EP2735369A1 - Multichannel pipette - Google Patents

Abstract

The pipette has spring elements which are designed by clamping up pipette tips (89) onto the spigots (26). The spigots are dislocated towards contact element in stop position, such that pipette tips hit contact element. Ejection equipment is provided with mounting section for mounting an ejector (43) on base (5), so as to be slidable in longitudinal direction of spigots. A drive device is connected to ejector. The ejector is provided with contact elements on different ejector portions (44,63) to squeeze off pipette tips from spigots.

Description

The invention relates to a multi-channel pipette with a plurality of pins ("lugs") for clamping pipette tips and a discharge device for releasing pipette tips from the pins.

Pipettes are used in particular in medical, biological, biochemical, chemical and other laboratories for dosing liquids. These are picked up in pipette tips through a tip opening and dispensed. In air cushion pipettes, a displacement device for air is integrated into the pipette and communicatively connected to the pipette tip through a connection hole of the pin. By means of the displacement device, an air cushion is displaced, so that liquid is sucked into the pipette tip and ejected therefrom. The displacement device is usually a cylinder with a piston displaceable therein.

The pipette tips are releasably connected to the spigot so that they can be exchanged for a fresh pipette tip after use. As a result, contaminations are avoided at subsequent dosages. Single-use pipette tips are available inexpensively from plastic.

The pin for holding pipette tips is also referred to as a "working cone" and is often a conical or cylindrical projection with respect to a housing or other body. The pipette tip can be clamped onto the journal with a matching sealing seat at an attachment opening. This can be done without touching the pipette tip by pressing the pipette with the pin into the mounting opening of the pipette tip provided in a holder.

To avoid contact of the user with the contaminated pipette tips, pipettes have a discharge device with a drive device and an ejector. By actuating the drive device, the ejector is displaced so that it releases the pipette tip from the pin without the user having to touch it. In many cases, the drive device has a mechanism that must be actuated by means of a button to release the pipette tip from the pin. Alternatively, the drive means has an electric motor that can be controlled by operating a knob to disengage the pipette tip from the pin. Especially with manual pipettes, i. for pipettes that can be held and operated by the user when using with one or both hands. In the embodiment as manually driven pipettes, these pipettes have a mechanism for the displacement device which can be driven manually by means of a dosing button and, in the embodiment as electronic pipettes, an electric drive motor for the displacement device that can be controlled by means of an electrical dosing button.

The release of a pipette tip from the pin can require considerable effort in the case of a pipette tip firmly clamped on a pin.

Multi-channel pipettes serve to simultaneously receive liquid from one or more vessels or to dispense into one or more vessels. Multichannel pipettes are widely used for the processing of microtiter plates which have a multiplicity of vessels in a matrix-like arrangement. For this purpose, multi-channel pipettes have a plurality of parallel in a row next to each other at the same height arranged pin whose through holes each with a separate displacement means or a common Displacement device are connected. In adaptation to a commonly used format of 96 (= 8x12) microtiter plates, multichannel pipettes often have eight or twelve pegs. The multiple displacement means and the common displacement means are connected in a manually driven multi-channel pipette with a mechanical drive means and in an electronic multi-channel pipette with an electric drive motor. Furthermore, multichannel pipettes with an ejector are known, which presses off all the pipette tips from the pins with a rectilinear stop element and for this purpose has a drive mechanism which can be driven manually. The force required to force several pipette tips off the spigots of a multichannel pipette is significantly greater than in the case of a single-channel pipette in which only one pipette tip is pressed off by one spigot.

Multi-channel pipettes are already known in which, in order to reduce the force required to eject the pipette tips, an ejector is not formed with a rectilinear stop element but with a stepped stop element. With these multichannel pipettes, the steps hit the pipette tips one at a time, requiring only the force to eject the pipette tips that are in contact with stages of the ejector. The maximum force to be applied for the ejection of the pipette tips is thereby reduced. A graduated stop element leads to different Aufsteckhöhen the pipette tips on pins of a multi-channel pipette. At different Aufsteckhöhe reach not all pipette tips, which are simultaneously attached to the pins of the multichannel pipette, the bottoms of a microtiter plate.

The DE 10 2004 003 433 B4 describes a multi-channel pipette, which reduces the force required for the operation of the ejection device in that it limits the force for clamping the pipette tips on the pins. For this purpose, the multichannel pipette has a base body, a plurality of protruding from the body, axially movable on the base body mounted pin for placing pipette tips, displacement means which are fixedly connected to the pins, and springs, via which the displacement means are supported on the base body. The sprung pin is associated with a stop over which the pins protrude axially when they are not loaded to the spring. A discharge device for releasing the pipette tips from the pins has an ejector associated with the pins, wherein the pins and the ejectors are movable relative to each other. The stop can also be the ejector. In addition, the multi-channel pipette has a drive device operatively connected to the ejector and / or the pin for relatively moving the ejector and the pin.

When inserting the multi-channel pipette with the pins in the mounting openings of several pipette tips the Aufklemmkraft is introduced into the springs. If the clamping force exceeds a certain value, the springs are elastically deformed until the pipette tips clamped on the pins strike against the stop. As soon as the pipette tips touch the stop, they can not be pushed further onto the pins. As a result, the clamping force of the pipette tips is limited. The springs are designed and optionally biased, that the pipette tips exactly when they sit with the desired Aufklemmkraft on the pin, abut the stop. The clamping force is determined so that the pipette tips sit or seal securely on the pin.

The known pipette avoids high Aufklemmkräfte that complicate the ejection of the pipette tips. However, the clamping force required for a secure fit and the sealing of the pipette tips on the pins must be ensured during the operation Throwing off be overcome. The total applied Abwerfkraft is high because multiple pipette tips must be pressed simultaneously.

Based on this, the present invention seeks to provide a multi-channel pipette, which further reduces the force required for the operation of the discharge device.

The object is achieved by a multi-channel pipette with the features of claim 1. Advantageous embodiments of the multi-channel pipette are specified in subclaims.

