EP3778028B1 - Pipette with adjustable volume - Google Patents

Description

The invention relates to a pipette with an adjustable metering volume.

Pipettes are particularly used in laboratories for dispensing liquids. For this purpose, a pipette tip is clamped with its upper end on a seat of the pipette. The seat is usually a conical or cylindrical projection with respect to a housing of the pipette, onto which a pipette tip with an upper opening of its tubular body can be clamped. The pipette tip can absorb and dispense liquid through a lower opening in its tubular body. Air-cushion pipettes comprise a displacement device for air which is connected to the pipette tip in a communicating manner through an opening in the seat. An air cushion is displaced by means of the displacement device, so that liquid is sucked into the pipette tip and expelled therefrom. For this purpose, the displacement device has a displacement chamber with a displaceable displacement element. The displacement device is usually a cylinder with a piston that can be displaced therein.

The pipette tip is removed from the seat after use and exchanged for a fresh pipette tip. In this way, contamination caused by the transfer of liquid can be avoided during subsequent dosing. Most pipettes have an ejection device which enables pipette tips to be ejected by pressing a button without touching the pipette tips. Pipette tips for single use are mostly made of plastic.

The piston is coupled to a drive device which is used to move the piston in the cylinder. The drive device has a lifting rod which can be displaced with a stop element between an upper and a lower stop. At the beginning of the suction of air into the cylinder is located the stop element at the lower stop. At the beginning of the displacement of air from the cylinder, the stop element rests against the upper stop. The amount of liquid absorbed or discharged depends on the stroke of the lifting rod between the lower and upper stop.

With fixed volume pipettes, the distance between the upper and lower stop is constant. In the case of pipettes with adjustable dispensing volumes, the position of the upper stop can be changed. Known pipettes have an upper stop on the underside of a threaded spindle, which is adjustable in a spindle nut fixedly arranged in the housing. To adjust the threaded spindle, there are setting devices which are coupled to display devices for displaying the set dosing volume in the form of a counter.

the DE 43 35 863 C1 and U.S. 5,531,131 describe a pipette in which an actuating button protrudes from the top of the housing and is connected to the upper end of a lifting rod which is connected to the piston at the lower end. The lifting rod is passed through channels of a threaded spindle and a lower stop. It has a stop element in the form of an outwardly protruding bead which limits the movement of the lifting rod between the upper stop at the bottom of the threaded spindle and the lower stop. By pressing in the actuating element against the force of a return spring, the piston is moved deeper into the cylinder until the stop element rests against the lower stop. After the actuation element is relieved of pressure, the piston returns to its starting position due to the action of the return spring, in which the stop element rests against the threaded spindle. Adjusting devices for adjusting the threaded spindle have an adjusting sleeve rotatably mounted in the housing, which protrudes from the top of the housing and in which the actuating button can be axially displaced. The adjusting sleeve is non-rotatably connected to the threaded spindle by means of axial grooves on its inner circumference and drivers projecting radially from the upper end of the threaded spindle. Go berserk the adjusting sleeve, the threaded spindle with the upper stop and thus the dosing volume can be adjusted. The adjusting sleeve has a spur gear at the lower end which is positively coupled to a spur gear of a counter via coupling devices with two coupling spur gears on a common axis. The axis on which the two coupling spur gears are mounted can be shifted by means of switching devices in order to release the coupling devices. This enables the pipette to be calibrated at the factory.

the EP 1 743 701 B1 and US 8,133,453 B2 describes a pipette of the type described above, which additionally has an adjusting device for adjusting the position of a holder holding the lower stop relative to the cylinder and a display device for displaying the position of the holder. This makes it easier for the user to change the calibration and to find the factory calibration again.

the WO 01/61308 A1 describes a manually adjustable pipette which, for fine adjustment of the dispensing volume, has a threaded rod which is coupled to a piston rod in a rotationally fixed manner and which can be displaced in a nut which is arranged in the housing in a rotationally fixed manner. In the upper end position of the piston, a flange element rests on the piston rod on the underside of the threaded spindle. For a quick adjustment of the metering volume, the piston rod is passed through an axially displaceable sleeve which carries the spindle nut at the bottom. A locking mechanism prevents axial displacement of the sleeve in the locked position and releases it for quick adjustment when unlocked. The set dosage amount is determined by means of position sensors that detect the position of the piston rod. The piston unit has an operating button on the upper end, with which both the fine adjustment of the dosing volume and the uptake and delivery of liquid by means of a pipette tip are controlled. As a result, the dispensing volume can be adjusted when pipetting come. In addition, the pipette is complex due to the mechanical and electronic components.

the US 2019/0083969 A1 and US 2019/0083970 A1 describe a quick adjustment mechanism for the dispensing volume of a pipette. One embodiment has a frame for insertion into a housing of a pipette, in which a planetary gear with an input shaft and an output shaft is arranged. An operating mode selector is coupled to the input of the planetary gear. The mode selector is between a direct drive position, in which the planetary gear is disengaged, so that the rotation of the input shaft causes a 1: 1 rotation of the output shaft of the planetary gear, and a speed-multiplying position in which the planetary gear is engaged, so that a rotation of the Input shaft produces a rotation of the output shaft at a multiple speed, displaceable. Another embodiment has a carrier for insertion into a housing of a pipette, on which a gear drive with an input shaft, an output shaft and a shaft parallel to it, a spur gear on the input shaft and a spur gear meshing with it on the parallel shaft, a spur gear on the Output shaft and a spur gear meshing with it on the parallel shaft as well as claw clutches between the two spur gears on the input shaft and the output shaft and the two spur gears on the shaft parallel thereto. By coupling the input shaft and the output shaft, a direct drive is achieved in which the rotation of the input shaft in a ratio of 1: 1 is converted into a rotation of the output shaft. By closing the other dog clutch, a speed-multiplying state is achieved, so that a rotation of the input produces a rotation of the output at a multiple speed. The high structural complexity and the large space requirement are disadvantageous, since the rapid adjustment mechanism takes up a length section in the housing of the pipette above a threaded spindle. In addition, the setting of the Dosing speed is limited by the fact that in the direct drive mode the speed on the input shaft is the same as on the output shaft.

