In-cylinder EGR for regulating the air-fuel ratio

Abstract

System for air-fuel ratio (AIRR) management in a multi-cylinder engine (100), the engine comprising: corresponding reciprocating pistons (160) in the multiple cylinders (1-6), the corresponding reciprocating pistons being connected to a crankshaft (101) for rotating the crankshaft, a computer-controlled fuel injection system configured to inject fuel into the multiple cylinders, corresponding computer-controlled inlet valves (130) and exhaust valves (150) for opening and closing the multiple cylinders, and a computer control network connected to the fuel injection system and the corresponding inlet and exhaust valves, the network comprising a processor, a tangible storage device (1401), and control algorithms executable by processor (1403) for implementing an air-fuel ratio management method.wherein the method comprises: detecting a power output demand on the engine (100); determining a fuel-saving air-fuel ratio based on the detected power output; detecting a current air-fuel ratio either in an intake manifold (103) connected to the engine, an exhaust manifold (105) connected to the engine, or in both; determining an adjustment of an air-fuel ratio based on the determined fuel-saving air-fuel ratio and based on the detected current air-fuel ratio; selecting an in-cylinder exhaust gas recirculation procedure based on the determined adjustment of the air-fuel ratio, wherein the in-cylinder exhaust gas recirculation procedure adjusts an oxygen content and a particulate matter content of exhaust gas resulting from combustion; selecting a number of cylinders of the multi-cylinder engine,to implement the in-cylinder exhaust gas recirculation process; and controlling the inlet valves (130) and the exhaust valves (150) for the selected number of cylinders to adjust the oxygen content and particulate matter content of the exhaust gas by applying a second compression stroke of the corresponding pistons (160) of the selected number of cylinders (1-6) to the exhaust gas; wherein selecting the in-cylinder exhaust gas recirculation process includes selecting between a cylinder deactivation mode, a reverse intake mode, and a re-intake mode,

Description

Field of InterestThis application provides systems and methods for utilizing in-cylinder exhaust gas recirculation to adjust an engine air-fuel ratio.Prior ArtCylinder deactivation (ZAS) improves low load and idle fuel economy by reducing losses associated with otherwise low usage of a cylinder. By utilizing ASS, either fuel for the normally running cylinders is increased or their air-fuel ratio (LKV) is decreased to compensate for the lack of torque from the ASS cylinders.Exhaust gas recirculation (EGR) methods route exhaust gas from a point downstream of the exhaust manifold back to the intake manifold. EGR is useful for pollutant combustion and for adjusting ACV for combustion. External circuits lose heat and are subject to leaks. DE 10 2014 206 305 A1 proposes a method for the alternating cylinder deactivation of a three-cylinder or five-cylinder internal combustion engine in partial load operation, in which the opening of the gas exchange valves of the deactivated cylinders is deactivated. The valve deactivation of the deactivated cylinders is intended to begin or end their regular intake stroke with the deactivation and subsequent reactivation of the inlet valves of these cylinders in each case initially.SUMMARYThe present invention resides in a system for air-fuel ratio (LCV) management in a multi-cylinder engine according to claim 1 and a system for temperature management in a multi-cylinder engine according to claim 38. A current air-fuel ratio is detected in either an engine-connected intake manifold, an engine-connected exhaust manifold, or both. An adjustment of an air-fuel ratio is determined based on the determined fuel saving air-fuel ratio and based on the detected current air-fuel ratio. An in-cylinder exhaust gas recirculation method is selected based on the determined air-fuel ratio adjustment. The in-cylinder exhaust gas recirculation method adjusts an oxygen and particulate matter content of exhaust gas arising as a result of combustion. A number of cylinders of the multi-cylinder engine is selected to implement the in-cylinder exhaust gas recirculation method. The intake valves and the exhaust valves are controlled for the selected number of cylinders to adjust the oxygen and particulate matter content of the exhaust gas by applying a second compression stroke of the respective pistons of the selected number of cylinders to the exhaust gas. Selecting the in-cylinder exhaust gas recirculation method includes selecting between a cylinder deactivation mode, a reverse intake mode, and a re-intake mode.The method for temperature management performed in the system of claim 38 comprises detecting a power output request to the engine and detecting a current air-fuel ratio in an intake manifold connected to the engine, an exhaust manifold connected to the engine, or both. A low temperature condition is detected in an intake manifold and / or an exhaust manifold. An adjustment of an air-fuel ratio by thermal management is determined based on the detected current air-fuel ratio and based on the low temperature condition. An in-cylinder exhaust gas recirculation method is selected based on the determined air-fuel ratio adjustment through thermal management. The in-cylinder exhaust gas recirculation method adjusts a combustion-induced oxygen and particulate matter content of exhaust gas to decrease the air-fuel ratio of available gases for combustion. A number of cylinders of the multi-cylinder engine is selected to implement the in-cylinder exhaust gas recirculation method. The intake valves and the exhaust valves are controlled for the selected number of cylinders to apply a second compression stroke of the respective reciprocating pistons of the selected number of cylinders to the exhaust gas. The temperature of the exhaust gas is adjusted by reburning the exhaust gas to which a second compression stroke has been applied. A catalyst temperature may be controlled by controlling the exhaust temperature. Instead of manifold temperature, catalyst temperature may be monitored to determine that a low temperature condition exists.The methods disclosed herein are implemented by a system comprising a multi-cylinder engine, the engine comprising respective reciprocating pistons in multiple cylinders, the respective pistons being connected to a crankshaft to rotate the crankshaft. A computer controllable fuel injection system is configured to inject fuel into the plurality of cylinders. Respective computer controllable intake valves and exhaust valves are configured for opening and closing the plurality of cylinders. A computer control network is connected to the fuel injection system and the corresponding intake valves and exhaust valves. The network includes a processor, a tangible storage device, and processor-executable control algorithms for implementing the disclosed methods.Other objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic illustration of an engine system.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic illustration of an engine system. FIG. 2 is a schematic illustration of a computer control network. FIGS. 3A-3C show aspects of engine cylinders. FIG. 4 shows catalyst efficiencies for an example catalyst. FIGS. 5A-5H show amplitude profiles for valve actuations and fuel injections with piston positions over time. FIGS. 6A-6C show variations for reverse intake mode. FIGS. 7A-7C show variations for re-aspiration mode. FIG. 8 shows modes of in-cylinder EGR in a comparison of turbine output temperature and brake specific fuel consumption. FIG. 9 shows an over-cylinder oxygen excess for an example manifold in in-cylinder EGR methods. FIG. 10 is a flow chart for methods of air fuel ratio management and temperature management.DETAILED DESCRIPTIONDetailed reference to the examples illustrated in the accompanying drawings follows. As far as possible, the same reference numerals are used for all drawings to refer to the same or similar parts. Directional references such as "left" and "right" are used to facilitate reference to the figures. Terms such as "upstream" and "downstream" are used to indicate the direction of flow from a fluid entry point to a fluid exit point. Fluids in this disclosure may include a variety of compounds including fresh air or ambient air, exhaust gas, other combustion gases, evaporated fuel, or catalysts such as, but not limited to, urea. This disclosure is primarily concerned with the operation of diesel engines, but principles of this disclosure may be applied to other fuel-powered engines and engine systems, including those powered by bio-fuels and other petroleum products such as gasoline, as well as hybrid electric vehicles.A diesel engine cylinder deactivation system 10 includes a multi-cylinder diesel engine 100 including at least one corresponding intake valve 130 and at least one corresponding exhaust valve 150 for each of the plurality of cylinders 1- 6. An intake manifold 103 is provided for distributing fluid flow to the cylinders 1-6. An exhaust manifold 105 is used to collect or distribute exhaust gas to the cylinders 1-6. A valve control system comprising a variable valve timing (VVS) controller 200 is coupled to selectively deactivate a respective intake valve 130 and exhaust valve 150 of a selected cylinder 1- 6 of the multi-cylinder diesel engine 100. A fuel injection control system comprising a fuel control device 300 is connected to selectively disable fuel injection into the selected cylinders and simultaneously increase fuel for the igniting cylinders. The multi-cylinder diesel engine 100 enters a cylinder deactivation mode whereby the valve control system, including a VVS controller 200, shuts off the corresponding intake valve and exhaust valve of the cylinder while continuing to ignite other cylinders of the multi-cylinder diesel engine. The fuel injection control system shuts down fuel injection into the cylinders and adjusts fuel for the igniting cylinders. The manifolds and VVS controller 200 are used to balance the flow of air through cylinders 1- 6.In a first aspect, the shortening of the time for heating the catalyst 800 is advantageous for many vehicles, in