Method and system for adjusting engine cylinder air charge

Abstract

The present disclosure provides "Methods and systems for adjusting engine cylinder air charge." Systems and methods for operating an internal combustion engine based on an output of an intake manifold pressure sensor and an output of a cylinder pressure sensor are described. The systems and methods provide a way of determining a cylinder air charge such that a fuel injector has sufficient time to provide a desired amount of fuel to a cylinder during a cycle of the cylinder.

Description

Technical Field

[0001] This specification relates to methods and systems for determining the air volume of an internal combustion engine including a direct fuel injector. The methods and systems are particularly applicable to engines including an intake manifold pressure sensor and one or more cylinder pressure sensors. Background Technology

[0002] Internal combustion engines may include direct fuel injectors for supplying fuel directly to the engine cylinders. Direct fuel injectors can be sized such that they can accurately supply small or large amounts of fuel to the cylinders during the cylinder cycle. However, to supply a large amount of fuel to the cylinders to meet the driver's torque demands, the direct fuel injector may need to begin injecting fuel before the intake valve closes, thus injecting the desired amount of fuel into the cylinder. If the intake manifold pressure is sampled too early before the intake valve closes, the intake manifold pressure may not indicate air charge in the cylinders, especially during engine start-up when the intake manifold pressure changes significantly over a short period. Therefore, basing the amount of fuel injected into the cylinders solely on the intake manifold pressure before the intake valve closes can result in an air-fuel ratio in the cylinders that deviates from the desired cylinder air-fuel ratio. Furthermore, due to errors in cylinder air charge estimation, the cylinder ignition timing may deviate from the desired ignition timing. Summary of the Invention

[0003] The inventors have recognized the above-mentioned problems and have developed an engine operation method comprising: injecting a first amount of fuel into the cylinder during a cylinder cycle in response to an open-loop estimate of cylinder air charge, the open-loop estimate of cylinder air charge varying with the first cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop.

[0004] By adjusting the cylinder air charge estimate based on the first cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop, improved engine air-fuel control can be achieved. In particular, the inventors have recognized that observations of cylinder air charge from previous engine starts can form the basis for changing the cylinder air charge estimate for the current engine start. A cylinder air charge estimate determined during a previous engine start and based on the pressure in the cylinder corresponding to a specific first cylinder ignited and the total number of actual combustion events since the most recent engine stop can form the basis for updating the cylinder air charge estimate based on engine intake manifold pressure during the current engine start. The cylinder air charge estimate determined during the current engine start and based on cylinder pressure provides a cylinder air charge estimate that includes the effects of intake manifold airflow characteristics and cylinder head airflow characteristics during engine start. A cylinder air charge estimate determined during a previous engine start and based on cylinder pressure can also form the basis for adjusting the cylinder air charge estimate based on intake manifold pressure during the current engine start. The cylinder air filling estimate determined during a previous engine start-up can be modified to reflect the intake manifold pressure-based cylinder air filling estimate during the current engine start-up, taking into account the influence of intake manifold and cylinder head airflow characteristics. In this way, the cylinder air filling estimate based on intake manifold pressure, determined during the current engine start-up, can be adjusted to more closely approximate the actual air volume in the cylinders during engine start-up. Therefore, fuel injection can be initiated earlier in the cylinder cycle based on the improved cylinder air filling estimate, allowing the desired amount of fuel to be injected during the cylinder cycle.

[0005] This specification offers several advantages. Specifically, the method provides improved engine air-fuel ratio control. Furthermore, the method provides more repeatable engine starting. Even further, the method improves engine starting regardless of which engine cylinder ignites first after the most recent engine stop.

[0006] The advantages and other advantages and features of this specification will become readily apparent when considered alone or in conjunction with the accompanying drawings, based on the following detailed description.

[0007] It should be understood that the above description of the invention is provided to introduce a series of concepts in a simplified form, which are further described in the detailed embodiments. This does not imply identification of the key or essential features of the claimed subject matter, and the scope of the claimed subject matter is uniquely defined by the claims following the detailed embodiments. Furthermore, the claimed subject matter is not limited to implementations that address any of the shortcomings pointed out above or in any part of this disclosure. Attached Figure Description

[0008] The advantages described herein will be more fully understood by reading, alone or with reference to, the examples of embodiments referred to herein as specific implementations, in which:

[0009] Figure 1 This is a schematic diagram of an engine;

[0010] Figure 2 An exemplary table of cylinder air charge scalars is shown;

[0011] Figures 3 to 5 An exemplary flowchart of a method for operating an engine is shown; and

[0012] Figure 6 It is a graph showing the starting sequence of two engines. Detailed Implementation

[0013] This specification relates to adjusting cylinder air charging estimates to improve engine start-up and air-fuel ratio control during engine start-up. Fuel can be injected into the engine in response to two different cylinder air charging estimates in the cylinder cycle. Fuel can be injected during the first fuel pulse that occurs during the cylinder's intake stroke. Fuel can also be injected during the second fuel pulse that occurs during the cylinder's compression stroke. Cylinder air charging can be targeted at... Figure 1 An estimation is performed for the type of engine shown. The cylinder charge estimate from a previous engine start can serve as the basis for changing the value of the cylinder air charge scalar, which varies with the first cylinder ignited after the engine stops and the total number of actual combustion events after the engine stops. Figures 3 to 5 A method for operating the engine is shown. Figure 6 A portion of an exemplary engine starting sequence is shown in the figure.

[0014] refer to Figure 1 The internal combustion engine 10 is controlled by an electronic engine controller 12. The internal combustion engine 10 includes multiple cylinders, one of which is in operation. Figure 1As shown in the diagram. Engine 10 includes a cylinder head 35 and a cylinder block 33, the cylinder block 33 including a combustion chamber 30 and cylinder walls 32. A piston 36 is positioned therein and reciprocates via a connection to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 (e.g., a low-voltage (operating at less than 30 volts) motor) includes a pinion shaft 98 and a pinion 95. The pinion shaft 98 selectively advances the pinion 95 to engage the ring gear 99. The starter 96 may be mounted directly to the front or rear of the engine. In some examples, the starter 96 may selectively supply torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a basic state when not engaged with the engine crankshaft. The combustion chamber 30 is shown communicating with an intake manifold 44 and an exhaust manifold 48 via corresponding intake valves 52 and exhaust valves 54. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. The position of the intake camshaft 51 can be determined by the intake camshaft sensor 55. The position of the exhaust camshaft 53 can be determined by the exhaust camshaft sensor 57. The intake valve 52 can be selectively activated and deactivated by the valve activation device 59. The exhaust valve 54 can be selectively activated and deactivated by the valve activation device 58. The valve activation devices 58 and 59 can be electromechanical devices.

