Pipette with adjustable dispensing volume

Abstract

The invention relates to a pipette comprising a rod-shaped housing, at least one seat for releasable holding of a pipette tip on a lower end of the housing, an expelling device comprising an expelling chamber with an expelling element, a connection channel connecting the expelling chamber with an opening in the seat, a travel lever movable in longitudinal direction in the housing, an operating button connected with an upper end of the travel lever and protruding from the housing, a stop element on an outer circumference of the travel lever, an upper stop for the stop element and a lower stop for the stop element, an adjustment device for adjusting the position of the upper stop in the housing, a display device for displaying an adjusted delivery volume, wherein between the adjustment device and the display device there is a form-locking coupling device which is configured to couple the adjustment device with the display device in an engaged state and to decouple the adjustment device from the display device in a disengaged state.

Description

TECHNICAL FIELD

[0001] The present invention relates to a pipette with an adjustable dispensing volume. BACKGROUND

[0002] Pipettes are used for dispensing liquids, in particular in laboratories. For this purpose, a pipette tip is clamped with its upper end on a seat of the pipette. The seat is mostly a conical or cylindrical protrusion from the housing of the pipette, through the upper opening of which the tubular body of the pipette tip can be clamped. Through the lower opening of the tubular body of the pipette, the pipette tip can take up and discharge liquids. Air displacement pipettes comprise a displacement device for air, which is connected in communication with the pipette tip through an opening in the seat. By means of the displacement device, an air cushion is moved, so that liquid is sucked into the pipette tip and pushed out of the pipette tip. For this purpose, the displacement device has a displacement chamber with a displaceable displacement element. The displacement device is mostly a cylinder with a piston that can be moved therein.

[0003] After use, the pipette tip is separated from the seat and a new pipette tip is exchanged. Thereby, contamination by liquid transfer can be avoided at the subsequent dispensing. The pipette mostly has a removal device, which enables the removal of the pipette tip by actuating a button without holding the pipette tip. Pipette tips for single use are mostly made of plastic.

[0004] The piston is coupled with a drive device for moving the piston in the cylinder. The drive device has a stroke rod, which can be moved with a stop element between an upper stop and a lower stop. At the beginning of the suction of air into the cylinder, the stop element is located on the lower stop. At the beginning of the expulsion of air from the cylinder, the stop element is resting on the upper stop. The quantity of liquid taken up or discharged is related to the stroke of the stroke rod between the lower stop and the upper stop.

[0005] In fixed-volume pipettes, the distance between the upper stop and the lower stop is constant. In pipettes with an adjustable dispensing volume, the position of the upper stop can be varied. Known pipettes have an upper stop on the underside of a spindle, which can be adjusted in a spindle nut fixedly arranged in the housing. In order to adjust the spindle, there is an adjustment device coupled with a display device in the form of a counter for displaying the adjusted dispensing volume.

[0006] Patent documents DE 43 35 863 C1, EP 0 649 678 B1 and US 5,531,131 describe a pipette in which a handling button projects from the upper part of the housing and is connected with the upper end of a stroke rod, which is connected at the lower end with a piston. The stroke rod is guided through a through passage of a screw spindle and a lower stop. The stroke rod has a stop element in the form of an outwardly projecting lug, which limits the movement of the stroke rod between an upper stop and the lower stop on the lower part of the screw spindle. By pressing the handling 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 releasing the handling element, the piston returns into its initial position due to the action of the return spring, in which the stop element rests against the screw spindle. An adjustment device for adjusting the screw spindle has an adjustment sleeve rotatably supported in the housing, which projects from the upper part of the housing and in which the handling button is axially movable. The adjustment sleeve is rotationally fixedly connected with the screw spindle by an axial groove on the inner periphery of the adjustment sleeve and a driving element projecting radially from the upper end of the screw spindle. By rotation of the adjustment sleeve, the screw spindle can be adjusted together with the upper stop and thus the delivery volume. The adjustment sleeve has a spur gear on the lower end, which is positively coupled with the spur gear of a counter by a coupling device having two coupling spur gears on a common shaft. The shaft supporting the two coupling spur gears can be moved by means of a switching device to decouple the coupling device. Thereby a factory calibration of the pipette is achieved. Disadvantageously, this calibration requires an iterative method, since the adjustment of the upper stop by rotation on the upper end of the adjustment sleeve is not accurate without measuring the corresponding adjusted stroke.

[0007] A known factory calibration is described in the above documents, in which a slip coupling between the adjustment device for the piston stroke and the counter is adjusted. For this purpose, there is an opening in the pipette housing through which a screwdriver can be guided onto the slip coupling consisting of a set of bevel gears. By setting a fixed volume and rotating the screwdriver or vice versa, the volume setting and the coupling of the counter can be changed. The accuracy deviation achieved thereby (difference between the contained and displayed liquid volume) can be checked by weighing the quality of the pipetting. Disadvantageously, the adjustment of the pipette correction factor cannot be well accessed from the outside and is mostly only used for factory adjustment or in exceptional cases by the user. Furthermore disadvantageously, the frictional engagement elements of the slip coupling are permanently rotated together when adjusting the counter, so that the stroke rod system needs to be fixed so that it is not moved. Furthermore, the permanent frictional contact of the frictional engagement elements leads to significant wear in the system.

[0008] The patent documents DE 10 2005 033 378 B4, EP 1 743 701 B1 and US 8,133,453 B2 describe pipettes of the type described above, which additionally have an adjustment device for adjusting the position of the holder holding the lower stop relative to the cylinder and a display device for displaying the position of the holder. Thereby, the changing of the calibration and the re-finding of the factory calibration is simplified for the user.

[0009] The patent documents DE 10 2012 003 846 B and EP 2 633 915 B1 describe a pipette, in which the adjustment device for adjusting the position of the lower stop has a structure which is realized with fewer components compared to the pipettes described above, thereby realizing a calibration with better calibration accuracy for the user. SUMMARY

[0010] On the basis thereof, it is the object of the present application to realize a pipette which simplifies the calibration.

[0011] This object is achieved by a pipette according to the application.