particular for medium and high load diesel engines. Most off-road engines do not meet the current FTP (Federal Testing Procedure) NOx requirements, since the majority of their running time is under low load, resulting in low temperature exhaust gases. FIG. 4 shows an example of catalyst efficiency for catalyst 800. Adjustment of the filter material of the catalyst 800 shifts the illustrated line. For example, the catalyst 800 has a "base layer" of material through which the exhaust gases 420 pass. The heat of this "base layer" affects the efficiency of detecting dirt. Oxides of nitrogen and nitrous oxides (NOx) are the target pollutant in FIG. 4. At 100° C., the catalyst has an efficiency of 0% in the detection of NOx (point A). At 150° C., the catalyst converts only 24% NOx (point B). Increasing the exhaust temperature to 200°C (point C) increases the conversion efficiency to up to 78%, to 90% at 250°C (point D) and to 96% at 300°C (point E). Therefore, for the catalyst in the example, an exhaust temperature of about 300° C. is ideal. The thermal management methods disclosed herein dramatically reduce the time to bring the catalyst 800 to an effective pollution filtering temperature.For example, many off-road vehicles do not meet the Federal Testing Procedure (FTP) standard because they require 7-20 minutes to reach an effective temperature at all. Using the on-demand method disclosed herein, ZAS mode, reverse aspiration mode, re-aspiration mode, or combinations thereof may be implemented to generate heat very quickly. Instead of in 7-20 minutes, catalyst 800 may reach an effective pollution filtering temperature in 10-550 seconds, preferably within 10-90 seconds, or within 90-180 seconds. Additionally, achievable time ranges for heating an aftertreatment device to a target temperature, such as at or above 250° C., may depend on, among other things, the material selection for the catalyst base layer, the type of fuel, or the catalyst agent used.Material selection limits which temperature the catalyst is effective, which temperature the catalyst is destroyed by sintering effects, and which temperature the catalyst can perform diesel particulate matter regeneration at point R. FIG. 4 shows that at a regeneration temperature of 500° C., the catalyst is only 50% effective in detecting NOx. According to performing diesel particulate regeneration of the catalyst 800, a timer may also be run. When an exhaust time exceeding a time threshold is detected, the computer controller 1400 may execute control programming to enter a diesel particulate regeneration mode by implementing the increased heat output mode.Usually, the temperature of the exhaust gas may fluctuate based on the revolutions per minute (rpm) of the crankshaft 101 and based on the engine load. Many vehicles, such as buses and off-road vehicles, can only achieve effective pollutant management temperature when transported on expressways, but not during slow modes of operation. When implementing an exhaust temperature management method disclosed herein, a majority of the engine operating bandwidth may result in an exhaust temperature that results in the catalyst 800 filtering fouling efficiently at any crankshaft rpm and engine load.By utilizing a cylinder for fuel combustion at an optimum air-fuel ratio (LKV), an exhaust gas flow of higher temperature is generated. The fuel efficiency for the optimum ACV combustion is quite high and the torque output is high. Interrupting fuel delivery to some cylinders and closing associated valves allows heat to be generated to the closed cylinder via a combustion stroke. Heating a charge in this manner removes fouling by combustion in some cylinders and increases overall fuel economy.Referring now to FIG. 1, a schematic illustration of an engine system 10 is shown. An engine 100 includes 6 cylinders 1-6. Other numbers of cylinders may be used, but 4 or 6 cylinders are shown here for description. The cylinders 1-6 receive the intake gases consisting of combustible gases such as air or air mixed with exhaust gas (exhaust gas recirculation "EGR") from the intake manifold 103. One or more intake manifold sensors 173 may monitor the pressure, flow rate, oxygen content, exhaust gas content, or other characteristics of the inducted fluid. The intake manifold 103 is connected to an intake port 133 in the engine block to distribute intake fluid to the cylinders 1- 6. In a diesel engine, the intake manifold 103 has a vacuum unless the intake manifold is boosted. Zas is advantageous because the cylinder can be closed. High fuel efficiency is achieved by not pulling the piston down against the manifold vacuum. With the cylinder deactivated, crankshaft 101 has less resistance from the piston and the crankshaft may transmit more torque from the igniting cylinders.Fuel is injected into individual cylinders by a fuel injection controller 300. The fuel injection controller 300 may adjust the amount and timing of the injected fuel into each cylinder and stop and resume fuel injection for each cylinder. Fuel injection into each cylinder 1- 6 may be identical or unique for each cylinder 106 such that one cylinder receives more fuel than another and one cylinder may not receive fuel injection while other fuel is receiving.A user input sensor 900 may be connected to the engine system 10 to detect user inputs such as, but not limited to, braking, accelerating, cranking mode selection, disabling mode selection, accessory activation. The user selection may impact the load requirements on the engine system 10, and the power settings of the cylinders 1- 6 may be adjusted in response to the user selection. Valve timing via VVS controller 200 and fuel injection via fuel controller 300 may be tuned based on the user selection detected by user input sensor 900. If the thermal management program is pre-programmed and real-time temperature detection is not required for all operating conditions, it is possible to introduce certain thermal management engine cycle patterns based on user input or other sensor-sensed data points other than the thermal sensor. For example, if a certain load is imposed on the engine 100, it is possible to preprogram that the temperature of the exhaust gases will be too hot or too cold and make changes to the operating modes without actual thermal feedback.A variable valve timing (VVS) controller 200 is also connected to cylinders 1-6 to actuate intake valves 130 and exhaust valves 150. The VVS controller 200 may vary the actuation of the intake valves 130 and exhaust valves 150 such that the valves are opened or closed normally, too early, too late, or differently, such as during negative valve overlap or adjustment of the operation of the valves. VVS controller 200 may cooperate with a valve actuator 185, such as a hydraulic, electric, or electric coil system, to control intake and exhaust valves 130 and 150. The valve actuators 185 for each cylinder 1- 6 may be identical for all cylinders 106, whereby each valve of each cylinder may switch between combustion mode, deactivation mode, reverse intake mode, or re-intake mode. Or, the valve actuator 185 may be different for intake valves 130 and exhaust valves 150, such that certain functions are possible only for one or the other of these valves. Or in accordance with discussions below, the functions may be distributed such that some valves may switch back and forth between combustion mode and deactivation mode while others may switch back and forth between combustion mode and suck back mode or suck back mode. And if more than one intake valve or more than one exhaust valve are used per cylinder 106, the valve actuators 185 may be identical or different for each of these valves.In later figures, air chambers may be added to further tune a distribution of gases in the intake manifold 103 and the exhaust manifold 105. The need for and placement of intake manifold sensors 173 and exhaust manifold sensors 175 may depend on the use and placement of air chambers and the placement of cylinders equipped to implement a ZAS mode, re-intake mode, or back-intake mode. The mode selected for a cylinder affects the heat output of that cylinder, so that air chambers and associated sensors may be arranged to detect and direct particular heat outputs along exhaust circuits designed for the selected modes of the engine. That is, the illustrated arrangements are merely examples and other circuits may be used.The engine 100 may have cams or may be cam-free, or a hybrid "cam-free AC.". That is, the intake valves 130 and exhaust valves 150 may be connected to either a cam system for actuation, such as camshafts 181, 182 in the example of FIG. 3A, a hydraulic rail, a latched rocker arm, another rocker arm, a shift drum follower, a retarded capsule, an electric actuator, a hydraulic actuator, an electro-hydraulic actuator, etc. Other functions such as engine brake and hydraulic tappet adjustment may be added. It is possible to use a rocker lost motion capsule with retraction for modular design of HLA and brakes. Other designs may include HLA and engine brake in a cam or camless engine.Alternatively to illustration, a camless direct acting mechanism may selectively actuate individual valves to open or close the valves.The crankshaft 101 may be connected to transfer energy between the crankshaft 101 and the camshafts 181, 182, such as with a torque-transmitting mechanism 115 that may include transmissions, belts, or other transfer mechanisms. While FIGS. 3B and 3C show an intake valve 130 and an exhaust valve 150, respectively, it is also possible to have two intake valves 130 and two exhaust valves 150 for each cylinder, as in FIG. 3A. The engine block 102 has been removed for the example in FIG. 3A for clarity and the cylinders are shown in dashed lines.A diesel engine functions by compressing an intake fluid into a cylinder 1-4 by means of a piston 160. Once the intake fluid has moved from the intake manifold 103 to the cylinder, it may be referred to as "charge", and as the charge moves from the cylinder to the exhaust manifold 105, it may be referred to as exhaust gas.In a combustion mode, fuel is injected via fuel injector 310. The high heat and compression ignites the fuel and combustion forces push the piston from top dead center (TDC) shown in FIG. 3B to bottom dead center (BDC) shown in FIG. 3C. Torque Y is directed toward the crankshaft 101 for output to an associated flywheel. In diesel engines, this is referred to as "compression ignition.". For combustion in a gasoline engine, a spark plug is included to ignite the gasoline. That is, to adapt this disclosure to gasoline engines, an additional spark plug controller and control algorithms would be added to control the timing of an included spark plug.Diesel operation may be referred to as "4 stroke", although other modes of operation such as 2 stroke, 6 stroke, and 8 stroke are also possible and known in the art. On the 4 stroke, the piston moves from TDC to BDC to fill the cylinder with intake fluid (stroke 1). The beginning of the cycle is shown in FIGS. 3B and 5A, and FIG. 3C shows the end of stroke 1 when the cylinder is filled with intake fluid. The piston moves up back to TDC (stroke 2). Fuel is injected and ignites to push the piston 160 to BDC (stroke 3). The piston lifts back to TDC to expel the exhaust gas through the exhaust valve (stroke 4). Intake valve 130 is open during lift 1 and closed during strokes 2- 4, although VVS 200 may adjust the stroke for opening and closing. Exhaust valve 150 is open during lift 4 and closed during lifts 2- 4, although VVS 200 may adjust the stroke to open and close. Compression occurs on the second stroke and combustion occurs on the third stroke. 