EP0591038B1 - Pipette for sampling and distributing variable volumes of liquids - Google Patents

Pipette for sampling and distributing variable volumes of liquids Download PDF

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Publication number
EP0591038B1
EP0591038B1 EP93402356A EP93402356A EP0591038B1 EP 0591038 B1 EP0591038 B1 EP 0591038B1 EP 93402356 A EP93402356 A EP 93402356A EP 93402356 A EP93402356 A EP 93402356A EP 0591038 B1 EP0591038 B1 EP 0591038B1
Authority
EP
European Patent Office
Prior art keywords
push rod
sleeve
sheath
pipette
rotation
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.)
Expired - Lifetime
Application number
EP93402356A
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German (de)
French (fr)
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EP0591038A1 (en
Inventor
Eric Jacques Henri Georges Marteau D'autry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gilson Medical Electronics (france)sa
Original Assignee
Gilson Medical Electronics (france)sa
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Publication date
Application filed by Gilson Medical Electronics (france)sa filed Critical Gilson Medical Electronics (france)sa
Publication of EP0591038A1 publication Critical patent/EP0591038A1/en
Application granted granted Critical
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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
    • B01L3/021—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
    • 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
    • B01L2300/02—Identification, exchange or storage of information
    • B01L2300/025—Displaying results or values with integrated means
    • B01L2300/026—Drum counters

