Single-channel lower part for pipette and pipette having upper part and single-channel lower part

Abstract

The invention relates to a single-channel lower part for a pipette, comprising: a hollow cylindrical housing lower part having an inner chamber, an opening at the upper end, a housing bottom at the lower end, a sleeve opening for sleeving a pipette tip, and a spring chamber; a rod-shaped piston actuator for displacing the piston in the cylinder; the contact surface is used for a lifting rod of the driving device; a spring support; a coil spring; and a first guide for guiding the piston actuator in the axial direction of the lower part of the hollow cylindrical housing, the first guide has at least one first guide surface on the inner circumference of the spring chamber and at least one second guide surface guided on the first guide surface on the outer circumference of a guide element which projects radially outward from the piston actuator and is connected to the piston actuator.

Description

Technical Field

[0001] The present invention relates to a single-channel lower portion for a pipette and a pipette having an upper portion and a single-channel lower portion. Background Technology

[0002] Pipettes are used, particularly in scientific and industrial laboratories for medical, molecular biological, and pharmaceutical applications, to measure selected volumes of liquid. The liquid can be a homogeneous (single-phase) liquid, especially composed of a single liquid component or a homogeneous mixture (solution) of multiple liquid components. Furthermore, the liquid can be a heterogeneous (multiphase) mixture of one liquid with another liquid (emulsion) or solid (suspension).

[0003] Known pipettes have a long, hollow pipette housing with a pin (sleeve) at the lower end for clamping the pipette tip. The pin is typically conical, cylindrical, or segmented conical and cylindrical protrusions and is also referred to as a "working cone." The pipette tip is a hollow tube with a tip opening at the lower end and a sleeve opening at the upper end, through which the tip can be clamped onto the pin. Liquid is collected into and expelled from the pipette tip. Liquid collection and expulsion are controlled using the pipette. Fixed-volume pipettes are used for pipetting at constant volumes. In variable-volume pipettes, the volume to be measured is adjustable. A mechanical counter is used to display the adjusted volume. To adjust the volume, the stroke of the drive mechanism can be adjusted by means of an adjustment device coupled to the counter. After use, the pipette tip is detached from the sleeve and can be replaced with a new tip. This avoids cross-contamination in subsequent pipetting.

[0004] Air cushion pipettes have a piston-cylinder assembly or other expulsion device within the pipette housing, which connects via a through-channel to a hole in the lower end of a pin. By displacing the piston within the cylinder using a drive mechanism, the air cushion is moved to draw liquid into and expel it from the pipette tip, which is clamped onto the pin. Disposable or reusable pipette tips are typically made of plastic.

[0005] In air cushion pipettes, contamination of the dispensing device can occur. This can be attributed to the seepage of liquid into the dispensing device due to improper handling, or the seepage of vapor or the finest droplets of the liquid to be pipet into the dispensing device.

[0006] Direct displacement pipettes are used with pipette tips that have an integrated piston. This type of pipette has a pin for securing the pipette tip and a drive mechanism that couples with the integrated piston (tip piston) for displacing the piston. The piston is in direct contact with the liquid, eliminating the adverse effects of air cushions. Direct displacement pipettes are particularly suitable for metering liquids with high vapor pressure, high viscosity, or high density, and are suitable for use in molecular biology where the absence of aerosols is crucial to avoid contamination.

[0007] Air cushion pipettes are known in which the lower portion, having a dispensing device and a sleeve for mounting the pipette tip, can be separated from the upper portion, having a drive mechanism for actuating the dispensing device. This facilitates the installation and removal of the dispensing device and the drive mechanism, as well as cleaning, maintenance, and repair, and allows the upper portion to be used for connection with different single-channel and / or multi-channel lower portions.

[0008] EP 1559480 B1 describes a pipette in which a dissipation device and a drive device can be more easily and quickly connected and disconnected from each other. The pipette has a dissipation device having a dissipation chamber with a displaceable boundary, the dissipation device being referred to hereinafter as a piston according to a preferred embodiment. Furthermore, the pipette has a sleeve for connection to a pipette tip and a connection channel between the free ends of the dissipation chamber and the sleeve. Additionally, the pipette has a drive device for driving the piston of the dissipation device, the drive device having a drive member having a releasable effective connection to the piston. Furthermore, the pipette has a bayonet connection between the drive device and the dissipation device, which can be established by establishing an effective connection between the drive member and the piston and can be released by disengaging the effective connection between the drive member and the piston.

[0009] The driving component is a movable lifting rod parallel to the longitudinal axis of the bayonet connection of the driving device, and the expulsion device has a contact surface oriented transversely to the lifting rod, connected to the piston via a piston rod. This contact surface is pressed against the lower end of the lifting rod by a lifting spring. The lifting spring is a helical spring surrounding the piston rod. The effective connection between the driving component and the piston is established by establishing the bayonet connection and released by disengaging the bayonet connection. Summary of the Invention

[0010] Therefore, the present invention is based on the objective of providing a single-channel lower portion for a pipette that enables more reliable and accurate pipetting.

[0011] This objective is achieved by a single-channel lower portion of a pipette according to claim 1. Advantageous embodiments of the invention are given in the dependent claims and in the following description.

[0012] The single-channel lower portion for a pipette according to the present invention includes:

[0013] • The lower part of the hollow cylindrical shell has:

[0014] οInner cavity;

[0015] ο The opening at the top;

[0016] ο At the bottom of the shell at the lower end;

[0017] ο A sleeve for attaching a pipette tip, the sleeve protruding downward from the bottom of the housing and having a through channel extending from the lower end of the sleeve into the inner cavity; and

[0018] ο A spring chamber, which forms an inner cavity or part of an inner cavity, has an opening at the top and at least one radially inwardly projecting boundary at the bottom, the boundary having a through opening;

[0019] • A rod-shaped piston actuator for displacing a piston in a cylinder, wherein the piston actuator is at least partially arranged in a spring chamber, extends axially along the lower part of a hollow cylindrical housing and is oriented toward a through opening.

