bausteine pumpensynchron je Segment die Stellgrößen für die Hochdruckpumpe und das Druckregelventil einem Ausgabe-Baustein zugeführt und berechnet werden, und den Stellgliedern der Hochdruckpumpe und des Druckregelventils zur volumenbasierten Einstellung des Raildrucks zugeführt werden.

The fuel supply system associated with the method is set up to carry out the method, the basic concept of the fuel supply system (without cylinder-selective rail pressure control) for determining a discrete input variable for a controller module for the high-pressure pump and for determining a discrete input variable for a controller module for a dem Fuel accumulator associated pressure control valve includes the following additional modules,

• a setpoint specification module for the rail pressure and an associated setpoint discretization module and
• an actual value signal acquisition module for the rail pressure and an actual value discretization module,
• as well as a control error calculation module and
• includes a conversion module that converts a pressure-based discretized control difference into a volume flow-based control difference,
• the conversion module being linked to a controller state machine which outputs the discrete input variable for the controller module of the high-pressure pump and the discrete input variable for the controller module of the pressure control valve,
• The controller modules are linked to a pilot control module, whereby by means of the pilot control module and the connected controller modules, the manipulated variables for the high-pressure pump and the pressure control valve are fed to an output module and calculated for each segment, and the actuators of the high-pressure pump and the pressure control valve for volume-based adjustment of the rail pressure.

• einen Sollwertvorgabe-Baustein des Raildrucks und eine zugehörigen Sollwert-Diskretisierungs-Baustein und
• einen Istwert-Signalerfassungs-Baustein des Raildruck und einen Istwert-Diskretisierungs-Baustein,
• sowie einen Regelfehler-Berechnungs-Baustein und
• einen Umrechnungs-Baustein umfasst, der aus einer druckbasierten diskretisieren zylinderselektiven Regeldifferenz eine Umrechnung in eine volumenstrombasierte zylinderselektive Regeldifferenz vornimmt,
• wobei der Umrechnungs-Baustein mit einer Regler-Zustandsmaschine verknüpft ist, welche zylinderselektiv die diskrete Eingangsgröße dem jeweiligen Regler-Baustein der Hochdruckpumpe und zylinderselektiv die diskreten Eingangsgröße dem jeweiligen Regler-Baustein des Druckregelventils ausgibt,
• wobei die Regler-Bausteine jeweils zylinderselektiv mit einem Vorsteuer-Baustein verknüpft sind, wodurch mittels des Vorsteuer-Bausteins und der aufgeschalteten zylinderselektiven Regler-Bausteine pumpensynchron je Segment die Stellgrößen für die Hochdruckpumpe und das Druckregelventil einem Ausgabe-Baustein zugeführt und berechnet werden, und den Stellgliedern der Hochdruckpumpe und des Druckregelventils zur volumenbasierten zylinderselektiven Einstellung des Raildrucks zugeführt werden.

The fuel supply system associated with the method is set up as an extension of the basic concept, namely with cylinder-selective rail pressure control for carrying out the method, with the fuel supply system having a number of cylinder-selective controller modules for the high-pressure pump and determining a discrete input variable to determine the respective discrete input variable of the respective cylinder of the respective cylinder cylinder-selective multiple controller modules for a pressure control valve assigned to the fuel reservoir comprises the following additional modules,

• a setpoint specification module for the rail pressure and an associated setpoint discretization module and
• an actual value signal acquisition module for the rail pressure and an actual value discretization module,
• as well as a control error calculation module and
• a conversion module that converts a pressure-based, discretized, cylinder-selective control difference into a volume flow-based, cylinder-selective control difference,
• The conversion module is linked to a controller state machine, which outputs the discrete input variable to the respective controller module of the high-pressure pump on a cylinder-specific basis and the discrete input variable to the respective controller module of the pressure control valve on a cylinder-specific basis,
• wherein the controller modules are each cylinder-selectively linked with a pilot control module, whereby by means of the pilot control module and the connected cylinder-selective controller modules pump-synchronously per segment, the manipulated variables for the high pressure pump and the pressure control valve are fed to an output module and calculated, and the Actuators of the high-pressure pump and the pressure control valve for volume-based cylinder-selective adjustment of the rail pressure are supplied.

Yet another aspect of the invention is that the fuel supply system comprises an observer module which observes a signal processing chain for current detection and current regulation of the actuators of the fuel supply system, as is also detailed in the description.

The internal combustion engine is advantageously operated with any liquid fuel or fuel mixture, as a result of which the linearization of the conversion of pressure difference into volume flow difference can be adapted to the respective fuel by a physically different modulus of elasticity. As a result, the explained method and the design of the fuel supply system are not only suitable for diesel engines, which are designed in particular as common rail diesel engines, but also applicable and usable for gasoline engines that use a gasoline engine - externally ignited - combustion process.

Figur 1

eine schematische Darstellung eines Kraftstoffversorgungssystems, das mit einer volumenstrombasierten pumpensynchronen Regelstruktur, insbesondere volumenstrombasierten pumpensynchronen und zylinderselektiven Regelstruktur zur Raildruckregelung gemäß dem erfindungsgemäßen Verfahren betrieben wird;

Figur 2A

die volumenstrombasierte pumpensynchrone Regelstruktur zur Raildruckregelung, die in einem elektronischen Steuergerät mit einem Mikroprozessor abgelegt und zur Ausführung des erfindungsgemäßen Verfahrens eingerichtet ist;

Figur 2B

die volumenstrombasierte pumpensynchrone und zylinderselektive Regelstruktur zur Raildruckregelung, die in einem elektronischen Steuergerät mit einem Mikroprozessor abgelegt und zur Ausführung des erfindungsgemäßen Verfahrens eingerichtet ist;

Figur 3

die erfindungsgemäße volumenstrombasierte pumpensynchrone Regelstruktur zur Raildruckregelung gemäß Figur 2A oder die erfindungsgemäße volumenstrombasierte pumpensynchrone und zylinderselektive Regelstruktur zur Raildruckregelung gemäß Figur 2B mit Stromerfassung und Stromregelung der Stellglieder der Raildruckregelung weiter erfindungsgemäß auf der Basis eines Beobachter-Modells.

