A landing gear and status management system for triggering a wheel load signal

Abstract

The application provides a landing gear and state management system for triggering wheel load signals, and belongs to the technical field of landing gear design. The landing gear comprises a front landing gear and two main landing gears. The front landing gear comprises a first outer cylinder, an inner cylinder, a first piston rod, and a first triggering mechanism. The first outer cylinder is fixedly connected with the fuselage, the inner cylinder moves in the vertical direction inside the first outer cylinder, the first piston rod transmits the ground load to the inner cylinder and the first outer cylinder, and the first triggering mechanism is installed on the upper part of the front landing gear. Each main landing gear comprises a second outer cylinder, a second piston rod, and a second triggering mechanism. The second outer cylinder is fixedly connected with the fuselage, the second piston rod moves in the vertical direction inside the second outer cylinder, an oil cavity is formed between the second outer cylinder and the second piston rod, and the second triggering mechanism is installed on the upper part of the main landing gear. In the application, the wheel load signal micro switch has higher precision, higher sensitivity, higher reliability, and stronger designability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of landing gear design, and particularly relates to a landing gear triggering a wheel load signal and a state management system. BACKGROUND

[0002] The airplane / helicopter grounding signal is an important signal in the flight process. Generally, the landing gear system is the only part of the whole machine in contact with the ground, and the wheel load signal is an important signal source in the flight process of the airplane / helicopter. The flight control system, avionics system and other subsystems judge the position of the airplane at the moment by collecting the wheel load signal. How to accurately collect the wheel load signal and how to design the triggering mode of the wheel load signal micro switch are important contents in the design of the landing gear.

[0003] The wheel load signal micro switch of the traditional landing gear is generally installed on the anti-twist arm, as shown in FIG. 1. Figure 1 When the airplane lands, the buffer overcomes the oil damping force and the air spring force to compress, the anti-twist arm rotates relatively, the wheel load signal micro switch contacts or separates from the trigger piece, and the circuit is turned on or off to judge whether the landing gear is grounded. The disadvantage of this method is that the landing gear needs to overcome a larger force, the anti-twist arm needs to have a larger angle change, and the corresponding buffer needs to have a larger compression amount to trigger the wheel load signal micro switch, so the sensitivity is poor. In addition, the wheel load signal micro switch is often installed outside the fuselage, which is easily affected by the external environment. During the working process of the landing gear, the sensor and the anti-twist arm rotate relatively, which causes wear and other reliability problems after long-term use.

[0004] The existing technology sets the wheel load signal on the buffer strut, as shown in FIG. 2. Figure 2 It designs a complex mechanism to realize this function. First, the vertical displacement is converted to the horizontal direction through the trigger mechanism, and then the horizontal displacement is converted to the vertical direction through the rocker arm. The disadvantage is that the structure is complex and not easy to implement, and it is not suitable for installing multiple micro switches. SUMMARY

[0005] To solve the problem that the structure of setting the wheel load signal on the buffer strut in the prior art is complex and not easy to implement, and it is not suitable for installing multiple micro switches, the present application provides a landing gear triggering a wheel load signal and a state management system. Compared with the existing triggering mechanism, the precision, sensitivity, reliability and designability of the wheel load signal micro switch are higher by using the mechanism. The technical solution is as follows:

[0006] In the first aspect, a landing gear triggering a wheel load signal is provided, and the landing gear includes a front landing gear and two main landing gears,

[0007] The front landing gear comprises a first outer cylinder 61, an inner cylinder 8, a first piston rod 171, and a first trigger mechanism, wherein the first outer cylinder 61 is fixedly connected with the fuselage, the inner cylinder 8 moves in the vertical direction inside the first outer cylinder 61, the first piston rod 171 transmits the ground load to the inner cylinder 8 and the first outer cylinder 61, and the first trigger mechanism is installed on the upper part of the front landing gear.