[0015] Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, a direct injection method known to those skilled in the art. Fuel injector 66 delivers liquid fuel in proportion to the pulse width from controller 12. Fuel is delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). In one example, a high-pressure two-stage fuel system may be used to generate higher fuel pressure.

[0016] Furthermore, intake manifold 44 is shown communicating with turbocharger compressor 162 and engine intake port 42. In other examples, compressor 162 may be a supercharger compressor. Shaft 161 mechanically connects turbocharger turbine 164 to turbocharger compressor 162. An optional electronic throttle 62 adjusts the position of throttle plate 64 to control airflow from compressor 162 to intake manifold 44. Because the inlet of throttle 62 is within boost chamber 45, the pressure in boost chamber 45 may be referred to as throttle inlet pressure. Throttle outlet is in intake manifold 44. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44, such that throttle 62 is an intake manifold throttle. Compressor recirculation valve 47 may be selectively adjusted to multiple positions between fully open and fully closed. The exhaust valve 163 can be adjusted via controller 12 to allow exhaust gas to selectively bypass turbine 164 to control the speed of compressor 162. Air filter 43 cleans the air entering engine intake 42.

[0017] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Pressure in combustion chamber or cylinder 30 can be determined via cylinder pressure sensor 77. Universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled upstream of catalytic converter 70 to exhaust manifold 48. Alternatively, dual-state exhaust oxygen sensor can replace UEGO sensor 126. Exhaust pressure in exhaust manifold 48 can be determined via pressure sensor 78.

[0018] In one example, converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each having multiple bricks, may be used. In one example, converter 70 may be a three-way catalytic converter.

[0019] Controller 12 in Figure 1 The computer is shown as a conventional microcomputer, which includes: a microprocessor unit 102, an input / output port 104, a read-only memory 106 (e.g., non-transitory memory), a random access memory 108, a keep-alive memory 110, and a conventional data bus. The controller 12 is shown to receive, in addition to the signals previously discussed, various signals from sensors coupled to the engine 10, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling manifold 114; position sensor 134 coupled to accelerator pedal 130 for sensing force applied by human foot 132; position sensor 154 coupled to brake pedal 150 for sensing force applied by foot 152; measurement of engine manifold pressure (MAP) from pressure sensor 122 coupled to intake manifold 44; engine position sensor from Hall effect sensor 118 for sensing crankshaft 40 position; measurement of air mass entering the engine from sensor 120; and measurement of throttle position from sensor 68. Atmospheric pressure (sensor not shown) can also be sensed for processing by the controller 12. In a preferred aspect of this specification, engine position sensor 118 generates a predetermined number of equidistant pulses for each crankshaft revolution, thereby determining the engine speed (RPM).

[0020] During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, the exhaust valve 54 is generally closed and the intake valve 52 is open. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its maximum volume) is commonly referred to by those skilled in the art as bottom dead center (BDC).

[0021] During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its minimum volume) is commonly referred to by those skilled in the art as top dead center (TDC). Fuel is introduced into the combustion chamber during what is hereinafter referred to as injection. During what is hereinafter referred to as ignition, the injected fuel is ignited by a known ignition device such as spark plug 92, resulting in combustion.

[0022] During the expansion stroke, the expanding gas pushes piston 36 back to the BDC. Crankshaft 40 converts the piston movement into rotational torque on the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture into exhaust manifold 48, and piston returns to the TDC. It should be noted that the above is only shown as an example, and the opening and / or closing timing of the intake and exhaust valves can vary, such as to provide positive or negative valve overlap, delayed intake valve closing, or various other examples.

[0023] Figure 1The system provides a vehicle system comprising: an engine; an intake manifold pressure sensor coupled to the engine; a cylinder pressure sensor coupled to the engine and partially located within a cylinder of the engine; and a controller including executable instructions stored in a non-transitory memory, the executable instructions being configured to: provide a first fuel injection to a cylinder of the engine during a cylinder cycle in response to an output of the intake manifold pressure sensor during a cylinder cycle; and provide a second fuel injection to the cylinder during a cylinder cycle in response to an output of the cylinder pressure sensor. The system also includes additional instructions for estimating cylinder air charge via the intake manifold pressure sensor. The system further includes additional instructions for estimating cylinder air charge via the cylinder pressure sensor. The system includes, wherein injecting fuel to a cylinder of the engine during a cylinder cycle in response to an output of the intake manifold pressure sensor comprises: injecting fuel via a direct fuel injector during the intake stroke of the cylinder. The system includes, wherein injecting fuel into an engine cylinder during a cylinder cycle in response to the output of a cylinder pressure sensor comprises: injecting fuel via a direct fuel injector during the compression stroke of the cylinder. The system also includes additional instructions for adjusting ignition timing in response to the output of the cylinder pressure sensor during a cylinder cycle.

[0024] Figure 2 Table 200 shows the cylinder air charge scalar. Table 200 may be included in... Figure 1 The controller 12 shown is stored in (e.g., non-transitory or transient) memory. In this example, table 200 comprises nine rows (1-9) and four columns (1-4). Table 200 can be applied to systems including four-cylinder engines with cylinders 1-4. Of course, for systems including a larger number of cylinders or where it may be desirable to compensate for more than nine combustion events, a table larger than 9×4 is contemplated. Rows represent cylinder combustion events since the most recent engine stop (e.g., when the engine speed is zero). A cylinder combustion event is the occurrence of combustion in an engine cylinder, where combustion is initiated in the cylinder by supplying air, fuel, and a spark to the cylinder. For example, a first combustion event since the most recent engine stop may occur in a cylinder that is supplied with air, fuel, and a spark to ignite the air-fuel mixture therein since the most recent engine stop. A second combustion event since the most recent engine stop may occur in a cylinder that receives air, fuel, and a spark to ignite the air-fuel mixture therein after the most recent engine stop.

[0025] The column designates the first cylinder to be ignited since the most recent engine stop. For example, if cylinder number three is the first cylinder to receive air, fuel, and spark since the most recent engine stop, then cylinder number three could be the first cylinder to be ignited since the most recent engine stop. The first cylinder to be ignited can be based on the engine stop position and other considerations. In some examples, the first cylinder to be ignited can be the cylinder in its intake stroke with its piston closest to the crankshaft position where the intake valve of that cylinder is closed. The first cylinder to be ignited can vary with starting, and the selection criteria for the first cylinder to be ignited since the most recent engine stop can also vary depending on engine operating conditions.

