Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B5/00—Other centrifuges
  • B04B5/04—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers
  • B04B5/0442—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers with means for adding or withdrawing liquid substances during the centrifugation, e.g. continuous centrifugation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
  • B04B9/12—Suspending rotary bowls ; Bearings; Packings for bearings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
  • B04B9/08—Arrangement or disposition of transmission gearing ; Couplings; Brakes

Definitions

• the present invention relates to a centrifuge for continuous flow centrifugation according to the general part of claim 1 and to a method of use of a centrifuge according to claim 15.
• Centrifuges for continuous flow centrifugation and in particular centrifuges for fluidized bed centrifugation, which are of particular interest here, are used for a range of applications in biotechnology, including cell therapy, vaccine production and cell cultivation for recombinant protein production like antibody production.
• the type of continuous centrifuge in focus here comprises a rotor with chambers which are usually single-use chambers that can be fed with media while rotating.
• a force equilibrium between the centrifugal force and a fluid flow in the opposite direction suspends particles of different sizes at different locations in the chambers.
• applications of fluidized bed centrifuges comprise for example cell separation.
• an anti-twisting mechanism is implemented for the tubes leading to the chambers.
• This anti-twisting mechanism is based on the known principle that the chambers may rotate with double the velocity of the tubes without the tubes twisting. Implementing this principle puts a number of constructional restraints on the centrifuge, leading to complex mechanics.
• the known prior art ( EP 4 321 255 A1 ) that builds the basis of the invention is related to a centrifuge according to the general part of claim 1.
• This document also summarizes the general working principle of fluidized bed centrifuges.
• the centrifuge comprises a drum, a rotor and a motor for driving the drum and the rotor, wherein the drum, driven by the motor, rotates around a common rotation axis with a rotational frequency during use of the centrifuge, wherein the rotor is coupled to the drum, wherein due to being coupled to the drum, the rotor, driven by the motor, rotates around the common rotation axis with the double of the rotational frequency, wherein the centrifuge comprises a drive bearing arrangement, wherein the drive bearing arrangement comprises at least two drive roller bearings, wherein the drive roller bearings each comprise an inner race, an outer race and a bearing axis, wherein one of said races is connected to the drum and one of said races is
• Another way of keeping ball bearings lubricated is encasing the ball bearings in a chamber and lubricating the chamber, as for example shown in US 2015/0174539 A1 .
• the ball bearings are located on a rotating drum such that the ball bearings as a whole are subject to centrifugal forces.
• the ball bearings are oriented at an angle to the centrifugal force and the chamber in which the ball bearings are placed is closed at a side in the direction of centrifugal force from the ball bearings, such that lubricant is urged towards the sealed side of the chamber and therefore not lost.
• the invention is based on the problem of improving the known centrifuges such that the lifetime of the known centrifuge is achieved.
• the main realization of the present invention is that in an arrangement as in EP 4 321 255 A1 , high rotational speeds of the drum can lead to a loss of lubricant through the seal of the bearings. That is, even if the seal is connected to an outer race of the bearing and the direction of centrifugal force is towards the outer race of the bearing and therefore towards the sealed side and away from a space between the seal and an inner race of the bearing, lubricant can still leave the bearing. Having identified this problem, a solution has been found in providing a further sealing outside the bearing and thereby catching the released lubricant and keeping it near the bearing.
• the outer wall comprises a ridge connected to the outer wall by a connection providing a sealing-function and extending from the outer wall towards the inner races along the sealing.
• a preferred embodiment according to claim 2 relates to a feeding pipe for the rotor in which tubes may be placed.
• the feeding pipe of this embodiment helps provide an anti-twisting mechanism, however, because the feeding pipe rotates around the rotor, driving the rotor via the motor is mechanically challenging.
• An end of the feeding pipe may define a front side of the centrifuge.
• the centrifuge may comprise a rotor drive train between the motor and the rotor with a drive shaft connected to the drive roller bearings (claim 4).
• the drive shaft extends through the drum such that motor and rotor may be located on different sides of the drum functionally.
• the bearing housing may be mounted onto the drum (claim 5) and the rotor drive shaft may extend completely through the bearing housing (claim 6). The bearing arrangement then may rotate with the feeding pipe, providing a solution to drive the rotor without interference with the feeding pipe.
