EP1759768A1 - Pipette - Google Patents

Abstract

A pipetting system has separable upper and lower casing parts and a driving mechanism, in which a spigot is secured in its holder by snap hooks with catches and released by a wedge system which pushes the catches towards the axis of the pipette when an unlocking ring is moved in one direction and pulls them away from the axis when the ring is moved in the opposite direction. A pipetting system comprises an upper casing part (1) with a driving device with a moveable driving organ (3) and a spigot holder (10) with catch seating(s) (13), a lower casing part (14) with a displacement device (15) containing a displacement chamber (16) which is connected via a channel (22) to a receiver (21) (on 14) for a detachable pipette tip and a spigot (25) for fitting into (10), snap hook(s) (26', 26'') on the spigot with a catch (28', 28'') which engages with (13) and an elastic shank (27', 27'') which can be moved at right angles to the axis of the spigot to lift the catches out of the seatings, an unlocking ring (37) which can be moved on the spigot, a wedge mechanism (29', 29'') on the shaft and ring which pushes the snap hooks in towards the axis when the ring is moved in one direction and pulls them away from the axis when it is moved in the opposite direction, and a device (3, 19) for coupling the driving organ and the displacement device when the spigot is in its holder.

Description

The invention relates to a pipetting device having an upper housing part and a lower housing part detachably connectable to the upper housing part, which housing has at least one seat for releasably holding a pipette tip.

Pipetting devices are used in particular in the laboratory for dosing liquids. These are picked up in pipette tips through a tip opening and dispensed. In air cushion pipettes, a displacer for a gas is integrated into the pipetting device and communicatively connected to the pipette tip through a hole in the seat. By means of the displacement means an air cushion is displaced, so that liquid is sucked into the pipette tip and ejected therefrom. The displacement device is usually a cylinder with a piston displaceable therein.

The pipette tip is releasably held in place so it can be replaced with a fresh pipette tip after use. As a result, carry-over and contamination can be avoided in subsequent dosages. Single-use pipette tips are available inexpensively from plastic.

With air cushion pipettes, a contamination of the displacement device and in particular of the lower part of the pipette housing can occur. Therefore, it is desirable, the pipette housing in two parts with a To perform housing upper part and a lower housing part, which are separable from each other for example for autoclaving. Furthermore, it may be desirable to replace housing bases with displacement means in order to use the pipetting device in different volume areas can. Finally, by replacing the housing lower part, a single-channel pipette can be converted into a multi-channel pipette or the number of channels of a multi-channel pipette can be changed.

From the EP 0 428 500 B1 already a pipetting device with a displacement device in a lower housing part is known, which can be screwed by means of a union nut to the shaft of a housing upper part with a drive device for the displacement device. However, the replacement of the lower housing part is troublesome, time-consuming and prone to failure. For the use of threads, the assembly is expensive. In addition, it may easily come to unwanted separation of the lower housing part of the upper housing part due to the threaded connection.

From the GB 2 161 398 A is a pipette with a snap connection between the lower housing part and the upper housing part known. The lower housing part is connected via a coupling with the upper housing part, which has hook-shaped flanges, which snap into receptacles of the housing upper part. The release of the parts of the snap connection from each other is difficult if the snap connection is dimensioned so that the upper housing part and lower housing part are connected to each other with sufficient certainty. If the strength of the snap connection is reduced, There is a risk that the upper housing part and lower housing part are inadvertently separated from each other during use.

Based on this, the present invention seeks to provide a pipetting available in the upper housing part and lower housing part are easier separable from each other and yet connected to each other with great certainty.

The object is achieved by a pipetting device with the features of claim 1. Advantageous embodiments of the pipetting device are specified in the subclaims.

