Stirring Tool and Stirrer Comprising a Tool of Said Type

Abstract

A stirring tool for a stirrer for stirring a mixture comprises a connecting element for connecting the stirring tool to a stirring drive, drivable about a rotational axis, of the stirrer, a carrier ring, a plurality of stirring spokes disposed between the connecting element and the carrier ring, and at least one stirring boss, which projects radially on the carrier ring, wherein two adjacent stirring spokes are arranged mutually offset in the direction of the rotational axis.

Claims

1. A stirring tool for a stirrer for stirring a mixture, wherein the stirring tool comprises a. a connecting element for connecting the stirring tool to a stirring drive, drivable about a rotational axis of the stirrer, b. a carrier ring, c. a plurality of stirring spokes disposed between the connecting element and the carrier ring, and d. at least one stirring boss, which projects radially on the carrier ring, wherein two adjacent stirring spokes are arranged mutually offset in the direction of the rotational axis.

2. The stirring tool as claimed in claim 1, wherein at least one first stirring spoke terminates flush with at least one of a top side of the stirring tool and/or at least one second stirring spoke terminates flush with a bottom side of the stirring tool.

3. The stirring tool as claimed in claim 1, wherein the stirring spokes respectively have a stirring spoke axis of straight-line configuration.

4. The stirring tool as claimed in claim 1, wherein the stirring tool is produced from plastic.

5. The stirring tool as claimed in claim 1, wherein the at least one stirring boss, with reference to a rotation angle about the rotational axis, is arranged between two stirring spokes.

6. The stirring tool as claimed in claim 1, comprising a plurality of stirring bosses, which in the peripheral direction of the stirring tool are arranged spaced apart.

7. The stirring tool as claimed in claim 1, wherein the stirring spokes respectively have a stirring spoke height (H.sub.S) which is less than a stirring tool height (H.sub.W).

8. The stirring tool as claimed in claim 1, wherein the stirring spokes respectively have a convexly configured cross-sectional shape.

9. The stirring tool as claimed in claim 1, wherein the contour of the at least one stirring boss is of exclusively convex configuration.

10. The stirring tool as claimed in claim 1, wherein the at least one stirring boss has a bearing portion for bearing against an inner wall of a stirring vessel, wherein the bearing portion has a bearing portion height (H.sub.A) which is less than a stirring tool height (H.sub.W).

11. The stirring tool as claimed in claim 10, wherein the at least one stirring boss within the bearing portion has a maximum stirring boss depth (T.sub.N,max) which defines a maximum stirring tool diameter (D.sub.R).

12. The stirring tool as claimed in claim 10, wherein the at least one stirring boss has a mixing portion for mixing the mixture, wherein the at least one stirring boss within the mixing portion has a reduced stirring boss depth.

13. The stirring tool as claimed in claim 1, wherein the at least one stirring boss has a leading surface for the onflow of the mixture against the stirring boss, wherein the at least one stirring boss has along the leading surface a reduced stirring boss depth.

14. The stirring tool as claimed in claim 13, wherein a peripheral angle (a.sub.An), related to the rotational axis, of the leading surface amounts to no more than 85% of a peripheral angle (a.sub.N) of the at least one stirring boss.

15. A stirrer for stirring a mixture with a drivable stirring drive and with a stirring tool, connected to the stirring drive, as claimed in claim 1.

16. The stirring tool as claimed in claim 1, wherein the at least one stirring boss, with reference to a rotation angle about the rotational axis, is arranged centrally between two stirring spokes.

17. The stirring tool as claimed in claim 1, comprising a plurality of stirring bosses, wherein respectively two stirring bosses are arranged diametrically opposite one another with respect to the rotational axis.

18. The stirring tool as claimed in claim 1, wherein the stirring spokes respectively have a stirring spoke height (H.sub.S) which is less than a stirring tool height (H.sub.W), wherein H.sub.S>0.75 H.sub.W.

19. The stirring tool as claimed in claim 1, wherein the stirring spokes respectively have a cross-sectional shape, which is arranged in relation to a stirring tool surface with an angle of inclination (w) different from zero.