The invention is explained below with reference to the accompanying drawings. Show it:

Figure 1

a schematic representation of a fuel supply system which is operated with a volume flow-based pump-synchronous control structure, in particular volume-flow-based pump-synchronous and cylinder-selective control structure for rail pressure control according to the method according to the invention;

Figure 2A

the volume flow-based pump-synchronous control structure for rail pressure control, which is stored in an electronic control unit with a microprocessor and is set up to carry out the method according to the invention;

Figure 2B

the volume flow-based pump-synchronous and cylinder-selective control structure for rail pressure control, which is stored in an electronic control unit with a microprocessor and is set up to carry out the method according to the invention;

Figure 3

the inventive volume flow-based pump-synchronous control structure for rail pressure control according to FIG Figure 2A or the volume flow-based pump-synchronous and cylinder-selective control structure according to the invention for rail pressure control according to FIG Figure 2B with current detection and current regulation of the actuators of the rail pressure regulation further according to the invention on the basis of an observer model.

The Figure 1 FIG. 4 shows a fuel supply system 100 which is equipped with a volume flow-based, pump-synchronous, in particular cylinder-selective, rail pressure control according to FIGS Figure 2A and 2 B is operated.

A high-pressure pump 1 is supplied with fuel from a fuel tank 3 by a pre-feed pump 2 via a low-pressure line 2.1. A filter unit 5 is located in the low-pressure line 2.1 and a dual sensor 6, which measures pressure p6 and temperature T6 upstream of the high-pressure pump 1 in the low-pressure line 2.1, is arranged.

The high-pressure pump 1 pumps fuel via a high-pressure line 1.4 into a fuel reservoir, in particular into a fuel rail 4. The fuel rail 4 includes a rail pressure sensor 7, which detects the rail pressure p7 in the fuel rail 4.

The fuel rail 4 also includes a pressure regulating valve 8 which, within the method, diverts a predeterminable volume flow V8 into the low-pressure line 2.1 from the fuel rail 4 via a return line 8.2.1.

Between the fuel rail 4 and the injectors 9n; (n = 1, 2, 3 ...) 91, 92, 93, 94 the injector lines 4.9 are shown, via which the injectors 9n are supplied with fuel.

The injectors 9n have leakage lines which open into a common return line 9.3. The return line 9.3 opens into a high pressure pump return line 1.3 of the high pressure pump 1, which leads back to the fuel tank 3.

A control unit S1, in particular an engine control unit, is directly connected to the duo sensor 6, the high pressure pump 1, the pressure control valve 8, the rail pressure sensor 7 and the injectors 91, 92, 93, 94 and in the exemplary embodiment indirectly via control lines (without reference symbols) a control unit S2 is connected to the prefeed pump 2 designed as a low-pressure pump.

The Figure 2A shows the volume flow-based pump-synchronous control structure for rail pressure control in the basic concept, which is stored in an electronic control device, in particular control device S1, which is set up to carry out one of the methods presented above. The control device S1 and the control device S2 are operated via a computer program for executing the method, a machine-readable storage medium with the computer program recorded thereon being provided on the computer.

The volume flow-based pump-synchronous control structure for rail pressure control is based on the Figure 2A explained in detail below.

The basic idea of the method explained below for the future diesel engines, which are designed as common rail diesel engines, is that a required rail pressure of up to 2700 bar is generated with the high pressure pump 1 by a predeterminable volume flow in the rail 4.

In the case of a positive quantity balance, that is to say an increasing volume flow in rail 4, the pressure in rail 4 rises. The rail pressure sensor 7 gives the control loop consisting of a pilot control model, a controller and an actuator of the high pressure pump 1 the corresponding pressure information.

According to the invention, the input variable of the method for operating the fuel supply system 100 according to the invention is a specific volume flow which is supplied to the high pressure pump 1 or discharged through the pressure regulating valve 8.

The object of the invention is thus that the complete high-pressure regulation, i.e. the rail pressure high-pressure regulation within the rail 4 of the fuel supply system 100, from a time-based cyclical calculation of a rail pressure regulator for regulating the rail pressure in the rail 4 to a volume flow-based and pump-synchronous based on the engine segment of the internal combustion engine discrete calculation for rail pressure control (in a two-digit concept pressure control valve control and high pressure pump control) is converted.

To this end, it is necessary according to the invention to discretely describe the volume flows to be observed and the associated model of the control structure according to the invention.

For this purpose, the pressure information p7 _actual from the rail pressure sensor 7 of an engine-synchronous / pump-synchronous segment is compared with the target rail pressure p7 _{target of} the preceding engine-synchronous / pump-synchronous segment (one speaks of the delayed target rail pressure) in order to determine the discrete control deviation Δp7.

This pressure difference Δp7 is converted into a volume difference via the modulus of elasticity E of the fuel and via the fuel temperature T6 determined by means of the duo sensor 6 and processed as an input variable ΔV _Rail in a control system.

This volume difference ΔV _Rail is calculated with the aid of the digital metering unit (not shown), which is preferably arranged in the pump chamber of the high-pressure pump 1, or by controlling the Pressure regulating valve 8 is supplied as an input variable to the controlled system and the actuators of high pressure pump 1 or pressure regulating valve 8 are activated, whereby the discretization, i.e. the calculation of the volume difference ΔV _Rail for each motor segment can be varied pump-synchronously.

For this purpose, a volume balance is created that physically describes the pressure p7 _{actual that is set} in rail 4.

The volume balance of the volume flow-based segment-synchronous calculation is based on a volume-constant room volume V _{H of} the high-pressure system in which there is a certain volume of fuel, depending on the pressure, which is basically supplied via the high-pressure pump 1 and discharged via the pressure control valve 1.

The space volume V _{H of} the high pressure system of the fuel supply system 100 comprises the space volume of the rail 4, the space volume of the injector lines 4.9 to the injectors 9n, the space volume in the injectors 9n up to the throttle point within the injectors 9n, the feed line 1.4 of the high pressure pump 1 to the rail 4 the check valve in the feed line 4.9 and the dead volume of the high pressure pump 1 (dead volume = volume between TDC of the piston of the high pressure pump 1 and the check valve in the feed line to the rail 4).

1. a) aus den Kraftstoff-Einspritzmengen V_9n über die Injektoren 91, 92, 93, 94 und
2. b) den Kraftstoff-Schaltleckagen V_SLeck der Injektoren 91, 92, 93, 94 sowie der
3. c) der Kraftstoff-Dauerleckage V_DLeck des Hochdrucksystems des Kraftstoffversorgungssystems 100

zusammensetzt.Starting from the spatial volume V _{H of} the high-pressure system of the fuel supply system 100, a total volume V _{Ges-Ab is} taken from the high-pressure system in a segment-synchronous manner, which is a total

1. a) from the fuel injection _quantities V _9n via the injectors 91, 92, 93, 94 and
2. b) the fuel switching _leaks V _{SLeck of} the injectors 91, 92, 93, 94 and the
3. c) the permanent fuel leakage V _{DLeck of} the high pressure system of the fuel supply system 100

composed.

