EP0078724A1 - Positive-displacement precision pipette - Google Patents

Positive-displacement precision pipette Download PDF

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Publication number
EP0078724A1
EP0078724A1 EP82401913A EP82401913A EP0078724A1 EP 0078724 A1 EP0078724 A1 EP 0078724A1 EP 82401913 A EP82401913 A EP 82401913A EP 82401913 A EP82401913 A EP 82401913A EP 0078724 A1 EP0078724 A1 EP 0078724A1
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EP
European Patent Office
Prior art keywords
piston
pipette
flange
capillary tube
clamping member
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.)
Granted
Application number
EP82401913A
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German (de)
French (fr)
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EP0078724B1 (en
Inventor
Eric Marteau D'autry
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Individual
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Individual
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Priority to AT82401913T priority Critical patent/ATE14994T1/en
Publication of EP0078724A1 publication Critical patent/EP0078724A1/en
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    • 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
    • B01L3/0275—Interchangeable or disposable dispensing tips
    • B01L3/0279—Interchangeable or disposable dispensing tips co-operating with positive ejection means
    • 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

Definitions

  • the present invention relates to an improvement made to precision positive displacement pipettes intended for the sampling and distribution of small quantities of liquid.
  • such positive displacement precision pipettes are already known which are of the type comprising an essentially tubular pipette body at the lower end of which is arranged a calibrated capillary tube in which it moves in a sealed and against an upward elastic restoring force exerted by a main spring, a piston controlled in its downward movement by a control rod protruding from the upper end of said pipette body, as well as a clamping member of the upper end of the piston, which is of the type with elastic branches deviating radially by displacement against the force exerted by a second spring of resistance much greater than that of the main spring and which is integral in translation with said rod control.
  • Such a positive displacement pipette is for example described in French patent application n ° 79,01335 belonging to the applicant.
  • the present invention specifically aims to achieve a positive displacement pipette which overcomes the aforementioned drawbacks.
  • the positive displacement precision pipette is characterized in that its piston has, in the vicinity of its upper end intended to be grasped by said gripping member, a collar capable of cooperating by its upper face with the 'free end of the elastic branches of the clamping member and by its underside with an abutment surface formed on the inner surface of said capillary tube tip.
  • the positive displacement pipette comprises an essentially tubular body 10 which, in a particular embodiment may be constituted by two separate parts secured to each other by screwing.
  • the upper part or housing (not shown) allows for example to incorporate a mechanism for adjusting and displaying the volume to be withdrawn and distributed, and the tubular lower part 12 is used mainly for guiding the nipping member 14 of the piston 16.
  • the particular adjustment and display mechanism is not part of the present invention and will therefore not be described here in detail. Such a mechanism is for example described in detail in French patent application No. 80 00130 filed in the name of the applicant and the lessons of which are integrated into the present description.
  • a calibrated capillary tube 18 in which moves, in a sealed manner and against an upward elastic restoring force exerted by a main spring 20, a piston 16 controlled in its movement by a control rod 22 projecting from the upper end of the case of the pipette body 10.
  • the pipette has a tip 24 which ends in a calibrated capillary tube 18 and which is able to cooperate by fitting with the free lower end of the pipette body 10.
  • a tip 24 will be made of a thermoplastic material chosen to resist the samples with which it comes into contact. It will for example be made of polypropylene or any other semi-rigid thermoplastic material.
  • the piston 16 has at least one sealing zone 26 coming into intimate contact with the inner surface of the capillary tube 18.
  • a piston 16 can for example advantageously be produced in the form of a 'a stainless steel wire having a coating, for example a coating of polyethylene or teflon, at the sealing zone 26.
  • a coating can for example affect a shape generally cylindrical or else may be equipped at its periphery with at least one annular sealing lip. coming into intimate contact with the internal surface of the capillary tube 18.
  • Such a type of pipette also comprises a clamping member 14 of the upper end of the piston 16, which is of the type with elastic branches 28 which move radially apart by displacement against the force exerted by a second spring (not shown). ) of resistance much higher than that of the main spring 20. It is clear that such a clamping member 14 must be secured in translation with the control rod 22 of the pipette.
  • this pinching member 14 can for example be in the form of a self-contained cartridge comprising a clamp proper ending at its lower end by elastic branches 28 and the other end of which is screwed into a clamp holder.
  • This clamp support is suitable for slide, against the force exerted by the second spring and according to a partial stroke in the upper part of an orifice formed in the clamp holder 30.
  • the latter clamp holder 30 slides itself inside the lower part 12 of the pipette body 10 against the force exerted by the main spring 20. It is important that the end of the elastic branches 28 has an outwardly flaring surface capable of being applied closely against the lower conical opening 32 of the clamp holder 30, and this precisely under the action of the force exerted by the second spring.
  • the assembly of this cartridge which constitutes the pinching member of the piston 16 is elastically urged upwards under the action of the force exerted by the main spring 20.
  • the holder clamp 30 has a shoulder 34 against which the main spring rests. By its lower end, the main spring 20 comes into fixed support on a shoulder 36 formed on the inner surface of the lower part 12 of the pipette body 10 , in the vicinity of its free lower end.
  • the clamp holder 30 can advantageously come into upper abutment against an adjustment screw (not shown), the variable vertical position of which makes it possible to adjust the useful stroke for taking and dispensing the liquid sample.
  • the present invention is however not limited to such a type of adjustable pipette, but can of course also extend to fixed pipettes, ie to pipettes whose adjusting screw would be replaced by a stroke limiting stopper. high which remains fixed in position relative to the pipette body 10.
  • the limiting stop down the useful stroke for dispensing the pipette is made at a shoulder 38 formed in the vicinity of the lower part of the clamp holder 30.
  • This shoulder 38 is able to cooperate with the shoulder corresponding 36 formed in the vicinity of the lower end of the pipette body 10.
  • Such a lower limit position of the clamp-holder member 14 is illustrated in FIG. 2. It will be noted that this position is obtained at the end of the compression complete with main spring 20.
  • the orifice 40 of the free lower end of the pipette body 10 is arranged so as to allow at least one part of the clamping member 14 to pass, which, after compression of the second spring and at the end of its travel towards the bottom, ensures the simultaneous ejection of said end piece 24 and of the piston 16 which remains trapped in the capillary tube 18.
  • the piston 16 has a flange 42 located near its upper end intended to be gripped by the elastic branches 28 of the pinching member 14.
  • This flange 42 has an upper face able to cooperate with the free end of the elastic branches 28 of the pinching member 14, as well as a lower face able to cooperate with an abutment surface 44 formed on the inner wall of the cap 24 with capillary tube 18, preferably in the vicinity of the junction between the upper flared part of the cap and the capillary tube 18 proper.
  • the flange 42 has a transverse dimension substantially equal to the outside diameter of the elastic branches 28, in the separated state, of the clamping member 14.
  • This flange 42 has on its underside at least one peripheral annular zone defining an abutment surface which is substantially perpendicular to the axis of the piston 16.
  • This particular arrangement makes it possible to ensure good abutment cooperation between the underside of the flange 42 and the abutment surface 44 formed on the inner wall of the end piece 24.
  • the flange 42 On its upper face, the flange 42 is shaped so as to be perfectly applied against the profile of the opening zone of the pinching member 14. Since in practice the elastic branches 28 of the pinching member have, near their free end, a bevelled internal face intended to facilitate the introduction of the upper end of the piston 16, the upper face of the collar 42 also has a central part affecting a slightly conical profile.
  • the upper free end of the piston 16 ends, beyond said flange 42, by a bulged portion 46 which is essentially cylindrical.
  • This bulged part 46 can also advantageously have a cone shape of very slight slope inverted with respect to the conical central profile 50.
  • This bulged part 46 only intended to facilitate the gripping of the piston 16 between the elastic branches 28 of the pinching member 14 has an axial dimension, extending from the free upper end of the piston 16 to the upper face of the flange 42, which remains significantly less than the depth of the central orifice 48 formed between the elastic branches 28 of the member pinching 14.
  • the lower face of the flange 42 comprises, in its central part, centering means, cooperating for example with the stop 44 formed on the inner wall of the end piece 24 with capillary tube 18.
  • centering means cooperating for example with the stop 44 formed on the inner wall of the end piece 24 with capillary tube 18.
  • the second spring is not yet fully compressed. Additional pressure exerted on the push button of the control rod 22 ensures complete compression of the second spring beyond the hard point corresponding to the position illustrated in FIG. 2.
  • the elastic branches 28 of the pinch member 14 always remains apart, which allows the release of the gripping of the piston 16, then during said complementary downward stroke these elastic branches 28 exert pressure on the flange 42, which is transmitted to the abutment surface 44 and therefore to the nozzle 24 which can thus be separated from the rest of the pipette.
  • Such an ejection can be obtained without any risk of loss of the nozzle in normal operation, for example by virtue of the particular embodiment described.
  • the inner surface of the upper part of the end piece 24 has at least one annular zone 54 projecting or recessed capable of cooperating elastically with a corresponding annular zone 56 recessed or projecting formed on the outer lateral surface of the lower part 12 of the pipette body.
  • These annular zones 54,56 projecting or recessed have been arranged so as to allow a large guide range of the tip 24 on the end of the pipette, for example of the order of 5 to 10 mm and preferably on the order of 6 to 8 mm.
  • these annular zones 54,56 projecting or recessed are also arranged so as to ensure a short engagement and disengagement stroke of the end piece 24, of the order of approximately 2 mm.

