Reciprocating positive displacement pump with electric reversing motor

Patent metadata

Field	Value
Publication number	US-10072652-B2
Application number	US-201214343475-A
Country	US
Kind code	B2
Filing date	Sep 10, 2012
Priority date	Sep 9, 2011
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A pump system comprises an electric motor, a pump, a converter and a controller. The electric motor has a rotational output shaft that is rotatable in a first rotational direction and an opposite second rotational direction. The pump has a linearly displaceable input shaft that is movable in a first linear direction and an opposite second linear direction. The converter couples the output shaft to the input shaft such that rotation of the output shaft in the first rotational direction translates the input shaft in the first linear direction, and rotation of the output shaft in the second rotational direction translates the input shaft in the second linear direction. The controller repeatedly reverses rotation of the output shaft to produce reciprocating motion of the input shaft.

First claim

The invention claimed is:

1. A pump system comprising:
an electric motor having an output shaft that is reversibly rotatable in a first rotational direction and an opposite second rotational direction;
a pump having an input shaft that is movable in a first linear direction and an opposite second linear direction;
a rack and pinion converter coupling the output shaft to the input shaft such that:
rotation of the output shaft in the first rotational direction translates the input shaft in the first linear direction;
rotation of the output shaft in the second rotational direction translates the input shaft in the second linear direction; and

a controller that repeatedly reverses rotation of the output shaft to produce reciprocating motion of the input shaft; and
wherein the controller reverses current flow direction of current provided to the electric motor to reverse rotation of the output shaft and wherein the controller progressively increases a magnitude of a stroke length of the pump shaft to a maximum stroke length and then progressively decreases the magnitude of the stroke length to a minimum stroke length to vary which gear teeth of the rack and pinion system converter are engaged when rotation reversal occurs so that shock loading is distributed over time among a number of different gear teeth.

2. The pump system of claim 1 wherein the pump comprises a positive displacement pump.

3. The pump system of claim 1 wherein the converter further comprises a gear reduction system.

4. The pump system of claim 3 wherein the gear reduction system comprises a two-stage speed reducing system.

5. The pump system of claim 1 further comprising:
wherein the electric motor comprises a brushless direct current motor.

6. The pump system of claim 5 wherein the controller maintains a constant torque output of the electric motor.

7. The pump system of claim 5 wherein the controller varies time between current flow direction reversals from one reversal to the next.

8. A method of operating a pump, the method comprising:
repeatedly reversing current flow direction to an electric motor to cause alternating rotation of an output shaft of the motor in clockwise and counterclockwise directions wherein:
rotation of the output shaft in the clockwise direction produces linear movement of the pump shaft in a first direction; and
rotation of the output shaft in the counterclockwise direction produces linear movement of the pump shaft in a second, opposite direction; and

converting the alternating rotation of the output shaft to reciprocating linear motion of a pump shaft, wherein converting the alternating rotation of the output shaft to reciprocating linear motion of the pump shaft comprises:
rotating a pinion gear with the output shaft; and
translating a rack gear with the pinion gear;

varying which gear teeth of the rack gear and the pinion gear are engaged when rotation reversal occurs so that shock loading is distributed over time among a number of different gear teeth, by one of:
varying a time interval between current flow direction reversals to achieve at least one of an upper piston position limit or a decrease of a lower piston position limit; or
varying a change-over position of the pump shaft where the pump shaft reverses linear translation; or
progressively increasing a magnitude of a stroke length of the pump shaft to a maximum stroke length and then progressively decreasing the magnitude of the stroke length to a minimum stroke length.

9. The method of claim 8 wherein:
the electric motor comprises a brushless direct current motor; and
the pump comprises a positive displacement pump.

10. The method of claim 8 further comprising:
supplying a constant flow of current to the electric motor to maintain a constant torque; and
maintaining a constant pressure output at the pump.

11. The method of claim 8 wherein the time between current flow direction reversals is varied in a non-uniform pattern.

12. A pump system comprising:
a brushless direct current electric motor having a rotational output shaft;
a positive displacement pump having a linearly displaceable input shaft;
a rack and pinion conversion system coupling the output shaft to the input shaft such that clockwise rotation of the output shaft translates the input shaft in a first direction and counterclockwise rotation of the output shaft translates the input shaft in a second direction that is opposite to the first direction; and
a controller that repeatedly reverses rotation direction of the output shaft to produce reciprocating translation of the input shaft, and wherein the controller varies stroke length of the pump shaft to vary which gear teeth of the rack and pinion conversion system are engaged when rotation reversal occurs so that shock loading is distributed over time among a number of different gear teeth.

13. The pump system of claim 12 wherein the rack and pinion conversion system comprises:
a pinion gear coupled to the output shaft;
a rack gear coupled to the input shaft; and
a gear reduction system coupled to the pinion gear and the rack gear.

14. A pump system comprising:
an electric motor having an output shaft that is reversibly rotatable in a first rotational direction and an opposite second rotational direction;
a pump having an input shaft that is movable in a first linear direction and an opposite second linear direction;
a rack and pinion converter coupling the output shaft to the input shaft such that:
rotation of the output shaft in the first rotational direction translates the input shaft in the first linear direction;
rotation of the output shaft in the second rotational direction translates the input shaft in the second linear direction; and

a controller that repeatedly reverses rotation of the output shaft to produce reciprocating motion of the input shaft; and
wherein the controller reverses current flow direction of current provided to the electric motor to reverse rotation of the output shaft and wherein the controller varies a time interval between current flow direction reversals to vary which gear teeth of the rack and pinion converter are engaged when rotation reversal occurs so that shock loading is distributed over time among a number of different gear teeth.

15. The pump system of claim 14 wherein the pump comprises a positive displacement pump.

16. The pump system of claim 14 wherein the converter further comprises a gear reduction system.

17. The pump system of claim 16 wherein the gear reduction system comprises a two-stage speed reducing system.

18. The pump system of claim 14 further comprising:
wherein the electric motor comprises a brushless direct current motor.

19. The pump system of claim 18 wherein the controller maintains a constant torque output of the electric motor.

20. A method of operating a pump, the method comprising:
repeatedly reversing current flow direction to an electric motor to cause alternating rotation of an output shaft of the motor in clockwise and counterclockwise directions; and
converting the alternating rotation of the output shaft to reciprocating linear motion of a pump shaft through a gear reduction and rack and pinion gear system;
varying a time interval between current flow direction reversals to vary at least one of an upper piston position limit, or a lower piston position limit, or a pinion stroke length, so that different gear teeth of the gear reduction and rack and pinion system are engaged when rotation reversals of th

Assignees

• Roman Timothy S
• Mrozek Greg T
• Graco Minnesota Inc

Inventors

• Roman Timothy S
• Mrozek Greg T

Classifications

• F04B2203/0209

  Rotational speed · CPC title

• F04B17/03 Primary

  driven by electric motors · CPC title

• F04B2201/0201

  Position of the piston · CPC title

• F04B49/12 Primary

  by varying the length of stroke of the working members · CPC title

• F04B49/06

  Control using electricity (regulating by means of floats actuating electric switches F04B49/04) · CPC title