Hydraulic door pivot mechanism

Abstract

The hydraulic door shaft swing mechanism relates to the field of aircraft door shafts, and comprises a brake and a rotary connection structure driven to rotate by the brake; the brake comprises a brake piston, a cylinder baffle, and a hollow brake cylinder; the cylinder baffle is arranged in the brake cylinder; one end of the brake piston is movably arranged in the brake cylinder and connected with the cylinder baffle, serving as a driving fixed vane; the brake piston is connected with the rotary connection structure at one end arranged in the brake cylinder; the rotary connection structure is used for connecting a cabin door; the brake piston is movable and used for driving the rotary connection structure to rotate and drive the cabin door to open and close. The hydraulic door shaft swing mechanism combines a direct-drive hydraulic swing cylinder with a piston cylinder, utilizes the swing cylinder to realize the function of output torque to drive the cabin door to rotate, and utilizes the piston cylinder to realize the function of mechanical braking on the swing mechanism; compared with the traditional mechanical-hydraulic drive, the hydraulic direct-drive door shaft swing mechanism can output rotary motion without a direct rotary converter, has the advantages of high driving efficiency, simple and compact structure, and low manufacturing and maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of aircraft door hinges, specifically to a hydraulic door hinge swing mechanism. Background Technology

[0002] Hydraulic transmission technology converts the pressure energy of a medium into mechanical energy. Compared to mechanical and electrical transmissions, it offers advantages such as high energy density, compact structure, light weight, rapid response, and easy stepless speed regulation. Furthermore, it can output linear or rotary motion without a conversion mechanism, making it widely used in the aerospace industry. Aerospace hydraulic technology utilizes fluid as the transmission medium, controlling the flow of the fluid to complete various aircraft movements, such as the rotation of control surfaces, the opening and closing of cabin doors, and the raising and lowering of landing gear. [2] Hydraulic technology has gradually replaced traditional mechanical and electric drive technologies in certain scenarios and has become an indispensable part of the modern aviation industry.

[0003] The opening and closing of aircraft doors is one of the fundamental operations of an aircraft. Due to space and weight constraints on onboard equipment, aircraft typically employ hydraulic drives with a high power-to-weight ratio for door operation. There are two main types of hydraulic drives for aircraft doors: rocker arm drives and rotary shaft drives, both using hydraulic cylinders as the power source. Rocker arm drives convert the linear motion of the hydraulic cylinder into the rotational motion of the door through a linkage mechanism. They are simple and reliable, but the rocker arm drive unit is relatively large and heavy. Rotary shaft drives output rotational motion through a door hinge swing mechanism. The door hinge is connected to the output shaft of the door hinge swing mechanism to achieve door opening and closing. Rotary shaft drive units require less installation space and have higher reliability.

[0004] Some existing aircraft require cabin doors to open and close during flight. These doors are subjected to significant aerodynamic loads during opening and closing, and the harsh environments in which these aircraft operate necessitate highly adaptable, reliable, and maintainable door drive systems. Due to space constraints, these aircraft employ hydraulic door shaft drives, primarily consisting of a hydraulic control system and a door shaft swing mechanism. Currently, these aircraft utilize a combined hydraulic and mechanical door shaft swing mechanism, converting the linear motion of the piston in the hydraulic cylinder into the rotational motion of the door via a linear-to-rotary converter. While offering good environmental adaptability and reliability, the complex mechanical structure results in low maintainability and high manufacturing costs for the swing mechanism.

[0005] Therefore, it is extremely important to study the door hinge swing mechanism in this aircraft and design a hydraulic direct-drive door hinge swing mechanism that is suitable for extreme working conditions, has high reliability and high maintainability. This is of great significance to the performance and safety of the aircraft and can also provide a reference for the door drive of other aircraft. Summary of the Invention

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A hydraulic door hinge swing mechanism, including a brake and a rotating connection structure driven to rotate by the brake;

[0008] The brake includes a brake piston, a cylinder baffle, and a hollow brake cylinder. The cylinder baffle is disposed inside the brake cylinder. One end of the brake piston is movably inserted into the brake cylinder and connected to the cylinder baffle, serving as a fixed blade for driving. The end of the brake piston located in the brake cylinder is connected to a rotating connection structure, which is used to connect to the hatch.

[0009] The brake piston moves to drive the rotating connection structure to rotate, thereby opening and closing the hatch.

[0010] Preferably, the rotating connection structure includes a rotating shaft that is rotatably inserted into the outer casing;

[0011] The brake cylinder has a channel opening at one end near the rotating shaft, and the channel opening is separated from the hollow cavity of the brake cylinder.

[0012] The end of the rotating shaft near the brake piston passes through the outer casing and is rotatably passed through the channel opening in the brake cylinder via a bearing. It is separated from the channel opening and is movably connected to the brake piston inside the brake cylinder.

[0013] The outer wall of the end of the rotating shaft near the brake piston is provided with a raised strip around its perimeter. The end of the brake piston near the rotating shaft is provided with a connecting hole. The end of the rotating shaft near the brake piston passes through the connecting hole, and the inner wall of the connecting hole is provided with a groove corresponding to the raised strip around its perimeter. The raised strip and the groove are adapted to each other.

