EP2659958B1 - Cogged mixing element - Google Patents

Description

The invention relates to a mixing element for mixing medical, pharmaceutical or cosmetic products according to the preamble of claim 1. In particular, the invention relates to a mixing element for mixing medical, pharmaceutical or cosmetic products, which is a hub for preferably reversible rotationally and axially fixed coupling comprising a drive shaft of a stirrer, an at least approximately concentrically arranged around the hub, annular Rührteilträger, and at least one spoke element for rotationally and axially fixed connecting the Rührteilträgers with the hub.

In the production of medical, pharmaceutical or cosmetic products, such as, for example, ointments, pastes, creams or powders, it is known in practice that different mixture constituents are mixed together in a cylindrical vessel, which is also referred to as a jar, by means of a mixing element be emulsified. This mixing element can be, for example, a mixing disk in which an annular stirring part is arranged concentrically around a hub provided centrally for this purpose. The stirring member and the hub are firmly connected to each other by a plurality of webs extending radially from the hub.

The hub is in turn coupled by a rotationally and axially fixed coupling with the end of a drive shaft of a stirrer. This coupling is either a permanent or a detachable connection. The drive shaft is rotated by the drive of the mixer in rotation, whereby the mixing disk is brought into a rotational movement.

For the actual preparation of the medical, pharmaceutical or cosmetic end products, the mixing disk is positioned in the mixing or stirring vessel. After the individual mixture components have also been introduced into the mixing vessel, the mixing disk is rotated by the drive shaft. Due to the rotational or rotational movement and any additional stroke movement of the mixing disk, the individual mixture components are mixed together to produce the final product. Such a mixing disk is for example in the EP patent 0 987 055 disclosed.

The German patent application DE 22 04 558 A1 discloses an apparatus for refining liquid viscous material having a horizontal cylindrical vessel, a material inlet and outlet at opposite ends of the vessel and at least one outlet for venting volatile material, a heating jacket, one substantially concentric with the cylinder axis within the vessel rotatable agitator and a drive shaft, wherein the agitator shaft memory wheels are placed in which the inner edge of each rim is left intact in a closed circle, while the outer edge of the wheel rim has projections which cause a continuous film formation and from the inlet to the outlet end of the reactor, the material which has a melt viscosity of about 1,000 poise to 100,000 poise.

The mixture constituents to be mixed together for the production of medical, pharmaceutical or cosmetic products are often constituents of different consistency. In addition, the mixture components often have a different density and / or a different viscosity. Furthermore, some of the mixture components may also contain suspended particles in the form of small solids, which may occur in different amounts and sizes in the respective components. It is also possible that mixture components should be mixed in powder form with liquid mixture components. Because of these different physical properties and the different states of aggregation of the individual constituents of the mixture, there is often no uniform mixing behavior when mixing these constituents to form a final product. In particular, due to the different density and viscosity of the individual mixture constituents to be mixed, the individual constituents and any suspended particles having a high density or a high viscosity move during the mixing process into the outer marginal area of the mixing or stirring vessel, ie away from the inner area between agitator and drive shaft. In contrast, the move Mixing components and possibly existing suspended particles with a low density or a low viscosity in the mixing process rather in the interior between the stirring member and hub. Due to this different behavior and the different positioning of the individual mixture constituents to one another, the mixing process for achieving a homogeneously mixed end product can be substantially prolonged or not terminated at all.

By longer mixing operations to achieve a homogeneously mixed end product there is also the risk that unintentionally additional heat energy is supplied to the mix. Often, this additional heat energy can cause heat-sensitive mixture components to deteriorate in their properties and thus the quality of the final product is deteriorated. In addition, longer blending operations produce unnecessary and higher manufacturing costs and generally adversely affect the efficiency of the blending process.

It is an object of the present invention to solve these problems. In particular, it is an object of the present invention to provide a mixing element according to the type mentioned, with which a fast and efficient production of homogeneously mixed, medical, pharmaceutical or cosmetic products with very different properties can be achieved and in this way a more efficient and thus more cost-effective production of ointments, pastes, creams or powders can be guaranteed.

