Method and system for adjusting a direct fuel injector

Abstract

This application relates to methods and systems for adjusting direct fuel injectors, and discloses methods and systems for reducing direct injector dosing errors due to injection variability in a transition region of a direct injector map. Fuel injection, including the use of one or more direct injection fuel pulses and intake port injection fuel pulses, can be scheduled based on engine operating conditions including engine temperature and driver demand. In response to any of the direct injection fuel pulses having a pulse width that lies in a high variability transition region of the direct injector, the fuel injection can be adjusted by an adjustment to the number of injections and / or split ratio so as to not operate in the transition region.

Description

Technical Field

[0001] The present invention generally relates to methods and systems for adjusting the operation of direct fuel injectors in internal combustion engines. Background Technology

[0002] Internal combustion engines can utilize direct fuel injection, in which fuel is injected directly into the engine cylinders to improve mixture preparation and reduce cylinder charge temperature. Direct fuel injection can replace or be added to port fuel injection, in which fuel is injected into the intake port upstream of the intake valve of the engine cylinder. The amount of time the direct fuel injector is activated (direct injection pulse width) can be a function of the fuel pressure supplied to the injector, engine speed, and engine load. To take advantage of the benefits of direct injection, complete control over the pulse width range of the direct fuel injector can be advantageous. This includes a wide variety of operating conditions, including but not limited to fuel rail pressure, engine speed, and mass fuel flow.

[0003] However, the performance of solenoid-controlled direct fuel injectors may be limited in terms of their flow characteristics between the ballistic region and the full-lift region. This region is often referred to as the transition region of direct fuel injectors. In this region, the fuel injector flow rate is inaccurate and unpredictable, resulting in shot-to-shot and component-to-component variability. For example, a direct fuel injector may deliver more or less fuel than expected in the transition region. Furthermore, the variability in the transition region may not exhibit a linear trend, making it difficult to detect and compensate for this variability. Injector variability can lead to cylinder torque imbalance due to different amounts of fuel injected into each cylinder, and can also result in higher tailpipe emissions and reduced fuel economy due to the inability to accurately meter the fuel to be injected into each cylinder. Therefore, there may be engine operating regions where direct fuel injectors cannot adequately meet NVH, drivability, and emissions requirements.

[0004] Various methods have been developed to reduce the variability of direct injectors. Ranga et al., in US20160153391, illustrate an exemplary method. In this method, direct fuel injection is divided into multiple injections, one of which has a sufficiently small pulse width to deliver within the impact region of the direct injector. The injector's transfer function is determined based on the lambda value and the split ratio. Subsequent direct injections are then adjusted based on the determined transfer function.

[0005] However, the inventors of this paper have recognized potential problems with the '391 method and other related methods. As an example, the variability of the injector in the transition region remains unmapped. Various methods update the transfer function based on the known injector variability in the impact region, where the injector pulse width is smaller than that in the transition region. However, for larger injector pulse widths located outside the impact region but smaller than those in the lift region, refueling errors may still exist. Therefore, NVH, drivability, and emissions issues may persist.

[0006] As an example, in the impact zone, increasing the electrical pulse width of the fuel injector increases the amount of mass delivered. While there may be some variability in this increase, this variability is known and can be adjusted in terms of the shape or displacement of the slope in the impact zone to account for it. However, in the transition zone, an increased pulse width may actually result in a reduction in the mass of fuel injected. Therefore, it may not be possible to simply shift or change the shape of the slope in the transition zone. The variability is exacerbated because the slope in the transition zone is different for each injector and varies significantly between injections. Summary of the Invention

[0007] In one example, the above problem can be addressed by a method for an engine that includes: estimating an initial ratio of intake manifold fuel to direct fuel injection during the combustion cycle based on engine operating conditions; and updating the initial ratio to move the direct fuel injection out of the transition region in response to the direct fuel injection at the initial ratio being located in a transition region of the direct fuel injector map. In this way, the variability of direct injectors in the transition region can be resolved.

[0008] As an example, the engine controller can determine the initial fuel injection profile based on engine operating conditions. This could include, for example, the total fuel mass to be delivered, and the split ratio of the portion of the total fuel mass to be delivered via direct injection relative to the portion of the total fuel mass to be delivered via duct injection. The direct fuel injector pulse width to be commanded is then determined based on the split ratio (including based on the fuel mass to be delivered to the direct injector and based on the fuel rail pressure). If the direct injection pulse width is determined to be within the transition region of the direct injector, the controller can update the injection profile to operate outside the transition region. Specifically, the controller can modify the fuel mass delivered to the direct injector based on the position of the direct injection pulse width within the transition region and its distance from adjacent impact and lift regions, thereby updating the split ratio. For example, the fuel mass of direct injection near the impact region can be reduced to move the direct injection from the transition region to the impact region, while correspondingly increasing the fuel mass of duct injection. As another example, the fuel mass of direct injection near the lift region can be increased to move the injection from the transition region to the lift region, while correspondingly decreasing the fuel mass of duct injection. This allows for adjustment of the mass of all injected fuel in order to maintain the total fuel mass.

[0009] In a further example, additionally or optionally, the number of direct injections and the split ratio of the direct injection fuel (the ratio of the mass of direct injection fuel delivered in each injection within multiple injections) can be updated. For example, in the case of delivering direct injection fuel within multiple direct injections, the split ratio can be increased or decreased to shift the direct injection pulse width out of the transition region. As another example, the number of direct injections can be increased or decreased. In a further example, a combination of the above methods can be selected. The selection can be based on engine operating conditions (such as engine speed constraints and NVH constraints).

[0010] This method reduces the variability of the direct injector. The advantage of adjusting the direct injection fuel quality based on the position of the injection pulse width on the direct injector operating region map is that the direct fuel injector cannot be operated under pulse widths where nonlinear fuel injector behavior occurs. Simultaneously, the overall fuel quality can be maintained. Since operation is performed outside the transition region of the direct injector, engine air-fuel ratio and torque errors can be reduced. Furthermore, the method can reduce engine emissions and NVH (noise, vibration, and harshness) issues. Overall, drivability is improved.

[0011] It should be understood that the above description of the invention is provided to introduce, in a simplified form, the conceptual options further described in the detailed embodiments. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings recorded above or in any part of this disclosure. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the engine system.

[0013] Figure 2 A high-level flowchart is shown for an exemplary method of adjusting the fuel injection distribution to move direct injector operation outside the transition region.

[0014] Figure 3 A high-level flowchart illustrates an exemplary method for updating the quality of direct injection fuel in order to move direct injector operation outside the transition zone.

[0015] Figure 4 An exemplary direct injector performance map is shown.

[0016] Figures 5-6 An example of operating a direct injector outside the transition zone is shown.

[0017] Figures 7-8 An example of operating a direct injector outside the transition zone is shown by adjusting the fuel mass of each injection in multiple direct injections.

[0018] Figures 9-10 An example of operating a direct injector outside the transition zone is shown by adjusting the split ratio of fuel delivered via direct injection relative to fuel delivered via intake port injection.

[0019] Figure 11 An exemplary fuel injection distribution that can be applied to operate a direct injector outside the transition zone is shown. Detailed Implementation

[0020] The following description relates to methods for improving engine systems (such as...) Figure 1 Systems and methods for improving the performance of direct injectors in engine systems. This can be based on, for example... Figures 2-3 The exemplary method's control routine operates the engine via a controller in a transition region where injector variability is high. Figure 4 Externally operated direct fuel injectors. This can be achieved by adjusting the split ratio of inlet-injected fuel to direct-injected fuel, the amount of direct injection, and the split ratio of direct-injected fuel. Figures 5-11One or more of the following can be used to update the fuel injection distribution:

[0021] Figure 1 An example of a combustion chamber or cylinder of an internal combustion engine 10 coupled in a vehicle 5 is depicted. In some examples, vehicle 5 may be a hybrid vehicle having multiple torque sources available for one or more wheels 55. In other examples, vehicle 5 is a conventional vehicle with only an engine, or an electric vehicle with only one or more electric motors. In the example shown, vehicle 5 includes an engine 10 and an electric motor 52. The electric motor 52 may be a motor or a motor / generator (M / G). When one or more clutches 56 are engaged, the crankshaft 140 of engine 10 and electric motor 52 are connected to the wheels 55 via a transmission 54. In the depicted example, a first clutch 56 is disposed between crankshaft 140 and electric motor 52, and a second clutch 56 is disposed between electric motor 52 and transmission 54. Controller 12 may send signals to the actuator of each clutch 56 to engage or disengage the clutch, thereby connecting or disconnecting crankshaft 140 from electric motor 52 and its connected components, and / or connecting or disconnecting electric motor 52 from transmission 54 and its connected components. Transmission 54 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0022] Motor 52 receives power from traction battery 58 to provide torque to wheel 55. Motor 52 can also operate as a generator to provide power, for example, during braking operations, to charge battery 58.

[0023] Engine 10 can be at least partially controlled by a control system including controller 12, and by input control from vehicle operator 130 via input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Cylinder (also referred to herein as a "combustion chamber") 14 of engine 10 may include a piston 138 positioned therein on a combustion chamber wall 136. Piston 138 may be coupled to crankshaft 140 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of the passenger vehicle via a transmission system. Additionally, a starter motor (not shown) may be coupled to crankshaft 140 via a flywheel to enable starting operation of engine 10.

[0024] Cylinder 14 receives intake air through a series of intake passages 142, 144, and 146. In addition to cylinder 14, intake passage 146 may also communicate with other cylinders of engine 10. In some examples, one or more intake passages may include a supercharging device (such as a turbocharger or supercharger). For example, Figure 1An engine 10 equipped with a turbocharger is shown, the turbocharger comprising a compressor 174 disposed between intake passages 142 and 144, and an exhaust turbine 176 disposed along an exhaust passage 148. The exhaust turbine 176 may at least partially power the compressor 174 via a shaft 180, wherein the booster is configured as a turbocharger. However, in other examples, such as engine 10 equipped with a supercharger, the exhaust turbine 176 may optionally be omitted, wherein mechanical input from a motor or engine may power the compressor 174. A throttle valve 162 including a throttle plate 164 may be disposed along the engine's intake passages to change the flow rate and / or pressure of the intake air supplied to the engine cylinders. For example, as Figure 1 As shown, the throttle valve 162 can be positioned downstream of the compressor 174, or alternatively, it can be positioned upstream of the compressor 174.

[0025] In addition to cylinder 14, exhaust passage 148 may also receive exhaust gas from other cylinders of engine 10. Exhaust sensor 128 is shown as an exhaust passage 148 coupled upstream of emission control device 178. For example, sensor 128 may be selected from a variety of suitable sensors for providing exhaust air / fuel ratio indication, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust oxygen), a dual-state oxygen sensor or EGO (as depicted), HEGO (heated EGO), NOx, HC, or CO sensor. Emission control device 178 may be a three-way catalytic converter (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0026] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown to include at least one intake lift valve 150 and at least one exhaust lift valve 156 located in the upper region of cylinder 14. In some examples, each cylinder of engine 10 (including cylinder 14) may include at least two intake lift valves and at least two exhaust lift valves located in the upper region of cylinder.

