Airplane brake system and control method for controlling brake pressure by brake handle

Abstract

An aircraft brake system and control method for controlling brake pressure through a brake handle, the brake handle is combined with an electric control brake handle, the brake handle angle rotation transmits the brake intention of the pilot, the working displacement of the handle is converted into a current signal received by the control unit through an electric control unit, so as to realize the wheel brake. During the brake process, the pilot can correct the brake instruction in time to ensure the stability of the aircraft heading during braking. The rotation angle of the brake handle collected by the angle displacement sensor is converted into a voltage signal through a signal conversion circuit, and then the received voltage signal is converted into a direct current signal to the pressure servo valve; the signal conversion circuit outputs a direct current voltage signal to control the hydraulic electromagnetic valve to open, so that the pressure servo valve is connected to the hydraulic source; the pressure servo valve outputs brake pressure proportional to the handle rotation angle. The pressure sensor receives the signal and connects the wheel to realize the brake, which has the characteristics of short reaction time, low failure rate and high reliability.

Description

Technical Field

[0001] This invention relates to the field of aircraft wheel braking systems, specifically an aircraft braking system and control method that controls the output of braking pressure by rotating the brake handle. Background Technology

[0002] Invention publication CN112693601A discloses an aircraft braking system that, through the combined action of a dynamic brake piston and a static brake piston, meets the static braking requirements of an aircraft under conditions of constant static friction coefficient of the brake disc and constant static braking pressure. In invention publication CN103818550B, Harbin Aircraft Industry Group discloses an aircraft hydraulic brake and nose wheel steering mechanism. When braking the aircraft wheels, the brake pedal is placed in the depressed position, and the pressure stored in the brake accumulator pushes the brake wheels to brake through the brake distribution valve, anti-slip solenoid valve, and anti-slip throttle valve.

[0003] Xi'an Aviation Braking Technology Co., Ltd. proposed an aircraft hydraulic braking system in its invention patent publication number CN104773287B, which uses a hydraulic system in conjunction with a foot pedal mode to control the hydraulic brake valve, hydraulic control switching valve, electro-hydraulic servo valve, and other brake control units. In its invention patent publication number CN104760692B, limit switches and electric valves are added to the hydraulic control system, still using a foot pedal mode. The hydraulic brake valve is installed near the foot pedal mechanism under the cockpit floor, and the anti-slip control box is installed inside the main landing gear bay. The electric valve is controlled by a limit switch and is installed on the hydraulic line downstream of the hydraulic brake valve. The electro-hydraulic servo valve is installed on the hydraulic line downstream of the electric valve.

[0004] Currently, the braking systems of large aircraft both domestically and internationally primarily use foot-operated controls. Aircraft such as the ARJ21 and EMB-190 employ a stop / emergency brake lever for emergency braking, and these aircraft utilize mechanical controls. Airbus aircraft, such as the A320, A330, A340, and A380, have separate normal and backup braking systems. The backup braking system uses fly-by-wire controls and anti-skid functionality, and the two systems are independent of each other or separated before a switching valve, using foot-operated brake pedals.

[0005] A typical schematic diagram of a brake pedal-type braking system can be found here. Figure 1 The system consists of a foot pedal (1), a brake command sensor (2), a brake control box (3), a hydraulic solenoid valve (4), a pressure servo valve (5), a pressure sensor (6), a wheel speed sensor (7), and wheels (8). The brake command sensor (2), brake control box (3), hydraulic solenoid valve (4), pressure servo valve (5), and pressure sensor (6) enable the aircraft's braking function, while the brake control box (3), pressure servo valve (5), and wheel speed sensor (7) enable the aircraft's anti-skid function.

[0006] Brake command sensor 2 is connected to the aircraft's brake pedal 1. When the pilot performs braking operations, pressing the brake pedal on the brake pedal moves brake command sensor 2 connected to brake pedal 1. Brake command sensor 2 outputs a DC voltage signal proportional to the travel of brake pedal 1 to brake control box 3. Brake control box 3 outputs a DC voltage signal to control hydraulic solenoid valve 4 to open, thus connecting pressure servo valve 5 to the hydraulic power source. Simultaneously, brake control box 3 outputs brake control current to pressure servo valve 5, causing pressure servo valve 5 to output brake pressure proportional to the control current for braking.

