Axisymmetric electropermanent magnets

Patent metadata

Field	Value
Publication number	US-10971292-B2
Application number	US-201716466409-A
Country	US
Kind code	B2
Filing date	Dec 7, 2017
Priority date	Dec 7, 2016
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

Embodiments of the subject invention relate to an electropermanent magnet core (EPM core) having two permanent magnets (or two permanent magnet portions where each portion can have one or more permanent magnets), including a fixed permanent magnet portion and a switching permanent magnet portion, where a switching magnetic field is used to switch the magnetization of the switching permanent magnet portion, but not switch the magnetization of the fixed permanent magnet portion. In this way, the fixed permanent magnet portion has a fixed magnetization, such that the direction of magnetization of the fixed permanent magnet portion remains the same during switching of the magnetization of the switching permanent magnet portion, given the magnitude and duration of the switching magnetic field used to switch the magnetization of the switching permanent magnet portion, and the switching permanent magnet portion has a switching magnetization, such that the direction of magnetization of the switching permanent magnet portion is switched during switching of the magnetization of the switching permanent magnet portion, given the magnitude and duration of the switching magnetic field used to switch the magnetization of the switching permanent magnet portion.

First claim

The invention claimed is:

1. A switchable magnet, comprising:
a magnet assembly,
wherein the magnet assembly comprises:
at least one fixed magnet having a first direction of magnetization from a south end of the at least one fixed magnet to a north end of the at least one fixed magnet,
wherein the first direction of magnetization is in a first direction;
at least one switching magnet having a second direction of magnetization from a south end of the at least one switching magnet to a north end of the at least one switching magnet,
wherein the at least one fixed magnet and the at least one switching magnet are permanent magnets, and
wherein:
(i) one or more fixed magnets of the at least one fixed magnet are positioned at least partially within a corresponding one or more bores through a first switching magnet of the at least one switching magnet; or
(ii) one or more switchable magnets of the at least one switching magnet are positioned at least partially within a corresponding one or more bores through a first fixed magnet of the at least one fixed magnet,

wherein:
(i) when the second direction of magnetization is in the first direction and an on-to-off switching magnetic field is positioned with respect to the magnet assembly for a first period of time, the on-to-off switching magnetic field switches the second direction of magnetization from the first direction to a second direction, where the second direction is an opposite to the first direction, and does not switch the first direction of magnetization; and
(ii) when the second direction of magnetization is in the second direction and an off-to-on switching magnetic field, where the off-to-on switching magnetic field is in an opposite direction to the on-to-off switching magnetic field, is positioned with respect to the magnet assembly for a second period of time, the off-to-on switching magnetic field switches the second direction of magnetization from the second direction to the first direction, and does not switch the first direction of magnetization.

2. The switchable magnet according to claim 1 , further comprising:
a first shunt plate,
wherein the first shunt plate is positioned with respect to a top of the magnet assembly such that:
(i) when the second direction of magnetization is in the first direction, an on state fixed magnetic flux exits out of the north end of the at least one fixed magnet and enters the first shunt plate, an on state switching magnetic flux exits out of the north end of the at least one switching magnet and enters the first shunt plate, and an on state external magnetic flux exits out of the first shunt plate and enters a bottom of the magnet assembly, such that the on state external magnetic flux creates an on state external magnetic field; and
(ii) when the second direction of magnetization is in the second direction, an off state magnetic flux exits out of the north end of the at least one fixed magnet and enters the first shunt plate, an off state switching magnetic flux exits out of the north end of the at least one switching magnet and enters the bottom of the magnet assembly, and an off state external magnetic flux exits out of the first shunt plate and enters the bottom of the magnet assembly, such that the off state external magnetic flux creates an off state external magnetic field.

3. The switchable magnet according to claim 1 , further comprising:
a first shunt plate; and
a second shunt plate,
wherein the first shunt plate and the second shunt plate are positioned with respect to the magnet assembly such that:
(i) when the second direction of magnetization is in the first direction, an on state fixed magnetic flux exits out of the north end of the at least one fixed magnet and enters the first shunt plate, an on state switching magnetic flux exits out of the north end of the at least one switching magnet and enters the first shunt plate, and an on state external magnetic flux exits out of the first shunt plate and enters the second shunt plate, such that the on state external magnetic flux creates an on state external magnetic field; and
(ii) when the second direction of magnetization is in the second direction, an off state magnetic flux exits out of the north end of the at least one fixed magnet and enters the first shunt plate, an off state switching magnetic flux exits out of the north end of the at least one switching magnet and enters the second shunt plate, and an off state external magnetic flux exits out of the first shunt plate and enters the second shunt plate, such that the off state external magnetic flux creates an off state external magnetic field.

4. The switchable magnet according to claim 1 , further comprising:
a coil,
wherein the coil is positioned with respect to the magnet assembly such that:
(i) when the second direction of magnetization is in the first direction and a first coil current is passed through the coil for the first period of time, the first coil creates the on-to-off switching magnetic field that switches the second direction of magnetization from the first direction to the second direction, and does not switch the first direction of magnetization; and
(ii) when the second direction of magnetization is in the second direction and a second coil current, where the second coil current is in an opposite direction to the first coil current, is passed through the coil for a second period of time, the second coil creates the off-to-on switching magnetic field that switches the second direction of magnetization from the second direction to the first direction, and does not switch the first direction of magnetization.

5. The switchable magnet according to claim 4 ,
wherein the coil is integrated with the magnet assembly.

6. The switchable magnet according to claim 4 ,
wherein the coil is separate from the magnet assembly.

7. The switchable magnet according to claim 1 ,
wherein the one or more fixed magnets of the at least one fixed magnet are positioned within the corresponding one or more bores through the first switching magnet of the at least one switching magnet.

8. The switchable magnet according to claim 7 ,
wherein the one or more fixed magnets of the at least one fixed magnet is a first fixed magnet, and the at least one switching magnet is a first switching magnet of the at least one switching magnet, such that the first fixed magnet is positioned within a bore through the first switching magnet.

9. The switchable magnet according to claim 8 ,
wherein the first fixed magnet and the first switching magnet are coaxial.

10. The switchable magnet according to claim 8 ,
wherein the first fixed magnet and the first switching magnet are concentric.

11. The switchable magnet according to claim 8 ,
wherein the coil is positioned with respect to the magnet assembly such that:
(i) when the first coil current is passed through the coil for the first period of time, the first fixed magnet and the first switching magnet are exposed to the first coil created magnetic field; and
(ii) when the second coil current is passed through the coil for the second
period of time, the first fixed magnet and the first switching magnet are exposed to the second coil created magnetic field.

12. The switchable magnet according to claim 8 ,
wherein the coil is positioned with respect to the magnet assembly such that:
(i) when the first coil current is passed through the coil for the first period of time, the first switching magnet is exposed to the first coil created magnetic field, and the first fixed magnet is not exposed to the first coil created magnetic field; and
(ii) when the second coil current is passed through

Assignees

• Univ Florida

Inventors

• Arnold David P
• Velez Cuervo Camilo

Classifications

• H01F13/003 Primary

  Methods and devices for magnetising permanent magnets (permanent magnets H01F7/02) · CPC title

• H01F7/0226 Primary

  PM with variable field strength (H01F7/0284 takes precedence) · CPC title

• H01F7/20

  without armatures (cores H01F3/00; coils H01F5/00 {; shaping metal by applying magnetic forces B21D26/14; electromagnets specially adapted for NMR applications G01R33/381}) · CPC title