EP2494175B1 - Method for the control and regulation of an internal combustion engine - Google Patents

Abstract

Disclosed is a method for the control and regulation of an internal combustion engine (1), comprising an independent common rail system on the A-side and an independent common rail system on the B-side. During normal operation, the rail pressure (pCR(A), pCR(B)) is controlled in each common rail system via a low pressure-side suction throttle (4A, 4B) as the first pressure-adjusting element in a rail pressure control loop and, at the same time, the rail pressure (pCR(A), pCR(B)) is subjected to a rail pressure disturbance variable via a high pressure-side pressure control valve (11A, 11B) as a second pressure-adjusting element, by means of which a pressure control valve volume flow is redirected via the high pressure-side pressure control valve (11A, 11B) from the rail (6A, 6B) into a fuel tank (2). The method is characterized in that a first emergency operation is implemented for the common rail system in question when a defective rail pressure sensor (8A, 8B) and a non-defective pressure control valve (11A, 11B) have been detected in said common rail system, while a second emergency operation is implemented for the common rail system in question when a defective rail pressure sensor (8A, 8B) and simultaneously a defective pressure control valve (11A, 11B) have been detected in said common rail system, and wherein the normal operation is implemented for the other, non-defective common rail system.

Description

The invention relates to a method for controlling and regulating an internal combustion engine with a separate A-side and an independent B-side common rail system, in which in normal operation in each common rail system of the rail pressure via a low-pressure suction throttle as the first pressure actuator in a rail pressure control loop is regulated and at the same time the rail pressure is acted upon via a high-pressure side pressure control valve as a second pressure actuator with a rail pressure disturbance by a pressure control valve volume flow is removed from the rail into a fuel tank via the high-pressure side pressure control valve.

In an internal combustion engine with common rail system, the quality of the combustion is largely determined by the pressure level in the rail. In order to comply with the statutory emission limit values, the rail pressure is therefore regulated. Typically, a rail pressure control loop comprises a reference junction for determining a control deviation, a pressure regulator for calculating a control signal, the controlled system and a software filter in the feedback branch for calculating the actual rail pressure from the raw values of the rail pressure. The control deviation is calculated from the target rail pressure to the actual rail pressure. The controlled system comprises the pressure actuator, the rail and the injectors for injecting the fuel into the combustion chambers of the internal combustion engine. For example, shows the DE 103 30 466 B3 a corresponding common rail system, wherein the pressure regulator accesses via the actuating signal to a suction throttle arranged on the low pressure side. In turn, the inlet cross-section to the high-pressure pump and thus the delivered fuel volume are determined via the suction throttle.

From the not pre-published DE 10 2009 031 527.6 is also a common rail system with pressure control of the rail pressure via a low-pressure side suction throttle known as a first pressure actuator. In addition, with this common rail system one high-pressure side pressure control valve provided as a second pressure actuator, via which a pressure control valve volume flow is removed from the rail in the fuel tank. By controlling the pressure control valve, a constant leakage with, for example, 2 liters / minute in the low load range is simulated. In the normal operating range, however, no fuel is removed from the rail. The pressure regulating valve volumetric flow is determined on the basis of a nominal volumetric flow with a static and a dynamic component. When calculating the dynamic component and when calculating the control signal for the rail pressure control loop, the actual rail pressure is the relevant input variable. A defective rail pressure sensor or an error in the signal detection of the rail pressure causes a wrong actual rail pressure and causes a faulty control of both the suction throttle as the first pressure actuator and the pressure control valve as a second pressure actuator. An error protection in case of failure of the rail pressure sensor is not shown in the specified reference.

From the DE 10 2006 040 441 B3 is a common rail system with pressure control is known in which a passive pressure relief valve is provided as a protective measure against too high a rail pressure, for example after a cable break in the power supply to the suction throttle. If the rail pressure exceeds a critical value, for example 2400 bar, the pressure relief valve opens. The fuel is then discharged from the rail into the fuel tank via the opened pressure relief valve. When the pressure relief valve is open in the rail, a pressure level, which depends on the injection quantity and the engine speed. At idle, this pressure level is about 900 bar, while at full load it is about 700 bar.

