WO2017048233A1

WO2017048233A1 - Air-handling control system with asymmetric turbocharger

Info

Publication number: WO2017048233A1
Application number: PCT/US2015/050139
Authority: WO
Inventors: Phanindra Garimella; Ming-Feng Hsieh; Karla FUHS
Original assignee: Cummins Inc.
Priority date: 2015-09-15
Filing date: 2015-09-15
Publication date: 2017-03-23

Abstract

Embodiments of the present invention relate to air-handling for engine systems that include an asymmetrical turbocharger. Further, embodiments of the present invention utilize the control of components of an exhaust system, such as, for example, a waste gate, exhaust throttle, and/or EGR control valve to control the characteristics of a charged flow and/or for thermal management of an exhaust gas. Certain embodiments can utilize operation of the EGR valve and/or waste gate to attain a target EGR flow and/or target EGR fraction for the charged flow. Further, the EGR valve and/or the waste gate may be utilized attain, but not exceed, peak cylinder pressures. Further, the EGR valve and/or exhaust throttle may be operated to reduce temperatures of exhaust gases in the exhaust gas manifold to temperatures that do not exceed inlet exhaust gas temperature limits for one or more turbines of the turbocharger.

Description

AIR-HANDLING CONTROL SYSTEM WITH ASYMMETRIC TURBOCHARGER

BACKGROUND

[0001] Embodiments of the present invention generally relate to air-handling for engine systems that include an asymmetrical turbocharger. More particularly, but not exclusively, embodiments of the present invention relate to the control of components of an exhaust system to control the characteristics of a charged flow that is delivered to an intake side of an engine.

[0002] Turbochargers traditionally assist in the supply of a charged flow to an intake manifold of an internal combustion engine at pressures above atmospheric pressure (boost pressures). A conventional turbocharger may include an exhaust gas driven turbine wheel that is mounted on a rotatable shaft within a turbine housing that is connected downstream of an engine cXiiausi mamiuiu. ivuietuun υι uic lui umc Wiicei lO uca a tuiTipi cssui wncCi uumeu uli uic other end of the shaft within a housing of the compressor. The compressor wheel delivers compresses at least air, and possibly recirculate exhaust gas, that is to be delivered in the charged flow to the engine intake manifold.

[0003] One known approach to improving turbocharging efficiency and reducing emissions for an engine with a wide speed/load range is through the use of an asymmetrical turbocharger. Certain asymmetrical turbochargers may utilize a sequential two stage turbocharging system, comprising of one relatively small high pressure turbocharger and another relatively large low pressure turbocharger. The turbochargers are arranged in series so that exhaust from the engine flows first through the smaller turbine of the high pressure turbocharger, and then through the larger turbine of the low pressure turbocharger. The compressors of the two turbochargers are also often arranged in series, with at least air flowing first through the relatively large compressor of the low pressure turbocharger and then through the relatively small compressor of the high pressure turbocharger.

[0004] Other asymmetrical turbochargers employ a divided exhaust manifold in which exhaust from a first set of engine cylinders is primarily directed to a first turbine and exhaust from a second set of engine cylinders is directed primarily to a second turbine. Yet, with such a configuration, varying the exhaust flow rates of the exhaust gas that is delivered to each turbine may affect turbocharger and engine operation and efficiency, and may require relatively complex controls to balance the exhaust flows, particularly when the associated exhaust system includes an exhaust gas recirculation system.

BRIEF SUMMARY

[0005] An aspect of an embodiment of the present invention is a method that includes determining a pressure ratio between an exhaust side and an intake side of an internal combustion engine of an engine system. The determined pressure ratio can be used to determine at least one of a predicted EGR fraction and a predicted EGR flow. Further, an adjusted pressure ratio between the exhaust side and the intake side may be determined that will adjust at least one of the predicted EGR fraction and the predicted EGR flow to at least one of a target EGR fraction and a target EGR flow. Additionally, a flow of recirculated exhaust gas through an EGR control valve of an EGR system of the engine system can be adjusted to attain the adjusted pressure ratio.

[0006] Another aspect of an embodiment of the present invention is a method that includes releasing, from a first set of cylinders of an engine, a first exhaust gas to a first exhaust gas manifold portion, the first exhaust gas manifold portion being in fluid communication with a first turbine. Additionally, a second exhaust gas from a second set of cylinders of the engine is released to a second exhaust gas manifold portion, the second exhaust gas manifold portion being in fluid communication with a second turbine. Further, the first and second turbines can have different flow capacities. A pressure ratio between an exhaust side and an intake side of the engine can be determined and used in determining at least one of a predicted EGR fraction and a predicted EGR flow. Further, an adjusted pressure ratio between the exhaust side and the intake side can be determined that will adjust at least one of the predicted EGR fraction and the predicted EGR flow to at least one of a target EGR fraction and a target EGR flow. Additionally, a flow of at least one of the first and second exhaust gases through a waste gate can be adjusted to attain the adjusted pressure ratio.

[0007] Another embodiment of the present invention provides a method that includes determining a flow value for a charged flow that is delivered to an intake side of an engine from at least one compressor of an asymmetrical turbocharger. A target flow value for the charged flow can be determined that corresponds to a target pressure of the charged flow that is delivered to the intake side of the engine. The method can also include adjusting a flow of exhaust gas through a waste gate to adjust the flow value to attain the adjusted flow value.

[0008] Another aspect of embodiments of the present invention is a method that includes determining a peak cylinder pressure for one or more cylinders of an internal combustion engine of an engine system, and which can be used to determine a quantity of recirculated exhaust gas that is to be include in a charged flow that is to be delivered to the internal combustion engine. Further, the quantity of the recirculated exhaust gas that flows through an EGR control valve of an EGR system of the engine system can be adjusted to attain the determined quantity of recirculated exhaust gas in the charged flow.