[0026] The first row is labeled 202, and the ninth row is labeled 204. The first column is labeled 206, and the fourth column is labeled 208. Each row / column represents the scalar value α for maintaining cylinder air supply. xy , where x indicates the row number of table 200, and y indicates the column number. Therefore, α 11 This represents the cylinder air charge scalar value for the first combustion event after the most recent engine stop, assuming cylinder number one is the first cylinder to ignite since the most recent engine stop. When cylinder number one is to become the first cylinder to ignite (e.g., burn air and fuel) after the most recent engine stop, this is expressed by the scalar value α. 11 The scalar is applied by multiplying the estimated cylinder air charge of cylinder one. Similarly, when cylinder three becomes the ninth cylinder to burn air and fuel since the most recent engine shutdown, the scalar α is applied by multiplying it by the estimated cylinder air charge of cylinder three. 93 The α value is adjusted based on data from past engine starts, such as... Figures 3 to 5This is explained in further detail in the method. Therefore, for each cylinder ignition event since the most recent engine start, the cylinder air charge can be adjusted in response to the cylinder air charge introduced during the previous engine start. This allows for individual adjustment of the individual cylinder air charge based on the ignition event since the most recent engine stop. This allows for compensation of the individual cylinder air charge for the engine intake manifold aerodynamics and cylinder head aerodynamics during engine start. Furthermore, for each cylinder ignition event since the most recent engine start, the cylinder air quantity can be adjusted according to which engine cylinder ignites first after the most recent engine stop, so that pressure changes in air charge that can propagate through the engine intake manifold and affect other cylinders can be taken into account. For example, if cylinder 1 of a four-cylinder engine is the first cylinder to receive air and spark after the most recent engine stop, then the cylinder air charge of cylinder 3 (the next cylinder in a 1-3-4-2 engine firing order) may be affected by the airflow dynamics of cylinder 1, which receives air before cylinder 3. Therefore, when cylinder 3 is the second cylinder to be ignited (e.g., to burn air and fuel) after the most recent engine stop, the scalar α... 21 The air volume of cylinder number three can be modified.

[0027] Now for reference Figures 3 to 5 The flowchart for operating a hybrid vehicle is shown. Figures 3 to 5 At least a portion of the method can be stored as Figure 1 The executable instructions in the non-transitory memory of the system shown are merged in. Additionally, Figures 3 to 5 Part of the method can occur in the physical world as an operation or action executed by a controller to change the operating state of one or more devices. Some of the control parameters described herein can be determined via controller 12 receiving inputs from the previously described sensors and actuators. Figures 3 to 5 The method can also provide Figure 6 The operation sequence shown.

[0028] At 302, method 300 determines whether engine position determination at engine shutdown and engine stop (e.g., zero engine rotation) is desirable. In one example, engine position determination at engine shutdown and engine stop is desirable if a human driver initiates an engine stop or requests an automatic engine stop (e.g., an engine stop requested via a controller in response to vehicle operating conditions). If method 300 determines that engine position determination at engine shutdown and engine stop is desirable, the answer is yes and method 300 proceeds to 304. Otherwise, the answer is no and method 300 proceeds to 306.

[0029] At 304, method 300 stops delivering spark and fuel to the engine cylinders. Method 300 also monitors the pressure in each engine cylinder and the engine position as the engine decelerates to zero speed. Method 300 tracks the current stroke and piston position of each cylinder up to, including, when the engine stops. Method 300 stores the engine position and stroke data in the controller memory. Method 300 proceeds to 306.

[0030] At 306, method 300 determines whether an engine start request has been made. Engine start can be requested via input from a human to the human / machine interface or (if no explicit request is made by a human) via an automatic engine start request from the controller. If method 300 determines that an engine start request has been made, it answers yes and method 300 proceeds to 308. Otherwise, it answers no and method 300 proceeds to exit.

[0031] At 308, method 300 determines whether the engine position was determined when the engine was off. Method 300 can determine whether the engine position was determined when the engine was off via a value stored in the controller memory. If the controller memory contains engine position data determined when the engine was off, the answer is yes and method 300 proceeds to 380. Otherwise, the answer is no and method 300 proceeds to 310.

[0032] At 380, method 300 starts the engine by rotating the starter motor (e.g., by rotating the engine via an electric motor). The engine can be started via a starter, an integrated starter / generator, or by rotating the motor in the vehicle's drivetrain. Method 300 proceeds to 314.

[0033] At 310, method 300 rotates the starter engine (e.g., by rotating the engine via an electric motor) to start the engine. The engine can be started via a starter, an integrated starter / generator, or by rotating an electric motor in the vehicle's drivetrain. Method 300 proceeds to 312.

[0034] At 312, method 300 monitors the pressure in each engine cylinder and the engine position when the engine is started. Method 300 determines the engine position based on the crankshaft position sensor and via the cylinder pressure sensor output. For example, if the cylinder pressure is not decreasing or is decreasing at a rate less than a threshold while the piston in the cylinder is moving away from top dead center as the engine is started and rotated, then method 300 can determine that the cylinder is in the intake stroke. Specifically, method 300 determines which cylinder's piston is closest to bottom dead center during the intake stroke when the engine is started via the cylinder pressure sensor and the engine crankshaft position sensor. Method 300 proceeds to 314.

[0035] At 314, method 300 determines, based on predicted emissions, whether it is desirable to add fuel to the cylinder closest to bottom dead center (BDC) during the intake stroke. In one example, engine emissions (e.g., HC, NOx, and CO) are stored in the controller memory, and they are stored based on the first cylinder ignited (e.g., combustion of air and fuel). When the first cylinder ignited is a particular cylinder and when the piston of that particular cylinder is closer to BDC during the intake stroke, the engine can produce higher emissions, possibly due to reduced fuel evaporation in the cylinder and fuel buildup in the gaps and clearances within the cylinder (e.g., the space between the cylinder wall and the piston). If the predicted engine emissions from the cylinder in its intake stroke, whose piston is closest to BDC, are greater than a threshold amount, the answer is no and method 300 proceeds to 385. Otherwise, the answer is yes and method 300 proceeds to 316.

[0036] At 385, method 300 does not supply fuel to the cylinder currently in its intake stroke whose piston is closest to bottom dead center (BDC) of the engine. Therefore, method 300 skips ignition to the cylinder currently in its intake stroke whose piston is closest to BDC, thereby reducing engine emissions. Method 300 selects the next cylinder in the combustion sequence as the first cylinder to be ignited since the most recent engine stop. For example, if the engine is a four-cylinder four-stroke engine with a 1-3-4-2 firing order, and cylinder number one is currently in its intake stroke, but engine emissions may be high for cylinder number one, then cylinder number three is selected as the first cylinder to be ignited since the most recent engine stop. Method 300 proceeds to 316.