[0008] Each main landing gear comprises a second outer cylinder 62, a second piston rod 172, and a second trigger mechanism, wherein the second outer cylinder 62 is fixedly connected with the fuselage, the second piston rod 172 moves in the vertical direction inside the second outer cylinder 62, an oil cavity is formed between the second outer cylinder 62 and the second piston rod 172, and the second trigger mechanism is installed on the upper part of the main landing gear.

[0009] Optionally, the first trigger mechanism comprises a first upper end cover 2, a first spring 3, a cover 4, a first positioning pin 5, a self-lubricating support sleeve 7, a fixed piston 9, a plug cap 10, a plunger 11, a locking nut 12, a sealing ring 13, a sealing ring 14, a self-lubricating support sleeve 15, a first micro switch 1, and a blocking ring 25.

[0010] The first upper end cover 2 is fixedly connected with the first outer cylinder 61 through the first positioning pin 5, the first outer cylinder 61 is fixedly connected with the fuselage, the cover 4 is provided with the first spring 3 at the upper end, the first upper end cover 2 is provided with a limiting boss as a stroke protection mechanism of the first micro switch 1 to avoid damage of the first micro switch 1 due to overstroke, the self-lubricating bushing 7 and the self-lubricating support sleeve 15 are installed between the first outer cylinder 61 and the inner cylinder 8 to reduce the friction when the inner cylinder 8 moves, a circular nut 24 is installed below the self-lubricating support sleeve 15, the circular nut 24 is threadedly connected with the first outer cylinder 61, the circular nut 24 is used for fixing the self-lubricating support sleeve 15, and at the same time, the circular nut 24 serves as a limiting block to prevent the cover 4 from being extruded and deformed and the first micro switch 1 from being damaged, the fixed piston 9 and the sealing ring 14 are installed on the upper part of the inner cylinder 8, the plunger 11 and the locking nut 12 are used for fixing the first upper end cover 2 and providing a pre-pressure for the first spring 3, the blocking ring 25 is installed between the inner cylinder 8 and the first outer cylinder 61 to prevent the inner cylinder 8 from being separated from the first outer cylinder 61, and the inner cylinder 8 moves in the vertical direction inside the first outer cylinder 61 under the support of the self-lubricating bushing 7 and the self-lubricating support sleeve 15, the displacement amount S1 of the inner cylinder 8 is equal to the rated stroke of the first micro switch 1, and is usually 2mm-5mm.

[0011] Optionally, for the front landing gear, when the airplane / helicopter is grounded, the ground load is transmitted to the first piston rod 171, the inner cylinder 8, and the cover 4 in sequence through the tire of the airplane wheel, the cover 4 compresses the first micro switch 1 by overcoming the pre-pressure K1 of the first spring 3, the internal circuit of the first micro switch 1 is connected, and the first micro switch 1 sends a grounding signal to the electromechanical management computer.

[0012] When the plane / helicopter leaves the ground, under the action of gravity and the first spring 3, the cover 4, the inner cylinder 8, and the first piston rod 171 move downward, the cover 4 is out of contact with the first micro switch 1, the internal circuit of the first micro switch 1 is disconnected, and the first micro switch 1 sends a signal to the electromechanical management computer.

[0013] Optionally, the pre-pressure K1 of the first spring 3 satisfies K1>n*Mg, n is the maximum downward overload coefficient during flight, and Mg is the gravity of the landing gear itself; when landing, the ground load N is greater than nMg+Mg, which can trigger the first micro switch 1.

[0014] Optionally, the second trigger mechanism is composed of a second upper end cover 52, a second spring 53, a micro switch trigger piece 19, a second positioning pin 55, a second outer cylinder 56, a throttle valve 16, a second piston rod 172, a floating piston 18, a plunger 20, a sealing ring 21, a compression nut 22, a self-lubricating bushing 23, a locking nut 26, and a second micro switch 51.

