PIPETTE FOR USE WITH A PIPETTE TIP

Description

[0001] The invention relates to a pipette for use with a pipette tip.

[0002] Pipettes are used primarily in scientific and industrial laboratories with medical, molecular biology, and pharmaceutical applications for dosing selected volumes of liquids. These liquids can 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).

[0003] Common pipettes for use with a pipette tip have a pipette housing in the form of an elongated hollow body with a stud (attachment) at the lower end for clamping a pipette tip. The stud is often conical, cylindrical, or partially conical and cylindrical 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 a plug-in opening at the upper end, through which the pipette tip can be clamped onto the stud. The liquid is drawn into and dispensed from the pipette tip. The aspiration and dispensing of the liquid is controlled by the pipette. Fixed-volume pipettes are used for pipetting constant volumes. Variable-volume pipettes allow the volume to be dispensed to be adjusted. A mechanical counter is used to display the set volume.To adjust the volume, the stroke of a drive unit is adjustable using an adjustment device connected to the counter. The pipette tip is removed from the attachment after use and can be replaced with a fresh pipette tip. This prevents cross-contamination during subsequent pipetting operations.

[0004] Air-cushion pipettes have a piston-cylinder or other displacement device in the pipette housing, which is connected via a channel to a through-hole in the stem. Pipette tips for air-cushion pipettes (air-cushion pipette tips) do not have an integrated piston. By moving the piston in the cylinder using the drive device, an air cushion is moved to suck liquid into and expel it from a pipette tip clamped onto the stem. Disadvantages of air-cushion pipettes include dispensing errors due to changes in the length of the air cushion caused by the weight of the sucked-in liquid, as well as changes in temperature, air pressure, and humidity. Contamination of the pipette by aerosols resulting from the sucked-in liquid can also be problematic.

[0005] Positive-displacement pipettes are used with pipette tips with an integrated piston (positive-displacement pipette tips). This type of pipette has a pin for attaching the pipette tip and a drive mechanism that can be coupled to the integrated piston (tip piston) to move the piston. The piston comes into direct contact with the liquid, eliminating the adverse effects of an air cushion. Positive-displacement pipettes are suitable, for example, for dispensing liquids with high vapor pressure, high viscosity, or high density, and for applications in molecular biology where aerosol-free dispensing is critical to avoid contamination.

[0006] Pipette tips for single use or reuse are made of plastic or glass.

[0007] EP 3 680 016 B1 describes a pipette comprising a pin at the lower end of a pipette housing for holding a pipette tip and a drive device for displacing a displacement element for sucking a liquid sample into a pipette tip held on the pin and ejecting the sample from the pipette tip. The pipette has an ejection device with an ejection rod for pushing a pipette tip, which is positively connected to the pin, off the pin, thereby elastically narrowing the pin and / or elastically expanding the pipette tip. The ejection device comprises a cam carrier (rotary sleeve) rotatably mounted in the pipette housing, having a first cam on the circumference, on which a first sensing element arranged on the ejection rod is guided in the pipette housing so as to be displaceable in the longitudinal direction of the pin.By rotating an operating element connected to the cam carrier, protruding outwards from the pipette housing and rotatable relative to the latter, the first scanning element can be moved downwards so that the ejection rod pushes a pipette tip off the pin.

[0008] The pipette also has a locking device with a locking sleeve to prevent a pipette tip, which is positively connected to the pin, from detaching from the pin. The locking device comprises a control rod projecting upward from the locking sleeve and having a second sensing element guided on a second curve on the circumference of the cam carrier. In a locked position, the locking sleeve limits the pin inside and / or the pipette tip outside and prevents elastic constriction of the pin and / or expansion of the pipette tip, thus preventing the pipette tip from detaching from the pin.

[0009] By turning the control element, the locking sleeve can be moved upwards and the ejector rod downwards at the same time, so that the locking sleeve releases the pin and / or the pipette tip and the ejector rod pushes the pipette tip off the pin.

[0010] The operating element can be displaced in the longitudinal direction of the pin to drive the drive device. The drive device has a transmission mechanism designed to alternately displace a drive element of the drive device downwards and upwards during successive downward displacements of the operating element, between which the operating element is displaced upwards. The operating element is guided on the rotating sleeve both in the longitudinal direction of the pin and is firmly connected to the rotating sleeve in rotation. This allows pipetting by displacing the operating element in the longitudinal direction of the pin and ejecting a pipette tip by rotating the operating element about the rotation axis of the rotating sleeve.

[0011] The operating element is connected to the outer end of an operating lever which projects out of the pipette housing through a slot arrangement. The slot arrangement comprises a first housing slot extending in the transverse direction of the pipette housing and a second housing slot extending downwards from the center of the first housing slot in the longitudinal direction of the pipette housing. As a result, the operating element can be pivoted horizontally along the first housing slot from an initial position at the upper end of the second housing slot and can be moved vertically along the second housing slot. The inner end of the operating lever is connected to a plate-shaped support via which the operating element is guided in the longitudinal direction of the pin on the rotating sleeve and is firmly connected to the rotating sleeve in terms of rotation.

[0012] The pipette is designed as a positive displacement pipette or an air-cushion pipette. In the positive displacement pipette design, the control element controls the movement of the tip piston and the ejection of the pipette tip. In the air-cushion pipette design, the control element controls the movement of a piston or other displacement element of a displacement device located in the pipette housing and the ejection of the pipette tip.

[0013] Solid, liquid, and gaseous substances can enter the pipette through the housing slots. This can lead to stiffness, corrosion, or destruction of lubricant and grease coatings, as well as other mechanical damage.

[0014] EP 2 656 915 B1 describes a pipette for actuating a syringe. The pipette has a rod-shaped housing with a receptacle at the lower end for inserting and holding a fastening section at the upper edge of a syringe cylinder. A receptacle body for inserting and holding a further fastening section of a syringe plunger is arranged in the housing. The pipette comprises means for displacing the receptacle body longitudinally within the housing. The displacing means comprise a lifting lever connected to the receptacle body via a connecting element that passes through a linear slot extending longitudinally of the housing.To prevent the viewer from viewing and the entry of contaminants into the housing, a cover strip covering the slot is held in the housing at two spaced-apart locations, and the connecting element has a channel through which the cover strip extends. Furthermore, the displacement means comprise a rack-and-pinion mechanism for stepwise piston advancement by means of a reciprocating dosing lever. By operating the lifting lever, liquid can be drawn into the syringe, and by operating the dosing lever, the liquid can be dispensed from the syringe in several steps.

