Patent Description:
Pumps are generally used to transport fluid between two locations. In biopharmaceutical applications, for example, pumps may be used to move biopharmaceutical materials between various storage containers, mixers, testing equipment, and other areas. Conventional pumps include drive shafts and rotating impellers imparting damaging forces along shear-sensitive fluidic components. Conventional pumps can impart uneven fluid flow rates and uneven pulsations which can damage or disturb sensitive systems.

<CIT> discloses a rotor for use with a fluid flow generator or reactor, the rotor being intended to rotate about a central axis and having a surface which defines an arcuate fluid pathway for fluid flow about the central axis about which the rotor is able to rotate, wherein the surface has the configuration of a logarithmic curve substantially conforming to the mathematical progression known as the Golden Section or the Fibonacci Progression.

Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.

The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope of the invention, which is solely defined by the appended claims.

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.

The use of "a" or "an" is employed to describe elements and components described herein. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise.

The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in textbooks and other sources within the fluid and pump arts.

A pump in accordance with the present invention is defined by claim <NUM> and includes, among other features, a housing defining an internal volume and an impeller disposed in the internal volume. The impeller includes a magnetic element adapted to magnetically couple with a drive element. The drive element, which can be externally located with respect to the housing, magnetically urges the impeller. At least a portion of the surface of the impeller conforms to a logarithmic spiral.

A single-use pump in accordance with one or more of the embodiments described but which is not claimed can generally include a housing defining an internal volume and an impeller disposed in the internal volume. At least a portion of the surface of the impeller can conform to a generally logarithmic spiral. The single-use pump is adapted to magnetically couple with a drive element. The drive element can be reusable between different pumping operations.

A fluid circulation system in accordance with one or more of the embodiments described herein includes first and second tubulars, and a pump according to the present invention disposed between the first and second tubulars.

In certain embodiments which are not claimed, a biopharmaceutical circulation system can include first and second tubulars coupled to first and second biopharmaceutical equipment, respectively. A pump disposed between the first and second tubulars can urge fluid from the first tubular to the second tubular. The pump can include a housing defining an internal volume and an impeller disposed in the internal volume. The impeller can include a magnetic element and at least a portion of the surface of the impeller can conform to a generally logarithmic spiral. A drive element can magnetically couple with the magnet element of the impeller and rotationally urge the impeller so as to create fluid movement within the system.

Referring to <FIG>, a fluid system <NUM> can generally include a pump <NUM>. The pump <NUM> includes a housing <NUM> and an impeller <NUM>. As illustrated, the impeller <NUM> seats within an internal volume <NUM> of the housing <NUM>. The internal volume <NUM> can define an internal volume between first and second tubulars <NUM> and <NUM>. The first tubular <NUM> can be coupled with a first equipment, such as a biopharmaceutical or medical equipment, and the second tubular <NUM> can be coupled with a second equipment, such as a biopharmaceutical or medical equipment. The equipment can include a storage container, a mixer, a sampling device, a testing device, other suitable equipment used in manufacturing or development of biopharmaceutical materials, or any combination thereof.

In an embodiment, fluid flow through the system <NUM> is unidirectional. In a particular embodiment, fluid flow occurs in a direction generally from the first tubular <NUM> to the second tubular <NUM>. In another embodiment, fluid flow through the system <NUM> is bidirectional. Rotation of the impeller <NUM> can generate axial fluid pressure, causing fluid movement through the system <NUM>.

In an embodiment, the housing <NUM> includes at least two discrete components. The at least two discrete components can be detachably coupled together. In an embodiment, the impeller <NUM> can be installed within the internal volume <NUM> prior to connecting the at least two discrete components together.

