Thrust reverser torque box with discrete major fittings

A thrust reverser torque box assembly for an aircraft engine is constructed with a torque tube having a cross section configuration tailored and conducive to carrying torsion and discrete major fittings at opposite ends of the torque tube that connect the torque tube and thrust reverser actuation and reacts loading due to reverse thrust operation to the aircraft engine fan case.

FIELD

This disclosure pertains to a thrust reverser torque box in an aircraft engine assembly where the torque box is constructed of metallic and/or composite material component parts.

BACKGROUND

Typical commercial aircraft engines are surrounded and encapsulated in aerodynamic structures which form a nacelle2represented inFIGS. 1 and 2. The typical nacelle2is comprised of an inlet3, fan cowl4, and thrust reverser5. The thrust reverser5is an assembly that is made up of a fixed inner structure assembly6and a translating structure assembly7represented inFIG. 2. The translating structure assembly7contains moving blocker doors and a sliding sleeve which when deployed block the fan flow and redirect the fan flow to provide reverse thrust. The fixed structure assembly6is made up of two halves that surround the engine core. Each half is hinged off of an engine strut and engages the engine through an inner and outer v-groove interface. The thrust reverser has v-blades that engage the engine v-groove to transmit forward and reverse thrust loads into the engine structure. The main part of the thrust reverser fixed structure assembly that transmits the reverse thrust air loads from the blocker doors and cascades to the engine v-groove is called the Torque Box Assembly8. The torque box8structurally connects the thrust reverser actuation systems9to the engine. Because the torque box8must react the loads created by the operation of the thrust reverser actuation systems, the construction of the torque box8is substantial.

Typically, a torque box8is comprised of two generally semi-circular sections that extend around opposite sides of the engine circumference. Each section is typically a closed box, metallic built up structure comprised of multiple sheet metal parts, forgings, and extrusions fastened together by thousands of fasteners per aircraft engine. The construction of the torque box8involves multiple processes and a significant amount of assembly time. Each torque box section typically has a constant cross section along its entire length, and the constructions of the sections are not specifically tailored to load at certain points of application and reaction. There are also typically radial stiffening ribs inside the torque box sections that are spatially arranged along the lengths of the sections to stabilize the sections for fatigue and shear buckling between load application areas.

SUMMARY

The thrust reverser torque box assembly of this disclosure is a replacement to the torque box assembly commonly utilized in thrust reversers. The thrust reverser torque box assembly serves as an enabler to reduce weight, assembly time, fabrication time, fastener counts, and part counts.

The torque box assembly provides discrete major fittings at load reaction areas where load is predominantly axial, and it utilizes a torque tube having a cross section tailored for appropriate loading in areas that traditionally carry torsion.

The construction of the thrust reverser torque box assembly of this disclosure reduces the number of parts associated with the assembly. It drastically reduces the number of fasteners because the construction of the torque box does not require radial stiffening ribs for fatigue and shear buckling resistance as in the prior art thrust reverser torque box construction. It also enables a more monolithic overall structure.

The thrust reverser torque box assembly of this disclosure is structurally tailored to accept loads resulting from reverse thrust operation via the thrust reverser actuation system and the cascades of an aircraft engine, react the loads to the engine fan case, and stabilize the induced torsion via a torque tube having a cross section appropriately tailored for loading.

The thrust reverser actuation system reacts through discrete stiffened major fittings of the torque box. Radial and axial loading of the torque box are reactive at the major fittings that are positioned on the torque box at the primary reaction locations for axial and radial loading.

The torque tube extends between and connects together adjacent major fittings. The cross section of the torque tubes is capable of carrying the required tangential and torsional loading of the thrust reverser torque box.

As in a conventional thrust reverser torque box, the thrust reverser torque box assembly of this disclosure is comprised of two predominantly semi-circular sections that are essentially mirror images of each other. Thus, the construction of each semi-circular section is substantially the same. Therefore, only one of the torque box assembly sections is described herein.

The thrust reverser torque box assembly comprises at least first and second major fittings. The fittings are each configured to be connected to a conventional thrust reverser actuation system of an aircraft engine in a conventional manner. The major fittings have cross section configurations that are substantially similar to those of conventional thrust reverser torque boxes. These cross section configurations are typically not circular.

The thrust reverser torque box assembly also includes a tube at least spanning the major fittings. The tube has a length with opposite first and second ends and a cross section configuration that is tailored to predominantly torsional loading. If there are two discrete fittings there is a minimum of one torque tube. If there are three discrete fittings there is a minimum of two torque tubes spanning between adjacent major fittings.

The tube first end is connected to the first major fitting by a first transition section at the tube first end. The first transition section has a cross section configuration that transitions from the cross section configuration of the tube to the cross section configuration of the first major fitting.

The tube second end is connected to the second major fitting by a second transition section at the tube second end. The second transition section has a cross section configuration that transitions from the cross section configuration of the tube to the cross section configuration of the second major fitting.