20. The stirring tool as claimed in claim 10, wherein the at least one stirring boss has a mixing portion for mixing the mixture, wherein the at least one stirring boss within the mixing portion has a reduced stirring boss depth, which is less than a maximum stirring boss depth (T.sub.N,max).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 shows a schematic representation of a stirrer having a stirring tool,

[0032] FIG. 2 shows a perspective representation of a stirring tool according to the invention,

[0033] FIG. 3 shows a view from below of the stirring tool in FIG. 2,

[0034] FIG. 4 shows a cross section according to the sectional line IV-IV in FIG. 3,

[0035] FIG. 5 shows a cross section according to the sectional line V-V in FIG. 3,

[0036] FIG. 6 shows an enlarged detailed representation of a stirring boss according to the detail VI in FIG. 2,

[0037] FIG. 7 shows an enlarged side view of a stirring boss,

[0038] FIG. 8 shows a view according to the arrow VIII in FIG. 7,

[0039] FIG. 9 shows a sectional representation according to the sectional line IX-IX in FIG. 3,

[0040] FIG. 10 shows a sectional representation according to the sectional line X-X in FIG. 3,

[0041] FIG. 11 shows a sectional representation according to the sectional line XI-XI in FIG. 3, and

[0042] FIG. 12 shows a sectional representation according to the sectional line XII-XII in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] A stirrer 1 (represented in FIG. 1) serves to stir a mixture, in particular for medical, pharmaceutical or cosmetic products. The stirrer 1 has a substantially C-shaped frame 2, comprising a base 3, a vertical column 4 and a supporting arm 5. The supporting arm 5 is oriented in particular horizontally and in particular parallel to the base 3. The supporting arm 5 bears a stirring drive 6, which is configured as an electric motor. The stirring drive 6 is coupled, in particular via a gear mechanism, with a stirring shaft 7. A rotary motion of the stirring drive 6 is transmitted to the shaft 7 and to a stirring tool 8 connected thereto. The rotary motion of the shaft 7 is marked by the arrow 9. The shaft 7 is guided into a stirring vessel 10, which is referred to as a stone jar, and connected to the stirring tool 8 disposed in the stone jar. The stone jar has a bottom 11, a cylindrical side wall 12 and a lid 13. The lid 13 is held in a lifting fixture 15 by means of a holding portion 14. The lifting fixture 15 is configured as a cantilever arm and is vertically movable along the vertical column 4, as is indicated by a double arrow. For this, a driven linear guide 15a, for instance a spindle drive, is provided.

[0044] For a stirring operation, the stirring tool 8 is introduced into the stirring vessel 10 and the stirring vessel 10 is sealed by means of the lid 13. The stirring operation, i.e. the mixing of the mixture, is realized by driving of the stirring tool 8 along the rotational direction 9. In addition, a vertical movement of the lifting fixture 15 with the stirring vessel 10 fastened thereto can be realized. A relative movement in the vertical direction between stirring vessel 10 and stirring tool 8 is thereby ensured.

[0045] The stirring tool 8 is more closely illustrated in FIGS. 2 to 12. The stirring tool 8 is produced from plastic, and in particular from polyamide. The surface of the stirring tool 8 has a smooth and, in particular, high-gloss finish. The risk of an unwanted material adhesion to the stirring tool 8 is thereby reduced.

[0046] The stirring tool 8 comprises a connecting element 16 in the form of a hub. With the connecting element 16, the stirring tool 8 is connectable about a rotational axis 17 to the shaft 7. The rotational axis 17 of the stirring tool 8 corresponds to the rotational axis of the shaft 7. The stirring tool 8 is accommodated and held coaxially on the shaft 7. The connecting element 16 is of ring-shaped configuration. On an inner side of the ring are provided two latching elements 18, which ensure a latching connection to corresponding recesses on the shaft 7. The stirring tool 8 is held on the shaft 7 with reference to a rotation about the rotational axis 17 and in the axial direction of the rotational axis 17. The latching elements 18 have in a plane oriented perpendicular to the rotational axis 17 a segment-like contour.

[0047] The stirring tool 8 further has a carrier ring 19. An inner shell surface 22 of the carrier ring 19 can have a taper. That means that the inner shell surface 22 has a conical course with reference to the rotational axis 17, wherein the cone angle is less than 5° and in particular measures at least 0.5°. The taper facilitates the removal of the stirring tool 8 from a plastic injection molding mold. The carrier ring 19 is arranged coaxially to the connecting element 16. The carrier ring 19 is arranged coaxially to the rotational axis 17. The carrier ring 19 encloses the connecting element 16. In a height direction which is oriented parallel to the rotational axis 17, the carrier ring 19 and the connecting element 16 are of equal height. The carrier ring 19 and the connecting element 16 define a stirring tool height H.sub.W. According to the shown illustrative embodiment, the stirring tool height H.sub.W measures 3 mm. The carrier ring 19 has a ring thickness s.sub.R of 2 mm. The ring thickness s.sub.R is of importance for the structural elasticity of the carrier ring 19 and thus of the stirring tool 8. The structural elasticity of the stirring tool 8 is all the greater, the lesser the ring thickness s.sub.R is. In order to increase the structural elasticity, for instance, in relation to the shown illustrative embodiment of the stirring tool 8, the ring thickness s.sub.R can be chosen less than 2 mm. The carrier ring 19 has a ring diameter D.sub.R which, according to the shown illustrative embodiment, measures 54.4 mm.