• the drive bearing arrangement may comprise one or two rings screwed into the bearing housing for exerting an axial preload on the drive roller bearings.
• the ridge may be formed integral with the outer wall, providing for a maximum sealing between the wall and the ridge and a simple production of the bearing housing.
• the ridge may also be formed by one of the rings. Providing a thread and a screwed connection between the bearing housing and the ring that provides sufficient sealing for the lubricant is usually not problematic as the lubricant does not move through most threads in relevant quantities.
• the bearing housing may have two longitudinal sides with holes, it is preferably the case that both comprise a ridge, therefore a further ridge may be provided.
• a space may be provided between the ridge and/or the further ridge and the rotor drive shaft to avoid friction and leave room for mounting the rotor drive shaft (claim 10).
• the ridge is preferably provided at least at the side to which the centrifugal force moves the lubricant, that being a side of the bearing housing furthest away from the common rotation axis (claim 11).
• the ridge may extend around the bearing axis.
• Claim 12 refers to preferred arrangements of the drive roller bearings in relation to the common rotation axis.
• Claim 13 refers to preferred arrangements of the sealing and the ring.
• a space is provided between the ridge and the closest roller bearing such that enough volume to collect the lubricant is provided.
• Another teaching according to claim 15, which is of equal importance, relates to method of use of a proposed centrifuge, wherein the rotor and drum are rotated by the motor.
• Fig. 1 shows as a preferred embodiment a centrifuge 1 for continuous flow centrifugation.
• the centrifuge 1 is here and preferably usable for fluidized bed centrifugation.
• the outer view of Fig. 1 shows a front side of the centrifuge 1 with a closed door 2.
• the centrifuge 1 may comprise an outer housing not shown in Fig. 1 .
• Fig. 2 shows a longitudinal cut through the centrifuge 1 in Fig. 1 along the line marked with II.
• the centrifuge 1 comprises a drum 3, a rotor 4 and a motor 5 for driving the drum 3 and the rotor 4.
• the drum 3, driven by the motor 5, rotates around a common rotation axis A with a rotational frequency during use of the centrifuge 1.
• the rotational frequency here and preferably can be set arbitrarily by the user in a range leading up to for example a g-force of 2000g applied to a medium in the rotor 4.
• the rotor 4 is coupled to the drum 3. Due to being coupled to the drum 3, the rotor 4, driven by the motor 5, rotates around the common rotation axis A with the double of the rotational frequency. It is a known principle that providing a ratio of 1:2 leads to an anti-twisting mechanism for tubes 6 feeding the rotor 4.
• the rotor 4 is preferably coupled mechanically to the drum 3, though a software coupling is conceivable. The mechanical coupling ensures that the rotational frequencies of the drum 3 and the rotor 4 keep the ratio of 1:2 without high precision sensors and software, such that the anti-twisting mechanism works.
• the centrifuge 1 comprises a drive bearing arrangement 7.
• the drive bearing arrangement 7 comprises at least two drive roller bearings 8, here and preferably four ball bearings.
• the drive roller bearings 8 each comprise an inner race 9, an outer race 10 and a bearing axis B.
• the races 9, 10 of the outer ball bearings are visible in more detail in Fig. 4 .
• one of said races 9, 10 is connected to the drum 3 and one of said races 9, 10 is connected to the rotor 4.
• the drive bearing arrangement 7 therefore provides a connection between the drum 3 and the rotor 4 that allows for relative rotation between both.
• the drive roller bearings 8 each comprise a lubricant, in particular grease. At least one of the drive roller bearings 8 comprises a sealing 11 separate from and connected to the outer race 10 and extending towards the inner race 9.
• at least the outer drive roller bearings 8 comprise a sealing 11 at their outer sides. More preferably and also realized here is that each drive roller bearing 8 comprises two sealings 11.
• Such sealings 11 are well known in the art and often clipped onto the outer races 10, a solution usually providing for enough sealing-functionality for usual use cases. It is also known that the sealings 11 usually, as is preferably the case here, do not reach the inner race 9, which would create friction and possibly wear down the sealing 11. The opening between the inner race 9 and the sealing 11 may lead to a loss of lubricant, which however is tolerable and not the focus here.
