Control apparatus for compression-ignition type engine

Patent metadata

Field	Value
Publication number	US-11313269-B2
Application number	US-201917051511-A
Country	US
Kind code	B2
Filing date	Apr 17, 2019
Priority date	May 2, 2018
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

The invention is provided with an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes an injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Timing of the preceding ignition is set to be more retarded when an engine speed is high than when the engine speed is low.

First claim

The invention claimed is:

1. An apparatus for controlling a compression-ignition type engine that includes: a cylinder; an injector that injects fuel into the cylinder; and an ignition plug that ignites air-fuel mixture, in which fuel injected from injector and air are mixed, and that can carry out partial compression ignition combustion to subject some of the air-fuel mixture to SI combustion by spark ignition using the ignition plug, and subject the rest of the air-fuel mixture to CI combustion by self-ignition, the control apparatus for the compression-ignition type engine comprising:
an injection control section that controls fuel injection operation by the injector; and
an ignition control section that controls ignition operation by the ignition plug,
wherein, when the partial compression ignition combustion is carried out, the ignition control section causes the ignition plug to carry out: main ignition in which a spark is generated in a period comprising a late period of a compression stroke and an initial period of an expansion stroke to initiate the SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition,
wherein, when the partial compression ignition combustion is carried out, the injection control section causes the injector to inject the fuel at such timing that the fuel exists in the cylinder at an earlier time point than the preceding ignition, and
wherein timing of the preceding ignition is set to be more retarded when an engine speed is high than when the engine speed is low.

2. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein energy of the preceding ignition is lower than energy of the main ignition.

3. The control apparatus for the compression-ignition type engine according to claim 2 ,
wherein the energy and the timing of the preceding ignition are set to such energy and such timing that a high-temperature portion at equal to or higher than 850 K and lower than 1140 K is generated around the spark generated from the ignition plug and that flame propagation of the air-fuel mixture does not occur.

4. The control apparatus for the compression-ignition type engine according to claim 3 ,
wherein the ignition control section controls the ignition plug such that the timing of the preceding ignition is retarded with an increase in the engine speed, and sets a change rate of the timing of the preceding ignition with respect to the engine speed to be constant regardless of the engine speed.

5. The control apparatus for the compression-ignition type engine according to claim 4 ,
wherein the ignition control section sets the change rate of the timing of the preceding ignition with respect to the engine speed to be substantially the same even when an engine load varies.

6. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the timing of the preceding ignition is set during an intake stroke or in an early period or a middle period of the compression stroke.

7. The control apparatus for the compression-ignition type engine according to claim 6 ,
wherein the preceding ignition and the main ignition are carried out by the single ignition plug having a single ignition circuit for each of the cylinders.

8. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the number of the preceding ignition in one cycle is set to three or less.

9. The control apparatus for the compression-ignition type engine according to claim 1 further comprising:
an openable/closable swirl valve that is provided in an intake port communicating with the cylinder,
wherein an opening degree of the swirl valve is controlled such that a swirl ratio in the cylinder becomes equal to or higher than 1.5 in an operation range where the preceding ignition and the main ignition are carried out.

10. The control apparatus for the compression-ignition type engine according to claim 1 further comprising:
a setting section that sets a target SI rate as a target value of a ratio of a heat generation amount by the SI combustion to a total heat generation amount in one cycle according to an engine operation condition,
wherein the ignition control section sets timing of the main ignition on the basis of the target SI rate that is set by the setting section.

11. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the ignition control section carries out the preceding ignition and the main ignition only in a portion on a low-load side of the operation range where the partial compression ignition combustion is carried out.

12. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein, in the operation range where the preceding ignition and the main ignition are carried out, the partial compression ignition combustion is carried out under lean A/F environment where an air-fuel ratio as a ratio between the air and the fuel in the cylinder exceeds 20 and is lower than 35, or the partial compression ignition combustion is carried out under lean G/F environment where a gas air-fuel ratio as a ratio between entire gas and the fuel in the cylinder exceeds 18 and is lower than 50 and the air-fuel ratio substantially matches a stoichiometric air-fuel ratio.

13. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the injection control section causes the injector to carry out second injection, in which the fuel is injected prior to the preceding ignition, and first injection, in which the fuel is injected prior to said second injection.

14. The control apparatus for the compression-ignition type engine according to claim 13 ,
wherein the injection control section controls the injector such that a fuel injection amount by the first injection is larger than a fuel injection amount by the second injection.

Assignees

• Mazda Motor

Inventors

• Matsumoto Kota
• Urushihara Tomonori
• Maruyama Keiji
• SUEOKA Masanari
• Ono Ryohei
• Harada Yuji
• Miyamoto Toru
• Inoue Atsushi
• Tokunaga Tatsuhiro
• Ohura Takuya
• Kawai Yusuke
• Nishida Tomohiro
• Arai Keita
• Yamaguchi Yodai

Classifications

• F02B1/12

  with compression ignition (with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00) · CPC title

• F02B23/08

  with positive ignition · CPC title

• F02B31/06

  Movable means, e.g. butterfly valves · CPC title

• F02B23/10

  with separate admission of air and fuel into cylinder · CPC title

• F02P15/08

  having multiple-spark ignition, i.e. ignition occurring simultaneously at different places in one engine cylinder or in two or more separate engine cylinders · CPC title