Definitions

  • the present invention relates to an improvement to a pipette for sampling and dispensing adjustable volumes of liquids.
  • the invention relates more particularly to an improvement to a pipette of the type comprising a pipette body elongated along a longitudinal axis and a piston mounted in translation along this axis inside said pipette body to define a chamber of variable volume opening onto a sampling port, the piston being driven on a limited stroke in the direction of the sampling port by means of a pressure exerted manually on a push rod mounted in translation in the pipette body and in the opposite direction by reaction of means of elastic return until it abuts against an axial end of a metal sleeve extending inside the pipette body along said longitudinal axis.
  • the sleeve is externally threaded and cooperates by screwing with an internal thread of the pipette body so as to move longitudinally when rotated, in order to adjust the stroke in the opposite direction of the piston and the volume of the chamber.
  • the sheath is able to be driven in rotation by a fine adjustment wheel secured thereto and meshes with means for displaying the volume to be dispensed.
  • the push rod is mounted in translation in the sleeve.
  • the volume to be dispensed is usually adjusted using the thumb and forefinger, these two fingers each applying to opposite sides of the fine adjustment wheel, accessible from the outside. through windows provided on two opposite sides of the pipette body.
  • the fine adjustment wheel allows precise adjustment of the volume to be dispensed but in return can only be driven, with each action of the thumb and forefinger, on a limited angle of rotation linked to the width of the windows provided on the pipette body.
  • the present invention relates to an improved pipette, overcoming the aforementioned drawbacks, in particular which is easily adjustable by an operator wearing gloves and presents a possibility of rapid adjustment of the volume to be dispensed.
  • the push rod has on a part at least of its length a non-symmetrical section of revolution, and the sleeve is made integral, by means of attachment, with a sleeve coaxial with the sleeve and in which the part of non-symmetrical section of revolution of the push rod is also engaged, the sleeve having an internal section of complementary or homologous profile of said part of push rod so as to secure in rotation the push rod and the sleeve for rapid adjustment of the volume to be dispensed, while allowing longitudinal movement of the push rod inside the sleeve.
  • the sleeve is glued inside the sheath.
  • the sleeve is received in a bore opening on the axial end of the sleeve serving as a stop for limiting the stroke in the opposite direction of the piston, the radially external surface of the sleeve having recesses for accommodating an adhesive. fixing in the bore of the sleeve.
  • the push rod has a part situated outside the pipette body provided with a push button comprising a quick adjustment wheel provided with means for securing in rotation with said push rod and a cover mounted free to rotate about said longitudinal axis, covering the axial end edge of the wheel located opposite the pipette body.
  • the means for securing in rotation the rapid adjustment wheel on the push rod comprise two longitudinal grooves formed on two diametrically opposite faces of the push rod, engaging with two ribs of complementary profile, projecting from the bearing surface of the quick adjustment dial.
  • the cover is mounted to rotate freely on the push rod and retained axially thereon by complementary shapes.
  • the cover is mounted to rotate freely on the quick adjustment wheel and retained axially thereon by complementary shapes.
  • the pipette shown in FIG. 1, according to the invention, is symmetrical with respect to a median plane corresponding to the section plane of FIG. 1.
  • the pipette comprises a pipette body elongated in the direction of a longitudinal axis L, contained in the aforementioned median plane, consisting of a housing 10 and a sampling tube 20 removably linked by a nut 30 engaged on the sampling tube 20 and coming engaged with an external thread provided on the housing 10.
  • the sampling tube 20, symmetrical of revolution about the longitudinal axis L, has from its upper end, adjacent to the housing 10, a succession of stepped internal walls 26, 24, 25 defining three respective conduits of decreasing diameters.
  • the sampling tube 20 receives a piston 40, mounted in translation inside of it.
  • the piston 40 defines, with the conduits formed by the stepped walls 24 and 25, a chamber 22 of variable volume opening onto an orifice 21 located at the lower end of the sampling tube 20.
  • the sampling tube 20 receives at its lower end, from removably, a disposable tubular end piece not shown communicating in a sealed manner with the withdrawal orifice 21 and intended to contain the liquid to be withdrawn and then to be dispensed. This end piece is held by friction on the external surface of the wall 25 of the sampling tube 20.
  • the latter has at its upper end a radial flange 23 which abuts with the nut 30.
  • the piston 40 preferably consisting of a metal cylinder of diameter corresponding to the diameter of the conduit formed by the wall 24, is integral with the lower end of a piston rod 41 mounted in translation in the pipette body.
  • the piston rod 41 has at its upper end an enlarged cylindrical part 48, the end edge of which serves as a bearing surface at one end 51 of a push rod 50 as will be seen hereinafter.
  • the end edge 42 is bordered radially on its periphery by a radial flange 42a projecting.
  • the piston 40 is driven in the direction of the sampling orifice 21 under the action of a pressure exerted manually on the push rod 50, mounted in translation in the housing 10, the end of the push rod 50 opposite to that coming to bear on the edge 42 being provided for this purpose with a push button 70.
  • the piston 40 is returned in displacement in the opposite direction by reaction of springs 43 and 44 acting on the piston rod 41 and the pipette body, up to abut against an axial end 61 of a metal sleeve 60, mounted inside the housing 10 and inside which freely moves in longitudinal translation the aforementioned push rod 50.
  • the sleeve 60 has a threaded external surface cooperating with an internal thread 68 of the housing 10, so that the drive in rotation of the sleeve 60, around the longitudinal axis L causes its displacement along this axis and consequently the adjustment. of the stroke in the opposite direction of the piston 40, therefore adjusting the volume of the sampling chamber 22. More specifically, the piston rod 41 passes through two washers 46 and 47 located in the pipette body, the washer 46 being kept fixed in the pipette body by clamping its periphery between the adjacent ends of the housing 10 and the sampling tube 20, the washer 47 being mounted in translation along the piston rod 41 between the washer 46 and the piston 40 in the conduit formed by the wall 26 of the tube 20.
  • the spring 43 is disposed in the housing 10 around the piston rod 41 and its enlarged cylindrical part 48, comes into abutment at one end against the glue ette radial 42a and in abutment by the other end against the washer 46.
  • the spring 44 is mounted around the piston rod 41 and is interposed axially between the washer 47 and an axial end of a sleeve 45, placed in the conduit formed by the wall 26, between the latter and the piston 40, the other axial end of this sleeve 45 coming, via an O-ring 49, in abutment against the transverse flank delimiting the stepped walls 24 and 26
  • the enlarged cylindrical part 48 of the piston rod 41 has a diameter less than the diameter of the hole in the washer 46 but greater than the diameter of the hole in the washer 47 so as to pass through the washer 46 when the push rod 50 drives the piston rod 41 and then come, by abutment on the washer 47, compress the spring 44.
  • the spring 44 has a stiffness constant much greater than the spring 43 so as to delimit for the pressed operator nt on the push button 70 two successive strokes for the piston, a first stroke, corresponding to the compression of the spring 43 until the enlarged cylindrical part 48 of the piston rod 41 comes up against the washer 47 and to the variation of the volume of the chamber 22 of the quantity to be withdrawn or to be distributed, and a second harder stroke, corresponding to the compression of the spring 44. This latter stroke is used to expel any drops of liquid retained by capillarity in the disposable tip .
  • the sleeve 60 is provided longitudinally, on its outer surface, with a groove 65 to mesh display means 90 of the volume dispensed.
  • these display means 90 housed in the housing 10, comprise a drum of units 91, integral in rotation with the sheath 60, and drums of tens 92 and hundreds 93 driven by the drum of units 91 by means gear teeth 96 provided on the drums and ratchets 97 mounted on an axis 95 parallel to the axis L, in a manner known per se and not described in more detail.
  • a transparent window 94 is provided in the housing 10 to allow the operator to read the volume to be dispensed.
  • the sleeve 60 is provided, at its axial end opposite the end 61 serving as a stop for the edge 42, with a fine adjustment wheel 100, integral in rotation with the sleeve 60.
  • the wheel 100 is located inside 'A housing 13 provided in the housing 10, leading to two access windows 19 used to actuate the wheel 100 from outside the housing 10.
  • the wheel 100 is provided with a braking ring 102 housed in an annular groove provided on the periphery of the wheel 100, forming a brake against the wall 14 of the housing 13.
  • Ejection means are also provided on the pipette to eject the tip after sampling and dispensing a liquid.
  • These ejection means preferably consist, as shown, of a push button 80 mounted in translation in the housing 10, to drive in the direction of the sampling orifice 21 a rod 81, returned in the opposite direction by reaction of a return spring 82, the free end 83 of this rod 81 receiving by friction fitting a curved blade 84, the cross section of which in the form of a portion of a circle centered around the longitudinal axis L substantially matches the external shape of the tube of collection 20.
  • the blade 84 is terminated at its free end 85 by two transverse openings curved around the end of the collection tube 20 for sliding guide the blade 84 on the tube 20 and press on the end edge of a disposable tip engaged on the tube 20 for its ejection.
  • the push rod 50 is stepped along its length to form three parts 50a, 50b, 50c of decreasing respective diameters, extending successively from the end 51 of the push rod 50 acting on edge 42 to push button 70.
  • the part 50a extends from the end 51 over a length greater than that of the sheath 60 to about half the length of the fine adjustment wheel 100.
  • the part 50a is retained at sliding in the sleeve and the wheel 100 by abutment of the transverse flank of the push rod 50 delimiting the parts 50a and 50b against the edge of a retaining ring 101 housed in the wheel 100 and whose internal diameter is greater than the diameter of part 50b but less than the diameter of part 50a.
  • the part 50b preferably has a cylindrical section of revolution around the longitudinal axis L.
  • the part 50c of smaller diameter, carries the push button 70.
  • the part 50a, engaged in the sheath 60 has a cross section of non-symmetrical profile of revolution, preferably hexagonal as shown in Figure 2.
  • the sleeve 60 has, in addition to a central lumen 66, cylindrical of revolution, serving for the passage of the push rod 50, a bore 67 opening out at its axial end 61, to receive a sleeve 110 coaxial with the axis L, the function of which is securing in rotation the push rod 50 and the sheath 60 while allowing a longitudinal displacement of the push rod 50 inside the sheath 60.
  • the sleeve 110 has for this purpose an internal section 111 of profile homologous to the profile of the part 50a of the push rod.
  • FIG. 3 shows a perspective view of a sleeve 110 according to the invention.
  • the sleeve 110 has a cylindrical outer surface 112 of revolution provided with recesses 115 for accommodating an adhesive C for fixing the sleeve in the bore 67 of the sleeve 60.
  • these recesses 115 are constituted by three longitudinal flats formed on the external surface of the sleeve 110, extending axially over only part of the length of the sleeve.
  • the sleeve is made of phenylene polysulphide and the adhesive used is an epoxy adhesive.
  • the push button 70 consists of a quick adjustment wheel 71 coaxial with the part 50c of the push rod 50, provided with means for securing in rotation with the push rod and a cover 72 mounted freely in rotation on the part 50c of the push rod 50, covering the axial end edge 73 of the quick adjustment wheel 71 located opposite the housing 10.
  • the part 50c has a generally cylindrical cross-section of revolution and the means for securing in rotation the wheel 71 with the push rod 50 consist of two longitudinal grooves 54, 55 formed along the diametrically opposite part 50c of the push rod, these longitudinal grooves 54 and 55 engaging with longitudinal ribs of complementary profile projecting from the bearing surface of the quick adjustment wheel 71.
  • the part 50c is provided, as shown in Figure 7, with two annular grooves 58 and 59 axially spaced, cooperating respectively by complementary shapes with annular ribs 74 and 75 projecting from the bearing surfaces of the quick adjustment wheel 71 and the cover 72, for axially retaining these on the part 50c of the push rod 50.
  • the wheel 71 s 'presses on the transverse side of the push rod 50 defining the parts 50b and 50c.
  • the role of the cover 72, mounted free to rotate, is to prevent the push rod from rotating when the operator presses on it and disrupts the volume to be dispensed.
  • the push rod only comprises the stepped parts 50a and 50b, the push button 70 is mounted at the free end of the part 50b, and the cover referenced 72 ′ is mounted free at rotation on the thumbwheel referenced 71 '.
  • the quick adjustment wheel 71 ′ has a radially internal surface 76, serving as a bearing surface on the part 50b, stepped, so as to come axially into abutment on the free end edge 50e of the part 50b.
  • the wheel 71 ' is retained on the push rod by complementarity of shapes between an annular groove 58' provided on the part 50b and an annular rib 74 'projecting from the radially internal surface 76.
  • the mounting of the wheel 71' on the push rod is made by insertion of the wheel 71 'on the push rod 50 and elastic crossing by the annular rib 74', of the region of the rod 50 located between the annular groove 58 'and the end edge 50e.
  • the cover 72 ' is retained axially on the thumb wheel 71' by complementarity of shapes. More specifically, as shown, the wheel 71 'has on its end edge 73' located opposite the housing 10 two cylindrical parts 78 'and 79' stepped and symmetrical of revolution around the longitudinal axis L, serving as bearing surface at the pivoting connection between the wheel 71 'and the cover 72', the latter having two stepped internal surfaces coming to bear respectively on the cylindrical parts 78 'and 79'.
  • the cylindrical part 79 'adjacent to the radially outer knurled surface 77' of the wheel 71 ' joins the cylindrical part 78' by a transverse flank 79'a on which the cover 72 'rests axially.
  • the cover 72 ' is retained axially on the thumbwheel 71' by complementarity of shapes between an annular groove 78'a provided at the base of the cylindrical part 78 'adjacent to the transverse flank 79'a and a annular rib 72'a projecting from the radially inner surface of the cover 72 '.
  • the mounting of the cover 72 'on the wheel 71' leaves a clearance J between the transverse surface of the end edge 73 'adjacent to the knurled surface 77' and the peripheral edge of the cover 72 ', thus facilitating the free rotation of the cover 72 'on the thumb wheel 71'.
  • a pipette according to the invention thanks to the coupling in rotation of the push rod 50 and the sleeve 60 by means of the sleeve 110, allows rapid adjustment of the volume to be dispensed, even by an operator wearing the gloves.

