CN108626014B - Common rail system and method for operating a common rail system - Google Patents

Common rail system and method for operating a common rail system Download PDF

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Publication number
CN108626014B
CN108626014B CN201810208429.8A CN201810208429A CN108626014B CN 108626014 B CN108626014 B CN 108626014B CN 201810208429 A CN201810208429 A CN 201810208429A CN 108626014 B CN108626014 B CN 108626014B
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pressure
control unit
common rail
rail pressure
fuel
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CN108626014A (en
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托尔斯滕·施诺尔布斯
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FEV Europe GmbH
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FEV Europe GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3836—Controlling the fuel pressure
    • F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D41/1402—Adaptive control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/141—Introducing closed-loop corrections characterised by the control or regulation method using a feed-forward control element
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1411—Introducing closed-loop corrections characterised by the control or regulation method using a finite or infinite state machine, automaton or state graph for controlling or modelling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/021—Engine temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0611—Fuel type, fuel composition or fuel quality
    • F02D2200/0612—Fuel type, fuel composition or fuel quality determined by estimation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/60—Input parameters for engine control said parameters being related to the driver demands or status
    • F02D2200/602—Pedal position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/31—Control of the fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The subject matter of the invention is a method for operating a common rail system of a combustion engine, wherein an input signal is supplied to a control unit of the common rail system and a control signal for a high-pressure pump of the common rail system is obtained by means of the control unit on the basis of a model stored in the control unit and the input signal. The control signal is supplied to the high-pressure pump such that the high-pressure pump is controlled to generate a nominal rail pressure in a fuel reservoir of the common rail system corresponding to the input signal. The actual rail pressure generated in the fuel accumulator is detected by a rail pressure sensor and compared to the setpoint rail pressure. A viscosity correction value is obtained from the deviation of the rail pressure obtained from the setpoint rail pressure, which is supplied to the control unit and adapted to the parameters for the viscosity of the fuel taken into account in the model in accordance therewith. By means of a model stored in the control unit, a corrected control signal for the high-pressure pump is obtained taking into account the viscosity correction value.

Description

Common rail system and method for operating a common rail system
Technical Field
The invention relates to a method for operating a common rail system of a combustion engine. The invention further relates to a common rail system.
Background
A method is known from DE 102012107596B 4, by which it should be possible to distinguish whether low-quality fuel is supplied to a high-pressure pump for fuel during operation of the high-pressure pump. For example, lubricity, compression modulus and viscosity are used as parameters for evaluating fuel quality. These parameters are obtained by means of a deviation of the actual pressure curve from the expected pressure curve in the compression chamber with respect to the lifting movement of the compression means of the high-pressure pump. In addition, variations in the leakage rate of the high-pressure pump can be obtained in order to determine the lubrication capacity, the compression modulus and the viscosity and therefore the quality of the fuel. When it is recognized that a low-quality fuel is supplied, a warning can be issued to the driver and/or the rail pressure, the control of the fuel injectors and/or the control of the high-pressure pump can be adapted.
From document DE 102013201500 a1 a method for adapting the rail pressure for a combustion engine with common rail injection is known, in which the viscosity of the injected fuel is obtained from the closing duration behavior (Schlie β daierverhalten) of the anchor of the injector of the injection system. The viscosity so obtained is taken into account in a first model, which depends on various operating parameters of the combustion engine or the injection system, to vary the rail pressure in correspondence with the obtained viscosity such that a desired nozzle flow is achieved at the injector. The injection start and/or injection end can vary depending on, inter alia, the viscosity obtained.
A method for regulating a common rail injector is known from DE 102014204098 a1, in which a sensor is used to measure the pressure in a valve chamber of the common rail injector. By means of the time profile of the pressure, for example, a characteristic of the fuel injected with the common rail injector, such as, for example, its viscosity, is obtained. Then, the switching characteristic of the switching valve or needle valve of the common rail injector is changed depending on the obtained characteristic so as to match the injection behavior.
Disclosure of Invention
The object of the present invention is to provide a method for operating a common rail system, which allows an optimized operating mode for the respective prevailing boundary conditions and at the same time allows a low cost. In addition, it is an object of the present invention to provide a common rail system which can be operated in an optimized manner under correspondingly prevailing boundary conditions without substantially increasing the design and/or control costs of the common rail system.
This object is achieved on the basis of the method according to the invention. In addition, this object is achieved by a common rail system according to the invention.
