Low-resistance easy-to-maintain tilting rotorcraft nacelle structure

Abstract

The invention provides a low-resistance easy-maintenance tilting rotorcraft nacelle structure and a tilting rotorcraft. The low-resistance easy-maintenance tilting rotorcraft nacelle structure comprises a nacelle supporting frame (1), a nacelle movable fairing (2), a nacelle fixed fairing (3), an equipment compartment fairing (4), a nacelle firewall (5) and an equipment compartment supporting frame (7). The nacelle supporting frame (1), the nacelle movable fairing (2), the nacelle fixed fairing (3), the nacelle firewall (5) and the rear firewall (5c) (6) jointly form a fireproof design area surrounding an engine, and the wind resistance and the weight of the nacelle are reduced through small-section layout. In addition to providing reliable support for the nacelle movable fairing (2), the nacelle fixed fairing (3) and the equipment compartment fairing (4) in flight, the nacelle supporting frame can be conveniently disassembled during ground maintenance, after the nacelle supporting frame (1) is disassembled, the maintenance space is greatly expanded, and an engine is conveniently hoisted.

Description

Technical Field

[0001] This invention belongs to the field of tiltrotor aircraft structural design, specifically relating to a low-drag and easy-to-maintain tiltrotor aircraft nacelle structure. Background Technology

[0002] Tiltrotor aircraft possess the vertical takeoff and landing (VTOL) capabilities of helicopters while also exhibiting the long-range, high-speed performance of fixed-wing aircraft, making them a crucial development direction for future VTOL aircraft. Currently, there are relatively few tiltrotor aircraft models in China, primarily concentrated in the fields of unmanned aerial vehicles (UAVs) and EVTOLs (Electronic Vehicle Transmission Systems). Detailed information about their nacelle structures is lacking from publicly available sources. Foreign tiltrotor aircraft, such as the V-280, appear to have a bolted, detachable, and enclosed nacelle structure from the outside. When engine maintenance is required, numerous bolts need to be removed for routine maintenance of the internal equipment.

[0003] During flight, the nacelle primarily maintains its aerodynamic shape to reduce drag and maintain cabin temperature. The nacelle fairing also protects the engines, accessories, and other equipment inside. When the aircraft is parked on the ground, the nacelle serves as a maintenance access point, requiring maintenance personnel to frequently open the hatch for routine maintenance and inspection of the engines, accessories, and other equipment. Furthermore, the high temperatures generated during operation necessitate timely ventilation and heat dissipation after ground shutdown; failure to do so could result in lingering heat damaging equipment. If a closed nacelle structure with numerous bolts, similar to that of the V-280, were adopted, the workload for ground maintenance personnel would increase significantly. Moreover, with current domestic technology, bolts lose their self-locking function after repeated disassembly, potentially leading to connection failure due to flight vibrations. Summary of the Invention

[0004] This invention provides a low-drag and easy-to-maintain tiltrotor nacelle structure, which reduces the nacelle's wind resistance and weight through a small cross-section layout.

[0005] This invention provides a low-drag and easy-to-maintain tiltrotor nacelle structure, including: a nacelle support frame 1, a movable nacelle fairing 2, a fixed nacelle fairing 3, an equipment compartment fairing 4, a nacelle firewall 5, and an equipment compartment support frame 7. The nacelle support frame 1 includes: a circumferential support 1a, a lower support 1a2, a first longitudinal support 1b, and a second longitudinal support 1c; the nacelle firewall 5 includes: a forward firewall 5a, a longitudinal firewall 5b, and a rear firewall 5c. The longitudinal firewall 5b is installed on the wing platform along the flight direction, the forward firewall 5a and the aft firewall 5c are installed on one side of the longitudinal firewall 5b, and the equipment compartment support frame 7 is installed on the other side of the longitudinal firewall 5b, forming the engine compartment and equipment compartment. The circumferential support 1a is disposed between the front firewall 5a and the rear firewall 5c; the circumferential support 1a includes an upper support 1a1 and a lower support 1a2 that are connected to each other; the other end of the upper support 1a1 is connected to the longitudinal firewall 5b, and the other end of the lower support 1a2 is connected to the wing platform; the two ends of the first longitudinal support 1b are respectively connected to the upper support 1a1 and the rear firewall 5c, and the two ends of the second longitudinal support 1c are respectively connected to the lower support 1a2 and the rear firewall 5c. The fixed fairing 3 of the nacelle is fixed to the front firewall 5a, the longitudinal firewall 5b, the first longitudinal support 1b and the rear firewall 5c; the upper edge of the movable fairing 2 of the nacelle is connected to the fixed fairing 3 of the nacelle by two hook locks 2e; the lower edge of the movable fairing 2 of the nacelle is rotatably connected to the wing platform and the second longitudinal support 1c by a gooseneck hinge. The equipment compartment fairing 4 is mounted on the equipment compartment support frame 7 and the longitudinal firewall 5b.