• the bearing axes B of the drive roller bearings 8 are each located spaced apart from, and in particular parallel to, the common rotation axis A, such that the drive roller bearings 8 rotate around the common rotation axis A.
• the term "spaced apart” here means that the bearing axes B and the common rotation axis A do not intersect at least within the respective roller bearing. Preferably, they do not intersect within the drive bearing arrangement 7, more preferably within the centrifuge 1 and more preferably never.
• the bearing axes B and the common rotation axis A may be parallel.
• the distance between the bearing axis B of each drive roller bearing 8 and the common rotation axis A may be greater than a radius or diameter of the drive roller bearing 8.
• the drive roller bearings 8 may be significantly spaced apart from the common rotation axis A, leading to a strong centrifugal force acting on the drive roller bearings 8 as a whole. That is usually not the case for common uses of roller bearings.
• This centrifugal force leads to a loss of lubricant through the connection of the outer race 10 and the sealing 11.
• the centrifugal force acts on the drive bearing arrangement 7 in a direction pointing downwards. Keeping this direction in mind, in Figs. 3 and 4 the lubricant is forced downwards during rotation of the drum 3.
• the rotating outer race 10 and balls redistribute the lubricant within the drive roller bearings 8, however, some lubricant is pressed through the connection of the outer race 10 and the sealing 11 at the bottom side (outer side from the common rotation axis A) of the drive bearing arrangement 7. This generally happens for all four drive roller bearings 8, however, between two drive roller bearings 8 this is not problematic. At the outsides of the outer drive roller bearings 8 however, the lubricant may be lost.
• the drive bearing arrangement 7 comprises a bearing housing 12.
• the bearing housing 12 comprises an outer wall 13 rotationally fixed to the outer races 10 of the drive roller bearings 8.
• the connection between the outer races 10 and the outer wall 13 may be based on friction as the rotational forces on the outer races 10 will usually be rather low.
• the outer wall 13 comprises a ridge 14 connected to the outer wall 13 by a connection providing a sealing-function and extending from the outer wall 13 towards the inner races 9 along the sealing 11.
• Figs. 2 to 4 show two ridges 14, a ridge 14 and a further ridge 14, on both longitudinal sides 15 of the bearing housing 12.
• Longitudinal sides 15 are the sides along a bearing axis B and preferably common rotation axis A, all of which axes are preferably parallel.
• the ridges 14 provide for a volume to collect the lubricant leaving the drive roller bearings 8 and keeping the lubricant close to the connection between outer race 10 and sealing 11.
• the loss of lubricant from the drive roller bearings 8 is therefore stopped and the lifetime of the drive roller bearings 8 increases greatly.
• the ridge 14 is here and preferably located outwards of one of the outer drive roller bearings 8 in the direction of the roller bearing axis B.
• the centrifuge 1 comprises a feeding pipe 16 for continuously feeding the rotor 4 with a medium for centrifugation, which can be seen in Fig. 2 .
• the feeding pipe 16 may be connected to the drum 3.
• the feeding pipe 16 preferably rotates around the common rotation axis A with the rotational frequency.
• the feeding pipe 16 leads along a back direction 17 of the centrifuge 1 around the rotor 4 and is connected to the drum 3 along a front direction 18 of the centrifuge 1, such that the feeding pipe 16 rotates around the rotor 4 around the common rotation axis A.
• the rotation of the feeding pipe 16 completely envelopes the rotor 4.
• to contact the rotor 4 only elements rotating synchronously with the feeding pipe 16 can be used.
• the drive bearing arrangement 7 for driving the rotor 4 is connected to the drum 3.
• the feeding pipe 16 takes in tubes 6 of a single-use tube set 19 connected to chambers 20 of the single-use tube set 19 and the rotor 4 takes in the chambers 20.
• the anti-twister mechanism aims at not intertwining these tubes 6.
• the chambers 20 may comprise a volume of at least 25 ml, preferably at least 50 ml, and/or, at most 200 ml, preferably at most 100 ml, more preferably exactly 50 ml, per chamber 20.
• the tube 6 set may comprise two or four or six chambers 20.
• the chambers 20 may also have a greater volume for example of 100 ml or 1000 ml.
• the centrifuge 1 may comprise a main shaft 21 defining the common rotation axis A.