[0007] Existing foot-operated braking systems require the pilot to press a pedal to apply the brakes. The brake pedal is located below the cockpit control panel, and the pilot can only feel the braking distance through the pressure applied to the pedal; they cannot directly visually inspect the pedal's movement. Foot-operated braking systems are mostly mechanical, and mechanical emergency braking systems typically use cable connections, resulting in significant weight and lower reliability. Furthermore, mechanical emergency braking systems are complex to install, have a cumbersome structure, and are difficult to maintain, making aircraft maintenance time-consuming and labor-intensive for maintenance personnel. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies where pilots cannot directly visually inspect the brake control mechanism, this invention proposes an aircraft anti-skid braking system and control method that controls brake pressure via a brake handle.

[0009] This invention proposes an aircraft braking system that controls brake pressure via a brake handle, comprising a brake handle, an angular displacement sensor, a signal conversion circuit, a hydraulic solenoid valve, a pressure servo valve, a pressure sensor, a wheel speed sensor, and wheels. The brake handle is mounted on the cockpit control panel, directly visible to the pilot. The angular displacement sensor is fixed to the rotating shaft of the brake handle, detecting the angle of rotation and outputting it as an AC voltage signal to the signal conversion circuit. The DC power input interface of the signal conversion circuit is connected to a regulated power supply. The hydraulic solenoid valve and the pressure servo valve are connected to the signal conversion circuit according to their interface definitions. The hydraulic inlet of the hydraulic solenoid valve is connected to the onboard hydraulic input source, and its hydraulic outlet is connected to the hydraulic inlet of the pressure servo valve to control the on / off state of the pressure servo valve's oil circuit. The wheel braking device includes a pressure sensor, a wheel speed sensor, and wheels; the pressure sensor and wheel speed sensor are respectively mounted on both sides of the wheels. The hydraulic outlet of the pressure servo valve is connected to the wheel braking device, outputting brake pressure to it. The angular displacement sensor converts the displacement of the handle rotation angle into an AC voltage, which is then output to the signal conversion circuit.

[0010] The signal conversion circuit receives the voltage signal caused by the handle displacement signal through a connector. Simultaneously, the power module is turned on, connecting the detection signal generator, the rheostat, and the conversion module. The analog switch receives and determines the voltage signal transmitted from the detection signal generator, then forms a feedback loop with the rheostat before outputting a voltage signal to the conversion module. The conversion module converts the voltage signal into a current signal and outputs it through the connector.

[0011] The signal conversion circuit includes a power converter, an angular displacement sensor exciter, an RMS converter, a proportional amplifier, and a voltage-to-current converter. Specifically, the signal conversion circuit converts the received power into two paths, with one path outputting 28V DC to power the pressure servo valve drive circuit, and the other path outputting +15V and -15V to the power conversion module as the driving voltage for its internal components.

[0012] The angular displacement sensor exciter is powered by the internal drive voltage of the conversion circuit. After being conditioned by the AD598 linear displacement differential transformer signal conditioning chip, it outputs a 7Vrms AC effective voltage and provides a 2400Hz excitation source for the angular displacement sensor.

[0013] The RMS converter collects the output signal from the angular displacement sensor and converts it into a 0–3.75V voltage signal. This voltage signal is then amplified by a proportional amplifier to a 0–8V voltage, and finally outputs a 0–40mA current by a voltage-to-current conversion circuit.

[0014] The primary coil has a resistance of 45±9Ω, and the secondary coil has a resistance of 55±10Ω. The voltage signal output by the angular displacement sensor is 0~3.75Vrms.

[0015] The AC voltage signal command signal from the angular displacement sensor is converted into a DC control current signal of 0-40mA for the pressure servo valve through a signal conversion circuit, thereby controlling the pressure servo valve to brake.

[0016] The pressure servo valve has a control current input range of 0-40mA and a resistance of 100Ω.

[0017] The specific process of controlling brake pressure via a brake lever, as proposed in this invention, is as follows:

[0018] Step 1: Determine the strokes of the angular displacement sensor:

[0019] The angular displacement sensor's stroke includes total stroke, idle stroke, and working stroke. During braking, the angular displacement sensor receives continuous changes in the brake lever angle to determine the sensor's total stroke, idle stroke, and working stroke.

