Patent ID: 8287259

Claim:
An oil-cooled type screw compressor having a compressor body that compresses a suction gas, and discharges compressed gas, comprising: a rotor casing of the compressor body; a pair of male and female screw rotors that is stored in said rotor casing, the male and female screw rotors meshing with each other; rotor shafts that are provided for each of said screw rotors, and that extend to both sides of each of said screw rotors, respectively; a suction port that is provided for one side in a longitudinal direction of said screw rotors, and that introduces the suction gas to said pair of screw rotors; a discharge port that is provided for the other side in the longitudinal direction of said screw rotors, and that discharges the compressed gas compressed by said screw rotors; a disc-shaped thrust plate that is provided near either end portion of each of said rotor shafts, respectively, in the longitudinal direction, the disc-shaped thrust plates rotating integrally with said rotor shafts, respectively; a sealing member that seals each respective thrust plate rotatably while spacing the thrust plates from said screw rotors, respectively, and the sealing members defining a first space and a second space on both sides of said thrust plates, respectively; a pair of thrust bearings that is disposed in the first space and the second space respectively, the pair of thrust bearings receiving a thrust force transmitted to said respective thrust plates placed between said pair of thrust bearings; an oil feed passage that communicates with one of said first space and said second space which is located on a side where a force is applied in a direction against the thrust force to the respective thrust plate when boosted, and that establishes communication between an inside of the one of said first and second spaces and an oil feed source; an oil discharge passage that communicates with the other of said first space and said second space which is located on side where a force is applied in a direction against an anti-thrust force to the respective thrust plate when boosted, and that establishes the communication between an inside of the other of said first and second spaces and an oil discharge destination; and an oil distribution passage through which oil is distributed between said first space and said second space.