Abstract:
A system for suspending a rotating body consisting of a combination of magnetic and engineered materials. The suspension system allows for some axial motion to account for varying system loads.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. patent application Ser. No. 13/185,418 (“Method and Apparatus for Hybrid Suspension System”), filed Jul. 18, 2011, which claims benefit of priority to U.S. provisional patent application No. 61/365,691, filed Jul. 18, 2010, both of which are incorporated in their entirety by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to the suspension of rotating structures. More particularly, the invention relates to both radial and axial stability with a minimum of rotating resistance. 
     Description of the Related Art 
     Historically, rotating structures have been supported by a series of radial and axial thrust bearings placed along and at the ends of the rotating assembly. Both radial and axial thrust bearings have typically been supplied by a roller bearing technology. Although quite successful for terrestrial clean environments, this technology fails in harsh fluid environments. 
     Recently a new class of bearing has been introduced which replaces the earlier roller technology with engineered materials such as ceramic and diamond. These bearings are designed to run against each other for long periods of time in harsh environments.  FIG. 1  is a view of a radial bearing assembly  10  with engineered materials. The radial bearing assembly  10  includes an inner race  20  and an outer race  30  that are lined with one row of manufactured diamond buttons  25 . When the inner race  20  is placed within the outer race  30  the manufactured diamond buttons  25  run against each other. As shown, the manufactured diamond buttons  25  on the inner race  20  and the outer race  30  are the same size (e.g., diameter). Although the manufactured diamond buttons  25  are specifically chosen to minimize friction, they still have friction which is a function of the applied load and, for this reason, are not applicable in all applications. 
     SUMMARY OF THE INVENTION 
     This invention generally relates to the suspension of rotating structures. In one aspect, a suspension system for use with rotating machinery is provided. The suspension system includes a first suspension assembly disposed between an inner structure and an outer structure of the rotating machinery for providing axial support. The first suspension assembly comprises an array of magnets. The suspension system further includes a second suspension assembly disposed between the structures for providing radial support. The second suspension assembly comprises at least one bearing member disposed between an inner portion and an outer portion. 
     In another aspect, a method of supporting an inner structure and an outer structure of rotating machinery is provided. The outer structure is configured to rotate relative to the inner structure. The method includes the step of providing a first suspension assembly between the inner structure and the outer structure for axially supporting the structures. The first suspension assembly comprises an array of magnets. The method further includes the step of providing a second suspension assembly for radially supporting the structures. The second suspension assembly comprises a bearing member. 
     In yet a further aspect, a rotating assembly is provided. The rotating assembly includes an inner structure and an outer structure, wherein the outer structure rotates relative to the inner structure. The rotating assembly further includes a first suspension assembly comprising an array of magnets for providing axial support to the structures. Additionally, the rotating assembly includes a second suspension assembly comprising an outer portion, an inner portion and at least one bearing member for providing radial support to the structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a view illustrating a conventional radial bearing assembly. 
         FIG. 2  is a view illustrating a hybrid suspension system. 
         FIGS. 3 a -3 c    are views illustrating a radial bearing assembly in the hybrid suspension system. 
         FIGS. 4 a -4 c    are views illustrating a radial bearing assembly in the hybrid suspension system. 
         FIGS. 5 a -5 c    are views illustrating a radial bearing assembly in the hybrid suspension system. 
         FIGS. 6 a -6 c    are views illustrating a radial bearing assembly in the hybrid suspension system. 
         FIGS. 7 a -7 c    are views illustrating a radial bearing assembly in the hybrid suspension system. 
         FIG. 8  is a view illustrating a lubrication system for use with the radial bearing assembly. 
         FIGS. 9 and 10  are views illustrating a rotating assembly that includes the hybrid suspension system. 
