FIELD OF THE INVENTION:

[0001] This disclosure relates generally to internal combustion engine operation, and more particularly to systems and methods for controlling the transport of fuel into oil during the regeneration of aftertreatment devices receiving exhaust gas produced by internal combustion engine operation.

BACKGROUND

[0002] Aftertreatment devices are well known and widely used in various internal combustion engine applications for the aftertreatment of engine exhaust gases. For example, devices such as diesel oxidation catalysts (DOC), diesel particulate filters (DPF) and selective catalytic reduction (SCR) devices have been useful for handling and/or removing controlled pollutants, including carbon monoxide, nitric oxide, unburned hydrocarbons, sulfur, and soot in the exhaust stream of an engine.

[0003] Particulate filter aftertreatment devices collect particulate matter such as soot from the exhaust gas. The accumulation of the particulate matter can cause an increase in back pressure in the exhaust system. Unless the particulate matter is removed, the accumulation of the particulate matter in the aftertreatment device can lead to fuel inefficiencies and/or uncontrolled exothermic reactions that could damage the

aftertreatment device. In addition, the aftertreatment devices may be contaminated with reversible poisoning constituents such as sulphur-based constituents. These poisons reduce the performance of the aftertreatment devices, and non-compliance with emissions levels can result if these reversible poisons are not removed.

[0004] Removal of the particulate matter is commonly undertaken in a controlled regeneration process before excessive levels have accumulated. A controlled regeneration event can be initiated by the engine's control system when a predetermined amount of particulate has accumulated on the filter, when a predetermined time of engine operation has passed, or when the vehicle has driven a predetermined number of miles. In one method to initiate regeneration of a diesel particulate filter, a reactant, such as diesel fuel, is introduced into the exhaust after-treatment system in order to supply hydrocarbons (HC) to initiate oxidation of particulate buildup and to increase the temperature of the filter. The temperature of the particulate filter is dependent upon the temperature of the exhaust gas entering the particulate filter. Controlled regeneration typically consists of driving the filter temperature up to 0 ₂ oxidation temperature levels for a predetermined time period, such that oxidation of soot accumulated on the filter takes place. The temperature of the exhaust must be carefully managed to ensure that a desired particulate filter inlet exhaust gas temperature is accurately and efficiently reached and maintained for a desired duration, in order to achieve a controlled regeneration event that produces the desired results.

[0005] Conventional systems use various strategies for managing the particulate filter inlet exhaust gas temperature. For example, some systems use a combination of air handling strategies, internal fuel dosing strategies, and external fuel dosing strategies. Internal fuel dosing strategies include injecting additional fuel into the compression cylinders, so as to provide additional hydrocarbons to the after-treatment system to aid in initiation of oxidation of particulate buildup, and increase temperature of the filter. In- cylinder injections may include main injections intended to supply fuel for combustion, as well as pre-injections, i.e., fuel injections occurring before a main fuel injection, and post- injections, i.e., fuel injection occurring after a main fuel injection.

[0006] Generally, post-injections include heat post-injections and non-heat post- injections. Heat post-injections are injections that participate along with the main fuel injection in the combustion event within the cylinder, and occur relatively soon after the main fuel injection. Non-heat post-injections, also called very late post injections, are injections that occur later in the expansion stroke compared to the heat post-injections. The non-heat post injections are post-combustion; they do not participate in the combustion event within the cylinder, and may be conducted in order to supply hydrocarbons to aid the oxidation of particulate buildup in the exhaust after-treatment system. In some dosing strategies, injections may be split, such that, for example, a single non-heat post-injection may be split into two or more injections or shots.

[0007] In internal combustion engines, unburned fuel can be forced by a combustion event to slip past the seals between the piston head and the wall of the compression cylinder. For example, the unburned fuel can be blown by the seals, or unburned fuel adhering to the cylinder wall can be scraped by the piston rings into the crankcase. The unburned fuel that slips past the seals enters the crankshaft case chamber below the compression cylinders and is transported into lubricating oil in the chamber, and thus may intermix with or be diluted into the lubricating oil stored in the chamber. The resulting fuel-in-oil dilution level of an engine is a measure of unburned fuel in the lubricating oil in the crankshaft case (often expressed as the percentage by volume of unburned fuel in the fuel/oil mixture). Most engines generate normal amounts of fuel-in-oil dilution (e.g., less than about 3%-5%), and often normal amounts of diluted fuel in the oil evaporates from the heat of the engine without negatively affecting the engine. However, when fuel dilution levels reach above-normal levels, the fuel does not burn off to a sufficient level to avoid excessively thinning the oil. Fuel-diluted oil having excessively high fuel dilution levels can lower the lubricating properties of the oil, which can cause a drop in oil pressure and an increase in engine wear. Therefore, preventing the fuel dilution level of an engine from reaching above-normal amounts is an important part of proper engine maintenance and performance.

[0008] Although conventional regeneration fuel injection strategies may be adequate for controlling the temperature of exhaust generated by the engine to allow conduct of regeneration events, the conventional fuel injection strategies often fail to maintain acceptable fuel dilution levels. For example, conventional strategies with one heat post-injection participating in the combustion of fuel within the cylinder may result in excessively high fuel dilution levels. Further, conventional regeneration fuel injection strategies result in more than typical amounts of fuel being injected into the compression cylinder. As discussed above, some of this fuel does not participate in the combustion event, i.e., the fuel is not combusted, and is not vaporized. With more fuel being injected into the compression cylinder than can be combusted, and less vaporization of the fuel, the cylinders often contain excessive amounts of unburned and unvaporized fuel, which typically leads to increased fuel dilution levels.

