Method and apparatus for precision squeeze tube valving, pumping and dispensing of work fluid(s)

• US 4,967,940 A
• Filed: 02/21/1989
• Issued: 11/06/1990
• Est. Priority Date: 02/21/1989
• Status: Expired due to Fees

• Current Assignee: Graco Incorporated
• Original Assignee: 3M Company
• Inventors: Blette, Russell E., Roeser, John O.
• Primary Examiner(s): SKAGGS JR, H GRANT
• Application Number:
  US07/313,389
• Time in Patent Office: 623 Days
• Field of Search: 417/474, 417/475, 417/477, 251/7, 222/214, 222/109, 222/110, 222/451, 222/450
• US Class Current: 222/214
• CPC Class Codes: B67D 7/0216 by squeezing collapsible or flexible storage containers B67D7/0255 takes precedence; for dispensing beverages on draught B67D1/0001

Abstract

Presented is a method and apparatus for precision control of work fluids in a squeezable tube that has no surge of work material during the shut off closing of the tube which is accomplished by a compensator moving simultaneously and oppositely to the shut off member movement, each of the compensator and the shut off member having different stroke lengths and tube engagable surface areas which effectively keep the internal volume of the tube the same. The method and apparatus are useful standing alone, in coordination with precision positive displacement pumping under computer control which is also presented, and as a part of sequential or simultaneous movement of a valve/pump dispensing head coordinated with a stationary or movable work piece to provide exceedingly fine control dispensing. Suckback between dispensing shots is coordinated with shut off and movements of inlet, outlet and dispensing members to afford operator programmable dispensing with precision and without drip.

Claims

1. A high precision positive displacement squeeze tube pump apparatus comprising:

(a) tube means having first and second spaced end means and characterized as;

(i) being hollow and having walls formed of resilient material,

(ii) forming a closed pathway for flow of a flowable work material therethrough,

(iii) having its first end associated with a source of flowable work material, and

(iv) having its second end associated with means for receiving said flowable work material after passage through said tube means, and

(b) flow control means for controlling the flow of work material through said tube means, said flow control means being characterized as comprising;

(i) first, second, third and fourth cooperating spaced tube squeezing means located intermediate said first and second spaced end means of said tube means and engagable with said tube means for effecting control of the flow of work material therethrough,

(ii) said first tube squeezing means having open and closed positions, being movable between said open and closed positions, and located near said first end means to control ingress of work material to said tube means,

(iii) said second tube squeezing means being spaced from said first tube squeezing means, having open and closed positions, and being movable between said open and closed positions for controlling exiting of said flowable work material from said tube means,

(iv) said third tube squeezing means being associated with said tube means intermediate said first and second tube squeezing means, being movable toward and away from squeezing relation of said tube means, and when moving toward said tube means being operable to displacingly force work material from said tube means, and

(iv) fourth tube squeezing means operable in coordination with said second tube squeezing means to compensate for displacement of work material through said tube means when said second tube squeezing means moves between its open and closed positions,

whereby the volume of material in said tube means that is displaced from said tube means will be primarily controlled by movement of said third tube squeezing means.

2. The apparatus set forth in claim 1 wherein said first tube squeezing means is further characterized as inlet means to permit and prevent flow of flowable work material into said apparatus, and said second tube squeezing means is further characterized as outlet means which is coordinated with a position of said inlet means whereby when said inlet means is in its flow preventing position said outlet means is in its open oposition, and when said inlet means is in its flow permitting position, said outlet means is in its closed position.

3. The apparatus set forth in claim 12 wherein said operator means comprises first tube engaging means, first mover means for moving said first tube engaging means toward and away from said tube means, first stepper motor means for moving said first mover means, and operator programmable means for programming the movement of said first stepper motor means, whereby the displacement of a volume of flowable work material in said apparatus may be controlled with precision.

4. The apparatus set forth in claim 3 wherein said fourth tube squeezing means is located down flow stream from said second tube squeezing means, link means for assuring that said fourth tube squeezing means moves in a direction opposite to the direction of movement of said second tube squeezing means, said fourth surface area means being larger than said second surface area means.

5. The apparatus set forth in claim 12 wherein the said second tube squeezing means has a first length of stroke of movement toward and away from squeezing said tube means and said fourth tube squeezing means has a second length of stroke of movement toward and away from squeezing said tube means, adjustment means associated with said link means for adjusting said second length of stroke of movement, whereby operator adjustment of said adjustment means is operable to cause the coordinated relative movement of said fourth tube squeezing means to said second tube squeezing means to be adjusted to provide adjustable suck back of said flowable work material.

