US3766784A - Pipettor stroke control mechanism - Google Patents

Pipettor stroke control mechanism Download PDF

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Publication number
US3766784A
US3766784A US00153692A US15369271A US3766784A US 3766784 A US3766784 A US 3766784A US 00153692 A US00153692 A US 00153692A US 15369271 A US15369271 A US 15369271A US 3766784 A US3766784 A US 3766784A
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United States
Prior art keywords
fingers
cam
indexing member
indexing
piston
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Expired - Lifetime
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US00153692A
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English (en)
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C Walker
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Sherwood Medical Co
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Sherwood Medical Industries Inc
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Priority to US00153692A priority Critical patent/US3766784A/en
Priority to CA140,423A priority patent/CA954836A/en
Priority to DE2227731A priority patent/DE2227731C3/de
Priority to GB2839272A priority patent/GB1389269A/en
Application granted granted Critical
Publication of US3766784A publication Critical patent/US3766784A/en
Assigned to SHERWOOD MEDICAL COMPANY reassignment SHERWOOD MEDICAL COMPANY MERGER (SEE DOCUMENT FOR DETAILS). Assignors: SHERWOOD MEDICAL INDUSTRIES INC. (INTO)
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/90—Separation; Purification
    • C01B17/907—Removal of arsenic
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150015—Source of blood
    • A61B5/150022—Source of blood for capillary blood or interstitial fluid
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150053—Details for enhanced collection of blood or interstitial fluid at the sample site, e.g. by applying compression, heat, vibration, ultrasound, suction or vacuum to tissue; for reduction of pain or discomfort; Skin piercing elements, e.g. blades, needles, lancets or canulas, with adjustable piercing speed
    • A61B5/150061—Means for enhancing collection
    • A61B5/150099—Means for enhancing collection by negative pressure, other than vacuum extraction into a syringe by pulling on the piston rod or into pre-evacuated tubes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150206—Construction or design features not otherwise provided for; manufacturing or production; packages; sterilisation of piercing element, piercing device or sampling device
    • A61B5/150213—Venting means
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150206—Construction or design features not otherwise provided for; manufacturing or production; packages; sterilisation of piercing element, piercing device or sampling device
    • A61B5/150236—Pistons, i.e. cylindrical bodies that sit inside the syringe barrel, typically with an air tight seal, and slide in the barrel to create a vacuum or to expel blood
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150206—Construction or design features not otherwise provided for; manufacturing or production; packages; sterilisation of piercing element, piercing device or sampling device
    • A61B5/150244—Rods for actuating or driving the piston, i.e. the cylindrical body that sits inside the syringe barrel, typically with an air tight seal, and slides in the barrel to create a vacuum or to expel blood
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150206—Construction or design features not otherwise provided for; manufacturing or production; packages; sterilisation of piercing element, piercing device or sampling device
    • A61B5/150259—Improved gripping, e.g. with high friction pattern or projections on the housing surface or an ergonometric shape
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/15—Devices for taking samples of blood
    • A61B5/150007—Details
    • A61B5/150343—Collection vessels for collecting blood samples from the skin surface, e.g. test tubes, cuvettes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/32—Needles; Details of needles pertaining to their connection with syringe or hub; Accessories for bringing the needle into, or holding the needle on, the body; Devices for protection of needles
    • A61M5/34—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub
    • A61M5/344—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub using additional parts, e.g. clamping rings or collets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
    • B01L3/02—Burettes; Pipettes
    • B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
    • B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type
    • B01L3/0224—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type having mechanical means to set stroke length, e.g. movable stops
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F11/00—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it
    • G01F11/02—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement
    • G01F11/021—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement of the piston type
    • G01F11/023—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement of the piston type with provision for varying the stroke of the piston
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F11/00—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it
    • G01F11/02—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement
    • G01F11/021—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement of the piston type
    • G01F11/025—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement of the piston type with manually operated pistons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31525—Dosing
    • A61M5/31531—Microsyringes, e.g. having piston bore diameter close or equal to needle shaft diameter
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/32—Needles; Details of needles pertaining to their connection with syringe or hub; Accessories for bringing the needle into, or holding the needle on, the body; Devices for protection of needles
    • A61M5/34—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub
    • A61M5/346—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub friction fit
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/32—Needles; Details of needles pertaining to their connection with syringe or hub; Accessories for bringing the needle into, or holding the needle on, the body; Devices for protection of needles
    • A61M5/34—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub
    • A61M5/347—Constructions for connecting the needle, e.g. to syringe nozzle or needle hub rotatable, e.g. bayonet or screw
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L2200/00—Solutions for specific problems relating to chemical or physical laboratory apparatus
    • B01L2200/04—Exchange or ejection of cartridges, containers or reservoirs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L2300/00—Additional constructional details
    • B01L2300/08—Geometry, shape and general structure
    • B01L2300/0832—Geometry, shape and general structure cylindrical, tube shaped
    • B01L2300/0838—Capillaries

