HAND-DOSING DEVICE

Description

[0001] The invention relates to a hand-held dosing device, in particular a pipette, with a dispensing mechanism for dispensing a defined fluid volume, hereinafter referred to as dispensing volume, in particular a liquid volume, with a volume adjustment mechanism for adjusting the dispensing volume, with a volume display for displaying a set dispensing volume and with an operating element for operating the volume adjustment mechanism.

[0002] Such hand-held dosing devices are known in various embodiments from the prior art, for example from the documents WO 2011 / 025399 A2, DE 203 21 525 U1, EP 1 743 701 A1, US 2008 / 223108 A1 and US 5 531 131 A.

[0003] Typically, hand-held dosing devices are calibrated and adjusted after production. For quality assurance reasons, hand-held dosing devices should be calibrated and adjusted several times a year, if necessary.

[0004] If the target values ​​determined during calibration do not match the actual values, the hand-held dosing devices must be adjusted. Some hand-held dosing devices are not designed for end-user adjustment. Other hand-held dosing devices can be adjusted using a special tool. Other hand-held dosing devices can also be adjusted without tools.

[0005] In principle, the manual dosing devices can be adjusted in two ways. Both involve establishing a match between the volume display of the manual dosing device and the actual fluid volume that can be dispensed or pipetted.

[0006] In a first variant for adjusting a handheld dispensing device, which is primarily used for pipettes with a fixed dispensing volume, the fluid volume to be dispensed is set to a defined target value. The handheld dispensing device is then subjected to gravimetric calibration. If the gravimetrically determined actual value deviates too greatly from the preset target value, the dispensing mechanism of the handheld dispensing device is adjusted accordingly to bring the actual value into line with the target value. This can be done, for example, by changing the piston stroke of a piston in the dispensing mechanism. Using calculation formulas, the piston stroke change required for the adjustment can be determined. This change is usually carried out by screwing or rotating elements of the dispensing mechanism or the volume adjustment mechanism. However, this involves a certain amount of effort.This adjustment procedure is used for many hand-held dosing devices with variable dispensing volume.

[0007] A second adjustment option, which is provided for other hand-held dosing devices, involves adjusting the volume indicator to match the actual fluid volume dispensed. The dispensed volume is first set to a defined target value. Calibration is then performed, and an actual value is determined. The value displayed on the volume indicator is then adjusted to the actual measured value. The volume adjustment mechanism does not adjust the dispensing mechanism in this case.

[0008] For example, the piston stroke of a dispensing mechanism's piston remains unchanged with this procedure. The adjustment is performed from "target value to actual value." After the adjustment is complete, the original target value is reset to perform the calibration again for verification purposes.

[0009] While the first described method for adjusting a hand-held dosing device requires calculations to make the necessary adjustments to the dispensing mechanism, the second method is characterized by its simplicity. Nevertheless, both approaches have their advantages.

[0010] The object of the invention is therefore to provide a hand-held dosing device of the type mentioned at the outset, which offers the user the option of carrying out both the one and the other type of adjustment.

[0011] To achieve this object, a hand-held dosing device of the type defined at the outset is proposed with the means and features of claim 1. In particular, to achieve this object, in a pipette of the type defined at the outset, it is proposed that the operating element comprises a display adjustment element connected to the volume display and a volume adjustment element connected to the volume adjustment mechanism, wherein the display adjustment element and the volume adjustment element are connected to one another via a releasable coupling in the normal position of use of the hand-held dosing device, so that a volume adjustment leads to a corresponding adjustment of the volume display and vice versa, and wherein the display adjustment element and the volume adjustment element are adjustable independently of one another when the coupling is released to adjust the hand-held dosing device.In this way, it is possible to adjust the display adjustment element, which remains connected to the volume display even when the coupling is released, independently of the volume adjustment element, which in turn remains connected to the volume adjustment mechanism when the coupling is released, and thus to operate the volume display and the volume adjustment mechanism independently of each other.

[0012] Thus, after calibrating the hand-held dosing device and determining an actual value of the dispensed fluid volume with the volume display unchanged, the fluid volume to be dispensed can be adjusted by changing the dispensing mechanism accordingly using the volume adjustment element.

