Method for operating fuel injector of internal combustion engine, control device, computer program product and fuel injection device

Abstract

The method, the control device (7), the computer program product (11) and the fuel injection device (1) according to the invention are designed to operate a fuel injector (4) which has an injector valve (4a) and is associated with a combustion chamber (3a) of the internal combustion engine (2), in particular within a critical operating range of the fuel injector (4). For this purpose, an electronic control device (7) associated with the fuel injector (4) first applies a test control signal to the injector valve (4a) during a non-critical operating interval and receives a corresponding response signal from the fuel injector (4) and determines therefrom an opening duration deviation of the injector valve (4a). Control parameters for controlling the fuel injector (4) to inject fuel in a critical operating interval of the fuel injector (4) are determined by means of a transfer function as a function of a specified target fuel injection amount and a determined opening duration deviation of the injector valve (4a), and a current pressure and / or a current fuel temperature, and a corresponding control signal is output to drive the fuel injector (4). In this way, a nominal specified fuel injection quantity and optionally a desired injection starting time can be achieved with high accuracy even in a critical operating range of the fuel injector (4).

Description

Technical Field

[0001] This invention relates to a method for operating a fuel injector for injecting fuel into the combustion chambers of each cylinder of an internal combustion engine, particularly within critical operating ranges. Furthermore, the invention also relates to a control device, computer program product, and fuel injection apparatus for operating the fuel injector according to the method of the invention. The internal combustion engine is preferably a motor vehicle internal combustion engine. Background Technology

[0002] In internal combustion engines, especially those in motor vehicles, fuel is supplied to each cylinder at high pressure and precision for combustion in each combustion cycle via a fuel injection system. The fuel injection system typically consists of a high-pressure pump that delivers fuel to a downstream high-pressure line or fuel pressure accumulator (also known as a "common rail") and pressurizes it to a pressure higher than ambient pressure. From this high-pressure accumulator, hydraulically connected fuel injectors, distributed to each cylinder, supply fuel at high pressure. Fuel is injected in a precisely metered amount by opening the injector valves of each fuel injector for a predetermined opening duration. Fuel can be injected directly into the combustion chamber of each cylinder or into the airflow distributed to the intake manifold for each cylinder. Fuel injectors come in various structural forms, such as electromagnetically driven or piezoelectrically driven designs.

[0003] The amount of fuel injected each time depends not only on the duration of the injector valve's opening but also primarily on the pressure level in the fuel pressure accumulator and the temperature of the supplied fuel, which in turn affects the opening behavior of the fuel injector valve. Based on the load and power requirements of the internal combustion engine, the electronic engine control unit (ECU) pre-calculates the nominal fuel injection quantity required for each fuel injector per injection, and from this, derives the nominal opening duration required for each fuel injector valve, and determines the nominal start time of each injection. Based on these determined parameters, the ECU calculates the control parameters for each injector and outputs corresponding control signals to each fuel injector, thereby realizing the opening of each injector valve and fuel injection.

[0004] However, in practice, it has been found that the actual fuel injection quantity obtained often does not match the pre-calculated nominal fuel injection quantity. Reasons for this include component tolerances in the fuel injectors and control unit electronic components, pressure fluctuations in the high-pressure system, and temperature variations in components and fuel.

[0005] The resulting deviation in actual fuel injection quantity can negatively impact performance, fuel consumption, and especially the exhaust emissions and pollutant content of internal combustion engines. Given current and anticipated legal requirements, particularly those concerning the exhaust behavior of internal combustion engines in motor vehicles, this is unacceptable and requires appropriate correction. Therefore, the injection behavior of each fuel injector is continuously monitored during operation, and corresponding correction factors are determined. These correction factors are subsequently incorporated into the calculation of individual injector control parameters.