     
    
    
     DETAILED DESCRIPTION 
     This present invention generally relates to a method of suspension of rotating structures utilizing both engineered materials and magnetic material to optimize the system. Engineered materials are used in the radial direction where lateral forces are minimum, providing low friction losses, and magnetic material is used to create the axial suspension member where loads are high and variable, resulting in no friction contribution to the axial system. The present invention will be described herein in relation to rotating machinery, such as turbines, generators or any rotating shaft systems. It is to be understood, however, that the suspension assembly may also be used for other types of applications without departing from principles of the present invention. To better understand the novelty of the suspension assembly of the present invention and the methods of use thereof, reference is hereafter made to the accompanying drawings. 
       FIG. 2  is a view illustrating a hybrid suspension system  100  according to one embodiment of the present invention. The hybrid suspension system  100  includes an axial bearing assembly  110  (e.g., first suspension assembly) and a radial bearing assembly  120  (e.g., second suspension assembly). The axial bearing assembly  110  is configured to provide support to the axial load of an outer structure  130 . The radial bearing assembly  120  is configured to provide support to the radial load of the outer structure  130 . In the embodiment shown in  FIG. 2 , the outer structure  130  rotates relative to an inner structure  135 . In another embodiment, the inner structure  135  rotates relative to the outer structure  130 . Further, as shown in  FIG. 2 , the hybrid suspension system  100  includes two axial bearing assemblies  110  and two radial bearing assemblies  120 . It should be understood, however, that the hybrid suspension system  100  may have one or any number of axial bearing assemblies  110  and radial bearing assemblies  120 , without departing from principles of the present invention. 
     The axial bearing assembly  110  includes an array of magnet members comprising a first magnet member  140 , a second magnet member  145 , a third magnet member  150  and a fourth magnet member  155 . The first magnet member  140  and the third magnet member  150  are attached to the inner structure  135 , and the second magnet member  145  and fourth magnet member  155  are attached to the outer structure  130 . In an alternative embodiment, the first magnet member  140  and the third magnet member  150  are attached to the outer structure  130 , and the second magnet member  145  and fourth magnet member  155  are attached to the inner structure  135 . The magnet members  140 ,  145 ,  150 ,  155  are shown as rings with a rectangular cross-section. It should be understood, however, that the magnet members  140 ,  145 ,  150 ,  155  may have any geometrical shape and cross-section, without departing from principles of the present invention. The present invention depicts the use of permanent magnets, however the present invention can also use electromagnets or a combination of permanent and electromagnets. The combination of electromagnets allows for controlled axial positioning with variable loading. 
     Each magnet member  140 ,  145 ,  150 ,  155  in the axial bearing assembly  110  includes a north magnetic pole (N) and a south magnetic pole (S). The magnet members may be arranged such that the magnetic poles for adjacent magnet members are the same. For instance, the south magnetic pole of the first magnet member  140  is facing the south magnetic pole of the second magnet member  145 , and as such a repulsive force is generated between the first and second magnet members  140 ,  145 . A similar arrangement may be established between the other magnet members such that the magnet members may be effectively held in balance between the repulsive forces of the other magnet members. As a result, the magnet members are arranged such that the outer structure  130  is automatically centralized relative to the inner structure  135 . However, upon application of an axial force that is greater than the repulsive forces of the magnet members, the structures  130 ,  135  will move in an axial direction relative to each other (see arrow  105  or arrow  115 ). The axial force may be generated by fluid flow through the hybrid suspension system  100  or any other means. 
     The array of magnet members in the axial bearing assembly  110  may be arranged in other configurations. For example, the magnet members may be selected and arranged such that the outer structure  130  requires an axial load to be centralized relative to the inner structure  135 . In another example, the magnet members may be selected and arranged such that the outer structure  130  is automatically offset relative to the inner structure  135 . In other words, magnetic directions, strength and face-to-face spacing would be chosen to yield the desired response of the outer structure  130 . An example of an axial magnetic suspension is described in U.S. patent application Ser. No. 13/163,136 filed on Jun. 17, 2011, which is incorporated herein by reference. 
