Permanent magnet rotary accelerometer

• US 6,427,534 B2
• Filed: 07/12/2001
• Issued: 08/06/2002
• Est. Priority Date: 09/24/1999
• Status: Expired due to Fees

• Current Assignee: Cda Astro Intercorp
• Original Assignee: Cda Astro Intercorp
• Inventors: Starin, Scott H., DʼAmico, Carmine
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/904,399
• Publication Number:
  US 20010037684A1
• Time in Patent Office: 390 Days
• Field of Search: 735/143.9, 735/190.1, 735/200.1, 324/174, 324/207.25
• US Class Current: 73/520.01
• 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 rotary accelerometer having a nonrotatable cylindrical magnet return path formed out of magnetic permeable material. One or more permanent magnets, with two opposite poles, are disposed around the magnetic return path. An electrically conductive cup with an access for rotation therearound in which the cup surrounds the permanent magnets and the permanent magnets are arranged so as to produce a magnetic field through the cup into the nonrotatable cylindrical magnet return path, thereby inducing eddy currents inside the cup when rotating in the magnetic field. A stator core is formed out of magnetic permeable material surrounding the cup and nonrotatable relative thereto, the stator core having at least two pickup members. The stator is formed from at least one continuous piece of magnetic permeable material. One or more stator windings are disposed on to the pickup members of the stator core for sensing changes in a secondary magnetic field generated by the eddy currents in the cup.

Claims

1. A rotary accelerometer comprising:

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

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

one or more sets of permanent magnets having opposite magnetic polarity mounted inside the cup, the one or more sets of permanent magnets producing a first magnetic field through the cup into the non-rotatable cylindrical magnetic return path for inducing eddy currents inside the electrically conductive cup when the electrically conductive cup is rotating in the first magnetic field;

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

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

2. A rotary accelerometer, comprising:

a housing defining an inner volume;

an electrically conductive rotatable cup positioned within the inner volume, the electrically conductive cup having an axis for rotation there around;

one or more sets of permanent magnets located within the inner volume having opposite magnetic polarity and being at least partially positioned about the axis for rotation, the one or more sets of permanent magnets a producing a first magnetic field through the cup and inducing eddy currents inside the cup when the cup is rotating in the first magnetic field;

a stator core formed out of magnetic permeable material concentrically arranged relative to the cup and nonrotatable relative to the cup, the stator core being located within the inner volume and comprising at least two pick up members positioned adjacent to the cup, the pick up members and the stator core being formed from at least one continuous piece of magnetic permeable material; and

one or more stator windings disposed on the pickup members of the stator core, the one or more stator windings sensing changes in a secondary magnetic field generated by the eddy currents in the cup.

3. The rotary accelerometer of claim 2, further comprising a mechanical input shaft coupled to the electrically conductive rotatable cup.

4. The rotary accelerometer of claim 3, wherein the mechanical input shaft is couplable to a rotating machine.

5. The rotary accelerometer of claim 4, wherein the rotating machine is a direct current stepper motor.

6. The rotary accelerometer of claim 4, wherein the rotating machine is a pneumatic machine.

7. The rotary accelerometer of claim 4, wherein the rotating machine is a combustion machine.

8. The rotary accelerometer of claim 2, wherein the stator core includes one or more sets of mounts and where the one or more sets of permanent magnets are held fixed on the mounts.

9. The rotary accelerometer according to claim 2, wherein the stator core is comprised of silicon iron.

10. The rotary accelerometer according to claims 2, wherein the stator core is comprised of Hyperco.

11. The rotary accelerometer according to claim 2, wherein there are a plurality of continuous pieces of magnetic permeable material forming the stator core, and wherein the stator core is a laminate.

12. The rotary accelerometer according to claim 2, wherein there are a plurality of continuous pieces of magnetic permeable material forming the stator core, and wherein the stator core is sintered.

13. The rotary accelerometer according to claim 2, wherein the one or more permanent magnets are bonded magnets.