Method for diagnosing abnormality of sensor

An apparatus for diagnosing an abnormal state of a machine operating condition sensor having a nonlinear output characteristic in which an output signal of a sensor changes nonlinearly in response to a physical condition of the machine to be detected by said sensor, said apparatus comprising:

• a) means for determining a first detection value which is indicated by the output signal of said sensor at a predetermined time;
• b) means for changing, by a predetermined value, said physical condition of the machine to which said sensor is attached;
• c) means for determining a second detection value which is indicated by the output signal of said sensor obtained when said physical condition has been changed by said predetermined value;
• d) means for judging whether or not a deviation between said first detection value and said second detection value is substantially equal to said predetermined value;
• and
• e) means for determining that said sensor is abnormal when judged that said deviation is substantially not equal to said predetermined value.

A method for diagnosing a sensor having an analog output which changes nonlinearly in response to a physical condition of a machine to which said sensor is attached, said analog output being converted to a digital signal by an analog-to-digital converter, said digital signal being processed by an electronic unit having data stored in said unit which defines a relationship between said digital signal and a value relating to said physical condition, said method comprising the steps of:

• a) converting an analog output of said sensor to a first digital signal;
• b) forwarding said first digital signal to said electronic unit;
• c) recognizing said first digital signal as a first value relating to said physical condition by using said data in said electronic unit;
• d) storing said first value as an initial value;
• e) changing, by a predetermined value, said physical condition of the machine to which said sensor is attached;
• f) converting an analog output of said sensor to a second digital signal when said physical condition has been changed by said predetermined value;
• g) forwarding said second digital signal to said electronic unit;
• h) recognizing said second digital signal as a second value relating to said physical condition by using said data in said electronic unit;
• i) storing said second value as a last value;
• j) calculating a difference between said last value and said initial value;
• and
• k) judging said sensor is abnormal when said difference is substantially not equal to said predetermined value.

A method for diagnosing a machine operating condition sensor having an analog output which changes nonlinearly with respect to a physical condition of the machine sensed by the sensor, said analog output of the sensor being converted to a digital signal by an analog-to-digital converter, said digital signal being forwarded to an electronic unit which recognizes said digital signal as a value relating to said physical condition of the machine by using data stored beforehand in said unit which defines a relationship between said digital signal and said value relating to said physical condition based on a characteristic of a normal sensor, said method comprising the steps of:

• a) converting an analog output of said sensor to a first digital signal using an A/D converter;
• b) forwarding said first digital signal to said electronic unit, said electronic unit comprising a central processing unit, a read only memory and at least one random access memory for storing said data;
• c) recognizing, with said electronic unit, said first digital signal as a first value relating to said physical condition by using said data stored in said read only memory;
• d) storing said first value relating to said physical condition as an initial value in said at least one random access memory;
• e) changing, by a predetermined value, said physical condition of the machine to which said sensor is attached in accordance with information stored in said read only memory;
• f) converting, with said A/D converter, an analog output of said sensor to a second digital signal when said physical condition has been changed by said predetermined value;
• g) forwarding said second digital signal to said electronic unit;
• h) recognizing, with said electronic unit, said second digital signal as a second value relating to said physical condition by using said data stored in said read only memory;
• i) storing said second value relating to said physical condition as a last value in said at least one random access memory;
• j) calculating a difference between said last value and said initial value using said central processing unit;
• and
• k) judging, with said electronic unit, said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.

A method for diagnosing a machine operating condition sensor having an analog output which changes nonlinearly with respect to a physical condition of the machine sensed by the sensor, said analog output of the sensor being converted to a digital signal by an analog-to-digital converter, said digital signal being forwarded to an electronic unit which recognizes said digital signal as a value relating to said physical condition of the machine by using data stored beforehand in said unit which defines a relationship between said digital signal and said value relating to said physical condition based on a characteristic of a normal sensor, said method comprising the steps of:

• a) converting an analog output of said sensor to a first digital signal;
• b) forwarding said first digital signal to said electronic unit;
• c) recognizing said first digital signal as a first value relating to said physical condition by using said data;
• d) storing said first value relating to said physical condition as an initial value;
• e) changing, by a predetermined value, said physical condition of the machine to which said sensor is attached;
• f) converting an analog output of said sensor to a second digital signal when said physical condition has been changed by said predetermined value;
• g) forwarding said second digital signal to said electronic unit;
• h) recognizing said second digital signal as a second value relating to said physical condition by using data;
• i) storing said second value relating to said physical condition as a last value;
• j) calculating a difference between said last value and said initial value;
• k) judging said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value;
• l) signalling that said sensor is abnormal by activating an alarm;
• and
• m) replacing said sensor with another sensor.