From the DE 10 2007 034 317 A1 is an internal combustion engine with a standalone A-side and a standalone B-side common rail system known which are identical. The two common rail systems are hydraulically decoupled from each other and therefore allow independent control of the A-side and B-side rail pressure. The separate control reduces pressure fluctuations in the rails. Correct rail pressure control requires a faultless rail pressure sensor. The failure of a rail pressure sensor or both rail pressure sensors caused in the specified system an undefined state of the pressure control and can cause a critical condition of the internal combustion engine, since no Fehlerabsicherung is shown.

The invention is therefore based on the object in an internal combustion engine with a separate A-side and an independent B-side common rail system together with passive pressure relief valve and pressure control valve to make the control of the rail pressure safer.

This object is achieved by a method for controlling and regulating an internal combustion engine with the features of claim 1. The embodiments are shown in the subclaims.

If, for example, a defective A-side rail pressure sensor and a non-defective pressure control valve were detected in the A-side common rail system, then a first emergency operation is set for the A-side common rail system, while the error-free B-side common rail system continues to be used normal operation remains set. In the first emergency operation, the A-side pressure control valve and the A-side intake throttle are actuated as a function of the same default size in the A-side common rail system. If the rail pressure sensor and additionally the pressure control valve fail in the A-side common rail system, a second emergency operation is set for the A-side common rail system. In the second emergency operation, the suction throttle is then controlled in the A-side common rail system in such a way that the rail pressure increases successively until the response of the passive pressure relief valve. If the A-side common rail system is error-free and the errors occur in the B-side common rail system, the procedure is analogous.

To improve the smoothness in the second emergency operation, the invention provides in one embodiment that is set by setting the second emergency operation for the A-side common rail system, the target rail pressure of the error-free B-side common rail system to a constant emergency service rail pressure. If, on the other hand, the second emergency mode is set for the B-side common rail system, then the nominal rail pressure of the fault-free A-side common rail system is set to the emergency service rail pressure in an analogous manner.

In normal operation, the energization duration of the injectors is calculated via an injector map as a function of a desired injection quantity and the actual rail pressure. In this case, the actual rail pressure on the A side is switched as a function of the ignition sequence to the B-side actual rail pressure as the input variable of the injector map. Now becomes the first emergency operation for the A-side common rail system with error-free B-side common rail system is set, so instead of the A-side actual rail pressure, a target map rail pressure is used. By setting the first emergency operation for the B-side common rail system and the faultless A-side common rail system, instead of the B-side actual rail pressure, the target map rail pressure is used as the input. By setting the second emergency operation for the A-side common rail system, a rail pressure average is set as the input parameter for the injector map. The rail pressure mean value is set to, for example, 800 bar. This pressure value corresponds to the mean value of the pressure range which occurs when the passive pressure relief valve is open.

In the first emergency operation, the rail pressure can still be set with a sufficient approximation using the pressure control valve. Since in this case the energization duration of the injectors is calculated with high accuracy, the contribution of the affected rail to the engine power is, with insignificantly higher emission values, maximum. The pressure control valve thus allows redundancy in case of failure of the rail pressure sensor. In the second emergency operation can still be represented by Absteuem the fuel via the passive pressure relief valve stable engine operation. There is therefore a double redundancy.

Figur 1

ein Systemschaubild,

Figur 2

die Raildruck-Regelkreise,

Figur 3

den A-seitigen Raildruck-Regelkreis mit Steuerung des Druckregelventils,

Figur 4

die Raildruck-Regelkreise mit einem Injektorkennfeld,

Figur 5

eine erste Tabelle und

Figur 6

eine zweite Tabelle.