The volumes a) and b) are taken on an event-related basis, while c) the permanent fuel leakage V _{DLeck of} the high-pressure system is discretized via a Z transformation. This means that the non-event-related permanent leakage V _{DLeck of} the high-pressure system is converted into an event-related, segment-synchronous discrete volume. In other words, there is an event-related discretization of the permanent leakage V _{DLeck of} the high pressure system, so that the volumes a), b), c) can be added accordingly as taken from the high pressure system as the total volume V _{Ges-Ab taken} .

Added to this is d) the so-called load and / or speed-dependent change request for the rail pressure, the so-called pressure change request (also referred to as the dynamic volume flow component) within the rail 4, which is generated by the supply of fuel volume (pressure increase) via the high-pressure pump 1 as a V _{Δp rail specification} or by discharging fuel volume (pressure reduction) via the pressure control valve 8 within the volume balance as a V _{Δp-rail specification} .

• bei einer Druckerhöhung ein segmentsynchrones Volumen V_Zu zu dem Gesamt-Volumen V_Ges-Ab addiert oder
• bei einer Druckabsenkung wird ein segmentsynchrones Volumen V_Ges-Ab von dem Gesamt-Volumen V_Ges-Ab subtrahiert

Depending on whether the pressure change request concerns an increase or decrease in pressure,

• in the event of a pressure increase, a segment-synchronous volume V _{zu is added} to the total volume V _Ges-Ab or
• at a pressure drop a synchronous segment V _{Total volume-Ab} from the total volume V _{Total Ab} is subtracted

The high-pressure pump 1 has, in a known manner and advantageously, a fixed assignment of the pump TDC segment synchronous / cylinder synchronous every 180 ° crank angle of the internal combustion engine to the cylinder piston TDCs of the cylinder pistons (not shown) of the internal combustion engine, the engine speed corresponding to the high pressure pump speed. A certain fixed offset can exist between the pump TDC and the cylinder piston TDC, but this is known and can be taken into account accordingly in the fixed assignment.

This fixed assignment enables the volume flow-based and pump-synchronous discrete calculation for rail pressure control to be based and discretized on this synchronicity. This means that only a discrete subset is obtained from a continuous amount of data or information, which simplifies the calculation of the variables within the controlled system.

The calculation according to the invention takes place via a trigger start signal nsync (cf. Figures 2A and 2 B and Figure 3 ), the calculation being segment-synchronous / cylinder-synchronous every 180 ° crank angle, with the calculation of the sizes of the controlled system for each of the cylinders or the associated injectors 9n which inject into this cylinder being carried out separately.

According to the Figure 2A The volume flow-based pump-synchronous control structure for regulating the rail pressure of the high-pressure pump 1 comprises a signal acquisition module B1 for signal acquisition of the rail pressure p7 by means of the rail pressure sensor 7.

According to the invention, the detection of the rail pressure p7 takes place synchronously within the module B1 for the signal detection of the rail pressure p7 in a measurement grid in ms steps, with an actual value being discrete segment-synchronously within the segment within the module B2, which is called the actual value discretization module p7 _Isl as the minimum pressure p _{7 is-min} and a maximum pressure p _{7 is-max} detected and stored, wherein from these pressures p _{7 is-min,} p _7lst-max also as an actual value p7 _lsl an average p7 _{actual 50%} of the Press P _7Ist-min , p _{7lst-max is} calculated within the segment and also saved.

According to the Figure 2A The volume flow-based pump-synchronous control structure for the rail pressure control of the high-pressure pump 1 includes a setpoint specification module A1 for the setpoint specification of the rail pressure p7 _Soll, which is stored in the form of map data in the computer program of the engine control unit, which stems from the respective combustion process applied and is specified.

According to the invention, this target rail pressure p7 _target is also discretized by any current default time grid, that is, a conversion takes place from the time "slice" to the segment "slice" at time nsync (trigger start signal), ie at the start of the calculation .

This explicitly means that the first value present in the segment disk is "frozen" and thus discretized within the time pattern as the target rail pressure p7 _target . This discretization takes place in the setpoint discretization module A2.

Because target rail pressure p7 _{target is} "frozen" at the beginning of a time slice of the segment at time nsync, the target rail pressure p7 _target (end of previous segment = start of next segment at time nsync) is discretized before, and is discretized and compared with the pressure information p7 _actual from the rail pressure sensor 7 from the current, i.e. the following segment within a working cycle, whereby a discrete control deviation Δp7 per segment (segment-synchronous) can be determined. This procedure is necessary because the system always has a time delay. The control value of a pilot control generates an increase in volume flow into the rail after the pump has delivered. Therefore it becomes the Difference formation used setpoint p7 _Soll delayed by exactly one work _cycle and compared with the actual value p7 _{lsl of} the following work _cycle .

As explained above, the minimum pressure p _7min or the maximum jerk p _7max or the mean value p7 _50% are available as the discrete actual value p7 _lsl .

In an advantageous manner, there is the possibility within the control (selection of several discrete signals from the setpoint discretization module A2) for the control as the actual value p7 _Ist the minimum discrete pressure p _7act-min or the maximum discrete pressure p _7lst-max or to use the discrete mean value p7 _actual-50% in order to compare the selected value with the discrete target rail pressure p7 _target , whereby, depending on the system requirements, the value p _{7lst-max is used} for a pressure _build-up and the value p7 _actual-min for a pressure _decrease to reduce control oscillations or to avoid overshoots or undershoots.

The corresponding pressure-related calculation is carried out in the control error calculation module A2 / B2 (cf. Figure 2A ) in which the discretized setpoint rail pressure values p7 _setpoint and the discretized actual rail pressure values p7 _lsl enter and are compared segment-synchronously and output and stored calculated as a control error.

At this point in the control error calculation, according to the invention, in a conversion module A2 ', B2' from the pressure-based discretized control deviation Δp7 = Δp _Rail, a conversion into a volume flow-based control difference ΔV _Rail , i.e. a volume flow difference with the resolution of a differential equation, is carried out, where E is is pressure- and temperature-dependent specific modulus of elasticity of the respective fuel and V _H , as explained above, the volume of space of the high-pressure fuel system of the fuel supply system 100. $${\mathrm{\Delta V}}_{\mathrm{Rail}}=\frac{V_{\mathrm{H}}}{\mathrm{E.}\left(p,T\right)}\ast {\mathrm{\Delta p}}_{\mathrm{Rail}}$$

This conversion into the segment-synchronous volume error ΔV _Rail has the advantage that the non-linear fuel properties of the fuel are taken into account in the control.

