EP4134166A1 - Pipette for use with a pipette tip - Google Patents

Abstract

Pipette for use with a pipette tip, comprising• an elongate chassis,• components connected to the chassis of a device for detachably holding at least one pipette tip and a drive device for displacing a displacement element for sucking in liquid samples into the pipette tip and ejecting the samples from the pipette tip, • a tubular pipette housing which surrounds the chassis, with the longitudinal direction of the chassis being aligned in the longitudinal direction of the pipette housing, and which is connected to the chassis, with• the chassis having a plurality of tubular chassis elements which are arranged one behind the other and connected to one another, and• that the components of the device for detachably holding at least one pipette tip and the drive device are connected to different chassis elements.

Description

The invention relates to a pipette for use with a pipette tip.

Pipettes are used in particular in scientific and industrial laboratories with medical, molecular biological and pharmaceutical fields of application for dosing selected volumes of liquids. The liquids can in particular be homogeneous (single-phase) liquids consisting of a single liquid component or of a homogeneous mixture of a plurality of liquid components (solutions). Furthermore, the liquids can be heterogeneous (multi-phase) mixtures of a liquid with another liquid (emulsions) or a solid (suspension).

Known pipettes have a handle-shaped pipette housing with a pin (approach) at the lower end for clamping on a pipette tip. The pin is often a conical, cylindrical or partially conical and cylindrical projection and is also referred to as a "working cone". A pipette tip is a hollow tube with a tip opening at the bottom and an attachment opening at the top, with which the pipette tip can be clamped onto the spigot. The liquid is aspirated into and dispensed from the pipette tip. Pipette tips without an integrated piston and pipette tips with an integrated piston are known. The uptake and delivery of the liquid is controlled by the pipette. Fixed-volume pipettes are used for pipetting constant volumes. With variable pipettes, the volume to be dosed can be adjusted. To adjust the volume, the stroke of a drive device can be adjusted by means of an adjustment device. A mechanical counter, which is coupled to the setting device, is used to display the set volume. The pipette tip is detached from the attachment after use and can be exchanged for a fresh pipette tip. In this way, cross-contamination can be avoided during subsequent pipetting. Most pipettes have a Ejection device that allows you to eject pipette tips by pressing a button without touching the pipette tips.

Air-cushion pipettes usually have a piston-cylinder arrangement in the pipette housing, which is connected via a channel to a through-hole in the spigot. Pipette tips for air cushion pipettes (air cushion pipette tips) do not have an integrated piston. By displacing the piston by means of the drive device in the cylinder, an air cushion is moved in order to suck liquid into and eject liquid from a pipette tip clamped onto the spigot. A disadvantage of air cushion pipettes are dosing errors due to changes in the length of the air cushion due to the weight of the liquid sucked in and changes in temperature, air pressure and humidity. Contamination of the pipette by aerosols can also be problematic.

Positive displacement pipettes are used with pipette tips with an integrated piston (positive displacement pipette tips). This type of pipette has a spigot for fastening the pipette tip and a drive device, which can be coupled to the integrated piston (tip piston), for displacing the piston. The piston comes in direct contact with the liquid, eliminating the adverse effects of an air pocket. Positive displacement pipettes are particularly suitable for dispensing liquids with a high vapor pressure, high viscosity or high density and for applications in molecular biology where freedom from aerosols is important to avoid contamination.

Pipettes are usually hand-held devices that can be held and operated by the user with just one hand during use. Manually driven pipettes are known in which the drive device is driven by muscle power. Furthermore, pipettes driven by an electric motor are known in which the Drive device comprises an electric motor and control electronics for controlling the electric motor.

Air cushion or positive displacement pipette tips for single use for reuse are made of plastic or glass.

In the EP 2 633 915 B1 is an air cushion pipette for use with an air cushion pipette tip and in the EP 3 560 596 A1 describes a positive displacement pipette for use with a positive displacement pipette tip.

In conventional pipettes, the pin for clamping on the pipette tip, components of the drive device and possibly other components are held directly on the pipette housing. The pipette housing thus serves as a supporting structure for the components of the pipette. As a result, all forces generated during pipetting are transmitted to the housing at various points. The result of this is that the housing has to be designed in a complex manner, which makes an injection molding tool for producing the housing complicated and expensive. In addition, all components of the pipette have to be mounted in or on the housing, so that the assembly as a whole is complex. Another consequence is that the choice of material for the housing is restricted, since the material must be suitable for absorbing the forces that arise. In particular, no soft housing materials can be used and their application advantages cannot be used. In addition, problems can arise during autoclaving if the pipette components are attached to the housing at different points.

The EP 2 578 317 B1 and U.S. 9,180,446 describe a hand-held dispensing device having a supporting structure which has means for releasably holding a lower end syringe or pipette tip and in which driving means for a piston for displacing a fluid in the syringe or pipette tip are fixed to the supporting structure above the means for releasably holding. The load-bearing structure is formed by an elongated frame having parallel, spaced-apart longitudinal members in such a way that forces occurring when the drive means are actuated are introduced into the frame. The housing encloses the drive means and the frame and is preferably mounted on the frame at only a few points to relieve the housing. The longitudinal beams of various frame parts have interlocking connection structures and there are fastening means connecting these connection structures to one another. An exemplary embodiment of a dispenser is described in detail. This is a positive displacement system for use with a syringe in which the barrel of the syringe is held in place and the plunger is pulled slightly out of the barrel using a winding lever to aspirate liquid. To dispense the liquid that has been taken up, the piston is pushed deeper into the cylinder by means of a rack and pinion device with adjustable increments. Compared to pipette tips with or without an integrated plunger, the syringes usually have a much larger volume. Also described is a pipette in which means for releasably holding a pipette tip are arranged at the lower end of the elongated frame having parallel spaced longitudinal members and a cylinder with a piston displaceable therein and drive means for the piston are attached above the means for releasable holding.

The EP 3 399 215 A1 describes an electronic hand dispenser with a spindle drive, which comprises a supporting structure to which a guide element for the drive spindle is fixedly connected and to which an electric drive motor for the drive spindle is attached. The supporting structure is a housing and/or a Frame (chassis) and / or a carrier and consists of a single or multiple components.

The DE 11 2016 006 174 T5 describes a bottom part of a multi-channel pipette with a unit housing designed as a double housing construction with a front and a rear housing on which attachments for pipette tips are held. An ejector shroud having a front shroud and a rear shroud houses the unit housing.

The EP 1 015 110 B1 describes a pipette with a rigid plastic frame embedded in a cushioned membrane that comfortably conforms to the user's hand. The frame is tubular and in the frame are arranged in series and partially interlocking components of a drive means, a counter and a gear for transmitting the setting of a volume adjustment ring to the counter. The volume adjustment ring is mounted between a lower part of the pipette, in which a cylinder with a piston that can be displaced therein is arranged, and an upper part of the pipette, which includes the membrane and the frame embedded therein. The assembly of the pipette is complex.

The EP 3 159 397 B1 describes a pipetting head for an automatic pipetting machine, which has a cylinder on a first frame with a piston that can be displaced therein and a spindle drive with an electric drive motor for the piston. A tip ejector is arranged on a second frame, which can be displaced relative to the first frame by means of a spindle drive, in order to push off a pipette tip placed on the cylinder.