[0020] • The contact surface for the lifting rod of the drive unit, which is arranged on the upper end of the piston actuator;

[0021] • A spring support member that connects to the piston actuator above the boundary and protrudes radially outward from the piston actuator;

[0022] • A helical spring, which is arranged in a spring chamber, is supported on the lower side of a spring support at the top and on a boundary at the bottom, and a piston actuator extends through the helical spring;

[0023] • A first guide for guiding a piston actuator along the axial direction of the lower part of a hollow cylindrical housing, the first guide having at least one first guide surface on the inner circumference of a spring chamber and at least one second guide surface on the outer circumference of a guide element that protrudes radially outward from and is connected to the piston actuator and is guided on the first guide surface.

[0024] The applicant has determined that, particularly in large-volume pipettes configured for use with pipette tips of nominal volumes of 2 ml, 5 ml, or 10 ml, the piston of the displacement device can tilt within the cylinder under adverse conditions. This can occur, for example, when the lower part and the displacement device disposed therein are coupled to the upper part and the drive mechanism disposed therein of an air-cushion pipette. To the applicant's knowledge, this piston tilt creates a gap between the seal and the cylinder wall, resulting in a slight to significant mis-sealing between the piston and the cylinder. Consequently, pipetting results may be erroneous, or pipetting may even become impossible. Furthermore, the tilting of the piston within the cylinder increases wear and repair costs.

[0025] According to the present invention, undesirable tilting of the piston in the cylinder is prevented by oriented the piston actuator for displacing the piston in the cylinder within the spring chamber of the lower housing. Therefore, the piston is not only guided within the cylinder but also oriented at a distance from the cylinder in the spring chamber by means of the piston actuator. Thus, tilting of the piston in the cylinder and its associated disadvantages are avoided. This improves pipetting accuracy, reduces pipette wear, and lowers the costs associated with calibration and repair. Expansion of the guide surface, friction occurring during piston displacement, and the cost of manufacturing the guide surface can be kept to a minimum.

[0026] The advantageous effects of this invention are particularly pronounced in large-volume pipettes with a nominal volume of at least 2 ml, because the piston of a large-volume pipette tends to tilt to a particularly strong degree due to its large cross-section. However, the advantageous effects of this invention can also be applied to pipettes with smaller nominal volumes. This invention can be used in both air-cushion pipettes and direct-displacement pipettes. This invention is suitable for use in both fixed-volume and variable-volume pipettes. This invention is particularly suitable for manually driven and electrically driven pipettes, and preferably for manual pipettes that can be held and operated with only one hand. This invention can also be advantageously used in laboratory automata and metering automata with a single-channel lower section as described in claim 1.

[0027] According to one embodiment of the invention, the contact surface is the upper side of the piston actuator and / or the upper side of the spring support. Thus, the contact surface is integrated into an existing component of the structure, saving on structural costs.

[0028] According to another embodiment, the contact surface is the upper side of the piston head, which is connected to the upper end of the piston actuator, and the piston head has a larger cross-section than the adjacent area of ​​the piston actuator. This provides a particularly large contact surface, which facilitates the connection between the lower and upper parts of the housing and the centering of the lower end of the lifting rod on the contact surface. According to another embodiment, the piston head can be releasably fastened to the upper end of the piston actuator or is a one-piece connection to the upper end of the piston actuator.

[0029] According to another embodiment, the contact surface is dome-shaped. The dome-shaped contact surface can center the lifting rod resting on it at its lower end, thereby avoiding lateral forces acting on the piston actuator that cause increased friction in the first guide.

[0030] According to another embodiment, the spring support includes a spring seat held on the piston actuator and a spring retainer that fastens the spring seat to the piston actuator. This facilitates the installation of the piston actuator, spring seat, and spring retainer. According to another embodiment, the spring retainer is releasably fastened to the piston actuator. This allows for disassembly, for example, for maintenance or repair. According to another embodiment, the spring seat and spring retainer are separate components. Alternatively, the spring seat and spring retainer are constructed as a single piece. Single-piece construction saves manufacturing and installation costs. According to another embodiment, the contact surface is formed on the upper side of the spring retainer. Therefore, a particularly large contact surface can be provided, which facilitates mounting the lower part on the upper part and facilitates centering of the lower end of the lifting rod.

[0031] According to another embodiment, the guiding element is a piston head and / or a spring support. This allows the first guide to be positioned at a particularly large distance from the cylinder body and enables particularly good piston orientation. Furthermore, structural costs can be reduced. According to another embodiment, the piston head and / or spring support has a second guiding surface on its outer circumference.

[0032] According to another embodiment, the first and second guide surfaces are cylindrical. This is particularly advantageous for the simple and precise manufacturing of the guide surfaces.

[0033] According to another embodiment, the spring chamber has two preferably two first guide surfaces, each partially rotating around the central axis and symmetrically distributed about it, with opposite diameters. The guide element abuts against the first guide surfaces with either a single fully rotating second guide surface or two correspondingly symmetrically distributed second guide surfaces, preferably two partially rotating with opposite diameters, about the piston actuator. This achieves particularly low-friction and uniform guidance of the piston actuator.

[0034] According to an alternative embodiment, the spring chamber has only a single fully rotating first guide surface, with the guiding element abutting against this first guide surface by two second guide surfaces, preferably two with opposite diameters, that are symmetrically distributed around the piston actuator and each only partially rotates. This achieves particularly low-friction and uniform guidance of the piston actuator.