• ein Gehäuseoberteil,
• eine im Gehäuseoberteil angeordnete Antriebseinrichtung mit einem beweglichen Antriebsorgan,
• eine im Gehäuseoberteil angeordnete Zapfenaufnahme,
• mindestens eine Klauenaufnahme innerhalb der Zapfenaufnahme,
• ein Gehäuseunterteil,
• mindestens eine im Gehäuseunterteil angeordnete Verdrängungseinrichtung mit einer Verdrängungskammer,
• mindestens einen am Gehäuseunterteil angeordneten und über einen Kanal mit der Verdrängungskammer verbundenen Sitz zum lösbaren Halten einer Pipettenspitze,
• einen am Gehäuseunterteil angeordneten Zapfen zum Einführen in die Zapfenaufnahme,
• mindestens einen am Zapfen angeordneten Schnapphaken mit einer Klaue zum Eingreifen in die Klauenaufnahme bei in die Zapfenaufnahme eingeführtem Zapfen und einem federnden Schaft, der zum Ausheben der Klaue aus der Klauenaufnahme quer zur Achse des Zapfens auslenkbar ist,
• einen auf dem Zapfen verlagerbaren Entriegelungsring,
• ein ein Auslenken des Schnapphakens zur Achse hin bei Verlagerung des Entriegelungsringes in einer bestimmten Richtung und von der Achse weg bei Verlagerung des Entriegelungsringes in entgegengesetzter Richtung bewirkendes Keilgetriebe an Schaft und Entriegelungsring und
• eine Kupplungseinrichtung zum Kuppeln von Antriebsorgan und Verdrängungseinrichtung bei in die Zapfenaufnahme eingeführtem Zapfen.

The pipetting device according to the invention has

• an upper housing part,
• a drive device arranged in the housing upper part with a movable drive element,
• a pin receptacle arranged in the housing upper part,
• at least one jaw receptacle within the pin receptacle,
• a housing base,
• at least one displacement device arranged in the lower housing part with a displacement chamber,
• at least one seat arranged on the lower housing part and connected to the displacement chamber via a channel for releasably holding a pipette tip,
• a pin arranged on the lower housing part for insertion into the pin receptacle,
• at least one snap hook arranged on the pin with a claw for engaging in the claw receptacle when the pin is inserted into the pin receptacle and a resilient shaft which is deflectable transversely to the axis of the pin for lifting the claw out of the claw receptacle,
• a displaceable on the pin release ring,
• a deflection of the snap hook towards the axis upon displacement of the unlocking ring in a certain direction and away from the axis upon displacement of the unlocking in the opposite direction effecting wedge gear shaft and unlocking and
• a coupling device for coupling the drive member and the displacement device when inserted into the pin receiving pin.

The pipetting device according to the invention has a snap connection between the upper housing part and the lower housing part. It is possible to make this snap connection particularly strong, so that the upper housing part and lower housing part are securely connected to each other. Nevertheless, a disassembly is easily possible because the snap connection can be canceled in a simple manner and with reduced effort by shifting the unlocking. The force for the deflection of the snap hook is namely considerably reduced due to the wedge gear formed on the shaft and unlocking ring. It is thus possible with relatively little effort to shift the unlocking ring against considerable spring force of the snap hook. Consequently, the snap hook can be made particularly stiff or engage with the claw under bias in the claw receiving. The invention is also advantageous if several snap hooks are provided, which must be deflected simultaneously for disassembly with increased force.

The invention includes various embodiments of the displacement device. This may be, for example, a displacement chamber with a movable wall designed as a membrane. Preferably, the displacement device is a cylinder in which a piston is displaceable. The invention relates to embodiments in which the piston and cylinder are arranged in the lower housing part and embodiments in which only the cylinder arranged in the lower housing part and the piston is assigned to the upper housing part and is introduced in connection of housing lower part and upper housing part in the cylinder.

For a precise dosage, it requires a defined seat of the lower housing part in the upper housing part. For this purpose, according to one embodiment, the housing upper part is assigned a compression spring device of the pin receptacle, which presses against the insertion direction of the pin against the pin inserted into the pin receptacle. This ensures that the pin with the claw occupies a defined position in the jaw receiving, so that the upper housing part and lower housing part take a defined position to each other. Furthermore, the disassembly is facilitated because the compression spring device presses apart the upper housing part and the lower housing part as soon as the claw is dug out of the claw receiver. The user can therefore concentrate on the operation of the unlocking ring, since the upper housing part and lower housing part automatically move apart when unlocked.

According to one embodiment, the pin has an insertion direction in the snap hook upstream sleeve portion and at least one arranged next to the snap hook connecting web, snap hook and connecting web are connected to a base part and form sleeve portion, connecting web and snap hooks together a hollow cylindrical pin, from which the claw of the snap hook after protrudes slightly outside when the pin is not inserted in the pin receptacle. The upstream in the insertion sleeve portion and the cylindrical shape facilitate the insertion of the pin in the pin receiving. The outwardly projecting claw may snap in when inserted into the jaw receptacle. The displacement device can be coupled by an end opening of the hollow cylinder with the drive member of the drive device. The base part is e.g. firmly connected to a seat for the pipette tip, e.g. is designed as a conical or cylindrical approach.

