MULTICHANNEL PIPETTING HEAD

Abstract

A multichannel pipetting head comprises a plunger actuator comprising at least one groove with an upper border, and a lower border. A plurality of plunger-cylinder units, wherein each plunger-cylinder unit comprises a cylinder and a plunger comprising a plunger head. The plunger head comprises a projecting upper abutment region adjoining the upper border, a projecting lower abutment region adjoining the lower border and laterally offset relative to the projecting upper abutment region, a plurality of guides. Each of the cylinders is coupled to a neck and held on each of the plurality of guides. During lateral movement of the plurality of guides, the plunger head is configured to tilt in the groove and to be held with the upper abutment region abutting the upper border and with the lower abutment region abutting the lower border of the groove due to restoring forces that occur during tilting in the plunger-cylinder units.

Claims

1. A multichannel pipetting head comprising: a horizontal plunger actuator comprising at least one groove, the at least one groove comprising an upper border, a lower border, and defining a side opening; a drive rod configured to move the horizontal plunger actuator in a vertical direction; a plurality of plunger-cylinder units, wherein each plunger-cylinder unit comprises, a hollow cylinder, and a plunger comprising a plunger head, the plunger head comprising, a projecting upper abutment region adjoining the upper border of the horizontal plunger actuator; a projecting lower abutment region. adjoining the lower border of the horizontal plunger actuator and laterally offset relative to the projecting upper abutment region, wherein the plunger is configured to engage the hollow cylinder and is sealed off from the hollow cylinder and wherein the plunger head engages the groove through the opening; and a plurality of guides configured to be shifted along a horizontal shaft, wherein each of the hollow cylinders is coupled to a neck and is held on each of the plurality of guides, wherein during a lateral movement of the plurality of guides along the horizontal shaft, the plunger head is configured to tilt in the groove and is configured to be held with the upper abutment region abutting the upper border and with the lower abutment region abutting the lower border of the groove due to restoring forces that occur during tilting in the plunger-cylinder units.

2. The multichannel pipetting head according to claim 1, wherein when the plunger-cylinder unit is comprised of a rigid material, the plunger head and the groove are configured to form an interference fit.

3. The multichannel pipetting head according to claim 1, wherein at least one of (1) the projecting upper abutment region of the plunger head is an upper abutment point on a top side; and (2) the projecting lower abutment region is a lower abutment point on a bottom side.

4. The multichannel pipetting head according to claim 3, wherein at least one of: (1) the upper abutment point is positioned on a spherical cap on the top side; and (2) the lower abutment point is positioned on a lower edge of the cylinder.

5. The multichannel pipetting head according to claim 1, wherein the plurality of guides are rotatably mounted on the horizontal shaft.

6. The multichannel pipetting head according to claim 3, wherein lower abutment points are laterally offset further from the horizontal shaft than the upper abutment points.

7. The multichannel pipetting head according to claim 1, wherein the groove comprises an upper border opposite the lower border that projects further in a horizontal direction from one side, wherein the one side defines the opening.

8. The multichannel pipetting head according to claim 1, wherein each cylinder comprises resilient hat-leather packing at a top through which a plunger rod connected to the plunger is guided in an upwardly sealing manner.

9. The multichannel pipetting head according to claim 1, wherein each plunger comprises a circumferential resilient sealing element positioned on an outer circumference and configured to seal a plunger running surface on an inner side of the hollow cylinder.

10. The multichannel pipetting head according to claim 1, wherein each neck is supported on the plurality of guides via a compression spring, wherein each neck is configured to he moved upward relative to the plurality of guides counter to the compression spring.

11. The multichannel pipetting head according to claim 1, wherein each plunger comprises a plunger rod configured to resiliently bend outward.

12. The multichannel pipetting head according to claim 1, wherein each of the plurality of guides is configured to he moved in a horizontal direction using a control mechanism.

13. The multichannel pipetting head according to claim 12, wherein the control mechanism is a scissor lever mechanism comprising, an adjusting wheel, a gear wheel, a toothed slide, and a grid.

14. The multichannel pipetting head according to claim 13, wherein each of the plurality of guides is suspended at a top and a bottom of the grid.

