Abstract:
A heat exchange system for use in fluid operated equipment to provide air and working fluid heat exchanges to cool the working fluid in airstreams on a stream side of a wall. An actuator is mounted to be substantially located on a side of the wall opposite the stream side thereof having a positionable motion effector. A heat exchanger core having a plurality of passageway structures therein to enable providing the working fluid to, and removal therefrom. The heat exchanger core is mounted on the motion effector so as to be extendable and retractable thereby through the opening for selected distances into that region to be occupied by the airstreams.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a divisional application of U.S. patent application Ser. No. 11/378,166, entitled “AIR-OIL HEAT EXCHANGER,” filed Mar. 17, 2006 by Frederick M. Schwartz et al. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to lubrication systems for turbine engines and for associated equipment, and more particularly, to air and lubricant heat exchangers for use in maintaining desired temperatures of the lubricants in such engines and equipment. 
     Lubrication systems for turbine engines, such as a turbofan engine, and for associated equipment, such as an integrated drive generator, provide pressurized lubricant, an oil, to lubricate, cool and clean the engine main bearings, gear box gears, and the like, and again for the lubrication of bearings and other parts in equipment associated with such turbine engines. During such lubrications, heating of the lubricant is caused to occur due to mechanical energy losses in the lubricated apparatus. Thermal management of such lubricants is very important for continued successful operation of such lubrication systems in the apparatus lubricated thereby. 
     The amount of heat necessary to be ejected from lubricants in such systems is increasing because of the use of larger electrical generators, for instance, in aircraft turbine engines due to increasing consumption of electrical power in the aircraft powered thereby, and because of the advances in aircraft turbine engines such as the use of geared turbofans for such aircraft with a large fan-drive gearbox. Despite the added heat generated by the such modified and expanded equipment, the necessary lubricating oil operating temperature ranges to provide satisfactory lubricating performance have not changed for the most part and, in some instances, the upper operating temperature limits have been reduced. 
     The lubrication system for a turbofan engine in an aircraft typically has a first heat exchanger providing lubricating oil passing through passageways in that heat exchanger that is cooled by the fuel stream flowing past these passageways. This arrangement permits the lubricating oil to reject heat therein to the fuel in the aircraft thereby heating that fuel to help prevent the occurrence of icing therein. Because in some flight situations more heat is generated in the lubricating oil than is needed for warming the fuel, a portion of the lubricating oil can be forced to bypass the heat exchanger for the lubricating oil and the fuel and be directed to a further heat exchanger, where the heat therein is transferred to the air in the secondary airstream provided by the fan of the turbofan engine. 
     In a typical arrangement, a duct is provided in the fan cowling through which a portion of the airstream is diverted, and the air and lubricating oil heat exchanger is placed in this duct so that the lubricating oil passing through passageways in that heat exchanger is cooled by the duct airstream flowing past these passageways in the exchanger. If such additional cooling of the oil is not needed in a flight situation, the lubricating oil can again be forced to bypass this air and lubricating heat exchanger. 
     However, the fan airstream diverted to pass through the lubricating oil and air heat exchanger in such duct systems always flows through that exchanger. Further, the duct cross sectional area and the heat exchanger passageways exposure to the duct airstream must always be sufficiently large to assure sufficient heat transfer to the airstream in the most difficult flight conditions encountered, and so are much greater in size than what is required in the great majority of flight conditions. Thus, such an air and lubricating oil heat exchanger duct based system continually leads to thrust losses in the turbofan engine despite being unnecessary for cooling the lubricating oil in many flight situations. Hence, there is a strong desire for an air and lubricating oil heat exchanger system that reduces such thrust losses and also reduces the volume required therefore in the more compact spaces in advanced turbofan engines. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a heat exchange system for use in operating equipment in which a working fluid is utilized in providing its operations with the heat exchange system providing air and working fluid heat exchanges to cool the working fluid at selectively variable rates in airstreams on a stream side of a wall provided with the equipment, and on which the equipment may be mounted. An actuator is mounted to be substantially located on a side of the wall opposite the stream side thereof having a positionable motion effector therein that can be moved to selected positions with respect to an opening in the wall. A heat exchanger core has a plurality of passageway are coupled to an input conduit at one end thereof and coupled to an output conduit at an opposite end thereof to enable providing the working fluid to, and removal from, interiors of the passageway structures through interiors of the input and output conduits. The heat exchanger core is mounted on the motion effector so as to be extendable thereby through the opening for selected distances into that region to be occupied by the airstreams on the stream side of the wall, and selectively retractable from those distances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a partially cut away side view of an embodiment of the present invention, and 
         FIG. 2  shows a partially cut away front view of the embodiment of the present invention shown in  FIG. 1 . 
