Diesel engine particulate filter regeneration system and method

Abstract

The present invention relates to a diesel engine particulate filter regeneration system and method. A method and system are described for estimating the amount of residual or retained fuel remaining in a cylinder from a first cycle of the cylinder to a second cycle of the cylinder. In one example, the amount of residual fuel is estimated in response to the temperature of an oxidation catalyst. The retained fuel amount can then serve as a basis for adjusting the amount of fuel injected during the second cycle of the cylinder.

Description

Technical Field

[0001] The present invention relates to a diesel engine particulate filter regeneration system and method. Background Art

[0002] Two-stroke and four-stroke diesel engines with variable valve timing can operate with relatively large amounts of residual exhaust gas remaining in the engine cylinders from previous combustion events. These same engines can include particulate filters in their exhaust systems to capture carbonaceous soot, which can be produced as a byproduct of combustion. Over time, the particulate filter can become saturated with soot, causing it to provide more significant exhaust restriction. The particulate filter can be regenerated by increasing the exhaust temperature and supplying an oxygen-rich exhaust mixture to the particulate filter to combust the soot remaining in the particulate filter, thereby regenerating the microfiltration filter. Exhaust temperature can be increased by injecting a post-injection amount of fuel into the cylinder that can be discharged into the engine exhaust system, where it can combust within an oxidation catalyst and increase the exhaust temperature. However, some of the post-injected fuel may remain in the engine cylinder, where it can be combusted during the cylinder's next cycle. This retained fuel can increase engine torque and promote earlier combustion timing than desired. Therefore, it is desirable to estimate the amount of fuel remaining in the engine cylinder from one cylinder cycle to the next. Summary of the Invention

[0003] The inventors herein have recognized the aforementioned challenges and have developed an engine control method comprising: estimating, by a controller, an amount of fuel retained in a cylinder from a first cycle of the cylinder to a second cycle of the cylinder in response to an increase in temperature of an oxidation catalyst; and adjusting, by the controller, an amount of fuel injected to the cylinder during the second cycle of the cylinder in response to the estimated amount of fuel.

[0004] By estimating the amount of fuel remaining in the cylinder from one cylinder cycle to the next in response to catalyst temperature, fuel injection can be adjusted during the next cylinder cycle in a manner that provides precise engine torque output and reduced emissions. Catalyst temperature can provide an accurate estimate of fuel remaining in the cylinder without requiring knowledge of cylinder pressure. In particular, post-injected fuel, which does not participate in combustion and is injected from the engine cylinder to facilitate particulate filter regeneration, increases catalyst temperature. The catalyst temperature increase is a function of the amount of post-injected fuel that does not participate in combustion and is injected from the cylinder. The amount of post-injected fuel that remains in the cylinder from one cylinder cycle to the next is the amount of post-injected fuel minus the amount of fuel that does not participate in combustion and is injected from the cylinder.

[0005] The present invention can provide several advantages. Specifically, the method can estimate the amount of post-injected fuel remaining in a cylinder from one cylinder cycle to the next without knowing the in-cylinder pressure. Furthermore, the method provides multiple ways to adjust fuel injection timing to improve engine torque control and engine emissions. Furthermore, the method can help improve control of exothermic reactions within an oxidation catalyst during particulate filter regeneration.

[0006] The above and other advantages and features of the present invention will be apparent from the following detailed description when taken alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above summary is provided to introduce some concepts in a simplified form that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined solely by the appended claims. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of an engine is shown;

[0009] Figure 2 An example particulate filter regeneration sequence is shown;

[0010] Figure 3 shows post fuel injection timing relative to piston position; and

[0011] Figure 4 is an example method of regenerating a particulate filter. DETAILED DESCRIPTION

[0012] The present invention relates to controlling the fuel supplied to a diesel engine. Figure 1 An example of a supercharged two-stroke diesel engine is shown, but the method described herein is equally applicable to a four-stroke diesel engine. Figure 1 The diesel engine in the embodiment is an opposed piston engine, but the method described herein can also be applied to a two-stroke engine comprising a single piston per engine cylinder. Figure 2 A block diagram showing the way fuel injection is regulated. The fuel injection sequence for a diesel engine is shown in Figure 3 A method for supplying fuel to a diesel engine is shown in Figure 4 is shown in .

[0013] refer to Figure 1 , contains multiple cylinders (one of which is in Figure 1) is controlled by an electronic engine controller 12. The controller 12 receives information from Figure 1 The various sensor signals are used based on the received signals and the instructions stored in the memory of the controller. Figure 1 Various actuators to adjust engine operation.

[0014] Engine 10 includes cylinder 30 and cylinder walls 32, with intake and exhaust pistons 36a and 36b positioned therein and connected to crankshafts 40a and 40b, respectively. Crankshafts 40a and 40b may be coupled together via a belt, chain, or gears. Crankshafts 40a and 40b may be rotated by a motor 77 (e.g., a starter motor) to start engine 10. Cylinder 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via intake ports 44a and 44b and exhaust ports 48a and 48b.

[0015] First and second fuel injectors 69 and 68 are shown positioned within cylinder wall 32 and can inject fuel directly into cylinder 30, a process known to those skilled in the art as direct injection. Fuel is delivered to first and second fuel injectors 69 and 68 via a fuel system comprising fuel tank 95, fuel pump 91, fuel pump control valve 93, and a fuel rail (not shown). The fuel pressure delivered by the fuel system can be adjusted by varying a position valve that regulates flow to the fuel pump (not shown). Additionally, a metering valve can be positioned within or near the fuel rail for closed-loop fuel control. The pump metering valve can also regulate fuel flow to the fuel pump, thereby reducing the amount of fuel pumped to the higher-pressure fuel pump.

[0016] Intake manifold 44 is shown communicating with optional electronic throttle 62, which adjusts the position of throttle plate 64 to control air flow from intake boost chamber 46. Supercharger compressor 162 is mechanically driven and draws air from downstream of turbocharger compressor 135. Turbocharger compressor 135 draws air from air intake 42. Supercharger compressor 162 supplies air to boost chamber 46. Exhaust gas rotates turbocharger variable geometry turbine 137, which is coupled to turbocharger compressor 135 via shaft 136. Supercharger compressor 162 is mechanically driven by crankshaft 40b via shaft 161 and gearbox 163, which may be coupled to crankshaft 40b via mechanism 164 (e.g., gears, a chain, or a belt). Supercharger gearbox 163 includes multiple gear ratios for varying the speed of supercharger compressor 162 relative to the speed of crankshaft 40b. Supercharger compressor speed can be adjusted by selecting and engaging gear 163a of gearbox 163. In one example, a given engine crankshaft speed can rotate supercharger compressor 162 at first and second speeds by shifting in gearbox 163 between first and second gear ratios.