[0012] The pipette according to the application with an adjustable dispensing volume comprises:

[0013] • a rod-shaped housing,

[0014] • at least one seat for releasably holding a pipette tip on a lower end of the housing,

[0015] • a displacement device, which comprises a displacement chamber with a displaceable displacement element,

[0016] • a connection channel connecting the displacement chamber with an opening in the seat,

[0017] • a travel lever for moving the displacement element in the displacement chamber, which is coupled to the displacement element on the lower end and is displaceable in the longitudinal direction in the housing,

[0018] • an operating button connected to the upper end of the travel lever and protruding from the housing,

[0019] • a stop element on the outer periphery of the travel lever,

[0020] • an upper stop for the stop element and a lower stop for the stop element for limiting the travel of the travel lever,

[0021] • an adjustment device for adjusting the position of the upper stop in the housing,

[0022] • a display device for displaying the adjusted dispensing volume,

[0023] • characterized in that a form-locking coupling device between the adjustment device and the display device, the coupling device being configured to couple the adjustment device with the display device in an engaged state and to decouple the adjustment device from the display device in a decoupled state.

[0024] In the pipette according to the application, the calibration (correction) by the service personnel and by the customer in the factory is significantly simplified. This is achieved in that the display device can be adjusted in the decoupled state of the form-locking coupling device, without the stroke of the stroke lever adjusted by means of the adjustment device being changed at the same time. That is, by decoupling the form-locking coupling device, the adjustment device is separated from the display device, so that the position of the upper stop is not adjusted by adjusting the display device by means of the correction device. Since the coupling device between the adjustment device and the correction device is a form-locking coupling device, it is ensured that the adjustment of the display device is not transmitted to the upper stop in the decoupled state. For this purpose, it is not necessary to secure the upper stop or the stroke lever system by additional measures, for example by means of a tool introduced from the outside, fixing or locking. Furthermore, there is no wear in the coupling device when adjusting the display device. The correction is simplified in that the display device can be adjusted directly to the result of the gravimetric measurement, whereby a significant time saving is achieved with respect to an iterative method. Furthermore, the application enables the adjustment of the position of the display device and the upper stop independently of one another. For this purpose, the display device can be adjusted in the decoupled state of the coupling device and the position of the upper stop is adjusted by means of the adjustment device independently thereof.

[0025] According to an embodiment of the application, the coupling device is configured such that it can be decoupled and coupled from the outside of the housing. This enables the calibration of the pipette without having to open or disassemble the pipette for this purpose. However, the application also comprises embodiments in which the coupling device is configured such that it can only be decoupled and coupled if the housing is opened or the pipette is disassembled. For this purpose, for example, the components of the pipette can be assembled on the housing and the housing can consist of several housing parts which can be partially removed for the calibration, and / or the components of the pipette can be completely or partially assembled on a chassis (frame) of the pipette which can be removed from the housing for the calibration.

[0026] According to a further embodiment, the coupling device is configured such that it can be decoupled and coupled by inserting a correction tool into the housing from the outside of the housing. By using a correction tool, the decoupling and coupling of the coupling device is simplified and an unintentional decoupling and coupling is prevented. According to a further embodiment, the coupling device is coupled with a mechanical switch or another actuating device which can be actuated from the outside of the housing, so that the coupling device can be decoupled and coupled by actuating the actuating device.

[0027] According to a further embodiment, the pipette comprises a correction device which is configured to change the setting of the display device when the coupling device is uncoupled. By means of the correction device the adjustment of the display device can be simplified. For this purpose, according to a further embodiment, the correction device is configured such that the setting of the display device can be changed from the outside of the housing. In an alternative embodiment, in the state in which the coupling device is uncoupled, the setting of the display device can be changed by directly adjusting the display device. This is possible, for example, in a display device which is configured as a (roller) counter. For this purpose, for example, the drive pinion or the input roller of the (roller) counter can be adjusted by means of a tool or by hand. Preferably, for this purpose, the housing can be partially removed or the chassis with the components of the pipette can be removed from the housing.

[0028] According to a further embodiment, the correction device is configured such that, when the coupling device is uncoupled, the setting of the display device can be changed from the outside of the housing by means of a correction tool. Thereby, the adjustment of the display device is simplified and an unintentional adjustment of the display device is prevented. In a further embodiment, the correction device is coupled with an adjustment roller or another adjustment mechanism which can be adjusted from the outside of the housing, so that the adjustment of the display device is carried out by adjusting this adjustment mechanism from the outside of the housing.

[0029] According to a further embodiment, the coupling device and the correction device are configured such that the coupling device can be uncoupled and coupled and the setting of the display device can be changed by means of the same correction tool. According to a further embodiment, for this purpose, the same correction tool can be introduced into the housing through the same housing opening of the housing from the outside of the housing.

[0030] According to a further embodiment, the coupling device and the correction device are configured such that, by introducing the correction tool into the housing, first the coupling device can be uncoupled and, by subsequently introducing the correction tool deeper into the housing and by subsequently turning the correction tool, the setting of the display device can be changed. Thereby, the calibration of the pipette is further simplified.

[0031] According to a further embodiment, the form-fitting coupling device is a toothed coupling or a claw coupling.

[0032] According to a further embodiment, the form-locking coupling device comprises a first gear wheel rotatably supported about a rotational axis and driven in coupling with the adjustment device, a shaft supported displaceably in the direction of the rotational axis in a first bearing in the housing and carrying the first gear wheel, a second gear wheel of the display device in engagement with the first gear wheel and driven, a cam drive with a first transmission element carried by the shaft and a second transmission element arranged fixedly in the housing, and a swivel lever connected rotationally with the first transmission element, wherein the first gear wheel is held on the shaft in such a way that it is prevented from moving upward on the shaft, and the first transmission element is held on the shaft in such a way that it is prevented from moving downward on the shaft, and the shaft is displaced translationally over the cam drive and the first gear wheel is disengaged from the second gear wheel by a swivel of the swivel lever, in order to decouple the adjustment device from the display device. This embodiment combines reliable functionality with simple operability.