[0009] Additionally, an aspect of embodiments of the present invention is a method that includes determining an exhaust gas temperature in a first exhaust manifold portion of a divided exhaust manifold, the first exhaust manifold being in fluid communication with a first set of cylinders of an internal combustion engine of an engine system, and a second exhaust manifold portion of the divided exhaust manifold being in fluid communication with a second set of cylinders of the internal combustion engine. A controller can determine whether the determined exhaust gas temperature exceeds a target inlet exhaust gas temperature of one or more turbines. The method also includes determining a flow of exhaust gas through an EGR control valve of an EGR system of the engine system that will reduce the pressure in the first exhaust manifold to a level at which the temperature of the exhaust gas in the first exhaust manifold portion does not exceed the target inlet exhaust gas temperature of the one or more turbines. Further, the EGR control valve can be adjusted to attain the determined flow of exhaust gas through the EGR control valve.

BRIEF DESCRIPTION OF THE DRAWINGS

[00010] The description herein makes reference to the accompanying figures wherein like reference numerals refer to like parts throughout the several views.

[00011] Figure 1 illustrates a schematic block diagram of an exemplary internal combustion engine system having an asymmetrical turbocharger.

[00012] Figure 2 illustrates an exemplary, high level representation of control levers for an air-handling system of an engine system that has asymmetrical turbocharger, exhaust gas recirculation valve, electric waste gate, and exhaust throttle architectures. 0139

[00013] Figure 3 illustrates a schematic flow diagram of an exemplary process of operation of an engine system in which a controller may control a pressure ratio across an engine through operation of at least an exhaust gas recirculation (EGR) valve to attain a target EGR fraction and/or target EGR flow.

[00014] Figure 4 illustrates a schematic flow diagram of an exemplary process in which a controller may control the operation of at least the EGR valve to control attained peak cylinder pressures in the cylinders of an engine.

[00015] Figure 5 illustrates a schematic flow diagram of an exemplary process for controlling an exhaust gas inlet temperature for one or more turbines of an asymmetrical turbocharger through operation of an EGR valve.

[00016] The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For, the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[00017] Certain terminology is used in the foregoing description for convenience and is not intended to be limiting. Words such as "upper," "lower," "top," "bottom," "first," and "second" designate directions in the drawings to which reference is made. This terminology includes the words specifically noted above, derivatives thereof, and words of similar import. Additionally, the words "a" and "one" are defined as including one or more of the referenced item unless specifically noted. The phrase "at least one of followed by a list of two or more items, such as "A, B or C," means any individual one of A, B or C, as well as any combination thereof.

[00018] Figure 1 illustrates a schematic block diagram of an exemplary internal combustion engine system 100 that includes an internal combustion engine 102 that is connected to an intake system 104 and an exhaust system 106. It shall be appreciated that the illustrated configuration and components of the engine system 100 are but one example, and that the disclosure contemplates that a variety of different engine systems and the associated components may be utilized. The engine 102 includes an engine block 108 that may define at least a portion of one or more cylinders 1 10 in a variety of different arrangements. Additionally, each cylinder 1 10 is sized to accommodate the slideable displacement of a piston (not shown) along at least a portion of the cylinder 1 10 such that the pistons may reciprocate between a top-dead-center position and a bottom-dead-center position. Each of the cylinders 1 10, its respective piston and cylinder head, form a combustion chamber. Further, at least a portion of the forces generated by the slideable displacement of the piston along at least a portion of the cylinder 1 10 during combustion events in the combustion chamber are transmitted to a mechanical drive system that converts the reciprocal movement of the pistons into rotational movement.

[00019] The cylinders 1 10 are in selective fluid communication with the intake system

104 such that a charged flow maybe delivered to the cylinders 1 10. The cylinders 1 10 are also in selective fluid communication with the exhaust system 106 such that exhaust gases produced by combustion of fuel(s) in the cylinders 1 10 may be delivered through an exhaust manifold 1 14 and to the exhaust system 106. A charged flow may be provided or delivered to an intake manifold 1 16 of the engine 102 through the intake system 104. According to certain embodiments, the intake system 104 may include first and second air inlets 118a, 1 18b that deliver airflow to first and second compressors 120a, 120b of first and second turbochargers 1 19a, 1 19b, respectively, of an asymmetrical turbocharger 122. As used herein, "air" includes fresh air alone or a mixture of fresh air and another component or components, such as any exhaust gas that may be recirculated for mixing with the fresh air and/or fuel that is injected or mixed at the compressor, including exhaust gas delivered to the intake system 104 by an exhaust gas recirculation (EGR) system 126.

[00020] Operation of the first and second compressors 120a, 120b may provide a charged flow, which may pass through a charged air cooler 128 before being distributed by one or more inlet supply conduits 130 to an intake manifold 1 16 of the engine 102 that distributes the charged flow to the cylinders 1 10 of the engine 102. The first and second compressors 120a, 120b, which may be a fixed and/or variable geometry compressor(s), are configured to compress the air or a combined flow of air and recirculated exhaust gas from the EGR system 126 to a predetermined pressure level to provide a charged flow to the engine 102. Further, the fresh air flow or combined flows in the intake system 104 can be filtered or unfiltered, among other conditions, and/or conditioned in any known manner, either before or after mixing with the EGR flow from the EGR system 126, when provided. The intake system 104 may also include other components configured to facilitate or control introduction of the charged flow to engine 1U2, such as, for example, an intake throttle (not shown) that is configured to regulate the charged flow to engine 102.