[0014] Preferably, a spring is fitted on the side of the brake piston away from the rotating shaft, and the spring is disposed inside the brake cylinder to protect the brake piston;

[0015] The rotating shaft is rotatably fitted with an outer retaining ring on the side near the brake piston. The outer retaining ring is located on the side of the bearing near the brake piston and is located in the channel opening of the brake cylinder. It contacts and limits the movement of the inner wall of the channel opening to seal and isolate the channel opening from the outside.

[0016] Preferably, hatch connectors for connecting hatches are provided on both sides of the outer shell, the hatch connectors are mounted on the rotating shaft, and slots for the rotating shaft to drive the hatch connectors to move are provided on both sides of the outer shell.

[0017] A movable connection structure is provided between the two hatch connectors, and the movable connection structure is located inside the outer shell.

[0018] Preferably, the movable connection structure includes a rotating shaft baffle, which is disposed inside the housing and sleeved on the rotating shaft, serving as a moving blade;

[0019] The two ends of the rotating shaft baffle are respectively provided with guide sleeves, and the two guide sleeves are movably inserted on the rotating shaft. Both guide sleeves are set inside the outer shell and in contact with the interior of the outer shell, which is used to isolate the rotating shaft baffle from the outside.

[0020] Each end of the guide sleeve away from the rotating shaft baffle is provided with a clamping block. The clamping blocks are movably inserted through the rotating shaft and closely fitted to the inner wall of the outer shell to limit the guide sleeve within the outer shell.

[0021] Preferably, the end of the rotating shaft away from the brake piston is rotatably connected to the inner wall of the housing via a bearing;

[0022] A retaining ring is rotatably inserted at the end of the rotating shaft away from the brake piston, and the retaining ring is disposed inside the outer casing and contacts and limits the movement of the inner wall of the outer casing;

[0023] The end of the rotating shaft away from the brake piston is provided with a cap, and the cap is connected to the outer wall of the outer casing near the retaining ring.

[0024] The beneficial effects of this invention are as follows: This hydraulic door hinge swing mechanism analyzes the principle of the traditional mechanical-hydraulic combined swing mechanism and designs an overall scheme for the swing mechanism in combination with design requirements. The overall structural design of this hydraulic door hinge swing mechanism includes a brake and a rotating connection structure driven by the brake. The brake includes a brake piston, a cylinder baffle, and a hollow brake cylinder. The cylinder baffle is disposed inside the brake cylinder. One end of the brake piston is movably inserted into the brake cylinder and connected to the cylinder baffle, serving as a driving fixed blade. The end of the brake piston located in the brake cylinder is connected to the rotating connection structure, which is used to connect the hatch. The movement of the brake piston drives the rotating connection structure to rotate, thereby opening and closing the hatch. From the overall design structure of the hydraulic door hinge swing mechanism, the hydraulic door hinge swing mechanism combines a direct-drive hydraulic swing cylinder with a piston cylinder. The swing cylinder is used to output torque to drive the door to rotate, and the piston cylinder is used to perform mechanical braking on the swing mechanism. Compared with the traditional hydraulic drive, the hydraulic direct-drive door hinge swing mechanism can output rotational motion without a direct-rotation converter. It has the advantages of high drive efficiency, simple and compact structure, and low manufacturing and maintenance costs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the hydraulic door hinge swing mechanism of the present invention;

[0026] Figure 2 For the present invention Figure 1 Schematic diagram of the AA section;

[0027] Figure 3 This is an exploded schematic diagram of the structural components of the hydraulic door hinge swing mechanism of the present invention;

[0028] Figure 4 This is a schematic diagram of the braking principle of the hydraulic door hinge swing mechanism of the present invention;

[0029] Figure 5 This is a schematic diagram of the force analysis of the brake cylinder of the hydraulic door hinge swing mechanism of the present invention;

[0030] Figure 6 This is a schematic diagram of the force analysis of the cylinder baffle of the hydraulic door hinge swing mechanism of the present invention;

[0031] Figure 7 This is a schematic diagram of the force analysis of the rotating shaft of the hydraulic door hinge swing mechanism of the present invention;

[0032] Figure 8 This is a schematic diagram of the force analysis of the rotating shaft baffle of the hydraulic door hinge swing mechanism of the present invention;

[0033] In the diagram, 1-outer shell, 2-door connector, 11-brake piston, 12-brake cylinder, 13-shaft, 14-spring, 15-shaft baffle, 16-guide sleeve, 17-clamping block, 18-retaining ring, 19-cap, 141-outer retaining ring. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0036] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] like Figures 1 to 8 As shown, the hydraulic door hinge swing mechanism includes a brake and a rotating connection structure driven by the brake. The brake drives the rotating connection structure connected to the brake to rotate, thereby driving the hatch mounted on the rotating connection structure to rotate, achieving the purpose of opening and closing. In existing technology, the spiral hydraulic swing cylinder is a linear-rotational switching mechanism, which can be divided into single-spiral swing cylinders and double-spiral swing cylinders, with the double-spiral structure being the most widely used. The double-spiral hydraulic swing cylinder mainly consists of a cylinder body, a nut, a piston, and an output screw. The nut is fixed on the cylinder body, and the piston forms a two-stage spiral pair with the nut and the output screw. When hydraulic oil pushes the piston to move linearly, the piston simultaneously rotates under the first-stage spiral effect, and the output screw outputs rotary motion under the second-stage spiral effect. The longer the piston stroke, the larger the angle of the output rotary motion. The spiral hydraulic swing cylinder is small in size, has a large output torque, low leakage, and high volumetric efficiency, but its structure is relatively complex. Due to the presence of meshing spiral pairs, it requires high machining precision, resulting in high manufacturing costs. Therefore, to overcome this problem, design improvements were made, leading to this hydraulic door hinge swing mechanism.