[0033] According to a further embodiment, the shaft has a shoulder on the end and / or a groove with a retaining ring held releasably therein, and the first gear wheel is prevented from moving upward on the shaft by the shoulder or the groove with the retaining ring held therein, and the first transmission element is prevented from moving downward by a further shoulder or a further groove with a further retaining ring held therein. According to a further embodiment, the shaft is a rotatably supported shaft, and either the first gear wheel is connected rotationally (rotationally fixed) with the shaft and the first transmission element and the swivel lever connected rotationally with the first transmission element are rotatably supported on the shaft, or the first gear wheel is rotatably supported on the shaft and the first transmission element and the swivel lever are connected rotationally with the shaft. According to a further embodiment, the swivel lever is accessible from the outside of the housing. In particular, the swivel lever can be swiveled by means of a correction tool or by hand. According to a further embodiment, the swivel lever can be swiveled by introducing a correction tool into an opening of the housing.

[0034] According to a further embodiment, the first transmission element is a first cam (Kurve) and / or the second transmission element is a second cam. In an alternative embodiment, only one of the two transmission elements is a cam and the other transmission element is a detection element which detects the cam.

[0035] According to a further embodiment, a first spring device is arranged between the shaft and a bearing fixedly arranged in the housing, the first spring device pressing the shaft with the first gear into a position in which the second gear is engaged, and the first gear can be disengaged from the second gear against the action of the first spring device. Preferably, the first spring device is pre-tensioned when the first gear is engaged with the second gear. In this embodiment, upon disengagement of the coupling device, the first spring device is (further) pre-tensioned, so that upon release of the turning lever, the first spring device presses the shaft into a position in which the first gear is engaged with the second gear. Thereby, the coupling device is automatically re-engaged after release of the turning lever, thereby further simplifying the operation.

[0036] According to a further embodiment, the correction device comprises a driven first wheel rotatably and displaceably in translation in a second bearing in the housing, the first wheel being displaceable in translation until it abuts against a second wheel which is driven and coupled to the display device, in order to rotate the second wheel by rotation of the first wheel and to change the setting of the display device. Thereby, the adjustment of the display device is simplified. According to a further embodiment, the rotation axis of the first wheel is oriented perpendicularly to the rotation axis of the second wheel. According to a further embodiment, the first wheel is displaceable in translation and rotatable from the outside of the housing. This embodiment is particularly suitable for use in combination with the above-mentioned form-locking coupling device, which comprises a turning lever which is accessible from the outside of the housing.

[0037] According to a further embodiment, the first wheel can be displaced by means of a correction tool attached to the first wheel until the second wheel, and the first wheel is rotated by rotation of the correction tool inserted into a tool action portion of the first wheel, and the second wheel is rotated by the first wheel.

[0038] According to a further embodiment, the first wheel and the second wheel are friction wheels of a friction wheel transmission. According to a further embodiment, the first wheel and the second wheel are toothed wheels, for example bevel gears having rotation axes oriented perpendicularly to each other.

[0039] According to a further embodiment, the first spring device presses the first wheel away from the second wheel by means of the shaft and the released turning lever until it abuts against the second bearing. Thereby, upon release of the turning lever, the first wheel is automatically introduced into a position in which it is not in contact with the second wheel.

[0040] According to a further embodiment, a second spring device is arranged between the first wheel and a second bearing fixedly arranged in the housing, which presses the first wheel away from the second wheel and moves the first wheel against the second wheel against the action of the second spring device. According to a further embodiment, the second spring device is pre-tensioned when the first wheel is pressed away from the second wheel until it rests against the stop element. By moving the first wheel against the second wheel, the second spring device is (further) pre-tensioned, so that the first wheel automatically returns into its initial position resting against the stop element after release. Thereby, the handling is further simplified.

[0041] According to a further embodiment, the coupling device and the correction device are configured for manipulation by means of a correction tool comprising a lever portion having a contour matching the tool action portion of the first wheel and a handle connected to the lever portion against rotation, in order to swing the rotating lever by introducing the lever portion into the opening of the housing into a connection against rotation with the first wheel, to frictionally lock the first wheel with the second wheel by continuing the introduction of the lever portion, and to rotate the second wheel by means of the first wheel by rotating the correction tool.

[0042] A further embodiment has an overtravel spring by means of which the lower stop is supported on an overtravel spring bearing fixedly arranged in the housing against downward movement by the stop element on the outer periphery of the stroke lever. Thereby, an overtravel is achieved by means of the expelling device for blowing out the remaining sample liquid from the pipette tip.

[0043] According to a further embodiment, the pipette has a lead screw, on the lower end portion of which the upper stop is configured and which has a through passage through which the stroke lever is guided. By the arrangement of the upper stop on the lower end portion of the lead screw in the lead screw nut, an adjustable upper stop is achieved.

[0044] According to a further embodiment, the adjustment device comprises an adjustment sleeve rotatably supported in the housing, which has an adjustment element accessible from the outside of the housing, which is coupled to the upper stop by a transmission mechanism. According to a further embodiment, the transmission mechanism comprises a groove extending axially on the inner periphery of the adjustment sleeve, into which a radial protrusion on the upper end portion of the lead screw engages. Thereby, the lead screw is simply actuated by rotating the end portion of the adjustment sleeve protruding from the housing in the upper portion.

[0045] According to a preferred embodiment, the display device is a (roller) counter.

[0046] Embodiments of such an overtravel device, a lead screw with a lead screw nut, an adjustment device and a display device are described in the patent documents EP 0 649 678 B1, EP 1 743 701 B1 and EP 2 633 915 B1. In this respect, reference is made to the patent documents EP 0 649 678 B1, EP 1 743 701 B1 and EP 2 633 915 B1, the contents of which are hereby incorporated into the present application.