• ● einen Grundkörper,
• ● mehrere in einer Reihe parallel nebeneinander angeordnete, vom Grundkörper vorstehende, in ihrer Längsrichtung beweglich am Grundkörper gelagerte Zapfen zum Aufklemmen von Pipettenspitzen,
• ● mindestens eine Verdrängungseinrichtung mit einer Verdrängungskammer und einem darin verlagerbaren Verdrängungsorgan, wobei die Verdrängungskammer mit Verbindungslöchern in den Zapfen verbunden ist, um Luft durch Öffnungen der Verbindungslöcher in unteren Enden der Zapfen auszustoßen oder einzusaugen,
• ● eine mit dem Verdrängungsorgan verbundene erste Antriebseinrichtung, die ausgebildet ist, das Verdrängungsorgan in der Verdrängungskammer zu verlagern,
• ● an den Zapfen und am Grundkörper angreifende erste Federelemente, wobei die Zapfen entgegen der Federwirkung der ersten Federelemente aus einer Ausgangsstellung in ihrer Längsrichtung nach oben verlagerbar sind,
• ● mindestens ein Anschlagelement, das eine Anschlagstellung hat, in der die Zapfen von dem Anschlagelement nach unten vorstehen,
• ● wobei die ersten Federelemente so ausgelegt sind, dass die Zapfen von definierten Aufklemmkräften, die durch Aufklemmen von Pipettenspitzen auf die Zapfen aufbringbar sind, solchermaßen zu dem Anschlagelement in der Anschlagstellung hin verlagerbar sind, dass die Pipettenspitzen auf das Anschlagelement auftreffen, und
• ● eine Abwurfeinrichtung zum Lösen von Pipettenspitzen von den Zapfen, umfassend einen Abwerfer, der Kontaktelemente aufweist, Mittel zum verschieblichen Lagern des Abwerfers am Grundkörper in Längsrichtung der Zapfen und eine mit dem Abwerfer verbundene zweite Antriebseinrichtung, die ausgebildet ist, den Abwerfer aus einer Ausgangsstellung, in der Pipettenspitzen bis zum Auftreffen auf das Anschlagelement in der Anschlagstellung auf die Zapfen aufklemmbar sind, in Längsrichtung der Zapfen nach unten zu verlagern, um mit den Kontaktelementen Pipettenspitzen von den Zapfen abzudrücken,
• ● wobei der Abwerfer die Kontaktelemente an verschiedenen Abwerferteilen aufweist und so ausgebildet ist, dass beim Verlagern des Abwerfers nach unten zumindest nach dem Auftreffen mindestens eines ersten Kontaktelements auf Pipettenspitzen mindestens ein zweites Kontaktelement dem ersten Kontaktelement nacheilt, um zunächst mit dem ersten Kontaktelement eine oder mehrere Pipettenspitzen und danach mit dem zweiten Kontaktelement eine oder mehrere Pipettenspitzen von den Zapfen abzudrücken.

The multichannel pipette according to the invention has

• ● a basic body,
• ● a plurality of pins arranged in parallel next to one another and projecting from the main body, mounted on the main body in the longitudinal direction so as to be movable, for clamping pipette tips;
• ● at least one displacement device having a displacement chamber and a displaceable displaceable therein, wherein the displacement chamber is connected to connecting holes in the pin to expel or suck in air through openings of the communication holes in lower ends of the pins,
• ● a first drive device, which is connected to the displacement element and which is designed to displace the displacement element in the displacement chamber,
• ● acting on the pin and on the base body first spring elements, wherein the pins are displaceable against the spring action of the first spring elements from a starting position in its longitudinal direction upwards,
• At least one stop element having a stop position in which the pins project downwardly from the stop element,
• ● wherein the first spring elements are designed so that the pins of defined Aufklemmkräften that can be applied by clamping pipette tips on the pins are so displaced towards the stop element in the stop position that the pipette tips impinge on the stop element, and
• A discharge device for detaching pipette tips from the pins, comprising an ejector which has contact elements, means for displaceably supporting the ejector on the main body in the longitudinal direction of the pins and a second drive device connected to the ejector, which is designed to move the ejector from a starting position, in the pipette tips can be clamped on the pins until they strike the stop element in the stop position, to be displaced downwards in the longitudinal direction of the pins in order to press pipette tips away from the pins with the contact elements,
• Wherein the ejector has the contact elements at different Abwerferteilen and is designed so that when moving the ejector down at least after the impact of at least one first contact element on pipette tips at least a second contact element lags the first contact element to first with the first contact element one or more Pipette tips and then with the second contact element depress one or more pipette tips of the pins.

In the case of the multichannel pipette according to the invention, the clamping forces for clamping pipette tips are limited by the fact that the pins engage with the clamping forces acting on them during the clamping of pipette tips be shifted towards at least one stop element until the pipette tips impinge on the stop element, which is located in a defined stop position. If the multi-channel pipette has several stop elements, they are in the stop position at the same height. The first spring elements are designed so that the pipette tips strike the stop element when defined clamping forces are achieved. These are preferably chosen so that the pipette tips sit securely and sealingly on the pin. High Aufklemmkräfte that would have to be overcome when dropping the pipette tips are avoided. In this multi-channel pipette, the use of an ejector with arranged in stages stop elements would not make sense, because this geometry favors different Aufsteckhöhen the pipette tips, which are associated with different Aufklemmkräften. The multichannel pipette according to the invention nevertheless makes it possible to clamp a plurality of pipette tips with a defined clamping force and to reduce the maximum force for ejecting the pipette tips. For this purpose, the multi-channel pipette on several contact elements on different Abwerferteilen. When attaching pipette tips, all the contact elements are in a defined starting position, which allows all pipette tips with a defined Aufklemmkraft be clamped on the pins until they hit the stop element. The ejector is designed so that when displacing the ejector down at least after the impact of a first contact element on pipette tips a second contact element lags the first contact element. As a result, first of all one or more pipette tips are pressed off the pins by the first contact element, and only one or more pipette tips are then pressed away from the pins by the second contact element. As a result, the maximum force for the ejection of the pipette tips is also reduced in the multi-channel pipette according to the invention. Preferably, the multi-channel pipette only has first and second contact elements on first and second Abwerferteilen. Moreover, the invention includes embodiments which has more than two Abwerferteile each with at least one contact element, wherein the contact element of another (eg third) Abwerferteils the contact element of the preceding (eg second) Abwerferteils at least after hitting pipette tips.

Preferably, the multi-channel pipette has identically designed pins, which are arranged in their initial position at the same height. The pins are preferably formed in accordance with the shape and dimensions coincident. Further preferably, the first spring elements of the multi-channel pipette are designed consistently. Further preferably, the first spring elements are biased when the pins are in the starting position. Preferably, the displacement device is a piston-cylinder device, wherein the displacement chamber is a cylinder and the displacement member is a piston displaceable in the cylinder.

According to one embodiment of the invention, the first and second Abwerferteile plate-shaped, the first contact element is at least one projecting horizontally from the lower edge of the first Abwerferteils first ridge with one or more first through holes, the second contact element is at least one horizontally from the lower edge of the second Abwerferteils projecting second web with one or more second through holes and the pins pass through the first and second through holes. About the plate-shaped first and second Abwerferteile and designed as webs first and second contact elements, the ejection force can be applied to one or more pipette tips on which the first contact member is seated, and one or more pipette tips, which is subsequently seated on the second contact element. By This embodiment is the ejector in a narrow, box-shaped pipette base (also called "dispensing head") of the multi-channel pipette housed.