The disadvantages mentioned above also apply to the rapid adjustment of the pipette with a planetary gear EP 2 329 885 B1 to.

Proceeding from this, the invention is based on the object of creating a pipette which enables fine adjustment of the dosing volume and rapid adjustment of the dosing volume with less structural complexity and less space requirement.

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

• ein stangenförmiges Gehäuse,
• mindestens einen Sitz zum lösbaren Halten einer Pipettenspitze am unteren Ende des Gehäuses,
• eine Verdrängungseinrichtung umfassend eine fest im Gehäuse angeordnete Verdrängungskammer mit einem darin verlagerbaren Verdrängungselement,
• einen die Verdrängungskammer mit einer Öffnung im Sitz verbindenden Verbindungskanal,
• eine am unteren Ende mit dem Verdrängungselement gekoppelte, in Längsrichtung im Gehäuse verlagerbare Hubstange zum Verlagern des Verdrängungselements in der Verdrängungskammer,
• einen mit dem oberen Ende der Hubstange verbundenen und vom Gehäuse vorstehenden Bedienknopf,
• ein Anschlagelement am äußeren Umfang der Hubstange,
• eine Gewindespindel, die eine zentrale Spindelbohrung aufweist, durch die die Hubstange hindurch geführt ist und die unten einen oberen Anschlag für das Anschlagelement aufweist,
• ein in einer festen Position im Gehäuse angeordnetes Innengewinde, in das die Gewindespindel mit einem Außengewinde eingreift,
• einen unterhalb des oberen Anschlages in einem Abstand von diesem angeordneten unteren Anschlag für das Anschlagelement,
• eine drehbar im Gehäuse gelagerte Mitnehmerhülse, die am Innenumfang mindestens eine in Längsrichtung verlaufende Nut aufweist, in die mindestens ein Mitnehmer der Gewindespindel eingreift,
• ein Zählwerk zum Anzeigen des Dosiervolumens, das ausgebildet und angeordnet ist, um die Drehung der Mitnehmerhülse zu erfassen,
• eine drehbar im Gehäuse gelagerte Einstellhülse,
• ein mit der Einstellhülse verbundenes, von der Außenseite des Gehäuses aus zugängliches Einstellelement,
• eine zur Einstellhülse und zur Mitnehmerhülse parallele, drehbar im Gehäuse gelagerte Übertragerwelle,
• wobei die Einstellhülse eine Antriebswelle, die Mitnehmerhülse eine Abtriebswelle und die Übertragerwelle eine Vorgelegewelle eines als Stirnradgetriebe ausgebildeten Schaltgetriebes ist, das eine Schalteinrichtung mit einem von der Außenseite des Gehäuses aus zugänglichen Schaltelement aufweist, wobei das Schaltgetriebe ausgebildet ist, durch Betätigen des Schaltelementes verschiedene Schaltstufen mit verschiedenen Übersetzungen zwischen der Drehgeschwindigkeit der Einstellhülse und der Drehgeschwindigkeit der Mitnehmerhülse zu schalten.

The pipette according to the invention with adjustable dosing volume comprises:

• a rod-shaped housing,
• at least one seat for releasably holding a pipette tip at the lower end of the housing,
• a displacement device comprising a displacement chamber which is fixedly arranged in the housing and has a displacement element which can be displaced therein,
• a connecting channel connecting the displacement chamber to an opening in the seat,
• a lifting rod coupled at the lower end to the displacement element and displaceable in the longitudinal direction in the housing for displacing the displacement element in the displacement chamber,
• an operating button connected to the upper end of the lifting rod and protruding from the housing,
• a stop element on the outer circumference of the lifting rod,
• a threaded spindle which has a central spindle bore through which the lifting rod is guided and which has an upper stop for the stop element at the bottom,
• an internal thread arranged in a fixed position in the housing, in which the threaded spindle engages with an external thread,
• a lower stop for the stop element arranged below the upper stop at a distance therefrom,
• a driver sleeve rotatably mounted in the housing, which has at least one longitudinal groove on the inner circumference, in which at least one driver of the threaded spindle engages,
• a counter for displaying the dosing volume, which is designed and arranged to detect the rotation of the driver sleeve,
• an adjusting sleeve rotatably mounted in the housing,
• an adjusting element connected to the adjusting sleeve and accessible from the outside of the housing,
• a transmission shaft that is parallel to the adjustment sleeve and the driver sleeve and rotatably mounted in the housing,
• wherein the adjusting sleeve is a drive shaft, the driver sleeve is an output shaft and the transmission shaft is a countershaft of a gearbox designed as a spur gear, which has a shifting device with a shifting element accessible from the outside of the housing, the shifting gear being designed with various shifting stages by actuating the shifting element to switch different translations between the speed of rotation of the adjusting sleeve and the speed of rotation of the driving sleeve.

The pipette according to the invention has, instead of an adjusting sleeve from the prior art mentioned at the beginning, which is non-rotatably connected to the threaded spindle and protrudes from the housing with the upper end for adjusting the dosing volume, a driving sleeve and a non-rotatable driving sleeve connected to the threaded spindle a separate, rotatably mounted adjustment sleeve in the housing for adjusting the dosing volume. The adjusting sleeve forms a drive shaft and the driver sleeve forms an output shaft of a spur gear designed as a gearbox. This additionally has a transmission shaft serving as a countershaft, which is arranged parallel to the adjustment sleeve and the driver sleeve. The gearbox comprises a switching device with which different gear stages can be switched, which have different gear ratios (gear ratios) between the speed of rotation of the adjusting sleeve and the speed of rotation of the driver sleeve. For switching, the switching device has a switching element accessible from the outside of the housing. Depending on which switching stage is selected, the driving sleeve and with it the threaded spindle are rotated faster or slower by turning the adjusting sleeve at the same rotational speed. The rotation of the driver sleeve is recorded and displayed by the counter. This makes it possible to set a dosing volume in two different speed levels. A fast speed level enables a quick, coarse adjustment of the dispensing volume and a slow speed level enables simple and exact setting of the dispensing volume at the end of the setting process. The low structural complexity of the adjustment mechanism is advantageous, since the drive shaft and output shaft of the spur gear replace the adjustment sleeve previously used and are not added as additional components. Another advantage is the small footprint, since the driver sleeve and the adjustment sleeve can be integrated into the adjustment mechanism. The driving sleeve takes on the threaded spindle and the adjusting sleeve can be pushed onto the driving sleeve. As a result, no additional length section has to be made available in the housing of the pipette for the adjustment mechanism.