[0038] Furthermore, in this embodiment, the brake of the hydraulic door hinge swing mechanism includes a brake piston 11, a cylinder baffle, and a hollow brake cylinder 12. The cylinder baffle is disposed inside the brake cylinder 12. One end of the brake piston 11 is movably inserted into the brake cylinder 12 and connected to the cylinder baffle, serving as a driving fixed blade. The end of the brake piston 11 placed in the brake cylinder 12 is connected to a rotating connection structure, which is used to connect the hatch. The rotating connection structure includes a rotating shaft 13, which is rotatably inserted into the outer casing 1. The movement of the brake piston 11 drives the rotating shaft 13 of the rotating connection structure to rotate, thereby driving the hatch, which is installed and connected by two hatch connectors 2, to open and close.

[0039] Based on practical design requirements, the aircraft door hinge swing mechanism is generally elongated due to installation space constraints, and its internal parts are relatively small. In this case, the simpler the structure of the parts, the higher their reliability. Since the vane-type swing cylinder directly drives the load through the pressure difference on both sides of the vane, it does not require a direct-drive switching structure and is a direct-drive hydraulic actuator with a relatively simple mechanical structure. Furthermore, due to advancements in hydraulic cylinder sealing technology, the working pressure of the vane-type swing cylinder has been increased. Therefore, this hydraulic door hinge swing mechanism is designed based on a single-vane hydraulic swing cylinder.

[0040] This hydraulic door hinge swing mechanism combines a single-blade hydraulic swing cylinder with a piston hydraulic cylinder, achieving both output torque and braking functions. The principle is as follows:

[0041] (1) Output torque function

[0042] The output torque function of this hydraulic door hinge swing mechanism is achieved by a single-vane hydraulic swing cylinder. For example... Figures 1 to 3 As shown, the outer shell 1 of the hydraulic door hinge swing mechanism has door connectors 2 on both sides for connecting the hatches. The door connectors 2 are mounted on the rotating shaft 13. The outer shell 1 has slots on both sides for the rotating shaft 13 to drive the door connectors 2 to move. A movable connection structure is provided between the two door connectors 2, and the movable connection structure is located inside the outer shell 1. The movable connection structure includes a rotating shaft baffle 15, which is located inside the outer shell 1 and sleeved on the rotating shaft 13, serving as a moving blade. Guide sleeves 16 are provided at both ends of the rotating shaft baffle 15, and the two guide sleeves 16 are movably inserted through the rotating shaft 13. Both guide sleeves 16 are located inside the outer shell 1 and are connected to the outer shell. The internal contact within the housing 1 is used to isolate the rotating shaft baffle 15 from the outside. A clamping block 17 is provided at the end of the guide sleeve 16 away from the rotating shaft baffle 15. Each clamping block 17 is movably inserted through the rotating shaft 13 and tightly fitted against the inner wall of the housing 1, limiting the guide sleeve 16 within the housing 1. Simultaneously, the end of the rotating shaft 13 away from the brake piston 11 is rotatably connected to the inner wall of the housing 1 via a bearing. A retaining ring 18 is rotatably inserted at the end of the rotating shaft 13 away from the brake piston 11, and the retaining ring 18 is positioned inside the housing 1 and contacts the inner wall of the housing 1 for limitation. A cap 19 is provided at the end of the rotating shaft 13 away from the brake piston 11, and the cap 19 is connected to the outer wall of the housing 1 near the retaining ring 18. Furthermore, a channel opening is opened at the end of the brake cylinder 12 near the rotating shaft 13. This channel opening is separated from the hollow cavity of the brake cylinder 12, forming two independent "cavity sealing structures" that do not affect each other, respectively. The rotating shaft 13 is installed and fixed in the position designed for the aircraft door using existing technology, and then the rotating shaft 13 is controlled by a brake to drive the door to close.