[0020] When the angular displacement sensor is in its no-stroke state, the signal conversion circuit does not output an open signal to the hydraulic solenoid valve, the hydraulic power source cannot enter the oil inlet of the pressure servo valve, and at the same time, the signal conversion circuit only outputs static current to the pressure servo valve and does not output control current. At this time, the braking system does not output braking pressure, and the angular displacement sensor is in its no-stroke state.

[0021] When the angular displacement sensor is determined to be in its working stroke, the signal conversion circuit outputs control signals to the hydraulic solenoid valve and the brake servo valve. At this time, the hydraulic power source enters the inlet of the pressure servo valve, and the pressure servo valve outputs a braking pressure proportional to the handle rotation angle. This angular displacement sensor is in its working stroke. The braking system then completes its normal braking function.

[0022] The total travel of the angular displacement sensor is the sum of the idle travel and the working travel.

[0023] When the driver applies the emergency brake and pulls the brake lever, the angular displacement sensor detects the change in the angle of the brake lever and generates an AC voltage signal, which is transmitted to the signal conversion circuit. The conversion circuit converts this signal into a DC current signal, which controls the pressure servo valve to output a braking pressure proportional to the lever rotation angle to achieve emergency braking.

[0024] Step 2: Determine the working logic of the hydraulic solenoid valve:

[0025] The working logic of the hydraulic solenoid valve includes no-stroke logic and working stroke logic.

[0026] The angle signal of the brake lever is converted into a voltage signal to determine the opening logic of the hydraulic solenoid valve.

[0027] The specific process for determining the working logic of a hydraulic solenoid valve is as follows:

[0028] The logic for controlling the opening of the hydraulic solenoid valve by the output signal of the angular displacement sensor is determined by formula (1).

[0029]

[0030] In the formula, S represents the state where the angular displacement sensor triggers the hydraulic solenoid valve to open; 1 indicates the hydraulic solenoid valve is open, and the hydraulic power source enters the inlet of the pressure servo valve; 0 indicates the hydraulic solenoid valve is not open, and the hydraulic power source does not enter the inlet of the pressure servo valve; R S This refers to the working stroke of the angular displacement sensor; R S0 This is the idle travel of the angular displacement sensor.

[0031] The logic for a defined empty run is 0, and the logic for a defined working run is 1.

[0032] Step 3: Determine the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve:

[0033] The voltage signal output by the angular displacement sensor is processed by a conversion circuit and converted into a brake current signal, which is then output to the pressure servo valve.

[0034] When determining the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve, the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve is determined by formula (2).

[0035]

[0036] In the formula I f It is the current input of the pressure servo valve; V S It is the working stroke voltage of the angular displacement sensor; V S0 K1 is the no-travel voltage of the angular displacement sensor; K2 is the conversion coefficient between the output signal of the angular displacement sensor and the input current signal of the pressure servo valve.

[0037] Step 4: Determine the relationship between the input current and output pressure of the pressure servo valve:

[0038] The relationship between the input current and the output pressure of the pressure servo valve is determined by formula (3).

[0039]

[0040] In the formula, P is the output pressure of the pressure servo valve; P0 is the return oil pressure of the brake system; I f0 K1 is the dead zone current of the pressure servo valve; K2 is the current gain coefficient of the pressure servo valve.

[0041] Step 5: Apply the brakes:

[0042] Based on the correspondence between the input current and output pressure of the pressure servo valve determined in step 4, the pressure servo valve outputs braking pressure, which is reflected by the rotation angle of the handle. The pressure sensor receives the signal and connects to the wheel to achieve braking, thus completing the normal braking function of the braking system.

[0043] This completes the entire process of controlling the aircraft's braking system via the brake lever.

