EP3680016B1 - Pipette for use with a pipette tip - Google Patents

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 a homogeneous mixture of several liquid components (solutions). Furthermore, the liquids can be heterogeneous (multiphase) mixtures of a liquid with another liquid (emulsions) or a solid (suspensions).

Pipettes have a stem-shaped pipette housing with a pin (shoulder) 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 lower end and an attachment opening at the upper end, with which the pipette tip can be clamped onto the pin. The liquid is taken up in the pipette tip and dispensed from it. The uptake and delivery of the liquid is controlled by means of the pipette. Fixed volume pipettes are used to pipette constant volumes. With variable pipettes, the volume to be dispensed can be set. A mechanical counter is used to display the set volume. To set the volume, the stroke of a drive device can be adjusted by means of an adjusting device which is coupled to the counter. The pipette tip is detached from the base after use and can be exchanged for a fresh pipette tip. In this way, cross-contamination can be avoided during subsequent pipetting operations. Air-cushion pipettes have a piston-cylinder system in the pipette housing, which is connected to a through hole in the pin via a channel. 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 in liquid into a pipette tip clamped onto the pin and to expel it therefrom. The disadvantage of air-cushion pipettes are metering errors due to the change in the length of the air cushion due to the weight of the liquid sucked in and the effects of temperature, air pressure and air 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 pin for fastening the pipette tip and a drive device, which can be coupled to the integrated piston (tip piston), for moving the piston. The piston comes in direct contact with the liquid, eliminating the effects of an air cushion. Positive displacement pipettes are particularly suitable for dosing liquids with high vapor pressure, high viscosity or high density and applications in molecular biology where freedom from aerosols is important in order to avoid contamination.

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

In the positive displacement pipette Biomaster® 4830 from Eppendorf AG, the drive device has a lifting rod for moving a piston in a pipette tip, which has a hollow lower lifting rod part and an upper lifting rod part inserted into the lower lifting rod part from above. The upper lifting rod part is connected to an operating element which protrudes from the upper end of the pipette housing. A Mastertip® pipette tip from Eppendorf AG is can be clamped onto a pin of the pipette. By pressing the operating element, the lifting rod can be moved downwards so that an upper end of the piston rod of a tip piston of the pipette tip is pressed into the lower lifting rod part. When moving the lifting rod down to a lower stop, a spring device is pretensioned. After the operating element is relieved of pressure, the spring device moves the lifting rod up to an upper stop, the tip piston being carried along and liquid being sucked into the pipette tip. The sucked-in liquid can be dispensed by pressing the control element again as far as the lower stop. To release the pipette tip, the user must press the control element with increased force so that another spring device compresses, the upper lifting rod part is shifted downwards in the lower lifting rod part, the piston is pushed out of the lower lifting rod part and the pipette tip is pushed off the pin.

To release the pipette tip from the pipette, the spring action of the spring devices must be overcome. This can be tiring for the user, especially if the pipette tips have to be replaced frequently. Furthermore, when dispensing highly viscous liquids and when dispensing liquids rapidly from the pipette tip, the pipette tip may become detached from the pin due to the increased flow resistance in the tip opening.

the EP 0 992 288 B1 describes a pipette with an ejection device for a pipette tip into which a traction mechanism, pressure mechanism or articulated mechanism is integrated. As a result of the translation of the gear, the ejection rod acting on the pipette tip covers a shorter distance than the drive rod connected to an ejection button, so that the ejection force is greater than the force for actuating the ejection device. The ejection device is in the pipette housing on the side next to the drive device for the displacement device arranged, whereby the pipette has a large volume. The pipette has the eject button in addition to the control button, so that the user has to change his grip to eject the pipette tip after pipetting.

the DE 103 55 914 B3 describes a pipette with an ejection device which converts an axial movement of the actuating button into an axial and rotary movement of the ejector with respect to the attachment. This is intended to reduce the effort required to operate the ejector.

the EP 1 689 528 B1 describes a pipette with a tip removal mechanism that includes a ramp member that is rotatable, has a ramp surface forming a circle, and includes one or more segments, the ramp surface having a high point and a low point in each segment. As a result, when the ramp surface is rotated over a single segment, a release element of the release device is to be forced to first move towards the tip and then to return. The known ejection device is also arranged laterally next to the drive device, whereby the structural volume of the pipette is large. In addition, the ejection device has a separate operating button. This is designed as an electrical button that controls a motor that rotates the ramp element via a gear. The structural effort of the discharge device is great.

the DE 27 11 124 C2 describes a pipette that can be connected to a pipette tip via a bayonet lock. The pipette tip must be removed from the pipette by hand. This can lead to contamination.

the DE 10 2006 036 764 B4 describes a pipette tip which has a latching element for latching with a slip-on shaft and a sealing area for sealing on the slip-on shaft. In the area of the latching element, the pipette tip has a slot running through at least one slot in the axial direction of the pipette tip weakened wall. In this way, the sealing fixing of the pipette tip on the slip-on shaft and the detachment of the pipette tip from the slip-on shaft can be facilitated. When pipetting highly viscous liquids and when pipetting quickly, the pipette tip can be pushed off the shaft.

the US 2003/0074988 A1 describes a pipette with an ejector and an actuating device for ejecting pipette tips. The actuating device has at least one cam element which is pivotably connected to the pipette housing about a horizontal hinge axis for cooperation with the ejector. This mechanism enables the cam element to have a variable torque conversion ratio when the actuating element is actuated.

the WO2011 / 025399 A2 describes a mechanical pipette with an ejection mechanism for pipette tips, which has a hand-operated lever that can be pivoted about a pivot axis perpendicular to the pipette axis on one side. When the user presses a push button on the side of the one-sided lever opposite the pivot axis, the actuating force is transmitted to the ejector by means of straight contact surfaces on the underside of the lever via an intermediate transmission means.

Proceeding from this, the invention is based on the object of providing a pipette which manages with a small structural volume and in which the ejection of a pipette tip requires little effort. In addition, the pipette should be suitable for securely attaching a pipette tip to the peg with little effort, so that a pipette tip is prevented from being pushed off the attachment when pipetting highly viscous liquids and when pipetting quickly.