[0048] Between the connecting element 16 and the carrier ring 19 are arranged six stirring spokes 20, 21. According to the shown illustrative embodiment, the stirring tool 8 comprises three first stirring spokes 20 and three second stirring spokes 21, which are arranged alternately in the peripheral direction about the rotational axis 17. The first stirring spokes 20 are respectively arranged such that they terminate flush with a top side which corresponds to the stirring tool surface 24. The second stirring spokes 21 are arranged such that they terminate flush with a bottom side 25 of the stirring tool 8. That means that two adjacent stirring spokes 20, 21 are arranged mutually offset in the direction of the rotational axis 17. Two adjacent stirring spokes 20, 21 have a height offset. The second stirring spokes 21 are arranged inclined with an angle of inclination in relation to the tool surface 24, wherein the angle of inclination of the second stirring spokes 21 corresponds to the negative angle of inclination of the first stirring spokes 20. For the angle of inclination w′ of the second stirring spokes 21: w′=−w or w′=180°−w. As a result of this arrangement of the stirring spokes 20, 21, an improved stirring result is possible. The six spokes 20, 21 are arranged radially with reference to the rotational axis 17. The stirring spokes 20, 21 respectively have a stirring spoke axis 23. The stirring spoke axes 23 are respectively of straight-line configuration. The stirring spoke axes 23 are oriented radially to the rotational axis 17.

[0049] The stirring spokes 20, 21 are arranged equally spaced with reference to a rotation angle about the rotational axis 17. The angle between two adjacent stirring spokes 20, 21 measures 60°. The intervening angle between two adjacent stirring spokes 20, 21 can be chosen larger or smaller in dependence on the number of stirring spokes.

[0050] The stirring spokes 20, 21 respectively have a cross-sectional shape which is oriented perpendicular to the stirring spoke axis 23 and which is of exclusively convex configuration. According to the shown illustrative embodiment, the cross-sectional shape is of lenticular configuration. The lenticular cross section has a lenticular length L.sub.L and a lenticular width LB. A principal axis of the cross-sectional shape, which is oriented along the lenticular length L.sub.L, is arranged inclined with an angle of inclination w in relation to a stirring tool surface 24. According to the shown illustrative embodiment: L.sub.L=4 mm, L.sub.B=1.6 mm and w=30°.

[0051] The stirring spokes 20, 21 have a stirring spoke height Hs which is less than the stirring tool height H.sub.W. According to the shown illustrative embodiment, the stirring spoke height Hs amounts to 70% of the stirring tool height H.sub.W.

[0052] On the carrier ring 19 are arranged six radially projecting stirring bosses 26. That means that the stirring tool 8 has precisely as many stirring spokes 20, 21 as stirring bosses 26. The stirring tool diameter D.sub.W is defined by the stirring bosses 26, in particular by their maximum stirring boss depth T.sub.N,max. According to the shown illustrative embodiment, the maximum stirring tool diameter D.sub.R measures 57.3 mm. The stirring boss depth T.sub.N is oriented in the radial direction with respect to the rotational axis 17.

[0053] The stirring bosses 26 are respectively, in a portion 27 between two stirring spokes 20, 21, integrally molded onto the carrier ring 19. That means that the stirring bosses 26 and the stirring spokes 20, 21 are arranged mutually offset. With reference to the rotational axis 17, a stirring boss 26 extends along a stirring boss included angle a.sub.N of 35°. A free region having a free region included angle a.sub.F correspondingly measures 25°. That means that the stirring boss 26 along the outer periphery of the carrier ring 19, in particular with reference to an included angle of the rotational axis 17, extends farther than the free region between two adjacent stirring bosses 26. Respectively two stirring bosses 26 are arranged diametrically opposite one another with respect to the rotational axis 17. The stirring tool 8 is supported via the stirring bosses 26 reliably against the inner surface of the stone jar. The stirring bosses 26 respectively have an exclusively convexly configured contour. Each stirring boss 26 has a bearing portion 28, a mixing portion 29 and a leading portion 30. The leading region 30 has a leading surface 31.