[0044] The system schematic diagram of this invention is shown below. Figure 2The brake lever transmits the pilot's braking intention through angular rotation. The brake lever can be mounted on the cockpit control panel, allowing the pilot to directly observe its movement. An angular displacement sensor is fixed to the brake lever's rotating shaft. When the brake lever rotates, the sensor outputs an AC voltage signal proportional to the lever's rotation angle to a signal conversion circuit. This circuit converts the received AC voltage signal into a DC current signal, which is then sent to the pressure servo valve. Simultaneously, the circuit outputs a DC voltage signal to control the hydraulic solenoid valve to open, connecting the pressure servo valve to the hydraulic power source. The pressure servo valve then outputs a braking pressure proportional to the lever's rotation angle. The pressure sensor receives the signal and connects to the wheels to achieve braking, thus completing the normal braking function of the braking system.

[0045] This invention employs a brake handle combined with an electronically controlled brake operating unit to meet the usage requirements of braking systems. The electronically controlled brake operating unit consists of a brake handle, an angular displacement sensor, a signal conversion circuit, a hydraulic solenoid valve, a pressure servo valve, a pressure sensor, a wheel speed sensor, and wheels, utilizing more reliable control circuits and components. During use, monitoring the functionality of the circuit components in the braking system is more convenient than with traditional hydraulic structures, enabling timely detection and effectively reducing the failure rate.

[0046] Compared with existing technologies, the improvement of this invention lies in that the pilot transmits the braking intention by manipulating the angle of the brake lever, and the electronic control unit converts the working displacement of the lever into a current signal that the control unit can receive, thereby realizing wheel braking. The brake lever is installed on the cockpit control panel, allowing the pilot to directly observe its movement. With foot-operated braking systems, the pilot can only feel the magnitude of the braking command through the force of the foot pedal mechanism, and cannot directly visually correct the braking command, which can easily cause instability in the aircraft's heading during braking. This invention allows the pilot to intuitively feel the movement of the brake control mechanism during braking operations, and can promptly correct the braking command through visual inspection, ensuring the stability of the aircraft's heading during braking. An angular displacement sensor is fixed on the rotating shaft of the brake lever; when the brake lever rotates, the angular displacement sensor outputs an AC voltage signal proportional to the rotation angle of the brake lever to the signal conversion circuit; the signal conversion circuit converts the received AC voltage signal into a DC current signal for the pressure servo valve; simultaneously, the signal conversion circuit outputs a DC voltage signal to control the hydraulic solenoid valve to open, connecting the pressure servo valve to the hydraulic source; the pressure servo valve outputs a braking pressure proportional to the rotation angle of the lever. The pressure sensor receives a signal, connects to the wheel to brake, and the braking system completes its normal braking function. Attached Figure Description

[0047] Figure 1 This is a block diagram of the foot-operated braking system.

[0048] Figure 2 This is a block diagram of the braking system principle of the present invention.

[0049] Figure 3 This is a structural diagram of the braking system of the present invention.

[0050] Figure 4 This is the signal conversion circuit diagram of the present invention.

[0051] Figure 5 It is a method of controlling brake pressure using a brake lever.

[0052] In the diagram: 1. Foot pedal; 2. Brake command sensor; 3. Brake control box; 4. Hydraulic solenoid valve; 5. Pressure servo valve; 6. Pressure sensor; 7. Wheel speed sensor; 8. Wheel; 9. Brake handle; 10. Angular displacement sensor; 11. Signal conversion circuit; 12. Connector; 13. Power module; 14. Detection signal generator; 15. Rheostat; 16. Analog switch; 17. Conversion module. Detailed Implementation

[0053] This invention is an improved digital electric fly-by-wire anti-skid braking system based on existing technology. The braking system structure diagram is shown below. Figure 3 As shown, it includes a brake handle 9, an angular displacement sensor 10, a signal conversion circuit 11, a hydraulic solenoid valve 4, a pressure servo valve 5, a pressure sensor 6, a wheel speed sensor 7, and a wheel 8.

