Method for controlling fuel injection in an internal combustion engine, control device, internal combustion engine and computer program product

Abstract

The present subject matter relates to a method and control device for reducing unburned hydrocarbon and particulate emissions of an internal combustion engine, especially at cold engine conditions. The problem to be solved is to provide an automatic generation of injection profiles taking into account the requirements of different combustion modes at different operating points of the internal combustion engine. The automatic generation of an injection profile is accomplished by controlling fuel injection with an injection profile including a plurality of fuel injections, the profile being generated by setting an injection signal to a positive value at predetermined times in an injection cycle when a calculated spray penetration length is less than or equal to a spray penetration length threshold, and resetting the injection signal to zero at predetermined times in an injection cycle when a calculated spray penetration length exceeds a spray penetration length threshold, until a fuel quantity calculated based on a previously generated fuel injection profile exceeds a predetermined fuel quantity.

Description

[Technical Field]

[0001] The present subject matter relates to a method, a control device, an internal combustion engine, and a computer program product for controlling fuel injection in an internal combustion engine, preferably a spark-ignition internal combustion engine, by an injection profile including multiple fuel injections generated according to a calculated spray penetration length of the injected fuel. [Background technology]

[0002] Future stringent legal requirements call for further reductions in emissions from internal combustion engines, especially during cold start periods. This requires both a reduction in raw emissions and early catalyst readiness. Rapid catalyst heating requires retarding ignition timing and injecting a small amount of fuel just before ignition. To reduce raw emissions, especially hydrocarbon and particulate emissions, it is essential to simultaneously avoid wall wetting in the combustion chamber. This is not only necessary during cold start periods, but is also a general requirement for fuel injection. Multiple fuel injection is known as an important means for solving the above problems. However, defining optimal injection profiles for different environmental conditions requires a high calibration effort. Therefore, there is a need to automatically determine the injection timing of multiple injections in relation to the different combustion modes used across the engine map. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,770,813 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent document 1 describes a method of reducing spray penetration that uses multiple injections and provides a residence time between successive injection events that allows each successive injection event to be independent of other successive events, such that the overall spray penetration of all injection events is reduced relative to the spray penetration of a single fluid injection event.

[0005] However, the teachings of the '666 patent do not provide for automatic generation of injection profiles, nor do they take into account different combustion modes that require injection timing to be matched with ignition timing. An objective of the described subject matter is to provide model-based generation of injection profiles that consider the requirements of different combustion modes at various operating points of an internal combustion engine. [Means for solving the problem]

[0006] The above object is solved by the subject matter of the independent claims. Further preferred developments are set out in the dependent claims.

[0007] The present invention includes a method for controlling fuel injection in an internal combustion engine (hereinafter also referred to as "engine" for short). Preferably, the engine may be a spark ignition engine. Most preferably, the engine may be a spark ignition engine with direct fuel injection.

[0008] An internal combustion engine has at least one cylinder, in which a combustion chamber is formed by a cylinder wall, a cylinder head, and a piston head. A piston reciprocates in the cylinder driven by a crankshaft. The piston may be connected to the crankshaft via a connecting rod. Preferably, the piston can move from bottom dead center (BTC) to top dead center (TDC) by a piston stroke s. The piston stroke s, which depends on the crank angle, can be determined by the following equation (1): where j represents the crank angle, r represents the stroke length of the crankshaft, and l represents the stroke length of the crankshaft. s represents the rod ratio.

[0009]

number

[0010] The engine includes at least one fuel injection device configured to inject fuel into a combustion chamber. Noi Preferably, at least one injector Noi The injector may be a high pressure injector configured to inject fuel directly into the combustion chamber, and may be actuated by a solenoid valve or a piezoelectric element.

[0011] Furthermore, the engine comprises at least one control device configured to control the fuel injection. Preferably, the control device may be an engine control unit (ECU). The control device may be integrated into the internal combustion engine or, alternatively, may be located in a position in the vehicle remote from the internal combustion engine, the control device and the internal combustion engine being connected via one or more signal lines. The control device may be the engine control unit (ECU) or one or more separate control devices. According to claimed subject matter, fuel injection comprises: At low loads and low speeds of the internal combustion engine, a stratified combustion mode is set as the combustion mode, in which multiple injections are performed during the compression stroke and the end of the injection cycle is immediately before the ignition timing of the internal combustion engine; At intermediate loads and speeds of the internal combustion engine, a homogeneous stratified combustion mode is set as the combustion mode, in which one or more injections are performed during the intake stroke, one or more injections are performed during the compression stroke, and the end of the injection cycle is before the ignition timing; At high loads and high speeds of the internal combustion engine, a homogeneous combustion mode is set as the combustion mode, in which one or more injections are performed during the intake stroke, the injection cycle ends before the end of the intake stroke, and no injection is required during the compression stroke; Determining a position of a piston depending on a crankshaft angle of the internal combustion engine; determining a spray penetration length threshold as a function of piston position and combustion mode; calculating the spray penetration length using a physical model that accounts for fuel pressure, fuel temperature, and combustion chamber conditions; At a given point in the injection cycle , total The calculated spray penetration length is controlled by comparing it to a spray penetration length threshold.

