Method for controlling an internal combustion engine and system with an internal combustion engine and a control unit

Abstract

Method for controlling an internal combustion engine, in particular a motor vehicle, wherein the internal combustion engine has at least one cylinder, wherein the internal combustion engine has at least one first injection valve (21) and one second injection valve (22) for fuel injection per cylinder, wherein the first injection valve (21) has a first valve needle and the second injection valve (22) has a second valve needle, wherein in a normal operating mode of the internal combustion engine, a predetermined first quantity of fuel is injected by actuating the first injection valve (21) during a first actuating time and an associated opening movement of the first valve needle, and a predetermined second quantity of fuel is injected by actuating the second injection valve (22) during a second actuating time and an associated opening movement of the second valve needle.wherein a signal evaluation is carried out to detect the opening movement and / or the closing movement and / or the position of the first and second valve needles, characterized in that-- in a first calibration operating mode of the internal combustion engine, a calibration control of the first injection valve (21) is carried out such that the state of movement and / or the position of the first valve needle is detected, wherein, during this time, an control of the second injection valve (22) is carried out such that a predetermined target quantity of fuel is injected, or-- in a second calibration operating mode of the internal combustion engine, a calibration control of the second injection valve (22) is carried out such that at least the state of movement and / or the position of the second valve needle is detected, wherein, during this time, an control of the first injection valve (21) is carried out such thatthat a predetermined target amount of fuel is injected.

Description

State of the art

[0001] The invention relates to a method for controlling an internal combustion engine according to the preamble of claim 1. Furthermore, the invention relates to a system comprising an internal combustion engine and a control unit, as well as a computer program and a computer program product.

[0002] Internal combustion engines with port fuel injection and two injectors per cylinder are generally known. For example, German patent DE 10 2008 044 244 A1 discloses an internal combustion engine with at least one combustion chamber, wherein the combustion chamber has two fuel inlet ports, each of which can be closed by an inlet valve. The internal combustion engine further comprises a fuel injection device which, in association with the at least one combustion chamber, has a first and a separate second injector for metered injection of fuel into at least one intake port of the combustion chamber. The injectors spray the fuel in atomized form as spray cones towards the inlet valves.

[0003] Furthermore, the so-called controlled operation of solenoid valves is known from the prior art, in which the actual movement of the valve needle and its stroke can be evaluated and thus detected via suitable feedback variables (e.g., current or voltage). This is also referred to as CVO (Controlled Valve Operation), so that, as a consequence, the movement of the valve needle (i.e., the needle movement) or the needle stroke can be uniformly adjusted from stroke to stroke of a valve or across several valves by suitable algorithms. It is also known in the prior art to determine the so-called valve delay time using special control strategies, for example, by multiple injections.

[0004] To determine or adapt such control parameters or operating behavior, either specific operating points with short valve actuation times must be reached, or the injection must be divided into two time-separated injections: a short one to learn the valve behavior and a longer one to deliver the required injection quantity. A disadvantage of this approach is that determining or adapting the control parameters depends on a multitude of secondary conditions and therefore cannot necessarily be performed at the optimal time or to the required extent. Disclosure of the invention

[0005] The inventive method for controlling an internal combustion engine, the inventive system comprising an internal combustion engine and a control unit, and the inventive computer program or computer program product according to the dependent claims have the advantage over the prior art that, both in the first calibration operating mode (with reference to the first injection valve) and in the second calibration operating mode (with reference to the second injection valve), the optimal control of the respective injection valve can be determined or adapted, whereby in certain (part-load) operating ranges of the internal combustion engine, the adaptation of the control of the respective injection valve can take place either entirely without fulfilling further boundary conditions or at least taking into account fewer boundary conditions or less restrictive boundary conditions.According to the invention, adapting the control of the respective injection valve is of particular interest, especially in the small quantity range, where non-linear behavior of the injection valve is to be expected. Therefore, according to the invention, it is advantageously possible to determine the needle lift behavior particularly easily, accurately, and quickly for a wider range of possible situations compared to the prior art, especially with regard to determining the valve deflection time. According to the invention, one of the two injection valves available for a cylinder (i.e., the second injection valve in the first calibration operating mode, and the first injection valve in the second calibration operating mode) covers the full injection quantity (i.e., the specified target fuel quantity) to ensure a trouble-free combustion process, while the other injection valve...The other injector (the first injector in the first calibration mode, the second injector in the second calibration mode) is calibrated by activating it with very short (gradually increasing, i.e., from one injection interval to the next) actuation durations. According to the invention, this advantageously separates the function of the injectors for maintaining engine operation on the one hand, and the function of adapting the valve behavior, in particular for determining valve delay, on the other. This makes it advantageously possible, according to the invention, to evaluate and adapt the small-quantity behavior at a wide variety of operating points, especially also in dynamic operation. In particular, there is no dependence on specific operating points (such as steady-state operation) for carrying out the adaptation.Furthermore, it is advantageous according to the invention that there is no influence, or at least a lesser influence, from the exhaust gas(es) during the adaptation process, particularly compared to the use of split injection (i.e., a temporally successive division of the injection into an adaptation phase and an operational phase) when using only one injector. It is also advantageous according to the invention that an evaluation and adaptation of the valve behavior is possible when exclusively using short injection valve actuation times (instead of having to alternate between shorter and longer actuation times in dual injection), so that the actual small-quantity operation of the injection valve can be observed and adapted according to the invention.According to the invention, it is therefore also advantageously possible for the adaptation to be carried out more frequently (and even continuously in certain operating ranges), so that any possible temporal drift in the behavior of the injection valve or the injection valve needle can be detected early and repeatedly regulated.