[0054] The brake handle 9 is mounted on the cockpit control panel, which is directly visible to the pilot. An angular displacement sensor 10 is fixed to the rotating shaft of the brake handle 9, which is the object of the pilot's braking operation. The angular displacement sensor 10 detects the rotation angle of the handle and transmits the detected rotation angle signal to the signal conversion circuit 11. The DC power input interface of the signal conversion circuit is connected to a regulated power supply. The hydraulic solenoid valve 4 and the pressure servo valve are connected to the signal conversion circuit according to their interface definitions. The hydraulic inlet of the hydraulic solenoid valve 4 is connected to the onboard hydraulic input source, and the hydraulic outlet of the hydraulic solenoid valve 4 is connected to the hydraulic inlet of the pressure servo valve 5 to control the opening and closing of the oil circuit of the pressure servo valve 5. The wheel braking device includes a pressure sensor 6, a wheel speed sensor 7, and a wheel 8; the pressure sensor and wheel speed sensor are respectively mounted on both sides of the wheel. The hydraulic outlet of the pressure servo valve 5 is connected to the wheel braking device, outputting braking pressure to the wheel braking device.

[0055] The angular displacement sensor 10 adopts existing technology and includes a rotor, a stator, a primary coil, and two secondary coils.

[0056] An angular displacement sensor is an electromagnetic device that utilizes the principle of a differential transformer. It mainly consists of a stator and a rotor, with the rotor rotating inside the stator. Different rotation angles generate different induced electromotive forces, resulting in different output voltage signals. A primary coil and two secondary coils are wound in parallel on the inner surface of the stator, with the primary and secondary coils wound in opposite directions. The two secondary coils are connected in series with opposite polarities. When a certain AC voltage is applied to the primary coil, an induced voltage is generated in the secondary coil, the magnitude of which is proportional to the angular displacement of the rotor relative to the stator. When the rotor is in the middle position of the secondary coils, the induced voltages in the two secondary coils are equal but opposite in phase, and the total output is zero. When the rotor deviates from the middle position, due to the unequal induced voltages in the two coils, the difference in the secondary output is not zero and increases with the angular displacement. When the rotor rotates from the middle position to both sides, the phase change of the secondary output voltage is 180°. The angular displacement sensor described in this article has an excitation voltage signal of 7Vrms, 2400Hz, a primary coil resistance of 4592Ω, a secondary coil resistance of 55±102Ω, and an output signal of 0~3.75Vrms.

[0057] The angular displacement sensor converts the displacement amount from the handle's rotation angle into an AC voltage output to the signal conversion circuit. This circuit powers other electrical equipment within the system; one path provides 28V DC to the pressure servo valve drive circuit, and the other path provides a 7Vrms, 2400Hz excitation source to the angular displacement sensor. The signal conversion circuit then converts the AC voltage command signal from the angular displacement sensor into a 0-40mA DC control current signal for the pressure servo valve, controlling the valve to brake.

[0058] The signal conversion circuit splits the received power supply into two paths, with one path outputting 28V DC to power the pressure servo valve drive circuit, and the other path providing 7Vrms and a 2400Hz excitation source to the angular displacement sensor. The signal conversion circuit powers all electrical components within the conversion module, including the power converter, angular displacement sensor exciter, RMS converter, proportional amplifier, and voltage-to-current converter. The signal conversion circuit converts the AC voltage command signal from the angular displacement sensor into a 0-40mA DC control current signal for the pressure servo valve, controlling the pressure servo valve to brake.

[0059] Signal conversion circuit diagram as follows Figure 4 As shown. The signal conversion circuit receives the handle displacement signal through connector 12, and the power module 13 is turned on simultaneously, connecting the detection signal generator 14, the rheostat 15, and the conversion module 17. After the analog switch 16 judges the signal, it forms a feedback loop with the rheostat 15 and outputs a signal to the conversion module 17. The conversion module then outputs the current signal through connector 12.

[0060] The signal conversion circuit mainly consists of five components: a power converter, an angular displacement sensor exciter, an RMS converter, a proportional amplifier, and a voltage-to-current converter. The signal conversion circuit is powered by an external 28V DC power supply. After conversion by the internal power converter, one path outputs 28V DC to power the pressure servo valve drive circuit, and the other path outputs +15V and -15V internal drive voltages via the power conversion module. The angular displacement sensor exciter is powered by the internal drive voltage of the power converter. After conditioning by the AD598 linear displacement differential transformer signal conditioning chip, it outputs 7Vrms at 2400Hz to provide the excitation source for the angular displacement sensor. The RMS converter samples the output signal from the angular displacement sensor and converts it into a 0–3.75V voltage signal. This 0–3.75V voltage is then amplified by the proportional amplifier to a 0–8V voltage. Finally, the 0–8V voltage is converted by the voltage-to-current converter to output a 0–40mA current.

