DE102022122178A1 - Displacer device and pipetting device - Google Patents

Abstract

The invention relates to a displacement device (1) for a pipetting device (26) for receiving and dispensing fluid volumes. The displacement device (1) has at least one piston-cylinder unit (2) which can be detachably connected to the displacement device (1), which has a piston (3) and a cylinder (4), and a piston receptacle (5) for each piston Cylinder unit (2). Each piston (3) has a piston head (12) and a displacement part (13), a restoring means (14) for the non-positive connection between the piston (3) and the piston receptacle (5), a fixed upper stop (15) for the restoring means ( 14) and a lower stop (16) for the restoring means (14). The lower stop (16) is movably arranged on the piston (3) in the longitudinal direction (L) of the piston (3). When the piston (3) is inserted into the piston receptacle (5), the upper stop (15) and the lower stop (16) are arranged within the piston receptacle (5) and the restoring force of the restoring means (14) acts on the upper stop ( 15) and on the lower stop (16) and the restoring force of the restoring means (14) presses the lower stop (16) at least indirectly against the piston receptacle (5) and the piston head (12) at least indirectly against the piston receptacle (5). The invention also relates to a pipetting device (26) for receiving and dispensing fluid volumes, wherein the pipetting device (26) has a displacement device (1) according to the invention.

Description

The invention relates to a displacement device for a pipetting device according to claim 1 and to a pipetting device for receiving and dispensing fluid volumes according to claim 14.

A pipetting device of the type in question is used to receive and dispense fluid volumes or to handle liquids by means of a displacement device. Such a pipetting device is used in particular for dosing, repeated dispensing, titration or pipetting of liquids.

The displacement device can be an integral part of the pipetting device or can be designed as a replacement part and can be detachably coupled to the pipetting device. In the latter case, the displacement device can be detached from the pipetting device after one or more dosing processes. Subsequently, another, in particular different, displacement device can be attached to the pipetting device.

The displacement device can be designed as a piston-cylinder unit or have several piston-cylinder units.

The displacement device preferably has a displacement means, in particular a piston, and a displacement housing, in particular a cylinder. The displacement means is movably arranged in the displacement housing and can be moved in the displacement housing by means of a drive device. The movement of the displacement means in the displacement housing is a substantially translational movement, in particular in the axial direction of the displacement housing.

The piston has a piston head. The term “piston head” refers to the part of the piston of a piston-cylinder unit that is located outside the cylinder when the piston is pushed maximally into the cylinder. A drive or an actuator of the pipetting device acts on the piston head.

The pipetting device, together with the displacement device, can be based on the air cushion principle or on the direct displacement principle.

A pipette tip, preferably airtight, can be attached to the displacement device. The pipette tip can be connected to the displacement device using a plug connection. For this purpose, the displacement device can have a tubular cylindrical or conical end piece onto which the pipette tip with a corresponding tubular opening is placed. The displacement device and the pipette tip can together form a closed air space. The displacement device changes the volume of the air space and thus enables liquid to be sucked in and released into and out of the pipette tip. The pipette tip can be separated or thrown away from the displacement device. To separate or eject the pipette tip from the displacement device, an ejector device or an ejector mechanism is provided on the pipetting device.

Alternatively, the displacement device can be designed as a syringe.

The displacement device can be completely or partially separable from the pipetting device.

The pipetting device can be hand-held or part of an automated laboratory device.

In the case of several piston-cylinder units in a displacement device, the terms multi-channel displacement device or multi-channel pipetting device or multi-channel pipette are also used. The latter are used, for example, to simultaneously absorb fluid volumes from several vessels or to release them into several vessels at the same time. In particular, depressions or wells of microtiter plates come into consideration as vessels. Displacer devices with eight and twelve piston-cylinder units are particularly frequently used because many microtiter plates have 96 wells in an 8 x 12 column/row arrangement.

In the case of several piston-cylinder units in a displacement device, the piston-cylinder units are usually arranged next to one another. In multi-channel pipetting devices for dosing large volumes of fluid, the piston-cylinder units are preferably arranged offset from one another for steric reasons. The cylinders and pistons of the cylinder-piston units are grouped together in a block. Each piston is held or stored in its own piston holder, for example a piston holder bar. The pistons are connected to a common piston drive. The pistons can be connected to the piston receiving beam via the piston head of each piston.