[0006] The internal combustion engine used for the method according to the invention is in particular a gasoline engine with port fuel injection for a motor vehicle, preferably an automobile. The fuel used can be gasoline, ethanol, or a mixture. The internal combustion engine preferably comprises more than one cylinder, each cylinder comprising a combustion chamber with, for example, two intake valves, each intake valve preferably being assigned one or more separate injection valves.

[0007] Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0008] It is particularly preferred according to the invention that the predetermined target fuel quantity in the calibration operating mode corresponds to the sum of the first and second fuel quantities in the normal operating mode. This allows the first or second calibration operating mode to replace the normal operating mode. Furthermore, it is also advantageous according to the invention that the calibration control of the first injector in the first calibration operating mode or of the second injector in the second calibration operating mode is carried out such that, during successive operating cycles, the calibration control is initiated from such short control times that an opening movement of the first or second valve needle does not initially occur. This allows the valve delay time to be determined with particular accuracy.

[0009] According to the invention, it is advantageously possible to inject different quantities of fuel with high accuracy through the first and second injection valves over a wide range. It is also possible, according to the invention, to configure the first and second injection valves with respect to the design quantity of fuel that can be injected (under given operating conditions) at maximum rate (so-called quantity Q). STAT The injectors can be designed to be the same size or of different sizes. Designing the injectors to be of a uniform size (where the design quantity of fuel per injector is halved compared to the total amount of fuel to be injected) has the advantage that a larger number of injectors can be produced, resulting in corresponding cost savings.

[0010] Furthermore, the present invention relates to a system comprising an internal combustion engine and a control unit for controlling the internal combustion engine.

[0011] Exemplary embodiments of the present invention are shown in the drawings and explained in more detail in the following description. Brief description of the drawings

[0012] They show

[0013] Fig. 1 to Fig. 3 schematic representations of different distributions of a fuel quantity to be injected between two injection valves, and

[0014] Fig. 4 A schematic representation of a fuel injection system. Embodiments of the invention

[0015] In the various figures, identical parts are always marked with the same reference symbols and are therefore usually only named or mentioned once.

[0016] In Fig. Figure 1 is a schematic representation of the distribution of a total injection quantity for one cylinder of an internal combustion engine between two injection valves (i.e., a first injection valve) 21 and a second injector 22 ) shown. A total amount Q to be injected STAT With two injectors, the fuel quantity is achieved by, for example, each injector delivering 50% of the maximum injection quantity Q. STAT injects, which can be achieved, for example, with just one injection jet. The representation according to Fig. Figure 1 corresponds to an exemplary illustration of the normal operating mode of the internal combustion engine. In the lower part of the Fig. Figure 1 schematically shows the injection durations for the two injection valves, indicated by the designations "ti A" and "ti B" and two horizontally aligned bars. 21 , 22indicated. Here, one means for both injectors (i.e., for the first injector). 21 or the injector A and for the second injector 22 or the injector B) horizontal bar of equal length, so that both injectors are actuated for the same length of time (to open the valve needle).

[0017] In Fig. 2 and Fig. Figure 3 schematically illustrates the distribution of the total injection quantity for one cylinder of an internal combustion engine between two injectors such that the required total quantity of fuel is injected through only one of the injectors, while the other injector is calibrated. The representation according to the Fig. 2 and Fig. 3 corresponds to an exemplary illustration of the first calibration operating mode ( Fig. 2) or the second calibration operating mode ( Fig. 3) the internal combustion engine. In the lower part of the Fig. Figure 2 schematically shows the injection durations for the two injection valves, indicated by the designations "ti A" and "ti B" and two horizontally aligned bars. 21 , 22 indicated, i.e. the (shorter) actuation time ("ti A") of the first injection valve 21 The first calibration operating mode is very low, so that there may be no movement of the valve needle and thus no opening of the injector, while the (longer) actuation time ("ti B") of the second injector 22 In the first calibration operating mode, the injected fuel quantity is dimensioned such that it corresponds to the required fuel quantity at the respective operating point. In the lower part of the Fig. Figure 3 schematically shows the injection durations for the two injection valves, indicated by the designations "ti A" and "ti B" and two horizontally aligned bars. 21 , 22indicated, i.e. the (shorter) actuation time ("ti B") of the second injection valve 22 The second calibration operating mode is very low, so that there may be no movement of the valve needle and thus no opening of the injector, while the (longer) actuation time ("ti A") of the first injector 21 In the second calibration operating mode, the amount of fuel injected is dimensioned such that it corresponds to the amount of fuel required at the respective operating point.