[0013] If the previously described second variant for adjusting the hand-held dosing device is to be implemented, this is also possible with the hand-held dosing device according to the invention. In this case, the dispensed fluid volume can first be determined in a calibration step, and the actual value of the dispensed fluid volume can be determined. Subsequently, with the dispensing mechanism and volume adjustment mechanism unchanged, the value for the dispensed volume displayed on the volume indicator is adjusted using the display adjustment element, which can be adjusted independently of the volume adjustment element, thus bringing the displayed value into line with the determined actual value.

[0014] It may be advantageous if the hand-held dosing device has a housing in which at least the dispensing mechanism and the volume adjustment mechanism are arranged.

[0015] It can also be advantageous if the volume adjustment element is also configured to actuate the dispensing mechanism. This allows the volume adjustment element to serve a dual function. On the one hand, the volume adjustment mechanism can be actuated using the volume adjustment element. On the other hand, the volume adjustment element can also be used to actuate and trigger the dispensing mechanism of the manual dosing device.

[0016] In particular, it can be provided that the volume adjustment element is designed as a rotatable pushbutton. A rotary movement of the pushbutton can be transmitted to the volume adjustment mechanism to adjust the fluid volume to be dispensed. An axial movement, for example a pressing movement, of the volume adjustment element designed as a pushbutton can be transmitted to the dispensing mechanism to dispense a preset fluid volume. The volume adjustment element can be designed as a rotatable pipetting knob, which is connected on the one hand to the volume adjustment mechanism and on the other hand to the dispensing mechanism of the manual dosing device.

[0017] The display adjustment element can be designed as a display adjustment wheel. This allows for convenient and precise operation of the display adjustment element. If the display adjustment element or display adjustment wheel forms a passage for the volume adjustment element, preferably designed as a rotatable pushbutton, in which the volume adjustment element is guided and arranged in the operating position, a torque transmitted to the display adjustment element can also be reliably transmitted to the volume adjustment element when the coupling between the display adjustment element and the volume adjustment element is closed. Furthermore, this can result in a particularly compact design of the manual dosing device.

[0018] According to the invention, the coupling of the hand-held dosing device is designed as a form-fluid radial coupling. The radial coupling comprises at least one coupling element and at least one counter-coupling element, wherein the at least one coupling element is arranged on the volume adjustment element and the at least one counter-coupling element is arranged on the display adjustment element.

[0019] The at least one coupling element on the volume adjustment element is a toothed segment, and the counter-coupling element on the display adjustment element is a counter-toothing system that matches the toothed segment. The counter-toothing system can be designed as an internal toothing system. Preferably, the coupling element, in particular the toothed segment, can be moved radially outward against a restoring force of a restoring element, in particular an annular spring, into a coupling position in which it engages the counter-toothing system.

[0020] The volume adjustment element can comprise a sleeve having an insertion opening for a coupling pin of the coupling at one actuating end. The at least one coupling element of the coupling can be moved into its coupling position on the counter-coupling element and secured there by inserting the coupling pin into the insertion opening, counter to the restoring force of the restoring element.

[0021] It can be provided that the coupling element, at least preferably designed as a toothed segment, extends through an opening in the sleeve with an extension into the interior of the sleeve of the volume adjustment element. The sleeve and / or the at least one coupling element can have a guide groove for the reset element, in which the reset element, in particular the annular spring, is arranged in a guided manner. Thus, the reset element, preferably designed as an annular spring, can be arranged in this guide groove on the coupling element and the sleeve and can be wrapped around the sleeve of the volume adjustment element from the outside.

[0022] If the coupling pin is now inserted through the insertion opening into the interior of the sleeve of the volume adjustment element, the coupling pin displaces the end of the coupling element that extends into the interior of the sleeve radially outward. This occurs counter to the action of the return element, which is preferably designed as an annular spring. This allows the coupling element to be automatically returned to a decoupled position with the help of the return element as soon as the coupling pin is removed from the sleeve of the volume adjustment element.

[0023] The aforementioned coupling pin can have a pressure surface on its upper side facing away from the insertion opening for actuating the volume adjustment element. This makes it possible to conveniently exert pressure on the volume adjustment element, in particular for actuating and triggering the dispensing mechanism.

