Engine Bearing Support

Abstract

A turbofan engine comprises an engine case. A gaspath extends through the engine case. A fan has a circumferential array of fan blades. A fan case encircles the fan blades radially outboard of the engine case. A plurality of fan case vanes extend outward from the engine case to the fan case. A front frame assembly includes a plurality of vanes extending radially across the gaspath. A transmission couples a shaft to a fan shaft to drive the fan. A bearing assembly couples the shaft to the front frame assembly. A bearing support extends aftward and radially inward from the front frame assembly to the bearing assembly.

1 . A turbofan engine comprising:
 an engine case;   a gaspath through the engine case;   a fan having a circumferential array of fan blades;   a fan case encircling the fan blades radially outboard of the engine case;   a plurality of fan case vanes extending outward from the engine case to the fan case;   a front frame assembly comprising a plurality of vanes extending radially across the gas path;   a shaft;   a transmission coupling the shaft to a fan shaft to drive the fan;   a bearing assembly coupling the shaft to the front frame assembly, the bearing assembly being a duplex bearing assembly; and   a bearing support extending aftward and radially inward from the front frame assembly to the bearing assembly.   
     
     
         2 . The engine of  claim 1  wherein:
 the shaft is a low pressure/speed spool shaft. 
 
     
     
         3 . The engine of  claim 1  wherein:
 the shaft is a flex-shaft. 
 
     
     
         4 . The engine of  claim 1  wherein:
 the bearing support has a main portion tapering at an angle of 10-45° off-axial. 
 
     
     
         5 . The engine of  claim 1  wherein:
 the bearing support has a main portion tapering at an angle of 10-35° off-axial. 
 
     
     
         6 . The engine of  claim 1  wherein:
 the bearing support extends partially within a hub of a compressor. 
 
     
     
         7 . The engine of  claim 6  wherein:
 the compressor is a low pressure compressor (LPC) having a single hub. 
 
     
     
         8 . (canceled) 
     
     
         9 . The engine of  claim 1  wherein:
 the duplex bearing comprises a forward bearing and an aft bearing; 
 the forward bearing has a center spaced apart from a center of the aft bearing by a bearing distance; and 
 the duplex bearing has a characteristic diameter, a ratio of said bearing distance to said characteristic diameter being between about 0.4:1 and about 3:1. 
 
     
     
         10 . The engine of  claim 1  wherein:
 a fan bearing assembly couples a forward hub structure to the fan shaft; and 
 the fan bearing assembly is a duplex tapered roller bearing assembly and a bellows spring engages an outer race of at least one of the bearings of the duplex tapered roller bearing. 
 
     
     
         11 . A method for assembling an engine, the method comprising:
 coupling a duplex bearing assembly to a shaft;   coupling a bearing support, that extends forward and radially outward from the bearing assembly, to a front frame assembly;   coupling a transmission to the shaft; and   coupling a fan to the transmission.   
     
     
         12 . The method of  claim 11 , wherein the fan has a circumferential array of fan blades, and wherein the step of coupling the fan to the transmission comprises coupling a fan case encircling the fan blades. 
     
     
         13 . The method of  claim 11 , wherein the step of coupling a fan to the transmission comprises coupling the fan to a fan drive shaft coupled to the transmission. 
     
     
         14 . The method of  claim 13 , wherein the step of coupling a fan to the transmission further comprises coupling, via a bearing, a fan rotor bearing support structure to the fan drive shaft and to the front frame assembly. 
     
     
         15 . A bearing support for mounting an engine front frame assembly to a bearing assembly, comprising:
 a forward mounting flange for mounting to the front frame assembly;   a web extending aftward and radially inward from the forward mounting flange;   a ring structure for mounting the bearing assembly, the web extending aftward and radially inward from the forward mounting flange to the ring structure, wherein:
 the forward mounting flange and the web are part of a single piece further comprising an aft mounting flange to which the ring structure is mounted; and 
 the bearing is a duplex bearing and the ring has an aft portion for mounting an aft bearing of the duplex bearing and a forward portion for mounting a forward portion of the duplex. 
   
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . The bearing support of  claim 15  wherein:
 the aft portion is a separate piece from the forward portion. 
 
     
     
         20 . The bearing support of  claim 19  wherein:
 the forward portion is forwardly cantilevered. 
 
     
     
         21 . A method for engineering the engine of  claim 1 , the method comprising:
 adding the duplex bearing to replace a non-duplex bearing and raise a rotor dynamic natural frequency of the engine.