[0015] In conventional pipettes with operating elements that protrude laterally from the pipette housing, the housing comprises at least two half-shells joined together lengthwise. During assembly, the pipette mechanism, including the drive, ejection, and, if applicable, displacement devices, is inserted into one half-shell, and an operating lever connected to the drive device is inserted from the inside through a slot or other housing opening. The pipette housing is then closed by joining the half-shells together, and an operating button is attached to the outer end of the operating lever. The construction of half-shells compromises the strength of the pipette housing. The pipette housing is easily deformed, particularly in the joining area of ​​the half-shells.

[0016] Based on this, the invention is based on the object of creating a pipette with a vertical and a horizontal housing slot for an operating lever, which is protected against the unwanted penetration of substances.

[0017] The object is achieved by a pipette according to claim 1. Advantageous embodiments of the pipette are specified in subclaims and in the following description.

[0018] According to claim 1, the pipette according to the invention for use with a pipette tip comprises: a pipette housing in the form of an elongated hollow body, a slot arrangement formed in a housing wall of the pipette housing with a vertical slot and a horizontal slot at the upper end of the vertical slot, an operating element arranged outside the pipette housing and displaceable along the slot arrangement, an operating lever extending through the slot arrangement and connected to the operating element at an outer end, and a support arranged in the pipette housing and connected to an inner end of the operating lever, characterized by a strip-shaped, vertical slot cover extending on the inside of the vertical slot, connected to the pipette housing at the lower end of the vertical slot, and extending to the upper end of the vertical slot, a strip-shaped, horizontal slot cover arranged on the inside of the horizontal slot,a vertical insertion slot for the operating lever extending from its lower edge and guided along the horizontal slot on a guide connected to the pipette housing, wherein the carrier has a vertical passage which receives the vertical slot cover when the operating lever engages in the vertical slot and which is released from the vertical slot cover when the operating lever engages in the horizontal slot and the insertion slot of the horizontal slot cover.

[0019] In the pipette according to the invention, the slot arrangement is covered by the vertical slot cover on the inside of the vertical slot and by the horizontal slot cover on the inside of the transverse slot. The support of the operating lever has a vertical passage that accommodates the vertical slot cover when the operating lever engages the vertical slot. When displaced along the vertical slot, the vertical passage is displaced on the vertical slot cover. The vertical slot cover ends at the upper end of the vertical slot. At the upper end of the vertical slot cover, the passage of the support is free from the vertical slot cover, so that the operating lever can be displaced within the horizontal slot.To ensure that the support with the passage on the vertical slot cover can be moved and released from the upper end of the vertical slot cover, the vertical slot cover is only connected to the pipette housing at the lower end of the vertical slot. The vertical slot cover can be attached directly to the pipette housing or to a chassis held in the pipette housing that carries components of a pipette mechanism. The horizontal slot cover has a vertical insertion slot at the lower edge into which the operating lever can be inserted so that the operating lever engages in the horizontal slot. When moved along the horizontal slot, the operating lever takes the horizontal slot cover with it because it rests against one edge of the vertical insertion slot and the horizontal slot cover is guided along the horizontal slot in a guide connected to the pipette housing.The guide can be formed directly on the pipette housing and / or attached to it and / or formed on and / or attached to a chassis held in the pipette housing, which carries components of the pipette mechanism. To move the operating lever from the horizontal slot into the vertical slot, the operating lever must be positioned above the vertical slot and the passage of the carrier above the vertical slot cover. In this case, the horizontal slot cover is aligned with the insertion slot on the vertical slot. Consequently, after moving the operating element along the vertical slot, the operating lever can be reinserted into the insertion slot to move the operating element along the horizontal slot. An unintentional displacement of the horizontal slot cover in the guide, e.g.due to vibrations, can be prevented by ensuring that the horizontal slot cover is guided in the guide with a certain amount of friction or is locked in its position above the vertical slot.

[0020] In the pipette according to the invention, the slot arrangement is covered by the vertical and horizontal slot covers in every position of the operating element. This prevents unwanted substances from entering the pipette and damaging the mechanism. Only in the area of ​​the vertical insertion slot is a small residual opening present when the operating lever is arranged in the vertical slot. Since the operating element can be moved along a vertical and a horizontal slot, it can be used for various functions. In particular, the aspiration and dispensing of liquids during pipetting or dispensing can be controlled by vertically moving the operating element, and the detachment of pipette tips from the stem can be controlled by horizontally moving the operating element.

[0021] According to one embodiment of the invention, a bracket is arranged in the pipette housing below the vertical slot, and the vertical slot cover is attached to the bracket. This ensures secure attachment of the vertical slot cover in the pipette housing without interfering with the movement of the operating lever. Furthermore, it enables simple installation of the vertical slot cover. For example, the vertical slot cover can be clamped or glued into a vertical pocket in the bracket. According to a further embodiment, the bracket protrudes inward from the pipette housing. In another embodiment, the bracket protrudes outward from a chassis that supports components of the pipette mechanism, and the vertical slot cover is connected to the pipette housing via the chassis.According to another embodiment, the vertical slot cover is detachably connected to the pipette body to facilitate maintenance and repair of the pipette.

[0022] According to a further embodiment, the horizontal slot runs on a circular arc, the horizontal slot cover is cylindrical and rotatably guided in the guide. This is advantageous for designs in which the pipette housing has the shape of a tube or is approximately tubular in the area of ​​the horizontal slot, the entire slot arrangement, or as a whole. According to a further embodiment, the carrier is mounted in the pipette housing so that it can rotate about a vertical axis. This allows the operating element to be pivoted parallel to the circular horizontal slot. The operating element can be relocated anywhere within a short distance of the horizontal slot, thus additionally covering it and further preventing the ingress of contamination.According to another embodiment, the horizontal slot is straight, whereby the support in the pipette housing can be displaced parallel to the horizontal slot or pivoted about a vertical axis.

[0023] According to a further embodiment, the horizontal slot cover is rotatably guided on a circular guide on the inside of the pipette housing. The circular guide can have one or more circular guide elements and / or guide elements arranged on a circular arc. The circular guide can be formed integrally with the pipette housing or chassis and / or be attached to the pipette housing or chassis.

[0024] According to a further embodiment, the guide has a cylindrical shell-shaped guide element at a distance from the inside of the pipette housing above the horizontal slot, and the horizontal slot cover engages from below into a gap between the pipette housing and the guide element and is guided therein. According to a further embodiment, below the horizontal slot, on both sides next to the vertical slot, there is at least one guide projection protruding from the inside of the pipette housing in a circular arc, on which the horizontal slot cover is guided. To simplify assembly, the horizontal slot cover is guided above the horizontal slot in the gap and below the horizontal slot on the guide projections.

