Abstract:
A rotary machine includes a shaft extending through the rotary machine; a bearing positioned around the shaft; and an air deflector mounted on the shaft between the bearing and the shaft, wherein the air deflector has a first cylindrical body portion that is connected to a second cylindrical body portion with a ramp portion. A method for cooling a bearing positioned around a rotating shaft includes providing air to a cavity that surrounds a rotating shaft; deflecting the air towards an inner surface of a bearing that is positioned radially outward of the rotating shaft, wherein the air is deflected with an air deflector that is mounted on the rotating shaft; and flowing the air between an outer surface of the air deflector and the inner surface of the bearing.

Description:
BACKGROUND 
       [0001]    The present invention relates to rotary machines, and in particular, to an air deflector for an air cycle machine. 
         [0002]    Air cycle machines are used in environmental control systems in aircraft to condition air for delivery to an aircraft cabin. Conditioned air is air at a temperature, pressure, and humidity desirable for aircraft passenger comfort and safety. At or near ground level, the ambient air temperature and/or humidity is often sufficiently high that the air must be cooled as part of the conditioning process before being delivered to the aircraft cabin. At flight altitude, ambient air is often far cooler than desired, but at such a low pressure that it must be compressed to an acceptable pressure as part of the conditioning process. Compressing ambient air at flight altitude heats the resulting pressurized air sufficiently that it must be cooled, even if the ambient air temperature is very low. Thus, under most conditions, heat must be removed from air by the air cycle machine before the air is delivered to the aircraft cabin. 
         [0003]    To condition the air as needed, air cycle machines include a fan section, a compressor section, and a turbine section that are all mounted on a common shaft. The compressor receives partially compressed air from the aircraft and further compresses the air. The compressed air then moves through a heat exchanger and is cooled by the fan section. The air then moves through the turbine section where it is expanded for use in the aircraft, for example, for use as cabin air. The turbine section also extracts energy from the air and uses the energy to drive the fan section and the compressor section via the common shaft. 
         [0004]    Air cycle machines also include bearings that are positioned around the common shaft. The bearings are cooled by passing a cooling air flow through a cavity that is adjacent the bearing. The cooling air flow then exits the cavity and is discharged from the air cycle machine into an ambient. The cooling air flow is limited in that it can only cool the bearing using convective heat transfer. The cooling air flow is further limited in that the cooling air flow in the cavity flows through a center of the cavity, meaning a majority of the cooling air flow does not flow across a surface of the bearing. 
       SUMMARY 
       [0005]    A rotary machine includes a shaft extending through the rotary machine; a bearing positioned around the shaft; and an air deflector mounted on the shaft between the bearing and the shaft, wherein the air deflector has a first cylindrical body portion that is connected to a second cylindrical body portion with a ramp portion. 
         [0006]    A method for cooling a bearing positioned around a rotating shaft includes providing air to a cavity that surrounds a rotating shaft; deflecting the air towards an inner surface of a bearing that is positioned radially outward of the rotating shaft, wherein the air is deflected with an air deflector that is mounted on the rotating shaft; and flowing the air between an outer surface of the air deflector and the inner surface of the bearing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a cross-sectional view of an air cycle machine. 
           [0008]      FIG. 2A  is a perspective view of an air deflector. 
           [0009]      FIG. 2B  is a cross-sectional side view of the air deflector seen in  FIG. 2A . 
           [0010]      FIG. 3  is an enlarged cross-sectional view of the air deflector in a fan section of the air cycle machine. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In general, the present disclosure is an air deflector for use in a rotary machine. The air deflector can be mounted on a shaft between a bearing and the shaft to dissipate heat away from the bearing and out of the rotary machine. The air deflector includes a body with a bore running through the body in which a shaft can be positioned. The body of the air deflector includes a first body portion, a ramp portion, and a second body portion. The ramp portion is positioned between the first body portion and the second body portion. The ramp portion has a conical shape with an incline to force cooling air flowing around the air deflector outwards towards the bearing. The cooling air flowing across the bearing can cool the bearing with convective heat transfer. 
         [0012]      FIG. 1  is a cross-sectional view of air cycle machine  10 . Air cycle machine  10  includes fan section  12 , compressor section  14 , and turbine section  16  that are all mounted on shaft  18 . Shaft  18  rotates around central axis  20 . Fan section  12  includes fan blade  30 . Compressor section  14  includes compressor inlet  40 , compressor outlet  42 , and compressor nozzle  44 . Turbine section  16  includes turbine inlet  50 , turbine outlet  52 , and turbine nozzle  54 . Also shown in  FIG. 1  is heat exchanger  60 , housing  70 , bearing  72 , bearing sleeve  74 , bearing foil  76 , bearing journal  78 , cooling air flow  80 , cooling air flow inlet  82 , cavity  84 , opening  86 , and air deflector  100 . 
         [0013]    Shaft  18  is a rod, such as a titanium tie-rod, used to connect other components of air cycle machine  10 . Central axis  20  is an axis with respect to which other components may be arranged. 
