Abstract:
A synchronization cross-feed system for a thrust reverser having at least first and second sides. Each side of the thrust reverser has a thrust reverser actuation system having a plurality of actuators. The actuators in each thrust reverser actuation system are synchronized by a synchronization system. A synchronization cross-feed system couples the synchronization systems of the thrust reverser actuation system of the first and second sides of the thrust reverser allowing an anti-deployment mechanisms of each thrust reverser actuation system to serve as one or more of the redundant anti-deployment mechanism for other the thrust reverser actuation system.

Description:
FIELD OF THE INVENTION 
     The present invention relates to thrust reversers for jet engines, and more particularly, to anti-deployment mechanisms for thrust reversers. 
     BACKGROUND OF THE INVENTION 
     Jet aircraft, such as commercial passenger and military aircraft, utilize thrust reversers on the aircraft&#39;s jet engines to reduce the aircraft&#39;s speed after landing. One type of thrust reverser used in modem jet aircraft is the cascade type, described in more detail in U.S. Pat. No. 5,448,884. For ease of reference, the description of the cascade type of thrust reverser is substantially reproduced herein. 
     Referring first to FIG. 1, there is shown a conventional aircraft nacelle indicated at  18  which includes a jet engine, such as a Pratt &amp; Whitney PW4000, indicated at  20  (shown in hidden lines) supported by a strut  22  on a wing  24  (only a portion of which is shown). The nacelle  18  includes a nose cowl  26 , a fan cowl  27 , a thrust reverser sleeve  28 , a core cowl  30  and nozzle exhaust  32 . Although some of these components are made up of two mirror image parts split vertically in a clamshell arrangement, each component will be referred to herein as being one piece. 
     As shown in more detail in FIGS. 2 and 3, the thrust reverser system includes an inner duct (fan duct cowl)  36  and outer sleeve  28 . The sleeve  28  translates in an aft direction indicated by an arrow identified by a number  42  in FIG. 2, and a forward direction indicated by an arrow identified by a number  44 . When the thrust reverser is deployed, the translating sleeve  28  moves aft from a “stowed” position shown in FIG. 1 to a “deployed” position shown in FIG.  2 . In this process, cascade vanes  46  (FIG. 2) mounted to a thrust reverser support structure are uncovered. Vanes  46  are slanted in a forward direction so that during thrust reverser operation, fan air from the engine is redirected forward through the vanes (indicated by arrows  47 ) to aid in decelerating the airplane. 
     Air driven aft by the engine fan flows along an annular duct  48  (FIGS. 2 &amp; 3) formed by the fan duct cowl  36  and core duct cowl  30 . Movement of the sleeve  28  in the aft direction, causes blocker doors  50  to pivot from their stowed positions (shown in FIG. 3) to their deployed positions (shown in FIG. 2) where the doors are positioned to block rearward movement of the air through duct  48 . In this manner all rearward movement of the engine fan air is redirected forward through the cascade vanes  46 . 
     Movement of the sleeve  28  is guided along a pair of parallel tracks mounted to the top and bottom of the fan duct cowl  36  in a fore and aft direction. The sleeve  28  is moved between the stowed and deployed positions by means of a number of hydraulic actuators indicated at  54  (FIG.  3 ), each having an actuator rod  56  which is connected to the sleeve  28 . More specifically, as shown in FIGS. 5 and 6, each actuator  54  is connected to a structural torque box  57  via a gimbal mount  61  thereby allowing the actuator to accommodate lateral variances in sleeve motion. As shown in FIG. 4, the actuator rod  56  is located inside the aerodynamic surface of sleeve  28  and is connected to the sleeve  28  by a ball joint  68 . The ball joint  68  is accessible by removing a panel  70  which is bolted to the exterior surface of the sleeve  28 . 
     In operation, when the thrust reverser is commanded by the pilot to the deployed position, each actuator rod  56  (FIG. 5) extends in the aft direction. Conversely, when the thrust reverser is commanded by the pilot to move to the stowed position, each actuator rod  56  retracts in the forward direction. In an exemplary embodiment, the actuator  54  is a thrust reverser actuator currently installed on Boeing  767  airplanes. 