[0024] The volume adjustment mechanism of the hand-held dosing device can be a spindle with a thread, the dispensing mechanism of the hand-held dosing device can be a piston that is movable in a cylinder of the hand-held dosing device, and the volume adjustment element can have a mating thread that matches the thread. The spindle can be connected to the volume adjustment element via the thread and the mating thread, and the spindle in turn can be connected to the piston. In this way, by rotating the volume adjustment element, it is possible to change the screw connection depth between the volume adjustment element and the spindle, and thus the immersion depth of the piston in the cylinder, and thus the piston stroke. The spindle is preferably mounted in a rotationally fixed and axially displaceable manner in a housing of the hand-held dosing device, for example the one mentioned above.

[0025] The control element can be moved from a locked starting position, in which volume adjustment is prevented and the dispensing mechanism can be actuated with the volume adjustment element, to a volume adjustment position, in which the volume adjustment mechanism and / or the volume display can be actuated with the aid of the volume adjustment element and / or the display adjustment element. This prevents unintentional volume adjustment of the manual dosing device if the manual dosing device is only intended for regular use to dispense a defined, preset fluid volume.

[0026] If the counter-coupling element, in particular if it is designed as a counter-toothing, has a greater axial extent than the at least one coupling element, which is preferably designed as a toothed segment, it is possible to axially displace the volume adjustment element with the coupling element for actuating the dispensing mechanism relative to the display adjustment element without the coupling being released.

[0027] It can be advantageous if the volume adjustment element and the display adjustment element can be rotated relative to each other when the coupling is released.

[0028] In order to adjust the volume and volume display over a wide range as conveniently and quickly as possible, it can be advantageous to have a gear mechanism interposed between the display adjustment element and the volume display, in particular between the display adjustment element and a mechanical counter of the volume display. It can be advantageous if the gear mechanism has a gear ratio less than 1, i.e., for example, one revolution of the display adjustment element can be translated into ten revolutions of a counter wheel connected to an output of the gear mechanism. The gear mechanism can, for example, be a single-stage or, preferably, a multi-stage planetary gear mechanism.

[0029] The hand-held dosing device can also have an ejection mechanism for ejecting a pipette tip attached to a free, preferably conical, shaft end of the hand-held dosing device. This makes it possible to eject such pipette tips without having to touch them directly. The ejection mechanism can be operated particularly conveniently if it can be actuated with the display adjustment element. This can be done in particular by axially displacing or pressing the display adjustment element from an initial position into an ejection position. The display adjustment element can thus also perform a dual function, namely, on the one hand, adjusting the volume display and, when the coupling is closed, also adjusting the volume adjustment mechanism and, in addition, actuating and triggering the ejection mechanism.

[0030] An embodiment of the hand-held dosing device according to the invention is described in more detail below with reference to the figures.

[0031] They show, in a partly highly schematic representation: Figures 1 and 2 : each a side view of a hand-held dosing device according to the invention designed as a pipette, wherein in Figure 1 an operating element of the manual dosing device in its locked initial position and in Figure 2 a display adjustment element of this control element can be seen in the volume adjustment position, Figures 3 and 4 : a perspective view of the Figures 1 and 2 pipette shown, where Figure 4 a coupling pin that can be inserted through an insertion opening of a sleeve of a volume adjustment element of the control element can be seen above the insertion opening, Figures 5 and 6 : two sectional views of the pipette shown in the previous figures, rotated by 90 degrees to each other, Figure 7: a perspective bottom view of the display adjustment element, Figures 8 to 10 : different views of the volume adjustment element, showing the coupling pin and two of a total of three coupling elements arranged evenly around the circumference of a sleeve of the volume adjustment element and designed as toothed segments, Figures 11 to 13 : different views of the Figures 8 to 10 illustrated volume adjustment element with the coupling pin in its position of use inserted through the insertion opening into the sleeve of the volume adjustment element.

[0032] The Figures 1 to 6show a hand-held dosing device, designated overall by 1 and designed as a pipette. This hand-held dosing device 1 has a dispensing mechanism 2 for dispensing a defined fluid volume, in particular a liquid volume, a volume adjustment mechanism 3 for adjusting the dispensed volume, and a volume display 4 for displaying a set dispensed volume. To operate the volume adjustment mechanism 3 and also to change the volume display 4 accordingly, the hand-held dosing device 1 is provided with an operating element 5, which is arranged in a head region 6 of the hand-held dosing device within reach of a user.

