Patent Description:
Centrifuge rotors are typically used in laboratory centrifuges to hold samples during centrifugation. While centrifuge rotors may vary significantly in construction and in size, one common rotor structure is the fixed angle rotor having a solid rotor body with a plurality of cell hole cavities distributed radially within the rotor body and arranged symmetrically about an axis of rotation. Samples are placed in the cavities, allowing a plurality of samples to be subjected to centrifugation.

Conventional fixed angle centrifuge rotors may be made from metal or various other materials. However, a known improvement is to construct a centrifuge rotor by a compression molding and filament winding process wherein the rotor is fabricated from a suitable material such as composite carbon fiber. For example, a fixed angle centrifuge rotor may be compression molded from layers of resin-coated carbon fiber laminate material. Examples of composite centrifuge rotors are described in <CIT>.

Because centrifuge rotors are commonly used in high rotation applications where the speed of the centrifuges may exceed hundreds or even thousands of rotations per minute, the centrifuge rotors must be able to withstand the stresses and strains experienced during the high speed rotation of the loaded rotor. During centrifugation, a rotor with samples loaded into the cavities experiences high forces along directions radially outwardly from the cavities and in directions along the longitudinal axes of the cavities, consistent with the centrifugal forces exerted on the sample containers. These forces cause significant stress and strain on the rotor body.

A centrifuge rotor should be able to withstand the forces associated with rapid centrifugation over the life of the rotor. Manufacturers continuously strive to develop centrifuge rotors that provide improved performance in consideration of the dynamic loads experienced during centrifugation, and which address these and other problems associated with conventional rotors.

The present invention overcomes the foregoing and other shortcomings and drawbacks of fixed angle centrifuge rotors heretofore known. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications, and equivalents as may be included within the scope of the appended claims.

According to the present invention, a fixed angle centrifuge rotor is provided comprising the combined features of claim <NUM>.

The pressure plate may include a central bore that is configured to receive a shaft portion of the rotor hub. In one embodiment, the central bore is tapered. The pressure plate may include an external side surface, wherein the external side surface is also tapered.

In an exemplary embodiment, the fixed angle centrifuge rotor includes a first elongate reinforcement extending around at least one exterior surface of the rotor body and at least one exterior surface of the pressure plate along a first path, and a second elongate reinforcement extending around an exterior surface of the first elongate reinforcement along a second path. In one embodiment, the first path may be circular, and the second path may be helical.

The fixed angle centrifuge rotor of the exemplary embodiment may include a lid having a planar lower surface. The rotor body may include a planar upper surface that engages the planar lower surface of the lid. At least one of the planar lower surface of the lid or the planar upper surface of the rotor body may include a pair of annular grooves that are configured to receive a pair of O-rings.

According to one embodiment, the fixed angle centrifuge rotor may include a pressure ring that extends around an exterior surface of the rotor body and is press-fitted to the rotor body. The first elongate reinforcement may extend around at least one exterior surface of the rotor body and at least one exterior surface of the pressure ring along the first path. The second elongate reinforcement may extend around an exterior surface of the first elongate reinforcement along the second path. In one embodiment, the first path may be circular and the second path may be helical.

According to the present invention a method of manufacturing a fixed angle centrifuge rotor according claim <NUM> is provided and comprises the combined features of claim <NUM>.

Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

With reference to <FIG> and <FIG>, an exemplary centrifuge rotor <NUM> according to one embodiment of the present invention is illustrated. The rotor <NUM> includes a rotor body <NUM> and a pressure plate <NUM> fixedly coupled to each other and symmetrical about an axis of rotation R defined by a rotor hub <NUM>, about which samples contained in sample containers <NUM> positioned in the rotor body <NUM> may be centrifugally rotated. The rotor <NUM> also includes a lid <NUM> removably coupled to the rotor hub <NUM> over the rotor body <NUM> via a lid screw <NUM> for assisting in retaining the sample containers <NUM> within the rotor body <NUM> during rotation thereof, for example. As described in greater detail below, first and second elongated reinforcements <NUM>, <NUM> each extend continuously around at least portions of the rotor body <NUM> and pressure plate <NUM>.

Referring now to <FIG>, with continuing reference to <FIG> and <FIG>, the illustrated rotor body <NUM> includes a generally disc-shaped top plate <NUM> and a generally frustoconical bottom sidewall <NUM> extending downwardly and outwardly from the top plate <NUM>. The top plate <NUM> includes an upper surface <NUM>, a lower surface <NUM> (<FIG>), and a first side surface <NUM>, and the bottom sidewall <NUM> includes a second side surface <NUM>. A circular bore <NUM> extends through the top plate <NUM> from the upper surface <NUM> to the lower surface <NUM> for receiving at least a shaft portion of the hub <NUM>, and is configured to be coaxial with the hub <NUM> such that the bore <NUM> may also define the axis of rotation R. In one embodiment, the upper surface <NUM> of the top plate <NUM> is generally flat. The lower surface <NUM> of the top plate <NUM> and an interior surface of the bottom sidewall <NUM> together at least partially define an interior space <NUM> of the rotor body <NUM>. In the embodiment shown, the first side surface <NUM> tapers slightly radially inwardly from the upper surface <NUM> toward the second side surface <NUM>. For example, the first side surface <NUM> may taper radially inwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to a plane parallel to the axis of rotation R. In the embodiment shown, the first and second side surfaces <NUM>, <NUM> are generally smooth. As used herein, the term "generally smooth" to describe the side surfaces <NUM>, <NUM> is intended to describe a surface that does not have a stepped configuration, and is generally free of corners or sharp edges. In this regard, the above-defined term is not intended to define the surface roughness of the surfaces <NUM>, <NUM>. Moreover, the rotor body <NUM> may be formed such that the generally smooth side surfaces <NUM>, <NUM> require no additional machining or finishing prior to the application of the reinforcements <NUM>, <NUM>.