[0027] Controller 12 can control intake valve 150 via actuator 152. Similarly, controller 12 can control exhaust valve 156 via actuator 154. During certain conditions, controller 12 can change the signals provided to actuators 152 and 154 to control the opening and closing of the corresponding intake and exhaust valves. The positions of intake valve 150 and exhaust valve 156 can be determined by the corresponding valve position sensors (not shown). The valve actuators can be electrically actuated, cam-actuated, or a combination thereof. Intake valve timing and exhaust valve timing can be controlled simultaneously, or any of the following possibilities can be used: variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing. Each cam actuation system can include one or more cams and can utilize one or more of the following: cam profile conversion (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which can be operated by controller 12 to change valve operation. For example, cylinder 14 may alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation including CPS and / or VCT. In other examples, the intake and exhaust valves may be controlled by a common valve actuator or actuation system, or a variable valve timing actuator or actuation system.

[0028] Cylinder 14 may have a compression ratio, which is the ratio of the volume of piston 138 at bottom dead center to the volume of piston 138 at top dead center. In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples using different fuels, the compression ratio may increase. This may occur, for example, when using fuels with higher octane ratings or fuels with higher potential enthalpy of vaporization. If direct injection is used, the compression ratio may also increase due to the effect of direct injection on engine knock.

[0029] In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. In a selected operating mode, ignition system 190 may provide an ignition spark to combustion chamber 14 via spark plug 192 in response to a spark advance signal SA from controller 12. However, in some embodiments, spark plug 192 may be omitted, such as when engine 10 can initiate combustion by automatic ignition or by fuel injection (as is the case in some diesel engines).

[0030] In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors for supplying fuel thereto. As a non-limiting example, cylinder 14 is shown including two fuel injectors 166 and 170. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. Fuel system 8 may include one or more fuel tanks, fuel pumps, and fuel rails. Fuel injector 166 is shown directly coupled to cylinder 14 for injecting fuel directly therein in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic actuator 168. In this manner, fuel injector 166 provides so-called direct injection of fuel into combustion cylinder 14 (hereinafter referred to as "DI"). Although... Figure 1 An injector 166 is shown positioned to one side of cylinder 14, but it can alternatively be located on top of the piston, such as near spark plug 192. This location can improve mixing and combustion when the engine is operating with alcohol-based fuels due to the lower volatility of some alcohol-based fuels. Alternatively, the injector can be located on top of and near the intake valve to improve mixing. Fuel can be delivered from the fuel tank of fuel system 8 to the fuel injector 166 via a high-pressure fuel pump and fuel rail. Furthermore, the fuel tank can have a pressure transducer that provides a signal to controller 12.

[0031] In some examples, the direct fuel injector 166 may be solenoid-controlled, where the amount of fuel delivered by the injector can be adjusted by changing the pulse width signal of the solenoid command coupled to the fuel injector. The inventors have recognized that, between the impact region and the full-lift region of injector operation, a solenoid-controlled direct injector may have unpredictable flow characteristics in the transition region of the direct fuel injector. Specifically, in this region, the flow rate of the fuel injector can be inaccurate and unpredictable, resulting in variability between injections and between components. To reduce cylinder torque output imbalance and undesirable tailpipe emissions due to injector variability, the engine controller can operate the direct injector outside the transition region. (See reference...) Figure 2 In detail, the engine controller can determine the fuel injection distribution, which includes the mass of fuel to be delivered through the direct injectors, the number of direct injections at a given fuel injection event, and the fuel split ratio in each injection of said number of direct injections. A pulse width signal can then be determined for each injection. If the pulse width signal of any direct injection falls into the transition region of the direct injector, the fuel injection distribution can be updated. Specifically, the pulse width signals of all direct injections can be adjusted to operate the direct injectors outside the transition region. For example, the mass of fuel in a given direct injection can be increased or decreased, the number of direct injections can be increased or decreased, and / or the fuel split ratio in the direct injection can be increased or decreased.

[0032] return Figure 1 In a configuration providing so-called port fuel injection (hereinafter referred to as "PFI") into the intake port upstream of cylinder 14, fuel injector 170 is shown arranged in intake passage 146 rather than in cylinder 14. Fuel injector 170 can inject fuel received from fuel system 8 in proportion to the pulse width of signal FPW-2 received from controller 12 via electronic actuator 171. It should be noted that a single actuator 168 or 171 can be used for both fuel injection systems, or multiple actuators can be used as depicted (e.g., actuator 168 for fuel injector 166 and actuator 171 for fuel injector 170).

[0033] In alternative examples, each of fuel injectors 166 and 170 may be configured as a direct fuel injector for injecting fuel directly into cylinder 14. In yet another example, each of fuel injectors 166 and 170 may be configured as a port fuel injector for injecting fuel upstream of intake valve 150. In still some other examples, cylinder 14 may include only a single fuel injector configured to receive a relatively varying amount of different fuels as a fuel mixture from the fuel system, and also configured to inject such fuel mixture directly into the cylinder as a direct fuel injector, or to inject such fuel mixture upstream of the intake valve as a port fuel injector. Therefore, it should be understood that the fuel system described herein should not be limited to the specific fuel injector configurations described herein by way of example.

[0034] Fuel can be delivered to the cylinder by two injectors during a single cycle of the cylinder. For example, each injector can deliver a portion of the total fuel injected for combustion in cylinder 14. Furthermore, the distribution and / or relative amount of fuel delivered from each injector can vary with operating conditions such as engine load, knock, and exhaust temperature, as described below. Intake port injection fuel can be delivered during an intake valve opening event, an intake valve closing event (e.g., generally before the intake stroke), and both during intake valve opening and closing operations. Similarly, direct injection fuel can be delivered, for example, during the intake stroke and partly during the preceding exhaust stroke, and during the intake stroke and partly during the compression stroke. Therefore, even for a single combustion event, the injected fuel can be injected at different timings from the intake port injector and the direct injector. Furthermore, for a single combustion event, multiple injections can be performed on the delivered fuel in each cycle. Multiple injections can be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0035] As mentioned above, Figure 1Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder can similarly include its own set of intake / exhaust valves, (multiple) fuel injectors, spark plugs, etc. It should be understood that engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Furthermore, each of these cylinders can include components manufactured by… Figure 1 Some or all of the various components described and depicted with reference to cylinder 14.

[0036] Fuel injectors 166 and 170 can have different characteristics. These include size differences; for example, one injector may have a larger injection orifice than the other. Other differences include, but are not limited to, different spray angles, different operating temperatures, different aiming, different injection timings, different spray characteristics, and different positions. Furthermore, different effects can be achieved depending on the fuel distribution ratio injected in injectors 170 and 166.

[0037] The fuel tank in fuel system 8 can hold fuels of different fuel types, such as fuels with different fuel qualities and different fuel compositions. These differences may include different alcohol contents, different water contents, different octane numbers, different heats of vaporization, different fuel blends, and / or combinations thereof. An example of fuels with different heats of vaporization may include gasoline as a first fuel type with a lower heat of vaporization and ethanol as a second fuel type with a higher heat of vaporization. In another example, the engine may use gasoline as the first fuel type and an alcohol-containing fuel blend such as E85 (which is approximately 85% ethanol and 15% gasoline) or M85 (which is approximately 85% methanol and 15% gasoline) as the second fuel type. Other feasible substances include water, methanol, mixtures of alcohol and water, mixtures of water and methanol, mixtures of alcohols, etc.

[0038] In yet another example, both fuels can be alcohol blends with different alcohol compositions. The first fuel type can be a gasoline-ethanol blend with a lower alcohol concentration, such as E10 (which contains approximately 10% ethanol), while the second fuel type can be a gasoline-ethanol blend with a higher alcohol concentration, such as E85 (which contains approximately 85% ethanol). Furthermore, the first and second fuels can also differ in other fuel qualities, such as temperature, viscosity, octane number, etc. Additionally, the fuel characteristics of one or both fuel tanks may vary frequently, for example, due to daily changes in fuel tank refills.

[0039] Controller 12 in Figure 1The controller 12 is shown as a microcomputer, including a microprocessor unit 106, an input / output port 108, an electronic storage medium for executable programs and calibration values ​​(shown in this particular example as a non-transient read-only memory chip 110 for storing executable instructions), a random access memory 112, a non-fail-to-recover memory (KAM) 114, and a data bus. In addition to the signals previously discussed, the controller 12 may also receive various signals from sensors coupled to the engine 10, including the following measurements: sensed mass airflow (MAF) from mass airflow sensor 122; engine coolant temperature (ECT) from temperature sensor 116 coupled to cooling manifold 118; surface ignition sensing signal (PIP) from Hall effect sensor 120 (or other type) coupled to crankshaft 140; throttle position (TP) from throttle position sensor; and absolute manifold pressure signal (MAP) from sensor 124. The controller 12 can generate an engine speed signal RPM based on the PIP signal. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of vacuum or pressure in the intake manifold.

[0040] Controller 12 from Figure 1 Various sensors receive signals and employ Figure 1 Various actuators are used to adjust engine operation based on received signals and instructions stored in the controller's memory. For example, the controller can adjust the fuel pulse width signal for direct fuel injector commands to operate the direct injector outside the injector's transition region.

[0041] In this way, Figure 1The components implement an engine system comprising: an engine cylinder; a direct injector for fueling the cylinder; and a controller having computer-readable instructions stored in a non-transient memory for: estimating an initial fuel injection distribution of the cylinder's combustion cycle based on engine speed-load and engine temperature, the initial fuel injection distribution comprising a plurality of direct injection fuel pulses, at least one of the plurality of direct injection fuel pulses having a pulse width in the transition region of the direct injector; during a first condition, modifying the initial fuel injection distribution to a first modified fuel injection distribution having a smaller number of the plurality of direct injection fuel pulses, each of the smaller number of the plurality of direct injection fuel pulses having a smaller pulse width in the lift region of the direct injector; and during a second condition, modifying the initial fuel injection distribution to a second modified fuel injection distribution, wherein the pulse width of a first group of the plurality of direct injection fuel pulses decreases to the impact region of the direct injector, while the pulse width of a second group of the plurality of direct injection fuel pulses increases to the full lift region of the direct injector, while maintaining the number of the plurality of direct injection fuel pulses, wherein the total direct injection fuel mass in each of the first modified fuel injection distribution and the second modified fuel injection distribution is the same as the fuel mass in the initial fuel injection distribution. In one example, during the first condition, if a solution cannot be found by adjusting the fuel mass due to the impact injection being below the minimum pulse width of the fuel injector, the fuel mass can be merged. A minimum pulse width must exist in the impact region because, in some cases, small fuel pulses are too inaccurate between injections and between injectors, and the risk of the injector failing to open may increase. The initial fuel injection distribution may include an initial number of direct injection fuel pulses, and the modification during each of the first and second conditions is based on the initial number of direct injection fuel pulses, and further on the relationship between the pulse width of at least one of the multiple direct injection pulses and the upper limit of the pulse width in the impact region and the lower limit of the pulse width in the lift region. The system may also include an intake port injector for fueling the cylinder, wherein the controller includes additional instructions for modifying the initial fuel injection distribution to a third modified fuel injection distribution under the third condition. This includes adjusting the total direct injection fuel mass to move the pulse width of at least one of the multiple direct injection fuel pulses out of the transition region of the direct injector, and adjusting the intake port injection fuel mass based on the adjusted direct injection fuel mass.

