Ultra-high speed rotor

Abstract

This invention provides an improved rotor that can be used in ultracentrifugation applications for the separation of exosomes and other materials having similar physical properties. [Solution] The rotor 10 for the centrifugal separator includes a rotor body 12, a drive hub 20, and a balance ring 16. The rotor body 12 includes an elongated bore 32 extending along its axis of rotation 24 and an upper surface 26 having an annular groove. The drive hub 20 is mounted within the elongated bore 32 and includes a drive portion 138 having a cross-sectional shape complementary to the cross-sectional shape of the elongated bore 32, which applies torque to the rotor body 12 through engagement between the drive portion 138 and the lower bore opening 36 of the rotor body 12. The balance ring 16 is positioned within the annular groove and includes a plurality of apertures 78 formed on its upper surface, each configured to balance the rotor 10 and receive weights 80 by selectively adding weights 80 to one or more of the apertures 78.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of the filing dates of co - pending U.S. Provisional Patent Application No. 63 / 112,018, filed November 10, 2020, and co - pending U.S. Provisional Patent Application No. 63 / 256,014, filed October 15, 2021, the disclosures of which provisional patent applications are hereby incorporated by reference in their entireties.

[0002] (Technical Field) The present invention generally relates to centrifuge rotors, and more particularly to rotors for ultra - centrifugation.

Background Art

[0003] Exosomes are cell - derived vesicles that can transport nucleic acids, lipids, or proteins from one cell to another. Exosomes play an important role in cell - to - cell communication and are essential for the proper functioning of the human body. Exosomes are also associated with certain diseases in addition to their roles in human standard physiology. Due to their roles as cell - to - cell communication agents and their potential in both disease diagnosis and treatment, interest in exosome research has been increasing. For example, exosomes have been studied as therapeutic targets, drug or gene delivery vectors, and cancer markers because they have different secreted components under physiological and pathological conditions.

[0004] Exosomes are a type of extracellular vesicle secreted by most cell types, typically having a diameter of 30-140 nm. Exosomes are usually secreted together with other types of extracellular vesicles, such as apoptotic bodies, which have a diameter of 50-500 nm, and ectosomes, which have a diameter of 30-100 nm. Exosomes can be separated from these other types of extracellular vesicles using centrifugation. However, since these additional extracellular vesicles often have similar physical properties to exosomes (e.g., similar size and density), extremely high gravitational acceleration may be required to isolate exosomes from other cellular secretions commonly found in biological suspensions.

[0005] The amount of gravitational acceleration that can be generated by a centrifuge depends at least in part on the physical properties of the rotor. Non-uniform mass distribution or fine structural defects that are not a problem in conventional centrifuges can cause vibration or malfunction at the rotational speed desired for efficient separation of exosomes.

[0006] Therefore, there is a need for an improved rotor that can be used in ultracentrifugation applications to separate exosomes and other materials with similar physical properties. [Overview of the project]

[0007] The present invention overcomes the aforementioned and other shortcomings and drawbacks of previously known centrifuge rotors for use in ultra-high-speed centrifugal separation. While the present invention is considered in relation to specific embodiments, it will be understood that the present invention is not limited to these embodiments.

[0008] In one embodiment of the present invention, a rotor for use in a centrifuge is provided. The rotor includes a rotor body having a rotating shaft, a top surface, a bottom surface opposite to the top surface, and an elongated bore extending along the rotating shaft between the top and bottom surfaces. The top surface of the rotor body includes a plurality of cavities extending from the top surface into the rotor body, each of which is configured to receive a sample container. The bottom surface of the rotor body includes a lower bore opening communicating with the elongated bore and having a first cross-sectional shape lateral to the rotating shaft. The rotor further includes a drive hub having a drive portion mounted in the elongated bore and having a second cross-sectional shape lateral to the rotating shaft, complementary to the first cross-sectional shape, so that the drive portion of the drive hub applies torque to the rotor body through engagement between the drive portion and the lower bore opening of the rotor body.

[0009] In aspects of the present invention, the first cross-sectional shape and the second cross-sectional shape may each be rectangular.