A plurality of tubular cell cup holders <NUM> extend from the lower surface <NUM> of the top plate <NUM> into the interior space <NUM> of the rotor body <NUM> along the bottom sidewall <NUM>. In the embodiment shown, each tubular cell cup holder <NUM> is at least partially defined by the bottom sidewall <NUM> of the rotor body <NUM>, a curved cup holder sidewall <NUM>, and a contoured cup holder bottom wall <NUM> such that each tubular cell cup holder <NUM> has a generally elongated U-shaped cross-section (<FIG>). As shown, each cell cup holder <NUM> has a respective longitudinal axis that is angled radially outwardly relative to the axis of rotation R. In this regard, the bottom sidewall <NUM> of the rotor body <NUM> and the cup holder sidewall <NUM> are each angled radially outwardly relative to the axis of rotation R. For example, the bottom sidewall <NUM> of the rotor body <NUM> and the holder sidewall <NUM> may each be angled radially outwardly relative to the axis of rotation R by between approximately <NUM>° and approximately <NUM>°, such that each cup holder <NUM> is angled radially outwardly relative to the axis of rotation R by between approximately <NUM>° and approximately <NUM>°. In the embodiment shown, a first step <NUM> is provided between the bottom wall <NUM> and the cup holder sidewall <NUM>, and a second step <NUM> is provided between the bottom wall <NUM> and the bottom sidewall <NUM> of the rotor body <NUM>, the purposes of which are described in greater detail below. Also, a pair of reinforcing flanges <NUM>, <NUM> (<FIG>) extends between each cup holder sidewall <NUM> and the bottom sidewall <NUM> to assist in strengthening the rigidity of the tubular cell cup holders <NUM>.

The rotor body <NUM> also includes a plurality of tubular cell hole cavities <NUM> each extending from the upper surface <NUM> of the top plate <NUM> toward the bottom wall <NUM> of a respective cell cup holder <NUM> such that each tubular cavity <NUM> opens to an exterior of the rotor body <NUM> via an opening <NUM> in the upper surface <NUM> and is closed off from the interior space <NUM> of the rotor body <NUM> by the sidewall <NUM> and bottom wall <NUM> of the cup holder <NUM>. As shown, each tubular cavity <NUM> has a longitudinal axis that is angled radially outwardly relative to the axis of rotation R in a manner similar to the corresponding cell cup holder <NUM>. In this regard, each tubular cavity <NUM> and/or corresponding cell cup holder <NUM> defines a central longitudinal axis L that is angled relative to the axis of rotation R.

In various embodiments, each central longitudinal axis L may be angled relative to the axis of rotation R. In various embodiments, the angle may be between about <NUM> to about <NUM> degrees. In some embodiments, the angle may be between about <NUM> to about <NUM> degrees for applications where increased rates of rotation and/or cooling efficiency are desirable. In some embodiments, the angle may be between about <NUM> to about <NUM> degrees for applications where increased separation efficiency is desirable. In some embodiments, lower volumetric capacities employ higher angles for increased separation. In some embodiments, higher volumetric capacities employ lower angles which may reduce the overall size of the rotor and, thereby, increase cooling efficiency by reducing frictional forces. Generally, increased angles may reduce cooling efficiency while increasing separation capacity and reduced angles may increase cooling efficiency while decreasing separation capacity.

Each of the cavities <NUM> is suitably sized and shaped to at least receive therein one of the sample containers <NUM> for centrifugal rotation of the containers <NUM> about the axis of rotation R. A tapered annular recess <NUM> is provided at the periphery of each of the cavities <NUM> in the top plate <NUM> and/or respective holder <NUM> generally proximate to the respective opening <NUM>. Each recess <NUM> is tapered radially outwardly from a position distal from the opening <NUM> toward a position proximate to the opening <NUM> to define a ledge <NUM>, the purpose of which is described below. For example, each recess <NUM> may taper radially outwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to a plane parallel to the respective central longitudinal axis L. In the embodiment shown, eight cell cup holders <NUM> and corresponding cell hole cavities <NUM> are provided for receiving eight sample containers <NUM>. However, any suitable number of cell cup holders <NUM> and/or cell hole cavities <NUM> may be used.

As used herein, the term "tubular" refers to any suitable cross-sectional shape, including for example and not limited to rounded shapes (e.g., oval, circular or conical), quadrilateral shapes, regular polygonal or irregular polygonal shapes, or any other suitable shape. Accordingly, this term is not intended to be limited to the generally circular cross-sectional profile of the exemplary tubular holders <NUM> and cavities <NUM> illustrated in the figures.

In one embodiment, the rotor body <NUM>, including the top plate <NUM>, bottom sidewall <NUM>, and/or holders <NUM>, is constructed of carbon fiber material. For example, the rotor body <NUM> may be compression molded from layers of resin-coated carbon fiber laminate material.

As best shown in <FIG> and <FIG>, a cell core or cup <NUM> is positioned within each of the cavities <NUM>. Each cell cup <NUM> includes a tubular wall <NUM> defining a compartment <NUM> for receiving the respective sample container <NUM> via an opening <NUM> of the cup <NUM>. In the embodiment shown, a tapered annular projection <NUM> is provided on the outer periphery of each of the cell cups <NUM> generally proximate to the cup opening <NUM>. Each projection <NUM> is tapered radially outwardly from a position distal from the cup opening <NUM> toward a position proximate to the cup opening <NUM> to define a stop surface <NUM>. For example, each projection <NUM> may taper radially outwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to the tubular wall <NUM>. The stop surface <NUM> is configured to operatively engage with the ledge <NUM> of the corresponding cavity <NUM> to assist in preventing the cell cup <NUM> from becoming dislodged from the cavity <NUM>, such as during centrifugation.