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  • Health & Medical Sciences (AREA)
  • Clinical Laboratory Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Devices For Use In Laboratory Experiments (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

The pipette according to the invention has a body of the pipette at the lower end of which is fitted an end fitting of a calibrated capillary tube in which a piston is movable, and a gripping device at the upper end of the piston. It is characterized in that the piston has, in the region of its upper end intended to be gripped by the gripping device, a flange adapted to cooperate at its upper face with the free ends of the resilient fingers of the gripping device and by its lower face with an abutment surface arranged on the interior surface of the said end fitting of the capillary tube.

Description

La présente invention concerne un perfectionnement apporté aux pipettes de précision à déplacement positif destinées au prélèvement et à la distribution de petites quantités de liquide.The present invention relates to an improvement made to precision positive displacement pipettes intended for the sampling and distribution of small quantities of liquid.

Dans la technique antérieure on connaît déjà de telles pipettes de précision à déplacement positif qui sont du type comprenant un corps de pipette essentiellement tubulaire à l'extrémité inférieure duquel est agencé un tube capillaire calibré dans lequel se déplace, de façon étanche et à l'encontre d'une force de rappel élastique vers le haut exercée par un ressort principal, un piston commandé dans son déplacement vers le bas par une tige de commande dépassant de l'extrémité supérieure dudit corps de pipette, ainsi qu'un organe de pincement de l'extrémité supérieure du piston, qui est du type à branches élastiques s'écartant radialement par déplacement à l'encontre de la force exercée par un second ressort de résistance très supérieure à celle du ressort principal et qui est solidaire en translation avec ladite tige de commande. Une telle pipette à déplacement positif est par exemple décrite dans la demande de brevet français n° 79 01335 appartenant à la demanderesse.In the prior art, such positive displacement precision pipettes are already known which are of the type comprising an essentially tubular pipette body at the lower end of which is arranged a calibrated capillary tube in which it moves in a sealed and against an upward elastic restoring force exerted by a main spring, a piston controlled in its downward movement by a control rod protruding from the upper end of said pipette body, as well as a clamping member of the upper end of the piston, which is of the type with elastic branches deviating radially by displacement against the force exerted by a second spring of resistance much greater than that of the main spring and which is integral in translation with said rod control. Such a positive displacement pipette is for example described in French patent application n ° 79,01335 belonging to the applicant.

Ce type général de pipette à déplacement positif a ensuite fait l'objet d'un perfectionnement destiné à permettre une éjection simultanée de l'embout capillaire et du piston, sans que l'opérateur n'ait à manipuler directement le capillaire et/ou le piston. Il est clair que, lors de la manipulation d'échantillons radioactifs ou encore de tous autres échantillons liquides contaminés, il est déterminant de pouvoir assurer facilement une telle éjection simultanée de l'embout capillaire et du piston qui constituent les seuls organes de la pipette entrant au contact direct du liquide contaminé prélevé.This general type of positive displacement pipette was then the subject of an improvement intended to allow simultaneous ejection of the capillary tip and of the piston, without the operator having to directly manipulate the capillary and / or the piston. It is clear that, when handling radioactive samples or any other contaminated liquid samples, it is crucial to be able to easily ensure such simultaneous ejection of the capillary tip and the piston which constitute the only organs of the incoming pipette in direct contact with the contaminated liquid withdrawn.

Un tel perfectionnement a pu être réalisé à l'aide d'une pipette de précision à déplacement positif du type précité comportant un embout à tube capillaire calibré, apte à coopérer par emmanchement avec l'extrémité inférieure libre du corps de pipette, l'orifice de cette dernière extrémité permettant le passage d'au moins une partie de l'organe de pincement qui, au voisinage de la fin de sa course vers le bas, vient au contact direct d'une butée ménagée sur la surface intérieure de l'embout pour assurer l'éjection simultanée dudit embout et du piston qui reste prisonnier dans l'orifice capillaire. Ce perfectionnement se trouve décrit de façon détaillée dans la demande de brevet français n° 80 00605 déposée au nom de la demanderesse et dont les enseignements sont incorporés à la présente description.Such an improvement could be achieved using a precision displacement pipette of the aforementioned type having a calibrated capillary tube tip, capable of cooperating by fitting with the free lower end of the pipette body, the orifice of this last end allowing the passage of at least a portion of the pinching member which, in the vicinity of the end of its downward stroke, comes into direct contact with a stop formed on the inner surface of the nozzle to ensure the simultaneous ejection of said tip and of the piston which remains trapped in the capillary orifice. This improvement is described in detail in French patent application No. 80 00605 filed in the name of the applicant and the lessons of which are incorporated into the present description.

Dans la pratique, une telle pipette à déplacement positif présente quelques inconvénients au niveau du calibrage. En effet, un calibrage parfait d'une telle pipette ne peut être obtenu avec certitude que si l'extrémité supérieure du piston occupe toujours, d'une opération à l'autre, la même position verticale dans l'organe de pincement. Pour atteindre un tel résultat, il était prévu de faire venir l'extrémité supérieure libre du piston au contact direct du fond de l'orifice central ménagé entre les branches élastiques de l'organe de pincement. Il est clair que ce positionnement correct de l'extrémité supérieure libre du piston, d'une part nécessite un usinage parfait de cette extrémité et ainsi interdit notamment la présence de bavures souvent rencontrées lors de la fabrication des pistons, et d'autre part se trouve défavorablement influencé par la présence de toutes sortes de salissures qui, au cours de l'utilisation de la pipette, peuvent s'accumuler au fond de l'organe de pincement. Un tel encrassement du fond de l'orifice ménagé entre les branches de l'organe de pincement va ainsi provoquer un décalage vers le bas du piston dans son tube capillaire, ce qui fausse bien sûr le calibrage de la pipette.In practice, such a positive displacement pipette has some drawbacks in terms of calibration. Indeed, a perfect calibration of such a pipette can only be obtained with certainty if the upper end of the piston still occupies a operation to another, the same vertical position in the clamping member. To achieve such a result, it was planned to bring the free upper end of the piston into direct contact with the bottom of the central orifice formed between the elastic branches of the pinching member. It is clear that this correct positioning of the free upper end of the piston, on the one hand requires perfect machining of this end and thus prohibits in particular the presence of burrs often encountered during the manufacture of the pistons, and on the other hand is adversely affected by the presence of all kinds of soiling which, during the use of the pipette, can accumulate at the bottom of the pinching member. Such fouling of the bottom of the orifice formed between the branches of the clamping member will thus cause a downward shift of the piston in its capillary tube, which of course distorts the calibration of the pipette.