[0035] According to another embodiment, the guide element has a hollow cylindrical section and at least one second guide surface on the outer circumference of the hollow cylindrical section, and the hollow cylindrical section houses the upper end of the piston rod. This allows for a structurally simple implementation of the guide element, which can be easily installed and disassembled when needed.

[0036] According to another embodiment, a second guiding surface exists on the outer side of the wing, which protrudes outward from the circumference of the hollow cylindrical section. This allows for a structurally simple and elastically deformable implementation of the guiding element, thereby reducing friction.

[0037] According to one embodiment, the wing has cavities parallel to the extension of the piston actuator, these cavities having an arcuate cross-section. This prevents material buildup, which is particularly advantageous for dimensionally stable injection molding of guide elements made of plastic. Furthermore, the arcuate hollow cross-section increases elasticity.

[0038] According to one embodiment, the guide element has at least one groove on its outer circumference, preferably two grooves with opposite diameters. The grooves facilitate the installation of the guide element and, if necessary, its removal.

[0039] According to another embodiment, the guide element has a snap-fit ​​connection and / or form-fit connection with the piston actuator. This facilitates the installation of the guide element and its removal when necessary. For removal, the snap-fit ​​connection and / or form-fit connection are configured to be releasable.

[0040] According to another embodiment, the hollow cylindrical segment has at least one connecting element on its inner circumference, which connects to the piston actuator. According to another embodiment, the hollow cylindrical segment and the piston actuator have mating connecting elements that connect to each other. According to another embodiment, the mating connecting elements are snap-fit ​​and / or form-fit connecting elements. According to another embodiment, the hollow cylindrical segment has four inwardly projecting, parallel legs on its inner circumference, which engage at their ends in grooves on the circumference of the piston actuator.

[0041] According to another embodiment, the boundary is a shoulder on the lower end of the spring chamber that completely or partially rotates around the inner circumference of the cavity.

[0042] According to another embodiment, the pipette is an air cushion pipette. According to another embodiment, the lower part of the housing has a hollow cylindrical upper housing section including a spring chamber forming part of the inner cavity, and the lower part of the housing has a hollow cylindrical lower housing section including a receiving chamber defined at the bottom of the housing and forming another part of the inner cavity. A cylinder is disposed in the receiving chamber and connected at the bottom to a through-channel of the sleeve. A piston is disposed in the cylinder, sealingly abutting the inner side of the cylinder circumferentially and movable in the axial direction of the cylinder. A piston actuator in the form of a piston rod is connected to the piston, extending upward from the piston through the through-opening into the upper housing section. In this air cushion pipette, the piston, guided in the cylinder located in the receiving chamber, is additionally oriented by a first guide of the piston actuator, and tilting of the piston is prevented.

[0043] According to another embodiment, the receiving chamber of the lower housing section has a larger diameter than the spring chamber of the upper housing section. This allows for the provision of a receiving chamber for a cylinder having a piston displaceable therein, with a specified stroke and volume, at a relatively low structural cost.

[0044] According to another embodiment, a connecting segment connects the lower edge of the upper housing segment to the upper edge of the lower housing segment. The connecting segment can bridge upper and lower housing segments of different diameters. By connecting upper and lower housing segments of different diameters to each other using the connecting segment, structural costs can be kept relatively low.

[0045] According to another embodiment, the connecting section includes an annular disc-shaped cover and a hollow cylindrical edging protruding downward from the outer edge of the cover. The upper housing section is connected to the upper side of the cover, the edging is connected to the upper edge of the lower housing section, and the cover covers the upper portion of the storage chamber. The connecting section simultaneously forms a cover for the storage chamber and the cylinder housed therein. The cover can be manufactured as a single piece with the upper housing section. This is advantageous for manufacturing the upper and lower housing sections by injection molding, as undercutting can be avoided. After injection molding, the upper housing section can be connected to each other at the edging of the cover and the upper edge of the lower housing section.

[0046] According to another embodiment, the edging is connected to the upper edge of the lower housing section via a screw connection, bayonet connection, releasable snap-fit ​​connection, or another releasable connection. This allows the lower housing to be opened non-destructively for cleaning, maintenance, or repair purposes and then closed again, for example, to replace the piston seal in the cylinder.

[0047] Alternatively, the trim is connected to the upper edge of the lower housing section by a non-releasable connection, such as by a snap-fit ​​connection that cannot be released in a non-destructive manner, by heat fusion, or by gluing.

[0048] According to another embodiment, the pipette is a direct displacement pipette. Even in a direct displacement pipette, it may be meaningful to assemble it into a lower and upper part to facilitate installation, disassembly, cleaning, maintenance and repair, and to enable the upper part to be used for connection with different single-channel and / or multi-channel lower parts.

[0049] According to another embodiment, the piston actuator has a means at its lower end for connection to the upper end of a pipette tip piston, which is inserted into a pipette tip that can be clamped onto a sleeve. In this embodiment, the piston actuator is configured such that it can be connected to a pipette tip piston of a pipette tip having an integrated pipette tip piston that can be clamped onto a sleeve. By oriented the piston actuator toward a first guide, tilting of the pipette tip piston in the pipette tip is avoided.

[0050] According to another embodiment, a second guide member of the piston actuator is present along the axial direction of the lower part of the hollow cylindrical housing. The second guide member has at least one third guide surface on the through opening and at least one fourth guide surface on the circumference of the piston actuator. The second guide member further improves the orientation of the piston in the cylinder and overcomes tilting.

[0051] According to one embodiment, the through opening has a circular cross-section in its boundary. According to another embodiment, the through opening has two guide grooves with opposing diameters, and the piston rod has at least two outwardly projecting guide ribs with opposing diameters on its outer circumference, these guide ribs engaging in the guide grooves. Anti-rotation is achieved by guiding the guide ribs within the guide grooves. This ensures that the first and second guide surfaces of the first guide are oriented toward each other and thus ensures the desired orientation of the piston.