According to one embodiment of the invention, the adjusting sleeve or the driver sleeve has a plurality of toothings with different ones on the outer circumference Diameters, the transmission shaft has several teeth with different diameters and the switching device is designed to connect the transmission shaft with the adjusting sleeve or the driver sleeve in different switching stages via different pairs of teeth. In this embodiment, the rotation is transmitted in different switching stages via the transmission shaft. This type of design enables gear ratios that are smaller than 1: 1. As a result, the gearbox can be designed with a larger ratio between the largest and smallest gear ratio (spread) than in a gearbox in which the drive shaft and the output shaft are connected directly to one another in direct gear and no rotation is transmitted via the countershaft. According to a further embodiment, the gearbox is designed so that it cannot be shifted into a direct gear with a ratio of 1: 1. In this way, structural effort can be saved.

The diameter of the toothing is understood to mean the diameter of the rolling cylinders or rolling circles, the center of which falls in the center of two intermeshing spur gears and which touch each other at the rolling point of the two spur gears. The pitch circle corresponds to the pitch circle if the distance between two identical flanks on the pitch circle (pitch p) is determined by the standardized module m = p: π.

According to a further embodiment, the switching devices are designed to displace the adjusting sleeve and the transmission shaft or the transmission shaft and the driver sleeve relative to one another in the axial direction. According to this embodiment, at least one of the components adjusting sleeve, transmission shaft and driver sleeve can be displaced in the axial direction in the housing. According to a further embodiment, the switching device is an additional device which is coupled to at least one of the adjusting sleeve, transmission shaft and driver sleeve components in order to move two of these components relative to one another in the axial direction relocate. According to another embodiment, the adjusting sleeve or the transmission shaft or the driver sleeve is at the same time the switching device or a component of the switching device. In this embodiment, the adjustment sleeve or the transmission shaft or the driver sleeve is used at the same time as a switching device or as a component of a switching device in order to switch different switching stages of the gearbox.

According to another embodiment, the gearbox has a direct gear. In this embodiment, the gearbox has a gear stage in which the drive shaft is connected directly to the output shaft. In another switching stage, the rotary movement is transmitted from the drive shaft to the output shaft via the transmission shaft.

According to a further embodiment, the gearbox is designed with more than two gear stages. For this purpose, additional teeth can be arranged on the adjustment sleeve and on the transmission shaft. The manual transmission with more than two gear stages can be a manual transmission without a direct gear or a manual transmission with a direct gear.

According to a further embodiment, the driver sleeve has a first toothing on the outer circumference, the adjusting sleeve has a second toothing on the outer circumference and a third toothing above the second toothing, the second toothing having a different diameter than the third toothing, the transmission shaft one with the first toothing meshing fourth toothing, above a fifth toothing and above a sixth toothing, wherein the fifth toothing and the sixth toothing have different diameters, and the switching device is designed to move the adjusting sleeve and the transmission shaft in the axial direction relative to each other, so that optionally the second toothing in engagement with the fifth toothing and at the same time the third toothing out of engagement with the sixth toothing can be brought or the third toothing can be brought into engagement with the sixth toothing and at the same time the second toothing can be brought out of engagement with the fifth toothing, whereby the translation between the rotational speed of the adjusting sleeve and the rotational speed of the driver sleeve can be changed. Here, the first toothing is non-rotatably connected to the driver sleeve, the second and third teeth are non-rotatably connected to the adjusting sleeve and the fourth, fifth and sixth teeth are non-rotatably connected to the transmission shaft. In this embodiment, a toothing of the adjusting sleeve is in engagement with a toothing of the transmission shaft in various switching stages. Depending on the switching stage, different pairs of toothings are brought into engagement with one another. The rotation of the transmission shaft is transmitted to the driver sleeve via additional teeth. As a result, different translations between the adjustment sleeve and the driver sleeve and thus the threaded spindle and the counter are generated. The speed levels are determined by the teeth with different diameters on the adjustment sleeve and the teeth with different diameters on the transmission shaft. The threaded spindle is rotated faster or slower depending on which pair of teeth of the adjustment sleeve and transmission shaft is in engagement. According to a further embodiment, the gearbox is designed in such a way that it cannot be shifted into a direct gear with a ratio of 1: 1.

According to a further embodiment, the fourth toothing has the same diameter and the same number of teeth as the fifth toothing. In this embodiment, the ratio between the speed of rotation of the adjusting sleeve and the speed of rotation of the driving sleeve is 1: 1 if the second toothing has the same number of teeth and the same diameter as the first toothing and the second toothing meshes with the fifth toothing.

According to a further embodiment, the fourth toothing is also the fifth toothing. In this embodiment, the fourth toothing and the fifth toothing are combined into a single toothing. As a result, the fourth toothing and the fifth toothing have the same diameter and the same number of teeth. The fourth toothing meshes permanently with the first toothing and the second toothing can also be brought into engagement with the fourth toothing, which also forms the fifth toothing. So that the fourth toothing can mesh with the first toothing and the second toothing at the same time, it is formed over a sufficient length of the transmission shaft. According to another embodiment, the fourth toothing and the fifth toothing are different toothings. The fourth toothing and the fifth toothing can be arranged at a distance from one another or directly adjoin one another and have an offset to one another in the circumferential direction.

According to another embodiment, the fourth toothing and the fifth toothing have different diameters. The fourth toothing and the fifth toothing can be arranged at a distance from one another or directly adjacent to one another, a step being formed between the fourth toothing and the fifth toothing. As a result of the different diameters of the fourth toothing and the fifth toothing, the ratio between the speed of rotation of the adjusting sleeve and the speed of rotation of the driving sleeve deviates from 1: 1 when the second toothing meshes with the fifth toothing. This makes it possible to achieve ratios below 1: 1.

