Magnetic rotational to linear actuator for well pumps

Patent metadata

Field	Value
Publication number	US-9726166-B2
Application number	US-201414566379-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Dec 10, 2014
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A well pump includes a plunger reciprocally carried within a barrel between up stroke and down stroke positions. A tubular linear actuator housing located below the barrel has a rotatable rotor. An array of rotor magnets is mounted to the rotor, directing rotor magnetic fields in an outward direction. A cage is fixed against rotation relative to the housing and carried within the housing for axial movement relative to the rotor and the housing. The cage has a cylindrical inner sidewall surrounding the outer sidewall of the rotor. An array of cage magnets is mounted to the inner sidewall of the cage. The cage magnets direct cage magnetic fields in an inward direction relative to the axis. The cage and rotor magnetic fields interact such rotation of the rotor causes axial movement of the cage. A motor rotates the rotor.

First claim

The invention claimed is:

1. A reciprocating well pump assembly, comprising:
a barrel having an axis;
a plunger reciprocally carried within the barrel between an up stroke and a down stroke;
a tubular linear actuator housing;
a rotating member having a cylindrical outer sidewall and mounted in the housing for rotation about the axis relative to the housing;
upper and lower bearing carriers rigidly secured to the housing above and below the rotating member, each having a radial bearing that receives an end of the rotating member for radially supporting the rotating member, the upper bearing carrier having a plurality of openings offset from the axis;
an array of rotating member magnets mounted to the outer sidewall of the rotating member;
a nonrotating member between the upper and lower bearing carriers and having a cylindrical inner sidewall surrounding the outer sidewall of the rotating member;
a plurality of connector members mounted to an upper end of the nonrotating member and extending upward through the openings in the upper bearing carrier, the connector members and the openings being engaged with each other to prevent rotation of the nonrotating member relative to the upper bearing carrier and the housing, but allow axial movement of the nonrotating member relative to the upper bearing carrier and the housing;
a plunger connector that connects the plunger to the connector members such that axial movement of the nonrotating member strokes the plunger;
an array of nonrotating member magnets mounted to the inner sidewall of the nonrotating member, the nonrotating member magnets having magnetic fields that interact with magnetic fields of the rotating member magnets such that rotation of the rotating member causes axial movement of the nonrotating member;
a motor cooperatively engaged with the rotating member for rotating the rotating member; and
reversing means for reversing a direction of rotation of the rotating member at a top of the up stroke and at a bottom of the down stroke of the plunger.

2. The assembly according to claim 1 , wherein:
the magnetic fields of the rotating member magnets are directed outward relative to the axis; and
the magnetic fields of the nonrotating member magnets are directed inward relative to the axis.

3. The assembly according to claim 1 , wherein:
the array of nonrotating member magnets has a lower end that is adjacent a lower end of the array of rotating member magnets while at the bottom of the down stroke, and an upper end that is adjacent an upper end of the array of rotating member magnets while at the top of the up stroke.

4. The assembly according to claim 1 , wherein:
each of the connector members has an axial length from the rod connector to the upper end of the nonrotating member that is greater than an axial length of the array of nonrotating member magnets.

5. The assembly according to claim 1 , wherein:
the array of rotating member magnets comprises a row of individual rotating member magnets side by side along a helical line along the rotating member; and
the array of nonrotating member magnets comprises a row of individual nonrotating member magnets side by side along a helical line along the nonrotating member.

6. The assembly according to claim 1 , wherein:
the array of rotating member magnets extends along a rotating member helical line along the outer sidewall of the rotating member, the rotating member helical line having multiple turns encircling the outer sidewall, the turns of the rotating member helical line being spaced apart from each other by a selected rotating member magnet pitch; and
the array of nonrotating member magnets extends along a nonrotating member helical line along the inner sidewall of the nonrotating member, the nonrotating member helical line having multiple turns encircling the inner sidewall, the turns of the nonrotating member helical line being spaced apart from each other by a nonrotating member magnet pitch that is the same as the rotating member magnet pitch.

7. The assembly according to claim 1 , further comprising a controller that supplies power to the motor, and wherein the reversing means comprises:
a timer selected to provide an estimated elapsed time between the bottom of the down stroke to the top of the up stroke and between the top of the up stroke to the bottom of the down stroke, and providing signals to the controller to reverse a direction of the motor.

8. The assembly according to claim 1 , wherein:
the array of nonrotating member magnets has an axial length that is less than an axial length of the array of rotating member magnets.

9. The assembly according to claim 1 , further comprising:
a controller that supplies power to the motor, and wherein the reversing means comprises:
an up stroke sensor mounted to the assembly that senses when the plunger nears the top of the up stroke;
a down stroke sensor mounted to the assembly that senses when the plunger nears the bottom of the down stroke; and
the up stroke and the down stroke sensors being in electrical communication with the controller to reverse a direction of the power being supplied to the motor upon receipt of a signal from the up stroke sensor and a signal from the down stroke sensor.

10. A reciprocating well pump assembly, comprising:
a barrel having an axis;
a plunger reciprocally carried within the barrel between an up stroke and a down stroke;
a tubular linear actuator housing located below the barrel;
a rotor mounted in the housing for rotation relative to the housing, the rotor having a cylindrical outer sidewall;
upper and lower bearing carriers rigidly secured to the housing above and below the rotating member, each having a radial bearing that receives an end of the rotor for radially supporting the rotor, the upper bearing carrier having a plurality of openings spaced around the axis;
an array of rotor magnets mounted to the outer side wall of the rotor, the rotor magnets directing rotor magnetic fields in an outward direction relative to the axis;
a cage carried within the housing for axial movement relative to the rotor and the housing, the cage having a cylindrical inner sidewall surrounding the outer sidewall of the rotor;
an array of cage magnets mounted to the inner sidewall of the cage and surrounding the rotor magnets, the cage magnets directing cage magnetic fields in an inward direction relative to the axis, the cage and rotor magnetic fields interacting such rotation of the rotor causes axial movement of the cage;
a plurality of connector members mounted to an upper end of the cage and extending upward through the openings in the upper bearing carrier, the connector members engaging the openings to prevent rotation of the cage relative to the upper bearing carrier and the housing, but allow axial movement of the cage relative to the upper bearing carrier and the housing;
a plunger connector that connects the plunger to the connector members above the upper bearing carrier such that axial movement of the nonrotating member strokes the plunger;
a motor cooperatively engaged with the rotor for rotating the rotor; and
reversing means for reversing a direction of rotation of the rotor at a top of the up stroke and at a bottom of the down stroke.

11. The assembly according to claim 10 , further comprising a controller that supplies power to the motor, and wherein the reversing means comprises:
a timer selected to provide an estimated elapsed time for moving from the bottom of the down stroke to the top of the up stroke and for moving from the top of the upstroke to the bottom of the down stroke, and providing signals to the controller to reverse a direction of the motor

Assignees

• Baker Hughes Inc

Inventors

• Tetzlaff Steven K
• Lawson Peter F
• Bierig Kevin R
• Robinson Lance T
• Cain Sean A

Classifications

• H02K7/06

  Means for converting reciprocating motion into rotary motion or vice versa · CPC title

• E21B43/128

  Adaptation of pump systems with down-hole electric drives · CPC title

• F04B9/047

  the means being pin-and-slot mechanisms · CPC title

• F04B47/06 Primary

  having motor-pump units situated at great depth · CPC title

• F04B17/03

  driven by electric motors · CPC title