[00021] The charged air cooler 128 may be an air-to-air type cooler, an air-to-liquid type cooler, or have any other suitable cooler configuration. The compressed inlet air is cooled in the charged air cooler 128 via a heat exchange process, and then pass through the inlet supply conduit 130 for delivery of the cooled, charged flow to at least one intake manifold 1 16. In one example, the first and second compressors 120a, 120b can increase the temperature and pressure of the intake air, while the charged air cooler 128 can increase a charge density and provide more air to cylinders HOa-f of engine 102. In another example, the charged air cooler 128 can be a low temperature aftercooler (LTA). The charged air cooler 128 can use air as the cooling media, while the LTA uses coolant as the cooling media. The intake manifold 1 16 distributes cooled compressed charged flow including inlet air for combustion by one or more cylinders 1 10a- f of the engine 102 that are connected to intake manifold 1 16.

[00022] According to the illustrated embodiment, the exhaust manifold 1 14 is a divided exhaust manifold 1 14 having a first exhaust manifold portion 134a and a second exhaust manifold portion 134b. According to such an embodiment, the first exhaust manifold portion 134a may deliver a portion of the exhaust gas generated by the engine 102, such as exhaust gas generated by a first set 1 12a of cylinders 1 10, to the first turbine 124a, and a second exhaust manifold portion 134b may deliver a portion of the exhaust gas generated by the engine 102, such as exhaust gas generated by a second set 1 12b of cylinders 1 10, to the second turbine 124b. The exhaust gases flowing from the first and second turbines 124a, 124b may be combined in an exhaust flow path and, according to certain embodiments, delivered to an after-treatment system 136 for emissions reduction from the exhaust before outlet to the atmosphere. Further, according to certain embodiments, the exhaust system 106 may include a mechanical or electrical waste gate 138 that is configured to divert at least a portion exhaust gas away from the first and/or second turbines 124a, 124b of the asymmetrical turbocharger 122. Operation of the waste gate 138 may be controlled by a controller 140, as discussed below.

[00023] According to certain embodiments, the different sizing between the first and second turbines 124a, 124b can optimize exhaust gas recirculation from the first set 1 12a of cylinders 1 10 and to minimize pumping losses through the second set 1 12b of cylinders 1 10. Moreover, the first turbine 124a may restrict exhaust flow by an amount greater than the second turbine 124b by having a lower flow capacity, which, in conjunction with an exhaust throttle 142, can increase the back pressure in EGR system 126 and in the first exhaust manifold 1 14. Flow capacity in the first turbine 124a may be decreased in a variety different manners, such as, but not limited to, a lower cross-sectional flow area at the opening to the turbine housing, smaller turbine wheel diameter, smaller trim profile, vane setting, or other arrangement that reduces exhaust flow relative to the second turbine 124b.

[00024] The after-treatment system 136 may be one of a variety of types of after-treatment systems, including, for example, those after-treatment systems designed to remove particulates, nitrogen-oxide compounds, and other regulated emissions. For example, according to certain embodiments, the after-treatment system 136 may include a selective catalytic reduction system and/or a diesel oxidation catalyst, among other systems. Thus, according to certain embodiments, in at least an attempt to manage the treatment of at least certain pollutants in the exhaust gas, the controller 140 may be structured to control the thermal management of the after- treatment system 136, components of the after-treatment system 136, and/or the exhaust gas that flows through the exhaust system 106. For example, according to certain embodiments, one or more controllers 140 may be adapted to at least attempt to manage certain engine system 100 operations so as to maintain the temperature of the exhaust gases released from the engine system 100 and/or entering into the after-treatment system 136 or components of the after- treatment system 136 at levels that may optimize reactions in the after-treatment system 136 that may convert pollutants, such as, for example, nitrogen oxides (NO_x) into nitrogen and water.

[00025] The exhaust system 106 further includes an EGR system 126 that is in fluid communication with at least the first set 1 12a of cylinders 1 10. The EGR system 126 may include an EGR flow path 144, an EGR cooler 146, and an EGR control valve 148. Further, certain embodiments may also include an EGR bypass that allows exhaust gas in the EGR system 126 to bypass the EGR cooler 146. In the illustrated embodiment, the EGR flow path 144 operably connects the first exhaust manifold 1 14 to the intake system 104. For example, the EGR flow path 144 may divert recirculated exhaust gas upstream or downstream of the outlet of first turbine 124a to a location in the intake system 104 that is upstream or downstream of the first and second compressors 120a, 120b. Moreover, according to the embodiment depicted in Figure 1 , according to certain embodiments, the EGR flow path 144 may deliver exhaust gas to the intake system 104 downstream of the charged air cooler 128 and at a location at or upstream of the intake manifold 1 16. Thus, according to such embodiments, a mass of charged flow (MCF) comprising compressed ambient air and recirculated exhaust gas from the EGR system 126 is supplied to the intake manifold 1 16 of the engine 102.

[00026] The EGR control valve 148 is adapted for use in the control the passage of recirculated exhaust gas from the EGR system 126 to the intake system 104. Thus, operation of the EGR control valve 148 may be used to control the amount of recirculated exhaust gases that are present in the cylinders 1 10 of the engine 102 during combustion events. According to certain embodiments, operation of the EGR valve 148 may be controlled by a controller 140 of the engine system 100, which may provide instructions or commands that operate an actuator that is operably coupled to the EGR control valve 148. Further, a variety of different types of valves maybe utilized for the EGR control valve 148, including, for example, a modulating valve and an on/off valve.

[00027] The controller 140 is adapted to receive data as input from various sensors, and send command signals as output to various actuators. Some of the various sensors and actuators that may be employed are described below. The controller 140 can include a processor, a memory, a clock, and an input/output (I/O) interface. In certain embodiments, controller 140 is structured to perform certain operations to control the asymmetrical turbocharger 122, the EGR system 126, a waste gate 138, and/or an exhaust throttle 142, among other components of the engine system 100, in achieving one or more target conditions. In certain embodiments, the controller 140 forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller 140 may be a single device or a distributed device, and the functions of the controller 140 may be performed by hardware and/or instructions for algorithms that are provided on non-transient computer readable storage media. During operation, the controller 140 can receive information from the various sensors 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.

