Methods and systems for measuring an axial position of a rotating component of an engine are described herein. The method comprises obtaining a signal from a sensor coupled to the rotating component, the rotating component having a plurality of position markers distributed about a surface thereof, the position markers having an axially varying characteristic configured to cause a change in a varying parameter of the signal as a function of the axial position of the rotating component. Based on the signal, the method comprises determining a rotational speed of the rotating component from the signal, determining the varying parameter of the signal, and finding the axial position of the rotating component based on a known relationship between the axial position, the rotational speed, and the varying parameter of the signal.

In one embodiment, an apparatus includes a different amplifier. A node in the apparatus receives a motor-current signal and an output of the differential amplifier. The motor-current signal represents a motor current of a DC brush motor. Moreover, a first input of the differential amplifier is coupled to a node. The apparatus also includes a low-pass filter with an input receiving a motor-current signal and an output coupled to a second input of the differential amplifier. The apparatus additionally includes a comparator with a first input coupled to the output of the differential amplifier and a second input coupled to a referential voltage.

In one embodiment, an apparatus includes a different amplifier. A node in the apparatus receives a motor-current signal and an output of the differential amplifier. The motor-current signal represents a motor current of a DC brush motor. Moreover, a first input of the differential amplifier is coupled to a node. The apparatus also includes a low-pass filter with an input receiving a motor-current signal and an output coupled to a second input of the differential amplifier. The apparatus additionally includes a comparator with a first input coupled to the output of the differential amplifier and a second input coupled to a referential voltage.

The invention relates to a method for filtering an input signal (3b, 4b, 5b) relative to a physical variable of a turbine engine (9), the input signal being digitised, the method implementing frequency filtering of said signal in a computer (6) of a control system (7) of said turbine engine (9), said signal being provided at the input of the computer, a digital derivative of said signal being intended for being used by the control system (7), characterised in that it involves: —detecting an amplitude variation of said variable on said input signal, by a step of generating a second derivative signal (S) of the input signal and a step of comparing a value of the second derivative value of the input signal with at least one predetermined threshold (S.sub.1 . . . S.sub.n); and —adapting the frequency filtering of said input signal as a function of the detected amplitude variation of said variable, by a step of controlling a controlled filter (PB.sub.11) capable of applying frequency filtering to the input signal, so that the controlled filter applies or does not apply the frequency filtering as a function of a result of the comparison step.

A sensor system can include a sensor configured to output a sensor signal having a waveform output with noise and a peak detector module configured to receive the waveform output from the sensor and to detect a peak amplitude of the waveform output. The peak detector module can be configured to output a peak amplitude signal. The system can include a threshold module configured to receive the peak amplitude signal and to calculate a cutoff threshold based on the peak amplitude signal. The threshold module can be configured to output a cutoff threshold signal. The system can include a comparator operatively connected to the sensor and the threshold module. The comparator can be configured to receive the sensor signal and the cutoff threshold signal to compare the sensor signal and the cutoff signal. The comparator can be configured to output a high signal or a low signal based on the comparison of the sensor signal and the cutoff threshold signal which changes as a function of the peak amplitude of the sensor signal.

A sensor system can include a sensor configured to output a sensor signal having a waveform output with noise and a peak detector module configured to receive the waveform output from the sensor and to detect a peak amplitude of the waveform output. The peak detector module can be configured to output a peak amplitude signal. The system can include a threshold module configured to receive the peak amplitude signal and to calculate a cutoff threshold based on the peak amplitude signal. The threshold module can be configured to output a cutoff threshold signal. The system can include a comparator operatively connected to the sensor and the threshold module. The comparator can be configured to receive the sensor signal and the cutoff threshold signal to compare the sensor signal and the cutoff signal. The comparator can be configured to output a high signal or a low signal based on the comparison of the sensor signal and the cutoff threshold signal which changes as a function of the peak amplitude of the sensor signal.