[0052] According to another embodiment, the cylinder has a volume of at least 2 ml, preferably 2 ml, 5 ml, or 10 ml. This improved metering accuracy and prevention of damage is particularly effective in large-volume pipettes with nominal volumes within or exceeding the specified ranges.

[0053] The present invention also relates to a pipette comprising an upper portion and a single-channel lower portion according to any one of claims 1 to 24 or any one of the embodiments given in the specification, wherein the upper portion comprises a housing upper portion, an operating button on the outer side of the housing upper portion, a drive mechanism disposed in the housing upper portion and effectively connected to the operating button, and a displaceable lifting rod of the drive mechanism, the lower end of which can be accessed from the outside through another opening in the housing upper portion, wherein the upper portion and the single-channel lower portion are configured to be positioned in a connected position, wherein the lower end of the lifting rod contacts the contact surface of a piston actuator, and a connection means is provided to connect the upper portion and the lower portion to each other in the connected position. Attached Figure Description

[0054] The present invention will be described in more detail below with reference to the accompanying drawings of the embodiments. In the drawings:

[0055] Figure 1 A manually driven air cushion pipette with a single-channel lower section according to the invention is shown in vertical cross-section;

[0056] Figure 2 The lower part is shown in an enlarged vertical cross-section;

[0057] Figure 3 The lower part is shown in a top view;

[0058] Figure 4 The lower part is shown in a top view with a horizontal cross section;

[0059] Figures 5a to 5e A three-dimensional oblique top view ( Figure 5a ) and three-dimensional oblique elevation view ( Figure 5b The image shows a piston actuator with spring supports before installation, in a three-dimensional oblique top view. Figure 5c ) and top view ( Figure 5d The image shows a piston actuator with a spring support in its pre-installed state, and a top view (…). Figure 5e The image shows a piston actuator with a spring support in its installed state. Detailed Implementation

[0060] In this application, "upper" and "lower," "above" and "below," and their derivative terms such as "lower side" and "upper side," as well as "horizontal" and "vertical," refer to the orientation of a pipette, wherein the seat is arranged on the lower end of the pipette and oriented vertically downward. In this orientation, the pipette tip mounted on the seat can be oriented toward the container located below it, so as to draw liquid into the pipette tip and expel it from the pipette tip.

[0061] according to Figure 1The pipette 1 has a rod-shaped housing 2, which has a hollow cylindrical lower part 3 and an elongated hollow upper part 4.

[0062] according to Figure 2 As shown in Figure 5, the lower housing 3 has a hollow cylindrical upper housing section 5 and a hollow cylindrical lower housing section 7. The hollow cylindrical upper housing section 5 includes a spring chamber 6, and the hollow cylindrical lower housing section 7 includes a receiving chamber 8. The spring chamber 6 and the receiving chamber 8 together form the inner cavity 9 of the lower housing 3. The lower housing section 7 has a larger inner diameter than the upper housing section 5.

[0063] The upper housing section 5 has a cylindrical upper sidewall 10 that laterally defines the spring chamber 6. The upper housing section 5 has a circular opening 11 at its upper part, defined by the upper edge of the upper sidewall 10, leading to the spring chamber 6, and a radially inwardly projecting boundary 12 in the form of a shoulder 13 surrounding the inner circumference of the upper sidewall, the shoulder 13 defining the spring chamber 6 at its lower part. A circular through opening 14 is centrally located within the shoulder 13. The through opening 14 has two axially extending guide grooves 15 on its inner circumference that are diametrically opposed to each other.

[0064] The upper sidewall 10 has two inwardly projecting base-like regions 16 on its inner circumference. These two base-like regions 16 extend axially along the spring chamber 6 and circumferentially only on a portion of the inner circumference, and are diametrically opposed to each other. The base-like regions 16 are located at... Figure 1 and Figure 2 Before and after the drawing plane and in Figure 3 As shown in the figure, each of the base-shaped regions 16 forms a first cylindrical guide surface 17 with a radius of curvature around the central axis of the spring chamber 6 on its inner side.

[0065] The lower housing section 7 has a cylindrical lower sidewall 18 that laterally defines a receiving chamber 8. The lower housing section 7 has another opening 19 at its upper part. The lower housing section 7 has a conical housing bottom 20 at its lower part, which defines the receiving chamber 8 at its lower part. An elongated, tubular, slightly conical sleeve 21 protrudes downward from the housing bottom 20. The sleeve 21 has a seat 22 with a groove for the rotation of an O-ring for mounting a pipette tip 23. The sleeve 21 has a through channel 24 with a circular cross-section that extends from the lower end of the sleeve into the receiving chamber 8.

[0066] The upper housing section 5 is connected to the lower housing section 7 via a connecting section 25. The connecting section 25 has an annular disc-shaped cover 26, which is one-piece connected to the lower edge of the upper sidewall 10. A downwardly projecting cylindrical edging 27 of the connecting section 25 is one-piece connected to the outer edge of the cover 26. The edging 27 has an internal thread 28, and the lower sidewall 18 has an external thread 29 on its upper edge to mate with the internal thread 28. The internal thread 28 of the connecting section 25 is screwed into the external thread 29 of the lower sidewall 18, thereby connecting the upper housing section 5 and the lower housing section 7. The disc-shaped cover 26 covers another opening 19 of the lower housing section 7.