[0017] Supercharger compressor bypass valve 158 can be selectively opened to reduce the air pressure in boost chamber 46 and return air and exhaust gas recirculation (EGR) upstream of supercharger compressor 162. In some examples, charge air cooler 156 can be provided downstream of supercharger compressor 162 to cool the air charge entering cylinder 30. Air charge cooler bypass valve 157 can be selectively opened to bypass charge air cooler 156. The position of vane actuator 137a can be adjusted by controller 12 to increase or decrease the rotational speed of turbine 137. In an alternative example, wastegate 137c can be used in place of or in addition to vane actuator 137a. Vane actuator 137a adjusts the position of variable geometry turbine vanes 137b. When the vanes are in the open position, exhaust gas can pass through turbine 137, thereby providing a small amount of energy to rotate turbine 137. When the vanes are in the closed position, exhaust gas is able to pass through the turbine 137 and apply increased force to the turbine 137. Alternatively, a wastegate 137c or bypass valve allows exhaust gas to flow around the turbine 137 to reduce the energy provided to the turbine.

[0018] In an alternative example, supercharger compressor 162 may be positioned upstream of turbocharger compressor 135. Further, an air charge cooler (not shown) may be positioned downstream of where EGR passage 82 joins intake 43 between supercharger compressor 162 and turbocharger compressor 135. The air charge cooler would eliminate the need for an EGR cooler.

[0019] Exhaust gas may be recirculated to cylinder 30 via EGR system 81. The EGR system includes an optional EGR cooler 85, an EGR valve 80, an EGR passage 82, an EGR cooler bypass 84, an EGR sensor 89, and a cooled EGR passage 83. Exhaust gas may flow from exhaust manifold 48 to engine air intake 43 between supercharger compressor 162 and turbocharger compressor 135. When the pressure in exhaust manifold 48 is greater than the pressure between turbocharger compressor 135 and supercharger compressor 162, EGR may flow to the engine air intake. EGR may flow through EGR cooler 85 to reduce engine exhaust temperature. When engine exhaust temperature is low, EGR may bypass the EGR cooler. EGR sensor 89 is used to determine EGR flow through an orifice, which is converted into an amount of EGR in each engine cylinder for each engine cycle.

[0020] After intake piston 36a covers intake ports 44a and 44b and exhaust piston 36b covers exhaust ports 48a and 48b, fuel can be injected into cylinder 30 as pistons 36a and 36b approach each other. The fuel can then be combusted with the air in cylinder 30 as piston 36 approaches top dead center in the compression stroke. The fuel and air are ignited by compression ignition. In some examples, universal exhaust gas oxygen (UEGO) sensor 126 can be coupled to exhaust manifold 48 upstream of emissions device 70. In other examples, the UEGO sensor can be positioned downstream of one or more exhaust aftertreatment devices. Also, in some examples, the UEGO sensor can be replaced by a NOx sensor having both NOx and oxygen sensing elements.

[0021] Engine 10 does not include glow plugs or spark plugs because it is a compression ignition engine and because it does not include a cylinder head. Also, engine 10 does not include poppet valves for regulating the flow of air and exhaust gas into and out of cylinder 30.

[0022] Exhaust system 131 transports exhaust gas from engine 10 and processes the exhaust gas. Exhaust valve 140 is shown positioned in exhaust passage 49 downstream of turbine 137a and upstream of exhaust device 70. Alternatively, exhaust valve 140 may be positioned downstream of exhaust device 70. Exhaust valve 140 can be opened and closed to control the pressure in exhaust manifold 48. Closing exhaust valve 140 restricts flow through exhaust valve 140 and can increase pressure in exhaust manifold 48. Opening exhaust valve 140 can increase flow through exhaust valve 140 and reduce pressure in exhaust manifold 48.

[0023] In one example, emissions control device 70 can include an oxidation catalyst 72 and a particulate filter 73. In another example, multiple emission control devices can be used, each with multiple catalyst bricks. In one example, emissions control device 70 can include an oxidation catalyst. In other examples, the emissions device can include a lean NOx trap or a selective catalytic reducer (SCR), and / or a diesel particulate filter (DPF). Temperature sensor 71 detects the temperature of oxidation catalyst 72.

[0024] The controller 12 Figure 1 1 is shown as a conventional microcomputer including: a microprocessor unit (CPU) 102, input / output ports (I / O) 104, read-only memory (e.g., non-volatile memory) (ROM) 106, random access memory (RAM) 108, keep-alive memory (KAM) 110, and a conventional data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10, including, in addition to those previously discussed, engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling jacket 114, position sensor 134 coupled to accelerator pedal 130 for detecting accelerator position adjusted by a person's foot 132, a measurement of engine manifold pressure (MAP) from pressure sensor 121 coupled to intake manifold 44, boost pressure from pressure sensor 122, exhaust oxygen concentration from oxygen sensor 126, an engine position sensor from Hall effect sensor 118 for detecting the position of crankshaft 40b, a measurement of air mass entering the engine from sensor 120 (e.g., a hot wire air flow meter), and a measurement of throttle position from sensor 58. Barometric pressure may also be detected (sensor not shown) for processing by controller 12. In a preferred aspect of the present invention, engine position sensor 118 produces a predetermined number of equally spaced pulses every revolution of the crankshaft, from which engine speed (RPM) can be determined.

[0025] During operation, each cylinder in engine 10 typically undergoes a two-stroke cycle: the cycle includes a first stroke, in which intake piston 36a moves toward exhaust piston 36b and exhaust piston 36b moves toward intake piston 36a. During a second stroke, intake piston 36a moves away from exhaust piston 36b and exhaust piston 36b moves away from intake piston 36a. Intake piston 36a controls flow through intake ports 44a and 44b. Exhaust piston 36b controls flow through exhaust ports 48a and 48b. In this example, exhaust piston 36b leads intake piston 36a by reaching its top dead center position (e.g., the maximum distance of exhaust piston 36b from crankshaft 40b) a few crankshaft degrees (e.g., the difference can range from 0-20 crankshaft degrees, depending on the configuration) before intake piston 36a reaches its top dead center position (e.g., the maximum distance of exhaust piston 36b from crankshaft 40b). Therefore, the exhaust piston motion deviates from the intake piston motion by a few crankshaft degrees.