[0009] Based on the foregoing, a need exists for an improved fuel injection strategy that achieves targeted engine outlet exhaust temperatures for conducting desired regeneration events, while also maintaining fuel dilution levels at or below an acceptable level for the engine.

SUMMARY

[0010] A system and method for controlling fuel transport to oil in connection with regeneration of an aftertreatment device that receives exhaust gas from operation of a multi-cylinder internal combustion engine are disclosed. While the system and method described herein have application in regeneration of aftertreatment devices such as DOC, DPF and SCR devices in an exhaust gas aftertreatment system of diesel engines, the method can be used in other filter technologies to improve the effectiveness of

regeneration of a filter or catalyst in non-diesel engines.

[0011] In some embodiments, the method may include controlling fuel transport to oil in an internal combustion engine, by determining a regeneration event for a particulate filter that receives exhaust gas from the internal combustion engine, the exhaust gas further being received by an oxidation catalyst. In response to the regeneration event, fuel is injected into at least one cylinder of the internal combustion engine at a first fuel pressure in an amount and timing to increase the exhaust gas temperature above a first threshold. In response to the exhaust gas temperature being above the first threshold, the method includes injecting fuel into the at least one cylinder very late post-combustion at a second fuel pressure that is greater than the first fuel pressure.

[0012] A system in which the method is employed may include a controller operably connected to the engine and to a fuel injector of the engine that is configured to inject fuel into a cylinder of the engine. The controller may include a regeneration module configured to determine a regeneration event associated with a particulate filter connected to the engine. The controller further includes a regeneration fuel injection module configured to, in response to the regeneration event determination by the regeneration module, inject fuel from the fuel injector into the at least one cylinder at a first fuel pressure, in an amount and timing that increases the exhaust gas temperature above a first threshold. In response to the exhaust gas temperature being above the first threshold and during a regeneration event, the regeneration fuel injection module is configured to inject fuel from the fuel injector into the at least one cylinder very late post-combustion at a second fuel pressure that is greater than the first fuel pressure.

[0013] This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1A shows one embodiment of an internal combustion engine system in which fuel transport to oil is controlled during regeneration of at least one aftertreatment device.

[0015] FIG. IB is a schematic of a cylinder of the engine of the system of Fig. 1 A.

[0016] FIG. 2 is a flow diagram of one embodiment of a procedure for controlling fuel transport to oil in a regeneration event.

[0017] FIG. 3 is a diagram illustrating an exemplary control apparatus for controlling fuel transport to oil in a regeneration event.

[0018] FIG. 4 is a chart showing fuel in oil dilution test data.

DETAILED DESCRIPTION

[0019] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

[0020] With reference to Fig. 1 A, a system 10 includes a four-stroke internal combustion engine 16. Fig. 1A illustrates an embodiment where the engine 16 is a diesel engine. The engine 16 can include a plurality of cylinders 22. Fig. 1 A illustrates the plurality of cylinders 22 in an arrangement that includes six cylinders in an in-line arrangement for illustration purposes only. Any number of cylinders and any arrangement of the cylinders suitable for use in an internal combustion engine can be utilized. The number of cylinders 22 that can be used can range from one cylinder to eighteen or more. Furthermore, the following description at times will be in reference to one of the cylinders 22.

[0021] FIG. IB illustrates an embodiment of a cylinder of FIG. 1A. It is to be realized that corresponding features in reference to the cylinder 22 described in Fig. IB at other locations herein can be present for the other cylinders of engine 16. The cylinder 22 houses a piston 35 that is operably attached to a crankshaft 39 that is rotated by reciprocal movement of piston 35 in cylinder 22. Within a cylinder head 41 of the cylinder 22, there is at least one intake valve 45, at least one exhaust valve 49 and a fuel injector 51 that provides fuel to a combustion chamber 54 formed by cylinder 22 between the piston 35 and the cylinder head 41.

[0022] The term "four-stroke" herein means the following four strokes - intake, compression, power, and exhaust - that the piston 35 completes during two separate revolutions of the engine's crankshaft 39. A stroke begins either at a top dead center (TDC) when the piston 35 is at the cylinder head 41 of the cylinder 22, or at a bottom dead center (BDC), when the piston 35 has reached its lowest point in the cylinder 22. [0023] During the intake stroke, the piston 35 descends away from cylinder head 41 of the cylinder 22 to a bottom (not shown) of the cylinder, thereby reducing the pressure in the combustion chamber 54 of the cylinder 22. In the instance where the engine 16 is a diesel engine, a combustion charge is created in the combustion chamber 54 by an intake of air through the intake valve 45 when the intake valve 45 is opened.

[0024] During the compression stroke, both the intake valve 45 and the exhaust valve 49 are closed, the piston 35 returns toward TDC and fuel is injected near TDC in the compressed air, and the compressed fuel-air mixture ignites in the combustion chamber 54 after a short delay. In the instance where the engine 16 is a diesel engine, this results in the combustion charge being ignited. The ignition of the air and fuel causes a rapid increase in pressure in the combustion chamber 54, which is applied to the piston 35 during its power stroke toward the BDC. Combustion phasing in combustion chamber 54 is calibrated so that the increase in pressure in combustion chamber 54 pushes piston 35, providing a net positive in the force/work/power of piston 35. During the exhaust stroke, the piston 35 is returned to the TDC while the exhaust valve 49 is open. This action discharges the burnt products of the combustion of the fuel in the combustion chamber 54 and expels the spent fuel-air mixture (exhaust gas) out through the exhaust valve 49.

