A liquid-injected compressor or vacuum pump device with a liquid-injected compressor or vacuum pump element (2), which includes a liquid return system (7), a motor (4) to drive the compressor or vacuum pumping element (2), a gearbox (3) provided between the motor (4) and the liquid-injected compressor or vacuum pump element (2), and a liquid separator vessel (5) in fluid connection with an outlet (6) of the compressor or vacuum pump element (2). The liquid return system (7) includes a main body (8) with a chamber in which a first compressed gas flow (11) from the liquid separator vessel (5) and a second fluid flow (15) from the gearbox (3) are mixed together to form a third fluid flow (20). The third fluid flow (20) leaves the chamber via an outlet (16) and is directed into the liquid-injected compressor or vacuum pump element (2) via the injection point (17).

A screw compressor includes a screw rotor, a casing, and a fluid supply portion to supply fluid in a membrane form into a compression chamber in the casing. The screw rotor has a male and female rotors. A male bore covering the male rotor and a female bore covering the female rotor are formed on the inner surface of the casing. An intersection line, on a higher pressure side, of the male and female bores is defined as a compression cusp. In a bore development view, a trajectory made by the first intersection of an extension line of a female lobe ridge and a male lobe ridge being moved, along with the rotation of the male and female rotors, is defined as a trajectory line. An opening of the fluid supply section to the compression chamber is positioned between the compression cusp and the trajectory line.

An oil-injected multi-stage compressor system that comprises at least a low-pressure stage compressor element (2) with an inlet (4a) and an outlet (5a) and a high-pressure stage compressor element (3) with an inlet (4b) and an outlet (5b), whereby the outlet (5a) of the low-pressure stage compressor element (2) is connected to the inlet (4b) of the high-pressure stage compressor element (3) through a pipeline (6), characterized in that the compressor elements (2, 3) are provided with their own drive in the form of an electric motor (2a, 3a), whereby the compressor elements (2, 3) are connected to the electric motor (2a, 3a) either directly or through a gearbox and that an intercooler (9) is provided in the aforementioned pipeline (6) between the low-pressure stage compressor element (2) and the high-pressure stage compressor element (3).

An oil-free water-injected screw air compressor comprises a housing that encloses two rotors for generating compressed air, an air water separator for separating the water from the compressed air. Injecting water during compression can remove the heat of compression and thus enhance efficiency of compression. However, injecting water may complicate bearing lubrication. According to the present subject matter, these challenges are tackled using a sealing system for isolation of bearing lubricant from water used for cooling.

A compressor is disclosed which can include a first stage and a second stage. In one form the compressor includes contact cooled compressor stages. The compressor can include a rod useful to inject a lubricant for purposes of cooling/lubricating/sealing the rotating components of the compressor. In one form the rod is an elongate rod with openings which permit a lubricant such as oil to be injected. The injected oil can be atomized via the openings. The rod can be positioned in the interstage space between the first and second stages, and can include a variety of openings.

A compressor is disclosed which can include a first stage and a second stage. In one form the compressor includes contact cooled compressor stages. The compressor can include a rod useful to inject a lubricant for purposes of cooling/lubricating/sealing the rotating components of the compressor. In one form the rod is an elongate rod with openings which permit a lubricant such as oil to be injected. The injected oil can be atomized via the openings. The rod can be positioned in the interstage space between the first and second stages, and can include a variety of openings.

A compressor includes a shell, first and second scroll members, a fitting assembly and a valve assembly. The first scroll member includes a first end plate having a first spiral wrap extending therefrom. The second scroll member includes a second end plate having a second spiral wrap extending therefrom and an injection passage formed in the second end plate. The second spiral wrap is meshingly engaged with the first spiral wrap to form compression pockets. The injection passage is in fluid communication with the compression pockets. The fitting assembly is in fluid communication with the injection passage. The valve assembly coupled to one of the second scroll member and the fitting assembly and movable between a closed position in which fluid communication between the compression pockets and the suction chamber is prevented and an open position in which fluid communication between the compression pockets and the suction chamber is allowed.

A compressor may include first and second scrolls, an axial biasing chamber, and a control valve. The second scroll includes an outer port and an inner port. The outer and inner ports may be open to respective intermediate-pressure compression pockets. The control valve may be in fluid communication with the inner port, the outer port, and the axial biasing chamber. Movement of the control valve into the first position allows fluid communication between the inner port and the axial biasing chamber. Movement of the control valve into the second position allows fluid communication between the outer port and the axial biasing chamber.

An air injection enthalpy-increasing scroll compressor is provided. The compressor has a main frame, a movable scroll plate and a stationary scroll plate. The movable scroll plate has a movable plate end plate and a movable scroll wrap arranged on a side end face of the movable plate end plate. A back pressure chamber is defined between the movable plate end plate and the main frame. The stationary scroll plate has a fixed scroll end plate and a stationary scroll wrap arranged on a side end face of the fixed scroll end plate. The stationary scroll wrap and the movable scroll wrap are engaged with each other to form a crescent-shaped compression cavity. The movable scroll plate and the stationary scroll plate are provided with medium pressure passages that, during the rotation of the movable scroll plate, communicate the compression cavity with the back pressure chamber.

The present disclosure is directed to a screw compressor system having a compressor housing with a pair of screw rotors rotatably supported within a compression chamber. Lubricant is injected into a compression chamber at a first volume ratio and at a second volume ratio greater than the first volume ratio to increase the sealing and lubrication between the screw rotors and rotor bores in the compressor housing as well as to increase heat transfer from a compressed working fluid in the compression chamber.