[0067] A discharge chamber 30 in the form of a cylinder 31 is arranged in the lower housing section 7. The cylinder 31 has a conical bottom 32 that defines the lower part of the cylinder 31. Another sleeve 33 protrudes downward from the conical bottom 32. Another through channel 34 extends from the lower end of the other sleeve 33 into the cylinder 31. The cylinder 31 is inserted into the lower housing section 7 in a precise fit. The outer contour of the cylinder 31 corresponds to the inner contour of the lower housing section 7. The other sleeve 33 is sealed on its outer circumference by an O-ring 35 on the inner circumference of the sleeve 21. The cylinder 31 is fixed in the lower housing section 7 at the upper part by a connecting section 25.

[0068] A generally disc-shaped piston 36 is arranged in the cylinder body 31, having a flat upper side and a flat conical lower side. A conical pin 37 protrudes downward from the center of the lower side and can be pushed into another sleeve 33 in a sealing manner. The piston 36 has a circumferential sealing lip 38. A rod-shaped piston actuator 39 protrudes vertically upward from the center of the upper side of the piston 36; this rod-shaped piston actuator 39 is also referred to as the piston rod 39. The piston actuator 39 is arranged on the central axis of the lower part 3 of the hollow cylindrical housing. The piston actuator 39 extends through the through opening 14 into the spring chamber 6 and protrudes from the opening 11 at the top.

[0069] The piston actuator 39 has four radially outwardly projecting, longitudinally extending guide ribs 41 on its outer circumference, two of which 41.1 project further outwardly and two of which project less outwardly. The two further outwardly projecting guide ribs 41.1 are guided in axially extending guide grooves 15 through the opening 14. The two less outwardly projecting guide ribs 41.2 are guided on the inner circumference of the opening 14 and each has a radially outwardly projecting step 41.3 at its foot (see...). Figure 5a , Figure 5c ).

[0070] Step 41.3 Figure 2 The uppermost position of the piston 36 shown abuts against the lower side of the cover 26.

[0071] The spring support 42 is fastened to the upper end of the piston actuator 39. The piston actuator 39 and the spring support 42 are in place before installation. Figure 5a and Figure 5b As shown in the diagram. A spring support 42 protrudes radially outward from the piston actuator 39. The spring support 42 has a hollow cylindrical section 43 and four parallel legs 44 extending inward from its inner circumference, which support the piston actuator 39. The piston actuator 39 has grooves 45 on its circumference, these grooves 45 having axial groove sections 45.1 extending axially downward from their upper ends and groove sections 45.2 each partially rotating from their lower ends. The legs 44 are pushed into the axial groove sections 45.1 with their inner ends (see diagram). Figure 5c and Figure 5d And the leg 44 is screwed into the partially rotating groove section 45.2 (see...) Figure 5e The slot 45 and the leg 44 form a bayonet connection 46, which holds the spring support 41 in a fixed position on the piston actuator 39.

[0072] The spring support 42 is also a guide element 47.

[0073] like Figure 3 As shown, two wings 48, formed by two arcuate regions 49, protrude outward from the outer circumference of the hollow cylindrical section 43. These two wings 48 are arranged on opposite diameter sides of the hollow cylindrical section 43 and extend over the entire height of the hollow cylindrical section 43. Each arcuate region 49 has a curved area 50 in cross-section and outwardly inclined side legs 51 starting from the end of this area, which connect to the hollow cylindrical section 43. The curved area 50 forms a cylindrical second guide surface 52. The second guide surface 52 has a radius of curvature on the outside corresponding to the radius of curvature of the first guide surface 17. The two curved areas 50 and the hollow cylindrical section 43 define two cavities 53 that extend along the axial direction of the lower portion 3 of the hollow cylindrical shell.

[0074] The first guide surface 17 and the second guide surface 52 together form the first guide element 54.

[0075] The guide groove 15 forms a third guide surface 55, and the guide rib 41 forms a fourth guide surface 56. The third guide surface 55 and the fourth guide surface 56 together form a second guide 57.

[0076] Between the two arc-shaped regions 49, the hollow cylindrical section 47 has two grooves 58 extending in the axial direction on its outer circumference, the two grooves 58 being opposite each other in diameter.

[0077] The spring support 42 is also the spring seat 59 and the spring retainer 60 that fixes the spring seat 59 to the piston actuator 39.

[0078] The upper end of the piston actuator 39 is dome-shaped and forms a contact surface 61 for the lower end of the lifting rod of the drive device.

[0079] A helical spring 62 is arranged in the spring chamber 6 and is supported at the lower part on the boundary 12 and at the upper part on the underside of the spring support 42. The helical spring 62 is installed under prestress such that it presses the piston actuator 39 upward until the piston 36 abuts against its upper piston side 63 on the lower side 64 of the cover 26 (see...). Figure 2 and Figure 5c ).

[0080] The lower housing 3 has an ejector sleeve 65 on its exterior, which is can-shaped. The upper housing section 5 and the lower housing section 7 are inserted into the ejector sleeve 65. The sleeve opening 21 protrudes downward from the conical bottom 67 of the ejector sleeve 65 through a circular lower hole 66. The ejector sleeve 65 is closed at the top by a cap-shaped ejector transmitter 68, which has a circular upper hole 69 through which the cylindrical upper sidewall 10 of the upper housing section 5 protrudes upward. On the upper side, the ejector transmitter 68 has an eyelet 70 for receiving the lower end of the ejector rod.

[0081] Upper part of the shell 4 according to Figure 1 The housing 2 includes a lifting rod 71 that abuts against the upper side of a contact surface 61. The lower end of the lifting rod 71 engages in a dome-shaped recess in the contact surface 61. An operation button 72 is fixed to the lifting rod 71 at the top, protruding outward from the upper end of the housing 2.