[0025] As shown in FIG. IB, the fuel is injected into the cylinder 22 via fuel injector 51. As seen in FIG. 1A, the fuel is supplied by a high pressure common rail system 85 that is connected to the fuel tank 86. Fuel from the fuel tank 86 is suctioned by a fuel pump 87 and fed to the common rail system 85. The fuel fed from the fuel pump 87 is accumulated in the common rail system 85, and the accumulated fuel is supplied to the fuel injector 51 of each cylinder 22 through a fuel line 88. The accumulated fuel in the common rail system 85 can be pressurized using known systems to boost and control the fuel pressure of the fuel delivered to combustion chamber 54 of cylinders 22 via the fuel injectors 51.

[0026] The intake air flows through an intake passage 72 and intake manifold 73 before reaching the intake valve 45. The intake passage 72 may be provided with an air cleaner 64, a compressor 62a of a turbocharger 62 and an optional intake air throttle 68. The intake air may be purified by the air cleaner 64, compressed by the compressor 62a and then aspirated into the combustion chamber 54 through the intake air throttle 68. The intake air throttle 68 can be controlled to influence the air flow into the cylinder.

[0027] The exhaust gas flows out from the combustion chamber 54 into an exhaust passage 75 that may be provided with a turbine 62b and a waste-gate 62c of the

turbocharger 62. The exhaust gas then flows into an aftertreatment device 79. The exhaust passage 75 can further or alternatively include an exhaust throttle 149 for adjusting the flow of the exhaust gas through the exhaust passage 75. The exhaust gas, which can be a combination of by-passed and turbine flow, then enters the aftertreatment device 79.

[0028] Optionally, a part of the exhaust gas in the exhaust passage 75 can be recirculated into the intake air via an exhaust gas recirculation passage (EGR passage) 76. The EGR passage 76 connects the exhaust passage upstream of the turbine 62b to the intake passage 72 downstream of the intake air throttle 68. Alternatively or additionally, a low pressure EGR system (not shown) can be provided downstream of turbine 62b and upstream of compressor 62a. An exhaust gas recirculation valve (EGR valve) 80 for regulating the exhaust gas recirculation flow (EGR flow) is provided on the EGR passage 76. The EGR passage can be further provided with an EGR cooler 78 and a flow measurement device 81. EGR passage 76 is shown connected to intake passage 72 downstream of a CAC cooler 77, but can also be connected upstream of CAC cooler 77.

[0029] In one embodiment, exhaust gases are expelled into a common exhaust manifold. In the illustrated embodiment of FIG. 1A, the exhaust manifold is divided into two manifold portions 50a, 50b that receive exhaust gases from a respective first and second portions of the cylinders 22. The outlets 53a, 53b from the exhaust manifold portions 50a, 50b combine downstream of EGR passage 76 either upstream of turbine 62b, or at a singled inlet or a twin entry inlet to turbine 62a. Still other embodiments contemplate more than two exhaust manifold portions 50a, 50b dedicated to respective portions of the plurality of cylinders 22.

[0030] In one alternative embodiment, a first portion of cylinders 22 is connected to second exhaust manifold portion 50b that is connected to EGR passageway 76, which is connected to the intake passage 72 of engine 16. A second portion of cylinders 22 is connected to first exhaust manifold portion 50a which does not provide exhaust flow to EGR passage 76. In-cylinder dosing can be provided only to the second portion of cylinders 22 that do not provide exhaust flow to EGR passage 76, preventing injected fuel from being present in the EGR flow. In another embodiment with EGR, in-cylinder dosing can be provided to any cylinder 22

[0031] The aftertreatment device 79 herein means one or more devices useful for handling and/or removing material from exhaust gas that may be harmful constituents, including carbon monoxide, nitric oxide, nitrogen dioxide, hydrocarbons, and/or soot in the exhaust gas. In some examples, the aftertreatment device 79 can include at least one of a catalytic device and a particulate matter filter. The catalytic device can be a diesel oxidation catalyst (DOC) device, ammonia oxidation (AMOX) catalyst device, a selective catalytic reduction (SCR) device, three-way catalyst (TWC), lean NOX trap (LNT) etc. The reduction catalyst can include any suitable reduction catalysts, for example, a urea selective reduction catalyst. The particulate matter filter can be a diesel particulate filter (DPF), a partial flow particulate filter (PFF), etc. A PFF functions to capture the particulate matter in a portion of the flow; in contrast the entire exhaust gas volume passes through the particulate filter.

[0032] The arrangement of the components in the aftertreatment device 79 can be any arrangement that is suitable for use with the engine 16. For example, in one embodiment as shown in Figure 1A, a DOC 102 and a DPF 109 are provided upstream of a SCR device 111. In one example, a reductant delivery device 112 may additionally be provided between the DPF 109 and the SCR device 111 for injecting a reductant into the exhaust gas downstream of the cylinders 22 but upstream of SCR device 111. The reductant can be urea, diesel exhaust fluid, or any suitable reductant injected in liquid and/or gaseous form.

[0033] The common rail fuel system 85 is responsive to an in-cylinder fuel dosing command to inject fuel in-cylinder into one or more of the cylinders 22. The fuel injection into the cylinder combustion chamber 54 can occur according to commands communicated to the common rail system 85 concerning the amount of fuel injected, the timing of the injection, splitting of an injection, and the pressure at which an injection is conducted. The commands may be for a post-combustion injection, for example, which would occur after the main injection of fuel that combusts to satisfy a torque request, where at least a portion of the late post-injection fuel does not combust in cylinders 22 of engine 16. [0034] In embodiments, the system 10 further includes a controller 125 structured to perform certain operations to control system 10. The controller 125 is provided to receive data as input from various sensors to which it is operably connected, and send command signals as output to various actuators to which it is operably connected. Some of the various sensors and actuators that may be employed are described in more detail below. The controller 125 can include a processor, a memory, a clock, and an input/output (I/O) interface for inputs/outputs communicated between the controller 125 and the sensors and actuators. In general, the procedures of the method as depicted in FIG. 2 are executed by a processor of controller 125 executing program instructions (algorithms) stored in the memory of the controller 125.