According to a further embodiment, the ejector comprises a first ejector part, which is connected to the drive device, and a second ejector part, wherein the first ejector part and the second ejector part are displaceably guided by means for guiding in the longitudinal direction of the pins, are the first Abwerferteil arranged with the first contact element and the second Abwerferteil with the second contact element in the starting position of the ejector at the same height and first driving means on the first Abwerferteil and second entrainment means on the second Abwerferteil available, which are spaced apart in the initial position of the ejector and the displacement of the Abwerfers down by moving the first Abwerferteils and the second Abwerferteils relative to each other along the means for guiding against each other are movable to each other on the impact of the first and second entrainment means the second Abwerferteil concurrent with the to shift down the first ejector part.

In the starting position, the first and second driving means of the ejector are at a distance from each other. When displacing the ejector downwards, the first ejection part and the second ejection part are displaceable relative to one another in the longitudinal direction of the pins. The displacement of Abwerferteile with respect to each other is limited by the impact of the first and second entrainment means on each other. When the first contact element strikes the pipette tips when the ejector is displaced downwards, the second contact element is initially prevented from being pushed further down by the pipette tips. As a result, only the first ejector portion is displaced further downward and ejects pipette tips from the lugs. Here, the first Abwerferteil is displaced relative to the second Abwerferteil until the first entrainment means on the take second driving means. Thereafter, the first Abwerferteil takes the second Abwerferteil down with the second contact element pushes pipette tips of the pins. Thus, multiple pipette tips or multiple groups of pipette tips are successively ejected from the pin and the maximum force for ejecting the pipette tips is reduced.

In this embodiment, the contact elements are in the starting position of the ejector at the same height. As a result, the contact elements can also be used as stop elements. According to a preferred further embodiment, the contact elements are at the same time the stop elements and take the contact elements in the starting position of the ejector, the stop position.

According to one embodiment, the distance between the first and second driving means in the starting position of the ejector in the vertical direction is 0.1 to 3 mm, preferably 0.5 to 1.5 mm. This distance is sufficient to press different pipette tips or different group of pipette tips by means of the ejector successively and can be realized without noticeably increasing the discharge stroke.

According to a further embodiment, the first ejector part has at its lower edge a first recess with first guide elements on two lateral edges, and the second ejector part is inserted into the first recess of the first ejector part and on second guide elements on two lateral edges on the first guide elements of first Abwerferteil in the longitudinal direction of the pins displaced. In this case, the first and second ejection parts are preferably plate-shaped. By guiding the second ejection part to two lateral edges of the first recess ensures that the second Abwerferteil is easily displaced with respect to the first Abwerferteil.

According to a further embodiment, the first entrainment means are formed by the upper edge of the recess and the second entrainment means from the upper edge of the second Abwerferteils. The second Abwerferteil is displaced into the recess until it meets with its upper edge on the upper edge of the depression.

According to a further embodiment, the second ejection part is held on the first ejection part by connecting means which have a play in the longitudinal direction of the pin. By the connecting means, the second Abwerferteil is captively connected to the first Abwerferteil so that it can not be detached from the underside of the multi-channel pipette. According to a further embodiment, the connecting means are snap-connection means. The connection of the Abwerferteile by (snap) connection means is advantageous for assembly.

According to a further embodiment, the snap connection means comprise an eyelet on the first ejector part and a catch hook engaging the eyelet with play in the longitudinal direction of the eyelet on the second ejection part or vice versa. With these snap connection means the snap connection is particularly easy and safe to produce.

The first ejector part and the second ejector part preferably each consist of a rigid material. Further preferably, they are made of a plastic, further preferably of a thermoplastic.

In an alternative embodiment to the ejector with ejector parts guided displaceably relative to one another, the ejector has a rigid first ejector part and an at least partially soft second ejector part and are the first ejector part with the first contact element and the second ejector part with the second contact element in the starting position of the ejector arranged at the same height. When the Abwerferteile meet with the contact elements on the pipette tips, first pushes the rigid first Abwerferteil pipette tips of pins and at least partially the soft elastic second Abwerferteil initially blocked by pipette tips and elastically compressed. Only when the force for compressing the at least partially soft-elastic second Abwerferteils exceeds the force for dropping the voltage applied to the second contact element pipette tips, they are discarded. This also reduces the maximum force required to eject pipette tips.

The fact that the contact elements are in the starting position of the ejector at the same height, they are also available as stop elements. According to a preferred further embodiment, the contact elements are at the same time the stop elements and take the contact elements in the starting position of the ejector, the stop position.

The second Abwerferteil is according to a configuration on both sides - for example, by columns or slots - separated from the first Abwerferteil. In this embodiment, the elastic compression of the second Abwerferteils is not hindered by a connection with the first Abwerferteil on the two longitudinal sides of the second Abwerferteils.

According to one embodiment, the second Abwerferteil is elastic overall. According to a preferred embodiment, the second Abwerferteil is soft elastic in only one or more sections and otherwise rigid. According to a preferred embodiment, the soft elastic portion preferably extends parallel to the second contact element, so that the second Abwerferteil is elastically compressed when pressing the second contact element against the upper ends of pipette tips. The elastic deformation of the second ejection member concentrates on the soft elastic portion of the second ejection member.

According to one embodiment, the second contact element is a soft-elastic portion of the second Abwerferteils. According to a preferred embodiment, the second contact element is formed on a rigid portion of the second Abwerferteils and has the second Abwerferteil the soft elastic portion at a distance from the second contact element. According to a preferred embodiment, the second Abwerferteil is connected via a soft elastic portion with the rigid first Abwerferteil or supported on this. The rigid portion of the second Abwerferteils below the soft elastic portion of the second Abwerferteil is guided according to a further embodiment by means for guiding in the longitudinal direction of the pin on the first Abwerferteil displaced. In accordance with a further embodiment, the rigid portion of the second removal part is displaceably guided on second guide elements on two lateral edges on first guide elements of the first ejection part in the longitudinal direction of the pins.

In a multichannel pipette with a rigid first ejection part and an at least partially soft elastic second ejection part, according to a preferred embodiment, the second ejection part is in a depression at the bottom Arranged edge of the first Abwerferteils, connected at its upper edge via a soft elastic portion fixed to the upper edge of the recess.

Alternatively, the at least partially soft elastic second ejection member is connected according to an embodiment at its upper edge via a snap connection or via another detachable or non-detachable connection with the first Abwerferteil.

Preferably, the rigid first Abwerferteil of a rigid plastic and / or at least partially the soft elastic second Abwerferteil total or at least partially made of an elastomer. Further preferably, the first Abwerferteil consists of a thermoplastic and / or the second Abwerferteil total or at least partially made of a thermoplastic elastomer, a silicone elastomer or latex. According to a further embodiment, the second Abwerferteil partially made of a thermoplastic. A second ejection member having at least one soft elastic portion and at least one rigid portion is preferably made of two different plastic components in the two component or in the multi-component injection molding process.