Definitions

  • a problem associated with pipettes is that all of the liquid drawn in on the intake stroke is not dispensed by the piston during the discharge stroke, leaving small amounts of liquid within the pipette barrel which, of course, detracts from the accuracy of any analytical measurements being made using the pipette. This is a particularly difficult problem in those pipettes which draw the liquid into a disposable reservoir, or nozzle tip, rather than directly into the pipette barrel, thereby eliminating cross-contamination on successive operations of the pipette.
  • a transfer fluid air
  • the use of an air interface between the liquid and the internal parts of the pipette prevents crosscontamination, but also decreases displacement accuracy due to the compressibility of the air in the system.
  • indexing members transfer the entire actuating force from the pushbutton to the piston and thus must be constructed of materials and designed to carry the full actuating loads,thereby complicating the devices and rendering them prone to wear, loss ofaccuracy and failure.
  • a stroke control mechanism for a pipette to produce alternate long and short strokes of the'pipette piston to assure complete fluid discharge from the pipette, with the stroke control mechanism providing smooth and positive indexing of short and long stops into engagement with one or more abutments.
  • the indexing mechanism transfers none of the load from the manual pushbutton actuator to the piston so'that the indexing or stroke control mechanism operates more smoothly and may be less expensively constructed than if load bearmg.
  • the pipette consists of a barrel having a rigid piston assembly therein with the pushbutton connected to one end of the piston assembly. In this manner there is no lost motion between the pushbutton and the fluid piston thereby permitting more accurate control of the stroke length of the piston, and allowing the stroke control mechanism to be non-load bearing, except for its own frictional resistance.
  • annular indexing sleeve is provided on the piston having high and low stops that selectively engage abutments within the pipette barrel.
  • opposed sets of flexible axial, cantilevered fingers are provided on the indexing member. Each set of fingers is out of phase with the other set and they engage two cams within the barrel having leading cam surfaces disposedso that the indexing member indexes equal incremental movements on each intakeand each discharge stroke of the piston assembly. It should be understood, of course, that the camming surfaces may be reversed by placing the fingers on the barrel and the cams on the sleeve.
  • the opposed sets of fingers are flexible and are spaced sufficiently close to one another so that they encapsulate each cam as they ride over it providing positive indexing of the indexible member. Moreover, the opposed sets of fingers aresufficiently close circumferentially with respect to the circumferential length of the cams such that at the end of movement of the piston mechanism in one direction, the-indexing member will be rotated sufficiently so that the lagging opposed finger will be in alignment with its cam surface, thus assuring continued indexing in the same direction upon movement of the piston assembly in the opposite direction.
  • a fine stroke adjustment is provieed by varying the position of the pushbutton relative to thepiston-assembly,-the pushbutton acting as a stop for one direction of movement for the indexing member which in turn acts as a stop for the piston assembly. Movement in the other direction is arrested by positive engagement of abutting shoulders on the barrel and piston assembly.
  • the minimal total work means the operators hand will be less fatigued and he can maintain accurate control over a longer period of the working day.
  • Another advantage in the present construction is that the reduced forces in the stroke control mechanism minimize wear and the possibility of stress failure.
  • the camming surfaces for rotating the indexing member are not the stopping surfaces.
  • the stopping surfaces are flat and extend approximately 166 of the l80 available for each stroke.
