A linear compressor and a method for controlling a compressor are provided. The compressor may include a piston that reciprocates within a cylinder, a linear motor that supplies a driving force to the piston, a discharge device through which a refrigerant compressed in the cylinder by the reciprocating motion of the piston is discharged, a pressure changing device that changes a variation rate of pressure applied to the piston before the piston reaches a virtual discharge surface (VDS) during the reciprocating motion, to prevent collision between the piston and the discharge device. The virtual discharge surface may be formed on at least a portion of the discharge device facing a compression space within the cylinder.

A pumping assembly is provided which is suitable for use in a variety of dosing pumps. The pumping assembly comprises a pump body with a pump bore, and a sleeve fixed within the pump bore. The sleeve has a first end, a second end and a sleeve bore. A plunger is adapted to enter the first end of the sleeve and to reciprocate within the sleeve bore. The sleeve has at least one port to allow fluid flow through a wall of the sleeve. The, or each, port is elongated in a direction substantially orthogonal to a direction of reciprocation.

The present invention provides a reciprocating compressor that compresses a gas, including: a piston; a cylinder that includes a hole portion into which the piston is inserted so as to be movable in the axial direction in a reciprocating manner and includes a compression chamber which is formed in an area of the hole portion near a front end of the piston so that a gas is introduced into the compression chamber; a crank mechanism that drives the piston so that the gas introduced into the compression chamber is compressed by the piston; and a piston ring that is fitted to the outside of the piston and slides on an inner surface forming the hole portion of the cylinder, wherein a tapered portion is formed in an end, which is located near a base end of the piston, in the inner surface forming the hole portion of the cylinder.

A flow restrictor (1) for application in bearing formation between a piston (2) and a cylinder (3) of a gas compressor (4). The gas compressor (4) includes a pad (5) externally surrounding the cylinder (3) and an inner cavity (6), arranged between the pad (5) and the cylinder (3), fluidly fed by a discharge flow arising from a compression movement exerted by the piston (2) within the cylinder (3). The gas compressor (4) includes a bearing formation gap (7) separating a piston outer wall (2) and an inner cylinder wall (3), and a flow restrictor (1) is provided with a housing (12) fluidly associating the inner cavity (6) to the bearing formation gap (7). The flow restrictor (1) includes a porous element (8), associated to the housing (12), provided with at least a restrictor part provided with a porosity sized to limit the gas flow flowing from the inner cavity (6) to the bearing formation gap (7).

A compressor crankcase assembly is provided for an air compressor. In one example, a compressor crankcase assembly includes a crankcase made of a material comprising at least 50% by weight aluminum and a crankcase liner disposed within the crankcase. The crankcase has a protrusion that is at least partially disposed within the groove of the crankcase liner.

A linear compressor includes: a piston configured to reciprocate in an axial direction, and a cylinder that is provided on a radially outer side of the piston to accommodate the piston and that defines a compression space with the piston. The cylinder includes: a gas hole defined at the cylinder such that a first end of the gas hole is at an outer circumferential surface of the cylinder and a second end of the gas hole is at an inner circumferential surface of the cylinder, and a gas pocket that is in communication with the gas hole and that is recessed from the inner circumferential surface of the cylinder, where a length of the gas pocket in the axial direction of the cylinder is longer than a length of the gas pocket in a circumferential direction of the cylinder.

A reciprocating compressor with a head-holding turret in the upper portion of which one or more recesses, open to the outside, are defined, which reduce as much as possible the contact surface with the valve carrier plate above.

A machine having one or more cylinders, each cylinder having an inner surface configured to engage a circumferential surface of a piston ring of a piston thereby defining a contact zone between the inner surface of the cylinder and the circumferential surface of the piston ring, the inner surface having at least one recess indented into the inner surface, wherein the ratio of the dimension of the recess in the direction of travel of the piston to the dimension of the contact zone in the direction of travel of the piston is in the range of approximately 1:5 to 3:5.

A cylinder liner for providing reduced oil carry-over in an air-assisted fuel injection system comprising an air compression piston wherein the cylinder liner and air compression system together in part define an air compression chamber, the cylinder liner comprising: an outer surface; and a plurality of projections on the outer surface; wherein the plurality of projections are arranged such that oil-laden air drawn up from an oil reservoir around the outer surface of the cylinder liner is forced into a labyrinthine path to increase the time the oil-laden air is in contact with the outer surface and increase the amount of oil adhering to the outer surface to minimize the amount of oil carry-over entering the air compression chamber.

A gas bearing is disclosed. The gas bearing may include a cylinder with an inner cylinder radius. The gas bearing may include a piston with a piston radius, wherein the inner cylinder radius is larger than the piston radius, wherein the piston is located within the cylinder. The gas bearing may include a gas bearing radius, wherein the gas bearing radius is greater than the piston radius and less than the inner cylinder radius. The gas bearing may include a gap that exists between the cylinder and the piston, wherein the gap contains a pressurized gas, the pressurized gas configured to prevent contact between the cylinder and the piston. The gas bearing may include a gas bearing interface, wherein the gas bearing interface is positioned to control a size of the gap.