[0042] Figure 1The component also implements an engine system comprising: an engine cylinder; a direct injector for fueling the cylinder; an intake manifold injector for fueling the cylinder; and a controller having computer-readable instructions stored in a non-transient memory for: estimating an initial fuel injection distribution for the combustion cycle of the cylinder based on engine speed-load and engine temperature, the initial fuel injection distribution including an initial split ratio of directly injected fuel to intake manifold fuel delivered by a plurality of direct injection fuel pulses, at least one of the plurality of direct injection fuel pulses having a pulse width in a transition region of the direct injector; and modifying the initial fuel injection distribution to change the split ratio of directly injected fuel to intake manifold fuel such that at least one of the plurality of direct injection fuel pulses is moved out of the transition region. The modification may include: increasing or decreasing the intake manifold fuel mass relative to the total direct injection fuel mass based on the relationship between the pulse width of at least one of the plurality of direct injection pulses and an upper limit of the pulse width of the impact region of the direct injector and a lower limit of the pulse width of the lift region of the direct injector. Reducing the total direct injection fuel mass may include reducing the number of multiple direct injection fuel pulses to move the pulse width of each of the reduced number of direct injection fuel pulses into the lift region, and increasing the total direct injection fuel mass includes increasing the number of multiple direct injection fuel pulses to move the pulse width of each of the increased number of direct injection fuel pulses into the impact region.

[0043] Now go to Figure 2 An exemplary method 200 for correcting the fuel injection distribution to operate the direct injector outside the transition region of the direct injector is shown. Figure 2 The method can be included as executable instructions stored in non-transient memory. Figure 1 In the system. Furthermore. Figure 2 The method can provide Figures 5-11 The operating procedure. Based on instructions stored in the controller's memory and combined with data from sensors in the engine system (such as those mentioned above). Figure 1 The controller can execute instructions for performing method 200 and the remaining methods included herein, based on signals received by the described sensors. According to the methods described below, the controller can employ the engine actuators of the engine system to adjust engine operation.

[0044] At point 202, the method includes estimating and / or measuring engine operating conditions. These operating conditions may include, for example, engine speed, engine load, engine temperature (e.g., inferred from engine coolant temperature), exhaust temperature, catalyst temperature (Tcat), desired torque, boost level, dilution requirements, etc.

[0045] At 204, the method includes determining an initial fuel injection distribution based on estimated engine operating conditions. Determining the initial fuel injection distribution includes, at 206, determining the overall split ratio of fuel to be delivered via direct injection (DI) relative to fuel to be delivered via port fuel injection (PFI). The controller may determine the total mass of fuel to be delivered on a given combustion cycle based on driver torque demand and engine speed-load, and then determine the proportion of that total fuel mass to be delivered via direct injection relative to the proportion delivered via port fuel injection. As an example, during engine cold starts, when the estimated engine coolant temperature before combustion begins in the engine is below a threshold (such as below the ignition temperature of the exhaust catalyst), a larger proportion of the fuel mass may be delivered as port fuel injection relative to direct injection (at least for multiple combustion events since the engine has been started from a standstill) to reduce particulate emissions and cold-start engine roughness caused by direct injection. In contrast, during engine hot starts, when the estimated engine coolant temperature is above a threshold before combustion begins in the engine, a larger proportion of the fuel mass can be delivered as direct injection relative to port injection (at least for multiple combustion events since the engine started from a standstill) to take advantage of the higher performance and charging-cooling effect of direct injection. It should be understood that in other examples, the entire commanded fuel mass may be delivered either via port injection alone or via direct injection alone.

[0046] In another example, the initial fuel injection distribution can be based on combustion chamber temperature. Large DI injections (such as when the DI fuel mass is above a threshold amount) can impact the combustion chamber walls / piston and produce particulate emissions. Therefore, when the combustion chamber temperature is high, the split ratio can be adjusted to reduce the DI fuel mass portion and increase the PFI fuel mass portion. As yet another example, the maximum flow limit of the injectors can be considered in the initial fuel injection distribution, especially when the injectors are cold and fuel from both injectors is needed to deliver the total fuel mass required to start the engine. This may be particularly true when dealing with an increased percentage of fuel ethanol. In yet another example, engine start-up time can be considered when determining the initial fuel injection distribution. DI injectors can inject during the compression stroke, allowing the engine to start on earlier cylinders, thus reducing start-up time. Therefore, when a shorter start-up time is required, a larger portion of the total fuel mass can be delivered via direct injection. As yet another example, the flow rate of the high-pressure fuel pump (HPP) coupled to the direct injectors can be considered when determining the initial fuel injection distribution. If the DI injector may cause HPP to overflow, then a significant portion of the total fuel mass can be delivered as PFI at engine start.

[0047] In one example, the amount of fuel delivered via port injectors and direct injectors is determined empirically and stored in predefined lookup tables or functions. For example, one table might correspond to determining the port injection amount, and another table might correspond to determining the direct injection amount. These tables can be indexed to engine operating conditions, such as engine speed and engine load, as well as other engine conditions. Furthermore, the tables can output the amount of fuel injected into the engine cylinders via port fuel injection and / or direct injection at each combustion cycle.

[0048] As another example, the controller can make logical determinations based on logic rules that are functions of parameters (engine speed and load), and further based on engine temperature (e.g., regarding the pulse width of the solenoid commands to be sent to the intake fuel injectors and direct fuel injectors). The controller can then generate pulse width control signals to be sent to the injector solenoids.

[0049] Determining the initial fuel injection distribution also includes, at 208, determining the number of injections for delivering fuel mass per combustion cycle. For example, within a given combustion cycle, one or more of the port-injected fuel mass and the direct-injected fuel mass may be delivered as multiple injections. In one example, within a given combustion cycle, the port-injected fuel mass may be delivered as a single port injection, while the direct-injected fuel mass may be delivered as multiple direct injections. The number of injections for multiple injections can be determined based on engine operating conditions. For example, during an engine cold start, the number of direct injections for delivering the direct-injected fuel mass may be higher (per combustion cycle) compared to an engine hot start. During an engine cold start, the controller can use both PFI (Pulse-Injected Fuel) and DI (Discharge-Injected Fuel). DI fuel can be used to promote catalytic heating. However, because DI fuel can increase emissions due to particulate contact with the combustion chamber, the DI fuel pulse can be divided into multiple injections.

[0050] The number of injections can also be based on the mass of fuel to be delivered. For example, when the mass of fuel to be delivered via a direct injector increases and exceeds the maximum pulse width of the direct injector, the fuel mass can be divided into multiple injections, each with a pulse width at or below the maximum pulse width. Similarly, when the mass of fuel to be delivered via a port injector increases and exceeds the maximum pulse width of the port injector, the fuel mass can be divided into multiple injections, each with a pulse width at or below the maximum pulse width. Multiple port injections can include multiple injections during the exhaust stroke (with the intake valve closed), the intake stroke (with the intake valve open), or a combination thereof. Multiple direct injections can include multiple injections during the intake stroke, the compression stroke, or a combination thereof.

[0051] By breaking the injection into multiple smaller bursts, the impact of fuel on engine components such as pistons and cylinder walls is reduced. When fuel hits these components, it either washes down the walls (which can damage the engine and release excess fuel into the fuel system) or it burns and produces particulate emissions. Breaking the fuel into smaller pulses avoids this. Compression injection can also be used, which atomizes the fuel near the spark plug at the moment of spark delivery.

[0052] Determining the initial fuel injection distribution also includes, at 210, determining the split ratio of fuel in multiple injections. For example, in a given combustion cycle, if the direct-injected fuel mass is delivered as a split direct injection comprising at least one intake stroke injection (DI_int) and at least one compression stroke injection (DI_comp), the controller can determine the ratio of the direct-injected fuel mass delivered via the intake stroke injection to the direct-injected fuel mass delivered via the compression stroke injection. Similarly, in a given engine cycle, if the direct-injected fuel mass is delivered via multiple intake stroke injections or multiple compression stroke injections, the split ratio of the direct-injected fuel mass in each injection can be determined. In one example, during engine cold start, the direct-injected fuel mass may be delivered as a split direct injection, wherein a larger portion of the direct-injected fuel mass is delivered during the compression stroke and a smaller portion is delivered during the intake stroke. In another example, during engine cold start, the mass of direct-injected fuel can be delivered as a split compression stroke direct injection, in which a larger portion of the fuel is delivered earlier during the compression stroke of the combustion cycle, and a smaller portion of the fuel is injected later during the compression stroke of the combustion cycle.

[0053] The injection split ratio and the number of multiple injections can be adjusted based on engine operating conditions (such as engine temperature at engine start, ambient temperature, and alcohol content of the injected fuel). Furthermore, the injection split ratio and number can be further adjusted based on exhaust catalyst temperature, exhaust PM filter PM load, and engine soot load at engine start. For example, as the alcohol content of the injected fuel increases, the number of direct compression stroke injections can be increased. As another example, as engine or ambient temperature decreases during engine cold start, the number of compression stroke injections applied during the first combustion event can be increased. In one example, multiple direct compression stroke injections of alcohol fuel can be advantageously used to heat the engine and catalyst, thereby promoting catalyst activation and improving engine and catalyst performance under cold start conditions, while reducing the soot load of direct injections.

[0054] As an example, the controller can determine the pulse width of the control signals to be sent to the direct fuel injector actuator and the port fuel injector actuator, such as signals determined based on engine speed and load, and further based on engine temperature, fuel alcohol content (or fuel octane rating), and engine PM load. Engine speed can be based on the output of a crankshaft sensor, and engine load can be based on operator torque requirements. The controller can determine the pulse width to be given for each injector command by directly considering the engine speed-load and engine temperature determination, such as increasing the direct injection pulse width as engine speed and engine load increase. Alternatively, the controller can determine the pulse width based on calculations using a lookup table, where the input is relative humidity and the output is the pulse width.

[0055] It should be understood that after determining the DI:PFI split ratio, the number of injections, and the direct injection split ratio, the controller can determine the fuel pulse width signal for each injection command based on the fuel rail pressure and the mass of fuel to be delivered in each injection.