[0026] During the first stroke, typically, intake piston 36a and exhaust piston 36b move toward each other to compress the air entering cylinder 30. This stroke begins at bottom dead center (BDC) of intake piston 36a (intake piston 36a is closest to crankshaft 40a) and ends at top dead center of intake piston 36a (intake piston 36a is at its greatest distance from crankshaft 40a). As described above, exhaust piston 36b leads intake piston 36a by a slight angle so that when the intake piston is at BDC, the exhaust piston has already moved toward its TDC position. Furthermore, exhaust piston 36b reaches its TDC position just before intake piston 36a reaches its TDC position. When intake piston 36a reaches its TDC position, exhaust piston 36b is just behind its TDC position. When intake piston 36a and exhaust piston 36b are near their respective TDC positions, the cylinder volume is at its minimum. As intake piston 36a and exhaust piston 36b advance toward their respective TDC positions, air and fuel are compressed within cylinder 30. As intake piston 36a and exhaust piston 36b approach their respective BDC positions, intake ports 44a and 44b open and compress the air flowing into cylinder 30. Exhaust ports 48a and 48b also open when intake piston 36a and exhaust piston 36b approach BDC. Supercharger compressor 162 and turbocharger compressor 135 provide compressed air to intake manifold 44, which can flow into cylinder 30 when intake ports 44a and 44b are open. As intake piston 36a and exhaust piston 36b advance toward their respective TDC positions, exhaust ports 48a and 48b close. As engine rotation continues, intake ports 44a and 44b close after a predetermined number of actual total crankshaft angles to prevent additional air from entering cylinder 36. Thus, the exhaust port opens before the intake port and remains open for approximately the same amount of time as the intake port. Fuel is injected into cylinder 30 after exhaust ports 44a and 44b close, and then the fuel and air mixture is ignited when intake piston 36a and exhaust piston 36b approach their respective TDC positions. The fuel and air mixture is ignited by compression ignition and does not rely on energy from a spark plug or glow plug. Fuel may be injected into cylinder 30 via multiple injections, including a pilot injection, a main injection, and a post injection.

[0027] During the second stroke, typically, intake piston 36a and exhaust piston 36b move away from each other after combustion occurs in cylinder 30. The second stroke begins at intake piston 36a's TDC and ends at intake piston 36a's BDC. Intake piston 36a and exhaust piston 36b are near their respective BDC positions, near which the volume of cylinder 30 is at its maximum. The expanding gases in cylinder 30 push intake piston 36a and exhaust piston 36b apart, toward their respective BDC positions. As exhaust piston 36b moves toward its BDC, it passes exhaust ports 48a and 48b. Exhaust ports 48a and 48b are exposed when exhaust piston crown 36d passes exhaust ports 48a and 48b while exhaust piston 36b moves toward crankshaft 40b. Exhaust gases exit cylinder 30 after exhaust piston 36b passes exhaust ports 48a and 48b while moving toward bottom dead center. Intake piston 36a and exhaust piston 36b further move toward their respective bottom dead center positions, and after a predetermined number of actual total crankshaft angles, intake piston 36a exposes intake ports 44a and 44b. When top 36c of intake piston passes intake ports 44a and 44b while intake piston 36a moves toward crankshaft 40a, intake ports 44a and 44b are exposed. When intake ports 44a and 44b are exposed, fresh air enters cylinder 30 through intake ports 44a and 44b. Intake piston 36a and exhaust piston 36b continue to move toward their respective bottom dead center positions. After the intake piston reaches the BDC position, the cylinder cycle repeats.

[0028] In this manner, an engine cycle consists of two strokes and an engine cycle is one engine revolution. The other engine cylinders operate in a similar manner, but these other cylinders may combust air and fuel out of phase with the cylinder shown. For example, the top dead center compression stroke of one engine cylinder may be at zero crankshaft angles while the top dead center of another cylinder may be at 180 crankshaft angles.

[0029] therefore, Figure 1 The system in the invention provides an engine system comprising: an opposed-piston diesel engine including a cylinder with a first fuel injector and a second fuel injector; a supercharger coupled to the opposed-piston diesel engine, the supercharger having a plurality of gear ratios; a turbocharger coupled to the opposed-piston diesel engine; an oxidation catalyst included in an exhaust system of the opposed-piston diesel engine; and a controller including executable instructions stored in non-transitory memory, the instructions providing an estimate of fuel remaining in a cylinder of the opposed-piston diesel engine from a first cycle of the cylinder to a second cycle of the cylinder in response to a temperature of the oxidation catalyst. The engine system also includes additional instructions for adjusting a pilot fuel injection amount in response to the estimate of fuel remaining in the cylinder.

[0030] In some examples, the engine system further includes additional instructions for adjusting the amount of main fuel injection in response to an estimate of fuel remaining in the cylinder. The engine system further includes additional instructions for adjusting the timing of the main fuel injection in response to the estimate of fuel remaining in the cylinder. The engine system further includes additional instructions for adjusting the amount of post-injection fuel injected during the second cycle of the cylinder in response to the estimate of fuel remaining in the cylinder. The engine system further includes additional instructions for estimating the fuel remaining in the cylinder in response to a pressure difference between an engine intake manifold pressure and an engine exhaust manifold pressure. The engine system further includes additional instructions for estimating the fuel remaining in the cylinder in response to an amount of external exhaust gas recirculation.

[0031] The engine 10 can receive fuel through various injection types. Pilot fuel injection is a short fuel injection that can be less than 4 mg. Pilot fuel injections begin and end before the top dead center compression stroke in the cylinder cycle in which they are injected. Pilot fuel injection can reduce engine combustion noise, control peak cylinder pressure, and regulate heat release in the cylinder. Main fuel injection is the injection of the largest amount of fuel injected during the cylinder cycle. Main fuel injection can vary from 3 mg per cylinder cycle to 10 mg per cylinder cycle. Pilot fuel injection precedes the main fuel injection. Early post fuel injection can occur 10 crankshaft degrees after the top dead center compression stroke and after the main fuel injection. Early post fuel injection can vary from 1 mg to 10 mg. Late post injection is a fuel injection performed during the cylinder cycle after combustion of the main fuel injection pulse is complete and before the exhaust port of the cylinder receiving the fuel is closed. Early and late post injections can be used to regenerate emissions control devices in the engine's exhaust system (e.g., PF).

[0032] Now refer to Figure 2 , which shows Figure 4 An example block diagram of a portion of a method. Figure 2 The block diagram provides the Figure 4 A diagram of the method of information exchange.

[0033] The driver demand torque (e.g., torque requested by a human or autonomous driver via an accelerator pedal or a variable in a register) and engine speed are referenced to table 202. Table 202 provides pilot fuel injection quantities for each driver demand and engine speed pair. For driver demand values ​​and engine speed values ​​that do not have corresponding table inputs for pilot fuel injection quantities, the pilot fuel injection quantity is interpolated. Table 202 outputs the pilot fuel injection quantity to connection point 214.

