EP1185368B1 - Pipette with tip ejector - Google Patents

Abstract

The invention relates to a pipette for transferring liquids, comprising the following: at least one piston-cylinder arrangement (3, 4), in which the cylinder (4) is arranged in such a way that it can be provided with a replaceable tip (8) for containing the liquid to be transferred; a piston actuating device (5) for drawing up and discharging the liquid; and a tip ejector device (6). Said ejector device comprises an ejection mechanism (16, 16') which can be displaced along the cylinder in order to eject a tip (8) from the end of said 24 cylinder. A device (17) for actuating the ejection mechanism is also provided. The invention is characterized in that the ejector device (6) comprises a device for adjusting position (24, 24', 33, 33', 39, 39'), which is arranged in such a way that it is possible to modify the limit position reached by an ejection end (22, 22') of the ejector device at the end of a stroke.

Description

The invention relates to a pipette for transferring liquids comprising at least one minus a piston-cylinder assembly arranged so as to be provided with a transfer tip.

Pipettes of this type are generally known, an example being described in US Patent 5,614,153. Such a pipette makes it possible to transfer small amounts of liquid in a replaceable tip mounted at the end free of the pipette cylinder. This transfer takes place without contamination of the pipette, the used tips being replaced by new tips. The pipette is equipped with a tip ejector that can be operated manually and comprises an ejection member sliding along the cylinder to abut against the tip and push it so as to separate it from the cylinder. In this pipette, the ejection organ travels an invariable distance and its final position is fixed.

The tips used may come from different manufacturers or have different different shapes, so that their dimensions can vary from one to the other. Thus, the position of the tips on the cylinder may differ depending on the variants available on the market and according to the commitment force. It follows a variation of the position of the edge of the tip on which the organ abuts ejection. The variations of position being of the order of magnitude of the race of the ejection member, some tips are not ejected or can abut on the ejector before the creation of a seal between the tip and the cylinder of the pipette.

US-A-4,965,050 discloses a pipette for the transfer of liquids relating to a tip ejector device on which an adapter ring is mounted so that when a piston actuator is fully depressed, an edge of the adapter ring comes into contact with a edge of a mouthpiece and ejects it.

An object of the invention is to provide a pipette which allows to attach and to eject the tips in a reliable manner, in particular taking into account the variable position of the edge of the tip relative to the pipette. Such a The pipette is preferably designed to be easy to use and robust.

The present pipette for transferring liquids has at least one piston-cylinder assembly, the cylinder of which can be provided with a nozzle replaceable, a piston actuator to cause aspiration and the delivery of the liquid and a tip ejector device comprising a ejection member movable along the cylinder, has the particularity that the ejector device comprises a position adjustment device arranged way to change the limit position reached at the end of the race by the eytremity of the election member during an ejection operation of the mouthpiece by setting the starting position of a free edge of the ejection end or by a variation of the stroke of the ejection member relative to the cylinder. he It should be noted that in practice the adjustment will generally be through the adjustment of the starting position of the free edge of the organ ejection intended to abut on the upper edge of the tip. In all the embodiments, the present pipette makes it possible to attach and eject, reliably, tips of different shapes and sizes.

The position adjusting device may comprise a socket arranged on the cylinder of the piston-cylinder assembly, the cooperation between this sleeve and the ejection member for adjusting the position of the end of the organ ejection with respect to the cylinder. The socket and the ejection member can be coupled by threaded parts or by the support of a pin or other element against a crown having an inclined surface, so that the adjustment of the position of the ejection member is effected by a relative rotation between the socket and this organ. Thus, in a first embodiment, the ejection member is rotatable and the socket is held fixed, and in one embodiment alternatively, the sleeve is rotatable and the ejection member is fixed. The socket and / or the ejection member may be provided with notches, a pin or means to define the angular position with respect to the counterpart. Advantageously, the socket which can be mounted on a part of the cylinder, and the ejection member are easily accessible and adjustable.

Variations of the position adjustment device consist in using, for example, example, a socket whose position is adjustable relative to the organ of ejection and which is mounted on this member so as to form the end ejection of it. The socket and the ejection member may have parts respective threaded or other means of attachment to adjust the position of the socket according to the tip used.