According to another embodiment, the second Abwerferteil is connected via a soft elastic portion with the first Abwerferteil. The fixedly connected second and first Abwerferteile can be prepared by two-component or multi-component injection molding.

According to a further embodiment, the means for displaceably supporting the ejector have at least one guide slot extending in the longitudinal direction of the pin in the ejector and at least one guide element engaging in the guide slot and firmly connected to the base body. The Guide element is preferably a pin, a rib or another projection which engages in the guide slot.

According to a further embodiment, the ejector is in the starting position with the first and second contact elements or another Abwerferteil on a fixedly arranged on the main body counter-stop element, which prevents the ejector at a further displacement upwards. This ensures that the ejector is not displaced beyond its initial position to the top. If the contact elements are also stop elements, the counter-impact element supports the ejector, so that the contact elements are arranged in the stop position. In addition, or instead, the home position of the ejector may be defined by guide slots in the first and second ejector parts and in the guide slots engaging pins, ribs or other protrusions which abut in the home position at the bottom of the slots. According to a preferred embodiment, the counter-stop element is rigid.

According to a further embodiment, the counter-stop element is a lower wall of the base body with third passage openings through which the pins project downwardly and against which the contact elements in the starting position lie down. The counter-stop element may in particular be formed by a lower wall of a housing of the multichannel pipette. In the lower wall and the first and second contact elements high forces can be introduced when clamping pipette tips.

In an alternative to a multi-channel pipette, in which the contact elements of the ejector are also stop elements, the at least one stop element is formed separately from the contact elements of the ejector.

The stop element is fixedly arranged in the defined stop position on the base body. The stopper member is formed by a lower wall of the main body having third through holes through which the pins project downwardly. The bottom wall extends only to a horizontal line which intersects all the pins so that the third through holes only partially surround the pins. For example, the third passages surround the pegs only in half, or up to a horizontal line that intersects all the pegs in the center. In addition to the lower wall, the ejector with its contact elements is arranged at least at the same height as this. Preferably, the contact elements on first and second through holes, which partially surround the pins on one side. When the ejector is in the home position, pipette tips are clamped onto the pins until they impact the abutment member. To eject the pipette tips, the ejector is displaced downwards, so that first the first stop elements and then the second stop element and, if appropriate, then further stop elements press pipette tips off the pins. In this embodiment, the ejector may be formed with stop elements which are arranged rigidly in stages. Instead, the ejector relative to each other displaceably guided Abwerferteile or have a rigid and a soft-elastic Abwerferteil.

According to a further embodiment, the ejector is displaceable downward against the spring action of a second spring element acting on the ejector and on the main body. Preferably, the second spring element is biased when the ejector is in the starting position. By the second spring element of the ejector is automatically shifted after dropping back into the starting position. According to an alternative embodiment, the multi-channel pipette has means for releasably holding the ejector in the starting position. The means for releasably holding are, for example latching means which the ejector in the starting position hold. The ejector is eg by clamping pipette tips on the pins of the pipette tips from a lower end position displaced to the starting position, in which the ejector is held by the means for releasable holding.

According to a further embodiment, the number of pins, of which by means of the first contact element pipette tips are abdrückbar, the same size as the number of pins which are abdrückbar by which means of the second contact element pipette tips. In this division, the ejection forces are distributed evenly on the first ejector part and the second ejector part.

According to one embodiment, the multichannel pipette has any number of pins for simultaneously holding any number of pipette tips. Preferably, the multi-channel pipette has eight pins or twelve pins. According to another embodiment, the multi-channel pipette on a multiple of eight pins or a multiple of twelve pins. The pins of the multi-channel pipette are preferably arranged in a row next to each other. According to a further embodiment, the multi-channel pipette has a plurality of rows of pins arranged next to one another.

According to a further embodiment, pipette tips of in each case four pins or of in each case six pins can be pressed off by means of the first and the second contact element. These multichannel pipettes can hold a total of eight pipette tips or twelve pipette tips simultaneously. This is advantageous for use with common microtiter plates having recesses in eight rows and twelve columns. According to a further embodiment, pipette tips of in each case less than four pins or of more than six pins can be pressed off by means of the first and the second contact element. These Embodiments may be particularly advantageous multi-channel pipettes having less than eight pins or more than twelve pins.

In one embodiment, the multichannel pipette is a manual pipette, i. a pipette that can be held and operated by the user when using one or both hands.

The first drive device is mechanical in a manually driven pipette. It preferably has a dosing button and a lifting rod protruding from the dosing button, which is connected or detachable at the lower end with the displacement element of the displacement device. The multichannel pipette is a fixed volume pipette or a pipette with adjustable dosing volume. In a fixed-volume pipette, the stroke of the lifting rod is limited by impingement of a circumferential bead or other projection on the circumference of the lifting rod to an upper and a lower stop whose position is not adjustable in the main body. In a pipette with adjustable dosing volume, the position of at least one of the two stops in the body is adjustable. Preferably, the multi-channel pipette for displacing the upper stop on a threaded spindle, which is threadably arranged in a nut which is fixedly connected to the main body. The lifting rod is passed through a passage channel of the threaded spindle and the lower end face of the threaded spindle forms the upper stop for the projection on the lifting rod.

In one embodiment of the multichannel pipette as a manually driven multichannel pipette, the second drive device can be actuated by means of the dosing button of the first drive device. After a Dosierhub and an overstroke the pipette tips are dropped in a discharge stroke of Dosierknopfes.

This embodiment allows a dosing and ejection of pipette tips by pressing the same button (so-called "one-button operation").

According to another embodiment, the multichannel pipette has a second drive device with a discharge button, which is formed separately from the dosing button (so-called "two-button operation"). Such a trained manually driven multi-channel pipette is for example in the DE 10 2004 003 433 B4 described. In this regard, reference is made to the DE 10 2004 003 433 B4 , the content of which is hereby incorporated into this application.

In the embodiment as an electronic pipette, the multichannel pipette has an electric drive motor and a transmission between the drive motor and the displacement element and an electronic control of the drive motor with an electrical dosing button. The second drive means of the multi-channel pipette is designed, for example, as in the DE 10 2004 003 433 B4 described. In this regard, reference is made to the DE 10 2004 003 433 B4 , the content of which is hereby incorporated into this application.

Preferably, the multi-channel pipette comprises a pipette top comprising the first and second drive means and a dispensing head comprising the displacement chambers and the ejector. The pipette top and the dispensing button are preferably releasably connectable to each other. The means for detachably connecting pipette upper parts and dispensing head are for example designed as in the DE 10 2004 003 433 B4 described. In this regard, reference is made to the DE 10 2004 003 433 B4 , the content of which is hereby incorporated into this application.