[0043] The movable connection structure between the two hatch connectors 2 consists of a rotating shaft baffle 15, a guide sleeve 16, a clamping block 17, etc. At the slots opened between the rotating shaft 13 and the outer shell 1, the end face sealing structures of the guide sleeve 16 and the clamping block 17 respectively form a structure similar to a "single-blade swing cylinder". In order to balance the force, the movable connection structure composed of the hatch connector 2, bearing, guide sleeve and clamping block 17 forms a "swing oil chamber" which is symmetrically distributed on both sides of the "swing oil chamber". The brake used to drive the rotating shaft 13 to rotate consists of a brake piston 11, a cylinder baffle, a brake cylinder 12, a spring 14, etc. Its specific implementation can be as follows: a channel opening is opened at one end of the brake cylinder 12 near the rotating shaft 13, the channel opening being separated from the hollow cavity of the brake cylinder 12; the end of the rotating shaft 13 near the brake piston 11 passes through the outer shell 1 and is rotatably connected to the brake piston 11, which is separated from the channel opening and movably disposed within the brake cylinder 12; a raised rib is provided around the outer wall of the end of the rotating shaft 13 near the brake piston 11, and a connecting hole is opened at the end of the brake piston 11 near the rotating shaft 13, the end of the rotating shaft 13 near the brake piston 11 passing through the connecting hole, and grooves corresponding to the raised ribs are formed around the inner wall of the connecting hole, the raised ribs and grooves fitting together; this design can form a structure similar to a "spline" for connection and transmission. A spring 14 is fitted on the side of the brake piston 11 away from the rotating shaft 13. The spring 14 is located inside the brake cylinder 12 and is used to protect the brake piston 11. An outer retaining ring 141 is rotatably fitted on the side of the rotating shaft 13 near the brake piston 11. The outer retaining ring 141 is located on the side of the bearing near the brake piston 11 and is located in the channel opening of the brake cylinder 12. It contacts and limits the movement of the inner wall of the channel opening and is used to seal and isolate the channel opening from the outside.

[0044] In this embodiment, the cylinder baffle of the hydraulic door hinge swing mechanism corresponds to the fixed blade of the "blade swing cylinder," and the rotating shaft baffle corresponds to the moving blade of the "blade swing cylinder." The rotating shaft baffle 15 is mounted on the rotating shaft 13, and the cylinder baffle is mounted on the inner wall of the brake cylinder 12. Through an end-face sealing device (structure), the internal space of the brake cylinder 12 is divided into two non-communicating chambers. The brake cylinder 12 has two oil ports, connecting the two chambers to oil circuits respectively. When one oil port is connected to the pressure oil circuit and the other chamber is connected to the return oil circuit, a pressure difference is formed on both sides of the rotating shaft baffle 15, driving the brake piston 11 to rotate the rotating shaft 13 towards the low-pressure side. The hatch is connected to the rotating shaft 13 through the hatch connector 2, and is thus driven to rotate by the hydraulic door hinge swing mechanism. When the oil supply direction is reversed, the rotating shaft baffle 15 moves in the opposite direction, similarly causing the hatch to rotate in the opposite direction.

[0045] (2) Braking function

[0046] The brake (piston-type hydraulic cylinder) of the hydraulic door hinge swing mechanism is implemented. The brake consists of a brake piston 11, cylinder baffle, brake cylinder 12, spring 14, and other parts. The braking function is achieved by the combined action of the brake, hydraulic lock, and shuttle valve. Figure 4 The diagram shown illustrates the braking principle of the brake.

[0047] In the diagram, P represents the pressure oil circuit, and T represents the return oil circuit. Both oil circuits of the hydraulic lock and the solenoid valve are connected to the two inlets of the shuttle valve, and the outlet of the shuttle valve is connected to the brake oil chamber. The shuttle valve functions similarly to an OR gate; when one of the two inlets is connected to pressure oil, the outlet outputs pressure oil. The braking and releasing process is as follows (the "swinging oil chamber" described above):

[0048] When the right chamber of the solenoid valve is de-energized and the left chamber is not energized at the same time, the hydraulic valve returns to the neutral position. The pressurized oil returns directly to the oil tank through the H-function in the neutral position. The hydraulic oil in front of the hydraulic lock in the left chamber also enters the hydraulic oil tank through the valve, and the pressure in front of the hydraulic lock drops to the return oil pressure. Under the pressure of the left chamber of the swing cylinder, the hydraulic lock closes quickly, and the control pressure of the right chamber of the hydraulic lock also drops to the return oil pressure. The hydraulic lock also closes quickly under the pressure. At this time, both chambers are locked by the hydraulic lock. The entire hydraulic lock front oil is connected to the return oil line. The hydraulic oil in the brake also enters the return oil line through the shuttle valve. Under the action of spring 14, the rotating shaft 13 brakes quickly enters the braking position, generating mechanical braking on the rotating shaft 13 and serving a protective purpose.

[0049] When the right-position solenoid valve is energized, pressurized oil enters the left-side oil chamber of the swing cylinder through the left chamber of the hydraulic lock. At the same time, the control port of the right chamber of the hydraulic lock receives pressurized oil, opening the right chamber of the hydraulic lock. The right-side oil chamber of the swing cylinder is connected to the return oil circuit through the right chamber of the hydraulic lock. Pressurized oil simultaneously enters the shuttle valve and then the brake oil chamber, pushing the brake to overcome the force of spring 14 and leave the brake position. The brake is released, and the hydraulic door shaft swing mechanism performs the door opening and closing action. The principle is the same when the left-side solenoid valve is energized.