6-stroke and 8-stroke methods include further aspects of compression and injection after closing the intake valve and before opening the exhaust valve. The application describes 4-stroke combustion methods in detail, however, 4-stroke combustion methods may be compatibly applied to extend to prior art 6-stroke combustion methods and 8-stroke combustion methods. 2-stroke engine braking methods may be used along with 2-, 4-, 6- or 8-stroke combustion methods.Exhaust gases exit cylinders through exhaust ports 155 in engine block 102. Exhaust ports 155 communicate with an exhaust manifold 105. An exhaust manifold sensor 175 may monitor the pressure, flow rate, oxygen content, nitric oxide or nitrous oxide (NOx) content, sulfur content, other pollutant levels, or other characteristics of the exhaust gas. Exhaust may drive a turbine 510 of a turbocharger 501, which may be a variable turbine geometry supercharger (VTG) or other turbocharger. Turbocharger 501 may be controlled via turbocharger controller 500 to adjust a connection 514 between turbine 510 and compressor 512. The turbocharger 501 may be adapted to control the intake or exhaust flow rate or the back pressure in the exhaust gas. A controllable valve 516 may be added to route stroke and amount of fluid to turbine 510 and catalyst 800 or to an optional EGR cooler 455 and EGR circuit that recirculates exhaust gases from the cylinder to the intake manifold for recirculation of exhaust gases.Exhaust may be filtered in an aftertreatment system comprising catalyst 800. At least one exhaust sensor 807 is placed in the aftertreatment system to measure exhaust conditions such as tailpipe emissions, NOxcontent, exhaust temperature, flow rate, etc. A catalyst sensor 809 may be added to monitor certain aspects of the temperature and content of the catalyst 800. Exhaust sensor 807 and catalyst sensor 809 may include more than one type of sensor, such as chemical, thermal, optical, resistive, velocity or pressure sensors, etc. A sensor connected to turbocharger 501 may also be added to detect turbine and compressor operation.Exhaust gases may exit the system after being filtered by the at least one catalyst 800. Or, exhaust gas may be recirculated to the intake manifold 103. An EGR controller 400 adjusts an EGR valve 410 to selectively control the amount of EGR provided to the intake manifold 103. EGR controller 400 may be connected to control valve 516, or intake assist controller 600 may be connected to control valve 516. The exhaust gas recirculated to the manifold 103 affects in-cylinder air-fuel ratio (LCV). Exhaust gas dilutes the oxygen content in the manifold 103. Unburned fuel from the fuel meter or unburned fuel remaining after combustion increases the amount of fuel in the LKV. Soot and other fines and pollutant gases also reduce the air-fuel ratio content. While fresh air introduced by intake system 700 may increase LCV, EGR may decrease LCV, and fuel injection to cylinders may further decrease LCV. Therefore, EGR controller 400, fuel injection controller 300 and intake assist controller 600 may adjust the air-fuel ratio for the engine operating conditions by respectively operating valve 516, EGR valve 410, fuel injector 310, and intake assist device 610. That is, an air-fuel ratio adjustment for an igniting cylinder may include delivering fresh air from the intake system 700 for the at least one igniting cylinder boosting cylinder by controlling an air-intake accessory 601 such as a compressor and / or lowering the air-fuel ratio for an igniting cylinder by boosting with exhaust gas recirculation for the igniting cylinder. A charge air cooler 650 may optionally be added to regulate intake flow temperature. This can be done with or without expansion by a turbocharger 501. Numerous alternative arrangements are possible for controlling the air-fuel ratio and further subordinate linkages and linkages of exhaust gas recirculation, turbo-charge and compressor are possible.Further, termination of fuel injection into one or more cylinders 1-6 adjusts the air-fuel ratio of exhaust gases, and deactivation of a cylinder decreases the amount of exhaust gas. Cylinder deactivation affects the ability to drive turbine 510 to operate compressor 512. The implementation of engine braking, re-intake, and reverse intake also affects the amount and composition of exhaust gases.A computer control network is outlined in FIG. 2 and is connected to fuel injectors 310 of the fuel injection system and valve actuators 185 for the respective intake valves and respective exhaust valves. If present, the computer control system is coupled to optional EGR valve 410, variable turbine geometry supercharger 510, and intake accessory 601. The network may include a bus for collecting data from various sensors, such as crankshaft sensor 107, intake manifold sensor 173, exhaust manifold sensor 175, exhaust sensor 807, catalyst sensor 809, user input sensor 900, etc. The sensors may be used for real-time adjustments to the fuel injection timing and amount and the valve opening and closing timing. Additional functions may be preprogrammed and stored in storage device 1401. The additional functions may include preprogrammed thresholds, tables, and other comparison and calculation structures for determining the power setting of the cylinders, duration of the power setting, and number and distribution of cylinders at particular power settings. For example, a detected vehicle crank selection, accessory selection, gear selection, load selection, or other sensor feedback may indicate that an exhaust temperature is or will be too low. In addition to temperature thresholds for entry and exit from thermal management strategies, the application of load thresholds is also possible. Load thresholds are particularly useful for determining aspects of power setting as outlined below, although it is possible to provide real-time computations using computer controller 1400.Storage device 1401 is a tangible read only memory structure such as RAM, EPROM, mass storage device, removable media drive, DRAM, hard disk drive, etc. Signals themselves are not included. The algorithms required to execute the methods disclosed herein are stored in the storage device 1401 for execution by processor 1403. When an optional variable turbine geometry supercharger is implemented, the VTG controller 1415 is transferred from the memory 1401 to the processor for execution and the computer control system acts as a turbocharger controller. Similarly, the computer control system 1400 implements stored algorithms for EGR control 1414 to implement an EGR control device 400; implements stored algorithms for intake assist control 1416 to implement an intake assist control device 600; and implements stored algorithms for fuel injection control 1413 to implement a fuel injection control device 300. When implementing stored algorithms for VVS controller 1412, various intake valve, controller, and exhaust valve, controller strategies are possible with respect to valve timing and valve lift strategies as set forth elsewhere in this application, and these strategies may be implemented by VVS controller 200. The processor may combine outputs from the various controllers with one another, for example, the processor may include additional functions to process outputs from the VTG controller 500 and intake assist controller 600 to determine a command for valve 516. A controller network (CAN) may be coupled to suitable actuation mechanisms to implement the instructions of processor 1403 and various controllers.While the computer control system 1400 is shown as a central component with a single processor, the computer control system 1400 may be distributed to include multiple processors or allocation programming to distribute the processor 1403. Or a distributed computer network may place a computer structure near one or more of the controlled structures. The distributed computer network may communicate with a centralized computer control system or may network between distributed computer structures. For example, one computer structure may be proximate turbocharger 501 for VTG controller 500, another computer structure may be proximate EGR valve 410 for EGR controller 400, another computer structure may be proximate intake and exhaust valves for variable valve actuators 200, another computer controller may be placed for fuel injection controller 300, and yet another computer controller may be implemented for intake assist controller 600. Subroutines may be stored in distributed computer structures with centralized or kernel processing performed in computer control system 1400.The computer network includes the processor 1403, at least one tangible storage device 1401, and processor-executable control algorithms for implementing the methods disclosed herein stored in the storage device 1401 and executable by the processor 1403. The stored processor-executable control algorithms implement the disclosed methods.Cylinder DeactivationDiesel