Fault detector for wheel slip control system
First Claim
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1. A fault detector for a wheel slip control system, said wheel slip control system having at least one wheel speed sensor whose output is connected to a control circuit and a solenoid valve selectively energizeable by control signals from said control circuit under predetermined conditions, comprising:
- (a) memory means connected to said control signals for storing successive increments of signal during successive solenoid valve energizations;
(b) output means for generating an output when the memory means attains a predetermined condition;
(c) reset means actuated by the end of said control signals for erasing at least some of the signal stored in said memory means;
(d) timer means for inhibiting said reset means until a predetermined time after the beginning of each of said control signals; and
(e) fallout detector means connected to said at least one wheel speed sensor and generating a fallout signal for lengthening said predetermined time when the signal from said at least one wheel speed sensor exhibits sensor fallout.
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Abstract
A memory circuit increments when sensor fallout or short solenoid energization is detected in a wheel slip control system. A disable or alarm signal is generated when the memory contents reach a predetermined threshold.
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Citations
21 Claims
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1. A fault detector for a wheel slip control system, said wheel slip control system having at least one wheel speed sensor whose output is connected to a control circuit and a solenoid valve selectively energizeable by control signals from said control circuit under predetermined conditions, comprising:
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(a) memory means connected to said control signals for storing successive increments of signal during successive solenoid valve energizations; (b) output means for generating an output when the memory means attains a predetermined condition; (c) reset means actuated by the end of said control signals for erasing at least some of the signal stored in said memory means; (d) timer means for inhibiting said reset means until a predetermined time after the beginning of each of said control signals; and (e) fallout detector means connected to said at least one wheel speed sensor and generating a fallout signal for lengthening said predetermined time when the signal from said at least one wheel speed sensor exhibits sensor fallout. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A fault detector for a wheel slip control system, said wheel slip control system having at least one wheel speed sensor operative to generate a wheel speed signal, said wheel speed signal being connected to a control circuit and a solenoid valve selectively energizeable by control signals from said control circuit under predetermined conditions comprising:
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(a) a memory capacitor operative to store charge during energization of said solenoid valve; (b) threshold circuit means for comparing the voltage stored in said memory capacitor with a threshold voltage and operative to generate an output signal when the stored voltage exceeds said threshold voltage; (c) a reset circuit operative to discharge said memory capacitor at the end of energization of said solenoid valve; (d) a timing capacitor connected to said reset circuit and operative to prevent operation of said reset circuit unless a predetermined voltage is stored therein at the end of energization of said solenoid valve; (e) means for charging said timing capacitor during the energization of said solenoid valve and for discharging it during the deenergization of said solenoid valve; (f) a sensor fallout detector connected to said wheel speed signal and operative to generate a fallout signal upon detecting sensor fallout; and (g) means in response to said fallout signal for limiting the voltage which may be stored in said timing capacitor to a value below said predetermined voltage. - View Dependent Claims (15, 16)
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17. A method of detecting faults in a wheel slip control system comprising:
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(a) storing increments of signal during actuation of said wheel slip control system; (b) comparing the stored signal with a fixed threshold and generating an output signal when the stored signal exceeds said fixed threshold; (c) erasing the stored signal at the end of actuation of said wheel slip control system; (d) inhibiting the erasing if the actuation continues for less than a predetermined time; and (e) inhibiting the erasing if a sensor fallout exists within a second predetermined time before the end of actuation of said wheel slip control system. - View Dependent Claims (18, 19, 20, 21)
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Specification