In the alternative of using a position adjustment device which allows to modify the limit position of the ejection member by a variation of the stroke of the ejection member relative to the cylinder, the ejection member can for example be coupled to its actuator through a variable length member so as to modify at least one limit position of the actuating member.

Other aspects, aims and advantages of the invention will emerge from the description given below, accompanying drawings and claims.

la Fig. 1 est une vue en coupe partielle d'une première forme d'exécution d'une pipette selon l'invention;

la Fig. 2 est une vue en coupe partielle d'un ensemble piston-cylindre de la pipette de la Fig. 1;

la Fig. 3 est une vue agrandie, en coupe, selon la ligne III-III de la Fig. 2;

la Fig. 4 est une vue en coupe d'une deuxième forme d'exécution d'une pipette selon l'invention;

la Fig. 5 est une vue en coupe partielle d'un ensemble piston-cylindre d'une troisième forme d'exécution; et

les Figures 6 à 9 sont des vues partielles, en coupe, de variantes d'un dispositif d'ajustement de position disposé à proximité de l'extrémité du cylindre de la pipette.

By way of example, embodiments of the invention are described below with reference to the drawings, in which:

FIG. 1 is a partial sectional view of a first embodiment of a pipette according to the invention;

FIG. 2 is a partial sectional view of a piston-cylinder assembly of the pipette of FIG. 1;

FIG. 3 is an enlarged sectional view along the line III-III of FIG. 2;

FIG. 4 is a sectional view of a second embodiment of a pipette according to the invention;

FIG. 5 is a partial sectional view of a piston-cylinder assembly of a third embodiment; and

Figures 6 to 9 are partial sectional views of variants of a position adjustment device disposed near the end of the pipette cylinder.

Figures 1 to 3 and FIG. 4 show, respectively, pipettes 1 and 1 ' whose like parts have been designated by the same reference numeral. Such a pipette comprises a pipette body 2 provided with a piston-cylinder assembly 3, 4, a piston actuator 5 and a device ejector 6, the piston actuator 5 comprises a pusher 7 acting on the piston 3 of the piston-cylinder assembly which makes it possible to suck and / or to discharge liquid through an exchangeable tip 8 mounted at the end 9 of the cylinder 4 of the piston-cylinder assembly. The cylinder 4 communicates with the tip 8 by an opening 10 of its end 9.

The pusher 7 of the actuating device 5 of the piston comprises a button 11 and a rod 12. The rod 12 is coupled to the knob 11 via a threaded portion 13, so as to allow the adjustment of the position of the rod 12 and therefore of the piston 3 with respect to the cylinder to determine the volume of liquid aspirated. Other actuating devices of the piston 12 can be provided without departing from the scope of the invention, the actuation can be, for example, hydraulic or electric.

The rod 12 is coupled at its end 14 in a separable manner to the piston 3. The piston 3 is provided with elastic arms 15 having depressions 56 on their surface interior so as to cooperate with the end 14 of the rod 12, which is ball-shaped. The coupling between the elastic arms 15 and the end 14 is therefore quickly separable by application of a certain traction force on the piston-cylinder assembly relative to the body 2. This allows, for example, example, to exchange the piston-cylinder assemblies with volumes different suction or shape and different dimensions to be comply with different standards, or exchange defective sets without have to replace the entire device. The connection between the elastic arms 15 and the ball 14 form a set of plug and prize advantageous because it is very quick and easy to disconnect and reconnect devices.

The ejector device 6 comprises an ejection member 16 or 16 'having a tubular portion slidably disposed on the cylinder 4, and a actuating device 17 of this ejection member. The device actuator 17 comprises a pusher 18 and a rod 19 connecting the pusher to a coupling member 20 or 20 '. The coupling member makes a connection separable between the ejection member 16 or 16 'and the actuating device 17 by snapping, for example by the interaction of protuberances and grooves formed on complementary parts. Pushing the pusher 18 to stop, position in which it comes for example abut on the sleeve or a portion 21 of the body 2 of the pipette, the ejection member 16 or 16 'is moved over a distance determined by the displacement of this pusher. The end 22 of the ejection member abuts on the upper edge 23 of the nozzle for to separate it from the cylinder 4. The pusher 18 is advantageously placed same side of the pipette body as the claw 21, which facilitates the actuation of the ejection pusher easily accessible to the operator. On the other hand, this provision makes the opposite side of the free pipette body to easily arrange a display device.

