Magnetic latching actuator

• US 8,279,027 B2
• Filed: 05/08/2009
• Issued: 10/02/2012
• Est. Priority Date: 05/08/2009
• Status: Active Grant

• Current Assignee: Sensus Spectrum, LLC (Xylem, Inc.)
• Original Assignee: Sensus Spectrum, LLC (Xylem, Inc.)
• Inventors: Brown, Michael R., Mazza, William R. Jr., Burstall, Oliver, Dames, Andrew
• Primary Examiner(s): Rojas, Bernard
• Application Number:
  US12/437,596
• Publication Number:
  US 20100283561A1
• Time in Patent Office: 1,243 Days
• Field of Search: 335220-229, 335/106, 335/127, 335131-133, 335167-171, 335/179, 335/190, 335/194, 335/195
• US Class Current: 335/167
• CPC Class Codes: H01F 7/1646 Armatures or stationary parts of magnetic circuit having permanent magnet
• CPC Class Codes: H01H 51/2209 with rectilinearly movable armature

Abstract

A magnetic latching actuator operable to control the movement of at least a first contact and second contact between a closed position in which the contacts physically engage each other and an open position in which the contacts are spaced from each other. The magnetic latching actuator includes first and second stationary permanent magnets oriented such that the first magnetic field created by the first magnet and the second magnetic field created by the second magnet are in opposite directions. An actuation coil surrounds both the first and second magnets. Current is supplied to the actuation coil in a first direction to create a first magnetic field or a second direction to create a second actuation magnetic field opposite the first actuation magnetic field. A yoke is movable relative to the first and second magnets to cause the first and second contacts to move between the open and closed positions.

Claims

1. A magnetic latching actuator, comprising:

a first stationary permanent magnet positioned to create a first magnetic field having a first polarity;

a second stationary permanent magnet positioned relative to the first permanent magnet to create a second magnetic field having a second polarity opposite the first polarity;

a magnet housing that receives and retains the first and second permanent magnets;

a yoke positioned to surround at least a portion of the magnetic housing and movable relative to the first and second permanent magnets between a first position and a second position, wherein the yoke is held in the first position by the first magnet and is held in the second position by the second magnet; and

an actuation coil surrounding both the first and second permanent magnets and contained within the magnetic housing, wherein the actuation coil is operable to generate an actuation magnetic field that creates a actuation force in either a first direction or an opposite, second direction to cause the yoke to move between the first and second positions.

2. The magnetic latching actuator of claim 1 wherein the actuation coil includes a plurality of windings.

3. The magnetic latching actuator of claim 1 further comprising a pole piece formed from a permeable material and positioned between the first and second magnets.

4. The magnetic latching actuator of claim 1 wherein the actuation coil is connected to a supply of current selectively flowing in either a first direction or a second direction, wherein the direction of the actuation force is in the first direction upon connection to current flowing in the first direction and the direction of the actuation force is in the second direction upon connection to current flowing in the second direction.

5. The magnetic latching actuator of claim 1 wherein the magnet housing has at least one guide rib received in at least one guide slot formed in the yoke.

6. A magnetic latching actuator operable to control the movement of a first contact between a closed position in which the first contact physically engages a second contact and an open position in which the first and second contacts are spaced from each other, comprising:

a first magnet positioned to create a first magnetic field having a first polarity;

a second magnet positioned relative to the first magnet to create a second magnetic field having a second polarity opposite the first polarity;

a magnet housing that receives and retains the first and second permanent magnets;

an actuation coil surrounding both the first and second magnets, wherein the actuation coil is operable to create an actuation magnetic field having either the first polarity or the second polarity; and

a yoke positioned to surround at least a portion of the magnet housing and movable along the magnet housing relative to the first and second magnets between a first position and a second position, wherein the yoke is held in the first position by the first magnet and is held in the second position by the second magnet.

7. The magnetic latching actuator of claim 6 wherein at least the first position of the yoke is determined by the physical engagement between the first and second contacts.

8. The magnetic latching actuator of claim 6 wherein the actuation coil includes a plurality of windings connected to a variable direction current supply such that the actuation magnetic field can have either the first polarity or the second polarity.

9. The magnetic latching actuator of claim 7 wherein the yoke is formed as part of an armature that engages the first contact, wherein movement of the yoke between the first and second positions opens and closes the first and second contacts through engagement of the armature with the first contact.

10. The magnetic latching actuator of claim 7 wherein the armature engages the first contact at a location generally aligned with a contact pad formed on the first contacts such that the armature applies a force to the first contact near the contact pad.

11. The magnetic latching actuator of claim 7 wherein the yoke includes a first yoke section and a second yoke section each formed from a permeable material.

12. The magnetic latching actuator of claim 11 wherein the magnet housing includes at least one guide rib received within at least one guide slot formed between the first and second yoke sections of the yoke.

13. The magnetic latching actuator of claim 7 further comprising a pole piece positioned between the first and second permanent magnets, wherein the pole piece is formed from a permeable material.

14. A method of operating a magnetic latching actuator to move a first and a second contact between a closed position and an open position, comprising the steps of:

positioning a first permanent magnet within a magnetic housing to create a first magnetic field having a first polarity;

positioning a second permanent magnet within the magnetic housing adjacent to the first permanent magnet to create a second magnetic field having a second polarity opposite the first polarity;

surrounding the first and second permanent magnets with an actuation coil including a plurality of windings;

mounting a yoke around both of the permanent magnets and the actuation coil in the magnetic housing, wherein the yoke is movable relative to the first and second permanent magnets;

supplying current to the plurality of windings in a first direction to create a first actuation magnetic field having the first polarity cause the yoke to move toward alignment with the first permanent magnet; and

supplying current to the plurality of windings in a second direction to create a second actuation magnetic field having the second polarity to cause the yoke to move toward alignment with the second permanent magnet.

15. The method of claim 14 further comprising the step of positioning a pole piece formed from a permeable material between the first and second permanent magnet.

16. The method of claim 14 wherein the first and second permanent magnets are stationary relative to each other.

17. The method of claim 14 wherein the yoke is formed as part of an armature that engages the first contact, wherein movement of the yoke between the first and second positions opens and closes the first and second contacts through engagement of the armature with the first contact.

18. The method of claim 17 wherein movement of the yoke is limited by the physical engagement between the first and second contacts.

19. The method of claim 14 wherein the yoke is formed from a permeable material such that the first and second permanent magnets hold the yoke in alignment with either the first permanent magnet or the second permanent magnet.