[0056] At 212, it can be determined whether any DI fuel pulse in the determined fuel injection distribution is within the transition region of the direct injector (specifically, the direct injector operation map). See reference... Figure 4 As described in detail, the transition region lies between the impact region and the lift (or linear) region of the direct injector, and the variability of the direct injector in the transition region is higher than that in each of the impact and lift regions. Determining whether any DI fuel pulse is within the transition region of the direct injector may include, for example, determining whether the pulse width signal for any DI fuel pulse is less than an upper threshold corresponding to the lift region of the direct injector and greater than a lower threshold corresponding to the impact region of the direct injector, the upper and lower thresholds being selected based on fuel rail pressure. Thus, the transition region includes a specific pulse width range at different fuel rail pressures. As the pressure at both ends of the DI injector changes, the characteristics of the injector change. Therefore, the transition region shifts and changes size at different fuel rail pressures. Therefore, calibration must be performed for each injector design (e.g., part number), but not individually for each injector. A set of limiting sample injectors can be used to calibrate the pulse width range at each pressure, and this calibration can then be used to cover the entire injector group. If no DI fuel pulse is located in the transition region, the method moves to 214 to deliver fuel according to the determined fuel injection distribution, and the method ends.

[0057] Temporarily switch to Figure 4Map 400 depicts an example map of the direct injector operating region. Map 400 depicts the injector pulse width along the x-axis and the fuel mass along the y-axis. Curve 402 shows the relationship between the commanded direct injector pulse width and the actual delivered fuel mass.

[0058] Curve 402 illustrates the different regions (impact, transition, full lift) of a direct injector as the width of the electrical pulse applied to the injector increases. First, the fuel injector is not even open, requiring a minimum electrical pulse to open it and allow fuel to begin flowing. Then, the impact region is the period when the needle is not fully open. In this region, small changes in pulse width result in large changes in fuel quality (due to the very steep ramp in this region). In the transition region, the needle may skip, and fuel delivery can be very unpredictable (between injections and between injectors). Finally, the full lift region always has the same, less steep ramp and is therefore linear. For example, in the linear region, if a 1ms pulse width flows through 100ml, a 2ms pulse width will flow through 200ml.

[0059] At higher command fuel pulse widths, the injector operates in the lift region 406, where fuel quality changes linearly with the command pulse width. At very small command fuel pulse widths, the injector operates in the impact region 404, where some variability may exist. Specifically, at very low command pulse widths, i.e., less than the injector's minimum pulse width, no fuel is delivered. However, thereafter, fuel quality changes linearly with the command pulse width. In the region between the lift region and the impact region, specifically in the intermediate transition region 408, the injector operates with high variability. For example, based on the pulse width's position within the transition region, the actual fuel quality delivered may be higher or lower than the expected fuel quality. Furthermore, this variability is non-linear and difficult to predict or model, making it difficult to compensate for.

[0060] Specifically, in the impact zone, increasing the electrical pulse width for the fuel injector increases the amount of mass delivered at a higher rate (steeper ramp). While there may be some variability in this increase, this variability can be mapped, and the shape or displacement of the ramp in the impact zone can be adjusted to take this mapped variability into account. For example, based on the variability, the ramp can be made steeper or less steep. However, in the transition zone, the increased pulse width may actually result in a reduction in the mass of fuel injected. Because the shape and ramp change drastically in the transition zone (between injections and between injectors in a group of injectors), it may not be possible to simply shift and change the shape of the ramp in the transition zone. The variability is exacerbated because the ramp in the transition zone is different for each injector and significantly different between injections.

[0061] As described in detail herein, refueling errors and the resulting torque and emissions problems can be reduced by updating the fuel injection distribution to move the DI fuel pulse out of the transition region. However, avoiding the injector's transition region is not as simple as changing the injection pulse width to jump precisely from the end of the impact region to the beginning of the full-lift region, because the fuel mass delivered in region 404 is significantly lower than that delivered in region 406. This results in a large jump in the fuel delivered to the engine. Therefore, simply updating the injector pulse width may not be sufficient to avoid the transition region. Instead, as referenced... Figure 3 and Figures 5-11 As detailed in the example, the fuel mass of each injection pulse in the initial fuel injection distribution may need to be modified to maintain the total fuel mass delivered to the engine.

[0062] return Figure 2If any DI fuel pulses in the initially determined fuel injection distribution are located within the transition region of the direct injector, then at 216, the method includes updating the fuel injection distribution to move the affected DI fuel pulse(s) out of the transition region. Updating the fuel injection distribution includes, at 218, updating the DI:PFI split ratio. For example, the proportion of total fuel mass delivered via direct injection may increase, while the proportion delivered via port injection may decrease accordingly. As another example, the proportion of total fuel mass delivered via direct injection may decrease, while the proportion delivered via port injection may increase accordingly. The controller may estimate an initial ratio of port-injected fuel to direct-injected fuel over the combustion cycle based on engine operating conditions (such as a cold start of the engine), and then, in response to the direct fuel injection at the initial ratio being located within the transition region of the direct injector map, the controller may update the initial ratio to move the direct fuel injection out of the transition region. The update may be based on the relationship between the pulse width of the direct fuel injection and each of the impact-transition boundary and lift-transition boundary of the direct injector map. As an example, in response to the distance between the direct fuel injection pulse width and the impact-transition boundary of the direct injector map being less than the distance between the direct fuel injection pulse width and the lift-transition boundary of the direct injector map, the controller can reduce the direct injection fuel mass to move the pulse width from the transition region to the impact region of the direct injector map, while increasing the intake port injection fuel mass. As another example, in response to the distance between the direct fuel injection pulse width and the impact-transition boundary of the direct injector map being greater than the distance between the direct fuel injection pulse width and the lift-transition boundary of the direct injector map, the controller can increase the direct injection fuel mass to move the pulse width from the transition region to the lift region of the direct injector map, while decreasing the intake port injection fuel mass. The initial ratio of intake port injection fuel to direct injection fuel can include multiple direct injections over the combustion cycle, and the increase and decrease can be based on the number of direct injections.

[0063] As described in detail below, the controller can adjust the number of multiple direct injections by reducing the number of injections to move the pulse width from the transition region to the lift region. Here, the reduction may respond to an unadjusted number of injections exceeding a threshold. As another example, the controller can adjust the number of multiple direct injections by increasing the number of injections to move the pulse width from the transition region to the impulsive region. Here, the increase may respond to an unadjusted number of injections falling below a threshold. In one example, multiple direct injections may include multiple direct injections during the intake stroke and / or compression stroke of the combustion cycle, and the update may also include updating the split ratio of the directly injected fuel delivered during the intake stroke relative to the directly injected fuel delivered during the compression stroke.

[0064] Additionally or optionally, updating the fuel injection distribution may include, at 220, updating the number of injections used to deliver fuel mass. For example, the total number of direct injections can be increased by splitting some fuel pulses into multiple smaller fuel pulses. As another example, the total number of direct injections can be reduced by merging some fuel pulses into fewer, larger fuel pulses. Additionally or optionally, updating the fuel injection distribution may include, at 222, updating the split-direct injection ratio of fuel delivered in multiple direct injection pulses. For example, the amount of total direct-injected fuel mass delivered via compression stroke direct injection may be increased, while the amount of fuel delivered via intake stroke direct injection may be decreased. As another example, the amount of total direct-injected fuel mass delivered via compression stroke direct injection may be decreased, while the amount of fuel delivered via intake stroke direct injection may be increased. See reference... Figure 3 Methods and Figures 5-11 Further options are possible, as described in the example. The update can be performed based on the relationship between the fuel quality position of the DI fuel pulse in the transition zone and each of the lift and impact zones. In this way, the DI fuel pulse can be modified to operate the direct injector outside the transition zone, thereby reducing refueling errors and related problems.

[0065] In one example, during the first condition, the controller can update the fuel injection distribution by adjusting the fuel quality between DI injections while maintaining the number of DI injections, as this deviates as little as possible from the base engine calibration. In another example, since reducing the number of DI injections diminishes the effectiveness of multiple injections in reducing particulate emissions, the number of DI injections can be reduced during the second condition when the exhaust PM load is below a threshold. In yet another example, the DI / PFI split ratio can be modified during the third condition; however, limitations may be imposed on the split ratio adjustment before it can begin to affect the side-spark and boost air cooling (power).

[0066] In a further example, a combination of the above methods can be chosen. This choice can be based on engine operating conditions (such as engine speed constraints and NVH constraints). For example, engine speed constraints can limit the total number of injections that the powertrain control module can inject. At higher engine speeds, the engine controller may not be able to handle the power consumption of multiple fuel injections. Therefore, at higher engine speeds, updating the injection distribution can include reducing the number of injections; or if the number of injections is increased, increasing the injection by a smaller amount (i.e., limiting the increased number of injections). As another example, additional fuel injections may increase ticking noise, which can negatively impact consumer perception. Therefore, when engine ticking noise is already present, updating the injection distribution can include reducing the number of injections; or if the number of injections is increased, increasing the injection by a smaller amount (i.e., limiting the increased number of injections).

[0067] At position 224, fuel is delivered based on the updated fuel injection distribution. For example, the controller can determine the fuel pulse width to be commanded based on the updated fuel quality of various pulses, and then send these signals to the corresponding fuel injectors. The method then ends.

[0068] Now go to Figure 3 An exemplary method 300 for updating the fuel injection distribution to move the DI fuel pulse out of the transition region of a direct injector is shown. Figure 3 The method can be used as Figure 2 It is part of the method to be executed, such as at 216.

[0069] At 302, the method includes determining whether any DI fuel pulses of the initially determined fuel injection distribution fall within the transition region of the direct injector map. If not, the method moves to 322 to deliver fuel according to the unmodified fuel injection distribution. This includes sending a pulse width signal to the fuel injector according to the initial fuel injection distribution.

[0070] If one or more DI fuel pulses of the initial fuel injection distribution are determined to have a fuel pulse width within the transition region, the method proceeds to 304, where the positions of the affected DI fuel pulse(s) within the injector's transition region are determined. For example, the distances of the affected DI fuel pulse(s) to each of the impact region (specifically, the boundary between the transition region and the impact region) and the lift region (specifically, the boundary between the transition region and the lift region) can be estimated. The controller can reference a direct injector mapping (such as...) Figure 4 (Example mapping) to estimate distance.

[0071] At 305, it can be determined whether a fuel pulse in the transition region is closer to the impact region relative to the lift region. For example, a first distance of the fuel pulse to the impact-transition boundary and a second distance of the fuel pulse to the lift-transition boundary can be compared. If the first distance is less than the second distance, the affected fuel pulse is determined to be closer to the impact region. It should be recognized that each DI fuel pulse in the transition region can be evaluated similarly.

