Patent Publication Number: US-8979490-B2

Title: Fan inlet diffuser housing riveted center body retention

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to fan inlet diffuser housings for air cycle machines, and more specifically, to systems and methods for retaining a center body in a fan inlet diffuser housing by mechanical fasteners. 
     In modern commercial aircraft, an air cycle machine (ACM) is provided to suitably condition air to be supplied to the cabin or cockpit or other locations for occupant comfort. Typically, such ACMs condition a flow of pressurized air, for example bleed air from the aircraft engine, by not only regulating the pressure of the air to a desired level for cabin pressurization, but also by cooling and dehumidifying the air. The flow of compressed bleed air to be conditioned, which can be in excess of 150° C., is first passed through a compressor section of the ACM where it is further cooled causing condensation of moisture in the air, thereby dehumidifying the air. The dehumidified air is then expanded through a turbine section of the ACM to reduce the pressure to a desired pressure level for delivery to its point of use, (e.g. the aircraft passenger or pilot cabin). ACMs include Fan Inlet Diffuser Housings (FIDHs) to receive the flow of the hot intake air. In order to reduce noise in the FIDH, components of the FIDH are in a bonded configuration. In the presence of the heated air, the bonds can release. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Exemplary embodiments include a fan inlet diffuser housing system, including an air cycle machine, a housing coupled to the air cycle machine, an inlet fan disposed on the air cycle machine and configured to pass inlet air into the fan inlet diffuser housing, a center tube disposed in the housing, a diffuser cone disposed around the center tube, an inboard strut supporting the inner tube within the diffuser cone, and an outboard strut supporting the inner tube within the diffuser cone, the outboard strut being integral with the diffuser cone, wherein the inboard strut is coupled to the inner tube with a first plurality of mechanical fasteners, and the outboard strut is coupled to the inner tube with a second plurality of mechanical fasteners. 
     Additional exemplary embodiments include a fan inlet diffuser housing apparatus, including a housing, a center tube disposed in the housing, a diffuser cone disposed around the center tube, an inboard strut supporting the inner tube within the diffuser cone, and an outboard strut supporting the inner tube within the diffuser cone, the outboard strut being integral with the diffuser cone, wherein the inboard strut is coupled to the inner tube with a first plurality of mechanical fasteners, and the outboard strut is coupled to the inner tube with a second plurality of mechanical fasteners. 
     Further exemplary embodiments include a method for supporting an inner tube in a diffuser cone of a fan inlet diffuser housing, the method including mechanically fastening three outer diameter walls of an inboard strut to the diffuser cone and the inner tube, mechanically fastening three inner diameter walls of the inboard strut to the inner tube and mechanically fastening three inner diameter walls of an outboard strut to the inner tube, the outboard strut being integral with the diffuser cone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a fan inlet diffuser housing system in accordance with one embodiment. 
         FIG. 2  illustrates further details of the fan inlet diffuser housing of  FIG. 1 . 
         FIG. 3  is a front view of an inboard strut of  FIGS. 1 and 2 . 
         FIG. 4  is a front view of an outboard strut of  FIGS. 1 and 2 . 
         FIG. 5  is a cross-section of a center tube of a diffuser section that illustrates mechanical fastener locations of inboard/outboard struts thereto. 
         FIG. 6  is a partial cross-section of a diffuser cone that illustrates mechanical fastener locations between the diffuser cone and an inboard strut. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a FIDH system  100  in accordance with one embodiment. The FIDH system  100  includes an ACM  105  coupled to a FIDH  115 . The system  100  further includes an inlet fan  110  that passes the inlet air into the FIDH  115 . Airflow is represented by arrow  150 . The FIDH  115  includes a housing  120 , a diffuser cone  125  disposed within the housing  120  and a center tube (center body)  130  disposed within the diffuser cone  125 . The center tube  130  is disposed within the diffuser cone  125  via an inboard strut  135  and an outboard inboard strut  140 . 