According to another embodiment, the fourth toothing and the fifth toothing have the same diameter and the same number of teeth, and the first toothing and the second toothing have different numbers of teeth and the same diameter. This results in a profile shift in the circumferential direction between the profiles of the first toothing and the second Interlocking achieved. As a result, the adjusting sleeve and the driver sleeve have different rotational speeds when the second toothing meshes with the fifth toothing. According to a further embodiment, the number of teeth of the first toothing and the second toothing differ by one tooth. According to a further embodiment, the second toothing has a larger number of teeth than the first toothing. This achieves a ratio between the speed of rotation of the adjusting sleeve and the speed of rotation of the driver sleeve of less than 1: 1. This embodiment is advantageous in terms of production technology compared to an embodiment in which the fourth toothing and the fifth toothing have different diameters.

According to a further embodiment, the counter has a drive gear which engages in a first toothing on the outer circumference of the driver sleeve. In this version, the counter is driven mechanically. The counter is preferably a mechanical counter, in particular a roller counter. In another embodiment, the counter is an electromechanical counter or an electronic counter. The electromechanical counter or the electronic counter can also be controlled by electrical pulses that are generated by a sensor that detects the rotation of the driver sleeve. The rotation of the driver sleeve can also be detected indirectly by detecting the rotation of the threaded spindle. The rotation of the driver sleeve denotes its position in relation to an initial position, which can be specified in the number of full or partial rotations or in degrees.

According to a further embodiment, the adjustment sleeve is arranged concentrically to the driver sleeve. According to a further embodiment, the adjustment sleeve is pushed onto the driver sleeve. This results in a particularly compact design.

According to a further embodiment, the switching device is designed to move the adjusting sleeve in the axial direction relative to the housing in order to selectively engage the second toothing in engagement with the fifth toothing and at the same time the third toothing out of engagement with the sixth toothing or the third toothing in engagement with the To bring the sixth toothing and at the same time the second toothing out of engagement with the fifth toothing. This makes it possible to switch different switching stages by displacing the adjusting sleeve somewhat out of the housing or into it. According to a further embodiment, the switching device is a switching device which is coupled to the adjusting sleeve and designed separately therefrom and which is designed to displace the adjusting sleeve in the axial direction. According to another embodiment, the adjusting sleeve is at the same time the switching device or a component thereof. In this embodiment, a section of the adjusting sleeve protruding from the housing can be used as a switching element. By gripping the section and moving the adjusting sleeve deeper into the housing or further out of the housing, the switching element can be actuated in order to shift the gearbox into different gear stages. In this embodiment, the setting sleeve is used both for switching different switching stages and for setting the dosing volume.

According to a further embodiment, the switching device is designed to move the transmission shaft in the axial direction relative to the housing in order to selectively engage the second toothing in engagement with the fifth toothing and at the same time the third toothing out of engagement with the sixth toothing or the third toothing in engagement with the To bring the sixth toothing and at the same time the second toothing out of engagement with the fifth toothing. In this way, it can be avoided that the metering volume is unintentionally adjusted when the gearbox is switched or the gearbox is unintentionally switched when the metering volume is set. According to a further embodiment, the switching device is one with the transmission shaft coupled and separately formed switching device, which is designed to move the transmission shaft in the axial direction. According to another embodiment, the transmission shaft is the switching device or a component thereof. According to a further embodiment, a section of the transmission shaft or a switching lever coupled to the transmission shaft protrudes outward from the housing. A section of the transmission shaft or shift lever that protrudes from the housing is a shift element that can be actuated from the outside in order to shift the gearbox into different shift stages.

Another embodiment has a first spring device which is supported in the housing and on the lifting rod or the displacement element and which holds the lifting rod with the stop element in contact with the first stop when the operating button is relieved. This ensures that the lifting rod is automatically displaced upwards after the control button is relieved of pressure until the stop element rests against the upper stop. According to another embodiment, the lifting rod is displaced by means of the control button or another control element after reaching the lower stop and possibly executing an overstroke until the stop element rests on the upper stop.

According to a further embodiment, the pipette has a device for setting a preferred position which sets the switching device to a specific switching stage. This allows the user to assume that the pipette is set to a certain switching stage before using it.

According to a further embodiment, the device for setting a preferred position is a second spring device.

According to a further embodiment, the transmission shaft is arranged in a free space between the adjustment sleeve and the counter. According to a further embodiment, the transmission shaft is in a wedge-shaped space between the adjustment sleeve and the counter. This reduces the space required by the adjustment mechanism.

According to a further embodiment, the counter has counter rollers with an axis of rotation parallel to the adjustment sleeve. According to a further embodiment, the counter is a roller counter. According to a further embodiment, the transmission shaft is arranged in a wedge-shaped free space between the counter rollers and the adjustment sleeve.

According to a further embodiment, the adjusting element is an adjusting ring at the upper end of the adjusting sleeve. The dosing volume can be adjusted by turning the setting ring, which is accessible from the outside of the housing. The adjusting ring at the upper end of the adjusting sleeve can at the same time be the switching element of the switching device.

According to another embodiment, the control button and the setting sleeve are connected to one another in a rotationally fixed manner and axially displaceable relative to one another via a device for rotationally fixed connection, so that the control button is at the same time the setting element for setting the setting sleeve.

According to another embodiment, the switching element is a slide or switch that can be actuated from the outside of the housing.

According to a further embodiment, the displacement device comprises a displacement chamber in the form of a cylinder and a displacement element in the form of a piston which can be displaced in the cylinder.

