Patent Publication Number: US-9405836-B2

Title: Continuous flow ultra-centrifugation systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 12/338,826 filed on Dec. 18, 2008, now U.S. Pat. No. 8,192,343 issued on Jun. 5, 2012, which claims the benefit of U.S. Provisional Application Ser. No. 61/008,902, filed Dec. 21, 2007, the contents of both of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to continuous flow ultra-centrifugation systems. More particularly, the present disclosure relates to continuous flow ultra-centrifugation systems having an electric drive assembly. 
     2. Description of Related Art 
     Centrifugal separation is commonly used to separate a solution into its constituent parts based on the density of the constituents. Here, the centrifugation system creates a centrifugal force field by spinning the solution containing the constituents to be separated, thus causing the constituents of higher density to separate from the solution. 
     Many different styles of centrifugation systems have been used and are typically classified by, among other things, the flow in the system (e.g., batch or continuous flow) and by the speed by the centrifugation (e.g., ultra-centrifugation). 
     Common continuous flow ultra-centrifugation systems typically rotate the rotor at speeds of more than 60,000 revolutions per minute. Many continuous flow ultra-centrifugation systems achieve such speeds using pneumatic drive systems. However, more recently electrically driven continuous flow ultra-centrifugation systems have been developed. 
     Unfortunately, such prior art continuous flow ultra-centrifugation systems have several common disadvantages. One common disadvantage is the size of the system, which often requires significant floor space. Another common disadvantage relates to the failure of the vacuum seals, which are located around the high-speed drive spindle. Yet another common disadvantage relates to the amount of heat generated and transferred to the solution and its constituents during the centrifugation process. 
     Accordingly, there is a need for continuous flow ultra-centrifugation systems that overcome, alleviate, and/or mitigate one or more of the aforementioned and other deleterious effects of the prior art systems. 
     BRIEF SUMMARY OF THE INVENTION 
     A continuous flow centrifuge system is provided. The system includes a rotor, a stator, a stator housing, upper and lower bearing plates, upper and lower bearings, first and second snap rings, and lip seal. The upper bearing rotatably secures a shaft of the rotor in the upper bearing plate. The first snap ring secures the upper bearing to the rotor shaft. The lip seal is over the upper bearing and forms a rotatable seal with the upper bearing plate. The second snap ring secures the lip seal to an inner diameter of the upper bearing plate. The upper and lower bearing plates are secured to the stator housing so that the rotor is operatively aligned with the stator. 
     In some embodiments, the stator housing can include a stator cooling chamber and the system can include a vapor-compression-cooling system that pumps a refrigerated coolant into the stator cooling chamber. The stator cooling chamber and the refrigerated coolant can be sufficient to prevent heating of a heating product within the system by more than about 4.0 degrees. 
     In other embodiments, the lower bearing plate can include a pair of ports and the stator can be positioned in the stator housing so that a power cable and a communication cable are in electrical communication with the stator through the pair of ports, respectively. 
     In still other embodiments, the upper bearing plate can include an inner surface that is sloped in a direction away from the lip seal. 
     A continuous flow centrifuge system is also provided that includes a control interface, a control cabinet, a lift assembly, a drive assembly, and a centrifugation tank assembly. The control cabinet is shaped and configured to fit under a horizontal boom of the lift assembly so that the control cabinet to occupies substantially the same foot print as the lift assembly. 
     A system is provided that includes a controller, a touch screen having a plurality of control icons, a controlled device, and a single safety sensor. The controller prevents operation of the controlled device without contact by a user of both the single safety sensor and a respective one of the plurality of control icons. 
