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An energy-recovery pump or pumping system includes, in a double action embodiment, first and second cylinders wherein respective first and second pistons, mounted to a common reciprocating piston shaft, are mounted for reciprocating motion. A hydraulic pump drives the common piston shaft back and fo

An energy-recovery pump or pumping system includes, in a double action embodiment, first and second cylinders wherein respective first and second pistons, mounted to a common reciprocating piston shaft, are mounted for reciprocating motion. A hydraulic pump drives the common piston shaft back and forth in accordance with a prescribed velocity profile that includes acceleration, constant velocity, and deceleration periods, as well as a short dwell time at the conclusion of each stroke during which the shaft and pistons remain stopped. Each piston divides each cylinder into first and second working volumes. Input and output valves connect a source of fluid with an output header through half of the working volumes in such a way that the fluid is received within whichever working volume is expanding and is pumped from whichever working volume is contracting, as the pistons move back and forth within their respective cylinders during a pump cycle. Energy recovery valves selectively connect a second fluid under pressure with whichever of the other half of the working volumes is expanding so that the pressure force associated with the second fluid assists in moving the respective piston during the appropriate portion of the pump cycle. The second fluid is discharged from the respective working volumes through discharge valves as such working volumes contract during the pump cycle. The energy recovery and discharge valves are switched from one position to another only when the pistons are stopped for the short dwell time at the end of a forward or backward stroke.

대표청구항 ▼

[ What is claimed is:] [1.] A positive displacement, energy recovery, fluid pump comprising:cylinder means wherein a piston is mounted for reciprocating motion, said piston defining a first working volume within said cylinder bounded by one side of the piston and a second working volume bounded by t

[ What is claimed is:] [1.] A positive displacement, energy recovery, fluid pump comprising:cylinder means wherein a piston is mounted for reciprocating motion, said piston defining a first working volume within said cylinder bounded by one side of the piston and a second working volume bounded by the other side of the piston;controlled power means coupled to the piston for generating forces that move the piston through a pump cycle that comprises a forward stroke and a backward stroke;said controlled power means including means for creating a dwell period during which the piston is stopped at the end of each forward and backward stroke;first valve means for directing a first fluid available at an input header into the first working volume when the piston stroke direction causes the first working volume to expand, and for allowing the first fluid to flow out of the first working volume under pressure to an output header when the piston stroke direction causes the first working volume to contract;second valve means including an inlet valve and a discharge valve for selectively directing a second fluid under pressure into the second working volume when the piston stroke direction causes the second working volume to expand, and for directing the second fluid out of the second working volume to a discharge header when the piston stroke direction causes the second working volume to contract; anda control unit for selectively opening and closing the inlet and discharge valves of second valve means only during the dwell periods,whereby a pressure force associated with the second fluid augments the forces produced by said power means to thereby assist in moving the piston through at least a portion of its pump cycle and whereby wear on the valves of said second valve means is significantly reduced.