The snap hook receptacle is e.g. formed as a pocket with limited extent in the circumferential direction on the inner circumference of the pin receiving. According to one embodiment, it is a circumferential on the inner circumference of the pin receiving annular groove, so that the lower housing part in any rotational position with respect to the pin receptacle is inserted into this or housing upper part and lower housing part in the locked state with respect to each other are pivotally.

According to one embodiment, the pin has a arranged in the insertion direction in front of the snap hook connecting element, which upon insertion of the Press pin in the pin receptacle against the compression spring device. This favors a gradual build-up of a spring tension of suitable height until the entry of the claw into the jaw receptacle and thus the defined positioning of the upper housing part with respect to the lower housing part and their automatic separation in the case of unlocking.

Basically, the snap hook can be aligned in the non-deflected state obliquely to the axis of the pin. According to one embodiment, the snap hook is aligned in the non-deflected state substantially parallel to the axis of the pin. This allows a substantially cylindrical design of the pin, which facilitates the insertion in any angular positions of the upper housing part and the lower housing part with respect to the journal axis.

According to one embodiment, the pipetting device has only a single snap hook. According to another embodiment, the pipetting device has a plurality of snap hooks distributed symmetrically over the circumference of the pin. As a result, a particularly secure attachment of the lower housing part is achieved on the upper housing part. Furthermore, the uniformly acting on the pin attachment forces favor a defined positioning of the upper housing part and lower housing part and facilitate assembly and disassembly.

According to a connecting the housing upper part and lower housing part facilitating execution, the claw on the in the insertion into the Pin receiving the preceding end on a taper and / or the pin receiving an outward extension.

The invention relates to different embodiments of the wedge gear on shaft and locking ring. According to one embodiment, the wedge gear on the shaft on an outwardly projecting projection and a wedge surface on the projection and / or a wedge surface on the inner circumference of the locking ring. Included is thus a projection with a wedge surface over which slides the locking ring with its inner circumference, which is designed without wedge surface. Also included is a projection without a wedge surface over which a wedge surface slides on the inner circumference of the locking ring. Furthermore, projection and inner circumference may each be designed with a wedge surface which slide over one another.

According to one embodiment, the wedge surface is directed in the direction of the pin and the unlocking ring axially displaceable on the pin. Thus, a deflection of the snap hook is effected by axial displacement of the unlocking ring.

According to one embodiment, the pin axial stops, between which the unlocking ring is displaced. By the stops the unlocking ring is captively connected to the pin. Furthermore, the stops limit the displacement area of the unlocking ring.

According to one embodiment, the wedge surface is directed in the circumferential direction of the pin and has the unlocking ring at least one receptacle on, in which the projection on the shaft of the snap hook can be screwed. In this embodiment, the snap hook is deflected by turning the Entriegelungsringes, since in this case the projection slides from the receptacle on the inner circumference of the unlocking ring. For this purpose, the expansion of the receptacle in the circumferential direction of the unlocking ring is limited. It is for example slightly larger than the extension of the projection in the circumferential direction, so that it is easily herausdrehbar. To lock the projection must be screwed into the receptacle. In this embodiment, axial stops may be present, which provide the unlocking ring in an axial position on the pin, in which the projection of the snap hook can enter into the receptacle of the locking ring.

According to one embodiment, the shaft has an outwardly projecting stop and the unlocking ring has a receiving groove for the stop, which has a limited extent in the circumferential direction of the unlocking ring, a rotation of the unlocking ring from the rotational position in which the projection engages in the receptacle in a rotational position permits, in which the projection rests next to the receptacle on the inner circumference of the unlocking ring. The stop limits the range of rotation of the locking ring, so that it can deflect the snap hook from the engaged position into the jaw receiving in a non-engaging position. Furthermore, the receiving groove can prevent an axial displacement of the unlocking ring on the pin, so that the projection is always easily screwed into the receptacle.