[0018] In Fig. 4 is schematically a fuel supply system 10The invention depicts an internal combustion engine intended for use in a vehicle. The internal combustion engine typically has four cylinders and thus four combustion chambers, although a different number of cylinders and thus combustion chambers is also possible. This internal combustion engine is an embodiment in which the fuel, preferably gasoline, is not injected directly into the combustion chambers, but rather operates with port fuel injection. However, according to the invention, it is also possible in principle for the fuel to be injected directly into the combustion chambers.

[0019] The fuel is drawn from a container by a pump (not shown). 18 , in particular via a filter (not shown), into a pressure chamber or pressure reservoir 12 is being pumped.

[0020] To the pressure reservoir 12Fuel injectors are connected, which are designed to inject fuel into the combustion chambers or the intake manifolds of the combustion chambers. In this process, the Fig. 2 schematically illustrates the case of four cylinders and two injectors per cylinder, with each cylinder having one injector. 21 and another injector 22The invention features a different configuration with respect to the number of cylinders and the number of injectors per cylinder, for example, one injector per cylinder or more than two injectors per cylinder. In particular, the invention provides for two intake manifold injectors per intake port, so that fuel is injected into one intake manifold via two paths (so-called twin injection). According to the invention, these two injectors are controlled, in particular, by two separate electronic output stages, so that the two injectors are controlled either synchronously or individually, i.e., with different phases and / or durations. According to the invention, the control of the injectors is carried out by a control unit. 16 or a control unit 16 carried out.

[0021] At a specific operating point, the internal combustion engine requires a specific amount of fuel per cylinder, which, depending on the system design, corresponds to a specific injection time "ti" at the respective injection valve. In the "Twin Injection" system according to the invention (i.e., the use of at least one first injection valve) 21 and a second injector 22 The required amount of fuel per cylinder (or combustion chamber) is supplied via two injectors, primarily in the intake manifold. In normal operation, i.e., in a standard operating mode, both twin injectors (i.e., the fuel injectors) take over. 21 and 22 , the task of fuel metering, which in Fig. Figure 1 is shown. In adaptation mode, the function of both injectors is separated, which is indicated in the Fig. 2 and Fig. 3 is shown. For both the one in the Fig. 2 shown first calibration operating mode as well as for the one in the Fig. The second calibration operating mode shown in section 3 is performed via one of the two injection valves (in the first calibration operating mode, the second injection valve). 22 and in the first calibration operating mode, the first injector 21The first injector is operated to cover the injection quantity required at this operating point. The second injector (the first injector in the first calibration mode and the second injector in the second calibration mode) is activated with a very short actuation time. Initially, the needle of the injector operating with the short actuation time will not lift from the valve seat. The actuation time is then slowly increased until the needle finally lifts and, before reaching its upper limit, reverses direction and falls back onto the valve seat. Finally, an actuation time is reached and exceeded at which the valve needle also reaches its upper limit.According to the invention, the behavior of the valve needle is detected in particular by evaluating the behavior of current signals and / or voltage signals, especially by observing a negative voltage caused by the closing movement of the valve needle due to the induction effect in the magnetic circuit of the injection valve.

[0022] Once the adaptation of one injector is complete, the adaptation of the other injector can begin with the roles reversed; that is, the first calibration operating mode and the second calibration operating mode are identical, whereby (especially with the same design (same Q) STAT ) of the first and second injectors) the roles are simply reversed.

[0023] Of particular interest is the behavior of very short injection times. Here, the amount of fuel injected by the injector being adapted (i.e., the first injector in the first calibration operating mode, or the second injector in the second calibration operating mode) is zero or very small compared to the amount injected by the other injector, which supplies the amount of fuel necessary for the operating point. Therefore, the influence on the air-fuel ratio of the combustion chamber (i.e., the so-called lambda value of the combustion chamber) and thus the influence on engine roughness or exhaust gas emissions can be neglected.

[0024] Since one injector covers the entire injection quantity during the adaptation phase, adaptation can also occur during dynamic operation, as this only affects the injector covering the injection quantity, not the injector being adapted. This results in the adaptation process being independent of the engine's operating range and operating state, which increases robustness and opens up new degrees of freedom for carrying out the adaptation.