In the figures, a preferred embodiment is shown. Show it:

FIG. 1

a system diagram,

FIG. 2

the rail pressure control circuits,

FIG. 3

the A-side rail pressure control loop with control of the pressure control valve,

FIG. 4

the rail pressure control circuits with an injector map,

FIG. 5

a first table and

FIG. 6

a second table.

The FIG. 1 shows a system diagram of an electronically controlled internal combustion engine 1 in V-arrangement with a stand-alone common rail system on the A-side and a stand-alone common rail system on the B-side. The A-side and B-side common rail systems are identically constructed and hydraulically separated from each other. In the further description, the components of the A-side are at the reference numeral with the suffix A and the components of the B-side marked with the suffix B at the reference numerals.

The common rail system on the A side comprises as mechanical components a low-pressure pump 3A for conveying fuel from a fuel tank 2, a low-pressure side suction throttle 4A as a first pressure actuator for influencing the volume flow, a high-pressure pump 5A, a rail 6A and injectors 7A for injection of fuel in the combustion chambers of the internal combustion engine 1. Optionally, the common rail system can also be designed with einzuspeichern, then for example in the injector 7A a single memory is integrated as an additional buffer volume. As a protection against an inadmissibly high pressure level in the rail 6A, a passive pressure relief valve 9A is provided, which opens, for example, at a rail pressure of 2400 bar and absteuert the fuel from the rail 6A in the fuel tank 2 in the open state. The A-side common rail system is supplemented by an electrically controllable pressure control valve 11A, via which an adjustable volume flow is diverted into the tank. This volume flow will be referred to in the text as pressure control valve volume flow.

The internal combustion engine 1 is controlled via an electronic engine control unit 10 (ECU), which contains the usual components of a microcomputer system, for example a microprocessor, I / O components, buffers and memory components (EEPROM, RAM). In the memory modules relevant for the operation of the internal combustion engine 1 operating data in maps / curves are applied. About this calculates the electronic control unit 10 from the input variables, the output variables. In the FIG. 1 For example, an A-side rail pressure pCR (A), a B-side rail pressure pCR (B), and a size ON are shown as inputs to the electronic engine control unit 10. The A-side rail pressure pCR (A) is detected by an A-side rail pressure sensor 8A and the B-side rail pressure pCR (B) by a B-side rail pressure sensor 8B. The size ON is representative of the other input signals, for example for an engine speed or for a performance request of the operator. The illustrated outputs of the electronic engine control unit 10 are a PWM signal PWMSD (A) for driving the A-side intake throttle 4A, a power-determining signal ve (A) for driving the A-side injectors 7A, a PWM signal PWMSD (B) for driving the B-side suction throttle 4B, a power-determining signal ve (B) for driving the B-side injectors 7B, a PWM signal PWMDV (A) for driving the A-side pressure control valve 11A, a PWM signal PWMDV (B) for driving the B-side pressure regulating valve 11 B and a size OFF. The latter is representative of the other control signals for controlling the internal combustion engine 1, for example, a control signal for controlling an EGR valve. Characteristic feature of the illustrated embodiment is the independent control of the A-side rail pressure pCR (A) from the B-side rail pressure pCR (B).

The FIG. 2 FIG. 12 shows the A-side rail pressure control loop 12A for controlling the A-side rail pressure pCR (A) and the B-side rail pressure control loop 12B. The A-side rail pressure control loop and the B-side rail pressure control loop are constructed identically, so that the description of the A-side rail pressure control loop 12A also applies to the B-side rail pressure control loop.

The input values of the A-side rail pressure control circuit 12A are: a target rail pressure pSL, a target consumption VVb, a rail pressure disturbance VSTG (A), the engine speed nMOT, a signal NB1 (A), a signal NB2 (A) , an emergency operating current value iNB and a quantity E1. Size E1 comprises a basic PWM frequency, the battery voltage and the ohmic resistance of the intake throttle coil with supply line, which are included in the calculation of the PWM signal. The signal NB1 (A) corresponds to the first emergency operation, which is set at a defective A-side rail pressure sensor and non-defective A-side pressure control valve of the A-side common rail system. The signal NB2 (A) corresponds to the second emergency operation, which is set at a defective A-side rail pressure sensor and at the same time defective A-side pressure control valve of the A-side common rail system. The output of the A-side rail pressure control circuit 12A is the raw value of the A-side rail pressure pCR (A). The further description initially takes place for normal operation, in which the switches S1A and S2A are in the position 1.