[00028] According to the illustrated embodiment, the engine system 100 may include sensors 150a-c that provide information utilized by the controller 140 to determine or predict a pressure in the intake manifold 1 16 and in one or more of the first and second exhaust manifold portions 134a, 134b. For example, according to certain embodiments, a first sensor 150a may be a pressure sensor that is positioned to provide measurements that indicate or are used to determine a pressure (IMP) within the intake manifold 1 16, while a second sensor 150b may be positioned to measure or detect a pressure (EMP) within in the first exhaust manifold portion 134a. As an alternative, or in addition, to pressure sensors, one or more of the sensors 150a-c with the intake manifold 116, the first exhaust manifold portion 134a, and/or the second exhaust manifold portion 134b may include, or be, a temperature sensor. For example, referencing Figure 1 , according to certain embodiments, the engine system 100 may include a first sensor 150a that provides a measurement(s) that is used to determine or indicate the pressure (IMP) of the charged flow in the intake manifold 1 16, and a second sensor 150b that either measures or detects information relating to a pressure (EMP) or temperature (EMT) of the exhaust gas in, or exiting, the first exhaust manifold portion 134a.

[00029] Additionally, according to certain embodiments, the sensors that provide information to the controller 140 may also include a temperature sensor(s) 150d at the inlets 154 of at least one of the first and second turbines 124a, 124b and an exhaust gas flow sensor (EGF) 156 that detects the amount of exhaust gas that is flowing through the EGR system 126, and more particularly, the amount of exhaust gas that is being recirculated to the intake system 104 and/or to the intake manifold 1 16. Alternatively, according to other embodiments, the controller 140 may determine or estimate the quantity of exhaust gas flowing through the EGR system 126. The EGR system 126 may also include a pressure or temperature sensor that may assist in determining a flow rate for the recirculate exhaust gas that is passing in or through the EGR system 126. Additionally, the engine system 100 may also include an intake flow sensor 158 to detect the amount of charged air, with or without recirculated exhaust gas, being delivered to the intake manifold 1 16. Alternatively, according to other embodiments, rather than using an intake flow sensor 158, the controller 140 may estimate the amount of charged flow, with or without recirculated exhaust gas, that is delivered to the intake manifold 1 16 using pressure or temperature information relating to the intake manifold 1 16, as provided by, for example, at least the first sensor 150a. For example, according to certain embodiments, the controller 140 may estimate the charged flow using a speed-density calculation.

[00030] Actuators that may be controlled by instructions from the controller 140 of the engine system 100 can be provided for opening and closing the waste gate 138, the exhaust 9

throttle 142, and, as previously discussed, the EGR control valve 148. During at least normal operating conditions, relatively precise control of the actuators and the associated EGR control valve 148, waste gate 138, and exhaust throttle 142 may assist in attaining proper engine 102 operation. For example, proper operation of the engine 102 often involves at least precise control of the flow of recirculated exhaust gas and the associated mass of charged flow (MCF), which may therefore involve at least relatively precise control of the EGR control valve 148. Additionally, accurate control of the actuators and their associated EGR control valve 148, waste gate 138, and exhaust throttle 142 may facilitate proper engine 102 operation and performance during off-nominal conditions, such as, for example, during cold starting of the engine 102. Further, control of the EGR control valve 148, waste gate 138, and exhaust throttle 142 by instructions or commands from the controller 140 to the actuator may assist in the thermal management of the exhaust system 106, including, for example, influence the temperature (TIT) of the exhaust gas at the inlet 154 of the first and/or second turbines 124a, 124b, the temperature of the exhaust gases being released from an outlet 155 of the first and/or second turbines 124a, 124b, and/or the temperature of the exhaust gases being deliver and/or passing through the after- treatment system 136. Other actuators can be provided for opening and closing the exhaust valves and intake valves of cylinders 110. Actuators can be solenoid actuated, hydraulically actuated, pneumatically actuated, mechanically actuated, or actuated in any suitable manner.

[00031] Figure 2 illustrates an exemplary, high level representation of the control levers

160 for an air-handling system of an engine system that has the asymmetrical turbocharger 122, EGR control valve 148, electrical waste gate 138, and exhaust throttle 142. According to the depicted embodiment, the engine system 100 may include the EGR control valve 148, the waste gate 138, which in this particular example is an electric waste gate, and the exhaust throttle 142. According to the depicted embodiment, and as discussed below, the controller 140 may control the operation of the EGR control valve 148 in connection with controlling the EGR flow, and moreover, influence the mass flow of recirculated exhausts gases contained in the charged flow that is delivered to the engine 102. As also indicated by Figure 2 and discussed below, according to certain embodiments, the controller 140 may operate the waste gate 138 in a manner that at least controls the pressure ratio (PR) between the exhaust manifold (EMP) and the intake manifold (IMP), the control of which may be utilized to attain, or fall within, a target EGR fraction (XEORfraction) and/or target EGR flow (XEGRH_OW)- The controller 140 may further control the operation of the waste gate 138 in connection with controlling the charged flow rate and the speed of the first and/or second turbines 124a, 124b. Additionally, the controller 140 may, in connection with the thermal management of at least the exhaust system 106, control the operation of the exhaust throttle 142 so as to regulate the engine-out pressure of the exhaust gases, and thereby control the engine-out temperature.

