Electrically-actuated linear pump system and method

Abstract

An electrically-actuated linear pump includes a linear actuator housing coupled to a screw housing. A rod is configured to linearly translate within screw housing and the linear actuator housing, the rod includes a threaded portion disposed axially between a first plunger portion and a second plunger portion. A linear actuator is disposed within the linear actuator housing and includes a drive mechanism in meshed engagement with the threaded portion of the rod, the meshed engagement operable to linearly translate the rod, the linear actuator being electrically-actuated. The pump includes a first fluid end and a second fluid end disposed opposite the first fluid end, each fluid end configured to receive and discharge a fluid. Translation of the rod toward the first fluid end discharges the fluid from the first fluid end and simultaneously draws the fluid into the second fluid end.

What is claimed is: 
     
         1 . An electrically-actuated linear pump, comprising:
 a linear actuator housing;   a screw housing coupled to the linear actuator housing;   a rod configured to linearly translate within the screw housing, the rod comprising a threaded portion disposed axially between a first plunger portion and a second plunger portion;   a linear actuator disposed within the linear actuator housing and comprising a drive mechanism in meshed engagement with the threaded portion of the rod, the meshed engagement operable to linearly translate the rod, the linear actuator being electrically-actuated;   a first fluid end and a second fluid end disposed opposite the first fluid end, each fluid end configured to receive and discharge a fluid; and   wherein translation of the rod toward the first fluid end discharges the fluid from the first fluid end and simultaneously draws the fluid into the second fluid end.   
     
     
         2 . The electrically-actuated linear pump of  claim 1  wherein the linear actuator further comprises at least one electric motor operably coupled to the drive mechanism. 
     
     
         3 . The electrically-actuated linear pump of  claim 2  wherein the at least one electric motor is a permanent magnet motor. 
     
     
         4 . The electrically-actuated linear pump of  claim 1  wherein the linear actuator comprises a plurality of electric motors circumferentially spaced apart about an axis of the rod, each of the plurality of electric motors operably coupled to the drive mechanism. 
     
     
         5 . The electrically-actuated linear pump of  claim 4  wherein the drive mechanism comprises a plurality of rollers spaced apart circumferentially about the axis of the rod, each roller in meshed engagement the threaded portion of the rod. 
     
     
         6 . The electrically-actuated linear pump of  claim 1  wherein the drive mechanism comprises a planetary gear train. 
     
     
         7 . The electrically-actuated linear pump of  claim 6  wherein the linear actuator further comprises a plurality of electric motors, each operable to drive the planetary gear train. 
     
     
         8 . The electrically-actuated linear pump of  claim 1  further comprising a first plunger housing coupled to one end of the screw housing and a second plunger housing coupled to an opposite end of the screw housing, the first fluid end being coupled to the first plunger housing and the second fluid end being coupled to the second plunger housing. 
     
     
         9 . The electrically-actuated linear pump of  claim 1  wherein the rod functions as a sun gear in a planetary gear train. 
     
     
         10 . The electrically-actuated linear pump of  claim 1  further comprising an inverter operable to convert AC power to DC power, the DC power energizing the linear actuator. 
     
     
         11 . A pump system, comprising:
 a first electrically-actuated linear pump and a second electrically-actuated linear pump, each comprising:
 a linear actuator housing; 
 a screw housing coupled to the linear actuator housing; 
 a rod configured to linearly translate within the screw housing, the rod comprising a threaded portion disposed axially between a first plunger portion and a second plunger portion; 
 a linear actuator disposed within the linear actuator housing and comprising a drive mechanism in meshed engagement with the threaded portion of the rod, the meshed engagement operable to linearly translate the rod, the linear actuator being electrically-actuated; 
 a first fluid end and a second fluid end disposed opposite the first fluid end, each fluid end configured to receive and discharge a fluid; and 
 wherein translation of the rod toward the first fluid end discharges the fluid from the first fluid end and simultaneously draws the fluid into the second fluid end and translation of the rod toward the second fluid end discharges the fluid from the second fluid end and simultaneously draws the fluid into the first fluid end in a duty cycle; and 
   a controller configured to control outputs of the first and second electrically-actuated linear pumps.   
     
     
         12 . The pump system of  claim 11  wherein the duty cycle of the first electrically-actuated linear pump is out of phase with the duty cycle of the second electrically-actuated linear pump. 
     
     
         13 . The pump system of  claim 11  wherein the linear actuator of each of the first and second electrically-actuated linear pumps further comprises a plurality of electric motors circumferentially spaced apart about an axis of the rod, each of the plurality of electric motors operably coupled to the drive mechanism. 
     
     
         14 . The pump system of  claim 13  wherein the controller is configured to control the outputs of at least three electrically-actuated linear pumps. 
     
     
         15 . The pump system of  claim 11  wherein each of the first and second electrically-actuated linear pumps further comprises a first plunger housing coupled to one end of the screw housing and a second plunger housing coupled to an opposite end of the screw housing, the first fluid end being coupled to the first plunger housing and the second fluid end being coupled to the second plunger housing. 
     
     
         16 . A method of delivering a fluid to a wellbore, comprising:
 rotating at least one electric motor in a first rotational direction, the at least one electric motor operably coupled to a drive mechanism of a linear pump, the linear pump, comprising:
 a linear actuator housing; 
 a screw housing coupled to the linear actuator housing; 
 a rod configured to linearly translate within the screw housing, the rod comprising a threaded portion disposed axially between a first plunger portion and a second plunger portion; 
 a linear actuator disposed within the linear actuator housing and comprising the at least one motor and the drive mechanism, the drive mechanism in meshed engagement with the threaded portion of the rod; and 
 a first fluid end and a second fluid end disposed opposite the first fluid end, each fluid end configured to receive and discharge a fluid; 
 wherein rotation of the at least one electric motor in the first direction translates the rod toward the first fluid end to discharge the fluid from the first fluid end and simultaneously draw the fluid into the second fluid end; and 
   rotating the at least one motor in a second rotational direction opposite the first rotational direction, wherein rotation of the at least one electric motor in the second direction translates the rod toward the second fluid end to discharge the fluid from the second fluid end and simultaneously draw the fluid into the first fluid end.   
     
     
         17 . The method of  claim 16  further comprising sensing a rotational position of the drive mechanism. 
     
     
         18 . The method of  claim 16  wherein rotating the at least one motor in the first rotational direction displaces the rod about two meters. 
     
     
         19 . The method of  claim 16  wherein the at least one electric motor comprises a plurality of electric motors circumferentially spaced apart about an axis of the rod, each of the plurality of electric motors operably coupled to the drive mechanism. 
     
     
         20 . The method of  claim 19  wherein the drive mechanism of each of the first and second electrically-actuated linear pumps comprises a planetary gear train.