EP0399118A1 - Mécanisme de pompage - Google Patents

Mécanisme de pompage Download PDF

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Publication number
EP0399118A1
EP0399118A1 EP89307675A EP89307675A EP0399118A1 EP 0399118 A1 EP0399118 A1 EP 0399118A1 EP 89307675 A EP89307675 A EP 89307675A EP 89307675 A EP89307675 A EP 89307675A EP 0399118 A1 EP0399118 A1 EP 0399118A1
Authority
EP
European Patent Office
Prior art keywords
fingers
tube
cam lobes
pumping mechanism
round shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89307675A
Other languages
German (de)
English (en)
Inventor
Charles R. Botts
David E. Kaplan
David Burkett
Laurence Warden
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imed Corp
Original Assignee
Imed Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imed Corp filed Critical Imed Corp
Publication of EP0399118A1 publication Critical patent/EP0399118A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B43/00—Machines, pumps, or pumping installations having flexible working members
    • F04B43/08—Machines, pumps, or pumping installations having flexible working members having tubular flexible members
    • F04B43/082—Machines, pumps, or pumping installations having flexible working members having tubular flexible members 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

Definitions

  • This invention relates generally to pumping mechanisms. More specifically, the present invention relates to linear peristaltic pumping mechanisms, and, in particular, to a linear peristaltic pump which can be assembled by snapping together its various components. This invention is particularly, but not exclusively, suited for assembling a linear peristaltic mechanism used for the infusion of medical solutions to a patient.
  • Peristaltic pumps have been used in the medical industry for many years to infuse intravenous (I.V.) fluids into patients.
  • the general principles of the operation for peristaltic pumps are common to both rotary and linear peristaltic pumps.
  • the objective is to create a moving zone of occlusion along a resilient tube for the purpose of pumping fluid through the tube.
  • the many diverse ways in which this objective is accomplished is manifested in the wide variety of types of peristaltic pumps.
  • peristaltic pumps include a pumping mechanism which is an assembly of many different components made from many different materials. As expected, the complexity of the interaction of these components increases with the sophistication of the pumps. Accordingly, this causes a corresponding increase in the difficulty of assembling the pump.
  • this difficulty is caused by the need for precise interaction of the pump's components. Additionally, the difficulty stems from the need to assemble a large number of parts. The main problem, however, at least insofar as manufacture and assembly is concerned, turns on how best to attach or connect the pump's individual components with acceptable precision.
  • the tube is placed between a platen and a series of occlusion members, such as fingers.
  • the series of finger are sequentially pressed against the resilient tube to provide a wavelike occlusion action for smoothly urging fluid through the tube.
  • a problem with linear peristaltic pumps exists when the occlusion members pressing on the tube cause a short term deformation of the tube, and periodically allow pressure to be built up within the tube. This results in a pulsatile flow of fluid through the tube, rather than linear flow as desired.
  • Some of the problems associated with a pulsatile flow of fluid can be alleviated by increasing the number of fingers making sequential contact with the tube. It has been found that the flow of fluid through a linear peristaltic pump becomes increasingly linear in nature when the number of fingers exceeds eight. For practical purposes, it has been found that the number of fingers should range between eleven and fourteen to obtain the optimal linear effect.
  • the present invention further recognizes that while unwanted increases in pressure can result from two simultaneous points of occlusion on the tube, other external problems can cause the resilient tube to become pressurized. Therefore, it would be further beneficial to monitor the pressure inside the tube to detect any excessive pressure therein.
  • a pumping mechanism for pumping fluid through a resilient tube to a patient by rotating interconnected cam lobes to establish sequential urging of a plurality of fingers against the tube
  • said pumping mechanism comprising: a support; a round shaft fixedly mounted on said support for receiving said interconnected cam lobes so that said inter­connected cam lobes can be coaxially aligned with said fixed round shaft for rotation about said fixed round shaft; and means for selectively reciprocating said fingers against said tube by rotation of said interconnected cam lobes about said fixed round shaft.
  • a pumping mechanism for pumping fluid through a resilient tube
  • said pumping mechanism comprising: a support; a plurality of fingers; a round shaft fixedly mounted on said support; a plurality of interconnected cam lobes coaxially aligned for rotation on said fixed round shaft, each of said cam lobes being operatively engaged with one of said fingers; a finger guide for restraining said respective fingers to reciprocal linear movement along substantially parallel paths; means for biasing said fingers against said tube; and a motor for rotating said cam lobes to sequentially reciprocate said fingers against said tube to create a moving zone of occlusion along said tube.