In one embodiment, the cell cups <NUM> are constructed of a homogeneous material compared to that of the rotor body <NUM> (which is typically a composite material). For example, the cell cups <NUM> may be constructed of a metallic material, such as titanium. In addition or alternatively, the cell cups <NUM> may be constructed of ceramics. The cell cups <NUM> may be co-molded to the rotor body <NUM> or may be inserted into the cavities <NUM> after construction of the rotor body <NUM>. In the latter case, the projections <NUM> may be eliminated to allow the cell cups <NUM> to be inserted into the cavities <NUM> unimpeded.

The illustrated centrifuge rotor <NUM> includes eight cavities <NUM> and respective cell cups <NUM> for receiving eight sample containers <NUM> each having a capacity of <NUM>, such that the centrifuge rotor <NUM> has a sample capacity of <NUM> x <NUM>. However, the centrifuge rotor <NUM> may have any other suitable sample capacity including but not limited to those described below with respect to <FIG> and <FIG>.

The illustrated pressure plate <NUM> is generally disc-shaped and includes, in one embodiment, a generally flat upper surface <NUM>, radially inner and outer lower surfaces <NUM>, <NUM>, and a generally smooth tapered side surface <NUM>. The upper surface <NUM> and radially inner low surface <NUM> may be spaced apart from each other to define a maximum thickness of the pressure plate <NUM>. For example, the pressure plate <NUM> may have a maximum thickness of between approximately <NUM> inch and approximately <NUM> inch. A tapered bore <NUM> extends through the pressure plate <NUM> from the upper surface <NUM> to the radially inner lower surface <NUM> for receiving at least a shaft portion of the hub <NUM> and is configured to be coaxial with the hub <NUM> such that the bore <NUM> may also define the axis of rotation R. In the embodiment shown, the bore <NUM> tapers radially outwardly from the upper surface <NUM> toward the radially inner lower surface <NUM>. For example, the bore <NUM> may taper radially outwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to the axis of rotation R. In the embodiment shown, the side surface <NUM> tapers radially inwardly from the upper surface <NUM> toward the radially outer lower surface <NUM>. For example, the side surface <NUM> may taper radially inwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to a plane parallel to the axis of rotation R. The illustrated pressure plate <NUM> includes an annular shelf <NUM> (<FIG>) provided at the periphery of the upper surface <NUM> for receiving a bottom portion of the bottom sidewall <NUM> of the rotor body <NUM>.

As best shown in <FIG>, a plurality of circumferentially-spaced depressions <NUM> are provided in the upper surface <NUM> of the pressure plate <NUM> and are each configured to receive and engage, in abutting relationship, a respective one of the cup holders <NUM> of the rotor body <NUM>, such as during high-speed rotation of the rotor <NUM>. In this regard, the depressions <NUM> are each suitably shaped or configured so as to contact a lower portion of the respective holder <NUM>, such as the bottom wall <NUM> and a portion of the sidewall <NUM> thereof. Each of the illustrated depressions <NUM> includes a contoured bottom surface <NUM> configured to fully envelop and engage the bottom wall <NUM> of the respective holder <NUM> and a curved side surface <NUM> configured to engage the sidewall <NUM> of the holder <NUM>. For example, the side surface <NUM> may be angled relative to the axis of rotation R by between approximately <NUM>° and approximately <NUM>°. A first ledge <NUM> is provided between the bottom surface <NUM> and the side surface <NUM> for engaging the first step <NUM> of the respective cup holder <NUM> and a second ledge <NUM> is provided between the bottom surface <NUM> and the shelf <NUM> of the pressure plate <NUM> for engaging the second step <NUM> of the cup holder <NUM>, such that cooperation between the steps <NUM>, <NUM> and respective ledges <NUM>, <NUM> may assist in locating and/or maintaining a desired position of the rotor body <NUM> relative to the pressure plate <NUM>. In the embodiment shown, eight depressions <NUM> are provided corresponding to the eight holders <NUM>. However, any suitable number of depressions <NUM> may be used.

As best shown in <FIG> and <FIG>, the radially inner and outer lower surfaces <NUM>, <NUM> are offset from each other to define an outwardly-facing step <NUM>. As shown, the radially inner lower surface <NUM> is generally flat and the radially outer lower surface <NUM> is generally curved upwardly from the step <NUM> toward the side surface <NUM> of the pressure plate <NUM> in a generally convex manner. A plurality of circumferentially-spaced bores <NUM> are provided in the radially inner lower surface <NUM> of the pressure plate <NUM> and are each configured to receive a respective pin <NUM> for operatively coupling the pressure plate <NUM> to the hub <NUM>. In one embodiment, three bores <NUM> may be provided and may be circumferentially spaced apart from each other by approximately <NUM>°. However, any suitable number of bores <NUM> may be used at any suitable spacing.

In one embodiment, the pressure plate <NUM> is constructed of carbon fiber material. For example, the pressure plate <NUM> may be compression molded from layers of resin-coated carbon fiber laminate material.

As best shown in <FIG> and <FIG>, the pressure plate <NUM> operatively couples to the bottom sidewall <NUM> and/or cell cup holders <NUM> of the rotor body <NUM> to close off the interior space <NUM> of the rotor <NUM> and to at least partially define the bottom of the rotor <NUM>. Notably, the pressure plate <NUM> is operatively coupled to the bottom walls <NUM> of the cup holders <NUM> to support the cup holders <NUM> during high-speed rotation of the rotor <NUM>, thereby providing structural integrity and minimizing the likelihood of failure of the rotor <NUM>. In use, when the rotor <NUM> is spun, the hub <NUM> applies torque directly to the pressure plate <NUM> via the pins <NUM>, and the pressure plate <NUM> applies torque directly to the cup holders <NUM> and the rotor body <NUM> via the engagement between the depressions <NUM> and the bottom portions of the respective cup holders <NUM>. More particularly, the pressure plate <NUM> may be the primary or only transfer mechanism of torque to the cup holders <NUM> and the rotor body <NUM> from the hub <NUM>. To this end, coupling between the pressure plate <NUM> and the rotor body <NUM> may be such that the pressure plate <NUM> exerts pressure against each of the bottom walls <NUM>, thereby providing the required support. The substantial contact of the depressions <NUM> with the bottom portions of the cup holders <NUM> facilitates minimizing the possibility of concentrating stresses associated with high-speed rotation on the pressure plate <NUM>.