Ce type de pipette présentait en outre l'inconvénient que, pour faire monter le piston dans sa position haute limite -atteinte lorsque son extrémité libre supérieure vient en butée au fond de l'organe de pincement- il fallait exercer une pression sur l'extrémité inférieure libre du piston qui dépasse de l'orifice du tube capillaire. Cette opération de positionnement correct du piston était habituellement effectuée par l'opérateur en appuyant sur la partie dépassante du piston soit à l'aide de son doigt, soit encore à l'aide de la paillasse. Cette opération était donc intolérable lorsque la pipette était utilisée pour le prélèvement d'échantillons stérilisés, étant donné qu'au cours de l'opération de positionnement correct du piston dans son tube capillaire, l'opérateur risquait de contaminer l'extrémité libre du piston et éventuellement l'extrémité du tube capillaire.This type of pipette also had the drawback that, in order to raise the piston in its high limit position - reached when its upper free end abuts at the bottom of the clamping member - it was necessary to exert pressure on the end free bottom of the piston protruding from the orifice of the capillary tube. This operation of correct positioning of the piston was usually carried out by the operator by pressing on the protruding part of the piston either with his finger or with the bench. This operation was therefore intolerable when the pipette was used to collect sterilized samples, since during the operation of correct positioning of the piston in its capillary tube, the operator risked contaminating the free end of the piston and possibly the end of the capillary tube.

La présente invention a précisément pour but de réaliser une pipette à déplacement positif qui permet d'écarter les inconvénients précités.The present invention specifically aims to achieve a positive displacement pipette which overcomes the aforementioned drawbacks.

Conformément à la présente invention, la pipette de précision à déplacement positif se trouve caractérisée en ce que son piston présente, au voisinage de son extrémité supérieure destinée à être saisie par ledit organe de pincement, une collerette apte à coopérer par sa face supérieure avec l'extrémité libre des branches élastiques de l'organe de pincement et par sa face inférieure avec une surface de butée ménagée sur la surface intérieure dudit embout à tube capillaire.According to the present invention, the positive displacement precision pipette is characterized in that its piston has, in the vicinity of its upper end intended to be grasped by said gripping member, a collar capable of cooperating by its upper face with the 'free end of the elastic branches of the clamping member and by its underside with an abutment surface formed on the inner surface of said capillary tube tip.

D'autres caractéristiques et avantages de la pipette conforme à la présente invention, apparaîtront à la lecture de la description détaillée faite ci-après notamment en référence aux dessins annexés sur lesquels :

  • - la figure 1 illustre la partie basse d'une pipette à déplacement positif conforme à la présente invention ;
  • - la figure 2 représente une vue à plus grande échelle de la zone de la pipette comportant le perfectionnement selon l'invention, et
  • - la figure 3 représente l'ensemble constitué par un embout à tube capillaire dans lequel se trouve introduit un piston, tel qu'ils peuvent être stockés, l'un dans l'autre, en vue de leur mise en place simultanée sur le corps de la pipette.
Other characteristics and advantages of the pipette according to the present invention will appear on reading the detailed description given below in particular with reference to the accompanying drawings in which:
  • - Figure 1 illustrates the lower part of a positive displacement pipette according to the present invention;
  • FIG. 2 represents a view on a larger scale of the area of the pipette comprising the improvement according to the invention, and
  • - Figure 3 shows the assembly consisting of a capillary tube tip into which is inserted a piston, as they can be stored, one inside the other, for their simultaneous implementation on the body pipette.

La pipette à déplacement positif selon l'invention comporte un corps essentiellement tubulaire 10 qui, dans un mode de réalisation particulier peut être constitué par deux parties distinctes solidarisées entre elles par vissage. La partie supérieure ou boîtier (non représentée) permet par exemple d'incorporer un mécanisme de réglage et d'affichage du volume à prélever et à distribuer, et la partie inférieure tubulaire 12 sert principalement au guidage de l'organe de pincement 14 du piston 16. Le mécanisme particulier de réglage et d'affichage ne fait pas partie de la présente invention et ne sera donc pas décrit ici en détail. Un tel mécanisme se trouve par exemple décrit de façon détaillée dans la demande de brevet français n° 80 00130 déposée au nom de la demanderesse et dont les enseignements sont intégrés à la présente description.The positive displacement pipette according to the invention comprises an essentially tubular body 10 which, in a particular embodiment may be constituted by two separate parts secured to each other by screwing. The upper part or housing (not shown) allows for example to incorporate a mechanism for adjusting and displaying the volume to be withdrawn and distributed, and the tubular lower part 12 is used mainly for guiding the nipping member 14 of the piston 16. The particular adjustment and display mechanism is not part of the present invention and will therefore not be described here in detail. Such a mechanism is for example described in detail in French patent application No. 80 00130 filed in the name of the applicant and the lessons of which are integrated into the present description.

De façon classique, à l'extrémité inférieure de la partie 12 du corps de pipette 10 se trouve agencé un tube capillaire calibré 18 dans lequel se déplace, de façon étanche et à l'encontre d'une force de rappel élastique vers le haut exercée par un ressort principal 20, un piston 16 commandé dans son déplacement par une tige de commande 22 dépassant de l'extrémité supérieure du boîtier du corps de pipette 10.Conventionally, at the lower end of the part 12 of the pipette body 10 is arranged a calibrated capillary tube 18 in which moves, in a sealed manner and against an upward elastic restoring force exerted by a main spring 20, a piston 16 controlled in its movement by a control rod 22 projecting from the upper end of the case of the pipette body 10.

Conformément à la présente invention, la pipette comporte un embout 24 qui se termine par un tube capillaire calibré 18 et qui est apte à coopérer par emmanchement avec l'extrémité inférieure libre du corps de pipette 10. De façon avantageuse, un tel embout 24 sera réalisé en une matière thermoplastique choisie pour résister aux échantillons avec lesquels il entre en contact. Il sera par exemple réalisé en polypropylène ou en toute autre matière thermoplastique semi-rigide.According to the present invention, the pipette has a tip 24 which ends in a calibrated capillary tube 18 and which is able to cooperate by fitting with the free lower end of the pipette body 10. Advantageously, such a tip 24 will be made of a thermoplastic material chosen to resist the samples with which it comes into contact. It will for example be made of polypropylene or any other semi-rigid thermoplastic material.

Dans un tel type de pipette, il est indispensable que le piston 16 présente au moins une zone d'étanchéité 26 venant au contact intime de la surface intérieure du tube capillaire 18. Un tel piston 16 peut par exemple être avantageusement réalisé sous la forme d'un fil d'acier inoxydable présentant un enrobage, par exemple un enrobage en polyéthylène ou en téflon, au niveau de la zone d'étanchéité 26. Comme cela se trouve illustré sur la figure 1, un tel enrobage peut par exemple affecter une forme générale cylindrique ou encore peut être équipé à sa périphérie d'au moins une lèvre annulaire d'étanchéité .venant au contact intime de la surface intérieure du tube capillaire 18.In such a type of pipette, it is essential that the piston 16 has at least one sealing zone 26 coming into intimate contact with the inner surface of the capillary tube 18. Such a piston 16 can for example advantageously be produced in the form of a 'a stainless steel wire having a coating, for example a coating of polyethylene or teflon, at the sealing zone 26. As shown in Figure 1, such a coating can for example affect a shape generally cylindrical or else may be equipped at its periphery with at least one annular sealing lip. coming into intimate contact with the internal surface of the capillary tube 18.

Un tel type de pipette comporte également un organe de pincement 14 de l'extrémité supérieure du piston 16, qui est du type à branches élastiques 28 s'écartant radialement par déplacement à l'encontre de la force exercée par un second ressort (non représenté) de résistance très supérieure à celle du ressort principal 20. Il est clair qu'un tel organe de pincement 14 doit être solidaire en translation avec la tige de commande 22 de la pipette.Such a type of pipette also comprises a clamping member 14 of the upper end of the piston 16, which is of the type with elastic branches 28 which move radially apart by displacement against the force exerted by a second spring (not shown). ) of resistance much higher than that of the main spring 20. It is clear that such a clamping member 14 must be secured in translation with the control rod 22 of the pipette.