The piston drive is used to move each piston within the associated cylinder. It is known to couple a piston actuating rod, which can be driven manually or by means of an electric motor linear drive, to the piston receiving bar.

In order not to have to replace the entire pipetting device if the piston-cylinder unit(s) wear out, it is important for the user to easily assemble and disassemble the piston-cylinder unit(s).

In addition, the piston-cylinder unit(s) must also be maintained regularly to ensure error-free use.

For this purpose, it is desirable to be able to easily insert and/or remove the piston into the displacement device using the piston head. For this purpose, it is advantageous if the piston head of the piston can be mounted laterally in the displacement device, in particular laterally in the piston receiving beam.

For the assembly or insertion of the piston head of the piston into the associated piston receptacle, a certain amount of play is necessary between the vertical extent of the piston head and the vertical extent of the piston receptacle. In any case, play between the piston head and the piston seat can hardly be avoided due to production-related fluctuations in the size or length of the piston or piston head.

However, a stable fixation of the piston head in the piston holder is important for the precession and stability of the pipetting device. If there is play between the piston head and the upper and lower ends of the piston holder, this counteracts a stable fixation. A certain amount of play is therefore necessary for assembly; this play should be eliminated as much as possible for stable operation of the pipetting device.

For this purpose, in the prior art, a spring is additionally inserted into the piston receptacle, which rests on the piston under pretension.

The document US 4,779,467 A describes a multi-channel pipetting device with several piston-cylinder units, each of which is inserted laterally into an opening in a piston receptacle. To compensate for the play, a spiral spring is arranged around each piston. Near one end of each piston there is a stop for the associated spiral spring, which holds the associated spiral spring on one side of the piston.

If the piston is inserted into the piston receptacle, the spiral spring is compressed - between the stop of the associated piston and a bottom of the opening of the piston receptacle - and thereby tensioned. In the assembled or inserted state, the spiral spring is therefore in a compressed state and in the unassembled state it is in a non-compressed state.

The documents US 3,855,868 A and EP 1 401 580A1 disclose multi-channel pipetting devices showing a spring below the piston head of the piston of each piston-cylinder unit.

The document EP 0 172 508 A2 discloses a multi-channel pipetting device in which the stroke length of each piston-cylinder unit can be shortened. This is achieved by using cylinders whose longitudinal dimensions are smaller than their transverse dimensions. This makes it possible to accommodate piston-cylinder units for larger volumes in a multi-channel pipetting device with limited space.

The Pipetman® Concept pipetting device from Gilson SAS has piston-cylinder units, each of which has a piston with a terminal spring. The springs are fixed in a blind hole at the end of the piston so that they cannot fall out. The end of each piston with the spring is inserted into a piston holder and the spring compensates for the play towards a fixation. However, here the spring is attached to the piston unprotected and not compressed, which can cause difficulties for the user in handling when inserting and removing the piston. When inserting the spring, the user must first compress it. The small spring is difficult to handle, making it difficult to assemble in production. This is also disadvantageous when using the known pipetting device, for example if the user dismantles and reassembles the pipetting device for cleaning or autoclaving or for replacing defective parts. An instruction manual (from April 2005) for the Pipetman® Concept from Gilson SAS is available at the following link: https://web.archive.org/web/20060314073341/http://www.gilson.com/PDFs/pdfid296.pdf

• https://web.archive.org/web/20060520144108/http:/www.rainin.com/pdf/manuaLclassic_multi.pdf

Another well-known multi-channel pipette on the market is the Rainin Classic® P200-8-M8 from Rainin Instruments, LLC. With this multi-channel pipette, each piston-cylinder unit can be removed individually from the pipette. After removing a housing, the piston-cylinder units are accessible. The piston of each piston-cylinder unit has a piston clip at the upper end with which it can be inserted into a piston receptacle of a piston bearing beam. The piston clip is made of a deformable and/or elastic material and is compressed when the piston is inserted into the piston receptacle. Here there is a wear and tear of the compress the material runs out, which makes it difficult to assemble and disassemble the pistons multiple times. An instruction manual (from May 2006) for the Rainin Classic® P200-8-M8 from Rainin Instruments, LLC is available at the following link:

• https://web.archive.org/web/20060520144108/http:/www.rainin.com/pdf/manuaLclassic_multi.pdf

An object of the present invention is to provide a displacement device or pipetting device which enables easy assembly of the piston-cylinder unit(s) and ensures high accuracy of the displacement device or pipetting device. The piston of the piston-cylinder unit(s) should be simple and inexpensive to produce.

