CN111071436B - Mechanical-hydraulic aircraft front wheel turning anti-swing system - Google Patents
Mechanical-hydraulic aircraft front wheel turning anti-swing system Download PDFInfo
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- CN111071436B CN111071436B CN201911276578.9A CN201911276578A CN111071436B CN 111071436 B CN111071436 B CN 111071436B CN 201911276578 A CN201911276578 A CN 201911276578A CN 111071436 B CN111071436 B CN 111071436B
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- 238000013016 damping Methods 0.000 claims abstract description 43
- 239000003921 oil Substances 0.000 claims description 168
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- 238000000034 method Methods 0.000 claims description 15
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- 239000013589 supplement Substances 0.000 claims description 11
- 230000009471 action Effects 0.000 claims description 8
- 239000010720 hydraulic oil Substances 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 230000001133 acceleration Effects 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
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- 238000005516 engineering process Methods 0.000 description 2
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- 238000011022 operating instruction Methods 0.000 description 1
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- 238000000926 separation method Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/50—Steerable undercarriages; Shimmy-damping
- B64C25/505—Shimmy damping
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Abstract
The invention discloses a mechanical-hydraulic airplane front wheel turning anti-swing system, and aims to provide a multifunctional combined valve integrating reversing, damping, compensation and state conversion. The invention is realized by the following technical scheme: the electromagnetic valve divides high-pressure oil into two paths, one path is sent into a state switching valve through a reversing valve, enters a safety valve to control an aircraft front wheel steering actuating cylinder, overcomes the spring force of the state switching valve, enables the state switching valve to be in a left-hand function, the reversing valve is communicated with two cavities of the aircraft front wheel steering actuating cylinder, the two cavities of the steering actuating cylinder are cut off by a one-way damping valve, and the other path enters a swing-reducing oil return compensator through a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of the electromagnetic valve; the electromagnetic valve is powered off, the high-pressure oil is communicated with the reversing valve, the reversing valve enters the swing-reducing oil return compensator through the bypass pipeline, the state switching valve is communicated, the reversing valve and the two cavities of the front wheel turning actuating cylinder are cut off, the two cavities of the turning actuating cylinder are communicated with the one-way damping valve, and the front wheel of the aircraft is controlled to be in a swing-reducing mode through the safety valve.
Description
Technical Field
The invention relates to a mechanical-hydraulic airplane front wheel turning anti-swing system.
Background
The control surface control, the front wheel steering, the landing gear retraction and the like of the airplane are all carried out by virtue of the hydraulic system of the airplane. The nose wheel control technology of the landing gear of the aircraft is a key technology for realizing ground control of a modern aircraft, and is directly related to the taking-off and landing safety of the aircraft. It is known to provide steering of an aircraft on the ground by a front wheel steering system. The input sources of turning are totally two, one is a turning hand wheel, and the other is a rudder pedal. The turning range controlled by the turning hand wheel is wider, the front wheel can be controlled to rotate by 78 degrees leftwards and rightwards in the maximum stroke, and the pedals can only be controlled to rotate by 7 degrees leftwards or rightwards maximally. The turning input from the turning hand wheel or rudder pedal reaches the turning metering valve through a wire loop, after which the turning metering valve provides left or right turning pressure to the turning cylinder. The aircraft controls the whole aircraft to turn through the rotation of the nose landing gear wheels around the axis of the buffer support, belongs to a mechanical feedback type nose wheel turning control system, and has two input modes: the hand wheel control input mode and the foot control input mode are that the hand wheel mechanism controls the front wheel to rotate when the ground slides at a low speed and turns at a large angle, and the steering plate mechanism is used for correcting the deviation of the front wheel when the ground takes off and lands. Along with the proposal of the large-angle turning requirement of the large civil aircraft, in order to meet the requirement of system swing reduction, the modern civil aircraft does not use a single-actuator front wheel steering mechanism. The front wheel steering system is widely used in aircraft design as a device for improving the ground taxi mobility and landing safety of the aircraft.
