EP4321253A1 - Continuous flow centrifuge and balancing rotor guiding device - Google Patents

Abstract

The invention relates to a flow centrifuge with a rotor which has at least one centrifugation chamber and is rotated about a rotor axis (7) at a rotor speed. The flow centrifuge has a connecting strand (12) through which connecting lines (16, 17) extend. During operation of the flow centrifuge with a rotating rotor, a medium can be supplied to the centrifugation chamber via the connecting lines (16, 17) and the medium can be removed from the centrifugation chamber. One end region (18) of the connecting strand (12) is arranged fixed to the housing, while the other end region (19) of the connecting strand (12) is rotated with the rotor. To avoid twisting of the connecting strand (12), the connecting strand (12) is guided in a balancing 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 allows the service life of the connecting strand (12) to be increased.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a flow centrifuge in which at least one medium (in particular a fluid, a liquid, a suspension, etc.) is supplied to a centrifugation chamber at least temporarily 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.

To give just a few examples that do not limit the invention, the flow centrifuge may be a blood centrifuge in which the medium to be centrifuged is blood and the extracted modified medium or sediment is blood bodies or particles, or it may be a flow centrifuge, by means of which cells, microcarriers or other particles contained in the medium are to be obtained from a medium. It is also possible that the centrifuged medium is not a pure liquid, but rather the medium is a solution or suspension with particles such as cells, cell debris or parts, etc.

The flow centrifuge is used, for example, for the production of biopharmaceutical products in biopharmaceutical companies or in bio-processing applications. The flow centrifuge can be used, for example, to obtain and/or clarify the cells or microcarriers, whereby the cells obtained in this way can also be used for cell therapy. Another area of application for the flow centrifuge is, for example, the production of vaccines.

The invention also relates to a balancing rotor guide device.

STATE OF THE ART

Generic flow centrifuges are sold, for example, by the company Sartorius AG, Otto-Brenner-Straße 20, 37079 Göttingen, Germany, and affiliated companies under the label “Ksep” (registered trademark). On the website relating to these flow centrifuges
www.sartorius.com/en/products/process-filtration/cell-harvesting/ksep-systems (date of inspection: July 6, 2022)
The functional principle of a flow centrifuge, which can also be used for the present invention, is described as follows on the basis of 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 over the circumference. The centrifugation chambers are arranged at equal radial distances from the axis of rotation of the rotor. A first connection line opens into a centrifugation chamber radially on the inside, while a second connection line opens into the centrifugation chamber on the radial outside. In a first operating phase, a first medium, for example blood, is supplied to the centrifugation chamber via the second connection line while the centrifugation chamber rotates with the rotor. In the centrifugation chamber, as a result of centrifugation, particles contained in the blood (e.g. blood bodies) are deposited radially on the outside, while the residual medium (i.e. the medium supplied radially on the outside reduced by the particles pushed radially outwards) flows out of the centrifugation chamber radially on the inside via the first connecting line. is discharged. In this first operating phase, the first connecting line is 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 the particles. In a subsequent optional second operating phase, the particles are washed in the centrifugation chamber. For this purpose, a washing or buffer solution is fed into the centrifugation chamber via the second connection line. The washing or buffer solution is flushed through the centrifugation chamber and is discharged radially on the inside via the first connection line. In this operating phase, too, the centrifugation chamber rotates with the rotor, so that as a result of the centrifugation force acting, the particles are prevented from exiting the centrifugation chamber with the washing or buffer solution via the first connection line. Even during the second operating phase, the first connection line serves as a discharge line for the washing or buffer solution, while the first connection line serves as a supply line for the washing or buffer solution. In a subsequent third operating phase, the centrifugation chamber continues to be rotated with the rotor. In the third operating phase, the direction of flow through the centrifugation chamber is reversed and the particles are removed from the centrifugation chamber via the second connection line, while washing or buffer solution can be fed into the centrifugation chamber via the first connection line. The third operating phase ends when all particles have been removed from the centrifugation chamber. This can be successively followed by further cycles with the three operating phases explained.

EP 3 936 601 A1 The design of a medium network can be seen, which is connected to the connection lines and ensures the different operating phases. With regard to this medium network, the included pump arrangement, the process control unit, an additional filter arrangement, receptacles for the different media and with regard to the process flow, additional information is provided EP 3 936 601 A1 , EP 2 310 486 B1 and EP 2 485 846 B1 referred.

EP 2 485 846 B1 describes that in flow centrifuges, fluidic connections to connection lines rotating with the rotor using rotary feedthroughs can be problematic, as the rotary feedthroughs are susceptible to leaks and carry 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 strands can be used in which the connecting cables can be integrated. One end region of the connecting strand is arranged fixed to the housing, while the other end region of the connecting strand is attached to the rotor and is rotated with the rotor. In order to prevent the twisting of the connecting strand from becoming ever greater as a result of 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 that has the shape of a rounded U with slight has spread apart side legs of different lengths. The opening of the U points in the direction of the rotation axis of the rotor. Starting from the end region fixed to the housing, the connecting strand enters a side leg of the U while curving outwards. In the U-shaped section, the connecting strand is guided around the rotor through the guide tube. The free end region of the other side leg of the U of the guide tube is curved back so that it is arranged coaxially to the axis of rotation of the rotor and is arranged immediately adjacent to the entry of the connecting strand into the rotor. The guide tube is then driven at half the speed of the rotor. EP 2 485 846 B1 Refers to the publication to explain how to avoid increasing twisting of the connecting strand by using the rotating guide tube US 3,586,413 .

OBJECT OF THE INVENTION

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 in terms of stress and fatigue strength.

SOLUTION

The object of the invention is achieved according to the invention with the features of the independent patent claims. Further preferred embodiments according to the invention can be found in the dependent patent claims.