[0054] The bearing portion 28 serves to bear against an inner wall of the stirring vessel 10. The bearing portion 28 has a bearing portion height H.sub.A. The bearing portion height H.sub.A is less than the stirring tool height H.sub.W. The bearing portion height H.sub.A, according to the shown illustrative embodiment, amounts to 30% of the stirring tool height H.sub.W. According to the shown illustrative embodiment, the bearing portion 28 is a bearing edge. The bearing portion 28 is of linear configuration. The line is oriented parallel to the rotational axis 17. In the peripheral direction about the rotational axis 17, the bearing portion 28 according to the shown illustrative embodiment has merely an infinitesimal spread. According to the shown illustrative embodiment in FIG. 3, the bearing portion 28 is arranged with reference to a rotation angle about the rotational axis 17, along the rotational direction 9, 30° behind a front spoke 20, 21 facing the mixing portion 29 and, say, 60° ahead of a following spoke 20, 21 facing the leading region 30. The bearing portion 28 divides the free portion 27 approximately in the ratio 1:2. The bearing portion 28 can also be arranged centrally on the free portion 27 between two adjacent spokes 20, 21. In dependence on a mixing result to be obtained, in particular in dependence on the components to be mixed, the stone jar size and/or the stirring speed, i.e. the generated stirring dynamic, the stirring bosses 26 can be appropriately secured on the carrier ring.

[0055] With reference to the rotational axis 17, the bearing portion 28 can extend along an included angle of, for instance, 2° to 15°. In the region of the bearing portion 28, the stirring boss 26 has the maximum stirring boss depth T.sub.N,max. According to the shown illustrative embodiment, the maximum stirring boss depth T.sub.N,max measures 1.4 mm. According to the shown illustrative embodiment, the bearing portion 28 is configured as a dividing edge between the mixing portion 29 and the leading surface 31.

[0056] The stirring boss depth T.sub.N is variable along the rotational direction 9. On the front of the stirring boss 26 in the rotational direction 9 is arranged the leading surface 31. In the region of the leading portion 30, the stirring boss depth rises up to the maximum stirring boss depth T.sub.N,max at the transition to the bearing portion 28. The leading surface 31 extends within an included angle a.sub.An, which, according to the shown illustrative embodiment, measures 30°. Starting from the carrier ring 19, the leading surface 31 extends counter to the rotational direction 9 firstly over the complete stirring tool height H.sub.W, whereupon a portion with reduced height follows. The reduced height corresponds in particular to the bearing portion height H.sub.A.

[0057] The mixing portion 29 extends within the included angle a.sub.A in the peripheral direction. According to the shown illustrative embodiment, the included angle a.sub.A measures 5°. The bearing portion 28 has the bearing portion height H.sub.A. The leading portion 30 has a leading portion height H.sub.An. The sum of the two portion heights, i.e. the bearing portion height H.sub.A and the leading portion height H.sub.An, corresponds to the stirring tool height H.sub.W.

[0058] The mixing portion 29 and/or the leading portion 30 are distinguished by the fact that a gap is formed between an inner side of the stirring vessel and an outer cylinder surface of the stirring tool 8. Beneath the bearing portion 28 at which the maximum stirring boss depth T.sub.N,max obtains, the gap is formed by a radial depression of the stirring boss 26. Starting from the bearing portion 28, the depression extends in the peripheral direction, both in and counter to the rotational direction 9, beneath the bearing portion 28 with reference to the longitudinal axis 17. The depression is part of the leading portion 30.

[0059] The mixing portion 29 has a first segment having a mixing portion height which substantially corresponds to the bearing portion height H.sub.A. The first segment of the mixing portion 29 directly adjoins the bearing portion 28 counter to the rotational direction 9. Counter to the rotational direction 9, the first segment is adjoined by a second segment of the mixing portion 29. The mixing portion 29 has in the second segment, as the height, the stirring tool height H.sub.W. With the second segment, the mixing portion 29 is molded onto the carrier ring 19.

[0060] The geometry of the stirring boss 26 is illustrated once again on the basis of the sectional representations in FIG. 9 to FIG. 12. FIG. 9 shows a cross section through the carrier ring 19 along the sectional line IX-IX. The sectional line is defined outside the stirring boss 26. Correspondingly, the mixing portion 29 is visible. In a region represented at the top in FIG. 10, with the bearing portion height H.sub.A the bearing portion 28 is provided. Below, with the leading portion height H.sub.An, the leading portion 30 is provided. The sectional line X-X is arranged through the linear bearing portion 28 at the maximum stirring boss depth T.sub.N,max. The leading portion 30 is in this region disposed beneath the bearing portion 28. The mixing portion 29 and/or the leading portion 30 is/are formed by a reduction in the stirring boss depth in relation to the maximum stirring boss depth T.sub.N,max. The sectional line XI-XI is disposed in that region of the stirring boss 26 in which the stirring boss depth in total, and in particular along the whole of the stirring tool height H.sub.W, is reduced. The sectional line XII-XII is, in the rotational direction 9, in front of the stirring boss 26, which therefore is not discernible. The following second stirring spoke 21 is discernible.