         FIG. 3  shows a partial cut away side view of a turbofan engine illustrating positioning of air-oil heat exchanger  10  and inner fan duct wall  11 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show partially cut away side and front views, respectively, of a partially deployed air-oil heat exchanger,  10 , mounted on a portion of an inner fan duct wall,  11 , provided in a turbofan engine which is otherwise omitted from this figure. A flange,  12 , holds heat exchanger  10  against the inner engine core side of wall  11  so that the deployable portion of heat exchanger  10  can be deployed in the engine fan airstream through an opening,  13 , in wall  11  that is on the opposite side of that wall from the engine core side thereof. Flange  12  is part of a metal container,  14 , for heat exchanger  10  provided on the engine core side of wall  11 . 
     A further bracket,  15 , located primarily on the airstream side of wall  11  and fastened to container  14  through opening  13  holds that container against wall  11 . Bracket  15  has triangular shaped sidewalls across from one another with an opening therebetween to the interior of container  14  below that bracket on the upstream side of opening  13  on the left in  FIG. 1 , i.e. the front side of heat exchanger  10 . Two further triangular shaped sidewalls are provided in bracket  15  across from one another with an opening therebetween to the interior of container  14  below on the downstream side of opening  13  on the right in  FIG. 1 . These two openings in bracket  15  permit a portion of the fan airstream to enter into the interior of container  14  on the upstream side and to exit from container  14  on the downstream side thereof whenever the deployable portion of heat exchanger  10  is at least partly deployed in the engine fan airstream through an opening  13 . The triangular shaped sidewalls on the upstream side help guide that portion of the airstream into the interior of container  14  whenever the deployable portion of heat exchanger  10  is at least partly deployed in the engine fan airstream by limiting to an extent airflow around that deployed portion of heat exchanger  10 . 
     The deployable portion of heat exchanger  10  is involves primarily a heat exchanger core,  20 , having a substantial number of spaced apart passageway structures,  21 , including air downstream passageway structures,  21 ′, and air upstream passageway structures,  21 ″, connected between two passageway end members including a lower passageway end member,  22 , and an upper passageway end member,  23 , held together by a frame,  24 , so as to have access to the open interiors of these passageway structures from the open interiors of corresponding channels in the passageway end members. Thus, the open interiors of air downstream passageway structures  21 ′, at the upper ends thereof in the figures, are joined to the open interiors of air upstream passageway structures  21 ″, at the upper ends thereof in the figures, by appropriate channels provided in upper passageway end member  23  so that the working fluid, or oil, passing through air downstream passageway structures  21 ′ can next pass through air upstream passageway structures  21 ″. 
     The open interiors of air downstream passageway structures  21 ′ at the opposite, lower ends thereof are joined to the open interior of core oil inlet connector stub,  25 , by channels in lower passageway end member  22 . Similarly, the open interiors of air upstream passageway structures  21 ″ at the opposite, lower ends thereof are joined to the open interior of core oil outlet connector stub,  26 , as seen in  FIG. 2 , by other channels in lower passageway end member  22 . Thus, if heat exchanger core  20  is exposed to the engine fan airstream, that air will pass between passageway structures  21 , first through air upstream passageway structures  21 ″ positioned toward the front, or upstream side, of heat exchanger  10 , and then through air downstream passageway structures  21 ′ positioned toward the rear of heat exchanger  10 . Oil will enter heat exchanger core  20  through core oil inlet connector stub  25  to pass lower passageway end member  22  as shown by the bolded block arrow pointing to the left in  FIG. 1  therefrom at the bottom of core  20 . Connections to air downstream passageway structures  21 ′ results in the oil at the greatest temperatures then passing first through air downstream passageway structures  21 ′ in core heat exchanger  20  to be cooled and then reach upper passageway end member  23  as shown by the bolded block arrows on the right pointing upward, and then the two pointing leftward at the top of the core, in  FIG. 1 . 
