Disposable plastic liquid pump

A unitary piston forming element formed entirely of plastic adapted to be received in a stepped cylindrical chamber having an inner cylindrical chamber of a first diameter and a coaxial, axially adjacent outer cylindrical chamber of a second diameter different from the first diameter,

• said piston forming element being generally cylindrical in cross-section with a central axially extending hollow stem having a central passageway closed at an inner end and having an outlet proximate an outer end,
• an inner circular flexing disc extending radially outwardly from the stem, the inner flexing disc having an elastically deformable edge portion proximate the chamber wall of the inner chamber circumferentially thereabout,
• an outer circular flexing disc extending radially outwardly from the stem spaced axially outwardly from the inner flexing disc, the outer flexing disc having an elastically deformable edge portion proximate the chamber wall of the outer chamber circumferentially thereabout,
• a circular sealing disc extending radially outwardly from the stem spaced axially outwardly from the outer flexing disc, the sealing disc engaging the chamber wall of the outer chamber circumferentially thereabout to substantially prevent fluid flow in the outer chamber past the sealing disc in an outward direction,
• an inlet located on the stem between the outer flexing disc and the sealing disc in communication with the passageway,
• the piston forming element slidably received in the stepped cylindrical chamber for reciprocal axial inward and outward movement therein with the inner flexing disc in the inner chamber and the outer flexing disc and sealing disc in the outer chamber,
• the inner flexing disc substantially preventing fluid flow in the inner chamber past the inner flexing disc in an inward direction,
• the outer flexing disc substantially preventing fluid flow in the outer chamber past the outer flexing disc in an inward direction,
• the inner flexing disc elastically deforming away from the chamber wall of the inner chamber to permit fluid flow in the inner chamber past the inner flexing disc in an outward direction,
• the outer flexing disc elastically deforming away from the chamber wall of the outer chamber to permit fluid flow in the outer chamber past the outer flexing disc in an outward direction.

A fluid pump comprising:

• piston-chamber forming means having a stepped chamber comprising an inner chamber and an outer chamber, the inner chamber and outer chamber each having a chamber wall, an inner end and an outer end,
• the outer end of the inner chamber opening into the inner end of the outer chamber,
• the inner end of the inner chamber in fluid communication with a source of fluid,
• a piston forming element received in the piston-chamber forming means axially slidable inwardly and outwardly therein,
• said piston forming element having an axially extending stem having a passageway therethrough between an inlet and an outlet, the outlet proximate an outer end of the stem,
• an inner flexing disc on the stem extending radially outwardly from the stem to proximate the chamber wall of the inner chamber circumferentially thereabout,
• an outer flexing disc on the stem spaced axially outwardly from the inner flexing disc and extending radially outwardly from the stem to proximate the chamber wall of the outer chamber circumferentially thereabout,
• a sealing disc on the stem spaced axially outwardly from the outer flexing disc and extending radially outwardly from the stem to proximate the chamber wall of the outer chamber circumferentially thereabout,
• the inlet located on the stem between the outer flexing disc and the sealing disc,
• the piston forming element slidably received in the piston-chamber forming means for reciprocal axial inward and outward movement therein with the inner flexing disc in the inner chamber and the outer flexing disc and sealing disc in the outer chamber,
• the inner flexing disc substantially preventing fluid flow in the inner chamber past the inner flexing disc in an inward direction,
• the outer flexing disc substantially preventing fluid flow in the outer chamber past the outer flexing disc in an inward direction,
• the sealing disc substantially preventing fluid flow in the outer chamber past the sealing disc in an outward direction,
• the inner flexing disc elastically deforming away from the chamber wall of the inner chamber to permit fluid flow in the inner chamber past the inner flexing disc in an outward direction,
• the outer flexing disc elastically deforming away from the chamber wall of the outer chamber to permit fluid flow in the outer chamber past the outer flexing disc in an outward direction,
• wherein in a cycle of a first stroke of inward axial movement and a reciprocal second stroke of outward axial movement of the piston forming element axially within the piston-chamber forming member, liquid is drawn from the reservoir past the inner flexing disc to between the inner flexing disc and the outer flexing disc in one of said first and second strokes and liquid is pumped from between the inner flexing disc and the outer flexing disc past the outer flexing disc and via the inlet to the passageway and out of the outlet, in the other of said first and second strokes.

A fluid pump comprising:

• piston-chamber forming means having a stepped chamber comprising an inner chamber and an outer chamber, the inner chamber and outer chamber each having a chamber wall, an inner end and an outer end,
• the outer end of the inner chamber opening into the inner end of the outer chamber,
• the inner end of the inner chamber in communication with a source of fluid,
• a piston forming element received in the piston-chamber forming means axially slidable inwardly and outwardly therein,
• said piston forming element having an axially extending stem,
• an inner flexing disc on the stem extending radially outwardly from the stem to proximate the chamber wall of the inner chamber circumferentially thereabout,
• an outer flexing disc on the stem spaced axially outwardly from the inner flexing disc and extending radially outwardly from the stem to proximate the chamber wall of the outer chamber circumferentially thereabout,
• a sealing disc on the stem spaced axially outwardly from the outer flexing disc and extending radially outwardly from the stem to proximate the chamber wall of the outer chamber circumferentially thereabout,
• a passageway through said piston forming element between an inlet between the outer flexing disc and the sealing disc and an outlet axially outward of the outer flexing disc,
• the piston forming element slidably received in the piston-chamber forming means for reciprocal axial inward and outward movement therein with the inner flexing disc in the inner chamber and the outer flexing disc and sealing disc in the outer chamber,
• the inner flexing disc substantially preventing fluid flow in the inner chamber past the inner flexing disc in an inward direction,
• the outer flexing disc substantially preventing fluid flow in the outer chamber past the outer flexing disc in an inward direction,
• the sealing disc substantially preventing fluid flow in the outer chamber past the sealing disc in an outward direction,
• the inner flexing disc elastically deforming away from the chamber wall of the inner chamber to permit fluid flow in the inner chamber past the inner flexing disc in an outward direction,
• the outer flexing disc elastically deforming away from the chamber wall of the outer chamber to permit fluid flow in the outer chamber past the outer flexing disc in an outward direction,
• wherein in a cycle of a first stroke of inward axial movement and a reciprocal second stroke of outward axial movement of the piston forming element axially within the piston-chamber forming member, liquid is drawn from the fluid source past the inner flexing disc to between the inner flexing disc and the outer flexing disc in one of said first and second strokes and liquid is pumped from between the inner flexing disc and the outer flexing disc past the outer flexing disc and via the inlet to the passageway and out of the outlet, in the other of said first and second strokes.