SCREW ROTOR OF SCREW PUMP, SCREW PUMP AND SUPERCHARGER USING SCREW PUMP

摘要

PROBLEM TO BE SOLVED: To prevent an intake atmosphere side and a discharge atmosphere side of a screw pump from communicating with each other through a blow hole.;SOLUTION: The number of threads in a first screw rotor 13 which rotates in mesh with a second screw rotor 14 is larger than that in a second screw rotor 14. When the number of threads in the second screw rotor 12 is n, and an angle formed by a pair of intersections P2, P1 of a second circle C2 which is a rotation trajectory of tips of screw tooth 30, 31, 32 of the second screw rotor 14 and a first circle C1 which is a rotation trajectory of tips of screw tooth 22, 23, 24, 25 of the first screw rotor 13 based on the rotation center of the second screw rotor 14 is γ, a twist angle Θ of a tooth profile G2 from the suction side end surface 141 to the discharge side end surface 142 in the second screw rotor 14 satisfies the following expression (1): (1) 0Θ≤360°-γ-360°/n.;COPYRIGHT: (C)2013,JPO&INPIT