An engine system is provided, including a controller which estimates an intake-valve-closing temperature inside a cylinder. When an engine operates at a given speed and a demanded engine load is a first load or a second load (>the first load), the controller controls so that a mixture gas inside the cylinder combusts by compression ignition, and controls so that, at the first load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a first temperature, and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the first temperature, whereas at the second load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a second temperature (<the first temperature), and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the second temperature.

A two-stroke engine (4) has a throttle motor (22) for driving a throttle valve (20), a fuel injection device (430) disposed in an intake system (18) including a crank chamber (420), and a control unit (24) controlling the throttle motor (22) and the fuel injection device. The two-stroke engine (4) is designed to achieve an engine rotation speed of 4,500 rpm to 7,000 rpm when the throttle valve (20) is fully open. The two-stroke engine (4) is operated with the throttle full open by the control unit (24), and a battery (8) is charged with electric power generated by a generator (6) using the two-stroke engine.

In a method for determining an optimized fuel injection profile in an internal combustion engine, a setpoint combustion profile is firstly defined. Furthermore, at least one influential parameter which influences the setpoint combustion profile is determined. With the influential parameter, a corrected fuel injection profile is determined in a closed-loop control process. This method is preferably repeated iteratively.

A two-stroke engine (4) has a throttle motor (22) for driving a throttle valve (20), a fuel injection device (430) disposed in an intake system (18) including a crank chamber (420), and a control unit (24) controlling the throttle motor (22) and the fuel injection device. The two-stroke engine (4) is designed to achieve an engine rotation speed of 4,500 rpm to 7,000 rpm when the throttle valve (20) is fully open. The two-stroke engine (4) is operated with the throttle full open by the control unit (24), and a battery (8) is charged with electric power generated by a generator (6) using the two-stroke engine.

An engine system is provided, including a controller which estimates a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel, and controls devices of an engine at a given engine speed so that, while a demanded engine load is a first load, at least part of a mixture gas inside the cylinder combusts by flame-propagation when the estimated G/F is below a first G/F, and the entire mixture gas combusts by compression ignition when the estimated G/F is above the first G/F, whereas while the demanded load is a second load (>the first load), at least part of the mixture gas combusts by flame-propagation when the estimated G/F is below a second G/F (<the first G/F), and the entire mixture gas combusts by compression ignition when the estimated G/F is above the second G/F.

A method for identifying a fuel injector characteristic may include generating a signal to supply electrical current to the fuel injector, and monitoring the electrical current supplied to the fuel injector. The method may also include identifying the characteristic of the fuel injector based on the electrical current, the characteristic including a type of fuel injector, and performing a corrective action based on the type of fuel injector which was identified based on the electrical current.

A method for controlling starting of a mild hybrid vehicle includes receiving a starting-request signal and in response, increasing a rotation speed of the engine by driving the MHSG by electricity supplied from a battery. Status data of the mild hybrid vehicle for controlling starting of the engine is monitored to obtain an engine rotation speed from the status data and determine an injection-starting rotation speed based on the status data. When the engine rotation speed is greater than the injection-starting rotation speed, fuel injection of the engine is started.

A method and apparatus for controlling part load mode engine torque are provided. The method includes setting a limitation of part load mode engine torque based on a current traveling environment and calculating a first engine torque variation in the basis of state information of a battery. When the first engine torque variation is calculated, a second engine torque variation is calculated based on a measured engine error amount. The limitation of part load mode engine torque is compensated based on the calculated first and second engine torque variations.

Methods and systems are provided for reducing a potential for release of undesired evaporative emissions to atmosphere for vehicles that rely primarily on an electric-only mode of operation for vehicle propulsion. In one example, a method may include in response to a vehicle-on request via a driver of a vehicle, maintaining off a fuel pump that supplies a fuel to a set of port fuel injectors, and re-pressurizing the set of port fuel injectors via operation of the fuel pump based on a predicted engine-start request during a drive cycle following the vehicle-on request. In this way, escape of fuel from pressurized port fuel injectors may be reduced or avoided during engine-off conditions, which may reduce opportunity for release of undesired evaporative emissions to atmosphere.

A vehicular internal combustion engine system includes an internal combustion engine and an electric intake air supply device. The internal combustion engine is shifted into a stoichiometric combustion mode, and a lean combustion mode. The electric intake air supply device is driven by an on-vehicle battery, and employed to contribute a part of intake air quantity at least under a specific operating condition when in the lean combustion mode. A control method includes: determining an electric energy of the electric intake air supply device that is required to maintain achievement of a target air fuel ratio of the lean combustion mode when in a lean combustion operation region; and causing a shift from the lean combustion mode into a stoichiometric combustion mode when the on-vehicle battery is in an insufficient state of charge with respect to the electric energy.