[0006] Optionally, the main body of the nacelle support frame 1 is a machined frame with an I-shaped cross-section and fireproof function. The whole is fixed to the longitudinal firewall 5b side and wing plane by bolts; its upper flange serves as the overlapping area of ​​the nacelle movable fairing 2 and the bolt installation position of the nacelle fixed fairing 3. The upper support 1a1 and the lower support 1a2 are joined together by four bolts and tightened into one piece. The first longitudinal support 1b is a machined frame with an I-shaped cross-section. Before flight, it is bolted to the support 1a1 by two plates, and the rear is connected to the rear firewall 5c by bolts 1d. After the four bolts connecting the upper support 1a1 and the lower support 1a2, the bolts connecting the longitudinal firewall 5b, and the bolts connecting the first longitudinal support 1b and the second longitudinal support 1c to the rear firewall 5c are removed, the upper support 1a1 and the first longitudinal support 1b can be removed as a whole from the top. At this time, the space above the engine compartment is completely unobstructed, which makes it convenient to hoist and maintain the engine. The second longitudinal support member 1c is a U-shaped machined frame, which, along with the first longitudinal support member 1b, provides longitudinal support for the nacelle support frame 1 and the rear firewall 5c.

[0007] Optionally, an ejector port 5d is provided on the rear firewall 5c, and the engine exhaust port is located inside the ejector port 5d. The ejector port 5d uses the pressure difference caused by the engine exhaust speed to extract hot air from the engine compartment.

[0008] Optionally, the nacelle movable fairing 2 adopts a fire-resistant composite material honeycomb sandwich structure, including: a front movable fairing 2a and a rear movable fairing 2b. The side edges of the forward movable fairing 2a and the aft movable fairing 2b of the nacelle are connected to the lock seats installed on the forward firewall 5a, the circumferential support 1a and the aft firewall 5c by two front and rear bolt locks 2d. The front fairing 3a of the nacelle and the rear fixed fairing 3b of the nacelle are provided with recessed areas 2i, and rubber pads 2j are provided in the recessed areas 2i. The upper edge of the movable fairing 2 of the nacelle is provided with an overlapping area that matches the recessed areas 2i. The nacelle movable fairing 2 is equipped with a pin lock 2d on the front and rear sides. After locking, the nacelle movable fairing 2 is fixed to the nacelle support frame 1 and the nacelle firewall 5. The positioning pin 2f is a single-sided limiting design. Limiting devices 2g are provided between the front movable fairing 2a and the front firewall 5a of the nacelle, and between the rear movable fairing 2b and the rear firewall 5c of the nacelle. When the movable fairing 2 is closed, the positioning pin 2f and the limiting device 2g form a double-sided limiting of the front movable fairing 2a and the rear movable fairing 2b of the nacelle. When maintenance of the engine and its accessories is required, open the latch lock 2d and hook lock 2e. The front movable fairing 2a and the rear movable fairing 2b of the nacelle will open along their respective positioning pins 2f. After opening to a certain angle, the limiting device 2g will release the limiting device on the movable fairing 2. The front movable fairing 2a and the rear movable fairing 2b of the nacelle can then be removed by moving them out along their respective positioning pins 2f in the axial direction.

[0009] Optionally, the 2d latch lock seat has an eccentric adjustable mechanism 2k, allowing the center hole of the lock seat to be adjustable within a 3mm circumference.

[0010] Optionally, an overhead heat insulation device 3e is provided in the overheated zone inside the rear movable fairing 2b of the nacelle. The overhead heat insulation device 3e includes an overhead structure and a heat shield 3f.

[0011] Optionally, the nacelle fixed fairing 3 includes: a front fixed fairing 3a of the nacelle, a rear fixed fairing 3b of the nacelle, and a lower fixed fairing 3d of the nacelle connected between the wing platform below the rear of the engine and the rear firewall 5c. The main body of the nacelle front fixed cover 3a and the nacelle lower fixed cover 3d is a fireproof composite honeycomb sandwich structure; the top of the nacelle front fixed cover 3a is provided with an engine accessory hot air outlet. The main body of the nacelle rear fixed cover 3b is an aluminum alloy frame with fireproof skin riveted assembly structure; the aluminum alloy frame has a T-shaped stiffened structure in cross section, and the nacelle rear fixed cover 3b is equipped with a four-level grid-type ejector system air intake. The lower fixed cover 3d of the nacelle is equipped with a heat insulation device 3e in the overheated zone.

[0012] Optionally, the lower edge of the nacelle movable fairing 2a is rotatably connected to the wing platform via a gooseneck hinge 2h and a positioning pin 2f fixed on the wing platform; the lower edge of the nacelle movable fairing 2b is rotatably connected to the second longitudinal support 1c via a gooseneck hinge 2h and a positioning pin 2f fixed on the second longitudinal support 1c.

[0013] Optionally, it also includes: exhaust compartment fairing 6; exhaust compartment fairing 6 includes: tail nozzle fairing 6a, longitudinal aluminum alloy frame 6b, transverse aluminum alloy frame 6c, longitudinal support 6d and end connection flange 6e. The longitudinal aluminum alloy frame 6b, the transverse aluminum alloy frame 6c, and the longitudinal support 6d are riveted together to form the internal support of the exhaust compartment fairing 6; the exhaust compartment fairing 6 is bolted to the rear firewall 5c.

[0014] Optionally, the upper flange of the middle frame of the equipment compartment support frame 7 has a notch, and a longitudinally arranged slide rail bracket 4d with reinforcing ribs is provided at the notch. A slide rail 4c is fixedly installed inside the slide rail bracket 4d with reinforcing ribs. The equipment compartment fairing 4 has a cut that exposes the slide rail 4c. The equipment compartment fairing 4 is connected to the equipment compartment support frame 7, the slide rail bracket with reinforcing ribs 4d, and the longitudinal firewall 5b.

[0015] The present invention also provides a tiltrotor aircraft, which adopts the low-drag and easy-to-maintain tiltrotor nacelle structure described above.