cylinder deactivation (ZAS) differs in many ways from gasoline cylinder deactivation. For gasoline, a cylinder may be deactivated for extended periods of time. However, because of the O2sensor that regulates fuel, a gasoline engine has difficulty managing the use of both fresh air and exhaust gas flows. There are several cycle options for diesel because combustion can occur at a wider range of air-fuel ratios.Cylinder deactivation is defined as intake valve deactivation, exhaust valve deactivation, and fuel injection into a cylinder. This is different from a "cylinder cut" which merely shuts off fuel injection, but the valves can continue to move.Closing of the intake valves 130 and exhaust valves 150 prevents fluid flow through the cylinder, prevents loss of resources allocated to other active cylinders through the cylinder, and prevents loss of energy to activate the valves. However, frictional losses and shrinkage continue to occur. Therefore, it is advantageous to use the cylinders from time to time to recharge the pressure in the cylinders to affect the oil that lubricates the cylinders back to the oil pan. Otherwise, the oil contaminates the engine. Further benefits are obtained, such as air flow control and temperature control.This leads to strategies to adjust the fuel ratio at each cylinder during power-on and power-off. While ZAS may be entered and exited (or electronically switched) again within a piston revolution, it is an on-demand system. However, the air boost and pressure in the manifold decreases to a different degree and is less on-demand. Fuel delivery must therefore be adjusted to redirect injection pressures to individual cylinders.The utilization of the following strategies may vary depending on the power requirement of the engine. Decision trees can help decide how long ASS is maintained and decide which methods are used to extend ASS to various loads and engine speeds.FIG. 5A depicts power demand over time for presenting an intake valve 130, a fuel injection 310, and an exhaust valve 150 to one of cylinders 1- 6. A corresponding piston 160 reciprocates within a corresponding cylinder 1- 6 from top dead center (TDC) to bottom dead center (BDC). FIG. 5A simplifies the question of whether variable valve actuation is used (LIVO, LIVC, etc.) and repeats the same valve lift and fuel injection pattern for each cylinder cycle. Intersections between valve openings and closings are not shown, but in practice the inlet valve may already open while the outlet valve is still closing. Variations for contrasting methods for "swirling", "cylinder wetting", "foaming", "scavenging", etc. are not shown, but such methods may be used as well as other combustion methods.From time zero T0 to time T1, the cylinder completes a 4-stroke cycle. The timeline begins where the piston of that cylinder is near TDC after an exhaust stroke. The piston position is shown superimposed by dashed lines to show the piston position in relation to the power demand. Stroke 1 moves the piston from TDC to BDC while the intake valve opens to feed intake gases. In some cases, the piston may already begin its travel back to TDC before the intake valve 130 has fully closed, but stroke 2 is a compression stroke because the piston pushes up against a closed intake valve 130 and a closed exhaust valve 150. Fuel injection occurs at or near TDC. If the fuel is diesel, the thermodynamics of compression ignite the fuel and the piston 160 moves from TDC to BDC in stroke 3, also called power stroke. The power of the fuel is converted into torque by energy transfer from the piston 160 to the crankshaft 101. The exhaust valve may begin opening at or near BDC of stroke 3. As the piston returns to TDC, the contents of the cylinder escapes past the exhaust valve 150.In-cylinder Exhaust Gas RecirculationOne strategy uses cylinder deactivation to detect hot charge to allow exhaust gas recirculation in the cylinder. The exhaust valve is opened during a stroke S 1 of a preceding stroke to exhaust the cylinder. Then, the intake valve is opened to receive intake gases in stroke S 1. Fuel is injected near the apex between Stroke 2 and Stroke 3, after which the fuel is burned. The power stroke S 3 transfers energy to the crankshaft 101. The exhaust valve is deactivated and the charge is not released in stroke S 4. The piston continues to reciprocate. This can be seen in FIG. 5B.Such a mode is useful when the engine is in a very low power state. If the torsional shocks can be taken into account, the mode can be used for higher power levels.This method releases exhaust gases, but no fresh air is forced through the engine. This is more useful during a warm-up mode for increasing cylinder temperatures and ultimately exhaust temperatures than if a ZAS mode were used to heat an aftertreatment system. Utilizing in-cylinder EGR in this manner ensures that all fuel is burned, heats the engine block, makes subsequent combustions more effective, and exhausts high temperature exhaust towards post-treatment for more effective detection of pollution. The in-cylinder EGR mode may be ended when no further heating of the cylinder is required, for example when a cylinder temperature threshold has been reached. This strategy is also useful when fresh air is not desired in the EGR circuit, such as in low LCV operating ranges. Preventing fresh air flow during the ASS mode, as by this hot charge sensing, is advantageous in avoiding dilution of the EGR circuit. The content of the EGR exhaust stream may be maintained to a desired pollutant level to allow detection of certain fines for their combustion, or for effective cylinder operation, such as by tuning the LCV. By properly controlling the fuel level injected into the cylinder, no excess fuel may be produced and no oxygen may remain in resulting exhaust gases from the deactivated cylinders.FIG. 5B shows a method for transitioning from the 4-stroke mode shown in FIG. 5A to an in-cylinder EGR mode ZAS. FIG. 5C shows a method for transitioning to an in-cylinder EGR maintained ASS mode to an 8 stroke mode. In both FIGS. 5B and 5C, the intake valve opens during lift S 1 and fuel is injected as part of lift S 2. Power stroke S3 is followed by stroke S4 during which no exhaust valves are open. In FIG. 5B, intake valve actuation, fuel injection, or exhaust valve actuation is not accordingly performed in lift S 5-S 8 because the cylinder is in deactivation mode. All remaining oxygen or fuel may be consumed from BDC to TDC via combustion ignition on the peak of the subsequent compression strokes, such as near the peaks of strokes S 6, S 8, etc.The exhaust gases corresponding to FIG. 5B are quite hot when exhausted due to multiple compression strokes. In an electronically actuated valve system, the exhaust valve may be opened during straight strokes, such as stroke S 6, S 8, S 10, S 12, etc. In a cam actuated system, it is convenient to use a single cam profile and a single cam rail for the exhaust valve, and so it is convenient to open the exhaust valve at strokes S 8, S 12 or S 16. Allowing an additional compression stroke on the burnt gases heats the cylinder log of the engine 100 and heats the exhaust gas. A timing of the release of the re-compressed exhaust gas becomes part of the thermal management strategies outlined here. The timed release acts on the level of particulate matter in the exhaust manifold to regulate the air-fuel ratio available in the system.Referring to FIG. 5C, in-cylinder EGR is combined with ZAS mode and additional in-cylinder EGR. Stroke S 1 includes intake gas injection, stroke S 2 compressed, fuel injector 310 injects fuel, and power stroke S 3 transmits power to the crankshaft. However, stroke S 4 does not include opening the exhaust valve. Instead, the hot charge is trapped in the cylinder. A full cycle of a cylinder deactivation mode is traversed in strokes 5-8, and the intake valve remains closed for piston stroke S9. The exhaust gases increase heat due to additional compression. Additional fuel injection includes a portion of compression stroke S 10. The amount of fuel injected may be adjusted based on the first cycle to consume all remaining oxygen. The total consumption of oxygen in the cylinder is useful for the control of the NOx pollutant level. When there is no or little oxygen, there is no oxygen to form NOx.Further in-cylinder EGR heats the charge and cylinder even more. Additional compression strokes consume remaining fuel and oxygen and provide heat. When the exhaust valve is opened, the heat of the exhaust gases is quite large. The exhaust valve 150 may be opened in straight strokes by an electrically or hydraulically actuated valvetrain, or strokes S 12 or S 16 or similar strokes in a cam actuated valvetrain.FIGS. 5A-5G utilize a timeline divided into 4-stroke blocks to facilitate comparisons between methods, but not to limit applicability to 4-stroke methods. It is possible to implement any 4-stroke, 6-stroke, 8-stroke method, or combination thereof, such that the firing cylinders follow one method while deactivated cylinders follow another method. The aforementioned variable valve timing (VVS) method can likewise be combined with it in order to open or close the valves normally, early or late, or combinations thereof.To implement the strategy of FIG. 5C, a lean LCV is housed within the cylinder so that a second combustion event may occur without opening the intake or exhaust valves. For example, a first combustion at the top of stroke 2 may include an LCV of 50:1 such that there is an excess of oxygen. Tuning of the LKV can be achieved by methods and additional circulation methods below.Limiting the low load or idle operation is also an option to implement the strategy of FIGS. 5B and 5C, as there is more flexibility in tuning the LKV at low load or idle mode of operation.One aspect of these strategies is improving fuel efficiency in the remaining igniting cylinders. By disabling some of the cylinders 1- 6 using this method, it is possible to increase the fuel injected into each of the remaining igniting cylinders in accordance with desired torque output. The efficiency of these igniting cylinders is increased, which in turn increases the heat output, which in turn increases the efficiency of the post-treatment. A higher turbine outlet temperature (TAT) is achievable, so that less fouling escapes from the tail