[00032] Figure 3 illustrates a schematic flow diagram of an exemplary process 300 of operation of an engine system 100 in which the controller 140 may control a pressure ratio (PR) across the engine 102 through operation of at least the EGR control valve 148 to attain, or fall within, a target EGR fraction and/or target EGR flow. The operations illustrated for all of the processes in the present application are understood to be examples only, and operations may be combined or divided, and added or removed, as well as re-ordered in whole or in part, unless explicitly stated to the contrary. At step 302, the controller 140 may be provided with measured or determined information that relates to an intake manifold pressure (IMP). Similarly, at step 304, the controller 140 may be provided with measured or determined information that relates to an exhaust manifold pressure (EMP) for at least one of the first and second exhaust manifold portions 134a, 134b. According to certain embodiments, the information provided at steps 302 and 304 may be measured pressure and/or temperatures from at least the first and/or second sensors 150a, 150b. At step 306, the controller 140 uses the intake and exhaust manifold pressures and/or temperatures to determine a pressure ratio (PR) across the engine 102 (e.g. , PR = EMP/IMP). At step 308, the controller 140 may reference or otherwise utilize the determined pressure ratio to predict the correlating mass flow of recirculated exhausts gases that is entering the engine 102 through the intake (EGR flow) and/or the EGR fraction, which may be the ratio of the EGR flow and the total mass of charged flow entering the engine 102 through the intake. Such a prediction may, according to certain embodiments, utilize a monotonic relationship, which may or may not be linear, among other relationships, between pressure ratio (PR) across the engine 102 and EGR flow and/or EGR fraction. Further, such a relationship(s), may, according to certain embodiments, be expressed as an algorithm, model, reference table, or provided in other forms, and may be stored in, or otherwise accessible to, the memory of the controller 140. At step 310, the controller 140 may evaluate the predicted EGR fraction and/or EGR flow to determine whether the predicted EGR fraction and/or EGR flow does, or does not, satisfy a target value or range of values for a target EGR fraction (XEGRfraction) and/or a target EGR flow X

[00033] If the predicted EGR fraction and/or EGR flow does comply with the target EGR fraction (XEGRfraction) and/or the target EGR flow X then the controller 140 may continue to monitor the intake and exhaust manifold pressures and/or temperatures (IMP, EMP, EMT) in connection with determining whether the predicted EGR fraction and/or EGR flow continue to comply with the target EGR fraction (XEGRfraction) and/or for the EGR flow (X )- However, if the predicted EGR fraction and/or EGR flow does comply with the target EGR fraction (XEGRfraction) and/or target EGR flow (X ), then at step 312, the controller 140 may determine an adjusted pressure ratio (PR) that attains the target EGR fraction (XEGRfraction) and/or target EGR flow (X

[00034] At step 314, according to certain embodiments, the controller 140 may determine adjustments in the operation of the EGR control valve 148, the waste gate 138, and/or the exhaust throttle 142 that may alter IMP and/or the EMP. For example, according to the illustrated example, the controller 140 may determine a recirculated exhaust gas flow value for recirculated gas through the EGR control valve 148 that will adjust the charged flow that is delivered to the intake manifold in a manner that adjusts the pressure ratio to attain the determined adjusted pressure ratio. Moreover, the controller 140 may determine the degree to which a position and/or an adjustment in the position of the EGR control valve 148 will adjust the quantity of recirculated exhaust gas in the charged flow that is delivered to the intake side of the engine 102, such as, for example, to the intake manifold 1 16 and/or to the cylinders 1 10, so that the adjusted pressure ratio is at a level that corresponds to the target EGR fraction (XEGRfraction) and/or target EGR flow (X According to certain embodiments, the flow value may correspond to a quantity, mass, or rate of flow of exhaust gases through the EGR system 126, including, for example, through the EGR control valve 148. Alternatively, the flow value may correspond to a degree or amount to which the position of the EGR control valve 148 is to be adjusted or opened/closed.

[00035] Accordingly, at step 316, the controller 140 may provide instructions to an actuator(s) associated with the EGR control valve 148, the waste gate 138, and/or the exhaust throttle 142 that adjusts such devices 138, 142, 148 in a manner that alters the flow, if any, through those devices 138, 142, 148 in a manner that may alter the pressure ratio (PR) across the engine 102 to attain the determined adjusted pressure ratio. For example, according to certain embodiments, the controller 140 may receive measured or predicted information indicating the mass flow of exhaust gas being recirculated to the intake system 104. According to such an embodiment, the mass flow of the recirculated exhaust gas may be detected by the exhaust gas flow sensor (EGF) 156 or predicted by the controller 140 using other information. Further, according to such an embodiment, the controller 140 may determine a degree of recirculated exhaust gas that is, or is not, to be included in the charged flow that is delivered to the intake manifold 1 16, and moreover which is present during the combustion event(s) in the cylinders 1 10, so as to alter the pressure ratio (PR) across the engine 102 so as to attain the target EGR fraction (X_EGRfraction) and/or target EGR flow (XEGRAOW).

[00036] At step 318, based on instructions provided by the controller 140, the position of the EGR control valve 148 may be adjusted in at least an attempt to adjust the pressure ratio (PR) across the engine 102. For example, according to the discussed example, based on instructions provided from the controller 140, the actuator may adjust the EGR control valve 148 so as to increase or decrease the mass of recirculated exhaust gas that is in the charged flow that is delivered to the intake manifold 1 16, and moreover to the cylinders 1 10, which may alter the characteristics of the pressure at the intake manifold 116 and/or the characteristics of the combustion event, and thereby adjust the pressure ratio (PR) between the intake manifold 116 and the first and/or second exhaust manifold portions 134a, 134b.