Front wheel steering systems have experienced mechanical, mechanical-hydraulic in the development process. In order to realize the directional control of the ground sliding stage and eliminate the front wheel shimmy after disturbance in the high-speed sliding process. A front wheel steering system having two operating states of steering and sway reduction is generally employed. The electrohydraulic servo control system for forming the double-actuating cylinder type front wheel steering system comprises a one-way valve, a filter, a selection valve, a backfill valve, a flow dividing valve, a swing reducing valve, an oil compensator, a steering actuating cylinder and a rotary conversion, wherein the selection valve and the flow dividing valve form a state conversion module which is responsible for realizing the conversion between a turning state and a swing reducing state; the pressure maintaining valve and the compensator form a pressure maintaining module, so that the system pressure is maintained above the air separation pressure, and cavitation in the loop is prevented; the aircraft is subjected to impact loads from the ground during ground running. In the double-actuating cylinder type front wheel turning mechanism, the two actuating cylinders are symmetrically distributed, and the stress condition is basically symmetrical under the swing reducing state, so that the relation curve of the acceleration of the piston with time is changed. Under the impact action of external load, the acceleration of the piston generates oscillation, and the acceleration is maximally increased to 12m/s; when the load disappears, the acceleration of the piston is rapidly reduced until approaching 0 under the hydraulic damping action generated by the swing reducing valve after small oscillation. The feedback mode of the system is that the turning actuator cylinder is connected with the turning control valve through the feedback pull rod and the steel cable, so that the position of the actuator cylinder corresponds to that of the turning control valve, and the aim of controlling the steering of the front wheels of the aircraft according to the steering command of the front wheels of the aircraft input by a driver is achieved. The front wheel steering system can not only operate the movement direction of the aircraft, but also respond in time when the aircraft front wheel shimmy or deviates from a preset course due to disturbance or crosswind, single-side tire burst air leakage and other reasons in the running process of the aircraft, and eliminate the front wheel shimmy and correct the course. Hydraulic transmission is a major source of power for each steering system of an aircraft. Because the front wheel steering system uses green system hydraulic pressure from the nose landing gear door closing oil circuit, the front wheel steering system cannot work after the aircraft executes the gravity landing gear releasing program, and a trailer is required to drag back to the parking apron. The two swing reducing valves and the two safety valves form a swing reducing module of the system, when the system is in a swing reducing mode, if the system is impacted to generate swing vibration, the swing reducing valve can reduce the vibration of the system and make the system stable through damping provided by the swing reducing valve; the two rotary reversing valves have the function of enabling the hydraulic circuit to complete automatic reversing when the actuator cylinder moves to the dead point position. The switching of the system operating state is accomplished by manipulating a controller on the control panel. When the turning condition of the front wheels is met, the input turning signals and the turning angle feedback signals of the system are transmitted to the controller, and the controller judges the difference value between the input signals and the feedback signals to control the valve opening of the servo valve, so that the required steering angle and speed are obtained. When the rotation angle of the front wheel reaches the angle corresponding to the input signal, the signal output by the controller is zero, and the servo valve is powered off at the moment, and the front wheel stops at the corresponding position, so that the servo control of the front wheel turning is realized. Correspondingly, the hydraulic system of the front wheel steering system is provided with two corresponding working circuits, namely a steering circuit and a swing reducing circuit of the front wheel steering system. In the turning working state, the selection valve is opened to the leftmost position by the input control signal, the flow dividing valve is activated at the same time, the system is in the turning preparation state, at the moment, the working channels of the two steering actuators are isolated by the flow dividing valve, a driver can input the turning signal to the servo valve through the controller, and the servo valve outputs corresponding pressure according to the obtained turning instruction, so that the two steering actuators are driven to move, and the front wheel deflection is realized. Under the condition that the front wheel does not need to turn or the electrical part of the system fails, the front wheel turning system is in a swing-reducing state, and working passages of the two actuating cylinders are mutually communicated. At this time, if the nose landing gear generates shimmy due to impact and the like, oil in the actuating cylinders can flow from one actuating cylinder to the other actuating cylinder through the shimmy reduction valve and the flow dividing valve, and the damping effect of the shimmy reduction valve converts energy generated by shimmy of the system into heat energy to be dissipated, so that the shimmy reduction effect is achieved. In addition to the swing reducing valve, a safety valve and a compensator are provided in the swing reducing circuit. The function of the compensator is to prevent the system from being impacted, but the system has the following disadvantages: because