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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)

Description

La présente invention concerne un perfectionnement à une pipette de prélèvement et de distribution de volumes réglables de liquides.The present invention relates to an improvement to a pipette for sampling and dispensing adjustable volumes of liquids.

L'invention concerne plus particulièrement un perfectionnement à une pipette du type comprenant un corps de pipette allongé selon un axe longitudinal et un piston monté à translation selon cet axe à l'intérieur dudit corps de pipette pour définir une chambre de volume variable débouchant sur un orifice de prélèvement, le piston étant entraîné sur une course limitée en direction de l'orifice de prélèvement au moyen d'une pression exercée manuellement sur une tige de poussée montée à translation dans le corps de pipette et en sens inverse par réaction de moyens de rappel élastiques jusqu'à venir en butée contre une extrémité axiale d'un fourreau métallique s'étendant à l'intérieur du corps de pipette selon ledit axe longitudinal. Le fourreau est fileté extérieurement et coopère par vissage avec un filetage intérieur du corps de pipette de façon à se déplacer longitudinalement lorsqu'entraîné en rotation, en vue de régler la course en sens inverse du piston et le volume de la chambre. En outre, le fourreau est apte à être entraîné en rotation par une molette de réglage fin solidaire de celui-ci et engrène des moyens d'affichage du volume à distribuer. La tige de poussée est montée à translation dans le fourreau.The invention relates more particularly to an improvement to a pipette of the type comprising a pipette body elongated along a longitudinal axis and a piston mounted in translation along this axis inside said pipette body to define a chamber of variable volume opening onto a sampling port, the piston being driven on a limited stroke in the direction of the sampling port by means of a pressure exerted manually on a push rod mounted in translation in the pipette body and in the opposite direction by reaction of means of elastic return until it abuts against an axial end of a metal sleeve extending inside the pipette body along said longitudinal axis. The sleeve is externally threaded and cooperates by screwing with an internal thread of the pipette body so as to move longitudinally when rotated, in order to adjust the stroke in the opposite direction of the piston and the volume of the chamber. In addition, the sheath is able to be driven in rotation by a fine adjustment wheel secured thereto and meshes with means for displaying the volume to be dispensed. The push rod is mounted in translation in the sleeve.

Dans une telle pipette, le réglage du volume à distribuer s'effectue habituellement à l'aide du pouce et de l'index, ces deux doigts s'appliquant chacun sur des faces opposées de la molette de réglage fin, accessibles depuis l'extérieur à la faveur de fenêtres prévues sur deux faces opposées du corps de pipette. La molette de réglage fin permet un réglage précis du volume à distribuer mais en contre-partie ne peut être entraînée, à chaque action du pouce et de l'index, que sur un angle de rotation limité lié à la largeur des fenêtres prévues sur le corps de pipette. Or, dans certains cas, I'opérateur utilisant la pipette doit distribuer successivement des volumes extrêmes, ce qui nécessite pour le réglage de la pipette aux valeurs correspondantes d'entraîner en rotation le fourreau sur un nombre de tours élevé et par conséquent d'effectuer un grand nombre d'actions sur la molette à l'aide du pouce et de l'index. Outre l'inconvénient que représente le caractère fastidieux du réglage de la pipette à des valeurs éloignées, il est fréquent, lorsque l'opérateur porte des gants, que la peau de ceux-ci se coince dans le jeu présent entre la molette et le bord des fenêtres ménagées sur le corps de pipette, et se déchire.In such a pipette, the volume to be dispensed is usually adjusted using the thumb and forefinger, these two fingers each applying to opposite sides of the fine adjustment wheel, accessible from the outside. through windows provided on two opposite sides of the pipette body. The fine adjustment wheel allows precise adjustment of the volume to be dispensed but in return can only be driven, with each action of the thumb and forefinger, on a limited angle of rotation linked to the width of the windows provided on the pipette body. However, in certain cases, the operator using the pipette must successively distribute extreme volumes, which requires, for the adjustment of the pipette to the corresponding values, to rotate the sheath over a high number of revolutions and therefore to perform a large number of actions on the dial using the thumb and forefinger. In addition to the drawback represented by the tedious nature of adjusting the pipette to values distant, it is frequent, when the operator wears gloves, that the skin of these gets stuck in the clearance present between the wheel and the edge of the windows formed on the pipette body, and tears.

La présente invention a pour objet une pipette perfectionnée, remédiant aux inconvénients précités, notamment qui soit réglable de manière aisée par un opérateur portant des gants et présente une possibilité de réglage rapide du volume à distribuer.The present invention relates to an improved pipette, overcoming the aforementioned drawbacks, in particular which is easily adjustable by an operator wearing gloves and presents a possibility of rapid adjustment of the volume to be dispensed.

Conformément à une première caractéristique de l'invention, la tige de poussée présente sur une partie au moins de sa longueur une section non symétrique de révolution, et le fourreau est rendu solidaire, par des moyens de solidarisation, d'un manchon coaxial au fourreau et dans lequel la partie de section non symétrique de révolution de la tige de poussée est également engagée, le manchon présentant une section interne de profil complémentaire ou homologue de ladite partie de tige de poussée de façon à solidariser en rotation la tige de poussée et le fourreau en vue d'un réglage rapide du volume à distribuer, tout en autorisant un déplacement longitudinal de la tige de poussée à l'intérieur du fourreau.According to a first characteristic of the invention, the push rod has on a part at least of its length a non-symmetrical section of revolution, and the sleeve is made integral, by means of attachment, with a sleeve coaxial with the sleeve and in which the part of non-symmetrical section of revolution of the push rod is also engaged, the sleeve having an internal section of complementary or homologous profile of said part of push rod so as to secure in rotation the push rod and the sleeve for rapid adjustment of the volume to be dispensed, while allowing longitudinal movement of the push rod inside the sleeve.

De préférence, le manchon est collé à l'intérieur du fourreau.Preferably, the sleeve is glued inside the sheath.

Dans une réalisation préférée de l'invention, le manchon est reçu dans un alésage débouchant sur l'extrémité axiale du fourreau servant de butée de limitation de course en sens inverse du piston, la surface radialement externe du manchon présentant des renfoncements pour loger une colle de fixation dans l'alésage du fourreau.In a preferred embodiment of the invention, the sleeve is received in a bore opening on the axial end of the sleeve serving as a stop for limiting the stroke in the opposite direction of the piston, the radially external surface of the sleeve having recesses for accommodating an adhesive. fixing in the bore of the sleeve.

