Flat threshold maintenance access structure and method of operation

Abstract

The application provides a flat threshold maintenance passage structure and an operation method. The structure comprises a large opening reinforcing structure assembly 100, a quick-release floor assembly 200, a footboard assembly 300, a door frame assembly 400, a stepping reinforcing assembly 500, a mechanical support rod assembly 600, a bolt locking mechanism 700, a maintenance passage door 800, an external hinge 900 and a boarding handle 1000. The large opening reinforcing structure assembly 100 comprises an upper reinforcing horizontal piece 101, a lower reinforcing horizontal piece 102, a reinforcing front partition frame 103, a reinforcing rear partition frame 104, a horizontal piece outer flange 105, a stretching belt plate 106, an upper horizontal piece inner flange 107, a stretching belt plate 108, a lower horizontal piece inner flange 109, a counter-pulling angle box 110 and a counter-pulling angle piece 111. The quick-release floor assembly 200 comprises an upper panel 201, an aluminum honeycomb 202, a lower panel 203 and a bowl-shaped piece 204. The footboard assembly 300 comprises a foldable cantilever footboard 301, a locking mechanism 302, a bolt 303, a partition frame T-shaped outer flange 304, a support lug 305, a rib 306 and a stepping pedal 307. The door frame assembly 400 comprises a door frame 401 and a skin 402.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of machine body structure, in particular to a flat threshold maintenance access structure and an operation method. BACKGROUND

[0002] To meet the maintenance requirements of the aircraft, a maintenance access is usually provided on the aircraft, which includes an out-of-cabin boarding access, a hatch and an in-cabin maintenance access. The arrangement needs to consider the size of the maintenance space, the transmission of the load, the feasibility of approaching the access, the accessibility of the operation space, the sealing, the aerodynamic resistance, the anti-tripping, the reliability and other factors. A reasonable maintenance access design can greatly improve the operation efficiency of the maintenance personnel and ensure the service rate of the aircraft.

[0003] The maintenance access needs to be provided with a large opening on the skin. The large opening destroys the complete force transmission structure of the fuselage, and the machine body needs to be designed with an opening reinforcement to ensure that the fuselage structure meets the requirements of stiffness continuity, i.e. deformation coordination. When the maintenance personnel step or step over the threshold to directly step on the bottom skin, the metal threshold has the risk of deformation and cracking, the composite threshold has the risk of deformation and delamination, and the bottom skin has the risk of honeycomb debonding. When the bottom skin is arranged with more avionics equipment and cables, the equipment and cables should be designed to have protection measures to avoid being stepped on, such as a floor, and the upper surface of the floor should be kept as flat as possible. When the threshold is high from the ground, an access to the in-cabin needs to be arranged. In order to ensure the integrity of the sealing of the machine body after the large opening of the machine skin, the installation surface of the rubber strip of the door frame and the stiffness of the door frame need to be reasonably designed. The installation of the lower locking point of the maintenance access door locking mechanism should not have the possibility of tripping the maintenance personnel. SUMMARY

[0004] The present application provides a flat threshold maintenance access structure design method, which reasonably arranges the force transmission path, selects a suitable configuration of the floor, arranges a height suitable foldable cantilever footstep, determines a reasonable cross-sectional form of the door frame, and designs a stepping function and a locking point installation method to avoid the above risks.

[0005] In a first aspect, the present application provides a flat threshold maintenance access structure, which comprises a large opening reinforcement structure assembly 100, a quick-release floor assembly 200, a footstep assembly 300, a door frame assembly 400, a stepping reinforcement assembly 500, a mechanical support rod assembly 600, a bolt locking mechanism 700, a maintenance access door 800, an external hinge 900 and a boarding handle 1000, wherein:

[0006] The large opening reinforcing structure assembly 100 includes upper reinforcing horizontal piece 101, lower reinforcing horizontal piece 102, reinforcing front bulkhead 103, reinforcing rear bulkhead 104, horizontal piece outer flange 105, stretch belt plate 106, upper horizontal piece inner flange 107, stretch belt plate 108, lower horizontal piece inner flange 109, counter pull angle box 110, counter pull angle sheet 111; the quick-release floor assembly 200 includes upper panel 201, aluminum honeycomb 202, lower panel 203, bowl-shaped piece 204; the footrest assembly 300 includes foldable cantilever footrest 301, locking mechanism 302, bolt 303, bulkhead T-shaped outer flange 304, support lug 305, rib 306, footrest pedal 307; the door frame assembly 400 includes door frame 401, skin 402, sealant strip mounting surface 403, small flange 404, notch 405, water guide groove 406; the footrest reinforcing piece assembly 500 includes first footrest reinforcing piece 501, vertical rib 502, footrest protrusion 503, second footrest reinforcing piece 504; the mechanical stay assembly 600 includes mechanical stay 601, ball head rod 602, hinge sheet 603, hinge support 604, ball head rod support seat 605, spring clamp 606, thermoplastic tube 607; the latch locking mechanism 700 includes three-lock-point latch 701, front lock point 702, rear lock point 703, latch support 704, lower lock point 705, sunken groove 706, latch support upper latch hole 707, lower lock point lock seat 708;

[0007] The maintenance access door 800 is installed on the skin large opening through the external hinge 900, the footrest assembly 300 is located outside the skin, the large opening reinforcing structure assembly 100 is a reinforcing measure for the large opening on the skin, the quick-release floor assembly 200 is located inside the skin and is installed on the large opening reinforcing structure assembly 100, the door frame assembly 400 is riveted to the large opening reinforcing structure assembly 100 of the skin through rivets, the maintenance access door 800 is locked and opened through the latch locking mechanism 700, and the mechanical stay assembly 600 is used to keep the opening state;

