Volumetric pump tube reshaper and method

• US 5,322,422 A
• Filed: 02/01/1993
• Issued: 06/21/1994
• Est. Priority Date: 03/15/1990
• Status: Expired due to Fees

• Current Assignee: Hospira Incorporated (Pfizer Inc.)
• Original Assignee: Abbott Laboratories
• Inventors: Lawless, Michael W., Natwick, Vernon R.
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): KORYTNYK, PETER G
• Application Number:
  US08/011,891
• Time in Patent Office: 505 Days
• Field of Search: 417/474-478, 604/153
• US Class Current: 417/474
• CPC Class Codes: A61M 2205/128 with incorporated valves
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 5/14228 with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
• CPC Class Codes: F04B 43/08 having tubular flexible members F04B43/12 takes precedence
• CPC Class Codes: F04B 43/082 the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism
• CPC Class Codes: F04B 43/123 using an excenter as the squeezing element
• CPC Class Codes: F04B 9/042 the means being cams
• CPC Class Codes: F16H 25/08 for interconverting rotary motion and reciprocating motion F16H23/00 takes precedence
• CPC Class Codes: F16H 53/06 Cam-followers F16H53/08 takes precedence
• CPC Class Codes: Y10T 74/18288 Cam and lever
• CPC Class Codes: Y10T 74/18296 Cam and slide
• CPC Class Codes: Y10T 74/2104 Flexible strip
• CPC Class Codes: Y10T 74/2107 Follower

Abstract

A volumetric pump and method for displacing a predetermined quantity of fluid at a predefined cracking pressure, independent of supply and output pressures. The volumetric pump (30) includes an inlet cracking valve (46), an outlet cracking valve (52), and a plunger (48)for displacing fluid from a pumping portion (34b) of flexible tubing (34) that extends through the volumetric pump. The pumping portion of the flexible tube fills with liquid when the inlet cracking valve is fully opened and is urged to expand by jaws (236) on pivotally-mounted arms (234). The arms are forced to pivot, as tubing reshaper rollers (160), disposed on the plunger, roll along the inner surface (232) of each arm. During a pumpback-pressurization segment of the pumping cycle, the inlet cracking valve applies a cracking force to the flexible tubing, while the plunger compresses the pumping portion of the flexible tubing sufficiently to develop a cracking pressure that displaces excess fluid back through the inlet cracking valve toward a container (32). After the excess fluid has been forced from the pumping portion of the flexible tubing, a pumping segment of the cycle begins, wherein the inlet cracking valve closes fully and the outlet cracking valve applies a cracking force to compress the flexible tubing. Fluid is then forced by the plunger from the pumping portion of the flexible tubing into a distal portion (34c). The volumetric pump compensates for variations in elasticity of the flexible tubing that would otherwise cause variations in the cracking pressure, using balance blocks (42 and 58).

Claims

1. Apparatus for compressing and shaping a flexible tube, comprising:

a. single plunger means, mounted to move bidirectionally along a reciprocation axis, for periodically alternately compressing a segment of the flexible tube to displace a fluid from an interior passage disposed within the flexible tube, and then allowing the flexible tube to expand to at least a partially uncompressed condition;

b. drive means, for periodically driving the plunger means to move along the reciprocation axis; and

c. tube reshaper means, actuated by the motion of the plunger means, for applying a reshaping force transversely against substantially the same segment of the flexible tube that was compressed, the reshaping force tending to expand the interior passage to a maximum desired volume.

2. The apparatus of claim 1, wherein the tube reshaper means comprise;

a. a pair of arms, pivotally mounted on opposite sides of the plunger means;

b. jaws disposed on the arms at each side of a segment of the flexible tube that is compressed by the plunger means; and

c. a pair of rollers disposed on opposite sides of the plunger means, said rollers transmitting the reshaping force from the plunger means to the pivotally-mounted arms, so that the interior passage is expanded by the jaws in synchronization, as the plunger means retract from a position of maximum compression of the flexible tube.

3. The apparatus of claim 2, wherein the pair of rollers are mounted on the plunger means and roll along facing surfaces of the pair of arms.

4. The apparatus of claim 1, wherein the drive means comprise a cam rotatably driven by a motor.

5. The apparatus of claim 4, wherein the plunger means comprise a plunger that is spring biased into contact with the cam, said plunger having a longitudinally extending surface that contacts the flexible tube along a segment thereof, while compressing it, said longitudinally extending surface being substantially parallel to the segment of the flexible tube that it contacts.

