A multi-stage electric gas pump includes a driving mechanism and an eccentric shaft including a main body having a longitudinal axis, a first eccentric portion, and a second eccentric portion, wherein the first eccentric portion and the second eccentric portion are fixed on the main body. The eccentric shaft is driven by the driving mechanism to produce a first circular movement of the first eccentric portion around the longitudinal axis and a second circular movement of the second eccentric portion around the longitudinal axis, wherein the second circular movement is synchronized with the first circular movement. The multi-stage electric gas pump further includes a first cylinder, a second cylinder, and a third cylinder. The cylinders in three stages are driven by the eccentric shaft so as to achieve three-stage pressurization of gas.

A piston ring includes a first ring portion which is fitted onto an outer circumferential portion of a piston and which is capable of sliding relative to an inner wall surface of a cylinder, and a second ring portion which is fitted onto the outer circumferential portion of the piston, arranged side-by-side with the first ring portion in the axial direction, and which is capable of sliding relative to the inner wall surface of the cylinder. The second ring portion is fitted onto the outer circumferential portion of the piston in such a way as to be positioned on a side opposite to a compression chamber inside the cylinder, relative to the first ring portion, and has a greater hardness than the first ring portion has.

The disclosure relates to a three-stage reciprocating compressor comprising pistons and suction and compression chambers in which a medium is compressed for each separate stage, which stages are connected in series and where a first stage is fluidly connected to an inlet for inlet of uncompressed or pre-compressed gas where the three-stage pistons move synchronously along a common axis in one connected unit such that the first and second stage suction and compression chambers share piston as well as cylinder wall, and having separate cylinder heads, a top headpiece and a bottom headpiece on each side of the piston, the third stage piston extending from a center of the first and second stage common piston and is passed through an opening in the cylinder head of the first stage suction and compression chamber, in extension of which is placed a third stage cylinder tube with a smaller diameter than a diameter of the cylinder for stage one and two, each stage fluidly separated by one or more one way valves, where the second stage suction and compression chamber is formed between the cylinder wall and a piston skirt as well as between an underside of the piston and the headpiece placed in a bottom of the cylinder.

Various embodiments of the present disclosure are directed to packing rings. In one example embodiment, a packing ring is disclosed including first and second axial ring ends, at least three ring segments, and at least three relief openings. The at least three relief openings each have a first relief opening end opening into the radially inside inner circumferential surface of the ring segment. The first relief opening ends of two relief openings arranged adjacent to one another in the circumferential direction are spaced apart from one another at a relief opening circumferential distance. The first relief opening ends are closer in the axial direction to the first axial ring end than to the second axial ring end and are spaced apart at a relief opening axial distance from the first axial ring end, which is 4% to 20% of the axial ring width of the ring segment.

A double-acting reciprocating pump comprises a piston assembly comprising at least one piston disposed within at least one piston cylinder for undergoing opposite reciprocal movements within said at least one piston cylinder, an upper pump chamber disposed above the piston, and a lower pump chamber disposed below the piston. A fluid inlet is fluidically connected to one of the upper and lower pump chambers so as to supply fluid thereto, and a fluid outlet dispensing port is defined within a lower end portion of the double-acting reciprocating pump assembly for permitting fluid to be dispensed out from the double-acting reciprocating pump assembly during both of the opposite reciprocal movements.

A double-acting reciprocating pump comprises a piston assembly comprising at least one piston disposed within at least one piston cylinder for undergoing opposite reciprocal movements within said at least one piston cylinder, an upper pump chamber disposed above the piston, and a lower pump chamber disposed below the piston. A fluid inlet is fluidically connected to one of the upper and lower pump chambers so as to supply fluid thereto, and a fluid outlet dispensing port is defined within a lower end portion of the double-acting reciprocating pump assembly for permitting fluid to be dispensed out from the double-acting reciprocating pump assembly during both of the opposite reciprocal movements.

A tangentially cut rod packing ring is provided. The tangentially cut rod packing ring comprises a first ring formed from a plurality of segments. Each of the segments has a portion of two interfaces where each interface slidably engages an interface of an adjacent segment. One interface terminates at a leading surface. One interface has a stop surface. The leading surface is originally separated from the stop surface by a gap. As the interfaces slidably move, the gap lessens until the leading surface abuts the stop surface. The tangentially cut rod packing ring also comprises a second ring formed from a plurality of segments. The second ring has a first portion and a second portion. The first portion forms as shelf on which the first ring sits. The second portion surrounds the first ring. An elastic member in a groove on the outer surface of the second portion provides a compressive force on both the second ring and the first ring.

A vacuum pump is provided that includes a body, a first cylinder at least partially inside the body, a second cylinder at least partially inside the body, and an electric drive motor attached to the body and driving a common crank pin. The first cylinder has a first cylinder axis, and a first piston is reciprocal in the first cylinder. A first piston rod is attached to the first piston. The second cylinder has a second cylinder axis, and a second piston is reciprocal in the second cylinder. A second piston rod is attached to the second piston. The first and second cylinder axes are arranged at substantially 90° to each other. The first and second piston rods engage the common crank pin such that the first piston and the second piston are commonly driven by the common crank pin.

A tangentially cut rod packing ring is provided. The tangentially cut rod packing ring comprises a first ring formed from a plurality of segments. Each of the segments has a portion of two interfaces where each interface slidably engages an interface of an adjacent segment. One interface terminates at a leading surface. One interface has a stop surface. The leading surface is originally separated from the stop surface by a gap. As the interfaces slidably move, the gap lessens until the leading surface abuts the stop surface. The tangentially cut rod packing ring also comprises a second ring formed from a plurality of segments. The second ring has a first portion and a second portion. The first portion forms as shelf on which the first ring sits. The second portion surrounds the first ring. An elastic member in a groove on the outer surface of the second portion provides a compressive force on both the second ring and the first ring.

A linear compressor is provided. The linear compressor includes a cylinder, a piston configured to reciprocate inside the cylinder, the piston including a head portion and a sliding portion extending rearward from a radially outer edge of the head portion, a supporter including a plate disposed at a rear of the piston, an elastic body disposed in the piston, the elastic body including an outer side coupled to an inner circumferential surface of the piston, and a rod configured to extend axially, the rod including one side coupled to a radially central area of the elastic body and other side connected to a radially central area of the plate.