[0010] In another aspect of the present invention, the rotor body may include an upper bore opening that communicates with an elongated bore, the elongated bore may be cylindrical in cross-section transverse to the axis of rotation between the lower bore opening and the upper bore opening.

[0011] In another aspect of the present invention, the rotor may further include a lid having a central wall portion, a conical wall portion extending upward and outward from the central wall portion, and an annular wall portion extending radially outward from the conical wall portion away from the central wall portion such that the annular wall portion is offset radially and axially from the central wall portion.

[0012] In another aspect of the present invention, the conical wall portion of the lid may be configured to engage with each sample container positioned within its respective cavity when the lid is operably coupled to the rotor.

[0013] In another aspect of the present invention, the upper surface of the rotor body may define an upper recess, and the central wall portion and the conical wall portion of the lid may be received in the upper recess.

[0014] In another aspect of the present invention, the lid may include a lid lifting handle that projects axially upward from the central wall portion of the lid.

[0015] In another aspect of the present invention, the lid lifting handle may include a cylindrical wall and a handle flange projecting radially outward from the free end of the cylindrical wall away from the central wall portion of the lid.

[0016] In another aspect of the present invention, the drive hub may include a cylindrical shaft projecting upward through an elongated bore from the drive portion of the drive hub.

[0017] In another aspect of the present invention, the upper portion of the cylindrical shaft may include a threaded outer surface.

[0018] In another aspect of the present invention, the rotor may further include a cover screw having a lower bore with a threaded inner surface, and a cover screw flange extending radially outward from the lower end of the cover screw. The threaded outer surface of the drive hub may be configured to screw into the threaded inner surface of the lower bore of the cover screw, and the cover screw flange may have a lower surface configured to bias the cover into contact with the rotor body in response to the screwing of the cover screw and the drive hub.

[0019] In another aspect of the present invention, the cylindrical wall of the lid lifting handle may be configured to receive the lid screw flange and to position the lid screw concentrically with the lid lifting handle.

[0020] In another aspect of the present invention, the lower surface of the lid screw flange may include an annular groove, and the rotor may further include an elastic member positioned within the annular groove, which is pressed against the upper surface of the central wall portion of the lid in response to the screwing of the lid screw with the drive hub.

[0021] In another aspect of the present invention, the lower bore opening may include one or more side walls, and the drive portion of the drive hub may each have one or more surfaces that engage with the respective side walls of the lower bore opening, and torque may be applied to the rotor body by the engagement of one or more surfaces with the respective side walls.

[0022] In another embodiment of the present invention, another rotor for use in a centrifuge is provided. The rotor includes a rotor body having a rotating shaft and a top surface with a first annular groove, and a balance ring positioned in the first annular groove. The balance ring includes a top surface and a plurality of apertures formed on the top surface. Each aperture on the top surface of the balance ring is configured to selectively receive a weight.

[0023] In another aspect of the present invention, the rotor body may include a lower surface opposite to its upper surface and an elongated bore extending along the axis of rotation between the upper and lower surfaces of the rotor body, and the rotor may further include a drive hub having a cylindrical shaft mounted within the elongated bore and projecting upward through the elongated bore. The cylindrical shaft may include an upper portion having a threaded outer surface. The rotor may further include a cover screw having a lower bore with a threaded inner surface configured to screw into the threaded outer surface of the drive hub, a cover screw flange extending radially outward from the lower end of the cover screw, a cover including a wall portion extending radially outward and having a second annular groove, and an elastic member positioned within the second annular groove, which is pressed against the upper surface of a balance ring in response to the screwing of the cover screw with the drive hub.

[0024] In another aspect of the present invention, the threaded outer surface may include threads having a large diameter and a small diameter, and the cylindrical shaft may include a protruding end having a small diameter and extending a distance beyond the threads of the threaded outer surface.

[0025] In another aspect of the present invention, the first annular groove may include a shoulder, and the balance ring may include a balance ring flange that projects radially inward and engages with the shoulder.

[0026] In another aspect of the present invention, the rotor body may include circumferential side walls, and the rotor may further include reinforcing members extending around the circumferential side walls.

[0027] In another aspect of the present invention, the reinforcing member may extend around and above the circumferential side wall of the rotor body to define a channel having a first annular groove, and the balance ring may be positioned within the channel.