The internal volume <NUM> can have a curved interior volume defined by a curved sidewall of the housing <NUM>. Fluid flow through the system <NUM> occurs at least in part around an outer surface of the impeller <NUM>. Referring to <FIG>, the impeller <NUM> forms a fluid bearing with an inner surface of the housing <NUM>. Fluid entering the pump <NUM> from the first tubular <NUM> passes into the housing <NUM> and moves through an opening <NUM> located between the impeller <NUM> and housing <NUM>. As the impeller <NUM> begins rotating, fluid passing by the impeller <NUM> creates a fluid bearing which maintains the impeller <NUM> in a rotationally lubricated state. The fluid bearing can also permit self-centering of the impeller <NUM> relative to the housing <NUM>. Fluid not directed through the fluid bearing between the housing <NUM> and impeller <NUM> passes through an aperture <NUM> (<FIG>) in the impeller <NUM>. As described below in greater detail, the fluid passing through the aperture is driven by vanes of the impeller <NUM>.

In the illustrated embodiment, the impeller <NUM> includes a hub <NUM> and a blade <NUM> extending from the hub <NUM>. The aperture <NUM> extends through the impeller <NUM>, passing through the hub <NUM> and the blade <NUM>. As fluid passed through the aperture <NUM>, it is urged by the blade <NUM> in a direction generally parallel with an axis <NUM> of the impeller <NUM>.

The blade <NUM> includes vanes <NUM> and <NUM> (<FIG>) adapted to bias the fluid through the system <NUM>. According to the invention, the blade <NUM> includes at least two vanes. In an embodiment, the blade <NUM> can include at least three vanes, or at least four vanes, or at least five vanes, or even at least ten vanes. In another embodiment, the blade <NUM> can include no greater than <NUM> vanes, no greater than <NUM> vanes, or even no greater than <NUM> vanes. The vanes <NUM> and <NUM> can have a shape, when viewed along the axis <NUM> of the impeller <NUM>, generally corresponding to a Fibonacci sequence, also known as a golden ratio. Viewed in cross section, the impeller can have a surface curvature generally conforming to the Fibonacci sequence pattern. Impellers with such pattern have been found to be particularly effective at providing even fluid flow and dynamic balance, while exhibiting non-destructive fluid behavior (i.e., not destroying any media, e.g., biological media, within the fluid) and avoiding clogs common among conventionally-shaped impellers. Any length, width, or shape of the blade is envisioned. In an embodiment, the blade <NUM> can have vanes <NUM> and <NUM> having a tulip shape.

When the impeller <NUM> rotates within the housing <NUM>, it creates axial flow of the fluid in the internal volume <NUM> in a direction generally corresponding to the axis <NUM> of rotation. As illustrated in <FIG>, and in accordance with an embodiment, fluid flow can occur in a left-to-right direction. In another embodiment, fluid flow can occur in a right-to-left direction. Fluid flow direction is a product of blade <NUM> design and rotational direction. Although illustrated in a <NUM> degree path with the fluid flow through the pump <NUM> as linear, in an alternative embodiment, the fluid flow may be divergent through one or more exit paths from greater than <NUM> degrees to less than <NUM> degrees on any axis.

At first, the impeller <NUM> generates fluid turbulence as the fluid is initially stationary. As the impeller <NUM> begins rotating and circulation begins to occur, the turbulence subsides and cavitation is minimized. In a particular embodiment, the pump <NUM> provides cavitation-free fluid flow. Cavitation-free fluid flow provides desired properties such as, for example, a reduction in noise levels, an increase in electrical efficiency, the elimination or reduction of pump damage during operation, the like, or any combination thereof. This is contrary to conventional impellers. Conventional impellers, for example, may have pump cavitation which creates bubbles and causes unpredictable shear forces on the pumped fluid and also undesirably increases system pressure. The impeller <NUM> is configured to allow biasing of higher volumetric flow rates without damaging or disturbing shear-sensitive media suspended within the fluid. Additionally, because the impeller <NUM> biases fluid through a central aperture <NUM> (<FIG>), and not along an outer perimeter typical of conventional impellers, the speed of liquid flow is greatest in the center of the internal volume <NUM> where frictional resistance caused by sidewalls of the tubulars <NUM> and <NUM> is greatest. The lack of any traditional leading edge on the impeller <NUM> further reduces media degradation typically associated with high speed impact of fluid along the leading edge of conventional impeller blades. The reduction in shear stress permits the system <NUM> to handle more sensitive materials which might degrade upon impact with conventional impellers. For instance, the system <NUM> may provide no to low shear pumping of sensitive materials such as, for example, animal cells. The no to low shear pumping significantly reduces or even eliminates cell damage or death. Further, low to no shear stress of the pumped material may provide higher yields in apheresis, filtration, and other refinement processes.

