Patent attributes
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.