[0008] Specifically, the upper reinforcing horizontal piece 101 is arranged at the upper part of the large opening of the skin, and the reinforcing horizontal piece 102 is arranged at the lower part of the large opening of the skin; the reinforcing front bulkhead 103 and the reinforcing rear bulkhead 104 are arranged in front of and behind the large opening of the skin; the upper reinforcing horizontal piece 101 and the lower reinforcing horizontal piece 102 respectively extend to the front and rear of the large opening of the skin by a distance of one opening width, and the reinforcing front bulkhead 103 and the reinforcing rear bulkhead 104 respectively extend by a distance of one opening height; the upper horizontal piece inner flange 107 is provided with a stretch belt plate 108 at the position where the bulkhead is disconnected to transfer the heading load; the upper reinforcing horizontal piece and the lower reinforcing horizontal piece outer flange 105 are designed with a stretch belt plate 106 at the disconnected position to transfer the heading load; when the reinforcing front bulkhead 103 inner flange is of an L-shaped section, the lower horizontal piece inner flange 109 is designed with a pull angle box 110 at the position where the bulkhead is disconnected to transfer the heading load; when the reinforcing rear bulkhead 104 inner flange is of a T-shaped section, the lower horizontal piece inner flange 109 is designed with a pull angle piece 111 at the position where the bulkhead is disconnected to transfer the heading load.

[0009] Specifically, the foldable cantilever footrest 301 is installed on the bulkhead T-shaped outer flange 304 by using a bolt 303, and the moment formed by the vertical load of the stepping point around the shaft of the support lug 305 is balanced by the tension and compression of the bolt 303 arranged along the span of the aircraft; the gusset of the reinforcing rear bulkhead 104 near the hole position of the bolt 303 is arranged with a rib 306 in the vicinity to facilitate the transfer of load; the foldable cantilever footrest 301 is buckled with the locking mechanism 302 installed on the skin of the fuselage in the closed state.

[0010] Specifically, the structural configuration of the door frame assembly 400 includes a first door frame form and a second door frame form, and the cross-sectional form of the door frame 401 includes a first cross-sectional form and a second cross-sectional form.

[0011] The first door frame form is that the normal of all the rubber strip installation surfaces 403 is perpendicular to the skin 402 profile, and the closing force of the maintenance access door 800 is positively pressed on the rubber strip; the second door frame form is that the left and right sides and the upper part of the rubber strip installation surface 403 are at a certain angle with the normal of the skin, and the lower part of the rubber strip installation surface 403 is perpendicular to the skin; the first cross-sectional form is a Z-shaped section with a bent edge, the sealing rubber strip is fixed on the rubber strip installation surface 403, and the rubber strip installation surface 403 is provided with a small flange 404, and the draft angle of the small flange 404 ranges from 1° to 2°; the second cross-sectional form is a C-shaped variable cross-section, and the upper part of the rubber strip installation surface 403 located on the left, right and upper part of the door frame 401 is provided with a water guide groove 406, and the upper part of the rubber strip installation surface 403 located below the door frame 401 is not provided with a water guide groove.

[0012] Specifically, the first section form door frame below with notched 405 for installing the first step reinforcement 501, the first step reinforcement 501 upper surface flush with the upper surface of quick release floor assembly 200; The first step reinforcement 501 is provided with a step protrusion 503; The second section form door frame below installs the second step reinforcement 504, and the second step reinforcement 504 and the door sill of the door frame 401 form a closed mouth-shaped structure.

[0013] Specifically, the maintenance access door is arranged with a support rod 601, one end of the support rod 601 is a ball head rod 602, the ball head rod 602 is installed at the end of the mechanical support rod 601 through a self-locking nut; The other end of the support rod 601 is a hinge piece 603 and a hinge support 604, the hinge piece 603 and the support rod 601 are connected through a bolt, a slot nut and a split pin, and the connection should ensure that the support rod can rotate freely; The both sides of the hinge support 604 are arranged with vertical ribs, which can improve the bending resistance of the hinge; The hinge bolts are arranged in two columns to form the bending resistance; After the door body is opened, the ball head rod 602 at the end of the support rod 601 is inserted into the groove of the ball head rod support seat 605 on the partition frame, so that the hatch door remains open; When the hatch door is closed, the support rod 601 is fixed in the spring clamp 606 on the door body, and a thermoplastic tube 607 is sleeved on the support rod at the contact position of the support rod 601 and the spring clamp 606.

[0014] Specifically, the front lock point 702 and the rear lock point 703 are arranged on the outer flanges of the pre-flight frame and the post-flight frame respectively; The bolt support 704 of the front lock point 702 and the rear lock point 703 is fixed on the front and rear reinforced partition frame and is not connected with the door frame; The lower lock point 705 is arranged on the horizontal plane of the first step reinforcement 501, and the first step reinforcement 501 is provided with a sunken groove 706 at the lock point mounting position, so that the upper surface of the lock seat is flush with the upper surface of the floor; Each bolt support is provided with a guide slope on the bolt hole 707 to ensure smooth insertion of the bolt; The width of the horizontal plane of the step reinforcement is determined according to the required adjustment width of the lower lock point lock seat 708.

[0015] Specifically, two external hinges 900 are arranged on the upper horizontal piece of the maintenance access door 800.