In one embodiment of the thrust reverser torque box assembly the first transition section is a single piece of continuous material with the tube and the second transition section is a single piece of continuous material with the tube.

In a further embodiment of the thrust reverser torque box assembly the first transition section is a separate piece of material from the tube and the second transition section is a separate piece of material from the tube.

The thrust reverser torque box assembled from the first and second major fittings and the tube enables the reduction of weight, fabrication time, assembly time, fastener count, and part count of the torque box assembly.

DETAILED DESCRIPTION

FIG. 3is a representation of a perspective view of one section of the thrust reverser torque box assembly10of this disclosure. As in a conventional thrust reverser torque box assembly, the thrust reverser torque box assembly10of this disclosure is comprised of two semi-circular sections that are substantially mirror images of each other. Thus, the construction of each semi-circular section is substantially the same. Therefore, only one section of the torque box assembly10is shown in the drawing figure and is described herein.

The thrust reverser torque box assembly10is a replacement to the conventional torque box assembly commonly utilized in thrust reversers. The torque box assembly10is structurally tailored to accept loads resulting from reverse thrust operation produced by the thrust reverser actuation system and the cascades of an aircraft engine. The loads accepted by the torque box assembly10are reacted to the engine fan case in a substantially conventional manner; however, instead of reacting axial loading around the circumference of the engine fan case, loads are reacted only at discrete major fittings located at the approximate location of the thrust reverser actuation system actuators. The construction of the thrust reverser torque box assembly10enables a reduced weight, assembly time, fabrication time, fastener counts and part counts from those of the conventional torque box assembly.

Each section of the thrust reverser torque box assembly10is comprised of at least first12and second14discrete major fittings. In the example of the torque box assembly10represented inFIG. 3, the assembly section also includes a third discrete major fitting16. The fittings12,14,16are each configured to be connected to a conventional thrust reverser actuation system of an aircraft engine in a conventional manner. Because the fittings12,14,16have substantially the same construction, the details of the construction of the first fitting12will be described herein. It should be understood that the construction of the other two fittings14,16are comparable to that of the first fitting12. The embodiment presented shows very similar construction through fittings12,14and16; however, it is not required that the fittings be the same. Fittings can be tailored to the load levels to which they are exposed and the components with which they may or may not interface (i.e. hinge/latch beams).

Referring toFIGS. 4 and 5, the first fitting12is a stiffened, discreet major fitting similar to current construction. InFIG. 4the fitting12is represented as having a general polygonal cross section configuration such as a triangular cross section configuration. However, this is only one example of a cross section configuration that the first fitting12could have. Because the torque box assembly10will be secured to other component parts of the aircraft engine, it is only necessary that the fitting12have a cross section configuration that is suitable for this purpose. Therefore, the first fitting12could have substantially any cross section configuration. The embodiment of the first fitting12is metallic and is comprised of a bottom panel18, a front panel20and a rear panel22. However, it is not required that the fitting12be metallic. The panels are connected together in any conventional manner, for example by welding, by fasteners, etc. The panels18,20,22give the fitting12its general triangular configuration with a triangular hollow interior24. A v-blade26is provided at the forward edge of the fitting bottom panel18. The v-blade26interfaces with a corresponding v-groove on the engine fan case and is responsible for reacting axial and radial loading resulting from reverse thrust operation into the engine fan case. Openings28,30are also provided through the respective front20and rear22panels. The openings28,30are dimensioned to allow a portion of a thrust reverse actuation system to pass through the openings. A pair of flanges32,34are provided on the fitting front panel20on opposite sides of the front panel opening28. The flanges32,34are provided to connect the fitting12to a thrust reverser actuation system in any conventional manner. The fitting12is secured at high load locations around the aircraft engine. These high load locations tend to be concentrated at the thrust reverser actuation system actuator locations. Axial loading at the v-blade26and the outer v-groove on the engine fan case tends to spike at the thrust reverser actuation system locations and connections to the engine. This is why stiffened discreet major fitting12is located at these areas.

The section of the thrust reverser torque box assembly10also includes at least one torque tube36for connecting fittings12,14and16. In the representation of the section of the torque box assembly10shown inFIG. 3, the assembly section includes a pair of circular torque tubes36,38. However, in other constructions of the torque box assembly that include only a first fitting12and a second fitting14, the assembly section includes only one torque tube36. Because the constructions of the torque tubes36,38are substantially the same, only the construction of the first torque tube36is described herein.