[0028] In another aspect of the present invention, the circumferential side wall may include a circumferential depression, and the reinforcing member may conform to the circumferential depression.

[0029] In another aspect of the present invention, the balance ring may be operatively coupled to the first annular groove by an adhesive, shrink fitting, or both an adhesive and shrink fitting.

[0030] In another aspect of the present invention, each aperture may be spaced from an adjacent aperture by the same angular distance at each angle.

[0031] In another aspect of the present invention, the plurality of apertures may be arranged in a plurality of aperture groups each including two or more apertures separated by a first angular distance, and each aperture group may be separated from an adjacent aperture group by a second angular distance different from the first angular distance.

[0032] In another aspect of the present invention, the balance ring may further include a plurality of markers on its upper surface, and each marker may be positioned between two aperture groups.

[0033] In another aspect of the present invention, the rotor body may further include a plurality of cavities extending from its upper surface into the rotor body, each of the plurality of cavities may be configured to receive a sample container, and each marker may be radially aligned with a respective cavity.

[0034] In another aspect of the present invention, the rotor may further include at least one weight received by at least one of the apertures.

[0035] In another aspect of the present invention, the at least one weight may be a screw including a threaded outer surface, and each of the apertures may include a threaded inner surface configured to threadably engage the screw.

[0036] In another aspect of the present invention, the screw may have a head and a first length, at least one aperture may have a second length longer than the first length, and the head of the screw may be below the upper surface of the balance ring.

[0037] In another aspect of the present invention, each aperture of a plurality of apertures may be at the same radial distance from the axis of rotation. [Brief explanation of the drawing]

[0038] The accompanying drawings incorporated herein and constituting part of this specification illustrate embodiments of the present invention and, together with the above-mentioned general description of the invention and the following detailed description, serve to illustrate the present invention. [Figure 1] This is a perspective view of a rotor according to an exemplary embodiment of the present invention. [Figure 2] Figure 1 is an exploded perspective view of the rotor, showing the rotor body, balance ring, drive hub, and cover. [Figure 2A] Figure 2 is a perspective view showing additional details of the lid. [Figure 2B] Figure 2 is a top perspective view showing additional details of the rotor body. [Figure 2C] Figure 2 is a bottom perspective view showing additional details of the rotor body and drive hub. [Figure 3] This is a cross-sectional view of the rotor in Figure 1. [Figure 3A] Figure 3 is an exploded cross-sectional view of a portion of the rotor, showing additional details of the cover, balance ring, and rotor body. [Figure 4] This is a top view of the rotor in Figure 1 with the cover removed. [Figure 5] This is a top view of the rotor in Figure 1 with the cover removed. [Figure 6] This is a top view of the rotor in Figure 1 with the cover removed, showing a balance ring according to an alternative embodiment of the present invention. [Figure 6A] Figure 6 is a cross-sectional view of the balance ring. [Figure 7] Figure 6 is a top view of the rotor with the cover removed, showing the balance ring with the weight installed inside the aperture. [Figure 7A] Figure 7 is a cross-sectional view of the balance ring, showing the weights placed in the aperture. [Modes for carrying out the invention]

[0039] Embodiments of the present invention aim to provide a rotor suitable for use in ultracentrifugation.

[0040] Ultracentrifugation separates sample components suspended in a liquid by utilizing differences in particle sedimentation velocities, which can be influenced by particle size, density, and shape. Centrifugal force can be applied stepwise to sequentially separate sample components according to their physical properties. Since sedimentation velocity depends at least partially on particle size, smaller particles can be isolated from larger particles using a series of sequentially increasing centrifugation speeds. For example, to separate cells, cell fragments, and other larger particles from a suspension sample, a relatively low gravitational acceleration (e.g., 300–1,000 × g) may be applied. The remaining supernatant can then be aspirated and subjected to subsequent centrifugation rounds at higher gravitational accelerations, progressively separating smaller particles in each round. To obtain a pellet of the desired material, ultracentrifugation generating high gravitational accelerations (e.g., up to 1,000,000 × g) may be used in later rounds of centrifugation. Density gradient separation using ultracentrifugation can also be used to isolate or purify sample components.

