Multi-channel lower part for a fluid transfer device, and multi-channel fluid transfer device

Abstract

The invention relates to a multi-channel lower part (20) for a fluid transfer device (100), comprising: - a piston actuator (40) for simultaneously moving a plurality of pistons (75), - a plurality of receiving volumes (80, 81, 82, 83, 84, 85, 86, 87), arranged parallel to one another, for a fluid, the receiving volumes (80, 81, 82, 83, 84, 85, 86, 87) each being delimited by one of the pistons (75), - a housing (22) with a spring chamber (15) for receiving a spring (52) for the piston actuator (40) and with a receiving chamber (17) for receiving the plurality of receiving volumes (80, 81, 82, 83, 84, 85, 86, 87) for receiving a fluid, - a contacting region (60) in which the multi-channel lower part (20) can be connected at or in the spring chamber (15) to an upper part (12) of a liquid transfer device (100), wherein - a first guide (54) for the piston actuator (40) or a component (56, 58) connected to the piston actuator (40) is formed in the spring chamber (15), and wherein - a second guide (68) for the piston actuator (40) or a component (102, 104) connected to the piston actuator (40) is formed on an inner side of the housing (22) facing the receiving chamber (17). The invention also relates to a fluid transfer device (100) having such a multi-channel lower part (20).

Description

[0001] Description

[0002] Multi-channel lower part for a fluid transfer device and multi-channel fluid transfer device

[0003] The invention relates to a multi-channel lower part for a fluid transfer device, in particular a pipette or dispenser, as well as to a multi-channel fluid transfer device with such a multi-channel lower part. The invention particularly relates to a piston actuator guide for a multi-channel lower part of such a multi-channel fluid transfer device, which minimizes tilting play of a piston actuator and thus enables particularly uniform fluid intake in all channels of the multi-channel fluid transfer device.

[0004] Multi-channel fluid transfer devices are, in particular, multi-channel pipettes and multi-channel dispensers designed for the calibrated aspiration of liquids and / or the subsequent dispensing of the liquids into containers. The multi-channel fluid transfer device is held in the hand of an operator during the aspiration and dispensing of the liquid. A multi-channel fluid transfer device has an upper part, in which the operating elements and the mechanics or electronics required for aspiration of the liquid are located, as well as a multi-channel lower part with several parallel dispensing channels, which are configured for the intake and / or dispensing of a liquid.

[0005] The precision and accuracy of the aspirated volume depend on the ability to achieve and reproduce the same simultaneous travel for each displacement element for a given volume setting. However, it has been observed that when using a multi-channel pipette, the piston actuator tends to exhibit an angular difference between the top and bottom positions of the pipette stroke, without maintaining orthogonality to the sliding direction. This effect, known as backlash, occurs during the reciprocating movement of the piston actuator and the displacement elements and results in a difference in the travel distance of one displacement element relative to another, thereby reducing the precision and accuracy of the volume aspirated between the multiple displacement elements.In particular, tilting clearance in a gravimetric measurement results in a stepped increase in the volume taken in and / or discharged between the channels of the multi-channel fluid transfer device. This tilting clearance is primarily caused by excessive guide clearance between the piston actuator and the piston actuator guide. Secondarily, an unsuitable shape of the return spring used to lift the piston actuator, insufficient stiffness of the piston actuator guide, varying friction at the seals of the displacement elements, and other effects also lead to tilting clearance of the piston actuator.

[0006] DE 102006031 460 B4 discloses a multi-channel pipette for dispensing liquids, comprising a piston actuator rod and several receptacles arranged at one end of the piston actuator rod, each for a piston head. An elastic element is arranged between the pistons of the individual channels of the multi-channel pipette and the receptacle for the respective piston head, which supports the centering of the piston in the receptacle.

[0007] EP 2 190 582 B1 describes a multi-channel pipette with a piston holder and a guide for the piston holder. For this purpose, guide tracks are formed on the side of a housing of the multi-channel lower part. These guide tracks interrupt the housing and guide a guide element connected to the piston holder. The guide elements comprise a roller that rolls along the guide track, thus enabling the piston holder to be guided with as little friction as possible.

[0008] A multi-channel lower part for a pipette is known from WO 2010 / 080 082 A1. The multi-channel lower part comprises a guide assembly including a plunger holder, first and second rotating elements, a shaft, and first and second tracks. The plunger holder includes a plurality of aligned notches, a first slot extending above the plurality of aligned notches and generally parallel to the plurality of aligned notches, and second and third slots extending generally orthogonal to the first slot. The first rotating element is mounted in the second slot, and the second rotating element is mounted in the third slot. The shaft is mounted in the first slot and connects the first rotating element to the second rotating element.The first rotating element is mounted so that it rolls along the first track, and the second rotating element is mounted so that it rolls along the second track. However, the disadvantage of these known solutions is that dust and contaminants can penetrate the housing of the multi-channel lower section through the openings in the housing. Furthermore, the piston actuator can still tilt, thus leading to different volume absorption in the individual channels of the multi-channel lower section.