pipe. Cylinder deactivation also decreases the amount of exhaust gas, but does not pump fresh air into the exhaust gas during the deactivation mode. This enables stagnation of hot exhaust gases in the post-treatment.As an alternative to shutting down a cylinder to reduce fresh air in exhaust gases, it is possible to increase the flow rate and volume for other reasons such as starting a turbocharger. This would entail disabling fuel injection while the cylinder's intake valve and exhaust valve continue to be opened and closed. Or, the initiation of a turbocharger may be accomplished by controlling the stroke of termination of the ZAS mode for a cylinder such that re-compressed charge fluid is expelled at a time when turbine 510 requires additional volume for operation of compressor 512.Other in-cylinder EGR methods are available. If the engine is running too lean, it is possible to route exhaust gas from the exhaust manifold to the intake manifold. One strategy utilizes reverse aspiration. The other strategy utilizes re-aspiration.Suck BackwardWhen the engine is running lean, such as at idle, the LCV may be between 50:1 and 100:1. This is different from rich modes where the LKV may be 140:1 or 150:1. A high LKV has a high oxygen content that has a high potential for forming NOx. However, in some high load conditions or on expressway driving, a high air flow through the engine occurs to meet the power demand. At low load or low engine speeds, it is possible to direct exhaust gases from the exhaust manifold through the intake manifold by means of reverse induction. Reverse induction may be used to improve TAT (turbine output temperature) and BWW (brake thermal efficiency).Backward induction assists lowering of the ACV by enriching the intake gas with exhaust gas. The exhaust gas contains some fuel and chemicals that dilute the combustible intake gas. The exhaust gas re-compressed in this manner is very hot, which increases the post-treatment temperature. The combustion results may be similar or better than conventional EGR that direct exhaust gas from the exhaust side to the intake side through an external circuit outside the engine 100. In the backward suction, the exhaust gas is sucked through the engine valves. This backward induction method reduces utilization of or eliminates the need for the external EGR circuit and improves the heat retention performance on the engine block.In one aspect, recirculation without external EGR circulation may be utilized during warm-up modes, such as cranking or DPF regeneration, where it is useful to retain heat in the engine block. Once the engine block has been heated to an effective temperature, the external EGR circuit may be utilized to drive the turbine for an expressway drive mode. Or, the external EGR loop may be utilized when the ignition mode is needed for all cylinders to achieve the engine power demand, and in-cylinder EGR methods may be utilized at power settings low enough to allow the disclosed methods. Hybrid use of both reverse intake, in-cylinder EGR, and external EGR may be used to adjust fouling management.In another aspect, cylinder deactivation improves low load and idle fuel economy by reducing losses associated with otherwise low usage of cylinders. By utilizing an AS mode in selected cylinders, the firing cylinders either receive more fuel or their air-fuel ratio (LKV) decreases to compensate for the lack of torque from the AS cylinders. A ZAS mode may be combined with back-suction to allow re-compression of exhaust gas prior to exhaust into the intake manifold 103. Or, combustion may be performed by fuel injection. This can be seen by comparing FIGS. 5E and 5F.To lower the LKV for effective high temperature combustion, a reverse intake mode is used to draw exhaust gas from the exhaust manifold 105 back to the intake manifold 103. In FIGS. 5D and 6A, cylinder 1 is actually a 2-stroke EGR pump. Intake gas enters intake manifold 103, but the closing and opening of intake valve 130 and exhaust valve 150 for cylinder 1 is timed to draw exhaust gas from exhaust manifold 105 to intake manifold 103. In-cylinder EGR lowers fresh air in intake manifold 103, resulting in lower LCV in igniting cylinders ( 4, 5, and 6). In FIG. 6A, cylinders 2 and 3 are in ZAS mode and no fluid is directed from the intake manifold 103 into the exhaust manifold 105 through cylinders 2 and 3.The number and position of an intake manifold opening 132 may be selected to tune the flow pattern of intake gases into the intake manifold 103. Similarly, a number and position of exhaust ports 155, 156 may be adjusted to direct the collection and redistribution of exhaust gas. For example, intake manifold opening 132 may be mounted above cylinder 1 so that convective forces may direct the distribution of hot and cold gases. Very hot back-drawn gases can mix with colder suction gases. Cylinders 2 and 3 in the ZAS mode may be near the reverse intake cylinder 1 to allow cross-flow across the intake manifold 103 or prevent hot reverse intake gas from being drawn downward. A large delta may allow for homogeneous mixing, or may be used to allow heat stagnation at an end of the intake manifold 103.More than one exhaust manifold opening 157, 156 may tune backpressure or may allow, among other things, certain routes for exhaust gas from igniting cylinders versus cylinders in the ASS mode. For example, as closer to cylinders in the ASS mode, exhaust manifold opening 157 may be connected to the external EGR circuit such that these gases are directed to optional EGR cooler 455 in FIG. 1, bypassing turbine 510 and bypassing catalyst 800 to avoid dilution of the particulate matter content of the exhaust stream. Or, with one or more computer controllable valves 1570 in exhaust manifold port 157, the very hot gas from the cylinders may be directed to catalyst 800 in the ZAS mode to heat it. Further, adjustment of valve 1570 in exhaust manifold opening 157 or adjustment of another downstream device may result in backpressure to enable recirculation. In another alternative, valve 1570 may be controlled and exhaust manifold pressure 105 or 1051 may be regulated to purge exhaust gases from the inlet of turbocharger 501 or to purge or exhaust other downstream device.Similarly, exhaust manifold opening 156 may include one or more computer controllable valves 1560 to direct exhaust gas via manifold 105 into an external EGR circuit to provide a particular backpressure to manifold 105, heat catalyst 800, or control the LCV.FIG. 6B provides an alternative divided into exhaust manifolds 1051 comprising a first exhaust plenum 152 and a second exhaust plenum 154. Including a partition 159 in exhaust manifold 1051 that separates exhaust gas from igniting cylinders 4-6 from high temperature gas from cylinders in the ZAS mode. A pressure difference may be maintained between the exhaust air chambers 152, 154. Or, controlled leakage may be permitted between the exhaust air chambers 152, 154. The heat in the first exhaust air chamber 152 may promote the backward intake into cylinder 1 and allow better control of the LKV of the backward intake gas. A computer controllable valve 158 may allow cross-flow between the exhaust plenum 152, 154. In some arrangements, it is advantageous to include additional baffles or additional manifolds. For example, an additional partition in a first exhaust plenum 152 could establish a separation between cylinder 1 and cylinders 2 and 3 to limit flow therebetween. Exhaust manifold 1051, or an additional manifold, could be configured to combine the exhaust gases from cylinders 1, 2, and 3 at a strategic location downstream of exhaust port 155 before reaching EGR cooler 455 or valve 516.Referring to FIG. 6C, two intake manifold openings 132, 134 are used to adjust flow patterns and pressures within the intake manifold 103. Intake manifold ports 132, 134 are located above cylinders 2, 5 selected for reverse intake. EGR charges are carried by cylinders 2, 5. Due to the manner in which heat and intake gases are distributed in the intake manifold 103, the combustion heat from cylinders 3, 4 may be higher than the combustion heat from cylinders 1, 6. The exhaust manifold may be equipped with or without a center baffle 159 and valves 158, 1570, 1560.The valve train would be very complex to offer both ZAS mode and either re-intake or reverse intake for all cylinders, and so one solution is to assign cylinder 1 to either the normal ignition mode or the re-intake mode or the reverse intake mode. The remaining cylinders may switch between other modes, such as normal firing mode, AS mode, or AS mode with other functions. Or halves or other parts of the engine may be associated such that some cylinders are configured to switch between spark and re-intake or reverse intake modes and other cylinders may be configured to switch between spark mode, ASS mode and possibly another mode such as engine braking.If only re-intake or backward intake is assigned to at least one cylinder, it is possible to omit an external EGR circuit. The associated cylinder may perform a required pumping of EGR gas to the intake manifold 103.FIGS. 5D and 6A illustrate backward suction associated with valve opening profiles and piston paths. A 2-stroke method is applied to cylinder 1. Cylinders 2 and 3 may follow either of FIGS. 5B or 5C for in-cylinder EGR or may be fully deactivated (no fuel injection, no intake valve or exhaust valve action) in ZAS mode. And cylinders 4- 6 may follow FIG. 5A for 4-stroke combustion. In cylinder 1, each stroke of piston 160 draws gas from exhaust manifold 105 or 1051 (air chamber 152). Each upward stroke forces this exhaust gas into the intake manifold 103.An alternative shown in Fig. 5E interleaves a compression stroke to heat the backward sucked gas. The down stroke of piston 160 from TDC to BDC draws exhaust gas at strokes 1, 5, 9, and 13 with exhaust valve 150 open. The upward stroke of piston 160, from BDC to TDC, forces compressed exhaust out of the cylinder at strokes 4, 8, 12 and 16. The compression strokes 2, 6, 10, and 14 allow compression ignition or combustion of fuel and oxygen remaining in the exhaust gas. The low LKV back-drawn gas is introduced into the intake manifold to decrease the oxygen content of the intake manifold. This is useful for pollution and thermal management.In FIG. 5F, fuel injection is