[0016] In a second aspect, the application provides an operation method of the flat-sill maintenance access structure, which comprises:

[0017] Step 1: press the lock catch on the foot pedal assembly 300 to open the foot pedal assembly 300;

[0018] Step 2: rotate the bolt lock closing mechanism 700 to open the maintenance access door 800;

[0019] Step 3: use the mechanical support rod assembly 600 to support the maintenance access door 800;

[0020] Step 4: when entering the cabin, step on the foot pedal assembly 300 with the right foot;

[0021] Step 5: Hold the boarding handle 1000 above the foot pedal assembly 300, step on the quick-release floor assembly 200 and the pedal reinforcing assembly 500 with the left foot to enter the cabin maintenance passage;

[0022] Step 6: Access other locations in the cabin through the quick-release floor assembly 200;

[0023] Step 7: Reset the mechanical support rod assembly 600, reset the bolt lock mechanism 700, and close the maintenance passage door 800;

[0024] Step 8: Reset the foot pedal assembly 300.

[0025] In summary, the flat threshold maintenance passage structure and operation method provided by the application have the following advantages:

[0026] 1) Safe and reliable: the large opening is reinforced, the lower threshold is designed to resist stepping, the threshold is flush with the floor, and the seal is complete;

[0027] 2) Simple to use and easy to maintain: the folding foot pedal is simple and convenient to open and close, and the hatch is simple and convenient to open and close;

[0028] 3) Wide range of applications: the configuration in the application or similar configurations derived from the application can be used in any flat threshold maintenance passage structure design;

[0029] 4) Light weight: the design method of improving the out-of-plane stiffness of the skin, the use of the pull angle box and the pull angle piece, the selection of the floor configuration, and the use of the hatch mechanical support rod make the maintenance passage structure as light as possible. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A schematic diagram of a flat threshold maintenance passage structure provided by the application;

[0031] Figure 2 A schematic diagram of a skin large opening reinforcing design structure provided by the application;

[0032] Figure 3 A schematic diagram of a reinforced horizontal piece outer flange load transfer provided by the application;

[0033] Figure 4 A schematic diagram of a lower horizontal piece inner flange heading load transfer provided by the application;

[0034] Figure 5 A schematic diagram of a floor structure provided by the application;

[0035] Figure 6 A schematic diagram of a foldable cantilever foot pedal structure provided by the application;

[0036] Figure 7 A schematic diagram of a foot pedal structure provided by the present application;

[0037] Figure 8-1 is a schematic diagram of a first door frame structure provided by the present application;

[0038] Figure 8-2 is a schematic diagram of a second door frame structure provided by the present application;

[0039] Figure 9-1 is a schematic diagram of a first door frame structure foot pedal reinforcing member mounting structure provided by the present application;

[0040] Figure 9-2 is a schematic diagram of a second door frame structure foot pedal reinforcing member mounting structure provided by the present application;

[0041] Figure 10 A schematic diagram of a three locking point latch and brace structure provided by the present application;

[0042] Figure 11 A schematic diagram of a hatch hinge and boarding handle structure provided by the present application;

[0043] Wherein: 100 - large opening reinforcing structure assembly, 101 - upper reinforcing horizontal member, 102 - lower reinforcing horizontal member, 103 - reinforcing front bulkhead, 104 - reinforcing rear bulkhead, 105 - horizontal member outer flange, 106 - stretch band plate, 107 - upper horizontal member inner flange, 108 - stretch band plate, 109 - lower horizontal member inner flange, 110 - opposing pull angle box, 111 - opposing pull angle piece, 200 - quick release floor assembly, 201 - upper panel, 202 - aluminum honeycomb, 203 - lower panel, 204 - bowl-shaped member, 300 - foot pedal assembly, 301 - foldable cantilever foot pedal, 302 - locking mechanism, 303 - bolt, 304 - bulkhead T-shaped outer flange, 305 - support ear piece, 306 - rib, 307 - foot pedal, 400 - door frame assembly, 401 - door frame, 402 - skin, 403 - sealant strip mounting surface, 404 - small flange, 405 - notch, 406 - water guide channel, 500 - foot pedal reinforcing member assembly, 501 - first foot pedal reinforcing member, 502 - vertical rib, 503 - foot pedal protrusion, 504 - second foot pedal reinforcing member, 600 - mechanical brace assembly, 601 - brace, 602 - ball head rod, 603 - hinge piece, 604 - hinge support, 605 - ball head rod support seat, 606 - spring clamp, 607 - plastic sleeve, 700 - latch locking mechanism, 701 - three locking point latch, 702 - front locking point, 703 - rear locking point, 704 - latch support, 705 - lower locking point, 706 - sinking groove, 707 - upper latch hole of latch support, 708 - lower locking point lock seat, 800 - maintenance access door, 45 - external hinge, 46 - boarding handle. DETAILED DESCRIPTION

[0044] Example One

[0045] As Figure 1 shown, the present application provides a flat threshold maintenance access structure, comprising a large opening reinforcing structure assembly 100, a quick-release floor assembly 200, a footrest assembly 300, a door frame assembly 400, a stepping reinforcement assembly 500, a mechanical support rod assembly 600, a latch locking mechanism 700, a maintenance access door 800, and an external hinge 900, wherein:

[0046] The large opening reinforcing structure assembly 100 comprises an upper reinforcing horizontal piece 101, a lower reinforcing horizontal piece 102, a reinforcing front partition frame 103, a reinforcing rear partition frame 104, a horizontal piece outer flange 105, a stretch belt plate 106, an upper horizontal piece inner flange 107, a stretch belt plate 108, a lower horizontal piece inner flange 109, a pair of pull angle boxes 110, a pair of pull angle pieces 111; the quick-release floor assembly 200 comprises an upper panel 201, an aluminum honeycomb 202, a lower panel 203, a bowl-shaped piece 204; the footrest assembly 300 comprises a foldable cantilever footrest 301, a locking mechanism 302, a bolt 303, a partition frame T-shaped outer flange 304, a support ear piece 305, a rib 306, a stepping pedal 307; the door frame assembly 400 comprises a door frame 401, a skin 402, a sealant strip mounting surface 403, a small flange 404, a notch 405, a water guide groove 406; the stepping reinforcement assembly 500 comprises a first stepping reinforcement 501, a vertical rib 502, a stepping protrusion 503, a second stepping reinforcement 504; the mechanical support rod assembly 600 comprises a support rod 601, a ball head rod 602, a hinge piece 603, a hinge support 604, a ball head rod support seat 605, a spring clamp 606, a thermoplastic tube 607; the latch locking mechanism 700 comprises a three-lock-point latch 701, a front lock point 702, a rear lock point 703, a latch support 704, a lower lock point 705, a sunken groove 706, a latch support upper latch hole 707, a lower lock point lock seat 708;

[0047] The maintenance access door 800 is installed on the skin large opening through the external hinge 900, the foot pedal assembly 300 is located outside the skin, the large opening reinforcing structure assembly 100 is a reinforcing measure of the large opening of the skin, the quick-release floor assembly 200 is located inside the skin and is installed on the large opening reinforcing structure assembly 100, the door frame assembly 400 is riveted on the large opening reinforcing structure assembly 100 of the skin through rivets, the maintenance access door 800 is locked and opened through the latch lock mechanism 700, and the opening state is maintained through the mechanical support rod assembly 600; in the closed state of the maintenance access, the foot pedal assembly 300 and the maintenance access door 800 are closed; when the maintenance access is opened, the foot pedal assembly 300 is opened in the first step, the maintenance access door 800 is opened by rotating the latch lock mechanism 700 in the second step, and the maintenance access door 800 is supported by using the mechanical support rod assembly 600; when entering the cabin, the right foot is stepped on the foot pedal assembly 300 in the first step, the left foot is stepped on the quick-release floor assembly 200 and the stepping reinforcing assembly 500 in the second step, the boarding handle 1000 above the foot pedal assembly 300 is gripped, and the maintenance access in the cabin is entered; the other positions in the cabin can be entered through the quick-release floor assembly 200.

[0048] Specifically, the upper reinforcing horizontal piece 101 is arranged at the upper portion of the skin large opening, and the lower reinforcing horizontal piece 102 is arranged at the lower portion of the skin large opening; the reinforcing front partition 103 and the reinforcing rear partition 104 are arranged in front of and behind the large opening; the upper reinforcing horizontal piece 101 and the lower reinforcing horizontal piece 102 respectively extend to a distance of one opening width in front of and behind the skin large opening, and the reinforcing front partition 103 and the reinforcing rear partition 104 respectively extend to a distance of one opening height upward and downward; the upper horizontal piece inner flange 107 is provided with a stretch belt plate 108 at the position where the partition is disconnected to transfer the heading load; the outer flange 105 of the upper reinforcing horizontal piece and the lower reinforcing horizontal piece is designed with a stretch belt plate 106 at the disconnected position to transfer the heading load; when the inner flange of the reinforcing front partition 103 is an L-shaped section, the lower horizontal piece inner flange 109 is designed with a pull angle box 110 at the position where the partition is disconnected to transfer the heading load; when the inner flange of the reinforcing rear partition 104 is a T-shaped section, the lower horizontal piece inner flange 109 is designed with a pull angle piece 111 at the position where the partition is disconnected to transfer the heading load.

[0049] As Figure 2As shown in Figure 4, the large opening size of the skin, i.e., the maintenance access door size, is 750mm in height and 500mm in width (minimum width 480mm) to meet the ergonomic design requirements. To compensate for the bending capacity of the cut skin, the reinforced frame has a certain web height to improve the rigidity of the skin opening area. The axial force on the cut skin is transferred to the horizontal member and the frame through skin shearing. To diffuse the load, the reinforced horizontal member extends forward and backward by a distance equal to the width of the opening, and the reinforced frame extends upward and downward by a distance equal to the height of the opening. The inner flange 107 of the upper horizontal member is designed with a tension plate 108 at the location where the frame is broken to transfer the yaw load.

[0050] like Figure 5 As shown, the quick-release floor assembly 200 is used as an in-cabin maintenance passage. The quick-release floor assembly 200 adopts a configuration of upper panel 201 + aluminum honeycomb 202 + lower panel 203. The panel material is 2A12. Compared with reinforced wall panel flooring, this configuration has a higher flexural section modulus for the same weight. Compared with fiber panel + honeycomb flooring, it has a similar weight but stronger impact resistance, and its removable function ensures accessibility to the space below the floor. At the bolt connection, a recessed bowl-shaped part 204 is embedded in the upper surface of the floor. The bowl-shaped part 204 is a sheet metal part made of 0Cr18Ni9 material with a thickness of 0.3mm. It is bonded to the aluminum honeycomb 202 through-hole filler with structural adhesive. The bowl-shaped part 204 is acid-washed to increase the bonding strength. At the bolt connection, self-locking bracket nuts are installed on the lower surface of the frame flange, beam flange, and horizontal reinforcement. The bolts and washers are recessed and installed in the bowl-shaped part 204 to ensure that they do not protrude from the upper surface of the floor.

