Continuous flow centrifuge and balancing rotor guiding device

Abstract

The invention relates to a flow centrifuge with a rotor that has at least one centrifugation chamber and is rotated about a rotor axis (7) at a rotor speed. The flow centrifuge has a connecting section (12) through which connecting lines (16, 17) extend. During operation of the flow centrifuge with a rotating rotor, a medium can be supplied to and discharged from the centrifugation chamber via the connecting lines (16, 17). One end section (18) of the connecting section (12) is fixed to the housing, while the other end section (19) of the connecting section (12) rotates with the rotor. To prevent twisting of the connecting section (12), it is guided in a compensating rotor guide device (20) (in particular a guide tube (21)), which is rotated about the rotor axis (7) at half the rotor speed.According to the invention, the compensating rotor guide device (20) has a guide contour (27) whose radius of curvature (32) in a first guide contour section (28) is larger than the radius of curvature (33) in a second guide contour section (29). This increases the service life of the connecting string (12).

Description

[0001] The invention relates to a flow-through centrifuge in which at least one medium (in particular a fluid, a liquid, a suspension, etc.) is at least temporarily supplied to a centrifugation chamber and / or a medium is removed from the centrifugation chamber while the centrifugation chamber rotates. The medium can be arranged in a container in the centrifugation chamber. The at least one medium is, in particular, the medium to be centrifuged, a rinsing liquid, a washing or buffer solution, a modified medium extracted from the centrifuged medium, and / or a sediment in the centrifugation chamber.

[0002] To name just a few non-limiting examples, the flow-through centrifuge may be a blood centrifuge, where the medium to be centrifuged is blood and the extracted modified medium or sediment is blood bodies or particles, or a flow-through centrifuge intended to extract cells, microcarriers, or other particles contained in the medium from a medium. It is also possible that the centrifuged medium is not a pure liquid, but rather a solution or suspension containing particles such as cells, cell debris, or parts of cells, etc.

[0003] The flow-through centrifuge is used, for example, for the production of biopharmaceutical products in biopharmaceutical companies or in bioprocessing applications. The flow-through centrifuge can be used, for example, to extract and / or purify cells or microcarriers, whereby the cells obtained in this way can also be used for cell therapy. Another application of the flow-through centrifuge is, for example, the production of vaccines.

[0004] The invention also relates to a compensating rotor guide device. STATE OF THE ART

[0005] Generic flow centrifuges are marketed, for example, by Sartorius AG, Otto-Brenner-Straße 20, 37079 Göttingen, Germany, and affiliated companies under the brand name "Ksep" (registered trademark). On the website dedicated to these flow centrifuges, www.sartorius.com / en / products / process-filtration / cell-harvesting / ksep-systems (date of access: July 6, 2022), the functional principle of a flow centrifuge, such as can be used for the present invention, is described as follows based on a linked video: A rotor of the flow centrifuge has any number (e.g., two or four) of centrifugation chambers, which can be designed as blood bags held on a rotor body and are evenly distributed around the circumference. The centrifugation chambers are arranged at equal radial distances from the rotor's rotational axis.A first connecting line opens radially inward into a centrifugation chamber, while a second connecting line opens radially outward into the centrifugation chamber. In a first operating phase, a first medium, for example blood, is fed to the centrifugation chamber via the second connecting line, while the centrifugation chamber rotates with the rotor. As a result of the centrifugation, particles contained in the blood (e.g. blood cells) are deposited radially outward in the centrifugation chamber, while the remaining medium (i.e. the medium fed in radially outward less the particles pushed radially outward) is discharged radially inward from the centrifugation chamber via the first connecting line. In this first operating phase, the first connecting line is therefore a discharge line, while the second connecting line is a supply line.As this operation continues, the proportion of particles and their concentration in the centrifugation chamber increases until it is largely and finally completely filled with particles. In a subsequent optional second operating phase, the particles in the centrifugation chamber are washed. For this purpose, a washing or buffer solution is fed into the centrifugation chamber via the second connecting line. The washing or buffer solution rinses the centrifugation chamber and is discharged radially inward via the first connecting line. During this operating phase, the centrifugation chamber rotates with the rotor so that the centrifugation force prevents the particles from escaping from the centrifugation chamber with the washing or buffer solution via the first connecting line.During the second operating phase, the first connecting line also serves as the discharge line for the washing or buffer solution, while the first connecting line serves as the supply line for the washing or buffer solution. In a subsequent third operating phase, the centrifugation chamber continues to rotate with the rotor. In the third operating phase, the flow direction through the centrifugation chamber is reversed and the particles are removed from the centrifugation chamber via the second connecting line, while washing or buffer solution can be added to the centrifugation chamber via the first connecting line. The third operating phase ends when all particles have been removed from the centrifugation chamber. This can be followed by successive cycles with the three operating phases described.

[0006] EP 3 936 601 A1 describes the design of a medium network, which is connected to the connecting lines and ensures the various operating phases. Regarding this medium network, the included pump arrangement, the process control unit, an additional filter arrangement, storage containers for the various media, and the process sequence, reference is made to EP 3 936 601 A1, EP 2 310 486 B1, and EP 2 485 846 B1.

[0007] EP 2 485 846 B1 describes that, in flow-through centrifuges, fluidic connections to connecting lines rotating with the rotor using rotary unions can be problematic, as the rotary unions are prone to leaks and pose the risk of undesirable contamination of the media. On the other hand, it is explained that, according to US 4,216,770, US 4,419,089, US 4,389,206, and US 5,665,048, connecting lines are used, into which the connecting lines can be integrated. One end of the connecting line is fixed to the housing, while the other end of the connecting line is attached to the rotor and rotates with the rotor.To prevent the connecting strand from becoming increasingly twisted due to the rotation of the rotor and the relative rotation of the end regions of the connecting strand, the connecting strand is additionally guided in a compensating rotor guide device designed as a guide tube. The guide tube has a section in the shape of a rounded U with slightly spread-out side legs of different lengths. The opening of the U points in the direction of the rotor's axis of rotation. Starting from the end region fixed to the housing, the connecting strand enters one side leg of the U, curving outwards. In the U-shaped section, the connecting strand is guided around the rotor by the guide tube.The free end region of the other side leg of the U-shaped guide tube is curved back so that it is arranged coaxially to the rotor's rotational axis and immediately adjacent to the entry of the connecting strand into the rotor. The guide tube is then driven at half the rotor's speed. EP 2 485 846 B1 refers to US Pat. No. 3,586,413 for an explanation of how the rotating guide tube prevents increasing twisting of the connecting strand.