The above-described object is solved by the features of independent claim 1. In the subsequent claims 2 to 15 are advantageous embodiments of this.

In particular, a mixing element for mixing medical, pharmaceutical or cosmetic products is provided that a hub for preferably reversible rotationally and axially fixed coupling with a drive shaft of a stirrer, an at least approximately concentric to the hub ange ange arranged, annular Rührteilträger and at least one spoke element for rotationally and axially fixed connecting the Rührteilträgers having the hub. It is further provided that at least two stirring teeth are provided on the outer peripheral side of the Rührteilträgers, and that the mean circumferential length of at least one stirring tooth, as viewed in the plane of the Rührteilträgers spanned central plane of the Rührteilträgers, equal to the distance between two successive Rührzähnen each other in the circumferential direction of the Rührteilträgers is. By providing the stirring teeth on the outer peripheral side of the Rührteilträgers additional partial streams are generated in addition to the mixed flow generated by the mixing element in total, which allow an improved and faster mixing of the individual different mixture components with each other. In addition, by the stirring teeth on the inner peripheral wall of the mixing vessel adhering components of the mixed material can be easily replaced. Furthermore, it is provided that the at least one spoke element runs at least partially in a circular arc segment from the hub to the inner peripheral surface of the stirring member carrier in the center plane of the stirring member carrier spanned by the annular member of the stirring member carrier. As a result, a good mixing of the mix is also achieved.

Already with two stirring teeth, which extend over a large outer peripheral portion of the Rührteilträgers with a corresponding distance from each other, excellent mixing results can be achieved with the mixing element according to the invention. However, it is also possible that more than two stirring teeth are arranged on the outer peripheral side of the Rührteilträgers. Here, the number of stirring teeth may be provided depending on the diameter of the stirring member carrier, that is, that as the diameter increases, the number of stirring teeth increases in the same manner, for example linearly, but also quadratically and so on. Also, with the same diameter of the Rührteilträgers a different number of Rührzähnen be provided. There is the possibility that both an even and an odd number of stirring teeth is arranged on the Rührteilträger.

In order to achieve the most robust and robust form possible for a stirring tooth, it is advantageous if the shape of at least one stirring tooth, viewed in the center plane spanned by the annular shape of the stirring member carrier of the Rührteilträgers, at least approximately that of a trapezoid, preferably an isosceles trapezoid. The two parallel ones are running Pages of the trapezium in a circular arc corresponding to the ring shape of the Rührteilträgers.

Another possible form for a stirring tooth may be that the shape of at least one stirring tooth, as viewed in the center plane of the stirring member carrier spanned by the annular shape of the stirring member carrier, is at least approximately that of a circular arc segment.

In the two above-described forms for the stirring teeth, the flanks facing in the two circumferential directions of the stirring member carrier have the same configuration. In order to be able to use the same mixing element also the ability to smash suspended particles, which are located in one or all of the mixture components of the mix, can also be provided in an advantageous manner that at least one of the pointing in one of the circumferential directions of the Rührteilträgers flanks at least one stirring tooth extends at least approximately radially to the hub. In other words, this flank extends at least approximately perpendicular to one of the circumferential directions of the stirring member carrier or one of the directions of rotation of the mixing element. If the stirring tooth provided with such an edge has the shape of a trapezoid, then this stirring tooth takes the form of a rectangular trapezium. Thus, the mixing element can be used so that upon rotation of the mixing element in a direction of rotation or in one of the circumferential directions of the Rührteilträgers in which the flank oblique (trapezoidal) or rounded (circular arc segmental shape), good mixing is achieved, whereas during a rotation of the mixing element in the opposite direction of rotation or circumferential direction of the Rührteilträgers by the at least approximately radially extending flank a shattering of the suspended particles is achieved. Consequently, one and the same mixing element can be used for different tasks.

The above-described embodiments for the stirring teeth can be provided on them in such a way that all the stirring teeth are the same or all the stirring teeth are unequal or the stirring teeth are arranged unequal and equal to one another. In the latter case, for example, every second stirring tooth, the trapezoidal shape and each first stirring tooth, the circular arc segment shape, optionally with or without perpendicular flank. Of course, the arrangement of a right-angled flank can also be provided here regularly or irregularly.

