Method for multiple injection with quantity correction for an internal combustion engine and engine control unit

Abstract

The invention relates to a method (100) for injecting a predetermined total amount of fuel by performing multiple injections using a fuel injector with a magnetic coil drive for an internal combustion engine of a motor vehicle, the method comprising: (a) determining (110) a first setpoint injection quantity that should be injected per injection in order to inject the total amount of fuel by a series of consecutive injections, (b) performing (120) a first sub-series of consecutive injections, wherein the fuel injector is actuated based on the first setpoint injection quantity, (c) determining (130) a first fuel quantity injected during the first sub-series of injections, (d) determining (140) a second setpoint injection quantity that should be injected per injection in a second sub-series of consecutive injections in order to inject the total amount of fuel by a first sub-series of consecutive injections and a second sub-series of consecutive injections, and (e) performing (150) a second sub-series of injections, wherein the fuel injector is actuated based on the second setpoint injection quantity. The invention also relates to an engine controller and a computer program.

Description

Technical Field

[0001] The invention relates to the technical field of injecting fuel in an internal combustion engine. In particular, the invention relates to a method for injecting a predetermined total amount of fuel by multiple injection using a fuel injector with a magnetic coil drive for an internal combustion engine of a motor vehicle. The invention also relates to an engine controller and a computer program. Background Art

[0002] In gasoline-driven engines, direct injection with turbocharging has become standard. Injectors with magnetic drives are used for injection, as they are a very cost-effective solution. Due to increasing emission requirements, the demands on injection systems are also increasing. In particular, the requirements on injection quantity accuracy and injection frequency are increasing.

[0003] For design reasons, magnetic injectors have a minimum dwell time of about 1 ms, for example, necessary for complete dissipation of the coil magnetization. In the case of shorter dwell times, the opening behavior of the fuel injector is influenced by the residual magnetization that is still present. If the energization of the injector is controlled in a known manner, i.e. essentially by means of the fuel pressure and temperature, the metering accuracy deteriorates due to the influence of the residual magnetization. Summary of the invention

[0004] The object of the present invention is to provide a high quantity accuracy in multiple injections with short dwell times in a simple manner and as cost-effectively as possible.

[0005] This object is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0006] According to a first aspect of the invention, a method for injecting a predetermined total amount of fuel by performing multiple injections using a fuel injector having a magnetic coil drive for an internal combustion engine of a motor vehicle is described. The described method comprises: (a) determining a first rated injection quantity that should be injected per injection in order to inject the total amount of fuel by a series of continuous injections, (b) performing a first sub-series of continuous injections, wherein the fuel injector is controlled based on the first rated injection quantity, (c) determining a first fuel quantity injected during the first sub-series of injections, (d) determining a second rated injection quantity that should be injected per injection in a second sub-series of continuous injections in order to inject the total amount of fuel by the first sub-series of continuous injections and the second sub-series of continuous injections, and (e) performing a second sub-series of injections, wherein the fuel injector is controlled based on the second rated injection quantity.

[0007] The described method is based on the finding that an over- or under-injection of fuel occurring during a first partial injection series can be compensated by adapting the target injection quantity per injection of a (subsequent) second partial injection series so that at the end of the second partial injection series the predetermined total fuel quantity is injected in total.

[0008] At the beginning of the method, a first setpoint injection quantity is determined. The first setpoint injection quantity corresponds to the quantity to be injected per injection, so that ideally the predetermined total amount of fuel is injected overall (over the total number of injections in a working cycle). The actual injection process then begins with the execution of a first sub-series of consecutive injections based on the previously determined first setpoint injection quantity for each individual injection. In other words, during the first sub-series, the fuel injector is controlled so that each individual injection should result in the injection of the first setpoint injection quantity. At the same time, the (actually) injected first fuel quantity is determined and used to determine the second setpoint injection quantity that should be injected per injection in the second sub-series, so that the predetermined total amount of injection is injected overall (over the first and second sub-series). Deviations that occur during the first sub-series are thus corrected by adapting the setpoint values ​​of the second sub-series.

[0009] According to an embodiment of the present invention, the first sub-series and the second sub-series together constitute a multiple injection process, in which the time intervals between two consecutive injections are the same.

[0010] In other words, the pause times between all consecutive injections in a multiple injection process are identical, ie in particular also between the last injection of the first partial series and the first injection of the second partial series.