[0025] According to a further embodiment, the slot arrangement is formed in a housing cover that covers a recess in the pipette housing. This can facilitate the assembly and disassembly of the slot covers. In addition, by removing the housing cover, the service department has the option of accessing parts of the pipette mechanism inside the pipette in order to inspect, clean and / or lubricate them, etc., without having to disassemble the entire pipette. According to a further embodiment, the vertical slot cover is attached and / or the horizontal slot cover is guided on the inside of the housing cover. This simplifies assembly and disassembly because the entire cover mechanism can be pre-assembled and disassembled in one assembly. This improves serviceability in the event of damage to the assembly. In particular, the assembly can be replaced by the service department at the customer's premises.

[0026] According to a further embodiment, the pipette has a device for connecting the housing cover and the pipette housing. According to a further embodiment, the connection device is a snap connection, a screw connection, or a combination of a plug connection with a snap connection or a screw connection.

[0027] According to a further embodiment, the housing cover is cylindrical shell-shaped and covers a recess in the pipette housing that is complementary to it.

[0028] According to another embodiment, the passage is formed by a vertical channel with a rectangular cross-section on a lateral edge of the support. This allows the vertical slot cover to be positioned closely against the inside of the pipette housing.

[0029] According to a further embodiment, the operating element for driving a drive device for a piston or another displacement element of a piston-cylinder device or another displacement device is displaceable along the vertical slot, and the operating element for driving an ejection device for a pipette tip is displaceable along the horizontal slot. The drive device and the ejection device can be designed, in particular, as described in EP 3 680 016 B1. In this regard, reference is made to EP 3 680 016 B1, the content of which is hereby incorporated into the present application.

[0030] According to a further embodiment, the drive device has a transmission mechanism which is designed to alternately move a drive element of the drive device downwards and upwards during successive downward displacements of the operating element, between which the operating element is displaced upwards.

[0031] According to a further embodiment, the transmission mechanism is controlled by the support of the operating element. According to a further embodiment, the support is a support plate that is applied to the upper side of a transmission element of the transmission device, as described in EP 3 831 487 A1, particularly in sections 61, 62, 100, and 101. In this regard, reference is made to EP 3 831 487 A1, the content of which is hereby incorporated into the present application.

[0032] According to a further embodiment, the transmission mechanism is designed as described in EP 3 928 868 A1. The carrier can be designed as a trigger, as described in EP 3 928 868 A1, particularly in sections 44, 45, and 55 to 57. In this regard, reference is made to EP 3 928 868 A1, the content of which is hereby incorporated into the present application.

[0033] Furthermore, the invention is based on the object of creating a pipette with an operating element protruding laterally from a tubular housing, which enables a housing with greater strength.

[0034] This object is achieved by the pipette described below. Advantageous embodiments of the pipette are specified in the dependent claims and in the following description. Further embodiments of the pipette described below have one or more features of the previously described pipettes.

[0035] The pipette according to the invention for use with a pipette tip comprises: a pipette housing in the form of an elongated hollow body, a through-opening in a wall of the pipette housing, an operating element arranged outside the pipette housing, an operating lever which passes through the through-opening and is connected to the operating element at an outer end, and a support arranged in the pipette housing and connected to the inner end of the operating lever, characterized by a recess on a long side of the pipette housing, a housing cover which is held on the pipette housing and covers the recess, in which the through-opening is formed, and a device for detachably connecting the inner end of the operating lever to the support.

[0036] The pipette according to the invention enables the retrofitting of the operating lever when the pipette mechanism with the support for the operating lever is already built into the pipette housing. For this purpose, the operating lever is releasably connected to the support through the opened recess using the device for releasable connection. The operating lever is mounted when the recess is not covered by the housing cover. After the operating lever is mounted on the support, the housing cover with the through-opening is pushed onto the operating lever and placed over the recess in the pipette housing so that it covers it. The housing cover is connected to the pipette housing in a position covering the recess. After the housing cover has been connected to the pipette housing, an operating element can be connected to the outer end of the operating lever.By subsequently attaching the operating lever, the pipette mechanism can be inserted through a front opening of a one-piece pipette housing in the form of an elongated hollow body. According to one embodiment of the invention, components of the pipette mechanism are held on a chassis that can be inserted into the pipette housing through a front opening. After inserting the pipette mechanism, the support for the operating lever is located on the inside of the recess, so that it is accessible from the outside for connection to the operating lever if the housing cover is not placed over the recess. After connecting the operating lever to the support, the recess is closed using the housing cover. A control element can then be attached to the outer end of the operating lever.

[0037] According to one embodiment, the device for detachable connection has a fork head with two fork tines at one end of the operating lever, which have noses projecting upwards or downwards at the ends, and the support comprises a shaft which is open on the side of the recess and which has pockets on the upper or lower side at the inner end for receiving the noses, wherein the operating lever can be inserted into the shaft in a position pivoted to the horizontal, with the noses pivoted into the pockets and can be fixed in a horizontal orientation in the shaft by means of a securing element which can be inserted between the fork head and the upper or lower side of the shaft. This embodiment of the device for detachable connection facilitates assembly and disassembly and ensures that the operating lever is securely seated on the support.

[0038] According to a further embodiment, the securing element is plate-shaped. According to another embodiment, the securing element has a contour that, at least in sections, matches the contour of the fork head. According to a further embodiment, the securing element is a locking plate. A locking plate can be designed with particularly low tolerances.

[0039] According to another embodiment, the pipette housing is constructed in one piece. This one-piece pipette housing is particularly stable. It is not easily deformed by pressing against one long side, as it does not have a joint extending along its entire length. According to another embodiment, the pipette housing has the front opening at the top end.

[0040] According to a further embodiment, the operating element is connected to the operating lever via a further device for detachable connection. The further device for detachable connection is, for example, a snap connection or a screw connection. According to another embodiment, the operating element is glued to the operating lever.

[0041] According to a further embodiment, the pipette has a device for detachably connecting the housing cover and the pipette housing. According to a further embodiment, the device for detachably connecting is a snap connection, a screw connection, or a combination of a plug connection with a snap connection or a screw connection.

[0042] According to a further embodiment, the through-opening is a slot arrangement comprising a horizontal slot and a vertical slot extending vertically downwards from the center of the horizontal slot. In this embodiment, the intake and dispensing of liquid can be controlled by moving the operating element along the vertical slot, and the ejection of a pipette tip from the spigot can be controlled by moving the operating element along the horizontal slot. According to another embodiment, the through-opening is formed solely by a vertical slot. A through-opening in the form of a vertical slot can be used, for example, for the vertical displacement of an operating element for intake and dispensing liquid. According to a further embodiment, the through-opening is a circular hole.The circular hole can, for example, be used to pass an operating lever for ejecting a pipette tip from the pin.

[0043] Furthermore, the invention is based on the object of providing a pipette with a laterally protruding operating element, in which the through opening for the passage of an operating lever can have a small width.

[0044] This object is achieved by the pipette described below. Advantageous embodiments of the pipette are specified in the dependent claims and in the following description. Further embodiments of the pipette described below have one or more features of the previously described pipettes.