[0082] The lifting rod 71 is guided through the central spindle hole 73 of a threaded spindle 74, which is arranged in the upper part 4 of the housing. The threaded spindle 74 has an external thread 75 on the outside, which can be screwed into the internal thread 76 of a lifting body 77, which is held at the bottom on a carrier 78 in the upper part 4 of the housing. The lifting body 77 forms a spindle nut 79.

[0083] The lower end of the threaded mandrel 74 is a stop 80 for a stop element 81 in the form of an annular flange 82 on the outer circumference of the lifting rod 71.

[0084] The threaded mandrel 74 is anti-rotatably connected at its upper end to the drive member 83, which engages in the axial groove 85 of the drive member sleeve 86 by means of radially outwardly projecting ribs 84. The drive member sleeve 86 is arranged concentrically with the threaded mandrel 74 and rotatably supported on the outer circumference of the lifting body 77. The drive member sleeve 86 has rotating teeth 87 on its lower edge on the outer circumference.

[0085] The adjusting sleeve 88 is pushed onto the driving sleeve 86. The adjusting sleeve 88 and the driving sleeve 86 are connected in an anti-rotational manner. The upper end of the adjusting sleeve 88 protrudes outward from the upper end of the housing 2. Here, the adjusting sleeve 88 has an adjusting ring 89 on its outer circumference, which carries another groove 90 on its outer circumference.

[0086] A counter 91 in the form of a roller counter is held on the first carrier 78. The counter 91 has a drive gear 92. The counting roller of the counter 91 is visible from the outside of the housing 2 through a window in the upper part 4 of the housing.

[0087] In the upper part 4 of the housing, a can-shaped retainer 93 is arranged below the lifting body 77. The retainer 93 includes a lower stop 94, which is supported on an overtravel spring 95 in the form of a coil spring, which is supported on the bottom of the retainer 93. The lifting rod 71 is guided through a central channel in the lower stop 94, through a central channel in the bottom of the overtravel spring 95, and in the retainer 93.

[0088] When the adjusting sleeve 88 rotates, the driving sleeve 86 also rotates. Using the driving sleeve 86, the threaded mandrel 74 is tightened in the internal thread 76 fixed to the housing, and the upper stop 80 moves upward or downward depending on the direction of rotation. Thus, the distance between the upper stop 80 and the lower stop 94 is adjusted, and this distance determines the metering volume. The adjusted metering volume can be read on a counter 91, which is driven by the driving sleeve 86 via a drive gear 92.

[0089] On the upper edge of the upper part 4 of the housing, in addition to the adjusting sleeve 88, the ejector button 96 is also mounted on the ejector rod 97. The ejector rod 97 extends through the upper part 4 of the housing parallel to the lifting rod 71. Its lower end is fixedly pressed into the eyelet 70 of the ejector transmitter 68 of the ejector sleeve 65, which is displaceably arranged on the lower part 3 of the housing.

[0090] An ejector spring 98 configured as a helical spring is arranged in the upper part 4 of the housing. The ejector spring 98 is supported in the housing 2 on one hand and engaged with the ejector rod 97 on the other hand. The ejector spring 98 presses the ejector rod 87 upward, so that the bottom 67 of the ejector abuts against the bottom 20 of the housing.

[0091] The lower part 3 and the upper part 4 of the housing are connected to each other by a snap-fit ​​connection 99. This snap-fit ​​connection 99 is based on... Figure 1 Preferably, it includes two resilient hooks 100, which are defined by a slit in the cylindrical upper sidewall 10 of the upper housing section 5 of the lower housing portion 3. The hooks 100 in... Figure 2 Not shown in the image, because Figure 2 It shows relative to Figure 1A vertical section rotating 90 degrees around the central axis of the lower part of the housing. Furthermore, the snap-fit ​​connection 99 includes an inner step 101 on the inner circumference of the axially oriented receiving portion 102 at the lower end of the upper part of the housing 4, for inserting the upper housing section 5 of the lower part of the housing 3. The lower part of the housing 3 and the upper part of the housing 4 are connected to each other by snapping the elastic hook 100 onto the upper rear side of the inner step 101.

[0092] Before pipetting, the user can adjust the desired volume. To do this, the user rotates the adjustment ring 33 until the desired volume is displayed by the counter 91.

[0093] The user can clamp the pipette tip 23 onto the pipette 1 by pressing the pipette 1 and seat 7 into the upper opening of the pipette tip 23. To pipette, the user first presses down the operation button 72, causing the stop element 81 to move from the upper stop 80 against the lower stop 94. In this case, the lifting rod 67 presses down on the piston 36 and the coil spring 62 is biased. Then, the user immerses the pipette tip 23 with its lower opening into the sample liquid and releases the operation button 72. Therefore, the coil spring 62 presses up on the piston 31 and the lifting rod 71 until the stop element 81 abuts against the upper stop 80. Here, the volume of liquid corresponding to the adjusted volumetric volume is drawn into the pipette tip 23.

[0094] To expel the liquid, the user holds the lower opening of pipette tip 23 over another container and presses the operation button 72 down again. After reaching the lower stop 94, the user can press the operation button 72 deeper over the resistance of the overtravel spring 95 to expel residual liquid from pipette tip 23 via overtravel.

[0095] The piston actuator 38 is guided downward and upward via the first guide 54 and the second guide 57 as the lifting rod 71 is displaced, thereby preventing the piston 36 from tilting in the cylinder 31.

