VARIABLE CAPACITY FLUID-DISPENSING DEVICE

• US 3,640,434 A
• Filed: 05/15/1970
• Issued: 02/08/1972
• Est. Priority Date: 05/15/1970
• Status: Expired due to Term

• Current Assignee: Sherwood Medical Company (Medtronic Plc)
• Original Assignee: Clarence L. Walker
• Inventors: Walker, Clarence L.
• Primary Examiner(s): Reeves, Robert B.
• Assistant Examiner(s): Bartuska, Francis J.
• Application Number:
  US05/037,809
• Time in Patent Office: 634 Days
• Field of Search: 222/309,386,387,388,336,137,386.5,206,134,135,136,145,144.5 128/218P,234,235,DIG.5
• US Class Current: 222/144.5
• CPC Class Codes: G01F 11/06 with provision for varying the stroke of the piston

Abstract

A pipette or other device for measuring and dispensing liquids which includes an aligned series of decreasing diameter, stepped cylinder chambers, e.g., three, contained in a barrel with the three chambers serviced by a common stepped piston for emptying and filling a receiver or reservoir carried by the device in communication with the chambers. A chamber at one end of the array is maintained in unobstructed flow communication with the receiver or reservoir which may or may not be a removable tip or nozzle on the device. A vented passageway communicates with vent ports from each chamber. A valving member is provided in the passage for selectively venting one or more of the chambers or connecting them in flow communication with the receiver or reservoir. In a specific form, the passageway can be formed between the barrel and a sleeve or collar surrounding the barrel which is rotationally slidable on the barrel. The valving member can be in the form of an elliptical ring on the inner surface of the sleeve or collar in sealing sliding engagement with the barrel outer surface, the ports of two of the other chambers falling between the longitudinal extents of the elliptical ring; and the center of the elliptical ring being located between the two ports. Rotation of the sleeve to a position placing the ring between the port vents one port while placing the other in flow communication with the nozzle, and rotation of the sleeve 90* one way or the other vents both ports or places both in flow communication with the nozzle to increase or decrease the liquid handling capacity of the device depending on the direction of rotation.

Claims

1. A variable capacity measuring and dispensing device for a liquid, comprising a body having a plurality of separate fluid holding chambers each having a port therein, reservoir means carried by said device and in communication with said chambers in said body for receiving and holding a measured volume of said liquid, a connecting passage having a vented end and connecting said ports in generally linear flow communication between the vented end and the reservoir means, means for selectively delivering fluid into and from each chamber, and operable means for selecting one or more chambers to be filled with said fluid and for selectively blocking the flow of said fluid to the nonselected chambers and for venting the nonselected chambers whereby only selected chambers are filled with said fluid which draws an equal measured volume of liquid into the reservoir means by operation of the delivering means, said operable means for blocking said fluid flow including a movable sealing member mounted for movement from a position sealing the vented end from all ports whereby all chambers are filled with said fluid which draws a measured volume of liquid into the reservoir means by said delivering means, to positions intermediate adjacent ports in said connecting passage whereby nonselected chambers are vented through said vented end and only selected chamber ports receive said fluid through said passage which draws an equal volume of said liquid into said reservoir means.

2. The device of claim 1, wherein said operable means includes means retaining said blocking means against movement to a position between the reservoir means and one of the chamber ports communicating with said passageway.

3. A variable capacity measuring and dispensing device for a liquid, comprising a stepped barrel having a plurality of separate fluid-holding cylinders approximately of equal length and formed as a linear array in order of decreasing diameter and volume in said barrel, means for selectively delivering fluid into and from each cylinder, including displacement means mounted for concurrent movement within said cylinders, said displacement means being in the form of a common stepped piston movable between a retracted position and a discharge position and having a discharge or displacement element properly sized for each cylinder with the discharge element for each cylinder positioned in the next larger cylinder while the piston is in a retracted position and including a port for each cylinder extending through the sidewall of the barrel, reservoir means carried by said device and in communication with said cylinders in said barrel, said reservoir means receiving and holding a measured volume of said liquid, and operable means including means for selecting one or more cylinders to be filled with said fluid and for selectively blocking the flow of said fluid to the nonselected cylinders and for venting the nonselected cylinders whereby only selected cylinders are filled with said fluid which draws an equal measured volume of liquid into said reservoir means by operation of the delivering means, and said operable means includes means for selectively connecting each of a plurality of said ports to said reservoir means or venting to atmosphere for varying the number of cylinders filled with fluid as said reservoir means is filled with an equal volume of liquid thereby varying the capacity of the device.