In an embodiment, the impeller <NUM> is spaced apart entirely from the housing <NUM> when the pump <NUM> is active (i.e., rotationally spinning about axis <NUM>). In another embodiment, the impeller <NUM> can rest against an inner surface of the housing <NUM> when the pump is not active. The impeller <NUM> can have a length, LI, that is less than a length, LH, of the housing <NUM>. In an embodiment, LI is at least <NUM>% LH, at least <NUM>% LH, at least <NUM>% LH, or at least <NUM>% LH. In another embodiment, LI is no greater than <NUM>% LH, no greater than <NUM>% LH, or no greater than <NUM>% LH. The length of the impeller <NUM> relative to the length of the housing <NUM> can be in a range between and including any of the values described above.

According to the invention, the pump <NUM> further includes a magnetic element <NUM> disposed at least partially in the impeller <NUM>. In an embodiment, the magnetic element <NUM> can be disposed in any configuration. For instance, the magnetic element <NUM> can be encased within, embedded in, attached to, or combination thereof to the impeller <NUM>. In an embodiment, the magnet element <NUM> can be either exposed to the fluid path or protected from the fluid path, depending on the final configuration desired. The magnetic element <NUM> can include any magnetic, partially magnetic, or ferromagnetic material. The magnetic element <NUM> only needs to be capable of coupling with a magnetic field supplied by a drive element <NUM>. Accordingly, in a particular embodiment, the magnetic element <NUM> may be ferromagnetic and selected from the group consisting of a steel, an iron, a cobalt, a nickel, and a rare earth magnet. In an embodiment, the magnetic element <NUM> is a neodymium rare earth magnet. In a particular embodiment, the neodymium rare earth magnet has desirable power in small configurations. The magnetic element <NUM> can be configured and chosen depending on the power desired. In a further embodiment, the magnetic element <NUM> can be selected from any other magnetic or ferromagnetic material as would be readily recognized in the art. In an embodiment, the magnetic element <NUM> can include a plurality of magnetic elements disposed at least partially, such as fully, within the impeller <NUM>. In a more particular embodiment, the plurality of magnetic elements <NUM> can be spaced apart from one another, such as spaced apart equal distances from one another. In an embodiment, the magnetic elements <NUM> can be embedded fully within the impeller <NUM>. This can reduce contact with fluid which might be harmful for particular fluid applications. In another embodiment, the magnetic elements <NUM> can be at least partially exposed.

As illustrated in <FIG>, the hub <NUM> of the impeller <NUM> can be disposed in a retaining area <NUM> of the housing <NUM>. The retaining area <NUM> can form a flanged volume for the previously described fluid bearing by creating an inner surface opposite the hub <NUM>. A ratio of fluid flow rate, FB, through a bearing space <NUM> to fluid flow rate, FA, through the aperture <NUM> [FB:FA] is in a range of <NUM>:<NUM>, in a range of <NUM>:<NUM>, or in a range of <NUM>:<NUM>.

The drive element <NUM> is adapted to drive, or rotate, the magnetic elements <NUM> within the impeller <NUM>, thus initiating axial biasing of fluid within the system <NUM>. In an embodiment, the drive element <NUM> can operate through polarity switching which drives the magnetic elements <NUM>. For instance, the drive element <NUM> changes polarity thus acting upon each magnet's specific polarity located in the impeller. In another embodiment, the drive element <NUM> can operate through a rotating magnet mechanism.