Coupling between the pressure plate <NUM> and rotor body <NUM> may be facilitated by compression-molding of the pressure plate <NUM>, bottom sidewall <NUM>, and holders <NUM> with one another to thereby yield a unitary structure. Those of ordinary skill in the art will readily appreciate that the illustrated coupling between the pressure plate <NUM> and rotor body <NUM> is exemplary rather than intended to be limiting, insofar as variations in the type of coupling between these components are also contemplated. For example, the pressure plate <NUM> and rotor body <NUM> may additionally or alternatively be coupled to each other via an adhesive. Such coupling may further be facilitated by the reinforcements <NUM>, <NUM>, as described below.

As best shown in <FIG>, <FIG> and <FIG>, a pressure ring <NUM> is positioned over the rotor body <NUM> and, more particularly, over the cell cup holders <NUM> to assist in strengthening the rotor body <NUM>. For example, the pressure ring <NUM> may be press-fitted to the rotor body <NUM> around the cell cup holders <NUM>, such as against the bottom sidewall <NUM> of the rotor body <NUM>. The illustrated pressure ring <NUM> has a generally triangular cross-section and is configured to be coaxial with the hub <NUM> such that the pressure ring <NUM> may also define the axis of rotation R. In this regard, the pressure ring <NUM> includes a radially outer surface <NUM> and a radially inner surface <NUM> intersecting each other at one end and spaced apart from each other at the other end by an upper surface <NUM>. In the embodiment shown, a radius <NUM> is provided between the radially outer surface <NUM> and the upper surface <NUM> to provide a smooth transition therebetween. The radially inner surface <NUM> is inclined at an angle relative to the axis of rotation R in a manner similar to the angling of the bottom sidewall <NUM> of the rotor body <NUM> relative to the axis of rotation R to match the bottom sidewall <NUM>. For example, the radially inner surface <NUM> may be angled relative to the axis of rotation R by between approximately <NUM>° and approximately <NUM>°. In this manner, substantially the entire radially inner surface <NUM> may be capable of operatively engaging the bottom sidewall <NUM> of the rotor body <NUM> when the pressure ring <NUM> is press-fitted to the rotor body <NUM>. As shown, the pressure ring <NUM> may be configured to be press-fitted to the rotor body <NUM> at or near a lower portion of the bottom sidewall <NUM>, which may be the location of the rotor body <NUM> at which maximum pressure occurs during centrifugation. In this regard, the pressure ring <NUM> may define a lower inner diameter generally equal to a lower outer diameter of the bottom sidewall <NUM>, and may define an upper inner diameter generally equal to an upper outer diameter of the bottom sidewall <NUM>. In the embodiment shown, the radially outer surface <NUM> of the pressure ring <NUM> tapers radially inwardly from the upper surface <NUM> toward the intersection of the outer surface <NUM> with the inner surface <NUM> in a manner similar to the tapering of the side surface <NUM> of the pressure plate <NUM> to provide a smooth transition therebetween when the pressure ring <NUM> is press-fitted to the rotor body <NUM>. For example, the radially outer surface <NUM> may taper radially inwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to a plane parallel to the axis of rotation R.

In one embodiment, the pressure ring <NUM> is constructed of a homogenous material. The pressure ring <NUM> may be constructed of a relatively hard material compared to that of the rotor body <NUM> and/or pressure plate <NUM>. For example, the pressure ring <NUM> may be constructed of a metallic material, such as titanium. In addition or alternatively, the pressure ring <NUM> may be constructed of ceramics.

As described above, in one embodiment, the coupling between the pressure plate <NUM> and rotor body <NUM> may further be facilitated by the first and/or second reinforcements <NUM>, <NUM>, which may be applied by winding (e.g., helically winding and/or circularly winding) one or more continuous strands of high strength fiber such as a single tow or strand of carbon fiber (e.g. a resin-coated carbon fiber) around the exterior surfaces of the rotor body <NUM> and/or pressure plate <NUM>, for example. Especially when the fiber is resin coated, after compression-molding (i.e., wherein heat and pressure are applied), the pressure plate <NUM> and rotor body <NUM> become a unitary structure. In a specific embodiment, making of the rotor <NUM> may include curing a resin-coated carbon fiber tow or strand of reinforcement such that the strand becomes integral with the rotor body <NUM> and/or the pressure plate <NUM>.

The illustrated first reinforcement <NUM> includes a first strand of material <NUM> circularly wound around at least portions of the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM>. The first strand <NUM> may be, for example, a carbon fiber strand or filament. The first strand or filament <NUM> may be a composite material of carbon fiber and resin and/or a thermoset coated fiber that, at the conclusion of the winding process, is cured so as to be integrally formed with the rotor body <NUM> and pressure plate <NUM>, for example. Alternatively, various other high-tensile, high-modulus materials, such as glass fiber, synthetic fiber such as para-aramid fiber (e.g., Kevlar®), thermoplastic filament such as ultra high molecular weight polyethylene, metal wire, or other materials suitable for reinforcing the rotor body <NUM> and pressure plate <NUM> may be used instead of carbon fiber. Any such materials may be used as a single continuous filament or as multiple filaments, and many such materials can be applied with a resin coating which can be set in a manner analogous to the setting of resin-coated carbon fiber. The first reinforcement <NUM> may comprise a single fiber tow, multiple fiber tows or unidirectional tape in various alternative embodiments.