     As shown in FIG. 7, each actuator  54  includes a double acting piston  72  which is extended in the rightward direction (with reference to FIG. 7) by hydraulic pressure acting against a face  74  of the piston  72 . Retraction of the piston  72  and the thrust reverser sleeve therewith is accomplished by relieving hydraulic pressure from the piston face  74 , so that hydraulic pressure acting against an opposing face  76  of the piston causes it to move in the leftward direction. The piston  72  is connected to the actuator rod  56  which in turn is connected to the thrust reverser sleeve  28  in the manner described previously. 
     In the exemplary embodiment, each thrust reverser sleeve is driven by three of the actuators  54  (FIG.  3 ). It is important that each actuator  54  extend and retract the sleeve at the same rate to avoid causing the sleeve to bind along the tracks  51 . To accomplish this, operation of each of the three actuators  54  is synchronized by means of an interconnecting synchronizing shaft  80 . The sync shaft  80  (FIGS. 5 and 6) is a tube having a stationary outer sleeve and an internal rotating flexible shaft  81  which synchronizes motion of the three actuators. The outer sleeve of the sync shaft  80  is connected to the actuator  54  by a swivel coupling  82 . 
     In order to explain this synchronizing operation in greater detail, reference is made to the section view of the actuator  54  in FIG.  7 . As shown, the piston  72  is connected via a non-rotating threaded drive nut  84  to a rotating Acme screw  86 . As piston  72  translates the drive nut  84  moves with it. Translating movement of the drive nut  84  along the Acme screw  86  causes the Acme screw to rotate thereby converting translational movement into rotational movement. Synchronizing operation is further accomplished by a worm gear  90  (FIG. 6) located inside the actuator housing which engages a spur gear  94  which in turn is mounted to the end of the Acme screw  86 . Furthermore, the internal sync shaft  81  has a splined end tip which is positioned inside a slot (not shown) in the right end of the worm gear  90 . 
     Referring again to FIG. 7, extension and retraction of the thrust reverser sleeve results in rotation of the Acme screw  86  and rotary gear  94  therewith. This causes rotation of the worm gear  90  in a manner that a high torque and low rotational speed input from the Acme screw  86  is converted by the worm gear  90  to a low torque and high rotational speed output to the sync shaft. In the event one of the actuators  54  attempts to move the thrust reverser sleeve at a different rate than the other actuators, their rates are equalized via the common sync shaft and through the respective worm gears, spur gears and Acme screws of the actuators. This results in uniform translation of the thrust reverser sleeve. 
     In order to allow the thrust reverser sleeve  28  to be moved between the stowed and deployed positions for maintenance purposes while the airplane is on the ground, a manual drive clutch mechanism  96  shown in FIG. 6 is attached to the left end of the actuator. The manual drive clutch  96  includes a socket (not shown) for receiving a square drive tool (also not shown) in its left end  95 . The manual drive clutch  96  is connected by a female coupling  97  to a threaded male connector  98  at the left end of the actuator. The drive clutch  96  includes a drive shaft  99  (FIG. 10) having a square-ended tip which extends in a rightward direction from the clutch and which fits inside an end slot  100  (FIG. 5) of the actuator worm gear  90 . 
     In operation, when the square drive tool is inserted into the manual drive clutch in a rightward direction, the clutch is engaged thereby allowing the square drive tool to drive the worm gear  90  (FIG.  6 ), which in turn drives the spur gear  94 , Acme screw  86  to translate the thrust reverser sleeve. 
     With reference to FIGS. 8-11, mechanical lock  104  is connected to the actuator  54  in place of the drive clutch  96 . In turn, the drive clutch  96  is connected to the left end of the mechanical lock  104 . Like elements described previously will be identified in FIGS. 8 through 11 by like numerals. 
     The purpose of the mechanical lock  104  is to prevent uncommanded translation of the thrust reverser sleeve. The mechanical lock  104  includes a cylindrical housing  106  (FIG. 10) having an internal cylindrical passageway  108 . Axially aligned with the centerline of the passageway  108  is a cylindrical shaft  110  having an eight-pointed splined slot  112  at its left end for receiving therein the splined end tip  99  of the clutch mechanism  96  described previously. At the right end of the shaft  110  is a splined tip  113  which is inserted in the socket  100  (FIG. 5) of the actuator worm gear  90 . Mounted centrally on the center shaft  110  (FIGS. 9 and 10) is a lock wheel  114  having a cylindrical outer surface  116 . 