In an embodiment, the pump <NUM> can include one or more stops <NUM> adapted to prevent over-insertion of the housing <NUM> into the tubulars <NUM> and <NUM>. In a particular embodiment, the stops <NUM> are integral with the housing <NUM>. Further, any flange is envisioned to enable coupling to a range of tubing diameters for the first tubular <NUM> and the second tubular <NUM>.

In an embodiment, pumps <NUM> in accordance with one or more embodiments described herein, can be adapted to provide smooth fluid flow within the system <NUM>. That is, unlike some conventional pumps used in fluid systems, the pump <NUM> can maintain a continuous fluid flow rate differing by no greater than <NUM>% at any moment, or no greater than <NUM>% at any moment, or no greater than <NUM>% at any moment, or no greater than <NUM>% at any moment, or no greater than <NUM>% at any moment. Such a continuous and unchanging flow rate, coupled with efficiencies and minimum fluid damage exhibited by the impeller <NUM>, can allow for use in certain high precision applications including ocular surgical instrumentation and other delicate areas of operation.

In an embodiment, pumps <NUM> in accordance with one or more embodiments described herein can be adapted to have a first flow rate, as measured during a first pumping operation (e.g., at time = <NUM>) and a second flow rate, as measured during a second pumping operation (e.g., at time = <NUM> minutes), where the first and second flow rates differ by no greater than <NUM>%, or no greater than <NUM>%, or no greater than <NUM>%, or no greater than <NUM>%, or no greater than <NUM>%, and the flow rate is approximately <NUM>/minute.

Pumps <NUM> in accordance with one or more embodiments herein are adapted to be used with aggressive fluids, such as DMSO or phenol. Additionally, pumps <NUM> in accordance with one or more embodiments described herein can operate at pressure differentials of at least <NUM> bars, or at least <NUM> bars, or at least <NUM> bars.

<FIG> includes a schematic view of a system <NUM> including a first area <NUM> and a second area <NUM> spaced apart by a first tubular <NUM> and a second tubular <NUM>. A pump <NUM> is disposed between the first and second tubulars <NUM> and <NUM>. The pump, driven by a drive element <NUM> is adapted to move fluid from the first area <NUM> to the second area <NUM>. The pump <NUM> can have any number of similar characteristics as compared to the pump <NUM> described above.

Peristaltic pumps are typically used in highly sensitive pumping applications, where finely tuned fluid flow rates are critical. For example, ocular surgery requires highly regulated fluid flow rates to prevent damage to highly fragile ocular tissue. Peristaltic pumps are conventionally utilized in such applications as they deliver highly metered doses of fluid as a result of their design. However, peristaltic pumps delivery highly inconsistent flow rates because of said design. Rollers moving along fluid pathways in the pump can cause erratic pressure gradients and fluid pulsation. Conventional impeller blades also fail to deliver adequate flow rate because of high rotational startup energy and non-uniform flow rates as measured at various locations around the impeller. Further, the damaging nature of the impeller's leading edge can destroy important medium within the fluid. Pumps in accordance with one or more of the embodiments described herein can reduce the problems associated with both peristaltic and conventional impeller-style pumps without compromising performance or fluid delivery. For instance, the wear-free configuration of the pump may eliminate particle shedding (i.e. when two materials generate a frictional force between them) and heat generation to allow for the processing of fluids, cell products, or other materials that are sensitive to the introduction of contaminates, temperature increase, or combination thereof, in the fluid path, to be pumped without the risk of contamination or degradation. For instance, the impeller and housing configuration provides a wear-free pumping action.

Further, given the reusable nature of the drive element <NUM> and disposable (or single-use) nature of the pump <NUM>, the risk of contamination between successive operations is minimized, unlike with peristaltic pumps, where an entire cassette may need to be disposed after operable use. In an embodiment, the pump <NUM> can be used in a single limited time (single-use), multiple-use, or continuous use operations. The pump <NUM> can be used for any industry envisioned that desires no to low shear stress pumping, contaminate-free pumping, consistent fluid flow rates, exposure to an aggressive fluid, or combination thereof. In a particular embodiment, the system <NUM> may be desirable for particulate-free systems. For instance, the system <NUM> may be advantageous for the micro-electronics industry where the process fluids used in chip fabrication must remain particulate-free. Industries such as the medical industry, biopharmaceutical industry, pharmaceutical industry, electronic industry, micro-electronic industry, chemical industry, and the like, where pumping is desired is envisioned.

