Patent ID: 7413419

Claim:
Water-injected screw compressor, comprising a compressor element with a housing which borders a compression chamber in which a male rotor and a female rotor are installed, each rotor having axle ends borne in the housing by water-lubricated slide bearings, an electric motor for driving said compressor element, which motor comprises a housing which carries a stator within an inner space thereof, which stator surrounds a rotor with a rotor shaft, a pressure conduit which connects to the compression chamber, a vessel, which also is a water separator, in the pressure conduit, and a water return between the vessel and the compression chamber, wherein an axle end of one of the rotors is directly coupled to or is formed in one piece with the rotor shaft of the motor, said rotor shaft being located in a prolongation of said axle end, and wherein the rotor shaft of the motor is borne in at least one water-lubricated slide bearing; wherein an inner space of the housing around a subassembly formed by the rotor shaft of the motor and the axle end connected thereto is sealed at an inside of each of the slide bearings situated at opposite sides of the rotor by a lip seal which is directed with a free extremity towards the respective slide bearing, whereas the inner space of the housing of the motor is in connection with a source of blocking gas under pressure via at least one conduit and said blocking gas from the inner space of the housing of the motor acts to lift the lip seals.