[0016] This invention provides a low-drag, easy-to-maintain tiltrotor nacelle structure that protects the internal equipment and provides an internal environment suitable for the normal operation of internal accessories. The compact structure and small cross-section design reduce the overall air resistance and weight of the aircraft. This invention forms a fire-resistant design zone around the engine; in the event of an engine fire, this zone can withstand temperatures of 1100±80℃ for 15 minutes without being burned through, effectively protecting other nacelle equipment after a fire. The nacelle support frame of this invention can be easily disassembled for ground maintenance, significantly expanding the maintenance space and facilitating engine hoisting. The nacelle structure of this invention is designed with an ejector ventilation system, using the pressure difference between the inside and outside of the nacelle caused by the engine exhaust velocity to extract hot air from the nacelle, allowing air circulation to carry away hot air and ensuring that internal accessories operate within the normal temperature range. The nacelle structure of this invention features a four-stage grid air intake on the metal fairing structure, providing a large air intake volume, low wind resistance, and lightweight efficiency. An overhead heat insulation device is designed for localized overheating areas. Attached Figure Description

[0017] Figure 1 It is a tiltrotor aircraft nacelle structure; Figure 2 For nacelle movable fairing and fixed fairing; Figure 3 For the exhaust compartment fairing; Figure 4 This is a schematic diagram of the equipment compartment; Explanation of reference numerals in the attached figures: 1. Nacelle support frame; 2. Nacelle movable fairing; 3. Nacelle fixed fairing; 4. Equipment compartment fairing; 5. Nacelle firewall; 6. Exhaust compartment fairing; 7. Equipment compartment support frame. Circumferential support 1a, first longitudinal support 1b, second longitudinal support 1c, bolt 1d, upper support 1a1, lower support 1a2; Front movable fairing 2a, rear movable fairing 2b, air vent 2c, pin lock 2d, hook lock 2e, positioning pin 2f, limiting device 2g, gooseneck hinge 2h, recessed area 2i, rubber pad 2j, eccentric mechanism 2k; Nacelle front fixed cover 3a, nacelle rear fixed cover 3b, air vent 3c, nacelle lower fixed cover 3d, heat insulation device 3e, heat shield 3f, grid air vent 3g; Equipment compartment front fixed cover 4a, equipment compartment rear fixed cover 4b, slide rail 4c, slide rail bracket with reinforcing ribs 4d; Front firewall 5a, vertical firewall 5b, rear firewall 5c, ejector port 5d; Tail nozzle fairing 6a, longitudinal aluminum alloy frame 6b, transverse aluminum alloy frame 6c, longitudinal support 6d, end connecting flange 6f. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a low-drag and easy-to-maintain tiltrotor nacelle structure. The tiltrotor nacelle is generally installed at both ends of the wing, and the nacelle generally houses the engine, main anti-lubrication device and other accessories.

[0020] like Figure 1-4 The present invention provides a low-drag and easy-to-maintain tiltrotor nacelle structure, comprising: a nacelle support frame 1, a movable nacelle fairing 2, a fixed nacelle fairing 3, an equipment compartment fairing 4, a nacelle firewall 5, an exhaust compartment fairing 6, and an equipment compartment support frame 7. The nacelle support frame 1 is divided into a circumferential support 1a, a first longitudinal support 1b, and a second longitudinal support 1c. The main body of the circumferential support 1a is a machined frame with an I-shaped cross-section and fireproof function. It is fixed to the longitudinal firewall side and the wing plane by bolts 1d (bolt + nut + washer combination). Its upper flange serves as the overlapping area of ​​the nacelle movable fairing 2 and the bolt installation part of the nacelle fixed fairing 3. The main body is designed as a segmented and detachable upper support 1a1 and a lower support 1a2. The upper and lower support components are connected by four bolts 1d to form a whole. The first longitudinal support member 1b is a machined frame with an I-shaped cross-section. Before flight, it is bolted to support member 1a1 via two plates, and connected to the aft firewall 5c via bolt 1d at the rear. After removing the four bolts connecting the upper support member 1a1 and the lower support member 1a2, the bolts connecting the longitudinal firewall 5b, and the bolt 1d connecting the first longitudinal support member 1b to the aft firewall 5c after flight, the upper support member 1a1 and the first longitudinal support member 1b can be removed as a whole from above. At this time, the space above the cabin is completely unobstructed, allowing for convenient hoisting and maintenance of the engine. The second longitudinal support member 1c is a U-shaped machined frame, and its function, like that of the first longitudinal support member 1b, is to provide longitudinal support for the nacelle support frame 1.

[0021] The nacelle firewall 5 is divided into a forward firewall 5a, a longitudinal firewall 5b, and a rear firewall 5c, all of which have fire-resistant functions. In the event of an engine fire, the nacelle firewall 5, together with the movable nacelle fairing 2 and the fixed nacelle fairing 3, isolates the fire source and protects other equipment. An ejector port 5d is designed on the rear firewall 5c. This ejector port 5d utilizes the pressure difference caused by the engine exhaust velocity to extract hot air from the nacelle.

