An imbalance detection device is provided. An obtainment process includes obtaining a rotation waveform variable based on a detection value of a sensor that detects a rotational behavior of a crankshaft, and an air-fuel ratio detection variable in each of a plurality of first intervals. A calculation process includes calculating an imbalance variable based on an output of a mapping having a value obtained by the obtainment process as an input. The imbalance variable indicates a degree of variations in an air-fuel ratio of the internal combustion engine. The rotation waveform variable indicates a difference between instantaneous speed variables that are variables corresponding to the rotational speed of the crankshaft in each of the second intervals.

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.

An engine system may include an engine including a plurality of combustion chambers for generating a driving force by combustion of fuel, an exhaust gas purification device mounted in an exhaust line through which exhaust gas discharged from the combustion chamber flows, an EGR gas collecting device configured for collecting a part of the exhaust gas from an exhaust manifold of the engine and supplying the exhaust gas to an intake manifold of the engine, and an EGR gas supply control valve provided between the EGR gas collecting device and the intake manifold and adapted to regulate a flow rate of EGR gas supplied to the intake manifold.

An engine system may include an engine including a plurality of combustion chambers for generating a driving force by combustion of fuel, an exhaust gas purification device mounted in an exhaust line through which exhaust gas discharged from the combustion chamber flows, an EGR gas collecting device configured for collecting a part of the exhaust gas from an exhaust manifold of the engine and supplying the exhaust gas to an intake manifold of the engine, and an EGR gas supply control valve provided between the EGR gas collecting device and the intake manifold and adapted to regulate a flow rate of EGR gas supplied to the intake manifold.

A charging device may include a turbine housing and a wastegate valve device. The wastegate valve device may include a flap, a spindle arm, a wastegate spindle, an axial stop, and a lever arm non-rotatably attached to the wastegate spindle. The wastegate spindle may be rotatably mounted in a bushing disposed on the turbine housing. A wastegate duct may be disposed in the turbine housing. The wastegate duct may have a duct aperture enclosed by a valve seat. The duct aperture, when in a closed state, may be closed by the flap of the wastegate valve device. A sealing face of the flap may be defined by a sequence of at least two conical peripheral surfaces arranged next to one another and each having a different inclination.

Methods and systems are provided for exhaust gas heat recovery at an exhaust gas heat exchanger. Exhaust gas may flow in both directions through an exhaust bypass passage and the heat exchanger coupled to the bypass passage. Hot or cold EGR may be delivered from the exhaust passage to the engine intake manifold and heat from the exhaust gas may be recovered at the heat exchanger.

Methods and systems are provided for exhaust gas heat recovery at an exhaust gas heat exchanger. Exhaust gas may flow in both directions through an exhaust bypass passage and the heat exchanger coupled to the bypass passage. Hot or cold EGR may be delivered from the exhaust passage to the engine intake manifold and heat from the exhaust gas may be recovered at the heat exchanger.

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.