DESCRIPTION OF THE INVENTION

The invention relates to a flow centrifuge. The flow centrifuge has a rotor that has (at least) one centrifugation chamber. The medium to be centrifuged can be arranged in the centrifugation chamber directly or in a suitable container and this can be flushed with other media such as a washing or buffer solution. In the flow centrifuge, the rotor is rotated around the rotor axis at a rotor speed. The flow centrifuge has a connecting cable. The connecting strand has a connecting line via which a medium can be supplied to the centrifugation chamber (in particular a container arranged in the centrifugation chamber) during operation of the flow centrifuge with a rotating rotor. Furthermore, the connecting strand has a Connection line via which a medium can be removed from the centrifugation chamber (in particular a container arranged in the centrifugation chamber). Depending on the operating phase, the flow directions through the connection lines can be reversed. One end region of the connecting strand is arranged fixed to the housing, while the other end region of the connecting strand is rotated with the rotor. In order to avoid twisting of the connecting strand, the connecting strand is twisted with a compensating rotor, the connecting strand being guided in a compensating rotor guide device of the compensating rotor, in particular a guide tube. The balancing rotor and the balancing rotor guide device are rotated around the rotor axis at half the rotor speed. In this respect, the flow centrifuge can, for example, be designed like the flow centrifuges of the prior art mentioned at the beginning.

In conventional flow centrifuges, the connecting strand consists of a flexible pipe or hose (preferably a corrugated pipe) through which the connecting lines extend. It is entirely possible that the costs of such a connecting strand with the connecting lines and the interfaces to the rotor on the one hand and to the medium network on the other hand are in the range of €5,000 to €15,000. Due to the high stress on the connecting line during operation of the flow centrifuge, it may be necessary to replace the connecting line after just 5 to 20 hours of operation, which on the one hand leads to long changeover times and downtimes of the flow centrifuge and on the other hand causes considerable costs. Since it is generally not possible to extend the operating life of the connecting strand by reducing the speed of the rotor or increasing the dimensions of the connecting strand and/or choosing high-strength materials for the connecting strand, such short service lives of the connecting strand are accepted according to the prior art.

1. a) Der Verbindungsstrang führt in der Ausgleichsrotor-Führungseinrichtung eine relative Drehbewegung um die Längsachse aus. Diese relative Drehbewegung führt zu einer Reibung zwischen dem Verbindungsstrang und der Ausgleichsrotor-Führungseinrichtung. Diese Reibung führt zu einer über die Längserstreckung des Verbindungsstrangs variierenden Torsionsbeanspruchung des Verbindungsstrangs. Darüber hinaus führt die Reibung zwischen dem Verbindungsstrang und der Innenwandung der Ausgleichsrotor-Führungseinrichtung zu einem Wärmeeintrag in den Verbindungsstrang im Bereich der Kontakt- und Reibflächen und unter Umständen zu einem Verschleiß.
2. b) Der Verbindungsstrang ist in der Ausgleichsrotor-Führungseinrichtung so geführt, dass der Verbindungsstrang, einem ersten Führungskonturabschnitt der Ausgleichsrotor-Führungseinrichtung folgend, von dem gehäusefesten Endbereich und der dortigen koaxialen Anordnung zu der Rotorachse nach außen gekrümmt ist. Ab einem Wendepunkt ist dann der Verbindungsstrang in einem zweiten Führungskonturabschnitt der Ausgleichsrotor-Führungseinrichtung in die entgegengesetzte Richtung gekrümmt, bis der Verbindungsstrang mit einem parallel zu der Rotorachse orientierten Abschnitt radial außenliegend an dem Rotor vorbeigeführt werden kann. Der Verbindungsstrang ist somit in den genannten Führungskonturabschnitten entsprechend einem langgestreckten S geführt, wobei die beiden Enden des S parallel zueinander orientiert sind und ein Ende koaxial zur Rotorachse angeordnet ist, während das andere Ende den maximalen Abstand des Verbindungsstrangs von der Rotorachse aufweist. Der Verbindungsstrang ist in der Ausgleichsrotor-Führungseinrichtung entsprechend den Führungskonturen der genannten Führungskonturabschnitte gekrümmt und somit aus seiner langgestreckten Ausgangslage mit einer Biegung beaufschlagt.
   Infolge der mechanischen Randbedingungen des Verbindungsstrangs, nämlich
   • der Befestigung eines Endbereichs des Verbindungsstrangs an dem ruhenden Gehäuse,
   • der Befestigung des anderen Endbereichs des Verbindungsstrangs an dem Rotor, der mit der Rotordrehzahl rotiert und
   • der Führung des Verbindungsstrangs in der Ausgleichsrotor-Führungseinrichtung, die mit der halben Rotordrehzahl verdreht wird,
   ist die Biegung des Verbindungsstrangs nicht stationär, sondern diese stellt eine Umlaufbiegung dar. Abseits einer (imaginären) neutralen Faser ist infolge der Umlaufbiegung ein jeweils temporär radial außenliegender Materialbereich des Verbindungsstrangs, insbesondere des flexiblen Schlauchs oder des flexiblen (Well-)Rohrs, abwechselnd mit einem harmonischen Verlauf einer Wechselspannung, also abwechselnd einer Zug- und einer Druckspannung, ausgesetzt.
3. c) Verfügt der Verbindungsstrang über ein Wellrohr, kann die umlaufende Biegung des Wellrohrs dazu führen, dass Wellen oder Rippen des Wellrohrs auf der radial innenliegenden Seite der gekrümmten Führungskontur aneinander zur Anlage kommen, was zu einer Nichtlinearität in der Steifigkeit des Wellrohrs führen kann, die einen veränderten Beanspruchungsmechanismus des Wellrohrs zur Folge haben kann.
4. d) Der Erfindung zugrunde liegende Überlegungen haben zu dem Ergebnis geführt, dass auf Längsabschnitte des Verbindungsstrangs (insbesondere den Schlauch oder das (Well-) Rohr und die darin angeordneten Leitungen und auch auf das in den Leitungen angeordnete Medium) eine Zentrifugalkraft wirkt, deren Betrag von dem Abstand des jeweiligen Längsabschnittes von der Rotorachse abhängig ist. Hierbei weist die auf den jeweiligen Längsabschnitt wirkende Zentrifugalkraft
   • eine erste Komponente auf, die in Richtung der Führungsfläche der Ausgleichsrotor-Führungseinrichtung wirkt und somit die Anpresskraft und Reibung zwischen dem Verbindungsstrang und der Ausgleichsrotor-Führungseinrichtung erhöht,
   • und eine zweite Komponente auf, die in Längsrichtung des Verbindungsstrangs orientiert ist und zu einer Zug- oder Druckkraft in Längsrichtung des Verbindungsstrangs führt.
   Die Aufteilung der Zentrifugalkraft auf die beiden Komponenten ergibt sich aus den trigonometrischen Funktionen in Abhängigkeit des Winkels, unter dem der Längsabschnitt gegenüber der Rotorachse geneigt ist. In dem ersten Führungskonturabschnitt führt die zweite Komponente zu einer Zugkraft, die eine Dehnung des Verbindungsstrangs zur Folge hat, während diese in dem zweiten Führungskonturabschnitt zu einer Druckkraft führt, die den Verbindungsstrang komprimiert. Hierbei ist eine Zugkraft infolge der Zentrifugalkraft in einem ersten Materialbereich des Verbindungsstrangs an einer ersten Längserstreckungskoordinate des Verbindungsstrangs, der einen kleinen Abstand von der Rotorachse hat, u. U. größer als die Zugkraft infolge der Zentrifugalkraft in einem zweiten Materialbereich des Verbindungsstrangs an einer zweiten Längserstreckungskoordinate des Verbindungsstrangs, der einen größeren Abstand von der Rotorachse hat. Der Grund hierfür ist, dass radial außenliegend von dem ersten Materialbereich des Verbindungsstrangs an der ersten Längserstreckungskoordinate des Verbindungsstrangs ein längerer Abschnitt des Verbindungsstrangs angeordnet ist, der zu einer größeren Zugkraft infolge der Zentrifugalkraft führen kann.
5. e) Je nach den wirkenden Beanspruchungen kann es zu veränderten Randbedingungen in dem Verbindungsstrang kommen. So kann beispielsweise eine Dehnung einer Anschlussleitung in dem Schlauch oder (Well-)Rohr dazu führen, dass die Anschlussleitung nicht mehr an der Innenfläche des Schlauchs oder (Well-)Rohrs anliegt, womit keine innere Abstützung des Schlauchs oder (Well-)Rohrs mehr gegeben ist und sich eine innere Reibung des Verbindungsstrangs verändert. Möglich ist auch, dass sich hierdurch eine Längs- und/oder Biegesteifigkeit des Verbindungsstrangs verändert.
6. f) Eine weitere Bedeutung kann eine etwaige Elastizität des Mediums in den Leitungen des Verbindungsstrangs haben, da die Zentrifugalkraft infolge der Elastizität zu Druckänderungen im Inneren der Anschlussleitungen, zu einer damit verbundenen veränderten Masseverteilung und/oder zu einer Veränderung der Steifigkeit führen kann.