Proceeding from this, the object of the invention is to provide a pipette for use with a pipette tip which facilitates assembly, absorbs the forces occurring during use and allows the pipette housing to be configured more freely.

The object is achieved by a pipette having the features of claim 1. Advantageous embodiments of the pipette are specified in the dependent claims.

• ein längliches Chassis,
• mit dem Chassis verbundene Bauteile einer Einrichtung zum lösbaren Halten mindestens einer Pipettenspitze und einer Antriebseinrichtung zum Verlagern eines Verdrängungselementes zum Einsaugen von flüssigen Proben in die Pipettenspitze und Ausstoßen der Proben aus der Pipettenspitze,
• ein rohrförmiges Pipettengehäuse, das das Chassis umgibt, wobei die Längsrichtung des Chassis in Längsrichtung des Pipettengehäuses ausgerichtet ist, und das mit dem Chassis verbunden ist,
  dadurch gekennzeichnet, dass
• das Chassis mehrere rohrförmige Chassiselemente aufweist, die hintereinander angeordnet und miteinander verbunden sind, und
• die Bauteile der Einrichtung zum lösbaren Halten mindestens einer Pipettenspitze und der Antriebseinrichtung mit verschiedenen Chassiselementen verbunden sind.

The pipette according to the invention for use with a pipette tip comprises:

• an elongated chassis,
• components connected to the chassis of a device for detachably holding at least one pipette tip and a drive device for displacing a displacement element for sucking in liquid samples into the pipette tip and ejecting the samples from the pipette tip,
• a tubular pipette housing surrounding the chassis, with the longitudinal direction of the chassis being aligned with the longitudinal direction of the pipette housing, and which is connected to the chassis,
  characterized in that
• the chassis comprises a plurality of tubular chassis members arranged in tandem and interconnected, and
• the components of the device for detachably holding at least one pipette tip and the drive device are connected to different chassis elements.

In the case of the pipette according to the invention, the chassis has a number of tubular chassis elements which are connected to one another. The chassis is also referred to as the frame and the chassis members are also referred to as the frame members. The Chassis elements enable a step-by-step assembly of assemblies consisting of chassis elements with associated components, so that the components are held captive on the chassis elements. The components can be all components relevant to the function of the pipette. The components relevant to the function of the pipette include at least the components of the device for detachable holding and the components of the drive device. Optionally, the components of other devices are added, in particular components of a display device for displaying a set dosing volume and/or an ejection device for ejecting at least one pipette tip from a spigot onto which it is clamped. The pipette body is connected to the chassis.

A major advantage is that by connecting the components to the chassis elements, all forces can be absorbed by the chassis. In this case, high-strength materials can be used for the chassis elements, since no materials have to be used for the chassis that are desired for the housing in order to achieve a specific design or haptic properties of the pipette. As a result, materials can be used for the housing that were out of the question for conventional pipettes, without having to give up the strength needed to absorb the forces. Due to the possible formation of the chassis element from corresponding high-strength materials, a reproducible accuracy of the traversing paths of the drive device can also be guaranteed. Another advantage is that the components can be pre-assembled separately on the various chassis elements, which makes assembly easier. To further facilitate assembly, the components can be captively pre-assembled on the chassis elements. An assembly (also called "pre-assembly" or "module") can be formed from one or more components and one chassis element each, which can be checked independently during assembly, which has advantages in terms of quality assurance. Also the complete or partial dismantling of the pipette for maintenance or repair purposes is facilitated by the construction of the pipette from chassis elements and associated components. Assemblies can be serviced and repaired independently. Furthermore, a chassis element can be designed to accommodate a lower part, as a result of which a retaining ring that previously had to be fixed separately in the housing can be replaced. Due to the modular design, different pipettes can be assembled using similar assembly steps, and functional assemblies can be varied by replacing or omitting individual components or assemblies of chassis elements and components. In addition, many identical parts can be used for different pipettes. A further advantage is that the development effort for further pipettes is reduced, since at least part of the basic structure of the pipette can continue to be used.

Because the chassis comprises a plurality of tubular chassis elements, a particularly stable design of the chassis is made possible, which withstands relatively high forces while using relatively little material. In addition, the tubular chassis elements favor particularly simple and stable connections of the tubular chassis elements to one another. A further advantage is that the tubular chassis elements are particularly well suited for the space-saving accommodation of the various tubular or rod-shaped components of the pipette. Another advantage is that the components can be protected in the tubular chassis elements. Finally, the chassis with the tubular chassis elements and the associated components can be easily inserted into the tubular pipette housing, for example by sliding through a lower or upper opening of a one-piece tubular pipette housing, by sliding parts of the tubular pipette housing over the ends of the chassis or by inserting of the chassis into a shell of one multi-shell tubular pipette body. This also makes it easier to dismantle the pipette.

Tubular chassis elements within the meaning of the present application are circular cylinders, cylinders with a cross section other than a circular cross section and other elongate hollow bodies, wherein the length of the hollow body can be greater, smaller than or equal to the maximum dimension of the hollow body perpendicular to the longitudinal axis of the hollow body. The tubular chassis members can also be sections or segments of a cylinder or other elongate hollow body. Furthermore, the tubular chassis members may have inwardly projecting structures and/or outwardly projecting structures with respect to their surfaces, thereby deviating from the shape of a cylinder or a simple elongate hollow body. The tubular chassis elements can be chassis elements that have at least one tubular section and one non-tubular section in a longitudinal direction one behind the other, with the tubular section being connected to the non-tubular section. For example, the tubular chassis member may have multiple annular or ring-segment-shaped sections connected to one another via one or more rod-shaped sections, or only a single annular or ring-segment-shaped section connected to one or more rod-shaped sections. A ring-shaped or ring-segment-shaped section of the chassis element is preferably connected to a further tubular chassis element.

According to one embodiment of the invention, all of the chassis elements are tubular. This enables a particularly stable chassis with a relatively low cost of materials.

According to a further embodiment, the chassis comprises one or more non-tubular chassis elements in addition to a plurality of tubular chassis elements. Non-tubular chassis elements include, in particular, chassis elements made from one or more rods (e.g. with a rectangular profile, circular profile, cross profile, U-profile, C-profile, T-profile each with a full cross-section or hollow cross-section) or from one or more frames ( e.g. formed from rods of the aforementioned type). Furthermore, the non-tubular chassis elements can include those chassis elements which are formed by one or more plates. The non-tubular chassis elements can in particular bridge the space between two tubular chassis elements or be arranged at the upper or lower end of the chassis.

According to a further embodiment, the chassis comprises exactly two or exactly three or exactly four tubular chassis elements.

According to a further embodiment, at least one component of a drive device for displacing a displacement element is connected to at least one chassis element and/or at least one component of a display device for displaying a set pipetting volume is connected to at least one chassis element and/or at least one component of a ejection device for ejecting at least a pipette tip is connected by a pin to at least one chassis element and/or at least one component of a device for detachably holding at least one pipette tip is connected to at least one chassis element and/or at least one component of a device for detachably holding the chassis elements in the pipette housing is connected to at least one chassis element tied together. This further facilitates the assembly and disassembly of the pipette.

According to a further embodiment, a first subassembly comprises a chassis element and at least one component of the drive device and/or a second subassembly comprises a chassis element and at least one component of the display device and/or a third subassembly comprises a chassis element and at least one component of the release device and/or comprises a fourth assembly comprises a chassis element and at least one component of the device for detachably holding at least one pipette tip and/or a fifth assembly comprises a chassis element and at least one component of the device for detachably holding the chassis elements in the pipette housing.