[0072] If the affected DI fuel pulse is closer to the injector's impact region, at 310, the method includes reducing the pulse width of the command for the affected DI fuel pulse to move it from the transition region to the impact region. Due to the change in pulse width, the mass of fuel delivered in the affected fuel is reduced. In contrast, if the affected DI fuel pulse is closer to the injector's lift region, such as when the second distance is less than the first distance, at 308, the method includes increasing the pulse width of the command for the affected DI fuel pulse to move it from the transition region to the lift region. Due to the change in pulse width, the mass of fuel delivered in the affected fuel is increased.

[0073] In this manner, in response to a DI fuel pulse (e.g., the fuel mass or pulse width of the affected DI fuel pulse) being less than the distance between the impact-transition boundary of the direct injector map and the lift-transition boundary of the direct injector map, the controller can reduce the fuel mass of that injection in a multi-injection sequence to move the fuel mass from the transition region to the impact region of the direct injector map, while increasing the fuel mass of another injection in the multi-injection sequence. In an alternative example, in response to a fuel mass being greater than the distance between the impact-transition boundary of the direct injector map and the lift-transition boundary of the direct injector map, the controller can increase the fuel mass of that injection in a multi-injection sequence to move the fuel mass from the transition region to the lift region of the direct injector map, while reducing the fuel mass of another injection in the multi-injection sequence. Here, the increase and decrease can be based on the total number of multi-injection sequences in the initial (unmodified) DI fuel injection distribution and the proportion of these injections located in the transition region.

[0074] The method moves from each of 308 and 310 to 320, in which the method includes adjusting the pulse width of each command in the remaining DI fuel pulse (outside the transition region) and the PFI fuel pulse to maintain the total fuel mass. In other words, the total fuel mass delivered by both the unmodified fuel injection distribution and the modified fuel injection distribution remains constant. In a further example, adjusting the pulse width may include: adjusting the direct injection fuel mass to move the affected pulse out of the transition region, and then, based on the updated DI fuel mass, adjusting the amount of fuel delivered to the cylinder via intake port injection over the combustion cycle to maintain the total fuel mass.

[0075] Additionally or optionally, when adjusting the affected fuel pulse based on its position within the transition region, the method may also (from 302) move to 314 to adjust the amount of direct injection. Specifically, at 314, it can be determined whether the DI fuel pulse in the transition region is part of a split direct injection. Split direct injection can be confirmed when delivering DI fuel mass within multiple intake stroke direct injections and / or compression stroke direct injections. As an example, split direct injection may include 2-4 direct injections, which can be any combination of intake stroke direct injection and compression stroke direct injection.

[0076] If the affected DI fuel pulse is not part of a split direct injection, such as when the DI fuel pulse is a single direct injection of an unmodified fuel injection distribution, then at 318, the method includes adjusting the fuel pulse width to split the affected DI fuel pulse into a plurality of smaller DI pulses, each of which is located within the impact region of the injector. By increasing the number of fuel pulses, the affected DI fuel pulse is moved out of the transition region, and each smaller fuel pulse is located within a less variable impact region.

[0077] If the affected DI fuel pulse is part of a split direct injection, such as when the DI fuel pulse is one of multiple direct injections in an unmodified fuel injection distribution, then at 316, the method includes adjusting the fuel pulse width to combine the affected DI fuel pulse with at least one other DI fuel pulse (such as another DI fuel pulse in the transition region, a DI fuel pulse in the impact region, or a DI fuel pulse in the lift region) into a larger DI pulse in the lift region of the injector. By reducing the number of fuel pulses, the affected DI fuel pulse is moved out of the transition region, and the resulting larger fuel pulse is located in a more linear lift region.

[0078] Reference Figure 5 An example is shown where the injection quantity is adjusted to operate outside the transition zone of a direct injector. Map 500 depicts a direct injector map (such as...). Figure 4 The map 500 (400) includes an impact region 404, a lift region 406, and a transition region 408. In this example, the initial (unmodified) fuel injection distribution consists of multiple direct injections per combustion cycle. Map 500 depicts two DI fuel pulses 502a and 502b (both with the same fuel mass and therefore the same pulse width) located in the transition region 408 of the injector map. In an alternative example, DI fuel pulses 502a and 502b may be located in the transition region and have different fuel masses. To avoid operation in the transition region 408, the number of fuel pulses is reduced by merging fuel pulses 502a and 502b into a single fuel pulse 504 with a larger fuel mass and therefore a larger pulse width. Specifically, the modified pulse width of fuel pulse 504 is located in the lift region 406. In this way, by reducing the number of direct fuel injections per combustion cycle, direct injector operation is moved out of the transition region and into the lift region while maintaining the direct injection fuel mass.

[0079] Reference Figure 6 Another example is shown where the injection quantity is adjusted to operate outside the transition zone of a direct injector. Map 600 depicts a direct injector map (such as...). Figure 4 The injection map 600 (400) includes an impact region 404, a lift region 406, and a transition region 408. In this example, the initial (unmodified) fuel injection distribution consists of a single direct injection per combustion cycle. The injection map 600 depicts a single DI fuel pulse 602 located in the transition region 408 of the injector map. To avoid operation in the transition region 408, the number of fuel pulses is increased by splitting the fuel pulse 602 into two fuel pulses 604a and 604b, each having a smaller fuel mass and therefore a smaller pulse width. In the depicted example, both fuel pulses 604a and 604b have the same fuel mass (and therefore the same pulse width) and are located in the impact region 404 of the injector map. In an alternative example, the DI fuel pulses 604a and 604b may be located in the impact region and have different fuel masses. In this way, by increasing the number of direct fuel injections per combustion cycle, the operation of the direct injector is moved from the transition zone to the impact zone, while maintaining the quality of the direct fuel injection.

[0080] In this way, during the first condition, the controller can reduce the number of multiple injections by merging the injection in the multiple direct injections with at least one other injection in the multiple direct injections, in order to move fuel mass from the transition region to the lift region. Then, during the second condition, the controller can increase the number of multiple injections by dividing the injection in the multiple direct injections into multiple direct injections in the impact region. In one example, during the first condition, the unadjusted number of multiple injections is higher than a threshold number, while during the second condition, the unadjusted number of multiple injections is lower than the threshold number.

[0081] refer to Figure 7 An example is shown where the fuel mass in a fuel injection distribution with multiple direct injections is adjusted to operate outside the transition region of the direct injector. Mapping diagram 700 depicts a direct injector mapping diagram (such as...). Figure 4 The injection map 700 (400) includes an impact region 404, a lift region 406, and a transition region 408. In this example, the initial (unmodified) fuel injection distribution consists of multiple direct injections per combustion cycle. The injection map 700 depicts two DI fuel pulses 702a and 702b (both with the same fuel mass and therefore the same pulse width) located in the transition region 408 of the injector map. In an alternative example, the DI fuel pulses 702a and 702b may be in the transition region and have different fuel masses. To avoid operation in the transition region 408, the fuel mass of each pulse in pulses 702a and 702b is adjusted while maintaining the total direct injection fuel mass and also maintaining the total number of direct injections. Specifically, the fuel mass of pulse 702a is increased to provide a modified fuel pulse 704 in the lift region 406 of the injector. Simultaneously, the fuel mass of pulse 702b is decreased to provide a modified fuel pulse 706 in the impact region 404 of the injector. In this way, by modifying the fuel mass and pulse width of each injection in multiple direct fuel injections of each combustion cycle, the operation of the direct injector is moved out of the transition zone.

[0082] In one example, the engine controller can modify each DI fuel pulse in the transition region based on the proximity of each pulse to the full-lift-transition region boundary and the impact-transition region boundary. The modification can also be based on the total fuel mass to be delivered via direct injection, the total fuel mass of the affected pulse(s)(s) in the transition region, the total number of direct injections, and the number of affected injections in the transition region. As an example, the controller can use algorithms (such as...) Figure 8 The algorithm 800, described in detail below, modifies the fuel quality for each fuel pulse.

[0083] The controller starts at Figure 8The total desired fuel mass to be injected (by direct injection) is determined as MFdes × Ndes, where MFdes is the desired fuel mass to be injected at each injection and Ndes is the desired injection quantity. The controller then converts the total desired fuel mass (MFdes × Ndes) into the same number of direct injection fuel pulses separated between the impact zone injection and the lift zone injection. Assuming MFbe represents the "end of impact" fuel mass, MFls represents the "linear start" fuel mass (fuel mass in the lift zone), and MFth represents the calibrable hysteresis for the transition zone, the following equation should hold:

[0084] Ndes = Nb + Nl;

[0085] MFdes×Ndes=MFlinear×Nl+MFballistic×Nb;

[0086] Where MFlinear and MFballistic are the modified fuel masses planned for injection in the lift region (also referred to as the linear region in this paper) and the impact region, respectively, and Nl and Nb are the number of pulses in each region, respectively.

[0087] The following conditions must be met:

[0088] MFlinear ≥ MFl;

[0089] MFballistic≤MFb;

[0090] This can be written as follows:

[0091] 0=Delta(MFlinear)×Nl+Delta(MFballistic)×Nb.

[0092] Upon further calculation and assuming MFlinear = MFl and / or Fballistic = MFb, we ultimately arrive at the following equation for floating-point operations:

[0093] Nb-float=(F32)Ndes×(MF Δl / MFtransition).

[0094] The optimal quantities for impact injection and linear injection are as follows:

[0095] Nb=(U8)uclip(1UL,(U32)(Nb-float+0.5F),((U32)Ndes–1UL));

[0096] and:

[0097] Nl = Ndes – Nb;

[0098] The following will help in calculating MFlinear and MFballistic, as shown below:

[0099]

[0100]

[0101] In this way, the fuel mass delivered in each DI fuel pulse can be modified to operate the direct injector outside the transition zone while maintaining the total fuel mass and total number of direct injections.

[0102] In one example, multiple direct injections of the unmodified fuel injection distribution can include multiple direct injections during the intake and / or compression strokes of the combustion cycle. Here, updating the fuel quality can include updating the split ratio of the directly injected fuel delivered during the intake stroke relative to the directly injected fuel delivered during the compression stroke. Furthermore, the number of intake stroke injections and compression stroke injections can vary.

[0103] Reference Figure 9 An example is shown where the split ratio of fuel delivered via direct injection relative to fuel delivered via inlet injection is adjusted to allow operation outside the transition region of the direct injector. An unmodified direct injector map 900 and a modified direct injector map 910 are shown. Similar to... Figure 4 Mapping diagrams 400, 900, and 910 include impact region 404, lift region 406, and transition region 408.

[0104] In this example, the initial (unmodified) fuel injection distribution comprises an initial split ratio of 50% DI:50% PFI for multiple direct injections per combustion cycle. Map 900 depicts two DI fuel pulses 902 (both with the same fuel mass and therefore the same pulse width) located in the transition region 408 of the injector map and together constituting 50% DI of the initial fuel injection distribution. In an alternative example, the DI fuel pulses 902 may be located in the transition region and have different fuel masses. The DI fuel pulses 902 are located in the transition region 408, near the boundary between the transition region and the lift region 406. To avoid operation in the transition region 408, the DI:PFI fuel split ratio is adjusted by changing the DI percentage. Specifically, since the DI fuel pulses are closer to the lift region 406 (relative to the impact region 404), the percentage of total fuel delivered via DI is increased from 50% to 70% to move the DI fuel pulses out of the transition region, as indicated by the modified pulse 904 in the lift region. At the same time, the total fuel mass is maintained by reducing the PFI percentage from 50% to 30%. In this way, the direct injector operation is moved out of the transition zone by increasing the percentage of fuel delivered via direct injection relative to fuel delivered via intake port injection over a given combustion cycle.