[0006] For example, document DE 10 2012 217 121 A1 discloses a method for determining the effective injection time / opening duration of a coil-driven valve, wherein the valve's opening and closing times are determined, and the effective injection time of the injection process is determined based on the determined opening and closing times. Document DE 10 2015 219 673A1 also discloses a method for determining the time of a predetermined opening state of a fuel injector with a magnetic coil drive in a motor vehicle internal combustion engine, wherein the predetermined opening state of the fuel injector can be the start of an opening phase, the end of an opening phase, the start of a closing phase, or the end of a closing phase.

[0007] Furthermore, document DE 10 2016 207 629 B3 discloses a method for identifying fuel injectors with similar motion behavior driven by magnetic coils. For each fuel injector, a series of actuations / measurements are performed, with the actuation time progressively increased, and the corresponding shut-off time is recorded, thereby obtaining the relationship between the actuation time and shut-off time of each fuel injector. The relationships between each actuation time and shut-off time are compared, and the similarity of the motion behavior of each fuel injector is determined based on this comparison. Through the relationship between actuation time and shut-off time, the minimum actuation time of each fuel injector can be determined, at which the armature of the first fuel injector moves. The minimum actuation time effectively determines the opening time of the injector valve.

[0008] As injection time decreases, the inaccuracy of relative injection quantity increases. Until now, these differences in relative quantities have been small compared to the total injection quantity and have no practical significance. However, the trend towards smaller injection quantities and injection times means that the impact of relative quantity deviations due to variations in injector valve opening behavior can no longer be ignored. Variations in injector valve closing or the end of its movement can be compensated for by appropriate closing time detection. However, due to the aforementioned developments, deviations at the opening timing point are also receiving increasing attention.

[0009] When determining the injector valve opening timing (i.e., the start of injection), current operating and environmental conditions have a greater impact. Numerous injector opening timing measurements show a close correlation between the injector valve opening timing and fuel pressure and temperature. This behavior may vary across different types of injectors. Of particular critical importance for determining the injector valve opening timing is the discontinuous pressure dependence. This discontinuity is more pronounced the later the injector valve opens. Furthermore, the discontinuous pressure behavior may also exhibit an additional dependence on fuel temperature. This makes it impossible to extrapolate values ​​measured in non-critical operating ranges to critical operating ranges.

[0010] Furthermore, fluctuations in operating conditions can be highly detrimental to accurately determining the opening timing of the injector valve. In particular, methods that detect the injector valve opening timing through a series of actuations (test pulses) require stable environmental conditions to ensure reliable detection.

[0011] Therefore, during normal engine operation, it is difficult to determine the injector valve opening time under conditions of extremely low fuel temperature, extremely low fuel pressure, or extremely short injection duration. This is because, on the one hand, fuel temperature automatically rises as the engine runs, and on the other hand, due to systemic combustion technology, fuel pressure is only regulated to the low range for a very short time. This means that for internal combustion engines, especially those in motor vehicles, there are certain operating conditions where the actual injector valve opening time cannot be determined due to the extremely short operating time within that range. Consequently, the actual injection or opening duration of the injector valve cannot be determined, yet injection quantity correction is still required based on the determined opening duration.

[0012] Overall, these measurements also show that similar injectors exhibit predictable (even if discontinuous) behavior in terms of fuel pressure and temperature. Summary of the Invention

[0013] Therefore, the objective of this invention is to provide a method for operating a fuel injector in an internal combustion engine that ensures improved metering accuracy when metering fuel to each cylinder combustion chamber, even under critical operating conditions.

[0014] This task is accomplished through the subject matter of the independent claims.

[0015] Advantageous embodiments, further developments and details of the invention can be obtained from the dependent claims, the specification and the drawings.

[0016] The advantage of this invention is that the drive parameters can be corrected even within the fuel injector operating range characterized by key operating parameters, thereby achieving the nominal fuel injection quantity and (if necessary) the target injection start time with high precision.

[0017] The present invention discloses a method for operating a fuel injector, the fuel injector comprising an injector valve and distributed to a combustion chamber of an internal combustion engine, wherein the following steps are performed by an electronic control unit distributed to the fuel injector. First, based on a target opening duration of the injector valve, the fuel injector is driven with one or more test drive signals within a fuel injector operating range characterized by non-critical operating parameters. Then, the electronic control unit receives and evaluates a response signal from the fuel injector to the test drive signals. Based on the feedback response signal, the actual opening duration of the injector valve and its deviation from the target opening duration are determined, and this deviation is stored, for example, in an electronic storage device of the control unit.