Fig. 1

eine erfindungsgemäße Pipette in einem Längsschnitt von der linken Seite;

Fig. 2

dieselbe Pipette in einem Längsschnitt von der rechten Seite;

Fig. 3.1 bis 3.4

einen Einstellmechanismus derselben Pipette vergrößert in einer Seitenansicht von der rechten Seite (Fig. 3.1), in einer Vorderansicht (Fig. 3.2), in einer Seitenansicht von der linken Seite (Fig. 3.3) und in einer Rückansicht (Fig. 3.4);

Fig. 4.1 bis 4.4

denselben Einstellmechanismus in eine anderen Schaltstufe geschaltet vergrößert in einer Seitenansicht von der rechten Seite (Fig. 4.1), in einer Vorderansicht (Fig. 4.2), in einer Seitenansicht von der linken Seite (Fig. 4.3) und in einer Rückansicht (Fig. 4.4);

Fig. 5.1 bis 5.4

denselben Einstellmechanismus auseinandergezogen in einer Seitenansicht von der rechten Seite (Fig. 5.1), in einer Vorderansicht (Fig. 5.2), in einer Seitenansicht von der linken Seite (Fig. 5.3) und in einer Rückansicht (Fig. 5.4);

Fig. 6

erste und zweite Verzahnung mit unterschiedlichen Zähnezahlen bei gleichen Durchmessern in einer Draufsicht;

Fig. 7.1 bis 7.4

einen anderen Einstellmechanismus mit einem Schalthebel vergrößert in einer Seitenansicht von der rechten Seite (Fig. 7.1), in einer Vorderansicht (Fig. 7.2), in einer Seitenansicht von der linken Seite (Fig. 7.3) und in einer Rückansicht (Fig. 7.4);

Fig. 8.1 bis 8.4

denselben Einstellmechanismus in eine andere Schaltstufe geschaltet vergrößert in einer Seitenansicht von der rechten Seite (Fig. 8.1), in einer Vorderansicht (Fig. 8.2), in einer Seitenansicht von der linken Seite (Fig. 8.3) und in einer Rückansicht (Fig. 8.4).

The invention is explained in more detail below with reference to the accompanying drawings of an exemplary embodiment. In the drawings show:

Fig. 1

a pipette according to the invention in a longitudinal section from the left side;

Fig. 2

the same pipette in a longitudinal section from the right side;

Fig. 3.1 to 3.4

an adjustment mechanism of the same pipette enlarged in a side view from the right side ( Fig. 3.1 ), in a front view ( 3.2 ), in a side view from the left side ( Fig. 3.3 ) and in a rear view ( Fig. 3.4 );

Fig. 4.1 to 4.4

the same adjustment mechanism switched to another gear stage, enlarged in a side view from the right side ( Fig. 4.1 ), in a front view ( Fig. 4.2 ), in a side view from the left side ( Fig. 4.3 ) and in a rear view ( Fig. 4.4 );

Fig. 5.1 to 5.4

the same adjustment mechanism pulled apart in a side view from the right side ( Fig. 5.1 ), in a front view ( Fig. 5.2 ), in a side view from the left side ( Fig. 5.3 ) and in a rear view ( Fig. 5.4 );

Fig. 6

first and second toothing with different numbers of teeth with the same diameters in a plan view;

Fig. 7.1 to 7.4

another adjustment mechanism with a shift lever enlarged in a side view from the right side ( Fig. 7.1 ), in a front view ( Fig. 7.2 ), in a side view from the left side ( Fig. 7.3 ) and in a rear view ( Fig. 7.4 );

Fig. 8.1 to 8.4

the same adjustment mechanism switched to another gear stage, enlarged in a side view from the right side ( Fig. 8.1 ), in a front view ( Fig. 8.2 ), in a side view from the left side ( Fig. 8.3 ) and in a rear view ( Fig. 8.4 ).

In the present application, the terms “top” and “bottom”, “above” and “below”, “top view” and “bottom view” relate to terms derived therefrom such as “bottom” and “top” and “horizontal” and “vertical” "to an orientation of the pipette in which the housing with the seat is oriented vertically downwards. In this orientation, a pipette tip attached to the seat can be aimed at a vessel located below in order to aspirate or dispense liquid.

According to Figs. 1 and 2 a pipette 1 according to the invention has a rod-shaped housing 2 with a lower housing part 3 and an upper housing part 4. The lower housing part 3 has a tubular base 5 with a conical bottom, from which a slender tubular, slightly conical extension 6 protrudes at the bottom has a seat 7 for attaching a pipette tip 8. In the extension 6, a displacement chamber 9 is formed in the form of a cylinder, which is connected via a connecting channel 10 to an opening 11 in the underside of the seat 7.

The lower housing part 3 also comprises a displacement element 12 in the form of a piston of the displacement device, which is guided into the cylinder 11 via a sealing system 13 on the top of the base. The displacement element 12 has at the upper end a plate 14 which has a central dome-shaped depression on the upper side. A first spring device 15 in the form of a helical spring is arranged between the plate 14 and the top of the base. The first spring device 15 presses the plate 14 from below against a closure cap 16 which is connected to the base body 5 and has a passage in the center through which the plate 14 is accessible from above.

The upper housing part 4 contains a lifting rod 17 which rests on the upper side of the plate 14. The lower end of the lifting rod 17 engages in the recess of the plate 14. At the top of the lifting rod 17, an operating button 18 is fixed, which protrudes from the upper end of the housing 2 to the outside.

The lifting rod 17 is passed through a central spindle bore 19 of a threaded spindle 20, which is arranged in the upper housing part 4. The threaded spindle 20 has on the outside an external thread 21 which can be screwed into an internal thread 22 of a lifting body 23 which is held at the bottom on a first carrier 24 in the upper housing part 4. The lifting body 23 forms a spindle nut.

The lower end face of the threaded spindle 20 is an upper stop 25 for a stop element 26 in the form of an annular bead on the outer circumference of the lifting rod 17.

The threaded spindle 20 is non-rotatably connected at the upper end to a driver 27, which by means of radially outwardly projecting ribs 28 (cf. Fig. 5 ) engages in axial grooves 29 of a driver sleeve 30. The driver sleeve 30 is arranged concentrically to the threaded spindle 20 and is rotatably mounted on the outer circumference of the lifting body 23. The driver sleeve 30 has a circumferential first toothing 31 at the lower edge on the outer circumference. This is particularly evident in FIG Figures 3 to 5 shown.