The invention is initially based on an investigation of the stresses acting on the connecting line during operation of the flow centrifuge. The investigations on which the invention is based have led to the conclusion that the connecting strand in the flow centrifuge is subject to complex stress:

1. a) The connecting strand carries out a relative rotational movement about the longitudinal axis in the compensating rotor guide device. This relative rotational movement results in friction between the connecting strand and the balance rotor guide device. This friction leads to a torsional stress on the connecting strand that varies over the longitudinal extent of the connecting strand. In addition, 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.
2. b) The connecting strand is guided in the compensating rotor guide device in such a way 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 past the rotor radially on the outside with a section oriented parallel to the rotor axis. The connecting strand is thus guided in the mentioned 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 has the maximum distance of the connecting strand from the rotor axis. The connecting strand is curved in the compensating rotor guide device in accordance with the guide contours of the guide contour sections mentioned and is therefore subjected to a bend from its elongated starting position.
   As a result of the mechanical boundary conditions of the connecting strand, namely
   • the attachment of an end region of the connecting strand to the stationary housing,
   • attaching the other end portion of the connecting strand to the rotor, which rotates at the rotor speed and
   • the guidance of the connecting strand in the balancing rotor guide device, which is rotated at half the rotor speed,
   The bend of the connecting strand is not stationary, but represents a circular bend. Away from an (imaginary) neutral fiber, as a result of the circular bend, there is a each temporarily radially external material area of the connecting strand, in particular of the flexible hose or the flexible (corrugated) pipe, alternately exposed to a harmonious course of an alternating stress, i.e. alternately a tensile and a compressive stress.
3. c) If the connecting strand has a corrugated tube, the circumferential bending of the corrugated tube can lead to waves or ribs of the corrugated tube 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 rigidity of the corrugated tube can result in a changed stress mechanism on the corrugated pipe.
4. d) 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 amount of which depends on the distance of the respective longitudinal section from the rotor axis. The centrifugal force acting on the respective longitudinal section points
   • a first component which 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 which is oriented in the longitudinal direction of the connecting strand and results in 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 which results in an elongation of the connecting strand, while in the second guide contour section this leads to a compressive force which compresses the connecting strand. Here, 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 small 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 at a greater distance from the rotor axis. The reason for this is that a longer section of the connecting strand is arranged radially outside of 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 as a result of the centrifugal force.
5. e) Depending on the stresses acting, the boundary conditions in the connecting strand may change. For example, a stretching of a connecting line in the hose or (corrugated) pipe can result in the connecting line no longer resting against the inner surface of the hose or (corrugated) pipe, which means there is no longer any internal support for the hose or (corrugated) pipe is given and internal friction of the connecting strand changes. It is also possible that this changes the longitudinal and/or flexural rigidity of the connecting strand.
6. f) Any elasticity of the medium in the lines of the connecting line may have further significance, since the centrifugal force as a result of 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.

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

This will be explained using the simplifying example, which does not limit the invention, that the guide contour is designed according to an elongated S in the horizontal direction with 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 There is a turning point in the middle of these end areas, in the area of which the curvature changes sign in a mathematical sense. For this simplifying 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 guiding contour section between the turning point and the upper right end region, the radius of curvature is constant with a second radius of curvature, the second Radius of curvature is smaller than the first radius of curvature.