• the main shaft 21 is mounted to a centrifuge housing 22, in particular at a side located in the back direction 17 from the drum 3 and the rotor 4, here at a back side 23, though it could also be mounted to a top side at the back of the centrifuge 1 or the like.
• the drum 3 and the rotor 4 are mounted onto the main shaft 21.
• the motor 5 may be mounted onto the centrifuge housing 22, too, here from the outside. A further outer housing is not shown. It can be seen that between the main shaft 21 and the rotor 4 and the drum 3, several main bearings 24 are located.
• the back direction 17 and front direction 18 are defined along the common rotation axis A. In principle, the directions are arbitrary and defined only by their functions.
• the front side may also be an upper side, for example.
• the centrifuge 1 may comprise a rotor drive train 25 between the motor 5 and the rotor 4.
• the rotor drive train 25 comprises a rotor drive shaft 26 connected to one of the races 9, 10 of each drive roller bearing 8.
• the rotor drive shaft 26 is connected, in particular directly, to the inner races 9 of the drive roller bearings 8 and the drum 3 is connected to the outer races 10 of the drive roller bearings 8 via the bearing housing 12. Further elements of the drive train will be explained in the following.
• the rotor drive shaft 26 is visible in a) and b).
• the bearing housing 12 is cut with the components of the rotor drive train 25 and the drive roller bearings 8 removed to allow a view inside the bearing housing 12 and in particular to show one embodiment of the ridge 14.
• the rotor drive train 25 extends through the drum 3 via the rotor drive shaft 26.
• the mechanical coupling of the rotor 4 and the drum 3 is realized here by driving the rotor drive train 25 and the drum 3, via a drum drive train 27, by the same motor 5. It is then a question of gearing to synchronize the speeds with a factor of 1:2.
• the rotor drive train 25 and the drum drive train 27 may comprise gearwheels 28, here belt wheels, in particular toothed belt wheels 29, with different sizes.
• the rotor drive train 25 here and preferably leads to the rotor 4 from the back direction 17 of the centrifuge 1. Further, it is conceivable to connect the races 9, 10 the other way around, the inner races 9 being connected to the drum 3 and the outer races 10 to the rotor 4.
• the rotor drive shaft 26 may be a counter shaft with regard to the main shaft 21.
• connection or a connection between the housing and the drum 3 may be achieved by mounting the bearing housing 12 onto the drum 3.
• the bearing housing 12 is screwed to the drum 3.
• the rotor drive shaft 26 extends completely through the bearing housing 12 from one longitudinal side 15 to another longitudinal side 15 of the bearing housing 12 along at least one of the bearing axes B and the rotor drive train 25 comprises drive elements 30 connected to the rotor drive shaft 26 at both longitudinal sides 15 of the bearing housing 12.
• the drive elements 30 on both sides are belts, in particular tooth belts.
• the rotor drive train 25 here and preferably comprises toothed belt wheels 29 on both longitudinal sides 15 of the bearing housing 12, one of them leading towards the motor 5 and one leading towards the rotor 4, here driving the rotor 4 directly. It can be seen that parts of the rotor drive train 25 rotate together with the feeding tube 6, enabling the rotation of the rotor 4 in spite of the feeding tube 6 enveloping the rotor 4.
• the belts may comprise mechanisms for adjusting the belt tension 31.
• the drive bearing arrangement 7 comprises a ring 32 screwed into the bearing housing 12 exerting an axial preload along at least one of the bearing axis B onto the drive roller bearings 8 ( Fig. 3 b ) and Fig. 4 ).
• the drive bearing arrangement 7 comprises a further ring 33 screwed onto the rotor drive shaft 26 exerting an axial preload along at least one of the bearing axes B onto the drive roller bearings 8. More preferably, the axial preload can be adjusted by adjusting a tightening torque of the ring 32 and/or the further ring 33.
• One of the ring 32 and the further ring 33 may preload only the outer races 10 and the other only the inner races 9.
• the outer races 10 may contact each other and/or be pressed against an outer race ridge 34 of the bearing housing 12.
• the inner races 9 may contact each other and/or be pressed against an inner race ridge 35 of the rotor drive shaft 26.
• the bearing housing 12 may comprise a screw thread 36.
• the rotor drive shaft 26 may comprise a screw thread 36.