Conformément à une caractéristique avantageuse de l'invention, la tige de poussée présente une partie située hors du corps de pipette munie d'un bouton-poussoir comprenant une molette de réglage rapide munie de moyens de solidarisation en rotation avec ladite tige de poussée et un couvercle monté libre en rotation autour dudit axe longitudinal, couvrant la tranche d'extrémité axiale de la molette située à l'opposé du corps de pipette.In accordance with an advantageous characteristic of the invention, the push rod has a part situated outside the pipette body provided with a push button comprising a quick adjustment wheel provided with means for securing in rotation with said push rod and a cover mounted free to rotate about said longitudinal axis, covering the axial end edge of the wheel located opposite the pipette body.

De préférence, les moyens de solidarisation en rotation de la molette de réglage rapide sur la tige de poussée comprennent deux rainures longitudinales formées sur deux faces diamétralement opposées de la tige de poussée, venant en prise avec deux nervures de profil complémentaire, formant saillie sur la surface de portée de la molette de réglage rapide.Preferably, the means for securing in rotation the rapid adjustment wheel on the push rod comprise two longitudinal grooves formed on two diametrically opposite faces of the push rod, engaging with two ribs of complementary profile, projecting from the bearing surface of the quick adjustment dial.

Dans une première réalisation, le couvercle est monté libre en rotation sur la tige de poussée et retenu axialement sur celle-ci par complémentarité de formes.In a first embodiment, the cover is mounted to rotate freely on the push rod and retained axially thereon by complementary shapes.

Dans une deuxième réalisation, le couvercle est monté libre en rotation sur la molette de réglage rapide et retenu axialement sur celle-ci par complémentarité de formes.In a second embodiment, the cover is mounted to rotate freely on the quick adjustment wheel and retained axially thereon by complementary shapes.

D'autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description détaillée qui va suivre, d'un exemple de réalisation non limitatif de l'invention, et à l'examen du dessin annexé sur lequel :

  • la figure 1 est une vue d'ensemble en coupe longitudinale d'une pipette conforme à l'invention,
  • la figure 2 est une section transversale partielle prise au niveau du repère II-II de la figure 1,
  • la figure 3 est une vue en perspective d'un manchon conforme à l'invention,
  • la figure 4 est une vue en coupe prise dans un plan médian de symétrie pour le manchon représenté sur la figure 3, perpendiculaire à l'axe longitudinal de celui-ci,
  • la figure 5 est une vue en coupe longitudinale, à échelle agrandie, montrant l'assemblage du manchon à l'intérieur du fourreau,
  • la figure 6 est une section transversale de la tige de poussée selon le trait de coupe VI-VI de la figure 1,
  • la figure 7 est une vue montrant l'assemblage du bouton poussoir sur la tige de poussée selon une première réalisation,
  • la figure 8 est une vue en coupe longitudinale d'une variante de réalisation de bouton poussoir conforme à l'invention.
Other characteristics and advantages of the present invention will appear on reading the detailed description which follows, of a non-limiting exemplary embodiment of the invention, and on examining the appended drawing in which:
  • FIG. 1 is an overall view in longitudinal section of a pipette according to the invention,
  • FIG. 2 is a partial cross-section taken at the level of the reference II-II in FIG. 1,
  • FIG. 3 is a perspective view of a sleeve according to the invention,
  • FIG. 4 is a sectional view taken in a median plane of symmetry for the sleeve shown in FIG. 3, perpendicular to the longitudinal axis of the latter,
  • FIG. 5 is a view in longitudinal section, on an enlarged scale, showing the assembly of the sleeve inside the sheath,
  • FIG. 6 is a cross section of the push rod along the section line VI-VI of FIG. 1,
  • FIG. 7 is a view showing the assembly of the push button on the push rod according to a first embodiment,
  • Figure 8 is a longitudinal sectional view of an alternative embodiment of a push button according to the invention.

La pipette représentée sur la figure 1, conforme à l'invention, est symétrique par rapport à un plan médian correspondant au plan de coupe de la figure 1. La pipette comprend un corps de pipette allongé selon la direction d'un axe longitudinal L, contenu dans le plan médian précité, constitué d'un boîtier 10 et d'un tube de prélèvement 20 liés de façon amovible par un écrou 30 engagé sur le tube de prélèvement 20 et venant en prise avec un filetage externe prévu sur le boîtier 10. Le tube de prélèvement 20, symétrique de révolution autour de l'axe longitudinal L, présente depuis son extrémité supérieure, adjacente au boîtier 10, une succession de parois internes étagées 26, 24, 25 définissant trois conduits respectifs de diamètres décroissants. Le tube de prélèvement 20 accueille un piston 40, monté à translation à l'intérieur de celui-ci. Le piston 40 définit avec les conduits formés par les parois étagées 24 et 25 une chambre 22 de volume variable débouchant sur un orifice 21 situé à l'extrémité inférieure du tube de prélèvement 20. Le tube de prélèvement 20 reçoit à son extrémité inférieure, de façon amovible, un embout tubulaire jetable non représenté communiquant de façon étanche avec l'orifice de prélèvement 21 et destiné à contenir le liquide à prélever puis à distribuer. Cet embout est maintenu par friction sur la surface externe de la paroi 25 du tube de prélèvement 20. Ce dernier présentè à son extrémité supérieure une collerette radiale 23 en butée avec l'écrou 30.The pipette shown in FIG. 1, according to the invention, is symmetrical with respect to a median plane corresponding to the section plane of FIG. 1. The pipette comprises a pipette body elongated in the direction of a longitudinal axis L, contained in the aforementioned median plane, consisting of a housing 10 and a sampling tube 20 removably linked by a nut 30 engaged on the sampling tube 20 and coming engaged with an external thread provided on the housing 10. The sampling tube 20, symmetrical of revolution about the longitudinal axis L, has from its upper end, adjacent to the housing 10, a succession of stepped internal walls 26, 24, 25 defining three respective conduits of decreasing diameters. The sampling tube 20 receives a piston 40, mounted in translation inside of it. The piston 40 defines, with the conduits formed by the stepped walls 24 and 25, a chamber 22 of variable volume opening onto an orifice 21 located at the lower end of the sampling tube 20. The sampling tube 20 receives at its lower end, from removably, a disposable tubular end piece not shown communicating in a sealed manner with the withdrawal orifice 21 and intended to contain the liquid to be withdrawn and then to be dispensed. This end piece is held by friction on the external surface of the wall 25 of the sampling tube 20. The latter has at its upper end a radial flange 23 which abuts with the nut 30.