[0061] The pressure servo valve outputs a proportional braking pressure based on the magnitude of the braking control current input to the signal conversion circuit, thus controlling the pressure output. In this example, the pressure servo valve has a control current input range of 0–40 mA and a resistance of 100 Ω.

[0062] The pressure servo valve outputs braking pressure proportional to the rotation angle of the brake lever. The pressure sensor receives the signal, connects to the wheels to activate the brakes, and the braking system completes its normal braking function. This completes the process of controlling the aircraft braking system via the brake lever.

[0063] The control process of the braking system proposed in this invention is as follows:

[0064] Step 1: Determine the strokes of the angular displacement sensor:

[0065] The angular displacement sensor's stroke includes total stroke, idle stroke, and working stroke. During braking, the angular displacement sensor receives continuous changes in the brake lever angle to determine the sensor's total stroke, idle stroke, and working stroke.

[0066] When the angular displacement sensor is in its no-stroke state, the signal conversion circuit does not output an open signal to the hydraulic solenoid valve, the hydraulic power source cannot enter the oil inlet of the pressure servo valve, and at the same time, the signal conversion circuit only outputs static current to the pressure servo valve and does not output control current. At this time, the braking system does not output braking pressure, and the angular displacement sensor is in its no-stroke state.

[0067] When the angular displacement sensor is determined to be in its working stroke, the signal conversion circuit outputs control signals to the hydraulic solenoid valve and the brake servo valve. At this time, the hydraulic power source enters the inlet of the pressure servo valve, and the pressure servo valve outputs a braking pressure proportional to the handle rotation angle. This angular displacement sensor is in its working stroke. The braking system then completes its normal braking function.

[0068] The total travel of the angular displacement sensor is the sum of the idle travel and the working travel.

[0069] When the driver applies the emergency brake and pulls the brake lever, the angular displacement sensor detects the change in the angle of the brake lever and generates an AC voltage signal, which is transmitted to the signal conversion circuit. The conversion circuit converts this signal into a DC current signal, which controls the pressure servo valve to output a braking pressure proportional to the lever rotation angle to achieve emergency braking.

[0070] Step 2: Determine the working logic of the hydraulic solenoid valve:

[0071] The working logic of the hydraulic solenoid valve includes no-stroke logic and working stroke logic.

[0072] The angle signal of the brake lever is converted into a voltage signal to determine the opening logic of the hydraulic solenoid valve. Specifically:

[0073] The logic for controlling the opening of the hydraulic solenoid valve by the output signal of the angular displacement sensor is determined by formula (1).

[0074]

[0075] In the formula, S represents the state where the angular displacement sensor triggers the hydraulic solenoid valve to open; 1 indicates the hydraulic solenoid valve is open, and the hydraulic power source enters the inlet of the pressure servo valve; 0 indicates the hydraulic solenoid valve is not open, and the hydraulic power source does not enter the inlet of the pressure servo valve; R S This refers to the working stroke of the angular displacement sensor; R S0 This is the idle travel of the angular displacement sensor.

[0076] The logic for a defined empty run is 0, and the logic for a defined working run is 1.

[0077] Step 3: Determine the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve:

[0078] The voltage signal output by the angular displacement sensor is processed by a conversion circuit and converted into a brake current signal, which is then output to the pressure servo valve.

[0079] When determining the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve, the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve is determined by formula (2).

[0080]

[0081] In the formula I f It is the current input of the pressure servo valve; V S It is the working stroke voltage of the angular displacement sensor; V S0K1 is the no-travel voltage of the angular displacement sensor; K2 is the conversion coefficient between the output signal of the angular displacement sensor and the input current signal of the pressure servo valve.

[0082] Step 4: Determine the relationship between the input current and output pressure of the pressure servo valve:

[0083] The relationship between the input current and the output pressure of the pressure servo valve is determined by formula (3).

[0084]

[0085] In the formula, P is the output pressure of the pressure servo valve; P0 is the return oil pressure of the brake system; I f0 K1 is the dead zone current of the pressure servo valve; K2 is the current gain coefficient of the pressure servo valve.