[0035] The controller 125 may be structured to perform certain operations to control system 10 in achieving one or more target conditions. In certain embodiments, the controller 125 forms a portion of a processing subsystem including one or more computing devices having memory, processing hardware, and communication hardware. The controller may be a single device or a distributed device, and the functions of the controller 125 may be performed by hardware and/or instructions encoded on non-transient computer readable medium within controller 125.

[0036] In certain embodiments, the controller 125 includes one or more modules structured to functionally execute the operations of the controller 125. The description herein including modules emphasizes the structural independence of the aspects of the controller 125, and illustrates one grouping of operations and responsibilities of the controller 125. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or software on a non-transient computer readable storage medium, and modules may be distributed across various hardware or software components.

[0037] Certain operations described herein include operations to interpret or determine one or more parameters. Interpreting and/or determining, as utilized herein, includes receiving values by any method known in the art, including at least receiving values from a datalink or network communication, receiving an electronic signal (e.g. a voltage, frequency, current, or PWM signal) indicative of the value, receiving a software parameter indicative of the value, reading the value from a memory location on a non- transient computer readable storage medium, receiving the value as a run-time parameter by any means known in the art, and/or by receiving a value by which the interpreted or determined parameter can be calculated, and/or by referencing a default value that is interpreted or determined to be the parameter value.

[0038] The sensors that can be operatively connected to the controller 125 to send data thereto may include sensors (not shown) for detecting amounts of particulate matter that have accumulated on an aftertreatment filter, or detecting other operating parameters of the aftertreatment device 79 that indicate that a regeneration of one or more

aftertreatment components is needed. Such sensors may also be provided for determining the amount of time of engine operation, or for determining the number of miles that the vehicle has been driven, as a condition affecting the determination that an aftertreatment device 79 regeneration event is needed.

[0039] The sensors may include a crank angle sensor (not shown) that detects a crank angle at intervals of a specified crank angle so as to detect the rotational angle position and the rotation speed of the crankshaft 39. One or more pressure sensors 140 is operably connected and positioned to detect the fuel pressure of the common rail system 85 and/or one or more fuel injectors 51, so as to determine the pressure at which fuel will be injected into the cylinder(s) 22.

[0040] The sensors may also include temperature sensors 131 and 139 which detect the exhaust gas temperature upstream and downstream or at an inlet and outlet, respectively, of the aftertreatment device 79. Other sensors that can be provided include a DOC inlet temperature sensor 147, a DOC outlet temperature sensor 146, a DPF outlet temperature sensor 144, an SCR inlet temperature sensor 143, an SCR outlet temperature sensor 141, a mid-bed SCR temperature and/or NH ₃ sensor 142, an engine out NOx sensor 148 for estimating urea dosing and a tail pipe NOx sensor 151 for diagnostics or closed loop urea dosing control. The listed sensors are provided by way of illustration and should not be construed as limiting the sensors in system 10 to those listed or as requiring the system 10 to include those that are specifically listed.

[0041] The various actuators of system 10 include one or more actuators operatively connected to the controller 125 for opening, closing and/or modulating fuel injection outlets in the fuel injectors 51 to supply fuel to the cylinder(s) 22. The actuators control the injectors 51 to perform the fuel injections pursuant to commands from the controller 125 by controlling the timing of each fuel injection, the amount of fuel injected during each injection event, the pressure of the injected fuel, and the splitting of a fuel injection into two or more split injections. For example, the actuators may include fuel valves associated with each injector 51 operatively connected to the controller 125 so as to open and close pursuant to control commands from the controller 125 to control the fuel pressure level in the high pressure common rail system 85.

[0042] System 10 may also include a valve actuation mechanism that can be provided for opening and closing the intake valves 45, for opening and closing the exhaust valves 49. The various actuators that can be employed with system 10 are not all illustrated in Fig. 1A and IB, but one skilled in the art would know how to implement the mechanisms needed for each of the components to perform the intended function.

[0043] During operation, the controller 125 can receive information from the various sensors listed above through the I/O interface, process the received information using the processor based on an algorithm stored in the memory, and then send command signals to the various actuators through the I/O interface. For example, the controller 125 can receive information regarding a temperature input, process the temperature input, and then make a determination based on the temperature input and control strategy, send a command signal to one or more actuators of fuel injectors 51 to take steps in response to the input.

[0044] The system 10 can be configured to implement the disclosed method for controlling fuel transport to oil in connection with aftertreatment device regeneration. It should be understood the various components of system 10 are provided by way of illustration to promote an understanding of the invention, but the disclosed systems and methods may also be implemented on systems that differ from illustrated system 10.

[0045] In one embodiment, the disclosed method involves determining whether a regeneration event for an aftertreatment particulate filter is indicated, by assessment of one or more operating conditions of the system. A controlled regeneration event can be initiated by the controller 125 when, for example, a predetermined amount of particulate has accumulated on the filter, when a predetermined time of engine operation has passed, when the vehicle has driven a predetermined number of miles, or when another condition affecting the system 10 is detected. The controller 125 can be configured to control the implementation of the method using the system 10 by issuing commands for adjustment so as to achieve a target condition of the exhaust gas. In a specific embodiment, the target conditions of the exhaust gas enable activation of regeneration of the aftertreatment device such as, for example, by elevating the exhaust gas temperature to achieve a light-off condition of the aftertreatment device 79.