• ein stangenförmiges Pipettengehäuse,
• einen Zapfen am unteren Ende des Pipettengehäuses zum Halten einer Pipettenspitze, der Mittel zum formschlüssigen Verbinden mit einer Pipettenspitze aufweist, sodass eine Pipettenspitze unter elastischer Verengung des Zapfens und/oder unter elastischer Aufweitung der Pipettenspitze vor ihrer formschlüssigen Verbindung mit dem Zapfen auf den Zapfen aufschiebbar ist,
• eine Antriebseinrichtung zum Verlagern eines Verdrängungselements zum Einsaugen einer flüssigen Probe in eine auf dem Zapfen gehaltene Pipettenspitze und Ausstoßen der Probe aus der Pipettenspitze,
• eine Abwurfeinrichtung umfassend einen drehbar im Pipettengehäuse gelagerten Kurventräger, ein an einer ersten Kurve am Umfang des Kurventrägers geführtes erstes Abtastelement an einer Abwurfstange, die in Längsrichtung des Zapfens verlagerbar im Pipettengehäuse geführt ist und ein mit dem Kurventräger verbundenes, vom Pipettengehäuse vorstehendes und relativ zum Pipettengehäuse drehbares Bedienelement, wobei die Abwurfeinrichtung ausgebildet ist, durch Drehen des Bedienelementes aus einer Ausgangsstellung den Kurventräger zu drehen, wobei die erste Kurve das erste Abtastelement so nach unten verlagert, dass die Abwurfstange eine auf dem Zapfen gehaltene Pipettenspitze vom Zapfen abdrückt,
• eine Sperreinrichtung umfassend eine konzentrisch zum Zapfen angeordnete Sperrhülse und eine von der Sperrhülse nach oben vorstehende Steuerstange in Richtung des Zapfens im Pipettengehäuse verlagerbar geführt ist,
• wobei von der Steuerstange ein zweites Abtastelement vorsteht und der Kurventräger am Umfang eine zweite Kurve aufweist, an der das zweite Abtastelement geführt ist, die so ausgebildet ist, dass bei Anordnung des Bedienelements in der Ausgangsstellung die Sperrhülse in einer Sperrstellung den Zapfen innen begrenzt und/oder die Pipettenspitze außen begrenzt, wodurch die Sperrhülse ein Ablösen einer formschlüssig mit dem Zapfen verbundenen Pipettenspitze vom Zapfen verhindert, und durch Drehen des Bedienelements die Sperrhülse nach oben verlagerbar ist, sodass der Zapfen und/oder die Pipettenspitze zumindest teilweise freigegeben wird und die Abwurfstange die Pipettenspitze vom Zapfen abdrückt.

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

• a rod-shaped pipette housing,
• a pin at the lower end of the pipette housing for holding a pipette tip, which has means for positive connection with a pipette tip, so that a pipette tip can be pushed onto the pin with elastic narrowing of the pin and / or with elastic expansion of the pipette tip before its positive connection with the pin ,
• a drive device for displacing a displacement element for sucking in a liquid sample into a pipette tip held on the pin and ejecting the sample from the pipette tip,
• an ejection device comprising a cam support rotatably mounted in the pipette housing, a first scanning element guided on a first curve on the circumference of the cam support, which is guided in the pipette housing so as to be displaceable in the longitudinal direction of the pin, and a cam support connected to the cam support, protruding from the pipette housing and relative to the pipette housing rotatable operating element, wherein the ejection device is designed to rotate the cam carrier by rotating the operating element from an initial position, the first curve displacing the first sensing element downward so that the ejection rod pushes a pipette tip held on the pin from the pin,
• a locking device comprising a locking sleeve arranged concentrically to the pin and a control rod projecting upward from the locking sleeve in the direction of the pin in the pipette housing,
• wherein a second scanning element protrudes from the control rod and the cam carrier has a second curve on the circumference, on which the second scanning element is guided, which is designed so that when the operating element is arranged in the starting position, the locking sleeve limits the pin inside in a locking position and / or the pipette tip is limited on the outside, whereby the locking sleeve a detachment of a form-fitting with the Prevents the pin connected pipette tip from the pin, and the locking sleeve can be displaced upwards by rotating the operating element, so that the pin and / or the pipette tip is at least partially released and the ejector rod pushes the pipette tip off the pin.

The cam carrier can be rotated in the pipette housing and is mounted in the pipette housing so that it cannot be displaced in the longitudinal direction of the pin. The first sensing element is guided on a first curve on the circumference of the curve carrier. Furthermore, the first scanning element is arranged on a release rod which is guided in the housing such that it can be displaced in the longitudinal direction of the pin. As a result, a rotary movement of the cam carrier is converted into a linear movement of the ejector rod. The rotary movement is generated by an operating element which protrudes from the pipette housing and is rotatable relative to the pipette housing and which is connected to the cam carrier. The operating element protruding from the pipette housing can be operated manually by the user. Thus, by manually rotating the operating element, its axis of rotation, preferably by less than 360 ° (hereinafter also referred to as "pivoting"), the ejection rod in the pipette housing can be displaced in the longitudinal direction of the pin. When it is shifted downwards, the ejector rod pushes a pipette tip held on the pin from the pin. For this purpose, the lower end of the ejection rod can preferably be pressed against the upper side of the pipette tip, preferably against the upper side of a piston rod of a syringe piston or against the upper side of a collar of the pipette tip. Thus, the pipette tip can be ejected from the pipette by manually turning the operating element. Furthermore, the course of the curve on the curve carrier can ensure that the force for actuating the operating element is less than the force required to eject the pipette tip. In addition, a rotatably mounted curve support can be accommodated in the housing to save space. In particular, the cam carrier can be designed and arranged in such a way that at least part of the drive device is arranged within the cam carrier in a space-saving manner. This allows the overall volume of the pipette to be reduced.

According to one embodiment of the invention, the ejection device is designed so that the cam carrier is only partially rotatable around its axis of rotation (hereinafter also referred to as "pivotable"), ie by an angle of less than 360 °, preferably less than 180 ° preferably less than 90 ° in order to push the pipette tip off the spigot. This can be achieved in that the first curve on the circumference of the curve carrier extends only over a corresponding angular range of less than 360 °, and / or or limit stops due to the movement of the curve carrier and / or the operating element. However, the invention also includes embodiments in which the cam carrier can be rotated completely simply, several times or as often as desired about its axis of rotation in order to push the pipette tip off the spigot.

