Magneto-rheological buffer for aircraft landing gear and control method

Abstract

The invention provides a magneto-rheological buffer for an aircraft landing gear and a control method, the magneto-rheological buffer comprises a magneto-rheological valve, two excitation coils with opposite winding directions are arranged in the magneto-rheological valve, and generated magnetic loops can be perpendicular to an oil damping channel and overlapped between two coil grooves. And the whole damping channel is covered with a magnetic field. The magnetorheological buffer further comprises a working cylinder barrel, a piston rod, a guider, an actuating piston, a floating piston and a connecting rod, an oil cavity and an air cavity are formed in the working cylinder barrel, the magnetorheological valve is fixed in the oil cavity through the connecting rod, and the floating piston arranged on the connecting rod in a sleeving mode can isolate magnetorheological fluid from air in the air cavity. According to the method, the input current curves of the buffer under different drop vibration working conditions are reliably predicted by constructing different neural network models, and the input current curves are preset in the external power supply controller to control the input current of the buffer, so that the damping self-adaptive adjustment of the magnetorheological buffer is realized, the output force of the magnetorheological buffer is ensured to be constant, and the buffer efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of large-scale structural impact load mitigation control in the field of aerospace, and in particular relates to a magnetorheological buffer for aircraft landing gear and a control method thereof. Background Art

[0002] During the landing phase, the aircraft will encounter complex excitations from the external environment, causing serious impact problems on the structure, so great attention must be paid to the mitigation of structural impact loads. At present, the common practice is to install buffers in the landing gear, but the traditional oil-gas buffers usually adjust the damping force of the buffer by adjusting the size of the oil needle in the oil chamber. However, since the size of the oil needle is fixed, it can only be designed according to the estimated landing conditions to meet the buffering efficiency requirements under the corresponding conditions. However, the buffering efficiency is low under severe landing conditions or landing conditions that cannot be estimated in advance, and it is difficult to flexibly adjust according to different landing scenarios (such as asymmetric landing, landing under severe weather conditions, etc.). Therefore, it has poor adaptability in complex and changeable landing conditions and cannot well meet the efficient buffering requirements of modern aircraft.

[0003] Magnetorheological buffers are semi-active control devices that use the magnetorheological effect of magnetorheological fluid under a controllable magnetic field to provide controllable damping. Due to their simple structure and reliable operation, and the ability to adjust the control current in real time according to different application conditions to ensure buffering efficiency, magnetorheological buffers are widely used in impact mitigation in actual engineering.

[0004] Currently, the most common control algorithm used to mitigate the drop load of magnetorheological landing gear is the On-Off control method. This control algorithm controls the on-off of the power supply through trigger conditions during the drop process of the landing gear. That is, the power supply is disconnected when the output force of the magnetorheological buffer is high, and the power supply is connected when the output force of the magnetorheological buffer is low. This method can adjust the output force of the magnetorheological buffer within a certain range, but the control method has low control accuracy and cannot achieve precise control of the buffer during the drop process of the aircraft landing gear. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the existing magnetorheological damper and control method cannot meet the needs of adaptive damping adjustment control during the landing shock process of an aircraft landing gear, and to provide a magnetorheological damper and control method for an aircraft landing gear.

[0006] To achieve the above purpose, the technical solution provided by the present invention is:

[0007] A magnetorheological valve comprises a housing, a first end cover, a second end cover, a first excitation coil, a second excitation coil, an iron core, a conductor and a magnetorheological fluid;

[0008] The iron core is coaxially installed in the cavity of the shell, and there is a gap between the outer wall of the iron core and the inner wall of the shell to form an annular oil damping channel; the iron core has a central hole opened along its axis;

[0009] Two annular coil grooves are symmetrically arranged on the outer wall of the iron core, and one wire of the first excitation coil and the second excitation coil is wound in the two annular coil grooves, and after winding, the free end of the wire is led out of the iron core through the central hole of the iron core; wherein the winding directions of the first excitation coil and the second excitation coil are opposite;

[0010] The first end cover and the second end cover are coaxially nested at both ends of the housing, and the first end cover and the second end cover end surfaces are provided with a plurality of arc-shaped holes around the circumference for the magnetorheological fluid to pass through and enter the annular oil damping channel;

[0011] The second end cover has a central through hole coaxial with the central hole of the core, for the wire to pass through so as to extend out of the housing and connect to an external power source.

[0012] Furthermore, the first excitation coil and the second excitation coil are treated with vacuum paint to improve the insulation strength of the excitation coils.

[0013] Furthermore, the iron core and the shell are made of electrical pure iron material; the first end cover and the second end cover are made of stainless steel material.