[0009] The object of the invention is to overcome the disadvantages known from the prior art and, particularly in the case of a multi-channel pipette or multi-channel dispenser, to ensure particularly uniform liquid aspiration and / or dispensing across the various channels of the multi-channel base. This can improve the accuracy of the multi-channel fluid transfer device. Furthermore, the invention aims to avoid an increase in operating forces.

[0010] This object is achieved by a multi-channel lower part for a fluid transmission device, which comprises the following components: a piston actuator for the simultaneous movement of several pistons, several receiving volumes for a fluid arranged parallel to one another, wherein the receiving volumes are each delimited by a piston, a housing with a spring chamber for receiving a spring for the piston actuator and a receiving chamber for receiving the several receiving volumes for receiving a fluid, a contact area in which the multi-channel lower part can be connected to an upper part of a fluid transmission device on or in the spring chamber, wherein a first guide for the piston actuator or a component connected to the piston actuator is formed in the spring chamber,and wherein a second guide for the piston actuator or a component connected to the piston actuator is formed on an inner side of the housing facing the receiving space.,

[0011] The additional guidance in the second guide section reduces the risk of the piston actuator tipping. In particular, it prevents transverse forces acting on the piston actuator through a transfer device from the upper section of the multi-channel fluid transfer device from leading to a misalignment or lateral deflection of the piston actuator. This prevents the piston actuator from being pushed off-center in the contact area and from being subjected to forces or moments that would cause the piston actuator to tip. It also prevents the piston actuator from contacting the housing of the multi-channel lower section on one side, which would lead to uneven friction conditions across the width of the piston actuator.This prevents the piston actuator from "getting stuck" on the housing and causing uneven absorption between the individual channels of the multi-channel lower part when a liquid is being taken up.

[0012] The features listed in the dependent claims enable advantageous improvements and further developments of the multi-channel fluid transmission device specified in the independent claim.

[0013] In an advantageous embodiment of the invention, the first guide and the second guide are aligned with each other. This enables particularly precise guidance of the piston actuator. In particular, with two aligned guide sections, offset of the piston actuator or angular misalignment of the piston actuator can be avoided, thereby further reducing the risk of the piston actuator tipping over.

[0014] In a preferred embodiment of the invention, the second guide is designed as a guide rail. A guide rail enables guidance of the piston actuator over a longer travel path, so that guidance is ensured essentially over the entire travel path of the piston actuator. This allows for a better guiding effect than, for example, with a guide bore, which is immobile relative to the movement of the piston and in which the guiding properties change depending on the position of the piston actuator due to a changing lever arm.

[0015] In an advantageous embodiment of the invention, a guide rail is formed on the housing in the receiving space, wherein the piston actuator is guided by the guide rail in the second guide at its end facing away from the contact area. This makes it possible to guide the piston actuator virtually over its entire length, so that the risk of the piston actuator tilting and the associated uneven fluid intake via the individual channels is further reduced. In addition, a guide rail can be easily and cost-effectively integrated into the housing of the multi-channel lower part by being molded into the housing, in particular into a housing shell of the housing, during the primary molding process, in particular during an injection molding process for producing the housing. Thus, no further machining of the housing is necessary after the primary molding process.

[0016] It is preferred if the housing has two housing shells, wherein a guide rail is formed on one of the housing shells on an inner wall of the housing shell that defines the receiving space. This guide rail guides the piston actuator at its end facing away from the contact area. Such a guide can be easily and cost-effectively integrated into a housing shell. Furthermore, such a guide rail enables the piston actuator to be guided over the entire actuation travel of the piston actuator, thus minimizing angular misalignment of the piston actuator.

[0017] Alternatively, the second guide section can also be formed in the side walls of the housing. By additionally guiding the piston actuator in the side walls of the housing, a very efficient guide can also be achieved, whereby the piston actuator is guided in one of the three guide sections over virtually its entire length. The side walls refer to the narrow walls of the housing, while the long sides are referred to as the front and rear of the housing in this patent application.

[0018] It is particularly preferred if a guide rail for the piston actuator is formed in each of the two side walls. This allows for particularly simple guidance of the piston actuator. In particular, improved guidance in both side walls of the housing can prevent the piston actuator from sticking to the housing, which could lead to uneven fluid absorption via the various channels of the multi-channel lower section.

[0019] In an advantageous embodiment of the multi-channel lower part, a guide body is molded or formed onto the piston actuator, which guide is guided in the guide rail of the second guide. A guide body molded onto or formed on the piston actuator enables particularly precise guidance of the piston actuator in the guide rail of the second guide. Furthermore, the shape of the guide body can minimize friction in the second guide, whereby the operating forces for the multi-channel lower part can be minimized and the improved guidance does not come at the expense of higher operating forces. It is particularly advantageous if the guide body is designed as a guide pin, which is guided in the guide rail of the second guide. A guide pin enables low friction forces on the one hand and precise guidance of the piston actuator on the other.Furthermore, a guide pin is suitable for compensating for angular misalignments of the piston actuator relative to the guide rail, so that such angular errors do not lead to a significant increase in the operating forces.