According to the invention, the previously described task is solved by a displacement device according to claim 1. Preferred embodiments of this aspect of the invention are the subject of the relevant subclaims.

The displacement device according to the invention has at least one piston-cylinder unit which can be detachably connected to the displacement device and which has exactly one piston and exactly one cylinder. The piston is movably arranged in the cylinder.

• - an einem oberen Ende des Kolbens einen Kolbenkopf und an einem unteren Ende des Kolbens ein Verdrängerteil,
• - ein Rückstellmittel zur kraftschlüssigen Verbindung zwischen dem Kolben und der Kolbenaufnahme,
• - am Kolbenkopf einen positionsfesten oberen Anschlag für das Rückstellmittel und
• - einen unteren Anschlag für das Rückstellmittel.

The displacement device has a piston receptacle for each piston-cylinder unit. Each piston receptacle has at least one side wall with an opening for the piston, in particular for a piston head of the piston, a bottom wall with an opening for the piston and a top wall.
Each piston has

• - a piston head at an upper end of the piston and a displacer part at a lower end of the piston,
• - a restoring means for a non-positive connection between the piston and the piston holder,
• - on the piston head a fixed upper stop for the restoring means and
• - a lower stop for the restoring means.

The following statements on “the piston”, its components and its design always refer to each piston of all piston-cylinder units of the displacer device.

The lower stop of the piston is movably arranged on the piston in the longitudinal direction of the piston. The longitudinal direction of the piston is defined by the longest extension of the piston.

When the piston is inserted into the piston receptacle, the upper stop and the lower stop are arranged within the piston receptacle and the restoring force of the restoring means acts on the upper stop and on the lower stop and the restoring force of the restoring means presses the lower stop at least indirectly against the piston receptacle , in particular against the bottom wall of the piston receptacle, and the piston head at least indirectly against the piston receptacle, in particular against the top wall of the piston receptacle.

The design of the displacer device according to the invention enables simple assembly or simple insertion of a piston-cylinder unit into the displacer device. The user can press the lower stop against the restoring means and thus the restoring means against the upper stop and then insert the piston head together with the upper stop, lower stop and restoring means through the opening in the side wall of the piston receptacle into the piston receptacle. When the user releases the lower stop, the design according to the invention results in a frictional connection between the piston and the piston receptacle, so that there is no play between the piston and the piston receptacle. As a result, the displacement device according to the invention achieves a high level of accuracy. The piston of the piston-cylinder unit(s) requires only a few simple components and can be produced easily and inexpensively.

The piston can preferably be inserted into the piston holder through the opening in the side wall of the piston holder. Preferably, the piston cannot be inserted into the piston receptacle from below the opening in the bottom wall of the piston receptacle through the opening in the bottom wall of the piston receptacle.

Preferably, at least a region of the lower stop is arranged below the upper stop.

It is preferred if the restoring means is arranged between the upper stop and the lower stop.

An advantageous embodiment provides that the restoring means rests on the upper stop and the lower stop when the piston is inserted into the piston receptacle.

The upper stop is preferably formed by a sleeve fixed to the piston head. To fix the sleeve on the piston head, a recess surrounding the piston head can be provided. The sleeve can be attached to the piston head can be fixed by attaching it as a pressure piece, pressing on, gluing, screwing on and/or welding. The sleeve is preferably made of a plastic, for example a polyether or polyester or fluoroplastic, and/or a metal.

The lower stop is preferably connected to the piston by positive locking.

The lower stop can be formed by a sleeve that partially surrounds the piston. The sleeve is preferably made of a plastic, for example a polyether or polyester or fluoroplastic, and/or a metal. The sleeve has a bottom wall with an opening for the piston head. The sleeve is open at the top so that the piston head can pass through the sleeve.