[0014] The present invention also provides a magnetorheological buffer for aircraft landing gear, comprising a working cylinder, a first connector, a cylinder end cover, a piston rod, a guide, an actuating piston, a connecting rod, a floating piston, an inflation nozzle, a second connector and the above-mentioned magnetorheological valve;

[0015] The working cylinder has a working cavity, including an oil cavity and an air cavity connected to each other;

[0016] One end of the piston rod is located inside one end of the oil chamber after being connected to the actuating piston, and the other end of the piston rod is located outside the working cylinder and fixedly connected to the first connector;

[0017] The cylinder end cover is coaxially sealed and mounted on one end of the working cylinder, and the guide is nested on the piston rod body and is located between the cylinder end cover and the actuating piston;

[0018] The magnetorheological valve is located at the other end of the oil chamber, and the second end cover of the magnetorheological valve is connected to the second connector coaxially installed at the other end of the working cylinder barrel through the connecting rod; the connecting rod has a central through hole for allowing the wire to extend out of the working cylinder barrel;

[0019] The oil cavity is filled with magnetorheological fluid, and the amount of the magnetorheological fluid injected must at least cover the magnetorheological valve; the air cavity is filled with gas through the inflation nozzle;

[0020] The floating piston is sleeved on the connecting rod body and can slide along the connecting rod under the action of the gas in the gas cavity to separate the magnetorheological fluid from the gas;

[0021] The first connector is used to connect one end of the magnetorheological buffer to the aircraft landing gear wheel, and the second connector is used to install the other end of the magnetorheological buffer at the connection position between the aircraft landing gear and the aircraft body.

[0022] Furthermore, the center hole of the iron core is a multi-step hole, wherein one end of the center hole is a threaded hole for threaded connection with the connecting rod.

[0023] Furthermore, after the connecting rod is connected to the screw hole and the central through hole of the second end cover of the magnetorheological valve, it is sealed by hot melt adhesive to fix the wire located in the central hole of the iron core.

[0024] Furthermore, it also includes a polyurethane rubber pad, which is located at the end of the cylinder end cover and is coaxially connected to the cylinder end cover to avoid collision between the cylinder end cover and the first connecting head.

[0025] The present invention also provides a magnetorheological buffer control method, which is implemented based on the magnetorheological buffer for aircraft landing gear, and the control method comprises the following steps:

[0026] Step 1, obtaining the optimal expected damping force under several landing gear drop conditions, constructing an expected damping force neural network model, and using the drop condition parameters and the corresponding optimal expected damping force as training data to train the constructed expected damping force neural network model;

[0027] The expected damping force neural network model is used to predict the optimal expected damping force corresponding to the output according to the input drop shock working condition parameters;

[0028] The drop shock working condition parameters include drop shock mass, sinking speed and initial pressure of the buffer;

[0029] Step 2: construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the input current of the magnetorheological buffer under different drop shock conditions:

[0030] Step 2.1, based on the output force expression of the magnetorheological buffer F=f(s, v, I), respectively construct a current time characteristic neural network model and a current numerical characteristic neural network model, wherein, in the formula F=f(s, v, I), F is the output force of the magnetorheological buffer, s is the compression amount of the magnetorheological buffer, v is the compression speed of the magnetorheological buffer, and I is the input current of the magnetorheological buffer;

[0031] The current time characteristic neural network model is used to output the corresponding time characteristic of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force;

[0032] The current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force;

[0033] Step 2.2, obtaining the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under several drop shock conditions of the aircraft landing gear, using the parameters of each drop shock condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model, and the time characteristic or numerical characteristic data of the input current of the magnetorheological buffer as training data, respectively training the current time characteristic neural network model and the current numerical characteristic neural network model;

[0034] Step 2.3, respectively predicting and outputting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer corresponding to different drop shock conditions through the current time characteristic neural network model and the current numerical characteristic neural network model;

[0035] Step 3: Fitting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under the same drop shock working condition obtained in step 2 to obtain the current-time curve of the magnetorheological buffer under the corresponding drop shock working condition;

[0036] Step 4: The current-time curve of the magnetorheological buffer in each drop shock condition obtained in step 3 is preset in an external power supply controller. The power supply controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the output force of the magnetorheological buffer.

[0037] Furthermore, in step 1, the specific process of obtaining the optimal expected damping force under several landing conditions of the aircraft landing gear is as follows:

[0038] Step 1.1, traverse and take values ​​of the expected damping force of each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula:

[0039] The calculation formula of the buffering efficiency of the magnetorheological buffer is:

[0040]

[0041] Where, T1 is the end time of the first compression stroke of the magnetorheological buffer; F max is the maximum output force of the magnetorheological buffer; s max is the maximum value of the compression of the MR buffer; F(t) is the output force of the MR buffer at any time in the first compression stroke, and s(t) is the compression of the MR buffer at any time in the first compression stroke;

[0042] Step 1.2, traverse all expected damping forces and the corresponding buffering efficiencies of the magnetorheological buffers, and take the expected damping force corresponding to the buffering efficiency of the highest magnetorheological buffer as the optimal expected damping force under the current drop shock condition;

[0043] Step 1.3, obtain the optimal expected damping force corresponding to each drop shock condition according to the method in step 1.2.

[0044] Furthermore, in the step 2.2, the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under several landing conditions of the aircraft landing gear are obtained based on the simulation.