According to the invention, the pin has means for positive connection with a pipette tip, so that a pipette tip can be pushed onto the pin with elastic narrowing of the pin and / or with elastic expansion of the pipette tip before its positive connection with the pin, a locking device comprising one concentric to the pin arranged locking sleeve and a control rod protruding upward from the locking sleeve in the direction of the pin in the pipette housing, a second scanning element protrudes from the control rod and the cam support has a second curve on the circumference, on which the second scanning element is guided, which is designed in this way is that when the control element is arranged in the starting position, the locking sleeve in a locking position limits the inside of the pin and / or limits the pipette tip on the outside, whereby the locking sleeve prevents a pipette tip connected to the pin from being detached from the pin, and by rotating the operating element, the locking sleeve can be displaced upwards so that the pin and / or the pipette tip is at least partially released and the ejection rod pushes the pipette tip off the pin.

In this embodiment, the forces for connecting the pipette tip to the spigot and for releasing the pipette tip from the spigot can be reduced and the pipette tip can still be held sufficiently firmly on the spigot so that it is not detached from the spigot when pipetting highly viscous liquids and when pipetting quickly. The connection of the pipette tip to the peg is facilitated by the fact that the peg is elastically narrowed by pushing on the pipette tip and / or the pipette tip can be elastically widened by the penetration of the peg. The elastic narrowing and / or widening is brought about by the force acting between the means for positively connecting the pipette tip and the pin when it is pushed open. The elastic narrowing and / or elastic widening is completely or partially reversed when the means for positively connecting the pipette tip reach the means for positively connecting the peg when it is pushed on and the pipette tip enters into the interlocking connection with the peg. The at least one locking sleeve is then moved into the locking position. This secures the pipette tip on the peg, since the locking sleeve in the locked position prevents the peg from being elastically narrowed and / or the pipette tip being elastically widened, which is necessary to break the positive connection between the peg and the pipette tip. To eject the pipette tip from the pipette, the locking sleeve is removed from the locking position, so that it at least partially releases the peg and / or the pipette tip and the peg is elastically narrowed and / or the pipette tip can be elastically expanded. As a result, the positive connection can be broken with little effort and the pipette tip can be detached from the pin. The displacement of the locking sleeve is also controlled by the cam carrier, which has a second cam for this purpose. The shape of the second curve and its position relative to the first curve on the curve support can ensure that the locking sleeve is removed from the locking position in good time before the ejector rod presses against the pipette tip.

For the elastic constriction, the pin can have at least one slot running in the longitudinal direction. Here, the pin can consist of a hard-elastic or soft-elastic material, for example a metal or a plastic. A pin made from a soft elastic material, for example from silicone rubber, a thermoplastic elastomer or rubber, can have sufficient elasticity for the elastic constriction even without a slot. For the elastic expansion, the pipette tip can have at least one slot running in the longitudinal direction at the upper end. The pipette tip can consist of a hard-elastic plastic, for example polypropylene or polyethylene, or a soft-elastic plastic. It is also possible to manufacture a pipette tip at least at the upper end from a soft elastic material, for example from silicone rubber, a thermoplastic elastomer or from rubber, so that it has sufficient elasticity for elastic expansion even without a slot. The pipette tip can be manufactured from several materials by multi-component injection molding. The different materials can be physically and / or chemically bonded to one another. In particular, they can be positively and / or cohesively connected to one another (e.g. by gluing or welding). The locking sleeve is designed in such a way that it does not deform when loaded with a radial force which is suitable for elastically narrowing the pin and / or elastically expanding the pipette tip. The locking sleeve consists e.g. of a metal or a hard-elastic or rigid plastic.

According to a further embodiment of the invention, the cam carrier is a rotary sleeve, i.e. a rotatably mounted sleeve. The design as a rotating sleeve enables a particularly space-saving accommodation of at least part of the drive device within the curve support.

According to a further embodiment, the cam carrier has an axis of rotation extending in the longitudinal direction of the pin. This is beneficial for a space-saving Accommodation of the curve support. This can for example be arranged in a space-saving manner above the drive device in the rod-shaped pipette housing. According to a particularly space-saving embodiment, the cam carrier is a rotary sleeve with an axis of rotation extending in the direction of the pin and at least part of the drive device is arranged within the rotary sleeve. According to another embodiment, the cam carrier has an axis of rotation extending perpendicular to the longitudinal direction of the pin.

According to a further embodiment, the longitudinal direction of the pin is at the same time the longitudinal direction of the rod-shaped pipette housing or essentially corresponds to it. The longitudinal direction of the peg is the direction in which a pipette tip can be pushed onto the peg and detached from the peg. The longitudinal direction of the pipette housing is its main direction of expansion.

According to a further embodiment, the first curve and / or the second curve is arranged on the outer circumference of the curve carrier. This is the case, for example, when the cam carrier is designed as a solid cylinder or as a rotating sleeve. According to another embodiment, the cam carrier is a rotary sleeve and the first curve and / or the second curve is arranged on the inner circumference of the cam carrier.

According to a further embodiment, the first curve has symmetrically arranged sections on both sides of a high point and / or the second curve on both sides of a low point in which the first and / or the second scanning element is positioned in the starting position, so that by rotating the operating element from the starting position to the pipette tip can be pushed off the spigot in different directions. This enables the user to select the direction of rotation of the operating element for ejecting the pipette tip.

According to a further embodiment, the first curve is a first groove and / or the second curve is a second groove. In this way, a particularly safe and energy-saving guidance of the first scanning element and / or the second scanning element on the cam carrier is achieved. In another embodiment, the first curve and / or the second curve is formed on an end face of the curve carrier, it being possible for the respective scanning elements to be pressed against the curve by a spring device.

According to a further embodiment, the first curve has the shape of an inverted, ie upside-down, V or U or Y and / or the second curve has the shape of an upright V or U. These embodiments allow the pipette tip to be ejected by optionally rotating the Control element in one of two different directions.