In the first guide contour section, the cross sections at the respective longitudinal extension coordinates are subjected to a rotational bending stress as a result of the circumferential bending, which can be constant in magnitude over the longitudinal extent in the first guide contour section, but changes its sign according to the revolution with a harmonious course. Superimposed on this rotating bending stress is the tensile stress, which arises as a result of the mass of the connecting strand as a result of the centrifugal force in accordance with the distance from the rotor axis and which is quadratically dependent on the speed. At the first end of the first guide contour section, where the bending begins from the coaxial alignment with the rotor axis, the centrifugal force acts, which is generated by the entire section of the connecting strand in the first guide contour section and, under certain circumstances, also a section in the second guide contour section. For longitudinal extension coordinates in the first guide contour section with a greater distance from the rotor axis, the tensile force acting as a result of the centrifugal force in the cross section at the longitudinal extension coordinate is reduced, so that at the first end the tensile force as a result of the centrifugal force and the resulting tensile stress is maximum. In the cross sections at the respective longitudinal extension coordinates, the circumferential bending stress and the tensile stress due to the centrifugal force are superimposed. If the circumferential bending temporarily leads to a circumferential bending compressive stress, the superposition of the tensile stress due to the centrifugal force results in a reduction in the resulting stress, which is advantageous 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 bend, for which the superposition of the tensile stress as a result of the centrifugal force then leads to an addition of the amounts of the circumferential bending tensile stress and the tensile stress as a result of the centrifugal force. This results in an increased maximum of the resulting stress, which can be responsible for a possible attempt to explain the limitation of the service life of the connecting strand.

The design according to the invention allows the maximum of the resulting stress to be reduced, which means that the service life can be increased (possibly significantly):
According to the invention, the radius of curvature is chosen to be larger in the area of the rotor axis or adjacent to it. By increasing the radius of curvature, the amplitude of the circumferential 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 superimposition with the tensile stress due to the centrifugal force.

• lediglich für einen diskreten Krümmungsradius an einer spezifischen Längserstreckungskoordinate der Führungskonturabschnitte gelten,
• für einen Teilabschnitt der Führungskonturabschnitte gelten, in dem der Krümmungsradius konstant ist,
• für gemittelte Krümmungsradien in den Führungskonturteilabschnitten gelten oder
• für sämtliche Krümmungsradien bei einem sich kontinuierlich verändernden Krümmungsradius in den Führungskonturabschnitten gelten.

For one proposal of 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 designed in the shape of a quarter circle with curvatures in opposite directions, in which case the guide contour sections have different radii. However, it is also entirely possible for guide contour part sections with different radii of curvature to be present in at least one guide contour section, whereby the radius of curvature can vary in steps or even 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 which is preferably oriented radially to the rotor axis. For the example explained at the beginning 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, it being also possible for a straight, 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 has 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 give just a few examples that do not limit the invention, the radius of curvature in the first guide contour section can be increased by 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 % be larger than the radius of curvature in the second guide contour section. This can, for example,

• only apply to a discrete radius of curvature at a specific longitudinal extension coordinate of the guide contour sections,
• apply to a 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.

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.

In principle, within the scope of the invention, the connecting strand can be constructed in any way. The connecting strand preferably has a corrugated tube through which the different lines, in particular connecting lines, of the connecting strand can extend. The corrugated pipe is used, for example, to bundle the cables, protect the cables and guide and encapsulate the cables.

For a particular proposal of the invention, the radius of curvature in the first guide contour section becomes continuously smaller as the distance from the rotor axis increases. It is possible that this only applies to the first guide contour section. Preferably, the radius of curvature in the second guide contour section also becomes continuously smaller as the distance from the rotor axis increases.

• einer Zugbeanspruchung des Verbindungsstrangs an den Längserstreckungskoordinaten, die sich infolge der Zentrifugalkraft infolge des Abschnitts des Verbindungsstrangs, der radial außenliegend von der Längserstreckungskoordinate angeordnet ist, ergibt;
• einer Umlaufbiegebeanspruchung des Verbindungsstrangs an den Längserstreckungskoordinaten, die sich infolge der umlaufenden Biegung des Verbindungsstrangs entsprechend der Krümmung desselben ergibt.

As explained above, the stresses on the connecting strand 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 one embodiment of the flow centrifuge, in the first guide contour section and/or in the second guide contour section, a radius of curvature at the different longitudinal extension coordinates is dimensioned such that a stress on the connecting strand guided in the compensating rotor guide device is constant at these or all longitudinal extension coordinates or only a maximum of ± 20% , maximum ± 15%, maximum ± 10% or maximum ± 5% varies. Here the stress that should remain constant or only around the specified Percentage should vary, determined from a superposition of two different partial stresses:

• a tensile stress on the connecting strand at the longitudinal extension coordinates, which arises as a result of the centrifugal force due to the section of the connecting strand which is arranged radially outside of the longitudinal extension coordinate;
• a circumferential bending stress on the connecting strand at the longitudinal extension coordinates, which results from the circumferential bending of the connecting strand in accordance with the curvature of the same.

This interpretation is based, on the one hand, on the assumption that the two partial stresses mentioned are decisive for the strength of the connecting strand, whereby on the one hand safety can be taken into account via the specified percentage variation ranges and, on the other hand, other occurring stresses (friction, heating, wear, ...) are taken into account can be worn.

For an alternative or cumulative design criterion, the radius of curvature is dimensioned in such a way that the stress due to the aforementioned two partial stresses over 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 smaller than a permissible stress on the connecting strand . For example, for the use of a corrugated pipe in the connecting strand, a maximum static bending stress can be specified by the manufacturer, so that in this case the resulting stress determined from the two partial stresses is smaller by a predetermined percentage than this bending stress specified by the manufacturer. A further permissible stress, to which the stress determined with the partial stresses is based on a percentage, can be a maximum dynamic tensile and/or bending stress or a predetermined tensile strength or fatigue strength of a component of the connecting strand or of the entire connecting strand.

A further solution to the problem on which the invention is based is a balancing rotor guide device which is intended for a flow centrifuge, as explained above. The balancing rotor guide device has or consists of a guide tube 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 portion has a curvature in a first direction, while the second guide contour portion has a curvature in a second direction that is 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 or a turning section, which is preferably oriented radially to the rotor axis. The first guide contour section has a smaller distance from the rotor axis than the second guide contour section. The radius of curvature in the first guide contour section is smaller than the radius of curvature in the second guide contour section. Alternatively or cumulatively, the radius of curvature in the first guide contour section in the guide tube becomes smaller in the direction of the end region that faces the second guide contour section, which can occur in stages or continuously.