[0034] The driver demand torque and engine speed are also used to reference table 204. Table 204 provides the start of injection timing of the pilot fuel injection for each driver demand and engine speed pair (e.g., the crankshaft angle at which the pilot fuel injection begins for a cylinder cycle). For driver demand values ​​and engine speed values ​​that do not have a corresponding table input for the start of injection timing of the pilot fuel injection, the start of injection timing of the pilot fuel injection is interpolated. Table 204 outputs the start of injection timing of the pilot fuel injection to block 218.

[0035] The driver demand torque and engine speed are also referenced to table 206. Table 206 provides main fuel injection amounts for driver demand and engine speed pairs. For driver demand values ​​and engine speed values ​​that do not have corresponding table inputs for main fuel injection amounts, the main fuel injection amount is interpolated. Table 206 outputs the main fuel injection amount to connection point 216.

[0036] The driver demand torque and engine speed are also referenced to table 208. Table 208 provides the start of injection timing for the main fuel injection for each driver demand and engine speed pair (e.g., the crankshaft angle at which the main fuel injection begins for a cylinder cycle). For driver demand values ​​and engine speed values ​​that do not have a corresponding table input for the start of injection timing for the main fuel injection, the start of injection timing for the main fuel injection is interpolated. Table 208 outputs the start of injection timing for the main fuel injection to block 218.

[0037] The desired increase in oxidation catalyst temperature, engine speed, and diesel particulate filter (DPF) regeneration requirement are referenced to table 210. Table 210 provides post-fuel injection amounts for each desired increase in oxidation catalyst temperature and engine speed. For values ​​of desired increase in oxidation catalyst temperature and engine speed for which there are no corresponding table inputs for post-fuel injection amounts, the post-fuel injection amount is interpolated. Table 210 outputs the post-fuel injection amount to block 218.

[0038] The desired increase in oxidation catalyst temperature, engine speed, and DPF regeneration requirement are also referenced to table 212. Table 212 provides the end-of-injection timing of the post fuel injection for each desired increase in oxidation catalyst temperature and engine speed (e.g., the crankshaft angle at which the post fuel injection ends). For values ​​of desired increase in oxidation catalyst temperature and engine speed that do not have a corresponding table input for the start-of-injection timing of the pilot fuel injection, the end-of-injection timing of the pilot fuel injection is interpolated. Table 212 outputs the end-of-injection timing of the pilot fuel injection to block 218.

[0039] The values ​​in Tables 202-212 were empirically determined by operating the engine on a dynamometer at various engine speeds and loads. The fuel injection amount and timing were swept to determine the fuel injection amount and fuel injection timing that provide the desired engine torque and emissions values. The post-injection amount was determined by adjusting the post-injection amount and timing to provide the desired oxidation catalyst temperature at various engine speeds.

[0040] The amount of residual fuel remaining or retained in the cylinder from the first cylinder cycle to the second cylinder cycle (the second cylinder cycle immediately following the first cylinder cycle) is estimated at block 224. The oxidation catalyst temperature, the amount of exhaust gas, the pressure difference between the intake manifold pressure and the exhaust manifold pressure, the post-injection fuel amount, and the post-injection end timing of the post-injection are inputs to block 224. The residual fuel amount is calculated based on the Figure 4 Block 224 outputs the residual fuel for each engine cylinder to blocks 220 and 222 .

[0041] As will Figure 4 As described in greater detail in the description of FIGURE 2, an estimated residual fuel at least partially burned during compression is determined at block 220. The estimated residual fuel at least partially burned during compression is directed to junction 214, where it is subtracted from the pilot fuel injection amount. By subtracting the estimated residual fuel at least partially burned during compression from the pilot fuel injection amount, a desired pilot fuel injection amount can be obtained to provide a desired level of engine noise and vibration. The adjusted pilot fuel injection amount is directed from block 214 to block 218.

[0042] As will Figure 4 As described in greater detail in the description of FIGURE 2, an estimated residual fuel burned after compression ignition is determined at block 222. The estimated residual fuel burned after compression ignition is directed to junction 216, where it is subtracted from the main fuel injection amount. By subtracting the estimated residual fuel burned after compression ignition from the main fuel injection amount, a desired main fuel injection amount can be obtained to provide a desired level of engine torque. The adjusted main fuel injection amount is directed from block 216 to block 218.

[0043] At block 218 , fuel is injected into one or more cylinders via the fuel injector based on the pilot fuel injection amount, the injection start timing of the pilot fuel injection, the main fuel injection amount, the injection start timing of the main fuel injection amount, the post fuel injection amount, and the injection start timing of the post fuel injection.

[0044] In this manner, sensor inputs and calculated values ​​adjust the fuel injected into the engine cylinders. The amount and timing of the injected fuel can be adjusted in response to the amount of residual fuel remaining in the engine cylinders. Individual estimates of the amount of residual fuel can be provided to each engine cylinder, and the pilot, main, and post injections supplied to each cylinder can be adjusted in response to the amount of fuel remaining in the cylinder receiving the fuel.

[0045] Now refer to Figure 3 , which shows a DPF regeneration sequence according to method 400 . Figure 3 The DPF regeneration sequence can be used for Figure 1 The engine and system shown in FIG. The vertical lines at times t0-t4 represent the times of interest in the sequence. These curves are aligned in time and occur simultaneously. In this example particulate filter regeneration sequence, the pilot fuel injection amount and the main fuel injection amount are adjusted in response to the residual fuel within the engine cylinder. Residual fuel is fuel that remains in the cylinder after being injected during the current cylinder cycle for post-injection in the next cylinder cycle. For example, post-fuel may be injected during the stroke when the exhaust valve or exhaust port is open as the piston moves toward BDC, and a portion of the port-injected fuel may remain in the cylinder when the piston completes the stroke and begins to compress the charge in the cylinder. This portion of the port-injected fuel that remains in the cylinder is the retained or residual fuel amount.