[0046] One target condition for the exhaust gas is a target temperature of the exhaust gas at a particular position in the exhaust passageway 75 that exceeds a certain (first) exhaust gas temperature threshold. In one specific example, when the DPF 109 is to be regenerated in response to a determination by controller 125 that a regeneration event exists, the target temperature is a temperature or range of temperatures exceeding a first threshold of the exhaust gas at the DOC 102 of the aftertreatment device 79 that is a DOC light-off temperature. In some instances, the first threshold temperature is set to be 250° C; in this instance the in-cylinder fuel dosing injection can be enabled to allow a higher range of target temperatures to be achieved downstream of the DOC 102. For example, the target temperature downstream at the DPF 109 can range from 400° C to 600° C. At these temperatures, the soot oxidation rate on the DPF 109 increases to allow for regeneration of the DPF 109. Target temperatures exceeding a first threshold can also be set for desulphation of the catalysts; desulphation temperatures depend on the catalyst formulation and can range from 400° C to above 650° C, although lower temperature are possible with longer regeneration times. Target temperatures exceeding a first threshold can also be set for the removal of urea based deposits. In some cases, temperatures at the SCR catalyst above 280° C are sufficient to remove ammonia-sulphate based compounds. When hard urea deposits form, temperatures in excess of 400 ° C and even in excess of 500 ° C might be needed to remove the deposits in a timely manner.

[0047] In some embodiments, operation of system 10 is controlled to achieve more than one target condition of the exhaust gas. For example, one or more operation conditions are controlled to achieve a target temperature range of the exhaust gas and a target amount of N0 ₂ or an amount of particulate matter in the exhaust gases.

[0048] In another example, one or more target conditions is at least one of a target temperature range of the exhaust gas and a target amount of oxygen present in the exhaust gas upstream of the aftertreatment device 79. In one instance, one or more target conditions is both a target temperature range of the exhaust gas and a target amount of oxygen present in the exhaust gas upstream of the aftertreatment device 79. In this instance, when one or more target conditions is reached, effective oxidation by oxygen can be achieved in the aftertreatment device 79.

[0049] With reference to FIG. 2, in one embodiment, the disclosed method is implemented using a procedure 200 that initiates at, for example, the start of engine 16 or at a key-on event. Procedure 200 includes an operation 202 to interpret regeneration parameters associated with the condition of the aftertreatment device 79. The regeneration parameters can be, for example, parameters indicating a need for regeneration or condition indicating that regeneration should be initiated. For example, such parameters may include a pressure drop across the aftertreatment device 79, a time elapsed since a last regeneration event, a number of miles driven by a vehicle since the last regeneration event, a catalyst and/or filter loading condition, an amount or estimate of particulate matter emitted from engine 16 since a last regeneration event, or any or other condition indicative of aftertreatment device performance that, when deficient, can be remedied through regeneration. The regeneration parameters can be indicative of any one aftertreatment device condition, or a combination of such conditions, such as of hydrocarbon adsorption on the catalysts, soot or particulate accumulation on DPF 109, sulphur or other poisoning of one or more catalysts, and/or ammonia-sulphate based deposit accumulation.

[0050] In response to the interpretation of the regeneration parameters at operation 202, procedure 200 continues at conditional 204 to determine if a regeneration event is indicated based on the regeneration parameters indicating regeneration is needed.

Interpretation of the regeneration event can include determining the type of regeneration event in view of the condition or conditions of the aftertreatment device 79 to be addressed, such as hydrocarbon adsorption, soot or particulate accumulation, sulphur or other poisoning, ammonia-sulphate based deposit accumulation, and/or a drop in deNOx efficiency of one or more catalysts. The indicator to initiate regeneration can be determined, for example, in response to regeneration parameters such as a temperature of aftertreatment device 79 exceeding a threshold at certain operating conditions, a pressure drop across the aftertreatment device 79 exceeding a threshold, a pressure at an inlet to aftertreatment device 79 exceeding a threshold, a time since a last regeneration event exceeding a threshold, a catalyst or filter loading condition exceeding a threshold, an amount or estimate of particulate matter emitted from engine 16 since a last regeneration event exceeding a threshold, an ammonia-sulphate deposit amount exceeding a threshold, or any or other condition indicating a regeneration event for aftertreatment device 79 is required or desirable. If a regeneration event is not indicated at conditional 204, procedure 200 returns to operation 202. If conditional 204 is positive, procedure 200 continues at operation 206.

[0051] Operation 206 includes initiating the regeneration event with a first fuel dosing mode of operation that includes in-cylinder fuel dosing. In one embodiment, the timing of the fuel dosing is controlled by the controller 125 to be a heat post-injection that is timed so that the fuel is injected shortly after the main injection to aid in the

aftertreatment device, in particular the DOC 102, reaching a light-off temperature. The heat post-injection at operation 206 raises the temperature of the exhaust gases expelled from the cylinders to aid in the DOC 102 reaching the light-off temperature. In another embodiment, the timing of the fuel dosing at operation 206 is controlled by the controller 125 to be a split post injection, such that the heat post-injection is split into two or more heat injections of fuel as DOC 102 approaches the light-off temperature.