[0011] According to a further embodiment of the invention, the time interval is so short that the magnetization of the magnetic coil driver from the previous injection cannot be completely dissipated. For typical fuel injectors, this means in particular that the time interval (or the pause time) is shorter than 1 ms.

[0012] According to another embodiment of the invention, the second subseries contains a single injection. In this case, therefore, deviations from the target value occurring in the first subseries are compensated in the single injection of the injection process, ie, the last injection.

[0013] Alternatively, the second partial series contains multiple injections. In this case, deviations from the target value occurring in the first partial series are therefore compensated in the multiple injections of the injection process, ie in the last injection (after the first partial series).

[0014] According to another embodiment of the invention, the second target injection quantity is equal to the difference between the predetermined total fuel quantity and the determined first injected fuel quantity divided by the number of injections in the second subseries.

[0015] If SEM2 represents the second set injection quantity, GKM represents the predetermined total amount of fuel, EKM1 represents the first injection fuel quantity, and N2 represents the number of injections in the second sub-series, it can be represented by the following formula:

[0016] SEM2=(GKM-EKM1) / N2.

[0017] For comparison, the first set injection quantity SEM1 mentioned above can be calculated as follows (where N1 represents the number of injections in the first sub-series):

[0018] SEM1=GKM / (N1+N2).

[0019] According to a further embodiment of the invention, determining the first fuel quantity injected during the first subseries of injections comprises estimating the injected fuel quantity based on a measured current course and / or a measured voltage course in the magnetic coil driver.

[0020] In particular, the opening and closing times of the fuel injector can be determined in a manner known per se by analyzing the time course of the current and / or the time course of the voltage in the coil of the magnetic coil drive. This allows the opening time of each injection and thus the injection duration of each injection to be determined, and ultimately the injection quantity to be estimated with high accuracy.

[0021] According to a second aspect of the invention, an engine controller for an internal combustion engine of a motor vehicle is described. The described engine controller is configured to carry out a method according to the first aspect or one of the preceding embodiments.

[0022] The described engine controller is essentially based on the same idea as the above-described method according to the first aspect and in particular enables a simple implementation of the invention without additional hardware.

[0023] According to a third aspect of the present invention, a computer program having computer executable instructions is described, which, when executed by a processor, are arranged to perform the method according to the first aspect or one of the above embodiments.

[0024] In the sense of this document, the nomenclature of such a computer program is synonymous with the concepts of program elements, computer program products and / or computer-readable media that contain instructions for controlling a computer system to appropriately coordinate the working mode of the system or method in order to achieve the effects associated with the method according to the invention.

[0025] The computer program may be implemented as a computer-readable instruction code in any suitable programming language (e.g. JAVA, C++, etc.). The computer program may be stored on a computer-readable storage medium (CD-ROM, DVD, Blu-ray disc, removable disc drive, volatile or non-volatile memory, built-in memory / processor, etc.). The instruction code may program a computer or other programmable device (e.g. a control device for an engine of a motor vehicle, in particular) so that the desired functions are performed. In addition, the computer program may be provided in a network such as the Internet, from which a user may download the computer program when necessary.

[0026] The invention can be implemented either by means of a computer program (ie software) or by means of one or more specific circuits (ie in hardware or in any mixed form), ie by means of software components and hardware components.

[0027] It should be noted that embodiments of the invention have been described with reference to different subject matters of the invention. In particular, some embodiments of the invention are described with method claims, while other embodiments of the invention are described with device claims. However, it will be immediately clear to a person skilled in the art after reading this application that, unless expressly stated otherwise, any combination of features belonging to different types of subject matters is possible in addition to the combination of features belonging to one type of subject matter.

[0028] Further advantages and features of the invention emerge from the following exemplary description of preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The figure shows a block diagram of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] It should be pointed out that the embodiments described below represent only a limited selection of possible implementation variants of the present invention.

[0031] The figure shows a block diagram of a method 100 according to an exemplary embodiment of the present invention for injecting a predetermined total amount of fuel by multiple injections using a fuel injector with a magnetic coil drive for an internal combustion engine, in particular a gasoline engine of a motor vehicle.

[0032] First, at 110, a first setpoint injection quantity that should be injected per injection in a multiple injection process in order to inject a predetermined total amount of fuel overall is determined. This can be done in particular by determining the first setpoint injection quantity as the predetermined total amount of fuel divided by the total number of injections in the multiple injection process. For example, if this total number is equal to eight, the first setpoint injection quantity is equal to one eighth of the predetermined total amount of fuel.