[0045] The advantages of the present invention are:

[0046] 1. The magnetorheological valve of the magnetorheological buffer of the present invention adopts a double-coil reverse winding structure. The two coils generate magnetic circuits in opposite directions. Both magnetic circuits can generate magnetic induction intensity perpendicular to the oil damping channel, and the magnetic induction intensity is superimposed on each other in the middle part of the two coil grooves. The entire damping channel is covered with magnetic induction intensity, which effectively solves the problem of low magnetic field utilization efficiency of the magnetorheological valve, realizes efficient utilization of the magnetic induction intensity of the magnetorheological buffer, and increases the damping adjustment range of the magnetorheological buffer.

[0047] 2. In the present invention, based on a neural network control algorithm, three neural network models of the designed magnetorheological buffer are constructed according to different landing conditions of the aircraft (including the landing mass of the landing gear, the sinking speed and the initial pressure of the buffer). The expected damping force neural network model is first trained and predicted to obtain the optimal expected damping force under different conditions. Then, the current time characteristic neural network model and the current numerical characteristic neural network model are trained and predicted with the optimal expected damping force obtained under different landing conditions, respectively, to obtain the current time characteristic and the current numerical characteristic under the corresponding conditions, that is, the trained and predicted neural network model can accurately predict the control current time history under different conditions, and can directly adaptively adjust the magnetorheological buffer current through the constructed neural network model according to different landing conditions, thereby realizing the adaptive adjustment of the damping parameters of the magnetorheological buffer, effectively reducing the output force peak of the magnetorheological buffer, greatly improving the buffering efficiency of the buffer, and solving the problems of fixed and unadjustable damping parameters of traditional aircraft landing gear buffers and low buffering efficiency of traditional control methods.

[0048] 3. The simulation results show that the control method of the present invention is reliable and effective. Compared with the traditional magnetorheological buffer and the traditional control method, the output force peak of the magnetorheological buffer is reduced, and the buffering efficiency is as high as more than 95%, with significant effect.

[0049] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0051] Figure 1 It is a front view of the magnetorheological valve of the present invention;

[0052] Figure 2 yes Figure 1 AA section view of the medium magnetorheological valve;

[0053] Figure 3 is a magnetic field distribution diagram of the magnetorheological valve in the present invention;

[0054] Figure 4 is a three-dimensional schematic diagram of a magnetorheological buffer of the present invention;

[0055] Figure 5 is a cross-sectional view of the magnetorheological buffer of the present invention along its axial direction;

[0056] Figure 6 is a flow chart of the magnetorheological buffer control method of the present invention;

[0057] Figure 7 It is the landing gear drop shock dynamics model diagram;

[0058] Figure 8 is a current curve diagram of a magnetorheological buffer under a certain working condition obtained based on simulation in an embodiment of the present invention;

[0059] Fig. 9 It is a comparison diagram of the current curve obtained by the method of the present invention and the current curve obtained by simulation;

[0060] Fig.10 It is a magnetorheological buffer current curve diagram predicted by the neural network model constructed by the present invention;

[0061] Fig.11 The figures are comparisons of the drop shock test results using the magnetorheological buffer of the present invention and the results of the existing on-off control; 11a is a comparison of the output force time history of the magnetorheological buffer, and 11b is a comparison of the work of the magnetorheological buffer.

[0062] Explanation of the reference numerals: 1-lower connecting head, 2-piston rod, 3-guide, 4-actuating piston, 5-working cylinder, 6-oil chamber, 7-air chamber, 8-magnetorheological valve, 801-housing, 802-upper end cover, 803-lower end cover, 804-first excitation coil, 805-second excitation coil, 806-iron core, 807-conducting wire, 9-floating piston, 10-upper connecting head, 11-one-way inflation nozzle, 12-polyurethane rubber pad, 13-connecting rod, 14-cylinder end cover. DETAILED DESCRIPTION

[0063] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0064] Reference Figure 1 and Figure 2The embodiment of the present invention provides a magnetorheological valve, including a housing 801, an upper end cover 802, a lower end cover 803, a first excitation coil 804, a second excitation coil 805, an iron core 806 and a wire 807. The iron core 806 is embedded in the housing 801 cavity, and there is a gap between the outer wall of the iron core and the inner wall of the housing 801, forming an annular oil damping channel; two annular coil grooves are symmetrically arranged on the outer wall of the iron core, and the first excitation coil 804 and the second excitation coil 805 are formed by winding a wire 807 in the two annular coil grooves, and the first excitation coil 804 and the second excitation coil 805 are wound in opposite directions, so that the two coils can generate magnetic circuits in opposite directions, and both magnetic circuits can generate magnetic induction intensity perpendicular to the oil damping channel, and the magnetic induction intensity at the position between the two coil grooves is superimposed and enhanced, which greatly improves the utilization efficiency of the radial magnetic field at the oil damping channel. In this embodiment, the first excitation coil and the second excitation coil are wound with 260 turns in total. After winding, they are treated with vacuum paint to improve the insulation strength of the coil and avoid direct contact between the magnetorheological fluid and the coil to corrode the coil.