[0041] Embodiments of the present invention include rotors that, compared to conventional rotors, offer improved uniformity of mass distribution with respect to their respective axes of rotation, increased strength, and reduced overall mass. The low vibration levels and high gravitational acceleration (e.g., 200,000 × g at 50,000–60,000 rpm) enabled by these rotors may allow for improved isolation and purification processes for materials suspended in biological fluids, such as cells, exosomes, mitochondria, and other organelles.

[0042] Figures 1 to 5 show a rotor 10 according to an exemplary embodiment of the present invention. As best shown in Figure 2, the rotor 10 includes a rotor body 12, a reinforcing member 14, a balance ring 16, a cover 18, a drive hub 20, and a cover screw 22. The rotor 10 has a rotating shaft 24 and is configured to rotate around it when used in a centrifuge, and the components of the rotor 10 are arranged concentrically around it.

[0043] As best illustrated by Figures 2B and 3, the rotor body 12 may be made of carbon fiber composite or other suitable lightweight and rigid material, and includes an upper surface 26, a lower surface 28, circumferential side walls 30, and an elongated bore 32 passing through the upper surface 26 and the lower surface 28. The elongated bore 32 may be axially aligned with the rotation axis 24 and intersects with an upper recess 34 in the upper surface 26 and a lower bore opening 36 in the lower surface 28 of the rotor body 12. As will be described in more detail below, the lower bore opening 36 may have a horizontal cross-sectional shape keyed to the drive hub 20 to prevent rotation of the rotor body 12 relative to the drive hub 20.

[0044] The upper surface 26 of the rotor body 12 may include an annular surface 38, a central surface 40 recessed axially downward from the annular surface 38, and an annular groove 42. The annular groove 42 may define the outer circumference 44 of the annular surface 38 and the upper edge 46 of the circumferential side wall 30. The annular groove 42 may be defined by an upper rubber 48 and a lower rubber 50 that overlap and define a shoulder 52. The central surface 40 may be connected to the annular surface 38 by a connecting surface 54. The connecting surface 54 may extend axially upward and radially outward from the outer circumference of the central surface 40 to the inner circumference of the annular surface 38. The connecting surface 54 may be oriented so that it faces axially upward and radially inward, and may include a lower portion 56 and an upper portion 58. The upper portion 58 of the connecting surface 54 may be raised above the lower portion 56 in a direction perpendicular to the connecting surface 54.

[0045] The rotor body 12 may further include a plurality of cavities 60, each extending axially downward and radially outward into the rotor body 12 from the lower portion 56 of the connection surface 54. Each cavity 60 may have a central axis perpendicular to the connection surface 54 and may be suitably sized and molded to receive a sample container 62. Each cavity 60 may be configured to hold its respective sample container 62 at an angle, for example, 45 degrees, with respect to the rotation axis 24, in a position and orientation suitable for centrifugation. Each sample container 62 may be configured to hold a certain amount of sample suspension (e.g., 1.5 mL) and may include a cap 64 that seals the sample container 62 when pressed to the closed position. The cap 64 may include a tab 66 configured to facilitate opening of the sample container 62. The cavities 60, sample containers 62, and caps 64 may be configured such that the tab 66 is supported by the upper portion 58 of the connection surface 54 when the sample container 62 is fully inserted into its respective cavity 60. Advantageously, the upper portion 58 of the connecting surface 54 can prevent the high gravitational acceleration generated by centrifugation from causing the cap 64 to deflect, which could potentially break the seal between the cap 64 and the body of the sample container 62 or damage the sample container 62.

[0046] As best illustrated in Figure 3, the reinforcing member 14 may include one or more helical windings extending around and above the circumferential sidewall 30 of the rotor body 12. The inner surface 68 of the reinforcing member 14 may work in cooperation with the annular groove 42 of the rotor body 12 to define a channel 70 in which the balance ring 16 is positioned. The reinforcing member 14 may be formed by a filament winding process followed by a compression molding process using a suitable material such as epoxy-coated carbon fiber. For example, the reinforcing member 14 may be compression-molded onto the rotor body 12 and the balance ring 16 after a layer of resin-coated carbon fiber laminate material has been laid, or after one or more strands of carbon fiber have been wound onto a surface facing the outside of the circumferential sidewall 30.

