Patent Application
20080006100
The invention is described in more detail hereinafter with reference to the accompanying drawings of an embodiment, in which:
While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated
According to
The basic structure 1 is, for example, produced from metal or from a rigid and solid plastic.
A fastening sleeve 6 with an external thread 7 is arranged externally on the fastening device 5, rotatable relative thereto and axially immovable. The fastening sleeve 6 is also produced from metal or a rigid and solid plastic.
A through-hole 8 extends coaxially to the fastening device 5 transversely through the base 2.
A piston actuating rod 9 extends coaxially through the fastening device 5 and through the through-hole 8. The piston actuating rod 9 has a coupling device 10 on one end projecting outwardly from the fastening device 5, for connecting to a drive device which comprises two peripheral circular disc-shaped shaft collars 11, 12 with a groove 13 therebetween.
The piston actuating rod 9 is connected on the inside of the base 2 to a cross-member 14 which is aligned transversely to the piston actuating rod 9.
In the fastening device 5 a helical spring 15 is arranged which is supported at one end on the outer face of the base 2 and at the other end on an abutment 16 in the form of a ring nut which is screwed onto the piston actuating rod 9 in the vicinity of an opening of the fastening device 5. The helical spring 15 is located in the position shown in a pretensioned state, so that it presses the cross-member 14 against the inside of the base 2.
The cross-member 14 has, on the side facing away from the base 2, a plurality of parallel receivers 17 for one respective piston head. Each receiver 17 is accessible from outside on the side facing away from the base 2 through a through-opening 18 in a base 19, The base 19 thus forms an edge defining the through-opening 18, which projects inwardly relative to the part of the receiver 17 located thereover.
Each receiver has an abutment surface 20, axially relative to the through-opening 18. Each receiver 17 is, moreover, accessible from outside through an insertion opening 21 extending perpendicular to the piston actuating rod 9 and to the cross-member 14 (and/or perpendicular to the drawing plane).
The piston actuating rod 9 and the cross-member 14 are, for example, produced from a metallic material or from a rigid and solid plastic.
A multipart housing 22 is fixed to the base structure 1, The housing 22 is relatively planar, i.e. its outer dimensions perpendicular to the drawing plane are only a fraction of the outer dimensions shown in the drawing plane.
In the housing 22 directly adjacent to the ends of the arms 3, 4 is a perforated plate 23 extending parallel to the base 2 with guide holes 24 extending in the axial direction of the piston actuating rod 9 and aligned with the through-holes 18.
At a further distance from the base 2 a further perforated plate 25 is arranged with threaded holes 26 coaxial relative to the guide holes 24. The further perforated plate 25 seals the housing 22 on said front face.
The housing 22 is produced from a rigid and solid plastic or from a metallic material.
Moreover, the pipetting device comprises a plurality of cylinders 27 with a cylindrical hollow space 28 which are connected integrally to a seat 29 in the form of a tapered portion for a pipette tip. The cylindrical hollow space 28 is connected via a tapered through-channel 30 to a through-hole 31 in a front face of the seat 29.
Each cylinder 27 has a peripheral flange 32. Moreover each cylinder 27 has, on the side of the seat 29 in the vicinity of the flange 32, an external thread 33. The cylinder 26 consists of a metallic material or from a rigid and solid plastic.
Each cylinder 27 is inserted into a guide bore 24 and screwed into a threaded bore 26 coaxial thereto, so that the flange 32 is positioned on the inside of the further perforated plate 25. Instead of which, the cylinder 27 may be designed without an external thread 33, and inserted into a threadless hole of the further perforated plate 25. A spring may hold the flange 32 in abutment against the further perforated plate 25. In this position, the seat 29 projects outwardly beyond the adjacent front face of the housing 22.
An annular groove 34 circulates around the periphery of the seat 29 and in which a seat sealing ring 35 is arranged.
All guide bores 24 and threaded bores 26 are equipped in the aforementioned manner with cylinders 27. In the drawings, only one individual cylinder 27 is shown for simplification.
A piston 36 is axially displaceably guided in each cylinder 27.
Each piston 36 has a piston head 38 at the end of a piston rod 37 projecting from the cylinder 27.
Each piston head 38 encompasses an annular disc 39 and a tapered portion 40 (see
On the side of the piston rod 37, the piston head 38 has a lower face 41 and a planar upper face 42 on the opposing side.
Proceeding from the upper face 42 the piston comprises a blind hole 43 which has a recess 44 on the base. Said recess has radial widened portions 45, 46 which extend perpendicular to the drawing plane of
A resilient body 47 is arranged in the blind hole 43. The resilient body 47 is cylindrical in the region of the blind hole 43 and spherical in a region projecting beyond the upper face 42. In the example, the region 48 of the resilient body 47 projecting beyond the upper face 42 has the shape of a hemisphere.
The resilient body is anchored below in the piston head 38 by the strip-shaped portion 49 arranged in the recess 44 and the widened portions 45, 46.
The end of the piston 36 opposing the piston head 38 comprises a narrow tapered portion 50, the cone angle thereof corresponding to that of the through-channel 30. A peripheral annular groove 51 is present between the tapered portion 50 and the piston rod 37 which receives a piston seal 52 in the form of a piston sealing ring.
The piston 36 is produced in a two-component injection-moulding method. In this connection, the piston 36 is produced from a hard plastic, for example from a thermoplastic such as Fortron (glass-fibre reinforced polyvinyl sulphide from the Hoechst company). The resilient body 47 is injection-moulded in a second injection cycle from silicone (rubber) or from a thermoplastic elastomer onto the piston 36.
Each piston 36 is arranged with the tapered portion 50 and the piston seal 52 in the cylindrical hollow space 28, even if the piston 36 is withdrawn to a maximum extent from the cylinder 27 (
Each piston head 38 is located in a receiver 17 coaxial to the cylinder 27. In this connection the piston rod 37 extends through the through-hole 18.
The piston head 38 is positioned in the region of the circular disc 30 with the lower face 41 on the base 19.
Moreover, the spherical region 48 of the resilient body 47 is positioned on the abutment surface 20. The resilient body 47 is slightly elastically compressed in the spherical region 48.
Each piston 36 may be connected by simple insertion of the piston head 38 through the insertion opening 21 into the receiver 17 with the cross-member 14. Due to the elastic compression of the resilient body 47, it is held in a defined position in the receiver 17 and play between the piston head 38 and the receiver 17 is compensated thereby. Conversely, the piston 36 may be disassembled extremely easily.
For pipetting, the pipetting device is connected to a drive device 53. To this end, it is inserted with the fastening device 5 in a fastening receiver 54 of the drive device 53 and by screwing the fastening ring 6 into an internal thread 55 of the fastening receiver 54 connected thereto. In this connection, the fastening device 5 is positioned with its frontal end on the bottom of the fastening receiver 54.
Moreover, the coupling device 10 is connected to a further coupling device 56 of a lineal drive 57 of the drive device 53 adjusted thereto.
By axial displacement of the linear drive 57 the piston actuating rod 9 and the pistons 36 connected thereto may be displaced. In this connection, the pistons 36 displace air columns inside the hollow spaces 28 and the connecting channels 30, in order to eject liquid from and/or to suction liquid into the pipette tips mounted on the seat 29.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.
Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.
This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 031 460.3 | Jul 2006 | DE | national |