An adjusting sleeve 32 is pushed onto the driver sleeve 30. The adjustment sleeve 32 is rotatably mounted on the outer circumference of the driver sleeve 30 and is guided on the driver sleeve 30 so that it can be displaced in the axial direction between two limits. The upper end of the adjusting sleeve 32 projects outward from the upper end of the housing 2. There, the adjusting sleeve 32 has an adjusting ring 33 on the outer circumference, which has a corrugation on the outer circumference.

The adjusting sleeve 32 has on the lower edge a circumferential second toothing 34 and a little further up a circumferential third toothing 35. The first toothing 31 and the second toothing 34 have the same diameter and the same number of teeth. The third toothing 35 has a larger diameter and a larger number of teeth than the second toothing 34.

The second toothing 34 is on the upper side and the third toothing 35 is closed on the underside by an intermediate disk 36. The underside of the disk 36 forms a lower limit 37 and the upper side of the disk 36 forms an upper limit 38 for the displacement of the adjusting sleeve 32.

In addition to the driver sleeve 30 and the adjustment sleeve 32, a transmission shaft 39 is rotatably mounted on the first carrier 24. The transmission shaft 39 is provided at the bottom with a fourth toothing 40, above it with a fifth toothing 41 and above it with a sixth toothing 42. The fourth toothing 40 and the fifth toothing 41 have the same diameter and the same number of teeth and are combined into a single toothing 43. The sixth toothing 42 is arranged at a distance from the fifth toothing 41. It has a smaller diameter and a smaller number of teeth than the fifth toothing 41.

The transmission shaft 39 is rotatably mounted at the top in a second carrier 44 which is fixed in the upper housing part 4.

In addition, a counter 45 in the form of a roller counter is held between the first carrier 24 and the second carrier 44. A counting roller axle 46 of the roller counter is mounted at the bottom in the first carrier 24 and at the top in the second carrier 44. The second carrier 44 is supported at the top on a projection in the housing. In addition, a drive gear 47 is rotatably mounted on the first carrier 24, which has two spur gears 48, 49 with different diameters on one common shaft includes. The spur gear 48 with the smaller diameter meshes with the first toothing 31 of the driver sleeve 30 and the spur gear 49 with the larger diameter meshes with a drive pinion 50 on an initial roller of the roller counter.

The number rollers 51 of the counter 45 are visible from the outside of the housing 2 through a window 52 in the upper housing part 4, which has a transparent cover 53 (cf. Fig. 2 ).

In the upper housing part 4, a cup-shaped holder 54 is arranged below the lifting body 23. The holder 54 has an external thread 55 which is screwed into an internal thread 56 of a third carrier 57 fastened in the housing 2.

The holder 54 contains a cap-shaped lower stop 58 which is held under a downwardly curved upper edge 59 of the holder 54. An overtravel spring 60 in the form of a helical spring, which is supported on the bottom 61 of the holder 54, presses the lower stop 58 against the upper edge 59 The bottom 61 of the holder 54 is passed through.

The setting sleeve 32 is a drive shaft, the driver sleeve 30 is an output shaft and the transmission shaft 39 is a countershaft of a gearbox 63 designed as a spur gear 62. Switching between the various gear stages is achieved by axially moving the setting sleeve 32 into an in Fig. 3 and 4th shown lower switching position (fine adjustment position) and in an in Fig. 4 The upper switching position shown (quick adjustment position) causes. In the fine adjustment position of Fig. 3 the adjusting sleeve 32 is shifted downwards at most up to the abutment of the lower limit 37 on the upper side of the fifth toothing 41 and in the quick adjustment position the adjusting sleeve 32 is up to the abutment the upper limit 38 on the underside of the sixth toothing 42 shifted upwards. Thus, the adjusting sleeve 32 is at the same time a shifting device 64 of the gearbox, the adjusting ring 33 being a shifting element 65 of the shifting device 64.

In the exemplary embodiment, the gearbox 63 does not have a preferred position, so that the gearbox always retains the gear stage that was last set. The invention includes other types of embodiment with a preferred position of the gearbox, which are implemented, for example, by means of a second spring device.

When the setting sleeve 32 is rotated, the driving sleeve 30 is rotated along with it in accordance with the switching stage set in each case. With the driver sleeve 30, the threaded spindle 20 is screwed into the internal thread 22 fixed to the housing and the upper stop 25 moves up or down depending on the direction of rotation. This adjusts the distance between the upper stop 25 and the lower stop 58, which determines the dosing volume. The metering volume set in each case can be read off on the counter 45, which is driven by the drive sleeve 30 via the drive gear 47.

At the upper edge area of the upper housing part 4, next to the setting sleeve 32, there is an ejector button 66 on an ejector rod 67. The ejector rod 67 runs parallel to the lifting rod 17 through the upper housing part 4. Its lower end is connected to a lateral fastening attachment 68 of an ejector sleeve 69, which is arranged displaceably on attachment 6.

An ejector spring 70, designed as a helical spring, is arranged in the upper housing part 4, which is supported at one end in the housing 2 and at the other end engages the ejector rod 67. The ejector spring 70 presses the ejector rod 67 upwards, so that the ejector sleeve 67 rests against the extension 6.

The lower housing part 3 and the upper housing part 4 are connected to one another by a snap connection 71.

Before pipetting, the user can set the desired dispensing volume. To do this, he turns the setting ring 33 until the desired dosing volume is displayed by the counter 45. The user can choose between two speed levels for setting the dosing volume. In particular, if the last set dosing volume deviates significantly from the dosing volume to be set, the user can first select a fast switching level. If the gearbox is not already set to the fast gear stage, the user grips the setting ring 33 and pulls the setting sleeve 32 out of the fine adjustment position Fig. 3 a little further out of the housing 2 into the in Fig. 4 shown quick adjustment position.