From the raw values of the rail pressure pCR (A), the actual rail pressure pIST (A) is calculated by means of a filter 13A. Also from the raw values of the rail pressure pCR (A), a dynamic rail pressure pDYN (A) is calculated via a filter 18A, which is included in the calculation of the control variable of the pressure control valve. The filter 18A has a smaller one Phase delay as the filter 13A. At a summation point A, the actual rail pressure pIST (A) is compared with the desired rail pressure pSL, resulting in a control deviation ep (A). From the control deviation ep (A), a pressure regulator 14A calculates its manipulated variable, which corresponds to a regulator volume flow VR (A) with the physical unit liters / minute. For the regulator volume flow VR (A), the calculated nominal consumption VVb and the rail pressure disturbance VSTG (A) are added at a summation point B. The setpoint consumption VVb is calculated as a function of a desired injection quantity and the engine speed ( Fig. 3 ). The rail pressure disturbance VSTG (A) is zero during normal operation (VSTG (A) = 0 liters / minute). The result of the addition corresponds to an unlimited A-side target volume flow VSLu (A), which is the input of a function block 15A. In function block 15A a limitation and a pump characteristic are summarized. The limitation limits the unlimited volumetric flow VSLu (A) as a function of the engine speed nMOT and calculates an electric current iKL (A) via the pump characteristic. The pump characteristic is designed in such a way that a decreasing current iKL (A) is assigned to an increasing nominal volume flow. Since, in normal operation, the switch S2A is in the position 1, the set current iSL (A) corresponds to the current iKL (A) calculated via the function block 15A. The target current iSL (A) is an input of the calculation PWM signal 16A. By way of the calculation 16A, a PWM signal PWMSD (A) is calculated as a function of the desired current iSL (A), with which the solenoid of the A-side suction throttle is then driven. As a result, the path of the magnetic core is changed, whereby the flow rate of the A-side high-pressure pump is influenced freely. For safety reasons, the A-side suction throttle is normally open and is acted upon with increasing PWM value in the direction of the closed position. The A-side suction throttle, the A-side high-pressure pump and the A-side rail are combined in the unit 17A. The control of the A-side intake throttle can be subordinated to a current control loop, in which the Saugdrosselstrom is detected as a controlled variable. The A-side rail pressure pCR (A) generated by the high-pressure pump in the A-side rail is then detected via the A-side rail pressure sensor. This closes the A-side rail pressure control loop.

Will now a defective A-side rail pressure sensor ( Fig. 1 : 8A), a correct calculation of the control deviation ep (A) and the controller volumetric flow VR (A) is no longer possible. It is therefore set the first emergency operation for the A-side common rail system, if at the same time the A-side pressure control valve is not defective. The further explanation will be given together with the FIG. 5 in which the switch positions for the individual operating states are shown. In the first emergency operation NB1 (A) of the A-side common rail system, the switch S1A is reversed from the position 1 to the position 2, while the switch S2A remains unchanged in the position 1. In position 2 of the switch S1A, the pressure regulator 14A is no longer determinative. At the output of the switch S1A, either the value zero (0 liter / minute) or, optionally, as shown, the value of a leakage volume flow VLKG is applied. This is calculated via a leakage map 19 as a function of the desired injection quantity QSL and the engine speed nMOT. The desired injection quantity QSL, in turn, can either be calculated via a characteristic map as a function of the power requirement or corresponds to the manipulated variable of a speed controller. In the first emergency operation NB1 (A), the unlimited nominal volume flow VSLu (A) is calculated from the sum of the output value of the switch S1A, the target consumption VVb and the rail pressure disturbance variable VSTG (A). The latter is calculated in the first emergency operation. The more detailed explanation is in connection with the FIG. 3 ,

