Mazda Motor Corporation

Kouji Sumida

Takayoshi Hayashi

Mitsuo Hitomi

Toshiaki Nishimoto

Taketoshi Yamauchi

Yoshiyuki Shinya

Kouji Asanomi

Masahisa Yamakawa

Keiji Araki

Noriyuki Iwata

Satoru Matsuzaki

Hiroyuki Maeda

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 cylindersA,D 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 passageinto following cylindersB,C on the intake stroke side and only gas exhausted from the following cylindersB,C is fed to an exhaust passage, which is provided with a three-way catalyst. Combustion controller is provided that controls the combustion of each of the cylinders such that combustion is conducted by forced ignition in a condition in which the air/fuel ratio is a lean air/fuel ratio which is larger by a prescribed amount than the stoichiometric air/fuel ratio in the preceding cylindersA,D and, in the following cylindersB,C, fuel is supplied to burnt gas of lean air/fuel ratio introduced from the preceding cylindersA,D and combustion is conducted by compression ignition.

Spark ignition engine control device

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 (A,D) which is currently in the exhaust stroke is introduced directly into the following cylinder (B,C) which is currently in the intake stroke through an intercylinder gas channel () and gas discharged from only the following cylinder (B,C) is led to an exhaust passage () provided with a three-way catalyst () in a low-load, low-speed operating range. Fuel supply to the individual cylinders is controlled in such a manner that combustion in the preceding cylinder (A,D) is made under lean mixture conditions at an air-fuel ratio larger than the stoichiometric air-fuel ratio by a specific amount and combustion in the following cylinder (B,C) is made under conditions of the stoichiometric air-fuel ratio created by supplying fuel to the burned gas introduced from the preceding cylinder (A,D).

Control device for spark-ignition engine

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.

Spark-ignition engine controller

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.

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. At engine startup, the flow path switching unit switches the engine to the independent cylinder configuration to perform combustion in normal operation mode.

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.

Growing community of inventors

Fuchu-cho, Japan

Kouji Sumida