Permanent magnet rotary accelerometer

• US 20010037684A1
• Filed: 07/12/2001
• Published: 11/08/2001
• Est. Priority Date: 09/24/1999
• Status: Active Grant

• Current Assignee: Cda Astro Intercorp
• Original Assignee: Cda Astro Intercorp
• Inventors: Starin, Scott H., DʼAmico, Carmine
• Granted Patent: US 6,427,534 B2
• Time in Patent Office: Days
• US Class Current: 73/514.31
• CPC Class Codes: G01P 15/003 Kinematic accelerometers, i.e. measuring acceleration in relation to an external reference frame, e.g. Ferratis accelerometers G01P15/001, G01P15/16, G01P15/165 take precedence
• CPC Class Codes: G01P 3/49 using eddy currents

Abstract

A permanent magnet rotary accelerometer comprising: a cylindrical magnetic return path formed out of magnetic permeable material; an electrically conductive cup with an axis for rotation there around, the cup surrounding the magnetic return path; one or more sets of permanent magnets having opposite magnetic polarity, surrounding the cup, for a producing magnetic field through the cup into the magnetic return path, thereby inducing eddy currents inside the cup when rotating in the magnetic field; a stator core formed out of magnetic permeable material surrounding the cup and nonrotatable relative thereto, the stator core comprising at least two pick up members and a stator core return path therein, wherein the pick up members and the stator core return path are formed from at least one continuous piece of magnetic permeable material; and one or more pickup coils disposed on the pickup members of the stator core for sensing changes in a secondary magnetic filed generated by the eddy currents in the cup.

Claims

1. A rotary accelerometer comprising:

(FOR RA-001 and RA-002)

a cylindrical magnetic return path formed out of magnetic permeable material;

an electrically conductive cup with an axis for rotation there around, the cup surrounding the magnetic return path;

one or more sets of permanent magnets having opposite magnetic polarity, surrounding the cup, for a producing magnetic field through the cup into the magnetic return path, thereby inducing eddy currents inside the cup when rotating in the magnetic field;

a stator core formed out of magnetic permeable material surrounding the cup and nonrotatable relative thereto, the stator core comprising at least two pick up members and a stator core return path therein, wherein the pick up members and the stator core return path are formed from at least one continuous piece of magnetic permeable material; and

one or more pickup coils disposed on the pickup members of the stator core for sensing changes in a secondary magnetic filed generated by the eddy currents in the cup.

2. The rotary accelerometer of

claim 1

, further comprising a mechanical input shaft for coupling to a rotating machine and wherein the cup is dispose on magnetic return path, and the magnetic return path is coupled to the shaft and the cup and the magnetic return path rotates around the axis of the cup with the shaft.

3. The rotary accelerometer of

claim 1

, further comprising a mechanical input shaft for coupling to a rotating machine and wherein the magnetic return path is nonrotatable and the cup surrounding the magnetic return path forms a gap therebetween to permit the cup to rotate with the shaft about the magnetic return path.

4. The rotary accelerometer of

claim 1

, wherein the stator core is comprised of one or more layers of magnetic permeable materials laminated together so that at least one layer forms one continuous piece that includes the pickup members and stator core return path.

5. The rotary accelerometer of

claim 1

, wherein the stator core includes one or more sets of mounts and where the one or more sets permanent magnets are held fixed on the mounts.

6. The rotary accelerometer of

claim 1

, wherein the cup is coupled to a rotating electrical machine to provide a closed loop motion control therewith.

7. The rotary accelerometer of

claim 1

, wherein the rotating electrical machine is a direct current stepper motor.

8. The rotary accelerometer of

claim 1

, wherein the cup is coupled to a rotating pneumatic machine to provide a closed loop motion control therewith.

9. The rotary accelerometer of

claim 1

, wherein the cup is coupled to a rotating combustion machine to provide a closed loop motion control therewith.

10. A rotary accelerometer comprising:

(FOR RA-003)

a nonrotatable cylindrical magnetic return path formed out of magnetic permeable material;

one or more permanent magnets, with two opposite magnetic poles, disposed around the magnetic return path;

an electrically conductive cup with an axis for rotation there around, the cup surrounding the permanent magnets and the permanent magnets are arranged so as to produce a magnetic field through the cup into magnetic return path thereby inducing eddy currents inside the cup when rotating in the magnetic field;

a stator core formed out of magnetic permeable material surrounding the cup and nonrotatable relative thereto, the stator core comprising at least two pick up members and a stator core return path therein, wherein the pick up members and the stator core return path are formed from at least one continuous piece of magnetic permeable material; and

one or more pickup coils disposed on the pickup members of the stator core for sensing changes in a secondary magnetic filed generated by the eddy currents in the cup.

11. A rotary accelerometer comprising:

(FOR RA-004)

a nonrotatable cylindrical magnetic return path formed out of magnetic permeable material;

an electrically conductive cup rotatably mounted inside the magnetic return path;

one or more sets of permanent magnets having opposite magnetic polarity, mounted inside the cup, for a producing magnetic field through the cup into the magnetic return path, wherein eddy currents are induced inside the cup when rotating in the magnetic field;

a stator core formed out of magnetic permeable material mounted inside the cup and nonrotatable relative thereto, the stator core comprising at least two pick up members and a stator core return path therein, wherein the pick up members and the stator core return path are formed from at least one continuous piece of magnetic permeable material; and

one or more pickup coils disposed on the pickup members of the stator core for sensing changes in a secondary magnetic filed generated by the eddy currents in the cup.

12. A rotary accelerometer comprising:

(FOR RA-005)

a nonrotatable cylindrical magnetic return path formed out of magnetic permeable material;

an electrically conductive cup rotatably mounted inside the magnetic return path;

one or more sets of permanent magnets having opposite magnetic polarity, mounted outside the cup, for a producing magnetic field through the cup into the magnetic return path, wherein eddy currents are induced inside the cup when rotating in the magnetic field;

a stator core formed out of magnetic permeable material mounted inside the cup and nonrotatable relative thereto, the stator core comprising at least two pick up members and a stator core return path therein, wherein the pick up members and the stator core return path are formed from at least one continuous piece of magnetic permeable material; and

one or more pickup coils disposed on the pickup members of the stator core for sensing changes in a secondary magnetic filed generated by the eddy currents in the cup.