A method for diagnosing an engine water temperature sensor having an analog output which changes nonlinearly with respect to water temperature of the engine sensed by the sensor, said analog output of the sensor being converted to a digital signal by an analog-to-digital converter, said digital signal being forwarded to an electronic unit which recognizes said digital signal as a value relating to said engine water temperature by using data stored beforehand in said unit which defines a relationship between said digital signal and said value relating to said engine water temperature based on a characteristic of a normal sensor, said method comprising the steps of:

• a) converting an analog output of said sensor to a first digital signal;
• b) forwarding said first digital signal to said electronic unit;
• c) recognizing said first digital signal as a first value relating to said engine water temperature by using said data;
• d) storing said first value relating to said engine water temperature as an initial value;
• e) changing said engine water temperature by a predetermined value;
• f) converting an analog output of said sensor to a second digital signal when said engine water temperature has been changed by said predetermined value;
• g) forwarding said second digital signal to said electronic unit;
• h) recognizing said second digital signal to a second value relating to said engine water temperature by using said data;
• i) storing said second value relating to said engine water temperature as a last value;
• j) calculating a difference between said last value and said initial value;
• and
• k) judging said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.

A method for diagnosing an engine intake air amount sensor having an analog output which changes nonlinearly with respect to intake air amount of the engine sensed by the sensor, said analog output of the sensor being converted to a digital signal by an analog-to-digital converter, said digital signal being forwarded by an electronic unit which recognizes said digital signal as a value relating to said engine intake air amount by using data stored beforehand in said unit which defines a relationship between said digital signal and said value relating to said engine intake air amount based on a characteristic of a normal sensor, said method comprising the steps of:

• a) converting an analog output of said sensor to a first digital signal;
• b) forwarding said first digital signal to said electronic unit;
• c) recognizing said first digital signal as a first value relating to said engine intake air amount by using said data;
• d) storing said first value relating to said engine intake air amount as an initial value;
• e) changing said engine intake air amount by a predetermined value;
• f) converting an analog output of said sensor to a second digital signal when said engine intake air amount has been changed by said predetermined value;
• g) forwarding said second digital signal to said electronic unit;
• h) recognizing said second digital signal as a second value relating to said engine intake air amount by using said data;
• i) storing said second value relating to said engine intake air amount as a last value;
• j) calculating a difference between said last value and said initial value;
• and
• k) judging said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.

An apparatus for diagnosing a machine operating condition sensor having an analog output which changes nonlinearly with respect to a physical condition of the machine sensed by the sensor, said apparatus comprising:

• a) an analog-to-digital converter for converting an analog output of said sensor to a first digital signal;
• b) an electronic unit comprising a central processing unit, a read only memory and at least one random access memory;
• c) means for forwarding said first digital signal to said electronic unit;
• d) means for recognizing, with said electronic unit, said first digital signal as a first value relating to said physical condition by using data, stored beforehand in said read only memory, which defines a relationship between said digital signal and said value relating to said physical condition based on a characteristic of a normal sensor;
• e) means for storing said first value relating to said physical condition as an initial value in said at least one random access memory;
• f) means for changing, by a predetermined value, said physical condition of the machine to which said sensor is attached in accordance with information stored in said at least one random access memory;
• g) means for converting, with said analog-to-digital converter, an analog output of said sensor to a second digital signal when said physical condition has been changed by said predetermined value;
• h) means for forwarding said second digital signal to said electronic unit;
• i) means for recognizing, with said electronic unit, said second digital signal as a second value relating to said physical condtion by using said data stored in said read only memory;
• j) means for storing said secnd value relating to said physical condition as a last value in said at least one random access memory;
• k) means for calculating, with said central processing unit, a difference between said last value and said initial value;
• and
• l) means for judging, with said electronic unit, that said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.