[0020] According to a preferred embodiment of the invention, a spring seat and a spring retainer are arranged in the contacting area, wherein the second guide section is / are formed on the spring seat and / or on the spring retainer. In solutions known from the prior art, the spring chamber has so far represented an area in which the piston actuator is designed to be essentially free of any guide. Since the force is introduced from the upper part of a fluid transfer device into the piston actuator in the contacting area from the upper part to the multi-channel lower part, it is particularly important to provide good guidance for the piston actuator in this area. Therefore, an additional guide in this contacting area is preferably formed on the spring seat and / or the spring retainer.The additional guide in the contact area with the upper part of the fluid transfer device prevents buckling at the coupling between the upper part and the piston actuator. This minimizes both transverse forces acting on the piston actuator and angular errors in the guide of the piston actuator.

[0021] In a preferred embodiment of the invention, the piston actuator has a recess in the contact area into which a collar of the spring retainer engages. This allows a mechanical, positive connection between the spring retainer and the piston actuator to be easily established. In particular, such a positive connection can ensure that the spring seat does not shift relative to the piston actuator. This enables particularly precise guidance, preferably play-free guidance, in this contact area.

[0022] Alternatively or additionally, it is advantageously provided that radially outwardly extending wings are formed on the spring retainer, which rest against the housing of the multi-channel lower part, the piston actuator being centered by the wings. In a preferred embodiment of the multi-channel lower part, the spring retainer is fixed to the piston actuator or a spring seat connected to the piston actuator in the manner of a bayonet lock. In this context, a bayonet lock is understood to mean a closure which is transferred into a fixing position by a pressing movement and subsequent rotation of the spring retainer. The spring retainer can be pushed onto the piston actuator through a corresponding recess and positively locked in the contact area.This not only improves guidance but also ensures that the spring is reliably fixed in place, so that the multi-channel lower part can be stored or cleaned as a finished assembly even without being connected to the upper part. Furthermore, the spring lock serves to preload the spring to ensure a reset function of the piston actuator after the fluid transfer device has been actuated. The spring is preferably preloaded with a force of 1.5 Newtons to 4 Newtons, particularly preferably with a force of 1.8 Newtons to 2.5 Newtons, in order to, on the one hand, ensure a reliable reset function of the piston actuator and the pistons connected to the piston actuator and, on the other hand, to keep the operating forces moderate, in order to enable the user to operate the fluid transfer device easily and, even with constant repetition, without fatigue.

[0023] In a preferred embodiment of the invention, the first guide in the spring chamber is designed as a guide rail, with a spring seat and / or a spring retainer guided in the guide rail. This enables particularly precise and essentially play-free first guidance of the piston actuator. Together with the second guide in the receiving chamber, the maximum angular misalignment is thus minimized, ensuring essentially equal absorption of volumes across the different channels of the multi-channel lower part.

[0024] In a particularly advantageous embodiment of the invention, the guide rail is designed as a cylindrical guide, and a corresponding curved geometry is accommodated on the spring seat and / or on the spring retainer in the cylindrical guide. The cylindrical guide preferably has opposing guide sections, preferably offset by 180°, with each guide section being formed over a circular section of 15° to 30°.

[0025] In an advantageous embodiment of the multi-channel lower part, the guide rail extends over at least half the length of the spring chamber, preferably over at least 70% of the length of the spring chamber, particularly preferably over at least 90% of the length of the spring chamber. This allows the piston actuator to be ideally guided in the first guide over the entire actuation travel, minimizing angular misalignments and offsets of the piston actuator. This minimizes the difference between the fluid volumes absorbed via the individual channels of the multi-channel lower part with low operating forces, thus improving the accuracy of the fluid transfer process.

[0026] A further aspect of the invention relates to a multi-channel fluid transfer device having an upper part and such a multi-channel lower part, wherein the upper part is designed to displace the piston actuator of the multi-channel lower part in the axial direction via a transfer element and a coupling element.

[0027] In a preferred embodiment of the invention, the multi-channel liquid transfer device is a multi-channel pipette or a multi-channel dispenser. For the simultaneous processing of multiple samples, laboratories use multi-channel pipettes or multi-channel dispensers that can be held and operated by an operator with one hand. Especially with such multi-channel pipettes or multi-channel dispensers, it is necessary that the aspiration and / or dispensing quantities across the individual channels of the multi-channel liquid transfer device are as uniform as possible.

[0028] Tests on test pieces have shown that the angular error of the piston actuator can be reduced by 40% compared to known solutions with a multi-channel lower part according to the invention. The absolute angular error is reduced to less than 0.2°, even in the worst case. This not only ensures very uniform liquid aspiration across all aspiration volumes of the multi-channel lower part, but also ensures that the operating forces, especially with a mechanical pipette, remain low and well-tolerated, and do not lead to premature fatigue of the operator's finger muscles.