[0008] Further prior art is known from EP 1 295 642 A1. OBJECT OF THE INVENTION

[0009] The invention is based on the object of proposing a flow centrifuge and a compensating rotor guide device for a flow centrifuge which is improved with regard to stresses and fatigue strength. SOLUTION

[0010] The object of the invention is achieved according to the invention with the features of the independent patent claims. Further preferred embodiments of the invention can be found in the dependent patent claims. DESCRIPTION OF THE INVENTION

[0011] The invention relates to a flow-through centrifuge. The flow-through centrifuge has a rotor that has (at least) one centrifugation chamber. The medium to be centrifuged can be placed in the centrifugation chamber directly or in a suitable container, and this chamber can be flushed with additional media such as a washing or buffer solution. In the flow-through centrifuge, the rotor is rotated about the rotor axis at a rotor speed. The flow-through centrifuge has a connecting line. The connecting line has a connecting line through which a medium can be fed to the centrifugation chamber (in particular to a container arranged in the centrifugation chamber) during operation of the flow-through centrifuge with a rotating rotor. Furthermore, the connecting line has a connecting line through which a medium can be discharged from the centrifugation chamber (in particular to a container arranged in the centrifugation chamber).Depending on the current operating phase, the flow directions through the connecting lines can be reversed. One end of the connecting line is fixed to the housing, while the other end of the connecting line is rotated with the rotor. To prevent twisting of the connecting line, the connecting line is rotated with a compensating rotor, whereby the connecting line is guided in a compensating rotor guide device of the compensating rotor, in particular a guide tube. The compensating rotor and the compensating rotor guide device are rotated around the rotor axis at half the rotor speed. In this respect, the flow-through centrifuge can, for example, be designed like the flow-through centrifuges of the prior art mentioned above.

[0012] In conventional flow-through centrifuges, the connecting line consists of a flexible tube or hose (preferably a corrugated tube) through which the connecting lines extend. The cost of such a connecting line, including the connecting lines and the interfaces to the rotor on the one hand and the medium network on the other, may be in the range of €5,000 to €15,000. Due to the high stresses on the connecting line during operation of the flow-through centrifuge, replacement of the connecting line may be necessary after just 5 to 20 hours of operation, which leads to long changeover times and downtime for the flow-through centrifuge, as well as considerable costs.Since it is generally not possible to extend the service life of the connecting string by reducing the speed of the rotor or by increasing the dimensioning of the connecting string and / or by choosing high-strength materials for the connecting string, such short service lives of the connecting string are accepted according to the state of the art.

[0013] The invention is based on an investigation of the stresses acting on the connecting rod during operation of the flow-through centrifuge. The investigations underlying the invention have led to the conclusion that the connecting rod in the flow-through centrifuge is subject to complex stresses: a) The connecting strand performs a relative rotational movement around the longitudinal axis in the compensating rotor guide device. This relative rotational movement leads to friction between the connecting strand and the compensating rotor guide device. This friction results in torsional stress on the connecting strand that varies along the longitudinal extent of the connecting strand. Furthermore, the friction between the connecting strand and the inner wall of the compensating rotor guide device leads to heat input into the connecting strand in the area of ​​the contact and friction surfaces and, under certain circumstances, to wear. b) The connecting strand is guided in the compensating rotor guide device such that the connecting strand, following a first guide contour section of the compensating rotor guide device, is curved outwards from the end region fixed to the housing and the coaxial arrangement there to the rotor axis.From a turning point, the connecting strand is then curved in the opposite direction in a second guide contour section of the compensating rotor guide device until the connecting strand can be guided radially outward past the rotor with a section oriented parallel to the rotor axis. The connecting strand is thus guided in the aforementioned guide contour sections according to an elongated S, with the two ends of the S being oriented parallel to one another and one end being arranged coaxially to the rotor axis, while the other end is at the maximum distance of the connecting strand from the rotor axis. The connecting strand is curved in the compensating rotor guide device according to the guide contours of the aforementioned guide contour sections and is thus subjected to a bend from its elongated starting position.Due to the mechanical boundary conditions of the connecting strand, namely the attachment of one end region of the connecting strand to the stationary housing, the attachment of the other end region of the connecting strand to the rotor, which rotates at the rotor speed, and the guidance of the connecting strand in the compensating rotor guide device, which is rotated at half the rotor speed, the bending of the connecting strand is not stationary, but represents a circumferential bending. Away from an (imaginary) neutral fiber, a temporarily radially outer material region of the connecting strand, in particular of the flexible hose or the flexible (corrugated) pipe, is exposed to an alternating stress with a harmonic progression, i.e. alternating tensile and compressive stress, as a result of the circumferential bending.c) If the connecting strand has a corrugated pipe, the circumferential bend of the corrugated pipe can lead to corrugations or ribs of the corrugated pipe coming into contact with one another on the radially inner side of the curved guide contour, which can lead to a non-linearity in the stiffness of the corrugated pipe, which can result in a changed stress mechanism of the corrugated pipe. d) The considerations underlying the invention have led to the result that a centrifugal force acts on longitudinal sections of the connecting strand (in particular the hose or the (corrugated) pipe and the lines arranged therein and also on the medium arranged in the lines), the magnitude of which depends on the distance of the respective longitudinal section from the rotor axis.The centrifugal force acting on the respective longitudinal section has a first component that acts in the direction of the guide surface of the compensating rotor guide device and thus increases the contact pressure and friction between the connecting strand and the compensating rotor guide device, and a second component that is oriented in the longitudinal direction of the connecting strand and leads to a tensile or compressive force in the longitudinal direction of the connecting strand. The distribution of the centrifugal force between the two components results from the trigonometric functions depending on the angle at which the longitudinal section is inclined relative to the rotor axis. In the first guide contour section, the second component leads to a tensile force that causes the connecting strand to stretch, while in the second guide contour section this leads to a compressive force that compresses the connecting strand.In this case, a tensile force due to the centrifugal force in a first material region of the connecting strand at a first longitudinal extension coordinate of the connecting strand, which is a short distance from the rotor axis, may be greater than the tensile force due to the centrifugal force in a second material region of the connecting strand at a second longitudinal extension coordinate of the connecting strand, which is a greater distance from the rotor axis. The reason for this is that a longer section of the connecting strand is arranged radially outward from the first material region of the connecting strand at the first longitudinal extension coordinate of the connecting strand, which can lead to a greater tensile force due to the centrifugal force. e) Depending on the acting stresses, changed boundary conditions in the connecting strand can occur.For example, an expansion of a connecting line in the hose or (corrugated) pipe can result in the connecting line no longer being in contact with the inner surface of the hose or (corrugated) pipe, which means that the hose or (corrugated) pipe is no longer supported internally and the internal friction of the connecting line changes. It is also possible that this can change the longitudinal and / or flexural rigidity of the connecting line. f) Any elasticity of the medium in the lines of the connecting line can also be important, since the centrifugal force due to the elasticity can lead to pressure changes inside the connecting lines, to an associated change in mass distribution and / or to a change in rigidity.

