A combustion mode module is configured to switch operation of a low-temperature combustion (LTC) engine between a spark ignition (SI) mode, a positive valve overlap (PVO) mode, and a negative valve overlap (NVO) mode. A spark control module is configured to control a spark plug to generate a spark in a cylinder of the LTC engine when the LTC engine is operating in the SI mode. A valve control module is configured to control intake and exhaust valves of the cylinder to yield a PVO and a NVO when the LTC engine is operating in the PVO mode and the NVO mode, respectively. An air/fuel (A/F) control module is configured to adjust a desired A/F ratio of the LTC engine to a rich A/F ratio when operation of the LTC engine is switched to the PVO mode from either one of the SI mode and the NVO mode.

A variety of methods and arrangements are described for determining a pilot injection mass during skip fire operation of an internal combustion engine.

A variety of methods and arrangements are described for determining a pilot injection mass during skip fire operation of an internal combustion engine.

A method of operating a hydrogen-fueled internal combustion engine. The engine is determined to have a mode control value, which represents a threshold torque. During operation of the engine, a demanded torque of the internal combustion engine is determined and compared to the threshold torque. If the demanded torque is less than the threshold torque, the engine is operated in a low load mode that uses spark ignition and pre-mixed combustion. If the demanded torque is greater than the threshold torque, the engine is operated in a high load mode that uses compression ignition and diffusion combustion.

Provided are an exhaust purification device and an exhaust purification method which can achieve improved fuel efficiency. The exhaust purification device (100) is equipped with: a DOC (5) for occluding hydrocarbons in an exhaust gas; a DPF (6) that is provided downstream from the DOC (5) and is for trapping particulate matter in the exhaust gas; and an ECU (10) for determining, in accordance with the amount of occluded hydrocarbons in the DOC (5), a start time for a regeneration process for removing particulate matter accumulated in the DPF (6).

Operating a direct-injection compression-ignition engine includes injecting early pilot shots of fuel, and controlling a cylinder temperature timing to combust the early pilot shots according to a combustion phasing that is based on the cylinder temperature timing. A main charge of the fuel is combusted based on the combustion of the early pilot shots. A combustion control unit is structured to command actuation of a fuel injector and a cylinder temperature controller to phase combustion of early pilot shots of the fuel, prior to a TDC position of a piston in an engine cycle. The cylinder temperature controller is a variable valve actuator or other apparatus controlling cylinder temperature in a manner decoupled from piston position.

An engine combustion chamber structure includes a combustion chamber of an engine and a fuel injection valve. The fuel injection valve injects fuel toward a cavity in a crown face of a piston. The cavity includes a first cavity provided in a radially central region of the crown face with a first bottom having a first depth, a second cavity provided in an outer side of the first cavity with a second bottom having a second depth being smaller than the first depth, a connecting portion, and a standing wall region disposed further in a radially outer side than the second bottom of the second cavity. The second bottom is provided lower than an upper end, of the connecting portion. A lower section of the standing wall region is provided further in a radially inner side than an upper edge of the standing wall region.

In a compression-ignition engine having a two-stage cavity, the distribution ratio between fuel for an upper cavity and fuel for a lower cavity is maintained even when the operational state of the engine changes. A piston of the compression-ignition engine includes a lower cavity, an upper cavity, and a lip portion between the lower cavity and the upper cavity. A controller causes a main injection and at least one pilot injection to be executed when the engine operates in a first state and a second state in which the load is higher than the load in the first state. The fuel spray is distributed to the lower cavity and the upper cavity. The controller causes a ratio of injection amount per pilot injection to the total injection amount to be higher when the engine operates in the second state than when the engine operates in the first state.

A fuel injection control method of injecting fuel to a combustion chamber through an injector, the method may include performing, by a controller electrically-connected to the injector, a main injection configured of controlling the injector to inject the fuel in a target injection fuel amount; and performing, by the controller, a pre-injection configured of driving the injector to inject the fuel in advance, before the performing of the main injection with a predetermined idle time interposed therebetween, wherein the performing of the pre-injection is configured of magnetizing an injector coil of the injector by applying a current to the injector during a predetermined pre-injection time, in which a flow rate of the fuel is prevented from being generated by the pre-injection.

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.