[0012] To avoid wetting of the combustion chamber walls and piston, the spray penetration length of the injected fuel must be shorter than the distance between the spray hole and the cylinder wall and the distance between the spray hole and the piston. The distance of the spray jet from the cylinder wall is taken into account when selecting an injector for a particular engine by performing so-called spray targeting, which indicates the position of the spray jet in the combustion chamber. This allows the required limit for the spray jet penetration length to be reduced to the distance between the spray orifice and the piston head, as explained below.

[0013] The spray penetration length of the injected fuel may depend on several parameters, the most important of which may be the fuel pressure and temperature in the combustion chamber, which may be taken into account in the physical model for calculating the spray penetration length described below.

[0014] According to the claimed method, the first predetermined time point for performing the comparison is the end of the injection cycle. The term "injection cycle" is to be understood as the region(s) of the engine operating cycle where injection should occur to generate torque and meet the requirements of a given combustion mode. The complete injection cycle, which may be independent of the combustion mode, can begin immediately after the exhaust valve closes and end just before the ignition timing. However, depending on the combustion mode, the injection cycle may vary. For example, in a homogeneous combustion mode, the injection cycle may end before the end of the intake stroke to achieve homogeneous cylinder filling. This means that in a homogeneous combustion mode, the end of the injection cycle may be, for example, before bottom dead center. In contrast, in a stratified combustion mode, the last injection event may end, for example, before the ignition timing. Starting the calculation at the end of the injection cycle takes into account the conditions of different combustion modes, which requires aligning the latest injection with the ignition.

[0015] A fuel injection profile including a plurality of fuel injections is generated based on a comparison of the calculated spray penetration length with a spray penetration length threshold by setting the injection signal to a positive value at predetermined times in the injection cycle when the calculated spray penetration length is less than or equal to the spray penetration length threshold and by setting the injection signal to a positive value at predetermined times in the injection cycle when the calculated spray penetration length exceeds the spray penetration length threshold. Resetting the injection signal to zero , Injection signal is calculated based on R fuel amount To be the sum of This is done by generating a fuel injection profile that includes multiple fuel injections. In other words, the injection timing and duration of the multiple injections can be generated by allowing injection only when the spray penetration length is equal to or less than a spray penetration length threshold representing the maximum allowable spray penetration length. A signal output by the control device to the injector representing the fuel injection profile can be generated by setting the injection signal to any positive value, such as 1 if the spray penetration length is acceptable and resetting the injection signal to zero if the spray penetration length is not acceptable. If the time between setting and resetting the injection signal is less than the minimum actuation time of the injector, the injection signal is set to zero in this range.

[0016] The fuel injection profile is generated until a fuel amount calculated based on the previously generated fuel injection profile exceeds a predetermined fuel amount, which may be the total amount of fuel required to satisfy torque and / or lambda control requirements. After the fuel injection profile is generated, the fuel injection profile is sent to the injector to perform injection.

[0017] The claimed method automatically calculates the complete injection profile, i.e., the number of injections and the start and end times of each injection for the following injection cycle. The calculation is performed in a backwards manner, starting from the end of the injection cycle and ending at the beginning of the injection event. This allows multiple injections to be adapted to different combustion modes, thereby simultaneously optimizing emissions and fuel consumption.

[0018] According to one aspect, the spray penetration length threshold may be determined as a function of the piston position and the predetermined combustion mode. As explained above, the method according to the present invention assumes an injector adapted to the combustion chamber, so that only the distance between the spray hole and the piston head needs to be taken into account when determining the spray penetration length threshold. The geometric threshold for the spray jet penetration length can be determined using the following equation (2):

[0019]

number

[0020] In equation (2), α represents the angle between the central axis of the spray jet and the central axis of the cylinder, and represents the distance between the injector spray hole and the top of the piston, which depends on the piston stroke s according to equation (1) and therefore on the crank angle j.

[0021] However, to additionally take into account the requirements of different combustion modes given in the engine maps, the spray penetration length threshold must be adapted. The predetermined combustion mode may be, for example, lean combustion with stratified cylinder charge, lean combustion with a mixture of homogeneous and stratified cylinder charge, and homogeneous combustion with stoichiometric cylinder charge.

[0022] The principle of stratified charge operation is to provide a sufficiently rich mixture for combustion near the spark plug and a very lean mixture in the rest of the cylinder. Stratified charge operation allows for reduced fuel consumption when operating at lower loads due to reduced pumping losses and an overall lean burn. To achieve stable ignition of the mixture near the spark plug, several injections are performed during the compression stroke, with the last injection occurring just before ignition. This means that the spray penetration length threshold can be set to zero, for example, during the intake stroke and the first half of the compression stroke, to include the requirements of the combustion mode in the generation of the fuel injection profile.