the pull rod, the rocker arm, the steel cable and the pulley are arranged in a long distance, the system has invalid travel, the operation performance is poor, and the operation force is large; the accessories and parts are more, and the weight is heavy; the installation and adjustment are complex, and the maintenance is difficult. The problem is mainly focused on the use of cable-operated hydraulic accessories, whether the cable of a front wheel steering system can be replaced by other equipment with the same function, and the operation of the cable is changed into the transmission operation of an operation signal, which is the fly-by-wire operation adopted by most of the current aircrafts. The fly-by-wire control is that a pilot operates an electric valve in a cabin, an operating instruction is transmitted through an electric wire, and the transmitted electric signal is processed through an operating control box to control the hydraulic booster of the operating actuator to stretch and deflect the front wheel. The fly-by-wire steering front wheel steering is characterized in that two sensors, an electromagnetic valve and a plurality of electric control elements are added on the basis of a mechanical-hydraulic steering system. One of the sensors (feedback potentiometer) is used for monitoring the action condition of the actuator cylinder, and the second sensor (input potentiometer) arranged on the front pillar is used as a sensor for issuing commands to monitor the position of the pedal or the hand wheel. The electromagnetic valve is used for electrically controlling the flow direction of hydraulic oil, controlling the actuating direction of the actuating cylinder and is arranged near the actuating cylinder. The system mainly replaces an input and output structure through a displacement sensor, compares and judges input signals and feedback signals through a control box, detects the deflection angle of the front wheels, controls a combined hydraulic valve to work through the difference value of the input signals and the feedback signals, drives a front wheel steering actuating cylinder, and ensures that the front wheels steer according to the instructions of a driver. The fly-by-wire front wheel steering system mainly realizes two functions of steering and swing reduction. The system is used for controlling the ground direction of an aircraft and preventing shimmy in a taxiing stage, and the normal working mode of the system comprises the following steps: a pedal manipulation mode; a hand wheel operating mode; and a swing reducing mode. When in a swing reducing state, the actuating cylinder and the electromagnetic valve are controlled to form a swing reducing loop, the front wheel encounters external force to generate swing vibration, the swing reducing loop can provide hydraulic damping, swing vibration energy is consumed, and the stability of plane sliding is ensured.
In the front wheel turning and swing reducing system of the airplane, the scheme for controlling the turning and swing reducing of the front wheels of the airplane mainly comprises a manual control and independent swing reducer, a mechanical-hydraulic front wheel turning and swing preventing system (comprising a turning and swing reducing booster), an electric front wheel turning and swing reducing system and the like. When the mechanical-hydraulic turning system is installed, the positions of all mechanical connection points, the pretightening force of the steel rope and other factors are considered, and the zero position of the system can be influenced due to poor adjustment. For a long time, the front wheel steering anti-swing system of the aircraft has a problem of front wheel deviation for a plurality of times, and the reason is that the mechanical-hydraulic front wheel steering anti-swing system used by the aircraft has an inherent fault mode, and the problem of front wheel deviation is necessarily caused under a certain specific condition. The mechanical-hydraulic front wheel turning anti-swing system integrates a reversing valve and a state switching valve into a part, so that the function authority of the reversing valve is not divided, turning and swing reducing oil ways are not divided, when the reversing valve does not return to the middle, a swing reducing state is entered, an actuating cylinder can form a dead cavity, the front wheel is in a locking state, and the swing reducing and braking deviation correcting functions are not performed; in addition, the mechanical-hydraulic front wheel steering anti-swing system is not provided with a swing-reducing oil return compensator, an oil supplementing valve, a safety valve, an oil return control valve and the like, and the safety valve is arranged in a loop in order to ensure the system safety when the unloading valve fails; the safety valve converts the passing hydraulic power of the oil into heat, so that the oil temperature is increased, the system performance is reduced, and the service life of the oil pump is seriously influenced. The swing reducing effect is poor, oil return is required to be completely cut off to achieve the swing reducing effect, and if the oil return is completely cut off for a long time, the pressure of the front wheel steering swing preventing system is possibly too high due to expansion caused by heat and contraction caused by cold, so that the safety of an airplane is affected.
Disclosure of Invention
Aiming at the defects of the existing mechanical-hydraulic front wheel turning anti-swing system, the invention aims to provide the mechanical-hydraulic front wheel turning anti-swing system for the aircraft, which has the advantages of quick response, large turning angle, high reliability and safety of the system, good maintainability, light weight, no interference between the turning and swing reducing functions of the front wheel of the aircraft, no matter whether a slide valve is in the middle of the turning or not, no locking of the front wheel is caused when the front wheel of the aircraft enters the swing reducing state.