[0050] Furthermore, in order to meet the requirements of aircraft, the hydraulic door hinge swing mechanism has a small overall size and many of its internal parts are non-standard, requiring individual design. Moreover, the pressure of the aviation hydraulic system is very high, and the internal parts of the hydraulic door hinge swing mechanism will be subjected to a large load, which may lead to failure of the swing mechanism due to insufficient strength. Therefore, the key components in the hydraulic door hinge swing mechanism scheme are structurally designed, and the finite element method is used for strength analysis. In addition, structural analysis of the components must be carried out during the design process to improve unreasonable designs.

[0051] The brake cylinder 12 is one of the main components of the hydraulic door hinge swing mechanism. It must possess sufficient strength and rigidity to ensure reliability while meeting output capacity, movement speed, and effective stroke requirements. Due to installation space limitations, the maximum outer diameter of the designed hydraulic direct-drive door hinge swing mechanism must not exceed 70mm. Other components in the swing mechanism are then designed based on the structure of the brake cylinder 12. The brake cylinder 12 has three mounting seats for fixing it to the aircraft. A U-shaped opening is cut on each of the left and right sides, through which the door connector 2 connects to the rotating shaft 13. The cylinder wall forming the oil chamber of the brake cylinder 12 has countersunk holes for installing cylinder baffles, and two oppositely distributed oil ports on the cylinder wall, with threads at both ends for installing clamping end caps. The cylinder baffles cooperate with the rotating shaft 13 and the brake cylinder 12 to separate the high and low pressure oil chambers. Due to the stroke angle and installation limitations of the hydraulic door hinge swing mechanism, the cylinder baffles are designed as annular, with their dimensions based on the dimensions of the brake cylinder 12 and the rotating shaft 13. Because the cylinder baffle and the rotating shaft 13 move relative to each other, a seal must be installed on the cylinder baffle to ensure the sealing between the two chambers of the oil cavity. The installation of the seal requires a groove to be made in the contact area between the baffle and the rotating shaft 13. The depth of the groove should be less than the height of the seal to ensure a certain pre-compression force after installation. Due to the limited overall size of the hydraulic door shaft swing mechanism, the blade thickness is very small, and the design of the sealing groove must consider its impact on blade strength. The groove depth is designed according to actual requirements to meet the requirements. To facilitate the installation and replacement of the seal on the cylinder baffle, the connection between the brake cylinder 12 and the cylinder baffle should be detachable. Furthermore, the internal space of the brake cylinder 12 in this hydraulic door shaft swing mechanism is narrow, making it inconvenient to arrange nuts; therefore, threaded bolts are selected for connection. Since the cylinder baffle is small, large countersunk holes or threaded holes are not suitable; M3 bolts are selected. Because the reciprocating motion of this hydraulic door hinge swing mechanism is symmetrical, the forces on both sides of the cylinder baffle are similar. Therefore, the bolt groups of the brake cylinder 12 and the cylinder baffle should be symmetrically distributed on both sides of the cylinder baffle. Due to the deformation of the parts under stress, when one side of the baffle is subjected to high-pressure oil, the pressure is basically borne by the bolts closest to the high-pressure side. Therefore, the bolt groups should be arranged in a row on each side along the baffle axis, with each bolt in the row being equidistant from the side to ensure uniform force distribution. The bolts should be as close as possible to the oil-receiving side. If the bolts are too far from the side, hydraulic oil will be squeezed into the gap between the brake cylinder 12 and the cylinder baffle, which may cause the baffle to warp and deform, affecting the smoothness of the hydraulic door hinge swing mechanism. The bolts should not be too close to the edge, otherwise it will affect the strength of the baffle and cause the weak points on the side of the baffle to be sheared off. Therefore, the distance from the bolts to the edge must be comprehensively considered. The spacing between the bolts should be greater than three times the hole diameter.

[0052] Furthermore, during the design process, a force analysis is performed on the brake cylinder 12 of the door hinge swing mechanism. The brake cylinder 12 is fixed to the aircraft (aircraft) by bolts on the mounting base and is stationary relative to the aircraft (aircraft). The aircraft is used as the reference frame during the force analysis. Figure 5 The diagram shown illustrates the force analysis of the brake cylinder.

[0053] In the diagram, F H1 F H2 F represents the pressure of high-pressure oil and low-pressure oil on the inner wall of brake cylinder 12, respectively. B1 F B2 F represents the force exerted by the bolts on both sides on the hole. N F is the resultant force of the supporting forces of the brake cylinder 12 on the parts. f The frictional force between the shaft baffle 15 and the brake cylinder 12 is considered. Without considering external forces acting on the brake cylinder 12, the influence of the weight of internal components on the strength of the brake cylinder 12 is very small compared to the hydraulic pressure, so it is ignored in the strength analysis; only the hydraulic pressure is considered. The hydraulic pressure in the brake cylinder 12 acts only on the surface of the oil chamber, which is composed of the shaft surface, the inner wall of the brake cylinder 12, the side of the shaft baffle 16, and the side of the cylinder baffle. The hydraulic pressure acting on one side of the shaft baffle 15 is converted into torque and output through the shaft baffle 15 and the shaft 13. The force acting on one side of the cylinder baffle is transmitted to the bore wall of the brake cylinder 12 via bolts, generating F. B1 F B2 Both of them are subjected to the same force as the bolt; the forces acting on the inner wall of the brake cylinder 12 and the surface of the rotating shaft are both manifested as pressure on the cylinder wall. Since the sum of the volumes of the high-pressure chamber and the low-pressure chamber is the same, the larger the volume of the high-pressure chamber, the greater the force on the brake cylinder 12.

