| 摘要 |
PROBLEM TO BE SOLVED: To provide a hybrid system turbo type vacuum instrument of which an axial length is shortened. SOLUTION: The turbo type vacuum instrument is provided with a turbo molecule pump TMP disposed at a transition flow area from a suction port 1K to a circumferential flow pump SP and formed between a rotor 2 and a housing 1; and a screw groove pump NP disposed at a transition flow area between the turbo molecule pump TMP and the circumferential flow pump SP and formed between the rotor 2 and the housing 1. A gas from the suction port 1K is discharged from a discharge port 1H provided on the housing 1. An outer periphery wall and an inner periphery wall have cylindrical parts 2P, 2L corresponding to a surface of the housing 1 and a circular disc part 2V connecting the cylindrical parts 2P, 2L to a rotation shaft 3. The turbo molecule pump TMP is formed between an outer periphery wall of this cylindrical part 2P and the housing 1 and the screw groove pump NP is formed between an inner periphery wall of the cylindrical part 2L and the housing 1. Accordingly, a shaft length as a vacuum instrument can be shortened and is advantageous for a small size.
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