[0018] In addition, the electronic control unit receives operating signals representing the current pressure and temperature of the fuel present at the fuel injector, and thereby derives the fuel pressure and temperature. Furthermore, it retrieves a transfer function, for example from a designated storage area of ​​the electronic control unit, for application in calculating fuel injector drive parameters, the calculation depending on a predetermined target fuel injection quantity, previously stored injector valve opening duration deviation, and at least one pressure and / or temperature of the fuel present at the fuel injector. Subsequently, drive parameters for driving the fuel injectors to inject fuel into the respective combustion chambers of the internal combustion engine are determined, particularly within the fuel injector operating range characterized by key operating parameters, based on the predetermined target fuel injection quantity and the determined injector valve opening duration deviation, and depending on the current pressure and / or current temperature. Finally, based on the calculated drive parameters, a drive signal for driving the fuel injectors is output to perform fuel injection into the assigned combustion chambers, also within the operating range characterized by the key operating parameters.

[0019] The fuel injector operating range characterized by non-critical operating parameters is characterized by operating parameters affecting operation (such as fuel pressure, fuel temperature, and required injection quantity) having values ​​that ensure a primarily linear relationship between the driving variable and the resulting variable (e.g., driving duration and injector valve opening duration). Conversely, within the range characterized by critical operating parameters, the operating parameters affecting operation have values ​​that do not ensure a linear relationship between the driving and resulting variables, but rather exhibit, for example, discontinuities.

[0020] To determine the actual opening duration, methods known in the prior art can be used to determine the actual opening and closing times of the injector valve. The actual opening and closing times refer to the rotational positions of the internal combustion engine crankshaft. The actual opening duration is the time interval or rotational angle segment between the actual opening and closing times. The test drive signals, response signals, operating signals, and drive signals for the fuel injector mentioned herein can be analog signals, digital signals, or data signals.

[0021] Conceptually, this method can be divided into two subroutines: an adaptive subroutine and a corrective subroutine. The adaptive subroutine includes steps until the deviation in the on-time is determined and stored. For example, to account for fuel injector aging, this subroutine only needs to be executed over longer time intervals. The corrective subroutine includes steps from receiving an operating signal representing the current pressure and temperature of the fuel present at the fuel injector to outputting a drive signal for the fuel injector. This subroutine must be executed for each injection operation during normal operation of the internal combustion engine.

[0022] Therefore, prior to the method of the present invention, it can be first checked in the test step PS whether the conditions for executing the entire method (i.e., the adaptive procedure and the correction procedure) are met. If met, the fuel injector is driven by one or more test drive signals to initiate and execute the method as claimed. Otherwise, the correction procedure is executed only when calculating the drive parameters for each injection operation, the calculation being based on the opening duration deviation stored during the last execution of the adaptive procedure.

[0023] Therefore, the adaptive procedure can be executed only over a specific, relatively long interval and under conditions that ensure stable operation, while the corrective procedure can be executed at each injection operation. The conditions for executing the adaptive procedure and thus the entire method of the invention can be, for example, met at each internal combustion engine restart, after a certain number of injection operations, or when environmental conditions undergo significant changes. Current operating conditions, such as the existence of stable operating conditions at a given operating temperature, and specific combinations of the above and / or other conditions, can also serve as prerequisites for executing the method.

[0024] One embodiment of this method is characterized in that the transfer function comprises a calculation method based on calibrable characteristic maps and / or mathematical-physical calculation models, which also extends to the operating range characterized by critical operating parameters. This approach advantageously allows for corrections when calculating the drive parameters used to drive the fuel injectors to inject fuel into the combustion chambers of the internal combustion engine, even within the fuel injector operating range characterized by critical operating parameters, where corrections by simple extrapolation from non-critical operating ranges are not feasible.