[0022] The nacelle movable fairing 2 is divided into two parts: the front movable fairing 2a and the rear movable fairing 2b. Both are primarily fire-resistant composite honeycomb sandwich structures. For quick maintenance of the engine inlet, the nacelle movable fairing 2 has a gooseneck hinge 2h at its bottom, which, along with a positioning pin 2f fixed to the wing platform, forms a rotating joint. Two hook locks 2e connect the upper edge of the nacelle movable fairing to the fixed fairing. The side edges are connected to lock seats mounted on the front firewall 5a, circumferential support 1a, and rear firewall 5c via two front and rear pin locks 2d. The pin lock 2d lock seats are designed with an eccentric adjustable mechanism 2k, allowing the center hole of the lock seat to be adjusted within a Φ3mm circumference. The upper edge of the nacelle movable fairing 2 overlaps with the recess 2i on the edge of the fixed fairing 3, and the two interlock to form an interlocking mechanism. A rubber pad 2j is added between the two overlapping areas. In the closed state, the friction generated by the locking force restricts the relative movement of the two. The interlocking structure restricts movement in the three directions other than the opening direction. This structure does not add extra weight, but only utilizes the fairing's own mechanism, so that the nacelle movable fairing 2 and the nacelle fixed fairing 3 form a mutually supporting configuration in the closed state, which can effectively restrict the in-plane movement of the movable fairing and greatly improve the overall connection rigidity of the nacelle fairing. A hook lock 2e is installed on the upper edge of the nacelle movable fairing 2, which, after locking, prevents in-plane movement. The fixed fairing 3 of the nacelle is integrated with the fixed fairing 3. Hook locks 2e are installed on the front and rear sides of the movable fairing 2 of the nacelle. After locking, the movable fairing is reliably fixed to the support frame 1 and the nacelle firewall 5. When maintenance of the engine and its accessories is required, the unlocking button can be pressed to open the latch locks 2d and 2e, allowing the front movable fairing 2a and the rear movable fairing 2b of the nacelle to open along their respective positioning pins 2f. After opening, when the movable fairing 2 needs to be removed, the positioning pins 2f are designed with a single-sided limit. A limiting device 2g is designed on the other side of the pin 2f. The limiting device 2g can limit the other side of the positioning pin 2f when the movable fairing 2 is closed, making the single-sided limiting positioning pin 2f a... The rotating shafts are fully limited at both ends. When the vehicle is parked on the ground, after the movable fairing 2 is opened to a certain angle, the limiting device 2g will release the other side of the positioning pin 2f. The movable fairing 2 can be removed by simply moving it out along the axial direction of its respective positioning pin 2f. After the movable fairing is removed, the maintenance space for ground maintenance personnel is greatly expanded. Similarly, when the movable fairing 2 needs to be installed, the mounting holes of the respective gooseneck hinges 2h are inserted into the positioning pins 2f to the limiting position. The fairing is closed until it fits the overlap area between the nacelle support frame 1 and the nacelle firewall 5. At this time, the limiting device 2g limits the other side of the positioning pin 2f. Locking the pin lock 2d and the hook lock 2e completes the closure of the movable fairing.The movable fairing 2b aft of the nacelle is located above the engine's hot zone. Based on calculations, an overhead heat shield 3e was designed for the overheated area of ​​the movable fairing 2b. This device 3e includes a heat deflector 3f above the locally high-temperature area, blocking some of the heat. The specific height of the air gap creates a flowing air heat shield layer between the movable fairing 2b and the fixed lower fairing 3d above the high-temperature area and the heat deflector 3f. Under the dual protection of the heat deflector and the flowing air layer, the movable fairing 2b aft of the nacelle avoids localized high-temperature failure.

[0023] The nacelle fixed fairing 3 is composed of three parts: the forward fixed fairing 3a, the aft fixed fairing 3b, and the lower fixed fairing 3d. All three are fire-resistant. Their main functions are to connect the nacelle support frame 1, the nacelle firewall 5, and the wing platform, enhancing the nacelle's in-plane stiffness and transferring the in-plane load across the entire forward section of the nacelle. The forward and aft fixed fairings 3a and 3b also serve as mounting points for the movable fairing hook locks, transferring the load from the movable hook locks. The nacelle ejector system bleed port 3c is also present. The forward and lower fixed fairings 3a and 3d are primarily constructed of fire-resistant composite honeycomb sandwich structures, providing fire protection. The top of the forward fixed fairing 3a has an engine accessory hot air outlet; two hook lock seats 2e, connected to the forward movable fairing 2a, are mounted on it. The aft fixed fairing 3b is located above the engine's hot zone, an area with high temperatures and heavy loads. The design leverages the high thermal conductivity and high-temperature load-bearing capacity of metals to create a fairing above the engine's hot zone that provides rapid heat conduction and fire resistance. The main body of the nacelle rear fixed fairing 3b is a riveted combination of an aluminum alloy frame and fire-resistant skin. Besides transmitting aerodynamic loads, its frame is equipped with hook lock seats connecting to the hook locks of the nacelle movable fairing 2. The aluminum alloy frame has a T-shaped reinforced structure, making it lightweight and highly rigid. The fire-resistant skin not only has strong in-plane load-bearing capacity but also fire resistance. Overall, the nacelle rear fixed fairing 3b, in addition to its high rigidity and strength under high-temperature conditions, allows for direct heat transfer from the hot zone to the outside of the fuselage, preventing overheating of internal equipment. The fire-resistant skin protects the internal fire-prone areas from escaping. The nacelle rear fixed fairing 3b features a four-stage grid-type ejector system air intake. This air intake, with its large intake volume and low height, effectively reduces wind resistance, resulting in low-resistance and high-efficiency air intake. Both the fixed lower fairing 3d and the movable rear fairing 2b of the nacelle are designed with heat insulation devices 3e in the overheating zone to prevent local high temperature failure.