Note that not all of the features described above are required, that a portion of a specific feature may not be required, and that one or more features may be provided in addition to those described. Still further, the order in which features are described is not necessarily the order in which the features are installed.

The following examples are provided to better disclose and teach processes and compositions of the present invention. They are for illustrative purposes only, and it must be acknowledged that minor variations and changes can be made without affecting the scope of the invention as recited in the claims that follow.

A CFD is a software used as a simulation technique to understand the behavior of a flow throughout a pump. By simulating the flow throughout a pump, the simulation model presents a complete and clear image of its operation. Conventionally, the CFD model is used identify areas where there is recirculation, flow detachment or where cavitation will occur, and can help establish their causes. The CFD simulation also predicts the flow profiles in the suction pipe or pipes, and can identify any vortex formation which could result in reduced pumping efficiency and premature pump failure.

High-fidelity computational fluid dynamics (Detached Eddy Simulation) and observations during physical testing are used as a mean to demonstrate pump performance and to support achievements and results related to no cavitation, more flow, less torque, and zero to low shear goal.

A custom-build pump testing rig is designed with a clear cylindrical housing in order to analyze the flow patterns and cavitation performance. The main components include a cone-bottom hopper tank, recirculation tubing, prototype test section, downstream pressure chamber with 'butterfly' valve, and inverter-controlled motor to belt-drive the rotor pipe.

The test apparatus is equipped with the following sensors: upstream pressure transducer, downstream pressure transducer, paddle wheel flowmeter, thermocouple, optical speed sensors, and wireless rotary torque transducer.

The working fluid in the tests run is ambient temperature tap water. Ambient temperature during test runs is between <NUM> degrees and <NUM> degrees Fahrenheit. Data is logged using Labview systems engineering software. Cavitation performance is evaluated during design concept phase and results are obtained to successfully achieve no cavitation. The achieved "no cavitation" is verified via high-fidelity computational fluid dynamics (Detached Eddy Simulation) and observations during physical testing (visualization completed in the physical test rig using neutrally-buoyant gel balls). A description of the settings is provided as follows:.

The value of "M" is "millions of tetrahedron" as measured by the CFD model; the values showing how many millions of tetrahedron are in different parts of the control volume.

Water at nominal ambient temperatures and atmospheric pressure requires pressure of approximately <NUM>,<NUM> - <NUM>,<NUM> Pa to induce a phase change from liquid to liquid vapor. The visualization technique of defining iso-surfaces ("iso" meaning the same value) for negative pressure in the control volume of -<NUM>,000Pa or -<NUM>,000Pa show that the pump in operation creates a negative pressure, but far less than the required <NUM>,<NUM> - <NUM>,<NUM> Pa needed for cavitation.

Physical tests of volutes are run as noted above. A transparent housing and transparent tubing is used to allow observation at varying RPM and pressure conditions. No bubble formation is seen under any test condition. No cavitation shock/vibration is observed under any test condition.

Observations obtained through physical testing are compared with results obtained in computer visualization, and the downstream flow pattern visualized with gel balls shows the same trends as the computational model. No cavitating flow patterns such as appearance of inchoate bubbles are observed in either of the testing models.

<FIG> represents an exemplary geometry for an exemplary housing <NUM>. The housing has a nozzled "exit" cylinder attached. This is a simulation model; the nozzled cylinder is not typically present in a physical experimental rig. The nozzle is analogous to the 'butterfly' valve being adjusted in the experimental rig for the same purpose.

By changing the radius of the exit nozzle on the cylinder (labelled as "N"), the flow rate, pressure drop, and torque of the volute and housing changes. The radius of the nozzle is set to <NUM>", <NUM>", <NUM>", <NUM>" and <NUM>".