[0025] Another embodiment of this method is characterized by the existence of critical operating parameters if the target fuel injection quantity for the upcoming fuel injection is less than 5 mg, particularly less than 4 mg or less than 3 mg. At such a small injection quantity, the fuel injector may already be in a so-called ballistic operating state. That is, the injector valve is no longer fully open, and the closing process begins before the injector valve is fully open. Within this operating range, the rules governing the injection quantity differ from those in the range where the injector valve is fully open and the injection quantity is primarily determined by the static flow rate. Therefore, these different rules must also be considered in the transfer function when correcting the drive parameters.

[0026] Critical operating parameters also exist if the fuel pressure at the fuel injector is less than 200 bar, especially less than 150 bar or less than 100 bar. Since the fuel pressure at the fuel injector affects the opening behavior of the injector valve, and the opening behavior at low fuel pressure differs from the predetermined opening behavior at higher, normal operating fuel pressure, this condition is also mapped into the transfer function and advantageously considered when correcting the drive parameters. Furthermore, critical operating parameters also exist if the fuel temperature at the fuel injector is less than 50°C, especially less than 40°C or less than 30°C. Such a low fuel temperature affects the temperature of the fuel injector mechanical components, for example, through thermal expansion, and may also cause discontinuities in injection quantity measurement; therefore, the required accuracy cannot be obtained simply by extrapolating correction values ​​from non-critical operating ranges. Therefore, this condition is also mapped into the transfer function and advantageously considered when correcting the drive parameters.

[0027] Finally, the aforementioned key operating parameters can appear in any combination and can influence each other. These cases are also advantageously stored in the transfer function and taken into account when modifying the driving parameters.

[0028] In one embodiment of the method of the present invention, the drive parameters to be calculated include at least the drive duration for opening the injector valve. The drive duration determines the opening duration, thereby determining the amount of fuel actually injected into the combustion chamber of each cylinder of the internal combustion engine. For example, to perform a test drive, a target opening duration and a target drive duration required for the injector valve can be determined. Within the fuel injector operating range determined by non-critical operating parameters, the actual opening duration based on the target drive duration and its deviation from the target opening duration are then determined.

[0029] Based on the determined deviation, the target drive duration of subsequent fuel injection operations can be corrected to ensure that the actual opening duration matches the target opening duration.

[0030] Within the fuel injector operating range characterized by non-critical operating parameters, there is generally a linear relationship between the drive duration and the injector valve opening duration, which can be easily corrected. However, within the fuel injector operating range characterized by critical operating parameters, firstly, the deviation between the actual obtained opening duration and the nominal opening duration cannot be determined for the reasons mentioned above, and secondly, due to discontinuities and the interaction between different operating parameters, extrapolation based on the deviation value determined in the non-critical operating range is not possible.

[0031] Therefore, a transfer function is needed to correct the drive duration within the fuel injector operating range characterized by critical operating parameters, based on deviations determined in non-critical operating ranges. Using the transfer function, the determined target drive duration is then corrected according to the required fuel injection quantity and / or current fuel pressure and / or current fuel temperature, ultimately ensuring that the target opening duration matches the actual opening duration even within the operating range characterized by critical operating parameters. This advantageously ensures that fuel injection accuracy is guaranteed even within the critical operating range.

[0032] In a further embodiment of the method of the present invention, when calculating the driving parameters for driving the fuel injector using the transfer function, the actual opening time of the injector valve, determined within the fuel injector operating range characterized by non-critical operating parameters (i.e., the start time of the injector valve opening process), is also considered and used as a further driving parameter to determine the corrected target driving start time for opening the injector valve using the transfer function. This advantageously improves the timing accuracy of the injection operation at the crankshaft rotation position of the internal combustion engine.