According to a further embodiment, the first scanning element is a first pin, a rotatably mounted first ball, roller or sleeve or a first roller bearing mounted on a first pin and / or the second scanning element is a second pin, a rotatably mounted second ball, roller or sleeve or a second roller bearing mounted on a second journal. The design as a pin is structurally particularly simple. Versions with a rotatably mounted element or a roller bearing are particularly low-friction and can reduce the effort required for actuation and wear.

According to a further embodiment, the operating element for actuating the ejection device is at the same time an operating element for driving the drive device. This enables the pipette to be operated with one hand without changing the grip. According to another embodiment, the pipette has an operating element for actuating the ejection device and an additional operating element, which is different from this operating element, for driving the drive device.

According to a further embodiment, the operating element for driving the drive device can be displaced in the longitudinal direction of the pin. In the case of a cam support which has an axis of rotation extending in the longitudinal direction of the peg, the pipetting can be controlled by shifting the operating element in the longitudinal direction of the peg and the ejection of the pipette tip can be controlled by rotating the operating element about the axis of rotation.

According to a further embodiment, the control element is non-rotatably connected, i.e. fixed in rotation, to the cam carrier, so that the cam carrier exactly follows the rotation of the control element. According to another embodiment, the operating element is connected to the cam carrier via a gear mechanism (e.g. a gear drive or a traction mechanism).

According to a further embodiment, the drive device has a transmission mechanism which is designed to shift a drive element of the drive device alternately downwards and upwards during successive downward displacements of the operating element, between which the operating element is displaced upward. This type of embodiment is advantageous in the case of an operating element which can be displaced in the longitudinal direction of the pin in order to drive the drive device. When the control element is first shifted downwards, the drive element is shifted from an upper position down to a lower position, when the control element is subsequently shifted upwards, the drive element maintains its lower position and when the control element is subsequently shifted downwards, this is Drive element moved back to the upper position. This sequence can be repeated as often as you like.

According to a further embodiment, the transmission mechanism is at least partially arranged within a rotating sleeve. This enables space-saving accommodation.

According to a further embodiment, the rotary sleeve has recesses parallel to the axis of rotation on two opposite sides, the operating element comprises a laterally protruding operating lever on a carrier plate, the carrier plate has a curved slot which is designed to receive a sector of the sleeve and along this sector to be displaced in the longitudinal direction of the pin and the carrier plate is connected to a drive of the transmission mechanism via a transmission element. According to a further embodiment, the operating element can be displaced within a first housing slot extending in the transverse direction of the pipette housing and within a second housing slot extending downwards from the center of the first housing slot in the longitudinal direction of the pipette housing, so that in the starting position it is at the upper end of the second housing slot in the first housing slot is pivotable in opposite directions and is linearly displaceable in the second housing slot.

In this embodiment, the operating element is both non-rotatably connected to the rotary sleeve and also displaceable in the longitudinal direction of the pin. This is achieved by guiding the operating element on the curved slot on a sector of the rotating sleeve. In addition, the movements of the operating element around the axis of rotation of the rotary sleeve can be guided through the first housing slot and in the longitudinal direction of the pin through the second housing slot.

According to a further embodiment, the rotary sleeve has a support ring at the upper end, which connects the two sectors of the sleeve to one another. The sleeve is stabilized by the support ring. Furthermore, the support ring can prevent the operating element from being pulled off the sector of the sleeve.

According to a further embodiment, the first curve and / or the second sleeve is arranged below the cutouts on the circumference of the rotating sleeve.

According to a further embodiment, the pipette housing and the cam carrier have a magnet arrangement and / or a spring device which is designed to automatically move the operating element into the starting position. The magnet arrangement comprises, for example, two permanent magnets or a permanent magnet and a ferromagnetic component. The permanent magnets or the ferromagnetic component are held on the pipette housing and on the cam carrier in such a way that they automatically move the operating element into the starting position when they come closer to one another. This can also be achieved by a spring device which is pretensioned when the cam carrier is rotated out of the starting position and strives to rotate the cam carrier back into the starting position.

According to a further embodiment, a third scanning element is provided concentrically to the pin, which is supported by a spring on the pipette housing and can be preloaded by sliding a pipette tip onto the pin, so that when a pipette tip is detached from the pin, the spring relaxes and the third scanning element releases the Pipette tip supported by the peg. The third scanning element can in particular be a scanning element of a scanning device for scanning the collar of a pipette tip, as in FIG EP 18 168 763.3 described. In this respect, reference is made to the above patent application, the content of which is hereby incorporated into the above application.

According to a further embodiment, the pipette is a positive displacement pipette or an air-cushion pipette.

According to a further embodiment (i.) When designed as a positive displacement pipette, the ejection rod is arranged within an axial bore in a lifting rod for displacing a tip piston in the pipette tip and with the lower end above a receptacle of the lifting rod for the lower end of the tip piston on the pin held and with the tip piston in a through hole of the pin engaging pipette tip and (ii.) when designed as an air-cushion pipette in the pipette housing a displacement device with a displacement element displaceable by a drive element of the drive device, which is connected to a through hole of the pin, and the lower end of the ejection rod is laterally next to the Cones arranged. According to the first variant (i.) The ejection of a pipette tip including a tip piston is achieved by a positive displacement pipette and in the second variant (ii.) The ejection of a pipette tip is achieved by an air-cushion pipette.

According to a further embodiment, the pipette is a single-channel pipette or a multi-channel pipette. In the case of a multi-channel pipette, the cam carrier can control the ejector rod of a multi-channel ejector.

Fig. 1

eine Direktverdrängerpipette mit auf dem Zapfen aufgesteckter Pipettenspitze teilweise geschnitten in einer Perspektivansicht;

Fig. 2

geschlitzter Zapfen mit innen anliegender Sperrhülse derselben Direktverdrängerpipette mit aufgesteckter Pipettenspitze in einer vergrößerten Perspektivansicht;

Fig. 3

dieselbe Anordnung in einer Seitenansicht;

Fig. 4

dieselbe Anordnung in einem Längsschnitt;

Fig. 5

Direktverdrängerpipette von Fig. 1 in einem Sprengbild;

Fig. 6

Direktverdrängerpipette von Fig. 1 in einem Sprengbild ohne Pipettengehäuse;

Fig. 7

Drehhülse mit der Abwurfstange und der Sperrhülse derselben Direktverdrängerpipette in der Ausgangsstellung in einer Perspektivansicht;

Fig. 8

dieselbe Direktverdrängerpipette in der Ausgangsstellung teilweise geschnitten in einer Seitenansicht;

Fig. 9

dieselbe Direktverdrängerpipette beim Pipettieren teilweise geschnitten in einer Seitenansicht;

Fig. 10

dieselbe Direktverdrängerpipette beim Abwerfen teilweise geschnitten in einer Seitenansicht;

Fig. 11

geschlitzte Pipettenspitze auf einem Zapfen einer anderen Direktverdrängerpipette mit einer außen an der Pipettenspitze anliegenden Sperrhülse in einem Längsschnitt.