     As shown in  FIG. 2 , the radial bearing assembly  120  includes an inner portion  170  and an outer portion  180  having a plurality of bearing members  175 . In the embodiment shown in  FIG. 2 , the inner portion  170  and the bearing members  175  are made from engineered materials, such as ceramic or diamond. The inner portion  170  is attached to the inner structure  135 , and the outer portion  180  is attached to the outer structure  130 . As described herein, the radial bearing assembly  120  is configured to maintain contact between the bearing members  175  and the inner portion  170  even as the outer structure  130  and the inner structure  135  move axially relative to each other (see arrow  105  or arrow  115 ). 
       FIGS. 3 a -3 c    are views illustrating a radial bearing assembly  200 . The radial bearing  200  includes an inner portion  205  and an outer portion  225  that are shaped as a ring member similar to the radial bearing assembly  120  shown in  FIG. 2 . To illustrate the function of the radial bearing assembly  200 , the inner portion  205  and the outer portion  210  have been flattened in  FIGS. 3 a -3 c   . The inner portion  205  includes a plurality of bearing members  210  having a first diameter, and the outer portion  225  includes a plurality of bearing members  230  having a second larger diameter. The inner portion  205  and the outer portion  225  are positioned such that the bearing members  210 ,  230  face each other. As shown, the inner portion  205  includes two rows of bearing members  210 , and the outer portion  225  includes one row of bearing members  230 . In another embodiment, the inner portion  205  includes one row of bearing members  210 , and the outer portion  225  includes two rows of bearing members  230 . Under no axial load, the outer portion  225  would be positioned as shown in  FIG. 3 b   , riding over the center between two rows of bearing members  210  of the inner portion  205 . As axial load is applied to the system, the inner portion  205  will move relative to the outer portion  225  in the direction away from the applied force, as shown in  FIGS. 3 a  and 3 c   . As shown, the radial bearing assembly  200  allows continuous radial support throughout the range of axial motion allowed between the inner portion  205  and the outer portion  225 . 
       FIGS. 4 a -4 c    are views illustrating a radial bearing assembly  250 . The radial bearing  250  includes an inner portion in the form of a plurality of blocks  255  and an outer portion  275  having a plurality of bearing members  280 . The blocks  255  and the bearing members  280  are made from engineering materials. The blocks  255  are configured to be attached to the inner structure  135  (see  FIG. 2 ). To illustrate the function of the radial bearing assembly  250 , the inner portion  255  and the blocks  255  have been flattened in  FIGS. 4 a -4 c   . The outer portion  275  is positioned such that the bearing members  280  face the blocks  255 . As shown, the outer portion  275  includes one row of bearing members  280 . Under no axial load, the outer portion  275  would be positioned as shown in  FIG. 4 b   , riding over the center between the blocks  255 . As axial load is applied to the system, the portion  275  can move in an axial direction (see arrow  105  or arrow  115 ) to positions as shown in  FIGS. 4 a  and 4 c   . The radial bearing assembly  250  allows continuous radial support throughout the range of axial motion allowed between the blocks  255  and the outer portion  275 . 
       FIGS. 5 a -5 c    are views illustrating a radial bearing assembly  300 . The radial bearing  300  includes an inner portion  305  and an outer portion  325 . The inner portion  305  includes a plurality of bearing members  310 . As shown, the outer portion  325  is positioned such that the bearing members  310  of the inner portion  305  face the outer portion  325 . The outer portion  325  is a continuous piece of hardened material upon which the bearing members  310  ride. Having the continuous piece of hardened material as the outer portion  325  can reduce manufacturing costs and complexity. In one embodiment, the bearing members  310  are diamond buttons, and the continuous outer portion  325  is silicon or tungsten carbide. A fluid pathway  315  is formed between the inner portion  305  and the outer portion  325 . Fluid may be pumped through the fluid pathway  315  to lubricate, cool and/or clean the surfaces of the bearing members  310  and the outer portion  325 . 
     To illustrate the function of the radial bearing assembly  30 , the inner portion  305  and the outer portion  325  have been flattened in  FIGS. 5 b -5 c   . Under no axial load, the inner portion  305  would be positioned as shown in  FIG. 5 b   , riding over the continuous outer portion  325 . As axial load is applied to the system, the inner portion  305  will still be riding over the continuous outer portion  325 . In a similar manner as the other embodiments, the radial bearing assembly  300  allows continuous radial support throughout the range of axial motion allowed between the inner portion  305  and the outer portion  325 . 