The technical scheme adopted for solving the technical problems is as follows: a mechanical-hydraulic aircraft nose wheel steering anti-sway system comprising: the electromagnetic valve 1 which is communicated with the oil filter 2 and the one-way damping valve 3 and the closed-loop one-way valve parallel oil return R which is communicated with the hydraulic pipeline through the electromagnetic valve 1 are characterized in that: a closed-loop swing-reducing hydraulic circuit formed by an oil return anti-charge one-way valve 8 connected in parallel with two ends of an overflow valve 7 and a throttle valve 9 and a swing-reducing oil return compensator 10 connected with the throttle valve 9 in series with the overflow valve 7 in sequence are connected on a hydraulic pipeline between closed-loop one-way valves connected in parallel with the oil return R communicated with the electromagnetic valve 1, two ends of the closed-loop swing-reducing hydraulic circuit are respectively communicated with a one-way damping valve 3 and a reversing valve 6 through bypass hydraulic pipelines, and the one-way damping valve 3 and the reversing valve 6 are connected with a safety valve 5 in parallel through a state switching valve 4; when the electromagnetic valve 1 is electrified, high-pressure oil enters from an opening of the electromagnetic valve 1P, the high-pressure oil is divided into two paths, one path is sent to the state switching valve 4 through the oil filter 2 and flows into the reversing valve 6, and enters the safety valve 5 to control the front wheel turning actuator cylinder of the aircraft, so that the state switching valve 4 is in a left position function against the spring force of the state switching valve 4, at the moment, the reversing valve 6 is communicated with two cavities of the front wheel turning actuator cylinder of the aircraft, and the two cavities of the front wheel turning actuator cylinder of the aircraft are cut off by the unidirectional damping valve 3, and the front wheel of the aircraft is in a turning mode; the other path of the hydraulic oil enters a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of the electromagnetic valve 1 and enters a swing-reducing oil return compensator which ensures that the front wheel always keeps certain pressure to be full of oil before swing; when the electromagnetic valve 1 is powered off, high-pressure oil does not enter the oil filter 2 from the P port of the electromagnetic valve 1, one path enters the oil filter 2 to be communicated with the reversing valve 6, the other path enters the swing reducing oil return compensator through a pipeline connected by a closed-loop swing reducing hydraulic circuit, oil is filled in the combined valve and the front wheel steering actuating cylinder all the time in the swing reducing process, the swing reducing oil return circuit is communicated with the control circuit of the one-way damping valve 3, the state switching valve 4 is communicated, the reversing valve 6 and the two cavities of the front wheel steering actuating cylinder are cut off under the action of a spring by the state switching valve 4, the two cavities of the front wheel steering actuating cylinder are communicated with the one-way damping valve 3, and the front wheel of the aircraft is controlled to be in a swing reducing mode through the 5 safety valve.
Compared with the prior art, the invention has the following beneficial effects:
The invention adopts an electromagnetic valve 1 aiming at a double-actuating cylinder type front wheel steering system, high-pressure oil is divided into two paths, one path is sent into a state switching valve 4 through an oil filter 2 and a flow-in reversing valve 6, and enters a safety valve 5 to control an aircraft front wheel steering actuating cylinder, so that the state switching valve 4 is in a left position function against the spring force of the state switching valve 4, and the other path enters a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of the electromagnetic valve 1, and enters a swing-reducing oil return compensator which ensures that the front wheel always keeps certain pressure to be full of oil before shimmy; the multifunctional combined valve is realized by combining the front wheel steering actuator cylinder and the swing-reducing oil return compensator, so that the front wheel steering operation of the aircraft is required to be realized, and the reliable swing reduction of the front wheel of the aircraft is required to be met.
According to the invention, through the state switching valve which enables the turning oil way and the swing reducing oil way to be completely independent, the mutual interference of the oil ways is avoided, and the front wheel deviation fault is prevented in principle; in the process of reducing the swing, the closed-loop swing reducing hydraulic circuit integrated with the swing reducing oil return compensator supplements oil for the combination valve and the front wheel steering actuating cylinder, can independently provide enough damping for the swing reduction of the front wheel, can eliminate the front wheel shimmy caused by the ground impact load in the process of the ground running of the aircraft, and has good swing reducing property. The pendulum damping moment generated by the pendulum absorber increases with the increase of the pendulum frequency and the pendulum angle and decreases with the increase of the diameter of the damping hole. The multifunctional combined valve integrates a plurality of parts such as a reversing valve, a state switching valve, a damping valve, a swing-reducing oil return compensator and the like, and is combined with a front wheel turning actuator cylinder of an airplane, so that the turning of the front wheel of the airplane can be controlled, and damping can be provided for the swing reduction of the front wheel of the airplane. Simulation results show that the acceleration generated by the piston under the action of hydraulic impact is simulated to be within an acceptable range.