[0029] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless otherwise stated in individual cases. The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Identical components or components with the same function are designated by the same reference numerals in the various figures. They show:

[0030] Figure 1 shows a multi-channel liquid transfer device according to the invention;

[0031] Figure 2 shows a first sectional view through a multi-channel

[0032] Lower part for a multi-channel fluid transfer device;

[0033] Figure 3 shows a further sectional view through a multi-channel

[0034] Lower part for a multi-channel fluid transfer device;

[0035] Figure 4 shows a housing of a multi-channel lower part according to the invention in a

[0036] sectional view;

[0037] Figure 5 shows a further sectional view through a multi-channel

[0038] Lower part for a multi-channel fluid transfer device;

[0039] Figure 6 shows a spring seat and a spring retainer, on which a guide for a

[0040] piston actuator;

[0041] Figure 7 shows a preferred embodiment of a guide for the piston actuator;

[0042] Figure 8 shows a further preferred embodiment for a guide of the

[0043] piston actuator;

[0044] Figure 9 shows another preferred embodiment for guiding the

[0045] piston actuator;

[0046] Figure 10 is a sectional view of a multi-channel lower part according to the invention for a liquid transfer device;

[0047] Figure 11 shows a top view of a contacting area of ​​a multi-channel lower part according to the invention for a liquid transfer device; Figure 12 shows a 3D representation of a section through a contacting area of ​​a multi-channel lower part according to the invention for a liquid transfer device;

[0048] Figure 13 shows a further sectional view of a multi-channel lower part according to the invention for a liquid transfer device;

[0049] Figure 14 shows a further 3D representation of a section through a contacting area of ​​a multi-channel lower part according to the invention for a liquid transfer device;

[0050] Figure 15 is a further plan view of a contacting area of ​​a multi-channel lower part according to the invention for a liquid transfer device; and

[0051] Figure 16 shows a detailed view of a spring retainer and a coupling element for connecting the multi-channel lower part to an upper part of a liquid transfer device.

[0052] Figure 1 shows a liquid transfer device 100 in the form of a multi-channel pipette 10 with an upper part 12 and a multi-channel lower part 20, which is reversibly and detachably connected to the upper part 12. An operating element 16 is provided on the upper part 12, with which a liquid can be taken up into the liquid transfer device 100 in a first process step and dispensed again by the same in a subsequent process step. Furthermore, the upper part 12 comprises a housing 14, in which a transfer rod (not shown) is arranged, with which a mechanical connection is established between the operating element 16 and the multi-channel lower part 20. A finger hook 18 is formed on the upper part, with which the liquid transfer device can rest on a finger of the operator in order to facilitate holding and operating the liquid transfer device 100.An ejector button 13 may also be formed on the upper part 12 to facilitate ejection of pipette tips after use of the liquid transfer device 100.

[0053] The upper part 12 has a preferably tubular housing 14, from which an operating element 16, in particular a control knob, protrudes at one end face. The operating element 16 serves to set a volume for the fluid transfer and / or to control the fluid intake and / or discharge through the multi-channel fluid transfer device 100. Furthermore, parts of the mechanics necessary for the fluid transfer as well as, if necessary, electronic components for controlling the multi-channel fluid transfer device 100 are arranged in the upper part 12.

[0054] The multi-channel lower part 20 comprises a housing 22 with a first housing shell 24 and a second housing shell 26, which are connected to one another and form the housing 22. The housing shells 24, 26 are separated at the side walls of the housing 22. The multi-channel lower part 20 comprises a plurality of parallel channels 30, 31, 32, 33, 34, 35, 36, 37, each with a receiving volume 80, 81, 82, 83, 84, 85, 86, 87 for a liquid. For this purpose, a pipette tip, into which the liquid is received, is attached to a cone 38 of the channels 30, 31, 32, 33, 34, 35, 36, 37. For ejecting the pipette tips, an ejection frame 28 is provided which is mechanically connected to the ejector button 13 and, when the ejector button 13 is pressed, causes the pipette tips to be ejected from the cones 38 of the channels 30, 31, 32, 33, 34, 35, 36, 37.

[0055] Figure 2 shows a section through a multi-channel lower part 20 according to the invention for a fluid transfer device 100. The multi-channel lower part 20 can have a support frame 50 to which a first housing shell 24 and a second housing shell 26 of the housing 22 can be fixed. Alternatively, the housing shells 24, 26 can also be connected to one another without a support frame 50. The multi-channel lower part 20 further comprises a piston actuator 40 with a first section 42, which extends substantially along a longitudinal axis of the fluid transfer device 100, and with a second section 46, which runs perpendicular to the first section 42 and preferably extends across the entire width of the housing 22. An opening 98 is formed on the housing 22, which separates a spring chamber 15 from a receiving chamber 17 of the multi-channel lower part 20.A spring 52 is arranged in the spring chamber 15, which is tensioned when the piston actuator 40 is moved and whose spring force returns the piston actuator 40 to its original position after the operating force is removed. The spring 52 is received in a spring seat 56 connected to the piston actuator 40 at an end of the spring chamber 15 facing away from the opening 98. The other end of the spring 56 is further received in a lower spring seat surrounding the opening 98. The spring seat 56 is fixed to the piston actuator 40 of the multi-channel lower part 20 by a spring retainer 58. For this purpose, a ring on the spring retainer 58 engages in a recess 44 in the first section of the piston actuator 40. In this case, a head 96 of the piston actuator 40 projects in the direction of an upper part 12 of a liquid transfer device 100, so that this head 96 can be mechanically contacted in a simple manner by a transfer element of the upper part 12.In this contact area 60, a first guide 54 for the piston actuator 40 is formed between the spring seat 56 and / or the spring retainer 58 and the housing 22. A plurality of piston receptacles 62 are formed on the second section 46 of the piston actuator 40, each of which accommodates a piston head 76 of a piston 75. Furthermore, a second guide section in the form of a recess 64 is formed on the second section 46 of the piston actuator 40. This second guide section is guided in a guide rail 66 in the housing 22 and thus forms the second guide 68.