     Extending from the locking wheel surface  116  at equally spaced intervals are four square teeth  118  (FIG. 11) whose rotational path is blocked by a locking pin  120  when the device is de-energized and the locking pin is in a down/locking position shown in FIGS. 10 and 11. More particularly, the locking pin  120  extends through an opening  122  in the upper wall of the housing  106 . It should be appreciated that the direction of the shear force created by the rotation of the locking wheel  114  and shaft  110  therewith is orthogonal to the locking/unlocking movement of the locking pin thereby minimizing the forces required to extend and retract the locking pin  120 . 
     In operation, when the locking pin  120  is in the down/locking position it prevents rotational movement of the shaft  110  thereby preventing rotation of the worm  90  (FIG.  9 ), worm gear  94 , and the Acme screw  86 . This, in turn, prevents translational movement-of the drive nut  84  (FIG.  7 ), the piston  72  and the thrust reverser sleeve  28  therewith, thereby preventing thrust reverser sleeve motion. 
     Movement of the locking pin  120  (FIG. 10) between the locked position and an unlocked position (where the pin  120  is above and clear of the teeth  118 ) is controlled by an electrically operated solenoid  124  through which the upper end of the locking pin  120  extends. Electrical control is initiated at the cockpit (not shown) via conventional airplane thrust reverser control circuits and is transmitted by electrical wires  125  to the solenoid  124 . Control of the solenoid may be accomplished in a conventional manner. It should be appreciated that other means for controlling movement of the locking pin  120 , such as hydraulic or electrohydraulic means, may be utilized. 
     Thrust reversers include various anti-deployment mechanisms to prevent in-flight deployment, such as locking actuators, non-locking actuators, synchronization shaft locks (sync lock), and auto-restow systems. Thrust reversers presently used on Boeing aircraft have three levels of locking means. For example, thrust reversers used on wide body aircraft illustratively have two locking actuators per nacelle and one sync lock per nacelle. Thrust reversers used on narrow body aircraft illustratively have one locking actuator per nacelle, one sync lock per nacelle, and an auto-restow system per nacelle. 
     It is an object of this invention to link the synchronization systems of the thrust reverser actuation systems of the two sides of the thrust reverser so that anti-deployment mechanisms used for each of the thrust reverser actuation systems can provide one or more of the redundant anti-deployment mechanisms for the other thrust reverser actuation system. 
     SUMMARY OF THE INVENTION 
     A synchronization cross-feed system for a thrust reverser having at least first and second sides. Each side of the thrust reverser has a thrust reverser actuation system having a plurality of actuators. The actuators in each thrust reverser actuation system are synchronized by a synchronization system. A synchronization cross-feed system couples the synchronization systems of the thrust reverser actuation systems of the first and second sides of the thrust reverser allowing an anti-deployment mechanisms of each thrust reverser actuation system to serve as one or more of the redundant anti-deployment mechanisms for other the thrust reverser actuation system. 
     In an embodiment, the synchronization cross-feed systems has first and second coupling assemblies that are removably coupled to each other so that they decouple from each other when the thrust reverser sides are opened to allow the thrust reverser sides to be opened. 
     In an embodiment, the first and second coupling assemblies have engagement teeth that mate with each other when the thrust reverser sides are closed. 
     In an embodiment, the engagement teeth of the first coupling assembly is disposed on a telescopic coupling shaft that is spring loaded by a spring in the first coupling assembly that forces telescopic coupling shaft toward the second coupling assembly. 