  • the stopping construction employs the direct compression of a solid flange on the indexing member which is advantageous since most materials are strongest in compression.
  • the forward stopping forces are contained entirely in the pushbutton and the abutments within the housing without any stress being placed on the plunger or the fine stroke adjusting mechanism.
  • an axially movable sleeve is provided in the barrel carrying the cams and the abutments for theindexing member. This permits the indexing member and the cam and abutment sleeve to be used in a plurality of different pipettes having widely different stroke lengths, thereby standardizing parts and reducing mold costs.
  • FIG. 1 is a longitudinal section of a pipette assembly according to the present invention
  • FIG. 2 is a fragmentary view of the pipettebarrel with the cam and abutment sleeve inserted therein;
  • FIG. 3 is an enlarged fragmentary view of a portion of the indexing mechanism cooperating with the cam and abutment sleeve;
  • FIG. 4 is an unrolled schematic view of the indexing member in solid lines and the cam and abutment sleeve in dotted lines; v
  • FIGS. 5 and 6 are unrolled views similar to FIG. 4 with the indexing member rotated 45' further in each view;
  • FIG. 7 is a fragmentary section of a pipette assembly according to another embodiment of the present invention.
  • a pipette assembly 10 is illustrated consisting generally of a cylindrical barrel l2 slidably receiving a piston mechanism l4 actuated by a manual pushbutton 16 at the upper end thereof projecting from the barrel l2 and a disposable reservoir or nozzle tip ISattached to the lower end 20 of the barrel 12.
  • the operator depresses the pushbutton l6, inserts nozzle tip into a reservoir,
  • the piston or plunger portion 25 is slidably received in cylinder 39 barrel portion 41 defining a chamber 44. As piston 25 moves upwardly in the cylinder, air is drawn into chamber 44 through axial passages 46 and 47 and liquid is drawn into reservoir tip 15.
  • a piston assembly return spring 48 is provided in the upper end of the barrel l2, biased against the lower surface 49 of the pushbutton 16 urging flange 26 on plunger 24 into engagement with the shoulder 37, so that upon release of the pushbutton 16 the piston assembly 14 will always move to its upper position with piston 25 withdrawn in cylinder 39.
  • the indexing mechanism 22 provides alternate short and long strokes for the piston assembly 14. That is, the piston assembly 14 always retracts to the same position determined by shoulder 37 in engagement with flange 26. Upon initial depression of pushbutton 16 the indexing mechanism 22 permits the piston assembly 14 to move a predetermined distance. After release of the pushbutton l6 and upon subsequent depression the indexingmechanism 22 stops the piston assembly 14 at a different position.
  • the stroke control mechanism 22 effects alternate short and long strokes of the piston mechanism 14, which may, for example, differ by approximately one-eighth of an inch. In this manner discharge from chamber 44 of an excess of fluid over that taken in onthe previous stroke is assured.
  • the indexing mechanism 22 includes a cylindrical cam sleeve 51 seated on the barrel shoulder 37.
  • the cam sleeve 51 has a flange 52 serving as a spring retainer for spring 48.
  • the earns 53 have camming surfaces 54, 55, 56 and 57 with a truncated surface 59 to permit clearance for other parts as will appear'more clearly below.
  • Surfaces and 57 are parallel as are surfaces 54 and 56.
  • the cams 53 cooperate with an indexing member 60 to cause relative rotation therebetween as will appear more clearly hereinbelow.
  • Two projections 62, 63 project upwardly from the upper end of cam sleeve 51 adjacent the cams 53 and serve as abutments for stops on the indexing member 60.
  • the indexing member 60 is a plastic molding and includes a tubular portion 64 freely rotatablymounted on reduced shaft portion 30 of plunger 24'. Extending axially downward from the upper end of the .member 60 are four fingers'or, beams 66 having chamferred end surfaces 67 and 68. As seen in FIG. 6, these fingers 66 are cantilevered and are flexible in a circumferential direction. Another set of fingers 69 project upwardly from the lower end of member 60 and are of the same shape and flexure as the-upper fingers 66. There are four lower fingers 69, 69a, 69b, 69c and they are 45 out of phase with respect to the four fingers 66a, 66b 66c, 66d, asseen clearly in FIGS.
