Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one primary EGR cylinder and a plurality of non-primary EGR cylinders. The systems, apparatus and methods control the amount of recirculated exhaust gas in a charge flow in response to EGR fraction deviation conditions.

Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one primary EGR cylinder and a plurality of non-primary EGR cylinders. The systems, apparatus and methods control the amount of recirculated exhaust gas in a charge flow in response to EGR fraction deviation conditions.

Systems, methods and apparatus are disclosed for providing or maintaining a target surge margin at the compressor during steady state engine operating conditions and to avoid compressor surge during transients by controlling a compressor recirculation valve position to a commanded position. The estimated surge margin can be determined in response to the measured pressure ratio across the compressor, an estimated compressor flow, and a compressor map for the compressor.

Systems, methods and apparatus are disclosed for providing or maintaining a target surge margin at the compressor during steady state engine operating conditions and to avoid compressor surge during transients by controlling a compressor recirculation valve position to a commanded position. The estimated surge margin can be determined in response to the measured pressure ratio across the compressor, an estimated compressor flow, and a compressor map for the compressor.

An engine system includes an engine with an intake manifold and an exhaust manifold, a turbocharger including a turbine in communication with the exhaust manifold and a compressor in communication with the intake manifold, and a regulator configured to control a flow of exhaust gas through the turbine. A controller of the engine system is operably connected with the regulator and is configured to monitor an engine load and an exhaust gas temperature during operation of the engine, identify a proscribed engine NOx emissions level based on the engine load and the exhaust gas temperature and, when the proscribed engine NOx emissions level is identified, modify the flow of exhaust gas through the turbine to reduce the energy extracted from the exhaust gas by the turbine and reduce a drive power provided to the compressor, thereby reducing a flow of intake air provided to the intake manifold by the compressor.

An engine system includes an engine with an intake manifold and an exhaust manifold, a turbocharger including a turbine in communication with the exhaust manifold and a compressor in communication with the intake manifold, and a regulator configured to control a flow of exhaust gas through the turbine. A controller of the engine system is operably connected with the regulator and is configured to monitor an engine load and an exhaust gas temperature during operation of the engine, identify a proscribed engine NOx emissions level based on the engine load and the exhaust gas temperature and, when the proscribed engine NOx emissions level is identified, modify the flow of exhaust gas through the turbine to reduce the energy extracted from the exhaust gas by the turbine and reduce a drive power provided to the compressor, thereby reducing a flow of intake air provided to the intake manifold by the compressor.

Provided is a control device and a control method of a high-efficiency internal combustion engine capable of stabilizing combustion and suppressing NO.sub.x emissions without unnecessarily increasing a mounting load on an ECU. Therefore, the control device of the internal combustion engine for controlling the internal combustion engine includes an ignition plug that ignites an air-fuel mixture of fuel and air in the combustion chamber, a combustion pressure estimation sensor that detects a combustion pressure in the combustion chamber, and a crank angle sensor that detects a crank angle of a crankshaft. An MBT region is set based on an ignition delay period from an ignition timing of the ignition plug calculated from a detection value of the combustion pressure estimation sensor and a detection value of the crank angle sensor to a combustion start timing in the combustion chamber, and a combustion period from the combustion start timing to a set amount combustion end timing when a set amount of combustion ends. An ignition timing of the ignition plug is controlled so as to fall within the set MBT region.

Provided is a control device and a control method of a high-efficiency internal combustion engine capable of stabilizing combustion and suppressing NO.sub.x emissions without unnecessarily increasing a mounting load on an ECU. Therefore, the control device of the internal combustion engine for controlling the internal combustion engine includes an ignition plug that ignites an air-fuel mixture of fuel and air in the combustion chamber, a combustion pressure estimation sensor that detects a combustion pressure in the combustion chamber, and a crank angle sensor that detects a crank angle of a crankshaft. An MBT region is set based on an ignition delay period from an ignition timing of the ignition plug calculated from a detection value of the combustion pressure estimation sensor and a detection value of the crank angle sensor to a combustion start timing in the combustion chamber, and a combustion period from the combustion start timing to a set amount combustion end timing when a set amount of combustion ends. An ignition timing of the ignition plug is controlled so as to fall within the set MBT region.

Embodiments disclosed herein relate generally to systems and methods of operating internal combustion (IC) engines, and more specifically to systems and methods of starting compression ignition (CI) engines when the surrounding environment is significantly colder than the normal operating temperature of the engine (i.e., “cold-starting”). In some embodiments, the CI engine can include an ignition-assist device. In some embodiments, a method of operating a CI engine during cold-start can include opening an intake valve to draw a volume of air into the combustion chamber, moving a piston from a bottom-dead-center position to a top-dead-center position in a combustion chamber at a compression ratio of between about 15 and about 25, injecting a volume of fuel, the fuel having a cetane number of less than about 30, closing the intake valve, and combusting substantially all of the volume of fuel.

Embodiments disclosed herein relate generally to systems and methods of operating internal combustion (IC) engines, and more specifically to systems and methods of starting compression ignition (CI) engines when the surrounding environment is significantly colder than the normal operating temperature of the engine (i.e., “cold-starting”). In some embodiments, the CI engine can include an ignition-assist device. In some embodiments, a method of operating a CI engine during cold-start can include opening an intake valve to draw a volume of air into the combustion chamber, moving a piston from a bottom-dead-center position to a top-dead-center position in a combustion chamber at a compression ratio of between about 15 and about 25, injecting a volume of fuel, the fuel having a cetane number of less than about 30, closing the intake valve, and combusting substantially all of the volume of fuel.