In the quick adjustment position, the first toothing 31 of the driver sleeve 30 meshes with the fourth toothing 40 of the transmission shaft 39 and meshes the third toothing 35 of the adjusting sleeve 32 with the sixth toothing 42 of the transmission shaft 39. This increases the rotational speed of the adjusting sleeve 32 to a higher rotational speed of the driving sleeve 30 translated so that the user can quickly set the dispensing volume close to the dispensing volume to be set.

The user can select a slow switching level for the precise setting of the desired dispensing volume. To do this, he presses the adjusting sleeve 32 deeper into the housing 2 on the adjusting ring 33, up to the in Fig. 3 Fine adjustment position shown. In this position, the first toothing 31 meshes with the fourth toothing 40 and the second toothing 34 with the fifth toothing 41 Speed than in the fast switching stage. In the toothing of the exemplary embodiment, the speed of rotation of the adjusting sleeve 32 is equal to the speed of rotation of the driver sleeve 30, since the first toothing 31 and the second toothing 34 as well as the fourth toothing 40 and the fifth toothing 41 each have the same number of teeth and diameter.

Before or after the precise setting of the dosing volume, the user can clamp a pipette tip 8 onto the pipette 1 by pressing the pipette 1 with the seat 7 into the upper opening 72 of the pipette tip 8. For pipetting, he first presses the operating button 18 downwards, so that the stop element 26 is displaced from the upper stop 25 against the lower stop 58. Here, the lifting rod 17 presses the displacement element 12 downwards and the first spring device 15 is pretensioned. The user then dips the lower opening 73 of the pipette tip 8 into the sample liquid and relieves the pressure on the control button 18. A quantity of liquid corresponding to the set dosing volume is sucked into the pipette tip 8.

To dispense the amount of liquid, the user holds the pipette tip 8 with the lower opening 73 over another vessel and presses the control button 18 downwards again. After reaching the lower stop 58, he can press the operating button 18 even deeper, overcoming the resistance of the overtravel spring 60, in order to eject a residual amount of liquid from the pipette tip 8.

A further quantity of liquid can then be pipetted in the same way or, to change the sample liquid, the pipette tip 8 can be ejected by pressing the ejector button 66 downwards. Here, the ejector sleeve 69 strips the pipette tip 8 from the seat 7. After the discharge of the Ejector button 66 displaces the ejector spring 70 the ejector rod 67 back into the starting position shown.

Further pipetting operations can then be carried out with the same set dispensing volume or with a newly set dispensing volume, the setting being made as described above.

the Fig. 6 shows the first and second toothing 31 ', 34' of a further embodiment. This differs from the previously described ones in that the first toothing 31 'and the second toothing 34' have the same diameter, although the first toothing 31 'has one tooth less than the second toothing 34'. As a result, the first toothing 31 'has a larger pitch than the second toothing 34'. The top view shows that, as a result, there is a profile shift of the teeth between the first toothing 31 'and the second toothing 34'.

In this embodiment too, the fourth toothing 40 and the fifth toothing 41 each have the same diameter and the same number of teeth. When the slow switching stage is switched on, this has the consequence that, with one revolution of the adjusting sleeve 32, the driver sleeve 30 performs a little less than one revolution. As a result, the speed of rotation of the adjusting sleeve 32 is greater than the speed of rotation of the driving sleeve 30. In the high-speed switching stage, with one revolution of the adjusting sleeve 32, the driving sleeve 30 is rotated as in the above embodiment. Overall, a somewhat larger spread of the ratios is achieved.

The adjustment mechanism of Fig. 7 and 8th differs from the adjustment mechanism of Fig. 3 and 4th in that it is not the adjusting sleeve 32 but the transmission shaft 39 which is held axially displaceably in the housing 2, which is a component of the switching device 64. Accordingly, two prevent Limits the displacement of the adjusting sleeve 32 in the axial direction. The displacement of the transmission shaft 39 in the axial direction is made possible by the fact that it engages with its two ends in bearings in the first carrier 24 and in the second carrier 44, which allow a corresponding displacement.

A switching lever 74 is seated on the transmission shaft 39 and protrudes perpendicularly outward from the transmission shaft 39. The switching lever 74 is the switching element 65 of the switching device 64. The switching lever 74 is held in a groove on the circumference of the transmission shaft 39. For this purpose, the switching lever 74 is snapped onto the transmission shaft 39 with a fork-shaped end, for example. The shift lever 74 engages in the annular groove in such a way that by moving the shift lever 74 in the axial direction, the transmission shaft can be shifted upwards and downwards and the transmission shaft 39 can be rotated with respect to the shift lever 74.

With one outer end, the switching lever 74 consists of a vertical slot in the housing 2 so that it can be displaced from the outside.

By placing the underside of the fourth toothing 40 on the first carrier 24, the transmission shaft 39 is displaced downwards (cf. Fig. 8 ) and when the shift lever 74 rests on the second carrier 44, the upward displacement of the transmission shaft 39 is limited (cf. Fig. 7 ).

In Fig. 7 the switching device 64 is switched to the fine adjustment position, in which a rotation of the adjusting sleeve 32 causes a slow adjustment of the threaded spindle 20. In Fig. 8 the switching device 64 is switched to the quick adjustment position, in which a turning of the adjusting sleeve 32 effects a quick adjustment of the threaded spindle 20.

In addition, the adjustment mechanism of Fig. 7 and 8th same properties as the adjustment mechanism of Fig. 3 and 4th on.