[0105] Reference Figure 10 Another example is shown where the split ratio of fuel delivered via direct injection relative to fuel delivered via inlet injection is adjusted to allow operation outside the transition region of the direct injector. An unmodified direct injector map 1000 and a modified direct injector map 1010 are shown. Similar to... Figure 4 Mapping diagram 400, mapping diagrams 1000 and 1010 include impact region 404, lift region 406 and transition region 408.

[0106] In this example, the initial (unmodified) fuel injection distribution comprises an initial split ratio of 50% DI:50% PFI for multiple direct injections per combustion cycle. Map 1000 depicts two DI fuel pulses 1002 (both with the same fuel mass and therefore the same pulse width) located in the transition region 408 of the injector map and together constituting 50% DI of the initial fuel injection distribution. In an alternative example, the DI fuel pulses 1002 may be located in the transition region and have different fuel masses. The DI fuel pulses 1002 are located in the transition region 408, near the boundary between the transition region and the impact region 404. To avoid operation in the transition region 408, the DI:PFI fuel split ratio is adjusted by changing the DI percentage. Specifically, since the DI fuel pulses are closer to the impact region 404 (relative to the lift region 406), the percentage of total fuel delivered by DI is reduced from 50% to 30% to move the DI fuel pulses out of the transition region, as indicated by the modified pulse 1004 in the impact region. At the same time, the total fuel mass is maintained by increasing the PFI percentage from 50% to 70%. In this way, the direct injector operation is moved out of the transition zone by reducing the percentage of fuel delivered via direct injection relative to fuel delivered via intake port injection in a given combustion cycle.

[0107] It should be recognized that, despite Figures 5-10 The example depicts an adjustment to one of the injection quantity, DI:PFI split ratio, and fuel mass of multiple direct injections, but this is not intended to be limiting. In a further example, various combinations of the methods described above can be used. For example, during selected conditions, the injection quantity and DI:PFI split ratio can be modified. As another example, during other conditions, each of the injection quantity, DI:PFI split ratio, and fuel mass of multiple direct injections can be modified.

[0108] For example, during the first condition, the pulse width signal of a single direct injection fuel pulse in response to the combustion cycle is located in the transition region of the direct injector, and the controller can move to operate on the combustion cycle using multiple direct injection fuel pulses, the pulse width signal of each of the multiple direct injection fuel pulses being located outside the transition region. In contrast, during the second condition, the pulse width signal of one of the multiple direct injection fuel pulses in response to the combustion cycle is located in the transition region of the direct injector, and the controller can move to operate on the combustion cycle using a single direct injection fuel pulse, the pulse width signal of which is located outside the transition region. In one example, during the first condition, the pulse width signal of each of the multiple direct injection fuel pulses is located in the impact region of the direct injector, while during the second condition, the pulse width signal of the single direct injection fuel pulse is located in the lift region of the direct injector. In another example, during each of the first and second conditions, the total fuel mass delivered by direct injection on the combustion cycle is maintained. Furthermore, during the third condition, if the pulse width signal of one of the multiple direct injection fuel pulses in response to the combustion cycle is located in the transition region of the direct injector, the controller can adjust the pulse width signal of each of the multiple direct injection fuel pulses to move out of the transition region while maintaining the number of pulses of the multiple direct injection fuel pulses.

[0109] As an example, the first condition (where the injection quantity increases) includes engine operation at lower engine speeds and / or lower PM loads; the second condition (where the injection quantity decreases) includes engine operation at higher speeds, higher PM loads, and / or at least one injection in a series of injections in the impact zone being too small (e.g., less than or at the injector's minimum pulse width); and the third condition includes PM loads above a threshold and / or engine NVH above a threshold. Shifting and adjustment during each of the first, second, and third conditions may include, for example, adjusting the total fuel mass delivered via direct injection over the combustion cycle, and the method further includes adjusting the fuel mass delivered via intake port injection over the combustion cycle based on the adjusted total fuel mass delivered via direct injection.

[0110] In yet another example, during a first condition, the controller may modify the initial fuel injection distribution to a first modified fuel injection distribution having a smaller number of direct injection fuel pulses, each of which has a smaller pulse width in the lift region of the direct injector; while during a second condition, the controller may modify the initial fuel injection distribution to a second modified fuel injection distribution, wherein the pulse width of a first group of the multiple direct injection fuel pulses is reduced to the impact region of the direct injector, while the pulse width of a second group of the multiple direct injection fuel pulses is increased to the lift region of the direct injector, while maintaining the number of multiple direct injection fuel pulses. Here, the total direct injection fuel mass in each of the first and second modified fuel injection distributions may be the same as the fuel mass in the initial unmodified fuel injection distribution. As an example, the first condition may include one or more of higher engine speed and higher PM load, while the second condition may include one or more of lower engine speed, higher engine NVH, and at least one injection of the initial fuel injection distribution operating at or near the minimum pulse width of the injector. The initial fuel injection distribution may include an initial number of direct injection fuel pulses, and modifications during each of the first and second conditions may be based on the initial number of direct injection fuel pulses, and further on the relationship between the pulse width of at least one of the multiple direct injection pulses and the upper limit of the pulse width of the impact region and the lower limit of the pulse width of the lift region. Furthermore, during the third condition, the controller may modify the initial fuel injection distribution to a third modified fuel injection distribution, which includes adjusting the total direct injection fuel mass to shift the pulse width of at least one of the multiple direct injection fuel pulses out of the transition region of the direct injector, and adjusting the intake manifold injection fuel mass based on the adjusted direct injection fuel mass.

[0111] In yet another example, during the first condition, when the pulse width of one of the multiple direct injection fuel pulses in response to the combustion cycle is within the transition region of the direct injector map, the controller can reduce the number of multiple direct injection fuel pulses while maintaining the direct injection fuel to intake fuel injection split ratio. During the second condition, when the pulse width of one of the multiple direct injection fuel pulses in response to the combustion cycle is within the transition region of the direct injector, the controller can adjust the direct injection fuel to intake fuel injection split ratio. As an example, adjusting the split ratio may include increasing the direct injection fuel to intake fuel injection split ratio within the combustion cycle when more fuel mass is needed in the impulsive DI injection (because it is less than the minimum permissible pulse width of the injector). In another representation, instead of splitting the DI pulse into impulsive and linear regions, the pulse is split into two impulsive injections and the remaining mass is then added to the PFI system, thereby changing the number of DI injections and reducing the direct injection fuel to intake fuel injection split ratio within the combustion cycle. Adjusting the split ratio may also include maintaining the number of multiple direct injection fuel pulses in the combustion cycle. Alternatively, adjusting the split ratio can include adjusting the number of multiple direct injection fuel pulses in the combustion cycle, and the mass of fuel delivered in each of the multiple direct injection fuel pulses. In one example, during a first condition, the pulse width of each of the reduced number of multiple direct injection fuel pulses lies within the full lift region of the direct injector. The number of DI pulses can be maintained by adding more fuel to avoid a minimum pulse width, or by removing fuel so that all DI injectors can be within the impact region. In another representation, the number of DI pulses can be reduced, and additional mass can be added to the PFI system. In yet another representation, the number of DI pulses can be increased by taking fuel from the PFI system to add fuel to the DI system, thereby increasing the number of DI injections and increasing the split ratio of direct injection fuel to port injection fuel within the combustion cycle.

[0112] refer to Figure 11 An exemplary modified fuel injection distribution is shown, in which several different adjustments can be applied to move the direct injection fuel pulse out of the transition region. Figure 11Mapping diagram 1100 illustrates exemplary fuel injection distributions 1102-1104 that can be used during engine operation in response to an initial fuel injection distribution 1101 having a DI fuel pulse located within the transition region of the operating mapping of a direct injector. Each injection distribution depicts the injection timing relative to the cylinder piston position or cylinder stroke. Based on the position of the cylinder piston at any time during the engine cycle, fuel can be injected into the cylinder during the intake stroke (I), compression stroke (C), power stroke (P), or exhaust stroke (E). The injection distribution also describes whether fuel is injected via port injection (shaded blocks), single or multiple direct injections (striped blocks), or both.

[0113] The initial fuel injection distribution can be determined based on engine operating conditions, including engine speed, driver torque demand, engine temperature, and fuel alcohol content. In one example, the initial fuel injection distribution could be the engine cold start fuel injection distribution. The initial fuel injection distribution includes, on a given combustion cycle, injecting a portion of the fuel as an intake port injection (shaded block) during the intake valve closing event (i.e., during the exhaust stroke of the previous cylinder combustion event), and injecting the remaining fuel as an intake stroke direct injection and two compression stroke direct injections (diagonal stripe blocks). The injection quantity can be adjusted such that 35% of the fuel injection can be delivered as an intake port injection during the intake valve closing event (e.g., during the exhaust stroke), another 35% as an intake stroke direct injection, and the remaining 30% as multiple compression stroke direct injections. Here, the fuel mass in the second (in the most recent combustion cycle) compression stroke injection can correspond to the pulse width located in the transition region of the direct injector.

[0114] To avoid the transition zone, the initial fuel injection distribution can be updated to a first modified fuel injection distribution (updated fuel injection distribution_A), where the number of direct compression stroke injections is increased by splitting the first (in earlier combustion cycles) compression stroke DI pulse into two smaller compression stroke DI pulses. Furthermore, the total amount of DI fuel delivered during the compression stroke decreases, while the amount of DI fuel delivered during the intake stroke increases accordingly. The proportion of fuel delivered via intake port injection remains unchanged, thus allowing the overall DI:PFI ratio to be maintained. Therefore, in this example, by increasing the number of direct injections and by changing the ratio of fuel mass delivered in each direct injection, the compression stroke DI fuel pulse predicted to be in the transition zone is moved to the impact zone. In one example, the first modified fuel injection distribution can be selected in response to the injection mode. If the engine is in a mode requiring catalyst heating, the DI compression injection size and injection timing are critical. Other fuel parameters (such as DI intake fuel mass) can be adjusted without affecting emissions, just as with changing the DI compression injection.