[0033] Finally, another embodiment of the method of the present invention is characterized in that the transfer function is derived based on measurements of multiple fuel injectors of the same type used in the internal combustion engine under laboratory conditions, particularly within the operating range of the fuel injectors characterized by key operating parameters. In this case, it is advantageous to measure the operating behavior of a certain type of fuel injector under ideal laboratory conditions and establish a transfer function based on these measurements, which extends to the key operating range of that type of fuel injector. Unlike internal combustion engine operation, the key operating range can be maintained for a sufficiently long time under laboratory conditions, thereby allowing the identification and analysis of operating data and their relationships within these ranges. The results can then be summarized into the transfer function for use in correcting drive parameters within the key operating range during normal operation of all fuel injectors of the same type.

[0034] The electronic control device for operating at least one internal combustion engine fuel injector according to any embodiment of the method of the present invention includes at least one electronic storage device, wherein at least a computer program product and program instructions for performing the method described above are provided. Furthermore, the electronic control device includes an input / output interface for receiving and outputting electrical / electronic signals, and an electronic processing unit (processor) for executing the program instructions. The electronic processing unit has access to at least one electronic storage device and the input / output interface. When the program instructions are executed by the electronic processing unit, the electronic control device performs any embodiment of the method of the present invention described above.

[0035] The computer program product of the present invention includes program instructions for execution by the electronic processing unit of the above-described electronic control device, which, when executed by the electronic processing unit, cause the electronic control device to perform any embodiment of the method of the present invention.

[0036] The fuel injection device for an internal combustion engine of the present invention includes at least a fuel pressure accumulator for supplying fuel for the operation of the internal combustion engine, at least one fuel injector, which is assigned to the combustion chamber of the internal combustion engine and supplied with fuel by the fuel pressure accumulator, and a control device (7) as described above for operating at least one fuel injector according to any embodiment of the method of the present invention described above.

[0037] With the electronic control device, fuel injection device, and computer program product of the present invention, the drive parameters can be corrected even within the fuel injector operating range characterized by key operating parameters, thereby achieving the nominal fuel injection quantity and (if necessary) the target injection start time with high precision.

[0038] In summary, a method, control device, computer program product, and injection device are proposed, which, according to the invention, are configured to operate a fuel injector comprising an injector valve and distributed to the combustion chamber of an internal combustion engine, particularly within the critical operating range of the fuel injector. To this end, an electronic control device distributed to the fuel injector first drives the fuel injector with a test drive signal in the non-critical operating range and receives a corresponding response signal from the fuel injector, thereby determining the actual opening time, actual closing time, and actual opening duration of the injector valve. Using a transfer function, then based on a predetermined target fuel injection quantity and the determined actual opening duration of the injector valve, and depending on the current pressure and / or current temperature, drive parameters for driving the fuel injector to inject fuel are determined, even within the critical operating range of the fuel injector, and a corresponding drive signal is output to drive the fuel injector. This advantageously ensures that the nominal fuel injection quantity and (if necessary) the target injection start time can be achieved with high accuracy even within the critical operating range of the fuel injector.

[0039] The features and combinations of features of the embodiments of the present invention described in the foregoing specification or the illustrations below, as long as they are not interchangeable or mutually exclusive, can be used individually, in part or in whole, in combination or in complement to each other for further development of the present invention, without exceeding the scope of the present invention.

[0040] The features and details described in relation to the method also apply to electronic control devices, claimed computer program products, and fuel injection devices, and vice versa; therefore, each aspect of the invention may be referenced in turn with respect to the disclosure of the present invention.

[0041] The following description, in conjunction with the accompanying drawings, further illustrates particularly advantageous embodiments, details, or further developments of the invention, although the subject matter of the invention is not limited to these examples. Attached Figure Description

[0042] Figure 1 This is a simplified schematic diagram of an internal combustion engine equipped with the fuel injection device and electronic control device of the present invention.

[0043] Figure 2 This is a simplified flowchart of the method of the present invention.