Le piston 40, constitué de préférence d'un cylindre métallique de diamètre correspondant au diamètre du conduit formé par la paroi 24, est solidaire de l'extrémité inférieure d'une tige de piston 41 montée à translation dans le corps de pipette. La tige de piston 41 présente à son extrémité supérieure une partie cylindrique élargie 48, dont la tranche d'extrémité 42 sert de surface d'appui à une extrémité 51 d'une tige de poussée 50 comme cela va être vu dans la suite. La tranche d'extrémité 42 est bordée radialement sur sa périphérie par une collerette radiale 42a formant saillie. Le piston 40 est entraîné en direction de l'orifice de prélèvement 21 sous l'action d'une pression exercée manuellement sur la tige de poussée 50, montée à translation dans le boîtier 10, l'extrémité de la tige de poussée 50 opposée à celle venant en appui sur la tranche 42 étant munie à cet effet d'un bouton poussoir 70. Le piston 40 est rappelé en déplacement en sens inverse par réaction de ressorts 43 et 44 agissant sur la tige de piston 41 et le corps de pipette, jusqu'à venir buter contre une extrémité axiale 61 d'un fourreau 60 métallique, monté à l'intérieur du boîtier 10 et à l'intérieur duquel se déplace librement en translation longitudinale la tige de poussée 50 précitée.The piston 40, preferably consisting of a metal cylinder of diameter corresponding to the diameter of the conduit formed by the wall 24, is integral with the lower end of a piston rod 41 mounted in translation in the pipette body. The piston rod 41 has at its upper end an enlarged cylindrical part 48, the end edge of which serves as a bearing surface at one end 51 of a push rod 50 as will be seen hereinafter. The end edge 42 is bordered radially on its periphery by a radial flange 42a projecting. The piston 40 is driven in the direction of the sampling orifice 21 under the action of a pressure exerted manually on the push rod 50, mounted in translation in the housing 10, the end of the push rod 50 opposite to that coming to bear on the edge 42 being provided for this purpose with a push button 70. The piston 40 is returned in displacement in the opposite direction by reaction of springs 43 and 44 acting on the piston rod 41 and the pipette body, up to abut against an axial end 61 of a metal sleeve 60, mounted inside the housing 10 and inside which freely moves in longitudinal translation the aforementioned push rod 50.

Le fourreau 60 présente une surface externe filetée coopérant avec un filetage intérieur 68 du boîtier 10, de sorte que l'entraînement en rotation du fourreau 60, autour de l'axe longitudinal L provoque son déplacement le long de cet axe et par conséquent le réglage de la course en sens inverse du piston 40, donc le réglage du volume de la chambre de prélèvement 22. Plus précisément, la tige de piston 41 traverse deux rondelles 46 et 47 situées dans le corps de pipette, la rondelle 46 étant maintenue fixe dans le corps de pipette par serrage de sa périphérie entre les extrémités adjacentes du boîtier 10 et du tube de prélèvement 20, la rondelle 47 étant montée à translation le long de la tige de piston 41 entre la rondelle 46 et le piston 40 dans le conduit formé par la paroi 26 du tube 20. Le ressort 43 est disposé dans le boîtier 10 autour de la tige de piston 41 et de sa partie cylindrique élargie 48, vient en butée par une extrémité contre la collerette radiale 42a et en butée par l'autre extrémité contre la rondelle 46. Le ressort 44 est monté autour de la tige de piston 41 et s'interpose axialement entre la rondelle 47 et une extrémité axiale d'une douille 45, placée dans le conduit formé par la paroi 26, entre cette dernière et le piston 40, l'autre extrémité axiale de cette douille 45 venant, par l'intermédiaire d'un joint torique 49, en butée contre le flanc transversal délimitant les parois étagées 24 et 26. La partie cylindrique élargie 48 de la tige de piston 41 présente un diamètre inférieur au diamètre de la lumière de la rondelle 46 mais supérieur au diamètre de la lumière de la rondelle 47 de façon à franchir la rondelle 46 lorsque la tige de poussée 50 entraîne la tige de piston 41 et venir ensuite, par butée sur la rondelle 47, comprimer le ressort 44. Le ressort 44 présente une constante de raideur beaucoup plus grande que le ressort 43 de façon à délimiter pour l'opérateur appuyant sur le bouton poussoir 70 deux courses successives pour le piston, une première course, correspondant à la compression du ressort 43 jusqu'à ce que la partie cylindrique élargie 48 de la tige de piston 41 vienne buter sur la rondelle 47 et à la variation du volume de la chambre 22 de la quantité à prélever ou à distribuer, et une deuxième course plus dure, correspondant à la compression du ressort 44. Cette dernière course sert à chasser d'éventuelles gouttes de liquide retenues par capillarité dans l'embout jetable.The sleeve 60 has a threaded external surface cooperating with an internal thread 68 of the housing 10, so that the drive in rotation of the sleeve 60, around the longitudinal axis L causes its displacement along this axis and consequently the adjustment. of the stroke in the opposite direction of the piston 40, therefore adjusting the volume of the sampling chamber 22. More specifically, the piston rod 41 passes through two washers 46 and 47 located in the pipette body, the washer 46 being kept fixed in the pipette body by clamping its periphery between the adjacent ends of the housing 10 and the sampling tube 20, the washer 47 being mounted in translation along the piston rod 41 between the washer 46 and the piston 40 in the conduit formed by the wall 26 of the tube 20. The spring 43 is disposed in the housing 10 around the piston rod 41 and its enlarged cylindrical part 48, comes into abutment at one end against the glue ette radial 42a and in abutment by the other end against the washer 46. The spring 44 is mounted around the piston rod 41 and is interposed axially between the washer 47 and an axial end of a sleeve 45, placed in the conduit formed by the wall 26, between the latter and the piston 40, the other axial end of this sleeve 45 coming, via an O-ring 49, in abutment against the transverse flank delimiting the stepped walls 24 and 26 The enlarged cylindrical part 48 of the piston rod 41 has a diameter less than the diameter of the hole in the washer 46 but greater than the diameter of the hole in the washer 47 so as to pass through the washer 46 when the push rod 50 drives the piston rod 41 and then come, by abutment on the washer 47, compress the spring 44. The spring 44 has a stiffness constant much greater than the spring 43 so as to delimit for the pressed operator nt on the push button 70 two successive strokes for the piston, a first stroke, corresponding to the compression of the spring 43 until the enlarged cylindrical part 48 of the piston rod 41 comes up against the washer 47 and to the variation of the volume of the chamber 22 of the quantity to be withdrawn or to be distributed, and a second harder stroke, corresponding to the compression of the spring 44. This latter stroke is used to expel any drops of liquid retained by capillarity in the disposable tip .

Comme cela apparaît sur la section transversale de la figure 2, le fourreau 60 est muni longitudinalement, sur sa surface externe, d'une rainure 65 pour engréner des moyens d'affichage 90 du volume distribué. Plus précisément, ces moyens d'affichage 90, logés dans le boîtier 10, comprennent un tambour d'unités 91, solidaire en rotation du fourreau 60, et des tambours de dizaines 92 et de centaines 93 entraînés par le tambour des unités 91 au moyen de dents d'engrenage 96 prévues sur les tambours et de rochets 97 montés sur un axe 95 parallèle à l'axe L, de façon connue en soi et non décrite plus en détail. Une fenêtre transparente 94 est ménagée dans le boîtier 10 pour permettre la lecture par l'opérateur du volume à distribuer.As shown in the cross section of Figure 2, the sleeve 60 is provided longitudinally, on its outer surface, with a groove 65 to mesh display means 90 of the volume dispensed. More specifically, these display means 90, housed in the housing 10, comprise a drum of units 91, integral in rotation with the sheath 60, and drums of tens 92 and hundreds 93 driven by the drum of units 91 by means gear teeth 96 provided on the drums and ratchets 97 mounted on an axis 95 parallel to the axis L, in a manner known per se and not described in more detail. A transparent window 94 is provided in the housing 10 to allow the operator to read the volume to be dispensed.

