Co-axial inverted piston linear actuator pumping system

Patent metadata

Field	Value
Publication number	US-11635071-B2
Application number	US-202117152959-A
Country	US
Kind code	B2
Filing date	Jan 20, 2021
Priority date	Jan 21, 2020
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

A pumping system for fracking fluid is designed to provide nearly constant flow rate. The pumping system includes a set of linear actuator pumping units, each driven by at least one electric motor. Each pumping unit includes a hollow threaded shaft driven by the linear actuator, two hollow cylinders fixed to an interior of the hollow shaft, and hollow pistons in each of the hollow cylinders. The hollow cylinders and hollow pistons form two pumping chambers. A first pumping chamber expels fluid when the linear actuator is moving in a first direction and a second pumping chamber that expels fluid when the linear actuator is moving in an opposite direction. The speeds of the actuators are coordinated such that a total flow rate of the pumping system is substantially constant.

First claim

What is claimed is:

1. A pumping unit comprising:
a housing;
a hollow threaded shaft supported for translation along an axis with respect to the housing and restrained against rotation about the axis with respect to the housing;
a linear actuator configured to rotate a nut about the axis, in response to power provided to at least one motor and to translate the hollow threaded shaft along the axis, in response to rotation of the nut;
a first cylinder fixed to an interior of the hollow threaded shaft to translate with the hollow threaded shaft along the axis;
a first hollow piston fixed to the housing and extending into the first cylinder such that the first cylinder and the first piston define a first chamber having a first volume which varies in response to translation of the hollow threaded shaft;
a first inlet valve configured to alternately fluidly connect the first chamber to a fluid source and separate the first chamber from the fluid source;
a first outlet valve configured to alternately fluidly connect the first chamber to a fluid sink and separate the first chamber from the fluid sink;
a second cylinder fixed to the interior of the hollow threaded shaft to translate with the hollow threaded shaft along the axis;
a second hollow piston fixed to the housing and extending into the second cylinder such that the second cylinder and the second piston define a second chamber having a second volume which varies in response to translation of the hollow threaded shaft;
a second inlet valve configured to alternately fluidly connect the second chamber to the fluid source and separate the second chamber from the fluid source; and
a second outlet valve configured to alternately fluidly connect the second chamber to the fluid sink and separate the second chamber from the fluid sink wherein the housing defines at least a portion of the first and second chambers.

2. The pumping unit of claim 1 wherein a sum of the first volume and the second volume is independent of an axial position of the hollow threaded shaft.

3. The pumping unit of claim 1 wherein:
the at least one motor comprises a plurality of motors arranged circumferentially around the axis; and
the linear actuator comprises the nut, a ring gear fixed to the nut, and a plurality of pinion gears, each pinion gear meshing with the ring gear and fixed to a rotor of a respective one of the plurality of motors.

4. The pumping unit of claim 1 wherein the first cylinder is mounted within the hollow threaded shaft such that a radial gap exists between an outer wall of the cylinder and an interior wall of the hollow threaded shaft.

5. A pumping system comprising:
a plurality of pumping units according to claim 1 ; and
a controller configured to vary a flow rate of each of the pumping units such that a total flow rate is substantially constant.

6. The pumping system of claim 5 wherein the flow rate of each pumping unit includes a series of alternating increasing phases and decreasing phases, each increasing phase coordinated with a decreasing phase of another of the pumping units, each decreasing phase coordinated with an increasing phase of another of the pumping units.

7. The pumping system of claim 6 wherein each decreasing phase is separated from a previous increasing phase by a constant flow phase.

8. The pumping unit of claim 1 , wherein the first cylinder is arranged adjacently to the second cylinder.

9. The pumping unit of claim 1 , wherein the first cylinder is coaxial to the second cylinder.

10. The pumping unit of claim 1 , wherein the first cylinder abuts with the second cylinder.

Assignees

• Schaeffler Technologies Ag

Inventors

• Vazquez Andre
• Hooker Craig
• Conlin Michael

Classifications

• F04B1/02

  having two cylinders (in V-arrangement F04B1/04) · CPC title

• F04B49/106

  Responsive to pumped volume · CPC title

• F04B9/02

  the means being mechanical · CPC title

• F04B23/06 Primary

  the pumps being all of reciprocating positive-displacement type · CPC title

• F04B19/022

  reciprocating cylinders · CPC title