Non-contacting self-calibrating vibration sensor

Claim 2

A non-contacting, self-calibrating vibration sensor comprising: first means for producing a first output signal representative of the instantaneous displacement between said sensor and an object; second means for vibrating said first means at a predetermined freguency and amplitude; third means, comprising an accelerometer and an integrating and filtering network connected to receive a signal from said accelerometer, for producing a second output signal representative of the frequency and amplitude of displacement of said first means; electrical means for combining said first and second output signals to produce a resultant output signal representative only of the frequency and amplitude of displacement of said object.

Claim 3

The non-contacting vibration sensor as defined in claim 1 wherein said first means is an eddy current probe.

Claim 4

The non-contacting vibration sensor as defined in claim 1 wherein said electrical means includes: phase shift means connected to receive said first output signal and responsive thereto to provide a third output signal in phase with said second output signal; and summing means having first and second input terminals and an output terminal, said summing means being connected to receive said second output signal on said first input terminal and to receive said third output signal on said second input terminal, wherein said summing means is effective to combine said second and third output signals in inverse phase relationship to produce said resultant output signal.

Claim 5

The non-contacting vibration sensor as defined in claim 1 and including means for adjusting said predetermined frequency of vibration of said sensor.

Claim 6

A sensor for measuring vibrations of a rotating shaft, said sensor comprising: a housing; an eddy current probe disposed within said housing; a crystal accelerometer attached to said probe, said accelerometer producing a first output signal in response to movement of said probe; a solenoid attached to said housing, said solenoid operatively connected with said probe; first electrical means connected to supply AC power to said solenoid to effect vibration of said probe at a predetermined frequency and amplitude; second electrical means connected to receive said first output signal, said electrical means being effective to double integrate said first output signal to thereby produce a second output signal proportional to probe displacement; third electrical means connected to supply oscillatory power to said probe, said third electrical means including a demodulator for producing a third output signal from said probe; fourth electrical means connected to receive said third output signal, said fourth electrical means being effective to phase shift said probe output signal a predetermined amount and to provide a fourth output signal in phase with said second output signal; fifth electrical means connected to receive said second output signal on a first input terminal and to receive said fourth output signal on a second input terminal, said fifth electrical means being effective to sum said second and fourth output signals in inverse phase relationship to produce a resultant signal representative of vibrations of said shaft.

Claim 7

A sensor for measuring vibrations of a rotating shaft, said sensor comprising: a housing; an eddy current probe disposed within said housing; a crystal accelerometer attached to said probe, said accelerometer producing a first output signal in response to movement of said probe; a solenoid attached to said housing, said solenoid operatively connected with said probe; first electrical means connected to supply AC power to said solenoid to effect vibration of said probe at a predetermined frequency and amplitude; second electrical means connected to receive said first output signal, said electrical means being effective to double integrate said first output signal to thereby produce a second output signal proportional to probe displacement; third electrical means connected to supply oscillatory power to said probe, said third electrical means including a demodulator for producing a third output signal from said probe; fourth electrical means connected to receive said third output signal, said fourth electrical means being effective to phase shift said probe output signal a predetermined amount and to provide a fourth output signal in phase with said second output signal; fifth electrical means connected to receive said second output signal on a first input terminal and to receive said fourth output signal on a second input terminal, said fifth electrical means being effective to sum said second and fourth output signals in inverse phase relationship to produce a resultant signal representative of vibrations of said shaft.

Claim 8

The sensor as defined in claim 5 and including means for controlling said predetermined frequency of vibration, said means comprising: first means for producing a signal proportional to the rotational frequency of said shaft; and second means responsive to said signal to effect control of the frequency of said AC power from said first electrical means.

Claim 9

The sensor as defined in claim 5 and including means for controlling the amplitude of vibrations of said probe at said predetermined frequency, said means comprising: frequency and amplitude responsive means connected to receive said second output signal and effective to provide a fifth output signal proportional to the amplitude of the component of said second output signal at said predetermined frequency; and means responsive to said fifth output signal to effect control of said AC power from said first electrical means to maintain said vibrations of said probe at said predetermined amplitude.

Claim 10

The sensor as defined in claim 5 and including a self-calibration circuit comprising: variable attenuator means serially connected between said third electrical means and said fourth electrical means; frequency responsive means connected to receive said resultant signal, said frequency responsive means producing a sixth output signal proportional to the amplitude of the component of said resultant signal at said predetermined frequency; and control means connected to receive said sixth output signal and responsive thereto to vary said variable attenuator means to eliminate said component of said resultant signal at said predetermined frequency.

