Failure diagnostic processing system

A failure diagnostic processing system for an apparatus supervised by sensors which detect individual conditions of the apparatus, said system comprising:

• a clock;
• checking means, operatively connected to the sensors and said clock, for periodically performing diagnostic checks with respect to the sensors at a predetermined constant interval in synchronism with said clock to produce first and second diagnostic signals regarding each of the sensors, the first and second diagnostic signals indicating that a failure condition exists and does not exist, respectively;
• counting means, operatively connected to said checking means and said clock, for generating a count number by incrementing and decrementing selectively in response to the first and second diagnostic signals, respectively, said counting means comprising an error counter for counting upward every time the predetermined constant interval passes when the first diagnostic signal is being produced and counting downward every time the predetermined constant interval passes when the second diagnostic signal is being produced and for generating the count number within a range between a lower limit of zero and an upper limit number;
• alarm means, operatively connected to said counting means, for providing an alarm indication in accordance with the count number of said counting means, said alarm means comprising:
• a first comparator, operatively connected to said error counter, for comparing the count number from said error counter to a first predetermined reference number and producing a signal;
• and
• an alarm indication element, operatively connected to said first comparator, activated by the signal produced by said first comparator when the count number is higher than the first predetermined reference number;
• and
• recording means, operatively connected to said counting means, for creating a history of failures by recording the count number of said counting means after the count number exceeds a second predetermined reference number, said recording means comprising:
• a history recording element, operatively connected to said error counter, for recording the count number from said error counter;
• a recording controlling element, operatively connected to said error counter and said history recording element, for producing an output for activating said history recording element;
• and
• a coincidence determined element, operatively connected to said error counter, for stopping the decrementing of said error counter, even if the second diagnostic signal is being produced, when the count number decreases and coincides with a third predetermined reference number, thus holding the count number to be at least as large as the third predetermined reference number and also for stopping the decrementing of the count number, when the count number has not exceeded the third predetermined reference number, once the count number coincides with 0.

A failure diagnostic method using data sensed by sensors, comprising the steps of:

• (a) checking the sensors periodically to detect whether a failure condition exists;
• (b) counting in dependence upon said checking by incrementing a count number if the failure condition exists and decrementing the count number if the failure condition does not exist, comprising the substeps of:
• (bi) stopping said incrementing when the count number coincides with a maximum count number;
• (bii) stopping said decrementing of the count number when the count number coincides with zero and the count number has remained less than a recording start number;
• and
• (biii) stopping said decrementing of the count number when the count number coincides with the recording start number after the count number has been incremented to a value at least as large as the recording start number;
• (c) indicating an alarm in dependence upon the count number;
• and
• (d) recording the count number when the count number is at least as large as the recording start number.

A failure diagnostic processing system for an apparatus monitored by sensors which detect individual conditions of the apparatus, said system comprising:

• clock means for supplying a clock signal;
• checking means, operatively connected to the sensors and said clock means, for periodically performing diagnostic checks with respect to the sensors at a predetermined constant interval in synchronism with the clock signal to produce first and second diagnostic signals regarding each of the sensors, the first and second diagnostic signals indicating that a failure condition exists and does not exist, respectively;
• counting means, operatively connected to said checking means and said clock means, for generating a count number by incrementing and decrementing selectively in response to the first and second diagnostic signals, respectively, said counting means comprising an error counter for counting upward every time the predetermined constant interval passes when the first diagnostic signal is being produced and counting downward every time the predetermined constant interval passes when the second diagnostic signal is being produced and for generating the count number within a range between a lower limit number and an upper limit number;
• alarm means, operatively connected to said counting means, for providing an alarm indication in accordance with the count number of said counting means, said alarm means comprising:
• a first comparator, operatively connected to said error counter, for comparing the count number from said error counter to a first predetermined reference number and producing a signal;
• and
• an alarm indication element, operatively connected to said first comparator, activated by the signal produced by said first comparator when the count number is higher than the first predetermined reference number;
• and
• coincidence determining means, operatively connected to said error counter, for stopping the decrementing of said error counter, even if the second diagnostic signal is being produced, when the count number decreases and coincides with a third predetermined reference number, thus holding the count number to be at least as large as the third predetermined reference number and also for stopping the decrementing of the count number, when the count number has not exceeded the third predetermined reference number, once the count number coincides with the lower limit number.