| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw compressor which can reduce starting torque by a simple structure. SOLUTION: This screw compressor 1 is provided with a piston valve 31 comprising a columnar space part 32 formed in a part of a casing 12 opposed to a delivery side end face of a screw rotor 13 to be opened to a tooth space 35 of the screw rotor 13 not connected to a suction port 17, a delivery port 19 and a feedback path 34 connected to the suction port 17 to make the tooth space 35 communicate with the feedback path 34 and a piston 33 insertion fitted capable of sliding into the columnar space part 32 to advance toward the delivery side end face to make the tooth space 35 and the feedback path 34 in a non-communication condition in the other hand to make both the tooth space and the feedback path into a communication condition by retreating in the reverse direction, the screw compressor is provided with a pressure switching flow path 36 making a back surface side space part 32A of the piston 33 communicate with the suction port 17 at pressure lower than the tooth space 35 at starting time and making the back surface side space part 32A communicate with the delivery port 19 at a pressure higher than the tooth space 35 after completion of starting.
|