     The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is perspective view of an exemplary embodiment of a continuous flow ultra-centrifugation system according to the present disclosure; 
         FIG. 2  is a perspective view of an exemplary embodiment of a control cabinet of  FIG. 1 ; 
         FIG. 3  is an opposite perspective view of the control cabinet of  FIG. 2 ; 
         FIG. 4  illustrates the control cabinet of  FIG. 2  having various covers removed to illustrate the components therein; 
         FIG. 5  illustrates the control cabinet of  FIG. 3  having various covers removed to illustrate the components therein; 
         FIG. 6  is a perspective view of an exemplary embodiment of a vacuum assembly of the control cabinet; 
         FIG. 7  illustrates an exemplary embodiment of a vapor-compression-cooling system of the control cabinet; 
         FIG. 8  illustrates an exemplary embodiment of an oil filter assembly and a coolant assembly of the control cabinet; 
         FIG. 9  is a perspective view of a drive assembly and a centrifuge tank assembly according to the present disclosure for use with the system of  FIG. 1 ; 
         FIG. 10  is a side view of the drive assembly and centrifuge tank assembly of  FIG. 9 ; 
         FIG. 11  is a perspective view of the drive assembly of  FIG. 1 ; 
         FIG. 12  is a perspective view of the drive assembly of  FIG. 11  having an upper cover removed; 
         FIG. 13  is a first partial exploded view of a rotor assembly of the drive assembly of  FIG. 11 ; 
         FIG. 14  is a second partial exploded view of the rotor assembly of  FIG. 13 ; 
         FIG. 15  is a sectional view of the rotor assembly of  FIG. 13  in an assembled state; 
         FIG. 16  is a perspective exploded view of a stator assembly of the drive assembly of  FIG. 11 ; and 
         FIG. 17  is a sectional view of the drive assembly of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and in particular to  FIG. 1 , an exemplary embodiment of a continuous flow ultra-centrifugation system according to the present disclosure is shown and is generally referred to by reference numeral  10 . 
     Continuous flow ultra-centrifugation system  10  (hereinafter “system”) includes a control interface  12 , a control cabinet  14 , a lift assembly  18 , a drive assembly  20 , and a centrifugation tank assembly  22 . 
     Control interface  12  is secured to lift assembly  18  by an arm  16 . In the illustrated embodiment, arm  16  is a moveable arm that allows an operator move the control interface to a desired position with respect to system  10 . Of course, it is contemplated by the present disclosure for control interface  12  to be secured to any component of system  10  such as, but not limited to, control cabinet  14 , drive assembly  20 , centrifugation tank assembly  22 , and any combinations thereof. 
     Control interface  12  is in electrical communication with, for example, control cabinet  14 , lift assembly  18 , and drive assembly  20  to allow the operator to control the various movements and operations of system  10  from one central location. Control interface  12  can be any human-machine-interface (HMI). Preferably, interface  12  is a touch screen that allows the operator to control the various components of system  10 . 
     Due to various safety regulations, it is common for many controlled devices, such as system  10 , to require two hand control devices a predetermined distance from one another. Typically, both hand control devices must be activated, indicating that the operator&#39;s hands are out of danger from any moving parts, before the control devices activate the controlled device. Unfortunately, the use of a touch screen for interface  12  has made compliance to this safety requirement difficult. 
     Advantageously, system  10  is configured to provide this desired safety feature while maintaining the use of a touch screen as control interface  12 . Here, system  10  can include a safety sensor  12 - 1  used in conjunction with any one of a plurality of programmed control icons  12 - 2  (only one shown) resident on control interface  12 . Safety sensor  12 - 1  is positioned on a side or rear of control interface  12  so that the safety sensor is a desired distance from programmed control icons  12 - 2 . 
     In this manner, system  10  is configured so that the operator must, during certain operations, maintain one hand on safety sensor  12 - 1  and the other hand on a respective one of the programmed control icons  12 - 2 . Thus, the removal of a hand from any control button  12 - 1  or icon  12 - 2  will result in system  10  stopping the particular operation. Accordingly, system  10  provides the enhanced ease of use features available when using a touch screen interface  12 , while ensuring operator safety by way of safety sensor  12 - 1 . 
     In the illustrated embodiment, lift assembly  18  is shown as a two-axis lift, which is configured to move in at least a vertical direction (x) and a horizontal direction (y). In this manner, lift assembly  18  is configured to, under the control of the operator via interface  12 , lift and remove drive assembly  20  from tank assembly  22  in a known manner. However, it is also contemplated by the present disclosure for lift assembly  18  to be a single-axis lift or a three-axis lift as desired. 
     Control cabinet  14  includes a mechanical enclosure  24  and an electrical enclosure  26 . A more detailed discussion of control cabinet  14  is made by way of reference to  FIGS. 1-3 . 
