Draw back pump

• US 20050276707A1
• Filed: 09/13/2004
• Published: 12/15/2005
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: Hygiene-Technik Inc.
• Original Assignee: Hygiene-Technik Inc.
• Inventors: Ophardt, Heiner
• Granted Patent: US 7,267,251 B2
• Time in Patent Office: Days
• US Class Current: 417/437
• CPC Class Codes: A47K 5/1207 Dispensing from the bottom of the dispenser with a vertical piston
• CPC Class Codes: B05B 11/1001 Piston pumps B05B11/1087, B05B11/1088, B05B11/109 take precedence
• CPC Class Codes: B05B 11/1097 with means for sucking back the liquid or other fluent material in the nozzle after a dispensing stroke

Abstract

A piston pump dispenser having a reciprocating piston pump arrangement which, in a dispensing stroke, dispenses fluid from an outlet and, in a charging stroke, to draw fluid from a reservoir also draws back fluid from the outlet through which fluid is dispensed in the dispensing stroke.

Claims

1. A pump for a fluid dispenser, the pump comprising:

a first piston pump and a second piston pump,

the first piston pump having a first chamber and a first piston reciprocally slidable in the first chamber between an extended and a retracted position,

the first chamber having an inlet adapted for communication with a reservoir of fluid,

the first chamber having an exit in communication with an outlet passageway having an outlet from which fluid is to be dispensed,

a one-way inlet valve permitting fluid flow into the first chamber from the reservoir via the inlet but preventing fluid flow outwardly from the first chamber through the inlet;

a one-way outlet valve permitting fluid flow to the outlet passageway from the first chamber via the exit but preventing fluid flow through the one-way outlet valve from the outlet passageway into the first chamber via the exit,

the second pump having a second chamber and a second piston reciprocally slidable in the second chamber for movement between an extended position and a retracted position,

a communication port opening into the second chamber in communication with the outlet passageway downstream of the one-way outlet valve,

a coupling mechanism coupling the first piston and the second piston for movement in unison such that when the first piston pump dispenses fluid from the first chamber to the outlet passageway via the exit, the second piston dispenses fluid from the second chamber to the outlet passageway and when the first piston pump draws fluid into the first chamber past the one-way inlet valve, the second piston pump draws fluid through its communication port from the outlet passageway into the second chamber.

2. A pump as claimed in claim 1 wherein the first piston and the second piston are mechanically coupled together for movement in unison.

3. A pump as claimed in claim 2 wherein the first piston and second piston are coaxially disposed for coaxially sliding within a piston chamber-forming member providing the first piston chamber and the second piston chamber coaxially therein.

4. A pump as claimed in claim 1 wherein in a charge stroke, the first piston and the second piston are moved respectively relative to the first chamber and the second chamber in the same direction with the movement of the first piston in the first chamber drawing fluid into the first chamber through the one-way inlet valve, and the movement of the second piston in the second chamber drawing fluid into the second chamber from the outlet passageway.

5. A pump as claimed in claim 4 wherein the first chamber and the second chamber are cylindrical, the second chamber having a diameter different than a diameter of the first chamber.

6. A pump as claimed in claim 5 wherein the first chamber and the second chamber are coaxial, the exit from the second piston chamber opening into the first chamber, the one-way outlet valve disposed across the exit of the first chamber wherein fluid to be discharged from the first chamber passes through the second chamber.

7. A pump as claimed in claim 6 wherein in the charge stroke suction is created in both the first chamber and the second chamber with the one-way outlet valve preventing suction from the first chamber acting on fluid in the second chamber.

8. A pump for dispensing liquids from a reservoir, comprising:

a piston-chamber forming member having a cylindrical inner chamber and a cylindrical outer chamber,

the inner chamber and outer chamber each having a diameter, a chamber wall, an inner end and an outer end,

the inner end of the inner chamber in fluid communication with a reservoir, the diameter of the inner chamber being less than the diameter of the outer chamber,

the inner chamber and outer chamber being coaxial with the outer end of the inner chamber opening into the inner end of the outer chamber,

a one-way valve between the reservoir and the inner chamber permitting fluid flow through the inner end of said inner chamber only from the reservoir to the inner chamber;

a piston forming element received in the piston-chamber forming member axially slidable inwardly and outwardly therein,

said piston forming element being generally circular in cross-section with a central axially extending hollow stem having a outlet passageway closed at an inner end and having an outlet proximate an outer end,

a circular flexing disc extending radially outwardly from the stem proximate an inner end of the stem, the flexing disc having an elastically deformable edge portion proximate the chamber wall of the inner chamber circumferentially thereabout,

