Control device of spark-ignition engine

Patent metadata

Field	Value
Publication number	US-9617945-B2
Application number	US-201414181505-A
Country	US
Kind code	B2
Filing date	Feb 14, 2014
Priority date	Mar 25, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A control device of a spark-ignition engine is provided. The control device includes a main body of the engine, a fuel injection valve, an ignition plug, and a controller. According to an engine operating state, the controller switches between a compression-ignition mode in which compression-ignition combustion is performed, and a spark-ignition mode in which spark-ignition combustion is performed. The controller switches from the spark-ignition mode to the compression-ignition mode by performing in order, a first stage where an air-fuel ratio of mixture gas is set to a predetermined value and the spark-ignition combustion is performed, a second stage where the air-fuel ratio of the mixture gas is set leaner than the first stage and the compression-ignition combustion is performed, and a third stage where the air-fuel ratio of the mixture gas is set richer than the second stage and the compression-ignition combustion is performed.

First claim

What is claimed is:

1. A control device of a spark-ignition engine, comprising:
a main body of the engine having a cylinder;
a fuel injection valve for injecting fuel to be supplied into the cylinder;
an ignition plug for igniting mixture gas within the cylinder;
a controller for operating the engine by controlling at least the fuel injection valve and the ignition plug; and
an internal exhaust gas recirculation (EGR) adjuster for adjusting an exhaust gas amount remaining within the cylinder in a period from exhaust stroke to intake stroke during a compression-ignition mode by controlling at least one of an exhaust valve and an intake valve provided in the main body of the engine,
wherein according to an operating state of the engine, the controller switches an ignition mode between the compression-ignition mode in which compression-ignition combustion is performed by causing the mixture gas to self-ignite and combust, and a spark-ignition mode in which spark-ignition combustion is performed by igniting the mixture gas with the ignition plug to combust the mixture gas,
wherein the controller switches the ignition mode from the spark-ignition mode to the compression-ignition mode by performing in order, a first stage where an air-fuel ratio of the mixture gas is set to a predetermined value and the spark-ignition combustion is performed, a second stage where the air-fuel ratio of the mixture gas is set leaner than the first stage and the compression-ignition combustion is performed, and a third stage where the air-fuel ratio of the mixture gas is set richer than the second stage and the compression-ignition combustion is performed, and
wherein in the first and second stages, the controller operates the internal EGR adjuster to maintain an operating state of the internal EGR adjuster just prior to the first stage in which spark-ignition is performed, and in the third stage, the controller operates the internal EGR adjuster to increase the exhaust gas amount remaining within the cylinder to an amount that is greater than the exhaust gas amount remaining within the cylinder in the second stage.

2. The control device of claim 1 , further comprising an intake valve operating mechanism for operating an intake valve provided in the main body of the engine,
wherein the intake valve operating mechanism is operated in either one of a first mode in which the intake valve is opened and closed with a first lift property and a second mode in which the intake valve is opened and closed with a second lift property, the first lift property with which a fresh air amount is relatively regulated, the second lift property with which the fresh air amount is increased compared to that with the first lift property, and
wherein the controller increases an amount of intake air into the cylinder by operating the intake valve in the first mode in the first stage and operating the intake valve in the second mode in the second stage.

3. The control device of claim 2 , further comprising an internal exhaust gas recirculation (EGR) adjuster for adjusting an exhaust gas amount remaining within the cylinder in a period from exhaust stroke to intake stroke by controlling at least one of an exhaust valve and the intake valve provided in the main body of the engine,
wherein in the first and second stages, the controller stops the operation of the internal EGR adjuster to reduce the exhaust gas amount remaining within the cylinder, and in the third stage, the controller operates the internal EGR adjuster to increase the exhaust gas amount remaining within the cylinder.

4. The control device of claim 1 , wherein the controller sets the air-fuel ratio of the mixture gas to a theoretical air-fuel ratio in the spark-ignition mode including the first stage.

5. The control device of claim 1 , wherein the controller performs the first to third stages in this order in a case of switching from the spark-ignition mode where an engine load is at a predetermined high load, to the compression-ignition mode where the engine load is lower than the predetermined high load.

6. The control device of claim 1 , wherein the controller performs the first to third stages in this order in a case of switching from the spark-ignition mode where an engine load is at a predetermined low load, to the compression-ignition mode where the engine load is at the predetermined low load.

7. The control device of claim 1 , further comprising an external exhaust gas recirculation (EGR) adjuster for circulating exhaust gas discharged from the cylinder to the intake side,
wherein when switching from the spark-ignition mode where the external EGR adjuster is operated to the compression-ignition mode, the controller stops the operation of the external EGR adjuster in the second stage and increases the number of engine cycles of the second stage compared to that when switching from the spark-ignition mode where the external EGR adjuster is not operated to the compression-ignition mode.

8. The control device of claim 7 , wherein when the engine load is at a predetermined low load, the controller controls the ignition mode to be the spark-ignition mode where the external EGR adjuster is not operated, and when the engine load is at a predetermined high load, the controller controls the ignition mode to be the spark-ignition mode where the external EGR adjuster is operated.

Assignees

• Mazda Motor

Inventors

• Takahashi Toshiaki
• Taga Junichi
• Iwai Kouhei

Classifications

• Y02T10/44

  Cross-Sectional Technologies · mapped topic

• Y02T10/47

  Cross-Sectional Technologies · mapped topic

• F02D41/3035

  a mode being the premixed charge compression-ignition mode · CPC title

• F02M26/28

  with liquid-cooled heat exchangers · CPC title

• F02D41/3011

  according to or using specific or several modes of combustion · CPC title