# US 7,411,388 B2 · Rotary position sensor and method for determining a position of a rotating body > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,411,388 B2 - Document ID: US7411388B2 - Status: Granted - Kind: B2 - Application number: 11/214,709 - Filed: 2005-08-30 - Published: 2007-03-01 - Granted: 2008-08-12 - Earliest claimed: 2005-08-30 - Assignees: Baker Hughes Incorporated - Inventors: Bahadur Sagoo; Borislav Tchakarov; Quan Phan - Web page: https://patentgrep.com/patent/US7411388B2 ## CPC - H02K 29/12: using detecting coils {using the machine windings as detecting coil} - G01D 5/2033: {controlling the saturation of a magnetic circuit by means of a movable element, e.g. a magnet} - H02K 24/00: Machines adapted for the instantaneous transmission or reception of the angular displacement of rotating parts, e.g. synchro, selsyn - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR ## Abstract A variable reluctance position sensor and a method for determining a position of a rotating body are provided. The variable reluctance position sensor includes a rotatable member configured to be operably coupled to the rotating body. The rotatable member has a first non-magnetic body portion and a plurality of magnets disposed equidistant from one another around an exterior region of the first non-magnetic body portion. The variable reluctance position sensor further includes a stator assembly having a second non-magnetic body portion with an aperture extending therethrough for receiving the rotatable member therein. The stator assembly further includes a plurality of coils and a plurality of coil brackets. Each coil of the plurality of coils is attached to a respective coil bracket of the plurality of coil brackets. The plurality of coil brackets are fixedly attached equidistant from one another to the second non-magnetic body portion. Rotation of the rotatable member induces the plurality of coils to generate voltage signals indicative of a position of the rotatable member. ## Claims ### Claim 1 A rotary position sensor, comprising: a rotatable member comprising a first non-magnetic body portion and a plurality of magnets; and a stator assembly comprising a second non-magnetic body portion with an aperture therein for receiving the rotatable member, the stator assembly further comprising a plurality of coils, the plurality of coils configured to generate waveform signals indicative of a position of the rotatable member in response to rotation of the rotatable member. ### Claim 2 (depends on 1) The rotary position sensor of claim 1, wherein the plurality of magnets comprise rare-earth magnets. ### Claim 3 (depends on 1) The rotary position sensor of claim 1, wherein the first non-magnetic body portion is constructed from plastic. ### Claim 4 (depends on 1) The rotary position sensor of claim 1, wherein the second non-magnetic body portion is constructed from plastic. ### Claim 5 (depends on 1) The rotary position sensor of claim 1, wherein the first non-magnetic body portion of the rotatable member comprises an aperture extending from a first end of the first non-magnetic body portion into the first non-magnetic body portion, the aperture being configured to receive a portion of the rotating body for fixedly coupling the rotatable member to the rotating body. ### Claim 6 (depends on 1) The rotary position sensor of claim 1, wherein plurality of magnets are disposed equidistant from one another around an exterior region of the first non-magnetic body portion. ### Claim 7 (depends on 1) The rotary position sensor of claim 1, further comprising a computer configured to receive the signals from the plurality of coils and to generate a first plurality of signals based on the signals from the plurality of coils. ### Claim 8 (depends on 1) The rotary position sensor of claim 1, wherein the sensor is suitable for operation in a wellbore environment. ### Claim 9 (depends on 1) The rotary position sensor of claim 1, wherein the sensor is suitable for operation at temperatures greater than 350 degrees Fahrenheit. ### Claim 10 (depends on 1) The rotary position sensor of claim 1, wherein the rotatable member and the stator assembly are adapted for use with a coring apparatus in a wellbore. ### Claim 11 A rotary position sensor, comprising: a rotatable member comprising a first non-magnetic body portion and a plurality of magnets; a stator assembly comprising a second non-magnetic body portion with an aperture therein for receiving the rotatable member, the stator assembly further comprising a plurality of coils, the plurality of coils configured to generate waveform signals indicative of a position of the rotatable member in response to rotation of the rotatable member; and a housing comprising an interior region for enclosing at least a portion of the rotatable member and the stator assembly wherein the housing is constructed from aluminum and the housing comprises an alignment groove extending from an exterior surface of the housing inwardly into the housing, for positioning the housing. ### Claim 12 A method for determining a position of a rotating body utilizing a rotary position sensor, the rotary position sensor comprising a rotatable member comprising a first non-magnetic body portion and a plurality of magnets, the rotary position sensor further comprising a stator assembly comprising a second non-magnetic body portion with an aperture therein for receiving the rotatable member, the stator assembly further comprising a plurality of coils, the method comprising: rotating the rotatable member of the rotary position sensor in response to rotation of the rotating body member coupled to rotatable member, wherein the plurality of magnets on the rotatable member are rotated past the plurality of coils of the stator assembly of the rotary position sensor to induce an electro-magnetic force in each of the coils to generate waveform signals; and measuring the waveform signals to determine the position of the rotatable member utilizing a controller. ### Claim 13 A rotary position sensor, comprising: a rotatable member comprising a first non-magnetic body portion and a plurality of magnets; and a stator assembly comprising a second non-magnetic body portion with an aperture therein for receiving the rotatable member, the stator assembly further comprising a plurality of coils, the plurality of coils configured to generate waveform signals indicative of a position of the rotatable member in response to rotation of the rotatable member wherein the stator assembly further comprises a plurality of coil brackets, each coil of the plurality of coils being attached to a respective coil bracket of the plurality of coil brackets, the plurality of coil brackets being fixedly attached equidistant from one another to the second non-magnetic body portion. ### Claim 14 (depends on 13) The rotary position sensor of claim 13, wherein the plurality of coil brackets are constructed from carbon steel. ### Claim 15 A core extraction system for extracting a core from an earth formation, the core extraction system comprising: a drilling device used for extracting the core; and a system for controlling the drilling device, the drilling device comprising a rotating body, comprising: a position sensor comprising a rotatable member and a stator assembly, the rotatable member being operably coupled to the rotating body, the rotatable member comprising a first non-magnetic body portion and a plurality of magnets, the stator assembly comprising a second non-magnetic body portion configured to receive the rotatable member, the stator assembly further comprising a plurality of coils configured to generate waveform signals indicative of a position of the rotatable member in response to rotation of the rotatable member; and a controller operably communicating with the position sensor, the controller configured to control operation of the drilling device based on the signals of the position sensor. ### Claim 16 (depends on 15) The system of claim 15, wherein the plurality of magnets comprise rare-earth magnets. ### Claim 17 (depends on 15) The system of claim 15, wherein the first non-magnetic body portion is constructed from plastic. ### Claim 18 (depends on 15) The system of claim 15, wherein the position sensor is suitable for operation at temperatures greater than 350 degrees Fahrenheit. ### Claim 19 (depends on 15) The system of claim 15, wherein the second non-magnetic body portion is constructed from plastic.