[0024] The exhaust fairing 6 consists of a tail nozzle fairing 6a, a longitudinal aluminum alloy frame 6b, a transverse aluminum alloy frame 6c, a longitudinal support component 6d, and an end connecting flange 6e. By relaxing the local thickness reference value of titanium alloy superplastic forming, and utilizing the high elongation process characteristics of titanium alloy superplastic forming technology, a tail nozzle fairing 6a with a large opening, large curvature, and deep drawing integral molding and an end connecting flange 6e with a large deformation shape were designed. This process reduces the internal connections and weight of the components. In other areas, an integral lightweight and efficient aluminum alloy machined or sheet metal frame (longitudinal aluminum alloy frame 6b, transverse aluminum alloy frame 6c) and longitudinal support component 6d were designed. They are riveted together to form the internal support of the exhaust fairing 6. The exhaust fairing 6 is bolted to the aft firewall 5c, which can realize component-level disassembly and maintenance. Overall, the exhaust fairing 6 achieves the characteristics of being lightweight, resistant to high exhaust temperatures, having high load-bearing capacity, and being easy to disassemble and maintain at the rear of the nacelle.

[0025] The equipment bay structure includes an equipment bay fairing 4 and an equipment bay support frame 7. The equipment bay is located on the right side of the nacelle and is bolted to the nacelle support frame 1, the movable nacelle fairing 2, the fixed nacelle fairing 3, the nacelle firewall 5, the exhaust nacelle fairing 6, the equipment bay support frame 7, and the wing platform. The equipment bay fairing is divided into a forward fixed fairing 4a and a rear fixed fairing 4b. A sliding rail 4c for the tilting movable fairing is arranged on the upper part of the equipment bay fairing 4 and the equipment bay support frame 7, specifically located on the forward fixed fairing 4a and the rear fixed fairing 4b and extending along the heading direction through the equipment bay fairing 4 and the equipment bay support frame 7. When the tilting movable fairing moves, it moves along the sliding rail; when the tilting movable fairing is not moving, the sliding rail 4c is used to limit and fix the movement of the tilting movable fairing. Due to the presence of slide rail 4c, the equipment compartment fairing is disconnected along the flight direction, with slide rail 4c installed within the disconnected area. Because the equipment compartment fairing 4 and the equipment compartment support frame 7 are structurally fitted together, a notch is cut into the upper flange of the support frame for fixing slide rail 4c. The disconnected equipment compartment fairing 4 and the notch in the flange significantly reduce the load-bearing capacity of the equipment compartment support frame 7. By designing slide rail brackets 4d with Y-direction reinforcing ribs on both sides, the disconnected equipment compartment fairing 4 and the notch in the flange are reconnected into a single unit, greatly improving the overall rigidity and load-bearing capacity of the equipment compartment. The slide rail bracket design not only fills in the gaps in the equipment compartment fairing sections and the support flange but also strengthens the slide rail rigidity, reduces slide rail deformation under wind load, and improves the stability of the tilting fairing movement. The equipment compartment support frame 7 is an aluminum alloy frame structure with light-reducing holes, mainly used for supporting the equipment compartment fairing. It is a bolt-removable structure, allowing the equipment compartment fairing 4 and the equipment compartment support frame 7 to be removed when maintenance of the equipment inside the compartment is required.

[0026] This invention reduces the wind resistance and weight of the nacelle through a small cross-section layout; This invention employs a front firewall 5a, a longitudinal firewall 5b, a rear firewall 5c, a nacelle movable fairing 2 made of fire-resistant composite material, and a nacelle fixed fairing 3 to form a fire-resistant design area around the engine. After the engine catches fire, this area can remain unburned for 15 minutes in an environment of 1100±80℃, effectively preventing the fire from spreading to other compartments and damaging other equipment.

[0027] This invention achieves the detachability of the upper part of the circumferential support 1a by dividing the circumferential support 1a into sections and connecting them with bolts; at the same time, it removes the bolt connection between the first longitudinal support 1b and the rear firewall 5c; thus, it enables the upper frame of the power installation platform to be detached. This structure greatly expands the maintenance space and facilitates the hoisting of the engine.

[0028] The nacelle structure of this invention is generally designed with an ejector ventilation system. External air vents are designed at specific locations on the movable fairing 2 and the fixed fairing 3 of the nacelle. The pressure difference between the inside and outside of the nacelle caused by the engine exhaust velocity draws out hot air from the ejector port 5d. Simultaneously, external air is drawn in through air vents 2c, 3c, and the grille air vent 3g on the movable fairing 2 and the fixed fairing 3, thus carrying away the hot air from both inside and outside the nacelle. Cold air from outside enters the nacelle through air vents 2c, 3c, and the grille air vent 3g, forming a circulation and ensuring that the internal accessories operate within a normal temperature range. This invention utilizes the high thermal conductivity of metal in the nacelle structure by designing a metal fairing structure 3b above the engine's hot zone. This fairing 3b is a riveted combination of an aluminum alloy frame and a fire-resistant skin. Besides transmitting aerodynamic loads, its frame is equipped with hook lock seats that connect to the hook locks of the movable fairing 2 of the nacelle. The aluminum alloy frame of the metal fairing structure 3b has a T-shaped stiffened cross-section, making it lightweight and highly rigid. The skin, in addition to its strong in-plane load-bearing capacity, also has fire-resistant properties. Overall, the metal fairing structure 3b, besides its high rigidity and strength, can directly conduct heat from the hot zone to the outside of the fuselage, preventing overheating of internal equipment. The fire-resistant skin design also protects the flames from spreading outwards in the event of a fire inside the nacelle.

