An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders, an air intake system to provide air to the plurality of cylinders through respective ones of a plurality of intake valves, an exhaust system to release exhaust gas from the plurality of cylinders through respective one of a plurality of exhaust valves. A valve train is provided for cylinder deactivation of a first part of the plurality of cylinders and compression release braking on a second part of the plurality of cylinders.

An engine system is provided, including a controller which controls devices of an engine at a given engine speed so that, when a demanded engine load is a first load, a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel is a first G/F and mixture gas inside the cylinder combusts by flame-propagation, when the demanded load is a second load (<the first load), the G/F is a second G/F (>the first G/F) and an injection center-of-gravity is at a timing such that the entire mixture gas combusts by CI combustion, and when the demanded load is between the first and second loads, the G/F is at a third G/F (between the first and second G/Fs) and the injection center-of-gravity is at a later timing such that at least part of the mixture gas combusts by the CI combustion.

A method for determining a combination of an actual intake camshaft phase position of an intake camshaft and an actual exhaust camshaft phase position of an exhaust camshaft of a production internal combustion engine having at least one cylinder, wherein the method is performed in operation of the production internal combustion engine and the relevant actual phase position of the camshafts is determined in relation to an operating point of the production internal combustion engine.

Methods and systems are provided for re-combustion of exhaust in a cylinder of a multi-cylinder engine in order to increase the temperature of the exhaust for enhancing catalytic conversion within the multi-cylinder engine. In one example, a method may include expelling combusted gases from the cylinder into an intake manifold via an intake valve during an exhaust stroke, in order to rebreathe in the combusted gases from the intake manifold via the intake valve in a subsequent intake stroke.

A control method can be used for securing continuously variable valve duration (CVVD) startability when a CVVD error is recognized by a CVVD controller during an operation of a CVVD system. The control method includes performing engine startability securing control for solving the CVVD error by applying a starting air volume to starting of an engine through at least one of a valve position fixing value, a valve position threshold, or an immediately previous valve position value.

Methods and systems are provided for providing secondary air to an exhaust system during catalyst warm-up. In one example, a method may include, during a cold start condition, operating an engine with a first number of cylinders unfired and a remaining number of cylinders fired during an engine cycle, opening an intake valve of an unfired cylinder of the first number of cylinders during an expansion stroke of the unfired cylinder, and opening an exhaust valve of the unfired cylinder during a compression stroke of the unfired cylinder. In this way, the unfired cylinders may provide the secondary air to the exhaust system during a stroke that increases mixing of the secondary air with burned exhaust gas from fired cylinders, thus increasing exotherm production in the exhaust system to increase a temperature of the catalyst.

To provide a controller and a control method for internal combustion engine which can set appropriately an angle interval for estimating the combustion state in accordance with change of a burning angle interval, and can reduce calculation processing load for estimation of the combustion state. A controller for internal combustion engine changes the estimation crank angle interval based on an operating condition of the internal combustion engine; calculates an increment of gas pressure torque by burning at each crank angle of the estimation crank angle interval; and estimates the combustion state of the internal combustion engine, based on the increment of gas pressure torque by burning in the estimation crank angle interval.

Methods and systems are provided for re-combustion of exhaust in a cylinder of a multi-cylinder engine in order to increase the temperature of the exhaust for enhancing catalytic conversion within the multi-cylinder engine. In one example, a method may include expelling combusted gases from the cylinder into an intake manifold via an intake valve during an exhaust stroke, in order to rebreathe in the combusted gases from the intake manifold via the intake valve in a subsequent intake stroke.

A control device for an engine is provided, which includes a combustion chamber formed by a cylinder and a piston, an intake air amount adjuster that adjusts an intake air amount supplied to the combustion chamber, a controller switchable of a combustion mode between a fuel-lean first combustion mode and a stoichiometric second combustion mode based on an engine operating state, and an intake air cooler that cools the intake air supplied to the combustion chamber. The controller controls the intake air cooler to start intake air cooling in response to a request for switching the combustion modes, and after the intake air cooling is started, controls the intake air amount adjuster to start the switching of the combustion modes, and then controls the intake air cooler and the intake air amount adjuster so that the switching of the combustion modes ends after the intake air cooling is finished.

Methods and systems are provided for providing secondary air to an exhaust system during catalyst warm-up. In one example, a method may include, during a cold start condition, operating an engine with a first number of cylinders unfired and a remaining number of cylinders fired during an engine cycle, opening an intake valve of an unfired cylinder of the first number of cylinders during an expansion stroke of the unfired cylinder, and opening an exhaust valve of the unfired cylinder during a compression stroke of the unfired cylinder. In this way, the unfired cylinders may provide the secondary air to the exhaust system during a stroke that increases mixing of the secondary air with burned exhaust gas from fired cylinders, thus increasing exotherm production in the exhaust system to increase a temperature of the catalyst.