Claim 11

A non-contacting, self-calibrating vibration sensor comprising: first means for producing a first output signal representative of the instantaneous displacement between said sensor and an object; second means for vibrating said first means at a predetermined frequency and amplitude; third means for producing a second output signal representative of the frequency and amplitude of displacement of said first means; electrical means for combining said first and second output signals to produce a resultant output signal representative only of the frequency and amplitude of displacement of said object; and, means for adjusting said predetermined frequency of vibration of said sensor including: a. means for sensing rotational frequency of said object; and, b. means for transmitting a signal representative of said rotational frequency to said second means to preclude said predetermined frequency from occuring at said rotational frequency or a harmonic frequency thereof.

Claim 12

A non-contacting, self-calibrating vibration sensor comprising: first means for producing a first output signal representative of the instantaneous displacement between said sensor and an object; second means for vibrating said first means at a predetermined frequency and amplitude; third means for producing a second output signal representative of the frequency and amplitude of displacement of said first means; electrical means for combining said first and second output signals to produce a resultant output signal representative only of the frequency and amplitude of displacement of said object; and, means for adjusting said predetermined frequency of vibration of said sensor including: a. means for sensing rotational frequency of said object; and, b. means for transmitting a signal representative of said rotational frequency to said second means to preclude said predetermined frequency from occuring at said rotational frequency or a harmonic frequency thereof.

Claim 13

A non-contacting, self-calibrating vibration sensor comprising: first means for producing a first output signal representative of the instantaneous displacement between said sensor and an object; second means for vibrating said first means at a predetermined frequency and amplitude; third means for producing a second output signal representative of the frequency and amplitude of displacement of said first means; and, electrical means for combining said first and second output signals to produce a resultant output signal representative only of the frequency and amplitude of displacement of said object, said electrical means further including: a. phase shift means connected to receive said first output signal and responsive thereto to provide a third output signal in phase with said second output signal; b. summing means having first and second input terminals and an output terminal, said summing means being connected to receive said second output signal on said first input terminal and to receive said third output signal on said second input terminal, wherein said summing means is effective to combine said second and third output signals in inverse phase relationship to produce said resultant output signal; c. variable attenuator means serially connected between said first means and said phase shift means; d. frequency responsive means connected to receive said resultant output signal and effective to provide a fourth signal when said resultant output signal contains a component at said predetermined frequency; e. control means connected to receive said fourth signal from said frequency responsive means and responsive thereto to vary said variable attenuator means to eliminate said component of said resultant output signal at said predetermined frequency; f. amplitude and frequency responsive means connected to receive said second output signal and effective to provide a fifth signal proportional to the amplitude of the component of said second output signal at said predetermined frequency; g. driver means responsive to said fifth signal to provide driving impulses to said second means to maintain said vibrations at said predetermined amplitude.

Claim 14

A non-contacting, self-calibrating vibration sensor comprising: first means for producing a first output signal representative of the instantaneous displacement between said sensor and an object; second means for vibrating said first means at a predetermined frequency and amplitude; third means for producing a second output signal representative of the frequency and amplitude of displacement of said first means; and, electrical means for combining said first and second output signals to produce a resultant output signal representative only of the frequency and amplitude of displacement of said object, said electrical means further including: a. phase shift means connected to receive said first output signal and responsive thereto to provide a third output signal in phase with said second output signal; b. summing means having first and second input terminals and an output terminal, said summing means being connected to receive said second output signal on said first input terminal and to receive said third output signal on said second input terminal, wherein said summing means is effective to combine said second and third output signals in inverse phase relationship to produce said resultant output signal; c. variable attenuator means serially connected between said first means and said phase shift means; d. frequency responsive means connected to receive said resultant output signal and effective to provide a fourth signal when said resultant output signal contains a component at said predetermined frequency; e. control means connected to receive said fourth signal from said frequency responsive means and responsive thereto to vary said variable attenuator means to eliminate said component of said resultant output signal at said predetermined frequency; f. amplitude and frequency responsive means connected to receive said second output signal and effective to provide a fifth signal proportional to the amplitude of the component of said second output signal at said predetermined frequency; g. driver means responsive to said fifth signal to provide driving impulses to said second means to maintain said vibrations at said predetermined amplitude.