[0023] To take advantage of lean burn even at mid-load, this region of the engine map uses lean burn with a mixture of homogeneous and stratified cylinder charge. To achieve the homogeneous charge, one or more injections are performed during the intake stroke. The stratified mixture is then created with one or more additional injections during the second half of the compression stroke, up until just before ignition. Therefore, the spray penetration length threshold may be set to zero, for example, during the first half of the compression stroke. For homogeneous combustion, injection during the compression stroke is not required, so the spray penetration length threshold can be set to zero, for example, during the compression stroke.

[0024] According to one aspect, the spray penetration length of the injected fuel can be calculated using a physical model that takes into account all relevant effects such as fuel pressure and air pressure and temperature in the combustion chamber. This model is expressed in equation (3) below, where k is the fuel pressure in the combustion chamber p cyl , temperature T cyl and gas concentration x cyl where Dp is the difference between the fuel pressure and the cylinder pressure, t is the time from the start of injection, and a and b are weighting coefficients for the pressure difference Dp and the time t.

[0025]

number

[0026] The use of a physical model to determine the spray penetration length improves the robustness and extrapolation behavior of the calculation compared to map-based calibration.

[0027] Spout The duration / distance between the start of injection and the time when the spray achieves the spray penetration length threshold may be identified by using a map, which may be pre-calibrated via test data from injector spray experiments.

[0028] According to one aspect, the duration of the fuel injection profile between the falling edge of the injection signal reset to zero and the subsequent rising edge of the injection signal set to a positive value may be greater than a predetermined time threshold. In other words, the distance between the end of one injection and the start of the next injection may be greater than a predetermined time threshold. The predetermined time threshold may be the injector dwell time, or an additional offset may be added to the dwell time to further increase or decrease the distance between two injection events, as needed.

[0029] According to one aspect, the end of the injection cycle may be determined depending on a predetermined combustion mode related to the ignition timing of the internal combustion engine. As explained above, the duration of an injection cycle within the meaning of the claimed subject matter may depend on the combustion mode. To ensure optimal ignition and combustion stability, the end of the injection cycle may further be determined in relation to the ignition timing. This means that if the ignition timing is shifted, the complete injection profile is also automatically shifted to maintain a constant distance between the end of the last injection and ignition.

[0030] Most The rising edge determined as the first can characterize the end of the last injection, and the falling edge determined as the last can characterize the start of the first injection. . Spout The last falling edge of the injection signal may be determined as a function of a predetermined fuel quantity, as described below.

[0031] According to one aspect, From a given point in time The calculated fuel quantity / total amount of fuel based on the previously generated fuel injection profile is determined each time the injection signal is reset. First, the last falling edge of the fuel injection profile and , from a given point in time The fuel quantity / quantity of fuel for injection corresponding to the period between the previous rising edge can be calculated using a physical hydraulic model. In other words, the injection period is calculated based on the last falling edge. , from a given point in timeThe fuel quantity of the last injection, defined by the time between the previous rising edge, can then be calculated. From a given point in time until the sum of the previously calculated fuel amounts exceeds the predetermined fuel amount. From a given point in time This may be added to the total fuel amount previously calculated.

[0032] A physics-based model is used to calculate the mass flow rate (MFR) for each injection event, which can be expressed by equation (4) below:

[0033]

number

[0034] In equation (4), C d is the flow coefficient of the injector, A is the opening area of the injector, and r f denotes the fuel concentration, and Dp denotes the difference between the fuel pressure and the cylinder pressure. By integrating the mass flow rate (MFR) over the previously determined injection period, the fuel quantity for each injection can be calculated.

[0035] According to one aspect, the start of the first injection may be determined based on a difference between a predetermined fuel quantity and a calculated fuel quantity based on a previously generated fuel injection profile.

[0036] As mentioned above, the claimed method ensures that the total amount of fuel (sum of all single injection events) meets the predetermined fuel amount required, for example, from lambda or torque control. Therefore, the method checks the total amount of fuel after each calculation step and stops the calculation if the predetermined fuel amount is achieved. In this way, only the earliest injection event is used to adjust / control the predetermined fuel amount. This is advantageous because the earliest injection event has the greatest distance from the ignition event and therefore does not cause disturbances to the ignition behavior.

[0037] According to one aspect, the predetermined points in the injection cycle at which the fuel injection profile is determined are equidistantly spaced relative to the crankshaft angle of the internal combustion engine. The equidistant intervals may be, for example, 1° CA, 0.5° CA, 0.1° CA, depending on the computational resources and the required computational accuracy. In other words, the method is performed based on crank angle resolved calculations, which means that the method is independent of engine speed.

[0038] The claimed subject matter further includes a control device for an internal combustion engine configured to perform the above-described method or aspects thereof, and an internal combustion engine comprising the control device. In this context, "comprising the control device" means that the control device may be integrated into the internal combustion engine or, alternatively, may be located in a location in the vehicle remote from the internal combustion engine, and the control device and the internal combustion engine may be connected via one or more signal lines.

[0039] Additionally, the claimed subject matter includes a computer program product storable in a memory containing instructions that, when executed by a computer or computing unit, cause the computer to perform the above-described method or aspects thereof, as well as a computer-readable [storage] medium containing instructions that, when executed by a computer, cause the computer to perform the method or aspects thereof.

