Controller and control method for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10900429-B2
Application number	US-201916519401-A
Country	US
Kind code	B2
Filing date	Jul 23, 2019
Priority date	Aug 7, 2018
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

A controller is configured to control an internal combustion engine. The controller is configured to execute a catalyst temperature-increasing control of increasing a temperature of the three-way catalyst device by introducing air-fuel mixture, which contains the fuel injected by a fuel injection valve, into an exhaust passage without burning the air-fuel mixture in a cylinder. The controller includes an air-fuel ratio control unit configured to control an air-fuel ratio of the air-fuel mixture during the execution of the catalyst temperature-increasing control such that the air-fuel ratio becomes a richer air-fuel ratio during a first period from a beginning of the catalyst temperature-increasing control to a specified air-fuel ratio switching timing than during a second period from the air-fuel ratio switching timing to a completion of the catalyst temperature-increasing control.

First claim

What is claimed is:

1. A controller configured to control an internal combustion engine, the internal combustion engine including:
a fuel injection valve;
a cylinder into which air-fuel mixture containing fuel injected by the fuel injection valve is introduced;
an ignition device that ignites the air-fuel mixture introduced into the cylinder with a spark;
an exhaust passage through which gas discharged out of the cylinder flows; and
a three-way catalyst device arranged in the exhaust passage, wherein
the controller is configured to execute a catalyst temperature-increasing control of increasing a temperature of the three-way catalyst device by introducing the air-fuel mixture, which contains the fuel injected by the fuel injection valve, into the exhaust passage without burning the air-fuel mixture in the cylinder, and
the controller comprises an air-fuel ratio control unit configured to control an air-fuel ratio of the air-fuel mixture during the execution of the catalyst temperature-increasing control such that the air-fuel ratio becomes a richer air-fuel ratio during a first period from a beginning of the catalyst temperature-increasing control to a specified air-fuel ratio switching timing than during a second period from the air-fuel ratio switching timing to a completion of the catalyst temperature-increasing control.

2. The controller according to claim 1 , wherein the air-fuel ratio control unit is configured to define, as the air-fuel ratio switching timing, a timing at which an integrated value of a fuel injection amount of the fuel injection valve after starting the catalyst temperature-increasing control becomes greater than or equal to a specified switching determination value.

3. The controller according to claim 2 , wherein the air-fuel ratio control unit is configured to set the switching determination to a larger value in a case in which the temperature of the three-way catalyst device is low when the catalyst temperature-increasing control starts than in a case in which the temperature is high.

4. The controller according to claim 1 , wherein the air-fuel ratio control unit is configured to control the air-fuel ratio by controlling a fuel injection amount of the fuel injection valve.

5. The controller according to claim 1 , wherein
the internal combustion engine includes a filter for capturing PM, the filter being located downstream of the three-way catalyst device in the exhaust passage, and
the controller is configured to estimate a PM deposition amount of the filter and execute the catalyst temperature-increasing control on the condition that the estimated PM deposition amount is greater than or equal to a specified value.

6. A method for controlling an internal combustion engine, the internal combustion engine including:
a fuel injection valve;
a cylinder into which air-fuel mixture containing fuel injected by the fuel injection valve is introduced;
an ignition device that ignites the air-fuel mixture introduced into the cylinder with a spark;
an exhaust passage through which gas discharged out of the cylinder flows; and
a three-way catalyst device arranged in the exhaust passage, wherein
the method comprises:
executing a catalyst temperature-increasing control of increasing a temperature of the three-way catalyst device by introducing the air-fuel mixture, which contains the fuel injected by the fuel injection valve, into the exhaust passage without burning the air-fuel mixture in the cylinder; and
controlling an air-fuel ratio of the air-fuel mixture during the execution of the catalyst temperature-increasing control such that the air-fuel ratio becomes a richer air-fuel ratio during a first period from a beginning of the catalyst temperature-increasing control to a specified air-fuel ratio switching timing than during a second period from the air-fuel ratio switching timing to a completion of the catalyst temperature-increasing control.

7. A controller configured to control an internal combustion engine, the internal combustion engine including:
a fuel injection valve;
a cylinder into which air-fuel mixture containing fuel injected by the fuel injection valve is introduced;
an ignition device that ignites the air-fuel mixture introduced into the cylinder with a spark;
an exhaust passage through which gas discharged out of the cylinder flows; and
a three-way catalyst device arranged in the exhaust passage, wherein
the controller comprises processing circuitry configured to:
execute a catalyst temperature-increasing control of increasing a temperature of the three-way catalyst device by introducing the air-fuel mixture, which contains the fuel injected by the fuel injection valve, into the exhaust passage without burning the air-fuel mixture in the cylinder; and
control an air-fuel ratio of the air-fuel mixture during the execution of the catalyst temperature-increasing control such that the air-fuel ratio becomes a richer air-fuel ratio during a first period from a beginning of the catalyst temperature-increasing control to a specified air-fuel ratio switching timing than during a second period from the air-fuel ratio switching timing to a completion of the catalyst temperature-increasing control.

Assignees

• Toyota Motor Co Ltd

Inventors

• Nose Yuki
• Ikeda Yuto
• Myojo Keiichi
• Ando Hirokazu

Classifications

• F01N2900/0422

  measuring the elapsed time · CPC title

• F01N3/035

  with catalytic reactors · CPC title

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F01N2550/04

  Filtering activity of particulate filters · CPC title

• F01N3/101 Primary

  Three-way catalysts · CPC title