Reciprocating completely sealed fluid-tight vacuum pump

A completely dry fluid-tight vacuum pump comprising at least one variable volume pumping chamber having an intake, an outlet, a fixed axial end wall and a mobile axial end wall, non-return means adapted to procure one way flow of fluid from said intake to said outlet and two radially stiff and axially flexible circular metal members in said chamber;

• said mobile axial end wall forming part of a mobile assembly which is adapted to move axially to and from between a position with said axial end walls moved apart and a position with said axial end walls moved together to apply said circular members respectively to said axial end walls;
• said fixed axial end wall and said mobile axial end walls comprising annular openings,
• said circular metal members having an annular configuration with a substantially toroidal transverse cross-section, formed by two flexible metal annular diaphragms joined back-to-back at their inside circular edges and fabricated in a single piece, and outwardly open to define two outside circular edges;
• said two outside circular edges respectively fastened and sealed to said fixed axial end wall and to said mobile axial end wall, wherein in the moved together position said two annular circular metal members and the respective adjacent annular openings in said axial end walls against which they are applied toward have substantially the same diametrical profile;
• such that the residual space between the circular members and the respective axial end walls is as small as possible while maintaining a very small clearance between said circular members and said respective axial end walls.

A completely dry fluid-tight vacuum pump comprising at least one variable volume pumping chamber having an intake, an outlet, a fixed axial end wall and a mobile axial end wall, non-return means adapted to procure one way flow of fluid from said intake to said outlet and two radially stiff and axially flexible circular metal members in said chamber;

• said mobile axial end wall forming part of a mobile assembly which is adapted to move axially to and fro between a position with said axial end walls moved apart and a position with said axial end walls moved together to apply said two circular members respectively to said axial end walls;
• said two circular metal members having similar central parts through which they are fastened together so that their respective diametrical profiles are substantially symmetrical relative to a transverse plane, said outside parts of said two metal members are respectively attached and sealed to said fixed axial end wall and to said mobile axial end wall, and having a passage formed in said fastened together central parts;
• wherein in the moved together position said circular metal members and the respective adjacent axial end wall against which it is applied towards have substantially the same diametrical profile;
• such that the residual space between the circular metal members and the respective axial end walls is as small as possible while maintaining a very small clearance between said circular metal members and said respective axial end walls.

A completely dry fluid-tight vacuum pump comprising at least one variable pumping chamber having an intake, an outlet, a fixed axial end wall and a mobile axial end wall, non-return means adapted to procure one-way flow of fluid from said intake to said outlet;

• two radially stiff and axially flexible circular metal members disposed in said chamber and fixed to each other in their central parts and having an entirely free passage extending through said central parts, said two circular metal members having a radially outwardly opening toroidal configuration and being symmetrical relative to a radial plane, the outer part of one circular member being sealingly fixed relative to said fixed axial end wall and the outer part of the other circular member being sealingly fixed to said mobile axial end wall;
• said circular members being axially reciprocably movable between a first position in which said axial end walls are relatively axially remote from each other and a second position in which said axial end walls are relatively axially close together, said circular members and said respective axial end walls having matching diametrical profiles in said second close together position;
• and minimal residual space being defined between said circular metal members and said respective axial end walls in said second close together position while maintaining a very small clearance between said circular metal members and said respective axial end walls.