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US 2010/0301840 A1Published application
Measuring the position of an object
AssigneeCalnetix, Inc.
InventorAlexei V. Filatov
Life of this patent
Estimating the term…
Abstract
Noncontact measuring of positions of objects is achieved through measurements of parameters characterized by the distribution of an AC magnetic flux in the air gap between stationary and moveable portions defining a sensor magnetic circuit.
Claims25
An apparatus for determining the position of a movable element relative to a stationary element along a measurement axis, the apparatus comprising:
- a sensor head fixed in relation to the stationary element, the sensor head comprising a soft-magnetic core;
- a sensor target fixed in relation to the movable element, the soft-magnetic core and the sensor target separated by an air gap and defining a magnetic circuit;
- a conductive excitation coil coiled around the soft-magnetic core and adapted to produce an AC magnetic flux in the magnetic circuit, the AC magnetic flux corresponding with a total magnetic flux in the air gap, the sensor target comprising different electromagnetic properties at different locations along the measurement axis that causes a distribution of the total magnetic flux in the air gap to change when the sensor target is displaced along the measurement axis;
- a magnetic flux density sensor fixed in relation to the sensor head and residing in the air gap between the soft-magnetic core and the sensor target, the magnetic flux density sensor configured to detect magnetic flux density in a portion of the air gap;
- and
- a controller in communication with the magnetic flux density sensor, configured to receive an output signal of the magnetic flux density sensor and determine the position of the sensor target along the measurement axis based on the total magnetic flux in the air gap and magnetic flux density detected by the magnetic flux density sensor.
3 more elements
A method for sensing a position of a movable element relative to a stationary element along a measurement axis, the method comprising:
- communicating a total magnetic flux in an air gap separating the stationary element from the movable element, the movable element comprising different electromagnetic properties along the measurement axis;
- measuring a magnetic flux density in a portion of the air gap;
- and
- determining the position of the movable element based on a ratio of the total magnetic flux in the air gap and the measured magnetic flux density.
1 more element
An electric machine system, the system comprising:
- a first element;
- a second element configured to translate in a direction parallel to a measurement axis relative to the first element;
- a third element fixed in relation to the first element, the third element comprising a soft-magnetic pole;
- a fourth element fixed in relation to the second element, the third element and the fourth element separated by an air gap, the third element and the fourth element defining a magnetic circuit;
- a source element fixed in relation to the third element, the source element configured to produce an AC magnetic flux in the magnetic circuit, the AC magnetic flux corresponding with a total magnetic flux in the air gap;
- a sensor fixed in relation to the third element, adjacent the soft-magnetic pole, and residing between the third element and the fourth element, the sensor configured to measure magnetic flux density in a portion of the air gap;
- and
- an electronics module in communication with the sensor, configured to measure an output of the sensor and determine a position of the fourth element along the axis based on the output of the sensor and the total magnetic flux in the air gap.
5 more elements
Dependencies are inferred from the claim text.