Malfunction detector for speed sensors
First Claim
1. A method of monitoring operation of a speed sensor that generates a pulse signal with a repetition frequency related to the speed being sensed, the method comprising the steps of deriving an analogue speed signal from said pulse signal, integrating said analogue speed signal in the periods between successive pulses of said pulse signal so as to obtain a separate integrated sum for each period, and comparing the integrated sum obtained for each period with a reference value corresponding to a limit for normal generation of pulses so that a warning signal is produced if said integrated sum exceeds said reference.
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Abstract
A system is disclosed for monitoring operation of a speed sensor which produces a pulse signal with a repetition frequency related to the speed being sensed.An analogue speed signal is derived from a pulse signal having a repetition frequency related to the sensed speed and is fed to an integrator which, under the control of the pulse signal, performs successive separate integrating operations on the analogue speed signal in the periods between successive pulses, and a comparator compares the integrated sum thus produced with a reference value corresponding to a limit for normal generation of pulses, to produce a warning signal if the integrated sum exceeds the reference value. The system may include a timer to respond to successive warning signals and produce a malfunction signal if they occur with less than a predetermined time interval between them. The system may also include a differentiator to differentiate the sensor pulse signal so as to obtain a spiked reset pulse at each edge of each sensor pulse, these reset pulses then being used to control the integrator. The integrating operations may be performed during the mark and the space portions of each pulse cycle.
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14 Claims
- 1. A method of monitoring operation of a speed sensor that generates a pulse signal with a repetition frequency related to the speed being sensed, the method comprising the steps of deriving an analogue speed signal from said pulse signal, integrating said analogue speed signal in the periods between successive pulses of said pulse signal so as to obtain a separate integrated sum for each period, and comparing the integrated sum obtained for each period with a reference value corresponding to a limit for normal generation of pulses so that a warning signal is produced if said integrated sum exceeds said reference.
- 8. Means for monitoring operation of a speed sensor that generates a pulse signal with a repetition frequency related to the speed being sensed, the means comprising a convertor for deriving an analogue speed signal from said pulse signal, integrating means for integrating said analogue speed signal in the periods between successive pulses of said pulse signal so as to obtain a separate integrated sum for each period, and comparison means for comparing the integrated sum obtained from said integrating means for each period with a reference value corresponding to a limit for normal generation of pulses so that a warning signal is produced if said integrated sum exceeds said reference.
Specification