Abstract:
A mounting system for mounting an air-cooled device to a mount, the device having a mounting flange and a cooling air outlet radially inward of an outer periphery of the device, the mounting flange adapted to cooperate with the mount, where the mounting system has a cooling air exhaust collection shroud adapted to surround the device and at least a portion of the mount, the shroud having a discharge outlet.

Description:
RELATED APPLICATION 
   This is a Divisional application of U.S. application Ser. No. 10/321,572 filed Dec. 18, 2002, now U.S. Pat. No. 6,851,267. 

   TECHNICAL FIELD 
   The invention relates to a compact quick attach starter-generator mounting system including a cooling air exhaust collecting shroud enveloping connecting flanges releasably secured with a compact V-band clamp. 
   BACKGROUND OF THE ART 
   Starter-generators are mounted to gas turbine engines via an auxiliary or accessory gear box housing. The accessory gear box is generally driven by a tower shaft meshing with gears on the low pressure shaft of the engine and providing gear reduced power take off for various accessories such as oil pumps, fuel pumps and the starter-generator on an exterior portion of the engine. 
   During manufacture, testing and routine maintenance, the starter-generator is often removed and reinstalled. The starter-generator conventionally is an electro magnetic machine with a drive shaft extending out the end mounted to the accessory gear box with a splined shaft surface to engage the gear drive mechanism of the accessory gear box. The starter-generator also includes air cooling with an air inlet usually at an end opposite to the mounted end of the starter-generator such that cooling air passes through to remove excess heat. Air is exhausted with fans out of the opposite mounting end adjacent to the connection of the starter-generator to the accessory housing. 
   Substantial heat is produced by the starter-generator which must be dissipated by the unit&#39;s cooling air flow. The cooling air flow, in a conventional V-band held starter-generator installation, is discharged overboard through a separately located scroll air duct. Conventional installations additionally mount a scroll or collector either axially in line with the starter-generator or radially outward from the starter-generator. 
   Also, conventionally, the starter-generator is mounted to the accessory gear box with mating flanges that are secured with a V-band clamp that encircles the flanges and provides a quick release and detachment method. The starter-generator has a connecting flange which mates with the connecting flange of the accessory gear box usually having a beveled flange rear face and planar forward face to abut the planar face of the mating flange. The V-band groove engages the beveled rear surfaces of both abutting flanges and when tightened with a clamp mechanism, a wedging action on the interlocking beveled or sloped faces occurs to ensure a tight connection and a liquid impervious seal. 
   It is an object of the invention to improve upon conventional starter-generator (S/G) mounting systems to include quick release and quick install means for collecting and exhausting the S/G cooling air that is emitted from the starter-generator. 
   It is a further object of the invention to provide a means to collect exhausted cooling air while maintaining the starter-generator mounting system as a compact and quickly operated system due to the numerous maintenance activities that require removal and installation. 
   Further objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below. 
   DISCLOSURE OF THE INVENTION 
   The invention provides a mounting system, for installing a starter-generator to an accessory housing, where the starter-generator has a mounting end with a connecting flange and a cooling air outlet radially inward of a peripheral starter-generator housing edge, and where the accessory housing has a matching connecting flange radially inward of a peripheral accessory housing edge. The mounting system includes a cooling air outlet collection shroud enveloping the peripheral starter-generator housing edge and the peripheral accessory housing edge, the shroud having a discharge outlet. A V-band clamp releasably secures the connecting flanges together and is enveloped within the shroud in a compact mounting system that collects and discharges the exhausted cooling air. 

   
     DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings. 
       FIG. 1  is an axial cross-sectional view through a typical turbofan engine showing the general arrangement of conventional components including the accessory gear box located at the bottom left and the starter-generator mounted thereto with cooling air flow shown with arrows. 
       FIG. 2  is perspective detail view of the starter-generator mounted to an accessory gear box with partially transparent and cut away cooling air outlet collection shroud and underlying the V-band clamp joining abutting connecting flanges of the starter-generator and accessory gear box housing. 
       FIG. 3  is a sectional view along lines  3 — 3  of  FIG. 2  showing the V-band clamp attached to the connecting flanges with a surrounding annular air exhaust connection shroud with flared discharge outlet towards the bottom of the outlet. 
       FIG. 4  is a detailed sectional view along lines  4 — 4  of  FIG. 3 . 
   