[0047] Finally, the present application relates to an assembly comprising a pipette as described above and a correction tool, wherein the correction tool has a lever portion provided with a contour matching the tool-acting portion of the first wheel and a handle portion connected to the lever portion in a rotationally fixed manner, for swinging the rotation lever by introducing the lever portion into the opening of the housing, causing the rotationally fixed connection to the driven first wheel, for frictionally locking the first wheel to the second wheel by continuing the introduction of the lever portion, and for rotating the second wheel by means of the first wheel by rotating the correction tool. BRIEF DESCRIPTION OF DRAWINGS

[0048] The application is explained in detail according to the drawings of the embodiments. In the drawings:

[0049] Figure 1 A pipette according to the present application is shown in a longitudinal section from the left side;

[0050] Figure 2 The same pipette is shown in a longitudinal section from the right side;

[0051] Figures 3.1 to 3.4 The same adjustment mechanism is shown in an enlarged manner in a side view from the right side ( Figure 3.1 ), in a front view ( Figure 3.2 ), in a side view from the left side ( Figure 3.3 ) and in a rear view ( Figure 3.4 );

[0052] Figures 4.1 to 4.4 The same adjustment mechanism is shown in an enlarged manner in a side view from the right side ( Figure 4.1 ), in a front view ( Figure 4.2 ), in a side view from the left side ( Figure 4.3 ) and in a rear view ( Figure 4.4 );

[0053] Figures 5.1 to 5.4 The same adjustment mechanism is shown in an exploded manner in a side view from the right side ( Figure 5.1 ), in a front view ( Figure 5.2 ), in a side view from the left side ( Figure 5.3 ) and in a rear view ( Figure 5.4 );

[0054] Figure 6 In a side view the combined component with coupling device, correction device and counter is shown;

[0055] Figure 7 In a perspective view from below and from the side the cam drive of the same assembly is shown;

[0056] Figure 8 In a bottom view the same assembly with the correction tool arranged before is shown;

[0057] Figure 9 In a bottom view the same assembly with the correction tool partially used for uncoupling the coupling device is shown;

[0058] Figure 10 In a front view the same assembly in the same situation is shown;

[0059] Figure 11 In a bottom view the same assembly with the correction tool fully used for adjusting the counter is shown;

[0060] Figure 12 In a perspective view from above and from the side the same assembly in the same situation is shown.

[0061] Embodiment

[0062] In this application the terms "above" and "below", "over" and "under", "top view" and "bottom view", concepts derived therefrom, such as "underside" and "upper side" as well as "horizontal" and "vertical" relate to the orientation of the pipette, wherein the housing with the seat is oriented vertically downwards. In this orientation, for the intake or output of liquid, the pipette tip mounted on the seat points to a container located thereunder.

[0063] According to Figure 1 and 2 The pipette 1 according to the application 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 body 5 with a conical bottom, from which a slightly conical elongated tubular extension 6 extends downwards, which has a seat 7 for the insertion of a pipette tip 8 on the lower end. In the extension 6 a cylindrical shaped expelling chamber 9 is configured, which is connected by a connecting channel 10 with an opening 11 in the lower side of the seat 7.

[0064] Furthermore, the housing lower part 3 comprises an expelling element 12 in the form of a piston of the expelling device, which is guided into the cylinder 11 by means of a sealing system 13 on the underside of the base. The expelling element 12 has a disc 14 on the upper end, which has a semispherical recess in the centre on the upper side. Between the disc 14 and the upper side of the base, a first spring device 15 in the form of a helical spring is arranged. The first spring device 15 presses the disc 14 from below against a closure cap 16, which is connected with the base body 5 and has a passage in the centre, through which the disc 14 can be accessed from above.

[0065] The housing upper part 4 contains a stroke rod 17, which lies against the upper side of the disc 14. The lower end of the stroke rod 17 engages into the recess of the disc 14. On the stroke rod 17, an operating button 18 is fixed from above, which projects out of the upper end of the housing 2.

[0066] The stroke rod 17 is guided through a screw hole 19 of a screw spindle 20 arranged in the centre of the housing upper part 4. The screw spindle 20 has an outer thread 21 on the outside, which can be screwed into an inner thread 22 of a stroke body 23, which is held on a first carrier 24 in the lower part in the housing upper part 4. The stroke body 23 forms a screw nut.

[0067] The lower end side of the screw spindle 20 is an upper stop 25 for a stop element 26 in the form of an annular projection on the outer periphery of the stroke rod 17.

[0068] The screw spindle 20 is connected without rotation on the upper end with a drive element 27, which engages into an axial groove 29 of a drive sleeve 30 by means of radially outward projecting ribs 28 (see Fig. 5). The drive sleeve 30 is arranged concentrically with the screw spindle 20 and is rotatably supported on the outer periphery of the stroke body 23. The drive sleeve 30 has a circumferential first toothing 31 on the outer periphery on the lower edge. This is shown in particular in Figs. 3 to 5.

[0069] An adjustment sleeve 32 is pushed onto the drive sleeve 30. The adjustment sleeve 32 is rotatably supported on the outer periphery of the drive sleeve 30 and is guided on the drive sleeve 30 in such a way that it can be moved in the axial direction between two delimitations. The upper end of the adjustment sleeve 32 projects out of the upper end of the housing 2. Here, the adjustment sleeve 32 has an adjustment ring 33 on the outer periphery, which has grooves on the outer periphery.

[0070] The adjustment sleeve 32 has a circumferential second toothing 34 on the outer periphery on the lower edge and further up a circumferential third toothing 35 on the outer periphery. 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 greater diameter and a greater number of teeth than the second toothing 34.

[0071] The second toothing 34 is closed on the upper side and the third toothing 35 is closed on the lower side by a disc 36 located therebetween. The lower side of the disc 36 forms a lower limit 37 for the movement of the adjustment sleeve 32 and the upper side of the disc 36 forms an upper limit 38 for the movement of the adjustment sleeve 32.

[0072] In addition to the driver sleeve 30 and the adjustment sleeve 32, a transmission shaft 39 is rotatably supported on the first carrier 24. The transmission shaft 39 is provided with a fourth toothing 40 in the lower portion, a fifth toothing 41 above the fourth toothing and a sixth toothing 42 above the fifth toothing. The fourth toothing 40 and the fifth toothing 41 have the same diameter and the same number of teeth and are combined into one unique toothing 43. The sixth toothing 42 is arranged spaced apart from the fifth toothing 41. The sixth toothing has a smaller diameter and a smaller number of teeth than the fifth toothing 41.