[0051] Specifically, the foldable cantilever foot pedal 301 is installed on the T-shaped outer flange 304 of the bulkhead using bolts 303. The torque Mx formed by the vertical load at the stepping point around the axis of the support lug 305 is balanced by the tension and compression of the bolts 303 arranged along the Y direction. Ribs 306 are arranged near the bolt holes on the web of the rear bulkhead 104 to facilitate load transfer. When the foldable cantilever foot pedal 301 is closed, it is engaged with the locking mechanism 302 installed on the fuselage skin.

[0052] Specifically, a footrest is installed directly below the threshold of door frame 401.

[0053] like Figure 6 As shown, when the threshold is high and the frequency of being stepped on is not high, a foldable cantilever foot pedal 301 can be arranged in an appropriate position to facilitate access to the maintenance passage. When the foldable foot pedal is open, the lowest step surface should not be higher than 600mm from the ground. When closed, it is fastened to the locking mechanism 302 installed on the fuselage skin. When closed, the shape of the foldable foot pedal should be as smooth as possible to reduce aerodynamic resistance.

[0054] like Figure 7As shown, when the threshold is high and the frequency of stepping on is high, the stepping pedal 307 can be installed right below the threshold, and the installation point should be supported by the reinforced horizontal piece of the lower part of the opening.

[0055] Specifically, the structural configuration of the door frame assembly 400 includes a first door frame form and a second door frame form, and the cross-sectional form of the door frame 401 includes a first cross-sectional form and a second cross-sectional form.

[0056] The first door frame form is that the normal of all the rubber strip installation surfaces 403 is perpendicular to the outer shape of the skin 402, and the closing pressure of the maintenance access door 800 is positively pressed on the rubber strip; the second door frame form is that the normals of the left and right sides and the upper part of the rubber strip installation surface 403 form a certain angle with the normal of the skin, and the normal of the lower part of the rubber strip installation surface 403 is perpendicular to the skin; the first cross-sectional form is a Z-shaped cross section with a bent edge, the sealing rubber strip is fixed on the rubber strip installation surface 403, the rubber strip installation surface 403 has a small flange 404, and the draft angle of the small flange 404 ranges from 1° to 2°; the second cross-sectional form is a C-shaped variable cross section, and a water guide groove 406 is arranged above the rubber strip installation surface 403 located on the left, right and upper part of the door frame 401, and no water guide groove is arranged above the rubber strip installation surface 403 located below the door frame 401.

[0057] The door frame 401 is manufactured separately from the skin 402 to avoid the hidden danger of disassembling the skin caused by the damage of the door frame during the service of the aircraft; the cross-sectional form of the door frame can be divided into different configurations according to specific needs, and two common forms are provided below:

[0058] As shown in FIG. 8-1, the small flange 404 of the first cross-sectional form door frame can avoid the emergence of the free edge of the rubber strip installation surface, thereby greatly improving the bending resistance of the cross section; due to the complex forming of this cross-sectional form door frame, a composite material forming process is adopted, and the glass cloth with good impact resistance is selected as the composite material; the small flange 404 has a draft angle of 1° to 2° to facilitate the process manufacturing demolding and improve the surface quality; due to the large size occupied by the rubber strip installation surface, this configuration is suitable for use in the case where the size of the cabin door opening is sufficient;

[0059] As shown in FIG. 8-2, the normals of the left and right sides and the upper part of the second cross-sectional form rubber strip installation surface 403 form a certain angle with the normal of the skin, and the normal of the lower part of the rubber strip installation surface 403 is perpendicular to the skin; when the space of the access door opening is tight, the width value of the rubber strip installation surface is required to be large, and this door frame form can be selected to save space; due to the complex forming of this cross-sectional form door frame, a composite material forming process is adopted, and the glass cloth with good impact resistance is selected as the composite material;

[0060] Specifically, the first section form door frame below with notched 405 for installing the first step reinforcement 501, the first step reinforcement 501 upper surface flush with the quick disassembly floor assembly 200 upper surface; the first step reinforcement 501 is provided with a step protrusion 503; the second section form door frame below installs the second step reinforcement 504, and the second step reinforcement 504 and the door sill of the door frame 401 form a closed mouth-shaped structure.

[0061] As shown in Figure 9-1, the step reinforcement 501 material aluminum alloy, every 100-150mm is arranged with a vertical rib 502 to improve the local bending capacity, and the vertical rib 502 is connected with the lower horizontal reinforcement 102 through a three-corner box rivet connection, so that the step load is transmitted to the lower horizontal reinforcement 102, and a peelable gasket or the like can be installed between the three-corner box and the upper surface of the step reinforcement 501 to compensate for the gap; the upper surface of the first step reinforcement 501 is flush with the upper surface of the quick disassembly floor assembly 200; the first step reinforcement 501 is designed with a step protrusion 503 to avoid the occurrence of step delamination and other failures caused by the use of composite door frames; the door sill of the door frame 401 is connected with the first step reinforcement 501 through a countersunk rivet to ensure the adhesion performance of the sealant and the door frame 401.