     This oil then next passes through air upstream passageway structures  21 ″ connected to upper passageway end member  23  to be further cooled as shown by the bolded block arrows on the left pointing downward, to reach lower passageway end member  22 . The cooled oil then exits heat exchanger core  20  via core oil outlet connector stub  26 , seen only in  FIG. 2 , as shown by the bolded block arrows pointing to the right in  FIG. 1  at the bottom of core  20 . These flow and position arrangements for the oil and air flows assures that there is always a positive transfer of heat from the oil to the airstream at both air downstream passageway structures  21 ′ and the air upstream passageway structures  21 ″. 
     The oil from the turbofan engine lubrication system, or the integrated drive generator lubrication system, or the fluid from the lubrication or other working fluid systems in other equipment, reaches heat exchanger core  20  therefrom through interconnections from tubing or piping in such systems that are typically removably interconnected to an exchanger oil inlet connector stub,  27 , seen in  FIG. 2 , mounted on the side of container  14  of heat exchanger  10 . Such oil or working fluid is returned to such systems from heat exchanger  10  through an exchanger oil outlet connector stub,  28 , also mounted on frame  14  of heat exchanger  10  as seen in  FIG. 2 . 
     One arrangement for connecting exchanger oil inlet connector stub  27  on frame  14  to core oil inlet connector stub  25  on heat exchanger core  20  is shown in  FIGS. 1 and 2  using two tube or hose sections,  29  and  30 , which are joined to one another by a swivel coupling,  31 . Section  29  is joined with core oil inlet connector stub  25  by another swivel coupling,  32 , and section  30  is joined with exchanger oil inlet connector stub  27  by a further swivel coupling,  33 . These swivel couplings each have two sections both having an outer wall about an open space within open to that of the other, and with these sections being connected to each other so as to allow them to rotate with respect to one another. Each of these sections has a corresponding fitting providing an opening therethrough to the space within that allows each section to be connected to a corresponding external conduit for transferring fluid to and from the interior space thereof. 
     Similarly, an arrangement for connecting exchanger oil outlet connector stub  28  on the same side of container  14  to core oil outlet connector stub  26  on heat exchanger core  20  is shown in  FIGS. 1 and 2  also uses two tube or hose sections,  34  and  35 , which are joined to one another by a swivel coupling,  36 . Section  34  is joined with core oil outlet connector stub  26  by another swivel coupling,  37 , and section  35  is joined with exchanger oil outlet connector stub  28  by yet another swivel coupling,  38 . Alternatively, the two tube or hose sections with swivel couplings could have flexible hoses and clamped slip-on couplings substituted therefor, or some other flexible conduit arrangement could alternatively be used. 
     Heat exchanger core  20  can be selectively deployed in selected frontal area fraction thereof for a turbofan engine in the engine fan airstream above wall  11 , in the figures, using alternatively an electrical, hydraulic or pneumatic motor,  40 , (an electric motor being shown in  FIGS. 1 and 2 ) to raise a platform upon which core  20  is mounted or, as alternatively shown in  FIGS. 1 and 2 , to rotate threaded jackscrews,  41  and  42 , engaged with threaded nuts,  43  and  44 , mounted directly across from one another on the opposite sides of core frame  24 . A gearbox,  45 , has one end of the rotor shaft (unseen in the figures) of motor  40  extending therein to engage suitable gearing (unseen in the figures) to rotate jackscrew  41  in response to the rotation of that rotor shaft within attached core frame nut  43 . Similarly, a gearbox,  46 , has the other end of the rotor shaft (unseen in the figures) of motor  40  extending therein to engage suitable gearing (unseen in the figures) to rotate jackscrew  42  in response to the rotation of that rotor shaft within attached core frame nut  44 . 
     In this arrangement, rotation of the motor rotor shaft in one direction results in raising heat exchanger core  20  toward and into the fan engine airstream above wall  11  in the figures a selected distance depending on the amount of shaft rotation. In the same manner, rotation of that shaft in the opposite direction results in lowering core  20  toward and back into the fan engine compartment a selected distance again depending on the amount of shaft rotation in this opposite direction. The electrical power to cause selected rotations of the rotor shaft of motor  40  is selectively supplied to an electrical connector,  47 , mounted on the side of container  14  to which an electrical wiring cable,  48 , extending from motor  40 , is connected. 