The restoring means preferably has a spring, in particular a spiral spring, or is formed by a spring, in particular a spiral spring. In the case of a spiral spring, it surrounds the piston or the piston head partially or completely.

In a preferred embodiment, each piston has a limiter fixed to the piston, which limits movement of the lower stop in the direction of the displacer part. The limiter is arranged between the upper stop and the displacer part. At least a region of the lower stop is arranged above the limiter. Due to the limiter, the lower stop cannot be moved to the displacer part. Rather, the lower stop and thus also the restoring means remain on the piston head, even if the piston is not inserted into the piston receptacle.

The limiter is preferably arranged at the lower end of the piston head of the piston.

In particular, it can be provided that the limiter is located in the opening of the bottom wall of the piston receptacle when the piston is inserted into the piston receptacle.

In the previously explained preferred embodiment it can be provided that the restoring means rests on the upper stop when the piston is not inserted into the piston receptacle.

In the preferred embodiment explained above, it is preferred that the lower stop partially surrounds the restoring means and the upper stop when the piston is not inserted into the piston receptacle.

In a further preferred embodiment it is provided that the lower stop can be moved in the longitudinal direction of the piston up to the displacement part when the piston is not inserted into the piston receptacle. In this embodiment there is no limiter as in the previously explained preferred embodiment.

In both preferred embodiments it can be provided that the top wall of the piston receptacle has a preferably concave recess or a centering opening and the piston head has a preferably convex formation at one end. When the piston is inserted into the piston receptacle, in this case the restoring force of the restoring means presses the formation into or against the recess or the centering opening. In particular, the formation engages with the recess or the centering opening. It is particularly preferred if the piston head is centered in the piston receptacle by means of the recess or centering opening and the molding when the piston is inserted into the piston receptacle.

The displacement device preferably has several, in particular eight or twelve, piston-cylinder units that can be detachably connected to the displacement device.

It has proven to be advantageous if all piston receptacles are preferably arranged next to one another in exactly one common piston receptacle bar of the displacer device. The piston receiving bar can be displaced in the longitudinal direction of the pistons, in particular by means of exactly one piston actuator of the displacer device.

It is preferred if the displacement device has a connecting device by means of which the displacement device can be releasably connected to a handle part of a pipetting device, this connection being rigid in the longitudinal direction, but allowing the displacement device to rotate relative to the handle part about the longitudinal axis.

The displacement device preferably has an outer housing surrounding all piston receptacles.

The displacement device preferably has exactly one cylinder receiving bar, on which all cylinders of the piston-cylinder units inserted into the displacement device are preferably attached next to one another.

According to the invention, the task described above is solved by a pipetting device according to claim 14. Preferred configuration This aspect of the invention is the subject of the relevant subclaims.

The pipetting device according to the invention is used to absorb and dispense fluid volumes and has a displacement device as explained above.

The pipetting device according to the invention enables simple assembly or simple insertion of a piston-cylinder unit into the displacement device. The construction according to the invention leads to a non-positive connection between the piston and the piston receptacle, so that there is no play between the piston and the piston receptacle. As a result, the pipetting device according to the invention achieves a high level of accuracy. The piston of the piston-cylinder unit(s) requires only a few simple components and can be produced easily and inexpensively.

The pipetting device preferably has a handle part that structurally defines a longitudinal axis and a piston drive device that is axially adjustable in the direction of the longitudinal axis. The handle part can be releasably connected to the displacement device by means of a connecting device and the piston drive device can be detachably connected to a piston actuator of the displacement device.

The invention is explained in more detail below based on the description of preferred exemplary embodiments, partly with reference to the drawing. The features described above and/or disclosed in the claims and/or in the following description can, if necessary, be combined with one another but can also be implemented independently of one another, even if this is not expressly described in detail.