[00037] According to another embodiment, in addition to, or rather than, using the EGR control valve 148 to control the pressure ratio (PR) across the engine 102, the pressure ratio (PR) may be controlled through operation of the waste gate 138. For example, according to certain embodiments, the waste gate 138 may be an electric waste gate 138 that is controlled■ by instructions from the controller 140 to actuator that is operably coupled to the waste gate 138. According to such an embodiment, altering the waste gate 138 so as to increase or decrease the flow of exhaust gases through the waste gate 138 may alter the exhaust gas pressure (EMP) in at least the first and/or second exhaust gas manifold portions 134a, 134b, and thereby adjust the pressure ratio (PR) across the engine 102. Further, according to certain embodiments, the controller 140 may adjust the flow of exhaust gas through the waste gate 138 to adjust the pressure ratio (PR) to a level in which the corresponding EGR flow and/or EGR fraction attains, or is within a range that meets, the target EGR fraction (XEGRfraction) and/or the target EGR flow

(XEGRflow)-

[00038] Alternatively, in addition to, or in lieu of, using the EGR control valve 148 and/or the waste gate 138 to control the pressure ratio (PR) across the engine 102, the controller 140 may utilize the exhaust throttle 142 to control the EMP, and thereby alter the pressure ratio (PR) across the engine 102. Again, similar to the EGR control valve 148 and the waste gate 138, the extent to which the controller 140 may adjust operation of the exhaust throttle 142 may, in at least certain situations, include consideration of the above-discussed monotonic relationship between pressure ratio (PR) and EGR flow and/or EGR fraction. Accordingly, the controller 140 may also control the exhaust throttle 142 in a manner in which the pressure ratio (PR) across the engine 102 corresponds to attaining the target EGR fraction (XEGRfraction) and/or the target EGR flow (XEGRA_OW). Further, for example, similar to the EGR control valve 148, the exhaust throttle 142 can be a butterfly valve, gate valve, ball valve, globe valve, or any type of suitable valve operable to selectively open, block, or partially open the flow path in which the valve is positioned.

[00039] According to certain embodiments, the controller 140 may control the waste gate 138 in a manner that influences the speed of the first and/or second turbines 124a, 124b. For example, the controller 140 may utilize the waste gate 138 to divert an increased amount of exhaust gases through the waste gate 138, which may decrease the speed of the first and/or second turbines 124a, 124b. Such a decrease in speed of the first and/or second turbines 124a, 124b may thereby decrease the power of the associated first and second compressors 120a, 120b, which may result in a decrease the amount of charged flow that is delivered to the engine 102. Conversely, the controller 140 may operate the waste gate 138 in a manner that decreases the amount of, and/or prevents, exhaust gases being diverted through the waste gate 138, which may increase the speed of the first and/or second turbines 124a, 124b. Further, increasing the speed of the first and/or second turbines 124a, 124b may increase the degree to which the charged flow is compressed by the associated first and second compressors 120a, 120b.

[00040] Further, by using the waste gate 138 to control the speed of the turbines 124a, 124b, the controller 140 may operate the waste gate 138 to adjust the pressure and/or mass of charged flow, also referred to as a flow value, that is delivered to the engine 102, and thereby adjust the IMP. For example, in certain instances in which the IMP is to be reduced, the controller 140 may determine that the flow value is to be adjusted in order to attain a target IMP. Further, the controller 140 may also determine an adjustment in the amount and/or rate at which exhaust gas is to flow through the waste gate 138 to attain the adjusted or target flow rate for the charged flow that is delivered to an intake side of the engine 102. Therefore, according to certain embodiments, the controller 140 may determine a degree or extent, if any, to adjust the flow through the waste gate 138 so as to adjust the charged flow in a manner that can attain the IMP. Further, in addition to, or in lieu of, the controller 140 may determine a speed of the one or more turbines 124a, 124b and/or associated speed or power for the compressor(s) 120a, 120b that will attain the target flow value for the charged flow.

[00041] For example, as previously discussed, by increasing the flow of exhaust gases that are diverted through the waste gate 138, the mass of the flow of exhaust gases delivered to at least one of the first and second turbines 124a, 124b may be decreased, thereby decreasing the speed of that first and/or second turbine(s) 124a, 124b. Further, reducing the speed of the first and/or second turbine 124a, 124b may reduce the power of the associated first and second compressors 120a, 120b, and result in a decrease in the charged flow delivered to the engine 102. Moreover, such a decrease in the delivered charged flow may decrease the IMP, which may result in an adjustment in the pressure ratio (PR=EMP/IMP), such as, for example, an increase in the pressure ratio (PR). Conversely, according to such an embodiment, a reduction in the amount of exhaust gases diverted through the waste gate 138 may result in an increase in the power of the first and second compressors 120a, 120b, and which may result in an increase in the charge flow delivered to the engine 102, and thus an increase in the IMP. Accordingly, by increasing the IMP, through operation of the waste gate 138, the controller 140 can decrease the pressure ratio (PR) (PR = EMP/IMP).

[00042] Figure 4 illustrates a schematic flow diagram of an exemplary process 400 in which a controller 140 may control the operation of at least the EGR control valve 148 to attained peak cylinder pressures in the cylinders 1 10 of the engine 102. More specifically, Figure 4 illustrates an embodiment in which operation of an EGR control valve 148 having on/off functionality is used to adjust the mass of charged flow delivered to the intake manifold 1 16 and/or to the cylinders 110 of the engine 102, with the mass of charged flow generally being the combined mass of the ambient air and the recirculated exhaust gas in the compressed air flow that is delivered to the engine 102. At step 402, the controller 140 may be provided with information indicating and/or used to determine the torque being outputted from combustion events in the cylinders 1 10 and/or the torque being outputted from operation of the engine 102. At step 404, the controller 140 may be able to determine the peak cylinder pressures (PCP) that may be experienced in the cylinders 1 10 when the engine 102 is producing, or is to produce, such a torque. At step 406, in view of the determined or predicted torque and the PCP, the controller 140 may determine the mass of, and/or the quantity of recirculated exhaust gas in, the charged flow that can be used to satisfy PCP requirements, but which may not exceed PCP limits. At step 408, the controller 140 may determine whether the charge flow is, or is not, to be adjusted. For example, the controller 140 may determine that attaining, and/or not exceeding, the PCP may require a change in the on/off position of the EGR control valve 148 so as to alter the quantity of recirculated exhaust gas in the charged flow. Further, such a determination may include a determination of the time period during which the EGR control valve 148 is to revert back, if at all, to either of the on/off positions. If the controller 140 determines that the charge flow is not to be altered, then the controller 140 may continue monitoring the actual or predicted torque and associated PCPs. If, however, the charge flow is to be altered, then, at step 410, the controller 140 may determine the amount of recirculated exhaust gas that is to be present in the charged flow and/or the extent to which the current recirculated exhaust gas in the charged flow is to be adjusted. Further, at step 412, the controller 140 may determine the degree to which the EGR control valve 148 is to be adjusted to attain the determined adjustment in the quantity of recirculated exhaust gas in the charged flow. Accordingly, at step 414, the controller 140 may communicate instructions for the actuator of the EGR control valve 148 to alter the on/off position of the EGR control valve 148 so as to adjust the presence of recirculated exhaust gas in the mass of charged flow that is to be delivered to the engine 102.