[0040] In summary, the claimed subject matter allows for reducing emissions of an internal combustion engine and simultaneously reducing its calibration effort by performing multiple injections based on a model-based, automatically generated fuel injection profile. Furthermore, when generating the fuel injection profile, the requirements of different combustion modes for multiple injections are taken into account.

[0041] The subject matter will be further explained below on the basis of at least one preferred example with reference to the accompanying exemplary and schematic drawings. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a schematic diagram of an example of a single-cylinder spark-ignition internal combustion engine; [Figure 2] 1 illustrates schematically the generation of a jetting profile according to the claimed method. [Figure 3] 1 shows a flowchart illustrating exemplary method steps of the claimed method. [Figure 4] FIG. 10 is a diagram showing an example of an engine map. [Figure 5] 10 illustrates exemplary different spray length penetration thresholds for each combustion mode according to the claimed method. [Figure 6] 10 shows examples of emission reductions achieved using different injection profiles according to the claimed method. DETAILED DESCRIPTION OF THE INVENTION

[0043] To provide context for the claimed subject matter, an example spark-ignition, single-cylinder combustion engine is shown schematically in Figure 1. Those skilled in the art will appreciate that the claimed subject matter is not limited to single-cylinder engines, but may be applied to engines having any number of cylinders.

[0044] The illustrated single-cylinder engine has a combustion chamber 1 formed by a cylinder wall 1a, a top of a piston 2, an intake valve 3, an exhaust valve 4 ,stomach The engine is equipped with a cylinder head (not shown) in which an injector 5 and an ignition plug 6 are arranged. The piston 2 can move in the cylinder by a piston stroke s from bottom dead center BTC to top dead center TDC.

[0045] stomachThe injector 5 and the spark plug 6 are electrically connected to a control device 7. The control device 7 can determine a fuel injection profile according to the claimed method and transmit it to the injector 5. The control device 7 can also control the ignition timing of the spark plug 6. The control device 7 can be integrated into the internal combustion engine or, alternatively, can be located in a location within the vehicle remote from the internal combustion engine, and the control device 7 and the internal combustion engine can be connected via one or more signal lines. The control device 7 can be an engine control unit (ECU) or one or more separate control devices.

[0046] In Figure 1, the piston is located at BDC, but it can be deduced from Figure 1 that when the piston is located near TDC, which is when injection occurs near the ignition timing, only a short fuel penetration length is allowed to avoid wetting the piston.

[0047] The phenomenon of wetting of the wall and piston is the result of the spray penetration length threshold SPL thres,0 This is shown schematically in Figure 2(a) in relation to the BDC. As long as the piston is located near BDC, piston wetting will not occur, but wall wetting may occur, which can be prevented by optimized spray targeting of the injector, as explained above. As the piston approaches top dead center, the spray can initially impinge on the outside of the piston, and as the piston continues to approach top dead center, the impingement point can move toward the piston center. The above-mentioned impingement of fuel on the piston surface is determined by the geometric spray penetration length threshold SPL, expressed by equation (2): thres,0 The parameters of equation (2) are shown in Figure 2(b), which shows a schematic example of a combustion chamber 1 having a piston 2, a spark plug 6, and an injector 5. As can be seen in Figure 2(b), the maximum allowable spray penetration length SPL thres,0 depends on the angle α between the central axis of the spray jet 7 and the central axis of the cylinder and the distance d between the spray hole of the injector and the top of the piston, and the distance d depends on the piston stroke s.

[0048] Figure 2(c) shows the spray penetration length calculated stepwise (SPL) and the geometric spray calculation length threshold (SPL) that results in the spray penetration length of multiple injections. thres,0 The illustrated example shows a comparison between the ignition timing at top dead center (TDC) and the F For combustion modes with catalyst heating, which are performed after the first injection, the spray penetration length (SPL) calculation starts at the ignition timing to determine the fuel injection profile for late multiple injections required to accelerate catalyst heating.

[0049] Figure 2(d) shows that the spray penetration length (SPL) calculated by the model using Equation (3) agrees very well with the experimental results, with the solid line representing the model data and the dashed line representing the experimental data. Furthermore, based on Figure 2(d), it can be shown how the start of injection can be determined via back-calculation. First, the start of hydraulic injection, φ, start,k and the spray is sprayed for a specific spray length SPL k The current position φ act The difference Δφ between the position φ act In Figure 2(d), the SPL curve is k The hydraulic injection φ is indicated by a vertical dashed line that intersects with the x-axis at the point where start,k The start of the SPL curve is also indicated by a vertical dashed line intersecting the x-axis at the point where the SPL curve begins to rise. The difference between the two points is the distance Δφ. For example, the distance Δφ can be determined from a map previously calibrated via test data from an injector spray experiment, e.g., Δφ=map(SPL k , RP, etc.) and then the current position φ actual and based on knowledge of the distance Δφ, for example, the current position φ actual The start of injection can be calculated by subtracting the distance Δφ from start、k =φ actual -Δφ.