In the embodiment shown, especially in <FIG>, the first strand <NUM> is wound around the first and second outer surfaces <NUM>, <NUM> of the rotor body <NUM> along a generally circular reinforcement path. For example, the first strand <NUM> may be wound around the portion of the outer surfaces <NUM>, <NUM> remaining exposed when the pressure ring <NUM> is press-fitted over the bottom sidewall <NUM> of the rotor body <NUM>. The first strand <NUM> is also wound around the radially outer surface <NUM> of the pressure ring <NUM> and around the side surface <NUM> of the pressure plate <NUM> along the same generally circular reinforcement path.

The first strand <NUM> may be wound upon the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM> by rotating the assembled rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM> about the axis of rotation R while applying the first strand <NUM> along the desired path, for example. The first strand <NUM> may be wound repeatedly around the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM> along the reinforcement path. This repeated winding of the strand <NUM> around the respective surfaces <NUM>, <NUM>, <NUM>, <NUM> yields a plurality of layers of material covering the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM> that thereby define the first reinforcement <NUM>. As shown, the first reinforcement <NUM> defines a radially inner surface <NUM> which may conform to the outer surfaces <NUM>, <NUM>, <NUM>, <NUM> of the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM>, and defines an outer surface <NUM> which may be generally smooth.

Interaction of the inner surface <NUM> of the first reinforcement <NUM> with the upper surface <NUM> of the pressure ring <NUM> may effectively lock the pressure ring <NUM> against the rotor body <NUM>. Interaction of the inner surface <NUM> of the first reinforcement <NUM> with the tapered first outer surface <NUM> of the top plate <NUM>, the tapered outer surface <NUM> of the pressure plate <NUM>, and/or the tapered outer surface <NUM> of the pressure ring <NUM> may assist in preventing or inhibiting axial displacement of the first reinforcement <NUM> relative to the rotor body <NUM>, pressure plate <NUM>, and/or pressure ring <NUM>, such as during centrifugation. For example, each of the tapered surfaces <NUM>, <NUM>, <NUM> may prevent or inhibit axial displacement of the first reinforcement <NUM> in an upward direction.

The illustrated second reinforcement <NUM> includes a second strand of material <NUM> helically wound around at least portions of the rotor body <NUM>, pressure plate <NUM>, lid <NUM>, and pressure ring <NUM>. In the embodiment shown, the second strand <NUM> is helically wound around the outer surface <NUM> of the first reinforcement <NUM> and is thereby radially spaced apart from portions of the rotor body <NUM>, pressure plate <NUM>, and pressure ring <NUM>. The second strand <NUM> may be, for example, a carbon fiber strand or filament. The second strand or filament <NUM> may be a composite material of carbon fiber and resin and/or a thermoset coated fiber that, at the conclusion of the winding process, is cured so as to be integrally formed with the rotor body <NUM>, pressure plate <NUM>, and first reinforcement <NUM>, for example. Alternatively, various other high-tensile, high-modulus materials, such as glass fiber, synthetic fiber such as para-aramid fiber (e.g., Kevlar®), thermoplastic filament such as ultra high molecular weight polyethylene, metal wire, or other materials suitable for reinforcing the rotor body <NUM> and pressure plate <NUM> may be used instead of carbon fiber. Any such materials may be used as a single continuous filament or as multiple filaments, and many such materials can be applied with a resin coating which can be set in a manner analogous to the setting of resin-coated carbon fiber. The second reinforcement <NUM> may comprise a single fiber tow, multiple fiber tows or unidirectional tape in various alternative embodiments.

In the embodiment shown, the second strand <NUM> is wound around the outer surface <NUM> of the first reinforcement <NUM> along a generally helical reinforcement path. The second strand <NUM> is also wound around the radially outer lower surface <NUM> of the pressure plate <NUM> to the outwardly facing step <NUM> of the pressure plate <NUM> along the same generally helical reinforcement path, and is also wound around at least a portion of the lid <NUM> along the same generally helical reinforcement path. As discussed below, the lid <NUM> is removably seated on the rotor body <NUM> and on the second reinforcement <NUM>. The outwardly facing step <NUM> of the pressure plate <NUM> is positioned radially inwardly of the central longitudinal axes L of the cell cup holders <NUM>, such that the second strand <NUM> extends along the lower surface <NUM> of the pressure plate <NUM> radially inwardly relative to the central longitudinal axes L of the cell cup holders <NUM>. The outwardly facing step <NUM> of the pressure plate <NUM> is also positioned radially inwardly relative to the bottom walls <NUM> of the cell cup holders <NUM>, such that the second strand <NUM> also extends along the lower surface <NUM> of the pressure plate <NUM> radially inwardly relative to the bottom walls <NUM> of the cell cup holders <NUM>. By extending radially inwardly relative to the bottom walls <NUM> of the cell cup holders <NUM>, the second reinforcement <NUM> is better able to resist centrifugal forces (or the components thereof) which occur in an axial direction, as described in <CIT>.

The second strand <NUM> may be wound upon the pressure plate <NUM>, lid <NUM>, and first reinforcement <NUM> by rotating the assembled rotor body <NUM>, pressure plate <NUM>, lid <NUM>, and first reinforcement <NUM> about the axis of rotation R while applying the strand <NUM> along the desired path, for example. The second strand <NUM> may be wound repeatedly around the pressure plate <NUM>, lid <NUM>, and first reinforcement <NUM> along the reinforcement path. This repeated winding of the strand <NUM> yields a plurality of layers of material covering the pressure plate <NUM>, lid <NUM>, and first reinforcement <NUM> that thereby define the second reinforcement <NUM>. In one embodiment, the second strand <NUM> may be applied in a manner similar to that described in <CIT>.