[00043] Figure 5 illustrates a schematic flow diagram of an exemplary process 500 for controlling an exhaust gas inlet temperature for one or more first and/or second turbines 124a, 124b through operation of the EGR control valve 148. Moreover, the controller 140 may be structured to use the on/off functionality of an EGR control valve 148 to control the temperature of the exhaust gas, through adjustment of the presence and/or quantity of exhaust gases in the mass of charged flow in the cylinders 1 10. According to such an embodiment, at step 502, the sensor 150b, 150c of the first or second exhaust manifold portion 134a, 134b may measure or detect information that indicates, or corresponds to, the temperature of the exhaust gas in the first and/or second exhaust manifold portions 134a, 134b. For example, according to certain embodiments, the second senor 150b may be a temperature sensor that measures the temperature (EMT) of the exhaust gas in the first or second exhaust manifold portion 134a, 134b. At step 504, the controller 140 may receive the measured or detected information regarding the temperature (EMT) of the exhaust gas at the first and/or second exhaust manifold portions 134a, 134b and determine whether the EMT is above or below a target EMT value(s). Such target EMT values may provide an indication of whether a temperature (TIT) of the exhaust gas that is entering an inlet 154 of the first and/or second turbines 124a, 124b does or will exceed a target turbine inlet temperature(s). If the controller 140 determines that the temperature (EMT) of the exhaust gases at the first and/or second exhaust manifold portions 134a, 134b are not above the target temperature(s), then, as shown in Figure 5, the controller 140 may continue with receiving and evaluating EMTs. If, however, the controller 140 determines that the EMT exceeds the target temperature, then at step 506, the controller 140 may determine the adjustment in the recirculated exhaust gas may reduce the temperature of the combustion events in the cylinders 1 10 such that the exhaust gas at least does not exceed the temperature limits of the inlet 154 of the first and/or second turbines 124a, 124b. According, at step 508, the controller 140 may determine the extent to adjust the operation of the EGR control valve 148 to attain the adjusted amount of recirculated exhaust gas in the charged flow.

[00044] Thus, at step 510, the controller 140 may communicate instructions for the actuator that is operably coupled to the EGR control valve 148 instructing the actuator to alter the position of the EGR control valve 148, as determined by the controller at step 508, so as to increase the mass flow of recirculated exhaust gas in the mass of charged flow, which may reduce the temperature(s) attained during the combustion event, and thereby reduce the temperature of the exhaust gas released to the first and/or second exhaust manifold portions 134a, 134b. Further, as previously discussed, by increasing the mass flow of recirculated exhaust gas in the mass of charged flow to reduce the EMT, the PIP attained in the cylinders 1 10 during associated combustion events may also be reduced. Conversely, in certain situations, the controller 140 may instruct the actuator to alter the position of the EGR control valve 148 so as to decrease the mass flow of recirculated exhaust gas in the mass of charged flow, which may facilitate an increase in both the temperature(s) attained during the combustion event and the PIP, and thereby increase the temperature of the exhaust gas released to the first and/or second exhaust manifold portions 134a, 134b.

[00045] According to certain embodiments, the controller 140 may also be adapted to utilize the exhaust throttle 142 in connection with the thermal management of the exhaust system 106. For example, the controller 140 may use the exhaust throttle 142 in connection with at least the thermal management of exhaust gas that is received and/or released from at least one of the first and second turbines 124a, 124b and/or in connection with the thermal management of exhaust gas that is delivered to the after-treatment system 136. According to such embodiments, the exhaust throttle 142 is adapted to control the engine-out pressure of exhaust gases, such as, for example, EMP. Accordingly, a decrease in engine-out pressure of exhaust gases by operation of the exhaust throttle 142 is generally accompanied by a decrease in the temperature of the exhaust gas. Accordingly, the controller 140 may be adapted to reduce the flow of exhaust gas through the exhaust throttle 142 when the temperature of the exhaust gas is to be increased, and conversely increase the flow of exhaust gas through the exhaust throttle 142 when the temperature of the exhaust gas is to be decreased.

[00046] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as "a," "an," "at least one" and "at least a portion" are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language "at least a portion" and/or "a portion" is used the item may include a portion and/or the entire item unless specifically stated to the contrary.

Claims

1. A method comprising:

determining a pressure ratio between an exhaust side and an intake side of an internal combustion engine of an engine system;

determining, using the determined pressure ratio, at least one of a predicted EGR fraction and a predicted EGR flow;

determining an adjusted pressure ratio between the exhaust side and the intake side that will adjust at least one of the predicted EGR fraction and the predicted EGR flow to at least one of a target EGR fraction and a target EGR flow; and

adjusting a flow of recirculated exhaust gas through an EGR control valve of an EGR system of the engine system to attain the adjusted pressure ratio.

2. The method of claim 1 , further including the steps of:

determining a pressure of a charged flow in an intake manifold of the internal combustion engine; and

determining a pressure of an exhaust gas in one of a first exhaust manifold portion and a second exhaust manifold portion of an exhaust manifold of the internal combustion engine, wherein the pressure ratio is a ratio between the determined pressure of the exhaust gas and the determined pressure of the charged flow.