[0045] The pipette according to the invention for use with a pipette tip comprises: a pipette housing in the form of an elongated hollow body, a through-opening in a housing wall of the pipette housing, an operating element arranged outside the pipette housing and an operating lever which passes through the through-opening and is connected to the operating element at the outer end, characterized by a locking device which surrounds the outer end of the operating lever and has a plurality of interlocking locking elements, wherein the interlocking locking elements with the outer end of the operating lever enclosed therein are inserted through an insertion opening into a cavity of the operating element and are supported on a wall of the operating element which delimits the cavity, and the operating element and the locking elements are snapped together via snap connection elements.

[0046] The invention enables the secure connection of an operating element made of a soft material to an operating lever with a small cross-section made of a high-strength material. The locking elements of the locking device are enclosed and held together in an interlocking position by the snap-connected operating element, together with the outer end of the operating lever enclosed therein. Due to the flat contact of the operating element with the locking elements, the latter are secured in an interlocking position, so that they permanently maintain a tight fit on the operating lever. The locking elements can be made of a high-strength material so that their contact surfaces with the operating lever are not damaged even by high operating forces, and the operating element made of a soft material sits securely on the operating lever.This allows the use of an operating lever with a small cross-section, which can be guided through a narrow opening in the pipette housing, thus preventing any substances from penetrating the pipette housing. Nevertheless, a user-friendly design of the operating element made of soft material is possible. The operating element can be released from the locking elements by loosening the snap-in connection elements. After removing the operating element, the locking elements can be released from the operating lever. This allows, for example, replacement of the operating element and / or partial disassembly of the pipette by service personnel.

[0047] According to one embodiment of the invention, the operating lever and the locking elements are connected to each other in a form-fitting manner. This is advantageous for the construction of the operating lever and locking elements from particularly strong or hard materials, which ensure a secure fit of the operating element on the operating lever.

[0048] According to a further embodiment, one locking element is arranged in a channel of another locking element. The channel forms a frame that prevents relative displacement of the locking elements perpendicular to the channel axis. Due to the flat contact of the locking elements with the operating element, only displacement of the locking elements perpendicular to a plane through the channel needs to be prevented.

[0049] According to a further embodiment, the locking elements have ribbing on the outside. This ribbing promotes a tight fit of the locking elements against an operating element made of soft material, which can, in particular, have a certain preload.

[0050] According to a further embodiment, the operating lever consists of a high-strength metal, in particular stainless steel, and the operating element consists of a soft-elastic and preferably chemically resistant plastic, preferably polypropylene.

[0051] According to a further embodiment, the operating element is an operating button which is designed, for example, as a sliding button with an actuating surface on the side for displacement in a direction perpendicular to the operating lever or as a push button with an actuating surface on the outer end for displacement in the direction of the operating lever.

[0052] In the present application, a pipette housing in the form of an elongated hollow body refers in particular to pipette housings that are partially or completely tubular or essentially tubular.

[0053] In the present application, the terms "top" and "bottom," "vertical" and "horizontal," and derived terms such as "above" and "below" and "one above the other" refer to an arrangement of the pipette in which the pipette housing is vertically oriented and the first holding device is located at the downward-facing end of the pipette housing. In this orientation, a pipette tip cylinder held in the first holding device is vertically oriented, with the tip opening located at the bottom.

[0054] The invention is explained in more detail below with reference to the accompanying drawings of exemplary embodiments. In the drawings: Fig. 1 shows a conventional positive displacement pipette with a pipette tip attached to the pin, partially cut away in a perspective view; Fig. 2 shows a slotted pin with an internal locking sleeve of the same positive displacement pipette with a pipette tip attached in an enlarged perspective view; Fig. 3 shows the same arrangement in a side view; Fig. 4 shows the same arrangement in a longitudinal section; Fig. 5 shows a positive displacement pipette from Fig. 1 in an exploded view; Fig. 6Direct displacement pipette from Fig. 1 in an exploded view without pipette housing; Fig. 7 Rotating 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 away in a side view; Fig. 9 The same positive displacement pipette during pipetting, partially cut away in a side view; Fig. 10 The same positive displacement pipette during ejection, partially cut away in a side view; Fig. 11 a-e A pipette according to the invention with the operating lever in the starting position in a front view ( Fig. 11a ) and in side view ( Fig. 11b ) and in front view with the operating lever swivelled from the starting position to the right ( Fig. 11c ), swung to the left ( Fig. 11d ) and shifted downwards ( Fig. 11e ); Fig. 12 a, bPipette housing and chassis of the same pipette before assembly in a front view ( Fig. 12 a) and in a side view ( Fig. 12b ); Fig. 13a, bthe same pipette housing and chassis assembled in front view ( Fig. 13a ) and in a side view (13b); Fig. 14a, b the same pipette with an operating lever before insertion in a side view ( Fig. 14a ) and in a perspective view diagonally from above ( Fig. 14b ); Fig. 15a-ethe same pipette with partially inserted operating lever in front view ( Fig. 15a ), a side view ( Fig. 15b ) and a perspective view diagonally from above ( Fig. 15c ); Fig. 16a-ethe same pipette with a safety element in front of the front view ( Fig. 16a ), a side view ( Fig. 16b ) and in a perspective view diagonally from above ( Fig. 16c ); Fig. 17a-ethe same pipette with inserted safety element in front view ( Fig. 17a ), a side view ( Fig. 17b ) and a perspective view diagonally from above ( Fig. 17c ); Fig. 18a, bthe same pipette with slot covers and a housing cover before assembly in a side view ( Fig. 18a ) and in a perspective view diagonally from above ( Fig. 18b ); Fig. 19a-cthe same pipette with mounted slot covers and housing cover in front view ( Fig. 19a ), a side view ( Fig. 19b ) and a perspective view diagonally from above ( Fig. 19c ); Fig. 20a-eOperating lever, carrier and slot covers of the same pipette in a perspective view obliquely from above ( Fig. 20a ), bottom view ( Fig. 20b ) and top view ( Fig. 20c ); Fig. 21The same pipette with locking device and operating lever before assembly in a side view (Fig. 22a) and in a perspective view obliquely from above (Fig. 22b); Fig. 22Locking device and operating element mounted on the operating lever with carrier and slot covers in an enlarged vertical section.

[0055] The Figuren 1 bis 10 show a pipette 1 designed as a positive displacement pipette according to the corresponding figures of EP 3 680 016 B1. This has a rod-shaped (e.g. cylindrical) pipette housing 2. A hollow cylindrical shaft 3 projects downwards from the lower end of the pipette housing 2. A pin 4 projects downwards from the lower end of the shaft 3, which according to Fig. 1 and 4 has a through-bore 5 with a through hole at the lower end. The inner diameter of the through-bore 5 is smaller than the inner diameter of the shaft 3.