Advantageous developments of the invention result from the patent claims, the description and the drawings.

The advantages of features and combinations of several features mentioned in the description are merely examples and can have an alternative or cumulative effect without the advantages necessarily having to be achieved by embodiments according to the invention.

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 geometries shown 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 of features of different patent claims is also possible, deviating from the selected relationships of the patent claims, and is hereby encouraged. This also applies to features that are shown in separate drawings or are 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.

The features mentioned in the patent claims and the description are to be understood in terms of their number in such a way that exactly this number or a larger number than the number mentioned is present, without the need for an explicit use of the adverb "at least". For example, when we talk about an element, this should be understood to mean that there is exactly one element, two elements or more elements. The features listed in the patent claims can be supplemented by further features or can be the only features that the subject of the respective patent claim has.

The reference symbols contained in the patent claims do not represent a limitation on the scope of the subject matter protected by the patent claims. They merely serve the purpose of making the patent claims easier to understand.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

zeigt in einem räumlichen Halblängsschnitt stark schematisiert eine Durchflusszentrifuge mit einem Verbindungsstrang (ohne Darstellung der Führungseinrichtung).

Fig. 2

zeigt einen Verbindungsstrang in einer Führungseinrichtung, wie diese Einsatz finden können in einer Durchflusszentrifuge gemäß Fig. 1.

Fig. 3 bis 5

zeigen Tabellen für die Dimensionierung der Krümmungsradien eines Führungsrohrs einer Ausgleichsrotor-Führungseinrichtung.

Fig. 6

zeigt einen beispielhaften Verlauf eines Krümmungsradius eines Führungsrohrs einer Ausgleichsrotor-Führungseinrichtung sowie einer sich infolge der Zentrifugalkraft ergebenden Zugkraft in Abhängigkeit von dem Abstand von einer Rotorachse.

Fig. 7

zeigt eine schematische Darstellung für eine Hilfsüberlegung zur Ermittlung einer an einer an einem Längsabschnitt an einer Längserstreckungskoordinate und in einem Abstand von einer Rotorachse auf ein Rohr oder einen Schlauch des Verbindungsstrangs wirkenden Zugkraft infolge einer Zentrifugalkraft.

The invention is further explained and described below using preferred exemplary embodiments shown in the figures.

Fig. 1

shows a highly schematic spatial semi-longitudinal section of a flow centrifuge with a connecting line (without showing the guide device).

Fig. 2

shows a connecting strand in a guide device, as can be used in a flow centrifuge according to Fig. 1 .

Fig. 3 to 5

show tables for dimensioning the radii of curvature of a guide tube of a balancing rotor guide device.

Fig. 6

shows an exemplary course of a radius of curvature of a guide tube of a balancing 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 on a on a longitudinal section on a longitudinal extension coordinate and in a distance from a rotor axis on a pipe or a hose of the connecting strand acting tensile force as a result of a centrifugal force.

FIGURE DESCRIPTION

In the figures, components or features that correspond or are similar are sometimes marked with 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 letter, which can then address one of the components or features, several or all of the components or features.

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

The flow centrifuge 1 has a rotor chamber temperature control circuit 10, of which in Fig. 1 only a rotor chamber temperature control loop 11 is shown. The rotor chamber temperature control loop 11 is integrated into the wall 4 of the boiler 3 and winds with several turns around the rotor axis 7 and the rotor chamber 5.

In Fig. 1 a connecting strand 12 can also be seen. The connecting strand 12 has a flexible hose or a flexible tube 13, which is in particular a corrugated tube. A temperature control feed line 14 and a temperature control discharge line 15 optionally extend through the hose or pipe 13, which can serve to control the temperature and cool the connecting line. Two extend through the hose or tube 13 Connecting lines 16, 17, through which the media flows in different directions in the different operating phases of the centrifugation process. In one end region 18, the connecting strand 12 is attached to the housing 2 or a wall 4 of the boiler 3, while in another end region 19 the connecting strand 12 is attached to the rotor 6 and is rotated with it.

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 in Fig. 2 is 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, the longitudinal extension coordinate 25 being 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. There is a radial play between an inner surface 26 of the guide tube 21 and the lateral surface of the connecting strand 12, with the connecting strand 12 being able to rest against the inner surface 26 of the guide tube 21 on one side, depending on the curvature of the connecting strand 12 and the previously explained stresses on the same.

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 area 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. 2 the 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, the second radius of curvature 33 being smaller than the first radius of curvature 32. In the first guide contour section 28, the curvature of the longitudinal extension coordinate 25 is counterclockwise, while in the turning section 30 it is reversed, so that in the second guide contour section 29, the curvature of the longitudinal extension coordinate 25 runs in the clockwise direction. The guide contour sections 28, 29 each extend over a circumferential angle of 90°. However, smaller circumferential angles are also possible, so that the guide tube 21 in the turning section 30 is not oriented radially to the rotor axis 7.

As in Fig. 2 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 flush in the turning section 30 and intermediate section 31. On the other hand, the other end region 37 of the second guide contour section 29 is oriented parallel to the rotor axis 7, with the guide tube 21 being at the maximum distance from the rotor axis 7 in this region. 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 exemplary embodiment shown, this mirror symmetry only applies 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 reflection, so that in the direction of the longitudinal extension coordinate 25 both guide contour sections 28 ', 29 'are curved in the clockwise direction and together form a half ring with a radius of curvature 32' which increases in the area of the turning section 30' and intermediate section 31' in the direction of the longitudinal extension coordinate 25.

For the exemplary embodiment according to Fig. 2 The guide tube 21 can thus consist of two assembled guide contour parts, which are identical and each form the guide contour sections 29, 29 ', and two guide tube parts which form the guide contour sections 28, 28', which may increase the constant proportion for the production of the guide tube 21 can be. It goes without saying that it is also possible to manufacture the guide tube 21 in one piece, depending on the manufacturing process used.

The ones in the Fig. 2 The guide contour sections 28, 29 shown are shown and explained only as examples, without the invention being limited thereby.