[0014] Against the background of these considerations, the investigation of the stresses on the connecting strand explained above and the tests on which the invention is based, the invention proposes that a compensating rotor guide device is used in a flow centrifuge which has a guide contour whose radius of curvature is greater for a first distance from the rotor axis than for a second distance from the rotor axis, wherein the first distance is smaller than the second distance.

[0015] This will be explained using a simplified example which does not limit the invention, in which the guide contour is designed according to an S which is elongated in the horizontal direction and has a lower left end region which is oriented coaxially to the rotor axis and an upper right end region which is oriented parallel to the rotor axis. Between these end regions there is a turning point in the middle, in the region of which the curvature changes sign in a mathematical sense. For this simplified example, in the first guide contour section between the lower left end region and the turning point the radius of curvature is constant corresponding to a first radius of curvature, while in the second guide contour section between the turning point and the upper right end region the radius of curvature is constant with a second radius of curvature, wherein the second radius of curvature is smaller than the first radius of curvature.

[0016] In the first guide contour section, the cross-sections at the respective longitudinal extension coordinates are subjected to a circumferential bending stress as a result of the circumferential bending. This circumferential bending stress can be constant in magnitude over the longitudinal extension in the first guide contour section, but changes sign with a harmonic curve according to the revolution. Superimposed on this circumferential bending stress is the tensile stress that results from the mass of the connecting strand as a result of the centrifugal force corresponding to the distance from the rotor axis and that is quadratically dependent on the speed. At the first end of the first guide contour section, where the bending begins, starting from the coaxial alignment to the rotor axis, the centrifugal force acts, which is generated by the entire sub-section of the connecting strand in the first guide contour section and possibly also a sub-section in the second guide contour section.For longitudinal coordinates in the first guide contour section with a greater distance from the rotor axis, the tensile force acting in the cross-section at the longitudinal coordinate due to the centrifugal force decreases, so that at the first end, the tensile force due to the centrifugal force and the resulting tensile stress are at a maximum. In the cross-sections at the respective longitudinal coordinates, the circumferential bending stress and the tensile stress due to the centrifugal force then superimpose themselves. If the circumferential bending temporarily leads to circumferential bending compressive stress, the superposition of the tensile stress due to the centrifugal force reduces the resulting stress, which is beneficial for the material stress.However, a short time later, the same cross-sectional area is also subjected to a circumferential bending tensile stress for the further circumferential bending. The superposition of the tensile stress due to the centrifugal force then results in the addition of the values ​​of the circumferential bending tensile stress and the tensile stress due to the centrifugal force. This results in an increased maximum of the resulting stress, which may be responsible for a possible explanation for the limitation of the service life of the connecting strand.

[0017] The inventive design allows the maximum resulting stress to be reduced, thereby (potentially significantly) increasing the service life: According to the invention, the radius of curvature is selected to be larger in the area of ​​the rotor axis or adjacent to it. By increasing the radius of curvature, the amplitude of the rotating bending stress is reduced, which can then lead to a reduction in the maximum resulting stress and thus to a reduction in the stress, despite the explained superposition of the tensile stress due to the centrifugal force.

[0018] According to the invention, the guide contour has a first guide contour section and a second guide contour section. For the aforementioned example, the guide contour sections can each be quarter-circular in shape with curvatures in opposite directions, wherein the guide contour sections then have different radii. However, it is also entirely possible for at least one guide contour section to contain guide contour sections with different radii of curvature, wherein the radius of curvature can vary in steps or continuously. For this proposal of the invention, the guide contour section has a curvature in a first direction, while the second guide contour section has a curvature in a second direction. The first guide contour section and the second guide contour section are connected to one another by an intermediate section that is preferably oriented radially to the rotor axis.For the example explained above with the quarter-circle-shaped guide contour sections, the intermediate section can be formed by the local connection point of the mutually facing ends of the guide contour sections, whereby it is also possible for a rectilinear, preferably radially oriented intermediate section to extend between these ends. Alternatively or cumulatively, it is possible for the first guide contour section and the second guide contour section to be connected to one another via a turning section in which the curvature changes sign. The first guide contour section is at a smaller distance from the rotor axis than the second guide contour section. In the first guide contour section, the radius of curvature is larger than the radius of curvature in the second guide contour section.To name just a few non-limiting examples, the radius of curvature in the first guide contour section can be at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, or even at least 50% greater than the radius of curvature in the second guide contour section. This can be, for example,... apply only to a discrete radius of curvature at a specific longitudinal extension coordinate of the guide contour sections, apply to a partial section of the guide contour sections in which the radius of curvature is constant, apply to averaged radii of curvature in the guide contour sections or apply to all radii of curvature with a continuously changing radius of curvature in the guide contour sections.