With single-channel pipettes, a displacement of the unlocking ring by hand is easily possible. In multi-channel pipettes, the displacement of the unlocking ring by hand is hindered by the lateral projection of the housing lower part. In particular, for multi-channel pipettes, according to one embodiment, the unlocking on the circumference on an axially directed teeth and the upper housing part a discharge device having an axially displaceable with respect to the pin receiving element another axial toothing, which is in uncontrolled release device out of engagement with the teeth and by pressing the ejection device can be brought into engagement with the toothing. When the serrations are brought into engagement with each other by operating the ejection means, the unlocking ring is prevented from rotating. As a result, it is possible by turning the housing lower part, to unscrew the projection of the snap hook from the receptacle of the detent unlocking ring and lift the snap hook with his claw from the jaws recording. The turning of the protruding housing lower part is easily possible. Furthermore, this embodiment ensures the pipetting device against accidental disconnection of the upper housing part and the lower housing part, since a separation is possible only when the ejection device is actuated. In particular, therefore, this embodiment is also advantageous in single-channel pipettes. Particularly advantageous is the use of an existing discharge device for pipette tips. Also included is the design of the pipetting device with a special ejection device for fixing the position of the unlocking ring, which is then a discharge device for the lower housing part.

According to a further embodiment, the axial toothing on the underside of a Abwurfübertragers is arranged, which - releasably or permanently - connected to a guided in the upper housing part discharge rod and - permanently or detachably - with a guided on the lower housing part ejector -. a discharge sleeve or a ejector plate - is connected for pipette tips.

According to one embodiment, the pipetting device is a single-channel pipette.

According to a further embodiment, the pipetting device is a multi-channel pipette. Pipetting devices that can be converted from a single-channel pipette to a multi-channel pipette by replacing the housing base and vice versa are also included.

Fig. 1

Gehäuseoberteil und Gehäuseunterteil bei verriegeltem Zapfen in einem vertikalen Teilschnitt;

Fig. 2

Gehäuseunterteil in einem Schnitt entlang der Linie II-II der Fig. 1;

Fig. 3

Gehäuseoberteil in einem vertikalen Teilschnitt und Gehäuseunterteil in Vollansicht bei verriegeltem Zapfen;

Fig. 4

Gehäuseunterteil in einer Ansicht entlang der Linie IV-IV der Fig. 3;

Fig. 5

Gehäuseoberteil und Gehäuseunterteil beim Einführen und Entriegeln des Zapfens in einem vertikalen Teilschnitt;

Fig. 6

Gehäuseunterteil in einem Schnitt entlang der Linie VI-VI der Fig. 5;

Fig. 7

Gehäuseoberteil und Gehäuseunterteil einer Mehrkanal-Pipettiervorrichtung in verriegeltem Zustand in einem vertikalen Teilschnitt;

Fig. 8

Gehäuseunterteil in einem Schnitt entlang der Linie VIII-VIII der Fig. 7;

Fig. 9

Gehäuseunterteil mit Abwurfübertrager in verrasteter Position und verriegelten Verriegelungshaken in Vollansicht;

Fig. 10

Gehäuseunterteil mit Abwurfübertrager in verrasteter Position und entriegelten Verriegelungshaken in vertikalem Teilschnitt;

Fig. 11

Gehäuseunterteil in einem Schnitt entlang der Linie XI-XI der Fig. 10;

Fig. 12

Gehäuseunterteil mit Abwurfübertrager bei entriegeltem Verriegelungshaken in Teilansicht;

Fig. 13

dasselbe Gehäuseunterteil mit Abwurfübertrager, wobei die axialen Zahnungen außer Eingriff sind, in Vollansicht.

The invention will be explained in more detail with reference to the accompanying drawings of exemplary embodiments. In the drawings show:

Fig. 1

Upper housing part and lower housing part with locked pin in a vertical partial section;

Fig. 2

Housing bottom in a section along the line II-II of Fig. 1;

Fig. 3

Upper part of the housing in a vertical partial section and lower part of the housing in full view with locked pin;

Fig. 4

Housing bottom in a view along the line IV-IV of Fig. 3;

Fig. 5

Upper housing part and lower housing part during insertion and unlocking of the pin in a vertical partial section;

Fig. 6

Lower housing part in a section along the line VI-VI of Fig. 5;

Fig. 7

Upper housing part and lower housing part of a multi-channel pipetting device in the locked state in a vertical partial section;

Fig. 8

Housing bottom in a section along the line VIII-VIII of Fig. 7;

Fig. 9

Housing base with ejector carrier in latched position and locked locking hook in full view;

Fig. 10

Housing base with Abwurfübertrager in latched position and unlocked locking hook in vertical section;

Fig. 11

Housing bottom in a section along the line XI-XI of Fig. 10;

Fig. 12

Lower part of housing with ejector carrier with unlocked locking hook in partial view;

Fig. 13

the same housing base with Abwurfübertrager, the axial serrations are disengaged, in full view.