[0065] The iron core 806 has two large holes and a smaller center hole along its axis. The wire 807 is wound in two annular coil slots and then led out from the center hole of the iron core for connection to an external power source.

[0066] The upper end cover 802 and the lower end cover 803 have the same appearance and are respectively installed at both ends of the housing 801. Four arc holes are evenly distributed around the circumference on the end faces of the upper end cover 802 and the lower end cover 803, which are used for the external magnetorheological fluid to pass through and enter the annular oil damping channel between the housing 801 and the iron core 806. The upper end cover 802 has a central through hole for the wire 807 to pass through. The wire 807 is connected to the external power supply after being led out through the central hole of the iron core and the central through hole of the upper end cover.

[0067] The iron core 806 and shell 801 of the magnetorheological valve are made of electrical pure iron with high magnetic permeability, and the upper end cover 802 and the lower end cover 803 are made of 304 stainless steel with low magnetic permeability. The purpose is to make the magnetic line loop gather in the iron core, the oil damping channel and the shell, reduce the magnetic line entering the upper end cover, the lower end cover and the external air, and maximize the use of the radial magnetic field generated by the excitation coil in the oil damping channel.

[0068] In order to verify and analyze the magnetic induction intensity distribution of the magnetorheological valve designed in the embodiment of the present invention, a constant DC current of 1A is passed through the magnetorheological valve in this embodiment, and the radial magnetic induction intensity of the oil damping channel at different axial depths under the same oil hole is measured through experiments and simulations. Figure 3It can be seen that the radial magnetic induction intensity at the oil damping channel of the magnetorheological valve is symmetrically distributed about the middle position of the oil damping channel. The direction of the magnetic induction intensity at the inlet and outlet of the oil damping channel is opposite to that at the middle position, and there are magnetic field areas with uniform intensity, and the magnetic induction intensity at the inlet and outlet is smaller than that at the middle position. Specifically, along the axial direction of the oil damping channel, at a depth of 0-10mm, the radial magnetic induction intensity of the oil damping channel gradually increases, and at a position near 10mm, the magnetic induction intensity is at the same level, about 60mT; at a depth of 15-20mm in the oil damping channel, the magnetic induction intensity gradually decreases until it is 0, at which time the magnetic field direction is opposite, and when the depth of the oil damping channel is 20-25mm, the magnetic induction intensity gradually increases until it reaches the maximum value; when the depth of the oil damping channel is 25-35mm, that is, in the middle position of the damping channel, the magnetic induction intensity always maintains a maximum value of about 70mT. The magnetic induction intensity of the oil damping channel depth of 35-60mm is symmetrically distributed with the oil damping channel depth of 0-25mm. Figure 3 The experimental data of medium magnetic field are close to the simulation data, which proves the effectiveness of simulation analysis.

[0069] Reference Figure 4 and Figure 5 The embodiment of the present invention also provides a magnetorheological buffer for aircraft landing gear, including a lower connector 1, a piston rod 2, a guide 3, an actuating piston 4, a working cylinder 5, a magnetorheological valve 8, a floating piston 9, an upper connector 10, an inflation nozzle 11, a polyurethane rubber pad 12, a connecting rod 13 and a cylinder end cover 14. Definition Figure 4 and Figure 5 The upper part of the magnetorheological buffer is on the right side of the middle, and the lower part of the magnetorheological buffer is on the left side.

[0070] The working cylinder 5 has a working cavity, wherein the upper part is an air cavity 7, and the lower part is an oil cavity 6 connected to the air cavity, wherein the air cavity is pre-filled with nitrogen, and the oil cavity is pre-filled with magnetorheological fluid, and the amount of the injected magnetorheological fluid must at least cover the magnetorheological valve 8. The magnetorheological valve 8 is arranged in the oil cavity, and the magnetorheological valve 8 is coaxially connected to the upper connector 10 arranged at the upper end of the working cylinder 5 through a connecting rod 13, thereby avoiding the direct connection between the magnetorheological valve and the working cylinder to cause structural damage to the working cylinder. In order to avoid the presence of gas affecting the buffering effect when the oil and gas are mixed, a floating piston 9 is mounted on the connecting rod 13 in this embodiment, and the floating piston 9 can slide along the connecting rod 13 to ensure the separation of oil and gas. Specifically, one end of the connecting rod 13 is fixedly connected to the upper end cover 808 and the iron core of the magnetorheological valve 8 by threads, and the other end is axially fixedly connected to the inner wall of the upper connector 10. The upper connector 10 has a central through hole, and the wire 807 extends out of the working cylinder along the central hole of the connecting rod 13 and the central through hole of the upper connector 10, and is connected to an external power source to prevent the wire from contacting the magnetorheological fluid and being corroded by the magnetorheological fluid, thereby shortening the service life. A one-way air filling nozzle 11 is installed on the outer wall of the upper end of the working cylinder, which is used to fill nitrogen into the air cavity 7 to adjust the pressure in the air cavity.