[0019] Alternatively or cumulatively, it is possible for the radius of curvature in the first guide contour section to become smaller continuously or in steps in the direction of the longitudinal extension and with increasing distance from the rotor axis.

[0020] In principle, the connecting line can be constructed in any way within the scope of the invention. Preferably, the connecting line comprises a corrugated pipe through which the various cables, in particular connecting cables, of the connecting line can extend. The corrugated pipe serves, for example, to bundle the cables, protect them, and guide and encapsulate them.

[0021] In a particular embodiment of the invention, the radius of curvature in the first guide contour section continuously decreases with increasing distance from the rotor axis. It is possible that this applies only to the first guide contour section. Preferably, the radius of curvature in the second guide contour section also continuously decreases with increasing distance from the rotor axis.

[0022] As previously explained, the stresses on the connecting string in the guide device are quite complex, which can also make the requirements for the design of the geometry of the guide contour sections complex. For a design of the flow-through centrifuge, a radius of curvature is dimensioned at the various longitudinal coordinates in the first guide contour section and / or in the second guide contour section such that the stress on the connecting string guided in the compensating rotor guide device is constant at these or all longitudinal coordinates or only varies by a maximum of ± 20%, a maximum of ± 15%, a maximum of ± 10%, or a maximum of ± 5%. The stress, which should remain constant or only vary by the specified percentage, is determined by superimposing two different partial stresses: a tensile stress on the connecting strand at the longitudinal extension coordinates, resulting from the centrifugal force due to the section of the connecting strand that is arranged radially outward from the longitudinal extension coordinate; a circumferential bending stress on the connecting strand at the longitudinal extension coordinates, resulting from the circumferential bending of the connecting strand according to its curvature.

[0023] This design is based on the assumption that the two partial stresses mentioned are decisive for the strength of the connecting strand, whereby the specified percentage variation ranges can be used to take safety into account on the one hand and to take into account other stresses that may occur (friction, heating, wear, etc.) on the other.

[0024] For an alternative or cumulative design criterion, the radius of curvature is dimensioned such that the stress resulting from the aforementioned two partial stresses along the longitudinal extent of the connecting strand in the first guide contour section and / or in the second guide contour section is at least a predetermined percentage lower than the permissible stress on the connecting strand. For example, for the use of a corrugated pipe in the connecting strand, a maximum static bending stress may be specified by the manufacturer, so that in this case, the resulting stress determined from the two partial stresses is a fixed percentage lower than the bending stress specified by the manufacturer.A further permissible stress, to which the stress determined with the partial stresses is related in percentage terms, can be a maximum dynamic tensile and / or bending stress or a specified tensile strength or fatigue strength of a component of the connecting strand or of the entire connecting strand.

[0025] A further solution to the problem underlying the invention is a compensating rotor guide device intended for a flow centrifuge as previously explained. The compensating rotor guide device has a guide tube or consists of a guide tube, wherein the guide tube has a guide contour with a first guide contour section and a second guide contour section. The first guide contour section has a curvature in a first direction, while the second guide contour section has a curvature in a second direction oriented opposite to the first direction. The first guide contour section and the second guide contour section are connected to one another by an intermediate section, preferably oriented radially to the rotor axis, or a turning section.The first guide contour section is spaced a shorter distance from the rotor axis than the second guide contour section. The radius of curvature in the first guide contour section is larger than the radius of curvature in the second guide contour section. It is possible for the radius of curvature in the first guide contour section in the guide tube to decrease toward the end region facing the second guide contour section, which can occur in stages or continuously.

[0026] Advantageous further developments of the invention emerge from the patent claims, the description and the drawings.

[0027] The advantages of features and combinations of several features mentioned in the description are merely exemplary and can be effective alternatively or cumulatively, without the advantages necessarily having to be achieved by embodiments according to the invention.

[0028] With regard to the disclosure content – ​​not the scope of protection – of the original application documents and the patent, the following applies: Further features can be found in the drawings – in particular the illustrated geometries and the relative dimensions of several components to one another, as well as their relative arrangement and operative connection. The combination of features of different embodiments of the invention or features of different patent claims is also possible, deviating from the chosen references of the patent claims, and is hereby encouraged. This also applies to features that are illustrated in separate drawings or mentioned in their description. These features can also be combined with features of different patent claims.Likewise, features listed in the patent claims may be omitted for further embodiments of the invention, but this does not apply to the independent patent claims of the granted patent.

[0029] The number of features mentioned in the claims and the description is to be understood as meaning that exactly this number or a greater number than the stated number is present, without the need for the explicit use of the adverb "at least." Thus, for example, if reference is made to one element, this is to be understood as meaning that exactly one element, two elements, or more elements are present. The features mentioned in the claims may be supplemented by further features or may be the only features present in the subject matter of the respective claim.

[0030] The reference signs contained in the patent claims do not represent a limitation of the scope of the subject-matter protected by the patent claims. They serve solely to make the patent claims easier to understand. BRIEF DESCRIPTION OF THE CHARACTERS

[0031] In the following, the invention is further explained and described with reference to preferred embodiments shown in the figures. Fig. 1 shows a highly schematic, spatial half-longitudinal section of a flow-through centrifuge with a connecting line (without representation of the guide device). Fig. 2 shows a connecting line in a guide device, as these can be used in a flow centrifuge according to Fig. 1 . Fig. 3 to 5 show tables for the dimensioning of the radii of curvature of a guide tube of a compensating rotor guide device. Fig. 6shows an exemplary curve of a radius of curvature of a guide tube of a compensating rotor guide device as well as a tensile force resulting from the centrifugal force as a function of the distance from a rotor axis. Fig. 7 shows a schematic representation for an auxiliary consideration for determining a tensile force acting on a pipe or hose of the connecting string at a longitudinal section at a longitudinal extension coordinate and at a distance from a rotor axis as a result of a centrifugal force. FIGURE DESCRIPTION

[0032] In the figures, components or features that correspond or are similar are sometimes identified by the same reference numerals, whereby these components or features can then be distinguished from one another by the additional letters a, b, .... In this case, reference can be made to these components or features with or without the additional letters, which can then refer to one of the components or features, several of them, or all of them.