Fig. 1

eine Mehrkanalpipette mit Einknopfbedienung in einer Ansicht von der Vorderseite bei teilweise ausgebrochenem Abgabekopf;

Fig. 2

dieselbe Mehrkanalpipette in Rückansicht bei teilweise ausgebrochenem Abgabekopf;

Fig. 3

den Abwerfer derselben Mehrkanalpipette in vergrößerter Vorderansicht;

Fig. 4

denselben Abwerfer in vergrößerter Rückansicht;

Fig. 5

denselben Abwerfer in vergrößerter Unteransicht;

Fig. 6

denselben Abwerfer in einer Perspektivansicht schräg von vom und von der Seite;

Fig. 7

denselben Abwerfer mit aneinander anliegenden Mitnahmemitteln der beiden Abwerferteile in Vorderansicht;

Fig. 8

denselben Abwerfer in seine Abwerferteile zerlegt in Vorderansicht;

Fig. 9

den Abgabekopf derselben Mehrkanalpipette in teilweise ausgebrochener, vergrößerter Vorderansicht;

Fig. 10

denselben Abgabekopf bei betätigten Abwerfer in vergrößerter, teilweise ausgebrochener Vorderansicht;

Fig. 11

eine Mehrkanalpipette mit Zweiknopfbedienung in Vorderansicht mit teilweise ausgebrochenem Abgabekopf;

Fig. 12

dieselbe Mehrkanalpipette in Rückansicht mit teilweise ausgebrochenem Abgabekopf;

Fig. 13

einen alternativen Abwerfer mit teilweise weichelastischem zweiten Abwerferteil in vergrößerter Vorderansicht;

Fig. 14

derselbe Abwerfer in vergrößerter Rückansicht;

Fig. 15

ein weiterer alternativer Abwerfer mit teilweise elastischem zweiten Abwerferteil in vergrößerter Vorderansicht;

Fig. 16

derselbe Abwerfer in vergrößerter Rückansicht.

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

Fig. 1

a multi-channel pipette with one-button operation in a view from the front with partially broken out dispensing head;

Fig. 2

the same multichannel pipette in rear view with partly broken out dispensing head;

Fig. 3

the ejector of the same multi-channel pipette in an enlarged front view;

Fig. 4

the same ejector in an enlarged rear view;

Fig. 5

the same ejector in an enlarged bottom view;

Fig. 6

the same ejector in a perspective view obliquely from and from the side;

Fig. 7

the same ejector with adjacent driving means of the two Abwerferteile in front view;

Fig. 8

the same ejector disassembled into its ejector parts in front view;

Fig. 9

the dispensing head of the same multi-channel pipette in partially broken, enlarged front view;

Fig. 10

the same dispensing head with actuated ejector in an enlarged, partially broken front view;

Fig. 11

a multi-channel pipette with two button operation in front view with partially erupted dispensing head;

Fig. 12

the same multichannel pipette in rear view with partly broken off dispensing head;

Fig. 13

an alternative ejector with partially soft elastic second Abwerferteil in enlarged front view;

Fig. 14

the same ejector in enlarged rear view;

Fig. 15

another alternative ejector with partially elastic second ejector part in an enlarged front view;

Fig. 16

the same ejector in enlarged rear view.

In this application, the terms "up" and "down", "at the same height" and "horizontal" and "vertical" refer to an orientation of the multichannel pipette in which pipette tips clamped on the pegs are vertically aligned with their syringe orifices facing downwards to pick up a liquid from an underlying vessel or to dispense into the vessel.

All embodiments relate to multi-channel pipettes in which the contact elements of the ejector are also stop elements. The contact elements are hereinafter referred to as stop elements.

According to Fig. 1 and 2 a multichannel pipette 1.1 has a pipette top part 2 with an upper housing part 3 and a pipette lower part 4 with a lower housing part 5. The upper housing part 3 is designed as a handle or a handle-shaped one. The lower housing part 5 essentially has the shape of a flat box. Upper housing part 3 and lower housing part 5 are together a basic body.

The pipette upper part 2 comprises a first drive device 6 for displacement devices and a second drive device 7 for a ejector.

The first drive device 6 comprises a top of the housing upper part 3 projecting and longitudinally displaceable in the upper housing part arranged Dosierknopf 8. The Dosierknopf 8 is coupled at the bottom with a lifting rod 9, which has a circumferential bead 10 on the circumference. The lifting rod 9 is in her Longitudinal direction by pressing the Dosierknopfes 8 against the action of a return spring 11 in the upper housing part displaced.

The displacement of the lifting rod 9 is limited by an upper stop 12 and a lower stop 13. The upper stop 12 is adjustable in the longitudinal direction of the upper housing part 3. The Dosierknopf 8 is coupled via a gear 14 with the upper stop 12, so that by turning the Dosierknopfes 8, the upper stop 12 in the longitudinal direction of the upper housing part 3 is adjustable.

The lower stop 13 is held in the upper housing part 3 by a spring device 15. The spring means 15 (also called "overstroke spring") allows for the impact of the bead 10 on the lower stop 13, a further displacement of the lifting rod 9 under increased effort down to perform an overstroke and a discharge stroke.

Further, a transmission device 16 is arranged in the upper housing part 3, which transmits a displacement of the lifting rod 9 during the discharge stroke to a displacement of a discharge sleeve 17 downwards, which is arranged at the lower end of the housing upper part 3.

The upper housing part 3 has at the lower end a hollow cylindrical receptacle 18 into which a sleeve-shaped retaining element of the pipette lower part 4 can be inserted through an insertion opening 19 in the lower end. The pipette upper part 2 has on the receptacle 18 first means for detachable connection 20 with the pipette lower part 4. The ejection sleeve 17 is arranged concentrically with respect to the receptacle 18 and projects from the lower edge of the insertion opening 19 downwards. The lower end of the lifting rod 9 projects from above into the receptacle 18 when the dosing button 8 is not pressed.

According to Fig. 1 . 2 and 9 . 10 For example, the pipette lower part 4 comprises a lower housing part 5, which is formed by a front and a rear housing shell 21, 22, which are joined together in a vertical plane. In the lower housing part 5 eight parallel piston-cylinder devices 23 are arranged in a row. Each piston-cylinder device 23 has a cylinder 24 into which a piston 25 dips.

Below, each cylinder 24 is integrally connected to a pin 26, which tapers downwardly, to a metering member 27. Each pin 26 has a connection hole 28 which is connected at the top to an inner space of the cylinder 24 in which the piston 25 is displaceable, and opens at the bottom in an opening 29 in the lower end of the pin 26.

Between the pins 26 and the cylinders 24, each metering component 27 has a circumferential projection 30.

The circumferential projections 30 of the Dosierbauteile 27 are based on the upper edges of third through holes 31 in a horizontal bottom wall 32 of the housing base 5 from. The cylinders 24 are passed further up through fourth through-holes 33 of a horizontal support plate 34 of the housing base 5.