In the embodiment shown in FIG. 4, the ejector device comprises a position adjusting device 24 comprising a threaded portion 25 to the upper end of the rod 19 which is engaged in a threaded portion complementary to a bore 26 of the pusher 18. The head of the threaded portion 25 is accessible from the outside to allow adjustment of the stem position 19 relative to the pusher 18, the coupling member 20 allowing the rotation of the rod 19. This rotation moves the ejection member 16 relative to the 4. The position of the end 22 of the ejection member 16 can therefore be adjusted to allow the ejection of tips 8 having upper edges located at different heights relative to the end 9 of the cylinder.

In a variant, the position of the pusher 18 is adjusted to vary the stroke of the actuating member determined by the distance between the limit position high of the pusher and the sleeve or claw 21. The variation of the stroke of the pusher 18 thus also modifies the limit position of the end 22 of the ejection member reached during the actuation of the ejector. We obtain reliable ejection of tips having positions and / or dimensions different.

Figures 1 to 3 show a preferred embodiment of the invention. In this example, the position adjusting device 24 'has a socket 27 mounted around the cylinder 4 near the upper end thereof. The bushing 27 has a peripheral groove 28 into which a protruding part of the coupling member 20 'connected to the actuating rod 19. In one embodiment, the sleeve 27 can rotate about its axis, while being integral, in the axial direction, with the actuating device of the ejection member 16 '. An internal thread 29 of the sleeve 27 cooperates with a threading 30 on the upper part of the ejection member 16 ', so that rotation of the socket allows the end 22 to be moved away or the ejection member of the end 9 of the cylinder 4. The inner surface of the sleeve has a series of axial notches 31 in which a gadroon 32 the periphery of the upper part of the member 16 'can engage to define the angular position of the sleeve relative to this body. The member 16 'is prevented from rotating around its axis and therefore moves in the axial direction relative to the cylinder 4 when adjusting its position by rotation of the sleeve 27. In another embodiment, the sleeve 27 is fixed and the member 16 'is rotatably mounted so that rotation of the member of ejection makes it possible to move the end 22 of the end 9 away from cylinder 4.

According to the embodiment of FIG. 5, the ejector device has a 24 "position adjustment device having a fixed sleeve 27 'and an organ ejection nozzle 16 "mounted so as to allow its rotation on the cylinder 4. The organ ejection is provided with a piece 32 with a pin 32 "which engages in notches 31 'of a ring 29' having an inclined engagement surface 29 "The notches 31 'arranged at intervals around the periphery of the crown and thus define different positions in height for the adjustment the position of the end 22 of the ejection member 16 ". acting on the sleeve 27 'and on the member 16 "ensures the engagement of the pin 32" in one of the notches 31 '. The piston-cylinder device of FIG. 5 can also comprise a piston and means for enabling quick coupling to a pipette body similar to the means described above in connection with the embodiment of FIG. 2.

Other embodiments of position adjustment devices are feasible without departing from the scope of the invention. In particular, a socket of adjustment can be mounted on an end portion of the ejection member, according to the variants shown in Figures 6 to 9, to form an ejection edge 22 'whose position can be adjusted relative to the cylinder 4 of the pipette.

In the variants of FIGS. 6 and 9, a bushing 33 or 33 'is mounted on the part 34 or 34 'of the ejection member which has a thread 35 or 35' cooperating with a complementary thread of the sleeve. According to FIG. 9, notch streaks 36 are formed on the bottom of the net to allow a good definition of the angular position of the socket 33. In the variant of the 6, the notch is displaced on the cylindrical portion 37 of the ejection member and formed by a set of notches-gadroons 38 on this part and the socket 33.

Fig. 7 shows a variant according to which a sleeve 39 is mounted on a end portion 40 of the ejection member via pins, such as 41, which are positioned in corresponding grooves arranged on the around the edge of the portion 40. These grooves, such as 42, 43, 44, have heights different that allow to define corresponding positions of the socket relative to the ejection member. The guiding of the socket is ensured by the cylinder 4 on which it slides.