Le fourreau 60 est muni, à son extrémité axiale opposée à l'extrémité 61 servant de butée à la tranche 42, d'une molette de réglage fin 100, solidaire en rotation du fourreau 60. La molette 100 est située à l'intérieur d'un logement 13 prévu dans le boîtier 10, débouchant sur deux fenêtres d'accès 19 servant à actionner la molette 100 depuis l'extérieur du boîtier 10. La molette 100 est munie d'une bague de freinage 102 logée dans une gorge annulaire prévue sur la périphérie de la molette 100, formant frein contre la paroi 14 du logement 13.The sleeve 60 is provided, at its axial end opposite the end 61 serving as a stop for the edge 42, with a fine adjustment wheel 100, integral in rotation with the sleeve 60. The wheel 100 is located inside 'A housing 13 provided in the housing 10, leading to two access windows 19 used to actuate the wheel 100 from outside the housing 10. The wheel 100 is provided with a braking ring 102 housed in an annular groove provided on the periphery of the wheel 100, forming a brake against the wall 14 of the housing 13.

Des moyens d'éjection sont en outre prévus sur la pipette pour éjecter l'embout après prélèvement et distribution d'un liquide. Ces moyens d'éjection sont de préférence constitués, comme représenté, d'un bouton poussoir 80 monté à translation dans le boîtier 10, pour entraîner en direction de l'orifice de prélèvement 21 une tige 81, rappelée en sens inverse par réaction d'un ressort de rappel 82, l'extrémité libre 83 de cette tige 81 recevant par emmanchement à friction une lame incurvée 84, dont la section transversale en forme de portion de cercle centrée autour de l'axe longitudinal L épouse sensiblement la forme externe du tube de prélèvement 20. La lame 84 est terminée à son extrémité libre 85 par deux épanouissements transversaux recourbés autour de l'extrémité du tube de prélèvement 20 pour guider en coulissement la lame 84 sur le tube 20 et appuyer sur la tranche d'extrémité d'un embout jetable engagé sur le tube 20 en vue de son éjection.Ejection means are also provided on the pipette to eject the tip after sampling and dispensing a liquid. These ejection means preferably consist, as shown, of a push button 80 mounted in translation in the housing 10, to drive in the direction of the sampling orifice 21 a rod 81, returned in the opposite direction by reaction of a return spring 82, the free end 83 of this rod 81 receiving by friction fitting a curved blade 84, the cross section of which in the form of a portion of a circle centered around the longitudinal axis L substantially matches the external shape of the tube of collection 20. The blade 84 is terminated at its free end 85 by two transverse openings curved around the end of the collection tube 20 for sliding guide the blade 84 on the tube 20 and press on the end edge of a disposable tip engaged on the tube 20 for its ejection.

Conformément à une caractéristique avantageuse de l'invention, la tige de poussée 50 est étagée selon sa longueur pour former trois parties 50a, 50b, 50c de diamètres respectifs décroissants, s'étendant successivement depuis l'extrémité 51 de la tige de poussée 50 agissant sur la tranche 42 jusqu'au bouton poussoir 70.According to an advantageous characteristic of the invention, the push rod 50 is stepped along its length to form three parts 50a, 50b, 50c of decreasing respective diameters, extending successively from the end 51 of the push rod 50 acting on edge 42 to push button 70.

Plus précisément, la partie 50a, de plus grand diamètre, s'étend depuis l'extrémité 51 sur une longueur supérieure à celle du fourreau 60 jusqu'à mi-longueur environ de la molette de réglage fin 100. La partie 50a est retenue en coulissement dans le fourreau et la molette 100 par butée du flanc transversal de la tige de poussée 50 délimitant les parties 50a et 50b contre le rebord d'une bague de retenue 101 logée dans la molette 100 et dont le diamètre interne est supérieur au diamètre de la partie 50b mais inférieur au diamètre de la partie 50a. La partie 50b présente de préférence une section cylindrique de révolution autour de l'axe longitudinal L.More specifically, the part 50a, of larger diameter, extends from the end 51 over a length greater than that of the sheath 60 to about half the length of the fine adjustment wheel 100. The part 50a is retained at sliding in the sleeve and the wheel 100 by abutment of the transverse flank of the push rod 50 delimiting the parts 50a and 50b against the edge of a retaining ring 101 housed in the wheel 100 and whose internal diameter is greater than the diameter of part 50b but less than the diameter of part 50a. The part 50b preferably has a cylindrical section of revolution around the longitudinal axis L.

La partie 50c, de plus petit diamètre, porte le bouton poussoir 70.The part 50c, of smaller diameter, carries the push button 70.

Conformément à l'invention, la partie 50a, engagée dans le fourreau 60, présente une section transversale de profil non symétrique de révolution, de préférence hexagonal comme représenté sur la figure 2. On se reporte maintenant plus particulièrement aux figures 3 à 5. Le fourreau 60 présente, outre une lumière centrale 66, cylindrique de révolution, servant au passage de la tige de poussée 50, un alésage 67 débouchant sur son extrémité axiale 61, pour recevoir un manchon 110 coaxial à l'axe L, dont la fonction est de solidariser en rotation la tige de poussée 50 et le fourreau 60 tout en permettant un déplacement longitudinal de la tige de poussée 50 à l'intérieur du fourreau 60. Le manchon 110 présente à cet effet une section interne 111 de profil homologue du profil de la partie 50a de la tige de poussée. On a représenté en perspective sur la figure 3 un manchon 110 conforme à l'invention. Le manchon 110 présente une surface externe 112 cylindrique de révolution munie de renfoncements 115 pour loger une colle C de fixation du manchon dans l'alésage 67 du fourreau 60. Avantageusement, comme représenté, ces renfoncements 115 sont constitués par trois méplats longitudinaux formés sur la surface externe du manchon 110, s'étendant axialement sur une partie seulement de la longueur du manchon. Ces méplats sont répartis angulairement sur la périphérie du manchon, s'étendent angulairement chacun sur un secteur angulaire voisin de 60° et symétriquement de part et d'autre d'un plan de symétrie transversal P pour le manchon. De préférence, le manchon est réalisé en polysulfure de phénylène et la colle utilisée est une colle époxy.According to the invention, the part 50a, engaged in the sheath 60, has a cross section of non-symmetrical profile of revolution, preferably hexagonal as shown in Figure 2. We now refer more particularly to Figures 3 to 5. The sleeve 60 has, in addition to a central lumen 66, cylindrical of revolution, serving for the passage of the push rod 50, a bore 67 opening out at its axial end 61, to receive a sleeve 110 coaxial with the axis L, the function of which is securing in rotation the push rod 50 and the sheath 60 while allowing a longitudinal displacement of the push rod 50 inside the sheath 60. The sleeve 110 has for this purpose an internal section 111 of profile homologous to the profile of the part 50a of the push rod. FIG. 3 shows a perspective view of a sleeve 110 according to the invention. The sleeve 110 has a cylindrical outer surface 112 of revolution provided with recesses 115 for accommodating an adhesive C for fixing the sleeve in the bore 67 of the sleeve 60. Advantageously, as shown, these recesses 115 are constituted by three longitudinal flats formed on the external surface of the sleeve 110, extending axially over only part of the length of the sleeve. These flats are distributed angularly on the periphery of the sleeve, each extend angularly over an angular sector close to 60 ° and symmetrically on either side of a transverse plane of symmetry P for the sleeve. Preferably, the sleeve is made of phenylene polysulphide and the adhesive used is an epoxy adhesive.