Claims (19)

1. A pipette with an adjustable dosing volume, comprising:

   - a rod-shaped housing (2),

   - at least one seat (7) for releasably holding a pipette tip (8) to a lower end of the housing (2),

   - a displacement device comprising a displacement chamber (9) fixedly arranged in the housing (2) having a displacement element (12) displaceable therein,

   - a connecting channel (10) connecting the displacement chamber (9) to an opening (11) in the seat (7),

   - a stroke rod (17) coupled at the bottom end to the displacement element (12) and displaceable in the longitudinal direction in the housing (2) for displacing the displacement element (12) in the displacement chamber (9),

   - a control button (18) connected to the upper end of the stroke rod (17) and projecting from the housing (2),

   - a stop element (26) on the outer circumference of the stroke rod (17),

   - a threaded spindle (20) that has a central spindle hole (19) through which the stroke rod (17) is guided and that has an upper stop (25) at the bottom for the stop element (26),

   - an inner thread (22) arranged in a fixed position within the housing (2) in which the threaded spindle (20) engages by an outer thread (21),

   - a lower stop (58) arranged below the upper stop (25) at a distance therefrom for the stop element (26),

   - a catch sleeve (30) rotatably mounted in the housing (2) that has at least one groove (29) running in a longitudinal direction on the inner circumference in which at least one catch (27) of the threaded spindle (20) engages,

   - a counter (45) for displaying the dosing volume that is designed and arranged to detect the rotation of the catch sleeve (30),

   - an adjusting sleeve (32) rotatably mounted in the housing (2),

   - an adjusting element (33) accessible from the outside of the housing and connected to the adjusting sleeve (32),

   - a transducer shaft (39) rotatably mounted in the housing and parallel to the adjusting sleeve (32) and the catch sleeve (30),

   - wherein the adjusting sleeve (32) has an input shaft, the catch sleeve (30) has an output shaft, and the transducer shaft (39) has a countershaft of a gearbox (63) designed as a spur gearbox (62) that has a shifting device (64) with a shift element (65) accessible from the outside of the housing (2), wherein the gearbox (63) is designed, by actuating the shift element (65), to shift various shift stages with different gear ratios between the rotational speed of the adjusting sleeve (32) and the rotational speed of the catch sleeve (30).
2. The pipette according to claim 1, wherein the adjusting sleeve (32) or the catch sleeve (30) on the outer circumference has a plurality of toothings (34, 35) with different diameters, the transducer shaft (39) has a plurality of toothings with different diameters (41, 42), wherein the shifting device (64) is designed to connect the transducer shaft (39) with the adjusting sleeve (32) or catch sleeve (30) in various shifting stages by various pairs of toothings (34, 35; 41, 42).
3. The pipette according to claim 1 or 2, wherein the catch sleeve (32) has a first toothing (31) on the outer circumference, the adjusting sleeve (32) has a second toothing (34) on the outer circumference and a third toothing (35) above the second toothing, wherein the second toothing (34) has a different diameter than the third toothing (35), the transducer shaft (39) has a fourth toothing (40) engaging with the first toothing (31), thereabove a fifth toothing (41) and thereabove a sixth toothing (42), wherein the fifth toothing (41) and the sixth toothing (42) have different diameters, and the shifting device is designed to displace the adjusting sleeve (32) and the transducer shaft (39) in an axial direction relative to each other so that optionally, the second toothing (34) can be brought into engagement with the fifth toothing (41), and the third toothing (35) can simultaneously be brought out of engagement with the sixth toothing (42), or the third toothing (35) can be brought into engagement with the sixth toothing (42) and simultaneously the second toothing (34) can be brought out of engagement with the fifth toothing (41), wherein the transmission ratio between the rotational speed of the adjusting sleeve (32) and the rotational speed of the catch sleeve (30) can be altered.
4. The pipette according to claim 3, wherein the fourth toothing (37) has the same diameter and the same number of teeth as the fifth toothing (41).
5. The pipette according to claim 4, wherein the first toothing (31) and the second toothing (34) have the same number of teeth and the same diameter.
6. The pipette according to claim 4, wherein the first toothing (31) and the second toothing (34) have a different number of teeth and the same diameter.
7. The pipette according to claim 3, wherein the fourth toothing (40) and the fifth toothing (41) have different diameters.
8. The pipette according to one of claims 1 to 7, wherein the counter (45) has a drive gear (47) that engages in a first toothing (31) on the outer perimeter of the catch sleeve (30).
9. The pipette according to one of claims 1 to 8, wherein the adjusting sleeve (32) is shoved onto the catch sleeve (30).
10. The pipette according to one of claims 1 to 9, wherein the shifting device (64) is designed to displace the adjusting sleeve (32) in an axial direction relative to the housing (2) and optionally bring the second toothing (34) into engagement with the fifth toothing (41) and simultaneously the third toothing (35) out of engagement with the sixth toothing (42), or the third toothing (35) into engagement with the sixth toothing (42), and simultaneously the second toothing (34) out of engagement with the fifth toothing (41).
11. The pipette according to one of claims 1 to 10, wherein the shifting device (64) is designed to displace the transducer shaft (39) in an axial direction relative to the housing (2) and optionally bring the second toothing (34) into engagement with the fifth toothing (41) and simultaneously the third toothing (35) out of engagement with the sixth toothing (42), or the third toothing (35) into engagement with the sixth toothing (42), and simultaneously the second toothing (34) out of engagement with the fifth toothing (41).
12. The pipette according to one of claims 1 to 11 that has a first spring device (15) braced in the housing (2) and against the stroke rod (17) or the displacement element (12) that holds the stroke rod (17) in contact with the top stop (25) when the control button (18) with the stop element (25) is released.
13. The pipette according to one of claims 1 to 12 that has a device for adjusting a preferential position that adjusts the shifting device (64) into a certain shifting stage.
14. The pipette according to claim 13, wherein the device is for adjusting a preferential position of a second spring device.
15. The pipette according to one of claims 1 to 14, wherein the transducer shaft (39) is arranged in a free space between the adjusting sleeve (32) and the counter (45).
16. The pipette according to one of claims 1 to 15, wherein the counter (45) has counter rollers (51) with a rotational axis parallel to the adjusting sleeve (32).
17. The pipette according to one of claims 1 to 16, wherein the adjusting element is an adjusting ring (33) at the upper end of the adjusting sleeve (32).
18. The pipette according to one of claims 1 to 17, wherein the adjusting sleeve (32) is displaceable in an axial direction in the housing (2), and the shift element (65) is arranged on the top end of the adjusting sleeve (32).
19. The pipette according to one of claims 1 to 16, wherein the control button (18) and the adjusting sleeve (32) are connected to rotate conjointly by a device for connecting for conjoint rotation, and are connected with each other so as to be displaceable relative to each other in an axial direction so that the control button (18) is simultaneously the adjusting element for adjusting the adjusting sleeve (32).

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