[0073] The transmission shaft 39 is rotatably supported in a second carrier 44 in the upper portion, which is fixed in the housing upper part 4.

[0074] Furthermore, a counter 45 in the form of a roller counter is held between the first carrier 24 and the second carrier 44. The counting roller 46 of the roller counter is supported in the lower portion in the first carrier 24 and in the upper portion in the second carrier 44. The second carrier 44 is supported in the upper portion on a protrusion in the housing. Additionally, on the first carrier 24, a drive gear wheel 47 is rotatably supported on a shaft, which drive gear wheel comprises two spur gears 48, 49 of different diameter which are connected to each other in a rotationally fixed manner. The spur gear 48 with the smaller diameter is in engagement with the first toothing 31 of the driver sleeve 30 and the spur gear 49 with the larger diameter is in engagement with a drive pinion 50 on a starting roller of the roller counter.

[0075] The spur gear 49 and the shaft are components of a form-locking coupling which will be explained further below.

[0076] The number roller 51 of the counter 45 is visible from the outside of the housing 2 through a window 52 in the housing upper part 4, which window has a transparent cover 53 (see Fig. 5). Figure 2

[0077] In the housing upper part 4, a cup-shaped holder 54 is arranged below the travel body 23. The holder 54 has an outer thread 55 which is screwed into an inner thread 56 of a third carrier 57 which is fixed in the housing 2.

[0078] ​The holder 54 comprises a cap-shaped lower stop 58 which is held below a downwardly curved upper edge 59 of the holder 54. An overtravel spring 60 in the form of a coil spring which is supported on the bottom 61 of the holder 54 presses the lower stop 58 against the upper edge 59. The travel lever 17 is guided through a central passage of the lower stop 58, through the overtravel spring 60 and through a central passage in the bottom 61 of the holder 54.

[0079] The adjustment sleeve 32 is a drive shaft, the follower sleeve 30 is a driven shaft and the transmission shaft 39 is a secondary shaft of a shift transmission 63 which is configured as a spur gear transmission 62. By axially pushing the adjustment sleeve 32 into the lower shift position (fine adjustment position) shown in Fig. 3 and into the upper shift position (quick adjustment position) shown in Fig. 4, a shift between different shift stages is caused. In the fine adjustment position of Fig. 3, the adjustment sleeve 32 is pushed maximally downwards until the lower limit 37 abuts on the upper side of the fifth tooth portion 41 and in the quick adjustment position the adjustment sleeve 32 is pushed maximally upwards until the upper limit 38 abuts on the lower side of the sixth tooth portion 42. The adjustment sleeve 32 is thus at the same time a shift device 64 of the shift transmission, wherein the adjustment ring 33 is a shift element 65 of the shift device 64. Figures 3 and 4

[0080] In this embodiment, the shift transmission 63 has no priority position, so that the shift transmission accordingly maintains the last adjusted shift stage. The invention comprises other embodiments with a priority position of the shift transmission, for example realized by means of a second spring device.

[0081] Upon rotation of the adjustment sleeve 32, the follower sleeve 30 is rotated together in correspondence with the respective adjusted shift stage. By means of the follower sleeve 30, the lead screw 20 which is screwed in the internal thread 22 on the housing is rotated and the upper stop 25 is moved upwards or downwards depending on the direction of rotation. The distance between the upper stop 25 and the lower stop 58 is thus adjusted, which distance determines the dosing volume. The respective adjusted dosing volume can be read on the counter 45, which is driven by the follower sleeve 30 by means of the drive gear 47.

[0082] On the upper edge area of the housing upper part 4, in addition to the adjustment sleeve 32, a removal button 66 is fitted on a removal lever 67. The removal lever 67 extends parallel to the travel lever 17 through the housing upper part 4. The lower end of the removal lever is connected with a lateral fixed extension 68 of a removal sleeve 69 which is movably arranged on the extension 6.

[0083] ​In the housing upper part 4 a removal spring 70 is arranged which is configured as a helical spring, which at one end is supported in the housing 2 and at the other end acts on the removal rod 67. The removal spring 70 presses the removal rod 67 upwards so that the removal sleeve 67 rests against the extension 6.

[0084] The housing lower part 3 and the housing upper part 4 are connected to one another by a snap connection 71.

[0085] Before the pipetting, the user can adjust the desired dosing volume. For this purpose, the user turns the adjustment ring 33 until the desired dosing volume is displayed by the counter 45. For adjusting the dosing volume, the user can choose between two speed levels. In particular when the last adjusted dosing volume differs significantly from the dosing volume to be adjusted, the user can first choose the fast switching level. If the switching transmission is not already adjusted into the fast switching level, the user at this point holds the adjustment ring 33 and continues to pull the adjustment sleeve 32 slightly out of the housing 2 from the fine adjustment position in Fig. 3 into the fast adjustment position shown in Fig. 4.

[0086] In the fast adjustment position, the first toothing 31 of the driver sleeve 30 engages with the fourth toothing 40 of the transmission shaft 39 and the third toothing 35 of the adjustment sleeve 32 engages with the sixth toothing 42 of the transmission shaft 39. Thereby, the rotational speed of the adjustment sleeve 32 is converted into a higher rotational speed of the driver sleeve 30 so that the user can quickly adjust the dosing volume to the vicinity of the dosing volume to be adjusted.

[0087] For accurately adjusting the desired dosing volume, the user can choose the slow switching level. For this purpose, the user presses the adjustment sleeve 32 deeper into the housing 2 on the adjustment ring 33 until the fine adjustment position shown in Fig. 3 is entered. In this position, the first toothing 31 engages with the fourth toothing 40 and the second toothing 34 engages with the fifth toothing 41. As a result, the adjustment sleeve 32 is rotated with a defined rotational speed, which causes the driver sleeve 30 to rotate with a smaller speed than in the fast switching level. In the toothing of this embodiment, the rotational speed of the adjustment sleeve 32 is equal to the rotational speed of the driver sleeve 30, since the first toothing 31 and the second toothing 34 and the fourth toothing 40 and the fifth toothing 41 respectively have a uniform number of teeth and diameter.