     In an embodiment, the first and second coupling assemblies have shafts that are coupled to respective actuators of the thrust reverser actuation systems of the first and second thrust reverser sides. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG.1 is a side view of a conventional nacelle and strut; 
     FIG. 2 is a side view of a conventional thrust reverser system; 
     FIG. 3 is an isometric view of a conventional thrust reverser system; 
     FIG. 4 is a partial view of a conventional thrust reverser sleeve showing an access port located on the sleeve; 
     FIG. 5 is an isometric view of a conventional thrust reverser actuator; 
     FIG. 6 is a side view of the conventional thrust reverser actuator shown in FIG. 5; 
     FIG. 7 is side sectional view of the thrust reverser actuator shown in FIGS. 5 and 6; 
     FIG. 8 is an isometric view of a thrust reverser actuator employing a prior-art mechanical synchronization shaft lock; 
     FIG. 9 is a side view of the thrust reverser actuator and mechanical lock shown in FIG. 8; 
     FIG. 10 is a side sectional view of the mechanical lock of FIG. 8; 
     FIG. 11 is a partial end sectional view of the mechanical lock of FIG. 8; 
     FIG. 12 is a cross-section of a thrust reverser having the synchronization cross-feed system of the invention; 
     FIG. 13 is a side view of the synchronization cross-feed system of the invention in an open position; 
     FIG. 14 is a sectional view taken along the line  14 — 14  of FIG. 13; 
     FIG. 15 is a sectional view taken along the line  15 — 15  of FIG. 14; 
     FIG. 16 is a side view of the synchronization cross-feed system of the invention in a closed position; and 
     FIG. 17 is a side view of a ninety degree mechanical drive mechanism. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses; 
     Referring to FIGS. 12-16, a synchronization cross-feed system  200  in accordance with the invention is described. Elements common to FIGS. 1-11 will be identified with the same reference numerals. Specifically referring to FIG. 12, a cross-section of a thrust reverser  202 , looking aft, is shown with synchronization cross-feed system  200  spanning a lower bifurcation area  204  of thrust reverser  202  and linking thrust reverser actuation systems  206  of left and right sides  203 ,  205 , (as oriented in FIG. 12) of thrust reverser  202 . Each thrust reverser actuation system  206  can illustratively be the thrust reverser actuation system described with reference to FIGS. 1-11. 
     Specifically referring to FIGS. 13-16, synchronization cross-feed system  200  is shown in greater detail. Synchronization cross-feed system  200  has left and right coupling assemblies  212 ,  213  (as oriented in FIGS. 13-16) having housings  208 ,  209  supporting respective bearing assemblies  210 . Left coupling assembly  212  has a telescopic coupling shaft  214  slidably coupled to a synchronization shaft coupling  216  affixed to an end of a synchronization shaft  218 . Right coupling assembly  213  has a fixed coupling  220  coupled to an end of a synchronization shaft  224 . Synchronization shaft coupling  216  and fixed coupling  220  are generally cylindrical, having bores in distal ends  219 ,  221  which respective ends of synchronization shafts  218 ,  224  are received. Distal ends  219  and  221  are machined as double square ends and the ends of synchronization shafts  218 ,  224  that are received in the double square machined ends  219 ,  221  are illustratively swaged into squares. It should be understood that right coupling assembly  213  could have the telescopic coupling shaft  214  and the left coupling assembly  212  could have the fixed coupling  220 . 
     Synchronization shaft coupling  216  and fixed coupling  220  illustratively include a threaded portion  226 ,  228 , respectively, and shoulders  230 ,  232 , respectively. A threaded bearing retainer  234  is threaded onto threaded portion  226  of synchronization shaft coupling  216  to retain bearing  236  of the bearing assembly  210  on left coupling assembly  212  against shoulder  230  to retain bearing  236  in place. Similarly, a second bearing retainer  234  is threaded onto threaded portion  228  of fixed coupling  220  retain bearing  236  of bearing assembly  210  on right coupling assembly  213  in place. 
     Left coupling assembly  212  further includes a pin  238  radially extending through synchronization shaft coupling  216  that holds a bearing retainer  240  in place. Bearing retainer  240  holds bearing  242  of bearing assembly  210  in left coupling assembly  212  in place. 
     Telescopic coupling shaft  214  includes wheel  244  having engagement teeth  246  extending radially outwardly around a proximal facing side  245  and extending axially therefrom toward fixed coupling  220 . Wheel  244  also has tapered engagement nose  248  extending axially from the center of proximal facing side  245  toward fixed coupling  220 . Wheel  244  and engagement teeth  246  are shown in more detail in FIG.  14 . Wheel  244  further includes a cylindrical shaft  250  that extends from a distal facing side  247  of wheel  244  over synchronization shaft coupling  216  and is slidably secured thereon by a pin  252 . A proximal end  254  of synchronization shaft coupling  216  has a spring receiving bore  256  therein that receives a spring  258  that extends within cylindrical shaft  250  of telescopic coupling shaft  214  to a spring receiving recess  259  in distal facing side  247  of wheel  244 . Housing  208  of left coupling assembly  212  has a radially outwardly extending flange  262  at a proximal end  260 . Flange  262  is secured to a fixed element of the thrust reverser, such as a torque box  57  of the left side of thrust reverser  202 , to secure left coupling assembly  212  in place. 