[0037] At point 316, method 300 determines the open-loop cylinder air charge estimate for the cylinder selected as the first to be ignited since the most recent engine stop. Method 300 determines the cylinder air charge based on the following equation:

[0038]

[0039] Where Mai is the air mass in the cylinder determined during the intake stroke of the first cylinder selected for ignition, and P i V is the intake manifold pressure during the intake stroke of the first cylinder selected for ignition, R is the gas constant, T is the temperature in the cylinder, and α is the intake manifold pressure. xy yes Figure 2 The scalar quantity of air supplied to the cylinder as described in the explanation. α xyThe value is retrieved from the controller memory and is determined based on cylinder air charging data determined during past engine starts, in which the engine operating conditions were substantially the same as those described at 320 (e.g., the same engine temperature). Mai estimation allows for earlier fuel injection during the cylinder cycle, enabling the injection of the desired amount of fuel into the cylinder. Method 300 proceeds to 318.

[0040] At 318, method 300, based on the open-loop cylinder air charge quantity determined at 316 and the engine's desired air-fuel ratio, delivers a portion of the fuel to be delivered to the first ignited cylinder during the cycle of the first ignited cylinder. In one example, method 300 determines the amount of fuel to be injected into the first ignited cylinder since the most recent engine stop via the following equation:

[0041] Mfi = Mai·FAR·DISFF

[0042] Where Mfi is the mass of fuel to be injected during the intake stroke of the first cylinder selected for combustion, Mai is the mass of air in the cylinder determined during the intake stroke of the first cylinder selected for ignition, FAR is the desired air-fuel ratio (e.g., 1:15), and DISFF is the desired fuel fraction for the intake stroke (e.g., a value of 0.75 would result in the amount of fuel to be injected being 75% of the estimated air mass in the cylinder multiplied by the air-fuel ratio to be injected into the cylinder). DISFF is restricted to a value less than 1, such that less fuel than would be expected to be injected into the cylinder to meet the desired air-fuel ratio. The value of DISFF allows for the injection of additional fuel during the cylinder compression stroke to correct for an air charge estimation error compensated for by adding additional fuel to the first cylinder ignited since the most recent engine stop. While injecting fuel during the intake stroke of the first cylinder ignited since the most recent engine stop, the starter engine continues to be turned. Method 300 proceeds to 320.

[0043] At position 320, method 300 updates the cylinder air filling estimate from the first cylinder ignited since the most recent engine stop. The cylinder air filling estimate is updated according to the following equation:

[0044]

[0045] Mac is the air mass in the cylinder determined during the compression stroke of the first cylinder selected for ignition, and P cV is the pressure in the first cylinder selected for ignition during the compression stroke, V is the cylinder volume at the determined pressure, R is the gas constant, and T is the cylinder temperature. The cylinder temperature can be inferred from the intake air temperature and engine coolant temperature. The pressure in the first cylinder ignited or burning air and fuel since the most recent engine stop is determined by a cylinder pressure sensor after the intake valve of the first cylinder ignited since the most recent engine stop closes. The cylinder volume is determined based on the engine position and engine displacement. Mac estimation allows for a more accurate estimation of the second fuel injection in the cylinder based on the cylinder air volume.

[0046] Additionally, method 300 determines α corresponding to the first ignition event of the cylinder selected as the first cylinder to be ignited since the most recent engine stop. xy The adjustment amount of the value. In one example, if the value of Mac-Mai is greater than the threshold, then α is adjusted. xy The value of α is increased by a predetermined amount (e.g., 0.005). If the value of Mac-Mai is less than the threshold, then α is increased. xy The value of α is reduced by a predetermined amount (e.g., 0.005). xy The updated values ​​of α are stored in the controller memory for subsequent engine starts. The initial value of each α can be equal to 1. The adjusted α... xy The value is stored at a specific location in the memory, the location depending on or based on the first combustion event (x) since the most recent engine stop and the first cylinder (y) selected for ignition. Method 300 proceeds to 322.

[0047] At 322, method 300 delivers replenishment fuel to the selected first cylinder (e.g., providing fuel at the desired fuel-air ratio (FAR) in the first ignited cylinder). Specifically, method 300 delivers a portion of the fuel to be delivered to the first ignited cylinder during the ignition cycle, based on the cylinder air charge quantity determined at 320 and the engine's desired air-fuel ratio. In one example, method 300 determines the amount of fuel to be injected into the first cylinder ignited since the most recent engine stop via the following equation:

[0048] Mfc=((Mac-Mai)·FAR)+((Mai·FAR)·(l-DISFF))

[0049] Where Mfc is the mass of fuel to be injected during the compression stroke of the first cylinder selected for ignition, Mac is the mass of air in the first cylinder selected for ignition determined by cylinder pressure, Mai is the mass of air in the cylinder determined during the intake stroke of the first cylinder selected for ignition, FAR is the desired air-fuel ratio (e.g., 1:15), and DISFF is the desired fuel fraction for the intake stroke (e.g., a value of 0.75 would result in the amount of fuel to be injected being 75% of the estimated air mass in the cylinder multiplied by the air-fuel ratio to be injected into the cylinder). Injecting the fuel margin of the first combustion event of the engine during the compression stroke of the first cylinder selected for ignition since the most recent engine stop allows for a correction of the injected fuel amount while still allowing a larger amount of fuel to enter the engine cylinder (because the cylinder air charge value can be high during engine start-up). Method 300 proceeds to 324.

[0050] At position 324, method 300 releases a spark in the first cylinder ignited since the most recent engine stop. The ignition timing is adjusted based on the cylinder air charge determined by the pressure in the first ignited cylinder. For example, the ignition timing can be determined by the following equation:

[0051] SAF = f(N, Mac)

[0052] Where SAF is ignition timing, N is engine speed, and Mac is cylinder air charge based on the pressure in the first cylinder ignited. Note that in some examples, the cylinder load value based on Mac can be used instead of Mac. Method 300 proceeds to 326.

[0053] At point 326, method 300 determines the open-loop cylinder air charge estimate for the next cylinder in the combustion sequence. For example, if the open-loop cylinder air charge is determined for cylinder number two of an engine with a 1-3-4-2 firing order, then the next cylinder air charge estimate is for cylinder number one. Method 300 determines the cylinder air charge based on the following equation:

[0054]

[0055] Where Mai is the air mass in the next cylinder to be ignited, determined during the intake stroke of the next cylinder selected for ignition, and P i V is the intake manifold pressure during the intake stroke of the next cylinder to be ignited, R is the gas constant, T is the temperature in the cylinder, and α is the intake manifold pressure. xy yes Figure 2 The scalar quantity of air supplied to the cylinder as described in the explanation. α xyThe value is retrieved from memory and is determined based on cylinder air charging data determined during past engine starts, in which engine conditions were substantially the same (e.g., the same engine temperature), the same total number of actual combustion events since engine start, and the same first cylinder ignited at engine start. Method 300 proceeds to 328.