According to a further embodiment, the drive device comprises a first subassembly made up of several components which is connected to at least one chassis element and/or the display device comprises a second subassembly made up of several components which is connected to at least one chassis element and/or the ejection device comprises a third subassembly consists of several components, which is connected to at least one chassis element and/or the device for detachably holding at least one pipette tip comprises a fourth sub-assembly made of several components which is connected to at least one chassis element and/or comprises the device for detachably holding the chassis elements in the pipette housing at least one fifth sub-assembly of multiple components connected to at least one chassis element. This enables at least one subassembly to be preassembled in a first preassembly step and at least one subassembly to be preassembled with at least one chassis element in a second preassembly step, and assembly and disassembly is further facilitated.

The pre-assembly of at least one subassembly can also be combined with the pre-assembly of at least one component on the same chassis element. According to a further embodiment, components of the drive device (e.g. an actuating element, a threaded spindle, a spindle nut and a lifting rod) are connected to a first chassis element and/or are components of the display device (e.g. a counter and/or a transmitter and/or a factory calibration device) is connected to a second chassis element and/or are components of the drive device (e.g. an overstroke system and/or customer calibration) and/or components of the ejection device connected to a third chassis element and/or is at least one component of the device for detachably holding at least one pipette tip (eg a tubular coupling element for a base) connected to a fourth chassis element or formed as such. This is an advantageous embodiment of an air cushion pipette.

According to a further embodiment, components of the drive device (e.g. a threaded spindle and a spindle nut) and/or components of the display device (e.g. a counter) are connected to a first chassis element and/or components of the drive device (e.g. an actuating element and/or a lifting rod and/or a switching device for switching the displacement of a lifting rod in different directions) and/or components of the ejection device (e.g. a rotary sleeve) are connected to a second chassis element and/or are components of the drive device (e.g. toothed racks and drive pinions for moving a lifting rod ) is connected to a third chassis element and/or components of the ejection device (e.g. an ejection rod and/or a locking sleeve) and/or components of the device for detachably holding at least one pipette tip (e.g. a pin) are connected to a fourth chassis element. This is an advantageous embodiment of a positive displacement pipette.

According to a further embodiment, the first chassis element is arranged above the second chassis element, the second chassis element is arranged above the third chassis element and the third chassis element is arranged above the fourth chassis element.

According to a further embodiment, at least one component and/or at least one subassembly is arranged at least partially inside and/or laterally on a tubular chassis element connected thereto.

According to a further embodiment of an air-cushion pipette, the drive device has a threaded spindle which engages in an internal thread of the first chassis element and can be adjusted in the longitudinal direction of the first chassis element. According to a further embodiment, the drive device has an adjusting sleeve rotatably mounted in the first chassis element and connected to the threaded spindle in a rotationally fixed manner and longitudinally displaceable relative to one another, with an adjusting knob protruding upwards from the first chassis element. According to a further embodiment, the drive device has a driver sleeve which is arranged concentrically to the adjustment sleeve and has circumferential teeth, the adjustment sleeve has two circumferential teeth of different diameters on its circumference, and the drive device has a transmitter with pinions of different diameters, with displacement of the adjustment sleeve or of the transmission from an upper to a lower position, different pinions of the transmitter can be brought into engagement with the toothing of the adjusting sleeve and the driver sleeve, and as a result different translations between the adjusting sleeve and driver sleeve can be set. In this embodiment, the drive sleeve is rotatably mounted in the first chassis member and is the Driving sleeve with the threaded spindle rotatably and in the longitudinal direction relative to each other displaceably connected. According to a further embodiment, the drive device has a through-hole extending in the longitudinal direction of the threaded spindle, which can be displaced with at least one projection on the circumference until it contacts a first stop on the underside of the threaded spindle, forms the drive element below the projection and has an operating button on the upper end of the first chassis member protruding lifting rod. As a result, the essential components of a drive device are connected to the first chassis element.

Details of a pipette with an adjustable translation between the adjusting sleeve and the driving sleeve are in the European patent application EP 19 191 903.4 described. In this regard, reference is made to the European patent application EP 19 191 903.4 , the content of which is hereby incorporated into this application.

According to a further embodiment of an air-cushion pipette, the second chassis element is held at the lower end of the first chassis element and a counter is held on holding devices on the jacket of the second chassis element and the first chassis element. This simplifies the pre-assembly of the counter and its connection to the drive device. According to a further embodiment, the transformer is held on holding devices on the shell of the second chassis element and the first chassis element.

According to a further embodiment of an air-cushion pipette, the third chassis element is connected to the lower end of the first chassis element and/or the second chassis element and an overlift system with a passage through which the lifting rod extends is arranged within the third chassis element extends downwards through it, with the lifting rod being displaceable further downwards against the action of an overtravel spring after the projection has hit a second stop on the upper side of the overtravel system when it is displaced downwards. This simplifies the pre-assembly of the overlift system and its coupling to the lifting rod.

According to a further embodiment of an air-cushion pipette, the fourth chassis element is a tubular coupling element and a lower part with a connecting pin inserted into the coupling element, the lower part having at least one displacement element in a displacement chamber and a hollow pin connected to the displacement chamber for detachably holding a pipette tip. A tubular coupling element at the lower end of the chassis is particularly well suited for coupling to a pin-shaped coupling element at the upper end of the base.

According to a further embodiment of an air-cushion pipette, the lower part in the connecting pin for coupling to the tubular coupling element has a drive rod which is coupled to the lower end of the lifting rod and is connected to at least one piston which is displaceably arranged in a cylinder, the cylinder being arranged in the lower part and at the lower end End is connected to a pin projecting from the base for releasably holding a pipette tip. In this embodiment, the lower part can be connected to the chassis via the connecting pin to form an overall particularly stable structure. The coupling of the lifting rod to the drive rod can be produced in a particularly simple manner. In a multi-channel pipette, the drive rod may protrude upwards from a traverse which is connected below to the piston rods of the piston of a plurality of piston-cylinder units, the cylinders of which are each connected to a hollow spigot for releasably holding a pipette tip. With a single-channel pipette, the drive rod can also be the piston rod of a piston of a piston-cylinder unit, the cylinder of which is connected to a hollow pin for detachably holding a pipette tip.

According to a further embodiment, a lower part having only one channel or a plurality of channels is coupled to the coupling element via a connecting pin. Each passage is formed by a piston slidably mounted in a cylinder having a spigot at the lower end. A lower part with only one channel forms, together with the pipette, a single-channel pipette (a single pipette tip can be clamped onto each pin). A lower part with a plurality of channels forms a multi-channel pipette, on the spigot of which a plurality of pipette tips can be clamped at the same time.

According to a further embodiment, a plurality of cylinders are held in parallel next to one another in a box-shaped base chassis which is connected at the top to the connecting pin and forms a base housing. In this embodiment, the lower part is also provided with a chassis.

According to a further embodiment of a positive displacement pipette, the first chassis element has setting devices for setting the dosing volume with an adjusting knob protruding upwards from the first chassis element and rotatably mounted on the first chassis element for setting the dosing volume and a counter coupled to the setting devices for setting the set dosing volume. In the case of the direct displacement pipette, the adjustment device and the counter can advantageously be arranged on the first chassis element.