It is known according to the invention that deviations of the rail pressure prevailing in the fuel accumulator from the nominal rail pressure can be caused by: the viscosity of the fuel delivered by the high-pressure pump into the fuel reservoir does not correspond to its viscosity value stored in a model of the common rail system, which leads to an erroneous control of the high-pressure pump and thus to an actual rail pressure in the fuel reservoir deviating from the setpoint rail pressure. Instead of compensating for this deviation solely by pressure regulation (which has to be effected over a long period of time) in order to ensure the required subsequent regulation of the high-pressure pump, according to the invention a viscosity correction value is obtained from the deviation of the actual rail pressure from the setpoint rail pressure and is taken into account directly in the model, by means of which a control signal for the high-pressure pump is generated. The actual rail pressure in the fuel reservoir is obtained here with a rail pressure sensor which is already present anyway, by means of which an optimized method for operating the common rail system can be implemented without great expense.
In a method according to the invention for operating a common rail system of a combustion engine, an input signal is supplied to a control unit of the common rail system. It is not necessary here to be a single input signal. But a plurality of input signals may also be supplied to the control unit. In particular, information for driver inputs (such as the position of the driver's pedal) and/or boundary conditions in the operation of the combustion engine (such as the engine temperature and/or other control parameters) can be supplied to the control unit via the input signals.
On the basis of the input signal, a control signal for a high-pressure pump of the common rail system is generated by means of a control unit. For this purpose, a model is stored in the control unit, by means of which it can be ascertained how the high-pressure pump needs to be controlled in order to ensure that the common rail system operates as a function of the input signals. Various parameters can be introduced into the model. On the one hand, the information contained in the input signal is introduced therein as a variable. On the other hand, other parameters describing the common rail system may be introduced, such as, for example, the leakage rate of the common rail system, the relationship between the amount of fuel delivered by the high-pressure pump and the rail pressure in the fuel reservoir, etc. Such parameters describing the common rail system can, for example, have been obtained beforehand in a model-based or experimental characterization of the common rail system. In addition, parameters for the characteristic properties of the fuel supplied to the common rail system, such as the viscosity of the fuel, are taken into account in the model.
The control signal generated by the control unit is supplied to the high-pressure pump, so that the high-pressure pump is controlled to generate a nominal rail pressure in a fuel reservoir of the common rail system, which corresponds to the input signal. In other words, the high-pressure pump is controlled to deliver a certain amount of fuel into the fuel reservoir, as obtained by means of a model stored in the control unit on the basis of the input signal.
The rail pressure actually generated in the fuel reservoir is obtained by a rail pressure sensor. Here, according to the present invention, the viscosity correction value is obtained from the deviation of the rail pressure obtained with the rail pressure sensor from the rated rail pressure. The viscosity correction value gives the deviation of the viscosity value of the delivered fuel used in the model from the actual viscosity value of the fuel.
By supplying the viscosity correction value to the control unit and adapting the parameter for the fuel viscosity considered in the model to the obtained viscosity correction value, a corrected control signal for the high-pressure pump can be generated subsequently. In other words, the model on which the control signal for the high-pressure pump is obtained can be adapted continuously during operation of the common rail system in accordance with the actual viscosity of the fuel, as a result of which precise control of the high-pressure pump and thus precise setting of the rail pressure can be achieved. For example, external temperature variations that have an effect on the fuel viscosity can be taken into account. It is also possible to adapt the operation of the common rail system to fuel types having different compositions and therefore also different viscosity values.
In particular, deviations of the actual rail pressure from the setpoint rail pressure can therefore result in the leakage behavior of the common rail system differing from that employed according to the model due to the viscosity erroneously employed in the model. For example, a lower viscosity than that used in the model may result in an increased leakage rate in the pump and/or fuel injector of the common rail system. By correcting the viscosity value used in the model in correspondence with the obtained viscosity correction value, the changed leak rate can be taken into account by: a correspondingly modified control signal for the high-pressure pump is generated and supplied to the high-pressure pump.
According to a preferred embodiment of the method, the control unit generates a corrected control signal for the high-pressure pump, based on the stored model and taking into account the viscosity correction value. But also generates a modified control signal for controlling the starting point in time of the fuel injection, the duration of the fuel injection and/or the ending point in time of the fuel injection. The effect of the changed fuel viscosity on the injection behaviour can then also be compensated. For example, the duration of fuel injection may be shortened at a lower viscosity than initially employed in the model.