The first suggestion is different Fig. 2 the radius of curvature 32 in the guide contour section 28 is not constant. Rather, this decreases in steps or continuously along the longitudinal extension coordinate 25.

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

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 section and is constant or changes in steps in another section can then be used in the second guide contour section 29.

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 below, a simplifying calculation with simplifying assumptions being explained here and the invention not being restricted to the radii of curvature determined in this way. 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 pipe 21. As in Fig. 2 can be seen, this is actually not the case, so that for a calculation with increased accuracy, a determination of the course of the hose or (corrugated) pipe 13 in the guide tube 21 and then a corresponding calculation of the radii of curvature for this course must be carried out.

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

berechnet worden (vgl. erste und zweite Spalte).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, is the expansion D _{tensile force} of the hose or (corrugated) pipe 13 resulting from the spring constant c $${\mathrm{D}}_{\mathrm{traction}}={\mathrm{F}}_{\mathrm{Train}}/\mathrm{c}$$

calculated (see first and second columns).

If the hose or pipe is bent with a radius of curvature R, the material area on the outside in terms of the curvature is subjected to expansion, while the material area on the inside is compressed. The elongation D _bending due to the bending in the radially outer area can be determined via $${\mathrm{D}}_{\mathrm{bend}}=0.5\mathrm{D}/\left(\mathrm{R}+0.5\mathrm{D}\right).$$

In the table in Fig. 3 In the fourth line, for the radii of curvature R given in the second line in the range from 0.45 m to 0.175 m, the elongation D _bend resulting from this bend is given.

If, during operation, the stretch due to the bend D _bend and the stretch due to the tensile force D _{tensile force} are superimposed in the material area that is maximally stretched as a result of the bend, then the following are shown in the table Fig. 3 Add the elongation due to the tensile force D _{tensile force} on the one hand and the elongation for a pure bend D _bend , which _{results in} the specified resulting elongations D.

• für Zugkräfte von 0 N bis 60 N (also bei einer weit von der Rotorachse 7 entfernten Längserstreckungskoordinate 25, bei der vorzugsweise das Führungsrohr 21 parallel zur Rotorachse 7 orientiert ist und somit keine Zentrifugalkraft wirkt) der Krümmungsradius R 0,055 m betragen kann,
• für Zugkräfte von 90 N bis 120 N der Krümmungsradius R 0,065 m betragen kann,
• für eine Zugkraft von 150 N bis 180 N der Krümmungsradius R 0,075 m betragen kann,
• für Zugkräfte von 210 N bis 240 N der Krümmungsradius R 0,085 m betragen kann,
• für eine Zugkraft von 270 N der Krümmungsradius R 0,095 m betragen kann,
• für eine Zugkraft von 300 N der Krümmungsradius R 0,105 m betragen kann,
• für eine Zugkraft von 330 N (die sich beispielsweise an einer Längserstreckungskoordinate 25 des Führungsrohrs 21 in dem Führungskonturabschnitt 8 in dem Endbereich 34 ergibt) der Krümmungsradius R 0,115 m betragen kann.

If the radius of curvature R is to be designed in such a way that the resulting elongation D _resulting from the superimposition is always smaller than 12%, only the radii of curvature R come into consideration, for which the table shows Fig. 3 the _resulting strains D are highlighted in bold. This means that for a _resulting elongation D less than 12%

• for tensile forces of 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 therefore no centrifugal force acts), the radius of curvature R can be 0.055 m,
• for tensile forces of 90 N to 120 N the radius of curvature R can be 0.065 m,
• for a tensile force of 150 N to 180 N the radius of curvature R can be 0.075 m,
• for tensile forces of 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.

(A corresponding calculation can also be made with smaller levels of tensile force or with a continuous change in the tensile force.)

According to the table Fig. 4 the first column shows a length along the longitudinal extension coordinate 25 of the guide tube 21 from the rotor axis 7 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 indicated in radians relative to an orientation radial to the rotor axis 7. At the longitudinal extension coordinate 0.00m, i.e. at the entry into the guide tube 21, the angle is 43 π/2, while the angle 43 is zero at the turning section 30 and is 37 - π/2 at the end region.

wobei hier ein konstanter Krümmungsradius R von 0,105 m angenommen worden ist.If one makes the simplifying assumption 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 used for the respective longitudinal extension coordinate 25 between these characteristic angles 43 $$\mathrm{<figure-callout\; id="43"\; label="angle"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">angle</figure-callout>}43=\mathrm{\pi }/2-\left(\mathrm{\pi }/2\times \mathrm{Longitudinal\; extension\; coordinate}25/\mathrm{R}\right),$$

whereby a constant radius of curvature R of 0.105 m has been assumed here.

wobei der Abstand A in Fig.4 in der dritten Spalte dargestellt ist.The distance A of a longitudinal section at the longitudinal extension coordinate 25 then results from $$\mathrm{A}=\mathrm{R}\left(1-\mathrm{<figure-callout\; id="43"\; label="sin\; angle"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">sin</figure-callout>}\left(\mathrm{angle}\right)\left(43\right)\right),$$

where the distance A is in Fig.4 is shown in the third column.

wobei n die Drehzahl der Ausgleichsrotor-Führungseinrichtung 20 ist und für die beispielhafte Berechnung 36,67 U/sec (2200 U/min) beträgt und wobei g = 9,813 m/s² gilt.For example, if it is assumed that the relative mass m _r of the connecting strand 12 per length m _r =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 a _z and the gravitational acceleration g, can be calculated via $${\mathrm{a}}_{\mathrm{e.g}}/\mathrm{G}={\left(2\mathrm{\pi }\mathrm{n}\right)}^2\mathrm{A}/\mathrm{G},$$

where n is the speed of the balancing rotor guide device 20 and for the exemplary calculation is 36.67 rpm (2200 rpm) and where g = 9.813 m/s ² applies.

If the relative centripetal acceleration a _z /g is multiplied by the relative mass m _r 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 based on the length ΔL of a longitudinal section.

