A downhole-type device includes an electric machine. The electric machine includes an electrical rotor configured to couple with a device to drive or be driven by the electric machine. An electrical stator surrounds the electric rotor. The electric stator includes a seal configured to isolate stator windings from an outside, downhole environment. An inner surface of the seal and an outer surface of the electric rotor define an annulus exposed to the outside environment. A bearing couples the electric rotor to the electric stator. A lubrication system is fluidically coupled to the downhole-type device. The lubrication system includes a topside pressure pump and a downhole-type distribution manifold configured to be used within a wellbore. The distribution manifold is fluidically connected to the topside pressure pump and the bearing to receive a flow of lubricant from the topside pressure pump.

A rotor has at its two axis end portions an upper large-diameter inner circumferential portion and a lower large-diameter inner circumferential portion that have inner diameters larger than the inner diameter of the axially middle portion of the rotor and are offset in the radial direction. A crankshaft has a passageway, which is formed in the crankshaft and allows refrigerant to flow therethrough, and a gas venting hole, which provides communication between the passageway and at least one discharge opening formed in the outer circumferential surface of the crankshaft. The at least one discharge opening is formed at a position facing the inner circumferential surface of the lower large-diameter inner circumferential portion 5b on the compression unit side.

A vacuum device, in particular to a vacuum pump, includes a reservoir for an operating medium; an outlet connector arranged at or in the reservoir; and a selection device that selectively closes or opens the outlet connector or an outlet line, which is connected via the outlet connector to the reservoir, in dependence on whether the operating medium or water is present at the outlet connector.

A rotary internal combustion engine including a rotor assembly where at least a first and a second of the combustion chambers have unequal theoretical volumetric ratios. Also, a rotary internal combustion engine including first and second rotor assemblies where at least one of the combustion chambers of the first rotor assembly and at least one of the combustion chambers of the second rotor assembly have unequal effective volumetric compression ratios and/or unequal effective volumetric expansion ratios.

Provided is a linear compressor including a linear motor having a mover reciprocating with respect to a stator; a piston coupled to the mover to reciprocate; a cylinder into which the piston is slidingly inserted, the cylinder having an inner circumferential surface forming a bearing surface together with an external circumferential surface of the piston, the cylinder forming a compression space together with the piston, and the cylinder having at least one first hole formed through the inner circumferential surface of the cylinder and an outer circumferential surface of the cylinder to guide refrigerant discharged from the compression space to the bearing surface; and a porous member inserted into the outer circumferential surface of the cylinder and configured to cover the first hole, the porous member having multiple micropores smaller than the first hole.

Provided is a linear compressor including a linear motor having a mover reciprocating with respect to a stator; a piston coupled to the mover to reciprocate; a cylinder into which the piston is slidingly inserted, the cylinder having an inner circumferential surface forming a bearing surface together with an external circumferential surface of the piston, the cylinder forming a compression space together with the piston, and the cylinder having at least one first hole formed through the inner circumferential surface of the cylinder and an outer circumferential surface of the cylinder to guide refrigerant discharged from the compression space to the bearing surface; and a porous member inserted into the outer circumferential surface of the cylinder and configured to cover the first hole, the porous member having multiple micropores smaller than the first hole.

Disclosed herein is a linear compressor. The linear compressor includes a piston, a cylinder, a frame, a first bearing gap formed between an inner circumferential surface of the frame and the outer circumferential surface of the cylinder, a second bearing gap formed between an inner circumferential surface of the cylinder and the outer circumferential surface of the piston, a bearing inflow passage and a bearing side passage formed in the cylinder such that fluid flows from the first bearing gap to the second bearing gap.

Disclosed herein is a linear compressor. The linear compressor includes a piston, a cylinder, a frame, a first bearing gap formed between an inner circumferential surface of the frame and the outer circumferential surface of the cylinder, a second bearing gap formed between an inner circumferential surface of the cylinder and the outer circumferential surface of the piston, a bearing inflow passage and a bearing side passage formed in the cylinder such that fluid flows from the first bearing gap to the second bearing gap.

A preheater for a compressor that is capable of heating a lubricant oil efficiently with smaller power is provided. A preheater for a compressor includes: a capacitive oil surface sensor that is provided at a compressor used in a refrigerating cycle, and detects an oil surface of a lubricant oil A in the compressor; and a power supply unit that applies high-frequency voltage to the oil surface sensor.

A hermetic compressor accommodates in hermetic container (101) electric motor element (102) and compression element (103) driven by electric motor element (102). Compression element (103) includes crankshaft (110) including main shaft (115), eccentric shaft (114), and flange (116), cylinder block (111) having cylinder bore (123) passing through cylinder block (111) in a cylindrical shape, and piston (112) configured to reciprocate in cylinder bore (123). Compression element (103) also includes connecting rod (113) connecting piston (112) and eccentric shaft (114) and bearing (124) formed on cylinder block (111) for pivotally supporting a radial load that acts on main shaft (115) of crankshaft (110). Crankshaft (110) further includes communicating oil supply passage (118) provided in flange (116), main shaft oil supply passage (119) configured for communication between communicating oil supply passage (118) and cylindrical surface (115a) of main shaft (115), and eccentric shaft oil supply passage (120) configured for communication between communicating oil supply passage (118) and cylindrical surface (114a) of eccentric shaft (114).