     Advantageously, control cabinet  14  is shaped and configured to fit under the horizontal boom  28  of lift assembly  18 . In this manner, the foot print of system  10  can be reduced by allowing control cabinet  14  to occupy substantially the same foot print as lift assembly  18 . 
     Mechanical enclosure  22  includes an operator access panel  30  and a first service access panel  32 , while electrical enclosure  26  includes a second service access panel  34 . Advantageously and as will be described in more detail below, the various components within control cabinet  14  are positioned for access via operator access panel  30 , first service access panel  32 , and second service access panel  34  by the appropriate personnel. 
     For example, the components within control cabinet  14  that are commonly accessed and used by an operator can easily be accessed via operator access panel  30 . Conversely, components within control cabinet  14  that are commonly accessed and used by service personnel (e.g., mechanics, electricians, engineers, etc) can easily be accessed via first and second service access panels  32 ,  34 , respectively. 
     In addition and as will be described in more detail below, control cabinet  14  is organized so that the various connectors  36 , which include, but are not limited to, fluid connectors, pneumatic connectors, oil connectors, electrical connectors, and communication connectors, generally exit the control cabinet from an upper panel  38  of the control cabinet. 
     In some embodiments, one or more connectors  36  can also exit from a front panel  40  of control cabinet  14 , where the front panel  40  is adjacent to and faces tank assembly  22 . 
     In this manner, control cabinet  14  is a universal cabinet, namely one that does not require special configuration as a left-handed or right-handed system. Rather, the only component of system  10  that need be established in a left or right position is control interface  12 , which can easily be secured to the left or right sides of lift assembly  18  as needed. 
     In other embodiments, control cabinet  14  can include one or more organization lugs  42  defined on front panel  40 . As can be imagined, the use of system  10  requires numerous conduits, wires, and cables (not shown) that are connected between connectors  36  and the various components of the system such as, but not limited to, control interface  12 , lift assembly  18 , drive assembly  20 , and centrifugation tank assembly  22 . Advantageously, lugs  42  allow the operator to maintain the conduits, wires, and cables in a desired and organized location by using to lugs to secure the conduits, wires, and cables in the desired location. 
     The internal components of control cabinet  14  are described with reference to  FIGS. 4 through 10 .  FIG. 4  illustrates a view of control cabinet  14  as accessible from first service access panel  32  and front panel  40 , while  FIG. 5  illustrates a view of the control cabinet as accessible from operator access panel  30 . 
     Although not illustrated, electrical enclosure  26  includes a plurality of known electrical controls including, but not limited to, one or more programmable logic controllers (PLC&#39;s), one or more relays, one or more circuit breakers, and other electrical controls. As such, an electrician or controls engineer can access the components in electrical enclosure via second service access panel  34 . 
     Control cabinet  14  includes a vacuum assembly  44 , a vapor-compression-cooling system  46 , an oil filter assembly  48 , and a coolant assembly  50 . 
     Vacuum assembly  44  includes a motor  52  drivingly engaged to a vacuum pump  54 . Vacuum assembly  44  is in fluid communication with tank assembly  22  via a vacuum hose  56 . 
     Advantageously, vapor-compression-cooling system  46  is in control cabinet  14  and, thus, can be used to providing cooling to drive assembly  20  as is described herein below. Vapor-compression-cooling system  46  includes a compressor, an evaporator, an expansion device, and a condenser in fluid communication with one another so that a refrigerant is compressed and expanded in a known manner. 
     Vapor-compression-cooling system  46  further includes a first coolant reservoir  60  of coolant ( FIG. 5 ) such as, but not limited to, glycol and a first heat exchanger  62  ( FIGS. 4 and 7 ). First heat exchanger  62  is in a heat exchange relationship with the condenser so that vapor-compression-cooling system  46  is configured to condition or refrigerate the coolant. 
     Importantly, control cabinet  14  is configured to pump the refrigerated coolant from reservoir  60  to tank assembly  22  and to drive assembly  20 , which is described in more detail below. 
     Oil filter assembly  48  includes an oil reservoir  64  ( FIG. 5 ) and a filter  66  ( FIG. 8 ). Control cabinet  14  is configured to pump the oil from reservoir  64  to the upper and lower dampers of tank assembly  22 , which is described in more detail below. In some embodiments, control cabinet  14  is configured to pump the oil from reservoir  64  through a heat exchanger  68  in heat exchange relationship with the refrigerated coolant from reservoir  60  to cool the oil. 