[0056] At 328, method 300, based on the open-loop cylinder air charge quantity determined at 316 and the engine's desired air-fuel ratio, delivers a portion of the fuel to be delivered to the next ignited cylinder during the cycle of the next ignited cylinder. In one example, method 300 determines the amount of fuel to be injected into the next ignited cylinder since the most recent engine stop via the following equation:

[0057] Mfi = Mai·FAR·DISFF

[0058] Where Mfi is the mass of fuel to be injected during the intake stroke of the next cylinder selected for ignition or combustion, Mai is the mass of air in the cylinder determined during the intake stroke of the next cylinder selected for ignition, FAR is the desired air-fuel ratio, and DISFF is the desired fuel fraction for the intake stroke. DISFF is constrained to a value less than 1, such that less fuel is injected into the cylinder than is expected to satisfy the desired air-fuel ratio. The value of DISFF allows for the injection of additional fuel during the cylinder compression stroke to correct for an air filling estimation error, which is compensated for by adding additional fuel to the next cylinder ignited since the most recent engine stop. Method 300 proceeds to 330.

[0059] At position 330, method 300 provides a corrected cylinder air filling estimate. The corrected cylinder filling estimate can be expressed as:

[0060] Mac=f(CylN,Pc,IMAP,EMAP,Mfi,Vc,T,R)

[0061] Where Mac is the mass of air in the cylinder determined during the compression stroke of the next cylinder selected for ignition, Pc is the pressure in the next cylinder selected for ignition during the compression stroke, Vc is the volume of the next cylinder at the determined pressure, R is the gas constant, T is the temperature in the cylinder, CylN is the total number of actual engine combustion events since the most recent engine stop, IMAP is the intake manifold absolute pressure when the intake valve of the next cylinder is closed, EMAP is the exhaust manifold absolute pressure when the exhaust valve of the next cylinder is closed, and Mfi is the mass of fuel to be injected during the intake stroke of the next cylinder selected for ignition or combustion. The cylinder temperature can be inferred from the intake air temperature and the engine coolant temperature. The pressure in the next cylinder for ignition or combustion of air and fuel since the most recent engine stop is determined by the cylinder pressure sensor after the intake valve of the next cylinder ignited after the most recent engine stop is closed. Method 300 proceeds to 332.

[0062] At 332, method 300 can adjust α corresponding to the next ignition event of the cylinder selected as the next cylinder to be ignited since the most recent engine stop. xy The value of α. In one example, if the value of Mac-Mai for the next cylinder ignited since the most recent engine stop is greater than a threshold, then α is set. xy The value is increased by a predetermined amount (e.g., 0.005). If the value of Mac-Mai for the next cylinder ignited since the most recent engine stop is less than the threshold, then α is increased. xy The value of α is reduced by a predetermined amount (e.g., 0.005). xy The updated value is stored in the controller memory for subsequent engine starts. The adjusted α... xy The value is stored at a specific location in the memory, the location depending on or based on the first combustion event (x) since the most recent engine stop and the first cylinder (y) selected for ignition. Method 300 proceeds to 334.

[0063] At 334, method 300 delivers replenishment fuel (e.g., fuel supplying the desired fuel-air ratio (FAR) in the cylinder) to the next cylinder to be ignited. Specifically, method 300 delivers a portion of the fuel to be delivered to the next cylinder to be ignited during the cycle of the next cylinder, based on the cylinder air charge quantity determined at 330 and the engine's desired air-fuel ratio. In one example, method 300 determines the amount of fuel to be injected into the next cylinder to be ignited since the most recent engine stop via the following equation:

[0064] Mfc=((Mac-Mai)·FAR)+((Mai·FAR)·(l-DISFF))

[0065] Where Mfc is the mass of fuel to be injected during the compression stroke of the next cylinder to be ignited, Mac is the mass of air in the next cylinder to be ignited, determined by cylinder pressure, Mai is the mass of air in the cylinder, determined during the intake stroke of the next cylinder to be ignited, FAR is the desired air-fuel ratio (e.g., 1:15), and DISFF is the desired fuel fraction for the intake stroke. Injecting the fuel margin for the next combustion event of the engine during the compression stroke of the next cylinder to be ignited since the most recent engine stop allows for a correction of the injected fuel quantity while still allowing a larger amount of fuel to enter the engine cylinder (because the cylinder air charge can be high during engine start-up). Method 300 proceeds to 336.

[0066] At position 336, method 300 releases a spark in the next cylinder ignited since the most recent engine stop. The ignition timing is adjusted based on the cylinder air charge determined by the pressure in the next ignited cylinder. For example, the ignition timing can be determined by the following equation:

[0067] SAF = f(N, Mac)

[0068] Where SAF is the ignition timing, N is the engine speed, and Mac is the cylinder air charge in the next cylinder to be ignited. Note that in some examples, the cylinder load value based on Mac can replace Mac. Method 300 also updates the next cylinder to be ignited. For example, if the engine is a four-cylinder engine with a 1-3-4-2 firing order and cylinder number one has just been ignited, then the next cylinder to be ignited is updated to cylinder number three. Method 300 proceeds to 338.

[0069] At 338, method 300 determines whether an engine cycle is complete. If the engine is a four-stroke engine, then the method determines that an engine cycle is complete after two revolutions following the initial introduction of air into the first cylinder that has been ignited since the most recent engine stop. If the method determines that an engine cycle is complete, it answers yes and method 300 proceeds to 340. Otherwise, it answers no and method 300 returns to 326.

[0070] At position 340, method 300 determines the open-loop cylinder air charge estimate for the next cylinder in the combustion sequence. Method 300 determines the cylinder air charge based on the following equation:

[0071]

[0072] Where Mai is the air mass in the next cylinder to be ignited, determined during the intake stroke of the next cylinder selected for ignition, and P iV is the intake manifold pressure during the intake stroke of the next cylinder to be ignited, V is the volume of the next cylinder to be ignited at a given pressure, R is the gas constant, T is the temperature in the cylinder, and α is the intake manifold pressure. xy yes Figure 2 The cylinder air charge scalar quantity described in the explanation. Method 300 proceeds to 342.

[0073] At 342, method 300, based on the open-loop cylinder air charge quantity determined at 340 and the engine's desired air-fuel ratio, delivers a portion of the fuel to be delivered during the cycle of the first ignited cylinder to the next ignited cylinder, as described at 328. Method 300 proceeds to 344.