If a defective rail pressure sensor and at the same time a defective pressure control valve are detected in the A-side common rail system, the second emergency mode NB2 (A) is set. By setting the second emergency operation NB2 (A), the switch S1A assumes the position 1 and the switch S2A changes to the position 2. See also FIG. 5 , In position 2 of the switch S2A, the setpoint current iSL (A) corresponds to an emergency operating current value iNB. The emergency operating current value iNB is in this case selected so that it reliably opens the passive pressure limiting valve, here: the A-side pressure limiting valve (FIG. Fig. 1 : 9A) is coming. If the A-side intake throttle is actuated in negative logic as described above, a constant value, for example, iNB = 0 A, is output as the emergency operating current value. Since now the A-side intake throttle is fully opened, the A-side rail pressure pCR (A) increases successively until the A-side pressure relief valve responds. Opens the A-side pressure relief valve, so sets in the A-side rail a rail pressure pCR (A), which is dependent on the operating point of the internal combustion engine. At idle, for example, pCR (A) = 900 bar and at full load pCR (A) = 700 bar. On average, a rail pressure of 800 bar. This mean rail pressure is a very good approximation for emergency operation. However, an opening of the passive A-side pressure limiting valve can also be caused if the emergency operating current value iNB is set to a somewhat greater value, for example iNB = 0.4 A, is set. This has the advantage that the fuel is less strongly heated by Absteuem in the fuel tank by the larger fuel throttling.

If a defective rail pressure sensor and a non-defective pressure control valve are detected in the B-side common rail system, then the first emergency mode NB1 (B) is set for the B-side common rail system, ie the switch S1 B changes to position 2 With the B-side rail pressure sensor and the B-side pressure control valve simultaneously defective, the second emergency operation NB2 (B) for the B-side common rail system is then set by the switch S1B in the position 1 and the switch S2B in the position 2 is redirected. See also the FIG. 5 ,

In the FIG. 3 is shown as a block diagram of the A-side rail pressure control loop 12A with a controller 20A. Via the controller 20A, the A-side pressure regulating valve volume flow VDRV (A) is set. The controller for the B-side pressure regulating valve is identical to the controller 20A, so that the description for the controller 20A also applies to the control of the B-side pressure regulating valve. The inputs of the controller 20A are: the engine speed nMOT, the target injection amount QSL or a target torque MSL, the first emergency operation NB1 (A), the size E1 for the conversion of the PWM signal PWMDV (A), and a quantity E2. Under the size E2 of the target rail pressure pSL, the A-side actual rail pressure pIST (A) and the A-side dynamic rail pressure pDYN (A) are summarized. The desired injection quantity QSL is either calculated via a characteristic map as a function of the power requirement or corresponds to the manipulated variable of a speed controller. The physical unit of the target injection amount QSL is mm ³ / stroke. In a torque-based structure, the setpoint torque MSL is used instead of the set injection quantity QSL. The outputs of the controller 20A are the pressure control valve volume flow VDRV (A), the target consumption VVb, and the rail pressure disturbance VSTG (A). The target consumption VVb and the rail pressure disturbance VSTG (A) are input to the A-side rail pressure control circuit 12A.