Furthermore, it can be provided that the outer surfaces of at least the stirring member carrier and the stirring teeth pointing in the direction of the central longitudinal axis or the rotational axis of the hub are arranged in two planes extending at least approximately parallel to each other and at least approximately perpendicular to the central longitudinal or rotational axis of the hub. In this case, the distance of the two planes smaller, preferably much smaller than the diameter of the Rührteilträgers be selected. This gives the mixing element the design of a mixing disk, which has a small thickness, whereby the space occupied by the mixing element space within the mixing or mixing vessel is low.

With regard to the diameter of the mixing element according to the invention, it should be noted that it can be selected to include the stirring teeth in accordance with the inner diameter of the stirring or mixing vessel. It is likewise possible for the diameter of the mixing element according to the invention, including the stirring teeth, to be smaller than the inner diameter of the stirring vessel. This makes it possible that the mixing element can be moved back and forth not only in the vertical direction in the mixing vessel, but that the mixing element can also perform a slight oscillating movement in a plane perpendicular to the central longitudinal or rotational axis of the hub. This also supports the mixing result, in particular the detachment of adhering to the inner peripheral wall of the mixing vessel components of the mix.

The provision of a spoke member for rotationally and axially fixed connection between the hub and Rührteilträger allows the mixing element through the Mixing material can be moved in the direction of the central longitudinal or rotational axis of the hub, since the mix can flow past the at least one spoke element.

A shape for a spoke element can advantageously consist in that the at least one spoke element has a first in the first circumferential direction of the Rührteilträgers or in the first direction of rotation of the mixing element facing the stirring surface and a second in the second circumferential direction of the Rührteilträgers or in the second direction of rotation Mixing element facing stirring surface, wherein the two stirring surfaces of the spoke element at least approximately parallel to each other. It is also possible for the at least one spoke element to have a first stirring surface pointing in the first circumferential direction of the stirring member carrier or the first rotational direction and a second stirring face pointing in the second circumferential direction of the stirring member carrier or in the second rotational direction of the mixing element, wherein the first stirring surface and the second stirring surface are in two intersecting planes.

Furthermore, it can be provided that at least one stirring surface of the at least one spoke element extends at least approximately perpendicular to one of the two circumferential directions of the stirring member carrier. As a result, an optimal attack or impact surface is formed on the spoke element, with which the mixture components can be mixed together and additionally smash the suspended in a mixture component suspended particles.

There is also the possibility that at least one stirring surface of the at least one spoke element extends in a plane which is aligned obliquely to the circumferential direction of the Rührteilträgers or the direction of rotation of the mixing element. Such an oblique configuration allows easy penetration of the mixed material in the stirring process, whereby at the same time by the inclination of the stirring surface partial flows are generated in a direction parallel to the central longitudinal or rotational axis of the scar.

Of course, a plurality of spoke elements between the hub and Rührteilträger be provided. Again, the spoke elements can all have the same shape or different shapes, which also has the possibility that a first spoke element has a shape and that subsequent spoke element of a plurality of spoke elements another shape, this sequence then continues for all spoke elements.

As already explained above, a plurality of spoke elements can be provided on a mixing element. These can, as well as the stirring teeth all be the same or regular or random alternately designed. Likewise, the orientation of the stirring surfaces of all spoke elements may be the same or different or may be provided on a spoke element two differently configured stirring surfaces. If the spoke elements have oblique stirring surfaces, it may further be provided that these stirring surfaces are aligned differently on successive spoke elements, i. in other words, that has an oblique stirring surface, for example in the direction of the bottom of the mixing vessel, whereas the other inclined stirring surface is aligned in the direction of the lid of the mixing vessel.

The ideas of the invention described above in connection with the spoke element can be used not only together with the above-described Rührteilträger and the stirring teeth but also independently thereof. In other words, the embodiments of the spoke element (s) can also be used in a mixing element which has no stirring member carrier and / or stirring teeth of the type explained above.