[0074] At position 344, method 300 provides an updated cylinder air filling estimate. The corrected cylinder filling estimate can be expressed as:

[0075] Mac=f(CylN,Pc,IMAP,EMAP,Mfi,Vc,T,R,CR1,CRE)

[0076] Where Mac is the mass of air in the cylinder determined during the compression stroke of the next cylinder to be ignited, Pc is the pressure in the next cylinder to be ignited during the compression stroke, Vc is the volume of the next cylinder at the determined pressure, R is the gas constant, T is the temperature in the cylinder, CylN is the total number of actual engine combustion events since the most recent engine stop, IMAP is the intake manifold absolute pressure when the intake valve of the next cylinder is closed, EMAP is the exhaust manifold absolute pressure when the exhaust valve of the next cylinder is closed, CR1 is the cylinder internal residual (e.g., exhaust), CRE is the cylinder exhaust residual due to external exhaust recirculation, and Mfi is the mass of fuel to be injected during the intake stroke of the next cylinder to be ignited or combusted. The cylinder temperature can be inferred from the intake air temperature and the engine coolant temperature. The pressure in the next cylinder to be ignited or combusted with air and fuel since the most recent engine stop is determined by the cylinder pressure sensor after the intake valve of the next cylinder to be ignited since the most recent engine stop is closed. Method 300 proceeds to 346.

[0077] At 346, method 300 delivers replenishment fuel (e.g., fuel supplying the desired fuel-air ratio (FAR) in the cylinder) to the next cylinder to be ignited. Specifically, method 300 delivers a portion of the fuel to be delivered to the next cylinder to be ignited during the cycle of the next cylinder, based on the cylinder air charge quantity determined at 344 and the engine's desired air-fuel ratio. In one example, method 300 determines the amount of fuel to be injected into the next cylinder to be ignited since the most recent engine stop via the following equation:

[0078] Mfc=((Mac-Mai)·FAR)+((Mai·FAR)·(l-DISFF))

[0079] Where Mfc is the mass of fuel to be injected during the compression stroke of the next cylinder to be ignited, Mac is the mass of air in the next cylinder to be ignited, determined by cylinder pressure, Mai is the mass of air in the cylinder, determined during the intake stroke of the next cylinder to be ignited, FAR is the desired air-fuel ratio (e.g., 1:15), and DISFF is the desired fuel fraction for the intake stroke. Injecting the fuel margin for the next combustion event of the engine during the compression stroke of the next cylinder to be ignited since the most recent engine stop allows for a correction of the injected fuel quantity while still allowing a larger amount of fuel to enter the engine cylinder (because the cylinder air charge can be high during engine start-up). Method 300 proceeds to 348.

[0080] At position 348, method 300 releases a spark in the next cylinder ignited since the most recent engine stop. The ignition timing is adjusted based on the cylinder air charge determined by the pressure in the next ignited cylinder. For example, the ignition timing can be determined by the following equation:

[0081] SAF = f(N, Mac)

[0082] Where SAF is the ignition timing, N is the engine speed, and Mac is the cylinder air charge in the next cylinder to be ignited. Note that in some examples, the cylinder load value based on Mac can replace Mac. Method 300 also updates the next cylinder to be ignited. Method 300 proceeds to 350.

[0083] At 350, method 300 determines whether an engine shutdown request has been made. The engine can be shut down in response to a request from a human driver, an autonomous driver system, or the start / stop engine controller. If the method determines that an engine shutdown request has been made, it answers yes and method 300 proceeds to 352. Otherwise, it answers no and method 300 returns to 340.

[0084] At point 352, method 300 stops delivering fuel and spark to the engine cylinders to stop the engine from rotating. Method 300 proceeds to exit.

[0085] In this way, the cylinder air charge value can be adjusted in response to the first engine cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop. The fuel injected into the engine cylinders can be adjusted in response to engine cylinder air charge estimation.

[0086] therefore, Figures 3 to 5The method provides an engine operation method comprising: injecting a first amount of fuel into the cylinder during a cylinder cycle in response to an open-loop estimate of cylinder air charge, the open-loop estimate of cylinder air charge varying with a first cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop. The method further comprises: injecting a second amount of fuel into the cylinder during the cylinder cycle in response to cylinder pressure. The method includes: wherein the first amount of fuel is injected during the intake stroke of the cylinder. The method includes: wherein the second amount of fuel is injected during the compression stroke of the cylinder. The method includes: wherein the open-loop estimate of cylinder air charge is further based on intake manifold pressure. The method includes: wherein the engine speed is zero during the most recent engine stop. The method includes: wherein the first amount of fuel is injected via a direct fuel injector.

[0087] Figures 3 to 5 The method also provides an engine operation method comprising: injecting a first amount of fuel into the cylinder during a cylinder cycle in response to a first cylinder air charge estimation, the first cylinder air charge estimation being based on a scalar quantity that varies with the number of first cylinders ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop; and adjusting the scalar quantity in response to a second cylinder air charge estimation. The method further comprises: wherein the second cylinder air charge estimation is further based on the pressure in the cylinder during the cylinder cycle. The method further comprises: storing the adjusted scalar quantity in a controller memory based on the first cylinders ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop. The method further comprises: injecting a second amount of fuel into the cylinder during the cylinder cycle in response to the pressure in the cylinder. The method further comprises: wherein the first cylinder air charge estimation is further based on intake manifold pressure. The method further comprises: adjusting the ignition timing in response to the pressure in the cylinder. The method includes: wherein the cylinder is a second cylinder ignited since the most recent engine stop, and further includes: adjusting a second amount of fuel injected into the cylinder during the cycle of the cylinder based on exhaust pressure.

[0088] Now for reference Figure 6 The figure shows the cylinder air charge value and fuel injection amount during the two engine starts. Figure 6 The sequence can be transmitted via Figure 1 The system and Figures 3 to 5The method is provided. In this example, in a two-engine start-up sequence, cylinder number one of the four-cylinder engine is the first cylinder to dominate combustion since the most recent engine stop. The vertical line at t0-t7 represents the time of interest during the sequence. The double SS along the horizontal axis represents a temporal interruption, and the duration of the temporal interruption can be long or short. Figure 6 The four curves are aligned in time. The first engine starts exactly after time t0, and the second engine starts exactly after time t4.

[0089] From Figure 6 The first graph at the top is a graph of the cylinder air charge scalar (α) for the first combustion event in cylinder number one after the most recent engine stop, assuming cylinder number one is the first cylinder ignited since the most recent engine stop. The vertical axis represents the cylinder air charge scalar value α, and the value of α increases in the direction of the arrow on the vertical axis. The horizontal axis represents the cylinder stroke of cylinder number one. The intake stroke of cylinder number one is indicated by "Intake," the compression stroke by "Compression," and so on. The engine... Figure 6 Left side to Figure 6 Rotate in the direction to the right. Trajectory 602 represents the scalar α.

[0090] From Figure 6 The second curve at the top is as follows Figure 3 Section 316 describes a graph representing the cylinder air charge estimate based on intake manifold pressure and the α scalar, or determined by both. The vertical axis represents cylinder air charge, and the cylinder air charge value increases in the direction of the arrow on the vertical axis. The horizontal axis represents the cylinder stroke of cylinder number one. The engine, from... Figure 6 Left side to Figure 6 Rotate in the direction to the right. Trace 604 represents the cylinder air filling estimate based on the intake manifold pressure.