[0054] During one operation, the swing mechanism rotates the shaft baffle 15 from the starting position to the end of the stroke by 105°. During this process, the volume of the high pressure chamber of the brake cylinder 12 gradually increases and the volume of the low pressure chamber gradually decreases. Therefore, when the door shaft swing mechanism is about to move to the end in one operation, and the solenoid valve has not yet switched to the braking state, the brake cylinder 12 is subjected to the greatest force. At this time, the arc angle of the high pressure oil is about 105°.

[0055] When the cylinder baffle of the hydraulic door hinge swing mechanism is stationary relative to the brake cylinder 12, the brake cylinder 12 is selected as the reference frame when the cylinder baffle is subjected to force. Figure 6 The diagram shows the force analysis of the cylinder baffle.

[0056] In the diagram, P0 represents the high-pressure chamber hydraulic pressure, P1 represents the low-pressure chamber hydraulic pressure, F0 and F1 represent the reaction forces of the bolts on the hole wall, and T represents the hydraulic pressure. fThe frictional torque is T between the rotating shaft 13 and the cylinder baffle. When the cylinder baffle is subjected to hydraulic pressure, it tends to rotate in the opposite direction, eventually coming to rest under the action of the bolts. The pressure difference between the two sides of the cylinder baffle generates a torque, which acts evenly on each bolt on both sides, and the cylinder baffle also experiences the same force. f The direction is opposite to the direction of the hydraulic torque on the baffle. Assuming that the shaft 13 is in overall force balance and the normal pressure distribution between the shaft 13 and the baffle is uniform, T is calculated according to the following formula. f Value:

[0057]

[0058] In the formula: Assuming the friction coefficient is given, and that the lubrication between the shaft 13 and the baffle is a full-film fluid lubrication system, Take 0.01; The arc angle of the high-pressure oil acting on the surface of the rotating shaft 13; denoted as _r_, where _r_ is the radius of the rotating shaft 13; and _b_ is the length of the baffle.

[0059] The rotating shaft 13 in the hydraulic direct-drive door hinge swing mechanism is the output structural component of the swing mechanism, responsible for driving the door to rotate and mainly bearing torque loads. The diameter of the rotating shaft 13 in the swing cylinder oil chamber is 30mm. According to design requirements, the pneumatic load on the door during opening and closing is 105 N·m, and the hydraulic holding torque in the closed state is not less than 300 N·m. To ensure reliability, 300 N·m is selected as the load torque of the shaft during design. The diameter of the rotating shaft 13 can be initially calculated using the following formula:

[0060]

[0061] In the formula: The torsional shear stress of the shaft is T; the torque transmitted by the shaft is T. The section modulus is the torsional section modulus. ; To allow for torsional shear stress. In this embodiment, 7075-T6 is selected as the material of the shaft, and the calculated shaft diameter d≥20.2mm. Considering the presence of a keyway on the shaft 13, the minimum diameter d=22mm is determined.

[0062] A shaft baffle 15, a guide sleeve 16, a bearing, and a hatch connector 2 are mounted on the shaft 13. Based on the installation relationship, the shaft 13 is designed as a stepped shaft. The shaft baffle 15 is connected to the shaft 13 by bolts. The guide sleeve is mounted on both sides of the baffle by a clamping device. The hatch connector 2 is mounted on the shaft 13 by keys on both sides. The number of keys is calculated according to the following formula:

[0063]

[0064] In the formula: T is the transmitted torque; m is the number of keys; D is the diameter of the shaft 13; k is the contact height between the key and the hub; l is the working length of the key; The minimum allowable stress among the key, shaft 13, and hatch connector 2 is calculated to be m=3.3. To balance the forces on the shaft and ensure reliability, four keyways are designed on both sides of the shaft, evenly distributed in the circumferential direction.

[0065] The hydraulic door hinge swing mechanism achieves braking through a rectangular spline, and one end of the rotating shaft 13 is designed with an external spline. According to the requirements, the swing mechanism needs to be braked at both extreme positions of the stroke, with a stroke angle of 105°. Therefore, the angle between adjacent splines must be the common divisor of 360° and 105°, which is 15°. Thus, the spline has 24 key teeth.

[0066] The rotating shaft baffle 15 in the hydraulic door hinge swing mechanism has a dimensional relationship with the cylinder baffle, rotating shaft 13 and brake cylinder 12. The rotating shaft baffle 15 is annular with an arc angle of 85°. The radius of the mating surface with the rotating shaft 13 is 15mm, the radius of the mating surface with the brake cylinder 12 is 20mm, and the length is 200mm.

[0067] When the rotating shaft baffle 15 is at the start and end of its stroke, the sum of its arc angles is 255°. Since the two oil ports on the brake cylinder 12 are symmetrically distributed at 180°, one oil port will inevitably be blocked by the rotating shaft baffle 15. Therefore, some material must be removed from both sides of the annular rotating shaft baffle 15 to prevent hydraulic oil from entering the chambers and thus preventing the door hinge swing mechanism from restarting. To ensure the sealing between the two oil chambers of the swing mechanism, an annular groove is designed on the rotating shaft baffle 15 for installing a seal. The depth of the annular groove should be less than the height of the seal to ensure that the seal has a certain pre-compression force after installation.