Advantageously, the mixing element, which consists of the hub, the at least one spoke element, the Rührteilträger and the at least two stirring teeth, integrally formed.

As material for the mixing element, different materials can be used, it being advantageous that a suitable plastic is selected.

Fig. 1

eine perspektivische Ansicht einer ersten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle;

Fig. 2

eine perspektivische Ansicht einer zweiten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle in einem ausgeschnittenen Rührgefäß;

Fig. 3

eine perspektivische Ansicht einer zweiten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle;

Fig. 4

eine perspektivische Ansicht einer dritten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle;

Fig. 5

eine perspektivische Ansicht einer vierten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle;

Fig. 6

eine perspektivische Ansicht einer fünften Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle; und

Fig. 7

eine perspektivische Ansicht einer sechsten Ausführungsform des erfindungsgemäßen Mischelements an einer nur teilweise dargestellten Antriebswelle.

Further advantageous embodiments and two embodiments of the invention will be explained in more detail below in connection with the description of the accompanying drawing figures. The terms "top", "bottom", "right" and "left" used in the description of the exemplary embodiments relate to the drawing figures in an orientation with normally readable reference numerals and figure names. Showing:

Fig. 1

a perspective view of a first embodiment of the mixing element according to the invention on a drive shaft only partially shown;

Fig. 2

a perspective view of a second embodiment of the mixing element according to the invention on a drive shaft only partially shown in a cut-out mixing vessel;

Fig. 3

a perspective view of a second embodiment of the mixing element according to the invention on a drive shaft only partially shown;

Fig. 4

a perspective view of a third embodiment of the mixing element according to the invention on a drive shaft only partially shown;

Fig. 5

a perspective view of a fourth embodiment of the mixing element according to the invention on a drive shaft only partially shown;

Fig. 6

a perspective view of a fifth embodiment of the mixing element according to the invention on a drive shaft only partially shown; and

Fig. 7

a perspective view of a sixth embodiment of the mixing element according to the invention on a drive shaft only partially shown.

Fig. 1 shows a perspective view of a first embodiment of the mixing element 10 according to the invention, which is coupled to an only partially shown drive shaft 20 of a known stirring device (not shown), which is used in the manufacture of medical, pharmaceutical or cosmetic products. As in Fig. 2 For this purpose, the mixing element 10 according to the invention is often located in a suitable cylindrical mixing vessel, which is also referred to as a jug K. The mixing element 10 has as main components a hub 30, spoke elements 40 and an annular stirring member carrier 60 with stirring teeth 80. These components will be described in detail below.

The mixing element 10 has a substantially flat upper side 12 and a substantially flat lower side (not shown), which extend at least approximately parallel. How out Fig. 1 it can be seen, the distance between the top 12 and the bottom is chosen so that the thickness of the mixing element 10 is much smaller than the diameter thereof.

The centrally disposed in the mixing element 10, a substantially circular cylindrical cross-section having hub 30 includes an opening, not shown, for receiving the one end face of the drive shaft 20. This front end of the drive shaft 20 is in this case detachably coupled to the hub 30. The releasable coupling between drive shaft 20 and hub 30 may be provided by a connecting means, such as e.g. a bayonet lock or the like, be realized. Alternatively, however, it is also possible that a permanent connection between the hub 30 and the drive shaft 20 is made. For this purpose, the mixing element 10 and the drive shaft 20 can be made together with the hub 30 in one piece.

The other front end of the drive shaft 20, not shown, is connected to the drive of the mixer, also not shown. The mixing element 10 is in such an alignment with the drive shaft 20 that the top side 12 of the mixing element 10 to the mixer and the bottom in the direction of the bottom of a mixing or mixing vessel, also not shown.

As already stated, there is the possibility that the mixing element 10 with the drive shaft 20 is releasably coupled or the mixing element 10 and the drive shaft 20, which can then form a one-piece unit, are releasably coupled to the drive means of the stirrer. In the former case, there is the possibility that a ready for sale unit, consisting of a mixing vessel and a mixing element, can be formed, in which case when using the mixing vessel, the drive shaft 20, possibly through a lid of the mixing vessel through and into the mixing vessel is introduced into and there is releasably coupled with the mixing element in a suitable manner. After completion of the mixing process, the drive shaft can then be separated again from the mixing element, wherein the mixing element remains in the mixing vessel. This solution is particularly advantageous if the mix can be contaminated by the ingress of ambient air.