6. A method of compressing and reshaping a flexible tube to repeatedly displace a desired volume of fluid from an interior passage disposed within the flexible tube, comprising the steps of:

a. forcing a longitudinally extending surface of a single plunger, which is mounted to move bidirectionally along a reciprocation axis, against a segment of the tube to compress the segment of the tube, the longitudinally extending surface being substantially parallel to the segment of the tube being compressed;

b. retracting the plunger away from the tube to remove the compressive force on the tube along the reciprocation axis; and

c. reshaping the flexible tube by forcing at least one reshaper jaw against at least one side of the tube in a direction substantially perpendicular to the reciprocation axis along substantially the same segment of the tube to which the compressive force was applied, such that the interior passage of the tube expands.

7. The method of claim 6, wherein the step of reshaping is accomplished with a pair of reshaper jaws mounted on opposite sides of the plunger such that the jaws move together to place opposing forces against opposite sides of the tube in response to the plunger being retracted away from the tube.

8. An apparatus for repeatedly compressing and shaping a flexible tube having an interior passage, comprising:

a. a frame for holding a portion of the flexible tube;

b. a single plunger coupled to the frame so as to be disposed opposite at least one side of a segment of the flexible tube;

c. plunger drive means coupled to the plunger for repeatedly moving the plunger into and out of compression against a segment of the flexible tube;

d. at least one jaw member disposed along substantially the same segment of the flexible tube as the plunger, the at least one jaw member being positioned to apply a compressive force to at least one side of the flexible tube in a direction generally transverse to the direction of plunger movement; and

e. jaw member drive means coupled to the at least one jaw member for repeatedly moving the at least one jaw member into and out of compression against at least one side of the same segment of the flexible tube, the at least one jaw member expanding the interior passage when in a position of compression with the tube.

9. The apparatus of claim 8, wherein the jaw member drive means is actuated by the motion of the plunger so that the at least one jaw member is caused to push against the tube when the plunger is moved out of compression with the tube, and so that the at least one jaw member is caused to move away from the tube when the plunger is moved into compression with the tube.

10. The apparatus of claim 9, wherein the at least one jaw member comprises a pair of jaws disposed on each side of a segment of the flexible tube that is compressed by the plunger, and wherein the jaw member drive means comprise:

a. a pair of arms, pivotally mounted on opposite sides of the plunger; and

b. a pair of rollers disposed on opposite sides of the plunger, said rollers transmitting the compressive force from the plunger to the pivotally-mounted arms, so that the interior passage is expanded by the jaws in synchronization, as the plunger retracts from a position of maximum compression of the flexible tube.

11. The apparatus of claim 10, wherein the pair of rollers are mounted on the plunger and roll along facing surfaces of the pair of arms.

12. The apparatus of claim 10, wherein the pair of rollers are mounted on the pair of arms and roll along facing surfaces of the plunger.

13. The apparatus of claim 8, wherein the plunger drive means comprise a cam rotatably driven by a motor, and wherein the plunger is spring biased into contact with the cam, said plunger having a longitudinally-extending surface that contacts the flexible tube along a segment thereof, while compressing it.

14. A single-plunger fluid pump for repeatably compressing and shaping a flexible tube having an interior passage, comprising:

a. a frame for holding a portion of the flexible tube;

b. a single plunger coupled to the frame so as to be disposed opposite at least one side of a segment of the flexible tube, said plunger having a longitudinal surface;

c. plunger drive means coupled to the plunger for repeatably moving the longitudinal surface of the plunger into and out of compression against a segment of the flexible tube;

d. at least one jaw member disposed along substantially the same segment of the flexible tube as the longitudinal surface of the plunger, said at least one jaw member being positioned to apply a compressive force to at least one side of the flexible tube in a direction generally transverse to the direction of plunger movement; and

e. jaw member drive means coupled to said at least one jaw member for repeatedly moving said at least one jaw member into and out of compression against at least one side of the same segment of the flexible tube, said at least one jaw member expanding the interior passage when in a position to compress the tube.

15. The single-plunger fluid pump of claim 14, further comprising means to adjust the range of movement of said at least one jaw member for proper expansion of the interior passage of the tube.