Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
2000-01-28
2001-09-25
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S034000, C701S076000, C701S093000, C073S146500
Reexamination Certificate
active
06295489
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for diagnosing a wheel speed input system in a vehicle motion control apparatus. The vehicle motion control apparatus comprises wheel speed sensors, a plurality of waveform converting means and an electronic control unit. The wheel speed sensors, which correspond individually to a plurality of wheels, output analog signals respectively. The respective waveform converting means convert the analog signals to obtain pulse signals. Then the electronic control unit controls an operation of an actuator which can modify a motion of a vehicle based on the pulse signals obtained at the respective waveform converting means. In the vehicle motion control apparatus, the diagnostic apparatus diagnoses a failure as existing in the respective waveform converting means themselves, and between the waveform converting means and the electronic control unit.
The above-mentioned diagnostic apparatus is known, for instance, in Japanese Patent Unexamined Publication No. Hei 2-114053 and 5-147477.
The Japanese Patent Unexamined Publication No. Hei 2-114053 discloses a diagnostic apparatus. In a vehicle motion control apparatus, respective waveform converting means, which correspond individually to a plurality of wheel speed sensors, output pulse signals. Then wheel speeds based on pulse signals obtained from respective waveform converting means are compared with wheel speeds based on pulse signals from other waveform converting means. Thus a failure is diagnosed as existing in the waveform converting means, and between the waveform converting means and an electronic control unit. However, in a case where some wheels have wheel diameters different from those of other wheels, for example, in a case where one wheel is changed to new one having a different wheel diameter because a flat tire of the wheel, it may be judged mistakenly that there exists a failure therein. In another case where all the waveform converting means are integrated in a single IC chip, there is a possibility that the respective waveform converting means fail all together at one time. In this case, it is impossible to diagnose a failure.
In addition, the above-mentioned Japanese Patent Unexamined Publication No. Hei 5-147477 discloses the other diagnostic apparatus. In a vehicle motion control apparatus, detected signals from a plurality of wheel speed sensors are inputted in parallel into a first microcomputer and a second microcomputer. The first microcomputer controls a operation of an actuator, and the second microcomputer monitors an operation of the first microcomputer as a monitoring device. A failure in a wheel speed input system is diagnosed by comparing operation results by the two microcomputers. However, such a construction makes the system redundant and operations complicated. Accordingly, a cost of the apparatus increases.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an apparatus and method for diagnosing a failure of a wheel speed input system in a vehicle motion control apparatus. The apparatus, which is simple in construction, diagnoses a failure as existing in at least either of waveform converting means themselves, and between the waveform converting means and an electronic control unit, even if some wheels have wheel diameters different from those of other wheels or the waveform converting means fail all together at one time. The failure as existing between the waveform converting means and the electronic control unit is, for instance, a disconnection or a short circuit.
The above-mentioned object can be achieved by an apparatus for diagnosing a wheel speed input system in a vehicle motion control apparatus, according to the present invention, comprising a first wheel speed sensor outputting a first analog signal corresponding to a wheel speed of a first wheel, a second wheel speed sensor outputting a second analog signal corresponding to a wheel speed of a second wheel, a first waveform converting means for converting the first analog signal into a first pulse signal, a second waveform converting means for converting the second analog signal into a second pulse signal and an electronic control unit. The electronic control unit controls an operation of an actuator which modifies a motion of a vehicle in response to the first and second pulse signals, receives first and second analog values outputted from the first and second wheel speed sensors, and judges whether or not each of the first and second waveform converting means outputs a third pulse signal which is in correspondence with a wheel speed equal to or less than a minimum wheel speed that can be detected with the first and second wheel speed sensors. The electronic control unit converts the first analog values into a first digital value at a predetermined sampling cycle when the electronic control unit judges that the first waveform converting means outputs the third pulse signal, and judges a failure in at least either of an operation of the first waveform converting means itself and an operation between the first waveform converting means and the electronic control unit in accordance with a variation of adjacent digital values thus sampled at the predetermined sampling cycle.
In the above mentioned apparatus according to the present invention, it is advantageous that when the variation of the adjacent digital values exceeds a threshold value, the electronic control unit judges that there exists the failure.
Further, in the apparatus, it is preferable that the first and second wheel speed sensors comprises a front right wheel speed sensor, a front left wheel speed sensor, a rear right wheel speed sensor and a rear left wheel speed sensor.
Furthermore, it is preferable that the electronic control unit further converts the second analog values into a second digital value at a given sampling cycle when the electronic control unit judges that the second waveform converting means outputs the third pulse signal, and judges a failure in at least either of an operation of the second waveform converting means itself and an operation between the second waveform converting means and the electronic control unit in accordance with a variation of adjacent digital values thus sampled at the given sampling cycle.
However, the above-mentioned object can also be attained by a method for diagnosing a wheel speed input system in a vehicle motion control apparatus comprising, a first wheel speed sensor outputting a first analog signal corresponding to a wheel speed of a first wheel, a second wheel speed sensor outputting a second analog signal corresponding to a wheel speed of a second wheel, a first waveform converting means for converting the first analog signal into a first pulse signal, a second waveform converting means for converting the second analog signal into a second pulse signal, and an electronic control unit controlling an operation of an actuator which modifies a motion of a vehicle in response to the first and second pulse signals. The method according to the present invention comprises the steps of:
receiving first and second analog values outputted from the first and second wheel speed sensors;
judging whether or not each of the first and second waveform converting means outputs a third pulse signal which is in correspondence with a wheel speed equal to or less than a minimum wheel speed that can be detected with the first and second wheel speed sensors;
converting the first analog values into a first digital value at a predetermined sampling cycle when the electronic control unit judges that the first waveform converting means outputs the third pulse signal; and
judging a failure in at least either of an operation of the first waveform converting means itself and an operation between the first waveform converting means and the electronic control unit in accordance with a variation of adjacent digital values thus sampled at the predetermined sampling cycle.
In the above-mentioned method according to the present invention, it is adv
Kurasima Kouji
Otsuka Yukihiro
Toyota Hideki
Arthur Gertrude
Cuchlinski Jr. William A.
McGuireWoods LLP
Nissin Kogyo Co, Ltd.
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