Pour le montage du manchon 110 à l'intérieur du fourreau 60, de la colle C est disposée dans les renfoncements 115 puis le manchon est introduit dans l'alésage 67 du fourreau 60. On notera qu'en cas de décollement de la colle et du manchon, la fonction de solidarisation en rotation de la tige de poussée et du fourreau est toujours assurée tant que la colle reste en prise sur l'alésage 67 du fourreau 60, par effet de coin de la colle sur les renfoncements 115 du manchon 110. On notera également que le manchon 110 est positionné dans l'alésage 67 légèrement en retrait de l'extrémité axiale 61 du fourreau.For mounting the sleeve 110 inside the sleeve 60, glue C is placed in the recesses 115 and then the sleeve is introduced into the bore 67 of the sleeve 60. It will be noted that in the event of the adhesive coming off and of the sleeve, the function of securing in rotation the push rod and the sleeve is always ensured as long as the adhesive remains in engagement on the bore 67 of the sleeve 60, by wedge effect of the adhesive on the recesses 115 of the sleeve 110 It will also be noted that the sleeve 110 is positioned in the bore 67 slightly set back from the axial end 61 of the sleeve.

Dans la réalisation représentée sur les figures 1 et 7, le bouton poussoir 70 est constitué d'une molette de réglage rapide 71 coaxiale à la partie 50c de la tige de poussée 50, munie de moyens de solidarisation en rotation avec la tige de poussée et d'un couvercle 72 monté libre en rotation sur la partie 50c de la tige de poussée 50, couvrant la tranche d'extrémité axiale 73 de la molette de réglage rapide 71 située à l'opposé du boîtier 10.In the embodiment shown in FIGS. 1 and 7, the push button 70 consists of a quick adjustment wheel 71 coaxial with the part 50c of the push rod 50, provided with means for securing in rotation with the push rod and a cover 72 mounted freely in rotation on the part 50c of the push rod 50, covering the axial end edge 73 of the quick adjustment wheel 71 located opposite the housing 10.

De préférence, comme représenté sur les figures 6 et 7, la partie 50c présente une section transversale généralement cylindrique de révolution et les moyens de solidarisation en rotation de la molette 71 avec la tige de poussée 50 sont constitués de deux rainures longitudinales 54, 55 formées le long de la partie 50c de la tige de poussée, diamétralement opposées, ces rainures longitudinales 54 et 55 venant en prise avec des nervures longitudinales de profil complémentaires formant saillie sur la surface de portée de la molette de réglage rapide 71. La partie 50c est munie, comme représenté sur la figure 7, de deux gorges annulaires 58 et 59 axialement espacées, coopérant respectivement par complémentarité de formes avec des nervures annulaires 74 et 75 formant saillie sur les surfaces de portée de la molette de réglage rapide 71 et du couvercle 72, pour retenir axialement ceux-ci sur la partie 50c de la tige de poussée 50. Une fois montée sur la partie 50c de la tige de poussée 50, la molette 71 s'appuie sur le flanc transversal de la tige de poussée 50 délimitant les parties 50b et 50c. Le rôle du couvercle 72, monté libre à rotation, est d'éviter que la tige de poussée ne tourne lorsque l'opérateur appuie sur celle-ci et vienne dérégler le volume à distribuer.Preferably, as shown in FIGS. 6 and 7, the part 50c has a generally cylindrical cross-section of revolution and the means for securing in rotation the wheel 71 with the push rod 50 consist of two longitudinal grooves 54, 55 formed along the diametrically opposite part 50c of the push rod, these longitudinal grooves 54 and 55 engaging with longitudinal ribs of complementary profile projecting from the bearing surface of the quick adjustment wheel 71. The part 50c is provided, as shown in Figure 7, with two annular grooves 58 and 59 axially spaced, cooperating respectively by complementary shapes with annular ribs 74 and 75 projecting from the bearing surfaces of the quick adjustment wheel 71 and the cover 72, for axially retaining these on the part 50c of the push rod 50. Once mounted on the part 50c of the push rod 50, the wheel 71 s 'presses on the transverse side of the push rod 50 defining the parts 50b and 50c. The role of the cover 72, mounted free to rotate, is to prevent the push rod from rotating when the operator presses on it and disrupts the volume to be dispensed.

En variante, comme représenté sur la figure 8, la tige de poussée ne comporte que les parties étagées 50a et 50b, le bouton poussoir 70 est monté à l'extrémité libre de la partie 50b, et le couvercle référencé 72' est monté libre à rotation sur la molette référencée 71'.As a variant, as shown in FIG. 8, the push rod only comprises the stepped parts 50a and 50b, the push button 70 is mounted at the free end of the part 50b, and the cover referenced 72 ′ is mounted free at rotation on the thumbwheel referenced 71 '.

Plus précisément, la molette de réglage rapide 71' présente une surface radialement interne 76, servant de surface de portée sur la partie 50b, étagée, de façon à venir axialement en butée sur la tranche d'extrémité libre 50e de la partie 50b. La molette 71' est retenue sur la tige de poussée par complémentarité de formes entre une gorge annulaire 58' prévue sur la partie 50b et une nervure annulaire 74' formant saillie sur la surface radialement interne 76. Le montage de la molette 71' sur la tige de poussée se fait par insertion de la molette 71' sur la tige de poussée 50 et franchissement élastique par la nervure annulaire 74', de la région de la tige 50 située entre la gorge annulaire 58' et la tranche d'extrémité 50e. Le couvercle 72' est retenu axialement sur la molette 71' par complémentarité de formes. Plus précisément, comme représenté, la molette 71' présente sur sa tranche d'extrémité 73' située à l'opposé du boîtier 10 deux parties cylindriques 78' et 79' étagées et symétriques de révolution autour de l'axe longitudinal L, servant de surface de portée à la liaison pivotante entre la molette 71' et le couvercle 72', ce dernier présentant deux surfaces internes étagées venant respectivement s'appuyer sur les parties cylindriques 78' et 79'. La partie cylindrique 79' adjacente à la surface radialement externe moletée 77' de la molette 71' rejoint la partie cylindrique 78' par un flanc transversal 79'a sur lequel s'appuie axialement le couvercle 72'.More specifically, the quick adjustment wheel 71 ′ has a radially internal surface 76, serving as a bearing surface on the part 50b, stepped, so as to come axially into abutment on the free end edge 50e of the part 50b. The wheel 71 'is retained on the push rod by complementarity of shapes between an annular groove 58' provided on the part 50b and an annular rib 74 'projecting from the radially internal surface 76. The mounting of the wheel 71' on the push rod is made by insertion of the wheel 71 'on the push rod 50 and elastic crossing by the annular rib 74', of the region of the rod 50 located between the annular groove 58 'and the end edge 50e. The cover 72 'is retained axially on the thumb wheel 71' by complementarity of shapes. More specifically, as shown, the wheel 71 'has on its end edge 73' located opposite the housing 10 two cylindrical parts 78 'and 79' stepped and symmetrical of revolution around the longitudinal axis L, serving as bearing surface at the pivoting connection between the wheel 71 'and the cover 72', the latter having two stepped internal surfaces coming to bear respectively on the cylindrical parts 78 'and 79'. The cylindrical part 79 'adjacent to the radially outer knurled surface 77' of the wheel 71 'joins the cylindrical part 78' by a transverse flank 79'a on which the cover 72 'rests axially.

