Engine control apparatus including A/D converter failure detection element and method therefor

• US 5,184,302 A
• Filed: 01/30/1991
• Issued: 02/02/1993
• Est. Priority Date: 02/08/1990
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ishida, Yasuhiko, Kondo, Katsuhiko
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): AUCHTERLONIE, THOMAS
• Application Number:
  US07/647,967
• Time in Patent Office: 734 Days
• Field of Search: 364/424.03, 364/431.03, 364/431.04, 364/431.11, 364/DIG. 2, 364/943.9, 364/943.91, 364/944.3, 364/944.9, 364/945.7, 364/947.5, 364/265 , 364/266, 364/266.6, 364/268, 364/269.2, 123/479, 341/120, 341/155, 371/25.1, 371/57.1, 371/8.1
• US Class Current: 701/114
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue
• CPC Class Codes: F02D 41/28 Interface circuits

Abstract

An engine control apparatus includes an operational condition detecting device for detecting the operational condition of an engine, an A/D converter for converting an analog output from the operational condition detecting device into a digital output, an abnormality detecting device for detecting an abnormality in the A/D converter, an arithmetic circuit for calculating a control quantity for the engine based on the digital output of the A/D converter and a driver for actuating selected devices included in the engine in accordance with the control quantity. According to one aspect of the invention, the control quantity for the engine is replaced by a control quantity calculated based on a previously determined fixed value based on whether an abnormal state in the A/D converter is detected. According to another aspect of the invention, the driver performs the actuation of the sections of the engine in accordance with a control quantity from a backup circuit, which resets the arithmetic circuit when an abnormal state in the A/D converter is detected. Methods of operating a control system in the event of A/D converter failure are also discussed.

Claims

1. A method for operating a control apparatus for an engine having a plurality of controlled sections, said method comprising the steps of:

detecting at least one analog signal representative of operational condition of said engine;

converting said analog signal into a digital output;

detecting whether an abnormality occurs in said converting step;

when said abnormality does not occur, calculating a control quantity for said engine based on said digital output;

when said abnormality does occur, calculating said control quantity for said engine based on a previously determined fixed value in place of said digital output; and

actuating at least one of said controlled sections of said engine in accordance with said control quantity;

wherein said detecting step further comprises the step of examining, at the beginning of each operation, whether an A/D conversion finishing signal is present so as to permit, when said finishing signal is present, a determination of occurrence of said abnormality during said converting step.

2. A control apparatus having first and second operating states for an engine having a plurality of controlled sections, comprising:

operational condition detecting means for detecting the operational condition of an engine;

an A/D converter for converting an analog output from said operational condition detecting means into a digital output;

abnormality detecting means for detecting an abnormality in said A/D converter;

arithmetic means for calculating a control quantity for said engine based on said digital output from said A/D converter during said first operating state and for calculating said control quantity for said engine based on a previously determined fixed value in place of said digital output during said second operating state, wherein said first operating state and said second operating state are selected in response to a determination made by said abnormality detecting means; and

driving means for actuating at least one of said controlled sections of said engine in accordance with said control quantity;

wherein said arithmetic means further comprises a control processing unit and wherein said abnormality detecting means further comprises means for examining, at the beginning of each operation, whether an A/D conversion finishing signal is input from said A/D converter to said control processing unit so as to permit, when said finishing signal is present, said determination, said determination being indicative of erroneous operation in said A/D converter.

3. A method for operating a control apparatus for an engine having a plurality of controlled sections, said method comprising the steps of:

detecting at least one analog signal indicating operational condition of said engine;

converting said analog signal into a digital output;

detecting whether an abnormality occurs in said converting step;

when said abnormality does not occur, calculating a first control quantity for said engine based on said digital output;

when said abnormality does occur, generating a second control quantity for said engine and a reset signal for said control system; and

actuating at least one of said controlled sections of said engine in accordance with a selected one of said first control quantity and said second control quantity based on said reset signal;

wherein said detecting step further comprises the step of examining, at the beginning of each operation, whether an A/D conversion finishing signal is provided after completion of said converting step so as to permit determination of occurrence of said abnormality during said converting step.

4. A control apparatus for an engine having a plurality of controlled sections, comprising:

operational condition detecting means for detecting the operational condition of an engine;

an A/D converter for converting an analog output from said operational condition detecting means into a digital output;

abnormality detecting means for detecting an abnormality in said A/D converter;

arithmetic means for calculating a first control quantity for said engine based on said digital output of said A/D converter;

a backup circuit for generating a second control quantity for said engine and for resetting said arithmetic means based on detection of an abnormal state of said A/D converter; and

driving means for actuating at least one of said controlled sections of said engine in accordance with said first control quantity from said arithmetic means and for actuating said at least one of said controlled sections of said engine in accordance with said second control quantity provided by said backup circuit in response to said resetting of said arithmetic means;

wherein said arithmetic means comprises a control processing unit and wherein said abnormality determining means further comprises means for examining, at the beginning of each operation, whether an A/D conversion finishing signal is provided from said A/D converter to said control processing unit, so as to permit determination of erroneous operation in said A/D converter.