[0033] Fig. 1 shows a highly schematic representation of a flow-through centrifuge 1 in a spatial representation in a semi-longitudinal section. The flow-through centrifuge 1 has a housing 2 and in particular a bowl 3 with a wall 4. The wall 4 of the bowl 3 defines a rotor chamber 5 in which a rotor 6 is rotated at a rotor speed about a rotor axis 7. In the schematic representation according to Fig. 1Only containers 8a, 8b (here two containers 8a, 8b, although any other number of containers 8 may be present) are shown arranged in the centrifugation chamber of the rotor 6. These containers may, for example, be blood bags 9 or any other containers. The containers 8 are evenly distributed in the circumferential direction around the rotor axis 7 and are at the same distance from the rotor axis 7.

[0034] The flow centrifuge 1 has a rotor chamber temperature control circuit 10, of which Fig. 1 Only one rotor chamber temperature control loop 11 is shown. The rotor chamber temperature control loop 11 is integrated into the wall 4 of the vessel 3 and winds several times around the rotor axis 7 and the rotor chamber 5.

[0035] In Fig. 1Furthermore, a connecting strand 12 can be seen. The connecting strand 12 has a flexible hose or a flexible pipe 13, which is in particular a corrugated pipe. Optionally, a temperature control supply line 14 and a temperature control discharge line 15 extend through the hose or pipe 13, which can be used to temperature control and cool the connecting strand. Two connecting lines 16, 17 extend through the hose or pipe 13, through which the media flows in different directions during the different operating phases of the centrifugation process. In one end region 18, the connecting strand 12 is fastened to the housing 2 or a wall 4 of the vessel 3, while in another end region 19 the connecting strand 12 is fastened to the rotor 6 and is rotated with it.

[0036] A compensating rotor also rotates around the rotor axis 7, the speed of the compensating rotor being half the speed of the rotor 6. The compensating rotor has a compensating rotor guide device 20, which is Fig. 2is shown and is designed here as a guide tube 21. The guide tube 21 has two guide tube halves 22, 23, which are separated from one another by the dash-dotted imaginary dividing line 24. The guide tube 21 has a constant circular cross-section along a longitudinal extension coordinate 25, wherein the longitudinal extension coordinate 25 is curved in different directions, as will be explained in more detail below. The connecting strand 12, which is designed here as a corrugated tube, extends through the guide tube 21. In both end regions of the guide tube 21, the connecting strand 12 extends out of the guide tube 21 in order to enable its attachment to the housing 2 or the rotor 6.A radial play results between an inner surface 26 of the guide tube 21 and the outer surface of the connecting strand 12, whereby depending on the curvature of the connecting strand 12 and the previously explained stresses on the same, the connecting strand 12 can rest on one side against the inner surface 26 of the guide tube 21.

[0037] In the guide tube half 22, the guide tube 21 has a guide contour 27, which is formed by the inner surface 26. The guide contour 27 has a first guide contour section 28 and a second guide contour section 29, which are directly connected to one another via a turning section 30. For this exemplary embodiment, the turning section 30 simultaneously forms an intermediate section 31, in the region of which the guide tube 21 is oriented radially to the rotor axis 7. In the first guide contour section 28, the guide contour 27, in particular the longitudinal extension coordinate 25 of the guide tube 21, has a first radius of curvature 32, while the guide contour 27 in the second guide contour section 29 has a second radius of curvature 33. For the exemplary embodiment in Fig. 2the first radius of curvature 32 in the first guide section 28 is constant and the second radius of curvature 33 in the second guide section 29 is also constant, wherein the second radius of curvature 33 is smaller than the first radius of curvature 32. In the first guide contour section 28, the curvature of the longitudinal extension coordinate 25 occurs counterclockwise, while this is reversed in the turning section 30, so that in the second guide contour section 29 the curvature of the longitudinal extension coordinate 25 runs clockwise. The guide contour sections 28, 29 each extend over a circumferential angle of 90°. However, smaller circumferential angles are also possible, whereby the guide tube 21 is then not oriented radially to the rotor axis 7 in the turning section 30.

[0038] As in Fig. 2As can be seen, one end region 34 of the first guide contour section 28 is oriented (approximately) coaxially to the rotor axis 7, while the other end region 35 of the first guide contour section 28 is oriented radially to the rotor axis 7. The facing end region 36 of the second guide contour section 29, which is also oriented radially to the rotor axis 7, adjoins the end region 35 in the turning section 30 and intermediate section 31. In contrast, the other end region 37 of the second guide contour section 29 is oriented parallel to the rotor axis 7, wherein in this region the guide tube 21 has the maximum distance from the rotor axis 7. In principle, the second guide tube half 23 can be designed to be mirror-symmetrical to the dividing line 24 of the first guide tube half 22.For the illustrated embodiment, this mirror symmetry applies only to the second guide contour section 29', while the first guide contour section 28' in the second guide tube half 23 is attached to the second guide contour half 29' without mirroring, so that in the direction of the longitudinal extension coordinate 25 both guide contour sections 28', 29' are curved in a clockwise direction and together form a half ring with a radius of curvature 32' that increases in the area of ​​the turning section 30' and intermediate section 31' in the direction of the longitudinal extension coordinate 25.

[0039] For the embodiment according to Fig. 2The guide tube 21 can thus consist of two composite guide contour parts, which are identical and each form the guide contour sections 29, 29', as well as two guide tube parts that form the guide contour sections 28, 28', which can potentially increase the component required for the manufacture of the guide tube 21. It is understood, however, that the guide tube 21 can also be manufactured from a single piece, depending on the manufacturing process used.

[0040] The Fig. 2 The guide contour sections 28, 29 shown are shown and explained merely as examples, without the invention being limited thereby.

[0041] For a first proposal, deviating from Fig. 2 The radius of curvature 32 in the guide contour section 28 is not constant. Rather, it decreases in steps or continuously along the longitudinal extension coordinate 25.