[0071] The coaxially connected piston rod 2 and the actuating piston 4 are installed in the lower part of the working cylinder, and the actuating piston 4 is located in the oil chamber 6 of the working cylinder 5. The magnetorheological buffer realizes the stretching or compression stroke through the actuating piston. The lower end of the working cylinder is successively installed with a cylinder end cover 14 and a polyurethane rubber pad 12 to avoid collision between the lower connector 1 and the cylinder end cover 14. A guide 3 is mounted on the piston rod 2, and the guide is located between the actuating piston 4 and the cylinder end cover 14, which is used to provide a guiding effect for the movement of the piston rod and ensure the coaxiality of the movement of the piston rod. The protruding end of the piston rod 2 is threadedly connected with a coaxially arranged lower connector 1, and the lower connector 1 is used to connect the magnetorheological buffer to the aircraft landing gear wheel; the upper connector 10 is connected to the connection position between the aircraft landing gear and the aircraft body.

[0072] The working principle of the magnetorheological buffer designed in the embodiment of the present invention is as follows: when the buffer is under pressure, the actuating piston 4 pushes the magnetorheological fluid into the oil damping channel through the fan-shaped through hole of the lower end cover of the magnetorheological valve, and the magnetic induction intensity at the oil damping channel can be adjusted with the change of the excitation coil current, thereby changing the shear yield stress of the magnetorheological fluid flowing through the oil damping channel, and then changing the fluid viscosity, and realizing the control of the damping force of the magnetorheological buffer. During the movement of the actuating piston, part of the aircraft landing energy is dissipated in the form of damping heat, and the other part is stored in the air cavity of the working cylinder 5 in the form of potential energy. When the nitrogen in the air cavity is compressed to a certain extent, the pressure of the air cavity is greater than the pressure of the actuating piston 4, and the buffer begins to stretch. The magnetorheological fluid enters the oil damping channel through the fan-shaped through hole of the upper end cover of the magnetorheological valve to generate a damping force, and the aircraft landing energy is dissipated again in the form of heat until the air cavity pressure is insufficient to support the buffer to stretch. In this reciprocating motion, the buffer dissipates the aircraft's landing energy through the compression and extension stroke of the actuating piston, thereby achieving the purpose of reducing the aircraft's landing gear drop shock load.

[0073] Design ideas of the magnetorheological buffer control method of the embodiment of the present invention:

[0074] Due to the magnetorheological effect of the magnetorheological fluid, when the external magnetic induction intensity increases, the shear yield stress of the magnetorheological fluid increases, which is manifested as an increase in the viscosity of the oil, thereby increasing the damping force of the magnetorheological buffer. The embodiment of the present invention is based on a neural network model to obtain a preset current curve under different drop shock conditions to control the magnitude of the buffer output force, so that the buffer output force is constant and the "platform" effect of the buffer output force is achieved, thereby improving the buffer's buffering efficiency and obtaining the optimal buffering effect of the magnetorheological buffer.

[0075] By constructing a landing gear drop dynamics model including the above-mentioned magnetorheological buffer, the damping force, air spring force and wheel spring force of the magnetorheological buffer are used to obtain specific relationship expressions through parameter identification methods to solve the landing gear drop dynamic response. The expression that affects the output force of the magnetorheological buffer is F=f(s, v, I), that is, the output force of the magnetorheological buffer can be determined by the buffer compression amount s, compression speed v and excitation coil current I (magnetorheological buffer input current). In order to improve the buffering efficiency of the magnetorheological buffer, it is necessary to make the shape of the work curve of the magnetorheological buffer tend to be rectangular, to ensure that the output force of the magnetorheological buffer remains constant and presents a "platform" effect, that is, to ensure that the output force of the magnetorheological buffer remains unchanged as the buffer compression amount s and compression speed v change, that is, the output force F=F desire , F desire is the optimal expected damping force of the magnetorheological buffer. desire When F=F desire The current I, when F>Fdesire When the current I=0, the external power supply can be used to control the current

[0076] The expected damping force of the magnetorheological buffer under different drop conditions is different. The corresponding expected damping force can be obtained according to the drop parameters of different drop conditions (including drop mass, sinking speed and initial pressure of the buffer). During the drop process of the landing gear, the magnetorheological buffer is continuously input according to the motion state of the magnetorheological buffer so that the output force of the magnetorheological buffer is equal to the expected damping force F. desire The current is used to keep the output force of the magnetorheological buffer constant throughout the entire falling shock process, thereby ultimately achieving a "platform" effect of the output force.

[0077] Considering that there is a time delay in the landing gear during the landing process, the current cannot be adjusted in real time according to the compression amount and compression speed of the magnetorheological buffer. Therefore, the present invention adopts a preset current method, and obtains a preset current curve under the working condition through a neural network control algorithm according to the landing condition, and then inputs the current curve into the external power control system, so that the external power control system controls and adjusts the input current of the magnetorheological buffer according to the current curve. Figure 6 The control method of the magnetorheological buffer of the present invention comprises the following steps:

[0078] Step 1, obtain the optimal expected damping force under several landing gear drop conditions, construct an expected damping force neural network model, and use the drop condition parameters and the corresponding optimal expected damping force as training data to train the constructed expected damping force neural network model. The expected damping force neural network model constructed in this step is used to predict the optimal expected damping force corresponding to the output according to the input drop condition parameters.