According to a further embodiment of a positive displacement pipette, a second chassis element rotatably supports a rotary sleeve on the jacket and is on the second

Arranged chassis element an actuator for performing a dosing stroke and for ejecting a pipette tip from the pin. Both the dosing and the ejection of a pipette tip can be controlled by means of the actuating element. Details of the rotating sleeve and actuator are in the European patent application EP 19 150 808.4 described. In this regard, reference is made to the European patent application EP 19 150 808.4 , the content of which is hereby incorporated into this application.

According to a further embodiment of a positive displacement pipette, a switching device is connected to the second chassis element, which is coupled to the actuating element in order to displace a piston lifting rod for displacing a syringe piston in different directions with successive displacements of the actuating element by a certain stroke downwards. Details of the switching device are in the European patent application EP 20 181 406.8 described. In this regard, reference is made to the European patent application EP 20 181 406.8 , the content of which is hereby incorporated into this application.

According to a further embodiment, a third chassis element is connected to racks, a lifting rod and a gear coupling the racks to the lifting rod and has guides for a piston ejector and for devices for adjusting an indicator sleeve. The racks are used to move the lifting rod in different directions and interact with the switching device. The arrangement of the switching device in the second chassis element and the fastening and guiding of the toothed racks on the third chassis element means that the coupling between the toothed racks and the switching device can be produced easily during assembly. According to another In this embodiment, the transmission has a multi-stage toothed rack with several parallel rows of teeth, a further toothed rack firmly connected to the lifting rod and two pinions with the same or different diameters connected in a rotationally fixed manner to a common shaft, one of the two pinions having the teeth of a row of teeth of the multi-stage toothed rack and the other of the two pinions meshes with the teeth of the other rack. By means of the multi-stage toothed rack, pipettes with different translations/reductions between the multi-stage toothed rack and the toothed rack firmly connected to the lifting rod can be realized using different gear wheel sets. As a result, pipettes for pipette tips of different nominal volumes can be made available with the same operating distance for dispensing the nominal volume. This assembly makes it easier to implement different pipette variants by using gear sets with different translations/reductions. Details of the racks, the lifting rod and the gearing coupling them are in the European patent application EP 20 181 406.8 described. In this regard, reference is made to the European patent application EP 20 181 406.3 (especially pages 15 to 17 and 27 to 28), the content of which is hereby incorporated into this application.

According to a further embodiment, the fourth chassis element has a protruding pin at the lower end for clamping on a pipette tip with an integrated plunger.

According to a further embodiment, an ejection device for ejecting pipette tips from the spigot is guided on the first chassis element and/or on the fourth chassis element. This enables simple pre-assembly of the ejection device. Details of the ejector and spigot are in the European patent application EP 19 150 847.2 described. In this regard, reference is made to the European patent application EP 19 150 847.2 , the content of which is hereby incorporated into this application.

Both air-cushion pipettes and direct displacement pipettes can be designed according to the following types of embodiment.

According to a further embodiment, the adjacent chassis elements are connected to one another in at least one of the following ways: detachable, non-detachable or conditionally detachable (with the destruction of connecting elements) and/or materially, positively or non-positively. The chassis elements are preferably connected to one another in a detachable manner. This achieves a particularly simple, firm and secure connection between the adjacent chassis elements.

According to a further embodiment, the components and/or assemblies are connected to the chassis elements in at least one of the following ways: detachable, non-detachable or conditionally detachable (destroying connecting elements) and/or positively, non-positively or materially. The components and/or assemblies are preferably detachably connected to the chassis elements. This achieves a particularly simple, firm and secure connection of the components and/or assemblies to the chassis elements.

According to a further embodiment, adjacent chassis elements have positioning elements which hold the adjacent chassis elements in a certain orientation or position relative to one another. According to a further embodiment, the positioning elements comprise at least one pair of latching elements, with adjacent chassis elements each having one latching element of the pair and the adjacent chassis members can be held in a particular orientation or position relative to each other by latching their latching members together. According to a further embodiment, the positioning elements comprise at least one pair of magnetic components, which are formed either by two magnets or by a magnet and a ferromagnetic component, with adjacent chassis elements each having a magnetic component of the pair.

According to a further embodiment, at least one chassis element has at least one protruding position rib or position surface on the outside, with which the chassis element or several assembled chassis elements can be easily placed in a test gauge in order to enable difficult dimensional checks in the shortest possible time and without great effort. This also enables checks by assembly workers in production.

According to a further embodiment, the pipette housing is connected to the chassis in at least one of the following ways and/or the lower part housing is connected to the lower part chassis in at least one of the following ways: detachable, non-detachable or conditionally detachable (destroying connecting elements) and/or form-fitting , non-positively or materially. The pipette housing is preferably detachably connected to the chassis. This achieves a particularly strong, simple and secure connection of the respective chassis to the respective housing, which avoids the introduction of high forces into the various housings.

According to a further embodiment, the pipette housing is connected to a point on the chassis. According to a preferred embodiment, these are several points or an area on a surface located on the inner circumference of the Pipette housing surrounding, closed line. According to another embodiment, the pipette housing is connected to the lower end of the chassis. According to a further embodiment, the pipette housing is only connected to a single chassis element or to two adjacent chassis elements. This prevents forces acting on the chassis from being transmitted via the pipette housing. Furthermore, this has the advantage that thermal expansion of the pipette housing has no effect on components that are relevant to the function of the pipette and are held on the chassis elements.

According to a further embodiment, the pipette housing is designed in such a way that the chassis, composed of all the chassis elements and equipped with the respective components, can be inserted into the pipette housing. This simplifies the assembly of the pipette. Furthermore, this allows tests, calibration and other adjustment work before the complete assembly, before the chassis equipped with the components is installed in the pipette housing.

In the present application, the terms “above” and “below” as well as “vertical” and “horizontal” and terms derived therefrom such as “above” and “below” such as “one above the other” refer to an arrangement of the pipette in which the spigot oriented vertically and located at the downward end of the pipette body.

Fig. 1

ein Oberteil einer Luftpolsterpipette in einem Längsschnitt;

Fig. 2

Chassiselemente mit damit verbundenen Bauteilen derselben Pipette in einem Sprengbild;

Fig. 3

dieselben Chassiselemente in einem Sprengbild;

Fig. 4

Chassiselemente von Fig. 3 zusammengefügt in einer Seitenansicht;

Fig. 5

mit Bauteilen verbundene Chassiselemente von Fig. 2 teilweise zusammengefügt in einer Perspektivansicht schräg von der Seite;

Fig. 6

mit Bauteilen verbundene Chassiselemente von Fig. 2 zusammengefügt in einer Seitenansicht;

Fig. 7

mit Bauteilen verbundene Chassiselemente zusammengefügt mit einem ersten Ausführungsbeispiel einer Abwurfeinrichtung in einer Perspektivansicht schräg von der Seite;

Fig. 8

mit Bauteilen verbundene Chassiselemente zusammengefügt mit einem zweiten Ausführungsbeispiel einer Abwurfeinrichtung in einer Perspektivansicht schräg von der Seite;

Fig. 9

Chassiselement mit Überhubsystem derselben Pipette in einer Explosionsansicht schräg von unten und von der Seite;