[0086] Step 5: Apply the brakes:

[0087] Based on the correspondence between the input current and output pressure of the pressure servo valve determined in step 4, the pressure servo valve outputs braking pressure, which is reflected by the rotation angle of the handle. The pressure sensor receives the signal and connects to the wheel to achieve braking, thus completing the normal braking function of the braking system.

[0088] This completes the entire process of controlling the aircraft's braking system via the brake lever.

Claims

1. An aircraft braking system that controls brake pressure via a brake lever, characterized in that, The system includes a brake handle (9), an angular displacement sensor (10), a signal conversion circuit (11), a hydraulic solenoid valve (4), a pressure servo valve (5), a pressure sensor (6), a wheel speed sensor (7), and wheels (8). The brake handle (9) is mounted on the cockpit control panel, which is directly visible to the pilot. The angular displacement sensor is fixed on the rotating shaft of the brake handle. The sensor detects the angle of rotation of the handle and transmits the detected angle signal to the signal conversion circuit (11). The DC power input interface of the signal conversion circuit is connected to a regulated power supply. The hydraulic solenoid valve (4) and the pressure servo valve (5) are connected to the regulated power supply. The valve is connected to the signal conversion circuit according to the interface definition; the hydraulic inlet of the hydraulic solenoid valve is connected to the hydraulic input source on the machine, and the hydraulic outlet of the hydraulic solenoid valve is connected to the hydraulic inlet of the pressure servo valve (5) to control the oil circuit of the pressure servo valve; the wheel brake device includes a pressure sensor (6), a wheel speed sensor (7) and a wheel (8); the pressure sensor and the wheel speed sensor are respectively installed on both sides of the wheel; the hydraulic outlet of the pressure servo valve is connected to the wheel brake device to output braking pressure to the wheel brake device; the displacement amount of the handle rotation angle is converted into AC voltage and output to the signal conversion circuit through the angular displacement sensor; The signal conversion circuit receives the voltage signal caused by the handle displacement signal through the connector (12); the power module (13) is turned on at the same time, connecting the detection signal generator (14), the rheostat (15) and the conversion module (17); the analog switch (16) receives the voltage signal transmitted by the detection signal generator and makes a judgment, and after forming a feedback loop with the rheostat, it outputs the voltage signal to the conversion module; the conversion module converts the voltage signal into a current signal and outputs it through the connector (12); The signal conversion circuit includes a power conversion circuit, an angular displacement sensor excitation circuit, an effective value conversion circuit, a proportional amplifier circuit, and a pressure-current conversion circuit; wherein: the signal conversion circuit converts the received power into two paths, and one path outputs 28V DC to power the pressure servo valve drive circuit, and the other path outputs +15V and -15V internal drive voltages through the power conversion module (17); The excitation circuit of the angular displacement sensor is powered by the internal drive voltage of the conversion circuit. After being conditioned by the AD598 linear displacement differential transformer signal conditioning chip, it outputs an effective AC voltage of 7Vrms and provides a 2400Hz excitation source for the angular displacement sensor. The effective value conversion circuit collects the output signal of the angular displacement sensor and converts it into a 0-3.75V signal. After being amplified to a 0-8V voltage by the proportional amplifier circuit, the voltage-to-current conversion circuit outputs a 0-40mA current.

2. The aircraft braking system for controlling brake pressure via a brake handle as described in claim 1, characterized in that, The angular displacement sensor (10) includes a rotor, a stator, a primary coil and two secondary coils; the resistance of the primary coil is 45±9Ω, the resistance of the secondary coil is 55±10Ω, and the voltage signal output by the angular displacement sensor (10) is 0~3.75Vrms.

3. The aircraft braking system for controlling brake pressure via a brake handle as described in claim 1, characterized in that, The AC voltage signal command signal of the angular displacement sensor is converted into a DC control current signal of 0-40mA for the pressure servo valve through the signal conversion circuit (11), and the pressure servo valve (5) is controlled to brake.

4. The aircraft braking system for controlling brake pressure via a brake handle as described in claim 1, characterized in that, The control current input range of the pressure servo valve (5) is 0-40mA, and the resistance is 100Ω.