Drawings
Fig. 1 is a schematic diagram of the oil circuit control of the front wheel turning anti-swing system of the mechanical-hydraulic aircraft turning leftward (the piston rod of the actuator extends leftward).
Fig. 2 is a schematic diagram of the control of the oil passage for turning the front wheel rightward (extending the cylinder rod rightward) in fig. 1.
Fig. 3 is a schematic diagram of the control of the front wheel swing reducing oil circuit of the present invention.
In the figure: the oil return valve comprises a solenoid valve 1, an oil filter 2, a one-way damping valve 3, a state switching valve 4, a safety valve 5, a reversing valve 6, an overflow valve 7, an oil return reverse-charging one-way valve 8, a throttle valve 9 and an oil return compensator 10.
The invention will be further described with reference to the drawings and examples, without thereby restricting the invention to the scope of the examples. All such concepts should be considered as being generic to the disclosure herein and to the scope of the invention.
Detailed Description
See fig. 1-2. In the embodiments described below, a mechanical-hydraulic aircraft nose wheel steering anti-sway system comprises: the electromagnetic valve 1 which is communicated with the oil filter 2 and the one-way damping valve 3 and the closed-loop one-way valve parallel oil return R which is communicated with the hydraulic pipeline through the electromagnetic valve 1 are characterized in that: a closed-loop swing-reducing hydraulic circuit formed by an oil return anti-charge one-way valve 8 connected in parallel with two ends of an overflow valve 7 and a throttle valve 9 and a swing-reducing oil return compensator 10 connected with the throttle valve 9 in series with the overflow valve 7 in sequence are connected on a hydraulic pipeline between closed-loop one-way valves connected in parallel with the oil return R communicated with the electromagnetic valve 1, two ends of the closed-loop swing-reducing hydraulic circuit are respectively communicated with a one-way damping valve 3 and a reversing valve 6 through bypass hydraulic pipelines, and the one-way damping valve 3 and the reversing valve 6 are connected with a safety valve 5 in parallel through a state switching valve 4; the electromagnetic valve 1 divides high-pressure oil into two paths, one path is sent to the state switching valve 4 through the oil filter 2 through the inflow reversing valve 6, enters the safety valve 5 to control the front wheel turning actuator cylinder of the aircraft, overcomes the spring force of the state switching valve 4, enables the state switching valve 4 to be in a left-position function, at the moment, the reversing valve 6 is communicated with two cavities of the front wheel turning actuator cylinder of the aircraft, and the two cavities of the front wheel turning actuator cylinder of the aircraft are cut off by the one-way damping valve 3, so that the front wheel of the aircraft is in a turning mode; the other path of the hydraulic oil enters a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of the electromagnetic valve 1 and enters a swing-reducing oil return compensator which ensures that the front wheel always keeps certain pressure to be full of oil before swing; when the electromagnetic valve 1 is powered off, high-pressure oil does not enter the oil filter 2 from the P port of the electromagnetic valve 1, one path enters the oil filter 2 to be communicated with the reversing valve 6, the other path enters the swing reducing oil return compensator through a pipeline connected by a closed-loop swing reducing hydraulic circuit, the combined valve and the front wheel steering cylinder are ensured to be always filled with oil in the swing reducing process, the swing reducing oil return circuit is communicated with the control circuit of the one-way damping valve 3, the state switching valve 4 is communicated, the reversing valve 6 and the two cavities of the front wheel steering cylinder are cut off under the action of a spring by the state switching valve 4, the two cavities of the front wheel steering cylinder are communicated with the one-way damping valve 3, and the front wheel of the aircraft is controlled to be in a swing reducing mode through the safety valve 5 to complete the turning of the double-actuation cylinder front wheel.