  • the stops 70 and 71 are formed on an annular ring portion 73 integral with the top end portion of indexing member 60.
  • the annular ring portion 73 extends radially outward from the fingers 66 so that the fingers may engage the earns 53 at the same time the stops 70 or 71 engage the abutments 62, 63, as best shown in FIG. 3.
  • the fingers 66 and 69 are spaced circumferentially a distance substantially equal to the circumferential length of the cam portions 55, 56, and are spaced axially a distance less than the axial length of one of the cam surfaces 55, 56.
  • the distance between the chamfers 68 on adjacent fingers 66 and the chamfers 75 on adjacent fingers 69 is less than the distance between the cam surfaces 54 and 56 so that the appropriate fingers 66 and 69 must spread slightly or bend as they ride over the cam surfaces 54 and 56 simultaneously.
  • fingers 66 have passed over point 77 on the cams and the fingers have returned to their unflexed positions.
  • the stroke volume may be adjusted by varying the position of pushbutton 16 with respect to the plunger portion 32.
  • the indexing member 60 is seated loosely between the bottom surface 49 of button l6 and shoulder 81 on guide portion 28 ofplunger 24.
  • Upper surface83 of the indexing member 60 is forced into engagement with the lower surface49 of the pushbutton 16 when the stops 70 or 71 engage abutments 62 and 63.
  • the lower limit of travel of piston 25 may be varied within certain limits. This, of course, does not affect thedifference in stroke length betweenthe intake stroke and the delivery stroke as determined by the stroke control mechanism 22.
  • the stroke control differential is controlled by the difference in height between stops 70 and 71.
  • a shoulder 85 is provided near the upper end of shaft portion that engages a counterbore 86 in the button 16 preventing this unwanted clamping.
  • the axial distance between shoulder 85 and shoulder 81 is greater than the sum of the axial length of member 60 and the axial depth of the bore 86.
  • a disposable nozzle tip 15 Prior to drawing liquid into the pipette 10, a disposable nozzle tip 15 is telescoped over tip 20.
  • the indexing member 60 is in its upper position shown in FIGS. 1 and 4.
  • fingers 66a and 66b ride down cam surfaces a and 55b which will start rotating the indexing member to the right as shown in FIG. 4.
  • both sets of fingers 66 and 69 will spread apart slightly and the fingers 69a and 69b will begin riding short cam surfaces 570 and 57b.
  • the flexing of fingers 66a and 66b and 69a and 69b under these conditions assures the positive rotation of indexing member 60 in only one direction.
  • the pipeete is then inserted in the reservoir of fluid and the pushbutton 16 is released slowly, drawing fluid into the reservoir of nozzle tip 15
  • the fingers 69a and 69b engage cam surfaces 56a and 56b and the resulting camrning action begins to rotate the indexing member 60 on shaft portion 30 again to the right.
  • the fingers 66c and'66d are released by cam corners 77 so that they are aligned with the beginning of cam surfaces 55a and 55b.
  • the continued upward movement of the plunger 14 and the index member 60 occurs without rotation of the index member with the fingers 69a and 69b merely riding axially along cam corners 94 and 95,. respectively.
  • FIG. 7 a somewhat modified form of the present invention is shown, differing basically from the construction shown in FIGS. 1 through 3 in that the cam sleeve is axially movable.
  • Pipette 110 is seen to include a barrel 112 having a plunger assembly 114 slidable therein and biased to its upper position by a spring 116.
  • the upper position of the piston assembly 114 is determined by flange 118 when in engagement with shoulder 120 on the inside of the barrel.
  • the upper end of the stepped piston 114 carries a pushbutton 119 for actuating the same.
  • indexing member 124 Similar to indexing member 51 in the embodiment shown in FIGS. 1 to 3.