[0091] From Figure 6 The third curve at the top is as follows Figure 4 The graph described at point 320 is based on the pressure in cylinder number one or an estimate of cylinder air charge determined from it. The vertical axis represents cylinder air charge, and the cylinder air charge value increases in the direction of the arrow on the vertical axis. The horizontal axis represents the cylinder stroke of cylinder number one. The engine is in motion from... Figure 6 Left side to Figure 6 Rotate in the direction to the right. Trace 606 represents the cylinder air filling estimate based on cylinder pressure.

[0092] From Figure 6The fourth curve at the top is a graph of the fuel injected into cylinder number one. The vertical axis represents the timing of fuel injection into cylinder number one. The length of the fuel pulses 608-614 indicates the amount of fuel injected during each injection. Longer pulses indicate a larger amount of fuel injected into cylinder number one compared to shorter pulses. The horizontal axis represents the cylinder stroke of cylinder number one. The engine... Figure 6 Left side to Figure 6 Rotate in the direction to the right. Traces 608-614 represent fuel pulses delivered to cylinder number one.

[0093] At time t0, the engine is not rotating. Engine rotation begins shortly after time t0, and the α scalar is at an intermediate level. After sampling the intake manifold pressure, the cylinder air filling estimate based on the intake manifold pressure increases. The intake manifold pressure (not shown) is at a higher level indicating ambient pressure. Since cylinder number one is in its intake stroke, no cylinder air filling estimate based on cylinder pressure is provided.

[0094] At time t1, fuel injection into cylinder 1 begins during the intake stroke, and the amount of fuel injected into cylinder 1 varies with the cylinder air charge of cylinder 1, determined based on the engine intake manifold pressure, and the value of the scalar α. By injecting fuel during the intake stroke, a larger amount of fuel can be injected during the cylinder cycle. Furthermore, in some cases, fuel evaporation can be enhanced. The value of the scalar α and the cylinder air charge value estimated based on the engine intake manifold pressure remain unchanged. The estimated cylinder air charge value based on cylinder pressure is not indicated.

[0095] Between time t1 and time t2, the engine rotates through the intake stroke of cylinder number one and enters the compression stroke of cylinder number one. The cylinder air charge value estimated based on the engine intake manifold pressure and the cylinder air charge value estimated based on the pressure in cylinder number one remain unchanged.

[0096] At time t2, the pressure in cylinder 1 (not shown) is determined after the intake valve of cylinder 1 closes. The cylinder air charge, estimated based on the pressure in cylinder 1, increases to an intermediate level, but it is lower than the cylinder air charge amount in cylinder 1 estimated based on the engine intake manifold pressure. At time t2, no fuel is injected into the engine.

[0097] At time t3, a second fuel pulse is delivered to cylinder 1 during the same cylinder cycle as when fuel is injected at time t2. The amount of fuel injected at time t3 is based on the desired fuel fraction of the intake stroke and the difference between the cylinder air charge in cylinder 1 estimated based on engine intake manifold pressure and the cylinder air charge estimated based on the pressure in cylinder 1 after the intake manifold of cylinder 1 closes. The second fuel pulse allows the air-fuel ratio of cylinder 1 to match the desired air-fuel ratio of cylinder 1. The scalar α value, the cylinder air charge in cylinder 1 based on engine intake manifold pressure, and the cylinder air charge in cylinder 1 based on the pressure in cylinder 1 after the intake valve of cylinder 1 closes remain at their previous values. The engine is stopped (not shown) between time t3 and time t4.

[0098] At time t4, the engine is not rotating. Engine rotation begins shortly after time t4. The scalar α is an intermediate level value, but it is lower than the α value at time t1 because the α value at time t4 has been updated based on the cylinder air charge estimate determined at time t2 (which is based on the pressure in cylinder 1 after the intake valve of cylinder 1 has closed). Therefore, the value of the scalar α at time t4 is updated to a lower level because the cylinder air charge determined at time t1 based on the engine intake manifold pressure is greater than the cylinder air charge determined at time t2 based on the pressure in cylinder 1. Even if the intake manifold pressures at time t1 and time t2 were equal (not shown), the cylinder air charge estimate based on the intake manifold pressure at time t4 is lower than the cylinder air charge estimate based on the intake manifold pressure at time t1 because the value of the scalar α has decreased. Since cylinder 1 is in its intake stroke, no cylinder air charge estimate based on cylinder pressure is provided.

[0099] At time t5, fuel injection into cylinder 1 begins during the intake stroke, and the amount of fuel injected into cylinder 1 varies with the cylinder air charge estimated based on the engine intake manifold pressure at time t4 and the value of the scalar α. By injecting fuel during the intake stroke, a larger amount of fuel can be injected during the cylinder cycle. Furthermore, in some cases, fuel evaporation can be enhanced. From time t4 onwards, the value of the scalar α and the cylinder air charge estimated based on the engine intake manifold pressure remain unchanged. The estimated cylinder air charge value based on cylinder pressure is not indicated. The amount of fuel injected at time t5 is less than the amount injected at time t1 because the estimated cylinder air charge based on the intake manifold pressure at time t4 has decreased with the corrected value of α.

[0100] Between time t5 and time t6, the engine rotates through the intake stroke of cylinder number one and enters the compression stroke of cylinder number one. The cylinder air charge value estimated based on the engine intake manifold pressure and the cylinder air charge value estimated based on the pressure in cylinder number one remain unchanged.

[0101] At time t6, the pressure in cylinder 1 is determined after the intake valve of cylinder 1 closes. The cylinder air charge, estimated based on the pressure in cylinder 1, increases to an intermediate level and is approximately equal to the cylinder air charge in cylinder 1 estimated based on the engine intake manifold pressure. At time t2, no fuel is injected into the engine.

[0102] At time t7, a second fuel pulse is delivered to cylinder 1 during the same cylinder cycle as when fuel is injected at time t5. The amount of fuel injected at time t7 is based on the desired fuel fraction DISFF of the intake stroke, as discussed in the description of method 300. The second fuel pulse allows the air-fuel ratio of cylinder 1 to match the desired cylinder air-fuel ratio of cylinder 1. The scalar α value, the cylinder air charge in cylinder 1 based on the engine intake manifold pressure, and the cylinder air charge in cylinder 1 based on the pressure in cylinder 1 after the intake valve of cylinder 1 closes retain their previous values. The value of scalar α is not updated because the cylinder air charge in cylinder 1 based on the pressure in cylinder 1 and the cylinder air charge in cylinder 1 based on the engine intake manifold pressure are close in value.

[0103] In this way, cylinder air filling estimates can be adjusted for engine operating conditions, including the total number of combustion events since the most recent engine stop and the first engine cylinder ignited after the most recent engine stop.