[0052] In an embodiment, the quantity of fuel dosed in the heat post-injection at operation 206 is determined and controlled by the controller 125 to obtain a target condition that corresponds to, for example, a temperature of DOC 102. The quantity of fuel dosing could be determined by closed loop feedback control based on DOC temperature, or could also be based on an open loop estimation. Appropriate limits to the fuel dosing quantity at operation 206 can be applied to prevent high hydrocarbon slip based on DOC temperature and exhaust flow rate. In one embodiment, the fuel dosing mode at operation 206 is controlled to increase the temperature of the exhaust gas expelled from the cylinders in an amount sufficient to aid in the DOC 102 reaching a light-off temperature. Hydrocarbons in the exhaust gases oxidize across the DOC 102 and the exothermic reaction increases the exhaust gas temperature as it exits the DOC 102.

[0053] In an embodiment of the procedure 200, the operation 206 includes a fuel dosing mode of operation that includes in-cylinder fuel dosing at a selected fuel injection pressure. The controller 125 controls the dosing at operation 206 such that the pressure at which fuel is injected by the fuel injector 51 into the cylinder 22 in a heat post-injection is a first fuel injection pressure, denoted as pressure PI in FIG. 2. The controller 125 at operation 206 controls the heat post-injection to have the first fuel injection pressure during a condition in which the exhaust gas temperature in the DOC 102 is lower than a first threshold temperature. The heat post-injection at operation 206 having the first fuel injection pressure is made in a timing and amount to increase the exhaust gas temperature expelled from the cylinders, so as to aid the DOC 102 to reach a light-off temperature.

[0054] After operation 206, as shown in FIG. 2, the procedure 200 proceeds at an operation 208 to interpret a temperature of the exhaust gas. The heat post- injection at operation 206 raised the temperature of the exhaust gases to aid in reaching a light-off temperature in the aftertreatment device, in particular, a light-off temperature in the DOC 102, and so it is expected that the temperature of the aftertreatment device was increased after dosing operation 206. The operation 208 may include, for example, obtaining data on temperature readings made by sensors such as temperature sensors 131 and 139 which detect the exhaust gas temperature upstream and downstream or at an inlet and outlet, respectively, of the aftertreatment device 79. In particular, temperature sensors of the DOC 102 may detect data on exhaust gas temperatures in the DOC 102.

[0055] The temperature data interpreted in operation 208 is compared to a first exhaust gas temperature threshold in conditional 210. The first exhaust gas temperature threshold may be a first temperature threshold determined by the controller 125 with reference to operating condition data of the engine determined by sensors in operable communication with the controller 125, which interprets the data and determines the first exhaust gas temperature threshold in reference to the data. In an example embodiment, the first temperature threshold corresponds to a light-off temperature of the DOC 102. In a condition in which the temperature interpreted in operation 208 equals or exceeds the first temperature threshold, then the conditional 210 is satisfied and the procedure 200 proceeds to the next operation 212. In a condition in which the temperature interpreted in operation 208 does not equal or exceed the first temperature threshold, the conditional 210 is not satisfied, and then the process 200 iterates such that the operation 206 heat post-injection at first fuel injection pressure PI is repeated until the conditional operation 210 is satisfied. In this regard, the injection of fuel into the cylinder 22 at the first fuel pressure PI is performed during a warm-up phase of operation of the engine to warm up the DOC 102 to its light-off temperature.

[0056] In response to conditional 210 being satisfied, the procedure 200 proceeds to operation 212. Operation 212 includes a second fuel dosing mode of operation, which may continue to include in-cylinder dosing that includes post-injections. Operation 212 may include such heat post-injections that are made at a second fuel pressure P2 that is higher than the first fuel pressure PI . Operation 212 may include non-heat post-injections that are made at the second fuel pressure P2 that is higher than pressure PI.

In one embodiment, the second fuel injection pressure P2 is controlled to be equal to or greater than a selected lower limit, and the first fuel injection pressure PI is controlled to be less than the selected lower limit. In engine operating conditions, the levels of PI and P2 may not be static, varying according to engine operating conditions such as engine speed and torque demand. In some operating conditions, the levels of PI may be equal to P2, but in an embodiment of the invention, the levels of PI and P2 are controlled such that the formula P2>P1 is satisfied. In an embodiment applied in certain engine geometries and operating conditions, the difference between the first fuel injection pressure PI and the second fuel injection pressure P2 is no greater than 100 bar. In an embodiment applied in other engine geometries and operating conditions, the difference between the first fuel injection pressure PI and the second fuel injection pressure P2 may be greater than 100 bar.

[0057] In one embodiment, the timing and amount of the higher pressure fuel dosing conducted at operation 212 is controlled by the controller 125 to be a non-heat post- combustion injection (i.e., a very late post-injection). In one embodiment, the timing of the fuel dosing at operation 212 is controlled by the controller 125 to be a non-heat post- injection that is timed so that the fuel is not combusted with the main injection, and instead doses hydrocarbons into the exhaust gas. In another embodiment, the timing of the higher pressure fuel dosing at operation 212 is controlled by the controller 125 to be a split post injection, such that the very late post injection is split into two or more bursts or shots.

[0058] In an embodiment of the procedure 200, the operation 212 includes a fuel dosing mode of operation that includes in-cylinder fuel dosing at a selected fuel injection pressure P2. The controller 125 controls the dosing at operation 212 such that the selected pressure at which fuel is injected by the fuel injector 51 into the cylinder 22 in the post- combustion injection is at the higher second fuel injection pressure P2. The controller 125 at operation 206 controls the post-combustion injection to have the second fuel injection pressure P2 during a condition in which the exhaust gas temperature is above the first threshold temperature, as interpreted in operation 208 and satisfying the conditional 210, such that the exhaust gas temperature is above the DOC 102 light-off temperature.