Fig. 10

Chassiselement mit Zählwerk derselben Pipette in einer Perspektivansicht von der linken Seite;

Fig. 11

Chassiselement mit Zählwerk derselben Pipette in einer Perspektivansicht von der rechten Seite;

Fig. 12

Unterteil derselben Pipette ohne Unterteilgehäuse in einer teilweise aufgebrochenen Vorderansicht;

Fig. 13

eine Direktverdrängerpipette in einer Vorderansicht;

Fig. 14

dieselbe Direktverdrängerpipette in einer Seitenansicht entlang der Längsachse in einer gegenüber Fig. 13 um 90° gedrehten Ebene,

Fig. 15

mit Bauteilen bestückte und vormontierte Chassiselemente derselben Pipette in einer Perspektivansicht schräg von unten und von der Seite;

Fig. 16

das erste Chassiselement derselben Direktverdrängerpipette in einer Perspektivansicht schräg von unten und von der Seite;

Fig. 17

dasselbe Chassiselement mit Bauteilen bestückt in einer Perspektivansicht schräg von unten und von der Seite;

Fig. 18

zweites Chassiselement von oben derselben Pipette in einer Perspektivansicht von unten und von der Seite;

Fig. 19

dasselbe Chassiselement bestückt mit Bauteilen in einer Perspektivansicht von unten und von der Seite;

Fig. 20

drittes Chassiselement von oben derselben Pipette in einer Perspektivansicht von unten und von der Seite;

Fig. 21

dasselbe Chassiselement bestückt mit Bauteilen in einer Perspektivansicht von unten und von der Seite;

Fig. 22

viertes Chassiselement von oben derselben Pipette in einer Perspektivansicht von unten und von der Seite;

Fig. 23

dasselbe Chassiselement bestückt mit Bauteilen in einer Perspektivansicht von unten und von der Seite;

Fig. 24

Kopplung der Baugruppe von Fig. 22 mit dem Zählwerk von Fig. 16 in einer Perspektivansicht schräg von unten und von der Seite.

The invention is described in more detail below with reference to the accompanying drawings of exemplary embodiments. In the drawings show:

1

an upper part of an air cushion pipette in a longitudinal section;

2

chassis elements with associated components of the same pipette in an exploded view;

3

the same chassis elements in an exploded view;

4

Chassis elements from 3 assembled in a side view;

figure 5

with components connected chassis elements from 2 partially assembled in a perspective view obliquely from the side;

6

with components connected chassis elements from 2 assembled in a side view;

7

chassis elements connected to components joined together with a first exemplary embodiment of a release device in a perspective view obliquely from the side;

8

chassis elements connected to components joined together with a second exemplary embodiment of a release device in a perspective view obliquely from the side;

9

Chassis element with overstroke system of the same pipette in an exploded view obliquely from below and from the side;

10

Chassis element with counter of the same pipette in a perspective view from the left;

11

Chassis element with counter of the same pipette in a perspective view from the right side;

12

Lower part of the same pipette without lower part housing in a partially broken front view;

13

a positive displacement pipette in a front view;

14

the same positive displacement pipette in a side view along the longitudinal axis in an opposite 13 plane rotated by 90°,

15

chassis elements of the same pipette equipped with components and preassembled in a perspective view obliquely from below and from the side;

16

the first chassis element of the same positive displacement pipette in a perspective view obliquely from below and from the side;

17

the same chassis element fitted with components in a perspective view obliquely from below and from the side;

18

second chassis element from above of the same pipette in a perspective view from below and from the side;

19

the same chassis element equipped with components in a perspective view from below and from the side;

20

third chassis element from above of the same pipette in a perspective view from below and from the side;

21

the same chassis element equipped with components in a perspective view from below and from the side;

22

fourth chassis element from above of the same pipette in a perspective view from below and from the side;

23

the same chassis element equipped with components in a perspective view from below and from the side;

24

Coupling the assembly from 22 with the counter from 16 in a perspective view obliquely from below and from the side.

According to Figures 1 to 11 the air-cushion pipette 1.1 has an upper part 2, which has a chassis 3, components 4 (e.g. an indicator ring) and assemblies 5 (e.g. a counter, cf. 2 ) and a tubular pipette housing 6 includes.

The chassis 3 comprises four tubular chassis elements 7.1, 7.2, 7.3, 7.4 which are detachably connected to one another. The chassis 3 has a first chassis element 7.1 at the top, which has an upper section 9.1, delimited by upper hollow cylinder segments 8.1, 8.2 of larger diameter, and at the bottom a lower section 9.2, delimited by lower hollow cylinder segments 8.3, 8.4, of smaller diameter (cf. 3 ). In between, an upwardly projecting dome 12 is arranged on a plate 10 with a central through hole 11 . Above are the upper ones Hollow cylinder segments 8.1, 8.2 are connected to one another on one side by a web 13 in the form of a circular arc, which has a pocket 14 which is open at the bottom.

A substantially ring-shaped, second chassis element 7.2 is arranged underneath, which can be pushed from below onto the lower section 9.2 of the first chassis element 7.1. On the inner sides of the lower section 9.2 of the first chassis element 7.1, grooves 15.1, 15.2 of a bayonet connection 16 are formed, which are directed in the axial and circumferential direction. The second chassis element 7.2 has brackets 17.1, 17.2 protruding outwards on the casing (cf. 2 , 10, 11 ).

A third chassis element 7.3 is arranged under the second chassis element 7.2, which has a tubular section 18 at the top with projections 19 of the bayonet connection 16 that are complementary to the grooves 15.1, 15.2 (cf. 3 ). At the bottom, the third chassis element 7.2 is provided with three legs 20.1, 20.2, 20.3 projecting downwards with hooks 21.1, 21.2, 21.3 at the ends. The tubular section 18 of the third chassis element 7.3 has an external thread 22 on the outer circumference and a bearing pin 23 protruding outwards above it.

The fourth chassis element 7.4, which is ring-shaped, is arranged underneath. The fourth chassis element 7.4 has a circumferential web 24 at the top and underneath it has several openings 25.1, 25.2, 25.3 in the jacket.

For connection to the first chassis element 7.1, the second chassis element 7.2 is pushed onto the lower section 9.2 of the first chassis element 7.1. Here, a minimum locking between the two chassis elements 7.1, 7.2 is effective.

The third chassis element 7.3 is connected to the first and second chassis element 7.1, 7.2 via the bayonet connection 16.

The fourth chassis element 7.4 is connected by sliding it onto the legs 20.1, 20.2, 20.3 of the third chassis element 7.3 until the hooks 21.1, 21.2, 21.3 engage in the openings 25.1, 25.2, 25.3 of the fourth chassis element 7.4.

Before the chassis elements 7.1, 7.2, 7.3, 7.4 are connected to one another, they can be equipped with components 4 and assemblies 5.

A hollow threaded spindle 27 is screwed into an internal thread 26 in the dome 12 of the first chassis element 7.1 from below. With the upper end of the threaded spindle 27, a driver 28 is rotatably connected with outwardly projecting driver wings 29.1, 29.2. A driver sleeve 30 is pushed onto the dome 12 from above, which sleeve has axial grooves 31.1, 31.2 on the inner circumference, which accommodate the driver wings 29.1, 29.2. The carrier sleeve 30 has circumferential teeth 32 on the outside at the lower end (cf. 1 ).