       FIG. 2  illustrates further details of the housing  120 , the diffuser cone  125 , the center tube  130 , the inboard strut  135  and outboard strut  140  of  FIG. 1 . As described further herein, the center tube  130  is mechanically fastened to the inboard and outboard struts  135 ,  140  via mechanical fasteners such as rivets at locations  136 ,  141 , respectively. In addition, the inboard strut  135  is mechanically fastened to the diffuser cone  125  via mechanical fasteners, such as rivets at location  137 . In the illustrated embodiment, the outboard strut  140  is integrally coupled to the diffuser cone  125 . In another embodiment, the outboard strut  140  can be mechanically fastened to the diffuser cone  125  via mechanical fasteners, such as rivets. As described herein, conventional methods to connect similar struts to similar diffuser cones, and similar center tubes to similar struts include material binding that can fail under the heated air. 
       FIG. 3  illustrates a front view of the inboard strut  135  of  FIGS. 1 and 2 .  FIG. 4  illustrates a front view of the outboard strut  140  of  FIGS. 1 and 2 . The locations  136 ,  141  in which the inboard strut  135  and the outboard strut  140 , respectively, are coupled to the inner tube  130  are illustrated further in  FIG. 5 . The location  137  in which the inboard strut  135  is coupled to the diffuser cone  125  are illustrated further in  FIG. 6 . As best seen in  FIGS. 3 and 4 , the inboard and outboard struts  135 ,  140  each have an inner diameter wall  138 ,  142  and an outer diameter wall  139 ,  143 , respectively. As such, it can be appreciated that the inner diameter walls  138 ,  142  at the locations  136 ,  141  are mechanically fastened to the inner tube  130 . It can further be appreciated that the outer diameter walls  139  at the location  137  is mechanically fastened to the diffuser cone  125 . 
     Referring to  FIG. 5 , details of the locations  136 ,  141  where the inboard and outboard struts  135 ,  140  are coupled to the inner tube  130  are now described. In one embodiment, the inner diameter walls  138 ,  142  are mechanically fastened to an outer surface  131  of the inner tube  130  by mechanical fasteners  500 . In one embodiment, the mechanical fasteners  500  are rivets having a head  505  and shaft  510 . In one example, the rivet can be a flush rivet in which the head  505  is flush with the inner diameter walls  138 , 142  of the inboard and outboard struts  135 ,  140 . When the rivets are inserted into the inner tube  130 , the shaft  510  becomes upset during installation as known when rivets are installed. It can be appreciated that the upset shaft  510  is not present in the airflow around the inner tube  130 . In one embodiment, the inner tube  130  can include acoustical foam  132  disposed therein to reduce any acoustical noise of the airflow across the mechanical fasteners  500 . As such, in one embodiment, the orientation of the mechanical fasteners  500  with the upset end of the mechanical fastener  500  facing out of the airflow into the acoustical foam  132  thereby provides a secure coupling between the inboard and outboard struts  135 ,  140  and the inner tube  130 . Furthermore, at least two mechanical fasteners  500  are implemented at each of the respective locations  136 ,  141  in order to be spaced evenly along the inner diameter walls  138 ,  142 . The total number of mechanical fasteners  500  for each of the inboard and outboard struts  135 ,  140  at the locations  136 ,  141  is six. Of course, in other embodiments, the number and locations of the rivets could be varied. 
     Referring to  FIG. 6 , details of the location  137  where the inboard strut  135  is coupled to the diffuser cone  125  are now described. In one embodiment, the outer diameter walls  139  are mechanically fastened to an inner surface  126  of the diffuser cone  125  by mechanical fasteners  500 . In one embodiment, the mechanical fasteners  500  are rivets having a head  505  and shaft  510 . In one example, the rivet can be a flush rivet in which the head  505  is flush with the outer diameter walls  139  of the inboard strut  135 . When the rivets are inserted into the diffuser cone  125 , the shaft  510  becomes upset during installation as known when rivets are installed. It can be appreciated that the upset shaft  510  is not present in the airflow adjacent the inner surface  126  of the diffuser cone  125 . In one embodiment, the diffuser cone  125  can include acoustical foam  127  therein to reduce any acoustical noise of the airflow across the mechanical fasteners  500 . As such, in one embodiment, the orientation of the mechanical fasteners  500  with the upset end of the mechanical fastener  500  facing out of the airflow into the acoustical foam thereby provides a secure coupling between the inboard strut  135  and the diffuser cone  125 . Furthermore, at least four mechanical fasteners  500  are implemented at each of the respective locations  137  in order to be spaced evenly along the outer diameter walls  139 . The total number of mechanical fasteners  500  for the inboard strut at the location  137  is twelve. Of course, the number and spacing of the mechanical fasteners  500  could be varied as needed. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.