Donald O Myers

US Patent:

42375177, Dec 2, 1980

Filed:

Apr 28, 1978

Appl. No.:

5/900889

Inventors:

Donald M. Myers - Berrien Springs MI

Assignee:

Ludlow Industries, Inc. - Batavia IL

International Classification:

G01D 348

US Classification:

361239

Abstract:

Apparatus for monitoring the motion of a movable element, such as a rotatable shaft, comprising sensor means for producing a series of repetitive pulses in response to the motion of the movable element, ramp generator means for producing an increasing ramp signal, the ramp generator means including means for resetting the ramp signal to a starting level in response to each of the pulses, level detector means operable in response to the increase of the ramp signal above a predetermined level, and control means for performing a control function in response to the operation of the level detector means. The sensor means preferably include at least one conductive member, means responsive to the movement of the movable element for producing corresponding movement of the conductive member along a closed path, an inductance coil adjacent the path but spaced therefrom, oscillator circuit means for producing oscillations in the inductance coil, such oscillations being modulated by the passage of the conductive member near the coil, and pulse producing means for producing one of the repetitive pulses in response to each modulation of the oscillations by the conductive member. The ramp generator means preferably comprise a timing capacitor, means for charging the capacitor at a controlled rate to produce the ramp signal across the capacitor, and means for discharging the capacitor in response to each of the repetitive pulses to reset the ramp signal to zero. The level detector means preferably comprise voltage comparator means for comparing the ramp signal with a predetermined voltage level.