In the following description, the terms "top" and "bottom" refer to the orientation of the pipetting device during pipetting in which the pipetting device is held vertically with the top of the housing top and the bottom of the housing and pipette tip attached thereto.

1 to 6, a single-channel pipetting device has an upper housing part 1 with a drive device 2, which has a movable drive member 3 in the form of a lifting rod which extends in the axial direction of a cylindrical cavity 4 in the upper housing part 1. The drive member 3 is axially displaceable in the direction of its longitudinal axis.

The drive device 2 has an actuating button 5, which is actuated counter to a return spring 6. By pressing the operating knob 5, the drive member 3 is movable downwards. After relieving the operating knob 5, the drive member 3 is moved back by the return spring 6 in the initial position shown.

When designed as a fixed volume pipette only a defined stroke of the drive member 3 is possible. In an embodiment as a pipette with adjustable metering volume, the drive device 2 comprises means which allow adjustment of the stroke of the drive member 3 and display devices which indicate the respectively set metering volume.

In the cavity 4 is designed as a helical spring compression spring means 7 at the upper ribs 8, which on the inner circumference of the cavity. 4 are arranged, supported and held by clamping action of their upper turn 9 in the cavity 4.

The lower part of the cavity 4, which extends approximately to the lower end of the compression spring device 7, is a pin receptacle 10. The pin receptacle 10 is accessible at the bottom through a housing opening 11. The housing opening 11 has a conical enlargement 12. Slightly above the housing opening 11, a jaw receptacle 13 is provided in the pin receptacle 10, which is designed as an annular groove running around the inner circumference of the pin receptacle 10.

The upper housing part 1 is e.g. made of a hard plastic. Components inserted into the housing top, such as e.g. the drive means 2 and the springs 6, 7 consist e.g. wholly or partly made of metal and / or plastic.

Furthermore, the pipetting device has a lower housing part 14. The lower housing part 14 comprises a displacement system 15, which is designed as a cylinder 16 with a piston 17 axially displaceable therein. Between piston 17 and cylinder 16, a sealing system 18 is present. The piston 17 has a piston plate 19 at the top. Between the piston plate 19 and top of the cylinder 16, a piston return spring 20 is present. On one of the two springs 6 or 20 can also be dispensed with.

The lower housing part 14 has at the bottom a cylindrical or slightly conical projection 21 for clamping a pipette tip. The cylinder 16 is connected via a channel 22 with a central opening 23 in the neck.

The displacement device 15 is wholly or partly made of metal and / or plastic.

Above the neck 21, the lower housing part 14 has a cone region 24. The neck 21 and cone region 24 together form a base part. In addition, the lower housing part 14 is designed as a substantially cylindrical pin 25. The pin 25 has two diametrically opposite snap hooks 26 ', 26 ", each of which has at the bottom a shaft 27', 27" connected to the cone area 24 and an outwardly projecting claw 28 ', 28 "at the top Center of each shaft 27 ', 27 "is an outwardly projecting projection 29', 29", which is wedge-shaped or outside a wedge surface 30 ', 30 "has. The wedge surfaces 30 ', 30 "are directed in the direction of the axis of the pin 25, wherein the height of the projections 29', 29" with respect to the shafts 27 ', 27 "increases from bottom to top.

The claws 28 ', 28 "have a conical taper 31 at the top.

The snap hooks 26 ', 26 "are aligned in an undeflected state (see Fig. 1) approximately parallel to the axis of the pin 25. They are elastically deflected towards the axis of the pin 25. For this example, the integral with it made cone portion 24 and projection 21 of the housing base 14 made of an elastic but hard plastic.

Furthermore, the pin 25 has a connecting element 32 which has two diametrically opposed connecting webs 33 ', 33 ". The connecting webs 33', 33" are arranged parallel to the axis of the journal 25. Above the snap hooks 26 ', 26 "they are interconnected by a complete circumferential, hollow cylindrical sleeve section 34. The sleeve section 34 has an inwardly projecting flange 35 with a central hole 36 through which the drive member 3 is insertable Plate 19 against the flange 35 and thus the piston 17 upwards.

