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CN-122029346-A - Method for operating a fuel injector of an internal combustion engine, control device, computer program product and fuel injection device

CN122029346ACN 122029346 ACN122029346 ACN 122029346ACN-122029346-A

Abstract

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

Inventors

  • ENGELMANN JOACHIM
  • SEBASTIAN ERNST
  • Oscar J. Soriano Palao

Assignees

  • 舍弗勒技术股份两合公司

Dates

Publication Date
20260512
Application Date
20240918
Priority Date
20231024

Claims (9)

  1. 1. Method for operating a fuel injector (4), which fuel injector (4) comprises an injector valve (4 a) and is assigned to a combustion chamber (3 a) of an internal combustion engine (2), characterized in that the following steps are performed by a control device (7) assigned to the fuel injector (4): Driving the fuel injector (4) with one or more test drive signals within an operating range of the fuel injector (4) based on a target opening duration of the injector valve (4 a), the operating range being characterized by non-critical operating parameters; receiving and evaluating a response signal of the fuel injector (4) to the test drive signal feedback; Determining the actual opening duration of the injector valve (4 a) and its deviation from the opening duration of the target opening duration based on the fed-back response signal, and storing the deviation of the opening duration; Receiving an operating signal representative of the current pressure and current temperature of the fuel present at the fuel injector (4) and deriving therefrom the pressure and temperature of the fuel; Retrieving a transfer function for calculating a driving parameter of the fuel injector (4) in dependence of a predetermined target fuel injection quantity, a stored deviation of the opening duration of the injector valve (4 a), and at least the pressure and/or temperature of the fuel present at the fuel injector (4); determining driving parameters for driving the fuel injectors (4) to inject fuel into the respective combustion chambers (3 a) of the internal combustion engine (2) based on a predetermined target fuel injection quantity and a stored deviation of the opening duration of the injector valves (4 a) and depending on a current pressure and/or a current temperature of the fuel, using a transfer function also within an operating range of the fuel injectors (4) characterized by key operating parameters; based on the calculated driving parameters, a driving signal for the fuel injector (4) is output to perform fuel injection to the allocated combustion chamber also within an operating range characterized by the key operating parameters.
  2. 2. The method according to claim 1, characterized in that the transfer function comprises a calculation method based on a calibratable characteristic map and/or a mathematical physical calculation model, which also extends to the operating range characterized by the key operating parameters.
  3. 3. The method according to claim 1 or 2, characterized in that critical operating parameters are present if at least the following conditions are fulfilled: target fuel injection amount assumption for upcoming fuel injections of less than 5mg, and/or The fuel pressure assumption present at the fuel injector (4) is less than 200bar, and/or The fuel temperature assumption present at the fuel injector (4) is less than 50 ℃.
  4. 4.A method according to any one of the preceding claims, wherein the driving parameters to be calculated comprise at least a driving duration for opening the injector valve (4 a).
  5. 5. A method according to any one of the preceding claims, wherein the actual opening moment of the injector valve (4 a) determined in normal operation is also taken into account when calculating the drive parameters for driving the fuel injector (4) using the transfer function, and as a further drive parameter a corrected drive start moment for opening the injector valve (4 a) is determined.
  6. 6. The method according to any of the preceding claims, wherein the transfer function is derived based on measurements of a plurality of fuel injectors (4) of the same type as used in the internal combustion engine (2) under laboratory conditions, in particular also within an operating range of fuel injectors (4) characterized by key operating parameters.
  7. 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 one of the preceding claims, comprising at least: An electronic storage device (7 b) in which at least one computer program product (11) is provided with program instructions for executing the method and the transfer function, and An input/output interface (7 c) configured to receive and output an electrical signal, and An electronic processing unit (processor) (7 a) for executing program instructions and having access to at least one electronic storage means (7 b) and an input/output interface (7 c); Wherein the program instructions, when executed by the electronic processing unit (7 a), cause the control device (7) to perform the method of any of the preceding claims.
  8. 8. A computer program product (11) comprising program instructions for execution by an electronic processing unit (7 a) of a control device (7) according to claim 7, wherein the program instructions, when executed by the electronic processing unit (7 a), cause the control device (7) to perform the method of any one of claims 1 to 6.
  9. 9. A fuel injection device (1) for an internal combustion engine (2), comprising: At least one fuel pressure accumulator (5) for supplying fuel to the operation of the internal combustion engine (2); At least one fuel injector (4) which is assigned to a combustion chamber (3 a) of the internal combustion engine (2) and is supplied with fuel by a fuel pressure accumulator (5); Control device (7) according to claim 7 for operating at least one fuel injector (4) according to the method of any one of claims 1 to 6.