[0047] To prevent the reinforcing member 14 from moving axially, the circumferential sidewall 30 may include an inwardly tapered portion defining a circumferential recess 72 in the circumferential sidewall 30. The inner surface 68 of the reinforcing member 14 may conform to the circumferential recess 72 so that the reinforcing member 14 resists axial movement relative to the rotor body 12. The reinforcing member 14 may be configured to withstand most of the centrifugal force applied to the rotor 10. A method for forming a reinforcing member of a centrifugal rotor using a filament winding process is described in detail in U.S. Patent No. 8,323,169, issued 4 December 2012, the disclosure of which is incorporated herein by reference in its entirety.

[0048] As best illustrated in Figure 3A, the balance ring 16 may include a body 74 having a rectangular cross-section and a flange 76. The flange 76 may project radially inward from the upper portion 74 of the body of the balance ring 16 and may be configured to engage with the shoulder portion 52 of the rotor body 12. The balance ring 16 may be heated and expanded before being placed on the annular groove 42, and then cooled in place by shrink-fitting to be held in place by the rotor body 12. The balance ring 16 may be placed on the annular groove 42 of the rotor body 12 before the reinforcement 14 is formed so that the reinforcement 14 holds the balance ring 16 in place. Adhesives may also be used to operably bond the balance ring 16 to the surface of the annular groove 42. The adhesive may be used alone or in combination with a shrink spring.

[0049] The balance ring 16 may include a plurality of apertures 78, each configured to receive a weight 80. To balance the rotor 10, one or more weights 80 can be selectively positioned in one or more of the apertures 78 of the balance ring 16. In one embodiment of the present invention, each weight 80 may include a threaded shaft 82 and a head 84. Each aperture 78 may include a threaded bore 86 configured to receive the threaded shaft 82 of the weight 80 and a receptacle 88 (e.g., a countersunk hole, counterbored hole, etc.) configured to receive the head 84 of the weight 80. The receptacle 88 may allow the top of the weight 80 to be flush with or recessed below the upper surface 90 of the balance ring 16 when the weight 80 is fully inserted into the aperture 78.

[0050] As best illustrated by Figures 4 and 5, the balance ring 16 may be positioned at an angle to the rotor body 12 with respect to the rotation axis 24 such that the apertures 78 of the balance ring 16 are positioned symmetrically with respect to the cavities. As a result of this symmetry, each of the two apertures 78 closest to each cavity 60 of the rotor body 12 extends radially outward from the rotation axis 24 and is equally spaced on both sides of a line passing through the central axis of the cavity 60. This angular positioning of the balance ring 16 can provide a ring with an orientation that ensures positional symmetry between the cavities 60 of the rotor body 12 and the apertures 78 of the balance ring 16, with each cavity 60 of the rotor body 12 centered at an angle between the two apertures 78 of the balance ring 16 closest to the cavity 60.

[0051] As best illustrated by Figure 2A, the cover 18 of the rotor 10 may include an annular wall portion 92, a central wall portion 93, and a conical wall portion 94, and may be made of carbon fiber composite, aluminum, or any other suitable low-mass, rigid material. The conical wall portion 94 of the cover 18 may connect the inner edge 95 of the annular wall portion 92 to the outer edge 96 of the central wall portion 93. The conical wall portion 94 may be joined at an obtuse angle to the annular wall portion 92 and the central wall portion 93 of the cover 18 such that the annular wall portion 92 is axially offset from and parallel to the central wall portion 93. The resulting shape of the cover 18 may substantially conform to the shape of the upper surface 26 of the rotor body 12.

[0052] Referring again to Figure 3A and continuing to refer to Figure 2A, the annular wall portion 92 of the lid 18 may include an elastic member 102, for example, a lower surface 98 having an annular groove 100 configured to receive an O-ring. The elastic member 102 may be made of any suitable material (e.g., silicone) and may be configured to engage with the upper surface 90 of the balance ring 16 when the lid 18 is operably coupled to the rotor 10.