3. The method of claim 2, wherein the step of determining the pressure of the charged flow comprises measuring, by a pressure sensor, a pressure in the intake manifold, and wherein the step of determining the pressure of the exhaust gas comprises measuring at least one of a pressure and a temperature in one of the first and second exhaust manifold portions.

4. The method of claim 3, wherein the step of determining the adjusted pressure ratio comprises determining, using a monotonic relationship between pressure ratio and at least one of EGR fraction and EGR flow, at least one of the predicted EGR fraction and the predicted EGR flow.

5. The method of claim 4, further including the step of measuring a flow of the recirculate exhaust gas through the EGR system, and wherein the step of adjusting the flow of the recirculated exhaust gas includes determining, using at least the measured flow, the extent to which to adjust the flow of the recirculated exhaust through the EGR control valve.

6. A method comprising:

releasing, from a first set of cylinders of an engine, a first exhaust gas to a first exhaust gas manifold portion, the first exhaust gas manifold portion being in fluid communication with a first turbine;

releasing, from a second set of cylinders of the engine, a second exhaust gas to a second exhaust gas manifold portion, the second exhaust gas manifold portion being in fluid communication with a second turbine, the first and second turbines having different flow capacities;

determining a pressure ratio between an exhaust side and an intake side of the engine; determining, using the determined pressure ratio, at least one of a predicted EGR fraction and a predicted EGR flow;

adjusting a flow of at least one of the first and second exhaust gases through a waste gate to attain the adjusted pressure ratio.

7. The method of claim 6, further including the steps of:

determining a pressure of at least one of the first and second exhaust gases in at least one of the first and second exhaust gas manifold portions,

wherein the pressure ratio is a ratio between the determined pressure of at least one of the first and second exhaust gases and the determined pressure of the charged flow.

8. The method of claim 7, further including the steps of adjusting, by adjustment of the flow through the waste gate, a quantity of the charged flow that is delivered to the intake side of the engine.

9. The method of claim 8, wherein the step of adjusting the quantity of the charged flow delivered to the intake side of the engine includes adjusting the speed of at least one of the first and second turbines.

10. The method of claim 8, further including the step of adjusting the flow of at least one of the first and second exhaust gases through an exhaust throttle to attain a target temperature for at least one of the first and second exhaust gases, the exhaust throttle being in fluid communication with at least one of the first and second exhaust manifold portions.

1 1. A method comprising:

determining a flow value for a charged flow delivered to an intake side of an engine from at least one compressor of an asymmetrical turbocharger;

determining a target flow value for the charged flow, the target flow value corresponding to a target pressure of the charged flow that is delivered to the intake side of the engine; and

adjusting a flow of exhaust gas through a waste gate to adjust the flow value to attain the adjusted flow value.

12. The method of claim 1 1 , wherein the flow value is a measured mass flow value, and wherein the adjusted flow value is an adjusted mass flow value.

13. The method of claim 12, further including the steps of:

determining an adjusted speed of one or more turbines of the asymmetrical turbocharger, the adjusted speed corresponding to a speed of the one or more turbines facilitates attaining the adjusted flow value for the charged flow, and

adjusting the flow of exhaust gas through the waste gate to attain the adjusted speed of the one or more turbines.

14. A method comprising:

determining a peak cylinder pressure for one or more cylinders of an internal combustion engine of an engine system;

determining, using the determined peak cylinder pressure, a quantity of recirculated exhaust gas to include in a charged flow that is to be delivered to the internal combustion engine; and adjusting the quantity of the recirculated exhaust gas that flows through an EGR control valve of an EGR system of the engine system to attain the determined quantity of recirculated exhaust gas in the charged flow.

15. The method of claim 14, wherein the step of determining the peak cylinder pressure includes determining a torque generated by operation of the internal combustion engine, and further wherein the step of adjusting the quantity of the recirculated exhaust gas includes operating an on/off functionality of the EGR control valve.

16. The method of claim 15, further including the step of delivering the charged flow having the adjusted quantity of recirculated exhaust gas to the internal combustion engine.

17. The method of claim 16, wherein the step of determining the quantity of recirculated exhaust gas includes determining a quantity of recirculated exhaust gas that will not result in the combustion of the charge flow in the one or more cylinders exceeding a limit for the peak cylinder pressure

18. A method comprising:

determining an exhaust gas temperature in a first exhaust manifold portion of a divided exhaust manifold, the first exhaust manifold being in fluid communication with a first set of cylinders of an internal combustion engine of an engine system, a second exhaust manifold portion of the divided exhaust manifold being in fluid communication with a second set of cylinders of the internal combustion engine;

determining, by a controller, that the determined exhaust gas temperature exceeds a target inlet exhaust gas temperature of one or more turbines;

determining a flow of exhaust gas through an EGR control valve of an EGR system of the engine system that will reduce the pressure in the first exhaust manifold to a level at which the temperature of the exhaust gas in the first exhaust manifold portion does not exceed the target inlet exhaust gas temperature of the one or more turbines; and

adjusting the EGR control valve to attain the determined flow of exhaust gas through the EGR control valve.

19. The method of claim 18, further including the step of determining a pressure value of the exhaust gas in the first exhaust manifold portion that corresponds to the temperature of the exhaust gas in the first exhaust manifold portion not exceeding the target inlet exhaust gas temperature of the one or more turbines.

20. The method of claim 19, wherein the step of determining a flow of exhaust gas through the EGR control valve comprises determining the flow of exhaust gas through the EGR control valve that corresponds to the determined pressure value of the exhaust gas in the first exhaust gas manifold portion, and wherein the step of determining the exhaust gas temperature in the first exhaust manifold portion includes measuring, by a temperature sensor, the temperature of the exhaust gas that is in the first exhaust manifold portion.