a circular sealing disc extending radially outwardly from the stem spaced axially outwardly from the flexing disc, the sealing disc engaging the chamber wall of the outer chamber circumferentially thereabout to form a substantially fluid impermeable seal therewith on sliding of said piston forming element inwardly and outwardly,

an inlet located on the stem between the flexing disc and sealing disc in communication with the outlet passageway,

the piston forming element slidably received in the piston-chamber forming member for reciprocal axial inward and outward movement therein with the flexing disc in the inner chamber and sealing disc in the outer chamber,

the flexing disc substantially preventing fluid flow in the inner chamber past the flexing disc in an inward direction,

the flexing disc elastically deforming away from the chamber wall of the inner chamber to permit fluid flow in the inner chamber past the flexing disc outwardly.

9. A pump as claimed in claim 8 including an engagement flange on said stem outward of the piston chamber forming member for engagement to move the piston forming element inwardly and outwardly,

15. A pump as claimed in claim 9 including a plurality of axially extending webs on said stem extending radially outwardly from the stem to engage the chamber wall of at least one of the inner chamber, intermediate chamber and outer chamber and guide the piston forming element in sliding axially centred alignment within the outer chamber.

16. A pump as claimed in claim 9 wherein the piston forming element consists of a unitary element formed entirely of plastic by injection molding.

10. A pump for dispensing liquid from a reservoir comprising:

a piston-chamber forming member having a cylindrical inner chamber, a cylindrical intermediate chamber and a cylindrical outer chamber, the inner chamber, intermediate chamber and outer chamber each having a diameter, a chamber wall, an inner end and an outer end;

wherein either;

(a) the diameter of the inner chamber being less than the diameter of the intermediate chamber, and the diameter of the intermediate chamber being less than the diameter of the outer chamber, or

(b) the diameter of the inner chamber being greater than the diameter of the intermediate chamber, and the diameter of the intermediate chamber being greater than the diameter of the outer chamber,

the inner chamber, intermediate chamber and outer chamber being coaxial with the outer end of the inner chamber opening into the inner end of the intermediate chamber and the outer end of the intermediate chamber opening into the inner end of the outer chamber;

the inner end of the inner chamber in fluid communication with a reservoir,

a piston forming element received in the piston-chamber forming member axially slidable inwardly and outwardly therein,

said piston forming element being generally circular in cross-section with a central axially extending hollow stem having a central outlet passageway closed at an inner end and having an outlet proximate an outer end,

a circular inner flexing disc extending radially outwardly from the stem proximate an inner end of the stem, the inner flexing disc having an elastically deformable edge portion proximate the chamber wall of the inner chamber circumferentially thereabout,

a circular intermediate flexing disc extending radially outwardly from the stem spaced axially outwardly from the inner flexing disc, the intermediate flexing disc having an elastically deformable edge portion proximate the chamber wall of the intermediate chamber circumferentially thereabout,

a circular sealing disc extending radially outwardly from the stem spaced axially outwardly from the intermediate flexing disc, the sealing disc engaging the chamber wall of the outer chamber circumferentially thereabout to form a substantially fluid impermeable seal therewith on sliding of said piston forming element inwardly and outwardly,

an inlet located on the stem between the intermediate flexing disc and the sealing disc in communication with the outlet passageway,

the piston forming element slidably received in the piston chamber forming member for reciprocal axial inward and outward movement therein with the inner flexing disc in the inner chamber, the intermediate flexing disc in the intermediate chamber and the 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 intermediate flexing disc substantially preventing fluid flow in the intermediate chamber past the intermediate 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 intermediate flexing disc elastically deforming away from the chamber wall of the intermediate chamber to permit fluid flow in the intermediate chamber past the intermediate flexing disc in an outward direction.

11. A pump as claimed in claim 10 wherein the diameter of the inner chamber is less than the diameter of the intermediate chamber and the diameter of the intermediate chamber is less than the diameter of the outer chamber.

12. A pump as claimed in claim 10 wherein the diameter of the inner chamber is greater than the diameter of the intermediate chamber and the diameter of the intermediate chamber is greater than the diameter of the outer chamber.

13. A pump as claimed in claim 10 wherein:

said piston forming element extends outwardly from the outer end of the outer chamber, and

an engagement flange is provided on the piston forming element outward of the piston-chamber forming member for engagement to move the piston forming element inwardly and outwardly.

14. A pump as claimed in claim 13 wherein:

the engagement flange comprises a circular flange extending radially outwardly from said stem.