       FIGS. 6 a -6 c    are views illustrating a radial bearing assembly  350 . The radial bearing assembly  350  includes an inner portion  355  and an outer portion  375 . The inner portion  355  includes a plurality of bearing members  360 . The outer portion  375  is a continuous piece of hardened material upon which the bearing members  360  ride. The outer portion  375  includes a plurality of grooves  380  formed along an inside surface thereof which are configured to act as a first fluid pathway. The first fluid pathway is interconnected with a second fluid pathway (e.g., gaps  365  between bearing members  360 ). Fluid may be pumped through the fluid pathways to lubricate, cool and/or clean the surfaces of the bearing members  360  and the outer portion  375 . In another embodiment, the inner portion  355  includes a plurality of grooves which may be used as the first fluid pathway. As illustrated, the inner portion  355  is a solid piece. In another embodiment, the inner portion  355  includes a longitudinal bore. Under no axial load and an axial load, the inner portion  355  will ride over the continuous outer portion  325 . In a similar manner as the other embodiments, the radial bearing assembly  350  allows continuous radial support throughout the range of axial motion allowed between the inner portion  355  and the outer portion  375 . 
       FIGS. 7 a -7 c    are views illustrating a radial bearing assembly  390 . For convenience, the components in the radial bearing assembly  390  that are similar to the components in radial bearing assembly  350  will be labeled with the same number indicator. As shown, the radial bearing assembly  390  includes the inner portion  355  and the outer portion  375 . The outer portion  375  includes a plurality of grooves  395  that are formed at an angle relative to a longitudinal axis of the outer portion  375 . In one embodiment, the angle of the grooves  395  is greater than 15 degrees, such as 30 degrees. In another embodiment, the angle of the grooves  395  is 45 degrees. Fluid may be pumped through the grooves  395  in the outer portion  375  to lubricate, cool and/or clean the surfaces of the bearing members  360  and the outer portion  375  as well as allow fluid energy to be converted into a rotational or tangential force. The generated force may be used to control the torsional stability of the radial bearing assembly  390  or in the case of a rotating application to support the rotational drive. 
       FIG. 8  is a view illustrating a lubrication system  320  for use with a radial bearing assembly. To minimize the wear of the mating surfaces in the radial bearing assembly, a fluid layer may be placed between the engineered surfaces and their mating race. In a sense, the surfaces of the radial bearing assembly hydroplane against each other, thus minimizing or eliminating wear. The lubrication system  320  may be used with each of the embodiments set forth herein. As shown, an inner portion  330  is disposed adjacent an outer portion  335  such that bearing members  340  on the portions  330 ,  335  face each other in a similar manner as described herein. Fluid compression ramps  345  are formed on the portions  330 ,  335  at the leading edge of the bearing members  340 . As the bearing members  340  approach each other, the fluid becomes trapped between opposing fluid compression ramps  345  and is forced onto the bearing surface of the bearing members  340 . Although there is some energy consumed by the fluid pumping, the increased bearing life can be important in many applications. 
       FIGS. 9 and 10  illustrate a rotating assembly  400  that includes the hybrid suspension system  100 .  FIG. 9  illustrates the rotating assembly  400  in the form of an electric generator in an off-position (e.g., without fluid flow), and  FIG. 10  illustrates the electric generator in an on-position (e.g., with fluid flow). The rotating assembly  400  includes a plurality of coils  405  and field magnets  410  arrayed around the inner and outer structures  135 ,  130 . The rotating assembly  400  further includes a plurality of vanes  415  disposed around the outer structure  130 . The rotational motion of the outer structure  130  relative to the inner structure  135  is caused by the fluid flow impinging on the plurality of vanes  415 . 