How out Fig. 1 it can be seen, the mixing element 10 according to the invention has a total of six spoke elements 40. In this case, two different configurations for the spoke elements 40 are provided, wherein the first group, consisting of three spoke elements 40 with the reference numeral 40A and the second group, also consisting of three spoke elements 40 is designated by the reference numeral 40B. The two groups 40A, 40B of the spoke elements 40 are alternately arranged in one of the two circumferential directions R1, R2 of the mixing element 10, ie, each spoke element 40 of the first group 40A is followed by a spoke element 40 of the second group 40B.

The spoke elements 40 each include a first end 40a and a second end 40b. With the first end 40 a, the spoke members 40 are integrally connected to the outer peripheral side of the hub 30 and also connected to the second end 40 b integrally with the inner peripheral side of the stirring member carrier 60. In addition, the spoke elements 40 are in the of the ring shape of the Rührteilträgers 60 spanned center plane arcuately curved like a circle, the curvatures of all spoke elements 40 are aligned the same. Relative to the circumferential direction R1 of the mixing element 10, the spoke elements 40 have a convex / concave curvature. The radius of curvature is the same at least within each group 40A, 40B of spoke elements 40. However, it may vary between groups 40A, 40B.

The two different groups 40A, 40B of spoke elements 40A, 40B differ in their cross-sectional shape. In the first group 40A of the spoke elements 40, the two spoke flanks 40c, 40d which are in the two circumferential directions R1, R2 of the mixing element 10 and which are stirring surfaces are formed differently so as to extend in two intersecting "planes". The spoke flank 40c, which faces in the circumferential direction R1, which corresponds to the main direction of rotation of the mixing element 10 extends obliquely in the spoke element 40 of the first group 40A from the top 12 to the bottom (not shown) of the mixing element 10. This will receive the spoke element 40 the spoke edge 40c a knife-like and concave edge 40e, which allows a good penetration of the mix in the mixing or mixing process with simultaneous formation of partial flows in the direction of the axis of rotation D of the hub 30 and the drive shaft 20. On the other hand, the spoke flank 40d of the spoke member 40 of the first group 40A oriented in the circumferential direction R2 is oriented substantially perpendicular to the top 12 and bottom of the mixing element 10, that is, this spoke flank 40d is substantially perpendicular to the circumferential directions R1, R2. If the mixing element 10 is set in rotation in the circumferential direction R2, the spoke flank 40d can be used, for example, for shattering suspended particles possibly contained in a mixture constituent.

The cross-sectional shape of the spoke elements 40 of the second group 40B is rectangular or square. In other words, the two stirring surfaces forming spoke flanks 40c, 40d are substantially parallel to one another. At this time, the cross-sectional area of the spoke member 40 of the second group 40B may be continuously changed from the outer peripheral surface of the hub 30 to the one Extend the inner peripheral surface of the Rührteilträgers 60. Furthermore, the width of the spoke elements 40 of the second group 40B, measured in one of the two circumferential directions R1, R2, is smaller than that of the first group 40A.

How out Fig. 1 can be seen, the width of the spoke elements 40, measured in the spanned by the annular shape of the Rührteilträgers 60 center plane of the Rührteilträgers 60, small compared to the plane defined by the inner periphery of the Rührteilträgers level. As a result, there is sufficient space between successive spoke elements 40 for a passage of the mixed material during the mixing process.