[0088] Before or after the accurately adjusted dosing volume, the user can clamp the pipette tip 8 to the pipette 1 by pressing the seat 7 into the upper opening 72 of the pipette tip 8 with the pipette 1. For pipetting, the user first presses the operating button 18 downward, whereby the abutment element 26 is moved from the upper stop 25 to the lower stop 58. Here, the travel lever 17 presses the expelling element 12 downward and pre-tensions the first spring means 15. Subsequently, the user dips the pipette tip 8 with its lower opening 73 into the sample liquid and releases the operating button 18. The first spring means 15 thus presses the expelling element 12 and the travel lever 17 upward until the abutment element 26 rests on the upper stop 25. Here, the liquid quantity corresponding to the adjusted dosing volume is sucked into the pipette tip 8.

[0089] For the output of this liquid quantity, the user places the pipette tip 8 with the lower opening 73 over another container and presses the operating button 18 downward again. After reaching the lower stop 58, the user presses the operating button 18 deeper against the resistance of the overtravel spring 60 in order to push the remaining liquid quantity out of the pipette tip 8.

[0090] Subsequently, further liquid quantities can be pipetted in the same way or the pipette tip 8 is detached downward by pressing the release button 66 in order to exchange the sample liquid. Here, the release sleeve 69 detaches the pipette tip 8 from the seat 7. After releasing the release button 66, the release spring 70 moves the release lever 67 back into the initial position shown.

[0091] Subsequently, pipetting can be continued with the same adjusted dosing volume or with a re-adjusted dosing volume, wherein the adjustment can be carried out as described above.

[0092] Next, according to Figures 6 to 12 The coupling device 74 and the correction device 75, which are omitted in Figure 1 in Figures 1 to 5, are explained in detail.

[0093] The coupling device 74 comprises a shaft 76, on which the two spur gears 48, 49 are rotatably supported about a rotational axis 77. The shaft 76 is supported in a first bearing 78, which is configured in the first carrier 24 and the second carrier 44, in a directionally translatable manner along the rotational axis 77. The spur gear 49 with the larger diameter is prevented from rotatingly connecting with the spur gear 48 with the small diameter and forms a driving first gear wheel 79 of the coupling device 74. The drive pinion 50, which meshes with the spur gear 49, forms a driven second gear wheel 80 for driving the counter 45.

[0094] Furthermore, the coupling device 74 comprises a cam drive 81 having a first drive element 82 in the form of a first cam 83 rotatably supported on the shaft 76 and a second drive element 84 in the form of a second cam 85 fixed in position on the underside of the first carrier 24 in the housing 7.

[0095] The first drive element 82 is connected in a rotationally fixed manner in the lower region to a rotary lever 86 having a cam-shaped end 87. A first spring device 88 in the form of a helical spring 89 guided on the shaft 76 is supported in the lower region on the first carrier 24 and in the upper region on the underside of the spur gear 49. The first carrier 24 forms a seat 90 for the first spring device 88. The first spring device 88 presses the spur gear 49 into a position in which the spur gear meshes with the drive pinion 50 (see Figure 6 ).

[0096] The shaft 76 can be moved downwardly by overcoming the action of the first spring device 88, so that the spur gear 49 is disengaged from the drive pinion 50.

[0097] The correction device 75 comprises a second bearing 91 in the form of a bearing body 92 which has a U-shaped cross section in a horizontal sectional view and a circular first through-hole 93 in a base 94. The bearing body 92 is mounted on the side of the first carrier 24. A first wheel 95 of the correction device 75 is rotatably and axially movably supported in the bearing body 92. The first wheel 95 has a projecting hollow cylinder 96 on the outside, which is rotatably and translationally movably supported in the first through-hole 93 of the bearing body 92 and projects outwardly from the outside of the bearing body 92. A tool action portion 97 is configured in the hollow cylinder 96. The tool action portion 97 has the shape of a circular second through-hole 98 having a circular-segment-shaped peripheral section.

[0098] The first wheel 95 is a first friction wheel 99 of a friction wheel drive 100 and is made of metal or plastic, for example.

[0099] Furthermore, the correction device 75 has a second wheel 101 which is rotationally fixedly connected to the start roller of the counter 45 below the digital roller 51. The second wheel 101 is a second friction wheel 102 of the friction wheel drive 100. The second wheel is constituted, for example, by a ring made of rubber.

[0100] The housing 2 of the pipette 1 has a housing opening 103 which is oriented centrally towards the first and second through-holes 93, 98.

[0101] The correction tool 104 has a shaft 105 having a profile that matches the tool engagement portion 97 of the first wheel 95. To this end, the shaft 105 has a circular profile with a chord-shaped section in a cross section through the shaft 105. A handle 106 is connected to the outer end of the shaft 105.

[0102] exist Figure 8 shows the calibration tool before insertion into the pipette 1. The spur gear 49 meshes with the drive pinion 50, and the shaft 76 is pushed upwards to the maximum extent and held in this arrangement by the first spring device 88. The rotary lever 86 is rotated by the cam mechanism 81 into a position in which it presses against the inside of the first wheel 95 and, in turn, presses the first wheel against the inside of the base 94 of the bearing body 92.

[0103] according to Figure 6 and 9 , the correction tool 104 is introduced laterally into the housing opening 103 of the pipette 1, so that the rod 105 engages in the tool-acting part 97 of the first wheel 95. Due to the mutually matching contours of the rod 105 and the tool-acting part 97, the rod and the tool-acting part are connected to each other in a rotationally fixed manner (rotationally prevented). When the rod 105 is inserted, the rod 105 causes the rotating lever 86 to pivot. As a result, the first cam 83 of the cam transmission 81 is moved above the second cam 85 and the shaft 76 is moved downward in translation a certain distance (see Figure 7 ). As a result, the spur gear 49 is disengaged from the drive pinion 50 (see Figure 10 ).

[0104] Finally, by continuing to push the correction tool 104 into the pipette 1, the handle 106 hits the hollow cylinder 96 and the first wheel 95 is moved further inwardly into the bearing body 92. Here, the rotating lever 86 can also be further swung (see Figure 11 Here, the first wheel 95 is in contact with the second wheel 101, so that the setting of the counter 43 can be changed by rotating the correction tool 104 (see Figure 12 ).