performed. Compression strokes 2, 6, 10, and 14 peak in fuel injection and a subsequent power stroke contributes to the output of the engine. The hot charge is expelled on the strokes 4, 8, 12 and 16 through inlet valve 130.Referring again to FIGS. 6A and 6B, reducing the number of firing cylinders to three firing cylinders decreases the air-fuel ratio for any speed and load. Therefore, it is possible to increase the fuel injected into the igniting cylinder to increase the torque output therefrom, thereby also increasing the heat and fuel efficiency of these cylinders. Operation of cylinder 1 as an associated cylinder that is aspirated from exhaust manifold 105, 1051 may deliver the same amount of exhaust gas to intake manifold 103 as expelled by two igniting cylinders in the 4-stroke mode.Re-AspirationRe-intake and reverse intake assist in lowering LCV by enriching the charge air in the cylinder with exhaust gas. Many of the advantages of thermal and pollution management correspond to the re-aspiration discussion below from the reverse aspiration discussion above. For example, both methods are advantageous for increasing the heat of the exhaust gas and may be used at engine speeds where there is not enough gas to start a turbocharger 501, and both methods may be used to recharge cylinders in ASS mode or igniting cylinders.Back-priming entails a reversal of flow from the exhaust manifold 105, 1051 to the intake manifold 103. However, re-intake is not intended to adjust the intake manifold 103 by pushing exhaust gas from the exhaust manifold to the intake manifold. Instead, re-intake draws exhaust gas into the cylinder for re-use of the exhaust gas in the cylinder without opening the intake valve 130 of that cylinder. This type of in-cylinder EGR may also avoid the transport of EGR gas by routing an external EGR circuit. Or this type of in-cylinder EGR may be utilized when the flow rate is not sufficient for use of the external EGR circuit.In-cylinder EGR in the suck back mode consumes the fuel and oxygen remaining in the exhaust gas. In a first method shown in FIGS. 5G and 7A, cylinders 2 and 5 re-draw exhaust gas by opening the exhaust valve during a piston down stroke shown at strokes 1, 5, 9, and 13. In FIG. 5G, a compression stroke is followed by a power stroke. The air spring effect gives a part of the force of compression back to the crankshaft. In strokes 4, 8, 12 and 16, the exhaust valve is again opened to release the charge to the exhaust manifold.In a second method shown in FIG. 5H, cylinders 2 and 5 transition from an ignition mode in FIG. 5A to stroke 1 by opening the exhaust valve. Fuel injection then occurs near the apex between strokes 2 and 3. the exhaust valve is held open for the duration of strokes 4 and 5 such that upward movement of the piston forces out the exhaust charge and then downward movement of the piston draws exhaust gas back out of the exhaust manifold. The exhaust valve long duration opening method may be used with or without fuel injection, but is shown only once here for brevity. Also, the last opening of the exhaust valve of an ignition mode may be maintained open until the start of the re-intake procedure.Re-induction improves TAT (turbine output temperature) and improves BWW (brake thermal efficiency). For example, in a two-cylinder re-intake setting at 1200 rpm and 50 ft·lb torque output setting, the LKV may decrease by about 40%, the TAT may increase by about 20%, and the BWW may increase by about 5%. Suck back further improves both TAT and BWW, some results of the suck back give a TAT of over 250° C., which is close to an ideal post-treatment temperature of the catalyst base layer. For example, in a two-cylinder setting at backward intake at 1200 RPM and 50 ft·lb torque output setting, the LKV may decrease by about 70%, the TAT may increase by about 53%, and the BWW may increase by about 14%. Further results are seen in FIG. 8, where the turbine output temperature (TAT) in degrees Celsius is compared to the brake specific fuel consumption (BSCV) in grams per kilowatts hour.The use of two cylinders in the re-intake mode and fuel injection F as in FIG. 5H results in great improvements in BSCV compared to the normal operating mode of FIG. 5A. However, using two cylinders in the reverse intake mode and fuel injection F of FIG. 5F yields a similar BSCV, but a higher TAT. Therefore, based on the goals of thermal management, it is possible to choose between the two in-cylinder EGR modes.Similarly, in the non-fuel injected NF re-intake mode of FIG. 5G, two cylinders have a slightly poorer BSCV and a higher TAT than the fueled scenario of FIG. 5F. However, a two-cylinder reverse intake without fuel injection NF as shown in FIG. 5E has the highest TAT values and the lowest BSCV values in this example. This mode may be selected for best fuel economy and maximum catalyst heating capability. However, if the catalyst is already quite hot, it is possible to select one of the in-cylinder EGR modes with lower TAT to conserve fuel or control the oxygen or particulate matter content for a next firing sequence or piston cycle.Thus, selection of a re-intake mode with a fuel injection cylinder F has the lowest TAT, but still exceeds the BSCV in the normal operating mode. The one-cylinder-in-reverse intake mode exceeds the one-cylinder-in-reverse intake mode in terms of BSKV and TAT. The 2-cylinder modes exceed both 1-cylinder modes, but one of the 1-cylinder modes may be selected when 5 cylinders are needed to meet the power demand to provide performance improvements to the system.Usually, valves are designed for unidirectional flow. It is possible to remodel valves for reverse intake methods and re-intake methods to optimize them for gas flow from the exhaust manifold to the intake manifold. It has been found that the design of the valves for one-way flow - from inlet to outlet - and subsequent use of the same valves in a reverse suction mode or re-suction mode is better for the final combustion results. With this valve design, there is better backpressure and this limits the gas drawn by the reverse intake cylinders and the re-intake cylinders as compared to gas drawn by the normal operation cylinders.Therefore, the intake valves associated with the backward or re-intake are further optimized for the fluid flow from the intake manifold 103 to the exhaust manifold 105, 1051. This supports combustion when these cylinders are in the ignition mode or consume fuel or oxygen in in-cylinder EGR modes. With intake valves 130 closed, EGR charge is drawn through exhaust valves 150 into one or more in-cylinder EGR cylinders.The exhaust valve head and associated opening at the top of the cylinder are smaller than the intake valve head and associated opening at the top of the cylinder. The intake valve opening is designed larger for a higher flow rate and draws in more intake gases for combustion. In in-cylinder EGR modes, the small size of the exhaust port is advantageous because it limits the amount of EGR that occurs via this process. The mixture in the intake manifold 103 is not made too rich. This creates natural EGR throttling and an additional flow restriction mechanism is optional and need not be added in all design scenarios.The EGR charge is expelled through the intake valves 130. The intake valves 130 are designed for intake actions and not for exhaust actions, making the exhaust into the intake manifold 103 inefficient. The intake valves 130 and exhaust valves 150 also differ in hardness and shape. In order to expel from the intake valve 130 to cope with higher temperatures of exhaust gases, it becomes necessary to attach an exhaust valve type valve to the position of the intake valve. This has an effect on the costs of the valve drive, since material with a higher temperature tolerance must be used both for inlet valves 130 and outlet valves 150.This system can be implemented in engines with limited operating time with a system with discrete switches. The limited operating time also bypasses the need for cams and bypasses complex camless systems, although re-intake and reverse intake may be designed and developed for more complex operating modes. A cam system can also be developed for both modes.To embody a discrete switching system, all cylinders may be selected for an individual mode of operation. Therefore, individual cylinder selection is made. A discrete cylinder is selected for in-cylinder EGR mode. One or more other discrete cylinders may be selected for in-cylinder EGR mode. The remaining cylinders are operated normally.FIGS. 7A-7C build upon the air chamber and manifold opening concepts in FIGS. 6A-6C. As in FIGS. 6A-6C, re-intake may be utilized with or without cylinder deactivation mode. FIGS. 6A and 6B utilize reverse intake with ASS mode, and FIGS. 6C-7C depict in-cylinder EGR methods without ASS mode. The representations do not exclude the use of additional or alternative operating modes. In-cylinder EGR methods may be utilized and combined in more cylinders than shown. In FIGS. 7A-7C, cylinders 2 and 5 are selected for discrete switching between normal ignition mode and re-intake. Depending on the valve train design and / or firing order, cylinders 1 and 6, 3 and 4, or 2 and 5 could be paired for re-intake. The selection for pairing may also be applied to rearward suction. Re-intake is not limited to two cylinders, and may be applied to one cylinder, half the cylinders, or other number of cylinders. There are operating modes in which it may be advantageous to utilize one or more in-cylinder EGR modes for all cylinders for one or more firing sequences or for one or more cycles.To make the selection of cylinder pairing less critical, the manifold 1031 may be configured to uniformly distribute intake gas across all cylinders, and the exhaust manifold 1052 may be configured to uniformly diffuse exhaust gas as in FIG. 7A. The intake manifold opening 1321 is centered, the exhaust manifold opening 1561 is centered, and there are no air chamber forming partitions. Otherwise, hot zones develop. Cylinders 3 and 4 are running almost normally because they are so close to the fresh air source, but cylinders 1 and 6 are furthest from the inlet and are close to the re-intake cylinders, so cylinders 1 and 6 become hot faster than other cylinders. Therefore, in this scenario, selection of cylinders 2 and 5 for