• the drive roller bearings 8 are ball bearings. Additionally or alternatively, the drive bearing arrangement 7 may comprise four drive roller bearings 8 and/or the drive roller bearings 8 may be angular ball bearings with an axial preload.
• the inner races 9 or outer races 10 of the angular ball bearings are angled and the respective other races 9, 10 are not angled. It may be the case that the inner races 9 and/or, as here, the outer races 10 of at least two angular ball bearings are angled in different directions (also visible in the enlarged sections in Fig. 4 ).
• the drive roller bearings 8 as ball bearings may be arranged in a TOT arrangement.
• the ridge 14 is formed integral with the outer wall 13, or, that the ridge 14 is formed by the ring 32.
• the drive bearing arrangement 7 comprises a further ridge 14 and the further ridge 14 is also formed integral with the outer wall 13 or by the ring 32.
• one ridge 14 is formed integral with the outer wall 13 ( Fig. 4 on the left) and one ridge 14 is formed by the ring 32 ( Fig. 4 on the right). Which of those is seen as the ridge 14 and which as the further ridge 14 is arbitrary.
• the ridge 14 and the further ridge 14 are located at opposite longitudinal sides 15 of the bearing housing 12. If the ridge 14 is formed by the ring 32, the threaded connection may have the sealing-function simply by a tight fit between the ring 32 and the screw thread 36.
• the ridge 14 and/or the further ridge 14 extends from the outer wall 13 towards the rotor drive shaft 26, leaving a space between the ridge 14 and the rotor drive shaft 26. It may additionally or alternatively be the case that the ridge 14 and/or the further ridge 14 extends from the outer wall 13 towards the inner races 9 along the sealing 11 for at least 5 %, preferably at least 7 %, more preferably at least 10 %, even more preferably at least 15 %, even more preferably at least 20 %, even more preferably at least 30 %, even more preferably at least 40 %, even more preferably at least 50 %, and/or at most 90 %, preferably at most 80 %, of a distance between the outer race 10 and the inner race 9.
• the distance between the outer race 10 and the inner race 9 is measured as the diameter of the balls for ball bearings and as a distance between the contact surfaces for other roller bearings. These distances allow for catching the lubricant and at the same time leave enough room for mounting the rotor drive shaft 26.
• the further ring 33 is located in the space between the ridge 14 and the rotor drive shaft 26.
• the ridge 14 In response to the direction of centrifugal force, the ridge 14 preferably extends from a side of the bearing housing 12 furthest away from the common rotation axis A towards the common rotation axis A. Here and preferably, the ridge 14 extends around at least one of the bearing axes B. This embodiment is easier to produce.
• the bearing axes B may be parallel, in particular identical.
• the common rotation axis A does not pass through the drive roller bearings 8 and/or does not pass through the bearing housing 12.
• the drive roller bearings 8 therefore rotate around the common rotation axis A as a whole.
• connection formed between the bearing housing 12 and the ring 32 by screwing the ring 32 is sealed.
• the ring 32 may be screwed into a sealing-material.
• the sealing 11 may be clipped onto the outer race 10 of the drive roller bearing 8 comprising the sealing 11.
• each drive roller bearing 8 comprises a sealing 11, in particular two sealings 11.
• the ridge 14 is spaced apart from the drive roller bearing 8 closest to the ridge 14 along a direction of the bearing axis B of said drive roller bearing 8.
• a distance between the ridge 14 and the drive roller bearing 8 closest to the ridge 14 along a direction of the bearing axis B is at least 2 %, preferably at least 5 %, of a width of said drive roller bearing 8 and/or at least 0.5 mm, preferably at least 0.8 mm.
• the distance may alternatively or additionally be at most 3 mm, preferably at most 2 mm and/or at most 20 % of a width of said drive roller bearing 8, preferably at most 10 % of a width of said drive roller bearing 8.
• the volume should be large enough but the lubricant should stay close to the drive roller bearings 8.
• Another teaching which is of equal importance relates to a method of use of the proposed centrifuge 1, wherein the rotor 4 and drum 3 are rotated by the motor 5.

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Citations (4)

• 2024
  • 2024-05-31 EP EP24179344.7A patent/EP4656291A1/de active Pending
• 2025
  • 2025-05-28 WO PCT/EP2025/064896 patent/WO2025248037A1/en active Pending

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