[0042] It is also possible that the radius of curvature 32 initially decreases continuously (for example only adjacent to the end 34), while it then remains constant in the guide contour section 28 or decreases further in steps.

[0043] For all embodiments, a constant radius of curvature 33, a radius of curvature 33 that decreases in steps, or a radius of curvature 33 that decreases continuously in one sub-section and is constant or changes in steps in another sub-section can then be used in the second guide contour section 29.

[0044] In the following, an exemplary possibility for determining a course of the radius of curvature 32, 33 of the guide tube 21 of the compensating rotor guide device 20 is explained, whereby a simplified calculation with simplifying assumptions is explained here and no restriction of the invention to the radii of curvature determined in this way is intended. For the following exemplary calculation, the assumption is made that the hose or the (corrugated) pipe 13 follows the course of the guide contour 27 of the guide tube 21. As in Fig. 2 As can be seen, this is actually not the case, so that for a calculation with increased accuracy, the course of the hose or (corrugated) pipe 13 in the guide pipe 21 must be determined and then the radii of curvature for this course must be calculated accordingly.

[0045] The exemplary calculation is based on a hose or (corrugated) pipe 13 with a diameter D of 0.013 m and a spring constant of c = 5,000 [tensile force in N / elongation] when subjected to a longitudinal tensile force. This spring constant c can be specified by the manufacturer or determined through a simple tensile test.

[0046] In the table in Fig. 3 For different tensile forces F Tension acting on the hose or the (corrugated) pipe 13 in the range from 0 N to 330 N, the elongation D Tensile force of the hose or (corrugated) pipe 13 resulting from the spring constant c D Zugkraft = F Zug / c calculated (see first and second columns).

[0047] If the hose or pipe is bent with a radius of curvature R, the material area on the outside of the bend is subjected to expansion, while the material area on the inside is compressed. The expansion D bending due to the bend in the radially outer area can be determined using D Biegung = 0 , 5 D / R + 0 , 5 D .

[0048] In the table in Fig. 3 In the fourth line, the strain D bending resulting from this bending is given for the radii of curvature R specified in the second line in the range from 0.45 m to 0.175 m.

[0049] If, during operation, the strain due to bending D bending and the strain due to tensile force D tensile force are superimposed in the material area which is maximally stretched as a result of bending, the following values ​​are to be calculated in the table according to Fig. 3the strain due to the tensile force D tensile force on the one hand and the strain for pure bending D bending on the other hand are added, from which the specified resulting strains D resulting are obtained.

[0050] If the radius of curvature R is to be designed in such a way that the resulting strain D resulting from the superposition is always less than 12%, only those radii of curvature R are to be considered for which the values ​​given in the table according to Fig. 3 The resulting strains D resulting are highlighted in bold. This means that for a resulting strain D resulting less than 12% for tensile forces from 0 N to 60 N (i.e. with a longitudinal extension coordinate 25 far away from the rotor axis 7, in which the guide tube 21 is preferably oriented parallel to the rotor axis 7 and thus no centrifugal force acts) the radius of curvature R can be 0.055 m, for tensile forces from 90 N to 120 N the radius of curvature R can be 0.065 m, for a tensile force from 150 N to 180 N the radius of curvature R can be 0.075 m, for tensile forces from 210 N to 240 N the radius of curvature R can be 0.085 m, for a tensile force of 270 N the radius of curvature R can be 0.095 m, for a tensile force of 300 N the radius of curvature R can be 0.105 m, for a tensile force of 330 N (which results, for example, at a longitudinal extension coordinate 25 of the guide tube 21 in the guide contour section 8 in the end region 34) the radius of curvature R can be 0.115 m.

[0051] (A corresponding calculation can also be made with smaller steps of the tensile force or with a continuous change of the tensile force.) In the table according to Fig. 4 In the first column, a length along the longitudinal extension coordinate 25 of the guide tube 21 from the rotor axis 7 is specified in the range from 0 m to 0.21 m, which corresponds to the length up to the dividing line 24. In the second column, an angle 43 of a longitudinal section of the connecting strand 12 arranged at the longitudinal extension coordinate 25 is specified in radians with respect to an orientation radial to the rotor axis 7. At the longitudinal extension coordinate 0.00 m, i.e. at the entry into the guide tube 21, the angle 43 is π / 2, while the angle 43 at the turning section 30 is zero and at the end region 37 is - π / 2.

[0052] If the simplifying assumption is made that the two guide contour sections 28, 29 are curved in a quarter circle shape with the same radii of curvature R, the angle 43 can be calculated for the respective longitudinal extension coordinate 25 between these characteristic angles 43 via Winkel 43 = π / 2 − π / 2 × Längserstreckungskoordinate 25 / R , where a constant radius of curvature R of 0.105 m has been assumed.

[0053] The distance A of a longitudinal section at the longitudinal extension coordinate 25 is then given by A = R 1 − sin Winkel 43 , where the distance A in Fig.4 shown in the third column.

[0054] For example, if it is assumed that the relative mass mr of the connecting strand 12 per length mr = 0.3705 kg / m, the relative centripetal acceleration at the respective longitudinal extension coordinate 25, which results from the quotient of the absolute centripetal acceleration az and the acceleration due to gravity g, can be calculated using a z / g = 2 π n 2 A / g , where n is the rotational speed of the compensating rotor guide device 20 and for the exemplary calculation is 36.67 rpm (2200 rpm) and where g = 9.813 m / s 2<.

[0055] If the relative centripetal acceleration az / g is multiplied by the relative mass mr and the length ΔL of a longitudinal section, where ΔL = 0.01 m, the values ​​given in column 5 of Fig. 4 are specified. This column therefore indicates the centrifugal force acting on the longitudinal section relative to the length ΔL of the longitudinal section.