The illustrated rotor hub <NUM> includes an elongate axle <NUM> extending axially from a head <NUM>. The axle <NUM> is sized and shaped to extend through the bores <NUM>, <NUM> of the rotor body <NUM> and pressure plate <NUM> with a close fit therebetween, and includes a threaded end <NUM> distal from the head <NUM> and a tapered end <NUM> proximate to the head <NUM>. The threaded end <NUM> is configured to threadably engage with the lid screw <NUM> for removably coupling the lid <NUM> to the rotor hub <NUM> over the rotor body <NUM>. The tapered end <NUM> tapers radially outwardly toward the head <NUM> to match the tapering of the bore <NUM> of the pressure plate <NUM>, such that interaction between the tapered end <NUM> and the tapered bore <NUM> may assist in removably securing the rotor hub <NUM> to the pressure plate <NUM>. For example, the tapered end <NUM> may taper radially outwardly at an angle of between approximately <NUM>° and approximately <NUM>° relative to the axis of rotation R.

The head <NUM> of the rotor hub <NUM> includes a plurality of circumferentially-spaced threaded bores <NUM>, each configured to threadably receive one of the pins <NUM> for operatively coupling the pressure plate <NUM> to the hub <NUM>. In the embodiment shown, three threaded bores <NUM> are provided and are circumferentially spaced apart from each other by approximately <NUM>° to correspond with the bores <NUM> of the pressure plate <NUM>. However, any suitable number of bores <NUM> may be used at any suitable spacing. Two or more blind bores <NUM> are provided in a bottom side of the rotor hub <NUM> for receiving respective pins of a centrifuge spindle (not shown) to operatively couple the rotor hub <NUM> to the centrifuge spindle. A central recess <NUM> provided in a bottom side of the rotor hub <NUM> may also receive a portion of the centrifuge spindle, such as to assist in stabilizing the rotor hub <NUM> during rotation. In the embodiment shown, the head <NUM> of the rotor hub <NUM> is positioned radially inwardly relative to the outwardly facing step <NUM> of the pressure plate <NUM> and spaced apart therefrom such that the head <NUM> is also positioned radially inwardly relative to and spaced apart from the second reinforcement <NUM>.

In one embodiment, the rotor hub <NUM> is constructed of a relatively hard material compared to that of the rotor body <NUM> and/or pressure plate <NUM>. For example, the rotor hub <NUM> may be constructed of a metallic material, such as titanium.

The illustrated lid <NUM> is generally disc-shaped and includes an upper surface <NUM>, a lower surface <NUM>, and an annular flange <NUM> defining a peripheral recess <NUM> for receiving a portion of the second reinforcement <NUM>. The lower surface <NUM> is generally flat and has a cross dimension generally similar to that of the upper surface <NUM> of the top plate <NUM> of the rotor body <NUM>, such that substantially the entire upper surface <NUM> of the top plate <NUM> may be capable of operatively engaging the lower surface <NUM> of the lid <NUM> when the lid <NUM> is removably coupled to the rotor hub <NUM> over the rotor body <NUM>. A bore <NUM> extends through the lid <NUM> from the upper surface <NUM> to the lower surface <NUM> for receiving at least a portion of the hub <NUM>, such as the axle <NUM>.

First and second annular grooves <NUM>, <NUM> are provided in the lower surface <NUM> for receiving first and second O-rings <NUM>, <NUM>, respectively. As shown, the first and second annular grooves <NUM>, <NUM> and first and second O-rings <NUM>, <NUM> may each have a generally rectangular cross-section. The first and second annular grooves <NUM>, <NUM> are radially spaced apart from each other by a distance greater than a cross dimension of the openings <NUM> in the upper surface <NUM> of the top plate <NUM> of the rotor body <NUM>. For example, the first annular groove <NUM> may be configured to be radially inward of the openings <NUM> and the second annular groove <NUM> may be configured to be radially outward of the openings <NUM> when the lid <NUM> is removably coupled to the rotor hub <NUM> over the rotor body <NUM>. In this manner, the O-rings <NUM>, <NUM> may be capable of providing a fluid-tight seal between the lid <NUM> and the rotor body <NUM> both radially inwardly of and radially outwardly of the openings <NUM>. The interface between the flat lower surface <NUM> of the lid <NUM> and the flat upper surface <NUM> of the top plate <NUM> may assist in providing such a fluid-tight seal to prevent samples from inadvertently escaping from the respective sample containers <NUM> as a result of rotation, evaporation, or any other event which may cause at least portions of the samples to move toward the lid <NUM>.

In one embodiment, the lid <NUM> is constructed of carbon fiber material. For example, the lid <NUM> may be compression molded from layers of resin-coated carbon fiber laminate material.

Once the rotor body <NUM> and pressure plate <NUM> are seated on the rotor hub <NUM>, the lid <NUM> of the rotor <NUM> may be removably coupled to the rotor hub <NUM> over the rotor body <NUM> via the lid screw <NUM>. In this regard, the lid screw <NUM> includes a threaded bore <NUM> which threadably receives the threaded end <NUM> of the axle <NUM> of the rotor hub <NUM>. The illustrated lid screw <NUM> also includes a lower annular flange <NUM> configured to cover at least a central portion of the lid <NUM>. The lid screw <NUM> may be tightened against the lid <NUM> via a tool rod (not shown), for example. When removably coupled to the rotor hub <NUM> over the rotor body <NUM> via the lid screw <NUM>, the lid <NUM> blocks access to the sample containers <NUM> held in the cavities <NUM>, such as during high speed rotation. The centrifuge spindle may then be actuated to drive the rotor <NUM> into high-speed, centrifugal rotation.

