Abstract: Methods for operating internal combustion engines and methods for controlling intake air temperature in engines of vehicles are provided. An engine includes an intake system configured to deliver intake air to the internal combustion engine; an exhaust system configured to discharge exhaust gas from the internal combustion engine; and an exhaust gas recirculation (“EGR”) system configured to selectively deliver a portion of the exhaust gas to the intake system. The internal combustion engine is located in an underhood zone; the intake system includes a first intake pipe having an outlet in communication with the intake system and having an inlet located outside of the underhood zone to receive ambient air; and the intake system includes a second intake pipe having an outlet in communication with the intake system and having an inlet located within the underhood zone to receive air warmed by the internal combustion engine.

Abstract: Methods and systems for optimizing fuel economy and maintaining particulate emissions below a threshold of an engine system in a vehicle. An engine system has port fuel injection, direct injection, variable compression ratio, and independent compression/expansion. A processor predicts settings for the four systems that optimize for a fuel economy that is maximized. A particulate rate of the engine system is computed based on the settings. A determination is made of whether the particulate rate is below a threshold. When the particulate rate is below the threshold, command signals are delivered to actuators of the systems to move to the settings. When the threshold is exceeded, the settings are revised to maintain the particulate below the threshold while optimizing for fuel economy.

Abstract: Methods and systems for enabling regeneration of a particulate filter of an engine system are provided. In one embodiment, a method includes: receiving, by a processor, a request for particulate filter regeneration; in response to the request, determining, by the processor, at least one of a compression ratio and an expansion ratio; generating, by the processor, control signals to actuators of the engine system to adjust the at least one of the compression ratio and the expansion ratio to achieve a desired exhaust temperature; generating, by the processor, control signals to actuators of the engine system to optimize torque output based on the desired exhaust temperature, engine speed, and a desired engine load; and initiating, by the processor, regeneration of the particulate filter based on the command signals.