Short-term fluctuations in rail pressure prevailing in the fuel reservoir may also occur during operation of the common rail system, which are not necessarily caused by changes in the viscosity of the fuel. In accordance with an embodiment of the method, it is therefore provided that the viscosity correction value is supplied to the control unit only when the rail pressure obtained deviates in one direction from the setpoint rail pressure over a predetermined minimum time interval. Changes in viscosity (e.g., due to fuel temperature and/or subsequent replenishment of fuel having a different composition) result in an actual rail pressure that deviates from the rated rail pressure over time. That is, a long-term positive or negative deviation of the obtained rail pressure from the rated rail pressure is generated. By waiting for a predetermined minimum time interval and checking whether the deviation occurs constantly in one direction, it is then possible to know whether there is a systematic deviation due to a different viscosity than that used in the model.
In order to be able to make short-term corrections, in particular with regard to the rail pressure, the common rail system may have a regulator, by means of which a regulating signal is generated as a function of a deviation of the rail pressure obtained from a setpoint rail pressure. In addition to the control signal provided by the control unit, a regulating signal is also supplied to the high-pressure pump, whereby the fuel quantity delivered by the high-pressure pump and thus the rail pressure in the fuel reservoir can also be corrected for a short time without relying on an adaptation of the parameters used in the model. The correction of the rail pressure can then be effected, for example, only temporarily (duration less than a minimum time interval) when deviating from the setpoint rail pressure. If, however, the minimum time interval is exceeded, the correction of the deviation is alternatively or additionally carried out by supplying the viscosity correction value obtained to the control unit.
In addition to directly affecting the operation of the common rail system, changes in viscosity may also indirectly affect the characteristics of the common rail system. The result of, for example, a changed viscosity is also a change in the lubricating properties of the fuel. In order to be able to compensate for changes in the lubrication properties, it can be provided that the control unit generates a control signal for the lubricant system in dependence on the viscosity correction value supplied to the control unit in order to supply additional lubricant to the common rail system and thus to adjust the lubrication properties according to a predetermined desired value. The injection part can be protected against increased wear, for example, by supplying lubricant.
The input signal received by the control unit and dependent thereon to obtain the high-pressure pump control signal may for example contain information about the engine speed, the nominal injection volume and/or the nominal rail pressure. However, other or additional information may also be included, such as, for example, fuel temperature or engine temperature, etc.
The common rail system for a combustion engine of the invention is especially configured to be able to operate according to the method according to the invention. In addition, the common rail system has a control unit which comprises an interface for receiving an input signal and an interface for outputting a control signal. The control unit is here configured to generate the control signal based on the model and the input signal. The generated control signal is supplied to a high-pressure pump, by means of which fuel can be delivered into a fuel reservoir of the common rail system, so that a setpoint rail pressure corresponding to the input signal is generated in the fuel reservoir. In order to be able to check the rail pressure prevailing in the fuel reservoir, the common rail system has a rail pressure sensor, by means of which the rail pressure actually available there can be detected. The rail pressure obtained is supplied to a processing unit, by means of which a viscosity correction value can be obtained from the deviation of the rail pressure obtained from the setpoint rail pressure and supplied to a control unit in order to adapt the parameter for the viscosity of the fuel, which is taken into account in the model.
In respect of preferred embodiments of the common rail system according to the invention, embodiments relating to the method according to the invention apply correspondingly.
For example, the control unit of the common rail injection system may be configured to generate a corrected control signal for controlling the injection process based on the model and taking into account the viscosity correction value in addition to the corrected control signal for the high-pressure pump.
In addition, the common rail system may have a regulator which is configured to generate a regulating signal in dependence on a deviation of the rail pressure obtained with the rail pressure sensor from a nominal rail pressure, in particular for short-term correction of the deviation. In this case, the high-pressure pump can receive the control signal via an interface provided for this purpose, so that the high-pressure pump is controlled to be operated by the control signal and the control signal, whereby also only temporary rail pressure fluctuations can be compensated for in a short time.
Finally, the control unit of the common rail system may be configured to generate a control signal for the lubricant system in dependence on the obtained viscosity correction value in order to supply additional lubricant to the common rail system, so that the lubrication characteristics can be adapted.
Drawings
Further measures for improving the invention are shown in detail below together with the description of a preferred embodiment of the invention with the aid of fig. 1. The figures show that:
fig. 1 shows a very schematic detail of a common rail system according to the invention.