[0053] The central wall portion 93 of the lid 18 may include a top surface 104, a central bore 106, and a lid lifting handle 108 projecting axially upward from the top surface 104. The central bore 106 may have the same diameter as the elongated bore 32 of the rotor body 12 so that the bore is axially aligned by the drive hub 20. The lid lifting handle 108 may include a cylindrical wall 109 having an inner surface 110 and a flange 112. The cylindrical wall 109 may be joined to the lid 18 at its lower end. The flange 112 may project radially outward from the upper portion of the lid lifting handle 108 at the free end of the cylindrical wall 109 away from the central wall portion 93 of the lid 18, providing a grip for gripping the rotor 10. This grip may improve the ergonomics of installing and removing the rotor 10 from the centrifuge compared to a rotor without this feature. The inner surface 110 of the cylindrical wall 109 may include a neck 114 adjacent to or near the top surface 104. The neck 114 may have a diameter d1 smaller than the diameter d2 of the main portion of the inner surface 110. The main portion of the inner surface 110 may be joined to the neck 114 by a bevel 116.

[0054] As best illustrated by Figure 2C, the drive hub 20 may include a shaft 120, a flange 122 projecting radially outward from the bottom portion of the shaft 120, and a central bore 124 extending axially into the bottom end of the shaft 120. The central bore 124 of the drive hub 20 may be axially aligned with the rotation axis 24 of the rotor 10, may include a bottom surface 130, and may be configured to receive a centrifuge spindle (not shown). The upper portion 126 of the shaft 120 may be configured to receive a cover screw 22. For this purpose, the upper portion 126 of the shaft 120 may include a threaded outer surface 128 configured to screw into the cover screw 22.

[0055] A portion of the shaft 120 adjacent to and below the threaded outer surface 128 may have a small radius (e.g., an undercut) to provide thread relief. This thread relief ensures that the lower surface 148 of the flange 146 of the cover screw 22 engages with the upper surface 104 of the central wall portion 93 of the cover 18 without interference from the shaft 120 when the cover screw 22 is screwed into the drive hub 20. The upper portion 126 of the shaft 120 may include a projection end 129 at its apex. The projection end 129 may have a diameter approximately the same as the small diameter of the threaded outer surface 128 and may extend beyond the threads of the threaded outer surface 128 for a distance of 1.5 to 2.5 thread widths. The drive hub 20 may be manufactured from a solid billet of metal, for example, using computer numerical control (CNC) machining or any other suitable process.

[0056] Referring again to Figure 3 and continuing to refer to Figure 2C, one or more drive pins 132 may extend axially downward from the bottom surface 130 of the central bore 124 to prevent the drive hub 20 from rotating relative to the spindle. Each drive pin 132 may be configured to engage with the respective receptacle of the centrifuge spindle. Each drive pin 132 may comprise a rod 134 inserted into a bore 136 that extends axially into the bottom surface 130 of the central bore 124. Each bore 136 may be radially offset from the central axis of the central bore 124. This offset may cause the drive pins 132 to experience shear forces in response to the spindle applying torque to the rotor 10 that would be sufficient to cause slippage between the spindle and the drive hub 20 if the drive pins 132 were not present.

[0057] The drive portion 138 of the hub 20 may extend axially upward from the flange 122 and radially outward from the shaft 120. The drive portion 138 of the hub 20 may have a horizontal cross-sectional shape that is keyed to or otherwise complementary to the horizontal cross-sectional shape of the lower bore opening 36 of the rotor body 12. Keying the drive portion 138 to the lower bore opening 36 can prevent the angular position of the rotor body 12 from shifting relative to the drive hub 20 under angular acceleration. For this purpose, the cross-sectional shape of the drive portion 138 may be the same as the cross-sectional shape of the lower bore opening 36, or it may be a different shape that fits within the lower bore opening 36 and has one or more surfaces 139 that engage with corresponding surfaces 141 of the side walls of the lower bore opening 36, or it may be a different shape that is keyed to the cross-sectional shape of the lower bore opening 36.