A monitoring system for monitoring one or more properties associated with a rotating shaft is provided. The system includes a first phonic wheel which is mounted coaxially to the shaft for rotation therewith, the first phonic wheel comprising a circumferential row of teeth. The system further includes a first sensor configured to detect the passage of the row of teeth of the first phonic wheel by generating a first alternating measurement signal. The system further includes a processor unit configured to determine the durations of successive first speed samples. Each first speed sample is a block of n successive cycles of the first alternating measurement signal, where n is an integer, and in which the beginning of each cycle is a zero-crossing point from the previous cycle and the end of each cycle is the corresponding zero-crossing point to the next cycle. At least one axial location of the first phonic wheel every m.sup.th tooth of the row of teeth of the first phonic wheel has a circumferential thickness which is different from that of the other teeth of the first phonic wheel, where m is an integer, m≠n, and m is neither a factor nor a multiple of n. When the first sensor is positioned at said axial location of the first phonic wheel and at any given rotational speed of the first phonic wheel, the durations of the successive first speed samples display a characteristic repeating pattern of longer and shorter sample durations relative to the average duration of the successive first speed samples. The amount by which the longer and shorter sample durations differ from the average duration is in proportion to the amount by which the circumferential thickness of the m.sup.th teeth differs from that of the other teeth at said axial location of the first phonic wheel. The processor unit monitors the properties associated with the rotating shaft from the characteristic repeating pattern.

A monitoring system for monitoring one or more properties associated with a rotating shaft is provided. The system includes a first phonic wheel which is mounted coaxially to the shaft for rotation therewith, the first phonic wheel comprising a circumferential row of teeth. The system further includes a first sensor configured to detect the passage of the row of teeth of the first phonic wheel by generating a first alternating measurement signal. The system further includes a processor unit configured to determine the durations of successive first speed samples. Each first speed sample is a block of n successive cycles of the first alternating measurement signal, where n is an integer, and in which the beginning of each cycle is a zero-crossing point from the previous cycle and the end of each cycle is the corresponding zero-crossing point to the next cycle. At least one axial location of the first phonic wheel every m.sup.th tooth of the row of teeth of the first phonic wheel has a circumferential thickness which is different from that of the other teeth of the first phonic wheel, where m is an integer, m≠n, and m is neither a factor nor a multiple of n. When the first sensor is positioned at said axial location of the first phonic wheel and at any given rotational speed of the first phonic wheel, the durations of the successive first speed samples display a characteristic repeating pattern of longer and shorter sample durations relative to the average duration of the successive first speed samples. The amount by which the longer and shorter sample durations differ from the average duration is in proportion to the amount by which the circumferential thickness of the m.sup.th teeth differs from that of the other teeth at said axial location of the first phonic wheel. The processor unit monitors the properties associated with the rotating shaft from the characteristic repeating pattern.

Methods and systems for measuring an axial position of a rotating component of an engine are described herein. The method comprises obtaining a signal from a sensor coupled to the rotating component, the rotating component having a plurality of position markers distributed about a surface thereof, the position markers having an axially varying characteristic configured to cause a change in a varying parameter of the signal as a function of the axial position of the rotating component. Based on the signal, the method comprises determining a rotational speed of the rotating component from the signal, determining the varying parameter of the signal, and finding the axial position of the rotating component based on a known relationship between the axial position, the rotational speed, and the varying parameter of the signal.

Methods and systems for measuring an axial position of a rotating component of an engine are described herein. The method comprises obtaining a signal from a sensor coupled to the rotating component, the rotating component having a plurality of position markers distributed about a surface thereof, the position markers having an axially varying characteristic configured to cause a change in a varying parameter of the signal as a function of the axial position of the rotating component. Based on the signal, the method comprises determining a rotational speed of the rotating component from the signal, determining the varying parameter of the signal, and finding the axial position of the rotating component based on a known relationship between the axial position, the rotational speed, and the varying parameter of the signal.