     Coolant assembly  50  includes a second coolant reservoir  70  ( FIG. 5 ) having a coolant such as, but not limited to, water and a heat exchanger  72  ( FIG. 8 ). Heat exchanger  72  is in a heat exchange relationship with the condenser so that vapor-compression-cooling system  46  is configured to condition or refrigerate the second coolant. Control cabinet  14  is configured to pump the coolant from reservoir  70  to the upper and lower seals of drive assembly  20 , which is described in more detail below. 
     Control cabinet  14  controls the operation of vacuum assembly  44 , vapor-compression-cooling system  46 , oil filter assembly  48 , and coolant assembly  50 . Further, control cabinet  14  is in electrical communication with interface  12  so that the operator can control each component within the control cabinet. 
     In some embodiments, control cabinet  14  can include a vent  74 , shown in  FIG. 2 , for venting air from within the cabinet to an exterior of the cabinet through a filter (not shown). In certain clean room applications, control cabinet  14  can be vented to an exterior of the clean room via a conduit (not shown) in fluid communication with vent  74 . 
     Referring now to  FIGS. 9 and 10 , centrifuge tank assembly  22  is described in more detail with reference thereto. Centrifuge tank assembly  22  includes an upper vibration damper  76 , a lower vibration damper  78 , a centrifuge tank  80 , and a centrifuge base  82 . Centrifuge tank assembly  22  is commercially available from the assignee of the present application and thus is not described in detail herein. Rather, drive assembly  20  of the present disclosure is configured to mate with the known upper vibration damper  76 . 
     Referring now to  FIGS. 11 through 17 , drive assembly  20  is described in more detail with reference thereto. Drive assembly  20  includes an upper housing  90 , a rotor assembly  92 , and a stator assembly  94 . 
     Upper housing  90  is secured to rotor assembly  92  at an outer housing  140  to define an upper seal chamber  96  ( FIG. 17 ) above the rotor assembly. Upper housing  90  having upper seal chamber  96  is commercially available from the assignee of the present application and thus is not described in detail herein. Rather, drive assembly  20  of the present disclosure is configured to mate with the known upper housing  90  having upper seal chamber  96 . 
     In addition, upper housing  90  is secured to rotor assembly  92  at outer housing  140  to define an air chamber  88  as seen in  FIG. 17 . For example, upper housing  90  can include an upper seal o-ring  98  ( FIGS. 12 and 17 ) secured between outer housing  140  of rotor assembly  92  and the upper housing by one or more bolts  100 . In this manner, air chamber  88  defines a substantially fluid tight chamber, which mitigates noise from emanating from drive assembly  20  and prevents spills of cooling fluid, in the event upper seal chamber  96  leaks into air chamber  88 . 
     In some embodiments, it is contemplated for drive assembly  20  to include a sound absorber feature  89  within air chamber  88 . For example, it is contemplated for drive assembly  20  to include a sound absorbing material such as, but not limited to, an open or closed cell foam member within air chamber  88 . In another example, it is contemplated for the sound absorber feature of drive assembly  20  to include one or more sound baffles or machined features within air chamber  88  to absorb and/or attenuate noise therein. Further, it is contemplated for the sound absorber feature of drive assembly  20  to include any combination of sound absorbing material and the sound attenuating baffles/features. 
     Coolant assembly  50  pumps coolant from reservoir  70  into upper seal chamber  96  via a first port  102  and returns the coolant to the reservoir via a second port  104  ( FIG. 11 ). In this manner, coolant assembly  50  is configured to cool the upper seal within upper seal chamber  96 . 
     Rotor assembly  92  includes an upper bearing plate  106  and a rotor  108  as seen in  FIGS. 13 through 15 . 
     Rotor  108  includes a plurality of magnets  110  disposed therein in a known manner and a hollow rotor shaft  112 . Rotor assembly  92  also includes a lower bearing  114  and an upper bearing  116 . Lower bearing  114  is secured to shaft  112  by a lower jam nut  118 . Upper bearing  116  is sealed within upper bearing plate  106  by one or more o-rings  120  (two shown) and is maintained on shaft  112  by a snap-ring  122  and an upper jam nut  124 . Snap-ring  122  is resiliently engaged in a groove (not shown) of shaft  112 . 