On each cylinder 24 designed as a helical spring first spring element 35 is guided, which is supported on the bottom of the circumferential projection 30 and the top of the underside of the support plate 34.

The pistons 25 have at the upper end of a piston rod 36 a piston plate 37. The piston plates are in piston plate receptacles 38 a horizontally oriented Traverse 39 held. The traverse 39 has a vertically upstanding rod 40 at the top, which has a contact surface for the lower end of the lifting rod 9 of the pipette shell 2 at the upper end.

From the lower housing part 5 is upwardly a sleeve-shaped retaining element 41, through which the rod 40 extends therethrough. The holding element 41 has second means for releasably connecting 42, which are detachably connected to the first means for releasably connecting 20 of the pipette top 2.

The components of the pipette lower part 4 described above are held in the front housing shell 21.

Furthermore, the pipette lower part 4 comprises an ejector 43. According to Fig. 3 to 9 the ejector 43 has a plate-shaped substantially rectangular, first Abwerferteil 44 with chamfers 45, 46 at the two upper corners. The first Abwerferteil 44 has at a rectilinear, lower edge 47 a centrally disposed, rectangular first recess 48. The first Abwerferteil 44 has on the lower edge 45 on both sides of the recess 48 each have a first stop member 49, 50, by a horizontally oriented first web is formed, the first passage openings 51, 52 which are open to the front edge 53, 54 of the first stop element 49, 50 out.

Further, the first Abwerferteil 44 a plurality of parallel guide slots 55, which are aligned perpendicular to its lower edge 47.

The first ejector portion 44 has centrally at the upper first edge 56 of the first recess 48 a downwardly projecting eyelet 57 with an elongate, rectangular eyelet opening 58.

From the upper edge 56 of the first Abwerferteils 44 an actuator 59 projects in the form of a shaft having a flat, aligned with the front of the first Abwerferteils front and with respect to the back of the first Abwerferteils 44 slightly cylindrical from the bulging back. In the bulging front, the actuator 59 has a longitudinally extending groove 60 which is bounded above by a first abutment 61.

The actuator 59 has two above, strip-shaped transmission elements 62, which are hollow cylindrical in a horizontal section.

In the first recess 48, a plate-shaped second Abwerferteil 63 is inserted. The second ejector portion 63 has at the lower edge 64 a second stop member 65 formed by a second land having second through holes 66 opened to the front edge 67 of the second land. At the upper second edge 68 of the second Abwerferteils 63 is centrally a small second recess 69 is provided, projecting beyond which a snap hook 70 which is connected below the second recess 69 with the front of the second Abwerferteils 63.

The upper first edge of the first recess 48 is a first entrainment means 56 and the upper second edge of the second Abwerferteils 63, a second driving means 68. When the first stop member 49, 50 and the second stop member 65 is arranged at the same height, is between the first and the second driving means 56, 68, a gap 71 is present, which is for example about 0.75 mm. In this position, the snap hook 70 is located at the bottom of the eyelet opening 58.

The second Abwerferteil 63 has at the two lateral edges in each case a longitudinal groove 72, 73. The first Abwerferteil 44 engages with the two lateral edges 74, 75 of the first recess 48 in the two longitudinal grooves 72, 73 a.

The ejector 43 is guided in the rear housing shell 22 of the lower housing part 5 of ribs 76 which protrude from the inside of the rear wall 77 of the housing lower part 5. The ribs 76 engage in the guide slots 55.

The actuator 59 is passed with the transmission elements 62 through arcuate slots 78 in a horizontal upper wall 79 of the rear housing shell 22. The rear wall 77 of the rear housing shell 22 has an outwardly curved rear wall part, in which the actuating element 59 is inserted with its bulging side. The rear wall 77 has on the inside in the region of the bulge on a second abutment. Between the second abutment and the first abutment 61 of the fastening element 59, a second spring element 82 designed as a helical spring is held in the groove 60 under prestressing, which loads the ejector 43 so that the ribs 76 bear against the lower end of the guide slots 55.

Two side walls 83, 84 of the rear housing shell 22 have on the inside small projecting retaining elements 86, which project slightly beyond the lateral edges of the first Abwerferteils 44. The first ejector portion 44 has two small lateral recesses 87, 88. The first ejector portion 44 is pushed with the side recesses 87, 88 on the retaining elements 86 and is held by the second spring element 82 in a position in which the retaining elements 85, 86 below the lateral recesses 44 abut the first Abwerferteil 44.

The ejector is thus held up in the slots 78 and at the bottom by the retaining elements 85, 86 in the rear housing shell 22.

When the front housing shell 21 and the rear housing shell 22 are assembled, the first and second stopper members 49, 50, 65 abut the bottom wall 32 of the housing base 5 at the bottom and the transmission members 62 abut against the retaining member 41 on the outside.

In the assembled state of pipette upper part 2 and pipette lower part 4, the first and second means for releasably connecting 20, 42 releasably connected to each other. The lifting rod 9 is located at the bottom of the upper end of the rod 40. The ejection sleeve 17 abuts against the upper end of the transmission elements 62.

The multi-channel pipette 1.1 can be used as follows:

If necessary, the metering volume is adjusted by means of the dosing knob 8.

Further, the multi-channel pipette 1.1 is inserted with the pins 26 in the Aufstecköffnungen of pipette tips 89, which are provided in a holder. Here are the first and second stop members 49, 50, 65 of the ejector 43 in stop position at the same height, as in Fig. 1 . 2 and 9 shown. As a result of the clamping forces, the first spring elements 35 are compressed until the pipette tips 89 rest against the first and second stop elements 49, 50, 65 at the bottom. Thereafter, the multi-channel pipette 1.1 is lifted with the clamped pipette tips and the pins 26 return to the starting position of Fig. 1 . 2 and 9 back.

Subsequently, the Dosierknopf 8 is pressed until the impact of the bead 10 on the lower stop 13, an increased resistance is felt. Here, the lifting rod 9 moves over the rod 40 and the cross member 39, the piston 25 against the action of the first spring elements 35 down so that air is forced out of the pipette tips. Subsequently, the pipette tips are simultaneously immersed in vessels and then the Dosierknopf 8 relieved. The return spring 11 displaces the lifting rod 9 back into the starting position and the first spring elements 35 displace the pistons 25 back into the starting position. As a result, liquid is sucked from the vessels into the pipette tips 89.

For the delivery of the absorbed liquid, the pipette tips 89 are directed to other vessels. Subsequently, the dosing button 8 is pressed until the impact of the bead 10 on the lower stop 13. By further pressing the Dosierknopfes 8 against the action of the spring means 15, an overstroke for a residual quantity is initially effected. The end of the overstroke is felt by the user at a further increased resistance due to the action of the second spring element 82 at the beginning of the discharge stroke. By further pressing the Dosierknopfes 8 a discharge stroke is effected, in which the transfer device 16, the discharge sleeve 17 shift down. Here, the ejection sleeve 17 moves the transmission elements 62 down and the ejector 43 is pressed against the action of the second spring member 82 down.