The stirring member carrier 60 essentially consists of a ring element 62 with a rectangular or square cross section. The Rührteilträger 60 is rotatably and axially fixed by the spoke elements 40 to the hub 30. On the outer circumferential side 66 of the ring element 62 there are a plurality of, in particular twelve, stirring teeth 80, which are integrally connected to the ring element 62. Considered in the plane spanned by the annular shape of the mixing element 10 level have the stirring teeth of the embodiment according to Fig. 1 an arcuate segment-like shape, wherein in the direction of the circumferential direction R1 facing edge 80a of a stirring tooth 80 is cut off, ie this Rührzahnflanke 80a extends radially to the ring member 62. This is similar to the spoke flanks 40d of the first group 40A and the two Speichichenflanken 40c , 40d reaches the second group 40B of the spoke elements 40, that they can also smash the floating particles possibly present in the mix. In addition, the radial edge 80a allows easy detachment of adhering to the inner peripheral wall of the mixing vessel components of the mix.

How out Fig. 1 is directly apparent, the average length of the Rührzähne 80, as viewed in the spanned by the annular shape of the Rührteilträgers 60 center plane of the Rührteilträgers 60, smaller than the distance of the successive Rührzähne 80. This allows the mix not only pass between the successive spoke elements 40 during stirring but also between the stirring teeth 80. This is particularly advantageous if the mixing element 10 is not only set in rotation, but is also reciprocated parallel to the axis of rotation D.

In the Fig. 3 to 7 Further embodiments of the mixing element 10 according to the invention are shown. These are similar to the mixing element 10 according to the Fig. 1 or designed so that only the differences are discussed below.

A first difference exists in the mixing element 10 according to the Fig. 3 in that the spoke elements 40, with respect to the circumferential direction R1 of the mixing element 10, are concave / convexly curved. Thus, the knife-like edge 40e of the first group 40A of the spoke elements 40 is convexly curved. In addition, the Rührzahnflanken 80a not in the circumferential direction R1 but in the circumferential direction R2.

The mixing element 10 according to the Fig. 4 corresponds essentially to the mixing element 10 according to the Fig. 1 however, one difference is that the ends of the spoke members 40 of the second group 40B facing towards the hub 30 are not attached to the hub 30 but are integrally connected near the hub 30 to the spoke flank 40c of the spoke members 40 of the first group 40A ,

That in the Fig. 5 shown mixing element 10 substantially corresponds to the mixing element 10 according to the Fig. 4 however, there is a difference that the blade-like edge 40e of the first group 40A of the spoke members 40 is convexly curved. In addition, the Rührzahnflanken 80a not in the circumferential direction R1 but in the circumferential direction R2.

The mixing element 10 of Fig. 6 corresponds essentially to the mixing element 10 of Fig. 4 , In contrast to the mixing element 10 of Fig. 4 However, the mixing element 10 is the Fig. 6 made filigree, ie the Speichenlemente 40 and the ring shape of the Rührteilträgers 60 are thinner or finer articulated. Another difference of the mixing element 10 of Fig. 6 is that the Stirring teeth 80 are designed in the form of a trapezoid, viewed in the plane spanned by the annular shape of the mixing element 10 level.

Fig. 7 shows a mixing element 10, which substantially the mixing element 10 of Fig. 6 equivalent. A difference, however, is that the knife-like edge 40e of the first group 40A of the spoke elements 40 convexly curved.

Depending on the embodiment of the mixer, it is also possible that the mixing element 10 in addition to the rotational or rotational movement also undergoes a stroke movement. For this purpose, the drive shaft 20, at one end face of which the mixing element 10 is coupled in a rotationally and axially fixed manner, is reciprocated at different intervals in a direction parallel to the axis of rotation D of the hub 30. The lifting movements are in this case set so that the mixing element 10 in a well-defined area within the in Fig. 2 shown stirring or mixing vessel (Kruke K) is moved up and down. By the lifting movement of the mixing element 10, the mixing of the mixed substance is further improved.