Le couvercle 72' est retenu axialement sur la molette 71' par complémentarité de formes entre une gorge annulaire 78'a prévue à la base de la partie cylindrique 78' adjacente au flanc transversal 79'a et une nervure annulaire 72'a formant saillie sur la surface radialement interne du couvercle 72'. De préférence, le montage du couvercle 72' sur la molette 71' ménage un jeu J entre la surface transversale de la tranche d'extrémité 73' adjacente à la surface moletée 77' et le bord périphérique du couvercle 72', facilitant ainsi la libre rotation du couvercle 72' sur la molette 71'.The cover 72 'is retained axially on the thumbwheel 71' by complementarity of shapes between an annular groove 78'a provided at the base of the cylindrical part 78 'adjacent to the transverse flank 79'a and a annular rib 72'a projecting from the radially inner surface of the cover 72 '. Preferably, the mounting of the cover 72 'on the wheel 71' leaves a clearance J between the transverse surface of the end edge 73 'adjacent to the knurled surface 77' and the peripheral edge of the cover 72 ', thus facilitating the free rotation of the cover 72 'on the thumb wheel 71'.

Finalement, une pipette conforme à l'invention, grâce au couplage en rotation de la tige de poussée 50 et du fourreau 60 au moyen du manchon 110, permet un réglage rapide du volume à distribuer, même par un opérateur portant les gants.Finally, a pipette according to the invention, thanks to the coupling in rotation of the push rod 50 and the sleeve 60 by means of the sleeve 110, allows rapid adjustment of the volume to be dispensed, even by an operator wearing the gloves.

Claims (12)

  1. Pipette for sampling and distributing variable volumes of liquid, of the type comprising a pipette body (10, 20) extending along a longitudinal axis (L) and a piston (40) mounted in sliding fashion along said axis inside said pipette body so as to define a chamber of variable volume (22) emerging at a sampling orifice (21), said piston (40) being driven over a limited distance of travel in the direction of the sampling orifice (21) by means of pressure manually exerted on a push rod (50) mounted in sliding fashion in the pipette body, and in the opposite direction by the reaction of elastic return means (43, 44) until it abuts against an axial extremity (61) of a metal sheath (60) extending along said longitudinal axis inside the pipette body, the sheath having an external thread which works by screwing with a thread (68) inside the pipette body in such a way as to move the sheath longitudinally when driven in rotation, in order to adjust the distance of travel of the piston (40) in the opposite direction and the volume of the chamber, the sheath (60) capable of being driven in rotation by a fine adjustment knob (100) integral with the sheath, said sheath (60) also intermeshing with means (90) for displaying the volume to be dispensed, the push rod (50) being mounted in sliding fashion in the sheath (60), characterised in that the push rod (50) has a non-symmetrical cross-section of revolution over at least a portion of its length, the sheath (60) being rigidly locked by looking means to a sleeve (110) arranged coaxially with respect to the sheath (60) and in which the portion of the push rod (50) with a non-symmetric cross-section of revolution is also engaged, the sleeve (110) having an internal cross-section of profile (111) complementary or homologous to said portion of the push rod so as to rigidly lock the push rod (50) and sheath (60) in rotation to provide rapid adjustment of the volume to be dispensed while allowing the push rod to move longitudinally inside the sheath.
  2. The pipette according to Claim 1, characterised in that the sleeve (110) is glued inside the sheath (60) by a glue (C).
  3. The pipette according to Claim 2, characterised in that the sleeve (110) is received in a bore (67) emerging on the axial extremity (61) of the sheath (60) serving as a distance of travel end stop for the piston in the reverse direction, the radially external face of the sleeve (110) having hollowings (115) to house the fixing glue (C) in the bore (67) of the sheath.
  4. The pipette according to any one of Claims 1 to 3, characterised in that the push rod (50) has a portion (50b, 50c) located outside the pipette body having a button (70) comprising a rapid adjustment knob (71, 71') provided with means for rigidly locking it in rotation with said push rod (50) and a cover (72, 72') mounted free in rotation about said longitudinal axis which covers the axial extremity section (73, 73') of the knob located furthest from the pipette body.
  5. The pipette according to Claim 4, characterised in that the means for rigidly locking the rapid adjustment knob (71) in rotation with the push rod (50) comprise two longitudinal slots (54, 55) formed on two diametrically opposed sides of the push rod (50) and which engage with two projecting ribs of complementary profile on the bearing surface of the rapid adjustment knob.
  6. The pipette according to Claim 5, characterised in that the cover (72) is mounted free in rotation on the push rod (50) and held axially onto it by complementarity of shapes.
  7. The pipette according to Claim 5, characterised in that the cover (72') is mounted free in rotation on the rapid adjustment knob (71') and held axially onto it by complementarity of shapes.
  8. The pipette according to any one of Claims 1 to 7, characterised in that said cross-section of the portion (50a) of the push rod (50) which is non-symmetrical in revolution engaged in the sleeve is hexagonal.
  9. The pipette according to any one of Claims 3 to 8, characterised in that said hollowings (115) provided on the external surface (112) of the sleeve (110) are made up of longitudinal flat parts extending axially over only a portion of the length of the sleeve.
  10. The pipette according to Claim 9, characterised in that said hollowings (115) are made up of three longitudinal flat parts equally distributed angularly about a longitudinal axis of symmetry for the sleeve (110) and symmetrically extending axially either side of a transverse plane of symmetry P for the sleeve (110).
  11. The pipette according to any one of Claims 1 to 10, characterised in that the sleeve (110) is made from phenylene polysulfide.
  12. The pipette according to any one of Claims 2 to 11, characterised in that the glue (C) is an epoxy glue.
EP93402356A 1992-09-28 1993-09-27 Pipette for sampling and distributing variable volumes of liquids Expired - Lifetime EP0591038B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9211529 1992-09-28
FR9211529A FR2696110B1 (en) 1992-09-28 1992-09-28 Improvement to a pick-up and distribution pole for adjustable volumes of liquids.

Publications (2)

Publication Number Publication Date
EP0591038A1 EP0591038A1 (en) 1994-04-06
EP0591038B1 true EP0591038B1 (en) 1997-05-07

Family

ID=9433952

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93402356A Expired - Lifetime EP0591038B1 (en) 1992-09-28 1993-09-27 Pipette for sampling and distributing variable volumes of liquids

Country Status (5)

Country Link
US (1) US5413006A (en)
EP (1) EP0591038B1 (en)
JP (1) JP3500458B2 (en)
DE (1) DE69310470T2 (en)
FR (1) FR2696110B1 (en)

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Also Published As

Publication number Publication date
JPH06210188A (en) 1994-08-02
DE69310470T2 (en) 1997-12-18
EP0591038A1 (en) 1994-04-06
FR2696110A1 (en) 1994-04-01
DE69310470D1 (en) 1997-06-12
JP3500458B2 (en) 2004-02-23
US5413006A (en) 1995-05-09
FR2696110B1 (en) 1994-12-09

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