     Fixed coupling  220  has a bore  266  therein that opens at a proximal end  264  of fixed coupling  220 . Proximal end  264  has engagement teeth  268  around the opening of bore  266 . Engagement teeth  268  extend axially toward telescopic coupling shaft  214 . Engagement teeth  268  preferably angle outwardly from bore  266  to facilitate reception of tapered nose  248  into bore  266  when synchronization cross-feed system  200  is in its engaged position where coupling assembly  212  mates with right coupling assembly  213 , as shown in FIG. 16. A bearing  270  of bearing assembly  210  of right coupling assembly  213  is disposed around fixed coupling  220  in a recess  272  therein and is received in a recess  274  in housing  209 . Housing  209  includes a flange  276  secured to fixed element of thrust reverser  202 , such as a torque box  57  of the right side of the thrust reverser  202 , to secure right coupling assembly  213  in place. 
     In operation, left coupling assembly  212  mates with right coupling assembly  213  when thrust reverser sleeves  28  are in their operational positions (stowed or deployed). In this regard, the right and left sides of thrust reverser  202  are in proximity to each other such that telescopic coupling shaft  214  has been urged into fixed coupling  220  such that engagement teeth  246  of left coupling assembly  212  engage engagement teeth  268  of right coupling assembly  213 . Cylindrical shaft  250  of telescopic coupling shaft  214  is urged into synchronization shaft coupling  216 , compressing spring  262 , which urges telescopic coupling shaft  214  into fixed coupling  220 . Telescopic coupling shaft  214  in cooperation with spring  262  allows for some movement between the halves of thrust reverser  202  without damaging synchronization cross-feed system  200  yet maintains the engagement of coupling assemblies  212  and  213 . Further, since coupling assemblies  212  and  213  are held together only by the force of spring  262 , they decouple from each other when the left and right sides  203 , 205  of thrust reverser  202  are opened for maintenance, thus allowing the left and right sides  203 ,  205  of thrust reverser  202  to be opened for maintenance. 
     Synchronization shafts  218 ,  224  are coupled to translation actuators  54  of left and right sides of thrust reverser  202  in the same fashion as described above with reference to synchronization shaft  80  and translation actuators  54  and illustratively couples to a translation actuator  54  in lieu of manual drive clutch mechanism  96 , thus coupling to the synchronization system (synchronization shaft  80  and associated components) of the thrust reverser actuation system. In this regard, a manual drive mechanism, such as manual drive mechanism  300  (FIG.  17 ), would be added to thrust reverser  202  in place of manual drive clutch mechanism  96 . Alternatively, manual drive clutch mechanism  96  would be appropriately modified to permit the respective synchronization shaft  218 ,  224  to couple to the translation actuator  54 . In another embodiment, mechanical lock  104  would be appropriately modified to permit the respective synchronization shafts  218 ,  224  to mate to mechanical lock  104  and thus to the synchronization system of the thrust reverser actuation system. 
     With reference to FIG. 17, mechanical drive mechanism  300  has a housing  301  in which a spring loaded drive pin  302  is mounted. Drive pin  302  has a square hole  304  in its top to receive a square driver. Drive pin  302  has a bevel gear  306  at a lower end  308  (as oriented in FIG.  17 ). A shaft  310  extends transversely through housing  301  at a lower end  312  thereof. Shaft  310  has a bevel gear  314  mounted thereon that mates with bevel gear  306  on drive pin  302  when drive pin  302  is depressed. A left end  316  (as oriented in FIG. 17) of shaft  310  is squared to mate with the double squared hole in a translation actuator, such as actuator  54 . Left end  316  of shaft  310  could also be formed to have a double squared hole to mate with a shaft, such as synchronization shaft  218  or  224 , for “in-line” installation. A right end  318  of shaft  310  has a double squared hole to receive a squared end of a shaft, such as synchronization shaft  218  or synchronization shaft  224 . Right end  318  of shaft  310  is affixed to cylindrical shaft  321  which is supported within housing  301  by a pair of bearings  322 . Housing  301  further has attachment fittings  320 , such as B-nut fittings, surrounding left end  316  and right end  318  of shaft  310 . 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.