Pumps are provided, more particularly piston type pumps having increased energy efficiency, systems incorporating such piston type pumps, and methods of operating piston type pumps. The pumps are suitable for pumping of oil from an oil well or for pumping other liquids such as ground water, subterranean liquids, brackish water, sea water, waste water, cooling water, gas, coolants, and the like.

A piston for a single-stroke pump includes a pump rod, a seal ring extending about the pump rod and having a central bore, and a retaining device disposed on the pump rod and retaining the seal ring on the pump rod. In a forward stroke, the seal ring is in a first position whereby the seal ring sealingly engages the pump rod such that the seal ring and pump rod drive a fluid out of the pump chamber. When transitioning to a return stroke, the seal ring is maintained stationary relative to the pump cylinder until retaining device engages seal ring, such that seal ring is in a second position. With the seal ring in the second position, a flow path is opened between the seal ring and the pump rod, allowing fluid to flow into the pump chamber to prime the pump the next pump cycle.

A system for energy recovery from a rod pump includes, in an exemplary embodiment, a hydraulic cylinder having a barrel, a piston, and a pressure chamber; the piston connected to a rod string of the rod pump; a reversible hydraulic pump connected to the pressure chamber; and a motor-generator having a rotor shaft connected to a coupling shaft of the pump; wherein the motor-generator operates in a motor mode to rotate the rotor and coupling shafts in a forward direction so that the hydraulic pump pumps hydraulic fluid to the pressure chamber to raise the piston and rod string in an upstroke, and operates in a generator mode in which a weight of the rod string displaces the piston in a downstroke to pump hydraulic fluid from the pressure chamber to rotate the pump coupling shaft and the rotor shaft in a reverse direction such that the motor-generator generates electricity.

A linear compressor includes: a piston configured to reciprocate along an axial direction of the linear compressor; a resonance spring configured to elastically support the piston along the axial direction; a motor assembly configured to provide a driving force to the piston, the motor assembly including a magnet that is disposed radially outside the piston; and a supporter configured to be coupled to the piston, the magnet, and the resonance spring. The supporter includes: a piston coupler coupled with the piston; a magnet coupler coupled with the magnet; and a spring coupler coupled with the resonance spring. The piston coupler, the magnet coupler, and the spring coupler are integrally formed by aluminum die casting.

A linear compressor includes: a piston configured to reciprocate along an axial direction of the linear compressor; a resonance spring configured to elastically support the piston along the axial direction; a motor assembly configured to provide a driving force to the piston, the motor assembly including a magnet that is disposed radially outside the piston; and a supporter configured to be coupled to the piston, the magnet, and the resonance spring. The supporter includes: a piston coupler coupled with the piston; a magnet coupler coupled with the magnet; and a spring coupler coupled with the resonance spring. The piston coupler, the magnet coupler, and the spring coupler are integrally formed by aluminum die casting.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed and includes a hydraulic cylinder having a piston and a hydraulic fluid port, the piston being coupled to a rod for driving the reciprocating pump, the piston being moveable between first and second ends of the cylinder in response to a flow of hydraulic fluid through the hydraulic fluid port. A variable displacement hydraulic pump is responsive to a displacement control signal to draw hydraulic fluid from a reservoir and to produce a controlled flow of hydraulic fluid at the outlet. The apparatus also includes a valve connected between the hydraulic fluid port and the reservoir, the valve being responsive to a valve control signal for controlling discharge of hydraulic fluid from the hydraulic fluid port of the cylinder back to the reservoir to facilitate movement of the piston through a downstroke away from the second end toward the first end of the cylinder. The apparatus further includes a first sensor located proximate the first end of the cylinder and operable to produce a first signal indicating a proximity of the piston to the first sensor, a second sensor located proximate the second end of the cylinder and operable to produce a second signal indicating a proximity of the piston to the second sensor, and a controller operably configured to generate the displacement control signal and the valve control signal in response to receiving the first signal and the second signal.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed and includes a hydraulic cylinder having a piston and a hydraulic fluid port, the piston being coupled to a rod for driving the reciprocating pump, the piston being moveable between first and second ends of the cylinder in response to a flow of hydraulic fluid through the hydraulic fluid port. A variable displacement hydraulic pump is responsive to a displacement control signal to draw hydraulic fluid from a reservoir and to produce a controlled flow of hydraulic fluid at the outlet. The apparatus also includes a valve connected between the hydraulic fluid port and the reservoir, the valve being responsive to a valve control signal for controlling discharge of hydraulic fluid from the hydraulic fluid port of the cylinder back to the reservoir to facilitate movement of the piston through a downstroke away from the second end toward the first end of the cylinder. The apparatus further includes a first sensor located proximate the first end of the cylinder and operable to produce a first signal indicating a proximity of the piston to the first sensor, a second sensor located proximate the second end of the cylinder and operable to produce a second signal indicating a proximity of the piston to the second sensor, and a controller operably configured to generate the displacement control signal and the valve control signal in response to receiving the first signal and the second signal.

A metering mechanism includes a body mounted in a sleeve covering the top and an adjustment nut covering the bottom, the adjustment nut threaded to the sleeve, the screw connection then causing rotation of the adjustment nut with respect to the body of the metering mechanism, the body being extended by a valve seat that can be closed by a valve, able to receive a plunger of which the reciprocating motion permits intake at the valve, the travel of the plunger depending on the screw position between the adjustment nut and the sleeve. The metering mechanism further includes a rotation lock between the adjustment nut and the body of the metering mechanism to prevent the adjustment nut being screwed or unscrewed on the sleeve. Also disclosed is a method for locking and unlocking such a mechanism, and to a proportional metering pump incorporating such a mechanism.

A metering mechanism includes a body mounted in a sleeve covering the top and an adjustment nut covering the bottom, the adjustment nut threaded to the sleeve, the screw connection then causing rotation of the adjustment nut with respect to the body of the metering mechanism, the body being extended by a valve seat that can be closed by a valve, able to receive a plunger of which the reciprocating motion permits intake at the valve, the travel of the plunger depending on the screw position between the adjustment nut and the sleeve. The metering mechanism further includes a rotation lock between the adjustment nut and the body of the metering mechanism to prevent the adjustment nut being screwed or unscrewed on the sleeve. Also disclosed is a method for locking and unlocking such a mechanism, and to a proportional metering pump incorporating such a mechanism.

A proportional metering pump includes a hydraulic machine, a metering mechanism provided with a nozzle, and a unit for attaching the nozzle to the pipe for access to the cavity inside the hydraulic machine, including a securing ring mounted in rotation about one of the ends of the nozzle, a locking ring mounted so as to be able to translate along the longitudinal axis around the pipe for access to the mixing chamber and is pressed, in the direction of the metering mechanism, against a shoulder created on the access pipe by a spring, the securing ring and the pipe being able to engage following a screw connection at the end of which they are secured in rotation so as to prevent unscrewing of the securing ring. Also disclosed is a method for assembling and disassembling a metering mechanism on a hydraulic machine of such a pump.