Le détail de réalisation de cet organe de pincement 14 ne fait pas partie de la présente invention, et ne se trouve donc pas illustré sur les dessins annexés. En se reportant à la demande de brevet français n° 80 00605, on constate que cet organe de pincement peut par exemple se présenter sous la forme d'une cartouche autonome comprenant une pince proprement dite se terminant à son extrémité inférieure par des branches élastiques 28 et dont l'autre extrémité se trouve vissée dans un support de pince. Ce support de pince est apte à coulisser, à l'encontre de la force exercée par le second ressort et selon une course partielle dans la partie supérieure d'un orifice ménagé dans le porte-pince 30. Ce dernier porte-pince 30 coulisse lui-même à l'intérieur de la partie inférieure 12 du corps de pipette 10 à l'encontre de la force exercée par le ressort principal 20. Il est important que l'extrémité des branches élastiques 28 présente une surface s'évasant vers l'extérieur apte à s'appliquer étroitement contre l'ouverture inférieure conique 32 du porte-pince 30, et ceci précisément sous l'action de la force exercée par le second ressort.The detail of embodiment of this clamping member 14 is not part of the present invention, and is therefore not illustrated in the accompanying drawings. Referring to French patent application n ° 80 00605, it can be seen that this pinching member can for example be in the form of a self-contained cartridge comprising a clamp proper ending at its lower end by elastic branches 28 and the other end of which is screwed into a clamp holder. This clamp support is suitable for slide, against the force exerted by the second spring and according to a partial stroke in the upper part of an orifice formed in the clamp holder 30. The latter clamp holder 30 slides itself inside the lower part 12 of the pipette body 10 against the force exerted by the main spring 20. It is important that the end of the elastic branches 28 has an outwardly flaring surface capable of being applied closely against the lower conical opening 32 of the clamp holder 30, and this precisely under the action of the force exerted by the second spring.

On constate sur la figure 1 que l'ensemble de cette cartouche qui constitue l'organe de pincement du piston 16, est élastiquement sollicité vers le haut sous l'action de la force exercée par le ressort principal 20. A cet effet, le porte-pince 30 présente un épaulement 34 contre lequel vient s'appuyer le ressort principal 20. Par son extrémité inférieure, le ressort principal 20 vient en appui fixe sur un épaulement 36 ménagé sur la surface intérieure de la partie inférieure 12 du corps de pipette 10, au voisinage de son extrémité inférieure libre. Le porte-pince 30 peut avantageusement venir en butée supérieure contre une vis de réglage (non représentée), dont la position verticale variable permet de régler la course utile de prélèvement et de distribution de l'échantillon liquide.It can be seen in FIG. 1 that the assembly of this cartridge which constitutes the pinching member of the piston 16, is elastically urged upwards under the action of the force exerted by the main spring 20. For this purpose, the holder clamp 30 has a shoulder 34 against which the main spring rests. By its lower end, the main spring 20 comes into fixed support on a shoulder 36 formed on the inner surface of the lower part 12 of the pipette body 10 , in the vicinity of its free lower end. The clamp holder 30 can advantageously come into upper abutment against an adjustment screw (not shown), the variable vertical position of which makes it possible to adjust the useful stroke for taking and dispensing the liquid sample.

La présente invention ne se trouve toutefois pas limitée à un tel type de pipette réglable, mais peut bien sûr également s'étendre à des pipettes fixes, i.e. à des pipettes dont la vis de réglage serait remplacée par une butée de limitation de course vers le haut qui reste fixe en position par rapport au corps de pipette 10.The present invention is however not limited to such a type of adjustable pipette, but can of course also extend to fixed pipettes, ie to pipettes whose adjusting screw would be replaced by a stroke limiting stopper. high which remains fixed in position relative to the pipette body 10.

La butée de limitation vers le bas de la course utile de distribution de la pipette se trouve réalisée au niveau d'un épaulement 38 ménagé au voisinage de la partie inférieure du porte-pince 30. Cet épaulement 38 est apte à coopérer avec l'épaulement correspondant 36 ménagé au voisinage de l'extrémité inférieure du corps de pipette 10. Une telle position limite inférieure de l'organe porte-pince 14 se trouve illustrée sur la figure 2. On notera que cette position est obtenue à la fin de la compression complète du ressort principal 20.The limiting stop down the useful stroke for dispensing the pipette is made at a shoulder 38 formed in the vicinity of the lower part of the clamp holder 30. This shoulder 38 is able to cooperate with the shoulder corresponding 36 formed in the vicinity of the lower end of the pipette body 10. Such a lower limit position of the clamp-holder member 14 is illustrated in FIG. 2. It will be noted that this position is obtained at the end of the compression complete with main spring 20.

L'orifice 40 de l'extrémité inférieure libre du corps de pipette 10 est agencé de manière à permettre le dépassement d'au moins une partie de l'organe de pincement 14 qui, après compression du second ressort et en fin de course vers le bas, vient assurer l'éjection simultanée dudit embout 24 et du piston 16 qui reste prisonnier dans le tube capillaire 18.The orifice 40 of the free lower end of the pipette body 10 is arranged so as to allow at least one part of the clamping member 14 to pass, which, after compression of the second spring and at the end of its travel towards the bottom, ensures the simultaneous ejection of said end piece 24 and of the piston 16 which remains trapped in the capillary tube 18.

Pour obtenir une telle éjection simultanée du piston 16 et de l'embout 24 à tube capillaire 18, tout en écartant les inconvénients précités de la technique antérieure, le piston 16 présente une collerette 42 située au voisinage de son extrémité supérieure destinée à être saisie par les branches élastiques 28 de l'organe -de pincement 14. Cette collerette 42 présente une face supérieure apte à coopérer avec l'extrémité libre des branches élastiques 28 de l'organe de pincement 14, ainsi qu'une face inférieure apte à coopérer avec une surface de butée 44 ménagée sur la paroi intérieure de l'embout 24 à tube capillaire 18, de préférence au voisinage de la jonction entre la partie supérieure évasée de l'embout et le tube capillaire 18 proprement dit.To obtain such a simultaneous ejection of the piston 16 and of the tip 24 of the capillary tube 18, while eliminating the aforementioned drawbacks of the prior art, the piston 16 has a flange 42 located near its upper end intended to be gripped by the elastic branches 28 of the pinching member 14. This flange 42 has an upper face able to cooperate with the free end of the elastic branches 28 of the pinching member 14, as well as a lower face able to cooperate with an abutment surface 44 formed on the inner wall of the cap 24 with capillary tube 18, preferably in the vicinity of the junction between the upper flared part of the cap and the capillary tube 18 proper.

Comme cela se trouve illustré notamment à la figure 2, la collerette 42 présente une dimension transversale sensiblement égale au diamètre extérieur des branches élastiques 28, à l'état écarté, de l'organe de pincement 14. Cette collerette 42 présente à sa face inférieure au moins une zone annulaire périphérique définissant une surface de butée qui est sensiblement perpendiculaire à l'axe du piston 16. Cette disposition particulière permet d'assurer une bonne coopération de butée entre la face inférieure de la collerette 42 et la surface de butée 44 ménagée sur la paroi intérieure de l'embout 24. A sa face supérieure, la collerette 42 est conformée de manière à parfaitement s'appliquer contre le profil de la zone d'ouverture de l'organe de pincement 14. Etant donné que dans la pratique les branches élastiques 28 de l'organe de pincement présentent au voisinage de leur extrémité libre une face interne biseautée destinée à faciliter l'introduction de l'extrémité supérieure du piston 16, la face supérieure de la collerette 42 comporte également une partie centrale affectant un profil légèrement conique.As illustrated in particular in Figure 2, the flange 42 has a transverse dimension substantially equal to the outside diameter of the elastic branches 28, in the separated state, of the clamping member 14. This flange 42 has on its underside at least one peripheral annular zone defining an abutment surface which is substantially perpendicular to the axis of the piston 16. This particular arrangement makes it possible to ensure good abutment cooperation between the underside of the flange 42 and the abutment surface 44 formed on the inner wall of the end piece 24. On its upper face, the flange 42 is shaped so as to be perfectly applied against the profile of the opening zone of the pinching member 14. Since in practice the elastic branches 28 of the pinching member have, near their free end, a bevelled internal face intended to facilitate the introduction of the upper end of the piston 16, the upper face of the collar 42 also has a central part affecting a slightly conical profile.