In the variant of FIG. 8, a sleeve 39 'is provided with tabs longitudinal 50, provided at their free ends protuberances 51 arranged so as to be able to enter skylights, such as 52, 53, 54, located at different heights in the portion 40 'of the ejection member.

Thus, in the embodiments of Figures 6 to 9, the limit position of the end of the ejection member is adjustable at this end of to obtain effective ejection for tips whose edge superior is at different heights compared to the cylinder of the pipette.

Claims (13)

1. A pipette for the transfer of liquids including at least a piston - cylinder assembly (3, 4), in which the cylinder (4) is arranged in such a manner that it can be provided with a removable tip (8), designed for containing the liquid to be transferred, an actuator device (5) of the piston for filling the tip with liquid and expelling the same therefrom and a device (6) for ejecting the tips and having an ejector end, the ejector device including an ejection member (16, 16") movable along the cylinder for ejecting a tip (8) from the end of the cylinder and an actuator device (17) for the ejection member, characterised in that the ejector device (6) includes a position adjustment device (24, 24', 24" 33, 33', 39, 39') arranged in such a manner as to modify the limit position of a free edge of the ejection end (22, 22') of the ejector device reached at the end of its travel by the adjustment of the starting position of said free edge.
2. A pipette according to claim 1, characterised in that the position adjustment device (24, 24', 24") includes a sleeve (27, 27', 33, 33', 39, 39') mounted in such a manner as to enable a relative displacement between a part of the ejection member and said sleeve.
3. A pipette according to claim 2, characterised in that the sleeve (27, 33, 33') and the ejection member have complementary threaded parts (29, 30 ; 35, 35') which co-operate to make possible said relative motion.
4. A pipette according to claim 2, characterised in that the position adjustment device (24") includes, at least, one lug (32") which is positioned on the ejection member or on a fixed opposite part and which is engaged into notches (31') provided, respectively, on an annular sloping surface (29"), respectively, of the opposite part or of the ejection member.
5. A pipette according to claim 4, characterised in that the position adjustment device includes a spring (55) pressing against the ejection member (16") to ensure that the lug (32") engages with one of the notches (31').
6. A pipette according to one of claims 2 to 5, characterised in that the sleeve (27, 27', 33, 33') and the ejection member include an arrangement (31, 32 ; 31', 32" ; 36, 38), which makes it possible to define the relative angular positions between, respectively, this member and the sleeve.
7. A pipette according to one of the claims 2 to 6, characterised in that the sleeve (27) is arranged in the vicinity of an end (28) of the cylinder (4) away from the end (9) on which is placed the tip (8).
8. A pipette according to one of the preceding claims, characterised in that the position adjustment device (24') includes an arrangement (20, 22'), which provides a separable connection between an ejection actuator rod (19) and the ejection member (16, 16').
9. A pipette according to claim 1, characterised in that the position adjustment device (24, 24') is arranged in such a manner as to enable a modification of the position of the ejection member (16, 16') or of a part integral therewith (33, 33', 39, 39'), relative to the cylinder (4) of the pipette.
10. A pipette for the transfer of liquids including at least one piston - cylinder assembly (3, 4), in which the cylinder (4) is arranged in such a manner that it may be provided with a replaceable tip (8), designed for containing the liquid to be transferred, an actuator device (5) for the piston, for filling the tip with liquid and emptying the same, and a tip ejector device (6) having an ejection end, the ejector device including an ejection member (16) movable along the cylinder for ejecting a tip (8) from the end of the cylinder and an actuator device (17) of the ejection member, characterised in that the ejector device (6) comprises a position adjustment device (24), arranged in such a manner as to allow a modification of the limit position of a free edge of the ejection end (22) of the ejector device reached at the end of the travel, by a variation of the travel distance of the ejection member with respect to the cylinder.
11. A pipette according to claim 9 or claim 10, characterised in that the position adjustment device (24) includes an actuator rod (19) and a pusher member (18) coupled in such a manner as to enable a modification of the position of this rod relative to said pusher member.
12. A pipette according to one of the preceding claims, characterised in that the ejector device (6) includes a pusher (18) positioned on the same side of the body of the pipette as the claw (21) and in the vicinity thereof.
13. A pipette according to one of the preceding claims, characterised in that the actuator device (17) of the ejection member is connected removably to the ejection member (16, 16') by a snap on means.

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