The connecting webs 33 ', 33 "and the shanks 27', 27" of the snap hooks 26 ', 26 "are likewise hollow cylindrical. In the undeflected state, the shanks 27', 27" complement the connecting webs 33 approximately to form a hollow cylindrical body which passes through the top hollow cylindrical sleeve portion 34 is supplemented. Overall, therefore, a hollow cylindrical pin 25 is formed by the above-described elements.

The inner diameter of the unlocking ring 37 slightly exceeds the outer diameter of the pin 25 below the projections 29 ', 29 ". The unlocking ring 37 is axially between a lower axial stop 38 and an upper axial stop 39 slidably (see Fig. 3) .The lower axial stop 38 is formed by two projections, the projecting outwardly at the top of the cone region 24 and diametrically opposite one another. The upper axial stop 39 is formed by protrusions 39 projecting outward on the connecting webs 33 ', 33 ".

The stop 38 is positioned so that the unlocking ring 37 is displaceable from a position in which it releases the projections 29 ', 29 "into a position in which it covers the projections 29', 29". The inner diameter of the unlocking ring 37 is dimensioned so that it slides when pushed onto the projections 29 ', 29 "with its inner circumference on the sliding surfaces 30', 30" and the snap hooks 26 ', 26 "to the axis of the pin 25 deflects out.

Upper housing part 1 and lower housing part 14 are handled as follows:

For assembly, the lower housing part 14 is axially inserted with the pin 25 in the pin receptacle 10. Here, the Zuspitzungen 31 ', 31 "slide over the extension 12 and the snap hooks 26', 26" are deflected inwards. The compression spring device 7 is slightly compressed by the connecting element 32 of the pin 25. The drive member 3 dips into the hole 36 and contacts the plate 19. Finally, the claws 28 ', 28 "snap into the jaw receptacle 13. The compression spring means 7 pushes the jaws 28', 28" against the jaw receptacle 13 with its underside that a defined position is maintained. The spring plate 19 is held by the piston return spring 20 in a defined contact with the drive member 3 (see Fig. 1).

The assembly can also take place in such a way that previously the unlocking ring 39 is pushed up to the upper stop 39, so that the snap hooks 26 ', 26 "spring in. When the claws 28', 28" at the level of the jaw receiving 13th located, the unlocking ring 37 must be pushed down so that the claws 28 ', 28 "engage in the jaw receptacle.

After clamping a pipette tip on the neck 21 can be moved by pressing the operating knob 5 by means of the displacement means 15, an air column to suck liquid into the pipette tip or eject.

For disassembly, the unlocking ring 37 is pushed upwards so that the jaws 28 ', 28 "are lifted out of the jaw receptacle 13. This is achieved when the unlocking ring 37 abuts on the upper stop 39. The compression spring device 7 presses the lower housing part 14 out of the Housing top 1 out, so that it is easily removable (see FIG .. 5).

In discussing the embodiment of Figs. 7 to 13, parts substantially identical to those of the embodiment of Figs. 1 to 6 are indicated by the same reference numerals.

The upper housing part 1 is identical. For this embodiment, it is important that the upper housing part 1 next to the cavity 4 has an axially directed shaft 40 through which a discharge rod 41st is guided. The discharge rod 41 is connected at the upper end of the housing upper part 1 with a discharge button 42. A discharge spring 43 between the housing and the discharge rod 41 pushes the discharge rod 41 back into an upper starting position. At the bottom, the discharge rod 41 has a bottom out of the housing upper part 1 protruding shank 44th

The lower housing part 45 has a pin 25 which, unlike the previously described pin, has projections 46 ', 46 "with wedge surfaces 47', 47" on the snap hooks 26 ', 26 "which are directed in the circumferential direction of the pin on the snap hook 26 ', 26 "in each case below a projection 46', 46" an outwardly projecting stop 48 ', 48 "present.

On the pin 25 sits a Entriegelungsring 37, the two diametrically opposed receptacles 49 ', 49 ", into which the projections 46', 46" are screwed. The receptacles 49 ', 49 "extend in the circumferential direction over the entire length of the projections 46', 46". The receptacles 49 ', 49 "are formed as openings of the unlocking ring 37.

Below the receptacle 49 ', 49 ", the unlocking ring 37 has two diametrically opposed receiving grooves 50', 50", which are also formed as openings. In the receiving grooves 50 ', 50 "the stops 48', 48" can be placed. The receiving grooves 50 ', 50 "extend over a region of the circumference of the pin 25, so that the stops 48', 48" are displaceable within the receiving grooves 50 ', 50 " Extension of the receiving grooves 50 ', 50 "slightly exceeds the axial extent of the stops 48', 48", so that the unlocking ring 37 is held immovably in the axial direction on the pin 25 when the stops 48 ', 48 "in the annular grooves 50', 50 "intervene.