[0056] The pin 4 has an upper pin section 6 in the shape of a hollow cylinder and, below it, a lower pin section 7 in the shape of a hollow cone. An annular groove 8 extends around the outer circumference of the pin 4 between the upper pin section 6 and the lower pin section 7.

[0057] The upper pin section 6, the annular groove 8 and the lower pin section 7 form first means for the positive connection 9 of the pipette with a pipette tip.

[0058] Furthermore, the pin 4 has two slots 10, 11 extending in its longitudinal direction, which are diametrically opposed to each other. The slots 10, 11 extend from the lower end over the entire length of the pin 4.

[0059] According to Fig. 1 , 5 and 6 A drive device 12 is provided 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 knob 19, which is firmly connected to a plate-shaped support 21 via an operating lever 20.

[0060] According to Fig. 6 The support 21 has an oval shape with a wide, rounded end and a narrow, rounded end, with the operating lever 20 protruding from the edge of the narrow, rounded end. Adjacent to this edge, the support 21 has a first curved slot 22 that runs approximately parallel to the contour of the narrow, rounded end. Furthermore, the support 21 has a rectangular first edge recess 23 in the center of the first curved slot 22 on the side of the narrow, rounded end.

[0061] According to Fig. 1 and 5 The lifting rod 17 is inserted from above into the shaft 3 and the pin 4. According to Fig. 4 It is hollow and provided with a longitudinal slot 24 extending from the lower end in the longitudinal direction. 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.

[0062] The transmission mechanism 15 is designed such that during successive downward movements of the operating element 18, between which the operating element 18 is moved upwards, the lifting rod 17 is moved alternately downwards and upwards. Consequently, by pressing the operating element 18 downwards, the lifting rod 17 can be moved from an upper position to a lower position, the lifting rod 17 maintains the lower position during the subsequent upward movement of the operating element 18, and the lifting rod 17 is moved upwards again by subsequently pressing the operating element 18 downwards. This can be repeated as often as desired.

[0063] According to Fig. 1 , 5 and 6The 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 is supported at the upper and lower ends between steps on the inner circumference of the pipette housing 2, so that it cannot be displaced in the axial direction within the pipette housing 2. The axis of rotation of the rotating sleeve 28 coincides with the longitudinal axis of the pipette housing 2 and the longitudinal axis of the pin 4.

[0064] The rotating sleeve 28 has recesses 29, 30 parallel to its axis of rotation on two diametrically opposite sides, extending from the upper edge of the rotating sleeve 28 and ending at a distance from its lower edge. Below the recesses, the rotating sleeve 28 thus consists of a circular base 31, and above it, it consists of two diametrically opposed sectors 32, 33 of a circular ring, which laterally delimit the two recesses 29, 30.

[0065] 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 shape of an inverted (upside down) Y. The vertical part 37 of the Y extends far upwards on a sector 32 until just before 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 rotary sleeve 28 in the shape of an upright V. The first curve 34 and the second curve 35 are arranged offset by 90° from one another 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.

[0066] According to Fig. 1 , 5 and 6The 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 ejection rod part 40 is connected to the upper end of the lower ejection rod part 41 via a strip-shaped connecting rod part 42 inclined at an angle to the two ejection rod parts. A first sensing element 43 in the form of a first guide pin 44 protrudes perpendicularly from the inside of the upper ejection rod part 40. The ejection rod 39 is preferably formed in one piece, for example from a rigid plastic.

[0067] According to Fig. 1 , 4 and 7the ejection rod 39 is guided with the guide pin 44 in the first groove 36, passes through the longitudinal slot 24 of the lifting rod 17 with the connecting rod part 42 and extends with the lower ejection rod part 41 within the lifting rod 17 until shortly before the lower end of the same.

[0068] According to Fig. 1 , 4 , 5 and 6 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 connected to one another via a second connecting rod part 48, which is inclined obliquely to the locking sleeve 46 and the control rod 47. A second sensing element 49 in the form of a second guide pin 49.1 protrudes from the inside of the control rod 47.

[0069] According to Fig. 1 and 7 the second guide pin 49.1 is guided in the second groove 38. According to Fig. 1 and 4 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.

[0070] 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 , 6 and 7The rotating sleeve 28 is connected at the top to a support ring 50, which bridges the two sectors 32, 33 and stabilizes the rotating sleeve 28. The support ring 50 has a downwardly projecting casing 51 on the outer edge, which laterally surrounds the two sectors 32, 33 at the outer edges. Furthermore, it 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, the casing 51 has a downwardly open, rectangular second edge recess 52.1, which is designed to receive the operating lever 20 between the operating element 18 and the carrier 21.

[0071] The support ring 50 is connected to the rotating sleeve 28, for example by gluing.

[0072] The rotating sleeve 28 and the locking sleeve 46, as well as the operating lever 20, are made, for example, of one or more rigid plastics and / or metal. The rotating sleeve 28, the support ring 50, the operating lever 20, and / or the locking sleeve 46 are preferably each formed as a single piece. An operating button 19 of the operating element 18 can also be made of an elastic or flexible plastic or rubber.

[0073] The operating lever 20 protrudes from the pipette housing 2 through a first housing slot that runs transversely to the longitudinal axis of the pipette housing 2 and extends over part of the circumference of the pipette housing 2, allowing it to be operated from the outside. The first housing slot is connected in the center to a second housing slot that runs in the longitudinal direction of the pipette housing 2.

[0074] The operating lever 20 can be displaced downward from the support ring 50 along the second housing slot, counter to the action of a spring device, sliding with the first curved slot 22 on the sector 32 of the rotating sleeve 28. After the load is released, the spring device automatically displaces the operating lever 20 back upward.

[0075] A sleeve-shaped third sensing 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 top of the third sensing element 53. The helical spring 54 presses the sensing element 53 from above against a stop element on the shaft 3 or pin 4.

[0076] An adjustment knob 55 for setting a dispensing volume is located on the top of the pipette housing 2. The dispensing volume can be adjusted by turning the adjustment knob 55. A counter 56 located below in the pipette housing 2 indicates the currently set dispensing volume. The adjustment knob 55 and / or the counter 56 are coupled to the transmission mechanism 15. The transmission mechanism 15 is designed to change the stroke of the lifting rod 17 according to the currently set dispensing volume, which is achieved by moving the operating element 18 downward.

[0077] According to Fig. 1 bis 4 A pipette tip 57 is placed onto the pin 4. The pipette tip 57 comprises a tubular body 58 having a tip opening 59 at the lower end, a collar 61 having a mounting opening 60 at the upper end, and a seating area 62 on the inner circumference of the collar 61 for clamping onto the pin 4. The seating area 62 has a contour complementary to the pin 4, comprising a conical lower seating section 63 at the bottom for receiving the conical lower pin section 7, a circumferential bead 64 above this for engaging in the annular groove 8 of the pin 4, and a cylindrical upper seating section 65 above this for receiving the cylindrical upper pin section 6. The lower seating section 63, the bead 64, and the upper seating section 65 form second means for positively connecting 66 the pipette tip 57 to the pipette 1.