[0050] FIG. 2(e) shows a schematic diagram of the timing and quantity of late staged injections resulting from the calculation of the allowable spray penetration length shown in FIG. 2(c). To improve catalyst heating, a fuel injection profile is shown that includes six injections in the region near TDC. The fuel injection profile is generated by applying an injection signal S at a predetermined point in the injection cycle where the calculated spray penetration length is equal to or less than the spray penetration length threshold. inj This may be generated by setting ,to a positive value and resetting the injection signal to zero at a predetermined point in the injection cycle where the calculated spray penetration length exceeds the spray penetration length threshold. From Figure 2(f), it can be derived that the mass fuel ratio MFRcalculated according to equation (4) also agrees very well with the experimental results.

[0051] 3 shows a flow chart illustrating the process steps of the claimed method as an example. In a first step S100, the spray penetration threshold SPL is calculated according to equation (2): thres In addition, the combustion mode may be taken into account, as described below in conjunction with Figure 5. In step S101, an injection counter k is set to zero, so that the crank angle j at which the calculation can start is the latest possible crank angle j. latest , i.e., the crank angle at which the injection cycle ends (S102). If the injection counter k>0, the crank angle for determining the next injection is set to the current crank angle j act The distance from may be set to a crank angle j, which corresponds to the residence time of the injector. This ensures that the distance related to the components between two injections is maintained. It is also possible to increase or decrease the crank angle between two consecutive injections. In step S104, an equidistant interval counter between calculation steps is set to i=1, and in step S105, the spray penetration length at crank angle j-1, i.e., the crank angle prior to the current crank angle, is calculated when the equidistant interval is 1° CA.

[0052] Calculated spray penetration length SPL k is the spray penetration length threshold SPL thres If it is smaller, the injection signal S injis set to 1 (S106), and the method proceeds to the next crank via step S106 to calculate the spray penetration length thereafter.

[0053] Calculated spray penetration length SPL k is the spray penetration length threshold SPL thres If so, the spray penetration length calculation for the current injection is terminated and the injection signal S inj is set to 0 (S108). Then, the start of the current injection event is determined to be the same as the calculated spray penetration length SPL k To calculate the start of the current injection event, the hydraulic injection φ start,k and a specific spray length SPL, which is preferably a predetermined value, e.g. k The spray has reached the current position φ act The model used can be a map-based structure that is calibrated via test data from injector spray experiments. Then, the hydraulic injection start SOI k is the equation explained in relation to Figure 2(d), φ start,k =φ actual Since the total hydraulic spray period is known, the fuel quantity Q model,k As explained above, the calculated fuel quantity Q can be calculated according to equation (4) based on the injection period (S110). model,k is the minimum fuel quantity Q of the injector min If so, no injection is generated and the method proceeds to the next crank angle via step S106.

[0054] Calculated fuel quantity Q model,k is the minimum fuel quantity Q of the injector min If it is greater than the calculated fuel quantity Q model,k is added to the previously calculated fuel quantity, and the sum of the calculated fuel quantities is equal to the predetermined fuel quantity Q total It is checked whether it is greater than or equal to the value.

[0055] The sum of the calculated fuel amounts is the predetermined fuel amount Q totalIf so, the method proceeds to step S111 to calculate the next injection, otherwise the generation of the fuel injection profile ends.

[0056] The claimed method, exemplarily depicted in Figure 3, allows for the automatic generation of a complete fuel injection profile that can be injected in a subsequent injection cycle. The method performs back-calculation and takes into account the requirements of various combustion modes and the constraints imposed by the injector.

[0057] The distribution of the different combustion modes across the engine map is shown in Figure 4. At low loads and speeds, a stratified combustion mode C3 with an overall air-fuel ratio of 1>1 can be implemented to reduce fuel consumption. Negative Load and middle At high loads and speeds, the so-called homogeneous stratified combustion mode C2 can be implemented to extend the benefits of lean mixtures to higher loads and speeds. degree In this case, homogeneous combustion mode C1 may be required to achieve the required engine power output.

[0058] FIG. 5 shows an example of the required fuel injection profile corresponding to each combustion mode C1 to C3 and the resulting spray penetration length threshold SPL. Each fuel injection profile is generated by applying the injection signal S inj This can be generated by setting a positive value, for example 1, and resetting the injection signal to zero at the point in the injection cycle where the calculated spray penetration length exceeds the spray penetration length threshold. In addition to any of the combustion modes C1 to C3, mode C4 may be executed to heat the catalyst after a cold start of the engine, and this must be additionally taken into consideration when generating the fuel injection profile.