Injecting fuel post-combustion into the cylinder 22 at the second fuel pressure P2 is performed after the DOC 102 reaches a light-off temperature and any other late post- injection enablement conditions are satisfied. In one embodiment, the second fuel pressure P2 at which the fuel injection of operation 212 is conducted is greater than first fuel pressure PI, such that the formula P2>P1 is satisfied. In another embodiment, the controller 125 is configured and structured to control the dosing at operation 212 at the higher fuel injection pressure P2 based on a condition where non-heat post-injection is activated. This condition may be activated in response to information regarding engine conditions such as temperature input received by the controller 125.

[0059] In an embodiment, the quantity of fuel dosed in the heat and non-heat post- injections at operation 212 is determined and controlled by the controller 125 to obtain a target condition that corresponds to, for example, a temperature of DPF 109. The quantity of fuel dosing could be determined by closed loop feedback control based on DPF temperature, or could also be based on an open loop estimation. Appropriate limits to the fuel dosing quantity at operation 212 can be applied to prevent high hydrocarbon slip based on DPF temperature and exhaust flow rate. In one embodiment, the fuel dosing mode at operation 212 supplies hydrocarbons to the exhaust gases expelled from the cylinders in an amount sufficient to aid in the DPF 109 reaching a temperature sufficiently high to aid in raising the oxidation rate of particulate matter in the DPF 109. Hydrocarbons in the exhaust gases oxidize across the DOC 102 and the exothermic reaction increases the exhaust gas temperature as it exits the DOC 102. [0060] FIG. 3 is a diagram illustrating an exemplary control apparatus 300 for controlling fuel transport to oil in a regeneration event. The control apparatus 300 may include the controller 125, which may include a regeneration module 135 and a regeneration fuel injection module 145. The modules 135, 145 of the controller 125 may be configured and structured to receive inputs via signal connections provided between the controller 125 or its modules, and sensors of the system as previously described. The inputs may include a particulate filter condition 301, a DOC inlet temperature 303 (or other suitable temperature or condition such as exhaust gas temperature indicative of DOC temperature), and a rail pressure 305 of the high pressure common rail system 85. An exemplary engine condition input, such as a particulate filter condition 301, is detected by sensors in the system 10 as previously described, and is communicated via signals sent to the regeneration module 135 via operative connections between the module 135 and the sensors positioned and adapted to detect the condition 301 in the aftertreatment device 79.

[0061] The regeneration module 135 is configured and structured to interpret the data incorporated in the signals relating to the particulate filter condition 301 to determine whether to command a regeneration event, and if so, the type of regeneration event to command, in view of the condition or conditions of the aftertreatment device 79. A command of a regeneration event may be indicated in response to regeneration parameters, including any condition indicating a regeneration event for aftertreatment device 79 is required or desirable. If a regeneration event is indicated, the regeneration module is configured and structured to issue a regeneration command 310 communicated to the regeneration fuel injection module 145.

[0062] The regeneration fuel injection module 145 is structured and configured to receive and interpret the regeneration command 310, the DOC inlet temperature input 303 (or exhaust gas or other suitable temperature), and the rail pressure input 305.

Additionally, a DOC inlet temperature threshold 307 (or exhaust gas or any suitable temperature threshold associated with the DOC) may be a fixed temperature, received and interpreted by the regeneration fuel module as an input according to system or controller settings input to the system 10, or may be calculated and determined by the regeneration fuel injection module 145 based on vehicle or engine operating condition inputs received by the controller 125 or the module 145 from sensors of the system 10 operatively connected thereto.

[0063] Based on receipt of the regeneration command 310, the regeneration fuel injection module 145 is structured and configured to compare the received DOC inlet temperature input 303 to the DOC inlet temperature threshold 307, as shown in output 320 of FIG. 3. The module 145 is further structured and configured to provide the output 320 in response to the DOC inlet temperature contained in the data of the DOC inlet temperature input 305 being greater than the DOC inlet temperature threshold 307.

[0064] If the output 320 indicates the DOC temperature is less than the threshold, the regeneration fuel injection module 145 is structured and configured to issue a PI injection command 330 to the fuel injector 51. The PI injection command 330 controls the operation of the actuators of the fuel injector 51 to inject fuel at the first fuel pressure PI as previously described. On the other hand, if the output 320 indicates the DOC temperature is greater than the threshold, the regeneration fuel injection module 145 is structured and configured to issue a rail pressure increase command 340 to the common rail system 85 and the fuel injector 51. This rail pressure increase command 340 operates actuators in the common rail system 85 to effectuate an increase in rail pressure that in turn increases the pressure at which the fuel injectors 51 make in-cylinder fuel injections. Upon the event of adequate increase of pressure to satisfy the rail pressure increase command 340, the module 145 issues a P2 injection command 350 to the fuel injector 51. The P2 injection command 350 controls the operation of the actuators of one or more of the fuel injectors 51 to inject fuel at the second fuel pressure P2 into the corresponding cylinder(s) 22, such that the formula P2>Plis satisfied, as previously described.

[0065] In a preferred embodiment, the PI and P2 fuel injection pressures satisfy the formula P2>P1. In one embodiment, the timing of one or more of the fuel injections commanded in the PI fuel injection command 330 is controlled to be a heat post-injection. In an embodiment, the timing of one or more of the fuel injections commanded in the P2 fuel injection command 350 is controlled to be a heat post-injection. In an embodiment, the timing of one or more of the fuel injections commanded in the P2 fuel injection command 350 is controlled to be a non-heat post-combustion injection. In an additional embodiment, the timing of fuel injections commanded in the P2 fuel injection command 350 is controlled to include both a heat post-injection, and a non-heat post-combustion injection. In one embodiment, the timing of one or more of the injections commanded in the PI and P2 fuel injection commands may be controlled to be one or more split injections.

