Abstract: For the purpose of improving the fuel efficiency by lean combustion and enhancing the fuel efficiency improvement effects by performing compression ignition efficiently in some cylinders, a multi-cylinder spark ignition engine is constructed such that exhaust gas, that is exhausted from preceding cylinders 2A, 2D on the exhaust stroke side among pairs of cylinders whose exhaust stroke and intake stroke overlap in a low load, low rotational speed region, is directly introduced through an inter-cylinder gas passage 22 into following cylinders 2B, 2C on the intake stroke side and only gas exhausted from the following cylinders 2B, 2C is fed to an exhaust passage 20, which is provided with a three-way catalyst 24.

Abstract: The invention is intended to provide improved emission-cleaning performance by use of a three-way catalyst alone, without the need for a lean NOx catalyst, while ensuring a fuel economy improvement effect of lean burn operation. A multicylinder spark-ignition engine is constructed such that, in a pair of preceding and following cylinders whose exhaust and intake strokes overlap each other, burned gas discharged from the preceding cylinder (2A, 2D) which is currently in the exhaust stroke is introduced directly into the following cylinder (2B, 2C) which is currently in the intake stroke through an intercylinder gas channel (22) and gas discharged from only the following cylinder (2B, 2C) is led to an exhaust passage (20) provided with a three-way catalyst (24) in a low-load, low-speed operating range.

Abstract: Burned gas discharged from an exhaust stroke side preceding cylinder of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced as is into an intake stroke side following cylinder through an intercylinder gas channel, and only the gas which is discharged from the following cylinder is led into an exhaust passage. Particularly during low loads and idling, combustion is performed in the preceding cylinder at an ultra-lean air-fuel ratio of at least three times the stoichiometric air-fuel ratio, and in the following cylinder, combustion is performed by spark ignition at a substantially stoichiometric air-fuel ratio by feeding fuel to the burned gas introduced from the preceding cylinder. In the following cylinder, combustion is performed through compression ignition in accordance with increases in the load.

Abstract: A control device for a spark-ignition engine, in which a mixture in a combustion chamber is fired by compression ignition in a part-load range under warm-running conditions, includes an EGR controller incorporating a valve operation controller for controlling internal EGR of hot burned gas and a cold EGR controller for controlling external EGR of cold burned gas. The EGR controller performs EGR control operation to leave the hot EGR gas in the combustion chamber in a lower-load, lower-speed region within a compression ignition combustion range and to introduce the cold EGR gas into the combustion chamber in a higher-load, higher-speed region within the compression ignition combustion range. The control device further includes a firing assist unit for inducing the compression ignition at least when ignitability of the mixture decreases due to introduction of the cold EGR gas in the compression ignition combustion range.

Abstract: A control device for a multicylinder spark-ignition engine includes a flow path switching unit for switching intake and exhaust flow paths between a two-cylinder interconnect configuration and an independent cylinder configuration and an air-fuel ratio control unit. In a low-load, low-speed operating range, the flow path switching unit switches the engine to the two-cylinder interconnect configuration, and the air-fuel ratio control unit produces a lean mixture having an air-fuel ratio larger than the stoichiometric air-fuel ratio by a specific amount in preceding cylinders by injecting fuel thereinto and an air-fuel ratio approximately equal to the stoichiometric air-fuel ratio in following cylinders by supplying fuel together with burned gas of a lean mixture state discharged from the preceding cylinders into the following cylinders to perform combustion in special operation mode.

Abstract: Intake air/exhaust gas flow control is performed in an partial load range of an engine such that burned gas which is discharged from an exhaust stroke side preceding cylinder of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced into an intake stroke side following cylinder through an intercylinder gas channel. In an operating range set as a special operation mode, a combustion condition controller executes control such that combustion is performed in the following cylinder by means of compression ignition. In an operating condition in which knocking is likely to occur within the compression ignition range of the following cylinder, control is executed by a fuel injection controller such that the timing of fuel injection into the following cylinder is retarded relative to that of an operating condition in which knocking is unlikely to occur.