The non-linear properties of the fuel with regard to pressure and temperature and compressibility are not mapped in pressure-based systems The advantage of the present method is that these non-linearities are taken into account by converting them into the segment-synchronous volume error ΔV _Rail .

This enables precise control and regulation with the smallest control errors even in highly dynamic driving situations, which results in decisive advantages in terms of combustion stability and emissions.

As an interim summary, compared to the state of the art, there is a change in the detection of the variables through the segmentation in modules A1, B1 and the discretization in modules A2, B2 and a conversion of pressure-based variables to volume flow-based variables in modules A2 / B2 and A2 '/ B2' before.

As an input variable for a controller module C, C1, C8, a discrete volume control difference ΔV _Rail is available due to the features of the basic concept described, which is used directly for the volume flow-based actuators E1, E8 (high pressure pump 1 and pressure control valve 8).

The expansion of the basic concept, the "cylinder-selective control", will be discussed in detail below under the same subheading.

The controller module C, C1, C8 comprises, as a sub-module, a controller state machine C which, depending on the requirements, determines the pressure based on the volume flow / volume flow, i.e. depending on the discrete volume control difference ΔV determined in the conversion module A2 '/ B2' _Rail increases or decreases, and it decides whether a control intervention via a PID controller module C1 of high-pressure pump 1 (cf. Figure 2A ) "pressure increasing" or via a PID controller module C8 of the pressure control valve 8 "pressure decreasing".

The structure also includes according to Figure 2A a pre-control volume flow value module D as a fault controller for the segment-synchronous volume flow-based pre-control (reference variable with disturbance variable compensation) of the fuel supply system, the reference variable of which is merged with the PID controller module C1 of the high-pressure pump 1 and the PID controller module C8 of the pressure control valve 8, so that the PID controller modules C1, C8 only have to compensate for the control fluctuations of the fuel supply system.

The pre-control volume flow value module D is added as pilot control variables to the segment-synchronous volume flows mentioned under a) to d), so that the control system is already managed in the pre-control volume flow value module D.

The values of the fault controller of the precontrol volume flow value module D, which are regulated by the PID controller modules C1, C8 (see Fig Figure 2 ) to an output module E, which electrically controls the actuators E1 and E8 of the high pressure pump 1 and the pressure control valve 8 and adjusts the actuators E1 and E8 as required via the controlled system based on the pump segment and based on volume.

Extension "cylinder selective control":

According to the invention, the rail pressure control explained above with regard to the basic concept is expanded to a so-called "cylinder-selective control", as follows with reference to FIG Figure 2B is explained.

To do this, for each cylinder, n = number of cylinders or the associated injectors 9n (cf. Figure 1 ) a separate cylinder-selective control deviation ΔV _Rail , in particular a proportional component and / or an integrator component and / or a differential component, is calculated and, according to the cylinder-selective control deviation ΔV _Rail , the control values E1, E8 cylinder for cylinder or injector for injector 9n or Injection valve for injection valve selected segment-synchronously and, as explained above, output based on volume flow for high-pressure pump 1 or pressure control valve 8.

Since the injectors 9n receive the same quantity setpoints from cylinder to cylinder in stationary operation, but different quantity decreases V _9n result from the rail 4 due to injector _{scatter, according} to the invention, for example, the individual integrator components of the cylinder-selective controllers C1 _n , C8 _{n show} the quantity deviations between the injectors 9 _n , which can have various causes. Depending on the type of quantity discrepancy, the causes can be assigned to specific error groups with a high degree of probability.

According to Figure 2A a discrete volume control difference ΔV _Rail is available as an input variable for a controller module C, C1, C8 in the basic concept according to the invention, which is used directly for the volume flow-based actuators E1, E8 (high pressure pump 1 and pressure control valve 8), with segment-synchronous for every cylinder or injector 9n "only one" control structure is used repeatedly. On an extension, the so-called "cylinder-selective control", in which several control structures are cylinder-selective (cf. Figure 2B ) are used, is explained in more detail below.

Analogous to the basic concept, a segment-synchronous discrete volume control difference ΔV _Rail is available as an input variable for several (n) controller modules C1n, C8n, which according to the extension "cylinder-selective" directly for the volume flow-based actuators E1, E8 (high pressure pump 1 and pressure control valve 8 ) is used.

For each cylinder or injector 9n there are several controller modules C1n (n = 4 in the exemplary embodiment; C11, C12, C13, C14), C8n (n = 4; C81 in the exemplary embodiment) as sub-modules that are assigned to a controller state machine C , C82, C83, C84) are available which, depending on the segmental requirement, increase or decrease the pressure based on volume flow / volume flow, i.e. depending on the discrete volume control difference ΔV _Rail determined in the conversion module A2 '/ B2', whereby the controller State machine C decides whether the control interventions are segment-synchronized via several PID controller modules C1n of high-pressure pump 1 (cf. Figure 2B ) "pressure increasing" or via several PID controller modules C8n of the pressure control valve 8 "pressure lowering" in a cylinder-selective manner.

The structure also includes according to Figure 2B a pre-control volume flow value module D as a fault controller for the segment-synchronous volume flow-based pre-control (reference variable with disturbance variable compensation) of the fuel supply system 100, the reference variable of which is combined with the PID controller module C1n of the high-pressure pump 1 and the PID controller module C8n of the pressure control valve 8, so that the PID controller modules C1n, C8n only have to compensate for the control fluctuations of the fuel supply system.

This results in the following effects:

The high-pressure control can now - as an extension of the basic concept - be performed on a cylinder-specific basis by means of the cylinder-selective control, i.e. for each cylinder or each injection process an adapted, cylinder-specific corrected manipulated variable is output as actuator output E1 of high-pressure pump 1 or actuator output E8 of pressure regulating valve 8.

In other words, the respective PID controller modules C1n, C8n can each be evaluated separately and calibrated. The evaluation of the four individual PID controller modules C1n or C8n in the exemplary embodiment, i.e. the comparison of the integrator components and proportional components that are different in steady-state operation, for example, allows a cylinder-related or injector-related error analysis and cause grouping, on the one hand Simple diagnostic function (on-board diagnosis without expansion) or a diagnostic function (on-board diagnosis without expansion) with a correction function is provided.

For example, a specific cylinder-related or injector-related error can be permitted up to a predefinable threshold value via the diagnostic function, and a cylinder-related or injector-related error correction only takes place after the threshold value has been exceeded.

According to the invention, there is in particular the possibility of grouping the injection quantity errors depending on the cause, with the injectors 9n, for example, when operating an error group with an injector defect (on-board diagnosis of an injector defect without removal), or another error group with an age-related injector drift (on-board diagnosis of injector drift without removal ) or another error group with a changing switching _{leakage quantity} V _SLeck (on- _board diagnosis of a too high switching _leakage without removal), the injection _{quantity errors} advantageously calling for replacement of the defective injector 9n within the on-board diagnosis or within the cylinder-selective Regulation can be taken into account and corrected.