[0078] Below the seat area 62, the tubular body 58 has a cylindrical piston running area 67. Below this, the tubular body 58 has a downwardly tapered tip section 68 in the shape of a hollow truncated cone. The tip section 68 is in Fig. 4 shown and omitted in the remaining drawings for simplification purposes. A tip piston 69 is inserted into the tubular body 58. This comprises a piston 70, which is guided in the piston running area 67. A piston rod 71, which has a smaller diameter than the piston 70, projects upwards from the piston 70. At the upper end, the piston rod 71 has a piston head 72. The piston head 72 is according to Fig. 4 pressed downwards into the receptacle 25 of the reciprocating piston 17.

[0079] The following is based on the Fig. 11 bis 22 A pipette according to the invention is explained. This pipette has a pin, a drive mechanism, a transmission mechanism, and an ejection device, as described above with reference to a conventional pipette. The corresponding components of the pipette according to the invention are designated by the same symbols and reference numerals.

[0080] According to Fig. 11 and 22 The operating lever 20 protrudes from the pipette housing 2 through a horizontal slot 73 running transversely to the longitudinal axis of the pipette housing 2 and extending over part of the circumference of the pipette housing, so that it can be operated from the outside. The horizontal slot 73 is connected in the center to a vertical slot 74 running in the longitudinal direction of the pipette housing 2.

[0081] The horizontal and vertical slots 73, 74 are formed in a cylindrical shell-shaped housing cover 75, which covers a recess 76 on one side of the pipette housing 2. The housing cover 75 has, according to Fig. 18 on the longitudinal edges snap hooks 77 with which it can be snapped behind the edge of the recess 76.

[0082] Below the vertical slot 74 is according to Fig. 18 and 22 from the inside of the housing cover 75, a bracket 78 is provided. The vertical slot 74 is covered on the inside of the housing cover 75 by a strip-shaped vertical slot cover 79 (cf. Fig. 11 and 20 ). This is only attached to the bracket 78 at its lower end and has no other connection to the housing cover 75.

[0083] A cylindrical shell-shaped, horizontal slot cover 80 is according to Fig. 11 , 18 , 20 and 22) is arranged on the inside of the housing cover 75 so that it covers the horizontal slot 73. The horizontal slot cover 80 has a vertical insertion slot 81 extending from the lower edge. It is rotatably guided on a guide 82 in the pipette housing 2. The guide 82 comprises a cylindrical shell-shaped guide element 83, which is firmly connected to the housing cover 75 above the horizontal slot 73. The horizontal slot cover 80 is guided at its upper edge in a gap 84 between the housing cover 112 and the cylindrical shell-shaped guide element 83 (cf. Fig. 22 ). Furthermore, the guide 82 comprises guide projections 85 below the horizontal slot 73 on both sides next to the vertical slot 74, projecting from the inside of the housing cover 75 on a circular arc, on which the horizontal slot cover 80 rests with its lower edge.

[0084] According to Fig. 20 and 22The carrier 21 comprises a substantially cylindrical trigger 86. The trigger 86 is part of a transmission mechanism, which is designed, for example, as described in EP 3 928 868 A1. Furthermore, the carrier 21 comprises a carrier plate 87 protruding from the lateral edge of the trigger 86. The carrier plate 87 has a first curved slot 22. Further outwardly, the carrier plate 87 contains a vertical passage 88 in the form of a shaft 89 with a substantially rectangular cross-section, which serves to receive the vertical slot cover 79.

[0085] The operating lever 20 is connected at its inner end to the carrier 21 via a device for detachable connection 90. For this purpose, the operating lever 20 has Fig. 14 at its inner end a fork head 91 with two fork tines 92, 93, which carry upwardly projecting lugs 94, 95 at the ends. The carrier 21 has a shaft 96 in the carrier plate 87 which is open to the side and which has pockets 97, 98 at its inner end on the top or bottom for receiving the lugs 94, 95 (cf. Fig. 20 ). The operating lever 20 is in accordance with Fig. 14 and 15 in a position pivoted to the horizontal, can be inserted into the shaft 96 and pivoted with the lugs 94, 95 into the pockets 97, 98. Furthermore, the device for detachable connection 90 according to Fig. 16 a securing element 99 in the form of a securing plate 100, the contour of which corresponds to the contour of the fork head 91 and an adjacent straight section of the operating lever 20. At the front edge, the securing plate 100 has vertically upstanding tabs 101, 102.

[0086] The shaft 89 has undercuts 103, 104 on both sides. The width of the fork head 91 is smaller than the distance between the undercuts 103, 104, so that the operating lever 20 can be pivoted past the undercuts 103, 104 into the shaft 96. The fork head 91 of the locking plate 100 is wider, so that the locking plate 100 engages behind the undercuts 103, 104 when it is inserted into the shaft 96 above the operating lever 20 (see Fig. 17 This prevents the operating lever 20 from accidentally pivoting out of the shaft 96. The tabs 101, 102 rest against the inside of the housing cover 75, preventing the locking element 99 from leaving the locking position in the shaft 96.

[0087] According to Fig. 21 and 22The operating element 18 comprises an operating knob 19 made of a soft, preferably flexible material. The operating knob 19 is preferably made of a chemically resistant material. For example, it is made of polypropylene.

[0088] The control knob 19 has a flat bottom 105 and a slightly curved top 106. It has a cavity 107 inside with an insertion opening 108 on a vertical side. A flat support plate 109 protrudes upward from this side. In a vertical section, the cavity 107 has a horizontal lower edge and a curved upper edge. The control knob 19 is actuated by pressing against the top 106.

[0089] The operating lever 20 is rod-shaped with a rectangular cross-section. Near its free end, a rectangular projection 110 protrudes downward from the underside of the operating lever 20. In the area of ​​the projection 110, the operating lever 20 is just as wide as the straight section above it.

[0090] The operating lever 20 is made of high-strength steel.

[0091] Furthermore, the operating element 18 comprises a two-part locking device 111. This has a lower locking element 112 with a wide lower channel 113 on the upper side. On both sides of the channel 113, the lower locking element 112 has a protruding ribbing 114 on the outside, which is supported on the inside of the cavity 107. Furthermore, the locking device 111 has a rib 115 projecting upwards from the base of the lower channel 113, which extends from one channel end in the longitudinal direction over part of the lower channel 113. The rib 115 has a receptacle 116 for the projection 110 on the underside of the operating lever 20 at a distance from the channel end from which the rib 115 originates.