[0066] The methods and systems described herein yields unexpected

improvements in reduction of transport of fuel to oil in the crankcase while also maintaining oxidation catalyst warm-up capability. The inventors have determined that the fuel dilution in the chamber may be reduced while still maintaining the engine's capability for quick warm-up to light-off temperature, by injecting fuel at a lower fuel injection pressure PI when the exhaust gas temperature is below the first threshold (light-off) temperature of the oxidation catalyst, and increasing the fuel injection pressure P2 and injecting very late (non-heat) post-combustion when the exhaust gas temperature reaches or exceeds the first threshold or light-off temperature. This fuel pressure control strategy decreases the length in time of each post-combustion injection event conducted after light- off temperature has been reached, and this shortened injection time has the effect of reducing fuel in oil dilution. The post-combustion injection can be split into at least two injection bursts, particularly when the fuel quantity exceeds a threshold fuel quantity, but the injection still occurs at the second fuel injection pressure P2, wherein the formula P2>P1 is satisfied.

[0067] FIG. 4, which illustrates a reduction in fuel in oil dilution levels achieved by employing a higher fuel injection pressure, such as P2 where the formula P2>P1 is satisfied. A fuel in oil dilution rate is shown as a percentage by volume of unburned fuel detected in the lubricating oil in the crankshaft case, plotted against engine operation time in hours. Line A of FIG. 4 shows results of a control sample operating in ordinary conditions, where post-combustion fuel injection is conducted at the lower fuel injection pressure PI regardless of the exhaust gas temperature being below or above the first threshold temperature (light-off temperature). Line B shows results achieved where the fuel injection pressure is raised to a higher fuel injection pressure, such as P2 where the formula P2>P1 is satisfied. Comparison of Line A to Line B show illustrates lower fuel in oil dilution percentages over time achieved by employing the higher fuel injection pressure. [0068] According to one aspect, a method for controlling fuel transport to oil in an internal combustion engine includes: determining a regeneration event for a particulate filter that receives exhaust gas from the internal combustion engine, the exhaust gas further being received by an oxidation catalyst; in response to the regeneration event, injecting fuel into at least one cylinder of the internal combustion engine at a first fuel pressure in an amount and timing to increase the exhaust gas temperature above a first threshold; and in response to the exhaust gas temperature being above the first threshold, injecting fuel into the at least one cylinder very late post-combustion at a second fuel pressure that is greater than the first fuel pressure.

[0069] In one embodiment, the second fuel pressure results in a reduction of transport of fuel to oil relative to the first fuel pressure. In another embodiment, the first threshold for the exhaust gas temperature corresponds to a light-off temperature of the oxidation catalyst. In yet another embodiment, the internal combustion engine is a diesel engine.

[0070] In another embodiment, injecting fuel into the at least one cylinder of the internal combustion engine at the first fuel pressure is performed during a warm-up phase of operation of the internal combustion engine to warm-up the oxidation catalyst to a light- off temperature. In a refinement of this embodiment, injecting fuel very late post- combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure is performed after the oxidation catalyst reaches light-off temperature. In a further refinement, injecting fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure doses hydrocarbons into the exhaust gas.

[0071] In another embodiment, the method includes a main fuel injection for combustion of fuel in the at least one cylinder that occurs before the very late post- combustion injections at the second fuel pressure. In still another embodiment, injecting fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure is performed as a split post-combustion injection. In yet another embodiment, the method includes a main fuel injection for combustion of fuel in the at least one cylinder that occurs before the injection of fuel at the first fuel pressure. [0072] According to another aspect, a system for controlling fuel transport to in oil in an internal combustion engine is provided. The system includes a controller operably connected to the engine and to a fuel injector of the engine that is configured to inject fuel into a cylinder of the engine. The controller includes a regeneration module configured to determine a regeneration event associated with a particulate filter connected to the engine and a regeneration fuel injection module configured to, in response to the regeneration event determination by the regeneration module, inject fuel from the fuel injector into the at least one cylinder at a first fuel pressure in an amount and timing that increases the exhaust gas temperature above a first threshold, and in response to the exhaust gas temperature being above the first threshold and during the regeneration event, inject fuel from the fuel injector into the at least one cylinder very late post-combustion at a second fuel pressure that is greater than the first fuel pressure.

[0073] In one embodiment, the injection of fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure results in a reduction of transport of fuel to oil relative to the first fuel pressure. In another embodiment, the first threshold for the exhaust gas temperature corresponds to a light-off temperature of the particulate filter. In yet another embodiment, the internal combustion engine is a diesel engine.

[0074] In another embodiment, the injection of fuel into the at least one cylinder of the internal combustion engine at the first fuel pressure is performed during a warm-up phase of operation of the internal combustion engine to warm-up the particulate filter to a light-off temperature. In a refinement of this embodiment, the injection of fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure is performed after the particulate filter reaches light-off temperature. In a further refinement, the injection of fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure doses hydrocarbons into the exhaust gas.

[0075] In another embodiment, the regeneration fuel injection module is configured to inject fuel from the fuel injector into the at least one cylinder in a main fuel injection for combustion of fuel in the at least one cylinder that occurs before the very late post-combustion injections. In yet another embodiment, the injection of fuel very late post-combustion into the at least one cylinder of the internal combustion engine at the second fuel pressure is performed as a split post-combustion injection.

[0076] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described. Those skilled in the art will appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

[0077] In reading the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.