Operating circuit for magnetoelastic force/pressure sensors
AssigneeGeneral Electric Company
InventorsWilliam P. Kornrumpf, Robert P. Alley
Life of this patent
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Abstract
An operating circuit for use with a magnetoelastic force/pressure sensor provides for changing the current flow through at least one sensor coil at a frequency responsive to the magnitude of a force impingent upon the sensor. The sensor operating circuit operates in a manner to prevent the sensor magnetoelastic core from being driven deeply into saturation, thus providing an operating circuit with a reduced current drain. A number of embodiments, including clock-driven and self-clocking (toggling) circuit providing digital and/or analog outputs are described.
Claims33
An operating circuit for providing an output having a characteristic changing responsive to the magnitude of a force incident upon a magnetoelastic sensor having at least one coil means wound about a magnetoelastic core with a magnetic flux density saturation magnitude changing responsive to the magnitude of said force, comprising:
- first means operating upon said at least one coil means for varying the magnetizing force in said core to cause the core flux density to attain substantially the saturation magnitude thereof in either selected one of a pair of opposite polarity saturation regions;
- second means for providing a signal upon detection of a change in the current flowing through said at least one coil means responsive to said core flux density entering one of said saturation regions;
- said operating circuit output characteristic being the frequency at which the second means signal occurs;
- third means, responsive to each occurrence of said second means signal, for causing said first means to reverse the direction of the magnetizing force in said core to vary said core flux density to the saturation region of the other polarity;
- and
- fourth means for varying said operating circuit output characteristic responsive to the number of core magnetizing force reversals in a selected time interval and therefore responsive to said incident force magnitude, and comprising:
- clock means for generating a periodic signal waveform;
- counter means for counting the number of clock means waveforms occurring between a pair of selected consecutive second means signals;
- and means for resetting said counting means after the occurrence of a selected number of second means signals, to facilitate providing a next count related to the incident force upon said sensor in the interval between the resettings of said counting means.
An operating circuit for providing an output having a characteristic changing responsive to the magnitude of a force incident upon a magnetoelastic sensor having a single coil, having first and second ends, wound about a magnetoelastic core with a magnetic flux density saturation magnitude changing responsive to the magnitude of said force, comprising:
- first means operating upon said at least one coil means for varying the magnetizing force in said core to cause the core flux density to attain substantially the saturation magnitude thereof in either selected one of a pair of opposite polarity saturation regions;
- second means for providing a signal upon detection of a change in the current flowing through said at least one coil means responsive to said core flux density entering one of said saturation regions;
- said operating circuit output characteristic being the frequency at which the second means signal occurs;
- third means, responsive to each occurrence of said second means signal, for causing said first means to reverse the direction of the magnetizing force in said core to vary said core flux density to the saturation region of the other polarity;
- said third means comprising:
- a flip-flop logic element having first and second complementary outputs and an input receiving each occurrence of said second means signal for toggling said complementary outputs to that one of a pair of states opposite to the state the associated output was in prior to receiving the second means signal occurrence;
- said first means utilizing the state of said complementary output signals for determining that one of said pair of saturation regions toward which said core flux density is varied;
- and
- fourth means for varying said operating circuit output characteristic responsive to the number of core magnetizing force reversals in a selected time interval and therefore responsive to said incident force magnitude.
An operating circuit for providing an output having a characteristic changing responsive to the magnitude of a force incident upon a magnetoelastic sensor having at least one coil means wound about a magnetoelastic core with a magnetic flux density saturation magnitude changing responsive to the magnitude of said force, comprising:
- first means operating upon said at least one coil means for varying the magnetizing force in said core to cause the core flux density to attain substantially the saturation magnitude thereof in either selected one of a pair of opposite polarity saturation regions;
- second means for providing a signal upon detection of a change in the current flowing through said at least one coil means responsive to said core flux density entering one of said saturation regions, and comprising:
- means for sampling the current flowing through all of said at least one coil means to provide a sampling signal;
- means for providing a reference signal of a preselected substantially-constant magnitude;
- and comparator means for providing said second means signal whenever the magnitude of said sampling signal exceeds the magnitude of said reference signal;
- third means, responsive to each occurrence of said second means signal, for causing said first means to reverse the direction of the magnetizing force in said core to vary said core flux density to the saturation region of the other polarity;
- and
- fourth means for varying said operating circuit output characteristic responsive to the number of core magnetizing force reversals in a selected time interval and therefore responsive to said incident force magnitude.
An operating circuit for providing an output having a characteristic changing responsive to the magnitude of a force incident upon a magnetoelastic sensor having first and second coils, each having a first end connected in common and oppositely-phased second ends, wound about a magnetoelastic core with a magnetic flux density saturation magnitude changing responsive to the magnitude of said force, comprising:
- first means operating upon said at least one coil means for varying the magnetizing force in said core to cause the core flux density to attain substantially the saturation magnitude thereof in either selected one of a pair of opposite polarity saturation regions;
- said first means comprising:
- a source of operating potential connected to said common coil first ends;
- a first means common terminal;
- and means including first and second switching means, each connected in series between an associated one of said first and second coil second ends and said common terminal for enabling and disabling current flow through the associated coil, responsive to different states of at least one input signal, from said source to flow through only one of said coils in a direction causing the magnetic force in said core to be directed in a direction opposite to the direction in which the magnetizing force would be directed if the current flows through the other coil;
- second means for providing a signal upon detection of a change in the current flowing through said at least one coil means responsive to said core flux density entering one of said saturation regions;
- third means, responsive to each occurrence of said second means signal, for causing said first means to reverse the direction of the magnetizing force in said core to vary said core flux density to the saturation region of the other polarity, and comprising:
- a flip-flop logic element having first and second complementary outputs and an input receiving each occurrence of said second means signal for toggling said complementary outputs to that one of a pair of states opposite to the state the associated output was in prior to receiving the second means signal occurrence;
- each of said switching means utilizing the state of a different one of said complementary output signals for determining the enablement and disablement of current flow through the associated one of said coils;
- and
- fourth means for varying said operating circuit output characteristic responsive to the number of core magnetizing force reversals in a selected time interval and therefore responsive to said incident force magnitude.
Dependencies are inferred from the claim text.