[0056] Figure 3 shows a further section through a housing 22 of a multi-channel lower part 20 according to the invention for a fluid transfer device 100. While the structure is essentially the same as that shown in Figure 2, only the differences will be discussed below. In this exemplary embodiment, the first guide section 54 in the contact area 60 of the piston actuator 40 has a different design. The piston actuator 40 is guided directly in the spring lock 58. Furthermore, no recess 64 is provided in the central position on the piston actuator 40. In this exemplary embodiment, a guide body 102, in particular a guide pin 104, which is guided in the guide rail 66 as a second guide 68 of the piston actuator 40, is formed directly on the second section 46 of the piston actuator 40.

[0057] Figure 4 shows a further section through a housing 22 of a multi-channel lower part 20. The housing 22 has a support element 50 to which a first housing shell 24 is fixed. This housing shell 24 can, in particular, be positively connected to the support element 50 with a reversibly detachable connection. Furthermore, it can be seen that the housing 22 is cylindrical in the region of the spring chamber 15. A first guide for the piston actuator 40 is formed in the contact area 60 for the piston actuator 40. Furthermore, it can be seen that a guide rail 66 for a second guide 68 for the piston actuator 40 is formed on the housing shell 24 or on the support element 50. The multi-channel lower part 20 has a support frame 74 for receiving the volumes 80, 81, 82, 83, 84, 85, 86, 87 of the different channels 30, 31, 32, 33, 34, 35, 36, 37.Furthermore, a retaining clip 72 is provided to connect the support frame 74 to the housing 22 or the support frame 50. No guide is formed at the opening 98 in order to reduce the forces acting on the piston actuator 40 and to avoid the risk of jamming the piston actuator 40 due to an overly determined guide. Figure 5 shows a further section through a multi-channel lower part 20 according to the invention for a fluid transfer device 100. In this section, the volumes 80, 81, 82, 83, 84, 85, 86, 87 of the channels 30, 31, 32, 33, 34, 35, 36, 37 are inserted into the support frame 74. It can be seen that the volumes 80, 81, 82, 83, 84, 85, 86, 87 are each surrounded by a volume spring 88, so that the force absorption when attaching pipette tips to the cones 38 is reduced and enables the pipette tips to be attached to the cones 38 in a particularly simple and haptically pleasant manner for the user.Furthermore, Figure 5 shows how the pistons, with their piston heads 76, are each held in the piston receptacles 62 of the piston actuator 40 and are displaceable by the latter. For this purpose, the piston head 76 is connected via a piston rod 78 to a piston tip, which is arranged axially displaceably in one of the volumes 80, 81, 82, 83, 84, 85, 86, 87 and thus controls the fluid intake of the respective channel 30, 31, 32, 33, 34, 35, 36, 37.

[0058] Figure 6 shows a spring seat 56 and a spring retainer 58 in a three-dimensional representation. A recess 94 is formed on the spring retainer 58 for sliding the spring retainer 58 onto the spring seat 56 and the head 96 of the piston actuator 40. Furthermore, a guide surface 90 is formed on the spring retainer 58 for guiding the piston actuator 40 in the first guide 54. Furthermore, wings 92 are formed on the spring seat 56 for positionally fixing the spring seat in the housing 22 of the multi-channel lower part 20 and / or locking it in the housing 22.

[0059] Figure 7 shows a further preferred embodiment for improved guidance of a piston actuator 40 in the contacting area 60. Guide elements 99 are formed on the housing 22, which extend radially inward from a cylindrical section of the housing 22 in order to accommodate the spring seat 56 and / or the spring retainer 58 essentially without play. The head 96 of the piston actuator 40 is guided in the spring seat 56 and / or the spring retainer 58. The spring retainer 56 has a collar which engages in an undercut on the head 96 of the piston actuator 40 and thus forms a positive locking mechanism for the spring retainer 58 and / or the spring seat 56. Figure 7a shows the improved guide in a plan view of the contacting area 60 of the multi-channel lower part 20. Figure 7b shows the improved guide in a sectional view.In the sectional view shown in Figure 7b, the piston actuator 40 is completely relieved of load, so that the spring 52 is completely relaxed. By pressing the head 96 of the piston actuator 40, the piston actuator 40 moves downward in the drawing, with the piston actuator 40 being guided by the first guide 54 and the second guide 68 shown in Figures 2 and 3. The guide element 99 is to be designed to be sufficiently long in the axial direction that the piston actuator 40 is guided by this first guide 54 over its entire actuating travel. The spring 52 is compressed and returns the piston actuator 40 to its original position after the operating force is released.