[0058] For example, the cross-sectional shape of the drive portion 138 may be a polygon (e.g., a square) having the same number of surfaces 139 as the shape of the lower bore opening 36, or more surfaces 139. As an example, in the case of a lower bore opening 36 having a square horizontal cross-section, the drive portion 138 may have a square shape, an octagonal shape, or other cross-sectional shape having one or more surfaces 139 complementary to the surfaces 141 of the lower bore opening 36. The lower bore opening 36 may also include one or more axially aligned channels 143 whose vertices of the surfaces 141 are positioned in a different way to facilitate the insertion of the drive portion 138 of the drive hub 20 into the lower bore opening 36.

[0059] As best illustrated in Figure 3, the cover screw 22 may be made of any suitable material (e.g., aluminum) and may comprise a cylindrical body having an outer surface 140, an upper bore 142, a lower bore 144, and a flange 146 projecting radially outward from the lower end of the cylinder. The flange 146 may have an outer diameter equal to or slightly smaller than the diameter d1 of the neck 114. The bevel 116 may guide the flange 146 into the neck 114 so that the flange 146 is inserted into the cover lifting handle 108 and the cover screw 22 is screwed into the drive hub 20. Thereafter, the neck 114 and the bevel 116 may work in cooperation with the flange 146 to position the cover screw 22 concentrically with the cover 18 and the drive hub 20, thereby aligning the cover 18 with the rotation axis 24 of the rotor 10 during engagement of the cover screw 22 with the drive hub 20. The final alignment between the cover 18 and the rotation axis 24 of the rotor 10 can be defined by the engagement between the shaft 120 of the drive hub 20 and the central bore 106 of the cover 18.

[0060] The flange 146 may include a lower surface 148, which may have an annular groove 150 configured to receive an elastic member 152. The elastic member 152 may be an O-ring or other type of gasket made of a suitable material such as silicone. The elastic member 152 may be pressed against the upper surface 104 of the central wall portion 93 of the lid 18 in response to the tightening of the lid screw 22 on the drive hub 20. Thereafter, the elastic member 152 may bias the lid 18 to operably engage with the rotor 10.

[0061] The cover screw 22 may further include one or more pairs of radially aligned holes 156 on either side of the upper bore 142. The radially aligned holes 156 may be configured to receive a rod or other tool for applying torque to the cover screw 22. Thereafter, the radially aligned holes 156 can facilitate tightening the cover screw 22 to the drive hub 20 and loosening the cover screw 22 from the drive hub 20.

[0062] The lower bore 144 of the cover screw 22 may include a threaded inner surface 158 configured to screw into the threaded outer surface 128 of the drive hub 20. The protruding end 129 of the shaft 120 can facilitate this threaded engagement between the drive hub 20 and the cover screw 22 by providing a clean initiation of engagement between the threaded outer surface 128 of the shaft 120 and the threaded inner surface 158 of the lower bore 144. Screwing the cover screw 22 into the drive hub 20 can bias the cover 18 against at least a portion of the upper surface 26 of the rotor body 12. The cover screw 22 can also bias the cover 18 against the cap 64 of the sample container 62, thereby keeping the cap 64 fully seated on the sample container 62. In this way, the cover 18 can also hold the sample container 62 in a fully seated position within their respective cavities 60 by applying a small force to the surface of each cap 64.

[0063] Figures 6 and 7 show a top view of the rotor 10 without the cover 18, and Figures 6A and 7A show a cross-sectional view of a balance ring 160 according to an alternative embodiment of the present invention. The balance ring 160 may include a body 161 having a rectangular cross-section, a flange 162, and a plurality of apertures 163, each configured to receive a weight 164. Each weight 164 may include a threaded shaft 166 and a head 167 configured to receive a tool, such as a hexagonal key. Each aperture 163 may include a threaded bore 168 configured to receive a weight 164. The threaded bore 168 may be longer than the length of the weight 164, thereby allowing selective adjustment of the position of the weight 164 within the threaded bore 168 by rotating the weight 164 in either a clockwise or counterclockwise direction. The ability to axially adjust the position of each weight 164 relative to the upper surface 170 of the balance ring 160 can facilitate achieving dynamic balance of the rotor 10. The head 167 of the weight 164 may be configured to allow the head 167 to be positioned below the upper surface 170 of the balance ring 160. This may allow the weight 164 to be positioned anywhere within the threaded bore 168. The weight 164 may be fitted with a set screw made from a suitable material, such as 316 stainless steel. Set screws of different lengths may be used to provide weights 164 with different masses. As an example, metric SST-316 set screws of size M4 × 0.7 come in various lengths, providing an excellent map for balancing.