         [0014]    Fan section  12  includes fan blade  30 . Fan section  12  is mounted on shaft  18 . Fan blades  30  rotate around shaft  18 . Fan section  12  typically draws in ram air from a ram air scoop or alternatively from an associated gas turbine or other aircraft component. Fan section  12  may also be used to draw air through heat exchanger  60 . 
         [0015]    Compressor section  14  includes compressor inlet  40 , compressor outlet  42 , and compressor nozzle  44 . Compressor section  14  is mounted on shaft  18 . Compressor inlet  40  is a duct through which air is received to be compressed. Compressor outlet  42  is a duct through which air can be routed to other systems after it has been compressed in compressor section  14 . Compressor nozzle  44  is a nozzle section that rotates through the air in compressor section  14 . In particular, compressor nozzle  44  is a rotor or impeller. 
         [0016]    Turbine section  16  includes turbine inlet  50 , turbine outlet  52 , and turbine nozzle  54 . Turbine section  16  is mounted on shaft  18 . Turbine inlet  50  is a duct through which air passes prior to expansion in turbine section  16 . Turbine outlet  52  is a duct through which air can be routed after it has been expanded to be used in other areas on an aircraft. For example, air can be routed out of turbine outlet  52  and into a cabin for use as cabin air. Turbine nozzle  54  is a nozzle section that extracts energy from air passing through turbine section  16 . In particular, turbine nozzle  54  is a rotor or impeller. Air passing through turbine section  16  drives the rotation of turbine section  16  and any attached components, including shaft  18 , fan section  12 , and compressor section  14 . 
         [0017]    Air is received in air cycle machine  10  at compressor inlet  40 . The air can be ram air from a ram air scoop or the air can be pulled into air cycle  10  using fan section  12  from an associated gas turbine or other aircraft component. The air passes through compressor section  14  where it is compressed with compressor nozzle  44  and then discharged out of compressor outlet  42 . From compressor outlet  42 , the air can pass through heat exchanger  60 . Fan section  12  may be used to draw air through heat exchanger  60 . Air that exits heat exchanger  60  is then routed into turbine inlet  50 . The air expands as it passes through turbine section  16  and it drives turbine nozzle  54  before it is discharged out of turbine outlet  52 . Air that is discharged out of turbine outlet  52  can then be routed to other parts of the aircraft, for example, for use as cabin air. 
         [0018]    Adjacent fan section  12  in air cycle machine  10  is housing  70 . Housing  70  forms an outer portion of air cycle machine  10 . Bearing  72  is positioned between shaft  18  and housing  70 . Bearing  72  is a foil bearing in the embodiment shown in  FIG. 1 . Bearing  72  includes bearing sleeve  74 , bearing foil  76 , and bearing journal  78 . Bearing foil  76  is positioned between bearing sleeve  74  and bearing journal  78 . Bearing sleeve  74  forms an outer surface of bearing  72  and bearing journal  78  forms an inner surface of bearing  72 . The inner surface of bearing journal  78  faces shaft  18 . Air deflector  100  is mounted on shaft  18  between bearing  72  and shaft  18  to dissipate heat out of bearing  72 . 
         [0019]    Cooling air flow  80  is bled from the air being routed from heat exchanger  60  to turbine inlet  50 . Cooling air flow  80  is routed through cooling air flow inlet  82  and through air cycle machine  10  to cavity  84 . Cavity  84  is an open area surrounding shaft  18  that is defined by fan section  12  and turbine section  16 . Air deflector  100  is positioned in cavity  84  adjacent fan blade  30 . Cooling air flow  80  will flow through cavity  84  and will pass around air deflector  100  to cool bearing  72 . Cooling air flow  80  will then exit through opening  86  that is formed between housing  70  and fan blade  30  and will be discharged into an ambient out of air cycle machine  10 . 
         [0020]      FIG. 2A  is a perspective view of air deflector  100 .  FIG. 2B  is a cross-sectional side view of air deflector  100  seen in  FIG. 2A . Air deflector  100  includes body  102  and bore  104 . Air deflector  100  further includes first body portion  110 , ramp portion  112 , and second body portion  114 . Also shown in  FIGS. 2A-2B  are first diameter D 1 , second diameter D 2 , and slope S. 
         [0021]    Air deflector  100  includes body  102 . Air deflector  100  can be made out of thermally conductive materials or thermally insulating materials. This can include metallic materials, plastic materials, ceramic materials, or any other suitable material. Bore  104  extends axially through body  102  with a first opening at a first end of body  102  and a second opening at a second end of body  102 . Bore  104  runs through air deflector  100  so that a shaft or other part can be positioned in bore  104  of air deflector  100 . 
         [0022]    Body  102  of air deflector  100  includes first body portion  110 , ramp portion  112 , and second body portion  114 . First body portion  110  has a cylindrical shape with first diameter D 1 . A first end of first body portion  110  forms the first end of air deflector  100 , and a second end of first body portion  110  is connected to a first end of ramp portion  112 . Ramp portion  112  has a conical shape and extends from first diameter D 1  to second diameter D 2 . Ramp portion  112  has an incline with slope S. The second end of ramp portion  112  is connected to a first end of second body portion  114 . Second body portion  114  is cylindrically shaped with second diameter D 2 . A second end of second body portion  114  forms the second end of body  102 . 