[0062] As shown in Figure 9-2, the second section form door frame 401 below installs the second step reinforcement 504, and the second step reinforcement 504 material aluminum alloy, the second step reinforcement 504 and the door sill of the door frame 401 form a closed "mouth" shaped structure, forming a good anti-step capacity.

[0063] Specifically, the maintenance passage door inside upper part is arranged with a support rod 601, one end of the support rod is a ball head rod 602, the other end is a hinge piece 603 and a hinge support 604, and the hinge piece 603 and the hinge support 604 can be connected through a through bar and an open pin or a flat head pin and an open pin and the like; the hinge piece 603 and the support rod 601 are connected through a bolt, a slot nut and an open pin, and the hinge support 604 is arranged with vertical ribs on both sides; when the door body is opened, the ball head rod 602 at the end of the support rod is inserted into the groove of the ball head rod support seat 605 of the partition frame, so that the hatch door remains open; when the hatch door is closed, the support rod is fixed in the spring clamp 606 on the door body, and the support rod 601 is sleeved with a thermoplastic tube 607 at the contact position with the spring clamp 606.

[0064] As Figure 10As shown, the maintenance access door is internally arranged with a support rod 601, the length of the support rod 601 should not be greater than the width of the maintenance access door 800, one end of the support rod is a ball head rod 602, the ball head rod is installed on the end of the support rod through a self-locking nut; the other end of the support rod is a hinge piece 603 and a hinge support 604, the hinge piece 603 and the hinge support 604 can be connected through a through bar and a split pin or a flat head pin and a split pin and the like; the hinge piece 603 and the support rod 601 are connected through a bolt, a slot nut and a split pin, and after connection, the support rod should be able to rotate freely; the hinge support 604 is arranged with vertical bars on both sides, which can improve the bending resistance of the hinge, and the bolts on the hinge are arranged in two columns to form bending resistance; the opening angle of the hatch should not be able to knock the head of the maintenance personnel; after the hatch is opened, a circle is drawn with the mechanical support rod starting point as the center and the length of the support rod 601 as the radius, and the intersection of the circle and the door frame assembly 400 is the position of the upper ball head rod support seat 605 of the partition frame; the ball head rod 602 at the end of the support rod is inserted into the groove of the upper ball head rod support seat 605 of the partition frame after the door body is opened, so that the hatch is kept open; when the hatch is closed, the support rod 601 is fixed in the spring clamp 606 on the door body, the contact position of the support rod 601 and the spring clamp 606, a thermoplastic tube 607 is sleeved on the support rod to protect the surface of the support rod and reduce the friction force of the support rod clamped into the spring clamp, the diameter of the thermoplastic tube 607 should be greater than the minimum size of the two rod ends of the support rod 601 to be sleeved into the support rod 601; the direction of pulling out the support rod 601 from the spring clamp 606 is the direction of rotating the hinge shaft of the support rod to eliminate the moment of the force acting on the hinge support when the support rod is pulled out.

[0065] Specifically, the front locking point 702 and the rear locking point 703 are arranged on the outer flanges of the front and rear frames respectively; the bolt support 704 of the front locking point 701 and the rear locking point 703 is fixed on the front and rear partition frames and is not connected with the door frame; the lower locking point 705 is arranged on the horizontal plane of the first tread reinforcement 501, the locking point installation position is provided with a sunken groove 706, so that the upper surface of the locking seat is flush with the upper surface of the floor; each bolt support is provided with a guide slope to ensure smooth insertion of the bolt; the width of the tread reinforcement horizontal plane is determined according to the required adjustment width of the lower locking point locking seat 708.

[0066] As shown in Figure 10 The maintenance access door locking mechanism adopts a three-locking-point bolt lock 700 configuration, which can effectively bear the in-plane and out-of-plane pressure difference of the load such as gun shock load.

[0067] Specifically, two external hinges 900 are arranged on the upper horizontal piece of the maintenance access door 800, and the hatch has the same motion trajectory, which is lighter than the structure of the built-in hinge.

[0068] As shown in Figure 11As shown, the threshold is arranged with a boarding handle 1000 above the threshold, which is convenient for maintenance personnel to enter the cabin; the boarding handle 1000 is connected to the outer flange of the bulkhead through four upper and lower bolts, and the corresponding bolt positions are arranged with upper and lower vertical ribs on the web of the bulkhead.

[0069] 2) The key points of the present application are:

[0070] 1) The outer stiffness of the skin surface is improved by using the high web surface of the bulkhead and the horizontal piece, instead of increasing the thickness of the skin, and the weight is lighter;

[0071] 2) The load of the horizontal piece inner flange is transmitted by using the pull angle box and the pull angle sheet instead of using the stretch belt plate, avoiding the perforation on the web of the bulkhead and paying more weight cost;

[0072] 3) The detachable floor structure selects the aluminum panel aluminum honeycomb sandwich structure, which has higher bending section modulus and stronger impact resistance;

[0073] 4) The detachable floor uses bowl-shaped pieces to fix bolts, which can ensure the flatness of the maintenance channel as much as possible;

[0074] 5) Two configurations of the stepping footboard and the installation mode are provided according to different situations to meet the boarding requirements in different use situations;

[0075] 6) The door frame and the skin are manufactured separately to avoid the hidden danger of disassembling the skin caused by the damage of the door frame during the service of the aircraft;

[0076] 7) Two configurations of the threshold are provided according to different situations, and the section form, material selection and anti-treading design of the threshold of different configurations are given;