Description

Method for operating a fuel injector of an internal combustion engine, control device, computer program product and fuel injection device Technical Field The present invention relates to a method for operating a fuel injector for injecting fuel into combustion chambers of cylinders of an internal combustion engine, in particular in critical operating intervals. The invention further relates to a control device, a computer program product and a fuel injection device for operating a fuel injector according to the method of the invention. The internal combustion engine is preferably an internal combustion engine of a motor vehicle. Background In an internal combustion engine, in particular of a motor vehicle, fuel is supplied to each cylinder by a fuel injection device for combustion at high pressure and with high accuracy for each combustion process. Fuel injection devices are typically composed of a high pressure pump through which fuel is delivered to a downstream high pressure line or fuel pressure accumulator (also referred to as a "common rail") and pressurized to a pressure above ambient pressure. From this high-pressure accumulator, the hydraulically connected fuel injectors assigned to the individual cylinders are supplied with fuel at high pressure. The fuel is injected in a predetermined opening duration by opening the injector valve of each fuel injector in an amount that is measured with high accuracy. The fuel may be injected directly into the combustion chamber of each cylinder or into the air flow of an intake manifold assigned to each cylinder. Fuel injectors come in a variety of configurations, such as electromagnetic or piezoelectric actuation. The amount of fuel metered each time depends, in addition to the duration of opening of the injector valve, mainly on the pressure level in the fuel pressure accumulator and the temperature of the supplied fuel, which in turn affects the opening behaviour of the injector valve of the fuel injector. Based on the load and power demands on the internal combustion engine, an electronic engine control unit (commonly referred to simply as an ECU) will pre-calculate the nominal fuel injection amount required for each injection of each fuel injector and derive therefrom the nominal opening duration required for the injector valve of each fuel injector and determine the nominal start time for each injection. Based on the parameters thus determined, the electronic engine control unit calculates individual injector control parameters and outputs corresponding control signals to each fuel injector, thereby effecting opening of each injector valve and fuel injection. However, in practice it is found that the actual fuel injection quantity actually obtained is generally not identical to the nominal fuel injection quantity calculated in advance. The reasons for this include component tolerances of the fuel injector and control unit electronics, pressure fluctuations in the high pressure system, temperature variations of the components and the fuel, etc. Deviations in the actual fuel injection quantity that result therefrom can have a negative effect on the performance, the fuel consumption, in particular on the exhaust emissions of the internal combustion engine and the pollutant content in the exhaust gases. This is not acceptable in view of the legal requirements that are currently and future expected, in particular regarding the exhaust gas behavior of the internal combustion engine of a motor vehicle, and corresponding modifications are required. Thus, during operation, the injection behavior of each fuel injector is continuously checked and corresponding correction factors are determined, which are subsequently incorporated into the calculation of the injector individual control parameters. For example, document DE 10 2012 217 121 A1 discloses a method for determining the effective injection time/opening duration of a valve with coil drive, wherein the opening time and closing time of the valve are determined and the effective injection time of the injection process is determined taking into account the determined opening time and closing time. Document DE 10 2015 219 673 A1 also discloses a method for determining the time of a predetermined opening state of a fuel injector with a magnetic coil drive in an internal combustion engine of a motor vehicle, wherein the predetermined opening state of the fuel injector can be the start of the opening phase, the end of the opening phase, the start of the closing phase or the end of the closing phase. Furthermore, DE 10 2016 207 629 B3 discloses a method for identifying fuel injectors with a magnetic coil drive and similar movement behavior. For each fuel injector, a series of drive/measurements are made and the drive time is incrementally increased, the corresponding off time is recorded, and the relationship between the drive time and the off time for each fuel injector is obtained. The relationship between each drive