[0092] An upper locking element 117 can be inserted into the lower channel 113. It has an upper channel 118 on its underside, which receives the rib 115 of the lower locking element 112 and the operating lever 20 mounted thereon. The upper channel 118 ends at a distance from the end of the lower channel 113, from which the rib 115 protruding in the lower channel 113 extends. The inner end of the upper channel 118 rests against the outer end of the rib 116 protruding from the lower channel. The upper locking element 117 has a further ribbing 119 on its outer side, with which it is supported on the inside of the cavity 107.

[0093] When assembled, the locking device 111 has a shape that tapers slightly at the end of the locking device 111 facing away from the fork head 91 of the operating lever 20. Furthermore, the locking device 111 has snap elements 120, 121 on the top and bottom sides at the end facing the fork head 91, which can be snapped together with snap elements 122, 123 adjacent to the insertion opening 108 of the cavity 107 in the operating knob 19. In the example, the snap elements 120, 121 have outwardly projecting snap bulges, and the operating knob 19 has molded-in snap grooves.

[0094] According to Fig. 21 and 22 the lower and upper locking elements 112, 117 can be brought into an interlocking and mutually blocking position around the operating lever 20, in which they can be fixed to one another by being pushed into the cavity 107 and snapping the snap elements 120 to 121 together.

[0095] The lower and upper locking elements 112, 117 are preferably made of a hard plastic or a hard-elastic plastic. This ensures secure fixation of the operating lever in the soft operating knob 19.

[0096] According to Fig. 12 and 13 A chassis 124 equipped with components 3 of the pipette mechanism can be pushed through an upper opening 125 of a substantially tubular pipette housing 2 until it rests against a stop. When the chassis 124 is pushed in as far as it will go, a shaft 3 with the pin 4 at the lower end for sliding on a pipette tip 57 protrudes from a lower opening 126 of the pipette housing 2. This is shown in the Fig. 17 and 18 shown.

[0097] The chassis 124 is secured in the inserted position in the pipette housing 2.

[0098] Through the recess 76 in one side of the pipette housing 2, the shaft 96 in the carrier 21 is accessible from the outside. The operating lever 20 is pivoted into the shaft 96 from the side with the fork head 91 and according to Fig. 16 and 17 secured by means of the securing plate 100 in the shaft 96.

[0099] According to Fig. 18 and 19 The housing cover 75 is then mounted with the slotted covers 79, 80. Beforehand, the guide element 83 is fixed to the inside of the housing cover 75, and the horizontal slotted cover 80 is mounted between the guide element 83 and the guide projections 85. Furthermore, the lower end of the vertical slotted cover 79 is fixed to the bracket 78.

[0100] The housing cover 75 is then snapped onto the recess 76, with the operating lever 20 being inserted into the insertion slot 81 of the horizontal slot cover 80.

[0101] When the operating lever 20 is moved out of the insertion slot 81 into the vertical slot 74, the vertical slot cover 79 enters the passage 88 of the carrier 21 and slides over it when the operating button 19 is moved downwards.

[0102] According to Fig. 21 and 22 Finally, in the manner described above, the operating knob 19 is attached to the operating lever 20 by means of the lower and upper locking elements 112, 117.

[0103] Pipette 1 can be used as follows:

[0104] According to Fig. 11a und b In an initial state, a pipette tip 57 is held on the pipette 1. The seating area 62 is positively connected to the pin 4, in particular by the engagement of the bead 64 in the annular groove 8. The operating element 18 is located in the initial position at the upper end of the vertical slot 74, in which it can be rotated into the first slot 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, whichever is smaller.

[0105] The locking sleeve 46 is according to Fig. 4 arranged in the lowest position, so that it prevents accidental detachment of the pipette tip 57 from the pin 4. To break the positive connection, a radial narrowing of the pin 4 would be necessary, which the locking sleeve 46 does not allow in this position. In deviation from Fig. 4 In the initial position, the tip piston 69 is not yet pressed with the piston head 72 into the receptacle 25 of the lifting rod 17.

[0106] To connect the tip piston 69 to the lifting rod 17, the operating element 18 is pressed downwards. This movement is transmitted by the transmission mechanism 15 to the lifting rod 17, so that it is pressed onto the piston head 72 with the holder 25. This is shown in Fig. 4 shown.

[0107] After the load is released, the operating element 18 is returned to its initial position by a spring device according to Fig. 8 The lifting rod 17 and the tip piston 69 retain the positions according to Fig. 4 at.

[0108] To aspirate liquid, the pipette 1 is immersed in a liquid with the lower end of the pipette tip 57 held thereon. The operating element 18 is then pressed downwards 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 upwards. The piston head 72 carries the ejector rod 39 with it, so that the first guide pin 44 slides upwards in the vertical part 37 of the Y-shaped first groove 36. Meanwhile, the locking sleeve 46 maintains its position. This is shown in Fig. 9 shown.

[0109] When the operating element 18 has completed the set stroke, the pipette tip 57 is filled with a specific amount of liquid. The operating element 18 is then released and moved back upward by the spring mechanism until it rests against the support ring 50. To dispense this amount of liquid, the pipette 1 can be aligned with the pipette tip 57 toward another container. By pressing the operating element 18 downward again, the lifting rod 17 is moved downward and the amount of liquid is dispensed. The first guide pin 44 slides downward to the junction point of the first groove 36.

[0110] The stroke performed by the control element 18 when taking in and dispensing liquid depends on the set amount of liquid.

[0111] The intake and release of fluid can be carried out several times.

[0112] To eject the pipette tip 57, the operating lever 18 is pivoted to the right or left in its initial position. This rotates the rotating 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 inwards. For this purpose, the locking sleeve 46 is preferably withdrawn from the through-bore 5. Furthermore, by rotating the rotating sleeve 28, the first guide pin 44 is displaced downwards in one of the two lateral sections of the lower part of the first groove 36 so that the ejection rod 39 presses against the tip piston 69, which is supported at the bottom on the tip section 68. The bead 64 exerts a radial force on the pin, so that it narrows and the positive connection between the pipette tip 57 and pin 4 is dissolved. This releases the pipette tip 57 from the pin 4. This is in Fig. 10 shown. The removal of the pipette tip 57 from the pin 4 can be further assisted by the sensing element 53, which is pressed against the upper edge of the pipette tip 57 by the preloaded helical spring 54. List of reference symbols