In addition, the cylinder-selective control information, that is to say the individual injection quantity errors of the individual injectors 9n, can generally be adapted and used to improve the pilot control D of the injectors 9n.

The respective cylinder-selective controlled variable C1n, C8n can also advantageously be converted into another reference variable, with particular consideration being given to the internal engine torque of the respective cylinder, so that a cylinder-selective torque-dependent control is made possible through the support of the cylinder-selective rail pressure control, in which the cylinder-selective control information in particular can be used for torque-cylinder equalization by, for example, transferring a corresponding pilot control value from the cylinder-selective rail pressure regulation to a cylinder-selective torque controller.

Extension "current measurement and current control of the actuators":

Another aspect of the invention is that the high-pressure control in the described non-cylinder-selective control or in the described cylinder-selective control outputs an adapted corrected manipulated variable in an actuator output E1 of the high-pressure pump 1 or in an actuator output E8 of the pressure control valve 8.

In order to be able to fully utilize the advantages according to the invention of the non-cylinder-selective control or the described cylinder-selective control without system weakness in the area of current detection and current control of the pressure control valve 8 and the high-pressure pump 1, a method for improved current control using an observer model for rail pressure control is described below a pressure control valve 8 and / or a high pressure pump 1 explained.

So far, current controls of components, especially high-pressure components in the automotive industry, have been implemented by pulse width modulation (PWM) of a fast switch in the engine control unit. The PWM modulation results in an average current in the actuator, which is measured for current regulation with an analog-to-digital converter (AD converter) in order to provide this to a controller as an actual variable. Due to the PWM modulation, the measured current contains frequencies / oscillations which correspond to a multiple of the PWM basic frequency. There are two established methods of measuring the current without errors.

A distinction is made between "PWM-synchronous current measurement systems" and "Time-synchronous current measurement systems".

PWM-synchronous current recording systems, in which a hardware filter with a high cut-off frequency is used to eliminate high-frequency interference, have the following disadvantages: A mean value-free acquisition cannot be performed. Sampling takes place in the frequency range of the HW filter with a high CPU load because the sampling frequency is coupled to the PWM base frequency. With small PWM duty cycles, aliasing errors can lead to undersampling, which leads to a shift in the mean value. The procedure is therefore rarely used.

Time-synchronous current acquisition systems in which a HW filter with a low cut-off frequency is used to smooth the PWM oscillation on the current signal have the following Disadvantages: Due to the low cutoff frequency and high filter time constant, these HW filters have a high phase shift. The controller must be adapted to a relatively slow HW filter. The time-synchronous current detection systems also show poor control behavior in the event of malfunctions, because the actual value reaches the controller with a delay due to the slow HW filtering.

In current recording systems, the voltage drop across the measuring resistor is used with the help of a measuring resistor to determine the current in the actuator. This value is recorded cyclically by means of an AD converter and made available to the current control as an actual value. This current measured value is regulated in a closed control loop. For sampling, this measured value must be filtered in front of the analog / digital converter using an analog hardware (HW) low-pass filter with a corresponding limit frequency (usually between 10 Hz and 50 Hz with time-synchronous current measurement). This filter is usually an RC element. As a result, a signal delay and a phase response are generated, which is a major disadvantage for the control loop, which is why the (internal) current controls are designed to be relatively slow.

As before, attention is paid to the fact that in this specific application "rail pressure control" in a regulator cascade of the rail pressure control, the inner control loops (control loops of the current regulator actuator) are generally designed to be faster than the outer control loops (control loops based on rail pressure) for a temporal decoupling to reach.

The actuators for the actuator output E1, E8 of the high pressure pump 1 and of the pressure control valve 8 of the high pressure control are the inner control loops, whereby the actual hydraulic pressure control already explained (compare the components of the hydraulic pressure control in the Figures 2A and 2 B and the associated description) represent the outer control loops.

After all this, it becomes clear that there is potential for improvement in the current detection and the current regulation of the pressure regulating valve 8 and the high pressure pump 1 based thereon, an improved procedure being explained below.

The solution according to the invention consists in a modified signal processing or signal processing chain, which according to the invention includes an in Figure 3 includes observer model shown.

In other words, an observer module W, called observer for short, is arranged integrated in the signal processing chain and is advantageously used in the signal processing chain to control components 1 and 8.

This observer W integrated in the signal processing chain improves the current detection of the high pressure pump 1 and the pressure control valve 8 and their current control in the described non-cylinder-selective rail pressure control and in the cylinder-selective rail pressure control.

The current detection is improved by means of the observer model in such a way that the delay times and phase shifts of the current detection, which are caused by the analog filtering (HW filter) of the signal, are circumvented, with the model ensuring that the observer W is constantly tracked by converging a so-called observation error to zero, the observation error being defined as the difference between the measured value and the observed value.

The current detection system according to the invention is shown in Figure 3 arranged in the output module component E and in Figure 3 in a schematically illustrated system diagram extracted from the output module component E.

The system according to the invention for current detection is based on time-synchronous current detection and a so-called state reconstruction or state vector construction.

The system diagram extracted from output module component E illustrates a voltage value u (which corresponds to a pulsating coil current or a pulsating coil voltage of a conventional PWM-synchronous current measurement), which represents the input variable of the system for current measurement.

der Steuereinheit der anzusteuernden Komponenten 1, 8 zugeführt wird.The voltage u represents the input variable that of the coil $\frac{1}{\mathit{Ls}+\mathrm{R.}}$

the control unit of the components 1, 8 to be controlled is supplied.

ist ein Stromwert i_1, der als sogenannter Effektivwert der Spule $\frac{1}{\mathit{Ls}+R}$

als Regelstrom zur Ansteuerung der Komponente 1, 8 gesucht wird, der messtechnisch nicht ohne entsprechende Aufbereitung des Signales erfasst werden kann.The output of the coil $\frac{1}{\mathit{Ls}+\mathrm{R.}}$

is a current value i _1, known as the effective value of the coil $\frac{1}{\mathit{Ls}+\mathrm{R.}}$

is sought as a control current for controlling the components 1, 8, which cannot be measured by measurement without appropriate processing of the signal.

stellt die Eingangsgröße für einen Hardware-Filter HW zur Filterung des Stromwertes i₁ darstellt, der wiederum den Stromwert i₂ ausgibt, der schließlich die Eingangsgröße für einen Software-Filter SW zur Dämpfung des Signals des Stromwertes i₂ im Steuergerät darstellt, sodass nach dieser Signalverarbeitungskette ein Signal eines Stromwertes i₃ zur Verfügung steht.The current value i ₁ or the effective value of the coil $\frac{1}{\mathit{Ls}+\mathrm{R.}}$

represents the input variable for a hardware filter HW for filtering the current value i ₁ , which in turn outputs the current value i ₂ , which finally represents the input variable for a software filter SW for damping the signal of the current value i ₂ in the control unit, so that after this Signal processing chain a signal of a current value i ₃ is available.