[0056] Should this be the result of the last column of the table in Fig. 4To calculate the tensile force acting on a longitudinal coordinate 25 (starting with the radially outermost longitudinal section at the longitudinal coordinate 25 of 0.21 m), the centrifugal force acting on the longitudinal section 25 must be calculated, which results from the product of the assigned value in the fifth column with g, and the result must be multiplied by the cosine of the angle 43 according to the second column of the table in Fig. 4multiplied, since only the component corresponding to the cosine of the angle 43 contributes to the tensile force acting in the direction of the longitudinal extension coordinate 25. With the transition to the next, radially inner adjacent longitudinal section 25, the previously determined tensile force is to be added to the tensile force calculated for the changed angle and the changed longitudinal extension coordinate 25 for this further longitudinal section 25. In the last column, more and more tensile force components of the individual radially outer longitudinal sections are summed up in the direction of the longitudinal extension coordinate 25.

[0057] The last column of Fig. 4 determined tensile force at the respective longitudinal coordinate 25 is also shown in column 2 of Fig. 5 In the third column, the elongation due to the tensile force D tensile force was calculated. Fig. 3In the following columns, the resulting resulting strains D resulting for a superposition of the strain due to the bending D bending for different radii of curvature R and the strain due to the tensile force D tensile force have been calculated.

[0058] If the design is such that the resulting elongation D should remain less than 12%, the radius of curvature R must be selected so that the Fig. 5 bold resulting strains D resulting. This means that for a longitudinal extension coordinate 25 in the range from 0.0 m to 0.05 m the radius of curvature R can be 0.115 m, a longitudinal extension coordinate 25 in the range from 0.06 m to 0.09 m the radius of curvature R can be 0.105 m, a longitudinal extension coordinate 25 in the range from 0.10 m to 0.11 m the radius of curvature R can be 0.095 m. a longitudinal extension coordinate 25 in the range from 0.12 m to 0.14 m the radius of curvature R can be 0.085 m, a longitudinal extension coordinate 25 in the range from 0.15 m to 0.16 m the radius of curvature R can be 0.075 m, a longitudinal extension coordinate 25 in the range from 0.17 m to 0.18 m the radius of curvature R can be 0.065 m and a longitudinal extension coordinate 25 in the range from 0.19 m to 0.21 m the radius of curvature R can be 0.55 m.

[0059] A calculation with a finer subdivision of the longitudinal extension coordinates 25 or a continuous calculation can also be performed. Excessive expansion can also be avoided by using larger radii of curvature than those specified in the above list for the respective longitudinal extension coordinates 25.

[0060] In Fig. 6 As a function of the coordinate 38 of the longitudinal extension coordinate 25 of the guide tube 21 or the hose or (corrugated) pipe 13, the effective tensile force 39 resulting from the centrifugal force is shown (see solid line, which was determined using a spline approximation of the individual tensile forces). On the other hand, the radius of curvature R 40 is shown here (see dashed line, which was also determined using a spline approximation), if the resulting elongation D may not exceed 12%.

[0061] As explained previously, the calculation method and the curve progression are as follows: Fig. 6 are shown only as examples and simplifying and possibly distorting assumptions have been made. As also mentioned previously, the actually used radius of curvature R may deviate from the tables or Fig. 6 in partial sections, in particular in the guide contour section 28 on the one hand and the guide contour section 29 on the other hand, be constant, provided that the radius of curvature R in a partial section adjacent to the rotor axis 7 is greater than in a partial section further away from the rotor axis 7. It is also possible to follow the curve according to Fig. 6 piecewise following, step-like or arbitrarily differently adapted courses of the radius of curvature R are used.

[0062] In Fig. 7A highly simplified schematic representation (for example, neglecting the friction between the connecting strand 12 and the hose or pipe 13 as well as the support of the hose or pipe 13 radially outward) is shown for an auxiliary consideration. In this case, the connecting strand 12 (in particular the hose or pipe 13 and / or the lines 14, 15, 16, 17) is divided into equally sized longitudinal sections 41, which are differentiated from each other by the suffix "-1", "-2". These longitudinal sections 41, which have the same masses Δm due to the same sizes, each have different distances A 1 , A 2 , ... from the rotor axis 7, which in Fig. 7 are marked with the reference numeral 42 and are also distinguished from each other by the suffix "-1", "-2", ... Each longitudinal section 41 is subject to the centrifugal acceleration az , for which a z = 2 πn 2 A where A is the respective distance 42 of the longitudinal sections 41 from the rotor axis 7 and n is the speed of the compensating rotor guide device 20 in [s -1< ]. The centrifugal force F z acting on the longitudinal sections 41 is then given by F z = Δ m a z .

[0063] For each longitudinal section 41, the centrifugal force F z leads to a tensile force acting in the direction of the longitudinal extension coordinate only with a force component that depends on the angle 43 for the respective longitudinal extension coordinate.

[0064] For the first longitudinal section 41-1, which is arranged coaxially to the rotor axis 7, the tensile force F Zug, 1 acting on the longitudinal section 41-1, in the simplified consideration chosen here, results from the sum of the centrifugal forces that must be held by the longitudinal section 41-1, i.e. from the sum of the force components of the centrifugal forces acting in the direction of the longitudinal extension coordinate 25, which act on the longitudinal sections 41-2, 41-3, ... Thus, the tensile force F Zug, 1 acting on the longitudinal section 41-1, F Zug , 1 = Δm 4 π 2 n 2 C 2 A 2 + C 3 A 3 + C 4 A 4 + … , while for the next longitudinal section 41-2 the tensile force F Zug, 2 can be determined as follows: F Zug , 2 = Δm 4 π 2 n 2 C 3 A 3 + C 4 A 4 + … etc.

[0065] Here, C describes, on the one hand, the conversion of the centrifugal force acting on the longitudinal section 41 into the force component acting in the direction of the longitudinal extension coordinate 25. Furthermore, another correction factor, for example, due to the consideration of friction, can also be taken into account in C. From the simplified consideration above, it follows that the acting tensile force F tensile is greatest at the longitudinal section 41-1, and with increasing distance of the longitudinal sections 41 from the rotor axis 7, the acting tensile force and thus the stress decrease.