The invention is explained below with reference to the attached drawings of an exemplary embodiment. In the drawings show:

Fig. 1

a positive displacement pipette with the pipette tip attached to the spigot, partially sectioned in a perspective view;

Fig. 2

slotted pin with locking sleeve lying on the inside of the same positive displacement pipette with attached pipette tip in an enlarged perspective view;

Fig. 3

the same arrangement in a side view;

Fig. 4

the same arrangement in a longitudinal section;

Fig. 5

Positive displacement pipette from Fig. 1 in an exploded view;

Fig. 6

Positive displacement pipette from Fig. 1 in an exploded view without pipette housing;

Fig. 7

Rotary sleeve with the ejection rod and the locking sleeve of the same positive displacement pipette in the starting position in a perspective view;

Fig. 8

the same positive displacement pipette in the starting position partially cut in a side view;

Fig. 9

the same positive displacement pipette during pipetting, partially sectioned in a side view;

Fig. 10

the same positive displacement pipette when ejected, partially cut in a side view;

Fig. 11

Slotted pipette tip on a pin of another positive displacement pipette with a locking sleeve resting on the outside of the pipette tip in a longitudinal section.

In the present application, the terms "above" and "below" as well as "vertical" and "horizontal" and terms derived therefrom, such as "above" and "below", "upright" and "upside down" and " one above the other "refers to an arrangement of the pipette in which the pin is oriented vertically and is located at the downward-facing end of the pipette housing. With regard to the pipette tip, these details relate to a vertical alignment of the central axis of the pipette tip, the tip opening being arranged at the bottom and the plug-on opening being arranged at the top.

According to Fig. 1 If a pipette 1 designed as a positive displacement pipette has a rod-shaped (for example cylindrical) pipette housing 2. A hollow cylindrical shaft 3 projects downward from the lower end of the pipette housing 2. A pin 4 projects downward from the lower end of the shaft 3, which according to FIG Fig. 1 and 4th has a through hole 5 with a through hole at the lower end. The inside diameter of the through hole 5 is smaller than the inside diameter of the shaft 3.

The pin 4 has an upper pin section 6 with the shape of a hollow cylinder and below it a lower pin section 7 with the shape of a hollow cone on. An annular groove 8 runs around on the outer circumference of the pin 4 between the upper pin section 6 and the lower pin section 7.

The upper pin section 6, the annular groove 8 and the lower pin section 7 form the first means for the positive connection 9 of the pipette with a pipette tip.

Furthermore, the pin 4 has two slots 10, 11 running in its longitudinal direction, which are diametrically opposite one another. The slots 10, 11 extend from the lower end over the entire length of the pin 4.

According to Fig. 1 , 5 and 6th a drive device 12 is present in the pipette housing 2, which comprises a transmission element 13 in the form of a transmission rod 14, a transmission mechanism 15 and a drive element 16 in the form of a lifting rod 17. Furthermore, the drive device 12 comprises an operating element 18 in the form of an operating lever 19, which is firmly connected to a carrier plate 21 via a web 20.

According to Fig. 6 the carrier plate 21 has an oval shape with a wide rounded end and a narrow rounded end, the operating lever 19 protruding from the edge of the narrow rounded end. In addition to this edge, the carrier plate 21 has a first curved slot 22 which runs approximately parallel to the contour of the narrow rounded end. Furthermore, the carrier plate 21 has a rectangular first edge recess 23 in the middle of the first curved slot 22 on the side of the narrow rounded end.

According to Fig. 1 and 5 the lifting rod 17 is guided into the shaft 3 and the pin 4 from above. According to Fig. 4 it is hollow and provided with a longitudinal slot 24 starting from the lower end. Due to the longitudinal slot 24, the lifting rod 17 has a C-shaped cross section. Its lower end forms a receptacle 25 for the upper end of a piston rod.

The transmission mechanism 15 is designed such that when the operating lever 19 is displaced downward one after the other, between which the operating lever 19 is displaced upward, the lifting rod 17 is alternately displaced downward and upward. As a result, the lifting rod 17 can be shifted from an upper position to a lower position by pressing the operating lever 19 downward, the lifting rod 17 maintains the lower position during the subsequent upward displacement of the operating lever 19 and the lifting rod 17 is activated by a subsequent pressing of the Operating lever 19 shifted downwards again upwards. This can be repeated as often as you like.

According to Fig. 1 , 5 and 6th the pipette 1 is provided with an ejection device 26. This comprises a cam carrier 27 which is rotatably mounted in the pipette housing 2 and is designed as a hollow cylindrical rotating sleeve 28. The rotating sleeve 28 is rotatably mounted, for example, with its outer circumference on the inner circumference of the pipette housing 2 and supported at the upper and lower end between shoulders of steps on the inner circumference of the pipette housing 2, so that it cannot be displaced in the axial direction in the pipette housing 2. The axis of rotation of the rotary sleeve 28 coincides with the longitudinal axis of the pipette housing 2 and the longitudinal axis of the pin 4.

The rotating sleeve 28 has on two diametrically opposite sides to its axis of rotation parallel recesses 29, 30 which extend from the upper edge of the rotating sleeve 28 and end at a distance from its lower edge. Below the recesses, the rotary sleeve 28 thus consists of an annular base 31 and above it consists of two sectors 32, 33 of a circular ring that are diametrically opposite one another and which laterally delimit the two recesses 29, 30.