The further description initially takes place for normal operation, in which the switches S3A, S4A and S5A are each in the position 1. See also the FIG. 5 , in which the switch positions for the operating states are shown. On the basis of the engine speed nMOT, the target injection quantity QSL and the size E2, a desired volume flow VSLDV (A) for the pressure regulating valve 11A is calculated via a calculation 21A. In the calculation 21A, the calculation of a static Volume flow, a dynamic volume flow, the addition of the two volume flows and the limitation in dependence on the A-side actual rail pressure pIST (A) summarized. Also based on the engine speed nMOT and the target injection quantity QSL is calculated via the calculation 26, the target consumption VVb, which is an input of the rail pressure control loop 12A. The desired volume flow VSLDV (A) of the pressure regulating valve is an input of a pressure regulating valve map 22A. The second input represents the A-side actual rail pressure pIST (A) because the switch S5A is in the 1 position. Depending on the two input variables, a desired current iSLDV (A) of the pressure regulating valve 11A is then calculated and converted into the duty cycle PWMDV (A) by means of a PWM calculation 23A, with which the pressure regulating valve 11A is actuated. The conversion can be subordinated to a current control, current control loop 25A with filter 24A, in which the controlled variable corresponds to the adjusting the pressure regulating valve 11A electrical current. The output signal of the pressure regulating valve 11A corresponds to the pressure regulating valve volume flow VDRV (A), that is to say the fuel volume flow which is diverted from the A-side rail into the fuel tank.

If now a defective A-side rail pressure sensor and a non-defective A-side pressure control valve is detected, the first emergency operation NB1 (A) is set for the A-side common rail system, whereby the switches S3A, S4A and S5A in the position Change 2. In position 2 of the switch S3A, instead of the set volume flow VSLDV (A), a setpoint emergency operating volume flow VSLNB is now an input variable of the pressure control valve characteristic map 22A. The target emergency operating volume flow VSLNB is calculated via an emergency operating characteristic map 27 as a function of the desired injection quantity QSL and the engine speed nMOT. The emergency operating map 27 is designed in such a way that a pressure regulating valve volume flow VDRV (A) greater than zero (VDRV (A)> 0 liter / minute) is diverted from the rail into the fuel tank over the entire operating range of the internal combustion engine. Under operating range of the internal combustion engine is the speed range between the starting speed (idle speed) to Abregeldrehzahl or between an idle torque and a maximum torque to understand. The setpoint emergency operating volume flow VSLNB is now also an input variable of the rail pressure control loop 12A, since the switch S4A assumes the position 2 and thus the rail pressure disturbance variable VSTG (A) corresponds to the setpoint emergency operating volume flow VSLNB (VSTG (A) = VSLNB). In other words: If the A-side rail pressure sensor is defective and the A-side pressure control valve is not defective, the setpoint emergency operating volume flow is VSLNB both the default size for the high pressure side arranged, A-side pressure control valve 11A and for the low pressure side arranged, A-side intake throttle in the rail pressure control loop 12A. The second input of the pressure control valve map 22A is now the target rail pressure pSL since the switch S5A is in the 2 position. The setpoint current iSLDV (A) for the pressure regulating valve is therefore calculated via the pressure regulating valve characteristic map 22A as a function of the setpoint rail pressure pSL and the set emergency operating volume flow VSLNB. The conversion into the pressure regulating valve volume flow VDRV (A) then takes place as described above.

If the second emergency mode NB2 (A) is set in the A-side common rail system, this has no effect on the switches S3A, S4A and S5A. These remain in position 2, see the FIG. 5 ,

The FIG. 4 shows in a block diagram the A-side rail pressure control loop 12A, the B-side rail pressure control loop 12B and an injector 28. For the sake of completeness, this calculation again shows the calculation 26, via which, depending on the target injection quantity QSL and the engine speed nMOT the target consumption VVb is calculated for the two rail pressure control loops. The input variables of the block diagram are the desired torque MSL, the engine speed nMOT, the target injection quantity QSL, the ignition sequence ZF, a pressure pA and a pressure pB. The output variables of the block diagram are the energization duration BD for controlling the injectors, the A-side rail pressure pCR (A) and the B-side rail pressure pCR (B). The further description is done together with the FIG. 6 , in which the different possibilities of error for the two rail pressure sensors and the two pressure control valves are shown.

