Control apparatus for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10443520-B2
Application number	US-201715852148-A
Country	US
Kind code	B2
Filing date	Dec 22, 2017
Priority date	Dec 27, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A control apparatus for an internal combustion engine includes an ECU configured to: determine whether a temperature-increasing process is being executed; calculate a target value of a parameter correlated with a difference between a rich air-fuel ratio and a lean air-fuel ratio achieved in the temperature-increasing process, based on an operating state of the internal combustion engine; calculate, as an upper limit, a value of the parameter required to increase the temperature of the catalyst to a predetermined upper limit temperature; determine whether the target value is equal to or lower than the upper limit; adjust the parameter used in the temperature-increasing process to the target value when the target value is determined to be equal to or lower than the upper limit; and adjust the parameter used in the temperature-increasing process to the upper limit when the target value is determined to be higher than the upper limit.

First claim

What is claimed is:

1. A control apparatus for an internal combustion engine, the control apparatus comprising:
an electronic control unit configured to i) determine whether a temperature-increasing process is being executed, the temperature-increasing process being a process of increasing a temperature of a catalyst configured to clean exhaust gas discharged from a plurality of cylinders of the internal combustion engine, by adjusting an air-fuel ratio in at least one cylinder of the plurality of cylinders to a rich air-fuel ratio that is lower than a stoichiometric air-fuel ratio, and adjusting an air-fuel ratio in the rest of the plurality of cylinders to a lean air-fuel ratio that is higher than the stoichiometric air-fuel ratio,
when the electronic control unit determines that the temperature-increasing process is being executed, the electronic control unit is configured to:
ii) calculate a target value of a parameter correlated with an amount of a difference between the rich air-fuel ratio and the lean air-fuel ratio that are achieved in the temperature-increasing process, based on an operating state of the internal combustion engine;
iii) calculate, as an upper limit, a value of the parameter required to increase the temperature of the catalyst to an upper limit temperature set in advance;
iv) determine whether the target value is equal to or lower than the upper limit;
v) adjust the parameter used in the temperature-increasing process to the target value when the electronic control unit determines that the target value is equal to or lower than the upper limit; and
vi) adjust the parameter used in the temperature-increasing process to the upper limit when the electronic control unit determines that the target value is higher than the upper limit.

2. The control apparatus according to claim 1 , wherein
the electronic control unit is configured to:
estimate the temperature of the catalyst excluding an increase in the temperature of the catalyst caused by the temperature-increasing process, based on the operating state of the internal combustion engine during execution of the temperature-increasing process;
calculate a temperature difference between the upper limit temperature and the estimated temperature of the catalyst; and
calculate, as the upper limit, a value of the parameter required to increase the temperature of the catalyst by the temperature difference.

3. The control apparatus according to claim 1 , wherein:
the catalyst includes an upstream catalyst and a downstream catalyst provided downstream of the upstream catalyst in a flow direction of the exhaust gas from the internal combustion engine; and
the electronic control unit is configured to calculate, as the upper limit, a value of the parameter required to increase the temperature of the upstream catalyst to the upper limit temperature through execution of the temperature-increasing process.

4. The control apparatus according to claim 1 , wherein in the temperature increasing process, an average of the air-fuel ratio in all of the plurality of cylinders is set to the stoichiometric air-fuel ratio.

5. The control apparatus according to claim 3 , wherein an average of the air-fuel ratios in all of the plurality of cylinders is set to a value within a prescribed range including the stoichiometric air-fuel ratio such that the temperature of the upstream catalyst and a temperature of the downstream catalyst can be increased.

6. The control apparatus according to claim 2 , wherein, in addition to being estimated based on the operating state of the internal combustion engine, the temperature of the catalyst is estimated based on one or more of an ignition retarded amount, an exhaust gas recirculation rate, a valve duration of each of an intake valve and an exhaust valve which is achieved by a variable valve timing mechanism, and a scavenging rate.

Assignees

• Toyota Motor Co Ltd

Inventors

• Nose Yuki
• Myojo Keiichi
• Shogenji Yoshiyuki
• Ikuta Eiji

Classifications

• F02D41/1475

  Regulating the air fuel ratio at a value other than stoichiometry · CPC title

• F02D41/008

  Controlling each cylinder individually · CPC title

• F01N2260/10

  for avoiding stress caused by expansions or contractions due to temperature variations · CPC title

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F02D41/1456

  with sensor output signal being linear or quasi-linear with the concentration of oxygen · CPC title