Detailed Description
In the partial diagram of the common rail system according to the invention shown in fig. 1, a plurality of input signals 5, 6, 7 are supplied to the connections 1, 2, 3 of the control unit 4 of the common rail system. The input signals 5, 6, 7 can be, for example, information about the engine speed, the nominal injection volume and the nominal rail pressure. Alternatively or additionally, further information may also be included, such as, for example, fuel temperature and/or engine temperature. Unlike what is shown in fig. 1, the input signals 5, 6, 7 can also be received via a common interface of the control unit 4.
Stored in the control unit 4 is a model, by means of which the operating behavior of the common rail system can be described. The control signal for the high-pressure pump 8 can be generated by means of the model by means of the input signals 5, 6, 7. Such as parameters that introduce behavior of the high pressure pump 8 into the model and leaks in the system. In addition, the parameters introduce the behavior of the fuel into the model, such as the viscosity of the fuel, since the viscosity influences, for example, leaks in the system and thus the rail pressure.
The generated control signal is output via the interface 9 and from there is supplied via a signal path 10 to the high-pressure pump 8, first via a processing unit 11 and finally via a further signal path 12. By means of the control signal, the high-pressure pump 8 is controlled in such a way that a quantity of fuel is delivered from a reservoir to a fuel reservoir, not shown in fig. 1, of the common rail system, in such a way that a setpoint rail pressure corresponding to the input signals 5, 6, 7 is generated in the fuel reservoir.
In order to detect whether the desired setpoint rail pressure is actually set in the fuel accumulator, the rail pressure actually present in the fuel accumulator is detected by a rail pressure sensor, which is not shown in fig. 1. The sensor signal corresponding to the rail pressure obtained is supplied via the signal path 13 to a comparator 14, by means of which a deviation of the rail pressure obtained from the nominal rail pressure is obtained, which is likewise supplied to the comparator 14. When one of the input signals 5, 6, 7 contains the nominal rail pressure, this input signal 7 can be supplied directly to the comparator 14 via the signal path 15 as shown in fig. 1. However, it is also possible to initially obtain the setpoint rail pressure in the control unit 4, wherein the obtained setpoint rail pressure can be supplied from the control unit 4 to the comparator 14.
The deviation of the actual rail pressure from the nominal rail pressure obtained by the comparator 14 is supplied to a processing unit 17 via a signal path 16. The viscosity correction value is obtained from the deviation in the processing unit 17. A different viscosity than that used in the model in the control unit 4 would result in, for example, a different leakage rate in the common rail system and thus a different rail pressure than that calculated from the model being set. The degree of deviation of the actual viscosity of the delivered fuel from the viscosity used in the model can then be ascertained conversely from the deviation of the rail pressure from the setpoint rail pressure.
This viscosity correction is transmitted to the control unit 4 via signal path 18. The parameters for the viscosity, which are taken into account in the model, are adapted to the viscosity correction values. That is, to further operate the common rail system, the control signal is generated on the basis of the value for the viscosity of the fuel, which is changed in the model. A modified control signal for the high-pressure pump 8 is correspondingly generated, by means of which the high-pressure pump 8 is controlled in such a way that a fuel quantity is supplied into the fuel accumulator, in which the desired setpoint rail pressure is achieved.
In the exemplary embodiment shown in fig. 1, the processing unit 17 additionally serves as a regulator 19, by means of which a regulating signal can be generated as a function of the deviation of the measured rail pressure from the setpoint pressure, which regulating signal is then supplied to the processing unit 11 via a signal path 20. In particular, the adjustment signal may be added in the processing unit 11 to the control signal generated by the control unit 4 in order to be able to correct the rail pressure for a short period of time. The regulator 19 can be designed here such that the regulating signal is generated and supplied to the processing unit 11 only before the model is adapted to the viscosity correction value in the control unit 4 and a corrected control signal can be generated. Alternatively, it can be provided that the controller 20 generates a corrected control signal for compensating short-term fluctuations in the rail pressure, while the parameters for the viscosity that are taken into account in the model are adapted only when systematic deviations of the rail pressure from the setpoint rail pressure occur. For this purpose, it can be provided, in particular, that the measured rail pressure deviates from the nominal rail pressure by substantially the same value over a longer period of time. Correspondingly, it can be provided that the processing unit 17 only obtains or supplies the viscosity correction value to the control unit 4 if the rail pressure is greater or less than the setpoint rail pressure for a longer period of time than the minimum time interval. Conversely, when the deviation is present in the case of less than the minimum time interval, an adjusting signal for short-term correction of the rail pressure is generated by the regulator 19 and is supplied to the high-pressure pump 8 in addition to the control signal.
