A reduction method for a catalytic converter in an exhaust system of an internal combustion engine for reducing the oxygen content in the catalytic converter, in particular after an overrun fuel cutoff mode of the internal combustion engine, the method including first injection of fuel into a first cylinder, the first injection taking place after an ignition point in time of a compression stroke of a first working cycle of the cylinder and including an introduction of the injected fuel from the cylinder into the catalytic converter during an exhaust stroke of the first cylinder.

A method (200) for determining an amount of hydrocarbons in an exhaust gas (10) downstream of a lean-operation internal-combustion engine (110), comprising the following steps: observing a first catalyst heating mode of the internal-combustion engine (110) at a high catalyst temperature, wherein a predefinable amount of fuel having a predominantly non-combusting portion is introduced into a combustion chamber of the internal-combustion engine (110); determining an actual temperature change downstream of an oxidation catalyst (120) downstream of the internal-combustion engine (110) during the first catalyst heating mode; and determining the amount of hydrocarbons (cHC) in the exhaust gas (10) upstream of the oxidation catalyst (120) based on the actual temperature change. Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

Disclosed is a four-stroke direct injection engine comprising a camshaft, and exhaust valve, and a control system. The control system is configured to change the timing of the camshaft to advance a closing of the exhaust valve, control a first fuel injection step during a compression stroke of the piston, control a second fuel injection step during a power stroke of the piston, and control a third fuel injection step, after the second fuel injection step, during the power stroke of the piston.

When an amount of PM trapped by a GPF is large and a request for regeneration is made, a CPU determines whether an execution condition for executing a temperature increasing process is satisfied. At a point in time t1, at which the execution condition is satisfied, the CPU executes a scavenging process to assign 1 to a condition satisfaction flag Ftr, cause the air-fuel ratio of air-fuel mixture in cylinders #1, #3, and #4 to be the stoichiometric air-fuel ratio, and stop a combustion operation in a cylinder #2. After a point in time t2, which is after a combustion cycle, the CPU executes a temperature increasing process. The temperature increasing process causes the air-fuel ratio of the air-fuel mixture in the cylinders #1, #3, and #4 to be richer than the stoichiometric air-fuel ratio, and stops the combustion operation in the cylinder #2.

Methods and systems are provided for reducing emissions during an engine cold start. In one example, a method may include, during emission control device heating, injecting heated air into an exhaust runner of each cylinder of the engine during an exhaust stroke of the corresponding cylinder, after a blowdown exhaust pulse. In this way, an amount of hydrocarbons in feedgas provided to the emission control device prior to the emission control device reaching its light-off temperature may be reduced.

A controller for an internal combustion engine is configured to execute a temperature-increasing process, a misfire detecting process that detects a misfire, a determining process, and a decreasing process. The temperature-increasing process includes increasing a temperature of a catalyst through a partial cylinder fuel cut-off process. The determining process includes determining whether a number of misfires detected by the misfire detecting process in a number of times combustion control has been executed in each of cylinders is greater than or equal to a given value. The decreasing process includes setting an amount of temperature increase in the catalyst to be smaller when the number of misfires is greater than or equal to the given value than when the number of misfires is less than the given value.

A controller configured to control a hybrid vehicle includes a catalyst temperature increase control unit configured to execute a catalyst temperature increase control of increasing a temperature of a three-way catalyst device, a motoring control of rotating a crankshaft of an internal combustion engine with power of a motor in a state in which combustion of the internal combustion engine is stopped, and a fuel introduction process of introducing unburned air-fuel mixture into an exhaust passage by performing fuel injection in the internal combustion engine during the execution of the motoring control.

A controller for an internal combustion engine, a control method for an internal combustion engine, and a memory medium are provided. The controller determines whether an execution request of a temperature-increasing process for an aftertreatment device for exhaust gas has been issued. When the execution request is determined as having been issued, supply of fuel by a fuel injection valve corresponding to a specified cylinder is deactivated. The specified cylinder is one of cylinders. An air-fuel ratio of air-fuel mixture in a cylinder of the cylinders that differs from the specified cylinder is set to be richer than a stoichiometric air-fuel ratio. When the temperature-increasing process is executed, an adjustment device is operated so as to reduce the fuel concentration in an intake port connected to the specified cylinder.

Methods and systems are provided for reducing emissions during an engine cold start. In one example, a method may include, during emission control device heating, injecting heated air into an exhaust runner of each cylinder of the engine during an exhaust stroke of the corresponding cylinder, after a blowdown exhaust pulse. In this way, an amount of hydrocarbons in feedgas provided to the emission control device prior to the emission control device reaching its light-off temperature may be reduced.

The invention relates to method for operating an internal combustion engine that has at least two combustion chambers, of which at least one is operated at a substoichiometric air-fuel ratio and of which at least another is operated at a superstoichiometric air-fuel ratio. The outlet of the internal combustion engine is connected to an exhaust gas system in which a three-way catalytic converter is arranged in the flow direction of an exhaust gas through an exhaust gas channel, and an exhaust gas heat-recovery device is arranged downstream from the three-way catalytic converter. It is provided for the unburned fuel components of the combustion chamber that is operated at a substoichiometric air-fuel ratio to be exothermally reacted with the residual oxygen from the combustion chamber that is operated at a superstoichiometric air-fuel ratio on the three-way catalytic converter, whereby the exhaust gas temperature is raised so that the exhaust gas heat-recovery device can recover a portion of the exhaust gas enthalpy downstream from the three-way catalytic converter.