  • a method for assembling a peristaltic pump which moves fluid through a tube comprising the steps of:
  • a preferred embodiment of the snap-together linear peristaltic pump includes a housing and a support which couple together to create a cavity for holding a peristaltic drive mechanism.
  • the peristaltic drive mechanism may comprise a plurality of fingers which sequentially urge against a resilient tube in wavelike fashion to create a moving zone of occlusion along the tube to pump I.V. fluid from an I.V. source to a patient.
  • the plurality of fingers may be reciprocally moved by cam lobes which are coaxially aligned on a round shaft.
  • the cam lobes may have key segments so that when they are assembled together along the round shaft, the cam lobes are arranged in a helical manner for operative engagement with the plurality of fingers.
  • the interconnected cam lobes may be rotated by an external motor about the round shaft which is fixedly held at both ends.
  • a special key segment may be provided on two preselected cam lobes which may be shaped to reduce pulsatile flow to ensure the preselected cam lobes are properly coupled together at the proper position on the round shaft.
  • a pressure transducer may be operatively connected to the resilient tube for detecting unusually high pressures inside the tube.
  • the motor may be connected to a programmable controller for varying the speed of infusion of I.V. fluid to a patient.
  • an encoder wheel may be carried on the round shaft with the cam lobes to detect the position of the fingers by an associated light sensing mechanism. The encoded wheel and its associated light sensing mechanism may be provided to ensure that a specified finger occludes the tube at a predetermined point when the pump is stopped in order to prevent any undesired flow of fluid to or from a patient.
  • an advantage of the present invention provides a linear peristaltic pump whose components can generally be assembled in a snap-together manner. Additionally, an advantage of the present invention is that it provides a linear peristaltic pump which reduces the surging of liquid caused when there are two simultaneous points of occlusion on a resilient tube. Still further, an advantage of the present invention is that it provides a pressure transducer to detect pressure inside the resilient tube. Another advantage of the present invention is that it provides a linear peristaltic pump which occludes the tube at a predetermined point when the pump is turned off for stopping the flow of fluid to or from a patient. Yet another advantage of the present invention is that it provides a linear peristaltic pump which is cost effective, reliable, and accurate. Finally, an advantage of the present invention is that it provides a linear peristaltic pump which is durable and easily serviced and maintained.
  • a linear peristaltic pump generally designated 10 is shown in its intended environment.
  • the pump 10 is mounted on I.V. pole 12 in a manner well known in the art.
  • An I.V. fluid source 14 is suspended from the I.V. pole 12, and an I.V. tube 16 is connected in fluid communication with fluid source 14 for operative connection with pump 10 in a manner as generally illustrated in Figure 1.
  • I.V. tube 16 Downstream from its point of operative connection with pump 10, I.V. tube 16 is coupled with patient 20 for the infusion of medical solutions to the patient 20.
  • FIG. 2 is a perspective exploded view of the pumping mechanism, generally designated 18, which is shown here in isolation from pump 10 for purposes of clarity. It should be understood that the order in which components of pumping mechanism 18 are assembled may vary. In the preferred embodiment, however, a motor 22 is initially assembled with its corresponding harness 26.
  • the motor 22 is preferably a variable speed motor, such as a stepper motor.
  • Harness 26 comprises a plurality of wires which are electrically engaged to a connector 28. Connector 28 is subsequently electrically coupled to a programmable controller (not shown) which controls the rate of motor 22.
  • Motor 22 is equipped with a cylindrical-­shaped motor shaft 24.
  • Motor shaft 24 is engageable with a motor coupling 30 which is used to rotate the internal moving parts of the pumping mechanism 18.
  • Motor coupling 30 comprises a plurality of teeth 31 which can be secured to a drive shaft coupling 32.
  • Motor coupling 30 is preferably made of an elastic material, such as silicone.
  • the drive shaft coupling 32 has a tube 33 extending therefrom for engagement with corresponding rotating members of pumping mechanism 18 as will be further discussed below. Attached to the circumference of tube 33 is a washer 34 which forms a slot 36 between the washer 34 and the drive shaft coupling 32. Slot 36 is used to hold the moving parts of pumping mechanism 18 in place, as will be further discussed below.
  • a round shaft 40 engageable with a plurality of cam lobes generally designated 41.
  • Each cam lobe 41 has a cam lobe surface and an interior receiving hole 43 for receiving round shaft 40.