The stops 48 ', 48 "limit in cooperation with the annular grooves 50', 50" the rotation of the Entriegelungsringes 37 on the pin 25 so that the projections 46 ', 46 "from the position shown in Fig. 7, in which they completely engage in the receptacles 49 ', 49 ", can be brought to the position shown in Fig. 10, in which they just next to the receptacles 49', 49" abut the inner circumference of the Entriegelungsringes 37. If the unlocking ring 37 from the in Fig. 7 shown position, the wedge surfaces 47 ', 47 "slide over the edges of the receptacles 49', 49", so that the snap hooks 26 ', 26 "are gradually shifted towards the pin axis.

The unlocking ring 37 has on the outer circumference at diametrically opposite areas in each case an axially upwardly directed toothing 51 ', 51 ".

Further, outside on the pin 25 a Abwurfübertrager 52 is guided axially displaceable. The Abwurfübertrager 52 has a parallel to the pin directed receptacle 53, in which the insertion 44 of the discharge rod 41 is pressed. Bottom of the Abwurfübertrager 52 has a downward, circumferential axial toothing 54 which is in engagement with the teeth 51 ', 51 ", when the Abwurfübertrager 52 is pushed down. The ejection carrier 52 is connected to an ejector plate, which is assigned to projections for attaching pipette tips, via ejector webs 55 ', 55 "arranged on one side of the housing lower part 45. The design of such ejectors for multichannel pipettes is known to the person skilled in the art and is not described in detail here.

On the axis of the pin 25 extends an actuating rod 56 which is connected below the pin in a widened housing portion with a cross member 57. The traverse 57 is in turn connected to non-illustrated pistons of a plurality of parallel displacement means which are communicatively connected to the approaches for attaching the pipette tips. These embodiments of multichannel pipettes, which are not shown in detail, are also known to the person skilled in the art.

A piston return spring 20 loads the plate 19 so that it is pressed up against the flange 35.

To connect the upper housing part 1 and the lower housing part 45, the pin 25 is inserted into the pin receptacle 10 until the claws 28 ', 28 "snap into the claw receptacle 13. The compression spring device 7 holds the claws 28', 28" in abutment with the underside lower wall of the claw receiver 13. Further, during the assembly of the pin 25, the drive member 3 comes to rest on the plate 19. As a result, dosing operations can be performed by operating the drive means 2.

In the plug-in receptacle 53 of the Abwurfübertragers 52, the insertion end 44 of the ejector rod 41 is pressed. When inserted into the pin receptacle 10, the pin 25 penetrates into the Abwurfübertrager 52 a. In this case, the ejector carrier 52 contacts the ejector webs 55 ', 55 ", which abut on the ejector carrier 52 under spring tension. This state is reached when the journal 25 is latched in the plug-in receptacle 53. By operating the ejection button 42, pipette tips plugged onto the attachments can be thrown off become.

It is possible to bring the lower housing part 45 in an arbitrary rotational position with respect to the upper housing part 1.

For disassembly, the ejection button 42 is actuated, so that the axial serrations 51 ', 51 "engage in the axial toothing 54. In this way, the unlocking ring 37 is held in its rotational position. Thereafter, by pivoting the housing lower part 45, a turning out of the projections 46', As a result, the claws 28 ', 28 "are lifted out of the jaw receptacle 13 and the compression spring device 7 pushes the lower housing part 45 out of the upper housing part 1.

Supporting can be pulled on the housing base 45.

Claims (15)