[0060] Figures 8a and 8b show a further preferred embodiment for improved guidance of a piston actuator 40 in the contact area 60, i.e., in the area of ​​the second guide 54. In this embodiment, the spring retainer 56 has a gear-shaped base body from which two vanes 92 extend radially outward. The vanes 92 are designed to be positively received in a recess on the housing 22. The spring retainer 56 has a central opening in which the head 96 of the piston actuator 40 is guided.

[0061] Figure 8b shows an upper section of a multi-channel lower part 20 for a liquid transfer device 100, in particular for a multi-channel pipette 10. A first section 42 of the piston actuator 40 is guided along an opening 98 in the housing 22 as a first guide 22. Furthermore, a head 96 of the piston actuator 40 is guided along a contact area 60 by a first guide 54. The first guide 54 comprises a spring seat 56 and a spring retainer 58. The piston actuator 40 has a recess 44 in the region of its head 96, at which the spring retainer 56 engages in a form-fitting manner in the recess 44 and thus holds the spring seat 56 and the spring 52 received on the spring seat in a defined position.

[0062] Figures 9a and 9b show a further preferred embodiment for improved guidance of a piston actuator 40 in the contact area 60. In this embodiment, the housing 22 of the multi-channel lower part 20 is cylindrical in the contact area 60 with the upper part 12. In this embodiment, the improved piston actuator guide comprises a spring seat 56 and a spring retainer 58, which are combined in a single component 56, 58. On this component 56, 58, protruding vanes 92 are formed in the radial direction over a circular base area of ​​the component 56, 58, which are supported on the inner wall of the cylindrical portion of the housing 22 and thus guide the piston actuator 40.The piston actuator 40 has a recess 44 in the region of its head 96, in which the component 56, 58 engages in a form-fitting manner and thus holds the component 56, 58 and a spring 52 received on the component 56, 58 in a defined position. Figure 10 shows a further embodiment of a multi-channel lower part 20 according to the invention for a fluid transfer device 100 in a sectional view. The multi-channel lower part 20 comprises a housing 22 and a plurality of parallel channels 30, 31, 32, 33, 34, 35, 36, 37, each with a receiving volume 80, 81, 82, 83, 84, 85, 86, 87 for a fluid. To collect the liquid, a pipette tip (not shown) is placed on a cone 38 of the channels 30, 31, 32, 33, 34, 35, 36, 37, in which the liquid is collected.For ejecting the pipette tips, an ejection frame 28 is provided, which is mechanically connected to the ejector button 13 of the upper part 12 of the pipette 10. Pressing the ejector button 13 causes the pipette tips to be ejected from the cones 38 of the channels 30, 31, 32, 33, 34, 35, 36, 37. A piston 75, comprising a piston rod 78 and a piston head 76, is arranged in each of the receiving volumes 80, 81, 82, 83, 84, 85, 86, 87. The piston heads 76 of the pistons 75 are each received in piston receptacles 62 in the piston actuator 40. The piston actuator 40 has a first section 42 extending perpendicularly in the plane of the drawing and a second section 46 extending substantially perpendicularly to the first section 42 and extending substantially horizontally in the plane of the drawing. The piston receptacles 62 are formed on the second section 46 of the piston actuator 40.The housing 22 forms a spring chamber 15 and a receiving chamber 17. The spring chamber 15 and the receiving chamber 17 are connected by an opening 98. In an unloaded initial state, the first section 42 of the piston actuator 40 is located essentially in the spring chamber 15, and the second section 46 of the piston actuator is located in the receiving chamber 17. A spring 52 is arranged in the spring chamber 15. This spring is tensioned when the piston actuator 40 is moved, and its spring force returns the piston actuator 40 to its original position after the operating force is removed. The spring 52 is received in a spring seat 56 connected to the piston actuator 40 at an end of the spring chamber 15 facing away from the opening 98. The other end of the spring 52 is further received in a lower spring seat surrounding the opening 98. The spring seat 56 is fixed to the piston actuator 40 of the multi-channel lower part 20 by a spring lock 58.The piston actuator 40 is guided in the contact area 60 on a first guide 54, which is formed between the housing 22 or a guide rail 106 inserted into the housing 22 and the spring retainer 56 connected to the piston actuator 40. Alternatively or additionally, the first guide 54 can also be formed between the housing 22 or a guide rail 106 inserted into the housing 22 and the spring seat 56. The piston actuator 40 is further guided on a second guide 68, which is formed between a guide rail 66 formed on the housing 22 and the second section 46 of the piston actuator 40 or a guide body 102, in particular a guide pin 104, which is preferably integrally connected to the second section 46 of the piston actuator 40.

[0063] Figure 11 shows a plan view of the contacting area 60 of the multi-channel lower part 20. It can be seen that a cylindrical guide 48 is formed on the housing 22, which is operatively connected to a corresponding curved contour 108 on the spring retainer 58 and thus forms the first guide 54. Furthermore, it can be seen that the spring retainer 58 has a cylindrical section 112 and four legs 114, 116, 118, 120 extending inward from the cylindrical section 112, which legs are supported on the piston actuator 40. A cavity 110 is formed between the cylindrical section 112 and the curved contour 108 in order to give the curved contour the necessary elasticity to be rotated into the corresponding defined position by a profiled section 122 and aligned relative to the cylindrical guide 48.

