An example pressure-driven metered mixing dispensing pump includes a housing, a fluid inlet, a piston disposed in the housing at least partially defining first, second and third chambers, the first and second chambers each in fluid communication with the third chamber, the piston to, in response to first fluid entering the first chamber via the fluid inlet, move in a first direction to decrease the volume of the second chamber thereby ejecting second fluid from the second chamber into the third chamber, a spring to move the piston in a second direction to decrease the volume of the first chamber thereby ejecting at least some of the first fluid from the first chamber into the third chamber thereby mixing the at least some of the first fluid and the second fluid to form a mixture, and an outlet to discharge the mixture from the third chamber.

An example pressure-driven metered mixing dispensing pump includes a housing, a fluid inlet, a piston disposed in the housing at least partially defining first, second and third chambers, the first and second chambers each in fluid communication with the third chamber, the piston to, in response to first fluid entering the first chamber via the fluid inlet, move in a first direction to decrease the volume of the second chamber thereby ejecting second fluid from the second chamber into the third chamber, a spring to move the piston in a second direction to decrease the volume of the first chamber thereby ejecting at least some of the first fluid from the first chamber into the third chamber thereby mixing the at least some of the first fluid and the second fluid to form a mixture, and an outlet to discharge the mixture from the third chamber.

Techniques and mechanisms for changing a flexibility of a sheet structure. In an embodiment, a garment or other device includes sheet structure, where an interface region is disposed between overlapping layer portions of a sheet structure. While a pressure differential is maintained between the interface region and a chamber of the garment, a valve of the garment is opened to allow an exchange of fluid between the interface region and the chamber. In another embodiment, the exchange of fluid changes a flexibility of the sheet structure by initiating or alleviating friction jamming between the overlapping layer portions.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed. The apparatus 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. The apparatus also includes a variable displacement hydraulic pump coupled to receive a substantially constant rotational drive from a prime mover for operating the hydraulic pump, the hydraulic pump having an outlet and being 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 hydraulic fluid line connected to deliver hydraulic fluid from the outlet of the hydraulic pump through the hydraulic fluid port to the cylinder for causing the piston to move through an upstroke away from the first end and toward the second end of the cylinder. The apparatus further 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 valve is operable to prevent flow of hydraulic fluid through the valve during the upstroke and the hydraulic pump is operable to prevent flow of hydraulic fluid back into the outlet of the hydraulic pump during the downstroke.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed. The apparatus 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. The apparatus also includes a variable displacement hydraulic pump coupled to receive a substantially constant rotational drive from a prime mover for operating the hydraulic pump, the hydraulic pump having an outlet and being 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 hydraulic fluid line connected to deliver hydraulic fluid from the outlet of the hydraulic pump through the hydraulic fluid port to the cylinder for causing the piston to move through an upstroke away from the first end and toward the second end of the cylinder. The apparatus further 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 valve is operable to prevent flow of hydraulic fluid through the valve during the upstroke and the hydraulic pump is operable to prevent flow of hydraulic fluid back into the outlet of the hydraulic pump during the downstroke.

A device that compensates for abrupt variations in fluid flow rate for a pump line is described. One or more aspects pertain to a system to accomplish automated in-situ placement of a concrete wall or embankment, where a fluid concrete is pumped into place, consolidated, and screeded to a finished surface, with remotely controlled or automated equipment.

A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

A linear compressor includes one spring assembly including a plurality of spring parts fixed to both side surfaces of a supporter and a rear cover and configured to support a load generated in the compressor. In addition, both side portions of the spring part are provided with fixing brackets coupled to the supporter and the rear cover, and the fixing bracket is provided with an insertion member or a bracket coupling member so that the coupling force of the spring part can be increased.

A linear compressor includes one spring assembly including a plurality of spring parts fixed to both side surfaces of a supporter and a rear cover and configured to support a load generated in the compressor. In addition, both side portions of the spring part are provided with fixing brackets coupled to the supporter and the rear cover, and the fixing bracket is provided with an insertion member or a bracket coupling member so that the coupling force of the spring part can be increased.