  • cam sleeve 127 Slidable on the piston portion125 is a cam sleeve 127 which has cams 130 and abutments 131 in the same manner as in FIGS. 1 to 3 embodiment.
  • FIG. 7 The difference in the FIG. 7 embodiment is that the cam sleeve 127 is axially movable within the barrel 112. Moreover, the cam sleeve 127 is freely rotatable within the barrel 112. Otherwise, indexing is accomplished in the same manner as in the embodiment shown in FIGS. 1-3. Indexing in this embodiment is effected by the relative movement between the indexing member 124 and the cam sleeve 127. Indexing member 124 has two sets of opposed fingers which are identical to the fingers 66 and 69 of the embodiment of FIG. 1, but only some fingers of one set, indicated at 128, and some fingers 128a of the other set appear in FIG. 7 because the sets of fingers are angularly offset from each other.
  • cam sleeve 127 is shown similar to cam sleeve 51 of FIGS. 1 and 3 and has two cams 130 which are identical to cams 53 (FIG. 2).
  • the two sets of fingers, including sets 128 and 128a, and the cams 130 are identical to the corresponding parts in the embodiment of FIG. 1.
  • the cam member 127 is axially movable and rotatable within barrel 112, the forces and friction between members effects relative motion between the indexing member and the sleeve 124 to effect relative movementbetween them for indexing.
  • the indexing member 124 and cam sleeve 127 may be used in, a variety of different-pipettes having different stroke lengths.
  • the only difference between pipettesneed be the location of shoulder 120 in order to effect a change in stroke length.
  • a pipette assembly comprising; barrel means, reciprocal piston means slidable in said barrel means to draw fluid into and expel fluid from areservoir communicating withsaid barrel means, pushbutton means for actuating said piston means, means providing alternate changes in stroke length including an indexing memberrotatably carried by said piston means, said indexing member having high and low stops thereon, abutment means for selectively engaging said high and low stops on the indexing member, means selectively rotating the stops into alignment with the abutment means including a plurality of axially opposed fingers on said indexing member, cam means engageable with said fingers to rotate the indexing member, said cam means including a first cam surface engageable with one set of opposed fingers and a second cam surface engageable with another set of fingers, said fingers being circumferentially spaced so that when one of the fingers of one set completes engagement with said one cam'surface, one of the fingers of the other set is in axial alignment with a portion of the other cam surface so that the indexing member continues rotation in the same direction upon
  • stops on the indexing member including an annular flange on one end of the indexing member, and recessed portions on said flange defining alternate highand low stops.
  • I a 1 7 A pipette assembly comprising barrel meansfor communication with a fluid reservoir, piston means axially movable in said barrel means to draw fluid into and expel fluid from the reservoir respectively on-intake and discharge strokes of said piston means, means in cluding pushbutton means for actuating said. piston means to move said piston means in oneand, the opposite direction, and means controlling changes in the stroke length of the piston means and operatively connected with said piston means and said pushbutton means, said means controlling changes in the stroke.
  • each of said sets of fingers comprises a plurality of equally circumferentially spaced fingers, the fingers of one of said sets being angularly offset from the fingers of the other of said sets.
  • each of said fingers is resiliently flexible in a circumferential direction
  • said cam means is sized relative to the spacing of said fingers to effect spreading apart movement of adjacent fingers respectively from said first and second sets of fingers during each piston means stroke, and return movement of said adjacent fingers upon each piston means stroke to, hold said rotated member in an indexed position.
  • first and second engagement means comprise engaging surfaces spaced from said fingers and lying in planes normal to the axis of rotation of said rotated one of said members.