A lower adjustment sleeve 33 is slid onto the driver sleeve 30 from above, which has two circumferential teeth 34.1, 34.2 of different diameters at the bottom on the circumference.

A bearing shell 35 is inserted between the lower adjustment sleeve 33 and the upper section 9.1 of the first chassis element 7.1. An upper adjustment sleeve 36 is pressed onto the lower adjustment sleeve 33 from above or is firmly connected to it in some other way, and this upper adjustment sleeve protrudes from the first chassis element 7.1 with an adjustment wheel.

A lifting rod 37 is inserted from below into the threaded spindle 27 and can be pushed with a bead-like collar 39 against the underside of the threaded spindle 27 , which forms an upper stop 40 .

On the brackets 17.1, 17.2 of the second chassis element 7.2, a counter 41, a transmitter 42 and a drive gear 43 can be pushed from above. The transmitter 42 is a shaft 44 on which several pinions 45.1, 45.2 are arranged. The drive gear wheel 43 comprises two front edges 46.1, 46.2 with different diameters on a common shaft 47 (cf. 2 , 5-8 , 10, 11 ).

A bearing plate 48 with a rib 49 projecting upwards in the shape of a circular arc is placed on top of the counter 41, the transmitter 42 and the drive gear wheel 43. In addition, devices 50 for a factory calibration are mounted on the second chassis element 7.2.

When the second chassis element 7.2 is slid onto the first chassis element 7.1, the arcuate rib 51 engages in the pocket 14. Furthermore, the pinions 45.1 and 45.2 on the transmitter 42 engage with the teeth 34.1 and 32 when the adjusting sleeves 33, 36 are arranged in their highest position. If they are shifted to their lowest position, the pinion 45.2 engages with the teeth 34.2 and 32 and the pinion 45.1 is disengaged. As a result, different translations between the adjusting sleeves 33, 36 and the driver sleeve 30 are realized. ,

A lower stop 51 of an overlift system 52 is inserted from below into the third chassis element 7.3. The lower stop 51 has outwardly protruding projections 53 which are in grooves 54 on the inner circumference of the third chassis element 7.3 be used. Furthermore, an overtravel spring 55 is inserted into the lower stop 51 from below. Finally, a plate 56 is pressed from below against the overtravel spring 55, which plate has latching lugs 57 projecting from the periphery and latching into latching holes 58 on the inner periphery of the third chassis element 7.3. Plate 56 is a bearing for overtravel spring 52 (cf. 1 , 5, 6 ).

The lower stop 51 and the plate 56 each have a central through hole 59, 60 for inserting the lifting rod 37.

On the external thread 22 of the third chassis element 7.3, an indicator ring 61 is screwed with circumferential teeth 62 at the top. The upper edge of the indicator ring 61 is inclined, its inclination corresponding to the pitch of the external thread 22 on the third chassis element 7.3. A drive element 63 of crown teeth 64 is pushed onto the bearing journal 23 and meshes with the teeth 62 on the upper edge of the indicator ring 61 . The drive element 63 has a hexagon socket 65 for attaching a tool for customer calibration.

Before connecting the third chassis element 7.3 to the first and the second chassis element 7.1, 7.2, a bayonet spring 66 is inserted from above into the third chassis element 7.3, which is supported at the bottom on an inwardly projecting shoulder 67 of the third chassis element 7.3 and at the top against a inside protruding projection 68 of the second chassis element 7.2 presses. The bayonet connection is secured in a connection position by the bayonet spring 66 .

The fourth chassis element 7.4 is connected to the third chassis element by snapping it onto the hooks on the legs of the latter.

Finally, 3 dropping devices 69.1, 69.2 are placed on the preassembled chassis from the outside, of which two variants in the Figures 7 and 8 are shown.

The assembled chassis 3 with the preassembled components 4 and assemblies 5 is pushed into the pipette housing 6 from above. The pipette housing 6 has three protruding projections 70.1, 70.2, 70.3 in the lower area on the inner circumference. The chassis 3 is pushed into the pipette housing 6 until the underside of the circumferential web of the fourth chassis element 7.4 is supported on the top of the projections 70 and the hooks 21.1, 21.2, 21.3 of the third chassis element 7.3 snap under the projections of the pipette housing. Finally, for securing from below, a bracing spring 71 is inserted into the fourth chassis element 7.4, which latches at the upper end with projections in the third chassis element and supports the legs 20.1, 20.2, 20.3 on the inside. The bracing spring 71 is also used to establish a connection with a lower part of the pipette.

For the connection to a lower part of the pipette 1.1, the fourth chassis element 7.4 (lower part coupling frame) has an inwardly projecting, circumferential shoulder 72 on the lower edge.

According to 12 For example, the pipette base 73 has a box-shaped base chassis 74 formed of front and rear housing shells 74.1, 74.2 joined together in a vertical plane. The base 73 has a tubular connecting pin 75 projecting upward from the upper edge of the base chassis 74 . The connecting pin 75 is integrally connected to one of the two housing shells 74.1, 74.2.

In the lower part 73 eight parallel piston-cylinder devices 76 are arranged in a row. Each piston-cylinder device 76 has a cylinder 76.1, into which a piston 76.2 dips, which is connected via a piston rod 76.3 to a piston plate 76.4.

At the bottom, each cylinder 76.1 is connected in one piece to a pin 77 protruding downwards for attaching a pipette tip to a dosing component 78. Each pin 77 has a through hole which is connected at the top to the interior of the cylinder 76.1, in which the piston 76.2 can be displaced, and opens out at the bottom in an opening in the lower end of the pin 77.

Each dosing component 78 has a peripheral projection 79 between the pin 77 and the cylinder 76.1.

The peripheral projections 79 of the dosing components 78 are supported on the upper edges of through holes 79 in a horizontal lower wall 80 of the lower part 73 . The cylinders 76.1 are passed through further through holes 81 of a horizontal support plate 82 of the lower part 73 further up.

A spring element 83 designed as a helical spring is guided on each cylinder 76.1, which is supported on the circumferential projection 79 at the bottom and on the underside of the support plate 82 at the top.

A drive rod 84 is inserted into the connecting pin 75 and is connected at the bottom to a traverse 85 which has receptacles 85.1 into which the piston plates 76.4 are inserted.

Furthermore, the lower part 73 comprises a two-part ejector 86, which has a vertical, plate-shaped ejector part 86.1, 86.2 at the lower edge, a two-part horizontal stop 86.3, 86.4 with through openings 86.5, 86.6 open towards the front edge, and a stop protruding upwards from the upper edge of the plate-shaped ejector part 86.1 Actuating element 86.7 has.

Details of the base 73 and the two-part ejector 86 and their coupling to a pipette are shown in FIG EP 2 735 369 A1 removed, in particular sections 55 and 62 to 83 and the Figures 1 to 10 . An alternative embodiment, which can also be used within the scope of the present invention, is particularly set out in paragraphs 91 to 98 and the Figures 11 to 16 of the aforementioned patent. In this regard, reference is made to the EP 2 735 369 A1 , the content of which is hereby incorporated into this application.

By inserting the connecting pin 75 into the fourth chassis element 7.4, the lower part 73 can be connected to the upper part 2 of the pipette 1.1.