[0068] A sealing ring needs to be installed on the pivot baffle 15, therefore the connection between the pivot baffle 15 and the pivot 13 should be detachable. The pivot baffle 15 has a relatively small thickness; since the depth of the bolt countersunk hole is large, it would affect the strength of the baffle. Therefore, a screw with a smaller countersunk hole depth is chosen for connection. The stress situation of the connection between the pivot 13 and the pivot baffle 15 is similar to that of the connection between the brake cylinder 12 and the cylinder baffle. Therefore, it can be concluded that the connection between the pivot 13 and the pivot baffle 15 uses M3 screws, made of TB3 titanium alloy; a total of 20 screws are arranged in two rows, evenly distributed on both sides of the pivot baffle 15, with each screw 10mm from the nearest baffle side and a screw spacing of 20mm.

[0069] Furthermore, the rotating shaft 13 in the hydraulic door hinge swing mechanism is responsible for transmitting the torque generated by the brake (hydraulic cylinder) to the hatch connector 2. According to the principle of force action, the rotating shaft 13 bears a torque load of the same magnitude. A portion of the rotating shaft 13 is immersed in hydraulic oil, and this section of the surface is subjected to oil pressure. When the hydraulic door hinge swing mechanism is at the end of one stroke, the rotating shaft 13 experiences the greatest force. To simplify the force model of the rotating shaft 13, it is assumed that the rotating shaft 13 is always in a state of force equilibrium in the circumferential direction during the operation of the hydraulic door hinge swing mechanism, and its force analysis is performed as follows: Figure 7 The diagram shows the force analysis of the rotating shaft.

[0070] In the diagram, T represents the torque transmitted by the rotating shaft baffle 15. f The frictional torque acting on shaft 13 mainly originates from the friction between shaft 13 and the cylinder baffle. The calculated frictional torque is 15.4 N·m. T1 and T2 are the reaction torques of the hatch on the shaft, acting on the side of the keyway on the shaft. F represents the hydraulic pressure exerted on the rotating shaft 13 portion, which is immersed in hydraulic oil.

[0071] like Figure 8 The diagram shown illustrates the force analysis of the rotating shaft baffle.

[0072] In the diagram, P0 represents the high-pressure oil pressure (28 MPa), P1 represents the return oil pressure (0.3 MPa), and F0 and F1 represent the reaction forces of the bolts on the hole wall. Due to the different hydraulic oil pressures on both sides of the baffle, the pressure difference generates a torque on the rotating shaft baffle 15, driving the rotating shaft 13 and the load on the shaft to rotate. The torque is 412 N·m. Assuming that the door hinge swing mechanism outputs uniform circular motion during operation, and the rotating shaft baffle 15 is in circumferential equilibrium with the rotating shaft 13, then the torque generated by the bolt force is the same as the torque generated by the hydraulic pressure.

[0073] A three-dimensional model of the rotating shaft was established, and a finite element static analysis was performed on it. When setting boundary conditions for the shaft, remote constraints were added to the two shaft segments where the bearings are installed, restricting five degrees of freedom except for axial rotation, to simulate the supporting effect of the bearings on the shaft. The shaft segment 13 located in the cylinder oil chamber was segmented, and a pressure of 28 MPa was applied to the surfaces forming the oil chamber to simulate hydraulic pressure. A torque load of 412 N·m was applied to the bore wall of the rotating shaft model to simulate the transmitted torque. Finally, fixed supports were added to the sides of each keyway at both ends of the shaft to maintain the overall force balance of the rotating shaft 13. The final calculations showed that the maximum stress and maximum deformation both met the requirements. A finite element static analysis was performed on the rotating shaft baffle 15 using the same procedure; the final parameters also met the requirements.

[0074] Furthermore, to address the issues of low drive efficiency, complex structure, and high manufacturing and maintenance costs associated with traditional aircraft-type hydraulic door hinge swing mechanisms, the hydraulic door hinge swing mechanism has been redesigned and improved.

[0075] (1) In view of the design requirements of hydraulic door shaft swing mechanism for traditional aircraft, the principle and advantages and disadvantages of traditional mechanical-hydraulic combined swing mechanism were studied. Furthermore, by analyzing and comparing the blade type hydraulic swing cylinder and the spiral type hydraulic swing cylinder, a suitable swing cylinder was selected to design the overall scheme of aviation hydraulic door shaft swing mechanism, and the design structure improvement of the hydraulic door shaft swing mechanism was established.

[0076] (2) Based on the design structure improvement of the hydraulic door hinge swing mechanism, the structural design of each component in the swing mechanism is carried out, a three-dimensional model of the component is established, the stress analysis and strength verification of the key components in the swing mechanism are carried out, and the weight reduction design of the swing mechanism is carried out on the basis of ensuring the strength of the components.