A CFD simulation is then completed for these various radii dimensions and performance values are generated. Refer to Table <NUM> below.

Table <NUM> contains values that demonstrate that the Mass Flow Rate is directly proportional to the Radius of the nozzle. The flow rate increases as the radius of the nozzle is increased.

The fluid flow through the pump may be linear, or divergent through one or more exit paths from greater than <NUM>° to less than <NUM>° on any axis.

The advantageous property of low shear is verified via high-fidelity computational fluid dynamics (Detached Eddy Simulation). CFD simulations directly provide the strain rate terms, which are then multiplied by water's viscosity to give viscous shear stress of the water. Low shear stress is defined to be in the range of <NUM>-<NUM> Pa. The visualization technique of defining iso-surfaces for the pump when operating at 10Pa, 30Pa, and 100Pa generates smaller, and nearly non-existent surfaces respectively for these values of shear stress. 100Pa is still far below the upper limit of 200Pa. Therefore, as defined in scientifically standard terms, the pump demonstrates low shear.

An exemplary pump and housing is designed and can be seen in <FIG>, <FIG>. Exemplary design features include, but are not limited to: a rotor scaled to <NUM>" in diameter with universal flanges to attach a range of tubing diameters; a rim drive motor positioned near the inlet with the option of an extended inlet pipe; and a single-use or reusable wet portion of the pump.

<FIG> illustrates an exemplary pump <NUM> including a housing <NUM> where a portion of the housing is illustrated as semi-transparent to view the impeller <NUM> contained within the internal volume <NUM> of the housing. An exemplary impeller is illustrated in <FIG>.

<FIG> illustrates multiple views of an exemplary impeller <NUM> with the blade <NUM> having vanes <NUM> and <NUM> with a tulip shape.

<FIG> illustrates a side exploded view of an exemplary housing <NUM> and impeller <NUM> of <FIG>, where the impeller <NUM> is viewed outside of the internal volume of the housing <NUM>, positioned near the inlet port of the housing <NUM>. The exemplary housing <NUM> illustrates an embodiment where the inlet port and the outlet port are relatively positioned at a <NUM> degree angle. <FIG> illustrates a view where the housing <NUM> of <FIG> has been rotated to view the outlet of the housing <NUM>.

<FIG> includes a top and a bottom view, respectively, of the exemplary housing <NUM> and impeller <NUM> of <FIG> and <FIG> where the impeller is contained within the internal volume of the housing.

<FIG> includes a top exploded view of an exemplary housing <NUM> and impeller <NUM> where the housing is illustrated as two discrete components that are detached and apart.

Any final dimensions and configuration of the housing and impeller are envisioned depending on the final properties and industry desired.

Claim 1:
A pump (<NUM>) comprising:
a housing (<NUM>) defining an internal volume (<NUM>);
an impeller (<NUM>) disposed in the internal volume (<NUM>) of the housing (<NUM>), wherein the impeller (<NUM>) comprises a magnetic element (<NUM>) and at least a portion of the surface of the impeller (<NUM>) conforms to a logarithmic spiral,
wherein the impeller (<NUM>) comprises a central aperture (<NUM>) that extends through the impeller (<NUM>) for fluid flow therethrough, wherein the fluid passing around the impeller (<NUM>) creates a fluid bearing within the housing (<NUM>), and wherein the fluid not directed through the fluid bearing between the housing (<NUM>) and impeller (<NUM>) passes through the central aperture (<NUM>); and
a drive element (<NUM>) adapted to magnetically couple with the magnetic element (<NUM>) of the impeller (<NUM>),
wherein the impeller (<NUM>) comprises a hub (<NUM>) and a blade (<NUM>) extending from the hub (<NUM>),
wherein the central aperture (<NUM>) extends through the impeller (<NUM>), passing through the hub (<NUM>) and the blade (<NUM>),
wherein the blade (<NUM>) includes at least two vanes (<NUM>, <NUM>) which have a shape, when viewed along the axis of rotation of the impeller (<NUM>), that corresponds to the logarithmic spiral.