According to Figures 13 to 24 a direct displacement pipette 1.2 has a chassis 87 with components 88 and assemblies 89 connected thereto and a pipette housing 90 enclosing the chassis 87 and the components 88 and assemblies 89.

The chassis 87 comprises four tubular chassis elements 91.1, 91.2, 91.3, 91.4.

At the top, the chassis 87 has a first chassis element 91.1, which has a circumferential groove 92 on the outer circumference and, next to it, a circumferential, outwardly projecting collar 93 for connection to a second chassis element 91.1. The second chassis element 91.2 has an inwardly projecting flange 94 at the upper end for connection to the groove 92 and collar 93 of the first chassis element 91.1. The first chassis element 91.1 and the second chassis element 91.2 can be releasably connected to one another by screwing the flange 94 into the groove 92.

The second chassis member 91.2 has a slot 94 at the lower end for pivotal connection with the third chassis member 91.3 which has outwardly projecting wings 95 for mating with the slot 94 on the shell.

The third chassis element 91.3 has slots 96 at the lower end on the circumference and the fourth chassis element 91.4 has projections 97 complementary thereto for a rotary connection of the third chassis element 91.3 and fourth chassis element 91.4.

The chassis elements 91.1 to 91.4 can be fitted with components 88 and assemblies 89 separately from one another. The first chassis element 91.1 can be equipped with a device for adjusting the pipetting volume 98. This includes a spindle nut 99 which can be connected to a flange and a wrench flat at the lower end of the first chassis element 91.1. A guide tube 100 projects downwards from the spindle nut 99 . Screwed into the spindle nut 99 is a threaded spindle which is provided at the top with an adjusting knob 101 which protrudes from the upper end of the first chassis element 91.1. An upper housing cover 102 is fixed on the upper end of the first chassis member.

A counter 103 is mounted on the open side of the first chassis element and is coupled to the threaded spindle via a gear.

A transmission mechanism 104 and a rotary sleeve 105 are inserted into the second chassis element 91.2. Furthermore, the transmission mechanism with a Actuator 106 connected. The second chassis element 31.2 comprises a device for switching between an upward movement and a downward movement of a piston lifting rod.

In the third chassis element 91.3, two toothed racks 108.1, 108.2, a piston lifting rod 109 with teeth at the upper end and a toothed gear 110 are mounted.

Finally, a pin 111 and a locking sleeve 112 and a piston ejection rod 113 are mounted in the fourth chassis element 91.4.

The preassembled assemblies are connected to one another by connecting the chassis elements 91.1 to 91.4 and the chassis 87 is installed in the pipette housing 90.

Reference List

1.1

air cushion pipette

2

top

3

chassis

4

component

5

module

6

pipette housing

7.1, 7.2, 7.3, 7.4

chassis element

8.1, 8.2

upper hollow cylinder segment

8.3, 8.4

lower hollow cylinder segment

9.1

upper section

9.2

lower section

10

plate

11

through hole

12

Dom

13

web

14

Bag

15.1, 15.2

grooves

16

bayonet connection

17.1, 17.2

consoles

18

tubular section

19.1, 19.2

protrusions

20.1, 20.2, 20.3

Legs

21.1, 21.2, 21.3

Hook

22

external thread

23

bearing journal

24

web

25.1, 25.2, 25.3

breakthrough

26

inner thread

27

lead screw

28

driver

29.1, 29.2

driving wings

30

driving sleeve

31.1, 31.2

axial grooves

32

gearing

33

lower adjustment sleeve

34.1, 34.2

gearing

35

bearing shell

36

upper adjustment sleeve

37

lifting rod

39

Federation

40

upper stop

41

counter

42

transmitter

43

drive gear

44

Wave

45.1, 45.2

pinion

46.1, 46.2

spur gear

47

Wave

48

bearing plate

49

rib

50

Setup for a factory calibration

51

lower stop

52

overlift system

53

head Start

54

groove

55

overtravel spring

56

Plate

57.1, 57.2, 57.3

detents

58.1, 58.2, 58.3

rest holes

59, 60

through holes

61

indicator ring

62

gearing

63

drive element

64

Crown gearing

65

Allen key

66

bayonet spring

67

Unit volume

68

head Start

69.1, 69.2

discharge device

70

protrusions

71

bracing spring

72

Unit volume

73

lower part

74

bottom chassis

74.1, 74.2

housing shell

75

connecting pin

76

Piston-cylinder device

76.1

cylinder

76.2

Pistons

76.3

piston rod

76.4

piston plate

77

Zapfen78 dosing component

79

circumferential projection

80

lower wall

81

through hole

82

support plate

83

spring element

84

drive rod

85

traverse

85.1

Recording

86

ejector

86.1, 86.2

plate-shaped ejector part

86.3, 86.4

horizontal stop

86.5, 86.6

passage opening

86.7

actuator

87

chassis

88

component

89

module

90

pipette housing

91.1, 91.2, 91.3, 91.4

tubular chassis member

92

groove

93

collar

94

flange

95

wing

96

slot

97

head Start

98

Device for setting the pipetting volume

99

spindle nut

100

guide tube

101

adjustment knob

102

top case cover

103

counter

104

transmission mechanics

105

rotating sleeve

106

actuator

108.1, 108.2

rack

109

piston lifting rod

110

gear transmission

111

cones

112

locking sleeve

113

piston ejector rod

Claims (26)