[0077] (3) To assess the strength of the hydraulic door hinge swing mechanism in the aircraft (aircraft) vibration environment, modal analysis was performed on the key components of the designed swing mechanism to obtain their natural frequencies. Random vibration analysis was then performed on the components based on their natural frequencies and the power spectrum of the vibration environment to verify the vibration strength of the hydraulic door hinge swing mechanism in the working environment.

[0078] (4) To address the issue that the clearance of the friction pair of the hydraulic door shaft swing mechanism changes under extreme working conditions, thermal deformation simulation of the friction pair of the swing mechanism is performed to analyze the influence of temperature deformation of the swing mechanism components on the clearance of the friction pair in extreme environments.

[0079] (5) In view of the sealing requirements of the hydraulic door hinge swing mechanism, the principle and advantages and disadvantages of different sealing forms are analyzed, a suitable sealing method is selected to design the sealing structure of each sealing surface in the swing mechanism, and the sealing performance of the hydraulic door hinge swing mechanism is analyzed.

[0080] Ultimately, this hydraulic door hinge swing mechanism combines a direct-drive hydraulic swing cylinder with a piston cylinder. The swing cylinder outputs torque to drive the door to rotate, while the piston cylinder provides mechanical braking for the swing mechanism. Compared to traditional hydraulic drives, the hydraulic direct-drive door hinge swing mechanism can output rotational motion without a direct-to-rotary converter, offering advantages such as high drive efficiency, simple and compact structure, and low manufacturing and maintenance costs.

[0081] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the embodiments described above. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. At the same time, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A hydraulic door hinge swing mechanism, characterized in that, Includes a brake and a rotating connection structure that drives rotation via the brake; The brake includes a brake piston (11), a cylinder baffle, and a hollow brake cylinder (12). The cylinder baffle is disposed inside the brake cylinder (12). One end of the brake piston (11) is movably inserted into the brake cylinder (12) and connected to the cylinder baffle, serving as a fixed blade for driving. The end of the brake piston (11) placed in the brake cylinder (12) is connected to a rotating connection structure, which is used to connect the hatch. The brake piston (11) moves to drive the rotating connection structure to rotate and drive the hatch to open and close; The rotating connection structure includes a rotating shaft (13), which is rotatably inserted into the outer shell (1); The brake cylinder (12) has a channel opening at one end near the rotating shaft (13), and the channel opening is separated from the hollow cavity of the brake cylinder (12); The end of the rotating shaft (13) near the brake piston (11) passes through the outer shell (1) and is rotatably passed through the channel opening of the brake cylinder (12) via a bearing, and is connected to the brake piston (11) which is separated from the channel opening and is movably disposed in the brake cylinder (12). The rotating shaft (13) has a raised strip around the outer wall of one end near the brake piston (11). The brake piston (11) has a connecting hole at one end near the rotating shaft (13). The rotating shaft (13) passes through the connecting hole at one end near the brake piston (11). The inner wall of the connecting hole has a groove corresponding to the raised strip around the perimeter. The raised strip and the groove are adapted to each other. A spring (14) is fitted on the side of the brake piston (11) away from the rotating shaft (13). The spring (14) is installed inside the brake cylinder (12) to protect the brake piston (11). The rotating shaft (13) is rotatably fitted with an outer retaining ring (141) on one side near the brake piston (11). The outer retaining ring (141) is located on the side of the bearing near the brake piston (11) and is located in the channel opening of the brake cylinder (12), contacting and limiting the inner wall of the channel opening to seal and isolate the channel opening from the outside. The end of the rotating shaft (13) away from the brake piston (11) is rotatably connected to the inner wall of the outer casing (1) via a bearing; A retaining ring (18) is rotatably provided at one end of the rotating shaft (13) away from the brake piston (11). The retaining ring (18) is disposed inside the outer shell (1) and contacts and limits the inner wall of the outer shell (1). A cap (19) is provided at the end of the rotating shaft (13) away from the brake piston (11), and the cap (19) is connected to the outer wall of the outer shell (1) near the retaining ring (18).

2. The hydraulic door hinge swing mechanism according to claim 1, characterized in that, The outer shell (1) is provided with hatch connectors (2) on both sides for connecting the hatch. The hatch connectors (2) are installed on the rotating shaft (13). The outer shell (1) is provided with slots on both sides for the rotating shaft (13) to drive the hatch connectors (2) to move. A movable connection structure is provided between the two hatch connectors (2), and the movable connection structure is located inside the outer shell (1).

3. The hydraulic door hinge swing mechanism according to claim 2, characterized in that, The movable connection structure includes a rotating shaft baffle (15), which is disposed inside the outer shell (1) and sleeved on the rotating shaft (13) as a moving blade; The two ends of the rotating shaft baffle (15) are respectively provided with guide sleeves (16), and the two guide sleeves (16) are respectively movably inserted on the rotating shaft (13). The two guide sleeves (16) are both set inside the outer shell (1) and in contact with the interior of the outer shell (1), which is used to isolate the rotating shaft baffle (15) from the outside. The guide sleeve (16) is provided with a clamping block (17) at the end away from the rotating shaft baffle (15). The clamping block (17) can be movably inserted on the rotating shaft (13) and closely fitted to the inner wall of the outer shell (1) to limit the guide sleeve (16) inside the outer shell (1).

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