When the front wheel of the aircraft reduces the swing, the combined valve and the front wheel steering actuating cylinder together form a hydraulic damper, and the key point of whether the hydraulic damper can normally play a damping role is whether the combined valve and the front wheel steering actuating cylinder are always filled with oil without generating air pockets; the swing-reducing oil return compensator is a spring-loaded accumulator, and keeps the pressure of an oil return pipeline of the turning system at 0.15MPa. The front wheel is ensured to be always full of oil and has certain pressure before shimmy through the one-way valve; in the swing reducing process, when the pressure of a hydraulic system is higher than 5MPa, an overflow valve 7 connected in series between a swing reducing oil return compensator 10 and a reversing valve 6 is opened, oil in the system is allowed to enter an oil return tank, the pressure is lower than 0.3MPa, the swing reducing oil return compensator 10 is connected in parallel with an oil return anti-charge check valve 8 on a closed-loop swing reducing hydraulic circuit at two ends of the overflow valve 7 and a throttle valve 9 through a closed-loop swing reducing hydraulic circuit, and the pressure is supplemented into the system; when the pressure of the hydraulic system rises to a certain set pressure value (10% -20% higher than normal), the safety valve (overflow valve) is opened to discharge redundant liquid flow out of the oil return tank, and the pressure of the system is limited to continuously rise, so that the overflow valve and the swing-reducing oil return compensator together achieve the function of pressure maintenance. The system pressure is highest when the safety valve is opened, and the output power of the hydraulic pump is largest; and in the non-working state of the system, the oil pump is started at intervals of two times. Depending on how much oil the anti-roll oil compensator can supplement and how much oil is leaking per unit time during unloading. The utility of the swing-reducing oil return compensator is used for filling the system leakage, maintaining the pressure of the system to reduce pressure fluctuation, preventing hydraulic impact from providing instantaneous large flow, assisting oil supply to meet the pressure and power requirements of multiple components in working and providing limited flow as an emergency hydraulic source, and when the pressure in the hydraulic system is lower than the pressure set by the swing-reducing oil return compensator, the swing-reducing oil return compensator can supplement the pressure in the system, maintaining the pressure in the system not lower than the set minimum value, and avoiding cavitation. When the pressure of the closed-loop swing-reducing hydraulic circuit is lower than the opening pressure of the swing-reducing oil return compensator, the closed-loop swing-reducing hydraulic circuit is opened, and the swing-reducing oil return compensator is allowed to supplement oil into the system, namely the system can effectively prevent cavitation. If the shimmy frequency is too high, the shimmy reducing loop generates negative pressure, and the shimmy reducing oil return compensator 10 supplements oil to the combined valve and the front wheel steering actuating cylinder through the closed-loop shimmy reducing hydraulic loop, supplements pressure at any time, and ensures the damping characteristic of the loop so as to prevent oil in the damping oil path from being extruded into the oil tank to generate cavitation. In addition, when the oil pressure in the front wheel turning actuator cylinder is lower than the pressure of the closed-loop swing-reducing hydraulic circuit, the swing-reducing oil return compensator 10 can be used for supplementing oil to the booster oil tank to the combination valve and the front wheel turning actuator cylinder, so that the combination valve and the front wheel turning actuator cylinder are always filled with oil in the swing-reducing process without generating air pockets, and the purpose of damping swing reduction is achieved.
See fig. 3. When the electromagnetic valve 1 is electrified, high-pressure oil enters from an opening of the electromagnetic valve 1P, the high-pressure oil is divided into two paths, one path is sent to the state switching valve 4 through the oil filter 2 and flows into the reversing valve 6, and enters the safety valve 5 to control the front wheel turning actuator cylinder of the aircraft, so that the state switching valve 4 is in a left position function against the spring force of the state switching valve 4, at the moment, the reversing valve 6 is communicated with two cavities of the front wheel turning actuator cylinder of the aircraft, and the two cavities of the front wheel turning actuator cylinder of the aircraft are cut off by the unidirectional damping valve 3, and the front wheel of the aircraft is in a turning mode; the other path of the hydraulic oil enters a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of the electromagnetic valve 1 and enters a swing-reducing oil return compensator 10 which ensures that the front wheel always keeps certain pressure to be full of oil before swing; when the electromagnetic valve 1 is powered off, high-pressure oil does not enter the oil filter 2 from the P port of the electromagnetic valve 1, one path enters the oil filter 2 to be communicated with the reversing valve 6, the other path enters the swing reducing oil return compensator 10 through a pipeline connected by a closed-loop swing reducing hydraulic circuit, the combined valve and the front wheel steering actuating cylinder are ensured to be always filled with oil in the swing reducing process, the swing reducing oil return circuit is communicated with the control circuit of the one-way damping valve 3, the state switching valve 4 is communicated, the reversing valve 6 and the two cavities of the front wheel steering actuating cylinder are cut off under the action of a spring by the state switching valve 4, the two cavities of the current wheel steering actuating cylinder are communicated with the one-way damping valve 3, and the front wheel of the aircraft is controlled to be in a swing reducing mode through the 5 safety valve.