Enfin, l'extrémité libre supérieure du piston 16 se termine, au-delà de ladite collerette 42, par une partie renflée 46 essentiellement cylindrique. Cette partie renflée 46 peut également avantageusement affecter une forme de cone de très faible pente inversée par rapport au profil central conique 50. Cette partie renflée 46 uniquement destinée à faciliter la préhension du piston 16 entre les branches élastiques 28 de l'organe de pincement 14 présente une dimension axiale, s'étendant de l'extrémité supérieure libre du piston 16 à la face supérieure de la collerette 42, qui reste notablement inférieure à la profondeur de l'orifice central 48 ménagé entre les branches élastiques 28 de l'organe de pincement 14.Finally, the upper free end of the piston 16 ends, beyond said flange 42, by a bulged portion 46 which is essentially cylindrical. This bulged part 46 can also advantageously have a cone shape of very slight slope inverted with respect to the conical central profile 50. This bulged part 46 only intended to facilitate the gripping of the piston 16 between the elastic branches 28 of the pinching member 14 has an axial dimension, extending from the free upper end of the piston 16 to the upper face of the flange 42, which remains significantly less than the depth of the central orifice 48 formed between the elastic branches 28 of the member pinching 14.

La face inférieure de la collerette 42 comporte, dans sa partie centrale, des moyens de centrage, coopérant par exemple avec la butée 44 ménagée sur la paroi intérieure de l'embout 24 à tube capillaire 18. Ces moyens qui permettent d'assurer le centrage de la partie supérieure du piston, se présentent avantageusement sous la forme d'un profil central conique 50 ménagé à la face inférieure de la collerette 42, le plus grand diamètre de ce profil central conique 50 étant légèrement inférieur au diamètre intérieur du tube capillaire 18. Il est clair que dans la pratique, la collerette 42, la partie renflée 46 ménagée à sa face supérieure et les moyens de centrage 50 prévus à sa face inférieure sont avantageusement réalisés en une seule et même pièce de matière plastique moulée.The lower face of the flange 42 comprises, in its central part, centering means, cooperating for example with the stop 44 formed on the inner wall of the end piece 24 with capillary tube 18. These means which make it possible to ensure centering of the upper part of the piston, advantageously take the form of a conical central profile 50 formed on the underside of the flange 42, the largest diameter of this conical central profile 50 being slightly less than the inside diameter of the capillary tube 18 It is clear that in practice, the collar 42, the bulged part 46 formed on its upper face and the centering means 50 provided on its lower face are advantageously made in one and the same piece of molded plastic.

Lorsque l'on désire utiliser la pipette à déplacement positif selon l'invention, il faut bien sûr équiper la partie inférieure du boîtier à l'aide -d'un embout 24 à tube capillaire 18, dans lequel se déplace un piston 16. Pour ce faire il existe deux possibilités.When it is desired to use the positive displacement pipette according to the invention, it is of course necessary to equip the lower part of the housing with the aid of a tip 24 with capillary tube 18, in which a piston 16 moves. There are two possibilities for doing this.

Selon une première possibilité, on dispose de pistons 16 et d'embouts 24 à tube capillaire stockés à l'état séparé. Dans pareil cas, on exerce sur le bouton poussoir équipant l'extrémité supérieure libre de la tige de commande 22 une pression suffisante pour réaliser la compression du premier et du second ressorts. Cette opération entraîne le déplacement vers le bas de l'équipage mobile de la pipette, ainsi que l'écartement des branches élastiques 28 de l'organe de pincement 14. Il est alors possible d'introduire la partie supérieure renflée 46 du piston 16 entre les branches élastiques écartées 28 de l'organe de pincement 14.According to a first possibility, there are pistons 16 and nozzles 24 with capillary tubes stored in a separate state. In such a case, pressure is exerted on the push button fitted to the free upper end of the control rod 22 to achieve compression of the first and second springs. This operation leads to the downward movement of the movable assembly of the pipette, as well as the spacing of the elastic branches 28 of the clamping member 14. It is then possible to introduce the bulged upper part 46 of the piston 16 between the elastic branches spaced apart 28 from the pinching member 14.

Cette introduction et cette mise en place du piston 16 s'effectuent dans une position verticale très approximative, l'essentiel étant d'assurer la préhension du piston 16 par l'organe de pincement 14. Puis, on emmanche à force l'embout 24 à tube capillaire 18 en veillant à ce que le piston 16 pénètre sans entrave à l'intérieur du tube capillaire 18. Pour ce faire, il est avantageux de ne pas utiliser comme surface de butée 44 un décrochement circulaire continu, mais plutôt une pluralité d'ergots ou de nervures présentant une répartition angulaire constante. Cet agencement particulier de la surface de butée 44 évite en effet de venir en butée avec la pointe du piston 16 contre une surface continue en décrochement. On notera également que la pénétration dans l'embout 24 et le tube capillaire 18 se trouve facilitée par la présence de paroi intérieure inclinée 52 de l'embout 24.This introduction and this positioning of the piston 16 takes place in a very approximate vertical position, the main thing being to ensure that the piston 16 is gripped by the pinching member 14. Then, the end piece 24 is force fitted with capillary tube 18, taking care that the piston 16 penetrates unhindered inside the capillary tube 18. To do this, it is advantageous not to use as abutment surface 44 a continuous circular recess, but rather a plurality of 'pins or ribs with a constant angular distribution. This particular arrangement of the abutment surface 44 in fact prevents it from coming into abutment with the tip of the piston 16 against a continuous surface in an offset. It will also be noted that penetration into the end piece 24 and the capillary tube 18 is facilitated by the presence of an inclined inner wall 52 of the end piece 24.

Lorsque le piston 16 et l'embout 24 à tube capillaire ont ainsi été rapidement mis en place, il est alors essentiel de s'assurer que le piston 16 occupe bien la bonne position limite inférieure dans son tube capillaire, c'est-à-dire qu'il faut faire un réglage du zéro de la pipette ou encore réaliser son calibrage. Grâce à la disposition selon la présente invention, pareil calibrage peut être réalisé très facilement par simple pression exercée sur le bouton poussoir équipant l'extrémité supérieure de la tige de commande 22 de la pipette. Une telle pression sur la tige de commande 22 comprime en totalité le premier ressort 20 et assure une compression partielle du second ressort jusqu'à atteindre une position illustrée par la figure 2. Au cours de cette course additionnelle, à la suite d'une compression partielle du second ressort, les branches élastiques 28 de l'organe de pincement 14 s'écartent puis descendent jusqu'à appuyer sur la face supérieure de la collerette 42 du piston 16. En poursuivant la compression du second ressort, on crée une course supplémentaire vers le bas de l'équipage mobile jusqu'à ce que la face inférieure de la collerette 42 vienne en butée sur la surface de butée interne 44 ménagée sur la paroi intérieure de l'embout 24. A ce stade l'opérateur perçoit une sensation de point dur et interrompt sa pression exercée sur la tige de commande 22.On a ainsi la certitude que le piston 16 occupe une position correcte dans le tube capillaire 18, le calibrage de la pipette étant ainsi réalisé de façon très simple et avec une précision parfaite.When the piston 16 and the capillary tube end piece 24 have thus been rapidly put in place, it is then essential to ensure that the piston 16 occupies the correct lower limit position in its capillary tube, that is to say say that you need to adjust the pipette zero or calibrate it. Thanks to the arrangement according to the present invention, such calibration can be carried out very easily by simple pressure exerted on the push button fitted to the upper end of the control rod 22 of the pipette. Such pressure on the control rod 22 fully compresses the first spring 20 and ensures partial compression of the second spring until it reaches a position illustrated in FIG. 2. During this additional stroke, following partial compression of the second spring, the elastic branches 28 of the pinching member 14 move apart then descend until they press on the upper face of the flange 42 of the piston 16. By continuing the compression of the second spring, creates an additional downward stroke of the movable assembly until the underside of the flange 42 abuts on the internal abutment surface 44 formed on the inner wall of the end piece 24. At this stage the operator perceives a feeling of hard point and interrupts his pressure exerted on the control rod 22. This gives us the certainty that the piston 16 occupies a correct position in the capillary tube 18, thus calibrating the pipette in a very simple manner. and with perfect precision.