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US00153692A 1971-06-16 1971-06-16 Pipettor stroke control mechanism Expired - Lifetime US3766784A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US00153692A US3766784A (en) 1971-06-16 1971-06-16 Pipettor stroke control mechanism
CA140,423A CA954836A (en) 1971-06-16 1972-04-24 Pipettor stroke control mechanism
DE2227731A DE2227731C3 (de) 1971-06-16 1972-06-07 Pipette
GB2839272A GB1389269A (en) 1971-06-16 1972-06-16 Pipette assembly

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00153692A US3766784A (en) 1971-06-16 1971-06-16 Pipettor stroke control mechanism

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US3766784A true US3766784A (en) 1973-10-23

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US00153692A Expired - Lifetime US3766784A (en) 1971-06-16 1971-06-16 Pipettor stroke control mechanism

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US (1) US3766784A (de)
CA (1) CA954836A (de)
DE (1) DE2227731C3 (de)
GB (1) GB1389269A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4141251A (en) * 1978-02-15 1979-02-27 Nichiryo Co., Ltd. Pipetting device
US4187724A (en) * 1978-01-11 1980-02-12 Indicon Inc. Replaceable tip for a pipette
WO1981001666A1 (en) * 1979-12-10 1981-06-25 Indicon Inc Replaceable tip for a pipette
US4442722A (en) * 1982-02-23 1984-04-17 Beckman Instruments Inc. Plunger operated pipet
US6295880B1 (en) 1999-12-08 2001-10-02 Warren E. Gilson Adjustable pipette
US20050142038A1 (en) * 2003-12-31 2005-06-30 Rainin Instrument, Llc Volume adjustable manual pipette with quick set volume adjustment
US20140332559A1 (en) * 2011-09-30 2014-11-13 Avenida Gmbh & Co. Kg Dispenser

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2489507B1 (fr) * 1980-08-27 1986-05-02 Hettich Andreas Pipette doseuse pour le debit de quantites predeterminees de liquide, procede d'etablissement de son organe d'entrainement et dispositif comprenant de telles pipettes
EP3928868A1 (de) 2020-06-22 2021-12-29 Eppendorf AG Pipette für den gebrauch mit einer einen kolben und einen zylinder aufweisenden pipettenspitze oder spritze

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3122280A (en) * 1961-08-14 1964-02-25 Clay Adams Inc Adjustable stroke liquid dispenser having yieldable aligning means
US3302462A (en) * 1964-05-25 1967-02-07 Dow Chemical Co Pipetting device with stop mechanism
US3506164A (en) * 1968-05-31 1970-04-14 Sherwood Medical Ind Inc Automatic pipette

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3122280A (en) * 1961-08-14 1964-02-25 Clay Adams Inc Adjustable stroke liquid dispenser having yieldable aligning means
US3302462A (en) * 1964-05-25 1967-02-07 Dow Chemical Co Pipetting device with stop mechanism
US3506164A (en) * 1968-05-31 1970-04-14 Sherwood Medical Ind Inc Automatic pipette

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4187724A (en) * 1978-01-11 1980-02-12 Indicon Inc. Replaceable tip for a pipette
US4141251A (en) * 1978-02-15 1979-02-27 Nichiryo Co., Ltd. Pipetting device
WO1981001666A1 (en) * 1979-12-10 1981-06-25 Indicon Inc Replaceable tip for a pipette
US4442722A (en) * 1982-02-23 1984-04-17 Beckman Instruments Inc. Plunger operated pipet
US6295880B1 (en) 1999-12-08 2001-10-02 Warren E. Gilson Adjustable pipette
US20050142038A1 (en) * 2003-12-31 2005-06-30 Rainin Instrument, Llc Volume adjustable manual pipette with quick set volume adjustment
US7175813B2 (en) * 2003-12-31 2007-02-13 Rainin Instrument, Llc Volume adjustable manual pipette with quick set volume adjustment
US20140332559A1 (en) * 2011-09-30 2014-11-13 Avenida Gmbh & Co. Kg Dispenser

Also Published As

Publication number Publication date
DE2227731C3 (de) 1980-09-11
DE2227731B2 (de) 1980-01-10
GB1389269A (en) 1975-04-03
DE2227731A1 (de) 1972-12-21
CA954836A (en) 1974-09-17

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