[0105] Since the counter 45 is disconnected from the adjusting sleeve 32 and the upper stop 25, the stroke rod system of the pipette 1 is not adjusted. However, the disconnection of the counter 45 from the adjusting device can also be used to adjust the stroke rod system by adjusting the adjusting sleeve 32.

[0106] After the correction tool 104 is pulled out, the spur gear 49 is meshed with the drive pinion 50 again by the first spring device 88, and the rotating lever 86 and the first wheel 95 are moved to the position according to the cam transmission mechanism 81. Figure 8 The pipette 1 is then recalibrated and made available for pipetting.

[0107] List of reference signs

[0108] 1 pipette

[0109] 2 housing

[0110] 3 housing lower part

[0111] 4 housing upper part

[0112] 5 base body

[0113] 6 extension

[0114] 7 seat

[0115] 8 pipette tip

[0116] 9 displacement chamber

[0117] 10 connecting channel

[0118] 11 opening

[0119] 12 displacement element

[0120] 13 sealing system

[0121] 14 disc

[0122] 15 spring device

[0123] 16 closure cap

[0124] 17 travel lever

[0125] 18 operating button

[0126] 19 screw hole

[0127] 20 screw

[0128] 21 external thread

[0129] 22 internal thread

[0130] 23 travel body

[0131] 24 first carrier

[0132] 25 upper stop

[0133] 26 abutment element

[0134] 27 entraining element

[0135] 28 rib

[0136] 29 groove

[0137] 30 entraining element sleeve

[0138] 31 first toothing

[0139] 32 adjustment sleeve

[0140] 33 adjustment ring

[0141] 34 second toothing

[0142] 35 third toothing

[0143] 36 disc

[0144] 37 lower limit

[0145] 38 upper limit

[0146] 39 transmission shaft

[0147] 40 fourth toothing

[0148] 41 fifth toothing

[0149] 42 sixth toothing

[0150] 43 toothing

[0151] 44 second carrier

[0152] 45 counter

[0153] 46 counter roller

[0154] 47 drive gear

[0155] 48, 49 spur gear

[0156] 50 drive pinion

[0157] 51 digital wheel

[0158] 52 window

[0159] 53 cover

[0160] 54 holder

[0161] 55 external thread

[0162] 56 internal thread

[0163] 57 third carrier

[0164] 58 lower stop

[0165] 59 upper edge

[0166] 60 overtravel spring

[0167] 61 bottom

[0168] 62 spur gear mechanism

[0169] 63 switching mechanism

[0170] 64 switching device

[0171] 65 switching element

[0172] 66 removal button

[0173] 67 removal lever

[0174] 68 fixed extension

[0175] 69 removal sleeve

[0176] 70 removal spring

[0177] 71 snap connection

[0178] 72 upper opening

[0179] 73 lower opening

[0180] 74 coupling device

[0181] 75 correction device

[0182] 76 shaft

[0183] 77 rotational shaft

[0184] 78 first bearing

[0185] 79 first gear wheel

[0186] 80 second gear wheel

[0187] 81 cam drive

[0188] 82 first transmission element

[0189] 83 first cam

[0190] 84 second transmission element

[0191] 85 second cam

[0192] 86 rotational lever

[0193] 87 cam-shaped end

[0194] 88 first spring device

[0195] 89 helical spring

[0196] 90 abutment

[0197] 91 second bearing

[0198] 92 bearing body

[0199] 93 first through-hole

[0200] 94 base

[0201] 95 first wheel

[0202] 96 hollow cylinder

[0203] 97 tool action portion

[0204] 98 second through hole

[0205] 99 first friction wheel

[0206] 100 friction wheel transmission

[0207] 101 second wheel

[0208] 102 second friction wheel

[0209] 103 housing opening

[0210] 104 correction tool

[0211] 105 stem portion

[0212] 106 handle

Claims

1. A pipette with an adjustable dispensing volume, the pipette comprising: a rod-shaped housing (2), at least one seat (7) for releasably holding a pipette tip (8) on the lower end of the housing (2), A displacement device comprising a displacement chamber (9) having a displacement element (12) movable in the displacement chamber, a connecting channel (10) connecting the displacement chamber (9) with the opening (11) in the seat (7), A lever (17) coupled to the displacement element (12) at the lower end and movable in the longitudinal direction in the housing (2) for displacing the displacement element (12) in the displacement chamber (9), an operating button (18) connected to the upper end of the travel rod (17) and extending from the housing, The stop element (26) on the outer periphery of the travel rod (17) an upper stop (25) for the stop element (26) and a lower stop (58) for the stop element (26), the upper stop and the lower stop being used to limit the travel of the travel rod (17), an adjusting device (32) for adjusting the position of the upper stop (25) in the housing (2), a display device (45) for displaying the adjusted dispensing volume, The invention is characterized by a positive-locking coupling device (74) between the adjusting device (32) and the display device (45), which is designed to couple the adjusting device (32) to the display device (45) in an engaged state and to decouple the adjusting device (32) from the display device (45) in a disengaged state. The pipette comprises a correction device (75), wherein the coupling device (74) and the correction device (75) are designed so that the coupling device (74) can be firstly disconnected by inserting the same correction tool (104) into the housing (2) through the same housing opening (103) of the housing (2), and the setting of the display device (45) can be changed by introducing the correction tool (104) deeper and then rotating it.

2. The pipette of claim 1, wherein, The coupling device (74) is configured such that it can be disengaged and engaged from the outside of the housing (2).

3. The pipette of claim 1 or 2, wherein, The coupling device (74) is configured such that it can be disengaged and engaged by inserting a calibration tool (104) into the housing (2) from outside the housing (2).

4. The pipette of claim 1 or 2, wherein, The correction device (75) is designed so that, when the coupling device (74) is disconnected, the setting of the display device can be changed from the outside of the housing (2) by means of a correction tool (104).