The voltage value u thus represents the input value into the observer module W, the current value i _{3 representing} the output value of the signal processing chain, which is also made available to the observer module W, the observer module W via the underlying observer Model calculates a new voltage value u in parallel to the signal processing chain explained above.

That is, the observer W is continuously tracked in that the so-called observation error converges to zero, the observation error being defined as the difference between the measured value i1 and the observed value i3.

This solution according to the invention enables a high performance and stability of the current detection corresponding to the requirements, whereby the inner current control loops with high performance are to be understood in detail as the following advantageous properties of the current detection according to the invention by means of observer W: This type of current detection has only a slight phase shift there on the The model value of the observer is regulated, which corresponds to the real current value which, however, due to the disadvantages of the phase response of the filtering, would only be recorded after the filter run time. The acquisition with observer is faster, so that ultimately the control based on it is also faster. The current detection according to the invention does not require averaging, that is to say it is more accurate in particular in contrast to the PWM-synchronous current detection (with averaging) that is used on all sides. In the current detection according to the invention, no aliasing effects occur, that is to say incorrect signal determination with undersampling, as is the case with other current detection methods, does not occur.

List of reference symbols

100

Kraftstoffversorgungssystem

1

Hochdruckpumpe

2

Vorförderpumpe

3

Kraftstofftank

4

Kraftstoffspeicher, Rail

ΔV_Rail

Volumen-Regeldifferenz, diskrete Regelabweichung

5

Filtereinheit

6

Duo-Sensor (p, T)

T6

Kraftstofftemperatur

7

Raildruck-Sensor

p7

Raildruck

p7_lsl

Ist-Raildruck

p_7lst-max

Ist-Raildruck (diskretisiert Max)

p7_Ist-min

Ist-Raildruck (diskretisiert Min)

p7_lst-50%

Ist-Raildruck (diskretisiert Mittelwert)

p7_Soll

Soll-Raildruck (diskretisiert)

Δp7 = Δ_PRail

diskrete Regelabweichung (druckbezogen)

E

Elastizitätsmodul

8

Druckregelventil

V8

abgesteuerter Volumenstrom über Rücklaufleitung 8.2.1

9n

Injektoren (n-ter Injektor)

91

erster Injektor

92

zweiter Injektor

93

dritter Injektor

94

vierter Injektor

1.4

Hochdruckleitung zwischen 1 und 4

2.1

Niederdruckleitung zwischen 2 und 1

4.9

Injektorleitungen zwischen 4 und 9n

8.2.1

Rücklaufleitung zwischen 8 und 2.1

9.3

Leckagerücklaufleitung zwischen 9n und 3

1.3

HDP-Rücklaufleitung zwischen 1 und 3

S1

erstes Steuergerät

S2

zweites Steuergerät

V_Ges  Gesamt-Volumen (V_9n + \/_DLeck V_SLeck+ V_{Δp-Rail-Vorgabe})
V_9n  Einspritzvolumen des jeweiligen n-ten Injektors 9n
V_DLeck  Dauerleckagevolumenstrom des Hochdruck-Kraftstoffversorgungssystems
V_SLeck  Schaltleckagevolumenstrom der Injektoren 9n
V_{Δp-Rail-Vorgabe}  Druckänderungswunsch systembedingt
V_ZU  zugeführtes Volumen in Abhängigkeit des Druckänderungswunsches Druckerhöhung
V_Ges-Ab  abgeführtes Volumen in Abhängigkeit des Druckänderungswunsches Druckabsenkung
V_H  konstantes Raumvolumen des Hochdruck-Kraftstoffversorgungssystems
nsync  Startzeitpunkt der Berechnung
A1  Sollwertvorgabe-Baustein des Raildrucks p7_Soll
A2  Sollwert-Diskretisierungs-Baustein
B1  Istwert-Signalerfassungs-Baustein Raildruck p7_lsl
B2  Istwert-Diskretisierungs-Baustein
A2/B2  Regelfehler-Berechnungs-Baustein
A2'/B2'  Umrechnungs-Baustein
C  Regler-Zustandsmaschine
C1  Regel-Baustein der Hochdruckpumpe
C8  Regel-Baustein des Druckregelventils
C1n  Regel-Baustein der Hochdruckpumpe (n-ter Regel-Baustein)
C8n  Regel-Baustein des Druckregelventils (n-ter Regel-Baustein
D  Vorsteuer-Baustein
E  Ausgabe-Baustein
E1  Stellgliedausgabe Hochdruckpumpe
E8  Stellgliedausgabe Druckregelventil
$\frac{\mathbf{1}}{\mathbf{Ls}+\mathbf{R}}$

  Spule
u  Spulenspannung
i1  Spulenstrom hinter der Spule
HW  Hardware-Filter
i2  Spulenstrom nach Hardware-Filter
SW  Software-Filter
i3  Spulenstrom nach Software-Filter
W  Beobachter-Baustein

100

Fuel supply system

1

high pressure pump

2

Feed pump

3

Fuel tank

4th

Fuel storage, rail

ΔV _rail

Volume control difference, discrete control deviation

5

Filter unit

6th

Duo sensor (p, T)

T6

Fuel temperature

7th

Rail pressure sensor

p7

Rail pressure

p7 _lsl

Actual rail pressure

p _7lst-max

Actual rail pressure (discretized max)

p7 _{actual min}

Actual rail pressure (discretized Min)

p7 _actual-50%

Actual rail pressure (discretized mean value)

p7 _target

Target rail pressure (discretized)

Δp7 = Δ _PRail

discrete control deviation (pressure-related)

E.

modulus of elasticity

8th

Pressure control valve

V8

controlled volume flow via return line 8.2.1

9n

Injectors (n-th injector)