[0033] The operating element 5 is constructed in two parts and comprises a display adjustment element 7 connected to the volume display 4 and a volume adjustment element 8 connected to the volume adjustment mechanism 3. Between the display adjustment element 7 and the volume adjustment element 8, a detachable coupling 9 is provided, which connects these two elements 7 and 8 to each other. This has the consequence that a volume adjustment leads to a corresponding adjustment of the volume display and vice versa - at least as long as the detachable coupling 9 is closed and the display adjustment element 7 is connected to the volume adjustment element 8. When the coupling 9 is released, the display adjustment element 7 and the volume adjustment element 8 can be adjusted or actuated independently of one another to adjust the manual dosing device 1. The individual components of the coupling 9 are described in the Figures 7 to 13 shown in more detail.

[0034] The hand-held dosing device 1 comprises a housing 10 in which at least the dispensing mechanism 2 and the volume adjustment mechanism 3 as well as further components of the hand-held dosing device 1 are arranged. In particular, based on the sectional views of the hand-held dosing device 1 according to the Figures 5 and 6 It becomes clear that the hand dosing device 1 is a mechanically manually operated pipette.

[0035] The volume adjustment element 8 is configured to actuate the dispensing mechanism 2 of the hand-held dosing device 1. For this purpose, the volume adjustment element 8 is designed as a rotatable pushbutton. A rotary movement of the pushbutton can be transmitted to the volume adjustment mechanism 3 to adjust the fluid volume to be dispensed. An axial movement, in particular a pressing movement, of the pushbutton can be transmitted to the dispensing mechanism 2 to dispense a preset fluid volume, which can also be referred to as the dispensing volume.

[0036] The display adjustment element 7 is designed as a display adjustment wheel. The display adjustment wheel 7 forms a passage 11 for the volume adjustment element 8, which is designed as a rotatable push button, in which the volume adjustment element 8 is arranged in a guided manner. The coupling 9 is a positive radial coupling which comprises at least one coupling element 12 and at least one counter-coupling element 13. The at least one coupling element 12 is arranged on the volume adjustment element 8 and the at least one counter-coupling element 13 is arranged on the display adjustment element 7. The at least one coupling element 12 on the volume adjustment element 8 is a toothed segment 14. The counter-coupling element 13 on the display adjustment element 7 is designed as a counter-toothing 15 matching the toothed segment 14. This counter-toothing 15 is according to Figure 7 an internal toothing.

[0037] The Figures 8 to 13illustrate that the three toothed segments 14, arranged evenly around the circumference of the volume adjustment element 8, can be moved radially outward into a coupling position against the restoring force of a restoring element 16, which in the present embodiment is designed as an annular spring. In this coupling position, the toothed segments 14 engage the counter-toothing 15, thereby closing the coupling 9.

[0038] The volume adjustment element 8 comprises a sleeve 17, which has an insertion opening 18 for a coupling pin 19 of the coupling 9 at one actuating end. This coupling pin 19 is particularly well integrated in the Figures 8 to 13By inserting the coupling pin 19 into the insertion opening 18, it reaches its use position and causes the coupling elements 12 to move into their coupling position on the counter-coupling element 13 against the restoring force of the restoring element 16 and to be held there.

[0039] In total, the coupling 9 has three coupling elements 12, each in the form of a toothed segment 14, arranged evenly around the circumference of the sleeve 17. Each of the toothed segments 14 extends with one end 20 through an opening 21 into the interior of the sleeve 17, so that an extension 22 at the end 20 of each toothed segment 14 projects into the interior of the sleeve 17. In this way, it is possible for the coupling pin 19, in its use position inserted through the insertion opening 18 into the interior of the sleeve 17, to displace the total of three toothed segments 14 radially outwards via their extensions 22.

[0040] This occurs counter to the restoring force of the return element 16, designed as an annular spring, which is placed on the outside of the sleeve 17 and guided within an external guide groove 23 of the sleeve 17, which continues into the toothed segments 14. The guide groove 23, the return element 16, and the coupling elements 12 are arranged in or on a retaining shoulder 17a of the sleeve 17.