• 1 schematisch in einer Frontansicht eine erste bevorzugte Ausführungsform einer erfindungsgemäßen Verdrängereinrichtung,
• 2 schematisch in einer Draufsicht die Verdrängereinrichtung aus 1,
• 3 schematisch einen Schnitt entlang der Linie A-A durch die Verdrängereinrichtung aus 2,
• 4 schematisch eine vergrößerte Darstellung des Details B aus 3,
• 5 schematisch einen Schnitt entlang der Längsachse durch einen Kolben der ersten bevorzugten Ausführungsform in einem Zustand, in dem der Kolben nicht in die Verdrängereinrichtung eingesetzt ist,
• 6 schematisch in einer Frontansicht eine zweite bevorzugte Ausführungsform einer erfindungsgemäßen Verdrängereinrichtung,
• 7 schematisch in einer Draufsicht die Verdrängereinrichtung aus 6,
• 8 schematisch einen Schnitt entlang der Linie A-A durch die Verdrängereinrichtung aus 7,
• 9 schematisch eine vergrößerte Darstellung des Details B aus 8,
• 10 schematisch einen Schnitt entlang der Längsachse durch einen Kolben der zweiten bevorzugten Ausführungsform in einem Zustand, in dem der Kolben nicht in die Verdrängereinrichtung eingesetzt ist,
• 11 schematisch in einer perspektivischen Ansicht eine erste bevorzugte Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung,
• 12 schematisch in einer Frontansicht die Verdrängereinrichtung aus 1, wobei ein Außengehäuse der Verdrängereinrichtung weggelassen ist, und
• 13 schematisch in einer Frontansicht die Verdrängereinrichtung aus 6, wobei ein Außengehäuse der Verdrängereinrichtung weggelassen ist.

Shown in the drawing

• 1 schematically in a front view a first preferred embodiment of a displacement device according to the invention,
• 2 schematically in a top view of the displacement device 1 ,
• 3 schematically a section along line AA through the displacement device 2 ,
• 4 schematically an enlarged representation of detail B 3 ,
• 5 schematically a section along the longitudinal axis through a piston of the first preferred embodiment in a state in which the piston is not inserted into the displacement device,
• 6 schematically in a front view a second preferred embodiment of a displacement device according to the invention,
• 7 schematically in a top view of the displacement device 6 ,
• 8th schematically a section along line AA through the displacement device 7 ,
• 9 schematically an enlarged representation of detail B 8th ,
• 10 schematically a section along the longitudinal axis through a piston of the second preferred embodiment in a state in which the piston is not inserted into the displacement device,
• 11 schematically in a perspective view a first preferred embodiment of a pipetting device according to the invention,
• 12 schematically in a front view of the displacement device 1 , wherein an outer housing of the displacement device is omitted, and
• 13 schematically in a front view of the displacement device 6 , wherein an outer housing of the displacement device is omitted.

1 shows a schematic front view of a first preferred embodiment of a displacement device 1 according to the invention. 2 shows this displacement device 1 schematically in a top view. The displacement device 1 is intended for use in a pipetting device for receiving and dispensing fluid volumes. This displacement device 1 is a pipetting device 1 based on the air cushion principle.

The displacement device 1 shown has several, namely twelve, piston-cylinder units 2 that can be detachably connected to the displacement device 1. Each piston-cylinder unit 2 has exactly one piston 3 and exactly one cylinder 4. The piston 3 is movably arranged in the cylinder 4.

3 shows schematically a section along line AA through the displacement device 1 2 . As in 3 can be seen, the displacement device 1 has one piston receptacle 5 for each piston-cylinder unit 2, a total of twelve piston receptacles 5. Each piston receptacle 5 has four side walls 6, one of the side walls 6 having an opening 7 for the piston 3 of one of the piston Cylinder units 2. Each piston receptacle 5 also has a bottom wall 8 with an opening 9 for the piston 3 of one of the piston-cylinder units 2 and a top wall 10. In the one shown In this embodiment, the ceiling wall 10 has an opening 11.

In the 1-4 and 12 the piston-cylinder units 2 are inserted into the respective piston receptacle 5.

• - an einem oberen Ende des Kolbens 3 einen Kolbenkopf 12 und an einem unteren Ende des Kolbens 3 ein Verdrängerteil 13,
• - ein Rückstellmittel 14 zur kraftschlüssigen Verbindung zwischen dem Kolben 3 und einer der Kolbenaufnahmen 5,
• - am Kolbenkopf 12 einen positionsfesten oberen Anschlag 15 für das Rückstellmittel 14 und
• - einen unteren Anschlag 16 für das Rückstellmittel 14.