The key point of whether the damping function can be normally achieved is whether the combined valve and the front wheel steering actuating cylinder can be always filled with oil without generating air pockets, and for this purpose, the swing-reducing oil return compensator 10 is provided with a one-way valve with two ends connected in parallel, and the front wheel is always kept full of oil and has a certain pressure before swing and vibration through the one-way valve. The closed-loop swing-reducing hydraulic circuit includes: the oil return channel bypass oil path between the electromagnetic valve 1 and the swing reducing oil return compensator 10 is connected with the overflow valve 7 and the throttle valve 9 which are connected in series between the swing reducing oil return compensator 10 and the reversing valve 6, and the oil return anti-charge check valve 8 which is connected with the closed loop oil return path at two ends of the overflow valve 7 and the throttle valve 9 in parallel. In the process of the swing reduction, the swing reduction oil return compensator 10 supplements oil to the combined valve and the front wheel steering actuating cylinder through the closed-loop swing reduction hydraulic circuit so as to prevent oil in the damping oil path from being extruded into the oil return tank to generate air pockets. In addition, when the oil pressure in the front wheel turning actuator cylinder is lower than the pressure of the closed-loop swing-reducing hydraulic circuit, the swing-reducing oil return compensator 10 can be used for supplementing oil to the booster oil tank to the combination valve and the front wheel turning actuator cylinder, so that the combination valve and the front wheel turning actuator cylinder are always filled with oil in the swing-reducing process without generating air pockets, and the purpose of damping swing reduction is achieved.
While the foregoing is directed to the preferred embodiment of the present invention, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (10)
1. A mechanical-hydraulic aircraft nose wheel steering anti-sway system comprising: the electromagnetic valve (1) is communicated with the oil filter (2) and the one-way damping valve (3), and the closed-loop one-way valve on the hydraulic pipeline is communicated with the electromagnetic valve (1) to form an oil return R in parallel, and the hydraulic pipeline is characterized in that: a closed-loop swing-reducing hydraulic circuit formed by connecting an overflow valve (7) and return oil reverse-charging check valves (8) at two ends of a throttle valve (9) in parallel and a swing-reducing oil return compensator (10) connected with the overflow valve (7) in series in sequence are connected on a hydraulic pipeline between closed-loop check valves connected with the electromagnetic valve (1) in parallel, two ends of the closed-loop swing-reducing hydraulic circuit are respectively communicated with a check damping valve (3) and a reversing valve (6) through a bypass hydraulic pipeline, and the check damping valve (3) and the reversing valve (6) are connected with a safety valve (5) in parallel through a state switching valve (4); when the electromagnetic valve (1) is electrified, high-pressure oil enters from a P port of the electromagnetic valve (1), the high-pressure oil is divided into two paths, one path is sent into the state switching valve (4) through the oil filter (2) through the inflow reversing valve (6), the state switching valve (4) is controlled by the safety valve (5) to overcome the spring force of the state switching valve (4) to enable the state switching valve (4) to be in a left-hand function, at the moment, the reversing valve (6) is communicated with two cavities of the front-wheel turning actuator of the aircraft, and the two cavities of the front-wheel turning actuator of the aircraft are cut off by the one-way damping valve (3), and the front wheel of the aircraft is in a turning mode; the other path of the hydraulic oil enters a closed-loop swing-reducing hydraulic loop connected by a hydraulic pipeline of an electromagnetic valve (1) and enters a swing-reducing oil return compensator which ensures that the front wheel always keeps certain pressure to be full of oil before swing; when the electromagnetic valve (1) is powered off, high-pressure oil does not enter the oil filter (2) from the P port of the electromagnetic valve (1), one path enters the oil filter (2) to be communicated with the reversing valve (6), the other path enters the swing reducing oil return compensator through a pipeline connected with the side of the closed-loop swing reducing hydraulic circuit, the combined valve and the front wheel steering actuator cylinder are ensured to be always filled with oil in the swing reducing process, the combined valve and the front wheel steering actuator cylinder are communicated with the control circuit of the one-way damping valve (3) through the swing reducing oil return circuit, the state switching valve (4) is communicated, the reversing valve (6) and the two cavities of the front wheel steering actuator cylinder are cut off under the action of a spring, and the two cavities of the front wheel steering actuator cylinder are communicated with the one-way damping valve (3), and the front wheel of the aircraft is controlled to be in a swing reducing mode through the safety valve (5).
2. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 1, wherein: when the front wheel of the aircraft is reduced in swing, the combined valve and the front wheel steering cylinder form a hydraulic damper together, and a swing reducing oil return compensator (10) is arranged on an oil return channel of the combined valve.
3. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 2, wherein: the wobble-reducing oil return compensator (10) is a spring-loaded accumulator.