[0041] The coupling pin 19 has a pressure surface 24 on its upper side facing away from the insertion opening 18. The pressure surface 24 serves to actuate the volume adjustment element 8, particularly when it is to be actuated to trigger the dispensing mechanism 2 of the manual dosing device 1.

[0042] The volume adjustment mechanism 3 comprises a spindle 25 with a thread 26, the dispensing mechanism 2 comprises a piston 27 that is movably guided in a cylinder 28 of the hand-held dosing device 1, and the volume adjustment element 8 comprises a counter-thread 29 that matches the thread 26. The counter-thread 29 is provided at an end of the sleeve 17 facing away from the actuating end. The spindle 25 is connected to the sleeve 17 of the volume adjustment element 8 via its thread 26 and the counter-thread 29. The spindle 25 is in turn connected to the piston 27, so that upon rotation of the volume adjustment element 8, a screw connection depth of the threads 26 and 29 between the volume adjustment element 8 and the spindle 25 and an immersion depth of the piston 27 or a piston stroke of the piston 27 within the cylinder 28 can be changed. The spindle 25 is mounted in the housing 10 of the hand-held dosing device 1 in a rotationally fixed but axially displaceable manner.

[0043] The display adjustment element 7 of the control element 5 can be made of a Figures 1 , 3, 4 and 5 and 6 shown starting position into a Figure 2 The mechanism for this is clearly shown in the sectional views of the manual dosing device 1 according to the Figures 5 and 6 can be seen. In the locked initial position, volume adjustment is prevented, while the dispensing mechanism 2 with the volume adjustment element 8 can still be actuated. In this way, unintentional volume adjustment when dispensing a defined fluid volume with the manual dosing device 1 is prevented.

[0044] In the Figure 2In the volume adjustment position shown, the volume adjustment mechanism 3 can be actuated using the operating element 5. This is done by turning the display adjustment element 7 or the volume adjustment element 8 connected to the display adjustment element 7 via the coupling 9. Since the display adjustment element 7 is interlocked or connected to the volume adjustment element 8 when the coupling 9 is closed, actuating the volume adjustment mechanism 3 by turning one of the two elements 7 or 8 also leads to a corresponding change in the volume display 4.

[0045] In particular Figure 7clarifies that the counter-coupling element 13, designed as counter-toothing 15, has a greater axial extent than the coupling elements 12. In this way, the volume adjustment element 8 with its coupling elements 12 can be axially displaced relative to the display adjustment element 7 for actuating the dispensing mechanism 2, without the coupling 9 being released in the process or thereby. The volume adjustment element 8 and the display adjustment element 7 are rotatable relative to each other when the coupling 9 is released. However, if the display adjustment element 7 is held in its locked initial position according to the Figures 1 , 3, 4 and 5 and 6, free rotation of the display adjustment element 7 is prevented. The locking of the display adjustment element 7 is achieved by means of a spur gear 40, which is produced by the engagement of teeth 41 formed on an underside of the display adjustment element 7 with a toothed ring 42 arranged within the housing 10.

[0046] If the coupling pin 9 is pulled upwards from its position of use within the sleeve 17 through the insertion opening 18, the coupling 9 is opened and the volume adjustment element 8 can be rotated independently of the position of the display adjustment element 7 to change the piston stroke of the piston 27.

[0047] A gear 30 is interposed between the display adjustment element 7 and the volume indicator 4. Specifically, the gear 30 is arranged between the display adjustment element 7 and a mechanical counter 31 of the volume indicator 4. A rotary movement of the display adjustment element 7 is transmitted to the gear 30 and the mechanical counter 31 of the volume indicator 4 by means of a transmission element 32. The gear 30 is a planetary gear that enables a sufficiently large transmission ratio of, for example, one to ten between the display adjustment element 7 and a first counter wheel of the counter 31 of the volume indicator 4 in a comparatively compact installation space.

[0048] The hand-held dosing device 1 also includes an ejection mechanism 33 for ejecting a pipette tip, not shown in the figures, that is attached to a free, tapered shaft end 34 of the hand-held dosing device 1. The ejection mechanism 33 can be actuated with the display adjustment element 7. This is done by axially displacing the display adjustment element 7 from an initial position into an ejection position. This axial displacement of the display adjustment element 7 from its initial position into its ejection position occurs counter to the restoring force of a return spring 35, by which the display adjustment element 7 can be automatically moved back from its ejection position to the initial position.

