Control apparatus for compression-ignition type engine

Patent metadata

Field	Value
Publication number	US-11199152-B2
Application number	US-201917051649-A
Country	US
Kind code	B2
Filing date	Apr 17, 2019
Priority date	May 2, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

Provided is 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. Ignition timing of the preceding ignition is set to be more retarded when an in-cylinder pressure specified by an in-cylinder pressure specification section is high than when the in-cylinder pressure is low.

First claim

The invention claimed is:

1. A control 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 the fuel injected from the injector and air are mixed, and that can carry out partial compression ignition combustion to subject a first portion of the air-fuel mixture to spark ignition (SI) combustion by spark ignition using the ignition plug and to subject a remaining portion of the air-fuel mixture to compression ignition (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 a fuel injection operation by the injector; and
an ignition control section that controls an ignition operation by the ignition plug,
wherein an operation range of the partial compression ignition combustion includes a first operation range and a second operation range, in which the second operation range is on a higher-load side than the first operation range,
wherein, in the second operation range, the partial compression ignition combustion is carried out under such an environment that an air-fuel ratio as a ratio between the air and the fuel in the cylinder substantially matches a stoichiometric air-fuel ratio,
wherein, in the first operation range, the partial compression ignition combustion is carried out under a lean air-fuel environment where the air-fuel ratio is larger than that in the second operation range,
wherein, in the first operation range, the ignition control section causes the ignition plug to carry out: a 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 a preceding ignition in which the spark is generated at an earlier timing than the main ignition,
wherein, in the first operation range, the injection control section causes the injector to inject the fuel at such a timing that the fuel exists in the cylinder at an earlier time point than the preceding ignition,
wherein a timing of the preceding ignition is set to be more retarded when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure is low, and
wherein, in the second operation range, the ignition control section causes the ignition plug to carry out the main ignition without carrying out the preceding ignition.

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

5. 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.

6. The control apparatus for the compression-ignition type engine according to claim 5 ,
wherein the preceding ignition and the main ignition are carried out by a single ignition plug having a single ignition circuit for each of a plurality of cylinders.

7. The control apparatus for the compression-ignition type engine according to claim 6 ,
wherein the number of the preceding ignition in one cycle is set to three or less.

8. 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.

9. 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 exhaust gas recirculation (EGR) gas that is recirculated from an exhaust passage into the intake passage, an engine load, and an accelerator operation amount.

10. 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.

11. 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 a timing of the main ignition on the basis of the target SI rate that is set by the setting section.

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 the lean air-fuel environment where an air-fuel ratio as a ratio between the air and the fuel in the cylinder is higher than 20 and is lower than 35.

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 a second injection, in which the fuel is injected prior to the preceding ignition, and a 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.

15. A control apparatus for controlling a compression-ignition type engine that includes: a cylinder; and an injector and an ignition plug disposed in a manner to face the cylinder and ignite an air-fuel mixture, in which fuel injected from the injector and air are mixed, the engine configured to carry out partial compression ignition combustion to subject some of the air-fuel mixture to spark ignition (SI) combustion by spark ignition

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

• F02B31/085

  having two inlet valves · CPC title

• F02D41/3047 Primary

  said means being a secondary injection of fuel · CPC title

• F02B31/04

  by means within the induction channel, e.g. deflectors · CPC title

• F02P15/08 Primary

  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

• F02B1/12

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