[0096] Explanation of reference numerals in the attached figures:

[0097] 1. Pipettes

[0098] 2. Shell

[0099] 3. Lower part of hollow cylindrical shell

[0100] 4. Upper part of the shell

[0101] 5. Upper shell section

[0102] 6. Spring chamber

[0103] 7. Lower shell section

[0104] 8 Storage Room

[0105] 9. Inner cavity

[0106] 10. Upper sidewall

[0107] 11. Circular opening

[0108] 12 Boundaries

[0109] 13 shoulder

[0110] 14 Through opening

[0111] 15 Guide slots

[0112] 16. Base-shaped area

[0113] 17. Guiding surface

[0114] 18. Lower sidewall

[0115] 19 Another opening

[0116] 20. Conical shell bottom

[0117] 21 Conical sleeve

[0118] 22 seats

[0119] 23 Pipette Tips

[0120] 24 Through Passage

[0121] 25 Connecting Section

[0122] 26 Circular disc-shaped cover

[0123] 27. Embroidery

[0124] 28 internal thread

[0125] 29 External thread

[0126] 30 Exclusion Room

[0127] 31 cylinder block

[0128] 32 Conical base

[0129] 33 Another set of mouths

[0130] 34 Another connecting passage

[0131] 35 O-ring

[0132] 36. Disc-shaped piston

[0133] 37 Conical pin

[0134] 38 Sealing Lip

[0135] 39 Piston Actuator

[0136] 40 Piston Rod

[0137] 41, 41.1, 41.2 Guide ribs

[0138] 41.3 Steps

[0139] 42 Spring support

[0140] 43 Hollow cylindrical section

[0141] 44 Legs

[0142] 45 slots

[0143] 45.1 Axial groove section

[0144] 45.2 Rotating groove section

[0145] 46. ​​Bayonet connection

[0146] 47. Guiding element

[0147] 48 wings

[0148] 49. Arc-shaped area

[0149] 50. Arc-shaped curved area

[0150] 51 Side Leg

[0151] 52 Second guiding surface

[0152] 53 Cavity

[0153] 54 First Guide

[0154] 55 Third guiding surface

[0155] 56 Fourth guiding surface

[0156] 57 Second Guide

[0157] 58. Grooves

[0158] 59 Spring seat

[0159] 60 Spring retainer

[0160] 61 Contact surface

[0161] 62 Coil Spring

[0162] 63 Piston upper side

[0163] 64. Underside of the cover

[0164] 65 Ejector sleeve

[0165] 66 lower hole

[0166] 67. Bottom of the conical ejector

[0167] 68 Ejector Transmitter

[0168] 69 Upper Hole

[0169] 70 eye holes

[0170] 71. Lifting mast

[0171] 72 Operation Buttons

[0172] 73 Mandrel Holes

[0173] 74 Threaded mandrel

[0174] 75 External Thread

[0175] 76 Internal Thread

[0176] 77 Lifting Body

[0177] 78 carriers

[0178] 79 Mandrel Nut

[0179] 80 Upper stop

[0180] 81 Stopping element

[0181] 82 Annular flange

[0182] 83 Drive components

[0183] 84. Prominent ribs

[0184] 85 Axial groove

[0185] 86 Drive component sleeve

[0186] 87. Teeth

[0187] 88 Adjusting Sleeve

[0188] 89 Adjusting ring

[0189] 90 Another grooved section

[0190] 91 counter

[0191] 92 Drive gear

[0192] 93. Can-shaped retainer

[0193] 94 Lower stop

[0194] 95 Overtravel Spring

[0195] 96. Push-out button

[0196] 97. Push-out lever

[0197] 98 ejection spring

[0198] 99 Clip-on connection

[0199] 100 hooks

[0200] 101 Inner Steps

[0201] 102 Storage Department

Claims

1. A single-channel lower portion for a pipette, comprising: • The lower part (3) of the hollow cylindrical shell has: οInner cavity (9); ο Opening at the top (11); ο At the bottom of the shell (20) at the lower end; ο A sleeve (21) for fitting a pipette tip (23), the sleeve (21) protruding downward from the bottom (20) of the housing and having a through channel (24) extending from the lower end of the sleeve (21) into the inner cavity (9); and ο Spring chamber (6), the spring chamber (6) forming the inner cavity (9) or a part of the inner cavity (9), having the opening (11) at the upper part and having at least one radially inwardly projecting boundary (12) at the lower part, the boundary (12) having a through opening (14); • A rod-shaped piston actuator (39) for displacing the piston (36) in the cylinder (31), wherein the piston actuator (39) is at least partially arranged in the spring chamber (6), extending along the axial direction of the lower part (3) of the hollow cylindrical housing and oriented toward the through opening (14). • The contact surface (61) of the lifting rod (71) for the drive device, which is arranged on the upper end of the piston actuator (39); • A spring support (41) is connected to the piston actuator (39) above the boundary (12) and protrudes radially outward from the piston actuator (39); • A helical spring (62) is arranged in the spring chamber (6), supported on the lower side of the spring support (42) at the top and on the boundary (12) at the bottom, and the piston actuator (39) extends through the helical spring (62); • A first guide (54) for guiding the piston actuator (39) along the axial direction of the lower part (3) of the hollow cylindrical housing, the first guide (54) having at least one first guide surface (17) on the inner circumference of the spring chamber (6) and at least one second guide surface (52) on the outer circumference of a guide element (47) that protrudes radially outward from the piston actuator (39) and is connected to the piston actuator (39) and is guided on the first guide surface (17).

2. The lower part according to claim 1, characterized in that, The contact surface (61) is the upper side of the piston actuator (39) and / or the upper side of the spring support (42).

3. The lower part according to claim 2, characterized in that, The contact surface (61) is the upper side of the piston head, which is connected to the upper end of the piston actuator (39), and the piston head has a larger cross-section than the adjacent area of ​​the piston actuator (39).

4. The lower part according to any one of claims 1 to 3, characterized in that, The contact surface (61) is dome-shaped.

5. The lower part according to any one of claims 1 to 4, characterized in that, The spring support (41) includes a spring seat (59) held on the piston actuator (39) and a spring retainer (60) that fastens the spring seat (59) to the piston actuator.