4. The device of claim 3, wherein said operable means comprises means mounted on the outer surface of the barrel for movement between a plurality of selectable positions, each representing a different volume or capacity for the device and including sealing means on the inner surface of said mounted means for sealing a different number of said ports upon movement to each selected position.

5. The device of claim 4, where said mounted means comprises a collar surrounding the barrel over said ports.

6. The device of claim 5, wherein said collar is mounted for rotary sliding movement of the outer surface of said barrel.

7. The device of claim 6, wherein the sealing means comprises an elliptical sealing ring secured to the inside of said collar in slidable sealing contact with the outer surface of said barrel and wherein two of said ports for two adjacent chambers are spaced from each other along the length of said barrel, the upper and lower expanse of said ring along the length of the barrel being above and below said two ports and the center of the extent of said ring along the length of the barrel being between said two ports, whereby rotation of the sleeve to position the center of the ring between the two ports communicates the upper port with the upper portion of the passageway between the collar and barrel and communicates the lower port with the lower portion of the passageway between the collar and barrel while rotation from said center position 90* in one direction communicates both ports with the lower portion of the passageway and rotation of the sleeve 90* from the center position in the other direction communicates both ports with the upper portion of the passageway.

8. The device of claim 7, wherein at least one of the plurality of chambers has its port disposed below the lowermost extend of the ring and said reservoir means is in direct flow communication with said lower chamber.

9. The device of claim 7, wherein said reservoir means is a nozzle on said sleeve in flow communication with the passageway between the collar and barrel above the uppermost expanse of said sealing means, and said plurality of chambers includes a chamber having its port communicating with the passageway above the uppermost extent of said sealing ring and of larger volume than the next lower chamber, and means sealing the end of the passageway beyond the nozzle and chamber outlet.

10. A variably capacity pipette for measuring and dispensing a liquid comprising a body having a plurality of fluid chambers therein, a movable plunger having a plurality of fluid displacement means respectively disposed for fluid displacement movement in said chambers, a reservoir for holding and dispensing said liquid, passage means for establishing fluid communication between said reservoir and said chambers, and selectively operable sealing means in said passage means, said sealing means being movable to a first position wherein one of said chambers is in fluid communication with said reservoir and a second position wherein plural chambers are in fluid communication with said reservoir thereby to selectively vary the effective number of said chambers in fluid communication with said reservoir to vary the volume of liquid drawn into and dispensed from said reservoir.

11. The pipette according to claim 10, wherein said plurality of chambers are disposed in a linear array and said displacement means are disposed in a linear array.

12. The pipette according to claim 11, wherein said displacement means are rigidly connected together.

13. The pipette according to claim 11, wherein said plurality of displacement means are of different fluid displacement sizes.

14. The pipette according to claim 11, wherein said displacement means comprises interconnected coaxial piston means of different diameters, and said fluid is air.

15. The pipette according to claim 14, wherein at least one of said piston means is movable in more than one of said chambers and all of said piston means are concurrently movable.

16. The pipette according to claim 15, wherein each of said chambers comprises a cylindrical bore having a stationary sealing ring for each of said pistons means.

17. The pipette according to claim 10, wherein said plunger is movable a predetermined distance to effect the drawing in of a predetermined volume of liquid into said reservoir when said sealing means is in said first position, and said plunger is movable said same predetermined distance when said sealing means is in said second position to effect the drawing in of a volume of liquid into said reservoir which is different than said predetermined volume, said fluid chambers are substantially coaxial, and said plurality of fluid displacement means are substantially coaxial.

18. The pipette according to claim 17, wherein said passage means has an end vented to atmosphere, said sealing means when in said first position venting to atmosphere and sealing from fluid communication with said reservoir all of said chambers except said one chamber, said sealing means when in said second position sealing said plural chambers from atmosphere.

19. The pipette according to claim 18, wherein said chambers comprise a plurality of cylinders in a linear array, and said plurality of displacement means comprise a plurality of pistons of different sizes rigidly connected together in a linear array.