[0046] since Figure 3 The first graph at the top of the graph is a graph of a diesel particulate filter (DPF) regeneration request versus time. Trace 301 represents the DPF regeneration request status. The vertical axis represents the DPF regeneration request status, and when trace 201 is at a high level near the vertical axis arrow, the DPF regeneration request is asserted. When trace 201 is at a low level near the horizontal axis, the DPF regeneration request is not asserted. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0047] since Figure 3 The second graph from the top is a graph of the post-fuel injection amount of fuel injected into the cylinder versus time. Trace 302 represents the pilot fuel injection amount. The vertical axis represents the pilot fuel injection amount, and the pilot fuel injection amount increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0048] since Figure 3 The third plot from the top is a graph of main fuel injection amount versus time. Trace 304 represents the main fuel injection amount. The vertical axis represents the main fuel injection amount, and the main fuel injection amount increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0049] since Figure 3 The fourth plot from the top is a graph of post-fuel injection amount versus time. Trace 305 represents the post-fuel injection amount. The vertical axis represents the post-fuel injection amount, and the post-fuel injection amount increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0050] since Figure 3 The fifth curve from the top is a graph of the residual fuel amount in the engine cylinder versus time. Trace 307 represents the residual fuel amount in the engine cylinder. The vertical axis represents the residual fuel amount in the engine cylinder, and the residual fuel amount in the engine cylinder increases along the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0051] since Figure 3 The sixth plot from the top of FIG is a graph of total EGR amount (e.g., internal EGR amount and external EGR amount) versus time. The vertical axis represents the amount of EGR supplied to the cylinders. Trace 308 represents the amount of EGR supplied to the engine cylinders. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0052] since Figure 3 The seventh curve from the top of the graph is a plot of the amount of soot stored in the DPF versus time. The vertical axis represents the amount of soot. Trace 310 represents the amount of soot stored in the DPF in the engine exhaust system. The horizontal axis represents time, with time increasing from the left side of the graph to the right side.

[0053] For each of the seven curves, the value where the vertical axis intersects the horizontal axis is zero. The scaling of each of the vertical axes is not necessarily equal.

[0054] At time t0, the engine receives intermediate amounts of pilot and main injection fuel. The engine combusts air and fuel at intermediate speed and load (not shown). The amount of soot stored in the DPF is high, but DPF regeneration is not requested in response to current vehicle operating conditions. The post-fuel injection amount is zero, and residual fuel is near zero. Based on engine speed and load (not shown), the total EGR amount is intermediate.

[0055] At time t1, in response to the accumulated soot level and vehicle operating conditions, a DPF regeneration request is asserted. In response to the asserted particulate filter regeneration request, the post fuel injection amount begins to increase. The post fuel injection amount is increased to increase the DPF temperature. The residual fuel amount in the engine cylinders begins to increase, and pilot and main fuel injections are reduced to compensate for the residual fuel amount that persists from one cylinder cycle to the next. The total EGR amount remains at its previous level, and the soot level remains at its previous level.

[0056] Between time t1 and time t2, the residual fuel amount continues to increase and in response to the increasing residual fuel amount, the pilot and main fuel injection amounts are reduced. The total EGR amount remains constant and the post-injection fuel amount levels off at a constant value. The DPF regeneration request remains asserted and the soot amount remains at a high level.

[0057] At time t2, the total EGR amount is increased to reduce engine NOx to compensate for the reduced NOx conversion efficiency of the exhaust system when the exhaust temperature is increased to regenerate the DPF. The residual fuel amount increases in response to the increased EGR amount because fuel injected from the cylinder is returned to the cylinder using EGR. The pilot and main fuel injections are further reduced in response to the increase in residual fuel amount. As the DPF temperature increases (not shown), the DPF regeneration request remains asserted and the soot level remains unchanged. The DPF reaches a temperature at which the soot stored in the DPF begins to burn shortly before time t3 and the soot level begins to decrease. The burning soot further increases the temperature of the DPF (not shown).

[0058] At time t3, the DPF reaches a threshold temperature and the post-injection fuel amount is reduced to maintain the DPF temperature. As the post-injection fuel amount decreases, the residual fuel amount decreases. In response to the decrease in the residual amount of fuel remaining in the cylinder, the main and pilot fuel injection amounts increase. Specifically, as the residual amount of fuel remaining in the cylinder decreases from the first cycle to the second cycle of the cylinder, the amount of residual fuel combusted in the second cycle decreases. Therefore, in order to maintain the engine noise, vibration, and torque at the desired levels, the main and pilot fuel injection amounts are reduced. The DPF regeneration request remains asserted and the total EGR amount remains at its previous level. The amount of soot continues to decrease.

[0059] Between times t3 and t4, the post-injection fuel quantity continues to decrease and then levels off to a constant value to maintain the DPF temperature below the threshold temperature. Main and pilot fuel injections increase and then level off to respective constant levels. Soot quantity continues to decrease and the EGR quantity remains constant. The DPF regeneration request remains asserted.

[0060] At time t4, the amount of soot stored in the DPF falls below a threshold, and the DPF regeneration request is withdrawn. The post fuel injection amount is reduced to zero, and the pilot and main fuel injections are increased in response to the reduction in residual fuel. As the engine exhaust system decreases, the total EGR amount decreases shortly thereafter.

[0061] In this way, the pilot and main fuel injection amounts can be increased and decreased in response to increases and decreases in the residual fuel amount, which is a result of post-injection fueling, EGR, and other conditions.

[0062] Now refer to Figure 4, which shows a method for operating an engine and regenerating a particulate filter placed in an exhaust system downstream of the engine. Figure 4 The method can be stored as executable instructions in a file such as Figure 1 In the non-transitory memory in the system shown. Figure 4 The method can be incorporated into Figure 1 in the system and can be used with Figure 1 Further, Figure 4 At least portions of the method may be incorporated as executable instructions stored in a non-transitory memory, while other portions of the method may be performed by a controller that changes the operating state of devices and actuators in the physical world. According to the method described below, the controller may utilize engine actuators of an engine system to adjust engine operation.

[0063] At 402, method 400 determines vehicle operating conditions. Vehicle operating conditions may include, but are not limited to, the amount of soot stored in the particulate filter, the amount of internal EGR residual, the amount of residual fuel, the particulate filter temperature, the engine speed, the engine load, and the driver's demand torque. The vehicle operating conditions may be determined by Figure 1 , or inferred from sensor data received by controller 12 shown in . For example, the internal EGR residual can be estimated in response to engine speed, engine load, intake manifold pressure, and exhaust valve position (e.g., 140). The engine speed, engine load, intake manifold pressure, and exhaust valve position can be referenced to one or more tables or functions that include values ​​for empirically determined internal EGR residual. The table or function outputs a cylinder residual estimate. The driver demand torque can be determined from the accelerator pedal position and vehicle speed with reference to a table or function with values ​​for empirically determined driver demand torque. The function or table outputs the driver demand torque. Method 400 proceeds to 404.

