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

• US 5,035,350 A
• Filed: 08/22/1990
• Issued: 07/30/1991
• Est. Priority Date: 02/21/1989
• Status: Expired due to Fees

• Current Assignee: Graco Incorporated
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Blette, Russell E., Roeser, John O.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): Bomberg, Kenneth
• Application Number:
  US07/570,896
• Time in Patent Office: 342 Days
• Field of Search: 222/212, 222/214, 222/476, 222/504, 222/559, 222/109, 251/7, 137/614.4
• US Class Current: 222/212
• CPC Class Codes: B67D 7/0216 by squeezing collapsible or flexible storage containers B67D7/0255 takes precedence; for dispensing beverages on draught B67D1/0001
• CPC Class Codes: G01F 11/088 using a deformable conduit-like element

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. The method of precision positive shut off of a flowable work material from a source operable to cause the flowable work material to move through a dispensing outlet and having a flexible tube means intermediate the dispensing outlet and the source, said flexible tube means having an inlet end, an outlet end, an outlet movable surface and a compensator movable surface, each of said outlet movable surface and said compensator movable surface being operable 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 to prevent flow of material from said source and to prevent egress of work material in said tube means out said outlet end,

b) substantially simultaneous with step (a), 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, and

c) moving said outlet movable surface from said complete tube pinching to prevent flow position to said flow permitting position while substantially simultaneously moving the compensator movable surface to its original partial tube pinching position whereby the volume of flowable work material in said tube means displacingly moved by outlet movable surface is offset by the tube internal volume change caused by movement of the compensator movable surface thereby preventing surge or suckback of work material through said outlet end when said outlet movable surface moves toward its pinching off of flow position or flow permitting position without ballooning of the tube means.

2. The method of claim 1 wherein during step (a) the compensator movable surface moves from its partial pinching position to a lesser tube pinching position.

3. The method set forth in claim 2 wherein said compensator movable surface is further moved away from a lesser tube 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 suckback of work material.