in-cylinder EGR has a more optimal impact on efficiency than other pairings.Otherwise, it is possible to select cylinders for rearward or re-intake based on the manifold design. By properly selecting the position, it is possible to align the suck back cylinders or re-cylinders at a particularly "rich" position in the manifold, while leaving the igniting cylinders in "lean" areas of the founder. That is, in FIG. 7B, it is possible to add an intake manifold partition 139 to the intake manifold 1032. This forms a first intake air chamber 136 and a second intake air chamber 138. The intake manifold opening 1321 fills both intake air chambers 136, 138. The exhaust manifold 1053 includes first exhaust air chamber 152 and second exhaust air chamber 154 that expel exhaust gas into the exhaust manifold opening 1561. This separation allows the formation of a "motor within a motor.". One half of engine 100 may be deactivated in the cylinder deactivation mode while the other half remains active, and either ignites or operates in any combination of in-cylinder EGR mode, ignition, and other modes. Or, one half of the engine may optimally ignite at a certain LCV and high BWW, while the other half manages fine combustion by reburning exhaust gas. The dual mode engine has much use in pollution and thermal management.In FIG. 7C, the intake manifold ports 132, 134 may be connected to various sources, such as one to a fresh air intake accessory, and the other to an external EGR circuit. Exhaust manifold ports 157, 156 may also be connected to associated circuits for fouling and thermal management processes. Computer controllable valves 137, 158, 1570, 1560, 516 may be used to further adjust flow and allow conversion between split engine operation and firing mode for all cylinders. Valve timing may be part of EGR control (1412) logic in a computer control system 1400, with commands issued by an EGR controller 400.FIG. 9 illustrates the oxygen excess ratio occurring above cylinders 1- 5 when the intake manifold 103 has been configured with an asymmetric intake manifold opening 132 as shown in FIG. 6A. When air enters the intake manifold at one end of the in-line engine, this results in stagnation of flow above cylinder 6, while air above cylinder 1 is quite oxygen-containing. Implementation of the in-cylinder EGR mode shown in FIG. 6C with the intake manifold of FIG. 6A results in non-stoichiometric results. A stoichiometric LCV above each cylinder would not result in excess oxygen above the cylinders. However, applying the method of FIG. 5F to cylinders 2 and 5 and applying the method of FIG. 5A to cylinders 1, 3, 4, and 6 shows that the in-cylinder EGR mode of the reverse intake decreases the oxygen content across cylinders 2 and 5 in non-uniform form. Cylinder 5 is too low, resulting in sooty exhaust. The cylinders in combustion mode have too much oxygen and the NOx output may be very high due to the availability of oxygen to which nitrogen binds.Utilizing the non-fuel injected reverse intake mode NF of FIG. 5E yields an inclined but more homogeneous oxygen profile across the cylinders. This enhances the ability to tune the shape of the air chamber, the placement of the intake ports, and other principles of FIGS. 6A-7C for purposes of controlling the air-fuel ratio in the manifolds 103, 105 and ultimately in the catalyst 800.A control strategy may be developed for entering and exiting normal mode in reverse or re-aspiration. This strategy may include switching from the normal firing mode as shown in FIG. 5A in a method outlined in FIGS. 5B-5G without having to stop the engine. It is also possible to switch between the cylinder cut mode, the backward suction mode and the re-suction mode from cycle to cycle. The cylinders may switch from cycle to cycle between any of the methods outlined in FIGS. 5A-5G. As described above, one cycle may include two or more strokes of the piston within its cylinder, with four strokes per cycle being shown for simplicity for all but FIG. 5D, which illustrates a 2-stroke cycle.Further, in-cylinder EGR methods may be modified among cylinders such that one cylinder of a multi-cylinder engine executes one of the methods while another cylinder of the multi-cylinder engine executes another method. The methods outlined in FIGS. 5A-5G may be combined in various ways such that one or more cylinders utilize one method while one or more other cylinders utilize a second method. Again, one or more other cylinders may utilize a third method, all in the same firing sequence. The firing sequence is the cylinder actuation pattern within the engine. An ignition sequence includes the number of cycles required to utilize each of the cylinders. For example, in some combustion modes, cylinders 1 and 3 may fire in combustion mode, then cylinders 4 and 6, then cylinders 2 and 5.In an air-fuel ratio management method, referring to FIG. 10, a power output request to the engine is detected in step S 101. This can be done, for example, by monitoring the acceleration pressure or an engine load. It is then possible to determine a fuel-saving air-fuel ratio on the basis of the detected power output in step S 103 This can be calculated either in real time or looked up in a stored table, for example. The LCV with the greatest fuel efficiency may be quite lean and may require the in-cylinder EGR mode to dilute the oxygen and increase the heat and severity of the combustion. The selected in-cylinder EGR mode may conform to the principles in FIG. 8. Some in-cylinder EGR modes provide higher heat results, while others provide better fuel consumption results. Trade-offs between these aspects help determine how to achieve a desired temperature, oxygen content, and particulate result. That is, a comparison step may be considered as step S 111.A current air-fuel ratio is detected in step S105 in either an engine-connected intake manifold, an engine-connected exhaust manifold, or both. Furthermore or alternatively, in step S 107, a temperature in the manifolds or in the catalytic converter may be detected as additional data. The temperature data may be used to determine an LKV required for effective catalyst operation in step S 109. Alternatively, the temperature data may be utilized to adjust the temperature or particulate matter content of the intake and exhaust manifolds, as described above with respect to FIGS. 6A-7C.An adjustment of the air-fuel ratio is determined in step S113. This may be done based on the air-fuel ratio determined for the fuel efficiency in step S 103 and based on the detected current air-fuel ratio in step S 105. An in-cylinder exhaust gas recirculation method is selected in step S 115 based on the determined air-fuel ratio adjustment. The in-cylinder exhaust gas recirculation method adjusts an oxygen and particulate matter content of exhaust gas arising as a result of combustion. A number of cylinders of the multi-cylinder engine is selected in step S 117 to implement the in-cylinder exhaust gas recirculation method. The intake valves and the exhaust valves are controlled for the selected number of cylinders to adjust the oxygen and particulate matter content of the exhaust gas by applying a second compression stroke of the respective pistons of the selected number of cylinders to the exhaust gas in step S 119. The second compression stroke is applied because the exhaust gas has already undergone at least one compression stroke to become exhaust gas. Retention in the cylinder for ZAS mode or retraction into the cylinder for reverse intake mode or re-intake mode results in the piston acting on the exhaust gas a second time, whether for combustion, compression or pumping.Another method for temperature management may include detecting a power output request to the engine at step S 101 and detecting a current air-fuel ratio in an intake manifold connected to the engine, an exhaust manifold connected to the engine, or both at step 105. A low temperature condition is detected in one or more of the intake manifold 103, the exhaust manifold 105, or the catalyst 800. Adjustment of an air-fuel ratio by thermal management is determined in step S 109 based on the detected current air-fuel ratio and based on the low temperature state. An in-cylinder exhaust gas recirculation method is selected in step S115 based on the determined air-fuel ratio adjustment by thermomanagement. The in-cylinder exhaust gas recirculation method adjusts a combustion-induced oxygen and particulate matter content of exhaust gas to decrease the air-fuel ratio of available gases for combustion. A number of cylinders of the multi-cylinder engine is selected in step S 117 to implement the in-cylinder exhaust gas recirculation method. The intake valves and the exhaust valves are controlled for the selected number of cylinders to apply a second compression stroke of the respective reciprocating pistons of the selected number of cylinders to the exhaust gas in step S119. The temperature of the exhaust gas is adjusted by reburning the exhaust gas to which a second compression stroke has been applied. A catalyst temperature may be controlled by controlling the exhaust temperature. Instead of manifold temperature, catalyst temperature may be monitored to determine that a low temperature condition exists.The methods disclosed herein may be implemented by a system as outlined in FIG. 1 including a multi-cylinder engine 100, the engine including respective reciprocating pistons 160 in the plurality of cylinders 1- 6, the respective pistons being connected to a crankshaft 101 to rotate the crankshaft. A computer controllable fuel injection system comprising a fuel controller 300 is configured to inject fuel into the plurality of cylinders. Respective computer controllable intake valves and exhaust valves connected to a VVS controller 200 are configured to open and close the plurality of cylinders. A computer control system 1400 is part of a computer control network shown in FIG. 2 for connection to the fuel injection system and corresponding intake valves and corresponding exhaust valves. The system includes a processor 1403, a tangible storage device 1401, and processor-executable control algorithms for implementing the disclosed methods.Those skilled in the art will recognize other implementations by considering the specification and application of the examples disclosed herein.