[0079] Step 1.1, according to Figure 7 The established landing gear drop dynamics model can obtain the drop dynamics equation of the magnetorheological buffer landing gear two-degree-of-freedom system:

[0080]

[0081] Where m1 is the sprung mass, including the total mass of the buffer outer tube, the hanging basket (corresponding to the mass of the aircraft body) and its connecting parts; m2 is the unsprung mass, including the total mass of the piston rod, the wheel and its connecting parts; F is the output force of the magnetorheological buffer, F t is the wheel elastic force; x1 is the displacement of the sprung mass block, x2 is the displacement of the unsprung mass block; the compression amount of the MR buffer s = x2-x1, and the compression speed of the MR buffer is

[0082] The positions of the sprung mass block and the unsprung mass block when the landing gear is fully extended and the wheels just touch the ground are taken as the coordinate origin, and the vertical upward direction is defined as the positive direction. Since the compression amount and compression speed of the magnetorheological buffer will change continuously with the change of the landing gear falling height during the landing gear falling process, the output force of the magnetorheological buffer F=f(s, v, I) can be obtained, that is, the output force of the magnetorheological buffer can be determined by the compression amount s, the compression speed v and the excitation coil current I. According to the magnetorheological buffer output force expression F=f(s, v, I), when the compression amount and compression speed are constantly changing, the output force of the magnetorheological buffer can be kept constant by adjusting the current. Next, we determine the optimal expected damping force to make the output force of the magnetorheological buffer constant:

[0083] Determine several drop shock working conditions, traverse and take values ​​of the expected damping force of each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula:

[0084] The calculation formula of the buffering efficiency of the magnetorheological buffer is:

[0085]

[0086] Where, T1 is the end time of the first compression stroke of the magnetorheological buffer; F max is the maximum output force of the magnetorheological buffer; s max is the maximum value of the compression of the magnetorheological buffer; F(t) is the output force of the magnetorheological buffer at any time in the first compression stroke, and s(t) is the compression of the magnetorheological buffer at any time in the first compression stroke.

[0087] Step 1.2, traverse all expected damping forces and the corresponding buffering efficiencies of the magnetorheological buffers, and take the expected damping force corresponding to the buffering efficiency of the highest magnetorheological buffer as the optimal expected damping force for the current drop condition.

[0088] Step 1.3, according to step 1.2, obtain the optimal expected damping force corresponding to multiple drop shock conditions.

[0089] Step 1.4, using each drop shock condition parameter and the corresponding optimal expected damping force as training parameters, the constructed expected damping force neural network model is trained, so that the neural network model of the constructed expected damping force neural network model memorizes the input-output relationship between the drop shock condition parameters and the optimal expected damping force.

[0090] Step 2: Construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the input current of the magnetorheological buffer under different drop shock conditions. Specifically, the following steps are included:

[0091] Step 2.1, based on the output force expression of the magnetorheological buffer F=f(s, v, I), respectively construct a current time characteristic neural network model and a current numerical characteristic neural network model, wherein, in the formula F=f(s, v, I), F is the output force of the magnetorheological buffer, s is the compression amount of the magnetorheological buffer, v is the compression speed of the magnetorheological buffer, and I is the input current of the magnetorheological buffer;

[0092] The constructed current time characteristic neural network model is used to output the corresponding time characteristic of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force.

[0093] The constructed current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force.

[0094] Step 2.2, in this embodiment, firstly, simulation is used to obtain the time characteristic data and numerical characteristic data of the input current of the magnetorheological buffer under several drop shock conditions of the aircraft landing gear, and then the parameters of each drop shock condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model in step 1, and the time characteristic data or numerical characteristic data of the input current of the magnetorheological buffer are used as training data to train the constructed current time characteristic neural network model and current numerical characteristic neural network model respectively, so that the constructed current time characteristic neural network model and current numerical characteristic neural network model are trained to memorize the corresponding input-output relationship respectively. The trained current time characteristic neural network model and current numerical characteristic neural network model can respectively predict and output the current time characteristic and current numerical characteristic under the corresponding drop shock condition according to any drop shock condition parameters and the corresponding optimal expected damping force.

[0095] Figure 8 This is the current-time characteristic curve of the magnetorheological buffer under a certain working condition obtained based on simulation in this embodiment. This current-time curve can be simplified into a curve composed of 8 characteristic numbers, where t1 is the time when the curve drops for the first time, t2 is the time when the curve drops to the minimum value, t3 is the time when the curve reaches the maximum value, t4 is the time when the curve drops for the second time, t5 is the time when the curve drops to the minimum value for the second time, and t6 is the time when the curve reaches the maximum value again. At the same time, y1 is the size of the first valley value, and y2 is the size of the second valley value. It can be seen from this that as long as we get these eight characteristic values, each section of the curve is fitted with a quadratic function to obtain the current-time curve.