  • cam lobes 41 are integrally formed together in pairs, as dual cam lobes 42 for enabling easier assembly of the pump 10.
  • Dual cam lobes 42 are snappingly engageable with each other having key segments such that upon complete engagement along the round shaft 40, the interconnected dual cam lobes 42 are helically oriented along a common longitudinal axis, coaxial with the axis of the longitudinal axis of the round shaft 40.
  • a set of corresponding number of dual cam lobes 42 can be connected together on a round shaft 40.
  • Cam lobe 44 is integrally formed with a spacer 45, and is associated with the ninth finger 60 c .
  • Cam lobe 46 is integrally formed with a spacer 47, and is associated with tenth finger 60 d .
  • Cam lobe 48 is a special dual cam lobe associated with the penultimate and ultimate (eleventh and twelfth) fingers 60 e , 60 f , respectively.
  • a special key segment 52 is provided to ensure that during assembly, while the dual cam lobes 42 are allowed to interconnect with each other as well as with cam lobe 44, dual cam lobes 42 are not allowed to interconnect with special dual cam lobe 48.
  • key 52 permits only special dual cam lobe 48 to be connected to cam lobe 46.
  • an encoder wheel 50 is held between the spacer 45 and spacer 47.
  • Encoder wheel 50 has a short hole 54 and a long hole 56. The purpose of encoder wheel 50 is to indicate the rotational position of the shaft to a programmable controller as more fully discussed below.
  • the plurality of fingers 60 are operatively coupled to the appropriate cam lobe 41.
  • the interconnection between fingers 60 and a finger guide 62 can be readily appreciated.
  • Finger guide 62 has a plurality of ribs 64 formed thereon to create a plurality of slots 66.
  • Finger guide 62 also has a notch 71 formed thereon which provides clearance for the encoder wheel 50 and a pressure sensing mechanism as will be subsequently discussed.
  • shoes 68 a and 68 b are formed onto finger guide 62 for attachment to sleeves 69 a and 69 b which are formed within support 70.
  • a finger 60 comprises an aperture 58 for operative engagement with its corresponding cam lobe 41. Additionally, an opening 124 is provided in each finger 60 for receiving the finger guide 62. Further, finger 60 includes an upper guide 126 and a lower guide 128 for sliding engagement with ribs 64 and slots 66 of finger guide 62. Finger 60 also has an edge 130 formed on the outer surface of the finger 60 to enable sliding engagement with the walls of cavity 94 of support 70. Additionally, for ensuring there is proper engagement between each finger 60 and tube 16, a blade 132 is formed onto finger 60 such that tube 16 is occluded upon complete engagement of finger 60 with the tube, which is typically held in place against a platen (not shown).
  • a support 70 having a flexible membrane bottom (not shown).
  • a bottle side bearing block 72 fixedly holds one end of round shaft 40, and on the patient side of support 70, a patient side bearing block 74 fixedly holds the other end of round shaft 40 so that the shaft does not rotate about its longitudinal axis.
  • inter-connected cam lobes 41 are rotatably engaged to a bearing 76 a and a bearing 76 b which are contained within bearing blocks 72 and 74, respectively.
  • Bottle side bearing block 72 and patient side bearing block 74 each have a pivot slot 82 a and 82 b , respectively, formed thereon for pivotally connecting the bearing blocks 72 and 74 at pivot tower 80 a and pivot tower 80 b .
  • a spring interconnection between bearing blocks 72, 74 and support 70 is provided by bias elements such as springs 84 a and 84 b attached to bearing block hooks 86 a and 86 b at one end of each spring; and to support hooks 88 a and 88 b at the other end of each spring.
  • the engaged springs 84 a and 84 b provide a mechanism for biasing the plurality of fingers against the flexible membrane bottom of support 70, and thus against the tube.
  • Top housing 90 is threadably connected to bearing blocks 72 and 74 by a plurality of screws 92. With top housing 90 connected to bearing blocks 72 and 74, a closed cavity is formed inside top housing 90 and support 70. When top housing 90 and support 70 form closed cavity 94, the plurality of cam lobes 41, round shaft 40, finger guide 62 and the plurality of fingers 60 are held therein to comprise the pumping mechanism 18.
  • Motor 22 is connected to a mounting block 96 having a double adhesive backed resilient foam pad (not shown) to reduce noise transmission.
  • Mounting block 96 also has a plurality of holes 98 formed therein for attachment to housing plate 100.
  • Motor 22, motor coupling 30 and drive shaft coupling 32 are connected to the plurality of interconnected cam lobes 41 when mounting block 96 is attached to plate 100.
  • Top housing 90 has a housing plug 112 formed therein for snapping engagement with an optical switch 102.
  • Optical switch 102 comprises a light emitter 104 and a light sensor 106.
  • a pressure transducer 114 is connected to tube 16.
  • the electrical signal of pressure transducer 114 is sent through a harness 116 to a connection 118 and sent to a programmable controller (not shown).
  • pressure transducer 114 supplies the necessary electrical signal to the programmable controller (not shown) which provides information to the operator.