[0044] The accompanying drawings are for illustrative purposes only, and the dimensional proportions of the figures and the components shown should not be considered as proportional relationships. For ease of display and / or understanding, some components may be exaggerated. Components with the same function and name, similar functions, or identical effects are labeled with the same reference numerals in all figures. For clarity, some reference numerals may be omitted in some figures. Detailed Implementation

[0045] Figure 1 An internal combustion engine 2, such as that of a motor vehicle, is schematically shown, having three cylinders 3. Each cylinder has a combustion chamber 3a. Each combustion chamber 3a, or each cylinder 3, is equipped with a fuel injector 4 for injecting fuel into the combustion chamber 3a. The fuel injector 4 is fluidly connected to a fuel pressure accumulator 5 via a fuel line 5a, and is supplied with fuel by the fuel pressure accumulator 5. Each fuel injector 4 includes an injector valve 4a and is connected via a respective signal line 8 to the input / output interface 7c of an electronic control unit 7, through which the control unit 7 can drive each fuel injector 4, and in particular each injector valve 4a, to inject fuel into the combustion chamber 3a of each cylinder 3. In this case, the response signal of the fuel injector 4 can also be fed back to the control unit 7. In another embodiment, a separate signal line can also be provided for each fuel injector 4 to feed back a response signal to the control unit 7.

[0046] The fuel pressure accumulator 5 (often also referred to as a "common rail") is fluidly connected to the fuel pump 6 via another fuel line 5a, and is supplied with pressurized fuel by the fuel pump 6. Depending on the type of internal combustion engine 2 and the design of the fuel injection device 1, fuel pressures ranging from a few bar to over 2000 bar can be generated here.

[0047] A pressure sensor 9 and a temperature sensor 10 are also installed on the fuel pressure accumulator 5. These sensors can detect the fuel pressure and fuel temperature present in the fuel pressure accumulator 5 and thus also present at the fuel injector 4, and convert them into electrical or electronic signals representing pressure or temperature. The pressure sensor 9 and the temperature sensor 10 are respectively connected to the input / output interface 7c of the control device 7 via signal lines 8.

[0048] The electronic control device 7 includes an electronic processing unit 7a (also called a processor), an electronic storage device 7b, and an input / output interface 7c. In this embodiment, the electronic storage device 7b includes a program memory 7b1, which stores a computer program product 11 and its program instructions. Furthermore, the electronic storage device 7b also includes a runtime data memory 7b2, which stores preset and runtime data 12 acquired during operation in the form of characteristic maps, etc. This storage area also stores, for example, transfer functions for the electronic processing unit to call.

[0049] The electronic processing unit 7a is configured to execute the method of the present invention described above and its further embodiments. For this purpose, the electronic processing unit 7a can access or be connected via data connections (indicated by connecting arrows) to the input / output interface 7c, the program memory 7b1, and the runtime data memory 7b2. When executing program instructions, the electronic processing unit 7a, in conjunction with the transfer function and related runtime data 12, drives the electronic control device 7 to execute the method of the present invention for operating the fuel injection device 1.

[0050] According to the program instructions, it receives sensor data or operating data, such as the response signal of the fuel injector, and the signals representing fuel pressure and temperature from the pressure sensor 9 and the temperature sensor 10 through the input / output interface 7c, executes the calculation operations specified by the program, and outputs control commands based on these operations, such as for controlling the fuel injector 4.

[0051] A computer-readable storage medium 13 is also shown, which stores a computer program product 11 and its program instructions, which, when executed by the electronic processing unit 7a of the electronic control device 7, cause it to perform the method described above for controlling the fuel injector 4 of the internal combustion engine 2. As described above, the computer program product 11 is pre-transmitted to the program memory 7b1 of the control device 7 via or together with the computer-readable storage medium 13.

[0052] exist Figure 2 In this embodiment of the method, process steps 20 to 26 are shown in a simplified flowchart. The method can conceptually be divided into two subroutines: an adaptive procedure and a corrective procedure. The adaptive procedure, identified by process steps 20 to 22, includes steps up to determining and storing the opening duration deviation. The corrective procedure, identified by process steps 23 to 26, must be performed for each injection operation during normal operation of the internal combustion engine.