5. A method for controlling brake pressure in an aircraft braking system as described in claim 1, characterized in that, The specific process is as follows: Step 1: Determine the strokes of the angular displacement sensor: The strokes of the angular displacement sensor (10) include the total stroke, the idle stroke, and the working stroke; during braking, the angular displacement sensor receives the continuous change in the angle of the brake handle to determine the total stroke, the idle stroke, and the working stroke of the angular displacement sensor. When the angular displacement sensor (10) is in the no-stroke state, the signal conversion circuit (11) does not output an open signal to the hydraulic solenoid valve (4), the hydraulic source cannot enter the oil inlet of the pressure servo valve, and at the same time the signal conversion circuit only outputs static current to the pressure servo valve (5) and does not output control current. At this time, the braking system does not output braking pressure, and the angular displacement sensor is in the no-stroke state. When the angular displacement sensor is determined to be in its working stroke, the signal conversion circuit (11) outputs control signals to the hydraulic solenoid valve (4) and the brake servo valve. At this time, the hydraulic source enters the oil inlet of the pressure servo valve, and the pressure servo valve (5) outputs a brake pressure proportional to the rotation angle of the handle. The angular displacement sensor is in its working stroke; the brake system completes the normal braking function. The total stroke of the angular displacement sensor is the sum of the idle stroke and the working stroke; Step 2: Determine the working logic of the hydraulic solenoid valve: The working logic of the hydraulic solenoid valve (4) includes no-stroke logic and working stroke logic; The angle signal of the brake handle (9) is converted into a voltage signal to determine the opening logic of the hydraulic solenoid valve; The logic value for a defined empty run is 0, and the logic value for a defined working run is 1. The specific process for determining the working logic of the hydraulic solenoid valve (4) is as follows: The logic for controlling the opening of the hydraulic solenoid valve by the output signal of the angular displacement sensor is determined by formula (1); （1） In the formula, S is the state in which the hydraulic solenoid valve (4) is opened triggered by the angular displacement sensor; 1 is the state in which the hydraulic solenoid valve (4) is open and the hydraulic source enters the oil inlet of the pressure servo valve; 0 is the state in which the hydraulic solenoid valve (4) is not open and the hydraulic source does not enter the oil inlet of the pressure servo valve. This refers to the working stroke of the angular displacement sensor. This is the idle travel of the angular displacement sensor; Step 3: Determine the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve: The voltage signal output by the angular displacement sensor (10) is processed by the conversion circuit and converted into a brake current signal and output to the pressure servo valve (5). When determining the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve, the correspondence between the output voltage signal of the angular displacement sensor and the input current signal of the pressure servo valve is determined by formula (2); （2） In the formula It is the current input of the pressure servo valve; It is the working stroke voltage of the angular displacement sensor; It is the no-travel voltage of the angular displacement sensor; The conversion coefficient between the output signal of the angular displacement sensor and the input current signal of the pressure servo valve; Step 4: Determine the relationship between the input current and output pressure of the pressure servo valve: The relationship between the input current and the output pressure of the pressure servo valve is determined by formula (3). （3） In the formula, P is the output pressure of the pressure servo valve; This refers to the return oil pressure of the braking system. This refers to the dead zone current of the pressure servo valve. This refers to the current gain coefficient of the pressure servo valve. Step 5: Apply the brakes: Based on the correspondence between the input current and output pressure of the pressure servo valve determined in step 4, the pressure servo valve outputs braking pressure, and the braking pressure is reflected by the rotation angle of the handle. The pressure sensor receives the signal and connects to the wheel to realize braking, and the braking system completes the normal braking function. This completes the entire process of controlling the aircraft's braking system via the brake lever.

6. The method for controlling brake pressure via a brake handle as described in claim 5, characterized in that, When the driver uses emergency braking, he pulls the brake handle (9). The angular displacement sensor (10) detects the change in the angle of the brake handle and generates an AC voltage signal, which is transmitted to the signal conversion circuit (11). The conversion circuit converts this signal into a DC current signal and controls the pressure servo valve (5) to output a braking pressure proportional to the rotation angle of the handle to achieve emergency braking.

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