15. The multichannel pipetting head according to claim 14, wherein each of the plurality of guides is suspended on necks projecting from the grid through one of: (1) a hole and a vertical longitudinal slot; and (2) two vertical longitudinal slots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be further explained below with reference to the accompanying drawings of exemplary embodiments. In the drawings:

[0024] FIG. 1 illustrates a front view of an embodiment a multichannel pipetting head with the front housing part removed;

[0025] FIG. 2 illustrates a sectional view of an embodiment of a guide with a neck and a plunger-cylinder unit of the multichannel pipetting of FIG. 1;

[0026] FIG. 3 illustrates an enlarged view of the embodiment of detail from FIG. 2;

[0027] FIG. 4 illustrates a sectional view of an embodiment of the multichannel pipetting head of FIG. 1 through a guide;

[0028] FIG. 5 illustrates a sectional view of an embodiment of a guide with neck and plunger-cylinder unit and plunger actuator of another embodiment of a multichannel pipetting head; and

[0029] FIG. 6 illustrates an enlarged view of detail VI FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In the present application, the terms “at the top” and “at the bottom” as well as “side” or “lateral(ly)” relate to a multichannel pipetting head which is oriented vertically with the plunger-cylinder units and in which the drive rod is arranged above the necks.

[0031] According to FIGS. 1 to 3, the multichannel pipetting head 1 comprises a support structure 2 formed of a two-part housing 3. In FIG. 1, a front housing part has been removed such that only a rear housing part is shown. Alternatively, the support structure may also be formed of a chassis that is clad with a housing.

[0032] The housing 3 is substantially box-shaped. A fastening neck 4 for connection to a pipette top part projects vertically upward on the upper edge of the housing 3. A horizontal shalt 5 having a circular cross-section is held in the housing. Multiple guides 6 (in example 4) are held on. the shaft 5 so as to he movable in the horizontal direction and pivotable about the shaft 5.

[0033] According to FIG. 2, each guide 6 comprises an approximately cuboid bearing portion 7 on the lower end that comprises a horizontal first bearing bore 8. According to FIG. 1, the guide is mounted by means of the first bearing bore 8 on the shaft 5 so as to be movable in the direction of the shaft and pivotable about the shaft 5. According to FIG. 4, the bearing portion 7 comprises a vertical slot 9 which proceeds from the side furthest away from the first bearing bore 8 and ends shortly before the first bearing bore 8. An upper neck portion 10 of a hollow neck 11 for clamping pipette tips is inserted in the slot 9. The neck 11 is connected at the top to a hollow cylinder 12 of a plunger-cylinder unit 13. The hollow space 14 in the neck 11 is connected to the hollow space 16 in the cylinder 12 via a through-hole 15. The inner side of the cylinder 12 forms a running surface for a plunger.

[0034] The neck 11 comprises a lower shoulder 17 at the lower end of the upper neck portion 10 and the cylinder 12 comprises an upper shoulder 18 at the upper end of the upper neck portion 10. The lower shoulder 17 adjoins the bottom side of the bearing portion 7 and the upper shoulder 18 adjoins the top side of the bearing portion 7, such that the neck 11 and cylinder 12 are held in the bearing portion 7 so as to be immovable in the vertical direction. The upper neck portion 10 is secured in the slot 9 by means of a pin 19 that is inserted in a horizontal pin bore 20 of the bearing, portion 7 that intersects the slot 9. At the bottom, the neck 11 comprises a conical portion 11.1 and above that a cylindrical portion 11.2. The conical portion 11.1 is provided with a circumferential annular groove 21 for inserting a sealing ring.

[0035] According to FIGS. 2 and 4, a sleeve-like guide portion 22 projects vertically upward from the top side of the bearing portion 7. The cylinder 12 is supported on the outside on various sides on first and second contact regions 22.1, 22.2 of the guide portion 22. A holding portion 23 having a flat U-profile projects vertically upward from the sleeve-like guide portion 22 above the first bearing bore 8. According to FIGS. 1 and 4, the guides 6 each comprise a longitudinal slot 24, 25 at the top and at the bottom. The longitudinal slots 24, 25 are used to engage upper and lower bearing bolts of a scissor lever mechanism (grid) for moving the guides 6 relative to one another in the horizontal direction. The guides 6 are preferably manufactured in one piece from plastics material, e.g. by means of injection-molding. The neck 11 and cylinder 12 are manufactured in one piece or in multiple pieces from plastics material (e.g. by means of injection-molding) and/or from metal (e.g. by means of turning).

[0036] According to FIGS. 2 and 4, each plunger-cylinder unit 13 comprises a plunger 26, which is pushed into the cylinder 12 from above. The plunger 26 comprises a plunger rod 27 having a thickened plunger portion 28 on the lower end, on which sits a circumferential sealing element 29. The plunger comprises a plunger head 30 on the upper end of the plunger rod 27. The plunger head 30 comprises a planar, e.g. circular disk-shaped portion 31, which has an upper abutment region 32 on the top side and a lower abutment region 33 on the bottom side. The upper abutment region 32 is located on the vertex of a spherical cap 34 on the top side of the circular disk-shaped portion 31. The lower abutment region 33 is located on the lower edge 35 of a cylinder 36 projecting downward next to the plunger rod 27 from the bottom side of the circular disk-shaped portion 31 next to the plunger rod 27. More precisely, the lower abutment region 33 is located on a radius 37 on the lower edge of the cylinder 36. In an embodiment, the plunger 26 is manufactured in one piece from plastics material, preferably by means of injection-molding. The sealing element 29 may also be manufactured in one piece with the plunger 26 or be clamped thereon.