[0064] At 404, based on the vehicle operating conditions determined at 402, method 400 determines fuel injection amounts and timings for the pilot and main fuel injections. In one example, the pilot fuel injection amount is determined by referencing a table of empirically determined pilot fuel injection amounts. The empirically determined pilot fuel injection amount may be a pilot fuel injection amount that provides a desired level of engine noise and vibration at a specific engine speed and driver demand torque. The pilot fuel injection amount is stored in a table or function in non-transitory memory and may be referenced or indexed by engine speed and driver demand torque. Similarly, a start-of-injection timing value for the pilot fuel injection may be determined by referencing a table of empirically determined start-of-injection timing values ​​for the pilot fuel. The empirically determined start-of-injection timing value for the pilot fuel injection may be a start-of-injection timing value for the pilot fuel injection that provides a desired level of engine noise and vibration at a specific engine speed and driver demand torque. The start-of-injection timing for the pilot fuel injection may be stored in a table or function in non-transitory memory and may be referenced or indexed by engine speed and driver demand torque.

[0065] The main fuel injection amount is also determined by referencing a table of empirically determined main fuel injection amounts. The empirically determined main fuel injection amount can be a main fuel injection amount that provides a desired level of engine torque at a specific engine speed and driver demand torque. The main fuel injection amount is stored in a table or function in non-transitory memory and can be referenced or indexed by the engine speed and driver demand torque. Similarly, the injection start timing value of the main fuel injection can be determined by referencing a table of empirically determined main fuel injection start timing values. The empirically determined main fuel injection timing value can be a injection start timing value for the main fuel injection that provides a desired level of engine torque at a specific engine speed and driver demand torque. The injection start timing of the main fuel injection can be stored in a table or function in non-transitory memory and can be referenced or indexed by the engine speed and driver demand torque. Method 400 proceeds to 406.

[0066] At 406, method 400 determines whether DPF regeneration is required. Method 400 may determine that particulate filter regeneration is required in response to the amount of soot stored in the particulate filter exceeding a threshold amount and the engine load being greater than a threshold load. If method 400 determines that DPF regeneration is required, the answer is yes and method 400 proceeds to 408. Otherwise, the answer is no and method 400 proceeds to 440.

[0067] At 440 , method 400 stops DPF regeneration by stopping injection of post-injection fuel. Also, method 400 may adjust engine boost pressure and exhaust throttle position to stop particulate filter regeneration. Method 400 proceeds to 442 .

[0068] At 442 , method 400 injects pilot and main fuel injection amounts at the injection start timing determined at 404 . The pilot fuel injection provides a desired level of engine noise and vibration and the main fuel injection provides a desired driver demand torque. Method 400 proceeds to exit.

[0069] At 408 , method 400 begins increasing PF temperature. Method 400 may increase boost pressure and at least partially close the exhaust throttle to increase exhaust temperature to begin PF regeneration. Method 400 proceeds to 410 .

[0070] At 410, method 400 determines a post fuel injection amount by referencing a table of empirically determined post fuel injection amounts. The empirically determined post fuel injection amount may be a post fuel injection amount that provides a desired level of catalyst temperature increase, starting from the catalyst temperature when the engine is operating at the same speed and driver demand torque without post fuel injection. For example, if the oxidation catalyst temperature without post fuel injection is 300°C at an engine speed of 2000 RPM and 200 Newton-meters (N·m), and the desired oxidation catalyst temperature for particulate filter regeneration is 650°C, then the post fuel injection amount that provides a 350°C oxidation catalyst temperature increase is the post fuel injection amount when the engine is operating at 2000 RPM and 200 N·m. The post fuel injection amount is stored in a table or function in non-transitory memory and may be referenced or indexed by engine speed and desired oxidation catalyst temperature increase. Likewise, a start-of-injection timing value for a post-fuel injection (e.g., the crankshaft angle at which a post-fuel injection begins for a cylinder cycle) can be determined by reference to a table of empirically determined start-of-injection timing values ​​for the post-fuel. The empirically determined timing value for the post-fuel injection can be an end-of-injection timing value for a post-fuel injection that provides a desired level of oxidation catalyst temperature rise and a desired residual amount of fuel in a cylinder in which the post-injected fuel is injected at a specific engine speed and desired level of oxidation catalyst temperature rise. The end-of-injection timing for the post-fuel injection can be stored in a table or function in a non-transitory memory and can be referenced or indexed by the engine speed and the desired oxidation catalyst temperature rise. The end-of-injection timing for the post-fuel injection is the crankshaft angle at which the post-fuel injection stops during a cylinder cycle. Method 400 proceeds to 412.

[0071] At 412, method 400 adjusts the pilot fuel injection amount, the main fuel injection amount, and the injection start timing of the main fuel injection. Specifically, the pilot fuel injection amount is reduced by an estimated amount of residual fuel burned during the compression phase of the cylinder cycle. Diesel fuel is a fuel that exhibits two-stage combustion. During the first stage of combustion (e.g., the low-temperature exothermic phase), larger chain hydrocarbons are broken down into smaller chain hydrocarbons in an exothermic reaction. The first stage of combustion can be characterized by the presence of formaldehyde formation and the absence of OH radicals and CO2. The second stage of fuel combustion is identified by the formation of CO2 and OH radicals. The second stage of fuel combustion can occur after compression ignition. The occurrence of both the first and second stages of combustion can be indicated by a change in cylinder pressure. The amount of residual fuel involved in the first stage combustion can be estimated by the amount of heat released during compression, which can be indicated by a rise in cylinder pressure. Furthermore, the amount of residual fuel from which the heat release originated can be estimated as further described in detail at 420. The amount of residual fuel participating in the first stage combustion can be expressed as a fraction of the residual fuel amount, and the fractional value can be stored in a table or function indexed by engine temperature, charge air temperature, cylinder air charge, and engine speed. The amount of the fraction can be determined empirically and can be multiplied by the residual fuel amount to determine the amount of residual fuel combusted during compression. The residual fuel amount combusted during compression can then be subtracted from the pilot fuel injection amount determined at 404 to determine the adjusted pilot fuel injection amount. In this way, an adjusted pilot fuel injection amount can be determined for each engine cylinder.

[0072] If the amount of residual fuel participating in the first stage combustion or compression stage combustion before the main fuel pulse starts to be injected is greater than a threshold, the start of the main fuel pulse width of the injection time can be delayed by a predetermined number of crankshaft degrees to delay the peak cylinder pressure, thereby limiting the engine torque so that the engine can produce a torque closer to the desired torque.

[0073] The amount of residual fuel participating in the second stage combustion can be estimated based on the heat release after compression ignition, which can be indicated by the increase in cylinder pressure. Furthermore, the amount of residual fuel from which the heat release originates can be estimated according to 420. The amount of residual fuel participating in the second stage combustion can be expressed as a fraction of the residual fuel amount, and this fractional value can be stored in a table or function indexed by engine temperature, charge air temperature, cylinder air charge, and engine speed. The magnitude of the fraction can be determined empirically and multiplied by the residual fuel amount to determine the amount of residual fuel combusted after compression ignition. The amount of residual fuel combusted after compression ignition can then be subtracted from the main fuel injection amount determined at 404 to determine an adjusted main fuel injection amount. In this way, an adjusted main fuel injection amount can be determined for each engine cylinder. After determining the adjusted pilot fuel injection amount, the adjusted main fuel injection amount, and the adjusted main fuel injection start timing, method 400 proceeds to 414.