Each piston has 3

• - at an upper end of the piston 3 a piston head 12 and at a lower end of the piston 3 a displacer part 13,
• - a restoring means 14 for a non-positive connection between the piston 3 and one of the piston receptacles 5,
• - On the piston head 12 a fixed upper stop 15 for the restoring means 14 and
• - a lower stop 16 for the restoring means 14.

The following statements regarding a piston 3, its components and its design apply to every piston 3 of all piston-cylinder units 2 of the displacer device 1.

The lower stop 16 of the piston 3 is movably arranged on the piston 3 in the longitudinal direction L of the piston 3. The longitudinal direction L of the piston 3 is defined by the longest extension of the piston 3.

4 shows schematically an enlarged representation of detail B 3 . In 4 the state is shown when the piston 3 is inserted into one of the piston receptacles 5. In this state, the upper stop 15 and the lower stop 16 are arranged within the piston receptacle 5. In this case, the restoring force of the restoring means 14 acts on the upper stop 15 and on the lower stop 16 and presses the lower stop 16 against the piston receptacle 5, in particular against an inside of the bottom wall 8 of the piston receptacle 5, and presses the piston head 12 of the piston 3 against the piston receptacle 5, in particular against an inside of the top wall 10 of the piston receptacle 5. When the piston 3 is inserted into the piston receptacle 5, there is a non-positive connection between the piston 3 and the piston receptacle 5.

In the embodiment shown, a region of the lower stop 16 is arranged below the upper stop 15. The restoring means 14 is arranged between the upper stop 15 and the lower stop 16. The restoring means 14 rests here on the upper stop 15 and on the lower stop 16 when the piston 3 is inserted into one of the piston receptacles 5.

In the embodiment shown, the upper stop 15 is formed by a sleeve 15 fixed to the piston head 12. To fix the sleeve 15 on the piston head 12, a recess 17 surrounding the piston head 12 is provided.

In the embodiment shown, the lower stop 16 is formed by a sleeve 16 which partially surrounds the piston 3. The sleeve 16 has a bottom wall 18 with an opening 19 for the piston head 12. The sleeve is open at the top so that the piston head 12 together with the sleeve 15 can pass through the sleeve 16.

In the embodiment shown, the restoring means 14 is formed by a spiral spring 14. The spiral spring 14 surrounds the piston 3 or the piston head 12 in areas.

At the in the 1-5 and 12 In the embodiment shown, each piston 3 has a limiter 20 fixed to the piston 3, which limits movement of the lower stop 16 in the direction of the displacer part 13. The limiter 20 is formed by a projection running transversely to the longitudinal direction L and surrounding the piston 3 in the circumferential direction. The limiter 20 is arranged between the upper stop 15 and the displacement part 13, namely at the lower end of the piston head 12 of the piston 3. The lower stop 16 is arranged above the limiter 20. Due to the limiter 20, the lower stop 16 cannot be moved to the displacement part 13. Rather, the lower stop and thus also the restoring means remain on the piston head, even if the piston is not inserted into the piston receptacle. When the piston 3 is inserted into one of the piston receptacles 5, the limiter 20 is located in the opening 9 of the bottom wall 8 of the piston receptacle 5.

5 shows schematically a section along the longitudinal axis through a piston 3 of the first preferred embodiment in a state in which the piston 3 is not inserted into the piston receptacle 5. In this state, in the embodiment shown, the restoring means 14 rests on the upper stop 15 and the lower stop 16 partially surrounds the restoring means 14 and the upper stop 15.

The 6-10 and 13 show schematically a second preferred embodiment of a displacement device 1 according to the invention. 6 shows a front view and 7 a top view of this displacement device 1. In contrast to the first preferred embodiment, there is no limiter 20 in the second preferred embodiment. The two preferred embodiments do not differ in the remaining design and functional features.

Due to the missing limiter 20, in the second preferred embodiment, the lower stop 16 can be moved in the longitudinal direction of the piston 3 up to the displacement part 13 if the piston 3 is not inserted into one of the piston receptacles 5. This is in 10 to recognize. 10 shows schematically a section along the longitudinal axis through a piston 3 of the second preferred embodiment in a state in which the piston 3 is not inserted into the piston receptacle 5. In this state, in the embodiment shown, the lower stop 16 rests on the displacement part 13 and the restoring means 14 rests on the lower stop 16. The restoring means 14 is relaxed or not compressed.