[0037] According to FIGS. 1 and 4, the multichannel pipetting head 1 comprises a horizontal plunger actuator 38 arranged next to the holding portions 23 above the cylinder 12. The plunger actuator 38 comprises a horizontal groove 39 on the side opposite the holding portions 23.

[0038] An upper border 40 of the groove 39 projects further toward the holding portion than a lower border 41. The groove 39 comprises an opening 42 on the side of the holding portions 23. A part of the plunger heads 30 is inserted into the groove 39 through the opening 42, such that the spherical cap 34 adjoins the upper border 40 by means of the upper support region 32 and the cylinder 33 adjoins the lower border 41 by means of the lower support region 33. The holding portion 23 is pivoted against the plunger actuator 38.

[0039] A drive rod 43 that protrudes into the fastening cylinder 4 projects upward from the top side of the plunger actuator 38. The plunger actuator 38 and the drive rod 43 are preferably manufactured in one piece from plastics material, preferably by means of injection-molding.

[0040] The fastening cylinder 4 is configured to be connected to a pipette top part via a snap connection and the upper end of the drive rod 43 can be connected to a drive apparatus in the pipette top part for vertically moving the drive rod 43 via a clamp connection. The plunger head 30 and the groove 39 are dimensioned such that the plunger head 30 would form an interference fit with the groove 39 at the upper and lower abutment points 32, 33 if the plunger-cylinder units. 13 were rigid and not elastically deformable. In particular, the plunger rod 27 and the sealing element 29 of the plunger-cylinder units 13 are designed to be resilient, such that the plunger heads 30 can tilt in the groove 39 under the elastic deformation of the plunger-cylinder units 13.

[0041] When the plunger head 30 and plunger actuator 38 are joined, the fact of the plunger head 30 being oversized relative to the groove 39 causes the plunger head 30 to be inclined with respect to the vertical (e.g. by 0.5°). In this position, the plunger 26 can be easily moved in the axial direction in the plunger actuator 38 by means of the plunger head 30. The preload in the plunger-cylinder unit 13 generated by the inclination of the plunger head 30 holds the plunger head 30 in the tilted position. The guide 6 and the cylinder 12 cannot follow the inclination A (cf. FIG. 4) of the plunger head 30, since the guide 7 strikes the plunger actuator 38 and thus blocks inward rotation. Since the plunger 26 comprises a lower support point 45 on the sealing element in the cylinder 12 in addition to the upper support point 44 in the plunger actuator 38. It is deformed in the manner of a flexible spring B (cf. FIG. 4). As a result, a counterforce is generated which causes the plunger 26 to rest against the abutment points 32, 33 in the plunger actuator 38 in a clearance-free manner at all times and prevents play of the plunger head 26 in the groove 39.

[0042] The embodiment shown in FIGS. 5 and 6 differs from that described above in that the lower plunger portion is the lower end of the plunger rod 27. Furthermore, the plunger 26 is not sealed off by means of a sealing element in a plunger running path of the cylinder 12, but rather by means of hat-leather packing 46, which is clamped onto the upper end of the cylinder 12 and rests on the outer side of the plunger rod 27 outside the cylinder 12. The plunger head 30 rests on the upper end of the plunger rod 27.

[0043] In this embodiment, the plunger rod 27 is preferably formed by a steel needle and the plunger head 30 is molded from plastics material onto the upper end of the steel needle. The counterforce for holding the plunger head in abutment with the groove 39 is generated by the elastic deformation of the hat-leather packing 46 and the steel needle. Furthermore, the neck 11 is held in a vertical second bearing bore 47 in the bearing portion 7 of the guide 6. The neck 11 is supported on the bearing portion 7 of the guide 6 via a compression spring 48. The compression spring 48 is guided on an upper neck portion 10 and supported at the bottom on a lower shoulder 17 of the upper neck portion 10 and at the top on the bottom. side of the bearing portion 7. Further up, the upper neck portion 10 has a tangentially flattened portion 49 on the circumference for engagement of a pin 19 inserted into a horizontal pin bore 20 of the bearing portion 7. As a result, the neck 11 and the cylinder 12 integrally connected thereto is secured on the bearing portion 7 and the vertical movement of the neck 11 in the bearing portion 7 is limited.

[0044] On account of the necks 7 being held on the guides 6 in a spring-loaded manner, the pipette tips are clamped on the various necks 7 at substantially equal heights.