| 摘要 |
The present invention relates to a screw rotor type vacuum pump having a lead angle which continuously changes one screw rotor in three steps of equal interval, unequal interval and equal interval, wherein stable exhaust performance may be kept up to the range of 0.5 ? from the atmospheric pressure. According to the present invention, provided is a screw rotor type vacuum pump comprising: a pair of screw rotors for rotating, to be engaged with each other; a housing for receiving the pair of screw rotors and having a suction hole at one side and a discharge hole at the other side; a motor for driving the screw rotors; and screw threads formed on the outer peripheral surfaces of the screw rotors and having portions wherein a lead angle is continuously changed. |