[0015] The upper end cover 52 is fixedly connected to the second outer cylinder 56 through the second positioning pin 55, the second outer cylinder 56 is fixedly connected to the fuselage, the second upper end cover 52 is installed on the upper part of the second spring 53 for compressing the second spring 53, the plunger 20 is installed at the opening of the upper part of the second outer cylinder 56, the micro switch trigger piece 19 is fixed to the plunger 20 through the compression nut 22 and moves together with the plunger 20, the plunger 20 is provided with a shoulder to ensure that the areas of the upper and lower ends are different; the self-lubricating bushing 23 is installed between the second piston rod 172 and the second outer cylinder 56 to reduce the friction when the second piston rod 172 moves vertically, the plunger 20 moves vertically by a small amount, and the displacement S2 of the plunger 20 is equal to the rated stroke of the second micro switch 51, which is usually 2mm-5mm.

[0016] Optionally, for the main landing gear, when the plane / helicopter contacts the ground, the landing gear is compressed, and the oil pressure increases. Because the areas of the upper and lower parts of the plunger 20 are different, there is an upward force, which overcomes the friction and the spring force, pushes the plunger 20, and moves the micro switch trigger piece 19 upward. The internal circuit of the second micro switch 51 is connected, and the second micro switch 51 sends a signal to the electromechanical management computer.

[0017] When the plane / helicopter leaves the ground, the landing gear is elongated, and the oil pressure disappears. Under the action of the pre-pressure K2 of the second spring 53 and the gravity mg, the plunger 20 moves downward, the micro switch trigger piece 19 is out of contact with the second micro switch 51, the internal circuit of the second micro switch 51 is disconnected, and the second micro switch 51 sends a signal to the electromechanical management computer.

[0018] Optionally,

[0019] The pre-pressing force K2 of the second spring 53 satisfies: Wherein, n is the maximum downward overload coefficient during flight, N is the ground load, A is the internal cross-sectional area of the second outer cylinder 56, u is the friction coefficient, m is the mass of the plunger 20, and f is the friction force between the sealing ring 21 and the plunger 20; when the ground load is triggered.

[0020] Optionally, the first triggering mechanism includes two first micro switches 1, and the second triggering mechanism of each main landing gear includes two second micro switches 51,

[0021] The take-off / landing signal of the aircraft / helicopter is executed by majority voting: more than half of the micro switches 1 send the take-off signal to the electromechanical management computer, and it is determined that the aircraft is in the take-off state; more than half of the micro switches 1 send the landing signal to the electromechanical management computer, and it is determined that the aircraft is in the landing state.

[0022] In a second aspect, a state management system is provided, including the landing gear of any one of the first aspect for triggering the wheel load signal, and the electromechanical management computer.

[0023] The present application has at least the following advantages:

[0024] 1) The micro switch triggering stroke can be designed, and the required landing stroke is short and the sensitivity is high;

[0025] 2) The micro switch is installed inside the landing gear, and is not easily affected by natural environment such as heat, salt mist, and sand dust, so that the service life of the switch can be increased;

[0026] 3) The triggering form of the micro switch is linear rather than rolling, so that the wear problem between the micro switch and the triggering piece can be reduced;

[0027] 4) Multiple switches can be conveniently installed, and the reliability of the landing signal can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Prevent the torsion arm from rotating to trigger the micro switch;

[0029] Figure 2 Convert the vertical displacement to the horizontal direction and then to the vertical direction;

[0030] Figure 3 The structure of the prior landing gear is shown in the schematic diagram;

[0031] Figure 4 The structure of the main landing gear is shown in the schematic diagram. DETAILED DESCRIPTION

[0032] The application will be described in further detail below with reference to specific embodiments and drawings.

[0033] The application provides a landing gear and state management system for triggering wheel load signals, which can conveniently trigger wheel load signals, has a simple and direct triggering mode, high precision, high sensitivity, high reliability, is not easily affected by external environment and the like.