[0077] 8) The locking point installation position is provided by using the treading reinforcement, and the reinforcement at the locking point is designed with a sinking groove to ensure that the locking seat is flush with the floor, and the width of the reinforcement is determined according to the adjustment amount of the locking seat;

[0078] 9) The three-lock-point bolt lock bolt support is designed as a guide slope to ensure smooth locking without jamming; all the bolt supports are fixed on the bulkhead to avoid riveting with the door frame to protect the door frame;

[0079] 10) The external hinge is arranged above the maintenance channel door, which has better stiffness and lighter weight than the built-in goose neck hinge;

[0080] 11) The maintenance channel door adopts a mechanical stay rod, and the arrangement and more reasonable opening and closing direction of the stay rod are given; the stay rod hinge support can bear the out-of-plane load, the stay rod assembly is light in weight and convenient and reliable to use, and the occurrence of similar air pressure stay rod pressure relief, oil leakage and other faults can be avoided;

[0081] In summary, the flat threshold maintenance channel structure provided by the present application has the following advantages:

[0082] 1) safe and reliable: large opening for reinforcement design, the lower threshold for anti-treading design, the threshold is flush with the floor, sealing is complete;

[0083] 2) simple to use and easy to maintain: folding foot pedal opening and closing and disassembly and assembly are convenient, and the hatch opening and closing are simple and convenient;

[0084] 3) wide application range: the configuration in the invention or similar configuration derived from the invention can be used in any flat threshold maintenance passage structure design;

[0085] 4) light weight: the design method of improving the skin surface stiffness, the use of tension angle box and tension angle sheet, the selection of floor configuration, and the use of hatch mechanical support rod make the maintenance passage structure as light as possible.

[0086] ②Effect and benefit:

[0087] At present, the flat threshold maintenance passage structure has been implemented on the machine, and the actual effect is good.

[0088] Example two

[0089] The embodiment of the application provides an operating method of a flat threshold maintenance passage with sealing function, which comprises the following steps:

[0090] Step 1: press the lock catch on the foot pedal assembly 300 to open the foot pedal assembly 300;

[0091] Step 2: rotate the latch locking mechanism 700 to open the maintenance passage door 800;

[0092] Step 3: use the mechanical support rod assembly 600 to support the maintenance passage door 800;

[0093] Step 4: when entering the cabin, step on the foot pedal assembly 300 with the right foot;

[0094] Step 5: hold the boarding handle 1000 above the foot pedal assembly 300 with the left foot, step on the quick-release floor assembly 200 and the treading reinforcement assembly 500 to enter the cabin maintenance passage;

[0095] Step 6: through the quick-release floor assembly 200, enter other positions in the cabin;

[0096] Step 7: reset the mechanical support rod assembly 600, reset the latch locking mechanism 700, and close the maintenance passage door 800;

[0097] Step 8: reset the foot pedal assembly 300.

Claims

1. A flat threshold maintenance access structure, characterized by, The application relates to a large-opening reinforcing structure assembly, a quick-release floor assembly, a footrest assembly, a door frame assembly, a footrest reinforcing assembly, a mechanical support rod assembly, a bolt lock mechanism, a maintenance access door and an external hinge, and an entry handle, wherein: The large-opening reinforcing structure assembly comprises upper reinforcing horizontal pieces, lower reinforcing horizontal pieces, reinforcing front partition frames, reinforcing rear partition frames, horizontal piece outer flanges, first stretching belt plates, upper horizontal piece inner flanges, second stretching belt plates, lower horizontal piece inner flanges, counter-pulling angle boxes and counter-pulling angle pieces; the quick-release floor assembly comprises upper panels, aluminum honeycombs, lower panels and bowl-shaped pieces; the footrest assembly comprises foldable cantilever footrests, locking mechanisms, bolts, partition frame T-shaped outer flanges, support lugs, ribs and footrest pedals; the door frame assembly comprises door frames, skins, sealing rubber strip mounting surfaces, small flanges, notches and water guide grooves; the footrest reinforcing assembly comprises first footrest reinforcements, vertical ribs, footrest protrusions and second footrest reinforcements; the mechanical support rod assembly comprises support rods, ball head rods, hinge pieces, hinge supports, ball head rod support seats, spring clamps and thermoplastic pipes; the bolt lock mechanism comprises a three-lock-point bolt lock, front and rear lock points, a bolt support, a lower lock point, a sinking groove, a bolt support upper bolt hole and a lower lock point lock seat; The maintenance access door is arranged on a large opening of a skin through an external hinge, the footrest assembly is arranged outside the skin, the large-opening reinforcing structure assembly is a reinforcing measure for the large opening of the skin, the quick-release floor assembly is arranged inside the skin and is arranged on the large-opening reinforcing structure assembly, the door frame assembly is riveted to the large-opening reinforcing structure assembly of the skin through rivets, the maintenance access door is locked and opened through the bolt lock mechanism and is kept in an open state through the mechanical support rod assembly; when the maintenance access door is closed, the footrest assembly and the maintenance access door are closed; when the maintenance access door is opened, the footrest assembly is opened first, the maintenance access door is opened through the rotation of the bolt lock mechanism and is supported by the mechanical support rod assembly, the right foot is stepped on the footrest assembly first, the left foot is stepped on the quick-release floor assembly and the footrest reinforcing assembly to enter the cabin, and the quick-release floor assembly is used to enter other positions in the cabin; The upper reinforcing horizontal pieces are arranged on the upper portion of the large opening of the skin, the reinforcing horizontal pieces are arranged on the lower portion of the large opening of the skin, the reinforcing front partition frames and the reinforcing rear partition frames are arranged in front and behind the large opening, the second stretching belt plates are arranged on the upper horizontal piece inner flanges at the positions where the partition frames are disconnected to transfer the heading load, the first stretching belt plates are arranged on the outer flanges of the upper reinforcing horizontal pieces and the lower reinforcing horizontal pieces at the disconnected positions to transfer the heading load, the foldable cantilever footrests are installed on the partition frame T-shaped outer flanges through bolts, the structure configuration of the door frame assembly comprises a first door frame form and a second door frame form, and the cross section form of the door frame comprises a first cross section form and a second cross section form. The first door frame form is that the normal of the installation surface of all rubber strips is perpendicular to the skin contour, and the positive pressure of the maintenance access door closing is pressed on the rubber strips; the second door frame form is that the normal of the left and right sides and the upper part of the installation surface of the rubber strips is at a certain angle with the normal of the skin, and the normal of the lower part of the installation surface of the rubber strips is perpendicular to the skin; the strut is arranged inside the maintenance access door, one end of the strut is a ball head rod, the ball head rod is installed on the end of the mechanical strut through a self-locking nut; the other end of the strut is a hinge piece and a hinge support; the front locking point and the rear locking point are arranged on the outer flanges of the front and rear frames respectively.