[0096] Step 2.3, respectively predicting and outputting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer corresponding to different drop shock conditions through the current time characteristic neural network model and the current numerical characteristic neural network model.

[0097] Step 3, using the quadratic function fitting method to fit the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under the same drop shock condition obtained in step 2, to obtain the current-time curve of the magnetorheological buffer in the corresponding drop shock condition.

[0098] Fig. 9 The figure is a comparison diagram of the current curve obtained under a certain drop shock condition based on the method of the present invention and the current curve obtained by simulation. It can be seen from the figure that the current curve obtained based on the prediction of the neural network model of the present invention and the data fitting method is basically consistent with the current curve obtained by simulation, indicating the reliability of the current control curve obtained by the method of the present invention. By analyzing and statistically analyzing the current curves obtained by the method of the present invention and the simulation method under multiple drop shock conditions, the prediction accuracy of the time characteristic neural network model is 94.78%, and the prediction accuracy of the numerical characteristic neural network is 95.53%, which proves the effectiveness of the neural network model method of the present invention.

[0099] Step 4, preset the current-time curve of the lower magnetorheological buffer in each drop shock condition obtained in step 3 in the external power controller, and the power controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is always equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the damping force of the magnetorheological buffer.

[0100] In order to verify the effectiveness of the method of the present invention, a certain drop shock condition is randomly selected, in which the landing gear drop shock mass is 210kg, the sinking speed is 1m / s, and the initial pressure of the buffer air cavity is 0.6MPa. First, the expected damping force neural network model constructed by the present invention is used to predict that the optimal expected resistance under this condition is 4600N. Then, the drop shock condition parameters and the obtained optimal expected damping force corresponding to this condition are input into the constructed current time characteristic neural network model and current numerical characteristic neural network model, and the time characteristic data and numerical characteristic data of the current are predicted respectively. Finally, the obtained time characteristic data and numerical characteristic data are fitted with a quadratic function to obtain the input current curve of the magnetorheological buffer. The current curve is shown in the figure. Fig.10 The current-time curve obtained by the method of the present invention is input into the constructed landing gear drop dynamics simulation model to obtain the output force time history curve and work curve of the magnetorheological buffer.

[0101] Fig.11The output force time history curve and work curve of the magnetorheological buffer obtained by the method of the present invention and the output force time history curve and work curve of the magnetorheological buffer obtained by the traditional on-off control method are shown, wherein 11a is the output force time history comparison of the magnetorheological buffer, and 11b is the work comparison of the magnetorheological buffer. It can be seen from the output force history curve that under the same landing gear drop shock condition, the peak value of the output force of the magnetorheological buffer when controlled by the traditional on-off method is 6249.5N; the peak value of the output force of the magnetorheological buffer when controlled by the control method of the present invention is 4505.7N. Under the control of the method of the present invention, the peak value of the output force of the magnetorheological buffer is reduced by 27.9%, while the output force of the magnetorheological buffer is kept constant, realizing the "platform" effect of the output force. It can be seen from the power curve that the buffering efficiency of the magnetorheological buffer is 61.86% when the traditional on-off method is used for control, while the buffering efficiency of the magnetorheological buffer reaches 95.10% when the method of the present invention is used for control. This shows that the control method of the present invention can effectively improve the buffering efficiency of the magnetorheological buffer, proving the superiority of the magnetorheological buffer designed by the present invention and the control method of the present invention.

[0102] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A magnetorheological valve, characterized in that: It includes a shell, a first end cover, a second end cover, a first excitation coil, a second excitation coil, an iron core, a conductor and a magnetorheological fluid; The iron core is coaxially installed in the cavity of the shell, and there is a gap between the outer wall of the iron core and the inner wall of the shell to form an annular oil damping channel; the iron core has a central hole opened along its axis; Two annular coil grooves are symmetrically arranged on the outer wall of the iron core, and one wire of the first excitation coil and the second excitation coil is wound in the two annular coil grooves, and after winding, the free end of the wire is led out of the iron core through the central hole of the iron core; wherein the winding directions of the first excitation coil and the second excitation coil are opposite; The first end cover and the second end cover are coaxially nested at both ends of the housing, and the first end cover and the second end cover end surfaces are provided with a plurality of arc-shaped holes around the circumference for the magnetorheological fluid to pass through and enter the annular oil damping channel; The second end cover has a central through hole coaxial with the central hole of the core, for the wire to pass through so as to extend out of the housing and connect to an external power source.

2. A magnetorheological valve according to claim 1, characterized in that: The first excitation coil and the second excitation coil are treated with vacuum paint to improve the insulation strength of the excitation coils.

3. The magnetorheological valve according to claim 2, characterized in that: The iron core and the shell are made of electrical pure iron material; the first end cover and the second end cover are made of stainless steel material.

