PURPOSE: To obtain the vacuum pump having a high efficiency by forming a thin expansion part which extends during shift and is closely attached onto the inner wall of a cylinder at the front and rear peripheral edges of a piston, thus improving the airtightness between the piston and the cylinder.
CONSTITUTION: A piston 7 is axially supported by a rod 6 in a cylinder 2. Each annular thin expansion part 7' is installed at the front and rear peripheral edges of the piston 7. Therefore, in the suction operation, the thin expansion part 7' at the rear edge of the piston 7 is closely attached with the inner wall of the cylinder 2, and the airtightness is improved, while in the discharge operation, the thin expansion part 7' at the front edge of the piston 7 is closely attached with the inner wall of the cylinder 2, and the airtightness is improved, and the inflow of gas from between the cylinder 2 and the piston 7 is prevented, and the vacuum pump having a high efficiency can be obtained.
HATASAKI YASUZO
TAKAI KEIICHI
KAWANOBU KINYA
OOTAGOSHI HITOSHI
AOKI ELECTRIC IND CO LTD
| JP55180092B |