[0059] In the example shown, the engine is homogeneous. combustionWhen operating in this mode, three injections are performed during the intake stroke. Since the last injection ends at BDC, the spray penetration length threshold SPLthres,C1 can be set to zero after BDC. In contrast, in the illustrated example, in the homogeneous stratified combustion mode C2, two injections are performed during the intake stroke and three injections are performed during the compression stroke. The most recent injection ends just before the ignition timing, e.g., just before the ignition timing, which means that the spray penetration length threshold SPLthres,C2 can be set to zero only in the first half of the compression stroke. For the stratified combustion mode C3, four injections are performed during the compression stroke, resulting in the spray penetration length threshold SPLthres,C3, which can be set to zero during the intake stroke and at the beginning of the compression stroke. For the catalyst heating mode, one or more injections are performed after TDC, just before the late ignition timing, e.g., just before the ignition timing. This means that a separate fuel injection profile for catalyst heating can be generated that can be combined with one of the other fuel injection modes depending on the selected combustion mode.

[0060] Geometric spray penetration length threshold SPL for different combustion modes thres,0 By modifying the spray penetration length threshold value SKL, it is possible to specifically consider the requirements of each combustion mode. thres By comparing only in the region of the engine operating cycle where potential injections are expected, the computational effort can be significantly reduced.

[0061] Figures 6(a) and 6(b) show examples of emission reductions achieved using different injection profiles according to the claimed method. Figure 6(a) shows the specific effective fuel consumption (be), nitrogen oxides (NOx), hydrocarbons (HC), and particulate counts for multiple injections, including three and five injections, compared to values measured using a single injection. Figure 6(b) shows various injection timings and durations, represented by injection current. A single injection occurs during the intake stroke, and three multiple injections also occur during the intake stroke. Meanwhile, five very short multiple injections are distributed between the intake and compression strokes, with three injections occurring during the intake stroke and two during the compression stroke. The last of the five injections occurs shortly before ignition timing.

[0062] From Figure 6(a), it can be deduced that generating a fuel injection profile according to the claimed method helps reduce emissions without affecting fuel consumption. In particular, hydrocarbons (HC) and particulate counts can be significantly reduced when performing multiple injections according to the claimed subject matter. While nitrogen oxides (NOx) are roughly the same for three and five injections, the injection profile shown in Figure 6(b) further reduces hydrocarbons (HC) and particulate counts (PN) with five injections.

[0063] In summary again, the claimed subject matter allows for reducing emissions of an internal combustion engine and at the same time reducing its calibration effort by performing multiple injections based on a model-based, automatically generated fuel injection profile. Furthermore, when generating the fuel injection profile, the requirements of the current combustion process for multiple injections are taken into account, which helps to significantly reduce the computational effort.

[0064] As will be appreciated by those skilled in the art, the disclosure described herein above and the accompanying drawings may be embodied as a method, an apparatus (including a device, a machine, a system, a computer program product, and / or any other apparatus), or combinations of the foregoing.

[0065] Accordingly, embodiments of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, which may be generally referred to herein as a "system."Furthermore, embodiments of the present disclosure may take the form of a computer program product on a computer-readable medium having computer-executable program code embodied in the medium.

[0066] Note that arrows may be used in the drawings to represent communications, transfers, or other activities involving two or more entities. A double-ended arrow generally indicates that activity can occur in both directions (e.g., a command / request in one direction and a corresponding reply in the other, or peer-to-peer communication initiated by either entity), although in some situations activity may not necessarily occur in both directions.

[0067] It should be noted that, although single-ended arrows may generally indicate exclusively or primarily unidirectional activity, in some circumstances such directional activity may actually involve bidirectional activity (e.g., a message from a sender to a receiver and an acknowledgment from the receiver to the sender, or the establishment of a connection before a transfer and the termination of the connection after a transfer). Thus, the types of arrows used in particular drawings to represent particular activities are illustrative and should not be considered limiting.

[0068] Aspects are described above with reference to flowchart illustrations and / or block diagrams of methods and apparatus, and with reference to some sample views of graphical user interfaces generated by the methods and / or apparatus. It will be understood that each block of the flowchart illustrations and / or block diagrams, and / or combinations of blocks in the flowchart illustrations and / or block diagrams, and graphical user interfaces, can be implemented by computer-executable program code.

[0069] Computer-executable program code may be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to produce a particular machine such that the program code, when executed by the processor of the computer or other programmable data processing apparatus, creates means for implementing the functions / acts / output specified in the flowcharts, one or more blocks of the block diagrams, illustrations, and / or written descriptions.

[0070] These computer-executable program codes may also be stored in a computer-readable memory that can instruct a computer or other programmable data processing apparatus to function in a particular manner, such that the program code stored in the computer-readable memory produces an article of manufacture including instruction means that implement the functions / acts / output specified in the flowcharts, block diagram block(s), figures, and / or written descriptions.

[0071] The computer-executable program code may also be loaded into a computer or other programmable data processing apparatus and cause a series of operational steps to be executed on the computer or other programmable apparatus to generate a computer-implemented process, such that the program code executing on the computer or other programmable apparatus provides steps for implementing the functions / operations / output specified in the flowcharts, block diagram block(s), figures, and / or written descriptions. Alternatively, steps or acts implemented by a computer program may be combined with steps or acts implemented by an operator or human to practice an embodiment.