4. A magnetorheological buffer for aircraft landing gear, characterized in that: It comprises a working cylinder, a first connector, a cylinder end cover, a piston rod, a guide, an actuating piston, a connecting rod, a floating piston, an air filling nozzle, a second connector and the magnetorheological valve according to any one of claims 1 to 3; The working cylinder has a working cavity, including an oil cavity and an air cavity connected to each other; One end of the piston rod is located inside one end of the oil chamber after being connected to the actuating piston, and the other end of the piston rod is located outside the working cylinder and fixedly connected to the first connector; The cylinder end cover is coaxially sealed and mounted on one end of the working cylinder, and the guide is nested on the piston rod body and is located between the cylinder end cover and the actuating piston; The magnetorheological valve is located at the other end of the oil chamber, and the second end cover of the magnetorheological valve is connected to the second connector coaxially installed at the other end of the working cylinder barrel through the connecting rod; the connecting rod has a central through hole for allowing the wire to extend out of the working cylinder barrel; The oil chamber is filled with magnetorheological fluid, and the injected amount of the magnetorheological fluid must at least cover the magnetorheological valve; The air cavity is filled with gas through the inflation nozzle; The floating piston is sleeved on the connecting rod body and can slide along the connecting rod under the action of the gas in the gas cavity to separate the magnetorheological fluid from the gas; The first connector is used to connect one end of the magnetorheological buffer to the aircraft landing gear wheel, and the second connector is used to install the other end of the magnetorheological buffer at the connection position between the aircraft landing gear and the aircraft body.

5. A magnetorheological buffer for aircraft landing gear according to claim 4, characterized in that: The center hole of the iron core is a multi-step hole, wherein one end of the center hole is a threaded hole for threaded connection with the connecting rod.

6. A magnetorheological buffer for aircraft landing gear according to claim 5, characterized in that: After the connecting rod is connected to the screw hole and the central through hole of the second end cover of the magnetorheological valve, it is sealed by hot melt adhesive to fix the wire located in the central hole of the iron core.

7. The magnetorheological buffer for aircraft landing gear according to claim 6, characterized in that: It also includes a polyurethane rubber pad, which is located at the end of the cylinder end cover and is coaxially connected to the cylinder end cover to prevent the cylinder end cover from colliding with the first connecting head.

8. A magnetorheological buffer control method, characterized in that: Based on the implementation of the magnetorheological buffer for aircraft landing gear according to any one of claims 4 to 7, the control method comprises the following steps: Step 1, obtaining the optimal expected damping force under several landing gear drop conditions, constructing an expected damping force neural network model, and using the drop condition parameters and the corresponding optimal expected damping force as training data to train the constructed expected damping force neural network model; The expected damping force neural network model is used to predict the optimal expected damping force corresponding to the output according to the input drop shock working condition parameters; The drop shock working condition parameters include drop shock mass, sinking speed and initial pressure of the buffer; Step 2: construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the input current of the magnetorheological buffer under different drop shock conditions: Step 2.1, based on the output force expression of the magnetorheological buffer F=f(s, v, I), respectively construct a current time characteristic neural network model and a current numerical characteristic neural network model, wherein, in the formula F=f(s, v, I), F is the output force of the magnetorheological buffer, s is the compression amount of the magnetorheological buffer, v is the compression speed of the magnetorheological buffer, and I is the input current of the magnetorheological buffer; The current time characteristic neural network model is used to output the corresponding time characteristic of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force; The current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force; Step 2.2, obtaining the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under several drop shock conditions of the aircraft landing gear, using the parameters of each drop shock condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model, and the time characteristic or numerical characteristic data of the input current of the magnetorheological buffer as training data, respectively training the current time characteristic neural network model and the current numerical characteristic neural network model; Step 2.3, respectively predicting and outputting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer corresponding to different drop shock conditions through the current time characteristic neural network model and the current numerical characteristic neural network model; Step 3: Fitting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under the same drop shock working condition obtained in step 2 to obtain the current-time curve of the magnetorheological buffer under the corresponding drop shock working condition; Step 4: The current-time curve of the magnetorheological buffer in each drop shock condition obtained in step 3 is preset in an external power supply controller. The power supply controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the output force of the magnetorheological buffer.

9. A magnetorheological damper control method according to claim 8, characterized in that: In step 1, the specific process of obtaining the optimal expected damping force under several landing conditions of the aircraft landing gear is as follows: Step 1.1, traverse and take values ​​of the expected damping force of each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula: The calculation formula of the buffering efficiency of the magnetorheological buffer is: Where, T1 is the end time of the first compression stroke of the magnetorheological buffer; F max is the maximum output force of the magnetorheological buffer; s max is the maximum value of the compression of the MR buffer; F(t) is the output force of the MR buffer at any time in the first compression stroke, and s(t) is the compression of the MR buffer at any time in the first compression stroke; Step 1.2, traverse all expected damping forces and the corresponding buffering efficiencies of the magnetorheological buffers, and take the expected damping force corresponding to the buffering efficiency of the highest magnetorheological buffer as the optimal expected damping force under the current drop shock condition; Step 1.3, obtain the optimal expected damping force corresponding to each drop shock condition according to the method in step 1.

2.

10. A magnetorheological damper control method according to claim 8, characterized in that: In the step 2.2, the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under several landing conditions of the aircraft landing gear are obtained based on the simulation.

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