Claims

A system for air-fuel ratio (ACV) management in a multi-cylinder engine (100), the engine comprising: respective reciprocating pistons (160) in the plurality of cylinders (1-6), the respective reciprocating pistons being connected to a crankshaft (101) for rotating the crankshaft; a computer controllable fuel injection system configured to inject fuel into the plurality of cylinders; respective computer controllable intake valves (130) and exhaust valves (150) for opening and closing the plurality of cylinders; and a computer control network connected to the fuel injection system and the respective intake valves and respective exhaust valves, the network comprising a processor, a tangible storage device (1401) and control algorithms executable by a processor (1403) for implementing an LKV management method, the method comprising: detecting a power output request to the engine (100); determining a fuel saving air-fuel ratio based on the detected power output; detecting a current air-fuel ratio in either an engine connected intake manifold (103), an engine connected exhaust manifold (105), or both; determining an adjustment of an air-fuel ratio based on the determined fuel saving air-fuel ratio and based on the detected current air-fuel ratio; selecting an in-cylinder exhaust gas recirculation method based on the determined air-fuel ratio adjustment, the in-cylinder exhaust gas recirculation method adjusting an oxygen content and a particulate matter content of exhaust gas arising from combustion; selecting a number of cylinders of the multi-cylinder engine to implement the in-cylinder exhaust gas recirculation method; and controlling the intake valves (130) and the exhaust valves (150) for the selected number of cylinders to adjust the oxygen content and the particulate matter content of the exhaust gas to the exhaust gas by applying a second compression stroke of the respective pistons (160) of the selected number of cylinders (1-6); wherein selecting the in-cylinder exhaust gas recirculation method comprises selecting between a cylinder deactivation mode, a reverse intake mode, and a re-intake modeThe system of claim 1, further comprising adjusting fuel injection by the fuel injection system based on the selected in-cylinder exhaust gas recirculation method.The system of claim 2, wherein adjusting fuel injection into the plurality of cylinders (1-6) comprises increasing fuel injection into combustion cylinders of the plurality of cylinders to increase torque output of the combustion cylinders.The system of claim 2, wherein adjusting fuel injection comprises terminating fuel injection into at least one half of the cylinders of the plurality of cylinders (1-6).The system of claim 2, wherein adjusting fuel injection comprises terminating fuel injection into all cylinders of the multiple cylinders (1-6).The system of claim 2, wherein adjusting fuel injection comprises increasing the injected fuel into the selected number of cylinders.The system of claim 2, wherein adjusting fuel injection comprises mitigating the injected fuel into the selected number of cylinders.The system of claim 2, wherein adjusting fuel injection comprises terminating fuel injection into the selected number of cylinders.The system of any preceding claim, wherein selecting the in-cylinder exhaust gas recirculation method comprises selecting two in-cylinder exhaust gas recirculation methods simultaneously implemented to different cylinders of the plurality of cylinders (1-6).The system of any preceding claim, wherein the cylinder deactivation mode comprises disabling fuel injection, actuating an intake valve (130), and actuating an exhaust valve (150) for at least one stroke cycle of the reciprocating pistons, and wherein a stroke cycle comprises between two and sixteen strokes of the reciprocating pistons (160) reciprocating within their respective cylinders.The system of claim 10, wherein the cylinder deactivation mode further comprises re-engaging fuel injection by the fuel injection system into the selected number of cylinders after a corresponding piston stroke from bottom dead center to top dead center in the selected number of cylinders without opening any of the corresponding intake valves (130) or the corresponding exhaust valves (150) for the selected number of cylinders.The system of any preceding claim, wherein the re-intake mode comprises: disabling intake valve actuation for the selected number of cylinders; and adjusting the stroke of the exhaust valve actuation to the lift motion in the selected number of cylinders such that the exhaust valves (150) of the selected number of cylinders open as the respective reciprocating pistons (160) move from top dead center to bottom dead center in the selected number of cylinders to draw exhaust gas from an exhaust manifold (105) into a selected number of cylinders.The system of claim 12, wherein the re-intake mode comprises closing both the respective intake valves (130) and the respective exhaust valves (150) of the selected number of cylinders while the respective reciprocating pistons (160) move in a compression stroke and through a power stroke from top dead center and back to bottom dead center in the selected number of cylinders.The system of claim 13, wherein the re-intake mode further comprises opening both the respective intake valves (130) and the respective exhaust valves (150) of the selected number of cylinders after a compression stroke as the respective reciprocating pistons (160) move from top dead center back to bottom dead center in the selected number of cylinders.The system of claim 13, wherein the re-intake mode comprises maintaining the respective exhaust valves (150) open to expel the compressed exhaust gas after the power stroke as the respective reciprocating pistons (160) move upward from bottom dead center back to top dead center without closing the respective exhaust valves, maintaining the respective exhaust valves open as the respective reciprocating pistons move from top dead center back to bottom dead center by the selected number of cylinders.The system of claim 13, further comprising re-engaging fuel injection by the fuel injection system into the selected number of cylinders while both the respective intake valves (130) and the respective exhaust valves (150) are closed during the compression and power strokes.The system of any preceding claim, wherein the reverse intake mode comprises: adjusting the stroke of the corresponding exhaust valve actuation for the selected number of cylinders to the lift motion in the selected number of cylinders such that the exhaust valves (150) of the selected number of cylinders open as the corresponding reciprocating pistons (160) in the selected number of cylinders move from top dead center to bottom dead center to draw exhaust gas from an exhaust manifold (105) into a selected number of cylinders; and adjusting the stroke of the corresponding intake valve actuation for the selected number of cylinders to the lift motion in the selected number of cylinders such that the intake valves (130) of the selected number of cylinders open as the corresponding reciprocating pistons (160) in the selected number of cylinders move from bottom dead center to top dead center;The system of claim 17, wherein the reverse intake mode comprises closing both the respective intake valves (130) and the respective exhaust valves (150) of the selected number of cylinders while the respective reciprocating pistons (160) move in a compression stroke and through a power stroke from top dead center and back to bottom dead center in the selected number of cylinders.The system of claim 18, wherein the reverse intake mode further comprises opening the respective intake valves (130) for the selected number of cylinders after the power stroke and as the respective reciprocating pistons (160) move from bottom dead center to top dead center in the selected number of cylinders.The system of claim 18, further comprising re-engaging fuel injection by the fuel injection system into the selected number of cylinders while both the respective intake valves (130) and the respective exhaust valves (150) are closed during the compression and power strokes.The system of claim 17, wherein the reverse intake mode comprises a 2-stroke cycle for pumping exhaust gas through the selected number of cylinders, and wherein the second compression stroke corresponds to movement of the respective reciprocating pistons (160) from bottom dead center to top dead center in the selected number of cylinders.The system of claim 1, wherein the second compression stroke decreases the amount of available oxygen in the exhaust gas.The system of claim 1, further comprising increasing the exhaust temperature to increase the temperature of a catalyst (800) downstream of the engine.The system of claim 1, further comprising an intake manifold opening (132) configured to direct intake gases within the intake manifold (103) coupled to the engine, and wherein the intake manifold opening is configured to promote a homogeneous mixture of gases in the intake manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of claim 1, further comprising an intake manifold opening (132) configured to direct intake gases within the intake manifold (103) coupled to the engine, and wherein the intake manifold opening is configured to concentrate heat in areas of the intake manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of claim 1, further comprising an intake manifold opening (132) configured to direct intake gases within the intake manifold (103) coupled to the engine, and wherein the intake manifold opening is configured to concentrate the presence of recirculated exhaust gas in areas of the intake manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of any of claims 24-26, further comprising a first intake air chamber (136) and a second intake air chamber (138), and a partition wall (139) therebetween.The system of claim 27, further comprising a controllable valve (137) in the bulkhead (139).The system of claim 27, further comprising a second intake manifold opening (134), wherein the first intake manifold opening (132) is associated with the first intake air chamber (136), and the first intake manifold opening and the first intake air chamber are configured to adjust a fluid flow rate into the selected number of cylinders, and wherein the second intake manifold opening (134) is associated with the second intake air chamber (138), and the second intake manifold opening and the second intake manifold air chamber are configured to adjust a fluid flow rate into the remaining cylinders of the plurality of cylinders.The system of claim 1, further comprising an exhaust manifold opening (157) configured to direct exhaust gases within the exhaust manifold (105, 1051) coupled to the engine, and wherein the exhaust manifold opening is configured to promote a homogeneous mixture of gases in the exhaust manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of claim 1, further comprising an exhaust manifold opening (157) configured to direct exhaust gases within the exhaust manifold (105, 1051) coupled to the engine, and wherein the exhaust manifold opening is configured to concentrate heat in areas of the exhaust manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of claim 1, further comprising an exhaust manifold opening (157) configured to direct intake gases within the exhaust manifold (105, 1051) coupled to the engine, and wherein the exhaust manifold opening is configured to concentrate exhaust gases in areas of the exhaust manifold when the in-cylinder exhaust gas recirculation method is implemented.The system of any of claims 30-32, further comprising at least one valve (1570) in the exhaust manifold opening (157) for regulating a backpressure in the exhaust manifold (105, 1051).The system of any of claims 30-32, further comprising a first exhaust air chamber (152) and a second exhaust air chamber (154), and a partition wall (159) therebetween.The system of claim 27, further comprising a controllable valve in the bulkhead.The system of claim 27, further comprising a second exhaust manifold opening (156), wherein the first exhaust manifold opening (157) is associated with the first exhaust air chamber (152) and the first exhaust manifold opening and the first exhaust air chamber are configured to adjust a fluid flow rate into the selected number of cylinders, and wherein the second exhaust manifold opening (156) is associated with the second exhaust air chamber (154) and the second exhaust manifold opening and the second exhaust manifold air chamber are configured to adjust a fluid flow rate into the remaining cylinders of the plurality of cylinders.The system of any of claims 30-32, wherein the method for LCV management further comprises purging exhaust gases downstream of the exhaust manifold.A system for temperature management in a multi-cylinder engine (100), the engine comprising respective reciprocating pistons (160) in the plurality of cylinders (1-6), the respective reciprocating pistons being connected to a crankshaft (101) for rotation of the crankshaft, a computer controllable fuel injection system configured to inject fuel into the plurality of cylinders, respective computer controllable inlet valves (130) and outlet valves (150) for opening and closing the plurality of cylinders, and a computer control network connected to the fuel injection system and the respective inlet valves and respective outlet valves, the network comprising a processor (1403), a tangible storage device (1401) and processor executable control algorithms for implementing a method for temperature management, wherein the method comprises: detecting a power output request to the engine (100); detecting a current air-fuel ratio in either an engine-connected intake manifold (103), an engine-connected exhaust manifold (105), or both. detecting a low temperature condition in the intake manifold (103) and / or the exhaust manifold (105); determining an air-fuel ratio adjustment by thermal management based on the detected current air-fuel ratio and based on the low temperature condition; selecting an in-cylinder exhaust gas recirculation method based on the determined air-fuel ratio adjustment by thermal management, the in-cylinder exhaust gas recirculation method adjusting an oxygen content resulting from combustion and a particulate matter content of exhaust gas to decrease the air-fuel ratio of gases available for combustion; selecting a number of cylinders of the multi-cylinder engine to implement the in-cylinder exhaust gas recirculation method; controlling the intake valves and exhaust valves for the selected number of cylinders to apply a second compression stroke of the respective reciprocating pistons of the selected number of cylinders to the exhaust gas and adjusting the temperature of the exhaust gas by reburning the exhaust gas to which a second compression stroke was applied.

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