A first curve 34 and a second curve 35 are arranged on the outer circumference of the circular base 31 of the rotary sleeve 28. The first curve 34 is designed as a first groove 36 in the form of an inverted (upside-down) Y. The vertical part 37 of the Y extends far up on a sector 32 to just short of the upper edge of the sector 32. The second curve 35 is a second groove 38 on the outer circumference of the base 31 of the rotating sleeve 28 with the shape of an upright standing V. The first curve 34 and the second curve 35 are arranged offset from one another by 90 ° on the circumference of the rotary sleeve. The first curve 34 and the second curve 35 each extend over an angular range of less than 90 ° over the circumference of the rotary sleeve 28.

According to Fig. 1 , 5 and 6th the ejection device 26 comprises a ejection rod 39 which comprises a strip-shaped upper ejection rod part 40 and a cylindrical lower ejection rod part 41. The upper and lower ejection rod parts 40, 41 are arranged parallel to one another and laterally offset from one another. The lower end of the upper ejecting rod part 40 is connected to the upper end of the lower ejecting rod part 41 via a strip-shaped connecting rod part 42 inclined at an angle to the two ejecting rod parts. A first scanning element 43 in the form of a first guide pin 44 projects perpendicularly from the inside of the upper ejection rod part 40. The ejector rod 39 is preferably made in one piece, for example from a rigid plastic.

According to Fig. 1 , 4th and 7th the ejection rod 39 is guided with the guide pin 44 in the first groove 36, the connecting rod part 42 extends through the longitudinal slot 24 of the lifting rod 17 and extends with the lower ejection rod part 41 within the lifting rod 17 to just before the lower end of the same.

According to Fig. 1 , 4th , 5 and 6th the pipette 1 comprises a locking device 45 which comprises a locking sleeve 46 and a strip-shaped control rod 47 parallel thereto. The upper end of the locking sleeve 46 and the lower end of the control rod 47 are via a second connecting rod part 48 connected to one another, which is inclined at an angle to the locking sleeve 46 and to the control rod 47. A second scanning element 49 in the form of a second guide pin 49.1 protrudes from the inside of the control rod 47.

According to Fig. 1 and 7th the second guide pin 49.1 is guided in the second groove 38. According to Fig. 1 and 4th the locking sleeve 46 is inserted into the shaft 3 from above and rests against the inside of the pin 4. The lifting rod 17 and the ejection rod 39 are inserted into the locking sleeve 46 from above.

The operating element 19 is pushed with the first curved slot 22 onto the sector 32 of the rotary sleeve 28 on which the first groove 36 extends. According to Fig. 1 , 6th and 7th the rotary sleeve 28 is connected at the top to a support ring 50 which bridges the two sectors 32, 33 and stabilizes the rotary sleeve 28. The support ring 50 has on the outer edge a downwardly protruding jacket 51 which laterally surrounds the two sectors 32, 33 at the outer edges. It also has a second curved slot 52 which receives the upper edge of the sector 33 which is not provided with a groove 36,38. On the diametrically opposite side of the jacket 51 there is a downwardly opened rectangular second edge recess 52.1 which is designed to accommodate the web 20 between the operating lever 19 and the carrier plate 21.

The support ring 50 is connected to the rotating sleeve 28, for example by gluing.

The rotating sleeve 28 and the locking sleeve 46 as well as the operating element 18 are made, for example, of one or more rigid plastics and / or of metal. The rotary sleeve 28, the support ring 50, the operating element 18 and / or the locking sleeve 46 are preferably each formed in one piece. An operating button of the operating element 18 can also be made of an elastic or soft elastic plastic or rubber.

The operating lever 19 protrudes from the pipette housing 2 through a first housing slot running transversely to the longitudinal axis of the pipette housing 2 and extending over part of the circumference of the pipette housing 2, so that it can be operated from the outside. The first housing slot is connected in the middle to a second housing slot running in the longitudinal direction of the pipette housing 2.

The operating lever 19 can be displaced downward from the support ring 50 along the second housing slot against the action of a spring device, sliding with the first curved slot 22 on the sector 32 of the rotating sleeve 28. After relief, the spring device automatically moves the operating lever 19 back upwards.

A sleeve-shaped third scanning element 53 is guided on the outside of the shaft 3. A spring device in the form of a helical spring 54 guided on the shaft is supported on the underside of the pipette housing 2 and on the upper side of the third scanning element 53. The sensing element 53 is pressed from above against a stop element on the shaft 3 or pin 4 by the helical spring 54.

On the top of the pipette housing 2 there is an adjusting knob 55 for adjusting a dosing volume. The dosing volume can be set by turning the adjusting knob 55. A counter 56 arranged underneath in the pipette housing 2 shows the respectively set dosing volume. The setting knob 55 and / or the counter 56 is coupled to the transmission mechanism 15. The transmission mechanism 15 is designed to change the stroke of the lifting rod 17, which is carried out by shifting the operating element 18 downwards, in accordance with the metering volume set in each case.

According to Figs. 1 to 4 a pipette tip 57 is attached to the pin 4. The pipette tip 57 comprises a tubular body 58 which has a tip opening 59 at the lower end and a collar 61 having an attachment opening 60 at the upper end At the end and on the inner circumference of the collar 61 has a seat area 62 for clamping onto the pin 4. The seat area 62 has a complementary contour to the pin 4, the bottom a conical lower seat section 63 for receiving the conical lower pin section 7, above a circumferential bead 64 for engaging in the annular groove 8 of the pin 4 and above a cylindrical upper seat section 65 for receiving the having cylindrical upper pin portion 6. The lower seat section 63, the bead 64 and the upper seat section 65 form second means for the form-fitting connection 66 of the pipette tip 57 with the pipette 1.

Below the seat area 62, the tubular body 58 has a cylindrical piston running area 67. Below that, the tubular body 58 has a downwardly tapering tip section 68 with the shape of a hollow truncated cone. The tip portion 68 is in Fig. 4 shown and omitted in the remaining drawings for the sake of simplicity. A tip piston 69 is inserted in the tubular body 58. This comprises a piston 70 which is guided in the piston barrel region 67. A piston rod 71, which has a smaller diameter than the piston 70, projects upward from the piston 70. The piston rod 71 has a piston head 72 at the upper end. The piston head 72 is according to FIG Fig. 4 pressed down into the receptacle 25 of the reciprocating piston 17.

