Abstract:
A variable inlet guide vane assembly includes a plurality of circumferentially spaced inlet guide vanes mounted to pivot to change an angle of the guide vanes relative to an air flow. An actuator actuates the plurality of inlet guide vanes to change the angle, and is positioned radially inward of the inlet guide vanes.

Description:
BACKGROUND 
     This application relates to a set of inlet guide vanes which are provided with an actuator to vary the position of the vanes, and wherein the actuator is positioned radially inwardly of the vanes. 
     Gas turbine engines are known, and typically have a fan delivering air into a compressor section. The compressor compresses air and delivers it into a combustion section. The air is mixed with fuel and combusted in the combustion section, and products of that combustion pass downstream over turbine rotors. 
     Typically, the fan includes a rotor driving a plurality of rotor blades. Inlet guide vanes direct and control the air flow approaching the rotor blades. One known type of inlet guide vanes has a variable angle which is changed by an actuator. By changing the position of the inlet guide vanes, the direction the air approaches the rotor, as well as the volume of air approaching the rotor can be controlled. A single actuator actuates or changes the position of a plurality of circumferentially spaced inlet guide vanes. The actuators have typically been positioned at a radially outer portion of the gas turbine engine. 
     In addition, the actuators have typically rotated a ring to change the position of the inlet guide vanes. 
     SUMMARY 
     A variable inlet guide vane assembly includes a plurality of circumferentially spaced inlet guide vanes mounted to pivot to change an angle of the guide vanes relative to an air flow. An actuator actuates the plurality of inlet guide vanes to change the angle, and is positioned radially inward of the inlet guide vanes. 
     A gas turbine engine is also disclosed. 
     These and other features of the present invention can be best understood from the following specification and drawings, of which the following is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a gas turbine engine. 
         FIG. 2  shows a portion of an inlet guide vane. 
         FIG. 3  shows an inlet guide vane in an open position. 
         FIG. 4  shows the inlet guide vane in a closed position. 
         FIG. 5  shows a second embodiment. 
         FIG. 6  shows another feature of the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A gas turbine engine  10 , such as a turbofan gas turbine engine, circumferentially disposed about an engine centerline, or axial centerline axis  12  is shown in  FIG. 1 . The engine  10  includes a fan section  14 , compressor sections  15  and  16 , a combustion section  18  and a turbine section  20 . As is well known in the art, air compressed in the compressor  15 / 16  is mixed with fuel and burned in the combustion section  18  and expanded in turbine  20 . The compressor section  15  is a “low pressure” compressor, which feeds compressed air into the “high pressure” compressor  16 . The turbine  20  comprises alternating rows of rotary airfoils or blades  26  and static airfoils or vanes  28 . Similarly, the compressor sections  15 / 16  include rotor blades  30  and vanes  32 . In fact, this view is quite schematic. It should be understood that this view is included simply to provide a basic understanding of the sections in a gas turbine engine, and not to limit the invention. This invention extends to all types of turbine engines for all types of applications. 
     Features which are unique in this application are shown within the fan section of  FIG. 1 . As shown, an inlet frame  136  extends inwardly from a cowl  133 . A cone  137  is positioned forwardly of the inlet frame  136 , and fixed to it. An actuator  44  for actuating variable guide vanes  132  which are attached to the inlet frame  136  is also shown. As shown, the actuator  44  is positioned outwardly of a forward most end  139  of a shaft  141  which drives several rotors included in the gas turbine engine  10 . 
       FIG. 2  shows a portion of the fan section  14 . As known, a rotor carries rotor blades  130  which rotate with the rotor. 
     The rotor blades  130  are positioned to be adjacent inlet guide vanes  132 . The inlet guide vanes  132  are variable angle vanes, and are pivotally mounted such as shown at  50  and at  134 . The inlet guide vanes  132  may be positioned adjacent to fixed inlet frame  136 . The inlet frame is shown somewhat simplistically, and typically includes inner and outer cylindrical rings connected by a plurality of struts. The connection  200  of the actuator  44  to the inlet frame  136  is shown somewhat schematically, but may be at the cylindrical portion at the inner periphery. As can be appreciated from  FIG. 1 , the shaft which drives the rotor blades  130  would be positioned to the right of the forward most movement of the cam ring  42 . 
     An actuator  44  is mounted radially inwardly of the guide vanes  132  and fixed to inlet frame  136  at  200 . The inlet frame actuator  44  drives a rod  60  on a line C. The rod  60  has a threaded rod end  64 , and a nut  62  secures a cam ring  42 . The actuator  44  may be a hydraulic or electric actuator. As shown, a fluid or electric current supply  46  provides power or hydraulic fluid to the actuator  44 . 
     The cam ring  42  has a cam slot  43 . A cam roller  40  is positioned in the slot  43   
     A link  38  connects the roller  40  to the pivot point  134  on the inlet guide vane  132 . A spherical bearing maybe used between a link  38  and a roller  40  to prevent constraints to either the link or the roller during actuation 
     As shown in  FIG. 3 , if the cam ring  42  is extended, the link  38  is moved axially, and causes the vane  132  to pivot to a vane open position. Plural links  38  and vanes  132  are associated with the cam ring  42 . As can be seen in  FIG. 3  there are a plurality of rollers  40  mounted within a common cam slot  43 . 
     Alternatively, as shown in  FIG. 4 , when cam ring  42  is retracted, the link  38  pivots the vane  132  to a relatively closed position. 
     Another embodiment  190  is illustrated in  FIG. 5 . In embodiment  190 , the operation is generally the same as in the original embodiment. However, additional features have been introduced to prevent roller binding during cam actuation. Here the single cam is constructed in two pieces  202  and  204  to enable assembly of a roller cage  208  receiving the rollers  206 . Axial translation of the cam  202  and  204  is intended to translate the roller cage  208  and the rollers  206  in the axial direction. Simultaneous movement of the rollers  206  in the circumferential direction, forced by the links  38 , will also rotate the cage  208  about the engine centerline  12 , ensuring the centerlines of the rollers always intersect engine centerline preventing any potential binding of rollers  206  in the cam slot  43 . 
     The roller cage  208  is illustrated in  FIG. 6  having plurality of slots  210  to receive the rollers  206 . The roller cage  208  is preferred to have fine surface finishes where it makes contact with the cam slot  43  and rollers  206  during actuation. Roller cage  208  constructed with self-lubricating material such as, WEARCOMP™ or FIBERCOMP™ may help improve actuation. 
     A worker of ordinary skill in the art would recognize when it would be desirable to position the vane in the different positions. However, the use of the actuator and linkage assembly positioned radially inward of the guide vane allows for a smaller profile engine than the prior art which provided the actuator radially outward of the vanes. Further, the use of the axially moving cam ring is simpler to operate than the prior art rotating cam rings. 
     Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.