[0115] To avoid the transition region, the initial fuel injection distribution can be updated to a second modified fuel injection distribution (updated fuel injection distribution_B), where the number of direct injections during the compression stroke is reduced by merging the first and second compression stroke DI pulses into a single compression stroke DI pulse, while also reducing the total amount of fuel delivered during the compression stroke. The amount of DI fuel delivered during the intake stroke is increased slightly until the maximum pulse width of the direct injector is reached. The remaining fuel mass is adjusted by increasing the proportion of fuel delivered through the intake manifold, resulting in a reduction in the overall DI:PFI ratio. Therefore, in this example, by reducing the number of direct injections, and by changing the proportion of fuel mass delivered in each direct injection, and by reducing the DI:PFI fuel ratio, compression stroke DI fuel pulses predicted to be in the transition region are moved into the impact region. In one example, the second modified fuel injection distribution can be selected in response to maintaining the same fuel-air control. If it is necessary to move fuel mass out of the DI injection to ensure that the DI pulse is not in the transition region, the PFI can be increased accordingly.

[0116] To avoid the transition region, the initial fuel injection distribution can be alternatively updated to a third modified fuel injection distribution (updated fuel injection distribution_C), where the number of compression stroke direct injections is reduced by merging the first and second compression stroke DI pulses with the intake stroke DI fuel pulses to provide a single intake stroke DI pulse, while also increasing the total amount of fuel delivered via direct injection. The proportion of fuel delivered via intake port injection is correspondingly reduced, resulting in an increase in the overall DI:PFI ratio. Therefore, in this example, by reducing the number of direct injections and by changing the ratio of fuel mass delivered in each direct injection and increasing the DI:PFI fuel ratio, the compression stroke DI fuel pulse predicted to be in the transition region is moved to the impact region. In one example, the third modified fuel injection distribution may be selected in response to maintaining the same fuel-air control and the driver's torque demand being under a higher load requiring DI boost air cooling.

[0117] In another example, under higher engine loads, such as when more power, more air intake for cooling, or earlier spark, the controller can increase the split ratio of direct-injected fuel to port-injected fuel within the combustion cycle. Conversely, under lower engine loads, such as at PM loads or when exhaust emissions are above a threshold load, the controller can decrease the split ratio of direct-injected fuel to port-injected fuel within the combustion cycle.

[0118] In other examples, the controller may continue adjusting the fuel quality until a solution cannot be found to place the pulses in the full lift and impact regions. At this point, the number of injectors can be reduced by one, and a solution determined. The controller may repeatedly adjust the number of pulses and then the number of injectors until the distribution drops to 1 injection. If the injection is still in the transition region, the DI / PFI split ratio can be changed (e.g., increased or decreased) to move the DI injection out of the transition region.

[0119] In yet another example, where there is no option to maintain the injection quantity, the controller can combine fuel pulses while redistributing them between the impact zone and the full-lift zone. Therefore, the controller can prioritize maintaining the pulse quantity and redistribute fuel mass across the full-lift and transition zones. If a solution cannot be achieved due to injections in the impact zone falling below the injector's minimum pulse width, the number of pulses can be reduced to enable full-lift injection.

[0120] Furthermore, when a larger mass of direct-injection fuel is required to allow the controller to divide the transition zone injection into impact zone injection and full-lift zone injection, the controller can increase the split ratio of direct-injection fuel to intake-injection fuel within the combustion cycle. Conversely, when a smaller mass of direct-injection fuel is required to move the injection out of the transition zone (e.g., because the number of DI injectors has been reduced), the controller can decrease the split ratio of direct-injection fuel to intake-injection fuel within the combustion cycle.

[0121] In this way, the variability of the direct injector is reduced, thereby allowing for reductions in gaseous and particulate emissions. For example, gaseous and particulate emissions can be reduced without reducing the number of multiple injections on a power-fuel dual-fuel (PFDI) engine. The technical effect of adjusting one or more of the number of direct injection fuel pulses, fuel mass, and split ratio based on the position of the fuel pulse relative to the transition region of the direct injector is that direct injection can be provided outside the highly variable transition region while maintaining the total fuel mass to be injected for a given combustion cycle. Furthermore, the amount of calibration effort required by the engine is reduced compared to the effort required to map the fuel mass separated between fuel pulses in a feedforward manner. Because operation is performed outside the inaccurate transition region of the direct injector, engine air-fuel ratio errors and torque errors can be reduced, thereby improving drivability.

[0122] An exemplary method for an engine includes: delivering fuel as multiple direct injections to a cylinder over a combustion cycle; and updating, in response to a fuel mass of one injection in the multiple direct injections being located in a transition region of a direct injector map, one or more of the ratio of fuel delivered in each injection in the multiple direct injections and the number of multiple injections to move the fuel mass of that injection out of the transition region. In a previous example, additionally or optionally, the transition region is located between a shock region and a lift region of the direct injector map, and wherein the direct injector variability in the transition region is higher than the direct injector variability in each of the shock region and the lift region. In any or all of the previous examples, additionally or optionally, the update is based on the position of the fuel mass relative to each of the shock-transition boundary and the lift-transition boundary of the direct injector map. In any or all of the preceding examples, additionally or optionally, the update includes: in response to the distance between the fuel mass and the impact-transition boundary of the direct injector map being less than the distance between the fuel mass and the lift-transition boundary of the direct injector map, reducing the fuel mass of that injection in the multiple direct injections to move the fuel mass from the transition region of the direct injector map to the impact region, while increasing the fuel mass of another injection in the multiple direct injections. In any or all of the preceding examples, additionally or optionally, the update also includes: in response to the distance between the fuel mass and the impact-transition boundary of the direct injector map being greater than the distance between the fuel mass and the lift-transition boundary of the direct injector map, increasing the fuel mass of that injection in the multiple direct injections to move the fuel mass from the transition region of the direct injector map to the lift region, while decreasing the fuel mass of another injection in the multiple direct injections. In any or all of the preceding examples, additionally or optionally, the increase and decrease are based on the number of multiple direct injections. In any or all of the preceding examples, additionally or optionally, updating the number of injections in multiple direct injections includes: during a first condition, reducing the number of multiple injections by merging the injection in the multiple direct injections with at least one other injection in the multiple direct injections to move fuel mass from the transition region to the lift region; and during a second condition, increasing the number of multiple injections by dividing the injection in the multiple direct injections into multiple direct injections in the impact region. In any or all of the preceding examples, additionally or optionally, during the first condition, the unadjusted number of multiple injections is higher than a threshold number, and wherein under the second condition, the unadjusted number of multiple injections is lower than the threshold number. In any or all of the preceding examples, additionally or optionally, the multiple direct injections include multiple direct injections during the intake stroke and / or compression stroke of the combustion cycle, and wherein updating further includes updating the split ratio of the direct injection fuel delivered during the intake stroke relative to the direct injection fuel delivered during the compression stroke.In any or all of the preceding examples, additionally or optionally, the method also includes adjusting the amount of fuel delivered to the cylinder via intake port injection during the combustion cycle based on an update. In any or all of the preceding examples, additionally or optionally, the method may be implemented in a hybrid vehicle system.

[0123] Another exemplary method includes: during a first condition, shifting the pulse width signal of a single direct injection fuel pulse in response to the combustion cycle, which is located within the transition region of the direct injector, to operation on the combustion cycle using a plurality of direct injection fuel pulses, wherein the pulse width signal of each of the plurality of direct injection fuel pulses is located outside the transition region; and during a second condition, shifting the pulse width signal of one of the plurality of direct injection fuel pulses in response to the combustion cycle, which is located within the transition region of the direct injector, to operation on the combustion cycle using a single direct injection fuel pulse, wherein the pulse width signal of the single direct injection fuel pulse is located outside the transition region. In the preceding examples, additionally or optionally, during the first condition, the pulse width signal of each of the plurality of direct injection fuel pulses is located within the impact region of the direct injector, and wherein during the second condition, the pulse width signal of the single direct injection fuel pulse is located within the lift region of the direct injector. In any or all of the preceding examples, additionally or optionally, during each of the first and second conditions, the total fuel mass delivered by direct injection on the combustion cycle is maintained. In any or all of the preceding examples, additionally or optionally, the method further includes, during the third condition, adjusting the pulse width signal of each of the plurality of direct injection fuel pulses to shift out of the transition region in response to the pulse width signal of one of the plurality of direct injection fuel pulses of the combustion cycle being located in the transition region of the direct injector, while maintaining the number of pulses of the plurality of direct injection fuel pulses. In any or all of the preceding examples, additionally or optionally, the second condition includes an engine speed above a threshold, and the third condition includes an engine speed below a threshold or an engine NVH level above a threshold. In any or all of the preceding examples, additionally or optionally, the shifting and adjustment during each of the first, second, and third conditions includes adjusting the total fuel mass delivered by direct injection over the combustion cycle, the method further including adjusting the fuel mass delivered by intake manifold injection over the combustion cycle based on the adjusted total fuel mass delivered by direct injection.

[0124] Another exemplary system includes: an engine cylinder; a direct injector for fueling the cylinder; and a controller having computer-readable instructions stored in a non-transient memory for: estimating an initial fuel injection distribution of the cylinder's combustion cycle based on engine speed-load and engine temperature, the initial fuel injection distribution including a plurality of direct injection fuel pulses, at least one of the plurality of direct injection fuel pulses having a pulse width in a transition region of the direct injector; during a first condition, modifying the initial fuel injection distribution to a first modified fuel injection distribution having a smaller number of the plurality of direct injection fuel pulses, each of the smaller number of the plurality of direct injection fuel pulses having a larger pulse width in a lift region of the direct injector; and under a second condition, modifying the initial fuel injection distribution to a second modified fuel injection distribution, wherein the pulse width of a first group of the plurality of direct injection fuel pulses decreases to the impact region of the direct injector, while the pulse width of a second group of the plurality of direct injection fuel pulses rises to the lift region of the direct injector, while maintaining the number of the plurality of direct injection fuel pulses, wherein the total direct injection fuel mass in each of the first modified fuel injection distribution and the second modified fuel injection distribution is the same as the fuel mass in the initial fuel injection distribution. In the preceding examples, additionally or optionally, the first condition includes an engine speed above a threshold, and the second condition includes an engine speed below a threshold. In any or all of the preceding examples, additionally or optionally, the plurality of direct injection fuel pulses of the initial fuel injection distribution includes an initial number of direct injection fuel pulses, and wherein the modification during each of the first and second conditions is based on the initial number of direct injection fuel pulses, and further on the relationship between the pulse width of at least one of the plurality of direct injection pulses and the upper limit of the pulse width of the impact region and the lower limit of the pulse width of the lift region. In any or all of the preceding examples, additionally or optionally, the method further includes an intake manifold injector for fueling the cylinder, wherein the controller includes additional instructions for: modifying the initial fuel injection distribution to a third modified fuel injection distribution during the third condition, which includes adjusting the total direct injection fuel mass to shift the pulse width of at least one of the plurality of direct injection fuel pulses out of the transition region of the direct injector, and adjusting the intake manifold injection fuel mass based on the adjusted direct injection fuel mass.