[0029] The nacelle structure of this invention has a four-stage grid air intake 3g with a low windward height and a specific elevation angle, which is integrally molded from composite material and designed to be lightweight and integrated on a metal fairing structure 3b. The grid air intake 3g is lightweight, efficient and has extremely low wind resistance. The four-stage grid design greatly increases the amount of air intake above the engine hot zone.

[0030] Two overhead thermal insulation devices 3e were designed in the local overheating areas of the movable fairing 2b and the fixed lower fairing 3d of the nacelle. These devices 3e have heat shields 3f above the local high-temperature areas to block some of the heat. The specific height of the overhead design creates a flowing air thermal insulation layer between the high-temperature areas of the movable fairing 2b and the fixed lower fairing 3d and the heat shield 3f. Under the dual protection of the heat shield and the flowing air layer, the movable fairing 2b and the fixed lower fairing 3d of the nacelle avoid failure due to localized high temperatures.

[0031] The nacelle structure of this invention features a front movable fairing 2a and a rear movable fairing 2b on the engine side, which can be quickly opened and removed. When the front and rear movable fairings 2a and 2b are locked, they are secured by a positioning pin 2f. After unlocking, the fairings can be rotated around the positioning pin 2f to open. The opened fairings facilitate quick engine inspection by maintenance personnel. Simultaneously, the positioning pin 2f is a single-sided limiting design, with a limiting device 2g on the other side. This limiting device 2g can limit the other side of the positioning pin 2f when the movable fairing 2 is closed. When the vehicle is parked on the ground, after the movable fairing 2 is opened to a certain angle, the limiting device 2g will release the other side of the positioning pin 2f, allowing the movable fairing 2 to be removed along the axial direction from the unlimited side of the positioning pin 2f. The detachable movable fairings significantly expand the maintenance space for ground maintenance personnel.

[0032] The nacelle structure of this invention features two additional pin locks on the front movable fairing 2a and the rear movable fairing 2b. This locking arrangement, after the movable fairing positioning pin 2f and the limiting device 2g's rotary joint limiting and hook lock tightening double limiting, allows the originally segmented movable fairing to form an integral closed cavity structure with the nacelle support frame in the closed state. This closed cavity structure can transmit multi-directional loads generated during flight, greatly improving the overall rigidity and load-bearing capacity of the nacelle. The pin lock 2d's locking seat is designed with an eccentric adjustable mechanism, allowing the center hole of the locking seat to be adjusted within a Φ3mm circumference.

[0033] In this invention, the nacelle structure on the equipment compartment side requires notches in the flanges of the equipment compartment fairing and support frame due to the need for slide rails on the upper part. These notches significantly reduce the load-bearing capacity of the equipment compartment side. This invention addresses this by designing slide rail brackets with Y-shaped reinforcing ribs on both sides of the notches. These brackets, through their own structure, fill the gaps in the equipment compartment fairing and support frame. Besides supporting the slide rails, these brackets also reassemble the disassembled equipment compartment fairing and the notched frame, greatly improving the overall rigidity and load-bearing capacity of the equipment compartment side, as well as enhancing the stability of the tilting fairing movement.

[0034] The exhaust fairing 6 is designed with a large opening, large curvature, and deep-drawn integral molded tail nozzle fairing 6a and its end connecting flange 6e by relaxing the local thickness reference value of titanium alloy superplastic molding; in other areas, an integral lightweight aluminum alloy frame and longitudinal support components 6d are designed; the exhaust fairing 6 is bolted to the rear firewall 5c, which can be easily disassembled and maintained; overall, the exhaust fairing 6 achieves the characteristics of being lightweight, resistant to high exhaust temperature, integrally disassembled and highly efficient in load bearing.

[0035] The present invention has the following advantages: The nacelle of this invention protects the equipment inside the cabin and provides an environment that allows for the normal use of the cabin accessories. Its compact structure and small cross-section design reduce the air resistance and weight of the entire machine.

[0036] The nacelle support frame 1, the movable nacelle fairing 2, the fixed nacelle fairing 3, the nacelle firewall 5, and the rear firewall 5c6 of this invention together form a fireproof design area around the engine. When the engine catches fire, this area can remain unburned for 15 minutes in an environment of 1100±80℃, effectively protecting other cabin equipment after a fire.

[0037] The nacelle support frame 1 of this invention not only provides reliable support for the movable nacelle fairing 2, the fixed nacelle fairing 3, and the equipment bay fairing 4 during flight, but also allows for easy disassembly during ground maintenance. Removing the nacelle support frame 1 greatly expands the maintenance space and facilitates the hoisting of the engine.

[0038] The nacelle structure of this invention is designed with an ejector ventilation structure. External air vents are designed at specific positions on the movable fairing 2 and the fixed fairing 3 of the nacelle. The pressure difference between the inside and outside of the nacelle caused by the exhaust speed of the engine draws out the hot air in the nacelle, so that the air inside and outside the nacelle can circulate and carry away the hot air, ensuring that the accessories in the nacelle can work within the normal temperature range. The nacelle structure of this invention features a metal fairing structure above the engine hot zone, which is a combination of an aluminum alloy frame and fireproof skin riveted together. This metal fairing is lightweight, has high load transfer efficiency, and can directly conduct heat from the hot zone to the outside. The nacelle structure of this invention features a four-stage grid air intake 3g on the metal fairing structure 3b. This grid air intake 3g has a large air intake capacity, low wind resistance, and is lightweight and efficient.