[0034] Please refer to Figure 3 and Figure 4 An embodiment of the application provides a landing gear for triggering wheel load signals, the landing gear comprising a front landing gear and two main landing gears,

[0035] The front landing gear comprises a first outer cylinder 61, an inner cylinder 8, a first piston rod 171 and a first triggering mechanism, wherein the first outer cylinder 61 is fixedly connected with a fuselage, the inner cylinder 8 moves in a vertical direction inside the first outer cylinder 61, the first piston rod 171 transmits a ground load to the inner cylinder 8 and the first outer cylinder 61, and the first triggering mechanism is installed on an upper portion of the front landing gear.

[0036] Each main landing gear comprises a second outer cylinder 62, a second piston rod 172 and a second triggering mechanism, wherein the second outer cylinder 62 is fixedly connected with the fuselage, the second piston rod 172 moves in a vertical direction inside the second outer cylinder 62, an oil cavity is formed between the second outer cylinder 62 and the second piston rod 172, and the second triggering mechanism is installed on an upper portion of the main landing gear.

[0037] The first triggering mechanism comprises a first upper end cover 2, a first spring 3, a cover 4, a first positioning pin 5, a self-lubricating support sleeve 7, a fixed piston 9, a plug cap 10, a plunger 11, a locking nut 12, a sealing ring 13, a sealing ring 14, a self-lubricating support sleeve 15, a first micro switch 1 and a blocking ring 25.

[0038] The first upper end cover 2 is fixedly connected with the first outer cylinder 61 through the first positioning pin 5, the first outer cylinder 61 is fixedly connected with the fuselage, the first spring 3 is arranged on the upper end of the cover 4, the first upper end cover 2 is provided with a limiting boss as a stroke protection mechanism of the first micro switch 1, so as to avoid damage of the first micro switch 1 due to overstroke, the self-lubricating bushing 7 and the self-lubricating support sleeve 15 are arranged between the first outer cylinder 61 and the inner cylinder 8, and are used for reducing friction when the inner cylinder 8 moves, the circular nut 24 is arranged below the self-lubricating bushing 15, the circular nut 24 is threadedly connected with the first outer cylinder 61, the circular nut 24 is used for fixing the self-lubricating bushing 15, and simultaneously, the circular nut 24 serves as a limiting block, so as to prevent the cover 4 from being extruded and deformed and the first micro switch 1 from being damaged, the fixed piston 9 and the sealing ring 14 are arranged on the upper portion of the inner cylinder 8, the plunger 11 and the locking nut 12 are used for fixing the first upper end cover 2 and providing pre-pressure for the first spring 3, the retaining ring 25 is arranged between the inner cylinder 8 and the first outer cylinder 61, and is used for preventing the inner cylinder 8 from being separated from the first outer cylinder 61, under the support of the self-lubricating bushing 7 and the self-lubricating support sleeve 15, the inner cylinder 8 moves in the vertical direction in the interior of the first outer cylinder 61, the displacement S1 of the inner cylinder 8 is equal to the rated stroke of the first micro switch 1, and is usually 2mm-5mm.

[0039] For the front landing gear, when the airplane / helicopter contacts the ground, the ground load is sequentially transmitted to the first piston rod 171, the inner cylinder 8 and the cover 4 through the tire of the wheel, the cover 4 compresses the first micro switch 1 by overcoming the pre-pressure K1 of the first spring 3, the internal circuit of the first micro switch 1 is connected, and the first micro switch 1 sends the grounding signal to the electromechanical management computer.

[0040] When the airplane / helicopter leaves the ground, under the action of gravity and the first spring 3, the cover 4, the inner cylinder 8 and the first piston rod 171 move downward, the cover 4 is separated from the first micro switch 1, the internal circuit of the first micro switch 1 is disconnected, and the first micro switch 1 sends the takeoff signal to the electromechanical management computer.

[0041] The second trigger mechanism is composed of the second upper end cover 52, the second spring 53, the micro switch touch piece 19, the second positioning pin 55, the second outer cylinder 56, the throttle valve 16, the second piston rod 172, the floating piston 18, the plunger 20, the sealing ring 21, the compression nut 22, the self-lubricating bushing 23, the locking nut 26 and the second micro switch 51.