On notera que dans la position illustrée par la figure 2, le second ressort n'est.pas encore complètement comprimé. Une pression supplémentaire exercée sur le bouton poussoir de la tige de commande 22 permet d'assurer la compression complète du second ressort au-delà du point dur correspondant à la position illustrée à la figure 2. Dans pareil cas, les branches élastiques 28 de l'organe de pincement 14 restent toujours écartées, ce qui permet la libération de la préhension du piston 16, puis lors de ladite course complémentaire vers le bas ces branches élastiques 28 exercent une pression sur la collerette 42, qui est transmise à la surface de butée 44 et donc à l'embout 24 qui peut ainsi être désolidarisé du reste de la pipette. Une telle éjection peut être obtenue sans aucun risque de perte de l'embout en fonctionnement normal, par exemple grâce au mode de réalisation particulier décrit. On constate sur la figure 2 que la surface intérieure de la partie supérieure de l'embout 24 présente au moins une zone annulaire 54 en saillie ou en retrait apte à coopérer élastiquement avec une zone annulaire correspondante 56 en retrait ou en saillie ménagée sur la surface latérale extérieure de la partie inférieure 12 du corps de pipette. Ces zones annulaires 54,56 en saillie ou en retrait ont été agencées de manière à permettre une grande portée de guidage de l'embout 24 sur l'extrémité de la pipette, par exemple de l'ordre de 5 à 10 mm et de préférence de l'ordre de 6 à 8 mm. En revanche, ces zones annulaires 54,56 en saillie ou en retrait sont également agencées de manière à assurer une faible course d'engagement et de dégagement de l'embout 24, de l'ordre d'environ 2 mm.Note that in the position illustrated in Figure 2, the second spring is not yet fully compressed. Additional pressure exerted on the push button of the control rod 22 ensures complete compression of the second spring beyond the hard point corresponding to the position illustrated in FIG. 2. In such a case, the elastic branches 28 of the pinch member 14 always remains apart, which allows the release of the gripping of the piston 16, then during said complementary downward stroke these elastic branches 28 exert pressure on the flange 42, which is transmitted to the abutment surface 44 and therefore to the nozzle 24 which can thus be separated from the rest of the pipette. Such an ejection can be obtained without any risk of loss of the nozzle in normal operation, for example by virtue of the particular embodiment described. We see on the Figure 2 that the inner surface of the upper part of the end piece 24 has at least one annular zone 54 projecting or recessed capable of cooperating elastically with a corresponding annular zone 56 recessed or projecting formed on the outer lateral surface of the lower part 12 of the pipette body. These annular zones 54,56 projecting or recessed have been arranged so as to allow a large guide range of the tip 24 on the end of the pipette, for example of the order of 5 to 10 mm and preferably on the order of 6 to 8 mm. On the other hand, these annular zones 54,56 projecting or recessed are also arranged so as to ensure a short engagement and disengagement stroke of the end piece 24, of the order of approximately 2 mm.

Selon une autre possibilité, il est possible de stocker, par exemple sur un râtelier, l'ensemble constitué par l'embout 24 à tube capillaire et le piston 16 déjà mis en place tel qu'illustré par la figure 3. On constate à l'examen de cette figure que la face inférieure de la collerette 42, et en particulier la zone annulaire périphérique perpendiculaire à l'axe du piston 16, joue ici une fonction supplémentaire de maintien du piston 16 dans le tube capillaire 18, évitant ainsi tout risque pour le piston de glisser vers le bas et par conséquent de s'échapper hors de l'embout 24 à tube capillaire 18. On comprendra à l'examen de cette figure 3 l'intérêt essentiel de ménager à la surface intérieure de la collerette 42 des moyens de centrage, par exemple sous la forme d'un cône 50, afin d'assurer le positionnement correct de la partie supérieure renflée 46 du piston 16 qui est destiné à pénétrer dans l'orifice 48 ménagé entre les branches élastiques 28 de l'organe de pincement 14. Ces moyens de centrage permettent en effet d'obtenir une certitude de coïncidence, lorsque l'on vient engager la partie inférieure du corps de la pipette dans l'embout 24. Cette opération s'effectue évidemment en ayant pris soin au préalable d'assurer une pression sur le bouton poussoir de la tige de commande 22 à l'encontre du premier et du second ressorts, afin d'écarter les branches élastiques 28 de l'organe de pincement 14, destiné à recevoir l'extrémité renflée 46 du piston 16. Dans pareil cas le calibrage, tel qu'explicité précédemment, se trouve réalisé automatiquement, puisque le piston 16 occupait déjà sa position correcte dans le tube capillaire 18. Il est toutefois possible de répéter l'opération précédente afin d'avoir la certitude d'un bon calibrage.According to another possibility, it is possible to store, for example on a rack, the assembly constituted by the end piece 24 with capillary tube and the piston 16 already put in place as illustrated in FIG. 3. 'examination of this figure that the underside of the collar 42, and in particular the peripheral annular zone perpendicular to the axis of the piston 16, plays here an additional function of holding the piston 16 in the capillary tube 18, thus avoiding any risk for the piston to slide downwards and consequently to escape from the end piece 24 with capillary tube 18. It will be understood on examining this figure 3 the essential advantage of providing the inner surface of the collar 42 centering means, for example in the form of a cone 50, in order to ensure the correct positioning of the bulged upper part 46 of the piston 16 which is intended to penetrate into the orifice 48 formed between the elastic branches 28 of the pinching member 14. These centering means indeed make it possible to obtain a certainty of coincidence, when one comes to engage the lower part of the body of the pipette in the nozzle 24. This operation is obviously carried out having taken care beforehand to ensure a pressure on the push button of the control rod 22 against the first and second springs, in order to separate the elastic branches 28 from the member. pinch 14, intended to receive the bulged end 46 of the piston 16. In such a case the calibration, as explained above, is carried out automatically, since the piston 16 already occupied its correct position in the capillary tube 18. It is however, it is possible to repeat the previous operation in order to be sure of a good calibration.

On comprendra aisément qu'une telle disposition ménageant un vide au fond de l'organe de pincement, écarte toutes les incidences d'un éventuel encrassement du fond de l'orifice 48 de l'organe de pincement 14.It will easily be understood that such an arrangement leaving a vacuum at the bottom of the pinching member, eliminates all the incidences of possible fouling of the bottom of the orifice 48 of the pinching member 14.

Bien entendu, la présente invention ne se limite pas aux modes de réalisation particuliers décrits, mais il est parfaitement possible, sans pour autant sortir du cadre de la présente invention, d'en imaginer un certain nombre de variantes d'exécution.Of course, the present invention is not limited to the particular embodiments described, but it is perfectly possible, without departing from the scope of the present invention, to imagine a number of alternative embodiments.

Claims (9)