   Further details of the invention and its advantages will be apparent from the detailed description included below. 
   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  shows an axial cross-section through a turbofan gas turbine engine. It will be understood however that the invention is applicable to any type of engine with a starter-generator such as a turboshaft, a turboprop, or auxiliary power unit. Application to other equipment is also possible. Air intake into the engine passes over fan blades  1  in a fan case  2  and is then split into an outer annular flow through the bypass duct  3  and an inner flow through the low-pressure axial compressor  4  and high-pressure centrifugal compressor  5 . Compressed air exits the compressor  5  through a diffuser  6  and is contained within a plenum  7  that surrounds the combustor  8 . Fuel is supplied to the combustor  8  through fuel tubes  9  which is mixed with air from the plenum  7  when sprayed through nozzles into the combustor  8  as a fuel air mixture that is ignited. A portion of the compressed air within the plenum  7  is admitted into the combustor  8  through orifices in the side walls to create a cooling air curtain along the combustor walls or is used for cooling to eventually mix with the hot gases from the combustor and pass over the nozzle guide vane  10  and turbines  11  before exiting the tail of the engine as exhaust. 
     FIG. 1  also shows at the bottom left corner the mounting of the accessory housing  12  and the starter-generator  13  with a cooling air exhaust collection shroud  14  according to the invention which will be described in detail below. In general, the starter-generator  13  provides: (a) startup power to the engine (to rotate the compressor until combustion is self-sustaining); and (b) electrical power generation by taking mechanical rotational power from the operating engine to power aircraft electrical systems and recharge batteries. 
   As shown in the detailed views of  FIGS. 2 ,  3  and  4 , the starter-generator  13  is attached to the accessory housing  12  with a mounting end that includes a starter-generator connecting flange  15  and the accessory housing  12  includes a matching accessory housing connecting flange  16 . A compact V-band clamp  17  releasably secures the connecting flanges  16  and  17  together. Of particular advantage, the V-band clamp  17  is of external diameter smaller than the internal diameter of the shroud  14 . As a result, the shroud  14  creates a cooling air collecting plenum  18  which completely surrounds the V-band clamp  17  and connecting flanges  15  and  16 . 
   As best seen in  FIG. 4 , the starter-generator  13  has a peripheral starter-generator housing edge  19  and the cooling air outlet  20  is radially inward of the starter-generator housing edge  19  enabling the shroud  14  to collect and contain the air passing from the starter-generator  13  through the cooling air outlet  20 . 
   The accessory housing  12  also includes a peripheral accessory housing edge  21  that is radially outward of the accessory housing connecting flange  16 . A relatively wide semicircular band  22  of the shroud  14  rests on cylindrical surfaces adjacent to the edges  19  and  21  and provides sufficiently tight seal to contain the cooling air exhaust which is directed to the discharge outlet  23  of the shroud  14  as indicated with arrows in the drawings. In the embodiment illustrated the shroud discharge outlet  14  is rectangular and flares outwardly downstream. Of course, depending on the specific configuration of the engine nacelle and starter-generator/accessory housing configuration, any subsequent ducting of exhaust air will be well within the scope of those familiar with this art. 
   As best seen in  FIG. 3 , in order to quickly attach and reinstall the shroud  14 , the shroud  14  is split along a joint  24  into a top semi-circular band  22  and a bottom portion  25  that includes a semi-circular cradle opening  26 . The bottom portion  25  therefore is shaped as a hollow rectangular box with the semi-circular cradle opening  26  on the upper end to seal around the bottom portions of the edges  19  and  21 . The top semi-circular band  22  and bottom portion  25  are joined along the joints  24  with abutting brackets  27  and  28  joined together with a simple bolt  29  and nut  30 . In the embodiment illustrated, the upper brackets  27  are formed together with a relatively narrow outer band  31  which results in a simplified construction and further reinforces the relatively wide semi-circular  22 . 
   Therefore, assembly of the starter-generator  13  onto the accessory housing  12  takes place by first offering the starter-generator up to the accessory gear box housing  12  and attaching the V-band clamp  17  to secure the abutting surfaces of the connecting flanges  15  and  16  together. Once secured, the two-piece cooling air exhaust collection shroud  14  is fitted upon the matching edges  19  and  21  of the starter-generator  13  and accessory housing  12 . Bolts  29  are secured within brackets  27  and  28  and clamped to provide an adequate air seal by tightening nuts  30 . Quick release couplings or other clamping mechanisms of course can be provided without departing from the scope of the invention. 
   Although the above description relates to a specific preferred embodiment as presently contemplated by the inventors, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein. It will be understood that certain terms used herein, such as “motor”, “starter”, “generator” etc and contextual and thus may refer generically to a device having a general configuration falling into one or more of these categories.