Method for detecting output-stuck fault of car body acceleration sensor, apparatus for detecting output-stuck fault of car body acceleration sensor, and anti-lock braking system for car

A method for detecting an output-stuck fault of a car body acceleration sensor installed in a car having an anti-lock braking system for a car, said method comprising the steps of:

• operating a relative change quantity difference between a change quantity of logical car body acceleration per unit time, the change quantity being operated on a basis of a wheel speed, and a change quantity of physical car body acceleration per unit time, the physical car body acceleration being detected by said car body acceleration sensor;
• measuring a duration time of a state in which the change quantity difference is exceeding a first rated value;
• storing a maximum value of the change quantity of the physical car body acceleration per unit time during the state in which the change quantity difference is exceeding the first rated value;
• and
• judging that said car body acceleration sensor is in its output-stuck fault state if the stored maximum value of the change quantity is a second rated value or less at a point of time when the duration time of the state in which the change quantity difference is exceeding the first rated value exceeds a rated time.

An apparatus for detecting an output-stuck fault of a car body acceleration sensor installed in a car having an anti-lock braking system for a car, said apparatus comprising:

• a wheel speed sensor outputting an alternating current signal having a frequency proportional to a rotational speed of a wheel of the car;
• a control section having an operation function for operating a wheel speed by receiving the alternating current signal from said wheel speed sensor to compute car body acceleration logically on a basis of the wheel speed;
• and
• a car body acceleration sensor for detecting car body acceleration physically to output the detected car body acceleration to said control section;
• wherein said control section comprises:
• means for operating a relative acceleration difference between the logical car body acceleration operated on a basis of the wheel speed and the physical car body acceleration detected by said car body acceleration sensor;
• means for measuring a duration time of a state in which the acceleration difference is exceeding a first rated value;
• means for storing minimum acceleration and maximum acceleration of the physical car body acceleration during the state in which the acceleration difference is exceeding the first rated value;
• and
• means for judging that said car body acceleration sensor is in its output-stuck fault state if a difference between the stored minimum acceleration and the stored maximum acceleration is a second rated value or less at a point of time when the duration time of the state in which the acceleration difference is exceeding the first rated value exceeds a rated time.

An apparatus for detecting an output-stuck fault of a car body acceleration sensor installed in a car having an anti-lock braking system for a car, said apparatus comprising:

• a wheel speed sensor outputting an alternating current signal having a frequency proportional to a rotational speed of a wheel of the car;
• a control section having an operation function for operating a wheel speed by receiving the alternating current signal from said wheel speed sensor to compute car body acceleration logically on a basis of the wheel speed;
• and
• a car body acceleration sensor for detecting car body acceleration physically to output the detected car body acceleration to said control section;
• wherein said control section comprises:
• means for operating a relative change quantity difference between a change quantity of the logical car body acceleration per unit time, the change quantity being operated on a basis of the wheel speed, and a change quantity of the physical car body acceleration per unit time, the physical car body acceleration being detected by said car body acceleration sensor;
• means for measuring a duration time of a state in which the change quantity difference is exceeding a first rated value;
• means for storing a maximum value of the change quantity of the physical car body acceleration per unit time during the state in which the change quantity difference is exceeding the first rated value;
• and
• means for judging that said car body acceleration sensor is in its output-stuck fault state if the stored maximum value of the change quantity is a second rated value or less at a point of time when the duration time of the state in which the change quantity difference is exceeding the first rated value exceeds a rated time.

An anti-lock braking system for a car, said system being equipped with an apparatus for detecting an output-stuck fault of a car body acceleration sensor, said apparatus comprising:

• a wheel speed sensor outputting an alternating current signal having a frequency proportional to a rotational speed of a wheel of the car;
• a control section having an operation function for operating a wheel speed by receiving the alternating current signal from said wheel speed sensor to compute car body acceleration logically on a basis of the wheel speed;
• and
• a car body acceleration sensor for detecting car body acceleration physically to output the detected car body acceleration to said control section;
• wherein said control section comprises:
• means for operating a relative acceleration difference between the logical car body acceleration operated on a basis of the wheel speed and the physical car body acceleration detected by said car body acceleration sensor;
• means for measuring a duration time of a state in which the acceleration difference is exceeding a first rated value;
• means for storing minimum acceleration and maximum acceleration of the physical car body acceleration during the state in which the acceleration difference is exceeding the first rated value;
• and
• means for judging that said car body acceleration sensor is in its output-stuck fault state if a difference between the stored minimum acceleration and the stored maximum acceleration is a second rated value or less at a point of time when the duration time of the state in which the acceleration difference is exceeding the first rated value exceeds a rated time.

An anti-lock braking system for a car, said system being equipped with an apparatus for detecting an output-stuck fault of a car body acceleration sensor, said apparatus comprising:

• a wheel speed sensor outputting an alternating current signal having a frequency proportional to a rotational speed of a wheel of the car;
• a control section having an operation function for operating a wheel speed by receiving the alternating current signal from said wheel speed sensor to compute car body acceleration logically on a basis of the wheel speed;
• and
• a car body acceleration sensor for detecting car body acceleration physically to output the detected car body acceleration to said control section;
• wherein said control section comprises:
• means for operating a relative change quantity difference between a change quantity of the logical car body acceleration per unit time, the change quantity being operated on a basis of the wheel speed, and a change quantity of the physical car body acceleration per unit time, the physical car body acceleration being detected by said car body acceleration sensor;
• means for measuring a duration time of a state in which the change quantity difference is exceeding a first rated value;
• means for storing a maximum value of the change quantity of the physical car body acceleration per unit time during the state in which the change quantity difference is exceeding the first rated value;
• and
• means for judging that said car body acceleration sensor is in its output-stuck fault state if the stored maximum value of the change quantity is a second rated value or less at a point of time when the duration time of the state in which the change quantity difference is exceeding the first rated value exceeds a rated time.