The pipette 1 can be used as follows:
According to Fig. 1 and 8th a pipette tip 57 is held on the pipette 1 in an initial state. The seat area 62 is connected to the pin 4 in a form-fitting manner, in particular by the bead 64 engaging in the annular groove 8. The actuating element 18 is in the starting position at the upper end of the second housing slot, in which the first housing slot can be rotated in both directions. The maximum angle of rotation is limited by the extent of the first and second grooves 36, 38 in the circumferential direction or the first housing slot, depending on which extension is smaller.

The locking sleeve 46 is according to Fig. 4 arranged in the lowest position, so that it prevents unintentional detachment of the pipette tip 57 from the pin 4. A radial narrowing of the pin 4, which the locking sleeve 46 does not allow in this position, would namely be necessary for the release of the form-fitting connection. In deviation from Fig. 4 In the starting position, the tip piston 69 is not yet pressed into the receptacle 25 of the lifting rod 17 with the piston head 72.

To connect the tip piston 69 to the lifting rod 17, the operating element 18 is pressed down. This movement is transmitted from the transmission mechanism 15 to the lifting rod 17, so that the latter is pressed with the receptacle 25 onto the piston head 72. This is in Fig. 4 shown.

After relief, the operating element 18 is returned to its starting position by a spring device Fig. 8 relocated. The lifting rod 17 and the tip piston 69 maintain the positions shown in FIG Fig. 4 at.

For the uptake of liquid, the pipette 1 with the lower end of the pipette tip 57 held on it is immersed in a liquid. Thereafter, the operating element 18 is pressed down again. This movement is converted by the transmission device 15 into a lifting movement of the lifting rod 17. As a result, the tip piston 69 is displaced upward. Here, the piston head 72 takes the ejector rod 39 with it, so that the first guide pin 44 slides upward in the vertical part 37 of the Y-shaped first groove 36. Meanwhile, the locking sleeve 46 maintains its position. This is in Fig. 9 shown.

When the operating element 18 has carried out the set stroke, the pipette tip 57 is filled with a certain amount of liquid. Then the control element 18 relieved and shifted back upwards by the spring device until it rests on the support ring 50. In order to dispense this amount of liquid, the pipette 1 with the pipette tip 57 can be aligned with another vessel. By pressing the operating element 18 downwards again, the lifting rod 17 is shifted downwards and the amount of liquid is dispensed. Here, the first guide pin 44 slides down to the junction of the first groove 36.

The stroke performed by the operating element 18 when the liquid is taken up and dispensed depends on the set amount of liquid.

The uptake and release of liquid can be carried out several times.

To eject the pipette tip 57, the operating lever 18 is pivoted to the right or to the left in the starting position. This rotates the rotary sleeve 28 so that the second groove 38 displaces the second guide pin 49.1 and thus the locking sleeve 46 upwards until the locking sleeve 46 has released the pin 4 to such an extent that it can be deformed radially inward. For this purpose, the locking sleeve 46 is preferably pulled out of the through hole 5. Furthermore, by rotating the rotary sleeve 28, the first guide pin 44 is displaced downward in one of the two lateral sections of the lower part of the first groove 36, so that the ejector rod 39 presses against the tip piston 69, which is supported at the bottom on the tip section 68. Here, the bead 64 exerts a radial force on the pin, so that it narrows and the positive connection between the pipette tip 57 and the pin 4 is broken. As a result, the pipette tip 57 is released from the pin 4. This is in Fig. 10 shown. The stripping of the pipette tip 57 from the pin 4 can also be assisted by the scanning element 53, which is pressed by the pretensioned helical spring 54 against the upper edge of the pipette tip 57.

When the used pipette tip 57 is detached from the pin 4, a new pipette tip 57 can be connected to the pin 4. For this purpose, the pipette 1 with the pin 4 can be inserted into the receiving opening 68 of a pipette tip 57 held ready in a carrier. Here, the scanning element 53 is displaced upwards and the helical spring 54 is pretensioned. Furthermore, the piston head 72 presses against the underside of the ejection rod 39, so that the first guide pin 44 slides as far as the first branch point of the first groove 36. Here, the rotary sleeve 28 is rotated in the pipette housing 2 until the operating element 18 is in the starting position. At the same time, the second guide pin 49.1 slides to the lowest point in the second groove 38. As a result, the locking sleeve 46 is in the locking position of Fig. 4 relocated, in which it prevents detachment of the pipette tip 57 from the pin 4.

The connection of the tip piston 69 to the lifting rod 17 and the pipetting can take place in the manner described above.

The embodiment of Fig. 1 differs from the one described above in that the locking sleeve 46 is pushed over the outer circumference of the collar 61 of the pipette tip 57 in the locking position. In this positive displacement pipette, pipette tips 57 are used which have at least one longitudinal slot extending from the upper end. The longitudinal slot enables the pipette tip 57 to be radially expanded in order to produce the form-fitting connection between the pipette tip 57 and the pin 4. The release of the positive connection is prevented when the locking sleeve 57 is in the locking position, as in FIG Fig. 11 shown. To detach the pipette tip 57 from the spigot 4, the locking sleeve 46 is displaced upward by means of the rotating sleeve 28, as in the previously described embodiment, and then the pipette tip 57 is detached from the spigot 4 by pressing against the top of the tip piston 69.