[0033] At 120 , a first subseries of consecutive injections is now performed, wherein the fuel injector is controlled so that each injection should inject the previously determined first target injection quantity. The first subseries preferably comprises a major part of all injections provided, for example 6 or 7 of a total of 8 injections.

[0034] Since residual magnetization may be present in the solenoid drive of the fuel injector, in particular in the case of short time intervals (pauses) between individual injections, such an actuation of the fuel injector may result in different (in particular larger) actual injection quantities at least in some injections.

[0035] To address this issue, a first fuel quantity injected during a first sub-series of injections is determined at 130 , for example by determining the opening and closing times based on current and voltage profiles measured in the magnetic coil.

[0036] Knowing the amount of fuel injected so far, a second set injection amount that should be injected per injection in the second sub-series injection is determined at 140 in order to inject the remaining fuel amount required in the second sub-series continuous injection that directly follows the first sub-series, so that a total amount of fuel is injected overall through the first sub-series continuous injection and the second sub-series continuous injection.

[0037] At 150 , the second partial injection series is performed, wherein the fuel injectors are now actuated based on a second setpoint injection quantity.

[0038] It should be noted that the first and second partial injection series directly follow each other, in particular there is no additional pause between the two partial injection series. In other words, the second target injection quantity is determined during the entire injection process.

[0039] Therefore, the first sub-series and the second sub-series together form a multiple injection process, in which the time interval between two consecutive injections is the same. Here, the time interval is particularly short so that the magnetization of the magnetic coil drive from the previous injection cannot be completely dissipated.

[0040] The second sub-series of injections comprises the last injection or injections of the entire multi-injection process.

[0041] In one embodiment, at 140 , the second target injection amount is calculated as the difference between the predetermined total fuel amount and the determined first injected fuel amount divided by the number of injections in the second sub-series.

[0042] In one embodiment, determining the first amount of fuel injected during the first sub-series of injections at 130 includes estimating the amount of fuel injected based on a measured current profile and / or a measured voltage profile in the magnetic coil driver.

[0043] The method according to the invention can be implemented directly in the engine control unit, in particular in the form of a computer program. It is particularly advantageous that no additional hardware such as special sensors or injectors is required, which would increase the overall cost of the system.

Claims

1. A method (100) for injecting a predetermined total amount of fuel by performing multiple injections using a fuel injector having a magnetic coil driver for an internal combustion engine of a motor vehicle, the method comprising: determining (110) a first target injection quantity that should be injected per injection in order to inject the total amount of fuel via a series of consecutive injections, performing (120) a first subseries of consecutive injections, wherein the fuel injector is controlled based on the first setpoint injection quantity, determining (130) a first fuel quantity injected during the first subseries of injections, determining (140) a second target injection quantity that should be injected per injection in the second sub-series of consecutive injections in order to inject the total amount of fuel through the first sub-series of consecutive injections and the second sub-series of consecutive injections, and performing (150) a second sub-series of injections, wherein the fuel injector is controlled based on the second setpoint injection quantity, The second sub-series of injections directly follows the first sub-series of injections so that the required remaining amount of fuel is injected in the second sub-series of injections.

2. The method (100) according to claim 1, wherein: The first subseries and the second subseries together form a multiple injection process in which the time intervals between two consecutive injections are the same.

3. The method (100) according to claim 2, wherein: The time interval is so short that the magnetization of the magnetic coil driver from the previous injection cannot be completely dissipated.

4. The method (100) according to any one of the preceding claims, wherein: The second sub-series comprises a single injection, or wherein the second sub-series comprises multiple injections.

5. The method (100) according to claim 4, wherein: The second target injection quantity is equal to a difference between the predetermined total fuel quantity and the determined first injected fuel quantity divided by the number of injections in the second sub-series.

6. The method (100) according to any one of the preceding claims, wherein: Determining a first fuel quantity injected during the first sub-series of injections includes estimating the injected fuel quantity based on a measured current profile and / or a measured voltage profile in the magnetic coil driver.

7. An engine control unit for an internal combustion engine of a motor vehicle, the engine control unit being configured to carry out the method (100) according to any one of the preceding claims.

8. A computer program having computer executable instructions, which, when executed by a processor, are arranged to perform the method (100) according to any one of claims 1 to 6.

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