[0042] The upper end cover 52 is fixedly connected with the second outer cylinder 56 through the second positioning pin 55, the second outer cylinder 56 is fixedly connected with the fuselage, the second upper end cover 52 is installed on the upper portion of the second spring 53 for compressing the second spring 53, the plunger 20 is installed at the opening of the upper portion of the second outer cylinder 56, the micro switch contact piece 19 is fixed with the plunger 20 through the compression nut 22 and moves together with the plunger 20, the plunger 20 is provided with a shoulder to ensure that the areas of the upper and lower end faces are different; the self-lubricating bushing 23 is installed between the second piston rod 172 and the second outer cylinder 56 for reducing the friction force when the second piston rod 172 moves in the vertical direction, the plunger 20 moves in the vertical direction by a small amount, the displacement amount S2 of the plunger 20 is equal to the rated stroke of the second micro switch 51, and is usually 2mm-5mm.

[0043] For the front landing gear, when the airplane / helicopter contacts the ground, the ground load N is transmitted to the first piston rod 171, the inner cylinder 8 and the cover 4 through the tire of the wheel, the first spring 3 is arranged on the upper end of the cover 4 and has a certain pre-pressure (K1>n*Mg), the cover 4 overcomes the pre-pressure of the first spring 3, compresses the first micro switch 1, the internal circuit of the first micro switch 1 is connected, the first micro switch 1 sends the grounding signal to the electromechanical management computer, and the ground load N is greater than (nMg+Mg). Meanwhile, the limiting boss is arranged on the outer cylinder 2 as the stroke protection mechanism of the micro switch to avoid damage of the micro switch 1 due to overstroke, the displacement amount S1 is equal to the rated stroke of the micro switch 1, and is usually 2mm-5mm.

[0044] When the airplane / helicopter leaves the ground, the cover 4, the inner cylinder 8 and the first piston rod 171 move downward under the action of the gravity and the pre-pressure of the first spring 3, the cover 4 is separated from the first micro switch 1, the cover ring 25 is arranged between the inner cylinder 8 and the first outer cylinder 61 to prevent the inner cylinder 8 from being separated from the outer cylinder 6, the internal circuit of the micro switch 1 is disconnected, and the off-ground signal is obtained on the airplane.

[0045] For the main landing gear, when the airplane / helicopter contacts the ground, the ground load N is transmitted to the second piston rod 172 through the tire of the wheel, and the pressure in the oil cavity in the landing gear increases at this time. The plunger 20 is provided with a boss to ensure that the areas of the upper and lower end faces are different, the plunger moves upward under the action of the oil pressure, the resultant force direction is upward, and the size is wherein d is the diameter of the plunger, u is the friction coefficient between the sealing ring 21 and the plunger, the friction coefficient is usually 0.1, m is the mass of the plunger, and K2 is the pre-pressure of the spring. The pre-pressure K2 of the second spring 53 satisfies When the ground load is greater than (nMg+Mg), the internal circuit of the second micro switch 51 is connected, and the second micro switch 51 sends the grounding signal to the electromechanical management computer.

[0046] When the aircraft / helicopter leaves the ground, the landing gear is extended, the round nut 26 is arranged between the second outer tube 56 and the second piston rod 172 to prevent the second piston rod 172 from being pulled out, the floating piston 18 is in contact with the throttle valve 16 under the action of the air cavity pressure, the pressure in the oil cavity disappears, at this time, the downward movement of the plunger 20, the internal circuit of the second micro switch 51 is disconnected, and the second micro switch 51 sends a take-off signal to the electromechanical management computer. The ground load N only needs to meet The second micro switch 51 can trigger the grounding signal, so the sensitivity of the micro switch triggering is high.