The torque tube36has a length with opposite first42and second44ends, and a cross section configuration that is circular in an embodiment shown inFIG. 6. The torque tube36extends between and connects together the adjacent first12and second14discrete major fittings. The cross section of the torque tube36shown inFIG. 6is capable of carrying the required tangential and torsional loading of the thrust reverser torque box assembly10. The cross section and construction of the torque tube36is to best tailor the tube for efficiently carrying the tangential and torsional loading, versus maintaining the cross sections of the discrete major fittings. The torque tube36takes the induced torsion resulting from the operation of the thrust reverser actuation system actuators. The cross section of the torque tube36is configured such that secondary requirements can be satisfied, for example connections to the discrete fittings, and the configuration can be optimized to carry torsion. For example, with there being no additional requirements on the torque tube36, the configuration of the torque tube36could be circular. The cross section of the torque tube36could also be that of a discrete major fitting it connects to and transition from the configuration at the fitting to a circular configuration of the torque tube36and then to another alternative configuration at another discrete major fitting. If the length of the torque tube36is required to seal against and provide support to an external nacelle fairing, the torque tube36could have a more half circle D-shaped or triangular cross section configuration. The torque tube36itself is configured for no connections to the aircraft engine on the tube. The torque tube36can be constructed in any conventional manner, and could have other cross sections than the hollow circular cross section of the tube shown inFIG. 6.

The torque tube first end42is connected to the first fitting12and the torque tube second end44is connected to the second fitting14. There are two methods of connecting the torque tube36to the fittings12,14, expressed in the embodiments presented, defining two embodiments of the thrust reverser torque box assembly10.

The torque tube first end42is connected to the first discrete major fitting12by a first transition section46at the tube first end. The first transition section46has a cross section configuration that transitions from the cross section configuration of the torque tube36to the cross section configuration of the first discrete major fitting12. Referring toFIG. 7, the first transition section46is a single piece of continuous material with the torque tube36and the second transition section47is a single piece of continuous material with the torque tube36. Thus, the torque tube36, the first transition section46and the second transition section47are monolithic. The cross section configuration of the two major fittings12,14are substantially the same and the cross section configurations of the two transition sections46,47are substantially the same. However, the major fittings could have different cross section configurations. In this situation the two transition sections would also have different cross section configurations. Because constructions of the first46and second47transition sections are the same, only the construction of the first transition section46is described herein. Referring toFIGS. 3 and 7, the first transition section46extends from the torque tube first end42into the interior24of the first fitting12, the external configuration of the first transition section46transitions from the cross section of the torque tube36to the cross section configuration of the interior24of the first fitting12. In the embodiment of the thrust reverser torque box assembly10shown in the drawing figures, the first transition section46transitions to a portion48having the general triangular configuration of the first fitting interior24. This enables the portion48of the first transition section46to be securely connected in the first fitting interior24and to the first fitting12by fasteners or other equivalent methods.

The second transition section47at the torque tube second end44is constructed in the same manner as the first transition section46and connects the torque tube second end44to the second discrete major fitting14in the same manner as the first transition section46.

In a further embodiment of the thrust reverser torque box assembly10the first transition section52is a separate piece of material or a separate part from the torque tube36and the second transition section (not shown) is a separate piece of material or a separate part from the torque tube36. The first transition section52in this embodiment is represented inFIGS. 10-12. The second transition section (not shown) has substantially the same construction as the first transition section52and therefore is not disclosed in the drawing figures or described herein. The second embodiment of the first transition section52has basically the same configuration as that of the first embodiment of the first transition section46, except for the second embodiment being separate from the torque tube36. As shown inFIGS. 10-12, the first transition section52has a first portion54having a cross section configuration that is shaped to fit tightly into the interior volume24of the first fitting12. A post56projects outwardly from a side of the first transition section first portion54. The post56has a cross section comparable to the torque tube36and is dimensioned to fit in a tight engagement with the interior of the torque tube36. The first transition section first portion54is secured to the interior of the first fitting12by fasteners or other equivalent methods. The first transition section post56is secured to the interior of the torque tube36by fasteners or other equivalent methods. In this way the first transition section52connects the torque tube first end42to the first fitting12. A second transition section (not shown) substantially the same as the first transition section52is used to connect the torque tube second end44to the second fitting14. The first transition section52could be constructed of the same composite material as the torque tube36, or a different material.

In both the described embodiments, the thrust reverser torque box10assembled from the first12and second14discrete major fittings and the torque tube36enables a reduction in the weight, fabrication time, assembly time, fastener count, and part count of the torque box assembly10. To better illustrate this benefit of the torque box assembly10of this disclosure,FIG. 13is a side-by-side comparison of the first described embodiment of the torque box assembly10and a conventional torque box62. The conventional torque box62also includes reaction fittings64,66that are each configured to be connected to a conventional thrust reverser actuation system of an aircraft engine. The portion of the torque box62that extends between the two fittings64,66basically maintains the same cross section configuration of the fittings. This is in contrast to the torque tube36which has a cross section that is specifically tailored or conducive to carrying predominantly torsional loading, versus maintaining the cross section configuration of the fittings. The torque tube36itself is not configured for connection to the aircraft engine. This enables removing radial stiffening ribs68and removing the fasteners associated with attaching webs and the radial stiffening ribs68in between the fittings64,66. This reduction in the material volume in between the fittings64,66results in a reduction of weight of the torque box assembly10of this disclosure.

As various modifications could be made in the construction of the apparatus and its method of operation herein described and illustrated without departing from the scope of the disclosure, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present disclosure should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.