A determination is made whether or not the condition that the amount V of condensed water remaining in an intake passage has exceeded a predetermined upper limit has been met, based on an input parameter associated with the amount V. If, during an engine operation in an unsupercharged mode, a determination is made that the condition has been met, a condensed water discharging operation of a supercharger is performed such that the condensed water remaining is discharged to a cylinder of the engine through operation of the supercharger.

An engine system capable of controlling an intake air flow includes a combustion chamber, an ignition plug, an intake air flow control valve, and a controller. The controller performs, in at least a part of an operating range, SPCCI combustion in which after jump-spark ignition combustion of a portion of a mixture gas inside the combustion chamber by a jump-spark ignition of the ignition plug, compression ignition combustion of the remaining mixture gas is carried out by a self-ignition. The controller strengthens, at least in a part of the operating range of SPCCI combustion, the intake air flow inside the combustion chamber by controlling the intake air flow control valve. The controller controls, in a middle-load range of the operating range where SPCCI combustion is performed, the intake air flow control valve so that the intake air flow becomes weaker than in a high-load range and a low-load range.

Substances in external EGR gas are smoothly guided to a combustion chamber. An intake passage includes: a main intake passage including intake ports and communicating with a combustion chamber and having a supercharger interposed in the main intake passage; and a bypass passage branching off from the main intake passage upstream of the supercharger, and connected downstream of the supercharger; a flow rage adjustment valve changing a cross-sectional flow area of the bypass passage. The bypass passage is provided above the main intake passage, and includes an upper passage to which an EGR passage is connected.

Substances in external EGR gas are smoothly guided to a combustion chamber. An intake passage includes: a main intake passage including intake ports and communicating with a combustion chamber and having a supercharger interposed in the main intake passage; and a bypass passage branching off from the main intake passage upstream of the supercharger, and connected downstream of the supercharger; a flow rage adjustment valve changing a cross-sectional flow area of the bypass passage. The bypass passage is provided above the main intake passage, and includes an upper passage to which an EGR passage is connected.

A method of implementing control logic of a compression-ignition engine is provided. A control part of the engine performs a calculation according to the control logic corresponding to an engine operating state in response to a measurement of a measurement part, controls a fuel injection part, a variable valve operating mechanism, an ignition part and a supercharger so that a G/F becomes leaner than a stoichiometric air fuel ratio and a A/F becomes equal to or richer than the stoichiometric air fuel ratio, while causing the supercharger to boost, and controls the ignition part so that unburnt mixture gas combusts by self-ignition after the ignition. The method includes determining a supercharging pressure P, and determining control logic defining a close timing IVC of an intake valve. When determining the control logic, the close timing IVC (deg.aBDC) is determined so that the supercharging pressure P (kPa) satisfies the following expression: P8.010.sup.11IVC.sup.61.010.sup.8IVC.sup.5+3.010.sup.7IVC.sup.44.010.sup.6IVC.sup.3+0.0068IVC.sup.20.3209IVC+116.63.

An electric supercharger includes an electric motor, a compressor wheel rotated by the electric motor, and a compressor housing. The compressor housing includes a first passage through which air is introduced, an introducing port connecting to an EGR device, a second passage through which at least one of air and EGR gas is flowed, a bypass passage through which at least one of air and EGR gas is flowed, and a bypass valve to open and close the bypass passage. When the bypass valve is opened, air introduced from the first passage and EGR gas introduced from the introducing port are flowed through the bypass passage to the internal combustion engine. When the bypass valve is closed, air introduced from the first passage and EGR gas introduced from the introducing port are compressed in the compressor wheel and flowed through the second passage to the internal combustion engine.

An electric supercharger includes an electric motor, a compressor wheel rotated by the electric motor, and a compressor housing. The compressor housing includes a first passage through which air is introduced, an introducing port connecting to an EGR device, a second passage through which at least one of air and EGR gas is flowed, a bypass passage through which at least one of air and EGR gas is flowed, and a bypass valve to open and close the bypass passage. When the bypass valve is opened, air introduced from the first passage and EGR gas introduced from the introducing port are flowed through the bypass passage to the internal combustion engine. When the bypass valve is closed, air introduced from the first passage and EGR gas introduced from the introducing port are compressed in the compressor wheel and flowed through the second passage to the internal combustion engine.

A secondary air injection system may include an engine that includes a plurality of cylinders that generate a driving torque of a vehicle by combustion of a fuel; a main line connected to an exhaust manifold or an exhaust line which is connected to the plurality of cylinders; a recirculation line which is branched from the main line and then connected to an intake manifold; an air injection line which is branched from the main line and then connected to an intake line; and an electric supercharger which is provided in the intake line.

A secondary air injection system may include an engine that includes a plurality of cylinders that generate a driving torque of a vehicle by combustion of a fuel; a main line connected to an exhaust manifold or an exhaust line which is connected to the plurality of cylinders; a recirculation line which is branched from the main line and then connected to an intake manifold; an air injection line which is branched from the main line and then connected to an intake line; and an electric supercharger which is provided in the intake line.

In an air handling system of an opposed-piston engine, mass airflow sensor operation is monitored by comparing mass airflow measured by the sensor with mass airflow through a supercharger.