5. The pipette of claim 1 or 2, wherein, The coupling device (74) comprises a driven first gear wheel (79) which is coupled to the adjustment device (32) and is rotatably mounted about a first axis of rotation, a shaft (76) which is displaceably mounted in a first bearing (78) in the housing (2) in the direction of the first axis of rotation and carries the first gear wheel, a second, driven gear wheel (80) of the display device (45) which meshes with the first gear wheel (79), a cam drive (81) having a first drive element (82) which is carried by the shaft (76) and a second drive element (84) which is arranged fixed in position in the housing (2), and a rotation lever (86) which is connected to the first drive element (82) in a rotationally fixed manner, wherein the first gear wheel (79) is held on the shaft (76) in such a way that it cannot be displaced upwards on the shaft (76) and the first drive element (82) is held on the shaft (76) in such a way that it cannot be displaced downwards on the shaft (76), and the shaft (76) can be displaced by the cam drive (81) and the first gear wheel (79) can be disengaged from the second gear wheel (80) by an oscillation of the rotation lever (86) in order to disengage the adjustment device (32) from the display device (45).

6. The pipette of claim 5, wherein, The first drive element (82) is a first cam (83) and / or the second drive element (84) is a second cam (85).

7. The pipette of claim 5, wherein, The rotation lever (86) can be oscillated by inserting a correction tool (104) through a housing opening (103) in the housing (2).

8. The pipette of claim 5, wherein, A first spring device (88) is arranged between the shaft (76) and a bearing (90) which is arranged fixed in position in the housing (2), the first spring device (88) pressing the shaft (76) with the first gear wheel (79) into a position in which it meshes with the second gear wheel (80), and the first gear wheel (79) can be disengaged from the second gear wheel (80) against the action of the first spring device (88).

9. The pipette of claim 3, wherein, The correction device (75) comprises a driven first wheel (95) which is rotatably and displaceably mounted in a second bearing (91) in the housing (2) about a second axis of rotation, the first wheel being accessible from the outside of the housing (2) in order to displace the first wheel (95) until it bears against a second wheel (101) which is driven and coupled to the display device (45), the second wheel (101) being rotatable and the setting of the display device (45) being changeable by rotating the first wheel (95).

10. The pipette of claim 9, wherein, The first wheel (95) can be displaced up to the second wheel (101) by inserting a correction tool (104) into the housing (2), and the first wheel (95) and the second wheel (101) which is driven by the first wheel can be rotated by rotating the correction tool (104).

11. The pipette of claim 9 or 10, wherein, The first wheel (95) and the second wheel (101) are a first friction wheel (99) and a second friction wheel (102) of a friction wheel drive (100).

12. The pipette of claim 8, wherein, The correction device (75) comprises a first wheel (95) which is driven, which is rotatably about a second axis of rotation and which is displaceably in the direction of the second axis of rotation supported in a second bearing (91) in the housing (2), which is accessible from the outside of the housing (2) in order to move the first wheel (95) until it rests on a second wheel (101) which is driven and which is coupled to the display device (45), by rotating the first wheel (95) the second wheel (101) can be rotated and the setting of the display device (45) can be changed.

13. The pipette of claim 12, wherein, The first wheel (95) can be moved up to the second wheel (101) by inserting the correction tool (104) into the housing (2) and the first wheel (95) and the second wheel (101) driven by the first wheel can be rotated by rotating the correction tool (104).

14. The pipette of claim 12 or 13, wherein, The first spring device (88) presses the first wheel (95) away from the second wheel (101) until it rests on the second bearing (91) by means of the shaft (76) and the released rotary lever (86).

15. The pipette of claim 12 or 13, wherein, The coupling device (74) and the correction device (75) are configured for manipulation by means of a correction tool (104) which comprises a lever portion (105) having a contour which matches the tool action portion (97) of the first wheel (95) and a handle (106) which is connected to the lever portion (105) in a rotationally fixed manner in order to swing the rotary lever (86) into a rotationally fixed connection with the driven first wheel (95) by introducing the lever portion (105) into the housing opening (103) of the housing (2), by continuing the introduction of the lever portion (105) the first wheel (95) is connected in a frictionally locking manner with the second wheel (101) and by rotating the correction tool (104) the second wheel (101) is rotated by means of the first wheel (95).

16. An assembly comprising a pipette according to one of claims 1 to 15 and a correction tool (104), wherein The coupling device (74) comprises a driven first gear wheel (79) coupled to the adjustment device (32) and rotatably mounted about a first axis of rotation, a shaft (76) which is displaceably mounted in a first bearing (78) in the housing (2) in the direction of the first axis of rotation and carries the first gear wheel, a second, driven gear wheel (80) of the display device (45) which meshes with the first gear wheel (79), a cam drive (81) having a first drive element (82) carried by the shaft (76) and a second drive element (84) which is fixedly arranged in the housing (2), and a rotation lever (86) which is rotationally connected to the first drive element (82), wherein the first gear wheel (79) is held on the shaft in such a way that it cannot be displaced upwards on the shaft (76), and the first drive element (82) is held on the shaft (76) in such a way that it cannot be displaced downwards on the shaft (76), and the shaft (76) can be displaced by the cam drive (81) and the first gear wheel (79) can be disengaged from the second gear wheel (80) by an oscillation of the rotation lever (86) in order to decouple the adjustment device (32) from the display device (45), the correction device (75) comprising a driven first wheel (95) which is rotatably and displaceably mounted in a second bearing (91) in the housing (2) about a second axis of rotation, which is accessible from the outside of the housing (2) in order to displace the first wheel (95) until it abuts against a second wheel (101) which is driven and coupled to the display device (45), and in order to rotate the second wheel (101) and to change the setting of the display device (45) by rotating the first wheel (95); The correction tool (104) comprises a lever portion (105) having a contour which matches the tool action portion (97) of the first wheel (95) and a handle (106) which is rotationally connected to the lever portion, in order to oscillate the rotation lever (86) by introducing the lever portion (105) into a housing opening (103) of the housing (2) into a rotationally fixed connection with the driven first wheel (95), to frictionally lock the first wheel (95) to the second wheel (101) by continuing the introduction of the lever portion (105), and to rotate the second wheel (101) by means of the first wheel (95) by rotating the correction tool (104).

Images