When the ejector 43 hits the pipette tips 89 with the stop members 49, 50, 65, the pipette tips 89 on the lugs under the second ejector portion 63 block further displacement of the second ejector portion 63 downward. Upon further actuation of the Dosierknopfs 8, only the first Abwerferteil 44 is further displaced downwards and pushes the two outer groups of pipette tips 89 of the pin 26 under the first stop elements 49, 50th from. Finally, the first and second entrainment means (56, 68) hit each other and thereby also the second Abwerferteil 63 is moved further down, so that the second stop member 65, the underlying middle group of pipette tips 89 from the pin 26 depressed. Fig. 10 shows the ejector 43 at the beginning of pressing the middle group.

After relieving the dosing 8, the return spring 11 presses the dosing button 8 via the lifting rod 9. According to one embodiment, the return spring 11 also pushes the transfer device 16 ejection sleeve 17 back into the upper position. Alternatively, the transfer device 16 has its own return spring, which moves the transfer device 16 and the discharge sleeve 17 back into the upper position. The spring device 15 assumes its initial state again. The second spring element 82 displaces the ejector 43 in the starting position of Fig. 1 . 2 and 9 back.

The multichannel pipette 1.2 of Fig. 11 and 12 differs from the above-described in that it has a two button operation. In the two-button operation of the dosing 8 controls only the recording and the delivery of liquid and controls an additional ejection button 90 the ejector 43. For this purpose, the multi-channel pipette 1.2 at the top of a top of the housing 3 upwardly projecting release button 90, the bottom with a in Longitudinal direction of the housing displaced guided discharge rod 91 is connected. The discharge rod 91 is in turn connected to the bottom of the discharge sleeve 17.

A discharge spring 92 engages the discharge bar 91 or the discharge button 90 and a fixed point in the upper housing part 3, so that the discharge button 90 against the action of the ejector spring 92 can be pressed.

The operation of this multichannel pipette 1.2 differs from the operation of the previously described multichannel pipette 1.1 only in that for dropping the pipette tips 89 of the ejection button 90 must be pressed. As a result, the ejection sleeve 17 is displaced downwards, whereby the transmission elements 62 of the ejector 43 are displaced downwards.

After discharge of the ejection button 90, the ejection spring 92 sets the ejection button 90 and the ejection rod 91 back to the upper starting position. Further, the second spring element 82, the ejector 43 in the dispensing head 4 back to the starting position.

The ejector 43.1 of Fig. 13 and 14 differs from the previously described ejector 43 in that at the upper second edge 68 of the second Abwerferteils 63, a strip-shaped portion 93.1 molded of soft elastic material. The strip-shaped portion 93.1 abuts with its upper edge on the upper first edge 56 of the first Abwerferteils 44. In this arrangement, the second Abwerferteil 63 is held by the snapped in the eyelet 57 snap hook 70 free of play.

The ejector 43.1 is like the previously described ejector 43 in the previously described multi-channel pipette 1.1, 1.2 can be installed. When attaching and dropping pipette tips 89 on and from the pins 26 of pipette tips 89 on and from the pin 26 of the ejector 43.1 acts as the ejector 43. When ejecting the pipette tips on the pipette tips 89, the strip-shaped portion 93.1 is first compressed in the vertical direction until the spring force acting in the strip-shaped section 93.1 is high enough to push the middle group of pipette tips 89 away from the pins 26. Here, the material consisting of rigid material lower plate-shaped portion 94 of the second Abwerferteils 63 guided with the longitudinal grooves 72, 73 at the lateral edges 74, 75 of the first Abwerferteils 44 (corresponding to Fig. 5 ).

The ejector 43.2 of Fig. 14 and 15 differs from the ejector 43 in that the second Abwerferteil 63 has a strip-shaped portion 93.2 of soft elastic material at the lower edge 64. The strip-shaped portion 93. 2 leaves the second through-holes 66 exposed, so that the pins 26 can be passed through the second through-holes 66. The strip-shaped section 93.2 forms the second stop element 65 and at the same time the second contact element. Incidentally, the second ejection part 63 is formed integrally with the first ejection part 44.

The ejector 43.2 is like the ejector 43 in a multi-channel pipette 1.1, 1.2 can be installed. When plugging and dropping pipette tips 89 onto the pins 26, the ejector 43. 2 acts like the ejector 43. During ejection, the strip-shaped section 93. 2 is first compressed when it strikes the middle group of pipette tips 86. When the elastic restoring forces in the strip-shaped section 93.2 have risen sufficiently, the strip-shaped section 93.2 or the second ejector 43.1 pushes the middle group of pipette tips away from the pins 26.

LIST OF REFERENCE NUMBERS

1.1, 1.2

Multichannel pipette

2

Pipette shell

3

Housing upper part (main body)

4

Pipette lower part (dispensing head)

5

Housing base (basic body)

6

first drive device

7

second drive device

8th

dose

9

lifting rod

10

bead

11

Return spring

12

upper stop

13

bottom stop

14

transmission

15

spring means

16

transmission equipment

17

ejector sleeve

18

admission

19

insertion

20

first means for detachable connection

21

front housing shell

22

rear housing shell

23

Piston-cylinder device

24

cylinder

25

piston

26

spigot

27

proportioning

28

connecting hole

29

opening

30

circumferential lead

31

third through hole

32

bottom wall

33

fourth through hole

34

support plate

35

first spring element

36

piston rod

37

piston plate

38

Piston plate receptacle

39

traverse

40

pole

41

retaining element

42

second means for releasably connecting

43, 43.1, 43.2

ejector

44

first ejection part

45.46

bevel

47

lower edge

48

first recess

49, 50

first stop element (first bridge)

51, 52

first through hole

53, 54

front edge

55

guide slot

56

first driving device (upper first edge)

57

eyelet

58

eyelet opening

59

actuator

60

groove

61

first abutment

62

transmission element

63

second ejection part

64

lower edge

65

second stop element (second bridge)

66

second through hole

67

front edge

68

second driving device (upper second edge)

69

second recess

70

snap hooks

71

gap

72, 73

longitudinal groove

74, 75

lateral edge

76

rib

77

rear wall

78

slot

79

upper wall

82

second spring element

83,84

Side wall

86

Retaining element

87, 88

lateral depression

89

pipette tip

90

ejector button

91

Abwurfstange

92

ejection spring

93.1, 93.2

strip-shaped section

94

plate-shaped section

Claims (16)