91

first injector

92

second injector

93

third injector

94

fourth injector

1.4

High pressure line between 1 and 4

2.1

Low pressure line between 2 and 1

4.9

Injector lines between 4 and 9n

8.2.1

Return line between 8 and 2.1

9.3

Leak return line between 9n and 3

1.3

HDP return line between 1 and 3

S1

first control unit

S2

second control unit

V _Total Total Volume (V _9n + \ / _{DLeck SLeck} V ₊ V _{Dp rail specification)}
V _9n injection _{volume of} the respective n-th injector 9n
V _{DLeck Continuous} leakage _volume flow of the high pressure fuel supply system
V _SLeck switching _{leakage volume flow} of injectors 9n
V _{Δp-rail specification} Pressure change request due to the system
V _ZU Volume supplied as a function of the pressure change request, pressure increase
V _Ges-Ab volume discharged depending on the pressure change desired pressure reduction
V _H constant volume of the high pressure fuel supply system
nsync Start time of the calculation
A1 Setpoint specification block for rail pressure p7 _setpoint
A2 Setpoint discretization module
B1 actual value signal acquisition module rail pressure p7 _lsl
B2 Actual value discretization module
A2 / B2 control error calculation module
A2 '/ B2' conversion module
C controller state machine
C1 control module of the high pressure pump
C8 control module of the pressure control valve
C1n control module of the high pressure pump (n-th control module)
C8n control module of the pressure control valve (n-th control module
D input control module
E output module
E1 actuator output high pressure pump
E8 Actuator output pressure control valve
$\frac{\mathbf{1}}{\mathbf{Ls}+\mathbf{R.}}$

Kitchen sink
u coil voltage
i1 coil current behind the coil
HW hardware filter
i2 coil current after hardware filter
SW software filter
i3 coil current after software filter
W observer block

Claims (17)

Method for regulating a rail pressure (p7 _setpoint ) for a fuel supply system (100) of an internal combustion engine caused by a high-pressure pump (1) in a fuel accumulator (4), wherein a crank angle-related or cam angle-related fixed angle difference of the internal combustion engine between a top dead center position of a cylinder piston of a Cylinder of the internal combustion engine and a top dead center position of the pump piston of the high-pressure pump (1) of the fuel supply system (100) is taken into account when metering the delivery volume of the high-pressure pump (1), with recurring pump-synchronous per segment, that of one revolution of a crankshaft and thus the movement of the pump piston of the high-pressure pump (1) corresponds from the top dead center position of the pump piston to the next top dead center position, a discretization of a control deviation (Δp ₇ ) of the rail pressure (p7) in the fuel accumulator (4) is made and the discrete control deviation ( Δp ₇ ) outgoing end a volume-related discrete volume control difference (ΔV _Rail ) is calculated, characterized in that the discrete control deviation (Δp ₇ ) as the difference between the discretized actual rail pressure (p7 _actual ) and the discretized target rail pressure (p7 _target ), in particular cylinder-selective is calculated by comparing discretized pressure information (p7 _actual ) from a rail pressure sensor (7) of the actively detected pump-synchronous segment with the discretized target rail pressure (p7 _{target) of} the previous pump-synchronous segment by one work cycle to determine the discrete control deviation (Δp7) , in particular to determine the discrete cylinder-selective control deviation (Δp ₇ ). Method according to Claim 1, characterized in that the discrete control deviation (Δp ₇ ) is _{calculated for each cylinder} as the difference between the discretized actual rail pressure (p7 _actual ) and the discretized setpoint rail pressure (p7 _setpoint) by adding discretized pressure information (p7 _actual ) of a rail pressure sensor (7) of the actively detected pump-synchronous segment is compared with the discretized target rail pressure (p7 _Soll ) of the pump-synchronous segment preceding by one work cycle in order to determine the discrete cylinder-selective control deviation (Δp ₇ ). Method according to claim 1 or 2, characterized in that the volume-related discrete volume control difference (ΔV _Rail ) as an input variable, in particular as Cylinder-selective input variable is fed to a control module (C1n) for the high-pressure pump (1) and a control module (C8n) for a pressure control valve (8) assigned to the fuel accumulator (4), the discrete volume control difference (ΔV _Rail ) with a pilot control module ( D) is linked, whereby pump-synchronously, in particular pump-synchronously and cylinder-selective for each segment, the manipulated variables for the high pressure pump (1) and the pressure control valve (8) are calculated in an output module (E8) and the actuators (E1, E8) of the high pressure pump (1) and the pressure control valve (8) for volume-based, in particular volume-based and cylinder-selective adjustment of the rail pressure (p7 _setpoint) . Method according to Claim 1 or 2, characterized in that the target rail pressure (p7 _{target) is} discretized at a point in time which is specified with a trigger start signal (nsync) which is output repeatedly at the beginning of a pump-synchronous segment. Method according to Claims 1 or 2 and 4, characterized in that the actual rail pressure (p7 _lst ) is repeatedly recorded and discretized within the segment started by the trigger start signal (nsync). Method according to Claim 5, characterized in that the actual rail pressure (p7 _Ist ), which is recurring within the pump-synchronous segment, is recorded as • in the segment maximum actual rail pressure (p7 _{actual max} ) and • in the segment minimum actual rail pressure (p7 _{actual min} ) and • Mean value calculated in the segment (p7 _{actual 50%} ) discretized and optionally compared with the discretized target rail pressure (p7 _target) to determine the discrete control deviation (Δp7), in particular the discrete cylinder-selective control deviation (Δp ₇ ). A method according to claim 6, characterized in that for the control as an actual value (p7 _lst) the detected minimum discrete pressure _(P7-min) or the detected maximum discrete pressure (p7 _lst-max) or the discrete mean _{(P7 -50%} ) is used to compare with the discrete target rail pressure (p7 _target ), whereby depending on the system requirements, the maximum discrete pressure (p7 _actual-max ) when pressure _{builds up} and the minimum discrete pressure (p7 _actual-min ) when pressure _decreases is used to reduce control oscillations, in particular control oscillations, for each cylinder or to avoid overshoots or undershoots, in particular overshoots or undershoots, for each cylinder. Method according to claim 6 or 7, characterized in that the discrete control deviation (Δp7), in particular the discrete cylinder-selective control deviation (Δp ₇ ) into the volume flow-based discrete volume control difference (ΔV ₇ = ΔV _Rail ), in particular the volume flow-based discrete cylinder-selective volume control difference ( AV _Rail ) is converted, with a permanent fuel leakage (V _DLeck ) of the high-pressure system of the fuel supply system being additionally taken into account. Method according to claim 1 or 2, characterized in that the pressure-based discretized control deviation (Δp7 = Δp _Rail ) is converted into a volume flow-based volume control difference (ΔV _Rail ), the pressure and temperature-dependent specific modulus of elasticity (E) of the respective Fuel and the volume (V _H ) of the high-pressure fuel system of the fuel supply system (100) according to the conversion formula ${\mathrm{\Delta V}}_{\mathrm{Rail}}=\frac{V_{\mathrm{H}}}{\mathrm{E.}\left(p,T\right)}\ast {\mathrm{\Delta p}}_{\mathrm{Rail}},$