1/ Pipette de précision à déplacement positif destinée au prélèvement et à la distribution de petites quantités de liquide, du type comprenant un corps de pipette essentiellement tubulaire à l'extrémité infé- . rieure duquel est emmanché de façon amovible un embout à tube capillaire calibré dans lequel se déplace, de façon étanche et à l'encontre d'une force de rappel élastique vers le haut exercée par un ressort principal, un piston commandé dans son déplacement par une tige de commande dépassant de l'extrémité supérieure dudit corps de pipette, ainsi qu'un organe de pincement de l'extrémité supérieure du piston, qui est du type à branches élastiques s'écartant radialement par déplacement à l'encontre de la force exercée par un second ressort de résistance très supérieure à celle du ressort principal et qui est solidaire en translation avec ladite tige de commande, l'orifice de l'extrémité inférieure libre du corps de pipette permettant le passage d'au moins une partie de l'organe de pincement qui, après compression du second ressort et au voisinage de la fin de sa course vers le bas, vient assurer l'éjection simultanée dudit embout et du piston qui reste prisonnier dans le tube capillaire, caractérisée en ce que le piston (16) présente, au voisinage de son extrémité supérieure destinée à être saisie par ledit organe de pincement (14), une collerette (42) apte à coopérer par sa face supérieure avec l'extrémité libre des branches élastiques (28) de l'organe de pincement (14) et par sa face inférieure avec une surface de butée (44) ménagée sur la surface intérieure dudit embout (24) à tube capillaire (18).1 / Precision positive displacement pipette intended for the sampling and distribution of small quantities of liquid, of the type comprising an essentially tubular pipette body at the lower end. of which a calibrated capillary tube endpiece is removably fitted in which moves, in leaktight manner and against an upwardly elastic restoring force exerted by a main spring, a piston controlled in its movement by a control rod protruding from the upper end of said pipette body, as well as a clamping member from the upper end of the piston, which is of the type with elastic branches deviating radially by displacement against the force exerted by a second spring of resistance much greater than that of the main spring and which is integral in translation with said control rod, the orifice of the free lower end of the pipette body allowing the passage of at least part of the clamping member which, after compression of the second spring and in the vicinity of the end of its downward stroke, ensures the simultaneous ejection of said tip and of the piston which remains trapped in the capillary tube, characterized in that the piston (16) has, in the vicinity of its upper end intended to be grasped by said gripping member (14), a flange (42) capable of cooperating by its upper face with the free end of the elastic branches (28) of the clamping member (14) and by its underside with an abutment surface (44) formed on the inner surface of said cap (24) with capillary tube (18). 2/ Pipette selon la revendication 1, caractérisée en ce que ladite collerette (42) présente une dimension transversale sensiblement égale au diamètre extérieur des branches élastiques (28),à l'état écarté, de l'organe de pincement (14).2 / pipette according to claim 1, characterized in that said collar (42) has a transverse dimension substantially equal to the outer diameter of the elastic branches (28), in the separated state, of the clamping member (14). 3/ Pipette selon l'une des revendications 1 et 2, caractérisée en ce que ladite collerette (42) présente une face inférieure dont au moins une zone annulaire périphérique définit une surface de butée sensiblement perpendiculaire à l'axe du piston (16).3 / Pipette according to one of claims 1 and 2, characterized in that said flange (42) has a lower face of which at least one peripheral annular zone defines an abutment surface substantially perpendicular to the axis of the piston (16). 4/ Pipette selon l'une des revendications 1 à 3, caractérisée en ce que ladite collerette (42) présente une face supérieure conformée de manière à parfaitement s'appliquer contre le profil de la zone d'ouverture de l'organe de pincement (14).4 / Pipette according to one of claims 1 to 3, characterized in that said flange (42) has an upper face shaped so as to be perfectly applied against the profile of the opening area of the clamping member ( 14). 5/ Pipette selon la revendication 4, caractérisée en ce que ladite collerette (42) présente une face supérieure dont la partie centrale affecte un profil conique.5 / A pipette according to claim 4, characterized in that said collar (42) has an upper face whose central part affects a conical profile. 6/ Pipette selon l'une des revendications 1 à 5, caractérisée en ce que l'extrémité libre supérieure du piston (16) se termine au-delà de ladite collerette (42) par une partie renflée (46) essentiellement cylindrique, destinée à pénétrer dans l'ouverture de l'organe de pincement (14), et en ce que la dimension axiale de cette partie renflée (46) s'étendant jusqu'à la face supérieure de la collerette (42) est inférieure à la profondeur de l'orifice (48) de l'organe de pincement (14).6 / pipette according to one of claims 1 to 5, characterized in that the upper free end of the piston (16) ends beyond said flange (42) by a bulged portion (46) essentially cylindrical, intended for penetrate into the opening of the clamping member (14), and in that the axial dimension of this bulged part (46) extending to the upper face of the flange (42) is less than the depth of the orifice (48) of the clamping member (14). 7/ Pipette selon l'une des revendications 1 à 6, caractérisée en ce que la face inférieure de ladite collerette (42) comporte, dans sa partie centrale, des moyens de centrage de la partie supérieure du piston (16).7 / Pipette according to one of claims 1 to 6, characterized in that the underside of said collar (42) comprises, in its central part, means for centering the upper part of the piston (16). 8/ Pipette selon la revendication 7, caractérisée en ce que lesdits moyens de centrage se présentent sous la forme d'un profil central conique (50) ménagé à la face inférieure de la collerette (42), le plus grand diamètre de ce profil central conique (50) étant légèrement inférieur au diamètre intérieur du tube capillaire (18).8 / pipette according to claim 7, characterized in that said centering means are in the form of a conical central profile (50) formed on the underside of the flange (42), the largest diameter of this central profile conical (50) being slightly smaller than the inside diameter of the capillary tube (18). 9/ Pipette selon l'une des revendications 1 à 8, caractérisée en ce que la collerette (42), la partie renflée (46) ménagée à sa face supérieure et les moyens de centrage (50) prévus à sa face inférieure sont réalisés en une seule et même pièce de matière plastique moulée.9 / Pipette according to one of claims 1 to 8, characterized in that the flange (42), the bulged part (46) formed on its upper face and the centering means (50) provided on its lower face are made in a single piece of molded plastic.
EP82401913A 1981-10-28 1982-10-19 Positive-displacement precision pipette Expired EP0078724B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82401913T ATE14994T1 (en) 1981-10-28 1982-10-19 PRECISION PIPETTE WITH DISPLACEMENT EFFECT.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8120220 1981-10-28
FR8120220A FR2515339A1 (en) 1981-10-28 1981-10-28 PRECISION PIPETTE WITH POSITIVE DISPLACEMENT

Publications (2)

Publication Number Publication Date
EP0078724A1 true EP0078724A1 (en) 1983-05-11
EP0078724B1 EP0078724B1 (en) 1985-08-21

Family

ID=9263478

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82401913A Expired EP0078724B1 (en) 1981-10-28 1982-10-19 Positive-displacement precision pipette

Country Status (7)

Country Link
US (1) US4474071A (en)
EP (1) EP0078724B1 (en)
JP (1) JPS5884049A (en)
AT (1) ATE14994T1 (en)
DE (1) DE3265643D1 (en)
FR (1) FR2515339A1 (en)
IE (1) IE53877B1 (en)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0226867A2 (en) * 1985-12-17 1987-07-01 Hamilton Bonaduz AG Pipette and pipetting system
EP0421785A2 (en) * 1989-10-04 1991-04-10 Drummond Scientific Company Pipetter device
WO1991017833A2 (en) * 1990-05-21 1991-11-28 Pb Diagnostic Systems, Inc. Fluid dispensing system having a pipette assembly with preset tip locator
EP0494735A2 (en) * 1991-01-07 1992-07-15 Labsystems Oy Positive-displacement pipette
US5983733A (en) * 1996-11-15 1999-11-16 Hamilton Company Manual pipette
WO2006030201A1 (en) 2004-09-13 2006-03-23 Microsample Ltd. Method and apparatus for sampling and analysis of fluids
WO2006087444A1 (en) * 2005-02-18 2006-08-24 Gilson S.A.S. Tip for sampling pipette and pipette thus equipped
WO2010086380A1 (en) 2009-01-30 2010-08-05 Pronota N.V. Biomarker for diagnosis, prediction and/or prognosis of acute heart failure and uses thereof
WO2011048173A1 (en) 2009-10-21 2011-04-28 Pronota N.V. Mcam as a biomarker for fluid homeostasis
WO2011128357A2 (en) 2010-04-13 2011-10-20 Pronota N.V. Biomarkers for hypertensive disorders of pregnancy
FR3012883A1 (en) * 2013-11-07 2015-05-08 Gilson Sas POSITIVE DISPLACEMENT PIPETTING SYSTEM HAVING DESIGN FOR FACILITATING PREVENTION OF THE PISTON OF THE CAPILLARY PISTON ASSEMBLY
EP2924439A1 (en) 2010-03-26 2015-09-30 Mycartis N.V. Ltbp2 as a biomarker for predicting or prognosticating mortality
US9804064B2 (en) 2011-09-19 2017-10-31 Gilson Sas Positive displacement pipette having an improved ejection function
US9931625B2 (en) 2013-03-25 2018-04-03 Gilson Sas Ejection function for a positive-displacement pipetting system
EP3831486A1 (en) * 2019-12-06 2021-06-09 Eppendorf AG Pipette tip family comprising pipette tips for use with pipettes of a pipette family and pipette family comprising pipettes for use with pipette tips of a pipette tip family
EP3831487A1 (en) * 2019-12-06 2021-06-09 Eppendorf AG Pipette for use with a pipette tip and pipette tip for use with a pipette