An apparatus for diagnosing a machine operating condition sensor having an analog output which changes nonlinearly with respect to a physical condition of the machine sensed by the sensor, said apparatus comprising:

• a) an analog-to-digital converter for converting an analog output of said sensor to a first digital signal;
• b) an electronic unit;
• c) means for forwarding said first digital signal to said electronic unit;
• d) means for recognizing, with said electronic unit, said first digital signal as a first value relating to said physical condition by using data, stored beforehand in said electronic unit, which defines a relationship between said digital signal and said value relating to said physical condition based on a characteristic of a normal sensor;
• e) means for storing said first value relating to said physical condition as an initial value;
• f) means for changing, by a predetermined value, said physical condition of the machine to which said sensor is attached;
• g) means for converting, with said analog-to-digital converter, an analog output of said sensor to a second digital signal when said physical condition has been changed by said predetermined value;
• h) means for forwarding said second digital signal to said electronic unit;
• i) means for recognizing, with said electronic unit, said second digital signal as a second value relating to said physical condition by using said data;
• j) means for storing said second value relating to said physical condition as a last value;
• k) means for calculating a difference between said last value and said initial value;
• l) means for judging, with said electronic unit, that said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value;
• m) means for actuating an alarm to signal that said sensor is abnormal;
• and
• n) means for replacing said sensor with another sensor.

An apparatus for diagnosing an engine water temperature sensor having an analog output which changes nonlinearly with respect to water temperature of the engine sensed by the sensor, said apparatus comprising:

• a) an analog-to-digital converter for converting an analog output of said sensor to a first digital signal;
• b) an electronic unit;
• c) means for forwarding said first digital signal to said electronic unit;
• d) means for recognizing, with said electronic unit, said first digital signal as a first value relating to said engine water temperature by using data, stored beforehand in said electronic unit, which defines a relationship between said digital signal and said value relating to said engine water temperature based on a characteristic of a normal sensor;
• e) means for storing said first value relating to said engine water temperature as an initial value;
• f) means for changing said water temperature by a predetermined value;
• g) means for converting, with said analog-to-digital converter, an analog output of said sensor to a second digital signal when said engine water temperature has been changed by said predetermined value;
• h) means for forwarding said second digital signal to said electronic unit;
• i) means for recognizing, with said electronic unit, said second digital signal as a second value relating to said engine water temperature by using said data;
• j) means for storing said second value relating to said engine water temperature as a last value;
• k) means for calculating a difference between said last value and said initial value;
• and
• l) means for judging, with said electronic unit, that said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.

An apparatus for diagnosing an engine intake air amount sensor having an analog output which changes nonlinearly with respect to intake air amount of the engine sensed by the sensor, said apparatus comprising:

• a) an analog-to-digital converter for converting an analog output of said sensor to a first digital signal;
• b) an electronic unit;
• c) means for forwarding said first digital signal to said electronic unit;
• d) means for recognizing, with said electronic unit, said first digital signal as a first value relating to said engine intake air amount by using data, stored beforehand in said electronic unit, which defines a relationship between said digital signal and said value relating to said engine intake air amount based on a characteristic of a normal sensor;
• e) means for storing said first value relating to said engine intake air amount as an initial value;
• f) means for changing said engine intake air amount by a predetermined value;
• g) means for converting, with said analog-to-digital converter, an analog output of said sensor to a second digital signal when said engine intake air amount has been changed by said predetermined value;
• h) means for forwarding said second digital signal to said electronic unit;
• i) means for recognizing, with said electronic unit, said second digital signal as a second value relating to said engine intake air amount by using said data;
• j) means for storing said second value relating to said engine intake air amount as a last value;
• k) means for calculating a difference between said last value and said initial value;
• and
• l) means for judging, with said electronic unit, that said sensor is abnormal when said calculated difference is substantially not equal to said predetermined value.