[0066] Under certain circumstances, a more precise modeling of the acting stresses can be carried out, whereby the qualitative statement that an increase in the fatigue strength can be achieved by increasing the radius of curvature for longitudinal sections 41 adjacent to the rotor axis 7 remains unchanged. LIST OF REFERENCE SYMBOLS

[0067] 1 Flow-through centrifuge 2 Housing 3 Vessel 4 Wall 5 Rotor chamber 6 Rotor 7 Rotor axis 8 Container 9 Blood bag 10 Rotor chamber temperature control circuit 11 Rotor chamber temperature control loop 12 Connecting line 13 Hose, pipe 14 Temperature control supply line 15 Temperature control discharge line 16 Connecting line 17 Connecting line 18 End section 19 End section 20 Compensating rotor guide device 21 Guide tube 22 Guide tube half 23 Guide tube half 24 Parting line 25 Longitudinal extension coordinate 26 Inner surface 27 Guide contour 28 First guide contour section 29 Second guide contour section 30 Turning section 31 Intermediate section 32 First radius of curvature 33 Second radius of curvature 34End area 35End area 36End area 37End area 38Distance 39Tensile force 40Radius of curvature 41Longitudinal section 42Distance 43Angle

Claims

1. Continuous flow centrifuge (1) comprising a) a rotor (6) with a centrifugation chamber, the rotor (6) being rotatable about a rotor axis (7) at a rotor speed, and b) a connecting section (12) with a connecting conduit (16; 17), via which a medium can be supplied to the centrifugation chamber during operation of the continuous flow centrifuge (1) with a rotating rotor (6), and with a connecting conduit (17; 16), via which a medium can be discharged from the centrifugation chamber, c) wherein one end section (18) of the connecting section (12) is arranged fixed to the housing and the other end section (19) of the connecting section (12) is rotated with the rotor (6) and d) to avoid twisting of the connecting section (12), the connecting section (12) is guided in a compensating rotor guiding device (20), which is rotated about the rotor axis (7) at half the rotor speed, e) wherein the compensating rotor guiding device (20) comprises a guiding contour (27) whose radius of curvature (32) at a first distance from the rotor axis (7) is greater than the radius of curvature (33) at a second distance from the rotor axis (7), the first distance being smaller than the second distance, f) the guiding contour (27) comprises a first guiding contour section (28) and a second guiding contour section (29), g) the first guiding contour section (28) comprises a curvature in a first direction and the second guiding contour section (29) comprises a curvature in a second direction, h) the first guiding contour section (28) and the second guiding contour section (29) are connected to each other by an intermediate section (31) or turning section (30) that is preferably oriented radially to the rotor axis (7), i) the first guiding contour section (28) has a smaller distance from the rotor axis (7) than the second guiding contour section (29), characterized in that j) a radius of curvature (32) in the first guiding contour section (28) is greater than a radius of curvature (33) in the second guiding contour section (29), wherein preferably the radius of curvature (32) in the first guiding contour section (28) becomes smaller in the direction of a coordinate of the longitudinal extension (25) and becomes smaller with increasing distance from the rotor axis (7).

2. Continuous flow centrifuge (1) according to claim 1, characterized in that the connecting section (12) comprises a corrugated tube.

3. Continuous flow centrifuge (1) according to one of the preceding claims, characterized in that the radius of curvature (32) in the first guiding contour section (28) and / or the radius of curvature (33) in the second guiding contour section (29) becomes continuously smaller with increasing distance from the rotor axis (7).

4. Continuous flow centrifuge according to claim 3, characterized in that in the first guiding contour section (28) and / or in the second guiding contour section (29) a radius of curvature (32; 33) at different or all coordinates of the longitudinal extension (25) is dimensioned in such a way that a stress of the connecting section (12) guided in the compensating rotor guiding device (20) at the coordinates of the longitudinal extension (25) as a result of a superposition a) of a tensile stress of the connecting section (12) at the respective coordinates of the longitudinal extension (25) resulting from the centrifugal force caused by a longitudinal section of the connecting section (12) arranged radially outwardly of the respective coordinate of the longitudinal extension (25) and b) of a rotating bending stress of the connecting section (12) at the respective coordinates of the longitudinal extension (25), which results from the rotating bending of the connecting section (12) corresponding to the radius of curvature (32; 33), is constant over the longitudinal extension or varies by a maximum of ± 20 %, ± 15 %, ± 10 % or ± 5 %.

5. Continuous flow centrifuge (1) according to claim 3 or 4, characterized in that in the first guiding contour section (28) and / or in the second guiding contour section (29) a radius of curvature (32; 33) at different or all coordinates of the longitudinal extension (25) is dimensioned in such a way that a stress of the connecting section (12) guided in the compensating rotor guiding device (20) at the coordinates of the longitudinal extension (25) as a result of a superposition a) of a tensile stress of the connecting section (12) at the respective coordinates of the longitudinal extension (25) resulting from the centrifugal force caused by a longitudinal section of the connecting section (12) arranged radially outwardly of the respective coordinate of the longitudinal extension (25), and b) of a rotating bending stress of the connecting section (12) at the respective coordinate of the longitudinal extension, which results from the rotating bending of the connecting section (12) corresponding to the radius of curvature (32; 33), is at least a predetermined percentage less than a permissible stress of the connecting section (12).

6. Compensating rotor guiding device (20) for a continuous flow centrifuge (1) according to one of claims 1 to 5 comprising a guiding tube (21), wherein the guiding tube (21) comprises a guiding contour (27) which has a first guiding contour section (28) and a second guiding contour section (29), wherein a) the first guiding contour section (28) comprises a curvature in a first direction and the second guiding contour section (29) comprises a curvature in a second direction, b) the first guiding contour section (28) and the second guiding contour section (29) are connected to each other by an intermediate section (32) or a turning section (30) preferably oriented radially to the rotor axis (7), c) the first guiding contour section (28) has a smaller distance from the rotor axis (7) than the second guiding contour section (29) and d) a radius of curvature (32) in the first guiding contour section (28) is greater than a radius of curvature (33) in the second guiding contour section (29), wherein preferably the radius of curvature (32) in the first guiding contour section (28) becomes smaller in the direction of the end region (35) facing towards the second guiding contour section (29).

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