[0053] Therefore, before proceeding with the method of this invention, the conditions for executing the entire method (i.e., executing the two subroutines sequentially) are first checked in the test step PS. If the conditions are met, the method is executed starting from process step 20 and according to the claims. Otherwise, the process jumps to process step 23, where the correction procedure is executed only when calculating the drive parameters for each injection operation.

[0054] Therefore, the adaptive program can be executed only over a specific, longer interval and under conditions that ensure stable operation, while the correction program can be executed at each injection operation.

[0055] After the method for operating the fuel injector 4 is initiated, the fuel injector 4, which includes an injector valve 4a and is assigned to the combustion chamber 3a of the internal combustion engine 2, performs the following process steps via an electronic control device 7 assigned to the fuel injector 4.

[0056] First, in process step 20, based on the target opening duration of injector valve 4a, fuel injector 4 is driven by one or more test drive signals (represented by arrow symbol P1) within the operating range of fuel injector 4 characterized by non-critical operating parameters.

[0057] In subsequent process step 21, the response signal of the fuel injector 4 to the test drive signal feedback is received (indicated by arrow symbol P2) and evaluated. This could be, for example, fluctuations in the applied voltage and / or flowing current caused by the actuator of the fuel injector.

[0058] In subsequent process step 22, based on the feedback response signal, the actual opening duration of the injector valve 4 and its deviation from the target opening duration are determined, and this opening duration deviation is stored, or a deviation value representing the opening duration deviation is stored, for example, in the operation data memory 7b2 of the electronic storage device 7b of the control device 7. For this purpose, for example, based on the feedback response signal in process step 21, the actual opening time and actual closing time of the injector valve 4a are determined. The actual opening duration is the time period between the actual opening time and the actual closing time. The deviation value of the opening duration from the target opening duration characterizes the deviation between the actual behavior of the injector valve 4a and the desired ideal behavior.

[0059] In subsequent process step 23, an operation signal (represented by arrow symbol P3) is received, which represents the current pressure and temperature of the fuel present at fuel injector 4, and from this, the fuel pressure and temperature are deduced. For example... Figure 1 As shown, these signals can be provided by pressure sensor 9 and temperature sensor 10, both of which are located on fuel pressure accumulator 5 and connected to input / output interface 7c of control device 7 via signal line 8.

[0060] In subsequent process step 24, the transfer function used to calculate the driving parameters of the fuel injector 4 is retrieved, for example, from the operating data memory 7b2 of the control unit 7, indicated by arrow symbol P5. This retrieval depends on a predetermined target fuel injection quantity, a stored deviation in the opening duration of the injector valve 4a, and at least one pressure and / or the temperature of the fuel present at the fuel injector 4.

[0061] Subsequently, in process step 25, the drive parameters for driving the fuel injector 4 to inject fuel into the corresponding combustion chamber 3a of the internal combustion engine 2 are determined, including within the operating range of the fuel injector 4 characterized by key operating parameters. This determination is based on a predetermined target fuel injection quantity and the deviation of the stored opening duration of the injector valve 4a, and depends on the current pressure and / or current temperature, using a transfer function. Finally, in process step 26, a drive signal based on the calculated drive parameters (represented by arrow symbol P4) is output to perform fuel injection into the assigned combustion chamber 3a, also within the operating range characterized by key operating parameters.

[0062] After completing the above process steps 20 to 26, return to the test step PS and the process restarts.

[0063] Reference number list 1. Fuel injection device 2. Internal Combustion Engine 3 cylinders 3a Combustion Chamber 4. Fuel Injectors 4a Injector Valve 5. Fuel pressure accumulator 5a Fuel Line 6. Fuel pump 7. Control device 7a Electronic processing unit 7b Electronic storage device 7b1 Program Memory 7b2 Running Data Memory 7c Input / Output Interface 8 signal lines 9. Pressure sensor 10 Temperature Sensor 11 Computer program products 12. Running Data 13 Storage Media 20...26 Process Steps P1...5 Arrow symbol