List of reference symbols:

1

pipette

2

Pipette housing

3

shaft

4th

Cones

5

Through hole

6th

upper journal section

7th

lower journal section

8th

Ring groove

9

first means for form-fitting connection

10

slot

11

slot

12th

Drive direction

13th

Transmission element

14th

Transmission rod

15th

Transmission mechanics

16

Drive element

17th

Lifting rod

18th

Control element

19th

Control lever

20th

web

21

Carrier plate

22nd

first curved slot

23

first edge recess

24

Longitudinal slot

25th

recording

26th

Discharge device

27

Curve beam

28

Rotating sleeve

29

Recess

30th

Recess

31

Base

32

sector

33

sector

34

first turn

35

second curve

36

first groove

37

vertical part

38

second groove

39

Drop bar

40

upper part of the ejector rod

41

lower part of the ejector bar

42

Connecting rod part

43

first sensing element

44

Guide pin

45

Locking device

46

Locking sleeve

47

Control rod

48

second connecting rod part

49

second scanning element 49.1 second guide pin

50

Support ring

51

coat

52

second curved slot

52.1

second edge recess

53

third sensing element

54

Coil spring

55

Adjustment knob

56

Counter

57

Pipette tip

58

body

59

Tip opening

60

Slip-on opening

61

collar

62

sitting area

63

lower seat section

64

bead

65

upper seat section

66

second means for form-fitting connection

67

Piston running area

68

Syringe section

69

Top piston

70

piston

71

Piston rod

72

Piston head

Claims (14)

1. A pipette for use with a pipette tip comprising:

   • a rod-shaped pipette housing (2),

   • a nipple (4) on the lower end of the pipette housing (2) for holding a pipette tip (57), which has means for the form-fit connection (9) to a pipette tip (57), so that a pipette tip (57) can be shoved onto the nipple (4) while elastic constriction of the nipple (4) and/or while elastically expanding the pipette tip (57) before its form-fit connection with the nipple (4),

   • a drive apparatus (12) to displace a displacement element (70) for aspirating a liquid specimen into a pipette tip (57) held on the nipple (4), and for ejecting the specimen from the pipette tip (57),

   • an ejection apparatus (18, 27, 39) comprising a curved support (27) that is rotatably mounted in the pipette housing (2), a first sensing element (43) on an ejection rod (39) that is guided on a first curve (36) on the perimeter of the curved support (27), said ejection rod being displaceably guided in the pipette housing (2) in the longitudinal direction of the nipple (4), and an operating element (18) connected to the curved support (27) that projects from the pipette housing (2) and can rotate relative to the pipette housing (2), wherein the ejection apparatus is designed to rotate the curved support (27) out of a start position by rotating the operating element (18), wherein the first curve (36) displaces the first sensing element (43) downward so that the ejection rod (39) presses a pipette tip (57) held on the nipple (4) off of the nipple (4),

   • a locking apparatus (45) comprising a locking sleeve (46) arranged concentric to the nipple and a control rod (47) projecting upward from the locking sleeve (46) are displaceably guided toward the nipple (4) in the pipette housing (2),

   • while a second sensing element (49) projects from the control rod (47), and the curved support (27) has a second curve (38) on the perimeter on which is guided the second sensing element (49) which is designed so that, when the operating element (18) is arranged in the start position, the locking sleeve (46) borders the nipple (4) on the inside when in a locked position, and/or borders the pipette tip (57) on the outside, whereby the locking sleeve (46) prevents a release from the nipple (4) of a pipette tip connected in a form-fit to the nipple (4), and the locking sleeve (46) is displaceable upward by rotating the operating element (18) so that the nipple (4) and/or the pipette tip (57) is at least partially released, and the ejection rod (39) pushes the pipette tip off of the nipple (4).
2. The pipette tip according to claim 1, wherein the curved support (27) is a rotating sleeve (28) with a rotational axis extending in the longitudinal direction of the nipple (4), and at least part of the drive apparatus (12) is arranged within the rotating sleeve (28).
3. The pipette according to claim 1 or 2, wherein the first curve (36) has symmetrically arranged sections on both sides of a high point, and/or the second curve has symmetrically arranged sections on both sides of a low point when the first and/or second sensing element (43, 49) is positioned in the start position so that the pipette tip (57) can be pressed off of the nipple (4) by rotating the operating element (18) from the start position in different directions.
4. The pipette according to one of claims 1 to34, wherein the first curve (34) is a first groove (36), and/or the second curve (35) is a second groove (38).
5. The pipette according to claim 3 and 4, wherein the first curve (34) has the shape of an inverted V, or U, or Y, and/or the second curve (35) has the shape of an upright V or U.
6. The pipette according to one of claims 1 to 5, wherein the first sensing element (43) and/or the second sensing element (49) has a guide pin (44, 49.1), a rotatably mounted ball, roller or sleeve, or a roller bearing mounted on a pin.
7. The pipette according to one of claims 1 to 6, wherein the operating element (18) for actuating the ejection apparatus (18, 27, 39) is simultaneously an operating element (18) for driving the drive apparatus (12).
8. The pipette according to one of claims 1 to 7, wherein the operating element (18) for driving the drive apparatus (12) can be displaced in the longitudinal direction of the nipple (4).
9. The pipette according to one of claims 1 to 8, wherein the drive apparatus (12) comprises a transmission mechanism (15) that is designed to displace a drive element (13) of the drive apparatus alternatingly downward and upward when the operating element (18) is sequentially displaced downward, between which the operating element (18) is displaced upward.
10. The pipette according to one of claims 32to 9, wherein the rotating sleeve (28) has parallel cutouts (29, 30) on two diametrically opposite sides parallel to the rotational axis, the operating element (18) comprises a laterally projecting operating lever (19) on a support plate (21), the support plate (21) has a curved slot (22) that is designed to accommodate a sector (32) of the rotating sleeve (28) and to be moved along this sector (32) in the longitudinal direction of the nipple (4), and the support plate (21) is connected via a transmission element (13) to the transmission mechanism (15).
11. The pipette according to claim 10, wherein the operating element (18) is displaceable within a first housing slot extended in the transverse direction and within a second housing slot starting from the middle of the first housing slot and extended in the longitudinal direction of the pipette housing (2) so that it can pivot in the first housing slot and can be moved in a straight line in the second housing slot.
12. The pipette according to claim 10 or 11, wherein the rotating sleeve (28) has a support ring (50) on the upper end that connects the two sectors (32, 33) of the rotating sleeve (28) to each other.
13. The pipette according to one of claims 1 to 12, wherein the pipette housing (2) and curved support (27) comprise a magnet assembly and/or a spring assembly that is designed to independently displace the operating element (18) into the start position.
14. The pipette according to one of claims 1 to 13, wherein there is a third sensing element (53) which is concentric with the nipple (4) and is braced against the pipette housing (2) via a spring (54) and can be pretensioned by shoving a pipette tip (57) onto the nipple (4) so that, when a pipette tip (57) is released from the nipple (4), the spring (54) relaxes, and the third sensing element (53) helps press the pipette tip (57) off of the nipple (4).

Images