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US5192511A (en) * 1991-05-31 1993-03-09 Tri-Continent Scientific, Inc. Pipette tip and piston
US6186012B1 (en) 1997-12-30 2001-02-13 Battelle Memorial Institute Hand held sample tube manipulator, system and method
US6955077B2 (en) * 2002-05-09 2005-10-18 Quality Scientific Plastics, Inc. Pipette tip with an internal sleeve and method for forming same
US7641859B2 (en) * 2004-02-11 2010-01-05 Matrix Technologies Corporation Pipette tip mounting and ejection assembly and associated pipette tip
US20090215192A1 (en) * 2004-05-27 2009-08-27 Stratos Biosystems, Llc Solid-phase affinity-based method for preparing and manipulating an analyte-containing solution
DE102005041183B3 (en) * 2005-08-31 2007-01-04 Eppendorf Ag Two-part pipetting system for metering liquids, has lower spigot which is secured in its holder by snap hooks with catches and released by wedge system actuated by movement of unlocking ring
GB0605003D0 (en) * 2006-03-13 2006-04-19 Microsample Ltd Method and apparatus for piercing the skin and delivery or collection of liquids
DE102007042115B4 (en) * 2007-09-05 2010-12-02 Eppendorf Ag pipette
US8899118B1 (en) * 2009-05-11 2014-12-02 Dan Seguin Multi-channel aspirating and dispensing instrument
EP2818245B1 (en) 2009-07-27 2019-07-17 Eppendorf Ag Nozzle, nozzle family and metering device
US8524170B2 (en) 2011-02-22 2013-09-03 Rainin Instrument, Llc Pipette and sealing tip
WO2014085931A1 (en) 2012-12-09 2014-06-12 Chromedx Inc. Automated ultra-filtration system
WO2015079477A1 (en) * 2013-11-29 2015-06-04 ヤマハ発動機株式会社 Aspiration method
WO2015079476A1 (en) * 2013-11-29 2015-06-04 ヤマハ発動機株式会社 Aspiration tip
JP6678096B2 (en) * 2016-12-13 2020-04-08 株式会社日立製作所 Dispensing device, dispensing method, dispensing device manufacturing method
JP7315625B2 (en) 2020-07-14 2023-07-26 エッペンドルフ エスイー Pipettes for use with pipette tips with integral plungers
GB2607893A (en) * 2021-06-11 2022-12-21 Spt Labtech Ltd Pipette tip for a liquid dispensing apparatus

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EP0014120A1 (en) * 1979-01-19 1980-08-06 Marteau d'Autry, Eric Pipette with positive displacement
EP0032469A1 (en) * 1980-01-11 1981-07-22 Marteau d'Autry, Eric Pipette with positive displacement

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DE2711124C2 (en) * 1977-03-15 1979-05-10 Labora Mannheim Gmbh Fuer Labortechnik, 6800 Mannheim Hand pipette
FI56937C (en) * 1978-08-04 1980-05-12 Suovaniemi Finnpipette PIPETT ANORDNING FOER ATT AVLAEGSNA EN ENGAONGSSPETSBEHAOLLARE FRAON EN PIPETT
FR2473124A1 (en) * 1980-01-04 1981-07-10 Marteau D Autry Eric DEVICE FOR COLLECTING AND DISPENSING DIGITAL ADJUSTABLE VOLUMES OF LIQUIDS

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EP0014120A1 (en) * 1979-01-19 1980-08-06 Marteau d'Autry, Eric Pipette with positive displacement
EP0032469A1 (en) * 1980-01-11 1981-07-22 Marteau d'Autry, Eric Pipette with positive displacement

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0226867A2 (en) * 1985-12-17 1987-07-01 Hamilton Bonaduz AG Pipette and pipetting system
EP0226867A3 (en) * 1985-12-17 1988-08-10 Hamilton Bonaduz Ag Pipette and pipetting system
EP0421785A2 (en) * 1989-10-04 1991-04-10 Drummond Scientific Company Pipetter device
EP0421785A3 (en) * 1989-10-04 1991-06-26 Drummond Scientific Company Pipetter device
WO1991017833A2 (en) * 1990-05-21 1991-11-28 Pb Diagnostic Systems, Inc. Fluid dispensing system having a pipette assembly with preset tip locator
WO1991017833A3 (en) * 1990-05-21 1991-12-26 Pb Diagnostic Systems Inc Fluid dispensing system having a pipette assembly with preset tip locator
EP0494735A2 (en) * 1991-01-07 1992-07-15 Labsystems Oy Positive-displacement pipette
EP0494735A3 (en) * 1991-01-07 1992-12-09 Labsystems Oy Positive-displacement pipette
US5983733A (en) * 1996-11-15 1999-11-16 Hamilton Company Manual pipette
WO2006030201A1 (en) 2004-09-13 2006-03-23 Microsample Ltd. Method and apparatus for sampling and analysis of fluids
US8092394B2 (en) 2004-09-13 2012-01-10 Microsample Ltd. Method and apparatus for sampling and analysis of fluids
WO2006087444A1 (en) * 2005-02-18 2006-08-24 Gilson S.A.S. Tip for sampling pipette and pipette thus equipped
FR2882273A1 (en) * 2005-02-18 2006-08-25 Gilson Sas Soc Par Actions Sim TIP FOR TAKING PIPETTE, AND PIPETTE THUS EQUIPPED
US8480972B2 (en) 2005-02-18 2013-07-09 Gilson S.A.S. Shaft for a sampling pipette
WO2010086380A1 (en) 2009-01-30 2010-08-05 Pronota N.V. Biomarker for diagnosis, prediction and/or prognosis of acute heart failure and uses thereof
WO2011048168A1 (en) 2009-10-21 2011-04-28 Pronota N.V. Biomarker for diagnosis, prediction and/or prognosis of acute heart failure and uses thereof
WO2011048173A1 (en) 2009-10-21 2011-04-28 Pronota N.V. Mcam as a biomarker for fluid homeostasis
EP2924439A1 (en) 2010-03-26 2015-09-30 Mycartis N.V. Ltbp2 as a biomarker for predicting or prognosticating mortality
WO2011128357A2 (en) 2010-04-13 2011-10-20 Pronota N.V. Biomarkers for hypertensive disorders of pregnancy
US9804064B2 (en) 2011-09-19 2017-10-31 Gilson Sas Positive displacement pipette having an improved ejection function
US9931625B2 (en) 2013-03-25 2018-04-03 Gilson Sas Ejection function for a positive-displacement pipetting system
FR3012883A1 (en) * 2013-11-07 2015-05-08 Gilson Sas POSITIVE DISPLACEMENT PIPETTING SYSTEM HAVING DESIGN FOR FACILITATING PREVENTION OF THE PISTON OF THE CAPILLARY PISTON ASSEMBLY
WO2015067579A1 (en) * 2013-11-07 2015-05-14 Gilson Sas Positive displacement pipetting system, having a design facilitating the gripping of the piston of the capillary-piston assembly
CN105705241A (en) * 2013-11-07 2016-06-22 吉尔松有限合伙公司 Positive displacement pipetting system, having a design facilitating the gripping of the piston of the capillary-piston assembly
US9931626B2 (en) 2013-11-07 2018-04-03 Gilson Sas Positive displacement pipetting system, having a design facilitating the gripping of the piston of the capillary-piston assembly
EP3831486A1 (en) * 2019-12-06 2021-06-09 Eppendorf AG Pipette tip family comprising pipette tips for use with pipettes of a pipette family and pipette family comprising pipettes for use with pipette tips of a pipette tip family
EP3831487A1 (en) * 2019-12-06 2021-06-09 Eppendorf AG Pipette for use with a pipette tip and pipette tip for use with a pipette
WO2021110902A1 (en) * 2019-12-06 2021-06-10 Eppendorf Ag Pipette tip family and pipette family

Also Published As

Publication number Publication date
IE822582L (en) 1983-04-28
ATE14994T1 (en) 1985-09-15
JPS5884049A (en) 1983-05-20
DE3265643D1 (en) 1985-09-26
US4474071A (en) 1984-10-02
JPH0153102B2 (en) 1989-11-13
IE53877B1 (en) 1989-03-29
EP0078724B1 (en) 1985-08-21
FR2515339A1 (en) 1983-04-29
FR2515339B1 (en) 1984-01-20

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