LIST OF REFERENCE NUMBERS

10

mixing element

12

Top of the mixing element

20

drive shaft

30

hub

40

spoke members

40a

first end of the spoke elements

40b

End of the spoke elements

40c

Stirring surface of the spoke elements

40d

Stirring surface of the spoke elements

40e

knife-like running edge

40A

first group of spoke elements

40B

second group of spoke elements

60

Rührteilträger

62

ring element

66

Outer peripheral side

80

Rührzähne

80a

Flank of the stirring teeth

R1

circumferentially

R2

circumferentially

D

axis of rotation

Claims (14)

1. A mixing element (10) for mixing medical, pharmaceutical or cosmetic products, said mixing element (10) including:

   - a hub (30) for preferably reversible, non-rotating and axially stationary coupling with a drive shaft (20) of a mixing machine,

   - an annular stirring portion carrier arranged at least approximately concentrically around said hub (30), and

   - at least one spoke element (40) for connecting the stirring portion carrier (60) in a non-rotating and axially stationary manner to the hub (30),
   wherein at least two stirring teeth (80) are provided on the outer circumferential side (66) of the stirring portion carrier (60), and wherein the average circumferential length of at least one stirring tooth (80), when viewed in the centre plane of the stirring portion carrier (60) formed by the annular shape of the stirring portion carrier (60), is equal at most to the distance between two successive stirring teeth (80) in relation to each other in the circumferential direction (R1, R2) of the stirring portion carrier (60),
   characterised in that the at least one spoke element (40) extends, in the centre plane of the stirring portion carrier (60) formed by the annular shape of the stirring portion carrier (60), at least partly in an arc segment from the hub (30) to the inner circumferential surface of the stirring portion carrier (60).
2. The mixing element according to claim 1,
   characterised in that more than two stirring teeth (80) are disposed on the outer circumferential side of the stirring portion carrier (60).
3. The mixing element according to claim 1 or 2,
   characterised in that the shape of the at least one stirring tooth (80), when viewed in the centre plane of the stirring portion carrier (60) formed by the annular shape of the stirring portion carrier (60), is at least approximately that of a trapezium.
4. The mixing element according to at least one of claims 1 to 3, characterised in that the shape of the at least one stirring tooth (80), when viewed in the centre plane of the stirring portion carrier (60) formed by the annular shape of the stirring portion carrier (60), is at least approximately that of an arc segment.
5. The mixing element according to at least one of claims 1 to 4, characterised in that at least one of the shoulders (80a) of a stirring tooth (80), facing in one of the circumferential directions (R1, R2) of the stirring portion carrier (60), extends at least approximately radially in relation to the hub (30).
6. The mixing element according to at least one of claims 1 to 5, characterised in that the stirring teeth (80) are identical in shape.
7. The mixing element according to at least one of claims 1 to 5, characterised in that the stirring teeth (80) are different in shape.
8. The mixing element according to at least one of claims 1 to 7, characterised in that the outer surfaces of at least the stirring portion carrier (60) and the stirring teeth (80), arranged facing in the direction of the rotational axis (D) of the hub (30), are arranged in two planes extending at least approximately parallel to one other and at least approximately perpendicularly to the rotational axis of the hub (30).
9. The mixing element according to at least one of claims 1 to 8, characterised in that the at least one spoke element (40) has a first stirring surface (40c) facing in the first circumferential direction (R1) of the stirring portion carrier (60) and a second stirring surface (40d) facing in the second circumferential direction (R2) of the stirring portion carrier (60), wherein the two stirring surfaces (40c, 40d) of the spoke element (40) extend at least approximately parallel to each other.
10. The mixing element according to at least one of claims 1 to 9, characterised in that the at least one spoke element (40) has a first stirring surface (40c) facing in the first circumferential direction (R1) of the stirring portion carrier (60) and a second stirring surface (40d) facing in the second circumferential direction (R2) of the stirring portion carrier (60), wherein the two stirring surfaces (40c, 40d) are arranged in two intersecting planes.
11. The mixing element according to claim 9 or 10,
    characterised in that at least one stirring surface (40d) of the at least one spoke element (40) extends at least approximately perpendicularly to one of the two circumferential directions (R1, R2) of the stirring portion carrier (60).
12. The mixing element according to at least one of claims 1 to 11, characterised in that a plurality of spoke elements (40) are provided.
13. The mixing element according to claim 12,
    characterised in that the spoke elements (40) are identical in shape.
14. The mixing element according to claim 13,
    characterised in that the spoke elements (40) are different in shape.

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