A pump is provided having a communication portion that provides continuous communication between a pump section and a discharge section in a state where a discharge-side check valve suppresses a backflow, and a size of the communication portion is set so that, when the continuously expanding and contracting pump section contracts, a volume of gas mixed in liquid in the pump section is contracted.

A well pump has a standing valve seat with a standing valve mounted in a lower end of a barrel. A plunger is carried within the barrel for axial stoking movement. A travelling seat with a travelling valve are mounted in a lower end of the plunger. The travelling valve has a head that lands on the travelling valve seat while the travelling valve is in a closed position. The travelling valve has a stem extending downward from the head through a hole in the travelling seat. The stem is a permanent magnet. Another permanent magnet is carried by the barrel below the travelling magnet. The polarities of the magnets are configured to interact and cause the travelling valve to lift relative to the travelling seat to an open position as the plunger nears a bottom of a stroke.

A foam pump for generating a foam comprising a foamable liquid and air has dual, coaxial air and liquid cylinders, each having a respective air and liquid piston which move together during a dispensing operation. In certain embodiments, the air and liquid cylinders are modular, separately formed components. In certain embodiments, a plurality of differently sized, liquid cylinders are provided, each with a corresponding liquid piston which is complementary in size thereto. Providing multiple differently sized liquid cylinder and piston components allows the pump to be configured to deliver a desired quantity of foamable liquid and/or a desired liquid-to-air ratio in the foam output of the pump. The differently sized liquid cylinder and piston components can be used interchangeably with a common air cup design and other common pump components, the modular construction allowing custom pump output configurations to be provided with minimal tooling investment per output size.

An oil feeder and a linear compressor including the same are disclosed. The oil feeder includes an oil cylinder defining an oil supply hole configured to extend in a first direction, an accommodation groove formed concavely at a side, and a communication hole configured to communicate the oil supply hole with the accommodation groove, an oil piston accommodated in the accommodation groove and configured to reciprocate in a second direction perpendicular to the first direction, a first ball accommodated in the oil supply hole and disposed below the communication hole, a second ball accommodated in the oil supply hole and disposed on the communication hole, and an elastic member comprising an outer portion coupled to the accommodation groove and an inner portion coupled to the oil piston.

A valve for a reciprocating pump includes a housing, a first chamber, a second chamber, a first valve element, and a second valve element. The housing includes an inlet and an outlet. The first and second chambers are within the housing. The first chamber includes a first valve seat and is fluidly connected to the inlet. The second chamber includes a second valve seat and is fluidly connected to the outlet. The first valve element is disposed in the first chamber and includes a spring-loaded check valve element. The second valve element is disposed in the second chamber and includes a buoyant material.

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 check valve assembly includes a housing having a fluid inlet arranged to be fluidly connected, in use, to a source of hydraulic fluid, a first stage body having a first stage fluid outlet and a second stage body having a second stage fluid outlet and a flow passage between the first and second stage bodies. The first stage body is a hollow body having a first end in fluid communication with the fluid inlet and housing a hollow first stage retainer around which is mounted a first stage spring that biases a first stage ball. The second stage body is a hollow body housing a second stage retainer around which is mounted a second stage spring that biases a second stage ball, and wherein a first stage pressure differential between the first stage fluid outlet and the fluid inlet creates a fluid flow path from the inlet outlet.

A mounting structure for a diaphragm and a retainer includes: the diaphragm that is formed to have a disc shape and includes a fixation part positioned in an outer circumferential part of the diaphragm, a movable part positioned in a central part of the diaphragm, and a linking part linking the fixation part and the movable part together, wherein a side of the diaphragm facing a pump chamber is defined as a front side and a side of the diaphragm opposite from the pump chamber is defined as a rear side; and the retainer that has an annular shape, supports the rear side of the movable part of the diaphragm, and reciprocates, together with the movable part, in an advancement/retreat direction to and from the pump chamber. The diaphragm has a first R-shaped part recessed toward the pump chamber, on the rear side of a boundary section between the movable part and the linking part. The retainer includes an abutment part that abuts against the rear side of the diaphragm and a second R-shaped part that is formed in an outer circumferential position of the abutment part so as to protrude toward the pump chamber and that mates with the first R-shaped part.

A diaphragm pump can include an inlet, an outlet, and a pump chamber positioned in a fluid path between the inlet and outlet. The assembly can include a diaphragm and a movable piston. Movement of the piston toward the pump chamber can force a portion of the diaphragm to move from its rest position to a position further within the pump chamber and to increase pressure in the pump chamber. Movement of the piston away from the pump chamber can force a portion of the diaphragm to move from its rest position to a position away from the pump chamber and to reduce pressure in the pump chamber. The assembly can also include a first and second check valve. In the closed position, the second check valve can be unsealed to provide an escape path for gas. In the closed position, the first check valve can be sealed.

A vacuum pump includes a motor, a pump coupled to the motor to receive torque therefrom, and a trestle including an inlet port, an outlet port, and a fluid pathway therebetween, the outlet port being fluidly connected to the pump. The vacuum pump also includes a first valve positioned within the fluid pathway and adjustable between an open state, in which an airflow induced by the pump is drawn through the inlet port, and a closed state, in which a reverse airflow through the inlet port is prevented, and a second valve positioned within the fluid pathway in series with the first valve and adjustable between an open state, in which the airflow induced by the pump is drawn through the inlet port, and a closed state, in which the reverse airflow through the inlet port is prevented when the motor is deactivated.