[0074] At 414, method 400 injects the adjusted pilot injection fuel amount and the adjusted main fuel injection amount into the engine cylinder. The pilot injection begins at the pilot injection start timing determined at 404 and the main injection begins at the adjusted main injection start timing determined at 412. Method 400 proceeds to 416.

[0075] At 416 , method 400 determines the diesel oxidation catalyst (DOC) or oxidation catalyst temperature. The oxidation catalyst temperature may be determined by a temperature sensor. Method 400 proceeds to 418 .

[0076] At 418 , method 400 estimates inner and outer residual exhaust gases in the engine cylinders. The inner and outer exhaust gases in the engine cylinders may indicate an amount of residual fuel in the engine cylinders.

[0077] The internal exhaust residual is the gaseous residual (HC, NOx, and CO) that remains in the cylinder from the first combustion event in the cylinder (e.g., the combustion of air and fuel in the cylinder) to the next second combustion event. Except that the internal exhaust residual may include the residual that leaves the exhaust port after the first combustion event and is sucked back into the cylinder from the exhaust port before the second combustion event, the internal exhaust residual does not leave the cylinder from the first combustion event to the next or second combustion event. The internal exhaust residual does not include the exhaust residual that leaves the exhaust port and re-enters the cylinder through the intake port. In one example, method 400 estimates the amount of internal exhaust residual (IEGR) in the cylinder. In one example, the amount of internal residual can be estimated by reference to one or more tables or functions based on engine speed, engine load, boost pressure (e.g., engine intake manifold pressure), and exhaust throttle position or exhaust manifold pressure. The table or function has an estimated value of the amount of internal residual exhaust gas determined empirically. The table or function outputs the amount of internal exhaust residual.

[0078] The external exhaust residual can be determined by estimating exhaust flow through EGR passage 82 using pressure sensor 89. The mass of exhaust gas flowing through exhaust passage 82 is apportioned among the total number of engine cylinders to determine the external EGR mass in each cylinder during a cylinder cycle. Method 400 proceeds to 420.

[0079] At 420, method 400 determines the residual fuel amount of the fuel in the engine cylinder. An estimate for each engine cylinder can be provided in a similar manner. In one example, the residual fuel amount is estimated from the oxidation catalyst temperature rise. Specifically, the oxidation catalyst temperature rise is the oxidation catalyst temperature after the start of post-injection of fuel minus the oxidation catalyst temperature before the start of post-injection of fuel. The oxidation catalyst temperature rise provides an indication of the amount of post-injected fuel that is oxidized on the catalyst and not in the engine cylinder. The oxidation temperature rise attributable to a single cylinder can be determined by dividing the oxidation catalyst temperature rise by the number of active cylinders (e.g., cylinders that burn air and fuel). The oxidation catalyst temperature rise can be expressed as a function of the post-injected fuel burned in the oxidation catalyst (e.g., 1°C increase in oxidation catalyst temperature = X ppm of HC) and the portion of the burned HC can be allocated to each engine cylinder. Therefore, the oxidation catalyst temperature rise can be converted into an estimate of the amount of post-injected fuel that leaves the engine cylinder. The amount of fuel remaining in the engine cylinder from the first cylinder cycle to the second cylinder cycle (the second cylinder cycle immediately following the first cylinder cycle) can then be determined by subtracting the amount of fuel oxidized in the catalyst, which causes the catalyst temperature to increase, from the amount of post-injected fuel in the cylinder. The amount of fuel remaining is an estimate of the amount of fuel remaining in the engine cylinder.

[0080] In another example, the residual fuel amount is estimated from the end of the post-injection injection time, the post-fuel injection amount, the pressure difference between the engine intake manifold pressure and the engine exhaust manifold pressure to determine the internal EGR amount, and the external EGR in the engine cylinder. Specifically, the pressure difference between the engine intake manifold and the engine exhaust manifold can be converted to an IEGR amount as described at 418, and the external EGR amount can be added to the IEGR amount to determine the total EGR amount in the cylinder. The total EGR amount in the cylinder for the current cylinder cycle is the portion of the total exhaust gas in the cylinder at the end of the just-passed cylinder cycle. Furthermore, the total EGR amount in the engine cylinder can be estimated to include the same portion of post-injected fuel as the portion of EGR remaining in the cylinder during the current cylinder cycle. For example, if the cylinder contained X milligrams of exhaust gas after combustion in the cylinder during the just-passed cylinder cycle, and the cylinder contained 5% of X milligrams of exhaust gas (e.g., the total EGR amount) during the current cylinder cycle, it can be estimated that the cylinder also contained 5% or an adjusted fraction of the post-injected fuel amount during the just-passed cylinder cycle. Therefore, if Y mg of fuel was post-injected during the just-elapsed cylinder cycle, it can be estimated that 5% of the Y mg of post-injected fuel is included as residual fuel in the current cylinder cycle. The estimated post-injected fuel remaining in the cylinder, as determined from EGR, can be further adjusted as a function of the end timing of the post-injection to provide an estimate of the fuel residual. For example, a value in a table or function empirically determined by adjusting the end timing of the post-injection fuel can be indexed by the end timing of the post-injection and multiplied by the amount of post-injected fuel remaining in the cylinder to provide an adjusted post-injection amount of fuel remaining in the cylinder from one cylinder cycle to the next. Further, if the amount of fuel remaining in the engine cylinder is estimated from the amount of post-injected fuel, the increase in catalyst temperature can be estimated from the amount of post-injected fuel combusted in the catalyst (e.g., the difference between the amount of post-injected fuel and the amount of fuel remaining in the cylinder) and a function that expresses the relationship between the amount of post-injected fuel combusted in the oxidation catalyst and the increase in catalyst temperature (e.g., 1° C. increase in oxidation catalyst temperature = (X ppm of HC)).

[0081] In this manner, the amount of fuel remaining in one or more engine cylinders, or residual fuel, can be determined. The amount of post-injection fuel remaining in the cylinder from the current cylinder cycle to the next cylinder cycle is stored in controller memory so that it can be retrieved and used at 412 when method 400 is executed again for the next cylinder cycle.