[0064] Figure 12 shows a further preferred embodiment of the contacting area 60 and the first guide 54. The spring retainer 58 and the spring seat 56 are formed integrally in one component. Furthermore, an arcuate contour 108 is formed on the spring retainer 58, which is guided in a cylindrical guide 48 on the housing 22 and thus forms the first guide 54 for the piston actuator 40.

[0065] Figure 13 shows a further embodiment of a multi-channel lower part 20 according to the invention for a fluid transfer device 100 in a sectional view. The multi-channel lower part 20 has a housing 22 and a piston actuator 40 arranged in the housing 22. The multi-channel lower part 20 can have a support frame 50, to which a first housing shell 24 and a second housing shell 26 of the housing 22 can be fixed. Alternatively, the housing shells 24, 26 can also be connected to one another without a support frame 50. The piston actuator 40 has a first section 42 running perpendicularly in the plane of the drawing and a second section 46 running essentially perpendicular to the first section 42 and essentially horizontally in the plane of the drawing shown. The housing 22 forms a spring chamber 15 and a receiving chamber 17. The spring chamber 15 and the receiving chamber 17 are connected by an opening 98.In an unloaded initial state, the first section 42 of the piston actuator 40 is located essentially in the spring chamber 15, and the second section 46 of the piston actuator is located in the receiving chamber 17. A spring 52 is arranged in the spring chamber 15, which spring is tensioned when the piston actuator 40 is moved, and whose spring force returns the piston actuator 40 to its original position after the operating force is removed. The spring 52 is received in a spring seat 56 connected to the piston actuator 40 at an end of the spring chamber 15 facing away from the opening 98. The other end of the spring 52 is further received in a lower spring seat surrounding the opening 98. The spring seat 56 is fixed to the piston actuator 40 of the multi-channel lower part 20 by a spring retainer 58.The piston actuator 40 is guided in the contact area 60 on a first guide 54, which is formed between the housing 22 or a guide rail 106 inserted into the housing 22 and the spring lock 56 connected to the piston actuator 40. The piston actuator 40 is further guided on a second guide 68, which is formed between a guide rail 66 formed on the housing 22, in particular on one of the housing shells 24, 26, and the second section 46 of the piston actuator 40 or a guide body 102, in particular a guide pin 104, which is preferably integrally connected to the second section 46 of the piston actuator 40.This provides guidance of the piston actuator 40 over the entire length of the piston actuator 40, thereby minimizing angular misalignments of the piston actuator 40 and the associated uneven absorption of liquids in the different absorption volumes 80, 81, 82, 83, 84, 85, 86, 87 of the multi-channel lower part.

[0066] Figure 14 shows a further preferred embodiment of the contacting region 60 and the first guide 54 of the multi-channel lower part 20. The contacting region 60 is designed in particular for an electronic pipette 10 and, in addition to the spring retainer 58, has a coupling element 59 for coupling the multi-channel lower part 20 to an upper part 12 of a liquid transfer device 100. Guide rails 106 are formed or arranged in the housing 22, which guide the spring retainer 58 on the curved section 108 through a cylindrical guide 48.

[0067] Figure 15 shows a further top view of the contacting area 60 of the multi-channel lower part 20. It can be seen that a cylindrical guide 48 is formed on the housing 22, which is operatively connected to a corresponding curved contour 108 on the spring retainer 58 and thus forms the first guide 54. In contrast to the exemplary embodiment shown in Figure 11, the spring retainer 58 in this exemplary embodiment is designed as a solid body, with no hollow space being formed between the curved section 108 and the cylindrical section 112 of the spring retainer 58. The cylindrical guide contour 48 has two opposite guide sections offset by 180°, each of which extends over an angular range of 20-30°.

[0068] Figure 16 shows a spring retainer 58 with an arcuate guide section 108 and a recess between a cylindrical section 112 of the spring retainer 58 and the arcuate guide section 108. Furthermore, a profiled section 122 is formed on the spring retainer 58 to facilitate screwing the spring retainer 58 onto the piston actuator 40. Furthermore, Figure 16 shows a spring seat 56 and a coupling element 59 for coupling the multi-channel lower part 20 to an upper part 12 of a fluid transfer device 100.