6. The lower part according to any one of claims 1 to 5, characterized in that, The piston head and / or the spring support (41) are the guide elements (47) and have the second guide surface (52) on the outer circumference.

7. The lower part according to any one of claims 1 to 6, characterized in that, The first guide surface (17) and the second guide surface (52) are cylindrical.

8. The lower part according to any one of claims 1 to 7, characterized in that, (i) The spring chamber (6) has two preferably two first guide surfaces (17) symmetrically distributed around its central axis, each with a diameter opposite to the first guide surface and each partially rotating around it, and the guide element abuts against the first guide surface (17) with a single fully rotating second guide surface (52) or with two preferably two partially rotating second guide surfaces (52) symmetrically distributed around the piston actuator (39), each with a diameter opposite to the first guide surface (17); or (ii) The spring chamber (6) has only a single fully rotating first guide surface (17), and the guide element (47) abuts against the first guide surface (17) with two preferably two partially rotating second guide surfaces (52) symmetrically distributed around the piston actuator (39), each with a diameter opposite to the first guide surface (17).

9. The lower part according to any one of claims 1 to 8, characterized in that, The guide element (47) has a hollow cylindrical section (42) and at least one second guide surface (52) on the outer circumference of the hollow cylindrical section (42), and the hollow cylindrical section houses the piston actuator (39).

10. The lower part according to claim 9, characterized in that, The second guide surface (52) is located on the outer side of the wing (48), which protrudes outward from the circumference of the hollow cylindrical section (43).

11. The lower part according to claim 10, characterized in that, The wing (48) has a cavity (53) extending parallel to the piston actuator (39), the cavity (53) having an arc-shaped cross-section.

12. The lower part according to any one of claims 1 to 11, characterized in that, The guide element (47) has at least one groove (58) on its outer circumference, preferably two grooves with opposite diameters.

13. The lower part according to any one of claims 1 to 12, characterized in that, The guide element (47) has a snap-fit ​​connection and / or form-fit connection with the piston actuator (39).

14. The lower part according to any one of claims 1 to 13, characterized in that, The boundary (12) is a shoulder (13) that completely or partially rotates around the inner circumference of the lower part (3) of the housing.

15. The lower part according to any one of claims 1 to 14, characterized in that, The lower part (3) of the housing has a hollow cylindrical upper housing section (5), which includes the spring chamber (6) and forms part of the inner cavity (9). The lower part of the housing also has a hollow cylindrical lower housing section (7), which includes a receiving chamber (8) that is defined at the bottom (20) of the housing and forms another part of the inner cavity (9). The cylinder body (31) is arranged... The cylinder is placed in the storage chamber (8), and the cylinder body is connected at the bottom to the through channel (24) of the sleeve (21). The piston (36) is arranged in the cylinder body. The piston is sealed against the inner side of the cylinder body (31) on the circumference and can be displaced in the axial direction of the cylinder body. The piston actuator (39) in the form of a piston rod (40) is connected to the piston (36). The piston rod (40) extends upward from the piston through the through opening (14) into the upper housing section (5).

16. The lower part according to claim 15, characterized in that, The storage chamber (8) of the lower housing section (7) has a larger diameter than the spring chamber (6) of the upper housing section (5).

17. The lower part according to claim 15 or 16, characterized in that, The connecting section (25) connects the lower edge of the upper housing section (5) to the upper edge of the lower housing section (7).

18. The lower part according to claim 17, characterized in that, The connecting section (25) includes an annular disc-shaped cover (26) and a hollow cylindrical edging (27) protruding downward from the outer edge of the cover. The upper housing section (5) is connected to the upper side of the cover (26), the edging (27) is connected to the upper edge of the lower housing section (7), and the cover (26) covers the storage chamber (8) at the top.

19. The lower part according to claim 18, characterized in that, The edging (27) is connected to the upper edge of the lower housing section (8) by a spiral connection, a bayonet connection, a non-destructive releasable snap connection or another non-destructive releasable connection.

20. The lower part according to any one of claims 1 to 19, characterized in that, The piston actuator (39) has a device on its lower end for connecting to the upper end of the pipette tip piston, which is inserted into the pipette tip (23) and can be clamped onto the sleeve (21).

21. The lower part according to any one of claims 1 to 20, characterized in that, The second guide (57) of the piston actuator (39) is present along the axial direction of the lower part (3) of the hollow cylindrical housing. The second guide (57) has at least one third guide surface (55) on the through opening (14) and at least one fourth guide surface (56) on the circumference of the piston actuator (39).

22. The lower part according to any one of claims 1 to 21, characterized in that, The through opening (14) has a circular cross-section.

23. The lower part according to any one of claims 1 to 22, characterized in that, The through opening (14) has two guide grooves (15) with opposite diameters, and the piston actuator (39) has at least two outwardly projecting guide ribs (41) with opposite diameters on its outer circumference, the guide ribs (41) engaging in the guide grooves.

24. The lower part according to any one of claims 1 to 23, characterized in that, The cylinder (31) has a volume of at least 2 ml, preferably 2 ml, 5 ml or 10 ml.

25. A pipette comprising an upper portion and a single-channel lower portion according to any one of claims 1 to 24, wherein, The upper part includes an upper housing (4), an operation button (72) on the outside of the upper housing (4), a drive device arranged in the upper housing (4) and effectively connected to the operation button (82), and a displacement lifting rod (71) of the drive device, the lower end of which can be accessed from the outside through another opening (4) of the upper housing (4), wherein the upper part and the single-channel lower part are configured to be placed in a connected position, in which the lower end of the lifting rod (71) contacts the contact surface (61) of the piston actuator (39), and there is a connecting device that connects the upper part and the lower part to each other in the connected position.

Images