First, the function of the block diagram in normal operation will be described, in which the switches S6A and S6B are in the position 1. In normal operation, the reference variable of the A-side rail pressure control loop 12A corresponds to the target rail pressure pSL. The command value of the B-side rail pressure control loop 12B also corresponds to the target rail pressure pSL. The desired rail pressure pSL, in turn, corresponds to the nominal map rail pressure pSLKF calculated via the map 29. The energization duration BD is calculated via the injector map 28. The first input is the target injection quantity QSL. The second input variable is the pressure pINJ, which in turn corresponds to the pressure pA or pB depending on the position of the switch S7. Switched is the Switch S7 via the ignition sequence ZF. In normal operation, the pressure pA corresponds to the A-side actual rail pressure pIST (A) and the pressure pB corresponds to the B-side actual rail pressure pIST (B). In the FIG. 6 this corresponds to the current number 1.

If a faulty A-side rail pressure sensor is detected with the A-side pressure control valve not defective, then the first emergency operation NB1 (A) is set for the A-side common rail system. In the first emergency operation NB1 (A) of the A-side common rail system, the pressure pA for the injector map 28 corresponds to the desired map rail pressure pSLKF. The pressure pB also corresponds to the B-side actual rail pressure pIST (B) when the B-side common rail system is faultless, that is, the B-side rail pressure sensor and the B-side pressure control valve are not defective. In the FIG. 6 this corresponds to the sequential number 2. The reverse case is in the FIG. 6 shown under the serial number 3. If the rail pressure sensor and at the same time the pressure control valve of the A-side common rail system are defective, then the second emergency operation NB2 (A) is set for the A-side common rail system. In the second emergency operation NB2 (A), the pressure pA for the injector map 28 is set to the rail pressure mean value pM, for example 800 bar. Since the B-side common rail system operates without errors, the pressure pB continues to correspond to the B-side actual rail pressure pIST (B). In the FIG. 6 this corresponds to the sequential number 7. If the A-side common rail system is in NB2 (A) in the second emergency mode, after opening the A-side pressure relief valve ( Fig. 1 : 9A) a rail pressure in the range of 700 bar to 900 bar. If the B-side common rail system is in normal operation, its rail pressure pCR (B) can be ≈ 2000 bar. The pressure difference between the two rails can cause torsional vibrations of the internal combustion engine. Therefore, it is provided in an option that the reference variable of the intact common rail system is switched to an emergency service rail pressure pNB, for example pNB = 1500 bar. For the case described above, therefore, the switch S6B is reversed to the position 2. See also the FIG. 5 in which switch S6B either maintains position 1 or changes to position 2 when the option is used.

If both common rail systems are in the second emergency mode, then the pressure pA and the pressure pB for the injector map 28 are set to the rail pressure mean value pM. This case is in the FIG. 6 shown as a serial number 16.

reference numeral

1

Internal combustion engine

2

Fuel tank

3A, B

Low pressure pump

4A, B

Suction choke, low pressure side

5A, B

high pressure pump

6A, B

Rail

7A, B

injector

8A, B

Rail pressure sensor

9A, B

Pressure relief valve, passive

10

electronic control unit (ECU)

11A, B

Pressure control valve, high pressure side

12A, B

Rail pressure control circuit

13A, B

filter

14A, B

pressure regulator

15A, B

function block

16A, B

Calculation PWM signal

17A, B

Unit (suction throttle, high-pressure pump and rail)

18A, B

filter

19

Leakage map

20A, B

control

21A, B

Calculation (set flow rate pressure control valve)

22A, B

Pressure control valve map

23A, B

Calculation PWM signal

24A, B

filter

25A, B

Current control circuit (pressure control valve)

26

Calculation (target consumption)

27

Notbetriebskennfeld

28

Injektorkennfeld

29

map

Claims (10)