[0125] Another example method includes: estimating an initial ratio of intake port fuel injection to direct injection fuel on the combustion cycle based on engine operating conditions; and updating the initial ratio to move the direct fuel injection out of the transition region in response to the direct fuel injection at the initial ratio being located in the transition region of the direct injector map. In the previous example, additionally or optionally, the transition region lies between the impact region and the lift region of the direct injector map, and wherein the direct injector variability in the transition region is higher than the direct injector variability in each of the impact and lift regions. In any or all of the previous examples, additionally or optionally, the update is based on the relationship between the pulse width of the direct fuel injection and each of the impact-transition boundary and the lift-transition boundary of the direct injector map. In any or all of the preceding examples, additionally or optionally, the update includes: in response to the distance between the direct fuel injection pulse width and the impact-transition boundary of the direct injector map being less than the distance between the direct fuel injection pulse width and the lift-transition boundary of the direct injector map, reducing the direct injection fuel mass to move the pulse width from the transition region of the direct injector map to the impact region, while increasing the intake port injection fuel mass. In any or all of the preceding examples, additionally or optionally, the update further includes: in response to the distance between the direct fuel injection pulse width and the impact-transition boundary of the direct injector map being greater than the distance between the direct fuel injection pulse width and the lift-transition boundary of the direct injector map, increasing the direct injection fuel mass to move the pulse width from the transition region of the direct injector map to the lift region, while decreasing the intake port injection fuel mass. In any or all of the preceding examples, additionally or optionally, the initial ratio of intake port injection fuel to direct injection fuel includes multiple direct injections over the combustion cycle, and wherein the increase and decrease are based on the number of multiple direct injections. In any or all of the preceding examples, additionally or optionally, the update further includes adjusting the number of multiple direct injections by reducing the number of multiple direct injections in order to move the pulse width from the transition region to the lift region. In any or all of the preceding examples, additionally or optionally, reducing the unadjusted number of multiple direct injections above a threshold in response to the multiple direct injections. In any or all of the preceding examples, additionally or optionally, the update further includes adjusting the number of multiple direct injections by increasing the number of multiple direct injections in order to move the pulse width from the transition region to the impact region. In any or all of the preceding examples, additionally or optionally, increasing the unadjusted number of multiple direct injections below a threshold in response to the multiple direct injections. In any or all of the preceding examples, additionally or optionally, the multiple direct injections include multiple direct injections during the intake stroke and / or compression stroke of the combustion cycle, and wherein the update further includes updating the split ratio of the directly injected fuel delivered during the intake stroke relative to the directly injected fuel delivered during the compression stroke.In any or all of the previous examples, additionally or optionally, the method may be implemented in a hybrid vehicle system.

[0126] Another exemplary method includes: during a first condition, reducing the number of the plurality of direct injection fuel pulses while maintaining the split ratio of direct injection fuel to port injection fuel in response to the pulse width of one of the plurality of direct injection fuel pulses in the combustion cycle being located in the transition region of the direct injector map; and during a second condition, adjusting the split ratio of direct injection fuel to port injection fuel in response to the pulse width of one of the plurality of direct injection fuel pulses in the combustion cycle being located in the transition region of the direct injector. In any or all of the preceding examples, additionally or optionally, adjusting the split ratio includes: increasing the split ratio of direct injection fuel to port injection fuel in the combustion cycle when more power is required, air-cooled, or spark advance is needed, such as at higher engine loads; and decreasing the split ratio of direct injection fuel to port injection fuel in the combustion cycle at lower loads when PM load is above a threshold. In any or all of the preceding examples, additionally or optionally, when more direct-injection fuel mass is required to move the pulse of the plurality of direct-injection fuel pulses out of the transition region, the split ratio of direct-injection fuel to intake fuel in the combustion cycle is increased; and when less direct-injection fuel mass is required to move the pulse of the plurality of direct-injection fuel pulses out of the transition region, the split ratio of direct-injection fuel to intake fuel in the combustion cycle is decreased. In any or all of the preceding examples, additionally or optionally, adjusting the split ratio includes maintaining the number of the plurality of direct-injection fuel pulses in the combustion cycle. In any or all of the preceding examples, additionally or optionally, adjusting the split ratio includes adjusting the number of the plurality of direct-injection fuel pulses in the combustion cycle, and the fuel mass delivered in each of the plurality of direct-injection fuel pulses. In any or all of the preceding examples, additionally or optionally, during the first condition, the pulse width of each of the reduced number of the plurality of direct-injection fuel pulses is located in the lift region of the direct injector. In any or all of the preceding examples, additionally or optionally, the first condition includes a higher engine load and the second condition includes a lower engine load.

[0127] Another exemplary engine system includes: an engine cylinder; a direct injector for fueling the cylinder; an intake port injector for fueling the cylinder; and a controller having computer-readable instructions stored in a non-transient memory for: estimating an initial fuel injection distribution for the combustion cycle of the cylinder based on engine speed-load and engine temperature, the initial fuel injection distribution including an initial split ratio of directly injected fuel to intake port injected fuel delivered by a plurality of direct injection fuel pulses, at least one of the plurality of direct injection fuel pulses having a pulse width in a transition region of the direct injector; and modifying the initial fuel injection distribution to change the split ratio of directly injected fuel to intake port injected fuel such that at least one of the plurality of direct injection fuel pulses is moved out of the transition region. In any or all of the preceding examples, additionally or optionally, the modification includes: increasing or decreasing the intake port injected fuel mass relative to the total direct injection fuel mass based on the relationship between the pulse width of at least one of the plurality of direct injection pulses and an upper limit of the pulse width of the impact region and a lower limit of the pulse width of the lift region of the direct injector. In any or all of the preceding examples, additionally or optionally, reducing the total direct injection fuel mass includes: reducing the number of multiple direct injection fuel pulses to move the pulse width of each pulse in the reduced number of direct injection fuel pulses to the lift region, and wherein increasing the total direct injection fuel mass includes increasing the number of multiple direct injection fuel pulses to move the pulse width of each pulse in the increased number of direct injection fuel pulses to the impact region.

[0128] In another representation, the engine is coupled to the hybrid vehicle system.

[0129] Note that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transient memory and can be executed by a control system including a controller combined with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, and / or functions shown may be executed in the order shown, in parallel, or in some cases omitted. Similarly, the order of processing is not necessary to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the shown actions, operations, and / or functions can be repeatedly performed, depending on the specific strategy used. Additionally, the described actions, operations, and / or functions can be graphically represented as code programmed into the non-transient memory of a computer-readable storage medium in the engine control system, wherein the described actions are performed by executing instructions in a system including various engine hardware components combined with electronic controllers.

[0130] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many variations are possible. For example, the above-described techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or attributes.

[0131] The following claims specifically point to certain combinations and sub-combinations that are considered novel and non-obvious. These claims may relate to a “one” element or a “first” element or its equivalent. Such claims should be understood to include a combination of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

Claims

1. A method for an engine, comprising: The initial ratio of intake manifold fuel to direct injection fuel in the combustion cycle is estimated based on engine operating conditions. as well as When PM load is above a threshold and / or engine NVH is above a threshold, in response to the direct fuel injection at the initial ratio being located in the transition region of the direct injector map, the initial ratio is updated to move the direct fuel injection out of the transition region. in: The direct injector mapping diagram depicts the relationship between injector pulse width and fuel quality. The transition region is located between the impact region and the lift region in the direct injector mapping, and The variability of the direct injector in the transition region is higher than that in each region of the impact region and the lift region.

2. The method of claim 1, wherein the update is based on the relationship between the pulse width of the direct fuel injection and each of the impact-transition boundary and lift-transition boundary of the direct injector map.

3. The method of claim 2, wherein the update comprises: In response to the direct fuel injection pulse width being less than the distance between the impact-transition boundary of the direct injector map and the lift-transition boundary of the direct injector map, the direct fuel injection mass is reduced to move the pulse width from the transition region of the direct injector map to the impact region, while the intake manifold injection mass is increased.

4. The method of claim 3, wherein the update further comprises: In response to the direct fuel injection pulse width being greater than the distance between the impact-transition boundary of the direct injector map and the lift-transition boundary of the direct fuel injection map, the direct fuel injection mass is increased to move the pulse width from the transition region of the direct injector map to the lift region, while the intake fuel injection mass is reduced.

5. The method of claim 4, wherein the initial ratio of intake manifold fuel to direct fuel injection comprises multiple direct injections over the combustion cycle, and wherein the increase and the decrease are based on the number of the multiple direct injections.

6. The method of claim 5, wherein the update further comprises adjusting the number of multiple direct injections by reducing the number of multiple direct injections to move the pulse width from the transition region to the lift region.

7. The method of claim 6, wherein the reduction in response to the unadjusted number of the multiple direct injections exceeds a threshold.

8. The method of claim 5, wherein the update further comprises adjusting the number of the multiple direct injections by increasing the number of the multiple direct injections in order to move the pulse width from the transition region to the impact region.

9. The method of claim 8, wherein the increase in response to the unadjusted number of the multiple direct injections is below a threshold.

10. The method of claim 5, wherein the multiple direct injections comprise multiple direct injections during the intake stroke and / or compression stroke of the combustion cycle, and wherein the update further comprises updating the split ratio of the direct injection fuel delivered during the intake stroke relative to the direct injection fuel delivered during the compression stroke.

11. An engine system comprising: Engine cylinders; A direct injector for fueling the cylinder; An intake manifold injector for refueling the cylinder; as well as The controller has computer-readable instructions stored in non-transient memory, the instructions being used for: The initial fuel injection distribution of the cylinder's combustion cycle is estimated based on engine speed-load and engine temperature. The initial fuel injection distribution includes an initial split ratio of directly injected fuel delivered by a plurality of direct injection fuel pulses to intake manifold fuel, at least one of the plurality of direct injection fuel pulses having a pulse width in the transition region of the direct injector map. as well as When PM load is above a threshold and / or engine NVH is above a threshold, the initial fuel injection distribution is modified to change the split ratio of direct injection fuel to intake manifold injection fuel, such that at least one of the plurality of direct injection fuel pulses is moved out of the transition region. in: The direct injector mapping diagram depicts the relationship between injector pulse width and fuel quality. The transition region is located between the impact region and the lift region in the direct injector mapping, and The variability of the direct injector in the transition region is higher than that in each region of the impact region and the lift region.

12. The system of claim 11, wherein the modification includes: Based on the relationship between the pulse width of at least one of the plurality of direct injection fuel pulses and the upper limit of the pulse width of the impact region and the lower limit of the pulse width of the lift region in the direct injector map, the intake manifold injection fuel mass is increased or decreased relative to the total direct injection fuel mass.

13. The system of claim 12, wherein reducing the total direct injection fuel mass comprises: Reducing the number of the plurality of direct injection fuel pulses to move the pulse width of each pulse in the reduced number of direct injection fuel pulses to the lift region, and wherein increasing the total direct injection fuel mass includes increasing the number of the plurality of direct injection fuel pulses to move the pulse width of each pulse in the increased number of direct injection fuel pulses to the impact region.

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