A pipette for use with a pipette tip comprising • an elongated chassis (3, 87), • components (4, 88) connected to the chassis (3, 87) of a device for detachably holding (80, 111) at least one pipette tip and a drive device (97, 105) for displacing a displacement element for sucking in liquid samples into the pipette tip and ejecting the samples from the pipette tip, • a tubular pipette housing (6, 90), which surrounds the chassis (3, 87), the longitudinal direction of the chassis being aligned in the longitudinal direction of the pipette housing, and which is connected to the chassis,
characterized in that • the chassis (3, 87) has a plurality of tubular chassis elements (7.1 to 7.4; 91.1 to 91.4) which are arranged one behind the other and connected to one another, and • that the components (4, 88) of the device for detachably holding (80, 111) at least one pipette tip and the drive device (37, 105) are connected to different chassis elements (7.1 to 7.4; 91.1 to 91.4). Pipette according to Claim 1, in which all of the chassis elements (7.1 to 7.4; 91.1 to 91.4) are tubular. Pipette according to Claim 1 or 2, in which at least one component of a drive device (37, 105) for displacing a displacement element connected to at least one chassis element and/or in which at least one component of a display device (41, 103) for displaying a set pipetting volume is connected to at least one chassis element and/or in which at least one component of an ejection device (113) for ejecting at least one pipette tip are connected to at least one chassis element and/or in which the components of a device for detachably holding (90, 111) at least one pipette tip are connected to at least one chassis element and/or in which at least one component of a device for detachably holding (21.1 to 21.3) the Chassis elements are connected in the pipette housing with at least one chassis element. Pipette according to one of Claims 1 to 3, which comprises a first assembly comprising a chassis element and at least one component of the drive device (37, 105) and/or a second assembly comprising a chassis element and at least one component of the display device (41, 103) and/or a third assembly comprising a chassis element and at least one component of the ejection device (69,.1, 69.2) and/or a fourth assembly comprising a chassis element and at least one component of a device for detachably holding (80, 111) at least one pipette tip and/or a fifth subassembly has a chassis element and at least one component of the device for detachably holding (21.1 to 21.3) the chassis elements in the pipette housing. Pipette according to one of Claims 1 to 4, in which the drive device (37, 105) comprises a first subassembly made up of several components which is connected to at least one chassis element and/or the display device (41, 103) comprises a second subassembly made up of several components which is connected to at least one chassis element and/or the dropping device (69.1, 69.2; 113) a third sub-assembly made up of several components, which is connected to at least one chassis element and/or the device for releasably holding (80, 111) at least one pipette tip a fourth sub-assembly made up of several components which is connected to at least one chassis element and/or the device for releasably holding (21.1 to 21.3) the chassis elements in the pipette housing at least one fifth sub-assembly made up of several components, which is connected to at least one chassis element. Pipette according to one of Claims 1 to 5, in which components of the drive device (37, 105) are connected to a first chassis element and/or components of the display device (41, 103) are connected to a second chassis element and/or components of the drive device (37 , 105) are connected to a third chassis element and/or at least one component of the device for detachably holding (80, 111) at least one pipette tip is connected to a fourth chassis element or designed as such and/or at least one component of a device for detachable holding ( 21.1 to 21.3) of the chassis elements in the pipette housing is connected to the fourth chassis element or is designed as such. Pipette according to one of Claims 1 to 5, in which components of the drive device (37, 105) and/or components of a display device (41, 103) are connected to a first chassis element and/or components of the drive device (37, 105) and/or Components of the dropping device (69.1, 69.2; 113) are connected to a second chassis element and/or components of the drive device (37, 105) are connected to a third chassis element and/or components of the dropping device (69.1, 69.2; 113) are connected to a fourth chassis element are connected. Pipette according to Claim 6 or 7, in which the first chassis element (7.1, 91.1) is above the second chassis element (7.2, 91.2), the second chassis element (7.2, 91.2) is above the third chassis element (7.3, 91.3) and the third chassis element (7.3 , 91.3) above the fourth chassis element (7.4, 91.4). Pipette according to one of Claims 1 to 8, in which at least one component and/or at least one subassembly is arranged at least partially inside and/or laterally on a tubular chassis element (7.1 to 7.4; 91.1 to 91.4) connected thereto. Pipette according to one of Claims 6 or 8 to 9, in which the drive device (37) has a threaded spindle (27), which engages in an internal thread of the first chassis element (7.1) and can be adjusted in the longitudinal direction of the first chassis element (7.1), a rotatable im first chassis element (7.1) and non-rotatably connected to the threaded spindle (27) so that it can be displaced relative to one another in the longitudinal direction. 27) has a lifting rod (37) running through it, which can be displaced with at least one projection on the circumference until it contacts a first stop on the underside of the threaded spindle, forms the drive element below the projection and protrudes from the first chassis element with an operating button at the upper end. Pipette according to one of Claims 6 or 8 to 10, in which the second chassis element (7.2) is held at the lower end of the first chassis element (7.1) and a counter (41) on holding devices on the jacket of the second chassis element (7.2) and the first chassis element (7.1) is held. Pipette according to one of Claims 6 or 8 to 11, in which the third chassis element (7.3) is connected to the lower end of the first chassis element (7.1) and/or the second chassis element (7.2) and within the third chassis element (7.3) an overstroke system (52) is arranged with a passage through which the lifting rod (37) extends downwards, with the lifting rod counteracting a second stop on the upper side of the overlift system (52) after the projection (39) has struck during a downward displacement the effect of an overtravel spring (55) can be displaced further downwards. Pipette according to one of Claims 6 or 8 to 12, in which the fourth chassis element (7.4) is a tubular coupling element and a base (73) with a connecting pin (75) is inserted into the coupling element (74), the base (73) has at least one displacement element (76.2) in a displacement chamber (76.1) and a hollow pin (77) connected to the displacement chamber for detachably holding a pipette tip. Pipette according to one of Claims 6 or 8 to 13, in which the lower part (73) in the connecting pin (75) has a drive rod (84) coupled to the lower end of the lifting rod (37) for coupling to the tubular coupling element (74). is connected to at least one piston (76.2) which is displaceably arranged in a cylinder (76.1), the cylinder (76.1) being arranged in the lower part (73) and having a pin (77) protruding from the lower part (73) at the lower end for detachably holding a pipette tip is connected. Pipette according to Claim 14, in which a plurality of cylinders (76.1) are held in parallel next to one another in a box-shaped base chassis (74) which is connected at the top to the connecting pin (75) and forms a base housing. Pipette according to Claim 7 or 8, in which the first chassis element (7.1) has setting devices (33, 36) for setting the metering volume with an adjusting knob for setting the metering volume which protrudes upwards from the first chassis element (7.1) and is rotatably mounted on the first chassis element and with a has a counter (41) coupled to the setting devices (33, 36) for setting the set dosing volume. Pipette according to one of Claims 7, 8 or 16, in which a second chassis element (91.2) rotatably mounts a rotary sleeve (105) on the casing and an actuating element (106) for executing a dosing stroke and for ejecting a pipette tip on the second chassis element (91.2). by the pin (111). Pipette according to one of Claims 7, 8, 16 or 17, in which switching means (105) are connected to the second chassis element (91.2) and are coupled to the actuating element (106) in order to switch over upon successive displacements of the actuating element (106). to move a certain stroke down a lift rod for displacing a tip piston in different directions. Pipette according to one of Claims 7, 8 or 16 to 18, in which a third chassis element (91.3) with racks (108.1, 108.2), a lifting rod (109) and a gear coupling the racks and the piston lifting rod (110) and guides for a piston ejector (113) and a device for adjusting a display sleeve. Pipette according to one of Claims 7, 8 or 16 to 19, in which an ejection device (113) for ejecting pipette tips from the spigot (111) is guided on the first chassis element (91.1) and/or on the fourth chassis element (91.4). Pipette according to one of Claims 1 to 20, in which adjacent chassis elements (7.1 to 7.4; 91.1 to 91.4) are connected to one another in at least one of the following ways: detachably, non-detachably or conditionally detachably and/or materially, positively or non-positively. Pipette according to one of Claims 1 to 21, in which the components and/or assemblies are connected to the chassis elements (7.1 to 7.4; 91.1 to 91.4) in at least one of the following ways: detachably, non-detachably or conditionally detachably and/or positively, non-positively or materially. Pipette according to one of Claims 1 to 22, in which the pipette housing (6, 90) is connected to the chassis (3, 87) in at least one of the following ways and/or the base housing (86) is connected to the chassis (3, 87) in at least one of the following ways Lower part chassis (74) is connected: releasably, non-releasably or conditionally releasably and/or positively, non-positively or materially. Pipette according to one of Claims 1 to 23, in which adjacent chassis elements (7.1 to 7.4; 91.1 to 91.4) have positioning elements which hold the adjacent chassis elements in a specific alignment or position relative to one another, the positioning elements preferably comprising at least one pair of magnetic components, the are formed either by two magnets or by a magnet and a ferromagnetic component. Pipette according to one of Claims 1 to 24, in which at least one chassis element (7.1 to 7.4; 91.1 to 91.4) has a positioning rib or surface with which the chassis element or several assembled chassis elements can be placed in a test jig. A pipette according to any one of claims 1 to 25, wherein the pipette housing (6, 90) is connected to the lower end of the chassis (3, 87).

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