[0025] The present invention can be applied not only to so-called twin injection systems but also to systems with port fuel injection and gasoline direct injection (PDI systems), where, at operating points where one of the two injectors is capable of covering the entire quantity, the other injector can be adapted. The same applies to the use of so-called bi-fuel systems, where the different fuels are injected with different injectors. QUOTES INCLUDED IN THE DESCRIPTION

[0026] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0027] DE 102008044244 A1

[0002]

Claims

[1] Method for controlling an internal combustion engine, in particular a motor vehicle, wherein the internal combustion engine has at least one cylinder, wherein the internal combustion engine has at least one first injection valve per cylinder for fuel injection ( 21 ) and a second injector ( 22 ) has, wherein the first injector ( 21 ) a first valve needle and the second injector ( 22 ) has a second valve needle, wherein in a normal operating mode of the internal combustion engine – by activating the first injection valve ( 21 ) during an initial actuation period and the associated opening movement of the first valve needle, a predetermined initial amount of fuel is injected and – by activating the second injection valve ( 22) during a second actuation period and a corresponding opening movement of the second valve needle, a predetermined second quantity of fuel is injected, where a signal evaluation is carried out to detect the opening movement and / or the closing movement and / or the position of the first and second valve needles, characterized by that – in a first calibration operating mode of the internal combustion engine, a calibration control of the first injection valve ( 21 ) is carried out in such a way that the state of movement and / or the position of the first valve needle is detected, while at the same time the second injection valve is controlled ( 22 ) is carried out in such a way that a predetermined target amount of fuel is injected, or – in a second calibration operating mode of the internal combustion engine, a calibration control of the second injection valve ( 22) is carried out in such a way that at least the state of movement and / or the position of the second valve needle is detected, while during this time the first injection valve is actuated ( 21 ) is carried out in such a way that a predetermined target amount of fuel is injected. [2] Method according to claim 1, characterized by that the specified target fuel quantity in calibration operating mode corresponds to the sum of the first and second fuel quantities in normal operating mode. [3] Method according to any one of the preceding claims, characterized by that the calibration control of the first injection valve ( 21 ) in the first calibration operating mode or of the second injector ( 22) in the second calibration operating mode such that during successive operating cycles the calibration control is based on such short control times that an opening movement of the first or second valve needle does not initially occur. [4] Method according to any one of the preceding claims, characterized by that the internal combustion engine is controlled by a control unit ( 16 ) is controlled, with the first injector being used for fuel injection ( 21 ) via a first power stage and independently of that the second injection valve ( 22 ) is controlled via a second power amplifier. [5] Method according to any one of the preceding claims, characterized by that the first injector ( 21 ) and / or the second injector ( 22 ) is intended for intake manifold injection. [6] System with an internal combustion engine and a control unit ( 16) for controlling the internal combustion engine, wherein the internal combustion engine has at least one cylinder, wherein the internal combustion engine has at least one first injection valve per cylinder for fuel injection ( 21 ) and a second injector ( 22 ) has, wherein the first injector ( 21 ) a first valve needle and the second injector ( 22 ) has a second valve needle, wherein the internal combustion engine is configured to operate in a normal operating mode, wherein the internal combustion engine is configured to actuate the first injector ( 21 ) during an initial actuation period and the associated opening movement of the first valve needle, to inject a predetermined initial quantity of fuel and, by actuating the second injector ( 22) to inject a predetermined second quantity of fuel during a second actuation time and an associated opening movement of the second valve needle, wherein the internal combustion engine is configured such that a signal evaluation is carried out to detect the opening movement and / or the closing movement and / or the position of the first and second valve needles, characterized by – that the internal combustion engine is configured to operate in a first calibration operating mode, wherein the internal combustion engine is configured to perform a calibration control of the first injection valve ( 21 ) such that the state of movement and / or the position of the first valve needle is detected, whereby the second injection valve is controlled ( 22 ) is carried out in such a way that a predetermined target amount of fuel is injected, or – that the internal combustion engine is configured to operate in a second calibration operating mode, wherein the internal combustion engine is configured to perform a calibration control of the second injection valve ( 22 ) such that the state of movement and / or the position of the second valve needle is detected, whereby an actuation of the first injection valve ( 21 ) is carried out in such a way that a predetermined target amount of fuel is injected. [7] Computer program using programming code tools, characterized by that all steps of a method according to one of claims 1 to 5 are executed when the program is on a computing device or a control unit ( 16 ) expires. [8] Computer program product comprising program code means stored on a machine-readable medium for carrying out a method according to any one of claims 1 to 5, when the program is on a computing device or a control device (16 ) expires.

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