[0082] At 422, method 400 determines whether DPF regeneration is complete. In one example, if the amount of soot in the DPF is less than a threshold, method 400 may determine that DPF regeneration is complete. Method 400 may determine that the amount of soot stored in the DPF is less than the threshold based on the pressure drop across the DPF. If method 400 determines that DPF regeneration is complete, the answer is "yes," and method 400 proceeds to exit. Otherwise, method 400 returns to 410.

[0083] therefore, Figure 4 A method provides an engine control method, comprising: estimating, by a controller, an amount of fuel remaining in a cylinder from a first cycle of the cylinder to a second cycle of the cylinder in response to a temperature increase of an oxidation catalyst; and adjusting, by the controller, an amount of fuel injected into the cylinder during the second cycle of the cylinder in response to the estimated amount of fuel. The engine control method further comprises estimating the amount of fuel remaining in the cylinder in response to injection timing of a post-fuel injection during the first cycle of the cylinder. The engine control method further comprises estimating the amount of fuel remaining in the cylinder in response to internal and external exhaust gas residuals in the cylinder. The engine control method further comprises estimating the amount of fuel remaining in the cylinder in response to a pressure difference between an intake manifold pressure and an exhaust manifold pressure. The engine control method comprises: wherein adjusting the amount of fuel injected during the second cycle of the cylinder comprises adjusting the amount of fuel in a pilot fuel injection. The engine control method comprises: wherein adjusting the amount of fuel injected during the second cycle of the cylinder comprises adjusting the amount of fuel in a main fuel injection. The engine control method comprises: wherein the second cycle of the cylinder immediately follows the first cycle of the cylinder. The engine control method further includes adjusting a start of injection timing of a main fuel injection during the second cycle in response to the estimated amount of fuel.

[0084] Figure 4 The method also provides an engine control method, comprising: estimating, via a controller, an amount of fuel remaining in the cylinder from the first cycle of the cylinder to the second cycle of the cylinder in response to a timing of post-injection fuel injected during a first cycle of the cylinder, an amount of post-injected fuel during the first cycle of the cylinder, an amount of exhaust residual in the cylinder during a second cycle of the cylinder, and a pressure difference between intake manifold pressure and exhaust manifold pressure; and adjusting, via the controller, an amount of fuel injected into the cylinder during the second cycle of the cylinder in response to the estimated amount of fuel. The engine control method includes: wherein injecting the post-injection fuel amount comprises injecting fuel via a second fuel injector between 20 and 30 crankshaft angle degrees before exhaust port opening during one cylinder cycle. The engine control method includes: wherein adjusting the amount of fuel injected during the second cycle of the cylinder comprises adjusting an amount of fuel in a pilot fuel injection. The engine control method includes: wherein adjusting the amount of fuel injected during the second cycle of the cylinder comprises adjusting an amount of fuel in a main fuel injection. The engine control method includes: wherein the second cycle of the cylinder immediately follows the first cycle of the cylinder.

[0085] Note that the example control and estimation routines included herein can be used with different engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and implemented by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. Furthermore, portions of the methods may be physical actions taken in the real world to change the state of a device. The specific routines described herein may represent one or more of any number of processing strategies (e.g., event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Thus, the various actions, operations, and / or functions described may be performed in the order described, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the described actions, operations, and / or functions may be performed repeatedly. Furthermore, the described actions, operations, and / or functions may graphically represent code programmed into non-transitory memory of a computer-readable storage medium in an engine control system, where the described actions are implemented by executing the instructions in a system including various engine hardware components in conjunction with an electronic controller. If desired, one or more of the method steps described herein may be omitted.

[0086] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be construed as limiting, as many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed four-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0087] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or a "first" element or the equivalent thereof. These claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal to, or different in scope than the original claims, are also deemed to be included within the subject matter of the present disclosure.

Claims

1. An engine control method, comprising: estimating, by a controller, an amount of fuel remaining in the cylinder from a first cycle of the cylinder to a second cycle of the cylinder based on a temperature increase of the oxidation catalyst; and An amount of fuel injected to the cylinder during the second cycle of the cylinder is adjusted by the controller in response to the estimated amount of fuel. 2 . The engine control method of claim 1 , further comprising estimating an amount of fuel remaining in the cylinder further in response to an injection timing of a post fuel injection during the first cycle of the cylinder. 3 . The engine control method of claim 1 , further comprising estimating an amount of fuel remaining in the cylinder in further response to an inner exhaust residual amount and an outer exhaust residual amount in the cylinder. 4 . The engine control method of claim 1 , further comprising estimating an amount of fuel remaining in the cylinder in further response to a pressure difference between an intake manifold pressure and an exhaust manifold pressure. 5 . The engine control method of claim 1 , wherein adjusting the amount of fuel injected during the second cycle of the cylinder includes adjusting the amount of fuel in a pilot fuel injection. 6 . The engine control method of claim 1 , wherein adjusting the amount of fuel injected during the second cycle of the cylinder includes adjusting the amount of fuel in a main fuel injection. 7 . The engine control method of claim 1 , wherein the second cycle of the cylinder immediately follows the first cycle of the cylinder. 8 . The engine control method of claim 1 , further comprising adjusting a start of injection timing of a main fuel injection during the second cycle in response to the estimated amount of fuel.

9. An engine system comprising: an opposed-piston diesel engine including a cylinder with a first fuel injector and a second fuel injector; a supercharger coupled to the opposed-piston diesel engine, the supercharger having a plurality of gear ratios; a turbocharger coupled to the opposed-piston diesel engine; an oxidation catalyst included in an exhaust system of the opposed-piston diesel engine; and A controller including executable instructions stored in non-transitory memory that provide an estimate of fuel remaining in a cylinder of the opposed-piston diesel engine from a first cycle to a second cycle of the cylinder based on a temperature rise of the oxidation catalyst.

10. The engine system of claim 9 further comprising additional instructions for adjusting a pilot fuel injection amount in response to the estimate of fuel remaining in the cylinder.

11. The engine system of claim 9 further comprising additional instructions for adjusting a main fuel injection amount in response to the estimate of fuel remaining in the cylinder.

12. The engine system of claim 9 further comprising additional instructions for adjusting timing of a main fuel injection in response to the estimate of fuel remaining in the cylinder.

13. The engine system of claim 9 further comprising additional instructions to adjust an amount of post-injected fuel injected during the second cycle of the cylinder in response to the estimate of the fuel remaining in the cylinder.

14. The engine system of claim 9 further comprising additional instructions for estimating fuel retained in the cylinder in response to a pressure difference between an engine intake manifold pressure and an engine exhaust manifold pressure.

15. The engine system of claim 9 further comprising additional instructions for estimating fuel remaining in the cylinder in response to an amount of external exhaust gas recirculation.

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