Multistage vacuum pump
AssigneesCommonwealth Scientific and Industrial Research Organization, Fuji Seiki Inc.
InventorEckhard Bez
Life of this patent
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Abstract
A multistage vacuum pump is achieved by utilizing a single piston and cylinder assembly having opposite end portions with substantially equal diameters and an enlarged diameter central portion. One end of the cylinder is closed by a valve and a first stage pumping chamber is defined between the valve and the piston. The enlarged diameter portion of the piston has an axial extent less than the axial extent of the enlarged diameter portion of the cylinder to define second and third stage pumping chambers on opposite sides of the enlarged diameter portion of the piston. The three pumping chambers are interconnected by passage means to an inlet and outlet to provide a sequential reduction in pressure. A single drive unit may be connected to a plurality of pumping units for reciprocating the piston in each pumping unit.
Claims8
A multi-stage vacuum pump comprising housing means, a cylinder disposed in said housing means having opposite end portions of substantially equal diameter and an enlarged diameter central portion, a piston with a substantially hollow interior disposed in said cylinder having a closed end and an end open to said interior cylindrical end portions adjacent each end having substantially equal diameters and an enlarged diameter intermediate portion, first exhaust valve means disposed in said cylinder adjacent said closed end of said piston to define a first stage pumping chamber between said valve means and said closed end of said piston, said large diameter portion of said piston having an axial extent less than an axial extent of said enlarged diameter portion of said cylinder and defining an annular second stage pumping chamber and an annular third stage pumping chamber on opposite sides of said enlarged diameter portion of said piston, inlet and outlet means disposed in said housing means and passage means interconnecting said inlet and outlet means with said pumping chambers, second and third exhaust valve means disposed in said passage means adjacent said second and third stage pumping chambers and drive means operatively connected to said piston for reciprocating said piston in said cylinder.
Dependencies are inferred from the claim text.