7. The apparatus set forth in claim 5 wherein said link means is operable to cause further movement of said fourth tube squeezing means subsequent to said second tube squeezing means reaching its fully closed position respecting said tube means.

8. The apparatus set forth in claim 5 wherein said second surface area means is of a size of approximately one-half of the size of the area of said fourth surface area means and said length of said first stroke of movement is approximately twice the length of movement of said second stroke of movement.

9. The apparatus set forth in claim 8 wherein there is a first path of the length of said first stroke of movement and a second path of the length of said second stroke of movement, said first path of movement and said second path of movement are in overlapping parallel relationship, the first stroke of movement and the second stroke of movement being opposite in direction and coordinated and arranged through said link means whereby when said second tube squeezing means moves said second surface area means into closed position respecting said tube means, said fourth tube squeezing means fourth surface area means is located in non tube pinching relationship and when said second tube squeezing means second surface area means is disposed in its open position, said fourth tube squeezing fourth surface area means is located in engagement with said tube means to cause a partial pinching of said tube means.

10. The apparatus set forth in claim 9 wherein the product of multiplying the first length of stroke times the second surface area means measurement in square inches is approximately equal to the product of said second length of stroke times the fourth surface area means measurement in square inches whereby the opening and closing movement of said outlet means has a de minimis effect on the volume of flowable work material being dispensed from said apparatus.

11. The apparatus set forth in claim 5 further comprising mechanical connection means between said first and second tube squeezing means, said connection means comprising pivotal lever means connected to each of said first and second tube squeezing means, said connection means further comprising first spring means, second spring means of lesser spring bias than said firs spring means, said connection means second spring means causing movement of said second tube squeezing means to open position from closed position upon movement of said first tube squeezing means from open position to closed position and said first spring means affecting movement of said second tube squeezing means from open position to closed position upon movement of said first:

tube squeezing means from closed to open position, said first spring means and second spring means being located, arranged and disposed in said connection means to assure that said first tube squeezing means will move to its open position only when said second tube squeezing means is in its closed position

12. The apparatus of claim 2 wherein said third tube squeezing means has operator means, said operator means being characterized as providing operator selected adjustable positions of squeezing on said tube means between full open and full closed positions in adjustable timed relationship to movement of said first, second and fourth tube squeezing means, whereby the displacement of a volume of flowable work material in said tube means may be selectively changed by an operator.

13. The apparatus set forth in claim 12 wherein said operator means comprises first tube engaging means, first mover means for moving said first tube engaging means toward and away from said tube means, first stepper motor means for moving said first mover means, and operator programmable means for programming the movement of said first stepper motor means, whereby the displacement of a volume of flowable work material in said apparatus may be controlled with precision.

14. The apparatus set forth in claim 5 wherein said operator programmable means is further characterized as having adjustable second control means, said first tube squeezing means comprises second tube engaging means and second mover means for moving said second tube engaging means toward and away from said tube means, said adjustable second control means being operative to cause said second mover means to move said second tube engaging means in adjustable timed relationship to movement of said third tube squeezing means through said operator programmable means.

15. The apparatus set forth in claim 13 wherein said first mover means comprises rotatable cam means having a cam surface of predetermined surface length, said cam surface operatively engaging said first tube engaging means to move said first tube engaging means from a recessed to a dispensed position, the degree of rotation of said cam means determining the tube pinching movement of said first tube engaging means and the location of said dispensed position to in turn provide displacement of a volume of flowable work material.

16. The apparatus set forth in claim 15 wherein said operator programmable means creates a pulse stream, said first stepper motor means receives said pulse stream means from said operator programmable means, and operator programming manipulation cf said pulse stream means being operable to cause said cam means to commence movement in a first direction, to stop movement and to reverse movement in very small increments of movement in any preselected sequence and duration, whereby, by operator selection said cam means will cause movement of said first tube engaging means to adjust movement toward and away from said tube means to afford adjustable displacement volume dispensing and suck back of flowable work materials

17. The apparatus set forth in claim 2 wherein said apparatus is further characterized as having pivotal mechanical means, said mechanical means being operable for causing said movable first and second tube squeezing means to move in coordinated relationship to each other and for simultaneously assuring that said first tube squeezing means does not move toward its open position from its closed position when said second tube squeezing means is in its open position.

