A linear compressor includes: a frame comprising a body portion, a flange portion extending from a front side of the body portion along a radial direction of the body portion, and a bearing communication hole that is in fluid communication with a front surface of the flange portion and an inner circumferential surface of the body portion, a cylinder coupled to the body portion, a piston that is disposed in the cylinder and that is configured to reciprocate along an axial direction of the cylinder, and a valve member that is disposed at the frame and that is configured to open and close the bearing communication hole based on a pressure of air between the cylinder and the piston.

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.

An axial piston machine is capable of suppressing a sudden change in hydraulic pressure in a piston oil chamber upon start and stop to enable the axial piston machine to start and stop smoothly. The axial piston machine includes: a cylinder block including a rotation axis and a plurality of piston oil chambers disposed around the rotation axis; pistons housed in the plurality of piston oil chambers, respectively; and orifices formed in the cylinder block that allow fluid communication between each of the piston oil chambers and an outside of the cylinder block. The orifices are positioned to be opened when the movable swash plate is in the neutral position and to be closed when the movable swash plate is in the operating position. The orifices are closed by outer peripheral surfaces of the pistons when the pistons approach a top dead center position.

A piston assembly for a piston pump includes an actuator rod, a piston coupled to the actuator rod and configured to contact a radially-inner wall of a cylinder, and a piston support structure coupled to the actuator rod and configured to contact the radially-inner wall of the cylinder. A fluid channel extends through the actuator rod and the piston support structure, and the fluid channel is configured to deliver a lubricating fluid to an annular space positioned between the piston and the piston support structure along an axial axis of the piston assembly.

A linear compressor includes a compressor body configured to compress a refrigerant. The compressor body includes a cylinder, a discharge valve, a groove, a gas hole, and a flow restrictor. The cylinder receives a piston. The discharge valve is configured to open and close one side of the cylinder and define a compression space for the refrigerant together with the piston. The groove is defined in an outer circumferential surface of the cylinder and into which at least a portion of the refrigerant discharged through the discharge valve is introduced. The gas hole is defined in the groove to pass through the cylinder. The flow restrictor includes twisting wires made of different materials and is disposed to be wound around the groove.

A linear compressor includes a cylinder that defines a compression space of a refrigerant and has a cylindrical shape, and a piston disposed in the cylinder and reciprocating along an axis of the cylinder. The cylinder includes a gas inlet on an outer circumferential surface and a supply port radially passing through the cylinder and communicating with the gas inlet. The gas inlet includes a first gas inlet and a second gas inlet disposed behind the first gas inlet, and the supply port includes a first supply port communicating with the first gas inlet and a second supply port disposed behind the first supply port and communicating with the second gas inlet. A flow rate passing through the first supply port is different from a flow rate passing through the second supply port.

A linear compressor is provided. The linear compressor may include a cylinder that defines a compression space for a refrigerant; a piston that axially reciprocates inside the cylinder; a motor configured to provide a drive force to the piston; a discharge valve configured to discharge the refrigerant compressed in the compression space; and a discharge cover having a discharge space in which the refrigerant discharged through the discharge valve flows. The discharge valve and the discharge cover may be arranged inside the motor.

A linear compressor according to the present disclosure may include a cylinder provided with at least one groove, a piston reciprocating within the cylinder, a motor configured to provide a driving force to move the piston within the cylinder, an inverter configured to perform a switching operation to transmit electric power to the motor, and a controller configured to receive temperature information from the electronic device and control the inverter to preheat the motor based on the received temperature information.

A linear compressor includes a cylinder that defines a compression space of a refrigerant and has a cylindrical shape, and a piston disposed in the cylinder and reciprocating along an axis of the cylinder. The cylinder includes a gas inlet formed on an outer circumferential surface of the cylinder, a supply port radially passing through the cylinder and communicating with the gas inlet, and a recess communicating with the supply port and formed on an inner circumferential surface of the cylinder. An angle formed by an axial cross section of the recess and a straight line extending the supply port and an angle formed by the axial cross section of the recess and a straight line extending the inner circumferential surface of the cylinder each are an acute angle.

A linear compressor includes a cylinder that defines a compression space of a refrigerant and has a cylindrical shape, and a piston disposed in the cylinder and reciprocating along an axis of the cylinder. The cylinder includes a supply port radially passing through the cylinder, and a recess formed on an inner circumferential surface of the cylinder and communicating with the supply port. The supply port includes a first supply port and a second supply port disposed in a rear of the first supply port, and the recess includes a first recess and a second recess disposed in a rear of the first recess. The first recess and the second recess are formed in different shapes.