     As shown in  FIG. 9 , the outer structure  130  has moved in an axial direction illustrated by arrow  105  which causes the inner portion  170  of the radial bearing assembly  120  to move relative to the outer portion  180 . The reason the outer structure  130  has moved in the axial direction illustrated by arrow  105  is because the magnetic directions, strength and face-to-face spacing of the magnet members  140 ,  145 ,  150 ,  155  in the axial bearing assembly  110  have been selected and arranged such that the outer structure  130  is automatically offset relative to the inner structure  135  when the rotating assembly  400  is in the off position (e.g., without fluid flow). 
     As shown in  FIG. 10 , fluid flow  425  is applied to the rotating assembly  400 , which places the electric generator in the on-position. As the fluid flow  425  impinges on the plurality of vanes  415 , the outer structure  130  rotates relative to the inner structure  135 . As the outer structure  130  rotates, field magnets  410  alternately pass coils  405 , thus generating an electric current in the coils, and such current is then drawn off for other useful purposes. This same fluid flow  425  applies a force to the outer structure  130 , pushing it in the axial direction indicated by arrow  115 . The axial bearings  110  adjust their balance position, shifting the operating point on the radial bearings  120  to the direction indicated by arrow  115 . In  FIG. 10 , the radial bearings  120  are shown in their loaded position. In this manner the suspension system  100  can maintain the rotating assembly  400  through a wide range of variable flow conditions. To allow for the motion, the coils  405  in the rotating assembly  400  may be designed to be larger than the field magnets  410  to prevent any loss of electrical efficiency in the rotating assembly  400 . 
     As with any magnetic bearing system there is a potential for axial oscillation and resonance. In the case illustrated in  FIGS. 9 and 10 , this instability can be managed by regulating the rate at which the fluid can leave the interstitial space between the inner structure  135  and the outer structure  130 , by managing the size and the spacing of the gaps  365  between the bearing members  360  and/or the grooves  380  in the outer portion  375  (see  FIG. 6 a   ). For example, enlarging the widths of the gaps  365  and/or grooves  380  (or increasing the number of gaps  365  and/or grooves  380 ) fluid will flow more freely through the interstitial space between the inner structure  135  and the outer structure  130  which results in a decrease of damping of the axial oscillation and resonance of the axial bearing assembly  110 . In contrast, decreasing the widths of the gaps  365  and/or grooves  380  (or decreasing the number of gaps  365  and/or grooves  380 ) there will be less fluid flow through the interstitial space between the inner structure  135  and the outer structure  130  which results in an increase of damping of the axial oscillation and resonance of the axial bearing assembly  110 . In this manner, the axial oscillation and resonance of the magnetic axial bearing assembly  110  can be managed accordingly. 
     In the present examples, the outer structure  130  is designated as the rotating unit. In other embodiments, the outer structure  130  is fixed, allowing the inner structure  135  to rotate and placing the driving vanes on the inside of the inner structure  135 . 
     There are numerous applications which can be attached to the connecting structures  130 ,  135  between the bearing structures  110 ,  120 , including various sensor means. In an alternate embodiment, the suspension system  100  could also be used for linear axial support of a non-rotating structure. 
     In one aspect, a hybrid suspension system is provided. The hybrid suspension system includes a magnetic axial suspension, a radial suspension of engineered materials and interconnection structure allowing for useful work. In one embodiment, the radial suspension is diamond-on-diamond inserts. In another embodiment, the radial suspension consists of inserts running on a continuous race of hardened material. The continuous race is grooved to allow fluid to pass through the radial suspension. The continuous race has grooves machined at an angle to the axis to allow fluid pressure to alter the operating functionality. In a further embodiment, the radial suspension is diamond on silicon or tungsten carbide. In another embodiment, the radial suspension member has races of different widths allowing for motion in the axial direction without loss of function. In a further embodiment, fluid pumping ramps are used to maintain fluid on the bearing faces of the radial suspension. In another embodiment, the useful work is the generation of electricity. In a further embodiment, the useful work is a sensor means. In an additional embodiment, the application is linear axial support. In another embodiment, the application is support of rotating structures. In a further embodiment, the axial instability or oscillation is managed by regulating the flow of fluid in the suspension system. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.