In the 5-9 and 13 the piston-cylinder units 2 are inserted into the respective piston receptacle 5.

In both preferred embodiments, the piston 3 can be inserted into the piston receptacle 5 through the opening 7 of the side wall 6 of the piston receptacle 5. Due to the dimensioning of the piston 3 including the upper stop 15, lower stop 16 and restoring means 14 as well as the dimensioning of the opening 9 of the bottom wall 8, the piston 3 is not from below the opening 9 of the bottom wall 8 of the piston receptacle 5 through the opening 9 of the bottom wall 8 Piston holder 5 can be inserted into the piston holder 5.

In both preferred embodiments, the top wall 10 of the piston receptacle 5 has a centering opening 29 and the piston head 12 has a convex formation at one end. When the piston 3 is inserted into the piston receptacle 5, the restoring force of the restoring means 14 presses the formation 30 into or against the centering opening 29. The formation 30 is then in engagement with the centering opening 29. The piston head 12 is then centered in the piston receptacle 5 by means of the centering opening 29 and the molding 30.

In both preferred embodiments, all piston receptacles 5 are arranged next to one another in exactly one common piston receptacle bar 21 of the displacement device 1. The piston receiving bar 21 can be displaced in the longitudinal direction L of the pistons 3, namely by means of exactly one piston actuator 22 of the displacer device 1.

In both preferred embodiments, the displacement device 1 has a connecting device 23, by means of which the displacement device 1 can be releasably connected to a handle part of a pipetting device, this connection being rigid in the longitudinal direction L, but allowing the displacement device 1 to rotate relative to the handle part about the longitudinal axis.

In both preferred embodiments, the displacement device 1 has an outer housing 24 surrounding all piston receptacles 5 and exactly one cylinder receiving bar 25, on which all cylinders 4 of the piston-cylinder units 2 inserted into the displacement device 1 are attached next to one another.

11 shows schematically a perspective view of a first preferred embodiment of a pipetting device 26 according to the invention. The pipetting device 26 according to the invention serves to absorb and dispense fluid volumes and has a displacement device 1 as explained above.

The illustrated and preferred pipetting device 26 has a handle part 27 which structurally defines a longitudinal axis A and a piston drive device 28 which is axially adjustable in the direction of the longitudinal axis A. The handle part 27 is detachably connected to the displacer device 1 by means of a connecting device 23 and the piston drive device 28 to a piston actuator 22 of the displacer device 1.

The information “above” and “below” refers to the corresponding components as shown in the 1-13 are shown and aligned.

List of reference symbols:

1

Displacer device

2

Piston-cylinder unit of 1

3

Piston of 2

4

Cylinder of 2

5

Piston intake from 1

6

Side wall of 5

7

Opening from 6

8th

Floor wall of 5

9

Opening from 8

10

Ceiling wall of 5

11

Opening from 10

12

Piston head from 3

13

Displacer part of 3

14

Resetting agent of 3

15

upper stop of 3

16

lower stop of 3

17

Recess of 3

18

Floor wall from 16

19

Opening from 4pm

20

Limiter of 3

21

Piston support beam from 1

22

Piston actuator from 1

23

Connection setup of 1

24

Outer casing of 1

25

Cylinder support beam from 1

26

Pipetting device

27

Grip part of 26

28

Piston drive device from 26

29

Centering opening of 10

30

Formation of 12

L

Longitudinal direction of 3

A

Longitudinal axis of 27

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4779467 A [0021]
• US 3855868 A [0023]
• EP 1401580 A1 [0023]
• EP 0172508 A2 [0024]

Claims (15)