[0047] The first triggering mechanism includes two first micro switches 1, and the second triggering mechanism of each main landing gear includes two second micro switches 51, and the take-off signal / grounding signal of the aircraft / helicopter is executed in a majority voting manner: more than half of the micro switches 1 send a take-off signal to the electromechanical management computer, and it is judged that the aircraft / helicopter is in a take-off state at this time; more than half of the micro switches 1 send a grounding signal to the electromechanical management computer, and it is judged that the aircraft / helicopter is in a grounding state.

[0048] The key points of the present application are as follows:

[0049] 1) Generally, the inner tube and the outer tube of the front landing gear buffer are fixedly connected, and the present application releases the vertical degree of freedom of the inner tube and the outer tube, thereby creating a movable amount S1;

[0050] 2) The movable amount S1 is equal to the design stroke of the micro switch;

[0051] 3) For the front landing gear, the spring stiffness is designed considering the influence of friction and aircraft maneuvering, and is related to the overload coefficient when the aircraft is maneuvering;

[0052] 4) The present application provides a calculation method of the main spring force;

[0053] 5) The present application can conveniently install multiple micro switches, judge the grounding signal in a majority voting manner, increase the reliability of the micro switch, and does not need to increase additional mechanisms.

[0054] The above only expresses the embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the patent scope. It should be noted that for ordinary skilled persons in the art, a number of modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. In addition, the non-exhaustive parts of the present application are all conventional technologies.

Claims

1. A landing gear for triggering a wheel load signal, characterized in that The landing gear comprises a front landing gear and two main landing gears, The front landing gear comprises a first outer cylinder (61), an inner cylinder (8), a first piston rod (171), and a first trigger mechanism, wherein the first outer cylinder (61) is fixedly connected with the fuselage, the inner cylinder (8) moves in the vertical direction inside the first outer cylinder (61), the first piston rod (171) transmits the ground load to the inner cylinder (8) and the first outer cylinder (61), and the first trigger mechanism is installed on the upper part of the front landing gear; Each main landing gear comprises a second outer cylinder (56), a second piston rod (172), and a second trigger mechanism, wherein the second outer cylinder (56) is fixedly connected with the fuselage, the second piston rod (172) moves in the vertical direction inside the second outer cylinder (56), an oil cavity is formed between the second outer cylinder (56) and the second piston rod (172), and the second trigger mechanism is installed on the upper part of the main landing gear; The first trigger mechanism comprises a first upper end cover (2), a first spring (3), a cover (4), a first positioning pin (5), a self-lubricating support sleeve (7), a fixed piston (9), a plug cap (10), a plunger (11), a locking nut (12), a sealing ring (13), a sealing ring (14), a self-lubricating support sleeve (15), a first micro switch (1), and a blocking ring (25); The first upper end cover (2) is fixedly connected with the first outer cylinder (61) through the first positioning pin (5), the first outer cylinder (61) is fixedly connected with the fuselage, the cover (4) is provided with the first spring (3) at the upper end, the first upper end cover (2) is provided with a limiting boss as a stroke protection mechanism of the first micro switch (1), the self-lubricating support sleeve (7) and the self-lubricating support sleeve (15) are installed between the first outer cylinder (61) and the inner cylinder (8), a circular nut (24) is installed below the self-lubricating support sleeve (15), the circular nut (24) is threadedly connected with the first outer cylinder (61), the fixed piston (9) and the sealing ring (14) are installed on the upper part of the inner cylinder (8), the plunger (11) and the locking nut (12) are used for fixing the first upper end cover (2) and providing a pre-pressure for the first spring (3), the blocking ring (25) is installed between the inner cylinder (8) and the first outer cylinder (61), the inner cylinder (8) moves in the vertical direction inside the first outer cylinder (61) under the support of the self-lubricating support sleeve (7) and the self-lubricating support sleeve (15), and the displacement amount S1 of the inner cylinder (8) is equal to the rated stroke of the first micro switch (1); The second trigger mechanism comprises a second upper end cover (52), a second spring (53), a micro switch touch piece (19), a second positioning pin (55), a throttle valve (16), a second piston rod (172), a floating piston (18), a plunger (20), a sealing ring (21), a pressing nut (22), a self-lubricating support sleeve (23), a locking nut (26), and a second micro switch (51); Wherein, the upper end cover (52) is fixedly connected with the second outer cylinder (56) through the second positioning pin (55), the second outer cylinder (56) is fixedly connected with the fuselage, the second upper end cover (52) is installed on the upper portion of the second spring (53) for compressing the second spring (53), the plunger (20) is installed at the opening of the upper portion of the second outer cylinder (56), the micro switch touch piece (19) is fixed with the plunger (20) through the compression nut (22) and moves together with the plunger (20), the plunger (20) is provided with a shoulder to ensure that the areas of the upper and lower end faces are different; the self-lubricating support sleeve (23) is installed between the second piston rod (172) and the second outer cylinder (56), the plunger (20) moves in the vertical direction, and the displacement S2 of the plunger (20) is equal to the rated stroke of the second micro switch (51).