     Heat exchanger core  20 , when fully retracted into container  14 , to a significant degree seals the engine compartment on the lower side of wall  11  in the figures from the engine fan airstream above that wall. A core cover,  50 , formed of materials similar to that used in providing wall  11 , is provided affixed to the top of core frame  24  to achieve this degree of sealing. The outer surface of core cover  50  is shaped to be flush with, and to conform to the curvatures and contours of, the adjacent surface contours of wall  11 . Thus, the outer surface of the engine compartment, with heat exchanger  10  mounted within this compartment, is presented to the engine fan airstream as a smooth surface when core  20  is fully retracted into container  14  except for the narrow edges of the triangular shaped sidewalls of bracket  15  facing the airstream. This configuration with core  20  being fully retracted thereby minimizes any airstream disturbance in conditions in which heat exchanger  10  is not being used to cool oil flowing through it from exchanger oil inlet connector stub  27  to exchanger oil outlet connector stub  28 . 
     The upstream side of core cover  50 , however, has a sculpted front to form a front inner surface,  51 , facing the engine fan airstream when core  20  is deployed to some extent in that airstream. Front inner surface  51  follows the contour of the outer surface of core cover  50  extending right and left as seen in  FIG. 2 , and begins at the upstream front edge of core cover  50  paralleling that outer surface thereof but then curves downward toward the engine compartment as seen in  FIG. 1 . Such a downward curving front inner surface directs a portion of the engine fan airstream downward through the upstream opening in bracket  15  into container  14  so that part of it passes more or less straight through the part of core  20  directly exposed to this airstream when that core is deployed to some extent therein. The remaining part of this airstream portion directed into container  14  passes through the part of core  20  that is still within container  14 . After passing through core  20 , the diverted portion thereof flows out of container  14  through the downstream opening in bracket  15  to rejoin the engine fan airstream. These flow paths of the portion of engine fan airstream when core  20  is partially deployed in that airstream are indicated by the light line extended block arrows drawn through core  20  in  FIG. 1 . 
     Thus, the entirety of passageway structures  21  in heat exchanger core  20  are subjected to the diverted airstream portion in varying degree to cool the oil flowing through those passageways upon any deployment of that core in the airstream, and not just the core part directly exposed to that airstream because of the deployment. As a result, there will need to be less of core  20  deployed into the engine fan airstream than there would be if only the directly exposed part thereof provided cooling of the oil flowing in that core. 
     The diverted airstream portion is further confined to pass through the entirety of passageway structures  21  in heat exchanger core  20  by, first, a baffle,  52 , seen  FIG. 1  that is attached to the bottom of heat exchanger core  20  and extends outward therefrom toward the upstream direction. Baffle  52  substantially closes off the portion of the interior volume of container  14  (across from air upstream passageway structures  21 ″, between those structures and the facing wall of that container) from the volume of container  14  below core  20  on the upstream side of that container at whatever degree of deployment of core  20  has occurred. In addition, a pair of sidewalls,  53  and  54 , mounted in container  14  on either side of heat exchanger core  20  substantially closes the sides of that same interior volume across from air upstream passageway structures  21 ″ so that the incoming diverted portion of the engine fan airstream is substantially directed toward air upstream passageway structures  21 ″. As a result, maximum cooling of the oil flowing in these structures is obtained from the diverted airstream portion substantially confined by baffle  52  and sidewalls  53  and  54  to pass by these structures. 
     Typically, heat exchanger  10  will be provided in fluid operated equipment system, such as the lubrication system for a turbofan engine, that is supplemented by an electrical control system directing operations of that equipment system and its components. Often, this will involve a feedback control loop using a temperature sensor to measure the temperature of the working fluid, such as oil in a lubrication system, and the sensor signal will be used by the controller in the control loop to control the cooling of that working fluid. Thus, such a control loop can be used to selectively direct electrical power to electrical connector  47  of heat exchanger  10 , and so to motor  40  therein, to control the extent of deployment of heat exchanger core  20  into the engine fan airstream to control the rate of cooling of the oil flowing through passageway structures  21  in that core. Because of thermal change delays in achieving fluid temperature changes, rather than a simple feedback control loop being used for controlling heat exchanger  10 , there may further aspects to the operation of the controller in such a loop, such as the controller relying also on lookup tables obtained from past experience, as to what degree of deployment of core  20  should be selected in any rising fluid temperature situation. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.