Displacer device (1) for a pipetting device (26) for receiving and dispensing fluid volumes, comprising: - at least one piston-cylinder unit (2) which can be detachably connected to the displacement device (1) and which has a piston (3) and a cylinder (4), the piston (3) being movably arranged in the cylinder (4), - one piston receptacle (5) for each piston-cylinder unit (2), each piston receptacle (5) having at least one side wall (6) with an opening (7) for the piston (3), in particular for a piston head (12). of the piston (3), a bottom wall (8) with an opening (9) for the piston (3) and a top wall (10), each piston (3) - has a piston head (12) at an upper end of the piston (3) and a displacer part (13) at a lower end of the piston (3), - has a restoring means (14) for the non-positive connection between the piston (3) and the piston receptacle (5), - Has a fixed upper stop (15) on the piston head (12) for the restoring means (14) and - has a lower stop (16) for the restoring means (14), the lower stop (16) being movably arranged on the piston (3) in the longitudinal direction (L) of the piston (3), whereby when the piston (3) is in the piston receptacle (5) is inserted, the upper stop (15) and the lower stop (16) are arranged within the piston receptacle (5) and the restoring force of the restoring means (14) is applied to the upper stop (15) and to the lower stop ( 16) acts and the lower stop (16) at least indirectly against the piston receptacle (5), in particular against the bottom wall (8) of the piston receptacle (5), and the piston head (12) at least indirectly against the piston receptacle (5), in particular against the Top wall (10) of the piston holder (5) presses. Displacer device after Claim 1 , wherein at least a region of the lower stop (16) is arranged below the upper stop (15) and / or the restoring means (14) is arranged between the upper stop (15) and the lower stop (16). Displacer device after Claim 1 or 2 , whereby when the piston (3) is inserted into the piston receptacle (5), the restoring means (14) rests on the upper stop (15) and the lower stop (16). Displacer device according to one of the preceding claims, wherein the upper stop (15) is formed by a sleeve (15) fixed to the piston head (12) and/or the lower stop (16) is formed by a sleeve (16) which partially surrounds the piston (3). . Displacer device according to one of the preceding claims, wherein the restoring means (14) has or is formed by a spring (14), in particular a spiral spring (14). Displacer device according to one of the preceding claims, wherein each piston (3) has a limiter (20) fixed to the piston (3), which limits movement of the lower stop (16) in the direction of the displacer part (13), the limiter (20) between the upper stop (15) and the displacement part (13), preferably at the lower end of the piston head (12) of the piston (3), and at least a region of the lower stop (16) is arranged above the limiter (20). . Displacer device after Claim 6 , whereby when the piston (3) is not inserted into the piston receptacle (5), the restoring means (14) rests on the upper stop (15). Displacer device according to one of the preceding claims, wherein, when the piston (3) is not inserted into the piston receptacle (5), the lower stop (16) partially surrounds the restoring means (14) and the upper stop (15). Displacer device according to one of the Claims 1 until 5 , whereby, if the piston (3) is not inserted into the piston receptacle (5), the lower stop (16) can be moved in the longitudinal direction (L) of the piston (3) up to the displacer part (13). Displacer device according to one of the preceding claims, wherein the piston (3) can be inserted into the piston receptacle (5) through the opening (7) of the side wall (6) of the piston receptacle (5). Displacer device according to one of the preceding claims, wherein the top wall (10) of the piston receptacle (5) has a preferably concave recess or a centering opening (29) and the piston head (12) has a preferably convex formation (30) at one end, whereby if the Piston (3) is inserted into the piston receptacle (5), the restoring force of the restoring means (14) presses the formation (30) into or against the recess or the centering opening (29) and, preferably, the piston head (12) by means of the Recess or centering opening (29) and the molding (30) is centered in the piston receptacle (5). Displacer device according to one of the preceding claims, wherein the displacement cleaning device (1) has a connecting device (23) by means of which the displacement device (1) can be detachably connected to a handle part (27) of a pipetting device (26), this connection being rigid in the longitudinal direction (L), but a rotation of the displacement device ( 1) relative to the handle part (27) around the longitudinal axis (A). Displacer device according to one of the preceding claims, wherein the displacer device (1) has exactly one cylinder receiving bar (25) on which all cylinders (4) of the piston-cylinder units (2) inserted into the displacer device (1) are preferably attached next to one another. Pipetting device (26) for receiving and dispensing fluid volumes, comprising a displacement device (1) according to one of the preceding claims. pipetting device Claim 14 , wherein the pipetting device (26) has a structurally defining a longitudinal axis (A) handle part (27) and a piston drive device (28) which is axially adjustable in the direction of the longitudinal axis (A), the handle part (27) being connected to the by means of a connecting device (23). Displacer device (1) and the piston drive device (28) can be detachably connected to a piston actuator (22) of the displacer device (1).

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