In one embodiment, the rotor body <NUM> and pressure plate <NUM> may be seated on the rotor hub <NUM>, or on a tool similar to the rotor hub <NUM>, during compression molding of the rotor body <NUM> and/or pressure plate <NUM>, and/or during winding of the first and/or second reinforcements <NUM>, <NUM>, to assist in locating and/or maintaining a desired position of the rotor body <NUM> relative to the pressure plate <NUM>, for example. Similarly, the lid <NUM> may be removably coupled to the rotor body <NUM> (or tool) during winding of at least the second reinforcement <NUM>, to assist in ensuring that a portion of the second reinforcement <NUM> is received within the peripheral recess <NUM> of the lid <NUM>. During centrifugation, the first and second windings <NUM>, <NUM> may contribute to the strength of the rotor <NUM> and thereby assist in maintaining the structural integrity of the rotor <NUM> under high stresses and strains. For example, the first reinforcement <NUM> may primarily assist in counteracting radially outwardly directed forces and the second reinforcement <NUM> may assist in counteracting both radially outwardly directed forces and axially downwardly directed forces.

The pressure ring <NUM> may also contribute to the strength of the rotor <NUM> during centrifugation. For example, the pressure ring <NUM> may assist in evenly distributing both radially outwardly and axially outwardly directed forces from the rotor body <NUM> to the first reinforcement <NUM>, thereby reducing or eliminating point stresses.

Turning now to <FIG>, wherein like numerals represent like features, another exemplary centrifuge rotor 10a according to another embodiment of the present invention is illustrated. The rotor 10a includes a rotor body 12a and a pressure plate 14a fixedly coupled to each other and symmetrical about an axis of rotation R defined by a rotor hub 16a, about which samples contained in sample containers 18a positioned in the rotor body 12a may be centrifugally rotated. The rotor 10a also includes a lid 20a removably coupled to the rotor hub 16a over the rotor body 12a via a lid screw 22a for assisting in retaining the sample containers 18a within the rotor body 12a during rotation thereof, for example. Similar to the embodiment shown in <FIG>, first and second elongated reinforcements 24a, 26a each extend continuously around at least portions of the rotor body 12a and pressure plate 14a.

The primary difference between the centrifuge rotor <NUM> illustrated in <FIG> and the centrifuge rotor 10a illustrated in the <FIG> is the sample capacity and, more particularly, the size and number of the cavities <NUM>, 60a and respective cell cups <NUM>, 70a and sample containers <NUM>, 18a. In this regard, the illustrated centrifuge rotor 10a has a sample capacity of <NUM> x <NUM>. In other words, the centrifuge rotor 10a includes <NUM> cavities 60a and respective cell cups 70a for receiving <NUM> sample containers 18a each having a capacity of <NUM>.

Various other features of the centrifuge rotor 10a are generally similar to those described above with respect to <FIG> and are not repeated here for the sake of brevity.

Turning now to <FIG>, wherein like numerals represent like features, another exemplary centrifuge rotor 10b according to another embodiment of the present invention is illustrated. The rotor 10b includes a rotor body 12b and a pressure plate 14b fixedly coupled to each other and symmetrical about an axis of rotation R defined by a rotor hub 16b, about which samples contained in sample containers 18b positioned in the rotor body 12b may be centrifugally rotated. The rotor 10b also includes a lid 20b removably coupled to the rotor hub 16b over the rotor body 12b via a lid screw 22b for assisting in retaining the sample containers 18b within the rotor body 12b during rotation thereof, for example. Similar to the embodiment shown in <FIG>, first and second elongated reinforcements 24b, 26b each extend continuously around at least portions of the rotor body 12b and pressure plate 14b.

The primary difference between the centrifuge rotor <NUM> illustrated in <FIG> and the centrifuge rotor 10b illustrated in the <FIG> is the sample capacity and, more particularly, the size of the cavities <NUM>, 60b and respective cell cups <NUM>, 70b and sample containers <NUM>, 18b. In this regard, the illustrated centrifuge rotor 10b has a sample capacity of <NUM> x <NUM>. In other words, the centrifuge rotor 10b includes eight cavities 60b and respective cell cups 70b for receiving eight sample containers 18b each having a capacity of <NUM>.

Various other features of the centrifuge rotor 10b are generally similar to those described above with respect to <FIG> and are not repeated here for the sake of brevity.

Turning now to <FIG>, an exemplary method of manufacturing the centrifuge rotor <NUM>, 10a, 10b is provided. At step <NUM>, the rotor body <NUM>, 12a, 12b is constructed. For example, the rotor body <NUM>, 12a, 12b may be compression molded from layers of resin-coated carbon fiber laminate material. At step <NUM>, each of the cell cores or cups <NUM>, 70a, 70b is positioned within a respective one of the cavities <NUM>, 60a, 60b of the rotor body <NUM>, 12a, 12b. The cell cups <NUM>, 70a, 70b may be co-molded to the rotor body <NUM>, 12a, 12b (e.g., during step <NUM>) or may be inserted into the cavities <NUM>, 60a, 60b after construction of the rotor body <NUM>, 12a, 12b. At step <NUM>, the pressure plate <NUM>, 14a, 14b is constructed. For example, the pressure plate <NUM>, 14a, 14b may be compression molded from layers of resin-coated carbon fiber laminate material.

