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

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.

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.

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.