Control device

Patent metadata

Field	Value
Publication number	US-11649779-B2
Application number	US-201917057301-A
Country	US
Kind code	B2
Filing date	Jun 17, 2019
Priority date	Jul 3, 2018
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

Provided is a technology of accurately classifying abnormality in response characteristics of an air-fuel ratio sensors into six deterioration modes. In order to solve the above problems, the present disclosure provides a control device including a microprocessor that detects a response delay of an air-fuel ratio sensor attached to an internal combustion engine, in which the microprocessor includes a target air-fuel ratio change unit configured to change a target air-fuel ratio between lean and rich, and a response delay detection unit configured to detect a respond delay of the air-fuel ratio sensor that occurs in a real air-fuel ratio sensor signal output from the air-fuel ratio sensor when the target air-fuel ratio is changed between the lean and the rich by the target air-fuel ratio change unit.

First claim

The invention claimed is:

1. A control device, comprising a microprocessor configured to detect a response delay of an air-fuel ratio sensor attached to an internal combustion engine,
wherein the microprocessor includes:
a target air-fuel ratio change unit configured to change a target air-fuel ratio between lean and rich,
a response delay detection unit configured to detect a response delay of the air-fuel ratio sensor occurring in a real air-fuel ratio sensor signal output from the air-fuel ratio sensor when the target air-fuel ratio change unit changes the target air-fuel ratio between the lean and the rich,
a response delay abnormality detection unit configured to detect abnormality in a response delay by determining whether the response delay detected by the response delay detection unit is greater than a predetermined response delay NG threshold value, and
a first failure mode determination unit configured to calculate a change in the real air-fuel ratio sensor signal and determine a type of the response delay based on a value of a ratio of a frequency of negative change and a frequency of positive change for a predetermined period.

2. The control device according to claim 1 , wherein the first failure mode determination unit calculates the frequency of the negative change by incrementing a negative counter when a differential value of the real air-fuel ratio sensor signal is less than zero, calculates the frequency of the positive change by incrementing a positive counter when the differential value of the real air-fuel ratio sensor signal is equal to or greater than zero, and determines a failure mode 1, a failure mode 2, and a failure mode 3 from a ratio of a value of the negative counter and a value of the positive counter for the predetermined period.

3. The control device according to claim 2 , wherein
the failure mode 1 is a mode in which a first response time constant delay occurs in the real air-fuel ratio sensor signal when the target air-fuel ratio change unit changes the target air-fuel ratio from lean to rich,
the failure mode 2 is a mode in which a second response time constant delay occurs in the real air-fuel ratio sensor signal when the target air-fuel ratio change unit changes the target air-fuel ratio from the rich to the lean, and
the failure mode 3 is a mode in which a third response time constant delay occurs in the real air-fuel ratio sensor signal both when the target air-fuel ratio change unit changes the target air-fuel ratio from the lean to the rich and when the target air-fuel ratio change unit changes the target air-fuel ratio from the rich to the lean.

4. The control device according to claim 1 , wherein the microprocessor further includes a first response deterioration abnormality determination unit configured to determine a type of the abnormality in the response delay based on information on the type of the response delay determined by the first failure mode determination unit when there is the abnormality in the response delay.

5. The control device according to claim 1 , wherein the microprocessor further includes a wasted time detection unit configured to detect wasted time from a time lag between the target air-fuel ratio and the real air-fuel ratio sensor signal, and a wasted time abnormality detection unit configured to detect abnormality in the wasted time by determining whether the wasted time detected by the wasted time detection unit is longer than a predetermined wasted time NG threshold value.

6. The control device according to claim 5 , wherein the microprocessor further includes a second failure mode determination unit configured to calculate the change in the real air-fuel ratio sensor signal output from the air-fuel ratio sensor, and determine the type of the wasted time based on a relationship between a frequency of zero change, a frequency of negative change, and a frequency of positive change, respectively, for a predetermined period.

7. The control device according to claim 6 , wherein the second failure mode determination unit calculates the frequency of the zero change by incrementing a zero counter when the differential value of the real air-fuel ratio sensor signal is zero, calculates the frequency of the positive change by incrementing a positive counter when the differential value of the real air-fuel ratio sensor signal is positive, calculates the frequency of the negative change by incrementing a negative counter when the differential value of the real air-fuel ratio sensor signal is negative, and determines a failure mode 4, a failure mode 5, and a failure mode 6 from a difference relationship between a value of the zero counter, a value of the positive counter, and a value of the negative counter.

8. The control device according to claim 7 , wherein
the failure mode 4 is a failure mode in which there is a first wasted time which is a time difference from time when the target air-fuel ratio rises in a lean direction to time when the real air-fuel ratio sensor signal rises in the lean direction, in the real air-fuel ratio sensor signal when the target air-fuel ratio change unit changes the target air-fuel ratio from the lean to the rich,
the failure mode 5 is a failure mode in which there is a second wasted time which is a time difference from time when the target air-fuel ratio rises in a rich direction to time when the real air-fuel ratio sensor signal rises in the rich direction, in the real air-fuel ratio sensor signal when the target air-fuel ratio change unit changes the target air-fuel ratio from the rich to the lean, and
the failure mode 6 is a failure mode in which there are both the first wasted time and the second wasted time, in the real air-fuel ratio sensor signal when the target air-fuel ratio change unit changes the target air-fuel ratio between the lean and the rich.

9. The control device according to claim 6 , wherein the microprocessor further includes a second response deterioration abnormality determination unit configured to determine the type of the abnormality in the wasted time based on the information on the type of the wasted time determined by the second failure mode determination unit when there is the abnormality in the wasted time.

10. A control device, comprising a microprocessor configured to detect a response delay of an air-fuel ratio sensor attached to an internal combustion engine,
wherein the microprocessor includes:
a target air-fuel ratio change unit configured to change a target air-fuel ratio between lean and rich,
a response delay detection unit configured to detect a first response delay of the air-fuel ratio sensor that occurs when the target air-fuel ratio change unit changes the target air-fuel ratio from lean to rich, a second response delay of the air-fuel ratio sensor that occurs when the target air-fuel ratio change unit changes the target air-fuel ratio from the rich to the lean, and a third response delay of the air-fuel ratio sensor that occurs both when the target air-fuel ratio change unit changes the target air-fuel ratio from the lean to the rich and when the target air-fuel ratio change unit changes the target air-fuel ratio from the rich to the lean based on a real air-fuel ratio sensor signal output from the air-fuel ratio sensor and a set threshold value,
a slope detection unit configured to detect a slope of the real air-fuel ratio sensor signal, and
a determination unit configured to determine whether the response delay detected by the response delay detection unit is the first response delay, the second response delay, or the third response delay based on a ratio of a period for which the slope detected by the slope detection unit is positive and a period for which the slope is negative

Assignees

• Hitachi Automotive Systems Ltd
• Hitachi Astemo Ltd

Inventors

• Fukuchi Eisaku

Classifications

• G01N27/26

  by investigating electrochemical variables; by using electrolysis or electrophoresis · CPC title

• F02D41/1495 Primary

  Detection of abnormalities in the air/fuel ratio feedback system · CPC title

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D2041/1431

  the system including an input-output delay · CPC title

• F02D2041/227

  Limping Home, i.e. taking specific engine control measures at abnormal conditions · CPC title