This should be the one in the last column of the table Fig. 4 specified tensile force acting on a longitudinal extension coordinate 25 must be calculated (starting with the radially outermost longitudinal section on the longitudinal extension coordinate 25 of 0.21 m) the centrifugal force acting on the longitudinal section 25 must be calculated, which is the product of the assigned value in the fifth column with g, and the result must be with the cosine of the angle 43 according to the second column of the table in Fig. 4 be multiplied, since only the component according to the cosine of the angle 43 makes a contribution 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 there are more and more in the direction of the longitudinal extension coordinates 25 Tensile force components of the individual longitudinal sections arranged radially on the outside are summed up.

The ones in the last column of Fig. 4 The tensile force determined at the respective longitudinal extension coordinate 25 is also in column 2 of Fig. 5 registered. In the third column, the elongation as a result of the tensile force D _{tensile force} has been calculated. Accordingly Fig. 3 The resulting resulting strains D have then been calculated in the following columns for a superposition of the strain _resulting from the bending D _bending for different radii of curvature R and the strain resulting from the tensile force D _{tensile force} .

• eine Längserstreckungskoordinate 25 im Bereich von 0,0 m bis 0,05 m der Krümmungsradius R 0,115 m betragen kann,
• eine Längserstreckungskoordinate 25 im Bereich von 0,06 m bis 0,09 m der Krümmungsradius R 0,105 m betragen kann,
• eine Längserstreckungskoordinate 25 im Bereich von 0,10 m bis 0,11 m der Krümmungsradius R 0,095 m betragen kann.
• eine Längserstreckungskoordinate 25 im Bereich von 0,12 m bis 0,14 m der Krümmungsradius R 0,085 m betragen kann,
  eine Längserstreckungskoordinate 25 im Bereich von 0,15 m bis 0,16 m der Krümmungsradius R 0,075 m betragen kann,
• eine Längserstreckungskoordinate 25 im Bereich von 0,17 m bis 0,18 m der Krümmungsradius R 0,065 m betragen und
• eine Längserstreckungskoordinate 25 im Bereich von 0,19 m bis 0,21 m der Krümmungsradius R 0,55 m betragen kann.

If here too the design is such that the _resulting elongation D should remain less than 12%, the radius of curvature R must be chosen so that the in Fig. 5 _resulting in bold formatted resulting strains D. 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 is 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.

A calculation with a finer subdivision of the longitudinal extension coordinates 25 or a continuous calculation can also be carried out. Excessive expansion can also be avoided if larger radii of curvature than the radii of curvature specified in the list above are used for the respective longitudinal extension coordinates 25.

In Fig. 6 Depending on the coordinate 38 of the longitudinal extension coordinate 25 of the guide tube 21 or the hose or (corrugated) pipe 13, on the one hand, the effective tensile force 39 resulting from the centrifugal force (cf. solid line, which is via a spline approximation of the individual tensile forces determined). has been determined). 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 be a maximum of 12%.

As explained previously, the calculation method and the curve shape are according to Fig. 6 presented only as an example and simplifying and possibly falsifying assumptions have been made. As was also mentioned before, the actually used radius of curvature R can differ from the tables or Fig. 6 in 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 is larger in a section adjacent to the rotor axis 7 than in a section further away from the rotor axis 7. It can also be done according to the curve Fig. 6 The following, stepwise or any other adapted courses of the radius of curvature R can be used piece by piece.

wobei A der jeweilige Abstand 42 der Längsabschnitte 41 von der Rotorachse 7 ist und n die Drehzahl der Ausgleichsrotor-Führungseinrichtung 20 in [s^-1] ist. Die auf die Längsabschnitte 41 wirkende Zentrifugalkraft F_z ergibt sich dann über $${\mathrm{F}}_{\mathrm{z}}=\Delta \mathrm{m}{\mathrm{a}}_{\mathrm{z}}.$$

In Fig. 7 A highly simplified schematic representation (for example, neglecting the friction between the connecting strand 12 and the hose or tube 13 as well as the support of the hose or tube 13 radially outwards) is shown for 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 longitudinal sections 41 of equal size, which are distinguished from each other by the addition "-1", "-2". are. 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 with the addition "-1", "-2", .... The centrifugal acceleration a _z acts on each longitudinal section 41, for which applies $${\mathrm{a}}_{\mathrm{e.g}}={\left(2\mathrm{\pi n}\right)}^2\mathrm{A}$$

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 then results from $${\mathrm{F}}_{\mathrm{e.g}}=\Delta \mathrm{m}{\mathrm{a}}_{\mathrm{e.g}}.$$

For each longitudinal section 41, the centrifugal force F _z only leads to a tensile force acting in the direction of the longitudinal extension coordinate with a force component that is dependent on the angle 43 for the respective longitudinal extension coordinate.

während sich für den nächsten Längsabschnitt 41-2 dann entsprechend die Zugkraft F_{Zug, 2} wie folgt ermitteln lässt: $${\mathrm{F}}_{\mathrm{Zug},2}=\Delta \mathrm{m}{\mathrm{4\pi }}^2{\mathrm{n}}^2\left({\mathrm{C}}_3{\mathrm{A}}_3+{\mathrm{C}}_4{\mathrm{A}}_4+\dots \right)$$

usw.For the first longitudinal section 41-1, which is arranged coaxially to the rotor axis 7, in the simplified view chosen here, the tensile force F _{Zug, 1} , which acts on the longitudinal section 41-1, results from the sum of the centrifugal forces generated by the Longitudinal section 41-1 must be held, 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, .... The following applies to the tensile force F _{Zug, 1} , which acts on the longitudinal section 41-1. $${\mathrm{F}}_{\mathrm{Train},1}=\Delta \mathrm{m}{\mathrm{4\pi }}^2{\mathrm{n}}^2\left({\mathrm{C}}_2{\mathrm{A}}_2+{\mathrm{C}}_3{\mathrm{A}}_3+{\mathrm{C}}_4{\mathrm{A}}_4+\dots \right),$$

while for the next longitudinal section 41-2 the tensile force F _{Zug, 2} can then be determined as follows: $${\mathrm{F}}_{\mathrm{Train},2}=\Delta \mathrm{m}{\mathrm{4\pi }}^2{\mathrm{n}}^2\left({\mathrm{C}}_3{\mathrm{A}}_3+{\mathrm{C}}_4{\mathrm{A}}_4+\dots \right)$$

etc.