is taken into account in particular for each cylinder. Method according to Claims 1 and 9, characterized in that in the case of the pump-synchronous, segment-wise recurring conversion of the pressure-based discrete control deviation (Δp ₇ ) into the volume-related discrete volume control difference (ΔV _Rail ), a) the fuel injection quantities (V _9n ) of the injectors (9n) and b) the fuel switching _leaks (V _SLeck ) of the injectors (9n) and c) a pressure change request (V _{Δp rail specification} ) with respect to the target rail pressure (p7 _{target) of} the fuel reservoir (4) are taken into account, with d) the permanent fuel leakage (V _DLeck ) of the high-pressure system of the fuel supply system (100) is determined by a pump-synchronous, segment-wise recurring separate conversion with a Z transformation and added to the volume-related discrete volume control difference (ΔV ₇ = ΔV _Rail ). Method according to Claims 2 and 9, characterized in that in the case of the pump-synchronous, segment-wise recurring conversion of the pressure-based discrete cylinder-selective control deviation (Δp ₇ ) into the volume-related discrete volume control difference (ΔV _Rail ), a) the fuel injection quantities (V _9n ) of the injectors (9n) and cylinder-selective b) the fuel switching _leaks (V _SLeck ) of the injectors (9n) and cylinder- _selective c) a pressure change request (V _{Δp-rail specification} ) with respect to the target rail pressure (p7 _{target) of} the fuel accumulator (4) is taken into account for each cylinder, with d) the permanent fuel leakage (V _DLeck ) of the high-pressure system of the fuel supply system (100) is determined by a pump-synchronous, segment-wise recurring separate conversion with a Z transformation and added to the volume-related discrete volume control difference (ΔV ₇ = ΔV _Rail ). Method according to Claim 11, characterized in that the injectors (9n) receive the same nominal volume values from cylinder to cylinder in steady-state operation, which are compared cylinder-selectively with the quantity decreases (V _9n ) from the rail (4), with injection quantity _errors being determined for each cylinder which are assigned to the injectors (9 _n ), a type of quantity discrepancy being assigned to specific error groups. The method according to claim 12, characterized in that the injection quantity errors are grouped depending on the cause, in particular depending on the level of the injection quantity error resulting in the target / actual comparison, the injectors (9n) in operation of an error group with an injector defect, an error group with an age-related injector _drift or an error group with a changing switching _{leakage quantity} (V _SLeck ), whereby the injection _{quantity errors} are determined within the cylinder- _selective control in the controller (C1 _n , C8 _n ) and corrected in the injection system and / or when the respective injector ( _s ) is replaced / Injectors (9n). Method according to Claim 1 or 2, characterized in that the manipulated variables of the actuators of the components (1, 8) for regulating the rail pressure (p7 _Soll ) in the fuel accumulator (4) are fed to an output module (E1, E8) and in the output - Module (E1, E8) for the volume-based setting of the rail pressure (p7 _target) can be calculated, with current detection and current control of the actuators (1, 8) being carried out on the basis of an observer model. Fuel supply system (100) set up to carry out the method according to at least one of claims 1 and 3 to 10, characterized in that the fuel supply system (100) for determining a • Discrete input variable for a controller module (C1) for the high pressure pump (1) and to determine a discrete input variable for a controller module (C8) for a pressure control valve (8) assigned to the fuel accumulator (4) comprises the following additional modules, • a setpoint specification module (A1) for the rail pressure (p7 _setpoint ) and an associated setpoint discretization module (A2) and • an actual value signal acquisition module (B1) of the rail pressure (p7 _actual ) and an actual value discretization module (B2), • as well as a control error calculation module (A2 / B2) and • comprises a conversion module (A2 '/ B2') which converts a pressure-based, discretized control deviation (Δp7 = Δp _Rail ) into a volume flow-based control difference (ΔV _Rail ), with • the conversion module (A2 '/ B2') is linked to a controller state machine (C), which contains the discrete input variable for the controller module (C1) of the high-pressure pump (1) and the discrete input variable for the controller module ( C8) of the pressure control valve (8) outputs, • where the controller modules (C1, C8) are linked to a pilot control module (D), whereby the control variables for the high pressure pump are pump-synchronously per segment by means of the pilot control module (D) and the connected controller modules (C1, C8) (1) and the pressure control valve (8) are fed to an output module (E8) and calculated, and fed to the actuators (E1, E8) of the high-pressure pump (1) and the pressure control valve (8) for volume-based adjustment of the rail pressure (p7 _target) will. Fuel supply system (100) set up to carry out the cylinder-selective method according to at least one of Claims 1 to 14, characterized in that the fuel supply system (100) • to determine the respective discrete input variable of the respective cylinder cylinder-selective several (n) controller modules (C1n) for the high pressure pump (1) and to determine the respective discrete input variable of the respective cylinder cylinder-selective several (n) controller modules (C8n) for one the pressure control valve (8) assigned to the fuel accumulator (4), and • a setpoint specification module (A1) for the rail pressure (p7 _setpoint) and an associated setpoint discretization module (A2) and • an actual value signal acquisition module (B1) of the rail pressure (p7 _actual ) and an actual value discretization module (B2), • as well as a control error calculation module (A2 / B2) and • comprises a conversion module (A2 '/ B2') which converts a pressure-based, discretized control deviation (Δp7 = Δp _Rail ) into a volume flow-based control difference (ΔV _Rail ), with • the conversion module (A2 '/ B2') is linked to a controller state machine (C) which assigns the discrete input variable to the respective controller module (C1n) of the high-pressure pump (1) and the discrete input variable to the respective cylinder-specific Controller module (C8n) of the pressure control valve (8) outputs, • where the controller modules (C1n, C8n) are each cylinder-selectively linked with a pilot control module (D), whereby the control variables are pump-synchronously per segment by means of the pilot control module (D) and the connected cylinder-selective controller modules (C1, C8) for the high pressure pump (1) and the pressure regulating valve (8) are fed to an output module (E8) and calculated, and the actuators (E1, E8) of the high pressure pump (1) and the pressure regulating valve (8) for volume-based, cylinder-selective adjustment of the rail pressure ( p7 _{target) are} supplied. Fuel supply system (100) according to Claim 15 or 16, characterized in that the fuel supply system (100) comprises an observer module (W) which has a signal processing chain ( $\frac{\mathrm{1}}{\mathrm{Ls}+\mathrm{R.}},$

HW, SW) for current detection and current control of the actuators (1, 8) of the fuel supply system (100) observed.

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