2. The landing gear according to claim 1, characterized in that, For the front landing gear, when the aircraft / helicopter touches the ground, the ground load is transmitted to the first piston rod (171), the inner cylinder (8) and the cover (4) in turn through the tire, the cover (4) compresses the first micro switch (1) against the pre-pressing force K1 of the first spring (3), the internal circuit of the first micro switch (1) is turned on, and the first micro switch (1) sends a ground signal to the electromechanical management computer; when the aircraft / helicopter leaves the ground, the cover (4), the inner cylinder (8) and the first piston rod (171) move downward under the action of gravity and the first spring (3), the cover (4) is out of contact with the first micro switch (1), the internal circuit of the first micro switch (1) is turned off, and the first micro switch (1) sends a take-off signal to the electromechanical management computer.

3. A landing gear as claimed in claim 2, characterised in that, The pre-pressing force K1 of the first spring (3) satisfies K1>n*Mg, n is the maximum downward overload coefficient during flight, and Mg is the gravity of the landing gear itself; when landing, the ground load N is greater than (nMg+Mg), so that the first micro switch (1) is triggered.

4. The landing gear according to claim 1, characterized in that, For the main landing gear, when the aircraft / helicopter touches the ground, the landing gear is compressed, the oil pressure increases, and because the areas of the upper and lower parts of the plunger (20) are different, there is an upward force, which overcomes the friction and spring force, pushes the plunger (20), the micro switch touch piece (19) moves upward, the internal circuit of the second micro switch (51) is turned on, and the second micro switch (51) sends a ground signal to the electromechanical management computer; when the aircraft / helicopter leaves the ground, the landing gear is elongated, the oil pressure disappears, the plunger (20) moves downward under the action of the pre-pressing force K2 of the second spring (53) and gravity mg, the micro switch touch piece (19) is out of contact with the second micro switch (51), the internal circuit of the second micro switch (51) is turned off, and the second micro switch (51) sends a take-off signal to the electromechanical management computer.

5. The landing gear according to claim 4, characterized in that, The pre-pressure K2 of the second spring (53) satisfies: , Wherein, n is the maximum downward overload coefficient in the flight process, N is the ground load, A is the internal cross-sectional area of the second outer cylinder (56), u is the friction coefficient, m is the mass of the plunger (20), f is the friction between the sealing ring (21) and the plunger (20), and d is the plunger diameter; when the ground load is triggered.

6. The landing gear of claim 1, wherein, The first trigger mechanism includes two first micro switches (1), and the second trigger mechanism of each main landing gear includes two second micro switches (51), The off-ground signal / ground signal of the airplane / helicopter is executed by majority voting: more than half of the first microswitch (1) or the second microswitch (51) sends the off-ground signal to the electromechanical management computer, and it is judged that the airplane / helicopter is in off-ground state; more than half of the first microswitch (1) or the second microswitch (51) sends the ground signal to the electromechanical management computer, and it is judged that the airplane / helicopter is in ground state.

7. A state management system, characterized by The landing gear for triggering the wheel load signal according to any one of claims 1 to 6, and the electromechanical management computer.

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