2. The structure of claim 1, wherein The upper and lower parts of the upper and lower reinforcing horizontal pieces extend by an opening width respectively in front of and behind the skin large opening, and the upper and lower parts of the reinforcing front and rear bulkheads extend by an opening height respectively; when the inner flange of the reinforcing front bulkhead is in an L-shaped section, the inner flange of the lower horizontal piece is designed to transfer the heading load to the pull angle box at the position where the bulkhead is disconnected; when the inner flange of the reinforcing rear bulkhead is in a T-shaped section, the inner flange of the lower horizontal piece is designed to transfer the heading load to the pull angle piece at the position where the bulkhead is disconnected.

3. The structure of claim 1, wherein The moment formed by the vertical load of the stepping point around the shaft of the support lug is balanced by the tension and compression of the bolts arranged along the span direction of the aircraft; the rib is arranged near the bolt hole of the frame web to facilitate the load transfer; the foldable cantilever footrest is buckled with the locking mechanism installed on the skin of the aircraft body in the closed state.

4. The structure of claim 1, wherein The first cross-sectional form is a Z-shaped section with a bent edge, the sealing rubber strip is fixed on the rubber strip installation surface, the rubber strip installation surface is provided with a small flange, and the draft angle of the small flange ranges from 1 to 2 degrees; the second cross-sectional form is a C-shaped variable cross-section, the upper part of the rubber strip installation surface on the left and right and upper part of the door frame is provided with a water guide groove, and the upper part of the rubber strip installation surface on the lower part of the door frame is not provided with a water guide groove.

5. The structure of claim 1, wherein The first cross-sectional form door frame is provided with a notch at the lower part for installing the first stepping reinforcing piece, the upper surface of the first stepping reinforcing piece is flush with the upper surface of the quick-release floor assembly; the first stepping reinforcing piece is provided with a stepping protrusion; The second cross-sectional form door frame is provided with a second stepping reinforcing piece at the lower part, and the second stepping reinforcing piece and the door sill form a closed mouth-shaped structure.

6. The structure of claim 1, wherein The hinge piece and the strut are connected through bolts, groove nuts and split pins, and the connection should ensure that the strut can rotate freely; the two sides of the hinge support are provided with vertical ribs to improve the bending resistance of the hinge, and the hinge bolts are arranged in two columns to form the bending resistance; after the door body is opened, the ball head rod at the end of the strut is inserted into the groove of the ball head rod support seat on the bulkhead to keep the cabin door open; when the cabin door is closed, the strut is fixed in the spring clamp on the door body, the contact position of the strut and the spring clamp is provided with a thermoplastic tube.

7. The structure of claim 1, wherein The bolt support of the front and rear locking points is fixed on the front and rear reinforcing bulkheads and is not connected with the door frame; the lower locking point is arranged on the horizontal surface of the first stepping reinforcing piece, the first stepping reinforcing piece is provided with a sunken groove at the locking point installation position, so that the upper surface of the locking seat is flush with the upper surface of the floor; the bolt hole of each bolt support is provided with a guide slope to ensure smooth insertion of the bolt; the width of the horizontal surface of the stepping reinforcing piece is determined according to the required adjustment width of the lower locking point locking seat.

8. The structure of claim 1, wherein Two external hinges are arranged on the upper part of the upper horizontal piece of the maintenance access door.

9. A method of operating a flat threshold maintenance access structure, characterized by, The method is applied to the flat-sill maintenance access structure according to any one of claims 1-8, and the method comprises the following steps: Step 1: pressing a lock buckle on the foot pedal assembly to open the foot pedal assembly; Step 2: rotating a bolt locking mechanism to open the maintenance access door; Step 3: supporting the maintenance access door by using a mechanical support rod assembly; Step 4: stepping the right foot on the foot pedal assembly when entering the cabin; Step 5: entering the cabin maintenance access by stepping the left foot on the quick-release floor assembly and the foot pedal assembly and holding a boarding handle above the foot pedal assembly; Step 6: entering other positions in the cabin through the quick-release floor assembly; Step 7: resetting the mechanical support rod assembly and the bolt locking mechanism, and closing the maintenance access door; Step 8: resetting the foot pedal assembly.

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