Here, C describes, on the one hand, the conversion of the centrifugal force acting on the longitudinal section 41 into the force component which acts in the direction of the longitudinal extension coordinate 25. Furthermore, another correction factor can also be taken into account in C, for example as a result of taking friction into account. From the above simplifying consideration it follows that the acting tensile force F _Zug is greatest at the longitudinal section 41-1 and as the distance between the longitudinal sections 41 and the rotor axis 7 increases, the acting tensile force and thus the stress becomes smaller.

Under certain circumstances, a more precise modeling of the acting stresses can be carried out, although the qualitative statement that an increase in fatigue strength can be achieved by increasing the radius of curvature for longitudinal sections 41 adjacent to the rotor axis 7 does not change.

REFERENCE SYMBOL LIST

1

Flow centrifuge

2

Housing

3

boiler

4

wall

5

Rotor chamber

6

rotor

7

Rotor axis

8th

container

9

Blood bag

10

Rotor chamber temperature control circuit

11

Rotor chamber temperature control loop

12

connecting strand

13

hose, pipe

14

Temperature control supply line

15

Temperature control discharge line

16

Connection cable

17

Connection cable

18

End area

19

End area

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

34

End area

35

End area

36

End area

37

End area

38

Distance

39

traction

40

Radius of curvature

41

Longitudinal section

42

Distance

43

angle

Claims (7)

Flow centrifuge (1). a) a rotor (6) with a centrifugation chamber, wherein the rotor (6) can be rotated about a rotor axis (7) at a rotor speed, and b) a connecting line (12) with a connecting line (16; 17), via which a medium can be fed to the centrifugation chamber during operation of the flow centrifuge (1) with rotating rotor (6), and with a connecting line (17; 16), via which a medium can be removed from the centrifugation chamber, c) wherein one end region (18) of the connecting strand (12) is arranged fixed to the housing and the other end region (19) of the connecting strand (12) is rotated with the rotor (6) and d) to avoid twisting of the connecting strand (12), the connecting strand (12) is guided in a compensating rotor guide device (20), which is rotated about the rotor axis (7) at half the rotor speed,
characterized in that e) the compensating rotor guide device (20) has a guide contour (27) whose radius of curvature (32) for a first distance from the rotor axis (7) is larger than the radius of curvature (33) for a second distance from the rotor axis (7), where the first distance is smaller than the second distance. Flow centrifuge (1) according to claim 1, characterized in that the guide contour (27) has a first guide contour section (28) and a second guide contour section (29), wherein a) the first guide contour section (28) has a curvature in a first direction and the second guide contour section (29) has a curvature in a second direction, b) the first guide contour section (28) and the second guide contour section (29) are connected to one another by an intermediate section (31) and/or turning section (30) which is preferably oriented radially to the rotor axis (7), c) the first guide contour section (28) is at a smaller distance from the rotor axis (7) than the second guide contour section (29) and d) a radius of curvature (32) in the first guide contour section (28) is larger than a radius of curvature (33) in the second guide contour section (29) and/or the radius of curvature (32) in the first guide contour section (28) in the direction of a longitudinal extension coordinate (25 ) and becomes smaller as the distance from the rotor axis (7) increases. Flow centrifuge (1) according to claim 1 or 2, characterized in that the connecting strand (12) has a corrugated tube. Flow centrifuge (1) according to one of the preceding claims, characterized in that the radius of curvature (32) in the first guide contour section (28) and/or the radius of curvature (33) in the second guide contour section (29) increases with increasing distance from the rotor axis (7). is continuously getting smaller. Flow centrifuge according to claim 4, characterized in that in the first guide contour section (28) and/or in the second guide contour section (29) a radius of curvature (32; 33) at different or all longitudinal extension coordinates (25) is dimensioned such that a stress on the in the connecting strand (12) guided by the balancing rotor guide device (20) at the longitudinal extension coordinates (25) as a result of an overlay a) a tensile stress on the connecting strand (12) at the respective longitudinal extension coordinate (25), which results as a result of the centrifugal force caused by a longitudinal section of the connecting strand (12) which is arranged radially on the outside of the respective longitudinal extension coordinate (25), and b) a circumferential bending stress on the connecting strand (12) at the respective longitudinal extension coordinate (25), which results from the circumferential bending of the connecting strand (12) corresponding to the radius of curvature (32; 33), is constant over the longitudinal extent or varies by only a maximum of ± 20%, a maximum of ± 15%, a maximum of ± 10% or a maximum of ± 5%. Flow centrifuge (1) according to claim 4 or 5, characterized in that in the first guide contour section (28) and/or in the second guide contour section (29) there is a radius of curvature (32; 33) at different or all longitudinal extension coordinates (25) is dimensioned in such a way that the connecting strand (12) guided in the compensating rotor guide device (20) is stressed at the longitudinal extension coordinates (25) as a result of superimposition a) a tensile stress on the connecting strand (12) at the respective longitudinal extension coordinate (25), which results as a result of the centrifugal force caused by a longitudinal section of the connecting strand (12) which is arranged radially on the outside of the respective longitudinal extension coordinate (25), and b) a circumferential bending stress on the connecting strand (12) at the respective longitudinal extension coordinate, which results from the circumferential bending of the connecting strand (12) corresponding to the radius of curvature (32; 33), is at least a predetermined percentage smaller than a permissible load on the connecting strand (12). Compensating rotor guide device (20) for a flow centrifuge (1) according to one of claims 1 to 6 with a guide tube (21), wherein the guide tube (21) has a guide contour (27) which has a first guide contour section (28) and a second guide contour section (29), where a) the first guide contour section (28) has a curvature in a first direction and the second guide contour section (29) has a curvature in a second direction, b) the first guide contour section (28) and the second guide contour section (29) are connected to one another by an intermediate section (32) which is preferably oriented radially to the rotor axis (7) and/or a turning section (30), c) the first guide contour section (28) is at a smaller distance from the rotor axis (7) than the second guide contour section (29) and d) a radius of curvature (32) in the first guide contour section (28) is smaller than a radius of curvature (33) in the second guide contour section (29) and/or the radius of curvature (32) in the first guide contour section (28) in the direction of the end region (35 ), which faces the second guide contour section (29), becomes smaller.

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