JPS5546011A - Oil cooled screw compressor with regulating valve - Google Patents

Abstract

PURPOSE:To eliminate deterioration of efficiency of an oil cooled screw compressor with a regulating valve during an intermediate load running of the compressor to improve the efficiency thereof by constituting same such that the regulating valve has a recovery hole formed therein so as to permit recovery oil to be returned into a compressing chamber after suction is completed even if the regulating valve is moved during volume regulating operations. CONSTITUTION:A compressor includes a pair of screw rotors 5, 6 adapted to be rotated within cylindrical bores 3, 4, respectively, in a casing in a meshed relation with each other, and regulating valve 21 adapted to vary a cut-off position of a compressing chamber to regulate the volume of compressed air. During running of the compressor, lubricating oil is introduced from an oiling port 35 into passages 36-38 to thereafter lubricate bearings 8-13 and a shaft seal 15. The oil is then passed through recovery passages 39-41, another passage 50, a groove 51 provided in the regulating valve 21, and a further passage 52 and is recovered into the compressing chamber through an opening 53. The opening 53 is provided adjacent to and inside of a seal line 57 in an advanced position by the groove width 56 of a rotor from an adjacent seal line of the rotor 6 that passes a crossing point 54 of a suction side end face 29 with a center line 43 of the regulating valve 21, as illustrated in the development in the drawing.