A method of transient control for enrichment operation in a low-temperature combustion engine. The method includes determining if a current mode of the low-temperature combustion (LTC) engine is a positive valve overlap (PVO) mode. Determining if a previous mode of the LTC engine was also the PVO mode when the current mode is the PVO mode, wherein the previous mode is immediately prior to the current mode. Determining if the previous mode of the LTC engine was a negative valve overlap (NVO) mode when the previous mode was not the PVO mode. Initiating a predetermined enrichment PVO mode for the LTC engine based on the previous mode of the LTC engine. The predetermined enrichment PVO mode includes initiating a deep enrichment PVO mode, when the previous mode of the LTC engine was the NVO mode, and initiating a shallow enrichment PVO mode, when the previous mode of the LTC engine was not the NVO mode.

A method of transient control for enrichment operation in a low-temperature combustion engine. The method includes determining if a current mode of the low-temperature combustion (LTC) engine is a positive valve overlap (PVO) mode. Determining if a previous mode of the LTC engine was also the PVO mode when the current mode is the PVO mode, wherein the previous mode is immediately prior to the current mode. Determining if the previous mode of the LTC engine was a negative valve overlap (NVO) mode when the previous mode was not the PVO mode. Initiating a predetermined enrichment PVO mode for the LTC engine based on the previous mode of the LTC engine. The predetermined enrichment PVO mode includes initiating a deep enrichment PVO mode, when the previous mode of the LTC engine was the NVO mode, and initiating a shallow enrichment PVO mode, when the previous mode of the LTC engine was not the NVO mode.

An engine management system and method may include a control system and method for controlling an internal combustion engine. The internal combustion engine may be a direct-injection engine using a Sonex Controlled Auto-Ignition (“SCAI”) combustion path. The control system and method may utilize fuel injection pressure, timing of start and end of injection, management of turbo airflow, fuel supplied, and other factors to provide reduced emissions and improved performance.

A conventional gasoline engine is retrofitted and calibrated to operate as a bi-fuel engine using Hydrogen as the second fuel. When operated with Hydrogen, which typically leads to a reduction of engine output power, the engine is preferably operated in a charged mode and in a lean mode with the engine throttle kept in a wide-open position during charged and lean mode operation resulting in a more efficient engine with a reduction of engine output power loss.

A system and method for a variable displacement internal combustion engine using different types of pneumatic cylinder springs on skipped working cycles to control engine and aftertreatment system temperatures are described. The system and method may be used to rapidly heat up the aftertreatment system(s) and/or an engine block of the engine following a cold start by using one or more different types of pneumatic cylinder springs during skipped firing opportunities. By rapidly heating the aftertreatment system(s) and/or engine block, noxious emissions such as hydrocarbons, carbon monoxide, NO.sub.x and/or particulates, following cold starts are significantly reduced.

A compression ignition (diesel) engine uses two or more fuel charges during a combustion cycle, with the fuel charges having two or more reactivities (e.g., different cetane numbers), in order to control the timing and duration of combustion. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot). At low load and no load (idling) conditions, the aforementioned results are attained by restricting airflow to the combustion chamber during the intake stroke (as by throttling the incoming air at or prior to the combustion chamber's intake port) so that the cylinder air pressure is below ambient pressure at the start of the compression stroke.

The method for controlling the operation of an internal combustion engine comprises at least two operating modes. In a first operating mode, the intake valve is closed at a first predetermined crank angle, in accordance with the Miller cycle, before the piston reaches bottom dead center during the intake stroke for reducing pressure in the cylinder, and fuel is injected using first fuel injection means optimized for large amounts of fuel. In a second operating mode the intake valve is closed at a second predetermined crank angle, in accordance with conventional intake valve closing timing, after or slightly before the piston has passed bottom dead center, and fuel is injected using second fuel injection means optimized for small amounts of fuel. The invention also concerns an internal combustion engine.

A control system of an internal combustion engine which performs diffusion combustion by compression autoignition on fuel injected in a main injection in at least a partial operating range and which performs stratified combustion by spark ignition using a spark plug on fuel injected prior to the main injection. The control system determines whether or not the diffusion combustion occurs and performs combustion by spark ignition using the spark plug on the fuel injected in the main injection when it is determined that the diffusion combustion does not occur.

Systems and methods for improving operation of a hybrid vehicle are presented. In one example, driveline oscillations are reduced during engine air-fuel ratio modulation. The driveline oscillations may be reduced via adjusting torque of a motor.

A remaining fuel amount warning device for a vehicle, the remaining fuel amount warning device giving a warning that an amount of fuel remaining in a fuel tank is smaller than a predetermined value on the basis of output of a fuel gauge measuring the remaining fuel amount, includes combustion state changing device for changing the combustion state of an engine. When the remaining fuel amount becomes smaller than the predetermined value, the remaining fuel amount warning device performs remaining amount warning control that produces vibration different than during normal operation by changing the combustion state of the engine by the combustion state changing device. A starter switch for starting the engine is made to serve also as a warning acknowledging button for stopping the remaining amount warning control for a predetermined time on the basis of an operation by an occupant.