PURPOSE: To obtain a small-sized vacuum pump which operates from the atmospheric pressure to a high vacuum by installing at least a siegbahn pump stage on a suction port side and arranging a circumferential flow compression pump stage on an exhaust port side.
CONSTITUTION: A rotary shaft 1 penetrates through a housing 2 having a suction port 2A and an exhaust port 2B and is supported by a bearing 7. In this case, an axial flow compression pump stage 15 and a siegbahn pump stage 14 are arranged in connection in the suction port 2A, and a circumferential compression pump stage 13 is connected in succession in the exhaust port 2B. The pump stage 15 is constituted of an axial flow vane wheel 15A and a fixed blade 15B, and the pump stage 14 is constituted of fixed plates 14A and rotary discs 14B. Further the pump stage 13 is constituted of the vane wheels 13A having vanes 13C radially installed and fixed plates 13B. Therefore, in the transient state in the initial stage of the pump operation, each pump stage 14, 15 is allowed to act as compressor, and in the stationary state, sealing action is secured by the pump stages 15 and 14.
NAGAOKA TAKASHI
TANIYAMA MINORU
MASE MASAHIRO
NISHIUCHI AKIRA
