Method and device for assessing the operating capacity of a lambda control

• US 5,404,861 A
• Filed: 08/12/1993
• Issued: 04/11/1995
• Est. Priority Date: 02/07/1992
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wild, Ernst
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US08/107,662
• Time in Patent Office: 607 Days
• Field of Search: 123/690, 123/688, 123/674, 123/675
• US Class Current: 123/674
• CPC Class Codes: F02D 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control

Abstract

In a method for assessing the operating capacity of a lambda control, which outputs regulated values FR which are to fluctuate about a desired regulated value FR_- DES, which lambda control is assisted by an adaptation outputting adaptation values, the current value of a decision quantity, which indicates the averaged absolute value of deviation of the regulated value from the desired regulated value, is calculated continuously, then the current value is compared with a decision-quantity threshold value SW_- EW, and the faulty signal is output when the current value exceeds the decision-quantity threshold value. It is therefore also possible to recognize those fails which occur only in part ranges of the total range in which an internal-combustion engine, in which the fuel supply is set by means of the lambda control, can be operated.

Claims

1. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW-EW; and

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW.

2. A device for assessing operating capacity of a lambda control, which outputs regulated values FR which are to fluctuate about a desired regulated value FR_-- DES, and the lambda control is assisted by an adaptation outputting adaptation values, the device comprising

computing means for continuous computation of a current value EW of a decision quantity which indicates an averaged absolute value of deviation of regulated values from a desired regulated value;

and

comparing means which compare the computed current value with a decision-quantity threshold value SW_- EW and which outputs a fault signal when current value exceeds the decision-quantity threshold value.

3. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW--EW; and

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW, said calculating the current value EW of a decision quantity including calculating the current value as follows;

space="preserve" listing-type="equation">EW=|(FR-FR.sub.-- DES)|.

4. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW-EW; and

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW, said calculating the current value EW of a decision quantity including calculating the current value as follows;

space="preserve" listing-type="equation">EW=|(FR-FR.sub.-- DES)|.sub.2.

5. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW-EW; and

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW, said calculating the current value EW of a decision quantity including calculating the current value as follows;

space="preserve" listing-type="equation">EW=frequency of |(FR-FR.sub.-- DES)|>

threshold value.

6. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW--EW;

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW; and

averaging to obtain the averaged absolute value of deviation and including digital low-pass filtering.

7. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW--EW;

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW; and

outputting the fault signal also when at least one adaptation value exceeds an associated adaptation threshold value SW_-- AWA, SW_-- AWM.

8. A method of assessing operating capacity of a lambda control, comprising the steps of

outputting regulated values FR which are to fluctuate about a desired regulated value FR_-- DES;

assisting the lambda control by an adaptation outputting adaptation values AWA, AWM;

continuously calculating a current value EW of a decision quantity, which indicates an averaged absolute value of deviation of regulated values from the desired regulated value;

comparing the current value with a decision-quantity threshold value SW--EW;

outputting a fault signal FS when the current value EW exceeds the decision-quantity threshold value SW_-- EW; and

determining the expected value EW of a decision quantity with a higher time constant than the at least one adaptation value AWA, AWM.