A direct drive air pump has a motor and a pumping mechanism connected to an end of the motor, and further has an auxiliary pumping mechanism connected to the other end of the motor, and a tube connected with the pumping mechanism and the auxiliary pumping mechanism. In each one of the pumping mechanism and the auxiliary pumping mechanism, a cylindrical body has a top plate having an exhaust hole. A single O-ring is used to seal between the cylindrical body and a cylindrical cover for reducing the sealing portions. A valve block of a non-return valve can co-work with a spring for opening and closing the exhaust hole. The valve block is soft for closing the exhaust hole well and reducing the noise of collision between the valve block and the top plate.

A linear compressor is provided. The linear compressor may include a suction valve with a plurality of wings. Each of the plurality of wings may include two first edge portions that extend in an outer direction of a fixing portion, and a second edge portion forming an outer circumferential portion of the wing. A distance between a first edge portion of a first wing among the plurality of wings and a second edge portion of a second wing among the plurality of wings gradually increases toward the outer direction of the suction valve.

A linear compressor and a method for manufacturing a linear compressor are provided. A piston of a linear compressor may include a surface treatment body made of aluminum or an aluminum alloy; a first surface treatment provided on an outer surface of the surface treatment body by a first vacuum deposition process; and a second surface treatment provided on an outer surface of the first surface treatment by a second vacuum deposition process.

A linear compressor is provided that may include a casing, a frame accommodated in the casing, a cylinder that passes through a center of the frame, supported by the frame, and defining a compression space for a refrigerant, a piston inserted into the cylinder to reciprocate in an axial direction of the cylinder and having a first end that compresses the refrigerant supplied to the compression space, a suction muffler which is coupled to a second end of the piston and through which the refrigerant supplied to the compression space may flow, a spring that allows a resonant motion of the piston, a back cover including a cover body that defines a refrigerant opening at a central portion, such that a refrigerant passes therethrough, the back cover supporting the spring, and an inflow guide which is fixed to the cover body and guides the refrigerant passing through the refrigerant opening towards an inside of the suction muffler. At least a portion of the inflow guide may be inserted into the suction muffler, and a central axis thereof may be aligned with a central axis of the refrigerant opening.

An easy-to-assemble air pump includes a cylinder, a piston member, a valve seat, and a valve connector. The piston member includes a piston portion and a rod portion integrally formed as a monolithic member. The piston portion is axially movably arranged into the cylinder, and the rod portion is movably coupled to the cylinder for movement with respect thereto. The valve seat is arranged in the cylinder. The valve connector is connected to one end of the cylinder. Thus, the assembly process of the air pump can be simplified and the assembly time can be shortened.

A linear compressor includes: a shell including an intake pipe configured to suction a refrigerant, a piston including a piston body, an intake muffler including a first muffler that includes a first muffler body defining a main flow passage and a first muffler flange extending in a radial direction from the first muffler body, and at least one auxiliary flow passage disposed between an outer peripheral surface of the first muffler body and an inner peripheral surface of the piston body and configured to guide the refrigerant remaining between the first muffler body and the piston body to an outside of the piston. A cross-sectional area of the at least one auxiliary flow passage is less than a cross-sectional area of an inlet hole provided at a rear end of the main flow passage and greater than or equal to 10% of the cross-sectional area of the inlet hole.

A reciprocating compressor 1A includes a compression part 2 compressing, by a piston 6, gas sucked into a cylinder 4 through a suction valve 36, and discharging the compressed gas through a discharge valve 51, a piston drive part 3 supplying a force to the piston 6 to reciprocate the piston 6 via a piston rod 9 coupled to the piston 6, and a housing 17 accommodating the compression part 2 and forming a vacuum region around the compression part 2.

A linear compressor includes a cylinder, a piston, and a discharge valve, wherein the piston includes a first part extending in the axial direction, a second part having a diameter greater than that of the first part and formed at one end of the first part facing the discharge valve, and a third part having a diameter greater than that of the first part and formed at the other end of the first part. The second part includes a first outer circumferential surface extending backward from a front surface of the piston, and a second outer circumferential surface spaced apart from the first outer circumferential surface in a direction away from the discharge valve, and a distance between the first outer circumferential surface and an inner circumferential surface of the cylinder is less than a distance between the second outer circumferential surface and the inner circumferential surface of the cylinder.

A piston for a compressor and a compressor including the same are disclosed. The piston is used in a compressor which compresses and discharges refrigerant suctioned into a cylinder. The piston includes a cylindrical slider and a head. The slider has an outer diameter corresponding to an inner diameter of the cylinder and defines a suction space in which the refrigerant suctioned in the cylinder is received. The head is coupled to the slider, in which a compression space is provided in the front and a suction space is provided in the rear, and in which a suction port communicating with the suction space and the compression space is formed, in which the head includes an inner body and an outer body surrounding the inner body, and the suction port is formed between the inner body and the outer body.

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.