1. Method for the control and regulation of an internal combustion engine (1), comprising an independent A-side common rail system and an independent B-side common rail system, in which method, during normal operation, the rail pressure (pCR(A), pCR(B)) is controlled in each common rail system by means of a low-pressure-side suction throttle (4A, 4B) as the first pressure-adjusting element in a rail pressure control loop (12A, 12B) and, at the same time, a rail pressure disturbance variable is applied to the rail pressure (pCR(A), pCR(B)) by means of a high-pressure-side pressure control valve (11A, 11B) as a second pressure-adjusting element by a pressure control valve volume flow (VDRV(A), VDRV(B)) being redirected by means of the high-pressure-side pressure control valve (11A, 11B) from the rail (6A, 6B) into a fuel tank (2), in which method first emergency operation (NB1(A), NB1(B)) is set for the common rail system in question when a defective rail pressure sensor (8A, 8B) and a non-defective pressure control valve (11A, 11B) are identified in this common rail system, a second emergency operation (NB2(A), NB2(B)) is set for the common rail system in question when a defective rail pressure sensor (8A, 8B) and at the same time a defective pressure control valve (11A, 11B) are identified in this common rail system, and in which method normal operation continues to be set for the other, non-defective common rail system.
2. Method according to Claim 1, characterized in that, during first emergency operation (NB1(A), NB1(B)), the high-pressure-side pressure control valve (11A, 11B) and the low-pressure-side suction throttle (4A, 4B) are driven as a function of the same prespecified variable in the common rail system in question.
3. Method according to Claim 2, characterized in that the prespecified variable corresponds to a setpoint emergency operation volume flow (VSLNB) which is calculated by means of an emergency operation characteristic diagram (27) as a function of a setpoint injection quantity (QSL) and the engine rotation speed (nMOT).
4. Method according to Claim 3, characterized in that the emergency operation characteristic diagram (27) is designed in the form that, over the entire operating range of the internal combustion engine (1), a pressure control valve volume flow (VDRV(A), VDRV(B)) is redirected from the rail (6A, 6B) into the fuel tank (2).
5. Method according to Claim 1, characterized in that, during second emergency operation (NB2(A), NB2(B)), the suction throttle (4A, 4B) is driven in the common rail system in question in such a way that the rail pressure (pCR(A), pCR(B)) is successively increased until a passive pressure-limiting valve (9A, 9B) responds.
6. Method according to Claim 5, characterized in that, when second emergency operation (NB2(A)) is set for the A-side common rail system, the setpoint rail pressure (pSL) of the non-defective B-side common rail system is set to an emergency operation rail pressure (pNB), or when second emergency operation (NB2(B)) is set for the B-side common rail system, the setpoint rail pressure (pSL) of the non-defective A-side common rail system is set to the emergency operation rail pressure (pNB).
7. Method according to one of the preceding claims, characterized in that, during normal operation, a changeover is made from the A-side actual rail pressure (pIST(A)), as a function of the ignition sequence (ZF), to the B-side actual rail pressure (pIST(B)) as an input variable for an injector characteristic diagram (28) for calculating a current-supply duration (BD) of the injector (7A, 7B), in that, when first emergency operation (NB1(A)) is set for the A-side common rail system and with a non-defective B-side common rail system instead of the A-side actual rail pressure (pIST(A)), a setpoint characteristic diagram rail pressure (pSLKF) is set as the input variable, and in that when first emergency operation (NB1(B)) is set for the B-side common rail system and with a non-defective A-side common rail system instead of the B-side actual rail pressure (pIST(B)), the setpoint characteristic diagram rail pressure (pSLKF) is set as an input variable.
8. Method according to Claim 7, characterized in that, when second emergency operation (NB2(A)) is set for the A-side common rail system, a rail pressure average value (pM) is set as the input variable for the injector characteristic diagram (28), and when second emergency operation (NB2(B)) is set for the B-side common rail system, the rail pressure average value (pM) is set as the input variable for the injector characteristic diagram (28).
9. Method according to Claims 7 and 8, characterized in that the second input variable of the injector characteristic diagram (28) corresponds to the setpoint injection quantity (QSL) which is calculated by means of a rotation speed controller as its actuating variable.
10. Method according to Claims 7 and 8, characterized in that the setpoint injection quantity (QSL) corresponds to an accelerator pedal position.

Images