[0049] Part of the ejection mechanism 33 is an ejection sleeve 36. This is axially displaceable relative to a shaft 37 of the hand-held dosing device 1 and is connected to the display adjustment element 7 via a connecting element 38 in such a way that a return movement of the display adjustment element 7 from the ejection position to the starting position caused by the return spring 35 can also be transmitted to the ejection sleeve 36.

[0050] A removable, hook-shaped handle 39 is arranged on an outer side of the housing 10.

[0051] In order to provide the user with different options for adjusting a hand-held dosing device 1, in particular a pipette, the hand-held dosing device 1 according to the invention is proposed, in which the operating element 5 for operating the volume adjustment mechanism 3 of the hand-held dosing device 1 is constructed in two parts and comprises the display adjustment element 7, which is connected to the volume display 4 of the hand-held dosing device, and the volume adjustment element 8, which is connected to the volume adjustment mechanism 3 of the hand-held dosing device 1. The display adjustment element 7 and the volume adjustment element 8 are connected to one another via the releasable coupling 9, so that a volume adjustment leads to a corresponding adjustment of the volume display and vice versa, as long as the coupling 9 is closed.If the coupling 9 is released, the display adjustment element 7 and the volume adjustment element 8 can be operated independently of each other to adjust the manual dosing device 1. List of reference symbols

[0052] 1Hand dosing device 2Dispensing mechanism 3Volume adjustment mechanism 4Volume display 5Operating element 6Head area of ​​1 7Display adjustment element 8Volume adjustment element 9Coupling 10Housing 11Feedthrough 12Coupling element 13Counter-coupling element 14Tooth segment 15Counter-toothing 16Reset element / annular spring 17Sleeve 17aRetaining shoulder on 17 18Insertion opening 19Coupling pin 20End of 14 21Opening 22Extension on 14 23Guide groove 24Pressure surface 25Spindle 26Thread 27Piston 28Cylinder 29Counter-thread 30Gear 31Counter 32Transmission element between 7 and 30 33Ejection mechanism 34Shaft end 35Return spring 36Ejector sleeve 37Shaft 38Connecting element between 7 and 36 39Handle 40Serration 41Teeth on the underside of 7 42Tooth ring

Claims

1. Manual metering device (1), in particular a pipette, having a dispensing mechanism (2) for dispensing a defined volume of fluid, in particular a volume of liquid, having a volume adjustment mechanism (3) for adjusting a dispensing volume, having a volume indicator (4) for displaying a set dispensing volume and having an operating element (5) for operating the volume adjustment mechanism (3), wherein the operating element (5) comprises an indicator adjustment element (7) connected to the volume indicator (4) and a volume adjustment element (8) connected to the volume adjustment mechanism (3), wherein the indicator adjustment element (7) and the volume adjustment element (8) are connected via a releasable coupling (9), so that a volume adjustment results in a corresponding adjustment of the volume indicator and vice versa, and wherein the indicator adjustment element (7) and the volume adjustment element (8) can be adjusted independently of one another when the coupling (9) is released, so that the volume indicator (4) and the volume adjustment mechanism (3) can be actuated independently of one another, characterized in that the coupling (9) is a form-fitting radial coupling which comprises at least one coupling element (12) and at least one mating coupling element (13), wherein the at least one coupling element (12) ) is arranged on the volume adjustment element (8) and the at least one mating coupling element (13) is arranged on the indicator adjustment element (7), and wherein the at least one coupling element (12) is a toothed segment (14) and the mating coupling element (13) is a mating toothing (15) matching the toothed segment (14).

2. Manual metering device (1) according to claim 1, characterized in that the manual metering device (1) has a housing (10) in which at least the dispensing mechanism (2) and the volume adjustment mechanism (3) are arranged.

3. Manual metering device (1) according to claim 1 or 2, characterized in that the volume adjustment element (8) is designed to actuate the dispensing mechanism (2), in particular in that the volume adjustment element (8) is in the form of a rotatable pushbutton, wherein a rotational movement of the pushbutton for adjusting the volume of fluid to be dispensed can be transmitted to the volume adjustment mechanism (3) and an axial movement, in particular a pressing movement, of the pushbutton for dispensing a preset volume of fluid can be transmitted to the dispensing mechanism (2).

