A refrigeration system with at least three compressors connected in a circuit. Each compressor has a housing with an oil sump. The oil sump is adapted to contain oil that defines an oil level. A supply line supplies refrigerant and entrained oil to each of the at least three compressors. The oil sump of each compressor has at least one oil port. Each oil port is disposed at an elevation that is equal to or minimally higher than the level of oil to promote equalization of oil levels in each compressor. There are a plurality of separate conduits which are not directly connected, but connected through the oil sumps of separate compressors. At least one compressor includes an oil sump extension having connections for the separate conduits. Each oil port is connected to the separate conduits or an oil sump extension. Each separate conduit connects a pair of compressors.

A liquid-feed-type gas compressor that can monitor the liquid surface height in a gas-liquid separator is provided. An oil-feed-type air compressor includes: an oil separator that separates oil from compressed air discharged from a compressor main body 1 and stores the oil therein; a sampling line whose inlet side is connected to a predetermined height position of the oil separator and that allows fluid from the predetermined height position of the oil separator to flow by the pressure difference between the inlet side and the outlet side; a pressure sensor that detects the pressure of the fluid that flows or has flown in the sampling line; a controller that determines which of air and oil the fluid that flows in the sampling line is by carrying out determination of whether the pressure detected by the pressure sensor exceeds a set value P1 in some cases and determination of whether the pressure falls below a set value P2 in some cases; and an informing device that informs a determination result of the controller.

Size reduction of a compressor and cooling of an electric motor are effectively achieved. An oilless compressor, having: a compressor main body that has a rotor for compressing air, a rotor shaft for supporting the rotor, and a bearing for rotatably supporting the rotor shaft; an electric motor for producing drive force for driving the compressor main body; at least one gear for transmitting drive force to the rotor shaft; a lubricating oil pipe for conveying lubricating oil to the bearing and/or the gear; and an oil pump for pressure-feeding the lubricating oil; wherein the electric motor has, in the external peripheral direction of an armature, a cooling jacket for channeling the lubricating oil to an internal flow channel to cool the armature of the electric motor, and the lubricating oil circulates through the cooling jacket and the lubricating oil pipe.

A method of operating a refrigeration system having at least three compressors, in which each compressor has an oil sump with oil at an oil level. The method includes separately connecting the oil sumps of the at least three compressors. Each separate connection allows oil flow only between the oil sumps of two of said compressors thereby preventing bypass flow. The method further includes flowing oil between oil sumps of the at least three compressors and along the separate connections to tend to equalize the oil levels among the oil sumps of the at least three compressors.

A compressor may include a shell, a first compression mechanism, and a second compression mechanism. The shell may define a first chamber containing fluid at a first fluid-pressure. The first compression mechanism may be disposed within the first chamber and may include a first orbiting scroll and a first non-orbiting scroll. The first compression mechanism discharging compressed fluid into the first chamber at the first fluid-pressure. The second compression mechanism may be disposed in the first chamber and may include a second orbiting scroll and a second non-orbiting scroll. The second compression mechanism may define a suction inlet and a discharge outlet. The suction inlet may receive fluid at the first fluid-pressure from the first chamber such that the fluid at the first fluid pressure flows from the first compression mechanism to the suction inlet without exiting the shell. The discharge outlet may discharge fluid at a second fluid-pressure out of the shell.

A technique that allows a plurality of series-connected compressors in a refrigerant circuit to have equal amounts of oil in a more versatile manner is provided. A compression apparatus according to an embodiment in the disclosure includes series-connected compressors 10, 20 in a refrigerant circuit 1 that is to circulate a refrigerant; an oil separator 30 is provided in a discharge passage 50 of the compressor 10 of the compressors 10, 20, and separates oil from the refrigerant discharged from the compressor 10 and causes the refrigerant separated from the oil to flow downstream (intake passage 80); an oil return passage 70 returns the oil separated by the oil separator 30 to the compressor 10 neighboring upstream; an oil discharge outlet 10A is provided in the compressor 10; and an oil discharge passage 60 connects the oil discharge outlet 10A to an inlet of the oil separator 30.

A compressor system includes: a compressor having a suction side and a discharge side, wherein the compressor is operative to compress a gas using oil, wherein the suction side operates at a suction pressure and is operative to receive a the gas and the oil into the compressor; and wherein the discharge side is operative to discharge the compressed gas and the oil; a gas/oil separator tank operative to store oil separated from the compressed gas for subsequent use by the compressor; a supplemental oil reservoir in fluid communication with the suction side; and a valve operative to, when opened, expose the supplemental oil reservoir to the suction pressure of the suction side of the compressor, and draw oil from the supplemental oil reservoir by suction into the suction side of the compressor.

A refrigeration system with at least three compressors connected in a circuit. Each compressor has a housing with an oil sump. The oil sump is adapted to contain oil that defines an oil level. A supply line supplies refrigerant and entrained oil to each of the at least three compressors. The oil sump of each compressor has at least one oil port. Each oil port is disposed at an elevation that is equal to or minimally higher than the level of oil to promote equalization of oil levels in each compressor. There are a plurality of separate conduits which are not directly connected, but connected through the oil sumps of separate compressors. At least one compressor includes an oil sump extension having connections for the separate conduits. Each oil port is connected to the separate conduits or an oil sump extension. Each separate conduit connects a pair of compressors.

A screw compressor for a utility vehicle has a housing, wherein, in the operationally ready and assembled state of the screw compressor, an oil sump is provided in the housing. A magnet is arranged in the oil sump.

Provided is an oil feed type air compressor which can increase the determination accuracy regarding a deterioration state of oil. An oil feed type air compressor 1 includes a compressor main body 3, a separator 6 that separates oil from compressed air discharged from the compressor main body 3, and an oil feeding system 8 that feeds the oil separated by the separator 6 into a compression chamber of the compressor main body 3. The oil feeding system 8 includes a temperature control valve 20 that adjusts a diversion ratio for an oil cooler 18 and a diversion ratio for a bypass pipe 19 according to a temperature of the oil. The oil feed type air compressor 1 includes pressure sensors 22A and 22B located in the oil feeding system 8, a discharge temperature sensor 11 located on the discharge side of the compressor main body 3, and a controller 9 that computes, when it is estimated that the diversion ratio for the oil cooler 18 is 100% from the temperature sensed by the discharge temperature sensor 11 exceeding a predetermined value Td1, a difference ?P between the pressure sensed by the pressure sensor 22A and the pressure sensed by the pressure sensor 22B and determines a deterioration state of the oil in reference to the difference ?P.