[0104] It should be noted 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-transitory memory and can be executed by a control system including controllers in conjunction 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. Thus, the various actions, operations, and / or functions shown can be executed in the order shown, can be executed in parallel, or, in some cases, can be omitted. Similarly, the processing order is not necessarily required 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 actions, operations, and / or functions shown can be repeatedly executed according to the specific strategy used. Furthermore, at least a portion of the described actions, operations, and / or functions can be graphically represented as code to be programmed into a non-transitory memory of a computer-readable storage medium in a control system. When the described actions are implemented by executing instructions in a system including various engine hardware components in conjunction with one or more controllers, the control actions can also transform the operating state of one or more sensors or actuators in the physical world.

[0105] This concludes the instruction manual. Many changes and modifications will be conceived by those skilled in the art upon reading this manual without departing from its spirit and scope. For example, this manual may be advantageously used with inline 3-cylinder, inline 4-cylinder, inline 5-cylinder, V6-cylinder, V8-cylinder, V10-cylinder, and V12-cylinder engines operating with natural gas, gasoline, diesel, or alternative fuels.

[0106] According to the present invention, an engine operation method includes: in response to an open-loop estimate of cylinder air charge, injecting a first amount of fuel into the cylinder during a cylinder cycle, the open-loop estimate of cylinder air charge varying with the first cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop.

[0107] According to one embodiment, a further feature of the invention is that, in response to cylinder pressure, a second amount of fuel is injected into the cylinder during the cycle of the cylinder.

[0108] According to one embodiment, the first amount of fuel is injected during the intake stroke of the cylinder.

[0109] According to one embodiment, the second amount of fuel is injected during the compression stroke of the cylinder.

[0110] According to one embodiment, the open-loop estimation of the cylinder air charge is further based on the intake manifold pressure.

[0111] According to one embodiment, during the most recent engine stop, the engine speed was zero.

[0112] According to one embodiment, the first amount of fuel is injected via a direct fuel injector.

[0113] According to the present invention, an engine operation method includes: injecting a first amount of fuel into the cylinder during a cylinder cycle in response to a first cylinder air charge estimation, the first cylinder air charge estimation being based on a scalar quantity that varies with the number of first cylinders ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop; and adjusting the scalar quantity in response to a second cylinder air charge estimation.

[0114] According to one embodiment, the second cylinder air filling estimate is further based on the pressure in the cylinder during the cycle of the cylinder.

[0115] According to one embodiment, an adjusted scalar is stored in the controller memory based on the first cylinder ignited since the most recent engine stop and the total number of actual combustion events since the most recent engine stop.

[0116] According to one embodiment, a further feature of the invention is that, in response to the pressure in the cylinder, a second amount of fuel is injected into the cylinder during the cycle of the cylinder.

[0117] According to one embodiment, the first cylinder air charge estimate is further based on the intake manifold pressure.

[0118] According to one embodiment, a further feature of the invention is that the ignition timing is adjusted in response to the pressure in the cylinder.

[0119] According to one embodiment, the cylinder is a second cylinder ignited since the most recent engine stop, and further includes: adjusting the amount of a second fuel injected into the cylinder during the cycle of the cylinder based on exhaust pressure.

[0120] According to the present invention, a vehicle system is provided, comprising: an engine; an intake manifold pressure sensor coupled to the engine; a cylinder pressure sensor coupled to the engine and partially located within a cylinder of the engine; and a controller including executable instructions stored in a non-transitory memory, the executable instructions being configured to: provide a first fuel injection to the cylinder of the engine during the cylinder cycle in response to an output of the intake manifold pressure sensor during a cycle of the cylinder; and provide a second fuel injection to the cylinder during the cylinder cycle in response to an output of the cylinder pressure sensor.

[0121] According to one embodiment, a further feature of the invention is an additional command for estimating cylinder air charge via the intake manifold pressure sensor.

[0122] According to one embodiment, a further feature of the invention is an additional command for estimating cylinder air filling via the cylinder pressure sensor.

[0123] According to one embodiment, injecting fuel into the cylinder of the engine during the cycle of the cylinder in response to the output of the intake manifold pressure sensor includes injecting fuel via a direct fuel injector during the intake stroke of the cylinder.

[0124] According to one embodiment, injecting fuel into the cylinder of the engine during the cycle of the cylinder in response to the output of the cylinder pressure sensor includes injecting fuel via a direct fuel injector during the compression stroke of the cylinder.

[0125] According to one embodiment, a further feature of the invention is an additional command for adjusting the ignition timing in response to the output of the cylinder pressure sensor during the cylinder cycle.

Claims

1. An engine operating method comprising: injecting a first amount of fuel into a cylinder during a cycle of the cylinder in response to an open loop estimate of cylinder air charge that varies with a first cylinder since a most recent engine stop and a total number of actual combustion events since the most recent engine stop.

2. The method of claim 1, further comprising: injecting a second amount of fuel into the cylinder during the cycle of the cylinder in response to cylinder pressure.

3. The method of claim 2, wherein the first amount of fuel is injected during an intake stroke of the cylinder.

4. The method of claim 3, wherein the second amount of fuel is injected during a compression stroke of the cylinder.

5. The method of claim 1, wherein the open loop estimate of cylinder air charge is further based on intake manifold pressure.

6. The method of claim 1, wherein engine speed is zero during the most recent engine stop.

7. The method of claim 1, wherein the first amount of fuel is injected via a direct fuel injector.

8. A vehicle system comprising: an engine; an intake manifold pressure sensor coupled to the engine; a cylinder pressure sensor coupled to the engine and partially located within a cylinder of the engine; and a controller comprising executable instructions stored in non-transitory memory for: providing a first fuel injection to the cylinder of the engine during a cycle of the cylinder in response to an output of the intake manifold pressure sensor during the cycle of the cylinder; and providing a second fuel injection to the cylinder during the cycle of the cylinder in response to an output of the cylinder pressure sensor. further instructions for estimating cylinder air charge via the intake manifold pressure sensor.

9. The system of claim 8, further comprising: further instructions for estimating cylinder air charge via the cylinder pressure sensor.

10. The system of claim 8, further comprising: injecting fuel via a direct fuel injector during an intake stroke of the cylinder.

11. The system of claim 8, wherein injecting fuel to the cylinders of the engine during the cycle of the cylinders in response to the output of the intake manifold pressure sensor comprises: injecting fuel via a direct fuel injector during a compression stroke of the cylinder.

12. The system of claim 8, wherein injecting fuel to the cylinder of the engine during the cycle of the cylinder in response to the output of the cylinder pressure sensor comprises: further instructions for adjusting a timing of ignition in response to an output of the cylinder pressure sensor during the cycle of the cylinder.

13. The system of claim 8, further comprising: ​

Images