[0039] An overhead heat insulation device 3e was designed in the local overheating zone. This device forms a flowing air heat insulation layer between the force transmission composite material fairing that needs protection and the heat insulation component in the local high temperature zone, effectively protecting the force transmission composite material fairing. The nacelle structure of this invention features a movable fairing on the nacelle side that can be quickly opened and removed. The fairing is opened quickly via a pin lock, hook lock, and positioning pin structure, facilitating rapid engine inspection by maintenance personnel. Simultaneously, a limiting device 2g is designed on the other side of the pin. During flight, the limiting device 2g engages with the pin to form a rotating pair with both ends of the limiting mechanism. When the fairing is open to a certain angle on the ground, the limiting device 2g disengages, allowing the fairing to be removed entirely along the pin axis, thus expanding the ground maintenance space. The nacelle structure of this invention features two latch locks, one before and one after the two movable canopies of the nacelle. This arrangement of latch locks, combined with hook locks and directional latch design, allows the originally segmented movable canopies to form an integral closed cavity structure with the nacelle support frame when closed. This closed cavity structure can transfer multi-directional loads generated during flight, greatly improving the overall rigidity and load-bearing capacity of the nacelle. The 2d latch lock seat is designed with an eccentric adjustable mechanism 2k, allowing the center hole of the lock seat to be adjusted within a 3mm circumference.

[0040] In this invention, the nacelle structure on the equipment compartment side requires a notch design because the equipment compartment fairing and support frame need to accommodate slide rails on the upper part. This notch significantly reduces the load-bearing capacity of the equipment compartment side. This invention addresses this by designing slide rail supports with Y-direction reinforcing ribs on both sides of the notch. These slide rail supports reinforce the equipment compartment fairing sections and support frame cutouts using their own structure. Besides mounting the support slide rails, these supports also reassemble the disassembled equipment compartment fairing and the notched frame into a single unit, greatly improving the overall rigidity and load-bearing capacity of the equipment compartment side.

[0041] The nacelle structure of this invention features a tail nozzle fairing 6a with a large opening, high curvature, and deep-drawn integral molding, designed by relaxing the local thickness reference value of titanium alloy superplastic molding, and its end connecting flange 6e. In other areas, an integral lightweight and efficient aluminum alloy structure is designed and integrated with the molded tail nozzle fairing 6a. Overall, the exhaust compartment fairing 6 achieves the characteristics of being lightweight, resistant to high exhaust temperatures, easy to disassemble, and highly efficient in load-bearing capacity.

[0042] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A low-resistance easy-to-maintain tilt-rotor nacelle structure, characterized by, Comprise: Nacelle support frame (1), nacelle movable fairing (2), nacelle fixed fairing (3), equipment cabin fairing (4), nacelle firewall (5) and equipment cabin support frame (7); Nacelle support frame (1) comprises: circumferential support (1a), lower support (1a2), first longitudinal support (1b) and second longitudinal support (1c); Nacelle firewall (5) comprises: front firewall (5a), longitudinal firewall (5b) and rear firewall (5c); The longitudinal firewall (5b) is installed on the wing platform along the heading, the front firewall (5a) and the rear firewall (5c) are installed on one side of the longitudinal firewall (5b), and the equipment cabin support frame (7) is installed on the other side of the longitudinal firewall (5b), forming an engine compartment and an equipment compartment; The circumferential support (1a) is arranged between the front firewall (5a) and the rear firewall (5c); The circumferential support (1a) comprises an upper support (1a1) and a lower support (1a2) connected to each other; The other end of the upper support (1a1) is connected with the longitudinal firewall (5b), the other end of the lower support (1a2) is connected with the wing platform, the two ends of the first longitudinal support (1b) are connected with the upper support (1a1) and the rear firewall (5c) respectively, and the two ends of the second longitudinal support (1c) are connected with the lower support (1a2) and the rear firewall (5c) respectively; The nacelle fixed fairing (3) is fixed on the front firewall (5a), the longitudinal firewall (5b), the first longitudinal support (1b) and the rear firewall (5c); The upper edge of the nacelle movable fairing (2) is connected with the nacelle fixed fairing (3) through two hook locks (2e); The lower edge of the nacelle movable fairing (2) is rotatably connected to the wing platform and the second longitudinal support (1c) through a swan neck hinge; The equipment cabin fairing (4) is arranged on the equipment cabin support frame (7) and the longitudinal firewall (5b).

2. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 1, wherein, The main body of the nacelle support frame (1) is a cross-section I-shaped machine frame with fireproof function, and the whole is fixed with the side of the longitudinal firewall (5b) and the wing plane through bolts; The upper flange serves as a lap joint area of the nacelle movable fairing (2) and a bolt mounting part of the nacelle fixed fairing (3); The upper support (1a1) and the lower support (1a2) are connected into an integrated body through four bolts; The first longitudinal support (1b) is a cross-section I-shaped machine frame, which is connected with the upper support (1a1) through two upper and lower plates with bolts in front, and connected with the rear firewall (5c) through bolts (1d) at the rear; When the four bolts connecting the upper support (1a1) and the lower support (1a2) are disassembled, the longitudinal firewall (5b) connecting bolts, the first longitudinal support (1b) and the second longitudinal support (1c) are connected with the rear firewall (5c) connecting bolts, the upper support (1a1) and the first longitudinal support (1b) can be disassembled from above, at this time, the upper space in the engine compartment is completely unobstructed, and the engine can be conveniently hoisted and maintained; The second longitudinal support (1c) is a U-shaped machine frame, which provides longitudinal support for the nacelle support frame (1) and the rear firewall (5c) together with the first longitudinal support (1b).

3. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 1, wherein, The rear firewall (5c) is provided with an ejector port (5d), and the engine exhaust port is arranged in the ejector port (5d). The ejector port (5d) uses the pressure difference caused by the engine exhaust velocity to extract hot air in the engine compartment.

4. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 1, wherein, The nacelle movable fairing (2) adopts a fireproof composite honeycomb sandwich structure, which comprises a nacelle front movable fairing (2a) and a nacelle rear movable fairing (2b). The side edges of the nacelle front movable fairing (2a) and the nacelle rear movable fairing (2b) are connected to the lock seats arranged on the front firewall (5a), the circumferential support (1a) and the rear firewall (5c) through the front and rear two latch locks (2d). The nacelle front fairing (3a) and the nacelle rear fixed cover (3b) are provided with recessed areas (2i), and rubber pads (2j) are arranged in the recessed areas (2i). The upper edge of the nacelle movable fairing (2) is provided with a lap joint area matched with the recessed area (2i). The nacelle movable fairing (2) is provided with latch locks (2d) on the front and rear sides. After locking, the nacelle movable fairing (2) is fixed on the nacelle support frame (1) and the nacelle firewall (5). The positioning latch (2f) is designed as a single-side limiting device. Limiting devices (2g) are arranged between the nacelle front movable fairing (2a) and the front firewall (5a), and between the nacelle rear movable fairing (2b) and the rear firewall (5c). When the movable fairing (2) is closed, the positioning latch (2f) and the limiting device (2g) form double-side limiting for the nacelle front movable fairing (2a) and the nacelle rear movable fairing (2b). When the engine and its accessories need to be maintained, the latch locks (2d) and the hook locks (2e) are opened, the nacelle front movable fairing (2a) and the nacelle rear movable fairing (2b) are opened along the rotating shafts of the respective positioning latches (2f). After being opened to a certain angle, the limiting device (2g) releases the limiting of the movable fairing (2), and the nacelle front movable fairing (2a) and the nacelle rear movable fairing (2b) are moved out along the axial direction of the respective positioning latches (2f), so that the nacelle movable fairing (2) can be removed.

5. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 4, wherein, The lock seat of the latch lock (2d) is an eccentric adjustable mechanism (2k), and the center hole of the lock seat is adjustable within a Φ3mm circle.

6. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 4, wherein, An overhead heat insulation device (3e) is arranged in the overheated area of the inner side of the nacelle rear movable fairing (2b). The overhead heat insulation device (3e) comprises an overhead structure and a heat blocking plate (3f).

7. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 6, wherein, The nacelle fixed fairing (3) comprises a nacelle front fixed cover (3a), a nacelle rear fixed cover (3b), a nacelle lower fixed cover (3d) connected between the engine rear lower wing platform and the rear firewall (5c); The main body of the nacelle front fixed cover (3a) and the nacelle lower fixed cover (3d) is a fireproof composite honeycomb sandwich structure. The top of the nacelle front fixed cover (3a) is provided with an engine accessory hot air outlet. The main body of the nacelle rear fixed cover (3b) is a riveted combination structure of an aluminum alloy frame and a fireproof skin; the aluminum alloy frame has a T-shaped stiffened structure, and the nacelle rear fixed cover (3b) is provided with four-stage grid type injection system air inlet ports; The nacelle lower fixed cover (3d) is provided with a heat insulation device (3e) in the over-temperature zone.

8. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 7, wherein, The lower edge of the nacelle movable fairing (2a) is rotatably connected to the wing platform through a swan neck hinge (2h) and a positioning pin (2f) fixed to the wing platform; the lower edge of the nacelle movable fairing (2b) is rotatably connected to the second longitudinal support member (1c) through a swan neck hinge (2h) and a positioning pin (2f) fixed to the second longitudinal support member (1c).

9. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 1, wherein, Further comprising: An exhaust cabin fairing (6); The exhaust cabin fairing (6) comprises a tail jet fairing (6a), a longitudinal aluminum alloy frame (6b), a transverse aluminum alloy frame (6c), a longitudinal support member (6d) and a terminal connection flange (6e); The longitudinal aluminum alloy frame (6b), the transverse aluminum alloy frame (6c) and the longitudinal support member (6d) are riveted and combined to form internal support of the exhaust cabin fairing (6); the whole exhaust cabin fairing (6) is bolted to the rear firewall (5c).

10. The low-drag, low-maintenance, tilt-rotor nacelle structure of claim 1, wherein, A longitudinal arrangement of a reinforced slide rail support (4d) is arranged in the notch of the upper flange of the middle frame of the equipment cabin support frame (7), and a slide rail (4c) is fixedly installed in the reinforced slide rail support (4d); The equipment cabin fairing (4) is provided with a breakage exposing the slide rail (4c), and the equipment cabin fairing (4) is connected with the equipment cabin support frame (7), the reinforced slide rail support (4d) and the longitudinal firewall (5b).

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