         [0023]    Air deflector  100  can be used in any rotary machine that has a shaft and a bearing positioned around the shaft. This can include air cycle machines and other turbine and motor driven compressors and fans. Air deflector  100  is advantageous, as ramp portion  112  of air deflector  100  forces cooling air to flow closer to a surface of a hot part that is positioned around air deflector  100 . The cooling air flow will absorb heat from the hot part as it flows across a surface of the hot part to cool the hot part. Air deflector  100  is further advantageous, as it is low weight and is easy and cost effective to manufacture. 
         [0024]      FIG. 3  is an enlarged cross-sectional view of air deflector  100  in fan section  12  of air cycle machine  10 . The portion of air cycle machine  10  shown in  FIG. 3  includes fan section  12  (including fan blade  30 ), shaft  18 , housing  70 , bearing  72 , bearing sleeve  74 , bearing foil  76 , bearing journal  78 , cavity  84 , opening  86 , and air deflector  100 . Air deflector  100  further includes body  102 , including first body portion  110 , ramp portion  112 , and second body portion  114 . 
         [0025]    Air cycle machine  10  includes fan section  12  that is mounted on shaft  18 . Shaft  18  is a common shaft that runs through air cycle machine  10  and that rotates around central axis  20 . Fan section  12  includes fan blade  30  that rotates with shaft  18  around central axis  20 . Adjacent fan blade  30  is housing  70 . Housing  70  forms an outer portion of air cycle machine  10 . 
         [0026]    Positioned between shaft  18  and housing  70  is bearing  72 . Bearing  72  is a foil bearing that includes bearing sleeve  74 , bearing foil  76 , and bearing journal  78 . Bearing foil  76  is positioned between bearing sleeve  74  and bearing journal  78 . Bearing sleeve  74  forms an outer surface of bearing  72  and bearing journal  78  forms an inner surface of bearing  72 . The inner surface of bearing journal  78  faces shaft  18 . Cavity  84  is formed between shaft  18  and the inner surface of bearing journal  78 . Cooling air flow can be routed through cavity  84  to cool bearing  72 . The cooling air flow can then exit through opening  86 . Opening  86  is an opening through bearing journal  78  between fan blade  30  and housing  70 . After cooling air flows through opening  86  it can be discharged from air cycle machine  10  into an ambient. 
         [0027]    Positioned in cavity  84  around shaft  18  is air deflector  100 . Air deflector  100  is mounted on shaft  18  so that it rotates with shaft  18  around central axis  20 . Air deflector  100  includes body  102  with first body portion  110 , ramp portion  112 , and second body portion  114 . Ramp portion  112  is positioned between first body portion  110  and second body portion  114 . Ramp portion  112  has a conical shape with an incline to force cooling air flowing through cavity  84  into an area between second body portion  114  and the inner surface of bearing journal  78 . 
         [0028]    Air deflector  100  transfers heat out of bearing  72  by forcing the cooling air closer to the inner surface of bearing journal  78 . This allows for convective heat transfer, as heat is being transferred into the air that is flowing across the inner surface of bearing journal  78 . The cooling air flow that is flowing through cavity  84  between the second body portion  114  of air deflector  100  and bearing journal  78  flows through opening  86  where it is discharged out of air cycle machine  10 . This discharges heat from bearing  72  into an ambient through the cooling air flow. 
         [0029]    Without air deflector  100 , bearing  72  would be cooled by flowing air through cavity  84 . That cooling method would be inefficient, as cooling air flowing through cavity  84  would have a large area through which it flows. A majority of the cooling air would flow through the center of cavity  84  between shaft  18  and journal bearing  68 . This would make the cooling method inefficient, as a majority of the cooling air would not come into contact with the inner surface of bearing journal  78 . 
         [0030]    Air deflector  100  is advantageous over prior art cooling systems, as the cooling air flow is forced into a smaller area between second body portion  114  of air deflector  100  and the inner surface of bearing journal  78 . This increases the effectiveness and efficiency of the convective heat transfer, as more cooling air flow is coming into contact with the inner surface of bearing journal  78 . Air deflector  100  thus improves the cooling of bearing  72  to make bearing  72  more reliable. 
         [0031]    Air deflector  100  also provides several advantages for air cycle machine  10 . First, air deflector  100  makes air cycle machine  10  more effective, as less cooling air flow is needed to cool bearing  72 . This means less cooling air flow needs to be routed away from the main flow path through air cycle machine  10 , thus improving the overall efficiency of air cycle machine  10 . Second, as more air is kept in the main flow path through air cycle machine  10 , the heat exchanger has to do less work. This means the size and weight of the heat exchanger can be reduced. The improved efficiency and effectiveness of air cycle machine  10  with air deflector  100  outweighs any concerns about the weight or cost of adding air deflector  100  to air cycle machine  10 . Air deflector  100  greatly improves the thermodynamic performance of air that is flowing through air cycle machine  10 . 
         [0032]    While the invention has been described with reference to an exemplary embodiment(s), 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 invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.