Claims

1. A method for operating a fuel injector (4), said fuel injector (4) comprising an injector valve (4a) and being dispensed into a combustion chamber (3a) of an internal combustion engine (2), characterized in that, The following steps are performed by the control device (7) assigned to the fuel injector (4): • Based on the target opening duration of the injector valve (4a), the fuel injector (4) is driven by one or more test drive signals within the operating range of the fuel injector (4), which is characterized by non-critical operating parameters; • Receive and evaluate the response signal of the fuel injector (4) to the test drive signal feedback; • Based on the feedback response signal, determine the actual opening duration of the injector valve (4a) and its opening duration deviation from the target opening duration, and store the opening duration deviation; • Receive an operating signal representing the current pressure and current temperature of the fuel present at the fuel injector (4), and deduce the pressure and temperature of the fuel from it; • Based on the predetermined target fuel injection quantity, the deviation of the opening duration of the stored injector valve (4a), and the minimum pressure and / or temperature of the fuel present at the fuel injector (4), retrieve the transfer function for calculating the driving parameters of the fuel injector (4); • Based on the predetermined target fuel injection quantity and the deviation of the opening duration of the stored injector valve (4a), and depending on the current pressure and / or current temperature of the fuel, the driving parameters for driving the fuel injector (4) to inject fuel into the corresponding combustion chamber (3a) of the internal combustion engine (2) are determined using the transfer function, also within the operating range of the fuel injector (4) characterized by key operating parameters. • Based on the calculated drive parameters, a drive signal is output for the fuel injector (4) so ​​that fuel injection is performed into the assigned combustion chamber within the operating range characterized by the key operating parameters.

2. The method according to claim 1, characterized in that, The transfer function includes computational methods based on calibrable characteristic maps and / or mathematical and physical computational models, and also extends to the operational range characterized by key operating parameters.

3. The method according to claim 1 or 2, characterized in that, A critical operating parameter exists if at least the following conditions are met: • The target fuel injection quantity for the upcoming fuel injection is assumed to be less than 5 mg, and / or • The fuel pressure at the fuel injector (4) is assumed to be less than 200 bar, and / or • The fuel temperature at the fuel injector (4) is assumed to be less than 50°C.

4. The method according to any of the preceding claims, wherein the drive parameters to be calculated include at least the drive duration for opening the injector valve (4a).

5. The method according to any of the preceding claims, wherein, When calculating the driving parameters for driving the fuel injector (4) using the transfer function, the actual opening time of the injector valve (4a) determined during normal operation is also considered and used as a further driving parameter to determine the corrected driving start time for opening the injector valve (4a).

6. The method according to any of the preceding claims, wherein, The transfer function is derived based on measurements of multiple fuel injectors (4) of the same type used in the internal combustion engine (2) under laboratory conditions, particularly within the operating range of the fuel injectors (4) characterized by key operating parameters.

7. A control device (7) for operating at least one fuel injector (4) of an internal combustion engine (2) according to the method of any of the preceding claims, comprising at least: • An electronic storage device (7b), wherein at least one computer program product (11) is provided with program instructions for performing the method and the transfer function, and • Input / output interface (7c), which is configured to receive and output electrical signals, and • An electronic processing unit (processor) (7a) for executing program instructions and having access to at least one electronic storage device (7b) and an input / output interface (7c). in, When the program instructions are executed by the electronic processing unit (7a), they cause the control device (7) to perform the method of any of the preceding claims.

8. A computer program product (11) comprising program instructions for execution by an electronic processing unit (7a) of a control device (7) according to claim 7, wherein, When the program instructions are executed by the electronic processing unit (7a), they cause the control device (7) to perform the method of any one of claims 1 to 6.

9. A fuel injection device (1) for an internal combustion engine (2), comprising: • At least one fuel pressure accumulator (5) for supplying fuel for the operation of the internal combustion engine (2); • At least one fuel injector (4) is assigned to the combustion chamber (3a) of the internal combustion engine (2) and is supplied with fuel by a fuel pressure accumulator (5); • and the control device (7) according to claim 7, for operating at least one fuel injector (4) by the method of any one of claims 1 to 6.

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