Abstract: For the purpose of improving the fuel efficiency by lean combustion and enhancing the fuel efficiency improvement effects by performing compression ignition efficiently in some cylinders, a multi-cylinder spark ignition engine is constructed such that exhaust gas, that is exhausted from preceding cylinders 2A, 2D on the exhaust stroke side among pairs of cylinders whose exhaust stroke and intake stroke overlap in a low load, low rotational speed region, is directly introduced through an inter-cylinder gas passage 22 into following cylinders 2B, 2C on the intake stroke side and only gas exhausted from the following cylinders 2B, 2C is fed to an exhaust passage 20, which is provided with a three-way catalyst 24.

Abstract: A control device for a spark-ignition engine, in which a mixture in a combustion chamber is fired by compression ignition in a part-load range under warm-running conditions, includes an EGR controller incorporating a valve operation controller for controlling internal EGR of hot burned gas and a cold EGR controller for controlling external EGR of cold burned gas. The EGR controller performs EGR control operation to leave the hot EGR gas in the combustion chamber in a lower-load, lower-speed region within a compression ignition combustion range and to introduce the cold EGR gas into the combustion chamber in a higher-load, higher-speed region within the compression ignition combustion range. The control device further includes a firing assist unit for inducing the compression ignition at least when ignitability of the mixture decreases due to introduction of the cold EGR gas in the compression ignition combustion range.

Abstract: The invention is intended to provide improved emission-cleaning performance by use of a three-way catalyst alone, without the need for a lean NOx catalyst, while ensuring a fuel economy improvement effect of lean burn operation. A multicylinder spark-ignition engine is constructed such that, in a pair of preceding and following cylinders whose exhaust and intake strokes overlap each other, burned gas discharged from the preceding cylinder (2A, 2D) which is currently in the exhaust stroke is introduced directly into the following cylinder (2B, 2C) which is currently in the intake stroke through an intercylinder gas channel (22) and gas discharged from only the following cylinder (2B, 2C) is led to an exhaust passage (20) provided with a three-way catalyst (24) in a low-load, low-speed operating range.

Abstract: An object of the present invention is to enable combustion to be performed through compression ignition in a following cylinder effectively, in a wider operating range, and while suppressing the occurrence of knocking. Intake air/exhaust gas flow control is performed in a partial load range of an engine such that burned gas which is discharged from an exhaust stroke side preceding cylinder of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced as is into an intake stroke side following cylinder through an intercylinder gas channel. In an operating range set as a special operation mode, a combustion condition controller executes control such that combustion is performed in the following cylinder by means of compression ignition.

Abstract: A control device for a multicylinder spark-ignition engine includes a flow path switching unit for switching intake and exhaust flow paths between a two-cylinder interconnect configuration and an independent cylinder configuration and an air-fuel ratio control unit. In a low-load, low-speed operating range, the flow path switching unit switches the engine to the two-cylinder interconnect configuration, and the air-fuel ratio control unit produces a lean mixture having an air-fuel ratio larger than the stoichiometric air-fuel ratio by a specific amount in preceding cylinders by injecting fuel thereinto and an air-fuel ratio approximately equal to the stoichiometric air-fuel ratio in following cylinders by supplying fuel together with burned gas of a lean mixture state discharged from the preceding cylinders into the following cylinders to perform combustion in special operation mode.

Abstract: An object of the present invention is to improve fuel economy by means of lean combustion, and in particular to improve fuel economy on a low load side and during idling. Burned gas discharged from an exhaust stroke side preceding cylinder of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced as is into an intake stroke side following cylinder through an intercylinder gas channel, and only the gas which is discharged from the following cylinder is led into an exhaust passage. Particularly during low loads and idling, combustion is performed in the preceding cylinder at an ultra-lean air-fuel ratio of at least three times the stoichiometric air-fuel ratio, and in the following cylinder, combustion is performed by spark ignition at a substantially stoichiometric air-fuel ratio by feeding fuel to the burned gas introduced from the preceding cylinder. In the following cylinder, combustion is performed through compression ignition in accordance with increases in the load.