The invention is not limited in its implementation to the preferred embodiments given above. Rather, many variants are conceivable which can employ the presented solution even in embodiments of different types in principle. All features and/or advantages, including constructional details or spatial arrangements, which are derived from the claims, the description or the drawings, may be essential to the invention as such and in different combinations.
List of reference numerals
1 interface
2 interface
3 interface
4 control unit
5 input signal
6 input signal
7 input signal
8 high-pressure pump
9 interface
10 signal path
11 processing unit
12 signal path
13 Signal path
14 comparator
15 signal path
16 signal path
17 processing unit
18 signal path
19 regulator
20 signal path

Claims (6)

1. A method for operating a common rail system of a combustion engine, the method comprising the steps of:
-supplying an input signal (5, 6, 7) to a control unit (4) of the common rail system,
-obtaining a control signal for a high-pressure pump (8) of the common rail system by means of the control unit (4) on the basis of a model stored in the control unit (4) and on the basis of the input signal (5, 6, 7),
-supplying the control signal to the high-pressure pump (8) such that the high-pressure pump (8) is controlled to generate a nominal rail pressure in a fuel reservoir of the common rail system corresponding to the input signal (5, 6, 7),
-obtaining the rail pressure actually generated in the fuel reservoir with a rail pressure sensor,
-obtaining a viscosity correction value from a deviation of the actually generated rail pressure from the nominal rail pressure,
-supplying the viscosity correction value to the control unit (4) for the high-pressure pump (8),
adapting the parameter for the viscosity of the fuel, which is taken into account in the model, to the viscosity correction value, and
-obtaining a corrected control signal for the high-pressure pump (8) by means of a model stored in the control unit (4) taking into account the viscosity correction value,
in addition to the corrected control signal for the high-pressure pump (8), a corrected control signal for controlling the starting point in time of the fuel injection, the duration of the fuel injection and/or the end point in time of the fuel injection is generated by the model, taking into account the viscosity correction value.
2. The method of claim 1, wherein
It is characterized in that the preparation method is characterized in that,
the viscosity correction value is supplied to the control unit (4) only if the obtained rail pressure deviates in one direction from the nominal rail pressure over a predetermined minimum time interval.
3. The method according to any one of the preceding claims,
it is characterized in that the preparation method is characterized in that,
-generating a regulating signal for short-term correction of the deviation of the rail pressure obtained as a function of the deviation from the nominal rail pressure by a regulator (19) of the common rail system, and
-supplying the regulating signal to the high-pressure pump (8) in addition to the control signal.
4. The method according to claim 1 or 2,
it is characterized in that the preparation method is characterized in that,
the control unit (4) generates a control signal for the lubricant system in dependence on the viscosity correction value obtained in order to supply additional lubricant to the common rail system.
5. The method according to claim 1 or 2,
it is characterized in that the preparation method is characterized in that,
the input signal includes information about engine speed, nominal injection volume, and/or nominal rail pressure.
6. Common rail system for a combustion engine, which common rail system is operable according to the method of any one of claims 1 to 5, wherein the common rail system has:
-a control unit (4) having an interface (1, 2, 3) for receiving an input signal (5, 6, 7) and an interface (9) for outputting a control signal, wherein the control unit (4) is configured to generate a control signal based on a model and the input signal (5, 6, 7) and to supply the control signal to a high pressure pump (8) of the common rail system,
-the high-pressure pump (8) which can deliver fuel into a fuel reservoir of the common rail system such that a nominal rail pressure corresponding to the input signal (5, 6, 7) is generated in the fuel reservoir by the control of a control unit (4),
a rail pressure sensor by means of which the actual rail pressure acting in the fuel accumulator can be obtained, and
-a processing unit (17) by means of which a viscosity correction value can be obtained from the obtained deviation of the actual rail pressure from the nominal rail pressure and supplied to the control unit (4) in order to adapt the parameter for the viscosity of the fuel, which is taken into account in the model.
CN201810208429.8A 2017-03-15 2018-03-14 Common rail system and method for operating a common rail system Active CN108626014B (en)

Applications Claiming Priority (2)

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DE102017105473.1 2017-03-15
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