At step <NUM>, the rotor body <NUM>, 12a, 12b is positioned on the pressure plate <NUM>, 14a, 14b. During step <NUM>, the rotor body <NUM>, 12a, 12b and pressure plate <NUM>, 14a, 14b may be seated on the rotor hub <NUM>, 16a, 16b, or on a tool similar to the rotor hub <NUM>, 16a, 16b, to assist in locating and/or maintaining a desired position of the rotor body <NUM>, 12a, 12b relative to the pressure plate <NUM>, 14a, 14b, for example. In one embodiment, step <NUM> may include coupling the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b together. For example, the pressure plate <NUM>, 14a, 14b and the bottom sidewall <NUM>, 32a, 32b and holders <NUM>, 46a, 46b of the rotor body <NUM>, 12a, 12b may be compression molded with one another to thereby yield a unitary structure. In addition or alternatively, the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b may be coupled to each other via an adhesive. For example, the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b may be initially coupled to each other via an adhesive prior to compression molding the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b to each other. Alternatively, the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b may be compression molded to each other during a later step, as described below.

At step <NUM>, the pressure ring <NUM>, 110a, 110b is positioned over the rotor body <NUM>, 12a, 12b. For example, the pressure ring <NUM>, 110a, 110b may be press-fitted to the rotor body <NUM>, 12a, 12b around the cell cup holders <NUM>, 46a, 46b, such as against the bottom sidewall <NUM>, 32a, 32b of the rotor body <NUM>, 12a, 12b.

At step <NUM>, the first reinforcement <NUM>, 24a, 24b is applied to at least the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b. For example, the first strand of material <NUM>, 120a, 120b may be circularly wound around at least portions of the rotor body <NUM>, 12a, 12b, the pressure plate <NUM>, 14a, 14b, and the pressure ring <NUM>, 110a, 110b. During step <NUM>, the rotor body <NUM>, 12a, 12b and pressure plate <NUM>, 14a, 14b may be seated on the rotor hub <NUM>, 16a, 16b, or on a tool similar to the rotor hub <NUM>, 16a, 16b, to assist in locating and/or maintaining a desired position of the rotor body <NUM>, 12a, 12b relative to the pressure plate <NUM>, 14a, 14b, for example. In one embodiment, step <NUM> may include curing the first strand <NUM>, 120a, 120b after the winding process so as to be integrally formed with the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b. Such curing may also include compression molding the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b together. Alternatively, the first strand <NUM>, 120a, 120b may be cured during a later step, as described below.

At step <NUM>, the second reinforcement <NUM>, 26a, 26b is applied to at least the pressure plate <NUM>, 14a, 14b and the first reinforcement <NUM>, 24a, 24b. For example, the second strand of material <NUM>, 130a, 130b may be helically wound around at least portions of the rotor body <NUM>, 12a, 12b, the pressure plate <NUM>, 14a, 14b, the lid <NUM>, 20a, 20b, and the pressure ring <NUM>, 110a, 110b. During step <NUM>, the rotor body <NUM>, 12a, 12b and pressure plate <NUM>, 14a, 14b may be seated on the rotor hub <NUM>, 16a, 16b, or on a tool similar to the rotor hub <NUM>, 16a, 16b, to assist in locating and/or maintaining a desired position of the rotor body <NUM>, 12a, 12b relative to the pressure plate <NUM>, 14a, 14b, for example. Similarly, the lid <NUM>, 20a, 20b may be removably coupled to the rotor hub <NUM>, 16a, 16b (or tool) during step <NUM>, to assist in ensuring that a portion of the second reinforcement <NUM>, 26a, 26b is received within the peripheral recess <NUM>, 166a, 166b of the lid <NUM>, 20a, 20b. In one embodiment, step <NUM> may include curing the second strand <NUM>, 130a, 130b after the winding process so as to be integrally formed with the rotor body <NUM>, 12a, 12b, the pressure plate <NUM>, 14a, 14b, and the first reinforcement <NUM>, 24a, 24b. Such curing may also include curing the first strand <NUM>, 120a, 120b, and/or compression molding the rotor body <NUM>, 12a, 12b and the pressure plate <NUM>, 14a, 14b together.

At step <NUM>, the rotor hub <NUM>, 16a, 16b is operatively coupled to the pressure plate <NUM>, 14a, 14b. For example, each of the pins <NUM>, 108a, 108b may be threadably received by a respective one of the threaded bores <NUM>, 148a, 148b and inserted into the corresponding bore <NUM>, 106a, 106b of the pressure plate <NUM>, 14a, 14b. As described above, step <NUM> may be performed before or during one or more of steps <NUM>, <NUM>, or <NUM>.

At step <NUM>, the lid <NUM>, 20a, 20b is removably coupled to the rotor hub <NUM>, 16a, 16b. For example, the lid <NUM>, 20a, 20b may be removably coupled to the rotor hub <NUM>, 16a, 16b over the rotor body <NUM>, 12a, 12b via the lid screw <NUM>, 22a, 22b, which may be tightened against the lid <NUM>, 20a, 20b via a tool rod. Usually, the lid <NUM>, 20a, 20b is coupled over the rotor body <NUM>, 12a, 12b only after samples in sample containers have been inserted into cavities <NUM>, 60a, 60b.

Claim 1:
A fixed angle centrifuge rotor (<NUM>, 10a, 10b), comprising:
a rotor body (<NUM>) having an upper surface (<NUM>) and a plurality of tubular cavities (<NUM>) extending from the upper surface to respective bottom walls (<NUM>), each cavity being configured to receive a sample container (<NUM>) therein; and
a pressure plate (<NUM>) including an upper surface (<NUM>) and a plurality of depressions (<NUM>) spaced apart from each other on the upper surface and each including a bottom surface (<NUM>), wherein the pressure plate is operatively coupled to the bottom walls and configured to transfer torque to the bottom walls,
wherein the pressure plate is configured to be directly coupled to a rotor hub and to receive torque directly from the rotor hub, characterized in that the pressure plate includes a lower surface and a plurality of bores (<NUM>) spaced apart from each other on the lower surface, and wherein the bores are each configured to receive a respective pin (<NUM>) for directly coupling the pressure plate to the rotor hub.