  • a feature has been provided for pumping mechanism 18 to ensure that the position of the plurality of cam lobes 41 is maintained along the longitudinal axis of round shaft 40.
  • This feature includes a groove 122 formed within bearing block 74 for the engagement of an index key 120. It can be appreciated that upon engagement of index key 120 with groove 122, the index key 120 is placed inside slot 36 of drive shaft coupling 32. Washer 34 and drive shaft coupling 32 rotate about both sides of the index key 120 to ensure that the interconnected cam lobs 41 are fixedly held about the longitudinal axis of the round shaft 40.
  • round shaft 40 is fixedly held between bearing blocks 72 and 74.
  • the interconnected cam lobes 41 are coaxially aligned with respect to round shaft 40 for rotational engagement about round shaft 40.
  • fingers 60 reciprocally move within the closed cavity 94 so that the fingers 60 are urged against the tube 16 sequentially in wavelike fashion, to create a moving zone of occlusion along tube 16.
  • the pumping mechanism 18 reduces the pressure build up in the pocket by increasing the rate of lift off of the last and next to last fingers of the series, i.e. fingers 60 f and 60 e . It has been found, that if the next to last, or eleventh, finger 60 e is lifted off tube 16 at a rate faster than the downward reciprocal movement of subsequent occluding fingers 60, then less pressure is allowed to be built up inside the pocket. Further, when the last, or twelfth, finger 60 f is lifted off tube 16 at a rate faster than the other fingers 60, a build up of overall pressure inside the pocket is prevented.
  • the rate of lift off of the eleventh and twelfth fingers 60 e and 60 f from tube 16 can be increased by selectively forming the shape of cam lobe surfaces 41 of corresponding special dual cam lobe 48.
  • the duration of occlusion caused by the last, or twelfth, finger 60 f may be reduced further by shortening the dwell time of twelfth finger 60 f .
  • the corresponding cam lobe surface of special dual cam lobe 48 is selectively formed so that there is a shortened dwell time and thus shortened occlusion time of the twelfth finger 60 f is achieved.
  • linear peristaltic pump 10 includes a mechanism for selectively determining the location of the interconnected cam lobes 41 about the round shaft 40.
  • the sensing mechanism includes the optical switch 102 having light emitter 104 and light sensor 106.
  • Optical switch 102 is inserted into top housing 90 at the housing plug 112. When the optical switch 102 is engaged, clearance inside pump 10 is provided by the notch 71 on finger guide 62.
  • interconnected encoder wheel 50 rotates about the longitudinal axis of round shaft 40.
  • light emitter 104 is electrically activated
  • light sensor 106 intermittently detects the light from emitter 104 which passes through either short hole 52 or long hole 54.
  • An electrical signal representative of the position of the encoder wheel with respect to said holes 52, 54 is sent from light sensor 106 through cable 108 to connection 110 and subsequently to a programmable controller (not shown).
  • a programmable controller not shown
  • the speed of rotation of motor shaft 24 of motor 22 can further be regulated by a programmable controller (not shown).
  • a programmable controller (not shown) may be programmed to vary the rate of stepper motor 22.
  • pressure transducer 114 detects the internal pressure of tube 16 and accordingly sends pressure information through harness 116 to connection 118 which is electrically connected to a programmable controller (not shown). By knowing the pressure of tube 16, the programmable controller (not shown) can safely operate the pump 10 and ensure that the pressure within tube 16 does not become excessive.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Infusion, Injection, And Reservoir Apparatuses (AREA)
EP89307675A 1989-05-23 1989-07-27 Mécanisme de pompage Withdrawn EP0399118A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US35565989A 1989-05-23 1989-05-23
US355659 1989-05-23

Publications (1)

Publication Number Publication Date
EP0399118A1 true EP0399118A1 (fr) 1990-11-28

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ID=23398295

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89307675A Withdrawn EP0399118A1 (fr) 1989-05-23 1989-07-27 Mécanisme de pompage

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EP (1) EP0399118A1 (fr)
JP (1) JPH034873A (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217355A (en) * 1991-08-05 1993-06-08 Imed Corporation Two-cycle peristaltic pump with occlusion detector

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4755109A (en) * 1987-04-03 1988-07-05 Fisher Scientific Company Inc. Snap-together peristaltic mechanism
EP0283614A1 (fr) * 1987-02-24 1988-09-28 Imed Corporation Dispositif pour pomper des liquides au travers d'un tuyau

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0283614A1 (fr) * 1987-02-24 1988-09-28 Imed Corporation Dispositif pour pomper des liquides au travers d'un tuyau
US4755109A (en) * 1987-04-03 1988-07-05 Fisher Scientific Company Inc. Snap-together peristaltic mechanism

Also Published As

Publication number Publication date
JPH034873A (ja) 1991-01-10

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