[0064] The aperture 163 may be located at a fixed radial distance from the rotation axis 24 of the rotor 10, and may be arranged in an aperture group 172. For example, the balance ring 160 may include 36 apertures 163 arranged in 12 aperture groups 172, each aperture group 172 having 3 apertures 163. Each aperture 163 may be at a fixed angular distance θ1 (e.g., 7.5 degrees) from an adjacent aperture 163 at an angle within the same aperture group 172. Each aperture group 172 may be at a fixed angular distance θ2 (e.g., 15 degrees) from an adjacent aperture group 172 at an angle. Each aperture group 172 may provide multiple (e.g., 3) balancing locations, and may be located between two adjacent cavities 60. The marker 174 may be located between each aperture group 172 and may include numbers, other markings, etc., to uniquely identify each cavity 60 in the rotor.

[0065] The balance ring 160 can be positioned at an angle to the rotor body 12 with respect to the rotation axis 24 such that the aperture 163 of the balance ring 160 is positioned symmetrically with respect to the cavity 60. As a result of this symmetry, each aperture group 172 closest to each cavity 60 of the rotor body 12 extends radially outward from the rotation axis 24 and is equally spaced on both sides of a line passing through the central axis of the cavity 60. This angular positioning of the balance ring 16 can provide a ring with an orientation that ensures positional symmetry between the cavity 60 of the rotor body 12 and the aperture 163 of the balance ring 160, with each cavity 60 of the rotor body 12 being centered at an angle between the two aperture groups 172 closest to the cavity 60.

[0066] The balance rings 16, 160 may be made of aluminum or any other suitable lightweight rigid material. One or more weights 80, 164 may be selectively placed within their respective apertures 78, 163 to counteract the unbalance of the rotor 10. For example, the weights 80, 164 may be added to align the center of gravity of the rotor 10 with the axis of rotation 24 (i.e., to achieve static balance), or to align the principal axis of the rotor's moment of inertia with the axis of rotation 24 (i.e., dynamic balance), or to allow the rotor 10 to be balanced both statically and dynamically.

[0067] Each of the exemplary embodiments of the rotor 10 described herein includes a certain number of cavities 60, apertures 78, 163, aperture group 172, and spacing; however, it should be understood that embodiments of the present invention are not limited to a certain number of cavities 60, apertures 78, 163, or aperture group 172. It should be further understood that the represented embodiments of apertures 78, 163 are not limited to the arrangements represented in their respective balance rings 16, 160. For example, aperture 163 represented in Figures 6 to 7A may be used in balance ring 16 represented in Figures 3A to 5, and aperture 78 represented in Figures 3A to 5 may be used in balance ring 160 represented in Figures 6 to 7A.

[0068] While various embodiments have been described in considerable detail, illustrating different aspects of the principles of the present invention, these are not intended to limit the scope of the invention to such details or to restrict it in any way. The various features shown and described herein may be used individually or in any combination. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, in its broader embodiments, the present invention is not limited to the specific details, representative apparatus and methods, and exemplary embodiments illustrated and described. Accordingly, deviations from such details can be made without departing from the general concept of the invention.

Claims

[Claim 1] A rotor for use in a centrifugal separator, A rotor body comprising a rotation axis, an upper surface, a lower surface opposite to the upper surface, and an elongated bore extending along the rotation axis between the upper surface and the lower surface, wherein the upper surface of the rotor body includes a plurality of cavities extending from the upper surface into the rotor body, each of the plurality of cavities configured to receive a sample container, and the lower surface of the rotor body includes a lower bore opening communicating with the elongated bore and having a first cross-sectional shape lateral to the rotation axis, A drive hub, which is mounted in the elongated bore and includes a drive portion, the drive portion having a second cross-sectional shape lateral to the rotation axis, complementary to the first cross-sectional shape, such that the drive portion of the drive hub applies torque to the rotor body through engagement between the drive portion and the lower bore opening of the rotor body. Rotor.

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