Control apparatus for compression-ignition type engine

Patent metadata

Field	Value
Publication number	US-11326508-B2
Application number	US-201917051636-A
Country	US
Kind code	B2
Filing date	Apr 23, 2019
Priority date	May 2, 2018
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

An engine control apparatus includes an ignition control section and an injection control section. When the 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 a expansion stroke to initiate the 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 the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. The energy of the preceding ignition is set to be higher when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure 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 in-cylinder pressure specification section that specifies an in-cylinder pressure as a pressure in the cylinder;
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 late period of a compression stroke or 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 energy of the preceding ignition is set to be higher when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure is low.

2. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the 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 of the preceding ignition is set to such energy 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 energy of the preceding ignition is increased with an increase in the in-cylinder pressure, and sets an increase rate of the energy of the preceding ignition with respect to the in-cylinder pressure such that said increase rate is higher in a range where the in-cylinder pressure is high than in a range where the in-cylinder pressure is low.

5. The control apparatus for the compression-ignition type engine according to claim 4 ,
wherein the in-cylinder pressure specification section is an in-cylinder pressure sensor that detects the in-cylinder pressure.

6. The control apparatus for the compression-ignition type engine according to claim 5 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.

7. The control apparatus for the compression-ignition type engine according to claim 4 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.

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

9. The control apparatus for the compression-ignition type engine according to claim 8 ,
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.

10. 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.

11. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the in-cylinder pressure specification section is an in-cylinder pressure sensor that detects the in-cylinder pressure.

12. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the in-cylinder pressure specification section estimates the in-cylinder pressure on the basis of such a specified parameter that the in-cylinder pressure is increased with an increase in a value of the parameter, and
wherein the parameter is at least one of a flow rate of intake air that is introduced into the cylinder through an intake passage, an opening degree of a throttle valve that is provided in the intake passage, a flow rate of EGR gas that is recirculated from an exhaust passage into the intake passage, an engine load, and an accelerator opening degree.

13. The control apparatus for the compression-ignition type engine according to claim 12 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.

14. 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.

15. 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.

16. The control apparatus for the compression-ignition type engine according to claim 1 ,
wherein the ignition control section executes 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.

17. 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 combusti

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

• 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

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02B11/00

  Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders · CPC title

• F02B9/02 Primary

  with compression ignition (engines characterised by fuel-air mixture compression with compression ignition F02B1/12; engines characterised by air compression and subsequent fuel addition with compression ignition F02B3/06) · CPC title

• F02P5/153

  dependent on combustion pressure · CPC title