4. Manual metering device (1) according to one of the preceding claims, characterized in that the indicator adjustment element (7) is designed as an indicator-adjusting wheel, preferably wherein the indicator-adjusting wheel forms a passage (11) for the volume adjustment element (8), preferably designed as a rotatable pushbutton, in which passage the volume adjustment element (8) is guided and arranged.

5. Manual metering device (1) according to one of the preceding claims, characterized in that the mating toothing (15) is an internal toothing, and / or in that the coupling element (12), specifically the toothed segment (14), can be moved radially outwards against a restoring force of a restoring element (16), in particular a ring spring, into a coupling position in which it engages in the mating toothing (15).

6. Manual metering device (1) according to one of the preceding claims, characterized in that the volume adjustment element (8) comprises a sleeve (17) which, at an actuating end, has an insertion opening (18) for a coupling pin (19) of the coupling (9), wherein the at least one coupling element (12) is movable into its coupling position on the mating coupling element (13) by insertion of the coupling pin (19) into the insertion opening (18) against the restoring force of one or the restoring element (16) and can be fixed there, preferably wherein the at least one coupling element (12) has an extension (22) and the sleeve (17) has at least one opening (21) for the at least one coupling element (12), wherein the extension (22) extends through the opening (21) into the interior of the sleeve (17), and / or wherein the sleeve (17) and / or the at least one coupling element (12) has a guide groove (23) for accommodating the restoring element (16).

7. Manual metering device (1) according to claim 6, characterized in that the coupling pin (19) has, on its upper side facing away from the insertion opening (18), a pressure surface (24) for actuating the volume adjustment element (8), preferably for triggering the dispensing mechanism (2).

8. Manual metering device (1) according to one of the preceding claims, characterized in that the volume adjustment mechanism (3) has a spindle (25) with a thread (26), the dispensing mechanism (2) has a plunger (27) which is movable in a cylinder (28) of the manual metering device (1), and the volume adjustment element (8) has a mating thread (29) that matches the thread (26), wherein the spindle (25) is connected to the volume adjustment element (8) via the thread (26) and the mating thread (29) and the spindle (25) is connected to the plunger (27) so that when the volume adjustment element (8) is turned, a screw connection depth between the volume adjustment element (8) and spindle (25) and a plunging depth of the plunger (27) into the cylinder (28) can be varied, preferably wherein the spindle (25) is mounted in a rotationally fixed and axially displaceable manner in one or the housing (10) of the manual metering device (1).

9. Manual metering device (1) according to one of the preceding claims, characterized in that the operating element (5), in particular the indicator adjustment element (7), can be moved out of a locked initial position into a volume adjustment position, wherein, in the locked initial position, a volume adjustment is blocked and the dispensing mechanism (2) can be actuated by means of the volume adjustment element (8), and wherein the volume adjustment mechanism (3) and / or the volume indicator (4) can be actuated in the volume adjustment position.

10. Manual metering device (1) according to one of the preceding claims, characterized in that the mating coupling element (13), in particular the mating toothing (15), has a greater axial extension than the at least one coupling element (12) so that the volume adjustment element (8) can be displaced axially with the at least one coupling element (12) for the purpose of operating the dispensing mechanism (2) relative to the indicator adjustment element (7) without the coupling (9) being released.

11. Manual metering device (1) according to one of the preceding claims, characterized in that the volume adjustment element (8) and the indicator adjustment element (7) can be rotated relative to one another when the coupling (9) is released.

12. Manual metering device (1) according to one of the preceding claims, characterized in that a gear mechanism (30), in particular a single-stage or multistage planetary gear mechanism, is interposed between the indicator adjustment element (7) and the volume indicator (4), in particular between the indicator adjustment element (7) and a mechanical counter (31) of the volume indicator (4).

13. Manual metering device (1) according to one of the preceding claims, characterized in that the manual metering device (1) has an ejection mechanism (33) for ejecting a pipette tip which is pushed onto a free shaft end (34) of the manual metering device (1), preferably wherein the ejection mechanism (33) is actuatable by the indicator adjustment element (7), in particular by axially displacing the indicator adjustment element (7) from a starting position into an ejection position.