[0113] 1 Pipette 2 Pipette housing 3 Shaft 4 Pin 5 Through hole 6 Upper pin section 7 Lower pin section 8 Annular groove 9 First means for positive connection 10 Slot 11 Slot 12 Drive direction 13 Transmission element 14 Transmission rod 15 Transmission mechanism 16 Drive element 17 Lifting rod 18 Operating element 19 Operating button 20 Operating lever 21 Carrier 22 First curved slot 23 First edge recess 24 Longitudinal slot 25 Receptacle 26 Ejection device 27 Curve carrier 28 Rotating sleeve 29 Recess 30 Recess 31 Base 32 Sector 33 Sector 34 First curve 35 Second curve 36 First groove 37 Vertical part 38 Second groove 39 Ejection rod 40 Upper ejection rod part 41 Lower ejection rod part 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 Casing 52 Second curved slot 52.1 Second edge recess 53Third 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 Seat area 63 Lower seat section 64 Bead 65 Upper seat section 66 Second means for positive connection 67 Plunger running area 68 Syringe section 69 Tip piston 70 Piston 71 Piston rod 72 Piston head 73 Horizontal slot 74 Vertical slot 75 Housing cover 76 Recess 77 Snap hook 78 Console 79 Vertical slot cover 80 Horizontal slot cover 81 Insertion slot 82 Guide 83 Cylindrical guide element 84 Gap 85 Guide projection 86 Trigger 87 Carrier plate 88 Passage 89 Shaft 90 Means for detachable connection 91 Fork head 92, 93 Fork tine 94, 95 Nose 96 Shaft 97, 98 Pocket 99 Securing element 100 Securing plate 101, 102 Flag 103, 104 Undercut 105 Flat bottom 106 Curved top 107 Cavity 108 Insertion opening 109 Contact plate 110 Projection 111Locking device 112 Lower locking element 113 Lower channel 114 Ribbing 115 Rib 116 Receptacle 117 Upper locking element 118 Upper channel 119 Further ribbing 120, 121 Snap element 122, 123 Snap element 124 Chassis 125 Upper opening 126 Lower opening

Claims

1. A pipette for use with a pipette tip, comprising: • a pipette housing (2) in the form of an elongated hollow body, • a slot arrangement having a vertical slot (74) and a horizontal slot (73) at the upper end of the vertical slot (74) formed in a housing wall of the pipette housing, • an operating element (18) arranged outside the pipette housing (2) and displaceable along the slot arrangement, • an operating lever (20) which engages through the slot arrangement and connected at an outer end to the operating element (18), and • a carrier (21) arranged in the pipette housing (2) and connected to an inner end of the operating lever (20), characterized by • a strip-shaped, vertical slot cover (79) which extends on the inside of the vertical slot (74), is connected at the lower end of the vertical slot to the pipette housing (2) and extends up to the upper end of the vertical slot, • a strip-shaped horizontal slot cover (80), which is arranged on the inside of the horizontal slot (73), has a vertical introduction slot (81) starting from its lower edge for the operating lever (20) and is guided along the horizontal slot on a guide (82) connected to the pipette housing (2), • wherein the carrier (21) has a vertical through-passage (88) which receives the vertical slot cover (79) when the operating lever (20) engages in the vertical slot (74) and which is released from the vertical slot cover (79) when the operating lever (20) engages in the horizontal slot (79) and the introduction slot (81) of the horizontal slot cover (80).

2. The pipette according to Claim 1, in which a bracket (78) is arranged below the vertical slot (74) in the pipette housing, to which bracket the vertical slot cover (79) is fastened, wherein the bracket (78) protrudes inward from the pipette housing (2) or protrudes outward from a component of a chassis (124) carrying a pipette mechanism.

3. The pipette according to Claim 1 or 2, in which the horizontal slot (79) runs in the form of a circular arc, the horizontal slot cover (80) is in the form of a cylindrical shell and the guide (82) is in the form of a circular arc.

4. The pipette according to Claim 3, in which the guide (82) has a guide element (83) in the form of a cylindrical shell at a distance from the inside of the pipette housing (2) above the horizontal slot (73), and the horizontal slot cover (80) engages from below in a gap (84) between the pipette housing (2) and the guide element (83) and is guided therein, and / or in which the guide (82) has, in each case, at least one guide projection (85) protruding from the inside of the pipette housing on a circular arc, below the horizontal slot (73) on both sides next to the vertical slot (74), on which guide projection the horizontal slot cover (80) is guided.

5. The pipette according to one of Claims 1 to 4, in which the slot arrangement is configured in a housing cover (75) which covers a recess (76) in the pipette housing (2).

6. The pipette according to Claim 5, in which the vertical slot cover (79) is fastened to the inside of the housing cover (75) and / or the horizontal slot cover (80) is guided.

7. The pipette according to Claim 5 or 6, which has an apparatus for connecting the housing cover (75) and the pipette housing (2) and which is preferably a snap connection, a screw connection or a combination of a plug-in connection and a snap connection or a screw connection.

8. The pipette according to Claim 6 or 7, in which the housing cover (75) is in the form of a cylindrical shell and covers a recess (76), which is complementary to it, of the pipette housing (2).

9. The pipette according to one of Claims 1 to 8, in which the operating element (18) for driving a drive apparatus for a piston (70) or another displacement element of a piston-cylinder apparatus or another displacement apparatus is displaceable along the vertical slot (74) and is displaceable along the horizontal slot (73) for ejecting a pipette tip (57) from the pin (4).

10. The pipette according to one of Claims 1 to 9, in which an apparatus for detachable connection (90) detachably connects the inner end of the operating lever (20) to the carrier (21).

11. The pipette according to Claim 10, in which the apparatus for detachable connection (90) has a fork head (91) with two fork teeth (92, 93) at one end of the operating lever (20), which carry noses (94, 95) protruding upward or downward at the ends, and the carrier (21) comprises a shaft (96) which is open on the side of the recess and which has pockets (97, 98) at the inner end of the top or bottom for receiving the noses (94, 95), wherein the operating lever (20) can be slid into the shaft (96) in a position pivoted to the horizontal, can be pivoted into the pockets (97, 98) with the noses (94, 95) and can be fixed by means of a securing element (99) which can be slid in between the fork head (91) and the top or bottom of the shaft, in a horizontal orientation in the shaft (96).

12. The pipette according to Claim 10 or 11, in which the pipette housing (2) is one piece.

13. The pipette according to one of Claims 1 to 12, in which the outer end of the operating lever (20) is enclosed by a locking apparatus (111) having multiple interlocking locking elements (112, 117), the interlocking locking elements (112, 127) having the outer end of the operating lever (20) enclosed therein are inserted through an insertion opening (108) into a hollow space (107) of the operating element (18) and are supported on a wall of the operating element (18) delimiting the hollow space (107) and the operating element (18) and the locking elements (112, 117) are snapped on to one another via snap connection elements (120 to 123).

14. The pipette according to Claim 13, in which the operating lever (22) and the locking elements (112, 117) are positively connected to one another.

15. The pipette according to one of Claims 1 to 14, in which the operating lever (20) consists of a high-strength steel, in particular stainless steel, and the operating element (18) consists of a soft-elastic and preferably chemical plastic, preferably propylene.