4. A mechanical-hydraulic aircraft nose wheel steering anti-sway system according to claim 3, characterized in that: the front wheel is ensured to be always full of oil and has certain pressure before shimmy through the one-way valve.
5. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 1, wherein: in the swing reducing process, when the pressure of the hydraulic system is higher than 5MPa, an overflow valve (7) connected in series between the swing reducing oil return compensator (10) and the reversing valve (6) is opened, so that oil in the system is allowed to enter the oil return tank.
6. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 5, wherein: the pressure is lower than 0.3MPa, the swing-reducing oil return compensator (10) is connected with the oil return reverse-charging check valve (8) of the closed-loop swing-reducing hydraulic circuit at the two ends of the overflow valve (7) and the throttle valve (9) in parallel through the closed-loop swing-reducing hydraulic circuit, and the pressure is supplemented into the system by opening; when the pressure of the hydraulic system is increased and is higher than the normal set pressure value of 10% -20%, the overflow valve (7) is opened to drain the redundant liquid flow out of the oil return tank, and the pressure of the system is limited to continuously increase.
7. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 6, wherein: when the pressure of the loop where the closed-loop swing-reducing hydraulic loop is positioned is lower than the opening pressure of the swing-reducing oil return compensator (10), the closed-loop swing-reducing hydraulic loop is opened, the swing-reducing oil return compensator (10) is allowed to supplement oil into the system, if the swing vibration frequency is too high, the swing-reducing loop generates negative pressure, the swing-reducing oil return compensator (10) supplements oil to the combined valve and the front wheel steering actuating cylinder through the closed-loop swing-reducing hydraulic loop, the pressure is supplemented at any time, and the damping characteristic of the loop is ensured.
8. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 1, wherein: the closed-loop swing-reducing hydraulic circuit includes: the oil return channel side oil path between the electromagnetic valve 1 and the swing reducing oil return compensator (10) is connected with the overflow valve (7) and the throttle valve (9) which are connected in series between the swing reducing oil return compensator (10) and the reversing valve (6), and the oil return anti-charging check valve (8) which is connected with the closed loop oil return path at two ends of the overflow valve (7) and the throttle valve (9) in parallel.
9. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 8, wherein: in the process of the swing reduction, the swing reduction oil return compensator (10) supplements oil for the combined valve and the front wheel steering actuating cylinder through the closed-loop swing reduction hydraulic circuit so as to prevent oil in the damping oil path from being extruded into the oil tank to generate air pockets.
10. The mechanical-hydraulic aircraft nose wheel steering anti-sway system of claim 1, wherein: when the oil pressure in the front wheel turning actuator cylinder is lower than the pressure of the closed-loop swing-reducing hydraulic circuit, the swing-reducing oil return compensator (10) supplements oil to the pressurizing oil tank to the combination valve and the front wheel turning actuator cylinder.
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| CN112572827B (en) * | 2020-12-04 | 2023-04-14 | 中国航空工业集团公司成都飞机设计研究所 | Zero correction method for aircraft nose wheel turning |
| CN113104201B (en) * | 2021-04-30 | 2023-06-20 | 山东大学 | Airplane front wheel steering system and civil branch airplane |
| CN115817806A (en) * | 2022-12-16 | 2023-03-21 | 北京特种机械研究所 | Hydraulic servo pump controlled airplane brake turning and swing reduction integrated method |
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| CN211281453U (en) * | 2019-12-12 | 2020-08-18 | 四川凌峰航空液压机械有限公司 | Hydraulic swing-reducing oil circuit system for turning front wheels of airplane |
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| JPH08258532A (en) * | 1995-03-24 | 1996-10-08 | Mitsubishi Motors Corp | Damping force controller |
| CN105564639A (en) * | 2014-10-11 | 2016-05-11 | 中国航空工业集团公司西安飞机设计研究所 | Dual-redundancy nose-wheel steering and shimmy-damping system |
| CN105905284B (en) * | 2016-04-28 | 2019-03-01 | 江西洪都航空工业集团有限责任公司 | The anti-oscillator system of Nose Wheel Steering with middling speed deviation-correcting function |
| CN109268349B (en) * | 2018-11-23 | 2020-09-18 | 北京精密机电控制设备研究所 | Dual-redundancy hydraulic actuator with single-end mechanical lock |
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| CN211281453U (en) * | 2019-12-12 | 2020-08-18 | 四川凌峰航空液压机械有限公司 | Hydraulic swing-reducing oil circuit system for turning front wheels of airplane |
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