Multi-channel pipette with ● a base body (5), ● a plurality of pins (26) projecting parallel to one another in a row from the base body (5) and mounted in the longitudinal direction so as to be able to clamp pipette tips (89), At least one displacement device (23) having a displacement chamber (24) and a displaceable therein displacer (25), wherein the displacement chamber (23) with connecting holes (28) in the pin (26) is connected to air through openings (29) of To eject or suck in connection holes (28) in lower ends of the pins (26), ● a first drive device (6), which is connected to the displacement element (25) and which is designed to displace the displacement element (25) in the displacement chamber (24), ● on the pin (24) and on the base body (5) engaging the first spring elements (35), wherein the pins (26) against the spring action of the first spring elements (35) from a starting position in its longitudinal direction are displaced upward, At least one stop element (49, 50, 65) having a defined stop position in which the pins (26) project downwardly from the stop element (49, 50, 65), Wherein the first spring elements (35) are designed so that the pins (26) of defined clamping forces, which can be applied by clamping pipette tips (89) on the pins (26), in such a way to the stop element (49, 50, 65) displaced in the stop position are that the pipette tips (89) impinge on the stop element (49, 50, 65), and An ejection device for releasing pipette tips (89) from the pins (26), comprising an ejector (43) having contact elements (49, 50, 65), means for displaceably supporting (55, 76) the ejector (43) on Main body (5) in the longitudinal direction of the pin (26) and connected to the ejector (43) drive means, which is designed, the ejector from a starting position in the pipette tips (89) to hitting the stop element (49, 50, 65 ) can be clamped in the stop position on the pins (26), in the longitudinal direction of the pin (26) to shift down to press with the contact elements (49, 50, 65) pipette tips (89) of the pins (26), Wherein the ejector (43) has the contact elements (49, 50, 65) at different Abwerferteilen (44, 63) and is formed so that when displacing the Abwerfers (43) downwards at least after the impact of at least one first contact element (49 50) on pipette tips (89) at least one second contact element (65) lags the first contact element (49, 50) in order first to contact the first contact element (49, 50) with one or more pipette tips (89) and then with the second contact element (49). 65) one or more pipette tips (89) from the pins (26). The multichannel pipette of claim 1, wherein the first and second ejection members (44, 63) are plate-shaped, the first contact member (49, 50) having at least one first land projecting from the lower edge of the first ejection member (44) with one or more first through-holes (51, 52), the second contact element (65) at least one horizontally from the lower edge of the second Abwerferteils (63) projecting second web with one or a plurality of second through holes (66) and the pins (26) pass through the first and second through holes (51, 52, 66). A multi-channel pipette according to claim 1 or 2, wherein the ejector (43) comprises a first ejection member (44) connected to the drive means and a second ejection member (63), the first ejection member (43) and the second ejection member being provided by means for guiding (72, 73, 74, 75) in the longitudinal direction of the pins (26) are displaceably guided with respect to each other, the first Abwerferteil (44) with the first contact element (49, 50) and the second Abwerferteil (63) with the second Contact element (65) in the starting position of the ejector (43) are arranged at the same height, and first entrainment means (56) on the first Abwerferteil (44) and second entrainment means (68) on the second Abwerferteil (63) are present in the starting position of the Abwerfers (43) are spaced from each other and when moving the Abwerfers (43) downwards by displacing the first Abwerferteils (44) and the second Abwerferteils (63) relative to each other along the means for guiding (72, 73, 74, 75) gege Movable with each other to move the second Abwerferteil (63) concurrently with the first Abwerferteil (44) to the bottom upon impact of the first and second entrainment means (56, 68). Multi-channel pipette according to claim 3, wherein the contact elements (49, 50, 65) are stop elements and in the initial position of the ejector (43) occupy the stop position. A multi-channel pipette according to claim 3 or 4, wherein the distance between the first and second driving means (56, 68) in the initial position of the Abwerfers (43) in the vertical direction 0.1 to 3 mm, preferably 0.5 to 1.5 mm. A multichannel pipette according to any one of claims 3 to 5, wherein the first ejection member (44) has at its lower edge a first recess (48) with first guide elements (74, 75) at two lateral edges, and wherein the second ejector member (63). in the first recess (48) of the first Abwerferteils (44) is inserted and on second guide elements (72, 73) on two lateral edges on the first guide elements (74, 75) of the first Abwerferteils (44) in the longitudinal direction of the pin (26) is displaced led. A multi-channel pipette according to claim 6, wherein the first entrainment means (56) from the upper edge of the recess (48) and the second entrainment means (68) from the upper edge of the second Abwerferteils (63) are formed. A multi-channel pipette as claimed in claim 6 or 7, wherein the second ejection member (63) is retained on the first ejection member (44) by snap-connection means or other connecting means (57,70) having longitudinal play of the pins (26). A multi-channel pipette according to claim 8, wherein the snap-connection means comprises an eyelet (57) on the first ejection member (44) and a snap hook (70) engaging the eyelet (57) longitudinally of the pins (26) on the second ejection member (63) or have reversed. A multi-channel pipette as claimed in claim 1 or 2, wherein the ejector (43.1, 43.2) comprises a rigid first ejector member (44) and an at least partially rigid second ejector member (63), and the first ejector member (44) is associated with the first ejector member (43) Contact element (49, 50) and the second Abwerferteil with the second contact element (65) in the starting position of the Abwerfers (43.1, 43.2) are arranged at the same height, so that when hitting the Abwerferteile with the contact elements on the pipette tips (89) initially the rigid first ejector member (44) depresses pipette tips from pins and blocks the at least partially soft elastic second ejector member (63) from pipette tips (89) and resiliently compresses and after an increase in force to compress the at least partially soft second ejector member (63) to force for discharging the value exceeding the value applied to the second contact element (65), the tips of the pipette (89) resting against the second contact element (65) are dropped off. A multi-channel pipette according to any one of claims 1 to 10, wherein the means for slidably supporting (55, 76) the ejector (43) at least one in the longitudinal direction of the pin (26) extending guide slot (55) in the ejector (43) and at least one in the Guide slot (55) engaging, fixed to the base body (5) connected to guide element (76). A multi-channel pipette according to any one of claims 1 to 11, wherein the ejector (43) at the top has an actuating element (59) projecting in the longitudinal direction of the pins (26). Multi-channel pipette according to one of claims 1 to 12, wherein the ejector with the first and second stop members (49, 50, 65) or another Abwerferteil in its initial position on a fixed to the base body (5) arranged counter-stop element (32) rests, the Prevent ejector at a displacement further up. The multichannel pipette of claim 13, wherein the counter-abutment member (32) is a bottom wall of the main body (5) having third through-holes through which the trunnions (26) project downwardly and at which the abutment members (49, 50, 65) in the Starting position at the bottom. Multichannel pipette according to one of Claims 1 to 14, in which the ejector (43) is displaceable downward against the spring effect of a second spring element (82) acting on the ejector (43) and on the base body (5). A multichannel pipette according to any one of claims 1 to 15, wherein the number of pins (26) projecting from the first stop member (49, 50) is equal to the number of pins (26) of the second stop member (65) ) protrude.

Images