18. The apparatus set forth in claim 1 wherein said tube means is a deliberately disposable replacement item adapted for quick easy mounting and dismounting relative to said valve pump means.

19. The apparatus set forth in claim 1 wherein coordination means is provided for coordinating predetermined sequential movements of said first, second, third and fourth tube squeezing means, said coordination means causing a timed second relationship between said first, second and third tube squeezing means, whereby when said first tube squeezing means moves to its tube means closing position, said second tube squeezing means moves to its open position, and said third tube squeezing means after moving toward said tube squeezing position to displace flowable work material subsequent to said first tube squeezing means arriving in its closed position, will move away from said tube means prior to movement of said first tube squeezing means to its open position and prior to said second tube squeezing means moving to its closed position, to cause a back pressure to suck back flowable work material.

6. The apparatus set forth in claim 59 wherein said first length of stroke of movement is greater than said second length of stroke of movement.

20. The method of precision positive displacement pumping of a flowable work material from a source operable to cause the flowable work material to move to a pump means having a dispensing outlet and having a flexible tube means having an inlet end and an outlet end and having an inlet movable surface, a displacement movable surface, an outlet movable surface and a compensator movable surface each for pinchingly engaging and disengaging said flexible tube means between the inlet end and outlet end, said compensator movable surface being larger than said outlet movable surface comprising the steps of:

(a) with said compensator movable surface being in a partial pinching position, moving the outlet movable surface from a flow permitting position to a complete tube pinching position while moving the inlet movable surface from a complete tube pinching position to a flow permitting position to permit flow of material from the said source and to prevent egress of work material in said tube means out said outlet end and to fill the flexible tube,

(b) preventing said flow from said source by moving said inlet movable surface to a complete tube pinching position and moving the outlet movable surface back to a flow permitting position,

(c) moving said displacement surface from a non tube pinching position toward a pinching position to cause displacement of material through said outlet end, and then,

(d) moving said outlet movable surface from the flow permitting position back to its pinching off position,

(e) substantially simultaneous with step (d), moving said compensator movable surface in a direction opposite to the movement of outlet movable surface and a distance proportional to the relative sizes of said outlet movable surface and said compensator movable surface,

whereby the volume of flowable work material in said tube means displacingly pumped by said displacement movable surface is substantially independent of the effect of movement of said outlet movable surface toward its pinching off of flow position.

21. The method of claim 20 wherein during step (a) the compensator movable surface moves from its partial pinching position to a non pinching position.

22. The method set forth in claim 21 further comprising the step of moving the displacement movable surface in a direction opposite to a tube pinching direction to cause a back pressure for suck back of flowable work material prior to movement of said outlet movable surface to its tub pinching position.

23. The method set forth in claim 22 wherein said compensator movable surface is moved away from a pinching engagement with said tube means subsequent to movement of the outlet movable surface completing a flow preventing pinching action to provide a back pressure suck back of work material.

24. Compact high precision versatile apparatus for positive displacement dispensing of a work liquid from a source of flowable work material, flow control means for receipt of flowable work material from said source and for precision displacement of said flowable work material to a dispensing outlet, said flow control means comprising frame means, flexible tube means mounted on said frame means, a displacement member movable with respect to said flexible tube means and said frame means, inlet valve tube pinching means and outlet valve tube pinching means, means for causing said inlet valve tube pinching means and said outlet valve tube pinching means to be movable in timed relationship to said displacement member and to each other to alternately permit filling of said flexible tube means and displacement from said flexible tube means of said work material for delivery to said dispensing outlet, rotary motion control means for said displacement member mounted on said frame means for moving said displacement member toward and away from pinching engagement with said flexible tube, said motion control means comprising rotary electric means and translation means, said translation means being comparable to translate rotary motion of said rotary electric means into rectilinear movement of said displacement member into and out of pinching movement of said displacement member to cause thereby displacement of a volume of work material for dispensing of work material at said dispensing outlet, said flow control means further comprising compensator means associated with said outlet valve tube pinching means, said compensator means being disposed for engagement with said flexible tube means, and linking means pivotally mounted on said frame means and interconnecting said compensator means and said outlet valve pinching means for movement in opposite directions with respect to said flexible tube means.

25. The apparatus set forth in claim 24 wherein said rotary motion control means comprises stepper motor means mounted on said frame means having a rotary output, cam means mounted on said frame means and associated with said rotary output for moving said displacement member to effect pinching engagement with said tube means, and programmable computer means located remote from said frame means for programmably controlling rotary output motion of said stepper motor means.