[0072] It should be noted that terms such as "server" and "processor" may be used herein to describe devices that may be used in some embodiments and should not be construed as limiting to any particular device type unless the context otherwise requires. Thus, a device may include, but is not limited to, a bridge, router, bridge-router (brouter), switch, node, server, computer, appliance, or other type of device. Such devices typically include one or more network interfaces for communicating over a communications network and a processor (e.g., a microprocessor with memory and other peripherals and / or application-specific hardware) configured to perform the device functions accordingly.

[0073] Communications networks generally may include public and / or private networks, may include local area, wide area, metropolitan area, storage, and / or other types of networks, and may employ communications technologies including, but by no means limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

[0074] It should also be noted that devices may use communication protocols and messages (e.g., messages created, sent, received, stored, and / or processed by the devices), and such messages may be carried by a communication network or medium.

[0075] Unless the context requires otherwise, this disclosure should not be construed as limited to any particular communication message type, communication message format, or communication protocol. Thus, a communication message may generally include, but is not limited to, a frame, a packet, a datagram, a user datagram, a cell, or other type of communication message.

[0076] Unless the context requires otherwise, it will be understood that references to particular communications protocols are exemplary and that alternative embodiments may employ variations of such communications protocols (e.g., modifications or extensions of the protocols as may be made from time to time) or other protocols, either now known or developed in the future, as appropriate.

[0077] It should also be noted that logic flows may be described herein to demonstrate various aspects and should not be construed as limiting the present disclosure to any particular logic flow or logic implementation. The described logic may be divided into different logic blocks (e.g., programs, modules, functions, or subroutines) without changing the overall result.

[0078] In many cases, logic elements can be added, modified, omitted, executed in a different order, or implemented using different logic constructs (e.g., logic gates, loop primitives, conditional logic, and other logic constructs) without changing the overall result.

[0079] The present disclosure may be embodied in many different forms, including, but not limited to, computer program logic for use with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general-purpose computer), programmable logic for use with a programmable logic device (e.g., a field programmable gate array (FPGA) or other PLD), discrete components, an integrated circuit (e.g., an application-specific integrated circuit (ASIC)), or any other means including any combination thereof. Computer program logic implementing some or all of the described functionality is typically implemented as a set of computer program instructions that are converted into a computer-executable form, stored on a computer-readable medium, or the like, and executed by a microprocessor under the control of an operating system. Hardware-based logic implementing some or all of the described functionality may be implemented using one or more appropriately configured FPGAs.

[0080] Computer program logic implementing all or part of the functionality previously described herein may be embodied in various forms, including, but not limited to, source code form, computer executable form, and various intermediate forms (e.g., forms produced by an assembler, compiler, linker, or locator).

[0081] Source code may include a series of computer program instructions implemented in any of a variety of programming languages (e.g., object code, assembly language, or high-level languages such as Fortran, C, C++, JAVA, or HTML) for use with various operating systems or operating environments. Source code may define and use various data structures and communication messages. Source code may be in a computer-executable form (e.g., via an interpreter), or source code may be converted into a computer-executable form (e.g., via a translator, assembler, or compiler).

[0082] Computer executable program code for carrying out operations of embodiments of the present disclosure may be written in scripting or non-scripting programming languages such as Java (object oriented), Perl, Smalltalk, C++, etc. However, computer program code for carrying out operations of embodiments may also be written in conventional procedural programming languages, such as the "C" programming language or similar programming languages.

[0083] Computer program logic implementing all or part of the functionality previously described herein may run at different times (e.g., simultaneously) on a single processor, or may run at the same or different times on multiple processors, and may run under a single operating system process / thread or under different operating system processes / threads.

[0084] Thus, the term "computer process" can generally refer to the execution of a set of computer program instructions, regardless of whether different computer processes run on the same or different processors, and regardless of whether different computer processes run under the same operating system process / thread or different operating system processes / threads.

[0085] A computer program may be fixed in any form (e.g., source code form, computer executable form, or intermediate form) permanently or temporarily on a tangible storage medium such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), a personal computer card (e.g., a PC card), or other memory device.

[0086] A computer program may be embodied in any form within a signal that can be transmitted to a computer using any of a variety of communication technologies, including, but by no means limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

[0087] The computer program may be distributed in any form, such as on a removable storage medium accompanied by printed or electronic documentation (e.g., shrink-wrapped software), may be pre-loaded onto a computer system (e.g., system ROM or fixed disk), or may be distributed from a server or electronic bulletin board via a communications system (e.g., the Internet or World Wide Web).

[0088] Hardware logic (including programmable logic for use with a programmable logic device) implementing all or a portion of the functionality described herein above may be designed using conventional manual methods, or may be designed, captured, simulated, or documented electronically using a variety of tools, such as computer-aided design (CAD), hardware description languages (e.g., VHDL or AHDL), or PLD programming languages (e.g., PALASM, ABEL, or CUPL).

[0089] Any suitable computer readable medium may be utilized, including, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or medium.

[0090] More specific examples of computer-readable media include, but are not limited to, an electrical connection having one or more wires, or other tangible storage media such as a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a compact disc read-only memory (CD-ROM), or other optical or magnetic storage device.