Pipetting device with an upper housing part (1), a drive device (2) arranged in the housing upper part (1) with a movable drive element (3), - A in the upper housing part (1) arranged pin receptacle (10), - At least one jaw receptacle (13) within the pin receptacle (10), a housing lower part (14), - At least one in the housing lower part (14) arranged displacement means (15) having a displacement chamber (16), at least one seat (21) arranged on the lower housing part (14; 45) and connected via a channel (22) to the displacement chamber (16) for releasably holding a pipette tip, a pin (25) arranged on the lower housing part (14; 45) for insertion into the pin receptacle (10), - At least one on the pin (25) arranged snap hook (26 ', 26 ") with a claw (28', 28") for engaging in the jaw receptacle (13) in the pin receptacle (10) inserted pin (25) and a resilient Shank (27 ', 27 ") which is deflectable for lifting the claw (28', 28") out of the jaw receptacle (13) transversely to the axis of the pin (25), - A releasable on the pin release ring (37), - A deflection of the snap hook (26 ', 26 ") towards the axis upon displacement of the unlocking ring (37) in a certain direction and away from the axis upon displacement of the unlocking ring (37) in the opposite direction wedge gear (29', 29" 46 ', 46 ", 37) on shank (27', 27") and unlocking ring (37) and - A coupling device (3, 19) for coupling of the drive member (3) and displacement means (15) in the pin receptacle (10) inserted pin (25). Pipetting device according to claim 1, wherein in the upper housing part (1) a compression spring device (7) is associated with the pin receptacle (10) which presses against the pin (25) inserted into the pin receptacle (10) counter to the insertion direction of the pin (25). Pipetting device according to Claim 1 or 2, in which the pin (25) has a sleeve section (34) arranged upstream of the snap hook (26 ', 26 ") in the insertion direction and at least one connecting web (33', 33) arranged next to the snap hook (26 ', 26"). 33 "), snap hooks (26 ', 26") and connecting web (33', 33 ") are connected to a base part (24), sleeve section (34), connecting web (33 ', 33") and snap hook (26', 26 ") form a hollow cylindrical pin (25) from which the claw (28 '28") projects slightly outwards when the pin (25) is not inserted in the pin receiving means (10). Pipetting device according to one of claims 1 to 3, wherein the snap hook (26 ', 26 ") in the undeflected state is aligned substantially parallel to the axis of the pin (25). Pipetting device according to one of claims 1 to 4, which has a plurality of symmetrically over the circumference of the pin (25) distributed snap hook (26 ', 26 "). Pipetting device according to one of claims 1 to 5, wherein the claw (28 ', 28 ") at the end preceding the insertion into the pin receptacle (10) has a taper (18) and / or in which the pin receptacle (10) has an outward direction directed extension (12). Pipetting device according to one of claims 1 to 6, in which the wedge gear (29 ', 29 ", 37) on the shaft (27', 27") has an outwardly projecting projection (29 ', 29 ") and a wedge surface (30', 30 ") on the projection (29 ', 29") and / or a wedge surface on the inner circumference of the locking ring (37). Pipetting device according to one of claims 1 to 7, wherein the wedge surface (30 ', 30 ") directed in the direction of the pin (25) and the unlocking ring (37) axially on the pin (25) is displaceable. Pipetting device according to one of claims 1 to 8, wherein the pin (25) has axial stops (38, 39), between which the unlocking ring (37) is displaceable. Pipetting device according to one of claims 7 to 9, wherein the wedge surface (47 ', 47 ") is directed in the circumferential direction of the pin (25) and the unlocking ring (37) at least one receptacle (49', 49"), in which the Projection (46 ', 46 ") can be screwed. The pipetting device according to one of claims 7 to 10, wherein the shaft (27 ', 27 ") has an outwardly projecting stop (48', 48") and the unlocking ring (37) has a receiving groove (50 ', 50 ") for the Stop (48 ', 48 ") which has a limited extent in the circumferential direction of the Entriegelungsringes (37), a rotation of the Entriegelungsringes (37) from the rotational position in which the projection (46', 46") in the receptacle ( 49 ', 49 "), in a rotational position permits, in which the projection (46', 46") adjacent to the receptacle (49 ', 49 ") on the inner circumference of the unlocking ring (37). Pipetting device according to claim 10 or 11, in which the unlocking ring (37) has an axially directed toothing (51 ', 51 ") on the circumference and the housing upper part (1) has a discharge device (41 to 44) which is mounted on a pin (3). 10) axially displaceable element (52) has a further axial toothing (54) which is in unactuated ejection device (41 to 44) out of engagement with the toothing (51 ', 51 ") and by pressing the ejection device (41 to 44) in Intervention with the teeth can be brought. Pipetting device according to claim 12, wherein the further axial toothing (54) on the underside of a Abwurfübertragers (52) is arranged, which connected to a housing upper part (1) discharge rod (41) and connected to a housing lower part (45) guided ejector for Pipette tips is connected. A pipetting device according to any one of claims 1 to 13, which is a single channel pipette. A pipetting device according to any one of claims 1 to 14, which is a multi-channel pipette.

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