     In addition, the upper bearing  116  is sealed from the contents of upper bearing plate  106 . For example, rotor assembly  92  can include an o-ring  126 , a lip seal  128 , and an internal snap ring  130 . Lip seal  128  forms a rotatable seal with shaft  112  over upper jam nut  124 . O-ring  126  forms a seal between an inner surface of bearing plate  106  and an outer surface of lip seal  128 . Snap-ring  130  is resiliently engaged in a groove (not shown) of bearing plate  106 . 
     Lip seal  128  can be made of any material sufficient to withstand the conditions within drive assembly  20 . In an exemplary embodiment, lip seal  128  is made of polytetrafluoroethylene (PTFE). 
     Advantageously, drive assembly  20  does not require rotor assembly  92  to be held in a vacuum environment, thus allowing more effective cooling of the rotor  108 . For example, eliminating the vacuum environment from the area around rotor  108  allows cooling from stator assembly  94 , which is described in more detail below, to convectively cool the rotor across the motor gap. 
     Upper bearing plate  106  includes an inner surface  132  that is sloped in a direction away from lip seal  128 . In this manner, any cooling fluid that may leak into air chamber  88  due to a failure of the seal in upper seal chamber  96  is urged away from lip seal  128  by the force of gravity into a collection area  134 . Thus, upper bearing plate  106  can assist in maintaining the seal provided by lip seal  128  by ensuring that the cooling fluid does not collect on the lip seal, but rather is moved away from the lip seal towards collection area  134 . 
     Stator assembly  94  includes an outer housing  140 , a lower bearing plate  142 , an inner housing  144 , and stator windings  146  as shown in  FIGS. 16 and 17 . 
     Outer and inner housings  140 ,  144  define a stator cooling chamber  148  therebetween. For example, outer and inner housings  140 ,  144  can be secured to one another so that a pair of o-rings  150  ensure chamber  148  is substantially fluid tight. 
     Vapor-compression-cooling system  46  pumps refrigerated coolant from reservoir  60  into stator cooling chamber  148  via a first port  152  and returns the coolant to the reservoir via a second port  154  ( FIG. 11 ). In this manner, cooling system  46  is configured to cool drive assembly  20 . As rotor assembly  92  of the present disclosure is not a vacuum environment, the cooling of inner housing  144  radiates across the air gap and convectively transfers across the air gap to cool rotor  108 . 
     Without wishing to be bound by any particular theory, it is believed that the use of refrigerated coolant from reservoir  60  to cool drive assembly  20  is effective to prevent the drive assembly from heating product within system  10 . For example, system  10  finds particular use in the production of viral vaccines, which are commonly manufactured in egg based media. It has been determined by the present disclosure that heating of the egg based media, and thus, the product by more than about 4.0 degrees Celsius (° C.) is detrimental to the resultant product. 
     Thus, drive assembly  20  of the present disclosure, which includes cooling via circulation of refrigerated coolant through stator cooling chamber  148 , is effective at removing sufficient heat generated by the drive assembly so that the temperature of product flowing through the drive assembly increases by no more than about 4.0° C. Preferably, drive assembly  20  is effective at removing sufficient heat so that the temperature of product flowing through the drive assembly increases by no more than about 0.0° C. Most preferably, drive assembly  20  is effective at removing sufficient heat so that the temperature of product flowing through the drive assembly decreases by up to about 4.0° C. or more. 
     Lower bearing  114  of rotor assembly  92  is sealed within lower bearing plate  142  by one or more o-rings  156  (two shown) so that the lower bearing rests on a resilient member  158 . 
     Lower bearing plate  142  includes a pair of ports  160  for providing a power cable  162  and a communication cable  164  from control cabinet  14  to stator windings  146 . More particularly, stator windings  146  are inverted as compared to other motors so that communication ports  160  are formed in lower bearing plate  142  instead of upper bearing plate  106 . In this manner, upper bearing plate  106  does not require ports defined therein. 
     It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated. 
     While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.