[0091] The programmable logic may be permanently or temporarily fixed in a tangible storage medium such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), or other memory device.

[0092] The programmable logic may be embodied in signals that are transmittable to a computer using any of a variety of communication technologies, including, but by no means limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

[0093] The programmable logic may be distributed as a removable storage medium with printed or electronic documentation (e.g., shrink-wrapped software), may be preloaded into a computer system (e.g., on a system ROM or fixed disk), or may be distributed from a server or bulletin board via a communications system (e.g., the Internet or World Wide Web). Of course, some aspects may be implemented as a combination of both software (e.g., a computer program product) and hardware. Still other embodiments may be implemented entirely in hardware or entirely in software.

[0094] While several exemplary aspects have been described and illustrated in the accompanying drawings, it should be understood that such aspects are exemplary and that the embodiments are not limited to the specific configurations and arrangements shown and described, as various other changes, combinations, omissions, modifications, and substitutions are possible, in addition to those described in the preceding paragraphs.

[0095] Those skilled in the art will appreciate that various adaptations, modifications, and / or combinations of the presently described embodiments may be made. Accordingly, it should be understood that, within the scope of the appended claims, the present disclosure may be practiced other than as specifically described herein. For example, unless expressly stated otherwise, the steps of processes described herein may be performed in an order different from that described herein, and one or more steps may be combined, separated, or performed simultaneously.

[0096] Those skilled in the art will also appreciate, in light of this disclosure, that different embodiments or aspects described herein can be combined to form other embodiments. [Explanation of symbols]

[0097] 1 combustion chamber, cylinder 2 pistons 3 intake valve 4 Exhaust valve 5 injectors 6 Spark plugs 7 Spray Jet

Claims

1. 1. A method for controlling fuel injection in an internal combustion engine, the internal combustion engine comprising: at least one cylinder having a combustion chamber defined by a cylinder wall and a top of a piston, the piston being driven by a crankshaft to reciprocate within the cylinder; at least one injector for injecting fuel into the combustion chamber; at least one control device for controlling the fuel injection; At low loads and low speeds of the internal combustion engine, a stratified combustion mode is set as the combustion mode, in which multiple injections are performed during the compression stroke and the end of the injection cycle is immediately before the ignition timing of the internal combustion engine; At an intermediate load and an intermediate speed of the internal combustion engine, a homogeneous stratified combustion mode is set as the combustion mode in which one or more injections are performed during an intake stroke and one or more injections are performed during a compression stroke, and the injection cycle ends before an ignition timing; When the internal combustion engine is under high load and high speed, the combustion mode is set to a homogeneous combustion mode in which one or more injections are performed during an intake stroke, the injection cycle ends before the end of the intake stroke, and no injection during a compression stroke is required; determining a position of the piston depending on a crankshaft angle of the internal combustion engine; determining a spray penetration length threshold in response to the position of the piston and the combustion mode; calculating the spray penetration length using a physical model that accounts for fuel pressure, fuel temperature, and conditions in the combustion chamber; comparing the calculated spray penetration length to the spray penetration length threshold at a predetermined time point in the injection cycle, the first predetermined time point being the end of the injection cycle; setting an injection signal to a positive value at the predetermined time point in the injection cycle when the calculated spray penetration length is less than or equal to the spray penetration length threshold, and resetting the injection signal to zero at the predetermined time point in the injection cycle when the calculated spray penetration length exceeds the spray penetration length threshold; generating a fuel injection profile including a plurality of fuel injections such that the sum of fuel amounts calculated based on the injection signals is a predetermined fuel amount; transmitting the generated fuel injection profile to the injector to perform the injection; Controlled by,method.

2. 2. The method of claim 1, wherein the duration of the fuel injection profile between a falling edge by resetting the injection signal to zero and a subsequent rising edge by setting the injection signal to the positive value is greater than a predetermined time threshold.

3. A method as described in claim 1 or 2, wherein a fuel quantity corresponding to the period between the start and end of a single injection characterized each time the injection signal is reset to zero is calculated using a physical hydraulic model, and the sum of the fuel quantities is determined by adding the calculated fuel quantities each time the injection signal is reset to zero.

4. 2. The method of claim 1, wherein the predetermined points in the injection cycle at which the fuel injection profile is determined are spaced equidistantly with respect to a crankshaft angle of the internal combustion engine.

5. 1. A control device for an internal combustion engine, the internal combustion engine comprising: at least one cylinder having a combustion chamber defined by a cylinder wall and a top of a piston, the piston reciprocating within the cylinder driven by a crankshaft; and at least one injector configured to inject fuel into the combustion chamber; The control device is configured to perform the method of claim 1 .

6. An internal combustion engine, at least one cylinder having a combustion chamber defined by a cylinder wall and a top of a piston, said piston reciprocating within said cylinder driven by a crankshaft; at least one injector configured to inject fuel into the combustion chamber; An internal combustion engine comprising a control device according to claim 5.

7. A computer program product storable in a memory comprising instructions that, when executed by a computer, cause the computer to perform the method of claim 1.

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