[0069] List of reference symbols

[0070] 10 pipettes

[0071] 12 Top

[0072] 13 Ejector button

[0073] 14 housings

[0074] 15 spring chamber

[0075] 16 Control element

[0076] 17 Recording room

[0077] 18 finger hooks

[0078] 19 Transfer element

[0079] 20 multi-channel lower part

[0080] 22 housings

[0081] 24 first housing shell

[0082] 25 interior wall

[0083] 26 second housing shell

[0084] 28 drop frames

[0085] 30 first channel

[0086] 31 second channel

[0087] 32 third channel

[0088] 33 fourth channel

[0089] 34 fifth channel

[0090] 35 sixth channel

[0091] 36 seventh channel

[0092] 37 eighth channel

[0093] 38 cone

[0094] 40 piston actuators

[0095] 42 first section

[0096] 44 recess 46 second section

[0097] 48 cylindrical guide

[0098] 50 supporting frames

[0099] 52 spring

[0100] 54 first lead

[0101] 56 spring seat

[0102] 58 Spring lock

[0103] 59 Coupling element

[0104] 60 contact area

[0105] 62 piston holder

[0106] 64 recess

[0107] 66 guide rail

[0108] 68 second lead

[0109] 70 recordings

[0110] 72 retaining clip

[0111] 74 supporting frames

[0112] 75 pistons

[0113] 76 piston head

[0114] 78 Piston rod

[0115] 80 first volume

[0116] 81 second volume

[0117] 82 third volume

[0118] 83 fourth volume

[0119] 84 fifth volume

[0120] 85 sixth volume

[0121] 86 seventh volume

[0122] 87 eighth volume

[0123] 88 volume spring

[0124] 90 guide surface

[0125] 92 wings

[0126] 94 Recess 6 Head (of the piston actuator)

[0127] 98 Breakthrough

[0128] 99 Guide element 100 Fluid transfer device

[0129] 102 guide bodies

[0130] 104 Guide pin

[0131] 106 Guide rail

[0132] 108 Arch contour

[0133] 110 recess

[0134] 112 cylindrical section

[0135] 114 first leg

[0136] 116 second leg 118 third leg

[0137] 120 fourth leg

[0138] 122 profiled section

Claims

Patent claims 1. Multi-channel lower part (20) for a fluid transmission device (100) comprising: a piston actuator (40) for the simultaneous movement of several pistons (75), several receiving volumes (80, 81, 82, 83, 84, 85, 86, 87) arranged parallel to one another for a fluid, wherein the receiving volumes (80, 81, 82, 83, 84, 85, 86, 87) are each delimited by one of the pistons (75), a housing (22) with a spring chamber (15) for receiving a spring (52) for the piston actuator (40) and a receiving chamber (17) for receiving the several receiving volumes (80, 81, 82, 83, 84, 85, 86, 87) for receiving a fluid, a contacting area (60) in which the multi-channel lower part (20) is connectable to an upper part (12) of a fluid transfer device (100) on or in the spring chamber (15), wherein a first guide (54) for the piston actuator (40) or a component (56, 58) connected to the piston actuator (40) is formed in the spring chamber (15),and wherein a second guide (68) for the piston actuator (40) or a component (102, 104) connected to the piston actuator (40) is formed on an inner side of the housing (22) facing the receiving space (17).

2. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 1, wherein the first guide (54) and the second guide (68) are formed in alignment with one another.

3. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 1 or 2, characterized in that the second guide (68) is designed as a guide rail (66).

4. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 3, characterized in that the housing (22) has two housing shells (24, 26), wherein a guide rail (66) is formed on one of the housing shells (24, 26) on an inner wall delimiting the receiving space (17) wherein the piston actuator (40) is guided at its end facing away from the contacting area (60) through the guide rail (66).

5. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 3 or claim 4, characterized in that a guide body (102) is formed or formed on the piston actuator (40), which is guided in the guide rail (66) of the second guide (68).

6. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 5, characterized in that the guide body (102) is a guide pin (104).

7. Multi-channel lower part (20) for a liquid transfer device (100) according to one of claims 1 to 6, characterized in that a spring seat (56) and a spring lock (58) are arranged in the contacting area (60), wherein the first guide (54) is formed on the spring seat (56) and / or on the spring lock (58).

8. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 7, characterized in that the piston actuator (40) has a recess (44) in the contact area (60) into which a collar of the spring lock (58) engages.

9. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 7 or 8, characterized in that radially outwardly extending wings (92) are formed on the spring lock (58), which wings rest against the housing (22), the piston actuator (40) being centered by the wings (92).

10. Multi-channel lower part (20) for a liquid transfer device (100) according to one of claims 7 to 9, characterized in that the spring lock (58) is fixed in the housing (22) or in the spring seat (56) in the manner of a bayonet lock.

11. Multi-channel lower part (20) for a liquid transfer device (100) according to one of claims 1 to 10, characterized in that the first guide (54) in the spring chamber (15) is designed as a guide rail (106), wherein a spring seat (56) and / or a spring lock (58) are guided in the guide rail (106).

12. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 11, characterized in that the guide rail (106) is designed as a cylindrical guide (48), wherein a corresponding arc geometry is accommodated on the spring seat (56) and / or on the spring lock (58) in the cylindrical guide (48).

13. Multi-channel lower part (20) for a liquid transfer device (100) according to claim 11 or 12, characterized in that the guide rail (106) extends at least over half the length of the spring chamber (15).

14. Multi-channel fluid transfer device (100) with an upper part (12) and a multi-channel lower part (20) according to one of claims 1 to 12, wherein the upper part (12) has an operating element (16) which is designed to displace the piston actuator (20) of the multi-channel lower part (20) in the axial direction via a transfer element (19).

15. Multi-channel liquid transfer device (100) according to claim 14, wherein the multi-channel liquid transfer device (100) is a pipette (10) or a dispenser.

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